The Basic Study And Industrial Practice Of Electronic Waste Smelting

Green and efficient utilization of"urban mine",such as electronic waste and other secondary resources,is a key solution in solving the resource shortage problem in China.The co-treating of these above materials in the copper/lead/nickel pyrometallurgical process is recognized as the preferred process.However,the contents of aluminum and halogen elements in electronic waste are high,and the contents of iron and sulfur are low.The smelting slag is always high in Al₂O₃,which results technical and equipment problems,such as difficult to operate and vulnerable key components of the furnace;Reaction behaviors of valuable metals in raw materials are also easily influenced by halogen elements,and they enter the slag phase,the gas phase and the crude copper phase.In order to clarify the reaction mechanism of electronic waste smelting with the top blowing smelting technology and to study the distribution behaviors of valuable metals in this process,this thesis investigated the phase equilibria of the high Al₂O₃ slag system,and determined the corrosion mechanism of magnesium series refractory and3-series stainless steel lance materials in e-waste smelting slag;Then,the distribution behavior of Au,Ag,Sn and other elements in the copper alloy/high aluminum slag/gas phase smelting system have been studied with the static erosion method,and the influence of halogen elements（F/CL/BR）have been found out.The e-waste smelting dust has been systematically analyzed,and the oxidation alkali leaching process has been put forward to recovery these halogens in the dust.Optimized parameters have been obtained through experiments,and Na Br has been prepared.The mass transportation and material mixing in the lance and the molten bath have been studied by dynamic simulation.Finally,the industrial practice of electronic waste smelting has been modeled with the results of fundamental research and industrial practice.The material balance and energy balance in the process have been studied through METSIM.The main results are as follows:（1）Under the electronic waste smelting conditions,the solubility of Al₂O₃in the Fex O-SiO₂-Al₂O₃-Ca O slag system decreased with the increase of Ca O content.When there was 20wt.%Ca O and the Fe/SiO₂ mass ratio was 0.86-1.1,the solubility of Al₂O₃ in slag could be 20wt.%.The dissolution of components and the formation of new phases were main reasons of the failure of magnesium-series refractories and 3-series stainless steel lance materials.The dissolution of refractories and steel components accelerated when increasing the temperature,and the increasing of Al₂O₃ content in slag slowed down the corrosion of refractories and lance materials.The newly formed（Mg,Fe）·（Cr,Fe,Al）₂O₄ spinel layer and the（Ni,Fe）·（Fe,Cr,Al）₂O₄ spinel layer could slow down the chemical corrosion process of magnesium-series refractory and the 3-series lance materials,respectively.However,the newly formed anorthite,olivine and other phases accelerated the corrosion process of the above materials.（2）In the phase equilibrium experiment,when adding 1-10%Ca F₂,93%Au entered the metal phase.When adding same amount of Ca Cl₂ or Ca Br₂,up to 32%Au might enter into the gas phase.When adding Ca F₂in to the system,22-49%of Ag enters to the gas phase.But when adding Ca Cl₂ or Ca Br₂,3-34%of Ag enters to the gas phase.The proportion of tin in the gas phase and slag phase increase along with increasing the temperature or the addition of halides.The contents of Au,Ag,Sn and Br in the smelting dust were high.More than 98.3%of halogen in the smelting dust can be removed with the oxidation alkali leaching process,and crude Na Br could be prepared with crystallization.The leaching residue could be used as reverts.METSIM simulation results showed that under the optimized conditions,the crude copper contained more than90%copper,the discharged slag contained about 0.5%copper,and the recovery rates of copper,gold and silver were≥98%.The heat of raw material reaction was the largest part of the heat income,and they accounted for 66.94%of the total.The fuel burning heat accounted for33.04%of the total.The heat carried away by the flue gas accounted for48.37%of the total hat output,and the heat carried away by the slag accounted for 28.47%.Figures 79;Tables 38;References 117...