{"id":35312,"date":"2022-09-09T09:43:50","date_gmt":"2022-09-09T04:13:50","guid":{"rendered":"https:\/\/apboardsolutions.guru\/?p=35312"},"modified":"2022-09-09T09:44:09","modified_gmt":"2022-09-09T04:14:09","slug":"ap-inter-2nd-year-chemistry-study-material-chapter-5","status":"publish","type":"post","link":"https:\/\/apboardsolutions.guru\/ap-inter-2nd-year-chemistry-study-material-chapter-5\/","title":{"rendered":"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy"},"content":{"rendered":"<p>Andhra Pradesh BIEAP <a href=\"https:\/\/apboardsolutions.guru\/ap-inter-2nd-year-chemistry-study-material\/\">AP Inter 2nd Year Chemistry Study Material<\/a> 5th Lesson General Principles of Metallurgy Textbook Questions and Answers.<\/p>\n<h2>AP Inter 2nd Year Chemistry Study Material 5th Lesson General Principles of Metallurgy<\/h2>\n<p><span style=\"color: #0000ff;\">Very Short Answer Questions<\/span><\/p>\n<p>Question 1.<br \/>\nWhat is the role of depressant in froth floatation?<br \/>\nAnswer:<br \/>\nBy using depressants in froth floatation process, it is possible to separate a mixture of two sulphide ores.<br \/>\nEg: In the ore containing ZnS and PbS, the depressant used is NaCN. It prevents ZnS from coming to the froth but allows PbS to come with the froth.<\/p>\n<p>Question 2.<br \/>\nBetween C and CO, which is a better reducing agent at 673K.<br \/>\nAnswer:<\/p>\n<ul>\n<li>Out of C and CO, Carbon nonoxide (CO) is a better reducting agent at 673K.<\/li>\n<li>At 983K (or) above coke(C) is better reducing agent.<\/li>\n<li>The above observations are form Ellingham diagram.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 3.<br \/>\nName the common elements present in the anode mud in the eletrolytic refining of copper.<br \/>\nAnswer:<\/p>\n<ul>\n<li>The common elements present in the anode mud in eletrolytic refining of copper are less reactive valuable metals, silver (Ag), gold (Au) and platinum (Pt) etc&#8230;.<\/li>\n<li>These elements donot lose eletrons at anode and collect under the anode as anode mud.<\/li>\n<\/ul>\n<p>Question 4.<br \/>\nState the role of silica in the metallurgy of copper.<br \/>\nAnswer:<br \/>\nThe role of silica in the metallurgy of copper is to \u00e0cts as an acidic flux. Silica reacts with the impurities of iron and form slag.<br \/>\nFeO (Gangue) + SiO<sub>2<\/sub> (flux) \u2192 FeSiO<sub>3<\/sub> (Slag)<\/p>\n<p>Question 5.<br \/>\nExplain \u201cpoling. [A.P. Mar.16, 15]<br \/>\nAnswer:<br \/>\nWhen the metals are having the metal oxides as impurities this method is employed. The impure metal is melted and is then covered by carbon powder. Then it is stirred with green wood poles. The reducing gases formed from the green wood and the carbon, reduce the oxides to the metal.<br \/>\nEg: Cu &amp; Sn metals are refined by this method.<\/p>\n<p>Question 6.<br \/>\nDecribe a method for the refining of nickel.<br \/>\nAnswer:<br \/>\nMond\u2019s process:<\/p>\n<ul>\n<li>In Mond\u2019s process, nickel is heated in a stream of carbon monoxide forming a volatile complex, nickel tetra carbonyl.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22794\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-1.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 1\" width=\"295\" height=\"38\" \/><\/li>\n<li>Nickel tetra carbornyl is strongly heated to decompose and gives the pure Nickel<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22795\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-2.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 2\" width=\"284\" height=\"38\" \/><\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 7.<br \/>\nHow is cast iron different from pig iron ?<br \/>\nAnswer:<\/p>\n<ul>\n<li>Cast iron is formed by melting pig iron with scrap iron and coke in presence of blast of hot air. It contains carbon content 3%(approximately). It is extremely hard and brittle.<\/li>\n<li>Pig iron is formed from blast furnace. It contains carbon 4% (approximately). It contains small quantities of impurities S, P, Si, Mu etc&#8230;.<\/li>\n<\/ul>\n<p>Question 8.<br \/>\nWhat is the difference between a mineral and an ore ?<br \/>\nAnswer:<br \/>\nMinerals : The naturally occuring chemical compounds of metal in the earth\u2019s crust are called minerals.<br \/>\nOre : The mineral from which metal can be extracted economically is called ore.<\/p>\n<p>Question 9.<br \/>\nWhy copper matte is put in silica lined converter ?<br \/>\nAnswer:<br \/>\nCopper matte conains Cu<sub>2<\/sub> sand FeS. In this mixture FeS is gangue. For removing the gangue, silica present in the lining of the Bessemer&#8217;s converter acts as acidic flux and forms slag.<br \/>\n2FeS (gangue) + 3O<sub>2<\/sub> \u2192 2FeO + 2SO<sub>2<\/sub><br \/>\nFeO (gangue) + SiO<sub>2<\/sub> (flux) \u2192 FeSiO<sub>3<\/sub> (Slag)<\/p>\n<p>Question 10.<br \/>\nWhat is the role of cryolite in the metallurgy of aluminium? [T.S. Mar. 16, 15]<br \/>\nAnswer:<br \/>\nBy adding the cryolite to the pure Alumina, the melting point of pure Alumina is lowered (which is very high 2324K) and eletrical conductivity of pure alumina is increased.<\/p>\n<p>Question 11.<br \/>\nHow is leaching carried out in the case of low grade copper ores?<br \/>\nAnswer:<br \/>\nIn case of low grade ores of copper, hydrometallurgy technique is used for extraction. Here leaching process can be done by using acids (or) bacteria, The solution containing Cu<sup>+2<\/sup> is treated with scrap iron (or) H<sub>2<\/sub>.<br \/>\nCu<sup>+2<\/sup><sub>(aq)<\/sub> + H<sub>2(g)<\/sub> \u2192 Cu<sub>(S)<\/sub> + 2H<sup>+<\/sup><sub>(aq)<\/sub><\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 12.<br \/>\nWhy is zinc not extracted from zinc oxide through reduction using CO?.<br \/>\nAnswer:<br \/>\nZinc is not extracted from zinc oxide through reduction by using CO.<br \/>\nExplanation:<br \/>\n2Zn + O<sub>2<\/sub> \u2192 2ZnO, \u2206G\u00b0 = -650 IcI<br \/>\n2C0 + O<sub>2<\/sub> \u2192 2CO, \u2206G\u00b0 = -450 kJ<br \/>\n2ZnO + 2CO \u2192 2Zn, 2CO<sub>2<\/sub>, \u2206G\u00b0 = 200 kJ<br \/>\n\u2206G\u00b0 = Positive indicatis that the reaction is not feasible.<\/p>\n<p>Question 13.<br \/>\nGive the composition of the following alloys. [A.P. &amp; T.S. Mar. 19, 17] [Mar. 14]<br \/>\na) Brass<br \/>\nb) Bronze<br \/>\nc) German Silver<br \/>\nAnswa:<br \/>\na) Composition of Brass : 60 &#8211; 80% Cu, 20 &#8211; 40% Zn .<br \/>\nb) Composition of Bronze : 75 &#8211; 90% Cu, 10 &#8211; 25% Sn<br \/>\nc) Composition of German silver : 50 &#8211; 60% Cu, 10 &#8211; 30% Ni, 20 &#8211; 30% Zn.<\/p>\n<p>Question 14.<br \/>\nExplain the terhts gangue and slag.<br \/>\nAnswer:<br \/>\nGangue : The ore is contaminated with the minerals of earth crust and undesired chemical compounds. These are known as gangue (or) matrix.<br \/>\nSlag: The fused material obtained during the refining (or) smelting of metals by combining the flux with gangue is called slag.<br \/>\nEg : FeO (gangue) + SiO<sub>2<\/sub> (flux) \u2192 FeSiO<sub>3<\/sub> (Slag)<\/p>\n<p>Question 15.<br \/>\nHow is Ag or Au obtained by leaching from the respective ores ?<br \/>\nAnswer:<br \/>\nAg and Au are leached with a dilute solution of NaCN (or) KCN in presence of 02(air). From the leached solution the metal is obtained through displacement by Zinc. .<br \/>\n4M<sub>(s)<\/sub> + 8eN<sup>&#8211;<\/sup><sub>(aq)<\/sub> + 2H<sub>2<\/sub>O<sub>(aq)<\/sub> + O<sub>2(g)<\/sub> \u2192 4[M(CN)<sub>2<\/sub>]<sup>&#8211;<\/sup><sub>(aq)<\/sub> + 4OH<sup>&#8211;<\/sup><sub>(aq)<\/sub><br \/>\n2[M(CN)<sub>2<\/sub> ]<sup>&#8211;<\/sup><sub>(aq)<\/sub> + Zn<sub>(s)<\/sub> \u2192 [Zn(CN)<sub>4<\/sub>]<sup>2-<\/sup><sub>(aq)<\/sub> + 2M<sub>(s)<\/sub><\/p>\n<p>Question 16.<br \/>\nWhat are the limitations of Ellingham diagram ?<br \/>\nAnswer:<br \/>\nLimitations of Ellingham diagram :<\/p>\n<ul>\n<li>Ellingham diagram is based only on the thermodynamic concepts. It does not explain the kinetics of the reduction process. The graph simply indicates whether a reacton is possible or not but not the kinetics of the reaction.<\/li>\n<li>The interpretation of \u2206G\u00b0 is depends on K [ \u2206G\u00b0 = -RTl.nK]<br \/>\nIt is presumed that the reactants and products are in equilibrium. .<br \/>\nM<sub>x<\/sub>O + A<sub>red<\/sub> \u21cc xM + AO<sub>ox<\/sub><br \/>\nThis is not always true because the reactant or product may be solid.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 17.<br \/>\nWrite any two ores with formulae of the following metals :<br \/>\n(a) Aluminium<br \/>\n(b) Zinc<br \/>\n(c) Iron<br \/>\n(d) copper<br \/>\nAnswer:<br \/>\na) Ores of Aluminium : Bauxite &#8211; Al<sub>2<\/sub> O<sub>3<\/sub>. 