Study On Treatment And Recovery Technology Of High Concentration Manganese Sulfate Waste Liquid With Double Membranes And Three Chambers

Manganese metal smelting and electroplating enterprises will produce a large number of heavy metal wastewater with manganese sulfate as the main salt in the operation process.In addition to the increasing demand for manganese ore in recent years,the treatment and recovery of manganese from high concentration manganese sulfate wastewater is an inevitable result.Combined with the characteristics of ion exchange membrane electrolysis,such as high efficiency,low energy consumption and environmental friendliness,a new membrane electrowinning technology,double membrane three-chamber electrolysis,was used to recover both manganese metal and particulate manganese dioxide from high concentration manganese sulfate waste liquor at the same time,so as to recycle resources and alleviate the burden of wastewater treatment plant.At the same time,the benefits of the traditional single-membrane double-chamber electrowinning process under the optimal operating conditions were compared with those of the double-membrane three-chamber electrolysis process under the optimal operating conditions.For the experimental study of double-film three-chamber electrolysis,the optimum working conditions obtained by single factor experiment are as follows:under the condition that the original waste liquid Mn²⁺is 30 g/L,the distance between the electrodes is 65mm,the concentration of sulphuric acid in the septum chamber is 0.5%.Under the condition that 0.03g/L SeO₂?in the form of selenium?is put into the cathode chamber and the cathode pH is neutral,stainless steel plate cathode and titanium-based lead dioxide anode are used to make the cathode current density 3.9 A·dm^-2.The current density of the anode is 5.45 A·dm^-2.The sulfuric acid concentration of the anode solution is 1.5 mol/L.The anode solution is electrolyzed at 30?for 2 hours.The anode solution is stirred slightly regularly.The results obtained by orthogonal experiments are as follows:the influence of various factors on cell voltage is significant:anode chamber sulfuric acid concentration>temperature>current density>anode material;the effect of each factor on current efficiency of anode and cathode is significant:cathode:temperature>anode material>current density>anode chamber sulfuric acid concentration;anode:anode material>anode chamber sulfuric acid concentration>temperature>current density;each factor and anode and anode and cathode.The significant degree of energy consumption is:cathode:anode chamber sulfuric acid concentration>temperature>anode material>current density;anode:anode material>anode chamber sulfuric acid concentration>temperature>current density.Four factors have great influence on the morphology of the cathode products.Anode materials and sulfuric acid concentration have little influence on the morphology of the cathode products.Current density and temperature have great influence on the morphology of the cathode products.The results of the orthogonal experiment are similar to those of the single factor experiment.Under the optimum conditions,the cell voltage is 7.6V,the cathode current efficiency is 62.4%,the anode current efficiency is 91.6%,the cathode energy consumption is 11882 kW·h/t,and the anode energy consumption is 5117 kW·h/t.In contrast,the optimum working conditions of single-film and double-chamber obtained by single factor are as follows:in the original waste liquid Mn²⁺30 g/L,Cr18%,Ni8%and Mo2%stainless steel plates are used as cathode,titanium-coated ruthenium plate with high overpotential is used as anode,JAM-II homogeneous ion exchange membrane is used as cathode,1%dilute sulfuric acid is added into anode chamber,the current density of anode is 6A/dm^-2,and the initial electrolysis distance of anode is 45 mm.Under these conditions,the optimum conditions of the four factors were as follows:adjusting the cathode pH to 7.4,adding 0.03 g/L SeO₂ additive?in the form of selenium?,current density of 400 A·dm^-2,and experimenting at 35?cell temperature.The orthogonal experiment results show that the influence of various factors on cell voltage is significant:current density>temperature>cathode pH value>cathode SeO₂ dosage;the influence of various factors on current efficiency is significant:current density>temperature>cathode SeO₂ dosage>cathode pH value;the influence of various factors on energy consumption is significant:current density>cathode SeO₂ dosage>temperature>cathode pH value.This is basically in accordance with the optimum conditions obtained by single factor experiments.Under the optimum conditions,the cell voltage is 5.5V,the current efficiency is 85.6%,and the energy consumption is 6269kW·h/t.Finally,the economic benefits of the two technologies are analyzed in this paper.If the given waste liquor is treated and recovered,the electricity price of the product recovered by the double membrane and three chambers is slightly lower than that of the single membrane and two chambers,and the economic benefit of each working cycle is higher than that of the latter,and the total benefit of sulfuric acid recovery is basically the same.Generally speaking,the economic benefit of the new process is better than that of the single membrane and double chamber electrolysis.This paper demonstrates the feasibility of treating and recovering high concentration manganese sulfate by double-membrane three-chamber electrolysis through a large number of experiments and analysis,but it has not been studied in depth.It just uses single-membrane and double-chamber electrolysis to redesign and make a comparative analysis of the benefits of the two technologies.However,for the traditional single-membrane and double-chamber electrolysis,this research has already made a start-up and it is expected that more scholars and research groups will promote the innovation of membrane electrowinning technology in the future.