Mechanism And Application Of Arsenic Fixation Of Steel Slag-based Active Materials

The mining of arsenic-containing minerals and industrial production makes a large amount of arsenic stored in the natural environment in the form of liquid and solid,thus posing a threat to human health.Solidification/Stabilization of arseniccontaining hazardous waste with strong migration is an important means to reduce the hazard of arsenic pollution.Steel slag was used as raw material to be activated for stabilization treatment of arsenic-containing waste acid and arsenic-containing sludge.The optimum condition and the mechanism of arsenic fixation was studied.First,the steel slag was subjected to acid,alkali,salt,and thermal modification treatments,and the effects of the modification treatment on the physico-chemical properties and arsenic removal performance of the steel slag were investigated.The results show that the modification treatment can effectively improve its arsenic removal ability.Among them,acid modification has the best arsenic removal effect.According to the solid-liquid ratio of 0.04 kg/L,acid modified steel slag was added,and it was oscillated for 120 min at room temperature under the action of oxidizer.After treatment,the residual arsenic concentration of waste acid decreased to 88.44 mg/L,and the arsenic removal efficiency reached 97.89%.Acid-modified steel slag can release a large amount of Ca and Fe ions,and remove arsenic through coprecipitation and adsorption.Secondly,the optimal conditions for preparing gel materials under the activation of alkali activator by steel slag silica fume were studied and used for the solidification / stabilization of arsenic in ionic form.When the steel slag-silicon fume ratio is 8: 2,the water-cement ratio is 0.25,and the amount of the alkali activator is 10%,the gel material has the best physical strength.At that time,the toxic leaching of the solidified body complied with national safety stacking standards,and its solidification rate of arsenic was above 99%.Analysis by FTIR,TEM and other characterization methods shows that arsenic is stabilized by physical encapsulation and chemical fixation.Provide theoretical guidance and experimental feasibility analysis for the subsequent solidification/stabilization of arsenic-containing sludge.Finally,the steel slag-red mud-cement ternary synergistic solidification of arsenic-containing sludge was carried out.The effects of the mixing ratio of steel slag,red mud,cement,and arsenic-containing sludge on physical compressive strength and arsenic-fixing performance were determined,and the optimal mixing ratio of each component was determined as steel slag: Red mud: Cement: Arseniccontaining sludge = 5: 2: 2: 1.After curing 28,the compressive strength of the solidified body can reach 20.07 MPa.At this time,the toxic leaching value is lower than the standard line of 5 mg/L,and the harmless and stabilized of arseniccontaining sludge are realized.The steel slag is used for arsenic treatment of arseniccontaining waste acid and arsenic-containing sludge,realizing clean production by waste treatment.