2H<sub>2<\/sub>O<br \/>\nCryolite &#8211; Na<sub>3<\/sub>AlF<sub>6<\/sub><br \/>\nb) Ores of Zinc : Zinc blende &#8211; Zns<br \/>\nCalamine &#8211; ZnCO<sub>3<\/sub><br \/>\nc) Ores of Iron : Haematite &#8211; Fe<sub>2<\/sub>O<sub>3<\/sub><br \/>\nMagnetite &#8211; Fe<sub>3<\/sub>O<sub>4<\/sub><br \/>\nd) Ores of copper : Copper pyrites &#8211; CuFeS<sub>2<\/sub><br \/>\nCopper glance &#8211; Cu<sub>2<\/sub>S.<\/p>\n<p>Question 18.<br \/>\nWhat is matte ? Give its composition.<br \/>\nAnswer:<br \/>\nDuring the extraction of &#8216;Cu&#8217; from copper pyrites the product of the blast furnace consists mostly of Cu<sub>2<\/sub>S and a little of FeS. This product is known as &#8220;Matte&#8221;. It is collected from the outlet at the bottom of the fumance.<\/p>\n<p>Question 19.<br \/>\nWhat is blister copper ? Why is it so called ? [T.S. Mar. 18]<br \/>\nAnswer:<br \/>\nDuring the extraction of &#8216;Cu&#8217; from copper pyrites when the matte is charged into a Bessemer converter then cuprous oxide combine with cuprous sulphide and forms Cu metal.<br \/>\n2CU<sub>2<\/sub>O + Cu<sub>2<\/sub>S \u2192 6Cu + SO<sub>2<\/sub><br \/>\nThe &#8216;Cu&#8217; meted is cooled.<br \/>\nThe obtained copper metal is impure and is known as &#8220;Blister copper&#8221; (98% pure).<br \/>\nThe solid fied copper has blistered appearance due to evolution of SO<sub>2<\/sub> Hence it is called blister copper.<\/p>\n<p>Question 20.<br \/>\nExplain magnetic separation of impurities from an ore.<br \/>\nAnswer:<br \/>\nElectro-magnetic method : The method is used if the gangue or the ore particles are magnetic in nature. The finely powdered ore is dropped on a belt moving on two strong electromagnetic rollers. The magnetic and the non-magnetic substances form two separate heaps.<\/p>\n<p>For example, let the ore particles be magnetic and then the non-magnetic material will be the gangue. The non-magnetic material forms a heap nearer to the magnetic roller.<br \/>\nEg : Haematite and magnetite hae magnetic ore particles. Cassiterite or Tin stone has Wolframite as magnetic impurity.<\/p>\n<p>Question 21.<br \/>\nWhat is flux ? Give an example.<br \/>\nAnswer:<br \/>\nFlux : An outside substance added to ore to lower its melting point is known as flux.<\/p>\n<ul>\n<li>Flux combines with gangue and forms easily fusible slag.<br \/>\ngangue + flux \u2192 slag<br \/>\nEg: FeO (gangue) + SiO<sub>2<\/sub> (flux) \u2192 FeSiO<sub>3<\/sub> (Slag<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 22.<br \/>\nGive two uses each of the following metals :<br \/>\n(a) Zinc<br \/>\n(b) Copper<br \/>\n(c) Iron<br \/>\n(d) Aluminium<br \/>\nAnswer:<br \/>\na) Uses of Zinc :<\/p>\n<ul>\n<li>Zinc is used in large quantities in batteries<\/li>\n<li>Zinc is used for galvanising iron.<\/li>\n<li>Zinc is used in manufacturing alloys.<br \/>\nEg: Brass, German silver,<\/li>\n<\/ul>\n<p>b) Uses of copper :<\/p>\n<ul>\n<li>Copper is used in manufacturing of water pipes and steam pipes.<\/li>\n<li>Copper is used in making wires used in electrical industry.<\/li>\n<li>Copper is used in manufacturing of alloys.<br \/>\nEg : Brass, Bronze. .<\/li>\n<\/ul>\n<p>c) Uses of Iron:<\/p>\n<ul>\n<li>Cast iron is used in casting stoves, railway si\u00e9epers- gutter pipers, toys etc.<\/li>\n<li>It is used in manufacturing of wrought iron and steel.<\/li>\n<li>Wrought iron is used in making anchors, wires, bolts, chains etc.<\/li>\n<\/ul>\n<p>d) Uses of Aluminium :<\/p>\n<ul>\n<li>Aluminium foils are used as wrappers for chacolates.<\/li>\n<li>Aluminium is fine dust used in paints and lacquers.<\/li>\n<li>Aluminium is used in photo frames.<\/li>\n<li>Aluminium is used in extraction of Cr and Mn from their oxides.<\/li>\n<\/ul>\n<p>Question 23.<br \/>\nBetween C and CO, which is a better reducing agent for ZnO ?.<br \/>\nAnswer:<br \/>\nCase &#8211; I : [Coke as reducing agent]<br \/>\nZnO + C \u2192 Zn + CO, \u2206G\u00b0 become lesser as the T is more then 1120K<br \/>\nCase &#8211; II : [CO as reducing agent]<br \/>\nZnO + CO<sub>2<\/sub> \u2192 Zn + CO, \u2206G\u00b0 becomes lesser when the T is more then 1323K.<\/p>\n<ul>\n<li>The value of \u2206G\u00b0 is negative for a reaction to occur.<\/li>\n<li>In the equation (1) \u2206G\u00b0 becomes negative at low temperature- so equation (1) is feasible i. r. C is a better reducing agent for ZnO.<\/li>\n<\/ul>\n<p>Question 24.<br \/>\nGive the uses of<br \/>\na) Cast iron<br \/>\nb) Wrought iron<br \/>\nc) Nickel steel<br \/>\nd) Stainless steel<br \/>\nAnswer:<br \/>\na) Uses of Cast iron :<\/p>\n<ul>\n<li>Cast iron is used for casting stoves, railway sleepers, gutter pipes, toys etc.<\/li>\n<li>It is used in manufacturing of wrought iron and steel.<\/li>\n<\/ul>\n<p>b) Uses of wrought iron :<\/p>\n<ul>\n<li>Wrought iron is used in making anchors, wires.<\/li>\n<li>Wrought iron is used in making chains and agricultural implements.<\/li>\n<\/ul>\n<p>c) Uses of Nickel steel:<\/p>\n<ul>\n<li>Nickel steel is used for making cables, automobiles and aeroplane parts.<\/li>\n<li>Nickel steel is used for making pendulum, measuring tapes, chrome steel for cutting tools and crashing machines.<\/li>\n<\/ul>\n<p>d) Uses of stainless steel:<\/p>\n<ul>\n<li>Stainless steel is used in manufacturing of cycles, automobiles.<\/li>\n<li>Stainless steel is used in manufacturing of utensils, pens etc.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 25.<br \/>\nHow is aluminium useful in the extraction of chromium and manganese from their oxides ?<br \/>\nAnswer:<\/p>\n<ul>\n<li>\u2019AT&#8217; is used as reducing agent.<\/li>\n<li>4 By Alumino thermite process Cr, Mn are extracted from their oxides.<\/li>\n<li>The reactions are highly exothermic.<br \/>\nCr<sub>2<\/sub>O<sub>3<\/sub> + 2Al \u2192 2Cr + Al<sub>2<\/sub>O<sub>3<\/sub><br \/>\n3Mn<sub>3<\/sub>O<sub>4<\/sub> + 8Al \u2192 4Al<sub>2<\/sub>O<sub>3<\/sub> + 9Mn<\/li>\n<\/ul>\n<p><span style=\"color: #0000ff;\">Short Answer Questions<\/span><\/p>\n<p>Question 1.<br \/>\nCopper can be extracted by hydrometallurgy but not zinc &#8211; explain.<br \/>\nAnswer:<br \/>\nCopper can be extracted by hydromefallurgy but not zinc.<br \/>\nExplanation:<\/p>\n<ul>\n<li>E<sup>0<\/sup> Value of Zn<sup>+2<\/sup>\/Zn = -0.762V is less than that of E<sup>0<\/sup> value of Cu<sup>+2<\/sup>\/Cu = 0.337V .<\/li>\n<li>From the above data zinc is a stronger reducing agent and can easily displace the Cu<sup>+2<\/sup> ions present in the complex.<br \/>\n[Cu(CN)<sub>2<\/sub>] + Zn (Soluble complex \u2192 [Zn(CN)<sub>2<\/sub>] + Cu (Precipitate)<\/li>\n<li>Zinc can be isolated by hydrometallurgy only when stronger reducing agents than zinc are present.<\/li>\n<li>So zinc cannot be extracted by hydrometallurgy.<\/li>\n<\/ul>\n<p>Question 2.<br \/>\nWhy is the extraction of copper form pyrites more difficult then that from its oxide ore through reduction?<br \/>\nAnswer:<br \/>\nThe extraction of copper from pyrites is more difficult than that from its oxide ore through reduction.<br \/>\nExplanation:<br \/>\nPyrites (Cu<sub>2<\/sub>S) Cannot be reduced by carbon(or) hydrogent because the standard free energy of formation (\u2206G\u00b0) of Cu<sub>2<\/sub>S is greater then those of CS<sub>2<\/sub> and H<sub>2<\/sub>S.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22796\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-3.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 3\" width=\"559\" height=\"62\" \/><br \/>\nThe \u2206G\u00b0 of copper oxide is less than that of CO<sub>2<\/sub>.<br \/>\n\u2234 The sulphide ore is first converted to oxide by roasting and then reduced.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22797\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-4.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 4\" width=\"358\" height=\"84\" \/><\/p>\n<p>Question 3.<br \/>\nExplain zone refining.<br \/>\nAnswer:<br \/>\nZone refining:<\/p>\n<ul>\n<li>Zone refining is based on the principle that the impurities are more soluble in the melt than in the solid state of the metal.<\/li>\n<li>A circular mobile heater is fixed at one end of a rod of impure metal.<\/li>\n<li>The molten zone moves along with the heater moves forward the pure metal crystallises out of the melt and the impurities pass into the adjacent molten zone.<\/li>\n<li>The above process is repeated several times and the heater is moved in the same direction form one end to the other end. At one end impurities get concentrated. This end is cut off.<\/li>\n<li>This method is very useful for producing semiconductor grade metals of very high purity. Eg : Ge, Si, B, Ga etc&#8230;<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22798\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-5.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 5\" width=\"428\" height=\"165\" \/><\/li>\n<\/ul>\n<p>Question 4.<br \/>\nWrite down the chemical reactions taking place in the extraction of zinc from zinc blende.<br \/>\nAnswer:<br \/>\nIn the extraction of zinc from zinc blende the following chemical reactions taking place.