| At present,accumulation of copper slag in china is up to 280 million tons,and copper slag emissions of china is about 18.56 million tons in 2016.Copper grade in slag is about 0.42%to 4.6%,much higher than the current copper mining grade,0.3%.Accumulation of copper slag not only occupies the land and pollute the environment,but also causes a huge waste of resources.Therefore,the dilution of copper slag to recover valuable copper is of great significance.Depletion methods of copper slag in industry are mainly beneficiation method and fire method,which using vulcanizing agent to dilution and appropriate CaO,SiO2 to improve slag type.Vulcanizing agent added in copper slag with high temperature will float on the slag surface.The chemical reaction is carried out relying on the "sliding contact" of the vulcanizing agent and the slag,resulting in severe volatile of vulcanizing agent and the terrible scene environment.In order to solve the problem,the mechanical stirring method is adopted to promote the copper slag dilution,that is,vortex dilution.In this thesis,the thermodynamics of vortex dilution was analyzed,the efficiency of eddy current dilution was verified by using the resistance furnace,the vortex dilution stirring parameter was determined by water model experiments,and the vortex dilution experiments were done in resistance furnace.The effects of reaction temperature,addition of vulcanizing agent,speed in settlement time and holding time on the process of depletion were investigated.The chemical compositions,XRD,SEM and other methods were used to analyze the mineralogical composition,the composition of slag and copper matte and the state of elemental occurrence after vortex depletion.The conclusions are as follows:(1)Thermodynamic calculations show that Fe3O4 can be reduced to FeO by FeS;oxides such as ZnO and PbO can be reduced;CaO and SiO2 remain in the residue;addition of appropriate amount of CaO and SiO2 help to decrease the reaction temperature and the viscosity of the slag,which is favorable for the deposition of copper matte particles.It can be known from isothermal section(1250?)and advantage area map that Cu2S and FeS have a stable existence region.(2)It can be obtained from the water model experiments that the agitation parameters of vortex dilution process are stirring speed 250rpm and immersing depth 70mm.The vortex morphology is obvious.The ratio of the actual concentration of the solution to theoretical concentration C/C0 is 0.83,the stirring effect is obvious.(3)Through the single factor experiments,it can be known that the appropriate conditions of vortex dilution are:experiment temperature is 1250?,addition amount of vulcanizing agent is 3%of the quality of copper slag,mixing speed is 250rpm,mixing time is lmin,stirring peed in settlement is 40rpm,stirring time is 30min,settling time is 120min.At this time,the content of copper in the slag decreases from 2.94%to 0.34%,and copper recovery is 91.34%.The content of Fe3O4 in slag decreases from 15.05%to 4.65%.Under the suitable experimental conditions obtained from the single factor experiments,different copper slag can be depleted in copper from 4.48%to 0.56%,the content of Fe3O4 in slag decreases from 20.14%to 8.87%,copper yield was 45.3%.the experimental conditions are stable,and the separation of slag and matte is good.Vortex dilution process has general applicability.(4)The separation of slag and matte is good.The main phases of matte are Cu2S,FeS and ZnS.At high temperature,part of As will enter into the soot aspartic,and most are coated by copper matte and settled to the bottom.The phase of the volatile is mainly ZnO and PbO.The phase of slag after dilution is mainly 2FeO·SiO2.(5)According to the calculation by Einstein-Roscoe model,the viscosity of copper slag decreases from 0.292Pa·s to 0.108Pa·s at the optimum dilution temperature 1250?.It can be known that the viscosity of copper slag decreases during vortex dilution,which is in favor of polymerization and settlement of copper matte particles. |
PDF Full Text Request