Research On Arsenic Removal Of Pyrites And Pyrite Cinder

Arsenic is a highly toxic pollutant, which belongs to the class I environmental carcinogens. Industrial production in China brings large amount of arsenic into the environment every year. Over years, large number of arsenic pyrite cinder discharged by sulphuric acid industry have caused serious pollution. Arsenic caused great harm to the residents healthe by polluting groundwater. This paper presents the research of arsenic removal on both the raw materials and the pyrite cinder, to reduce the arsenic pollution and hazards, and improve resource utilization. The main contents and achievement are as follows:(1) The arsenic removal of pyrites was started with the research of pure pyrite and arsenopyrite, to develop new combination depressants B31which could achieve satisfactory separation of pyrite and arsenopyrite in the flotation of artificial mixed minerals.(2) Experimental study of the depressants B31in the actual pyrites:The main composition of the Anhui material is pyrite. After investigating the effect of grinding fineness, pH and dosage on the flotation results, the concentrate with Zn29.52%, S39.27%, As0.32%were obtained with one rough selection, two scavengers, the recovery of S and As was45.68%and0.78%respectively. The Guangxi material contains mainly pyrrhotite and sphalerite, the gangue minerals was removed by bulk flotation, then the sphalerite concentrate with Zn29.4%, As0.57%and arsenic pyrrhotite concentrate with As4.18%were obtained at high pH conditions. After the pyrrhotite concentration was treated by B31, the final product contained S31.06%, As2.33%, the operation removal rate of arsenic was69.11%, which need further improvement and optimization.(3) The arsenic pyrite cinder was first treated by gravity separation and then processed by chemical method. The optimum conditions was determined as:grinding fineness is-0.074mm85%, the temperature is30℃, the acidity of sulphuric acid is2.5%, liquid-solid ratio is5:1, stirring speed is350r/min, leaching time is60min. Under the optimum condition, the concentrate with Fe63.3%, As0.033%could be obtained.(4) In the surface oxidization research of pyrites and arsenopyrite, it showed that there were stable interval among pyrite, pyrrhotite and arsenopyrite in the Eh-pH diagram, so sulfur-arsenic separation could be achieved according to the difference of each stable interval.(5) The effect of B31to the cyclic voltammetry curve of pyrite and arsenopyrite was studied in the electrochemical research. By the comparison and analysis of the variation of the oxidation peaks and reduction peaks in the curve, it was found that the depressants B31had facultative agency to the arsenopyrite surface, which could reduce the floatability of arsenopyrite and was conducive to the separation of arsenopyrite and pyrite.(6) The thermodynamics study of the pyrite cinder showed that FeAsO4could be seperated from the cinder by acid leaching.