<br \/>\ni) Roasting : The process of strong heating the zinc blende in presence of air is roasting.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22799\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-6.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 6\" width=\"387\" height=\"37\" \/><br \/>\nii) Reduction : Zinc oxide obtained by roasting undergo reduction with coke.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22800\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-7.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 7\" width=\"209\" height=\"36\" \/><\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 5.<br \/>\nWrite down the chemical reactions taking place in different zones in the blast furnace during the extraction of iron.<br \/>\nAnswer:<br \/>\nThe chemical reactions taking place in different zones in the blast furnace during the extraction of iron are<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22801\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-8.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 8\" width=\"323\" height=\"309\" \/><\/p>\n<p>Question 6.<br \/>\nHow is alumina separated from silica in the bauxite ore associated with silica ? Give equations.<br \/>\nAnswer:<br \/>\nSerpeck&#8217;s process is used for the purification of white Bauxite i.e., Bauxite containing silica as impurity.<br \/>\nIn this process bauxite is mixed with coke and is then heated to 2075K in a current of nitrogen. Silica is reduced to silicon and escapes as a vapour.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22802\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-9.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 9\" width=\"423\" height=\"62\" \/><br \/>\nAluminium nitride formed in the above step is hydrolysed to form aluminium hydroxide.<br \/>\nAlN + 3H<sub>2<\/sub>O \u2192 AZ(OH)<sub>3<\/sub> \u2193 + NH<sub>3<\/sub> \u2191<br \/>\nAl(OH)<sub>3<\/sub> PPt is washed, dried and then ignited to from purified bauxite.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22803\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-10.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 10\" width=\"302\" height=\"41\" \/><\/p>\n<p>Question 7.<br \/>\nGiving examples to differentiate roasting and calcination. [T.S. Mar. 19, 18, 16, 15; A.P. Mar. 16, 15]<br \/>\nAnswer:<br \/>\nRoasting: Removal of the volatile components of a mineral by heating mineral either alone (or) mixed with some other substances to a high temperature in the presence of air is called Roasting.<\/p>\n<ul>\n<li>It is applied to the sulphide ores.<\/li>\n<li>SO<sub>2<\/sub> gas is producted along with metal oxide.<br \/>\nEg : 2ZnS + 3O<sub>2 <\/sub><img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> 2ZnO + 2SO<sub>2<\/sub> \u2191<\/li>\n<\/ul>\n<p>Calcination: Removal of the volatile components of a mineral by heating in the absence of air is called calcination.<\/p>\n<ul>\n<li>\u00a0It is applied to carbonates and bicarbonates.<\/li>\n<li>CO<sub>2<\/sub> gas is produced along with metal oxide.<br \/>\nEg: CaCO<sub>3 <\/sub><img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> CaO + CO<sub>2<\/sub><br \/>\nZnCO<sub>3 <\/sub><img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> ZnO + CO<sub>2<\/sub><\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 8.<br \/>\nThe Value of \u2206G\u00b0 for the formation of Cr<sub>2<\/sub>O<sub>3<\/sub> is &#8211; 540kJ mol<sup>-1<\/sup> and that of Al<sub>2<\/sub>O<sub>3<\/sub> is &#8211; 827kJ mol<sup>-1<\/sup>. Is the reduction of Cr<sub>2<\/sub>O<sub>3<\/sub> Possible with Al?<br \/>\nAnswer:<br \/>\nFrom the given data the following are the thermo chemical equations<br \/>\n\\(\\frac{4}{3}\\) Cr<sub>(s)<\/sub> + O<sub>2(g)<\/sub> \u2192 \\(\\frac{2}{3}\\) Cr<sub>2<\/sub>O<sub>2(s)<\/sub>, \u2206G\u00b0 &#8211; 540 KJ &#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.. (1)<br \/>\n\\(\\frac{4}{3}\\) Al<sub>(s)<\/sub> + O<sub>2(g)<\/sub> \u2192 \\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3(s)<\/sub>, \u2206G\u00b0 &#8211; 827 KJ &#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.. (2)<br \/>\nEquation (1) &#8211; Equation (2)<br \/>\n\\(\\frac{2}{3}\\) Cr<sub>2<\/sub>O<sub>3(s)<\/sub> + \\(\\frac{4}{3}\\) Al<sub>(s)<\/sub> \u2192 \\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3(s)<\/sub> + \\(\\frac{4}{3}\\) Cr<sub>(s)<\/sub>, \u2206G\u00b0 &#8211; 287 KJ<br \/>\n\u2206G\u00b0 = -ve, So the reaction is feasible<br \/>\nHence the reduction of Cr<sub>2<\/sub>O<sub>3<\/sub> is possible with &#8216;Al&#8217;.<\/p>\n<p>Question 9.<br \/>\nWhat is the role of graphite rod in the electrometallurgy of aluminium ? [A.P. Mar. 16]<br \/>\nAnswer:<\/p>\n<ul>\n<li>In the electrolytic reduction of alumina b<sub>y<\/sub> Hall &#8211; Heroult process graphite rod acts as anode.<\/li>\n<li>At anode, O<sub>2<\/sub> gas is liberated which reacts with the carbon of anode to form CO<sub>2<\/sub> gas. So these graphite rods are consumed slowly and need to be replaced from time to time.<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub> \u21cc 2Al<sup>+3<\/sup> + 3O<sup>-2<\/sup><br \/>\nCathode : Al<sup>+3<\/sup> + 3e<sup>&#8211;<\/sup> \u2192 Al<br \/>\nAnode : 3O<sup>-2<\/sup> \u2192 3[O] + 6e<sup>&#8211;<\/sup><br \/>\nC<sub>(s)<\/sub> + O<sub>2(g)<\/sub> \u2192 CO<sub>2(g)<\/sub><\/li>\n<\/ul>\n<p>Question 10.<br \/>\nOutline the principles of refining of metals by the following methods.<br \/>\n(a) Zone refining<br \/>\n(b) Electrolytic refining<br \/>\n(c) Poling<br \/>\n(d) Vapour phase refining.<br \/>\nAnswer:<br \/>\na) Zone refining :<\/p>\n<ul>\n<li>Zone refining is based on the principle that the impurities are more soluble in the melt than in the solid state of the metal. .<\/li>\n<li>A circular mobile heater is fixed at one end of a rod of impure metal.<\/li>\n<li>The molten zone moves along with the heater moves forward the pure metal crystallises out of the melt and the impurities pass into the adjacent molten zone.<\/li>\n<li>The above process is repeated several times and the heater is moved in the same direction form one end to the other end. At one end impurities get concentrated. This end is cut off.<\/li>\n<li>This method is very useful for producing semiconductor grade metals of very high purity.<br \/>\nEg : Ge, Si, B, Ga etc..<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22805\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-12.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 12\" width=\"425\" height=\"176\" \/><\/li>\n<\/ul>\n<p>b) Electrolytic refining : This process is used for less reactive metals like Cu, Ag, AZ, Au etc.<\/p>\n<ul>\n<li>In this process anode is made by impure metal and a thin strip of pure metal acts as cathode. .<\/li>\n<li>On electrolysis metal dissolves from anode and pure metal gets deposited at cathode.<br \/>\nM \u2192 M<sup>n+<\/sup> + ne<sup>&#8211;<\/sup><br \/>\nImpure<br \/>\nM<sup>n+<\/sup> + ne<sup>&#8211;<\/sup> \u2192 M (Cathode) Pure metal<br \/>\nImpurities settle down below anode in the form of anode mud.<\/li>\n<\/ul>\n<p>c) Poling : When the metals are having the metal oxides as impurities this method is employed. The impure metal is melted and is then covered by carbon powder. Then it is stirred with green wood poles. The reducing gases formed from the green wood and the carbon, reduce the oxides to the metal.<br \/>\nEg : Cu &amp; Sh metals are refined by this method.<\/p>\n<p>d) Vapour phase refining: In this method the metal is converted into its volatile compound and collected. It is then decomposed to give pure metal. .<\/p>\n<ol>\n<li>The metal should form a volatile compound with an available reagent.<\/li>\n<li>The volatile compound should be easily decomposable. So the the recovery is easy.<br \/>\nE.g : Mond&#8217;s process :<\/li>\n<li>In Mond&#8217;s process, nickel is heated in a stream of carbon monoxide forming a volatile complex, nickel tetra carbonyl.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22806\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-13.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 13\" width=\"298\" height=\"42\" \/><\/li>\n<li>Nickel tetra carbomyl is strongly heated to decompose and gives the pure Nickel<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22807\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-14.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 14\" width=\"285\" height=\"36\" \/><\/li>\n<\/ol>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 11.<br \/>\nPredict the conditions under which Al might be expected to reduce MgO.