Basic Research On Cooperative Extraction Technology Of Alunite From Copper Tailings

With the growing market demand for copper resources of rapid economic development,more and more mines are mined to produce a large amount of copper tailings.By the end of 2014,China’s copper tailings reserves has reached 3 billion tons.The stockpiling of copper tailings not only occupies a large amount of land,but also causes serious pollution to the surrounding soil and water during the wind erosion and rain process,posing a certain threat to human health.The main mineral components in copper tailings are quartz,alunite,dickite,etc.As a multi-element composite raw ore,alunite has a high recycling value.The current comprehensive treatment method for copper tailings is mainly to enrich alunite concentrate by flotation,and recovery of valuable elements such as Al,K,and Ga in the concentrate.However,The development and utilization of alunite resources still have problems such as single product and low utilization rate.Based on this,This subject takes the collaborative extraction of multiple elements from alunite as the research object.Based on the research on the optimization mechanism of the alunite phase enrichment process in copper tailings,high-temperature rapid thermal decomposition and enhanced leaching processes are used to comprehensively recycle aluminum,potassium,and gallium in alunite concentrate.By optimizing the process and introducing mechanical activation means to strengthen leaching,the efficient and coordinated extraction of aluminum,potassium,and gallium from the alunite concentrate is realized.Combined with the problems in the comprehensive utilization of alunite,this article firstly studied the effect of the composition,dosage,and tailings composition on the flotation of alunite concentrate on the basis of the alunite flotation process of Zijinshan copper tailings.In addition,The mineral facies composition and the distribution of main and trace elements of alunite concentrates in different sizes are studied.The results showed that after removing pyrite,the flotation experiment was carried out with the amount of sodium carbonate as 2000 g/t,sodium silicate as 400g/t,sodium oleate as 100 g/t,Obtained alunite concentrate with SO3 grade of 25.41%and SO3 recovery rate of 72.54%.The results of the analysis of the phase composition of the alunite concentrates in different particle sizes show that the alunite concentrate with large particle size,the higher the alunite content,the lower the quartz content.Then,the influencing factors and optimal leaching conditions of the multi-element synergistic extraction process in alunite were systematically studied,and the optimal process conditions for potassium,aluminum and gallium extraction were determined.The results show that the best conditions for the thermal decomposition process are:temperature 900℃,time 10 min;the best conditions for water immersion K2 O are:room temperature(30℃),time 10 min,liquid-solid ratio 3;the best conditions for acid melting: temperature 240℃,the molar ratio n(H2SO4):n(Al2O3)is 3,the time is 20 min,the liquid-solid ratio is 3;the best conditions for water immersion aluminum sulfate are: temperature 95℃,time 5 min,liquid-solid ratio 6.Under the optimal conditions,the leaching rates of alumina,potassium oxide and gallium reached90.03%,81.24%,and 85.35%.Finally,on the basis of process optimization,mechanical activation enhanced leaching was introduced.Through the characterization of the crystal structure,particle size distribution,surface morphology,and thermal behavior of the ore samples before and after mechanical activation,the mechanism of mechanical activation to enhance the leaching of aluminum,potassium,and gallium was preliminarily explored,and on this basis,the aluminum in the concentrate after mechanical activation was carried out.The crystal structure,particle size distribution,surface morphology,and thermal behavior of the alunite concentrate before and after mechanical activation were characterized,and the mechanism of mechanical activation to strengthen the leaching of aluminum,potassium,and gallium was preliminarily explored.On this basis,a collaborative extraction experiment of aluminum,potassium,and gallium in the concentrate after mechanical activation was carried out.The results showed that the leaching rate of aluminum oxide,potassium oxide,and gallium increased to 96.45%,82.97%,and 92.71%.In this paper,aiming at the problems of complex phase and poor chemical reaction performance of alunite,the basic research on the multi-element collaborative extraction technology of alunite has been carried out,and the efficient and collaborative extraction of aluminum,potassium,and gallium in alunite has been realized,which has broad application prospects and promotion value.