Removal Of Arsenic From Copper-containing Molten Iron Reduced By Copper Slag

Copper smelting slag contains valuable metal elements such as copper and iron.In order to realize the high value of copper slag utilization,our research group proposes a new process of copper slag vortex dilution and reduction smelting copper-containing antibacterial stainless steeLHowever,the reduced molten iron contains harmful elements such as As,S,P.Especially,elelment As will not only affect the performance of the steel,also has the biological toxicity.So the arsenic removal is one of the important steps in this technique,which is the main influencing factor that copper-containing antibacterial stainless steelreduced from copper slag can be used in tableware and medical device.In this paper,the thermodynamics of the reaction system of arsenide,sulfide in copper-containing molten iron with calcium carbide is studied.The single factor experimentsare used to study the removal of arsenic in copper-bearing molten iron reduced by copper slag,and the removal of As by carbide is studied.Chemical analysis,XRD and SEM are used to detect and analyze the composition of metal and slag after arsenic removal.The main conclusions are as follows.(1)By scanning electron microscopy(SEM)analysis,it can be found that sulfur in copper slag is mainly combined with iron and copper,while arsenic is mainly combined with copper and coated with copper matte.(2)By thermodynamic calculationof the reaction system of arsenide,sulfide in copper-containing molten iron with calcium carbide,in the temperature range of 1200k-2000k,arsenide and sulfide in molten iron with copper both can react with calcium carbide to desulphurize and dearsenide.Desulphurization of calcium carbide is exothermic reaction and low temperature is conducive to desulphurization.Calcium carbide desulphurization is endothermic reaction,so high temperature is conducive to desulphurization.Theoretically,on the condition of 1573k,copper iron can be desulphurized to0.0022%by calcium carbide,and on the condition of 1823k,calcium carbide can remove arsenic in metal to 0.0154%.When the carbon content is 4%,copper iron can be desulphurized to0.0085%.(3)The optimum condition of arsenic removal is obtained by Single factor experimental study on reduction of copper-containing molten iron by prepared copper slag.While the reaction temperature is 1623K,the amount of calcium carbide added is 10 times the amount required for the reaction,the carbon content is 9%,under the best conditions,content of S in metal can be 0.0058%,desulphurization rate 99.59%,content of As is 0.022%,desulphurization rate 78.43%,reaching the standard of copper containing antibacterial stainless steel produced in Taiyuan steel plant.In addition,the experiment shows that S is removed before As,and the content of S has a great influence on the effect of arsenic removal.By XRD,it can be found the main phase of arsenic removal slag is C and CaS.In 1623K,the amount of calcium carbide added 8 times theoretically added,and the carbon content 9%,slag skimming experiment is carried out.After the reaction,the arsenic slag is removed in time,and the mass fraction of arsenic decreased from 0.050%to 0.042%,removed 16%.(4)The arsenic removal experiments are carried out under suitable conditions obtained in single factor experiments.The compositions of molten iron are 4.14%C,0.009%S,0.023%As,4.79%Cu,0.059%P.The As content has been in accordance the antibacterial stainless steel standard produced in Taiyuan steel plant,the S content reaches the national standard,and the contents of trace harmful elements such as Ni,Sb,Bi,Sn and Pb have reached the standard.(5)The kinetics study of the arsenic removal process of calcium carbide is carried out,and the expression of arsenic removal rate was calculated by using the liquid-liquid of slag and metal reactionmodel.When the reaction temperature is between 1350? and 1450?,the reaction rate constant is 0.0234?0.0301 m/s,and when the amount of calcium carbide addition is 8?12 times,the reaction rate constant is 0.0126?0.0306m/s,and Whenthe carbon content is 7?9%,the reaction rate constant is 0.0234?0.0272m/s.The apparent activation energy of arsenic removal by calcium carbide is 58.44 kJ/mol and the frequency factor is 1.77.