GENERAL PRINCIPLES OF METALLURGY GENERAL PRINCIPLES OF METALLURGY

GENERAL PRINCIPLES OF METALLURGY

GENERAL PRINCIPLES OF METALLURGY INTRODUCTION TO MINERALS & ORES

GENERAL PRINCIPLES OF METALLURGY Metal usage is part and parcel of our life. A few of them i. e. We use them for all our needs. for your eyes only Industrial equipment Cooking Medical equipment Transportation

GENERAL PRINCIPLES OF METALLURGY Metals are used for all our needs in all our applications of modern world. Most of the metals do not occur in free state. They occur in combined state in the earth crust.

GENERAL PRINCIPLES OF METALLURGY Metals find their applications in allthewalks of life. Let us observe the stages involved getting pure metal from an ore. Stage-I SELECTION OF ORES Stage-II CONCENTRATION OF ORE Stage-III EXTRACTION OF METAL Stage-IV REFINING OF METAL PURE METAL

GENERAL PRINCIPLES OF METALLURGY MINERAL : Do you know what Doexactly you know what an minerals ore is! mean! Ø The naturally occurring substances on the earth’s crust which are obtained by mining which contains the metal in free state or combined state. Ø A mineral containing a high percentage of the metal, from which the metal can be profitably extracted.

GENERAL PRINCIPLES OF METALLURGY ORE: What does ore contain? Ore has metal in the combined state and is usually contaminated with earthy impurities and undesirable chemicals

GENERAL PRINCIPLES OF METALLURGY MCQ S 1) The natural materials from which an element can be extracted economically are called… a) ores b) minerals c) gangue d) flux

GENERAL PRINCIPLES OF METALLURGY 2) Earth crust extends up to a) 50 km b) 1000 km c) 3000 Km d) 6500 Km

GENERAL PRINCIPLES OF METALLURGY MINERALS & ORES OF A FEW METALS

GENERAL PRINCIPLES OF METALLURGY Occurrence of Metals Aluminum Aluminium is the 3 rd most abundant element in earth’s crust (8. 3% approx. by weight)

GENERAL PRINCIPLES OF METALLURGY Occurrence of Metals Fe is one of the most important elements Fe is 2 ndessential most abundant usedmetal in highly plants in theevolved earth crust and animals. Fe is present in haemoglobin to supply oxygen through blood. Iron Cu, Ag, Au, pt, Fe are the metals that occur to some extent in native state as they are less reactive metals.

GENERAL PRINCIPLES OF METALLURGY Minerals & Ores of a few metals Haematite Fe 2 O 3 Magnetite Fe 3 O 4 2 Fe 2 O 3. 3 H 2 O Iron Zinc blende Zn. S Zinc Limonite Zincite Zn. O Calamine Zn. CO 3 Iron pyrite Fe. S 2 Siderite Fe. CO 3

GENERAL PRINCIPLES OF METALLURGY Minerals & Ores of a few metals Copper pyrites Cu. Fe. S 2 Copper Malachite Cu. CO 3. Cu(OH)2 Cuprite Cu 2 O Bauxite Al 2 O 3. 2 H 2 O Aluminum Cryolite Na 3 Al. F 6 China clay Al 2 O 3. 2 Si. O 2. 2 H 2 O Copper glance Cu 2 S

GENERAL PRINCIPLES OF METALLURGY Minerals & Ores of a few metals Magnesite Mg. CO 3 Dolomite Mg. CO 3. Ca. CO 3 Magnesium Epsom Salt Mg. SO 4. 7 H 2 O

GENERAL PRINCIPLES OF METALLURGY 1) Haematite formula a) Zn. S b) Mg. CO 3 c) Fe 3 O 4 d) Fe 2 O 3 MCQ S

GENERAL PRINCIPLES OF METALLURGY 2) Magnesite formula a) Zn. S b) Mg. CO 3 c) Fe 3 O 4 d) Fe 2 O 3

GENERAL PRINCIPLES OF METALLURGY 3) The number of water molecules present in Epsom salt a) 4 b) 5 c) 6 d) 7

GENERAL PRINCIPLES OF METALLURGY DEFINITION OF METALLURGY

GENERAL PRINCIPLES OF METALLURGY The process of extraction and isolation of metal from its naturally occurring compounds is called metallurgy. And it should be chemically and commercially viable. gold What is metallurgy?