<br \/>\nAnswer:<br \/>\nThe Equations for the formation of two oxides are<br \/>\n\\(\\frac{4}{3}\\)Al<sub>(S)<\/sub> + O<sub>2(g)<\/sub> \u2192 2Mg<sub>(S)<\/sub> + \\(\\frac{2}{3}\\) O<sub>2(g)<\/sub> \\(\\frac{4}{3}\\) 2MgO<sub>(S)<\/sub><br \/>\nFrom the Ellingham diagram the two curves of these oxides formation intersect each otherat a certain point. The corresponding value of \u2206G\u00b0 becomes zero for the reduction of MgO by aluminium metal,<br \/>\n2MgO<sub>(S)<\/sub> + \\(\\frac{4}{3}\\) Al<sub>(S)<\/sub> \u21cc 2Mg<sub>(S)<\/sub> + \\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3(S)<\/sub><\/p>\n<ul>\n<li>From the above information the reduction of MgO by Al metal cannot occur below this temperature (1665 K) instead, Mg can reduce\u00a0 Al<sub>2<\/sub>O<sub>3<\/sub> to Al below 1665 K.<\/li>\n<li>Al-Metal can reduce MgO to Mg above 1665K because \u2206G\u00b0 for Al<sub>2<\/sub>O<sub>3<\/sub> is less compared to that of MgO.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22808\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-15.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 15\" width=\"391\" height=\"38\" \/><\/li>\n<\/ul>\n<p>Question 12.<br \/>\nExplain the purification of sulphide ore by froth floatation method. [A.P. Mar.&#8217;19, 17, 15; T.S. Mar. 15]<br \/>\nAnswer:<br \/>\nFroth floatation method :<br \/>\nThis method is used to concentrate sulphide ores.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22809\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-16.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 16\" width=\"304\" height=\"306\" \/><\/p>\n<ul>\n<li>In this process a suspension of the powdered ore is made with water.<\/li>\n<li>A rotating paddle is used to agitate the suspension and air is blown into the suspension in presence of an oil.<\/li>\n<li>Froth is formed as a result of blown of air, which carries the mineral particles.<\/li>\n<li>To the above slurry froth collectors and stabilizers are added.<\/li>\n<li>Collectors like pine oil enhance non-wettability of the mineral particles.<\/li>\n<li>Froth stabilizers like cresol stabilize the froth.<\/li>\n<li>The mineral particles wet by oil and gangue particles wet by water.<\/li>\n<li>The broth is light and is skimmed off. The ore particles are then obtained from the froth. By using depressants in froth floatation process, it is possible to separate a mixture of two suplhide ores.<br \/>\nEg : In the ore containing ZnS and PbS, the depressant used is NaCN. It prevents ZnS from coming to the froth but allows PbS to come with the froth.<\/li>\n<\/ul>\n<p>Question 13.<br \/>\nExplain the process of leaching of alumina from bauxite. [T.S. Mar. 17]<br \/>\nAnswer:<br \/>\nThe principal ore of aluminium, bauxite, usually contains SiO<sub>2<\/sub>, iron oxides and titanium oxide (TiO<sub>2<\/sub>) as impurities, concentration is carried out by digesting the powdered ore with a concentrated solution of NaOH at 473 &#8211; 523 K and 35 &#8211; 36 bar pressure. The way. Al<sub>2<\/sub>O<sub>3<\/sub> is leached out as sodium aluminate (and SiO<sub>2<\/sub> too as sodium silicate) leaving the other impurities behind :<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub> (S) + 2NaOH(aq) + 3H<sub>2<\/sub>O(l) \u2192 2 Na[Al(OH)<sub>4<\/sub>](aq)<br \/>\nThe aluminate is alkaline in nature and is neutralised by passing CO<sub>2<\/sub> gas and hydrated Al<sub>2<\/sub>O<sub>3<\/sub> is precipitated. At this stage, the solution is seeded with freshly prepared samples of hydrated Al<sub>2<\/sub>O<sub>3<\/sub> which induces the precipitation of Al<sub>2<\/sub>O<sub>3<\/sub> xH<sub>2<\/sub>O<br \/>\n2 Na[Al(OH)<sub>4<\/sub>](aq) + CO<sub>2<\/sub>(g) \u2192 Al<sub>2<\/sub>O<sub>3<\/sub> xH<sub>2<\/sub>O(s) + 2NaHCO<sub>3<\/sub>(aq)<br \/>\nThe sodium silicate remains in the solution and the insoluble hydrated alumina is filtered, dried and heated to give pure Al<sub>2<\/sub>O<sub>3<\/sub>:<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22810\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-17.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 17\" width=\"374\" height=\"41\" \/><\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 14.<br \/>\nWhat is Ellingham diagram ? What information can be known from this in the reduction of oxides ?<br \/>\nAnswer:<br \/>\nThe graphical representation of Gibbs energy which provides a sound basis for considering the choice of reducing agent in the reduction of oxides. This graphical representation is known as Ellingham diagram.<\/p>\n<ul>\n<li>This diagram helps us in predicting the feasibility of thermal reduction of an ore.<\/li>\n<li>The Criterion of feasibility of a reaction is that at a given temperature, Gibbs energy of the reaction must be negative.<\/li>\n<li>\u00a0Ellingham diagram normally consists plots of \u2206G\u00b0 vs T for formation of oxides of elements.<\/li>\n<li>The graph indicates whether a reaction is possible or not, i.e., the tendency of reduction with a reducing agent is indicated with a reducing agent is indicated.<\/li>\n<li>The reducing agent forms its oxide when the metal oxide is reduced. The role of reducing agent is to make the sum of \u2206G\u00b0 values of the two reactions negative.<\/li>\n<li>Out of C and CO, Carbon monoxide (CO) is a better reducting agent at 673K.<\/li>\n<li>At 983K (or) above coke(C) is better reducing agent.<\/li>\n<li>The above observations are form Ellingham diagram.<br \/>\nZinc is not extracted from zinc oxide through reduction by using CO.<\/li>\n<\/ul>\n<p>Explanation :<\/p>\n<ul>\n<li>2Zn + O<sub>2<\/sub> \u2192 2ZnO, \u2206G\u00b0 =-650 kJ<\/li>\n<li>2CO + O<sub>2<\/sub> \u2192 2CO<sub>2<\/sub>, \u2206G\u00b0 = -450 kJ<\/li>\n<li>2ZnO + 2CO \u2192 2Zn, 2CO<sub>2<\/sub>, \u2206G\u00b0 = 200 kJ<br \/>\n\u2206G\u00b0 = Positive indicatis that the reaction is not feasible.<br \/>\nThe above fact is explained on the basis of Ellingham diagram.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22811\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-18.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 18\" width=\"546\" height=\"495\" \/><\/li>\n<\/ul>\n<p>Question 15.<br \/>\nHow is copper extracted from copper pyrites?<br \/>\nAnswer:<br \/>\nExtraction of copper from copper pyrites :<br \/>\nCopper pyrite is the main source of copper metal. Various steps involved in the extraction of copper discussed below.<br \/>\nStep &#8211; I:<br \/>\nConcentration of ore by froth floatation process :<br \/>\nThe ore is first crushed in ball mills. The finely divided ore is suspended in water. A little pine oil is added and the mixture is vigorously agitated by a current of air. The froth formed carries the ore particles almost completely. The gangue sinks to the bottom of the tank. The froth is separated and about 95% concentrated ore is obtained.<\/p>\n<p>Step -II:<br \/>\nRoasting : To remove the volatile impurities like As (or) Sb, the ore is roasted in a free supply of air. A mixture of sulphides of copper and iron are obtained and these are partially oxidised to respective oxides.<br \/>\nCu<sub>2<\/sub>S. Fe<sub>2<\/sub>S<sub>3<\/sub> + O<sub>2<\/sub> \u2192 Cu2S + 2FeS + SO<sub>2<\/sub><br \/>\n2Cu<sub>2<\/sub>S + 3O<sub>2<\/sub> \u2192 2Cu<sub>2<\/sub>O + 2SO<sub>2<\/sub><br \/>\n2FeS + 3O<sub>2<\/sub> \u2192 2FeO + 2SO<sub>2<\/sub><\/p>\n<p>Step -III:<br \/>\nThe roasted ore is mixed with a little coke and sand (Silica) and smelted in a blast furnace and fused. A blast of air, necessary for the combustion of coke, is blown through the tuyeres present at the base of the furnace. The oxidation of the sulphides of copper and iron will be completed further. A slag of iron silicate is formed according to the reactions given below :<br \/>\n2FeS + 3O<sub>2<\/sub> \u2192 2FeO + 2SO<sub>2<\/sub><br \/>\nFeO + SiO<sub>2<\/sub> \u2192 Fe SiO<sub>3<\/sub> Ferrous Silicate (Slag)<br \/>\nCu<sub>2<\/sub>O + FeS \u2192 Cu<sub>2<\/sub>S + FeO<\/p>\n<p>Step -IV : After smelting the copper ore in blast furnace, the product of the blast furnace consists mostly of Cu<sub>2<\/sub>S and a little of ferrous sulphide. This product is known as &#8220;Matte.&#8221; It is collected from the outlet at the bottom of the furnace. After then the following processes are carried out for getting the pure copper.<\/p>\n<p>Bessemerization : The matte is charged into a Bessemer converter. A bessemer converter is a pear-shaped furnace. It is made of steel plates. The furnace is given a basic lining with lime or magnesium oxide (obtained from dolomite or magnesite). The converter is held in position by trunnions and can be tilted in any position. A hot blast of air and sand is blown through the tuyeres present near the bottom. Molten metal, the product in the furnace, collects at the bottom of the converter.<\/p>\n<p>Reactions that took place in blast furnace go to completion. Almost all of iron is eliminated as a slag. Cuprous oxide combines with cuprous sulphide and forms Cu metal.