The Migration Of Arsenic During Sulfuric Acid Production From Pyrite Roasting

Taking a Hubei sulfuric acid manufacturer from pyrite roasting as an example,this paper studies on the mode of occurrence and the migration of arsenic during sulfuric acid production from pyrite roasting.With detecting arsenic's total quality of ore ?mixed ore ?fly ash?tailings?dilute acid and sulphuric acid,we can sum up the migration of arsenic in whole process which is combined with company's production consumption datas.Through the modified BCR method,the pyrite ore ?electrostatic precipitator's fly ash and tailings of roasting furnace were sequentially extracted in the production system,it shows different modes of ansenic's migration situation.The conclusions as follows:1)The weak acid extraction state of arsenic in ore accounts for 0.69%,reducible state accounts for 0.56%,oxidizabe state accounts for 8.94%,residual state accounts for 88.57%.The weak acid extraction state of arsenic in mixed ore accounts for 0.71%,reducible state accounts for 0.60%,oxidizabe state accounts for 9.43%,residual state accounts for 88.70%.The weak acid extraction state of arsenic in tailings accounts for 5.28%,reducible state accounts for 8.50%,oxidizabe state accounts for 14.70%,residual state accounts for 69.08%.The weak acid extraction state of arsenic in fly ash accounts for 5.06%,reducible state accounts for 7.23%,oxidizabe state accounts for 12.77%,residual state accounts for 74.37%.2)In the process of producing sulphuric acid in every arsenic production procedure,residual form occupies the largest proportion,silicates and native secondary minerals deposit residual heavy metals in their lattice,chemical properties of residual form are relatively stable and they don't usually migrate,the residual of heavy metals can be long-team stability in minerals,its toxicity and bioavailability were low,indicating that in the process of acid making,most arsenic trapped in the crystal lattice of minerals,its potential biological toxicity is also small.3)The residual state of arsenic decreased from 88.70% of the mixed ore to 69.08% of the tailings and 74.37% of the fly ash after oxidizing roast.It shows that parts of the residual arsenic was separated from the crystal lattice during roasting,which was converted to other states of higher activity.4)The ratio of arsenic distribution in systems for pyrite-based sulphuric acid plants is from big to small: tailings> fly ash> loss> dilute acid> sulfuric,the main transfer point of arsenic in pyrite ore is tailing and fly ash,among them,arsenic in tailings accounts for 64.65%;arsenic in fly ash accounts for 31.38%,it indicates that most of the arsenic is fixed in the fly ash and tailings in the form of solid.