GENERAL PRINCIPLES OF METALLURGY The selection of a mineral as an ore depends on following factors : Ø The percentage of metal in the mineral. Ø Nature and magnitude of impurities in the mineral. Ø The expenditure involved in the extraction of metal from the mineral. Ø The industrial utility of bye – products produced in the metal extraction.

GENERAL PRINCIPLES OF METALLURGY The extraction and isolation of metals from ores involve the following major steps: Concentration of the ore (Removal of gangue), Isolation of the metal from its concentrated ore, Ø Purification of the isolated metal.

GENERAL PRINCIPLES OF METALLURGY MCQ S 1. Metallurgy is … a) Isolation of ore from the metal b) Isolation of mineral from metal c) Isolation of metals from its ore d) None of these

GENERAL PRINCIPLES OF METALLURGY 2. Which of the following is not a reactive metal? a) Na b) Ag c) Mg d) Fe

GENERAL PRINCIPLES OF METALLURGY 3. Which of the following ores do not represent the ore of iron? a) Casseterite b) Haematite c) Limonite d) Magnetite

GENERAL PRINCIPLES OF METALLURGY CONCENTRATION OF ORES 1. HYDRAULIC WASHING

GENERAL PRINCIPLES OF METALLURGY Concentration of Ores Removal of the unwanted gangue (e. g. , sand, clays, etc. ) from the ore is known as Some of the important procedures concentration, dressing or benefaction. are described as follows. .

GENERAL PRINCIPLES OF METALLURGY e CONCENTRATION ue Watch this g e gangue CO MET M AL PO UN gang D ue ng u e ue Concentrated ore gangue ga gangue u ng gangue n ga ng ga e u ng ga ga ga u ng

GENERAL PRINCIPLES OF METALLURGY magnetic ores all ores Hydraulic Washing Magnetic Separation sulphide ores Froth Floatation Leaching CONCENTRATION METHODS Al, Ag & Au

GENERAL PRINCIPLES OF METALLURGY I) Hydraulic Washing or Levigation Ø It is a type of gravity separation. In one such process, an upward stream of running water is used to wash the powdered ore. Hydraulic Classifier Wilfley’s Table

GENERAL PRINCIPLES OF METALLURGY I) Hydraulic Washing or Levigation Working & using of hydraulic classifier method Aheavier powerful current of water is are Gangue particles are lighter and The Finely dividedore oreparticlesare collected dropped introduced through thewhich pipe thetheat carried awayof bythe thecone current ofat at thein apex iswater at through the HOPPER BOTTOM. thethe top. bottom of reservoir.

GENERAL PRINCIPLES OF METALLURGY

GENERAL PRINCIPLES OF METALLURGY MCQ S 1) The earthy impurities present in the mineral are called a) flux b) gangue c) slag d) Refractory material

GENERAL PRINCIPLES OF METALLURGY MAGNETIC SEPARATION

GENERAL PRINCIPLES OF METALLURGY II) Magnetic Separation Ø This is based on the differences in magnetic properties of the ore and gangue. One of them is attracted by magnet and separation is carried out. Conveyor belt Magnetic roller

GENERAL PRINCIPLES OF METALLURGY The ground ore is carried on a conveyor belt which passes over an electromagnetic wheel. Electromagnetic wheel of the WORKING conveyor attracts only magnetic with particles. Magnetic into a separate heap. separator Non Magnetic Ore Particles Electromagnetic belt Magnetic Ore Particles 1. Chromite ore is separated from non – magnetic silicon impurities.

