Metallurgy in this lesson we shall learn about Metallurgy and the process of obtaining pure metal from ore the process used for extraction of metals in their pure form from their ores is referred to as metallurgy [Music] pure metals can be obtained from their ores through five steps the first step of Metallurgy is crushing and grinding of ores ores are crushed into a fine powder in big jaw Crushers and ball Mills this process is called pulverization after pulverization the ores are concentrated based on the type of impurities and their percentage proportions removal of impurities results in concentration of the ores concentration can be done by any of the three methods centrifugation is done done when there is difference between the densities of the ore and the [Music] impurities in this method fine powder of ore is placed on a moving table with slots and is moved rapidly such that the particles of metal remain in the slot because of centrifugal force the dense or particles settle down in the grooves while the lighter impurities are separated froth flotation is used to concentrate ores that are in sulfide forms concentration of sulfi ores of copper lead and zinc metal are carried out by this method The Ore is taken in a large tank containing oil and water and is agitated with a current of compressed air The Ore vetted by the oil separates from the impurities or gang in the form of froth heavy particles like clay sand Etc become vet and settle at the bottom hence the sulfide ore is removed with sees in a second vessel and washed with water in magnetic separation the pulverized ore is placed on a conveyor belt that has two magnetic Wheels the magnetic particles are attracted to the magnetic veel and fall separately apart from the non-magnetic particles methods like roasting calcination and smelting are used to convert the concentrated ore into metal oxide roasting is the process of heating the concentrated ore to high temperature in presence of excess air calcination is the process of heating the concentrated ore in absence of air at a temperature not sufficient to melt the ore smelting is a melting operation in which the constituents of the ore are in melted form next step of Metallurgy involves reduction of metals it can be done using reducing agents as well as by the process of electrolysis and thermal [Music] decomposition reducing agents like carbon or carbon monoxide are used to reduce zinc iron lead and copper oxides when oxides of metals like like ion manganese and chromium are heated with aluminium the corresponding metal is obtained by reduction electrochemical reduction method is used to obtain metals from oxides of active metals because these Metals attract more oxygen than carbon the metals produced by reduction still contain impurities further refining of metals can be done by electrolysis liquefaction and distillation metals like copper zinc tin lead chromium nickel silver and gold are refined [Music] electrolytically for refining of an impure metal by electrolysis a thick block of impure metal is made the anode and a thin strip of pure metal is made the cathode a water soluble salt is taken as electrolyte on passing current through the electrolyte the impure metal from anode dissolves into the electrolyte an equivalent amount of pure metal from the electrolyte is deposited on the cathode the soluble impurity goes into the solution whereas the insoluable impurities settle down at the bottom of the anode and is known as the anode mud this method is used for refining of metals like tin lead Etc having low melting points in this method a furnace having slope is kept slightly at higher temperature than the melting point of the metal the metal melts and is collected in the vessel kept below the melting points of impurities are higher and so do not melt and are found in the solid form on the slope [Music] if impurities are present in traces the principle of fractional crystallization is followed the refining of semimetals like Silicon Boron Etc is carried out by Zone refining method the impurities are mostof ible in the molten form so as the molten metal cools down the solubility of impurities decrease and separates out from the metal in the form of crystals [Music] la