Study On Firing Lightweight Aggregate Of Chromium Contaminated Soil

At present, chromium slag harmness is processing in many chromium salt works,some has been basically completed. With the depth of the governance of chromium slag,the residue field at the bottom and the remediation of polluted soil is also on the agenda.The article provides an overview of the research on ceramisite at home and abroad,chromium contaminated soil dry detoxification principles and the feasibility of theexperimental program.First for measuring the performance of chromium-contaminatedsoil and pulverized coal; determining the main influencing factors and the number oftest by single factor experiment; then use pulverized coal proportion, calcinationtemperature impact and of roasting time haydite heap physical and chemical propertieswith L9（34） orthogonal experimental design method, and to determine the optimalprocess parameters, by analysis of variance to determine the influencing factorssignificantly; Finally, optimum conditions roasting haydite, Determination of leachingtoxic ceramsite, strength, bulk density,1hour water absorption.Through all aspects of the study, we get the following conclusions:（1） Soil moisture content is in the range of26.2%to49.0%drying methodmeasured samples, which is larger than normal soil moisture.（2）The soil samples are small and medium-sized particles from the point of view ofparticle size analysis.（3） Soil sample contains large amounts of chromium, total chromium content is1726.3mg/kg, Cr （VI） leaching concentration is60.25mg/l, with leaching toxic but donot have the corrosive hazardous waste. Total chromium content of the different soilparticle size is extremely close. By morphological analysis that: chromium residual>weak acid extractable> reduced state> oxidisable oxidisable and weak acid extractableand reached35.7%. Chromium is easy to occur in the soil migration.（4） Chromium does not appear significant volatilization phenomenon and causesecondary pollution during the heat treatment, less than3%.（5） Coal ratio affect the ceramsite Cr（VI） leaching toxicity （when the dust contentof10%,Cr（VI） concentration of the leaching sharp decline）, the Cr（VI） leachingtoxicity master index,determine the pulverized coal ratio of10%; calcinationtemperature on ceramisite Cr（VI） leaching concentration, particle strength, bulk densityand water absorption1h have a greater impact, a comprehensive analysis of the indicators to determine the optimum calcination temperature to1100°C;when roastingtime is10min, ceramisite firing process has been completed.（6） By single factor analysis showed that the optimum calcination conditions:pulverized coal dosage10%, the calcination temperature of1100°C, roasting timeshould not exceed10minutes.（7） By orthogonal experiments showed that the main calcination temperaturefactors that affect ceramisite performance. Leaching concentration, particle strength,bulk density,1h water absorption Control of calcination temperature on the theceramsite particles strength and bulk density significantly, not significant for the rest.Calcination temperature increases within a certain temperature range is conducive toenhanced intensity of ceramisite particles and a bulk density decreases.（8） Experimental optimal firing process: coal dosage of8%, calcinationtemperature of1120°C, roasting time10min. Basic performance: the detectionceramisite performance of Cr⁶⁺ leaching concentration of0.07mg/L, the bulk densityof639kg/m³, the strength of695N,1h water absorption of8.3%, better than the resultsof orthogonal experiment. Other performance to meet the standard requirements of lightweight aggregate, heavy metal leaching low toxicity, and environmental security.