<br \/>\n2Cu<sub>2<\/sub>O + Cu<sub>2<\/sub>S \u2192 6Cu + SO<sub>2<\/sub><br \/>\nThe molten metal is cooled in sand moulds. S02 escapes. The impure copper metal is known as &#8220;Blister copper&#8221; and is about 98% pure.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22812\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-19.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 19\" width=\"286\" height=\"339\" \/><br \/>\nStep -V:<br \/>\nRefining : The Blister copper is purified by electrolysis. The impure copper metal is made into plates. They are suspended into lead &#8211; lined tanks containing Copper (II) Sulphate solution. Thin plates of pure copper serve as cathode. The cathode plates are coated with graphite. On electrolysis, pure copper is deposited at the cathode. The copper obtained is almost 100% pure Cu.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 16.<br \/>\nExplain the extraction of Zinc form Zinc blende.<br \/>\nAnswer:<br \/>\n&#8220;Zinc blende (ZnS)&#8221; is an important source for &#8216;Zn&#8217; metal.<br \/>\nExtraction of Zinc : Zinc blende ore is treated in the following stages.<br \/>\ni) Crushing : The ore is crushed to a fine powder in ball mills.<\/p>\n<p>ii) Concentration of the ore : The ore is concentrated first by gravity process. The crushed ore is washed with a stream of water on a Wilfley&#8217;s table. The tables have a corrugated top and are under a rocking motion. Due to this motion, the lighter gangue particles are washed away by the steam. The heavier ore particles settle to the bottom of the table.<\/p>\n<p>The partially concentrated ore is further concentrated by froth floatation process. The ore particles go with the froth.<\/p>\n<p>The concentrated ore is subjected further to electromagnetic separation, if iron oxide is present in the gangue. Iron oxide is magnetic and so forms a heap nearer to the magnetic pole.<\/p>\n<p>iii) Roasting: The concentrated ore thus obtained is roasted in rotary shelf burner which is provided with horizontal shelves and raking arms. The ore is added at the top and zinc oxide is collected from the bottom. The following reactions take place.<br \/>\n2ZnS + 3O<sub>2<\/sub> \u2192 2ZnO + 2SO<sub>2<\/sub><br \/>\nZnS + 2O<sub>2<\/sub> \u2192 ZnSO<sub>4<\/sub><br \/>\n2ZnSO<sub>4<\/sub> \u2192 2ZnO + 2SO<sub>2<\/sub> + O<sub>2<\/sub>.<br \/>\niv) Reduction : Three methods are in practice for the reduction of the oxide to the metal., The most commonly used method is the Belgian process. In this process the roasted ore is mixed with coal or coke intimately and is taken in fireclay or earthem ware retorts. The retorts are made of fireclay which are bottle shaped tubes. These are closed at one end. The other end is connected to air cooled earthem ware condenser. A large number of retorts are placed in tiers in a large furnace and heated in 1100\u00b0C by burning the gas. &#8216;Prolongs&#8217; made of sheet iron are attached to the condensers. The metal condenses in these earthem ware condensers and the prolongs. The metal powder collected is mixed with some zinc oxide and is known as &#8220;zinc dust&#8221;. Some of the zinc metal is collected in the fused state. This is solidified in moulds. This metal is called &#8220;zinc spelter&#8221;.<br \/>\nZnO + C \u2192 Zn + CO<br \/>\nZnO + CO \u2192 Zn + CO<sub>2<\/sub><br \/>\nElectrolytic refining : Very pure zinc is obtained by electrolysis. The electrolyte is zinc sulphate solution containing a little H<sub>2<\/sub>SO<sub>4<\/sub>. Impure zinc is made the anode and the pure zinc plates are made the cathode.<\/p>\n<p>Question 17.<br \/>\nExplain smelting process in the extraction of copper.<br \/>\nAnswer:<br \/>\nThe roasted ore is mixed with a little coke and sand (Silica) and smelted in a blast furnace and fused. A blast of air, necessary for the combustion of coke, is blown through the tuyeres present at the base of the furnace. The oxidation of the sulphides of copper and iron will be completed further. A slag of iron silicate is formed according to the reactions given below :<br \/>\n2FeS + 3O<sub>2<\/sub> \u2192 2FeO + 2SO<sub>2<\/sub><br \/>\nFeO + SiO<sub>2<\/sub> \u2192 Fe SiO<sub>3<\/sub><br \/>\nFerrous Silicate (Slag)<br \/>\nCu<sub>2<\/sub>O + FeS \u2192 Cu<sub>2<\/sub>S + FeO<\/p>\n<p>Question 18.<br \/>\nExplain electrometallurgy with an example.<br \/>\nAnswer:<br \/>\nElectro metallurgy : Metallurgy involving the use of electric arc furnaces, electrolysis and other electrical operations is called electrometallurgy.<br \/>\nIn the reduction of a molten metal salt, electrolysis is used. These methods are based on electro chemical principles.<br \/>\nThese are expained by the equation<br \/>\n\u2206G\u00b0 = -n FE\u00b0<br \/>\nn = no. of electrons<br \/>\nE\u00b0 = Electrode potential.<br \/>\nElectrolytic Reduction of Alumina : Pure Alumina (Al<sub>2<\/sub>O<sub>3<\/sub>) is a bad conductor of electricity and it has high melting point (2050\u00b0C). So it cannot be electrolysed. Alumina is electrolysed by dissolving in fused cryolite to increase the conductivity and small amount of Fluorspar is added to reduce its melting point. Thus the electrolyte is a fused mixture of Alumina, Cryolite and Fluorspar.<br \/>\nElectrolysis is carried out in an iron tank lined inside with graphite (carbon) which functions as cathode. A number of carbon rods (or) copper rods suspended in the electrolyte functions as Anode.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22813\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-20.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 20\" width=\"417\" height=\"298\" \/><br \/>\nAn electric current of 100 amperes at 6 to 7 volts is passed through the electrolyte. Heat produced by the current keeps the mass in fused state at 1175 to 1225K. The following reactions take place in the electrolytic cell under these conditions.<br \/>\nNa<sub>3<\/sub>AlF<sub>6<\/sub> \u2192 3NaF + AlF<sub>3<\/sub><br \/>\nCryolite<br \/>\n4AlF<sub>3<\/sub> \u2192 4Al<sup>3+<\/sup> + 12F<sup>&#8211;<\/sup><br \/>\nAt cathode : 4Al<sup>3+<\/sup> + 12e<sup>&#8211;<\/sup> \u2192 4Al<br \/>\nAt anode : 12F<sup>&#8211;<\/sup> \u2192 6F<sub>2<\/sub> + 12e<sup>&#8211;<\/sup><br \/>\nF<sub>2<\/sub> formed at the anode reacts with alumina and forms Aluminium fluoride.<br \/>\n2Al<sub>2<\/sub>O<sub>3<\/sub> + 6F<sub>2<\/sub> \u2192 4AlF<sub>3<\/sub> + 3O<sub>2<\/sub><br \/>\nAluminium, produced at the cathode, sinks to the bottom of the cell. It is removed from time to time through topping hole.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 19.<br \/>\nExplain briefly the extraction of aluminium from bauxite.<br \/>\nAnswer:<br \/>\nExtraction of Aluminium from Bauxite:<br \/>\nFor the purpose of extraction of Al, Bauxite is the best source.<br \/>\npurification of Bauxite : Bauxite containing Fe<sub>2<\/sub>O<sub>3<\/sub> as impurity is known as red Bauxite.<br \/>\nBauxite containing SiO<sub>2<\/sub> as impurity is known as white Bauxite and can be purified by &#8220;Serpeck&#8217;s Process&#8221;. Red Bauxite is purified by Bayer&#8217;s process and Hall&#8217;s process.<br \/>\nBayer&#8217;s Process : Red bauxite, is roasted and digested in concentrated NaOH at 423 K. Bauxite dissolves in NaOH to form sodium meta aluminate while impurity Fe<sub>2<\/sub>O<sub>3<\/sub> does not dissolve which can be removed by filtration.<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub>.2H<sub>2<\/sub>O + 2NaOH \u2192 2NaAlO<sub>2<\/sub> + 3H<sub>2<\/sub>O<br \/>\nThe solution which contains sodium meta aluminate is diluted and crystals of AZ(OH)3, are added which serves as seeding orgent. Sodium meta aluminate undergoes hydrolysis to precipitate Al(OH)<sub>3<\/sub>.<br \/>\n2NaAlO<sub>2<\/sub> + 4H<sub>2<\/sub>O \u2192 2NaOH + 2Al(OH)<sub>3<\/sub> \u2193<br \/>\nAl(OH)<sub>3<\/sub> is filtered and ignited at 1200\u00b0C to get anhydrous alumina.<br \/>\n2Al(OH)<sub>3<\/sub> <img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> Al<sub>2<\/sub>O<sub>3<\/sub> + 3H<sub>2<\/sub>O<br \/>\nHalls&#8217; Process: Red Bauxite is fused with sodium carbonate to form sodium meta aluminate which is extracted with water. The impurity Fe<sub>2<\/sub>O<sub>3<\/sub> is filtered out.<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub> + Na<sub>2<\/sub>CO<sub>3<\/sub> \u2192 2NaAlO<sub>2<\/sub> + CO<sub>2<\/sub><br \/>\nInto the solution of sodium meta aluminate, CO<sub>2<\/sub> gas is passed to precipitate Al(OH)<sub>3<\/sub>.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22819\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-26.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 26\" width=\"457\" height=\"41\" \/><br \/>\nThe precipitated Al(OH)<sub>3<\/sub> is ignited at 1200\u00b0C to get anhydrous alumina.