Study On Cementation And Solidification Of Electrolytic Manganese Residue

Electrolytic manganese residue(EMR) is a kind of industrial waste with highsulphate content, small particles, high moisture and heavy metal content, which isgenerated from the manufacture of manganese. In recent years, with the rapiddevelopment of steel industry in our country, the demand of manganese is increasing,the issues of harmless disposal and resource utilization of EMR are also prominentincreasingly. Currently, due to the economic and technical reasons, most of the EMR aredeposited in landfill without any treatment, after a long time accumulation, theuntreated EMR causes serious pollution to surrounding environment. Therefore,cementation and solidification of EMR is not only a step to eliminate environmentalpollution, but also a step to sustainable development.In this thesis, the EMR was from a plant in Chongqing, In order to study EMR,various analytic methods were required to characterize its basic properties firstly.Secondly, the choice of treatment agent and its operation conditions of EMR in processof cementation and solidification were studied. At last, the mechanism of solidifiedmanganese and amminia removal was analyzed and discussed. Conclusions are asfollows:As used herein, EMR is a substance with small particles, black and mud pastepowder with a moisture content of19.8%and an average pH vale of about5.9. It ismainly composed of Mn, Si, Ca and Fe, Al, Mg, Ba etc., the percentage of them are asfollows: manganese(2.07%), silicon(15.3%), calcium(9.26%).In the process of cementation and solidification of EMR, the choice of treatmentagent and experimental conditions of EMR were discussed. It is proved that appropriatetreatment agent is trisodium phosphate, and corresponding experimental conditionswere discussed. The optimum condition is that: When addition of trisodium phosphateis5%, pH for the reaction is10.0, react50℃for4h, the leaching concentrations ofmanganese and ammonia are below the national standard(2mg/L,15mg/L), thestereoscan photographs show an obvious cemented phenomenon of manganese residueparticles.In the process of exploring mechanism of solidified manganese and amminiaremoval, simulative experiments were used to verify the process and reaction products.The reaction of simulative EMR and trisodium phosphate were simulated according to the main material proportion relationship in the preparation of EMR. XRD, IR and SEManalysis were used to compare the solidified simulative EMR and real EMR phasecomposition, chemical structure and surface morphology. After cementation andsolidification, the leaching rate of Mn2+and NH4+are decreasing in EMR. That isbecause hydrosoluble Mn2+and trisodium phosphate have generated manganesephosphate precipitate, and a double salt of manganese phosphate ammonium has beengenerated by hydrosoluble Mn2+and NH4+in process of cementation and solidification.NH3has been generated by Ammonium sulfate in EMR, while a double salt ofmanganese phosphate ammonium has been generated by NH4+in ammoniummanganous sulfate. In PO43-system, double salts such as magnesium ammoniumphosphate(MAP) and ferrous ammonium phosphate have been generated byhydrosoluble Mg2+, Fe2+and NH4+in process of cementation and solidification. Sohydrosoluble heavy metal ions and partial ammonia nitrogen are cemented andsolidified, and harmless disposal of manganese residue is achieved.