GENERAL PRINCIPLES OF METALLURGY MCQ S 1. Electromagnetic separation method is based upon… a) Preferential washing of ores & gangue particles b) Difference in densities of ore particles & impurities c) Difference in magnetic Properties of ore particles & impurities d) None of these

GENERAL PRINCIPLES OF METALLURGY 2. Magnetic separation is used for increasing concentration of following… a) Horn silver b) Calcite c) Haematite d) Magnesite

GENERAL PRINCIPLES OF METALLURGY FROTH FLOATATION METHOD

GENERAL PRINCIPLES OF METALLURGY III) Froth floatation method Ø ‘The surface of sulphide ores is preferentially wetted by oils while that of gangue is preferentially wetted by water. ’

GENERAL PRINCIPLES OF METALLURGY WORKING using Floatation cell a suspension of the powdered ore is A rotating paddle agitates the mixture mixed with iswater, to this collectors (e. g. The mineral froth light and is skimmed off. It The particles wet by oil and draws air in it. Asbecome a result, froth is Pine fattyacids, xanthates etc. ) isoils, then dried forparticles recovery of oreand while the gangue water. formed which carries the by mineral froth stabilizers (e. g. Cresols, aniline particles. etc. ) are added.

GENERAL PRINCIPLES OF METALLURGY Froth Floatation

GENERAL PRINCIPLES OF METALLURGY What if two sulphide ores are present? ADD DEPRESSANTS

GENERAL PRINCIPLES OF METALLURGY Principle T AN SS ORE 1 + ORE 2 RE P DE ORE 1 + DEPRESSANT ORE 2

GENERAL PRINCIPLES OF METALLURGY For example, Ø In case of an ore containing Zn. S and Pb. S, the depressant used is Na. CN Ø It selectively prevents Zn. S from coming to the froth but allows Pb. S to come with the froth Pb. S + Zn. S Na. CN Na 2[Zn(CN)4] Pb. S

GENERAL PRINCIPLES OF METALLURGY MCQ S 1. The froth-floatation process is based upon… a) Magnetic properties of gangue b) Specific gravity of ore particles c) Preferential wetting of ore particles by oil d) Preferential wetting of gangue particles by oil

GENERAL PRINCIPLES OF METALLURGY 2. Which of the following is used as a foaming agent in Froth Floatation process ? a) KCN b) Cu. SO 4 c) Nitric acid d) Pine oil

GENERAL PRINCIPLES OF METALLURGY 3. Which one of the following ores is not concentrated by Froth Floatation process ? a) Copper pyrites b) Pentlandite c) Iron Oxide d) Zinc blende

GENERAL PRINCIPLES OF METALLURGY LEACHING OF ALUMINA FROM BAUXITE

GENERAL PRINCIPLES OF METALLURGY IV) Leaching The process of extracting minerals from a solid by dissolving them in a liquid. It is used if the ore alone but not the gangue is soluble in some suitable solvent. The following examples illustrate the procedure

GENERAL PRINCIPLES OF METALLURGY (a) Leaching of alumina from bauxite Bauxite usually contains Si. O 2, iron oxides and titanium oxide (Ti. O 2) as impurities. Bauxite

GENERAL PRINCIPLES OF METALLURGY Ø Concentration is carried out by digesting the powdered ore with a concentrated solution of Na. OH at 473 – 523 K and 35 – 36 bar pressure. Al 2 O 3 (s) + 2 Na. OH (aq) + 3 H 2 O (l) → 2 Na[Al(OH)4] (aq) This way, Al 2 O 3 is leached out as sodium aluminate (and Si. O 2 too as sodium silicate) leaving the impurities behind

GENERAL PRINCIPLES OF METALLURGY Ø Sodium aluminate is neutralized by passing CO 2 gas and hydrated Al 2 O 3 is precipitated. 2 Na[Al(OH)4] (aq) + CO 2 (g) Al 2 O 3. x. H 2 O (s) + 2 Na. HCO 3 (aq) Ø The sodium silicate remains in the solution and hydrated alumina is filtered, dried and heated to give back pure Al 2 O 3. x. H 2 O (s) Al 2 O 3 (s) + x. H 2 O (g)

GENERAL PRINCIPLES OF METALLURGY (b) Other examples Ø silver and gold is leached with a dilute solution of Na. CN or KCN in the presence of air (for O 2) from which the metal is obtained later by the replacement by zinc. 4 M (s) + 8 CN– (aq) + 2 H 2 O (aq) + O 2 (g) 4[M(CN)2]– (aq) + 4 OH– (aq) (M= Ag or Au)

GENERAL PRINCIPLES OF METALLURGY MCQ S 1) The impurities present in Bauxite … a) Si. O 2 b) iron oxides c) Ti. O 2 d) All the above

