Study On The Treatment Method Of Ammonia-nitrogen From Electrolytic Manganese Residue

There were a lot of electrolytic manganese residue?EMR?which from electrolytic metal manganese?EMM?production process,and the chemical compositions of it were complex and diverse.Among them,the chemicals that can bring great harm to the environment are manganese ion and ammonia nitrogen.In order to reduce the impact of ammonia nitrogen on the ecological environment,it is necessary to find a suitable method for ammonia nitrogen treatment.Based on this,it is necessary to find a suitable treatment method of ammonia nitrogen.In this paper,the effect of electric field on the physical and chemical properties of EMR,electrochemical method,electrochemical method combined with curing manganese ion,CO₂ solidification of manganese and recovery of ammonia nitrogen were used to remove ammonia nitrogen.By X ray diffraction,X ray fluorescence spectrometer,scanning electron microscopy,atomic absorption spectrometer,surface analyzer,electrochemical workstation,and spectrophotometer,the structure and composition of EMR before and after treatment,and the relevant mechanism were deduced.The main contents and conclusions are as follows:?1?Learned from the influence of electric field on the physicochemical properties of EMR,the particles and the permeability increased,the chemical composition of Fe,Mn and Mg decreased,and the mineral phase of Mn2+ and NH4+-N transformed from insoluble salts to soluble salts under electric field.?2?The process conditions and oxidation mechanism of electrochemical oxidation of ammonia nitrogen of EMR were studied.Under the optimum conditions,such as solid to liquid ratio of 1:20?mass ratio?,chloride ion concentration of 200 mg / L,voltage of 20 V,and pH =5 or 10,the removal rate of ammonia nitrogen can reach 98.57%.In the process of electro-oxidation,ammonia nitrogen became to nitrogen and nitrate nitrogen,and chloride produced active chlorine.?3?Through the study of the influence of coexisting ions on the removal of ammonia nitrogen,it was found that the inhibition of manganese ions,so the curing method of manganese ion was studied in the process of removing ammonia nitrogen.By comparing the experimental results of quicklime,sodium phosphate,sodium silicate and sodium carbonate,the sodium carbonate had the high cure rate of manganese ion and low removal rate of ammonia nitrogen.When the mass ratio of sodium carbonate and EMR was 0.05,the cure rate of manganese ion was up to 99.12%.The main components of the reaction between EMR and sodium carbonate are manganese carbonate,magnesium carbonate and calcium carbonate.After the manganese ion was solidified,the ammonia nitrogen degradation rate could reach 97.14% by electro-oxidation.?4?The reaction conditions and reaction mechanism of carbon dioxide curing manganese ions and recovery of ammonia nitrogen were studied.Under the optimum reaction conditions,carbon dioxide flow rate of 60 m L/min,calcium oxide content of 6 g,stirring rate of 30 r/min,the removal rate of manganese ion reached 99.43%,the ammonia nitrogen removal rate reached 99.32% after 15 min.With carbon dioxide,the manganese ion formed for Mn?OH?₂,Mn₃O₄,MnCO₃,ammonia nitrogen can form sodium carbonate / sodium bicarbonate.