Tiêu đề 2. METALLURGY (103-135).pmd.pdf ✅

X – Chemistry (Vol – I) Olympiad Text Book 103 Narayana Group of Schools Olympiad Class Work Book Prin ciple s o f M etallurg y T y p es of Ore s Extra ctio n of Iro n R e v erb eratory Furn a ce H a n d Pic kin g M etals of Hig h R e a ctivity Distillatio n Bla st Furn a c e W a s hin g M etals of M o d erate R e a ctivity P olin g M uffle Furn a c e Froth Flo atatio n M etals of Le s s R ea ctivity Liq u atio n Electric Furn a ce M a g n etic S e p aratio n Ele ctrolytic R efinin g C orro sio n M etal A ctivity S erie s C o n c e ntratio n (O R) Dre s sin g Extra ctio n of Cru d e M etal R efinin g (O R) P urific atio n of T h e M etal Furn a c es A n d Its T y p e s Allo y s Extra ctio n of M etals Fro m T h e Ore s CONCEPT FLOW CHART
X–Chemistry (Vol–I) 104 Narayana Group of Schools Olympiad Class Work Book ANDERS CELSIUS: Anders celsius was a swedish astronomer who is known for inventing celsiustemperature scale. celsius also built the uppsala astronomical observatory in1740, the oldest astronomi- cal observatory in sweden. Celsius was an avid adimirer of the gregorian calendar, which was adapted in sweden in1753,just nine years after his death.”degree Celsius” the unit of temperature,has been named after this bril- liant scientist. ANDERS CELSIUS [1701– 1744] METALLURGY
X – Chemistry (Vol – I) Olympiad Text Book 105 Narayana Group of Schools Olympiad Class Work Book METALLURGY Introduction : All materials found on earth are made up of chemical elements. Most elements found on earth are metals and some of them are non-metals. Metals like iron, aluminium, copper, tin, lead, silver gold etc. and non-metals like carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus are found as sulphides, carbonates, halides and silicates. In this unit, we shall discuss the ores of metals and the types of rocks in which they are present. Methods of extraction of metals from their ores and the methods of purification of impure metals. Important Terms: Metallurgy : The branch of chemistry which deals with the method of extraction of metals from their ores. Metal : The element which tends to form positive ion is called a metal and which are electropositive in nature. Minerals : The various compounds of metals which occur in the earth's crust and are obtained by mining are called minerals. In earth’s crust, order of abundance of elements is. O > Si > Al > Fe A mineral may be single compound or a mixture. Ores: The rocky materials which contain sufficient quantity of mineral so that the metal can be extracted profitably or economically are known as ores. Gangue: The undesirable materials present in ore are known as gangue. Flux : A substance added in the furnace during smelting to remove gangue. Slag : A substance formed when flux reacts with gangue. SiO CaCO CaSiO CO 2 3 3 2    Roasting: It is a process in which ore is heated in regular supply of air at a temperature below melting point of the metal so as to convert the given ore into oxide ore. Sulphide ores are converted into oxide by roasting. It is also used to remove impurities as volatile oxides. 2Zns 3O 2ZnO 2SO 2 2     Smelting: It is the process of reducing roasted ore and removing the gangue. Calcination: It is a process of heating carbonate ores in absence of air so as to convert the ore into its oxides. It is also used to remove moisture and volatile impurities. CaCO CaO CO 3 2    Pyro metallurgy: Extraction is done using heat energy. The metals like Cu,Fe,Zn,Pb,Sn,Ni,Cr.Hg etc., which are found in nature in the form of oxides, carbonates, sulphides are extracted by this process.
