Lead blast furnace smelting process and the corresponding smelting equipment 

    Lead blast furnace smelting process is much simpler than copper process,only need sintering process and melting process can smelt out crude lead.Let’s look at the flow chart: 

    Sintering process 

    Concentrate powder,auxiliary materials and return product is mixed well by cylinder mixer,then enter into drum pelletizer to pelletize.The basic principle of lead concentrate sintering roasting is :load the materials prepared(lead concentrate powder,auxiliary materials,return product) into the sintering equipment(sintering machine,sintering pot),blow into a lot of air,ignite and heat to 800~950℃,then the sulfide in the burden will oxidate and produce metallic oxide and sulfur dioxide,various metallic oxides react with each other to form various salts,the melting point of lead silicate and per ferrite is lower than others,which acts as binder during sintering process,make the burden powder to be solid blocks,namely sinter(agglomerates). The purpose is:1.oxidative desulfurization makes the metallic oxide into oxide to adapt to the reduction smelting;2.sinter the burden powder to blocks;3.make the sulfur of concentrate to be sulfur dioxide in order to make acid;4.remove partial arsenic and antimony to avoid entering into blast furnace to produce a large amount of arsenic matte that can increase the loss of lead and precious metal. 　　　

    Equipment required:cylinder mixer,drum pelletizer,transport belt,sintering port or belt-type sintering machine,induced draft fan,dust collector.　　　

    Melting process 　　　

    Lead blast furnace is a kind of old lead smelting equipment,developes up yo now.With the large-scale production of modern,the water-jacketed torch type blast furnace with inclined bosh that wide at top,narrow at bottom is widely used around the world. 　　　

    Lead blast furnace is composed of furnace foundation,hearth,tuyere cooler,the upper water jacket,feed inlet,furnace top,frame and other components. 　　　

    Furnace foundation,is the base of lead blast furnace,is required to bear the full weight of lead blast furnace,generally is able to bear 40~60t/㎡,usually is built with concrete tamping stones. 　　　

    Furnace hearth,mason on the furnace foundation,usually make shell with thick steel plate,then pouring a cycle lead pool that big at top,small at bottom with high aluminum castable. 　　　

    Furnace body:composed of tuyere cooler and the upper water jacket.The cooling of water jacket is divided into circulating water cooling and evaporative cooling,each cooling method has its advantages,the inner wall of the water jacket is made by boiler plate,the outer wall is usually use common steel plate,with a brace in the middle.Water jacket is pressurized components,generally should take a 12Kg/㎡pressure test before delivery.Tuyere cooler sets 3~4 tuyeres depending on its width,the sectional area of tuyere center determines the furnace smelting capacity,there are 1.14㎡、1.5㎡、2.26㎡、3.2㎡、3.5㎡、6㎡、8㎡、10㎡ etc.,there is an angle between vent and standard,usually is 3~5℃.The center distance is 200~400mm,tuyere ratio is a very important value.　　　

    Feed inlet,namely the position of agglomerates and coke into. 　　　

    Furnace top,charge and exhaust device are known as the top of furnace. 　　　

    In the actual process of lead blast furnace’s reduction smelting,usually use coke as reductant,there are also some factories use a small number of anthracite. 　　　

    We divide the lead blast furnace into six areas along the height: 　　　　　　　　　

    When smelting lead burden in the lead smelting furnace,we can obtain various of smelted products such as crude lead,lead matte,arsenic matte,soot and slag etc.. 　　　

    crude lead,usually contain 96~99% lead,also contain metal impurities (such as copper,bismuth,tin) and precious metals(such as gold,silver and tellurium). 　　　

    Lead matte,arsenic matte. 　　　

    Soot,contains a lot of valuable metals,such as lead,cadmium,thallium and so on.Its composition depends largely on the melting conditions and raw materials. 　　　

    Slag,when the iron,silicon and calcium etc. in the furnace complete slagging process,lead and slag separate,the product quenched by water is furnace slag. 

     Equipment required:lead blast furnace,roots blower,induced draft fan,water pump,dust collector.