GENERAL PRINCIPLES OF METALLURGY 2) Which of the following aqueous solution is used in Leaching of Alumina… a) Na. OH b) Ca(OH)2 c) Cs. OH d) B(OH)3

GENERAL PRINCIPLES OF METALLURGY EXTRACTION OF CRUDE METAL FROM CONCENTRATED ORE

GENERAL PRINCIPLES OF METALLURGY A SECTION OF A MODERN REVERBERATOR FURNACE Charge Hooper Hangers Charge Hooper Tie rod Air and oil Magnestie Furnace charge Silica

GENERAL PRINCIPLES OF METALLURGY Ore. Limestone and coke Exhaust gases (CO, CO 2) 3 Fe 2 O 3 +CO→ 3 Fe. O + CO 2 (Iron ore) Fe 2 O 4 + CO→ 3 Fe. O + CO 2 Ca. CO 3 →Ca. O + CO 2 (Limestone ) Ca. O + Si. O 2 → Ca. Si. O 3 Slag Fe. O + CO → Fe + CO 2 C + CO 2 → 2 CO C + O 2 → CO 2 Fe. O + C → Fe + CO Blast of air and oxygen

GENERAL PRINCIPLES OF METALLURGY ORES CONCENTRATION EXTRACTION REFINING PURE METAL

GENERAL PRINCIPLES OF METALLURGY Extraction of Crude Metal from Concentrated Ore: Ø Isolation of metals from concentrated ore involves two major steps viz. , a) Conversion of ore into oxide if the ore is not an oxide b) Reduction of the oxide to metal

GENERAL PRINCIPLES OF METALLURGY a) Conversion to oxide. I) Calcination: After heating the metal oxide is formed Ø Calcination involves heating of the ore in the absence of air just below its fusion temperature in a reverberatory furnace. Fe 2 O 3 (s) + x. H 2 O (g) Fe 2 O 3. x. H 2 O (s) Zn. CO 3 (s) Zn. O (s) + CO 2 (g) Ca. O (s) + Mg. O (s ) + 2 CO 2 (g)

GENERAL PRINCIPLES OF METALLURGY II) Roasting: Ø In roasting, the ore is heated in a regular The SO 2 produced is supply of air in a reverberatory furnace utilized for at a temperature below the melting point manufacturing of H 2 SO 4 of the metal. q Some of the reactions involving sulphide ores are… 2 Zn. S + 3 O 2 → 2 Zn. O + 2 SO 2 2 Pb. S + 3 O 2 → 2 Pb. O + 2 SO 2 2 Cu 2 S + 3 O 2 → 2 Cu 2 O + 2 SO 2 Ø The sulphide ores of copper are heated in reverberatory furnace.

GENERAL PRINCIPLES OF METALLURGY If the ore contains iron oxide, it is mixed with silica and roasted. Iron oxide is converted into iron silicate, called slag A mixture of Cu 2 S and little Fe. S is know as Copper matte

GENERAL PRINCIPLES OF METALLURGY Smelting : Ø The process of separating molten metal in crude form (or) mixture of metal sulphides in molten form from ore is called smelting. Example : A mixture of copper iron pyrites, coke and sand on heating in blast furnace gives matte.

GENERAL PRINCIPLES OF METALLURGY b) Reduction of oxide to the metal Ø Reduction of the metal oxide usually involves heating it with some other substance acting as a reducing agent (Carbon or coke or CO) Ø The reducing agent (e. g. , carbon) combines with the oxygen of the metal oxide to form CO Mx. Oy + y. C →x. M + y CO

GENERAL PRINCIPLES OF METALLURGY To study the temperature dependence for thermal reduction and choice of reducing agent at high temperature can be made from Gibbs energy and temperature curves called Ellingham diagrams.

GENERAL PRINCIPLES OF METALLURGY MCQ S 1) Which gas is liberated during roasting? a) SO 2 b) O 2 c) SO 3 d) H 2

GENERAL PRINCIPLES OF METALLURGY 2) Reducing agent used in reduction of oxide to the metal a) CO 2 b) O 2 c) N 2 d) C

GENERAL PRINCIPLES OF METALLURGY Thank you…