| Lead has biological toxicity, when wastewater containing lead entered the environment, it can’t be microbial degradation, it can only form the mutual conversion between, dispersion and enrichment, and along the food chain transmission, through the skin, the digestive tract, respiratory tract into the body with a variety of organs and savings. But lead is widely distributed in nature and is often used as the raw material in manufacturing. If without proper safe disposal of wastewater containing lead inevitably bring great harm to the environment. Therefore, to find a safe, reliable and cost-effective way to deal with Pb wastewater becomes particularly important.Steel slag is a molten slag discharged from the steelmaking process, it can be divided into converter steel slag, furnace steel slag and electric furnace steel slag. Steel slag has long been used as solid waste for disposal.XRF, XRD, SEM and BET analysis the composition and microstructure of steel slag. The results show that:with a rough and porous surface, the steel slag has certain adsorption capacity. Chemical composition are mainly CaO、SiO2.When steel slag placed in the water, it is alkaline. So the steel slag has chemical precipitation of lead ions in aqueous solution by its alkaline. The mineral composition of steel slag are mainly C2S, C3S, similar to Portland cement clinker, can be used as mixed material to prepare steel slag cement. Therefore, use the steel slag to process lead wastewater, and explore the steel slag which adsorbed lead ions to prepare steel slag cement and the feasibility of used as building materials.In order to process the high concentration wastewater containing lead, use three kinds of modified method to modify steel slag:alumina help change, heat activated, acid leaching to improve its adsorption performance, optimize the operating conditions. Compare three modified methods of steel slag to improve the performance of adsorption effect, select the best modified method. Results show that the sulfuric acid modified steel slag adsorption performance is best; the steel slag dosing amount, reaction time and reaction temperature have more influence on the results; the best dosing ratio is 1/6(lead/steel slag); adsorption equilibrium is achieved at 200 min; when temperature is less than 25℃, it has a great influence on the adsorption.The mechanism of treatment to wastewater containing lead by steel slag has been discussed by using the Adsorption Isotherm Model, the Kinetic Model, chemical precipitation theory, experimental phenomena and characterization analysis. The adsorption of lead fit the Langmuir Isotherm Model. which belongs to monolayer adsorption, and is also in line with the pseudo-second-order kinetic model. By observe experiment and analysis characterization, there are also chemical precipitation effect in the reaction process.This article focuses on solving the adsorption of lead ions slag stable, harmless, resource processing problems, preparing steel slag cement which adsorbed lead ions. Test the physical properties, XRD, SEM, hydration heat, pore structure and leaching toxicity of lead ions in the cement. The results show that:The physical properties of slag cement can meet GB175-2007 "standard of common Portland cement". When doped with 10% slag, cement strength can reach 52.5R grade. When doped with 40% slag, cement strength can reach 42.5R grade. Abnormal hydration product didn’t appear. Heavy metal ion adsorption of lead slag didn’t lead to a delay of cement hydration. Dissolution concentration in acidic and neutral environments of lead ions in slag cement can meet GB5085.3-2007"Hazardous Waste Identification Standard-Leaching Toxicity Identification" standards. |
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