X–Chemistry (Vol–I) 106 Narayana Group of Schools Olympiad Class Work Book Hydrometallurgy: Extraction of metals involving aqueous solution is known as hydrometallurgy. Silver, gold, etc. are extracted by this process. Electrometallurgy: Extraction of highly reactive metals such as Na, K, Ca, Mg, Al, etc. by carrying electrolysis of one of the suitable compound in fused or molten state. Occurrence of the metals in nature: How the metals are present in nature? The earth’s crust is the major source of metals. Sea water also contains some soluble salts such as sodium chloride and magnesium chloride etc. Some metals like gold (Au), silver (Ag) and platinum (Pt) are available in nature in Free State as they are least reactive. Other metals mostly are found in nature in the combined form due to their more reactivity. The elements or compounds of the metals which occur in nature in the earth’s crust are called minerals. At some places, minerals contain a very high percentage of a particular metal and the metal can be profitably extracted from it. The minerals from which the metals are extracted without economical loss are called ores. Aluminium for example, is the most common metal in the Earth’s crust, occurring in all sorts of minerals. However, it isn’t economically worthwhile to extract it from most of these minerals. Instead, the usual ore it is profitable to extract from is bauxite which contains from 50-70 % of aluminium oxide . Important ore : 1.Oxide ore : (i) Bauxite -Al2O3 .2H2O (Major ore of Al) (ii) Haematite - Fe2O3H (iii)Zincite = ZnO (iv)Cassiterite or tin stone - SnO2 (Black Tin = 60 – 70% SnO2 ) (v)Cuprite or Ruby copper - Cu O2 2.Carbonate ore : (i) Lime stone - CaCO3 (ii) Dolomite - CaCO3 .MgCO3 (iii)Siderite - FeCO3 (iv) Malachite - CuCO3 .Cu(OH)2 (v) Azurite - 2CuCO3 .Cu(OH)2 (vi) Calamine - ZnCO3 (vii) Cerussite - PbCO3 3.Sulphate ore : (i)Epsom salt - MgSO4 .7H2O (ii)Gypsum - CaSO4 .2H2O (iii)Barytes-BaSO4 iv)Anglisite- PbSO4
X – Chemistry (Vol – I) Olympiad Text Book 107 Narayana Group of Schools Olympiad Class Work Book 4.Silicate ore : (i)Feldspar - KAlSi3O8 (ii)Spodumene-LiAl(SiO3 ) 2 (iii)Wollastonite-CaSiO3 (iv)Kaolinite(or) China- clay-Al2O3 .2SiO2.2H2O (v)Beryl- 3BeO.Al2O3 .6SiO2 - (vi)Asbestos- CaO.3MgO.4SiO2 (vii)Mica - K2O.3Al2O3 .6SiO2 .2H2O 5.Sulphurised ore : Consist of sulphides of metal like Iron, lead, zinc & mercury. (i)Iron pyrites (or) Fool’s gold - FeS2 (ii)Copper glance - Cu2S (iii)Copper pyrite or chalcopyrite - CuFeS2 (iv)Zinc Blende - ZnS (v)Galena - PbS (vi)Cinnabar - HgS 6.Halide ore : (i)Cryolite - Na3AlF6 (ii)Sylvine - KCl (or) Sylvite (iii)Carnallite - KCl.MgCl.6H2O (iv)Fluorspar - CaF2 (v)Horn silver - AgCl 7. Phosphate Ore: (i)Rock Phosphate - Ca3 (PO4 ) 2 (ii)Vivianite - Fe3 (PO4 ) 2 .8H2O (iii) Turquoise- 6 4 2     4 8 CuAl PO OH H O .4 Note :Mg obtained from both sea water & earth crust. The metals like K, Na, Ca, Mg and Al are so reactive that they never found in nature at free state. The metals like Zn, Fe, Pb etc., are moderately reactive. They are found in the earth crust mainly as oxides, sulphides and carbonates. Metals like Au, Ag are very least reactive and they found in free state in nature. Based on reactivity we can arrange metal in descending order of their reactivity as shown below: K,Na,Ca,Mg,Al High reactivity Zn, Fe, Pb, H Moderate reactivity Hg,Ag,Au,Pt Low reactivity