Research On Resource Utilization Of Gold Cyanidation Tailings

Cyanidation tailings is the solid waste of gold ore extracted by cyanidation method.With the rapid development of gold enterprises in China,the discharge amount of cyanidation tailings increases year by year,forming a series of environmental and social problems.The research on the reduction and resource utilization of cyanidation tailings has very important value for environment,economy and socity.Based on the analysis of the physical properties of cyanidation tailings,the effects of different technologies for arsenic removal on cyanidation tailings was studied.More importantly,the technology of recovering iron ore powder from cyanidation tailings was studied.In order to improve the utilization of cyanidation tailings,the technology and property of sintered bricks were studied using strong magnetic rough separation tailings of cyanidation tailings as main raw material.The basic physical properties of cyanidation tailings were firstly analyzed in this paper.The results show that the main mineral composition of cyanidation tailings was hematite,quartz,feldspar,etc.The tailings particle size was fine,the average particle size was about 30μm.The content of Fe₂O₃in cyanidation tailings was 59wt%,and the grade of iron was high,so it had great value of recovering.The content of As₂O₃was 0.36wt%,which greatly exceeds the requirement of iron ore powder index.The concentration of cyano in the leaching solution was 4.33 mg/L,which met the emission standard of solid waste containing cyanide stipulated in the"Identification standards for hazardous wastes-Identification for extraction toxicity"（GB 5085.3-2007）.On the basis of comparative analysis of the removal process of arsenic by pyroprocessing and wet processing,the effect of the concentration of arsenic removal agent Na OH,reaction temperature and reaction time on the effect of arsenic removal by wet process was also studied.The optimum conditions for arsenic removal were determined,the concentration of arsenic removal agent was 4wt%,the reaction temperature was 60℃,and the reaction time was 8 h.Under these conditions,the arsenic removal rate of cyanidation tailings reaches above 80%and the arsenic content reaches below 0.07wt%,which met the arsenic content index requirements of iron ore powder in GB/T32545-2016.The effect of rapid grinding time on the particle size of cyanidation tailings was studied,the effect of recovering iron ore powder from cyanidation tailings by different magnetic separation processes was analyzed,and the technological process of"rapid grinding-strong magnetic rough separation-weak magnetic fine separation"was determined.According to single factor experiment and orthogonal experiment,the optimal technological parameters of strong magnetic rough separation and weak magnetic fine separation were determined.In the first step,the magnetic field intensity was 1 T,mineral concentration was 10wt%,slurry inlet velocity was 4 L/min,and water discharge was 12L/min.In the second step,the magnetic field intensity was 0.2 T,the mineral concentration was 2.5wt%,the slurry inlet velocity was 2 L/min,and the water discharge was 12 L/min.The iron grade of the iron concentrate powder sorted under this optimal condition was55.79wt%,which met the requirement of GB/T32545-2016.The yield of iron ore powder was 52.38%and the total iron recovery was 70.76%.At last,the formulation and technology of sintering bricks were studied by using strong magnetic rough separation tailings as main raw material and bentonite as auxiliary material.The optimal solution for the preparation of sintered brick were determined,the addition amount of bentonite was 20wt%,the sintering temperature was 1000℃,and the holding time was 30 min.Under the optimal experimental conditions,the sintering bricks were prepared with compressive strength of about 27 MPa,volume density of 2.03 g/cm³,and water absorption rate of 16.09%,which met the performance requirements of MU20brick in"Fired common bricks"（GB/T5101-2017）.