Research On Preparation Of Electroplating Sludge Ceramsite

Elestraplating sludge?ES?results in serious environmental pollution since large production,wide distribution and strong toxicity.Using solid waste to prepare ceramsite is a new approach of management,which can realize both harmless disposal and resource utilization.In this paper,ES was partly replaced clay to prepare ceramsite.Physical properties,leaching amount of chromium?Cr?,crystalline phase and microstructure of ES ceramsite were investigated in order to explore the feasibility of chromium-contained waste ceramsite and to provide the basis and guidance for further study.To detect the feasibility of chromium-contained waste ceramsite,the CrO₃ was taken as simulation of waste and the effects of CrO₃ on density,water absorption,strength and leaching test were condeucted.At the same time,principle and influence factor of solidification were also investigated.Based on these findings,ES was used to partly replace clay to prepare ceramsite,and effects of ES ratio and sintering condition on performance of ES ceramsite were researched.Results show that:1.Effect of CrO₃ on properties and leaching toxicity?1?Bulk density,particle dendity and water absorption nearly unchanged with adding CrO₃?0-3.0%?.Increasing CrO₃,cylindrical strength is decreased slightly.?2?The solidification of ceramsite on Cr is magnificent.Even CrO₃ reaching to 3%,both Cr???and Cr???are lower than 0.1 mg/L.Increasing CrO₃ amount,leaching Cr is raised and higher in acid environment compared with neutral and alkaline environment.?3?Increasing sintering temperature,Na2CO₃ and cooling speed can lower leaching Cr.Sintering temperature is crucial to solifification and should be at least 1200 ?.When Na2CO₃ is up to 2%,ceramsite shows preferable solidification.2.Principle of solidification?1?Ceramsite is composed of crystalline phase,glass phase and pores.The main crystalline phase is quartz and glass phase is increased as increasing sintering temperature,Na2CO₃ and cooling speed.?2?Glass phase is of great importance to solidification.More glass phase forms,making ceramsite denser,wrapping up Cr well and thus decreasing leaching Cr.All methods which increasing glass phase will reduce leaching Cr.3.Properties and leaching toxicity of ES ceramsite?1?Density,water absorption and strength is decreased with the ES ratio rising.But density begins to be increased when exceeding 30%ES and strength is declined by a large margin.Water sbsorption of all samples are very low,which all between 2.5%-4%.The more ES added in ceramsite,the more leaching Cr shows.?2?Between 1050? and 1150?,density is increased with increasing temperature.Above 1150?,the density is reduced.At 1150?-1200?,ceramsite shows higher strength.Increasing temperature also decreasd water aborption except a bit rise at 1250?.?3?Increasing sintering time,both water absorption and strength comes downs.With 10min,ceramsite shows lowest density.Increasing sintering time also reduces leaching Cr,but exceeding 10min,the drop is not sharp.?4?ES ratio of ES ceramsite can reach to 30%,and optimum-sintering condition should be 1200? and 10min.The performance of ceramsite can meet GB/T 17431.1-2010 and leaching Cr is below the limititon of GB 3838-2002.This work shows that preparing ceramsite with ES can realize harmless disposal and save clay resource.ES ceramsite is potential method for management and is worth further studying.