<br \/>\n2Al(OH)<sub>3<\/sub> \u2192 Al<sub>2<\/sub>O<sub>3<\/sub> + 3H<sub>2<\/sub>O<br \/>\nSerpeck&#8217;s Process: Powdered bauxite is mixed with coke and heated to 2075 K in a current of nitrogen gas. Aluminium Nitride is formed while Si02 is reduced to SiO<sub>2<\/sub> which escapes out.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22820\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-27.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 27\" width=\"347\" height=\"72\" \/><br \/>\nAluminium nitride is hydrolysed to get aluminium hydroxide which on ignition gives anhydrous alumina.<br \/>\nAlN + 3H<sub>2<\/sub>O \u2192 Al(OH)<sub>3<\/sub> \u2193 + NH<sub>3<\/sub> \u2191<br \/>\n2Al(OH)<sub>3<\/sub> <img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> 3 Al<sub>2<\/sub>O<sub>3<\/sub> + 3H<sub>2<\/sub>O<\/p>\n<p>Electrolytic Reduction of Alumina : Pure Alumina (Al<sub>2<\/sub>O<sub>3<\/sub>) is a bad conductor of electricity and it has high melting point (2050\u00b0C). So it cannot be electrolysed. Alumina is electrolysed by dissolving in fused cryolite to increase the conductivity and small amount of Fluorspar is added to reduce its melt\u00acing point. Thus the electrolyte is a fused mixture of Alumina, Cryolite and Fluorspar.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22821\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-28.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 28\" width=\"442\" height=\"329\" \/><br \/>\nElectrolysis is carried out in an iron tank lined inside with graphite (carbon) which functions as cathode. A number of carbon rods (or) copper rods suspended in the electrolyte functions as Anode.<br \/>\nNa<sub>3<\/sub>AlF<sub>6<\/sub> \u2192 3NaF + AlF<sub>3<\/sub><br \/>\nCryolite<br \/>\n4AlF<sub>3<\/sub> \u2192 4Al<sup>3+<\/sup> + 12F<sup>&#8211;<\/sup><br \/>\nAt cathode : 4Al<sup>3+<\/sup> + 12e<sup>&#8211;<\/sup> \u2192 4Al<br \/>\nAt anode : 12F<sup>&#8211;<\/sup> \u2192 6F<sub>2<\/sub> + 12e<sup>&#8211;<\/sup><br \/>\nF<sub>2<\/sub> formed at the anode reacts with alumina and forms Aluminium fluoride.<br \/>\n2Al<sub>2<\/sub>O<sub>3<\/sub> + 6F<sub>2<\/sub> \u2192 4AlF<sub>3<\/sub> + 3O<sub>2<\/sub><br \/>\nAluminium, produced at the cathode, sinks to the bottom of the cell. It is removed from time to time through topping hole.<\/p>\n<p>Purification of Aluminium : (Hoope&#8217;s Process)<br \/>\nThe impurities present are Si, Cu, Mn etc.,<br \/>\nThe electrolytic cell used for refining of aluminium consists of iron tank lined inside with carbon. This acts as anode. The tank contains three layers of fused masses. The bottom layer contains impure aluminium. Middle layer contains mixture of AlF<sub>3<\/sub>, NaF and BaF<sub>2<\/sub> saturated with Al<sub>2<\/sub>O<sub>3<\/sub>. Top layer contains pure aluminium and graphite rods kept in it act as cathode.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22822\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-29.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 29\" width=\"515\" height=\"285\" \/><br \/>\nOn passing current aluminium ions from the middle layer are discharged at the cathode as pure aluminium. Equivalent amount of aluminium from the bottom layer passes into middle layer.<\/p>\n<p><span style=\"color: #0000ff;\">Long Answer Questions<\/span><\/p>\n<p>Question 1.<br \/>\nThe choice of a reducing agent in a particular case depends on thermo-dynamic factor, \u2022lain with two examples.<br \/>\nAnswer:<br \/>\nThe choice of a reducing agent in a particular case depends on thermodynamic factor. This fact can be explained by considering the following examples.<\/p>\n<ul>\n<li>Out of C and CO, Carbon nonoxide (CO) is a better reducting agent at 673K.<\/li>\n<li>At 983K (or) above coke(C) is better reducing agent.<\/li>\n<li>The above observations are form Ellingham diagram.<\/li>\n<li>Zinc is not extracted from zinc oxide through reduction using CO.<\/li>\n<\/ul>\n<p>Explanation :<br \/>\n2Zn + O<sub>2<\/sub> \u2192 2ZnO, \u2206G\u00b0 = -650 kJ<br \/>\n2CO + O<sub>2<\/sub> \u2192 2CO<sub>2<\/sub>, \u2206G\u00b0 = -450 kJ<br \/>\n2ZnO + 2CO \u2192 2Zn + 2CO<sub>2<\/sub>, \u2206G\u00b0 = 200 kJ<br \/>\n\u2206G\u00b0 = Positive indicatis that the reaction is not feasible.<br \/>\nThe extraction of copper from pyrites is more difficult than that from its oxide ore through reduction. &#8216; .<br \/>\nExplanation : Pyrites (Cu<sub>2<\/sub>S) Cannot be reduced by carbon (or) hydrogent because the standard free energy of formation (\u2206G\u00b0) of Cu<sub>2<\/sub>S is greater then those of CS<sub>2<\/sub> and H<sub>2<\/sub>S.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22814\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-21.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 21\" width=\"367\" height=\"64\" \/><br \/>\nThe \u2206G\u00b0 of copper oxide is less than that of CO<sub>2<\/sub>.<br \/>\n\u2234 The sulphide ore is first converted to oxide by roasting and then reduced. Roasting<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22815\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-22.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 22\" width=\"358\" height=\"83\" \/><br \/>\nThe following are the conditions that Al might be expected to reduce MgO. The Equations for the formation of two oxides are<br \/>\n\\(\\frac{4}{3}\\)Al<sub>(S)<\/sub> + O<sub>2(g)<\/sub> \u2192 \\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3(S)<\/sub><br \/>\n2Mg<sub>(S)<\/sub> + O<sub>2(g)<\/sub> \u2192 2MgO<sub>(S)<\/sub><br \/>\nFrom the Ellingham diagram the two curves of these oxides formation intersect each other at a certain point. The corresponding value of \u2206G\u00b0 becomes zero for the reduction of MgO by aluminium metal,<br \/>\n2MgO<sub>(S)<\/sub> + \\(\\frac{4}{3}\\)Al<sub>(S)<\/sub> \u2192 2Mg<sub>(S)<\/sub> + \\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3(S)<\/sub><\/p>\n<ul>\n<li>From the above information the reduction of MgO by Al metal cannot occur below this temperature (1665 K) instead, Mg can reduce Al<sub>2<\/sub>O<sub>3<\/sub> to Al below 1665 K.<\/li>\n<li>Al-Metal can reduce MgO to Mg above 1665 K because \u2206G\u00b0 for Al<sub>2<\/sub>O<sub>3<\/sub> is less compared to that of MgO.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22816\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-23.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 23\" width=\"379\" height=\"41\" \/><\/li>\n<\/ul>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 2.<br \/>\nDiscuss the extraction of Zinc from Zinc blend<br \/>\nAnswer:<br \/>\n&#8220;Zinc blende (ZnS)&#8221; is an important source for &#8216;Zn&#8217;metal.<br \/>\nExtraction of&#8217;Zinc : Zinc blende ore is treated in the following states.<br \/>\ni) Crushing : The ore is crushed to a fine powder in ball mills.<br \/>\nii) Concentration of the ore : The ore is concentrated first by gravity process. The crushed ore is washed with a stream of water on a Wilfley&#8217;s table. The tables have a corrugated top and are under a rocking motion. Due to this motion, the lighter gangue particles are washed away by the steam. The heavier ore particles settle to the bottom of the table.<\/p>\n<p>The partially concentrated ore is further concentrated by froth floatation process. The ore particles go with the froth.<\/p>\n<p>The concentrated ore is subjected further to electromagnetic separatioh, if iron oxide is present in the gangue. Iron oxide is magnetic and so forms a heap nearer to the magnetic pole.<\/p>\n<p>iii) Roasting: The concentrated ore thus obtained is roasted in rotary shelf burner which is provided with horizontal shelves and raking arms. The ore is added at the top and zinc oxide is collected from the bottom. The following reactions take place.<br \/>\n2ZnS + 3O<sub>2<\/sub> \u2192 2ZnO + 2SO<sub>2<\/sub><br \/>\nZnS + 2O<sub>2<\/sub> \u2192 ZnSO<sub>4<\/sub><br \/>\n2ZnSO<sub>4<\/sub> \u2192 2ZnO + 2SO<sub>2<\/sub> + O<sub>2<\/sub><br \/>\niv) Reduction : Three methods are in practice for the reduction of the oxide to the metal. The most commonly used method is the Belgian process. In this process the roasted ore is mixed with coal or coke intimately and is taken in fireclay or earthern ware retorts. The retorts are made of fireclay which are bottle shaped tubes. These are closed at one end. The other end is connected to air cooled earthern ware condenser. A large number of retorts are placed in tiers in a large furnace and heated in 1I00\u00b0C by burning the gas. &#8216;Prolongs&#8217; made of sheet iron are attached to the condensers. The metal condenses in these earthern ware condensers and the prolongs. The metal powder collected is mixed with some zinc oxide and is known as &#8220;zinc dust&#8221;. Some of the zinc metal is collected in the fused state. This is solidified in moulds. This metal is called &#8220;zinc spelter&#8221;.