| Arsenic belongs to the accompanying elements and is widely distributed in a variety of non-ferrous metallurgy ores.A large amount of arsenic wastewater and arsenic containing solid waste will be produced in mining,beneficiation and smelting.If handled improperly,it will cause serious ecological pollution and environmental hazards.Steel slag has adsorptive properties and chemical precipitation.Treatment of arsenic-containing wastewater and arsenic-containing waste with steel slag can significantly reduce the migration of arsenic in the environment.This paper uses steel slag to remove arsenic from water and applies the steel slag to co-cured arseniccontaining sludge,which makes full use of the arsenic removal characteristics and gel composition of steel slag,strengthens arsenic fixation,and realizes " waste treatment by waste".In this paper,the arsenic removal behavior of steel slag to water and the synergistic arsenic technology of steel slag are studied.The technical parameters such as XRD,XRF,ICP-OES,XPS and SEM are used to optimize the process parameters and explain the mechanism of arsenic removal and arsenic fixation.Steel slag is mainly composed of calcium ferrite,dicalcium silicate,tricalcium silicate,and other oxides.The p H of leaching solution from high-calcium steel slag is high up to 12.1,showing a high alkalinity.The arsenic removal rate of steel slag increases with decreasing particle size or increasing steel slag usage.When the particle size is 200-300 mesh,the removal of arsenic from steel slag in As(III)and As(V)water reaches 0.90 mg/g and 0.93 mg/g,respectively.The arsenic removal rate of steel slag is relative stable in the p H range of 1-12,and the arsenic fixation rate reaches 99%.The adsorption behavior of steel slag is controlled by the rate of chemical precipitation reaction.During the adsorption,chemical precipitation followed with the surface adsorption could simultaneously fix the arsenic.Calcium and iron oxides in high-calcium steel slag can precipitate arsenic ions though adsorption and chemical reactions,forming relatively stable calcium and iron arsenate and arsenite.It reduces the arsenic leaching toxicity and thus achieves arsenic stabilization.The leaching toxicity of arsenic-fixed steel slag is lower than the 5 mg/L.The arsenic-fixed steel slag is classified as a general solid waste.The composition of steel slag and cement is similar.The incorporation of steel slag can change the compressive strength of the solidified block.When the steel slag takes up 70% of the total amount of the cured lump,the compressive strength of the solidified block can reach 42.29 MPa at 28 days after natural curing.When the arsenic solution is cured by the steel slag and cement in a collaborative way,the leaching of arsenic ions is less than 5 mg/L when the content of steel slag is less than 60%.The solidification of arsenic is affected by hydration process of the solidified arsenic sludge.The leaching concentration of arsenic ions in the solidified block decreases with the increasing of the compressive strength.The amount of fixed arsenic sludge is 40%,and the proportion of steel slag in the solidified body is 30%,and the curing effect is the best.After 28 days of natural curing,the leaching concentration of arsenic ions is 3.25 mg/L.The solidified arsenic of steel slag in a collaborative way shows superior performance,which is suitable for the harmless disposal of arsenic acid and arsenic sludge. |
PDF Full Text Request