The Research Of Curing Soluble Mn²⁺ And Removing NH₃-N In Electrolytic Manganese Residue

Electrolytic manganese industry is a typical characteristics and advantages of strategic resource industry.Recent 10 years, the rapid development of electrolytic manganese industry, China’s electrolytic manganese production accounts for more than 98% of world production.Electrolytic manganese residue(EMR) is the largest and most dangerous source of pollution in electrolytic manganese industry, which is classified as general industrial solid waste (II category) in China.The EMR contains large amounts of Mn2+、NH3-N,which concentration in the leaching solution is of ten or even hundreds of times the national standard,if not handled properly,caused serious environmental pollution problems in the surrounding area of the enterprise. Therefore,The research of curing soluble Mn and removing NH3-N in EMR not only eliminate potential environmental risks,but also is an effective way for sustainable development.In this paper,author use X-ray fluorescence spectrometry (XRF),Test Method for X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), leaching toxicity analysis etc methods for characterizing and analyzing EMR samples’the basic physical and chemical properties.The results show:fresh EMR water content is 22-26%,density is 1.896g/cm3,pH value is 3-5.5;The main chemical composition are SiO2,Al203,Fe2O3CaO,MnO,MgO and SO3;Leaching toxicity analysis show:Mn2+ and NH3-N,Mn2+ concentration is up to 800-1350mg·L-1,NH3-N concentration is up to 600-900mg·L-l,the rest metal elements are no more than wastewater discharge integrated standard value (GB8978-1996);By curing Mn2+ and releasing NH3 experiment,research the effect of curing Mn2+ and releasing NH3 on the type of chemicals, added amount, two stage added,moisture content and other conditions.The results show:When adding quick lime powder amount to 5.5% or more,soluble Mn2+ concentration is below the limit of detection, the effect is very significant for curing Mn2+;When adding quick lime powder amount to 8.8% or more,the NH3-N concentration is less than 36mg·L-l,release ratio is up to 94.7%;It is best that releasing NH3-N effect when adding EMR moisture content to 27%.Through the experiment of recovering NH3-N, The results show:absorption solution of recovering NH3 gas, whose recovery rate of using dilute sulfuric acid is 33.07% higher than using water as absorbing solution; Adopting two-stage acid absorption in the way of recycling, first stage of absorption solution of recovering NH3-N is accounted for 97.33% of total recovery amount; By using gas flow rate of 0.5 m/min,the NH3 recovery amount is the highest. The release of NH3 mainly concentrated in the early N-NH3 of releasing is mainly dissolved in the water of EMR free NH3 volatilization lately; In the process of strengthening releasing and recovering NH3-N,when gas flow rate is 0.65 m/min, the total NH3-N releasing ratio is 71.47%.Thereby the soluble Mn2+ and NH3-N is no longer migrating into the environment, achieving safe disposal of EMR.