<br \/>\nZnO + C \u2192 Zn + CO<br \/>\nZnO + CO \u2192 Zn + CO<sub>2<\/sub><br \/>\nElectrolytic refining : Very pure zinc is obtained by electrolysis. The electrolyte is zinc sulphate solution containing a little H<sub>2<\/sub>SO<sub>4<\/sub>. Impure zinc is made the anode and the pure zinc plates are made the cathode.<\/p>\n<p>Question 3.<br \/>\nExplain the reactions occuring in the blast furnace in the extraction of iron.<br \/>\nAnswer:<br \/>\nIn the Blast furnace, reduction of iron oxides takes place in different temperature ranges. Hot air is blown from the bottom of the furnace and coke is burnt to give temperature upto about 2200K in the lower portion itself. The burning of coke therefore supplies most of the heat required in the process. The CO and heat moves to upper part of the furnace. In upper part, the temperature is 1o%er and the iron oxides (Fe<sub>2<\/sub>O<sub>3<\/sub> and Fe<sub>3<\/sub>O<sub>4<\/sub>) coming from the top are reduced in steps to FeO. Thus, he reduction reactions taking place in the lower temperature range and in the higher temperature range, depend on the points of corresponding intersections in the \u2206<sub>r<\/sub>G\u00b0 vs T plots.<\/p>\n<p>These reactions can be summarised as follows:<br \/>\nAt 500 &#8211; 800 K (lower temperature range in the blast furnace)<br \/>\n3 Fe<sub>2<\/sub>O<sub>3<\/sub> + CO \u2192 2 Fe<sub>3<\/sub>O<sub>4<\/sub> + CO<sub>2<\/sub><br \/>\nFe<sub>3<\/sub>O<sub>4<\/sub> + 4 CO \u2192 3 Fe + 4 CO<sub>2<\/sub><br \/>\nFe<sub>2<\/sub>O<sub>3<\/sub> + CO \u2192 2 FeO + CO<sub>2<\/sub><br \/>\nAt 900 &#8211; 1500 K (higher temperature range in the blast furnace)<br \/>\nC + CO<sub>2<\/sub> \u2192 2 CO<br \/>\nFeO + CO \u2192 Fe + CO<sub>2<\/sub><br \/>\nLime stone is also decomposed to CaO which removes silicate impurity of the ore as CaSiO<sub>3<\/sub> slag. The slag is in molten state and separates out from iron.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22817\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-24.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 24\" width=\"411\" height=\"439\" \/><br \/>\nThe iron obtained from Blast furnace contains about 4% carbon and many impurities in smaller amount (e.g., S, P, Si, Mn). This is known as pig iron. Cast iron is different from and is made by melting pig iron with scrap iron and coke using hot air blast. It has slightly lower carbon content (about 3%) and is extremely hard and brittle.<br \/>\nFe<sub>2<\/sub>O<sub>3<\/sub> 3 C \u2192 2 Fe + 3 CO<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 4.<br \/>\nDiscuss the extraction of copper from copper pyrites.<br \/>\nAnswer:<br \/>\nExtraction of copper from copper pyrites:<br \/>\nCopper pyrite is the main source of copper metal. Various steps involved in the extraction of copper discussed below.<br \/>\nStep &#8211; I:<br \/>\nConcentration of ore by froth floatation process:<br \/>\nThe ore is first crushed in ball mills. The finely divided ore is suspended in water. A little pine oil is added and the mixture is vigorously agitated by a current of air. The froth formed carries the ore particles almost completely. The gangue sinks to the bottom of the tank. The froth is separated and about 95% concentrated ore is obtained.<\/p>\n<p>Step &#8211; II: Roasting :<br \/>\nTo remove the volatile impurities like As (or) Sb, the ore is roasted in a free supply of air. A mixture of sulphides of copper and iron are obtained and these are partially oxidised to respective oxides.<br \/>\nCu<sub>2<\/sub>S. Fe<sub>2<\/sub>S<sub>3<\/sub> + O<sub>2<\/sub> \u2192 Cu<sub>2<\/sub>S + 2FeS + SO<sub>2<\/sub><br \/>\n2Cu<sub>2<\/sub>S + 3O<sub>2<\/sub> \u2192 2Cu<sub>2<\/sub>O + 2SO<sub>2<\/sub><br \/>\n2FeS + 3O<sub>2<\/sub> \u2192 2FeO + 2SO<sub>2<\/sub><\/p>\n<p>Step &#8211; III :<br \/>\nThe roasted ore is mixed with a little coke and sand (Silica) and smelted in a blast furnace and fused. A blast of air, necessary for the combustion of coke, is blown through the tuyeres present at the base of the furnace. The oxidation of the sulphides of copper and iron will be completed further. A slag of iron silicate is formed according to the reactions given below :<br \/>\n2FeS + 3O<sub>2<\/sub> \u2192 2FeO + 2SO<sub>2<\/sub><br \/>\nFeO + SiO<sub>2<\/sub> \u2192 Fe SiO<sub>3<\/sub><br \/>\nFerrous Silicate (Slag)<br \/>\nCu<sub>2<\/sub>O + FeS \u2192 Cu<sub>2<\/sub>S + FeO<br \/>\nStep -IV:<br \/>\nAfter smelting the copper ore in blast furnace, the product of the blast furnace consists mostly of Cu2S and a little of ferrous sulphide. This product is known as &#8220;Matte.&#8221; It is collected from the outlet at the bottom of the furnace . After then the following processes are carried out for getting the pure copper.<\/p>\n<p>1. Bessemerization: The matte is charged into a Bessemer converter. A bessemer converter is a pear-shaped furnace. It is made of steel plates. The furnace is given a basic lining with lime or magnesium oxide (obtained from dolomite or magnesite). The converter is held in position by trunnions and can be tilted in any position. A hot blast of air and sand is blown through the tuyeres present near the bottom. Molten metal, the product in the furnace, collects at the bottom of the converter.<\/p>\n<p>Reactions that took place in blast furnace go to completion. Almost all of iron is eliminated as a slag. Cuprous oxide combines with cuprous sulphide and forms Cu metal.<br \/>\n2Cu<sub>2<\/sub>O + Cu<sub>2<\/sub>S \u2192 6Cu + SO<sub>2<\/sub><br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22818\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-25.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 25\" width=\"266\" height=\"309\" \/><br \/>\nThe molten metal is cooled in sand moulds. S02 escapes. The impure copper metal is known as &#8220;Blister copper&#8221; and is about 98% pure.<\/p>\n<p>Step -V:<br \/>\nRefining : The Blister copper is purified by electrolysis. The impure copper metal is made into plates. They are suspended into lead &#8211; lined tanks containing Copper (II) Sulphate solution. Thin plates of pure copper serve as cathode. The cathode plates are coated with graphite. On electrolysis, pure copper is deposited at the cathode. The copper obtained is almost 100% pure Cu.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 5.<br \/>\nExplain the various steps involved in the extraction of almninium from bauxite.<br \/>\nAnswer:<br \/>\nExtraction of Aluminium from Bauxite:<br \/>\nFor the purpose of extraction of Al, Bauxite is the best source.<br \/>\npurification of Bauxite : Bauxite containing Fe<sub>2<\/sub>O<sub>3<\/sub> as impurity is known as red Bauxite.<br \/>\nBauxite containing SiO<sub>2<\/sub> as impurity is known as white Bauxite and can be purified by &#8220;Serpeck&#8217;s Process&#8221;. Red Bauxite is purified by Bayer&#8217;s process and Hall&#8217;s process.<br \/>\nBayer&#8217;s Process : Red bauxite, is roasted and digested in concentrated NaOH at 423 K. Bauxite dissolves in NaOH to form sodium meta aluminate while impurity Fe<sub>2<\/sub>O<sub>3<\/sub> does not dissolve which can be removed by filtration.<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub>.2H<sub>2<\/sub>O + 2NaOH \u2192 2NaAlO<sub>2<\/sub> + 3H<sub>2<\/sub>O<br \/>\nThe solution which contains sodium meta aluminate is diluted and crystals of AZ(OH)3, are added which serves as seeding orgent. Sodium meta aluminate undergoes hydrolysis to precipitate Al(OH)<sub>3<\/sub>.<br \/>\n2NaAlO<sub>2<\/sub> + 4H<sub>2<\/sub>O \u2192 2NaOH + 2Al(OH)<sub>3<\/sub> \u2193<br \/>\nAl(OH)<sub>3<\/sub> is filtered and ignited at 1200\u00b0C to get anhydrous alumina.<br \/>\n2Al(OH)<sub>3<\/sub> <img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> Al<sub>2<\/sub>O<sub>3<\/sub> + 3H<sub>2<\/sub>O<br \/>\nHalls&#8217; Process: Red Bauxite is fused with sodium carbonate to form sodium meta aluminate which is extracted with water. The impurity Fe<sub>2<\/sub>O<sub>3<\/sub> is filtered out.<br \/>\nAl<sub>2<\/sub>O<sub>3<\/sub> + Na<sub>2<\/sub>CO<sub>3<\/sub> \u2192 2NaAlO<sub>2<\/sub> + CO<sub>2<\/sub><br \/>\nInto the solution of sodium meta aluminate, CO<sub>2<\/sub> gas is passed to precipitate Al(OH)<sub>3<\/sub>.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22819\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-26.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 26\" width=\"457\" height=\"41\" \/><br \/>\nThe precipitated Al(OH)<sub>3<\/sub> is ignited at 1200\u00b0C to get anhydrous alumina.<br \/>\n2Al(OH)<sub>3<\/sub> \u2192 Al<sub>2<\/sub>O<sub>3<\/sub> + 3H<sub>2<\/sub>O<br \/>\nSerpeck&#8217;s Process: Powdered bauxite is mixed with coke and heated to 2075 K in a current of nitrogen gas. Aluminium Nitride is formed while Si02 is reduced to SiO<sub>2<\/sub> which escapes out.