磁铁矿还原法制备绿矾及其母液回收新技术

【作者】 彭春丽；

【导师】 郑雅杰； 陈文汨；

【作者基本信息】 中南大学 ， 冶金物理化学， 2004， 硕士

【摘要】 硫铁矿烧渣是硫酸工业的固体废物，综合利用硫铁矿烧渣具有十分重要的意义。本文利用硫铁矿烧渣制备得到高质量绿矾，将绿矾母液与氨反应得到硫酸亚铁铵，达到了清洁生产绿矾的目的。 在硫酸溶液中，加入硫铁矿烧渣，在搅拌下，控制反应温度为115℃，反应4h后过滤得到烧渣酸浸液。硫铁矿化学性质极其稳定，通常条件下与硫铁矿烧渣酸浸液中Fe³⁺反应速度很慢。硫铁矿经机械活化后反应活性大大提高，扫描电镜（SEM）实验表明硫精矿为块状体，球磨后硫精矿表面呈颗粒状，并有团聚现象，反应后团聚现象消失。 反应因素对硫铁矿还原法制备硫酸亚铁结果有着重要的影响，增加球料比、延长球磨时间、降低反应液固比、提高反应温度和溶液氢离子浓度，均有利于FeS₂与Fe³⁺反应速度的加快。Fe³⁺浓度高，不利于提高Fe³⁺的还原率。在球料比10.8∶1、球磨时间4h，反应液固比100∶20、反应温度80℃、总铁浓度2.230mol／L、Fe³⁺浓度2.130mol／L、氢离子浓度为0.700mol／L条件下，反应90minFe³⁺原率达到99.05％；当反应温度高于85℃时，反应中有白色沉淀物FeSO₄·H₂O生成。 通过对机械活化硫铁矿与硫铁矿烧渣酸浸液中Fe³⁺反应动力学的研究，得出该反应符合收缩未反应芯模型，属化学控制。反应动力学方程为1-（1-X_b）^1／3=kt，k=82.12e^-35120／RT，活化能E₀=35.12kJ·mol^-1。研究结果表明提高反应温度可以明显提高FeS₂与Fe³⁺反应速度，实验结果也得到证实。溶液中FeS₂与Fe³⁺发生如下反应FeS₂+14Fe³⁺+8H₂O=15Fe²⁺+2SO₄^2-+16H⁺，FeS₂+2Fe³⁺=3Fe²⁺+2S↓。 存放后机械活化的硫铁矿的活性有所降低，当液固质量比为25∶2时，90℃下反应240min，存放3个月的活性硫铁矿还原Fe³⁺的转化率为61.2％，未存放活性硫铁矿还原Fe³⁺转化率达到76.75％。 硫铁矿还原法所得绿矾母液含有较高浓度的Fe³⁺，使用少量铁屑还原处理后，绿矾母液中FesO;和玩50;含量一般为1 .18mol/L和1.44mol/L，重金属离子含量有所减少，Fe3+毛0.Olmol/L，有利于回收绿矾母液制备莫尔盐。 利用处理后绿矾母液制备工业级莫尔盐适宜条件是搅拌速度为200一350转/分钟、Fe3+浓度蕊0.osmol/L、反应终点pH值为1 .5一2.5、氨气流量为0.1一0.4m3/h。当母液中亚铁和硫酸浓度调节分别为1.654mol/L时，上述条件下制备得到的莫尔盐、硫酸亚铁回收率为85.20cy0。 硫铁矿作还原剂制得绿矾质量好于GB 1 0 5 31一S9优等品质量，接近GB664一93化学试剂。工业级莫尔盐样品质量达到企业标准，（Fe（NH4）2（504）:·6玩O含量）98%，水不溶物蕊0.1%)。更多还原

【Abstract】 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%.更多还原