Harmless Treatment And Resource Utilization Of Electrolytic Manganese Residue

Electrolytic manganese residue(EMR),produced from filtering the sulfuric acid leaching solution of rhodochrosite,is a kind of solid waste that contains highly concentrated manganese and ammonia nitrogen.With the rapid development of electrolytic manganese industries,the need of EMR is increasing fast,posing serious threats to the environment.At present,there is no any effective treatment to solve this problem,resulting in most of EMR waste deposited in the open air.Therefore,comprehensive utilization of EMR can not only fundamentally solve the environmental pollution,but also create economic value to a certain extent,which is a sustainable way.Here,this work proposed and studied a whole process for harmless treatment and resource utilization of EMR,including leaching,intensified precipitating,ammonia nitrogen removing,and wastewater recycling.Through characterization,the manganese content of the studied EMR from a plant was determined as 3.18%,and the total manganese and ammonia nitrogen exceeded the standard amounts by 453 times and 26 times,respectively.After washing with water for four times,77.48%of soluble manganese ions in the EMR could be washed out.Then the residue could be rendered harmless after further manganese fixation and deamination treatment.An intensified precipitating method was proposed to precipitate the manganese ions in the leaching solution of EMR with precipitant P-1 or P-2,where the precipitation was accelerated by the additive A-3.After 10 min,the recovery rate of manganese ions reached 99.9%.And the content of manganese in the precipitated solid was more than 60%,up to 67.6%,which could be used as a rich manganese resource for further utilization.In the continuous manganese fixation experiment,the self-built continuous manganese fixation device was adopted.After continuously treating 13 L leaching solution of EMR for 2 h,the manganese ions in the solution were almost completely recovered and the manganese content in the product was about 60%,suggesting that the continuous operation was feasible.The ammonia nitrogen removal in the wastewater was employed by catalytic ozonation and the removal rate could be up to 86%.When the pH of the system was kept between 7 and 8 at 60? for 6 h and the O3 flow rate was 7.2?10.4 mg/min,the concentration of ammonia nitrogen could be reduced from 1000 mg/L to below 350 mg/L.After reusing the wastewater for three times,the recovery rate of manganese ions was more than 99%,and the content of manganese in the obtained precipitated solid still remained at about 60%for resource utilization.