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22820\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-27.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 27\" width=\"347\" height=\"72\" \/><br \/>\nAluminium nitride is hydrolysed to get aluminium hydroxide which on ignition gives anhydrous alumina.<br \/>\nAlN + 3H<sub>2<\/sub>O \u2192 Al(OH)<sub>3<\/sub> \u2193 + NH<sub>3<\/sub> \u2191<br \/>\n2Al(OH)<sub>3<\/sub> <img loading=\"lazy\" class=\"alignnone size-full wp-image-22804\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-11.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 11\" width=\"51\" height=\"28\" \/> 3 Al<sub>2<\/sub>O<sub>3<\/sub> + 3H<sub>2<\/sub>O<\/p>\n<p>Electrolytic Reduction of Alumina : Pure Alumina (Al<sub>2<\/sub>O<sub>3<\/sub>) is a bad conductor of electricity and it has high melting point (2050\u00b0C). So it cannot be electrolysed. Alumina is electrolysed by dissolving in fused cryolite to increase the conductivity and small amount of Fluorspar is added to reduce its melt\u00acing point. Thus the electrolyte is a fused mixture of Alumina, Cryolite and Fluorspar.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22821\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-28.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 28\" width=\"442\" height=\"329\" \/><br \/>\nElectrolysis is carried out in an iron tank lined inside with graphite (carbon) which functions as cathode. A number of carbon rods (or) copper rods suspended in the electrolyte functions as Anode.<br \/>\nNa<sub>3<\/sub>AlF<sub>6<\/sub> \u2192 3NaF + AlF<sub>3<\/sub><br \/>\nCryolite<br \/>\n4AlF<sub>3<\/sub> \u2192 4Al<sup>3+<\/sup> + 12F<sup>&#8211;<\/sup><br \/>\nAt cathode : 4Al<sup>3+<\/sup> + 12e<sup>&#8211;<\/sup> \u2192 4Al<br \/>\nAt anode : 12F<sup>&#8211;<\/sup> \u2192 6F<sub>2<\/sub> + 12e<sup>&#8211;<\/sup><br \/>\nF<sub>2<\/sub> formed at the anode reacts with alumina and forms Aluminium fluoride.<br \/>\n2Al<sub>2<\/sub>O<sub>3<\/sub> + 6F<sub>2<\/sub> \u2192 4AlF<sub>3<\/sub> + 3O<sub>2<\/sub><br \/>\nAluminium, produced at the cathode, sinks to the bottom of the cell. It is removed from time to time through topping hole.<\/p>\n<p>Purification of Aluminium : (Hoope&#8217;s Process)<br \/>\nThe impurities present are Si, Cu, Mn etc.,<br \/>\nThe electrolytic cell used for refining of aluminium consists of iron tank lined inside with carbon. This acts as anode. The tank contains three layers of fused masses. The bottom layer contains impure aluminium. Middle layer contains mixture of AlF<sub>3<\/sub>, NaF and BaF<sub>2<\/sub> saturated with Al<sub>2<\/sub>O<sub>3<\/sub>. Top layer contains pure aluminium and graphite rods kept in it act as cathode.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22822\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-29.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 29\" width=\"515\" height=\"285\" \/><br \/>\nOn passing current aluminium ions from the middle layer are discharged at the cathode as pure aluminium. Equivalent amount of aluminium from the bottom layer passes into middle layer.<\/p>\n<p><span style=\"color: #0000ff;\">Textual Examples<\/span><\/p>\n<p>Question 1.<br \/>\nSuggest a condition under which magnesium could reduce alumina.<br \/>\nAnswer:<br \/>\nThe two equations are :<br \/>\na) \\(\\frac{4}{3}\\) Al + O<sub>2<\/sub> \u2192 \\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3<\/sub><br \/>\nb) 2 Mg + O<sub>2<\/sub> \u2192 2MgO<br \/>\nAt the point of intersection of the Al<sub>2<\/sub>O<sub>3<\/sub> and MgO curves (marked. &#8220;A&#8221; in Ellingham diagram), the \u2206G<sup>\u2296<\/sup> becomes ZERO for the reaction :<br \/>\n\\(\\frac{2}{3}\\) Al<sub>2<\/sub>O<sub>3<\/sub> + 2Mg \u2192 2MgO + \\(\\frac{4}{3}\\) Al<br \/>\nBelow that point magnesium can reduce alumina.<\/p>\n<p>Question 2.<br \/>\nAlthough thermodynamically feasible, in practice, magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium. Why ?<br \/>\nAnswer:<br \/>\nTemperatures below the point of intersection of Al<sub>2<\/sub>O<sub>3<\/sub> and MgO curves, magnesium can reduce alumina. But the process will be uneconomical.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 3.<br \/>\nWhy is the reduction of a metal oxide easier if the metal formed is in liquid state at the temperature of reduction ?<br \/>\nSolution:<br \/>\nThe entropy is higher if the metal is in liquid state than when it is in solid state. The value of entropy change (\u2206S) of the reduction process is more on +ve side when the metal formed is in liquid state and the metal oxide being reduced is in solid state. Thus the value of \u2206G<sup>\u2296<\/sup>becomes more on negative side and the reduction becomes easier.<\/p>\n<p>Question 4.<br \/>\nAt a site, low grade copper ores are available and zinc and iron scraps are also available. Which of the two scraps would be more suitable for reducing the leached copper ore and why ?<br \/>\nSolution:<br \/>\nZinc being above iron in the electrochemical series (more reactive metal is zinc), the reduction will be faster in case zinc scraps are used. But zinc is costlier metal than iron. So using iron scraps will be advisable and advantageous.<\/p>\n<p><span style=\"color: #0000ff;\">Intext Questions<\/span><\/p>\n<p>Question 1.<br \/>\nWhich of the ores mentioned in Table can be concentrated by magnetic separation method ?<br \/>\nAnswer:<br \/>\nOres in which one of the components (either the impurity or the actual ore) is magnetic can be concentrated.<br \/>\nE.g.: ores containing iron (haematite, magnetite, siderite and iron pyrites).<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22823\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-30.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 30\" width=\"704\" height=\"499\" \/><br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22824\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-31.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 31\" width=\"703\" height=\"150\" \/><\/p>\n<p>Question 2.<br \/>\nWhat is the significance of leaching in the extraction of aluminium ?<br \/>\nAnswer:<br \/>\nLeaching is significant as it helps in removing the impurities like SiO<sub>2<\/sub>, Fe<sub>2<\/sub>O<sub>3<\/sub> etc. from the bauxite ore.<\/p>\n<p>Question 3.<br \/>\nThe reaction, Cr<sub>2<\/sub>O<sub>3<\/sub> + 2 Al \u2192 Al<sub>2<\/sub>O<sub>3<\/sub> + 2 Cr (\u2206G<sup>\u2296<\/sup> = -421 kJ) is thermodynamically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?<br \/>\nAnswer:<br \/>\nCertain amount of activation energy is essential even for such reactions which are thermodynamically feasible, therefore heating is required.<\/p>\n<p><img loading=\"lazy\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/07\/AP-Board-Solutions.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy\" width=\"196\" height=\"17\" \/><\/p>\n<p>Question 4.<br \/>\nIs it true that under certain conditions Mg can reduce Al<sub>2<\/sub>O<sub>3<\/sub> and Al can reduce MgO ? What are those conditions ?<br \/>\nAnswer:<br \/>\nYes, below 1350\u00b0C Mg can reduce Al<sub>2<\/sub>O<sub>3<\/sub> and above 1350\u00b0C, Al can reduce MgO. This can be inferred from \u2206G<sup>\u2296<\/sup> vs T plots.<br \/>\n<img loading=\"lazy\" class=\"alignnone size-full wp-image-22825\" src=\"https:\/\/apboardsolutions.com\/wp-content\/uploads\/2022\/08\/AP-Inter-2nd-Year-Chemistry-Study-Material-Chapter-5-General-Principles-of-Metallurgy-32.png\" alt=\"AP Inter 2nd Year Chemistry Study Material Chapter 5 General Principles of Metallurgy 32\" width=\"536\" height=\"490\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Andhra Pradesh BIEAP AP Inter 2nd Year Chemistry Study Material 5th Lesson General Principles of Metallurgy Textbook Questions and Answers. AP Inter 2nd Year Chemistry Study Material 5th Lesson General Principles of Metallurgy Very Short Answer Questions Question 1. What is the role of depressant in froth floatation? Answer: By using depressants in froth floatation &hellip;<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[14],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts\/35312"}],"collection":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/comments?post=35312"}],"version-history":[{"count":1,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts\/35312\/revisions"}],"predecessor-version":[{"id":35313,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/posts\/35312\/revisions\/35313"}],"wp:attachment":[{"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/media?parent=35312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/categories?post=35312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/apboardsolutions.guru\/wp-json\/wp\/v2\/tags?post=35312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}