Research On The Harmless Treatment And Resource Utilization Of Electrolytic Manganese Residue

With the rapid development of China's electrolytic metal manganese industry,a large amount of solid waste has been generated by various electrolytic manganese production enterprises,which is called electrolytic manganese residue(EMR).And limited by numerous factors such as excessive treatment costs and unreasonable methods in the current research,EMR is generally treated by stacking and landfilling.This treatment method is likely to cause some pollution to the local environment,thereby threatening human health.Although it has been controlled under the unremitting efforts of the government and enterprises,the waste of land resources and the reduction of land use benefits have also become one cause of the conflict between people and land.Therefore,achieving the realization of safe storage and harmless treatment of solid waste EMR in electrolytic manganese enterprises,promoting the research and industrial application of solid waste resource utilization,and pushing forward the land reclamation in mining areas,which are not only related to the green development of enterprises,also important for the attention and protection of people's livelihood and economy.The purpose of this thesis was to establish a thrifty and efficient treatment mode,based on traditional industrial technologies such as electrokinetic remediation,organic complexation and stabilization/solidification,for the existing stockpiled and freshly produced EMR.The research on manganese and ammonia nitrogen conversion,manganese and ammonia nitrogen recovery and the reuse of manganese residue in the construction industry were carried out.The main conclusions are as follows.(1)In the initial process of electrokinetic remediation of EMR using solar-cell,the charged particles in the solid-liquid phase migrated under electrochemical action,and the chloride ions migrated to the anode,which reacted to form chloric acid based on the catalytic oxidation performance of DSA;Mn²⁺and NH₄⁺in the EMR and leachate,with the ability to lose electrons,migrated in the reverse direction under the strong oxidation of chloric acid,then were converted into Mn O₂ and N₂;after electrokinetic remediation,the ammonia nitrogen and manganese concentrations in the leaching toxicity of the cathode product were reduced to 1.93 mg·L^-1 and 4.84 mg·L^-1,respectively;at the same time,due to the system used the solar-cell instead of DC power,the leachate as the electrolyte,and eliminated the regional setting of the cathode and anode,this mode was more conducive to saving energy resources and simplifying process settings than the traditional electrokinetic remediation,and more suitable for EMR in waste field for long-term remediation treatment.(2)Aiming at the fresh EMR produced during the normal production process in electrolytic manganese enterprises,it still contained 1.52 wt.%of ammonia nitrogen and2.13 wt.%of manganese,so it could be used for the recovery of manganese and ammonia nitrogen by the organic complexing agent before it was put into the waste field for remediation;the recovery abilities of the three complexing agents used were EDTA(Mn²⁺)>NTA(Mn²⁺)>CA(Mn²⁺),NTA(NH₃-N)>EDTA(NH₃-N)>CA(NH₃-N).Through the complexation reaction,more manganese and ammonium ions were precipitated in the EMR and existed in the liquid phase in a complex or free form,thereby improving the recovery of manganese and ammonia nitrogen to 93.26%and22.24%.(3)A resource utilization scheme of EMR for the preparation of building materials was proposed,which could promote for self-sale and export of EMR in the assumption.It was found that the theory and practice were feasible possibly,which the EMR was used as a composite admixture,the waste from mining and beneficiation(WMB)was used as recycled coarse aggregate for concrete,and through cement bonding to produce recycled concrete:when referring to C40 concrete strength design,the leaching toxicity of the samples were reduced,achieved the requirements of harmless treatment;but according to the change of the compressive strength of the samples,it was found that the compressive strength of the obtained recycled concrete decreased with the increase of the amount of EMR and WMB added;when 2 wt.%of cement was replaced with EMR,and 20 wt.%of gravel was replaced with WMB,the 7d compressive strength of the sample decreased to 31.40 MPa,and the 28d compressive strength was estimated to be 39.83 MPa,which nearly reached the design target requirements.But the efficient utilization method of electrolytic manganese residue in the domain of building materials needed further exploration.The above research results can provide theoretical guidance and data support for the harmless treatment and resource utilization of electrolytic manganese residue,and have important academic significance and application value.