| In sulfuric acid industry pyrite cinder is the main solid waste, it is very important to use them comprehensively. In this paper, the high grade copperas were synthesized by using the pyrite cinder as raw materials, then the Fe(NFl4)(SO4)2.6H2O was synthesized by using copperas mother liquid and ammonia. In the whole process, there is no waste and clean production goal is achieved.The pyrite cinder was added into acid sulfuric solution, then stirring and keeping the temperature at 150 . After react for 4h, the leaching liquid was obtained. The SEM tests show that pyrite is clumpy, activated pyrite is granular and agglomerate and the agglomeration of activated pyrite disappears after reaction.Using the pyrite as the reductant, the reaction conditions have great effects on FeSO4 synthesized by reduction method. The rate of FeS2 and Fe3+ increasing as ratio of ball mass to pyrite mass, grinding time and reaction temperature, H+ concentration increase and ratio of solution volume to activated pyrite mass decreases. When Fe3+ concentration is higher, it is not available for the reduction of Fe3+.The reduction ratio of Fe3+to Fe2+ is up to 99.05%, when the reaction temperature is 80 and the ratio of solution volume to activated pyrite mass is 100:20 and the ratio of ball mass to activated pyrite mass is 10.8:1 and ball grinding time is 4h. And the total Fe concentration is 2.230mol/L and Fe3+ concentration is 2.130 mol/L and H+ concentration is 0.700mol/L and the reaction time is 1.5 h.. The white sediment FeSO4 H2O is produced when the reaction temperature is above 85The kinetics on Fe3+ produced by mechanical activation pyrite is studied in this paper, the reaction is controlled by diffusion and the reaction is applicable to the shrinking core model, the kinetics equation is the active energy E0 is 35.12kJ mol-1. The reaction rate between the FeS2 and Fe3+ increases obviously with the increase of the reaction temperature. The results can be proved by our experiment. The main reactions in the solution are below: FeS2+14Fe3++8H2O=15Fe2++2SO42-+16H+, FeS2+2Fe3+=3Fe2++2S .The activity of the mechanical activated pyrite is decreased after depositing it for a long time. The Fe3+ reduction ratio of the mechanicalactivation pyrite is 61.2% when the mass ratio of liquid to solid is 25:2 and the reaction time is 2h. at the reaction temperature of 90 and depositing it for 3 month, but the Fe3+ reduction ratio of the pyrite without deposition is 76.75%.The copperas mother liquid has high Fe3+ concentration. After putting the iron scraps into mother liquid, the concentration of FeSO4 and H2SO4 in the copperas mother liquid are respectively 1.18mol/L and 1.44mol/L. Meantime the ion concentration of heaven metals decreased and the concentration of Fe3+ is lower than 0.01 mol/L, the conditions are available for recovery of the ammonium iron( II ) sulfate hexahydrate by the method of recycling copperas mother liquid.The optimal conditions that make industry grade ammonium iron( II) sulfate hexahydrate by processed copperas mother liquid arethat stirring rate is 200-350 r/min, concentration of the Fe is lower than 0.05 mol/L, the pH value is 1.5-2.5, the flow of the ammonia is0.1-0.4 m3/h. when the concentration of the Fe and H2SO4 in the mother liquid is 1.654mol/L, the recovering of the ammonium iron(II) sulfate hexahydrate and FeSO4 is 85.20%.The quality of copperas prepared by this method is up to top gradeproduct of GB105 31-89 of China. Ammonium iron( II ) sulfatehexahydrate sample quality was up to the enterprise standard.Fe(NH4)2(SO4)2 6H2O content is more than 98%, water insolublesubstance is less than 0.1%. |
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