Compared with steel smelting, nonferrous metals smelting has more complex crafts, longer process procedures and more types of smelting furnaces. The production crafts of copper smelting comprise: pre-processing, matte smelting, copper blowing smelting, pyro-metallurgical refining and electrolyte refining.
Copper ore smelting methods can be classified into pyrometallurgy and wet metallurgy. Compared with wet metallurgy, pyrometallurgy has lower energy consumption, better adaptation to mineral grades and larger smelting scale, so pyro-metallurgy smelted copper accounts for 90% of all copper yield. Among copper pyrometallurgy smelting crafts, flash smelting and bath smelting are in dominant position.
Bath smelting is a high efficient self heating smelting method, which adopts direct blasting and intense bath agitation to swiftly realize the main chemical reactions between gas, liquid and solid phases. It is suitable for the smelting, sulfuring, oxidizing, reducing, blowing smelting and fuming of nonferrous metals materials. Flash smelting is the method that feeds dry and concentrate sulfide ore, flux, oxygen or oxygen rich air, or preheated air into high temperature furnace, raw material are quickly oxidized and melted at suspension state. The pyrometallurgy of copper including two steps: copper sulfide concentrate ore making matte smelting and matte blowing smelting.
Matte Smelting Furnace
Matte is half done copper frit which are smelted by adding silica, lime and other flux. Copper content of matte varies based on the types of smelting furnace, usually between 30%~50%. Matte smelting furnaces can be classified into blast furnace, reverberator, flash furnace and so on. Flash furnace is in the dominant position, the second is reverberator, others are isa furnace, Noranda reactor and so on.
Copper Blast Furnace
The method of making matte by copper concentrate ore in inclosed blast furnace are widely used in some countries. Copper blast furnace are composed of furnace top, furnace bosh, internal crucible, furnace hearth, tuyere and so on. During smelting, concentrate ore is added into furnace through hopper, the added ore makes the furnace a closed environment. Concentrate ore, coke, flux and other solid material are loaded from furnace top, high pressure air are blew into furnace from lower part of furnace bosh tuyere equipment. The up moving hot air will fully contact with down moving materials and make them melted, oxidized or reduced. Furnace slag and matte will separate with each other when entering into fore crucible through throat. Molten slag mainly comprises SiO2-FeO-CaO series material, the highest temperature of tuyere upper part smelting zone is 1350℃.
Copper Blast Furnace Refractory
Furnace top cover is consisted of cover board and water jacket, lateral side lining is made of chamotte bricks and asbestos board, covered by steel board. Furnace are consisted of water jackets, throat hole and furnace bottom are built by magnesia bricks.
Copper blast furnace upper part usually adopts clay bricks, chrome bricks. Tuyere and upper oblique furnace wall is built by clay bricks. The working lining of copper blast furnace is constructed bymagnesia chrome bricksor chrome bricks.
