Experimental Study Of Calcium Sulfate Whisker Preparation From Desulfurization Gas From Sintering Flue Gas

Desulfurization ash in Sintering flue gas is a major by-product of the desulfurization in sintering process.With the increasing of the sulfur dioxide output,the yield of desulfurization ash increases.Since the desulfurization ash contains a certain amount of chloride ions,its application is limited.Therefore,it is important for the iron and steel industry to achieve comprehensive utilization of desulfurization ash.In this paper,calcium sulfate dihydrate of chemically pure reagent is raw material.Based on kinetics behavior of calcium sulfate dissolution,the research was done by preparation of calcium sulfate whiskers(CSW)using desulphurization gypsum as primary materials under atmospheric pressure.Under the condition of this experiment,we have got the following conclusions:(1)In the atmospheric pressure conditions,the rate of dissolution of calcium sulfate dihydrate increases and the apparent activation energy decreases gradually with increasing of NaCl and MgCl2.NaCl and MgCl2 promote the dissolution of calcium sulfate,in addition that MgCl2 shows a stronger effect.(2)Under MgCl2 solution system,the dissolution rate of calcium sulfate dihydrate increases gradually with the decrease of pH value,and the increase of temperature and time.Moreover,the dissolve apparent kinetic model of calcium sulfate dihydrate under different NaCl,MgCl2 and pH value system is established(3)The aspect ratio of calcium sulfate whisker preparing from desulfurization ash increases first and then decreases with the increase of reaction temperature,stirring speed and pH value.When the pH value is 3.5,the aspect ratio reaches a maximum which is 85.But CSW is relatively small in the condition of low ph value.(4)By the method of hydrothermal,calcium sulfate whiskers can be prepared from desulphurization ash,whose aspect ratio is higher than 85.And reasonable process conditions are as follows:The range of reaction temperature is 130～150℃.And the range of reaction time is 37.5～45min.The initial pH value is from 3 to 3.5.The stirring rate is from 45 r·min-1 to 60r·min-1.The solid-liquid ratio is 1:10 and additive is 2.5%MgCl2.