| Electrolytic manganese residue is a high-water-content industrial waste produced in the process of electrolytic manganese metal production.So far the electrolytic manganese residue is over 120 million tons in China.Electrolytic manganese residue contains a large amount of manganese and ammonia nitrogen,which not only leads to a waste of resources,but also forms easily the leachate to pollute the surrounding environment.In addition,the presence of high water content in electrolytic manganese residue will take away part of manganese sulfate and ammonium sulfate,which will cause manganese loss.Therefore,it's a great challenge for electrolytic manganese industry to control the water content of newly discharged electrolytic manganese residue and to treat harmlessly the electrolytic manganese residue that have been stored for a long time.In this paper,aiming at the problems of disposing harmlessly and controlling water content of electrolytic manganese residue,the research on methods of conversion,removal,migration and enrichment of manganese and ammonia nitrogen in electrolytic manganese residue were carried out based on electrokinetic remediation and its strengthening technology.Meanwhile,the leaching process of manganese ore was regulated by surfactant,and the control method of water content in electrolytic manganese residue was explored.The research results are as follows.?1?In the experiment,the direction of H+,manganese and ammonia nitrogen removal were from anode to cathode,which was consistent with the direction of electroosmosis and electromigration.Under the pulsed electric field,the removal rate of soluble manganese in electrolytic manganese residue increased from 41.21%to 45.57%compared to the direct current?DC?electric field,only F1?acid extracted state?manganese was effectively removed,and the removal rate of ammonia nitrogen increased from 33.32%to 36.21%.Under the citric acid+pulsed electric field system,the removal rate of soluble manganese increased to 94.74%.Then,most of the F3?oxidizable state?and F4?residual state?manganese in electrolytic manganese residue were converted to F1?acid extracted state?or F2?reducible state?.In addition,the ammonia nitrogen removal rate reached 81.11%.Under the SDBS+citric acid+pulsed electric field system,the removal rate of ammonia nitrogen increased to 84.70%.?2?The removal mechanism of manganese and ammonia nitrogen in electrolytic manganese residue is mainly electromigration and electroosmosis.Among them,the main mechanism was electromigration,and electroosmosis played a secondary role.In the‘sodium dodecyl benzene sulfonate?SDBS?+pulse electric field'system,the EOF from 160 mL to 225 mL compared with the condition without the pretreatment agent,which strengthened the electroosmosis effect of the experimental process.In the‘citric acid+pulse electric field'system,the current density from 11.0 mA/cm2 to 15.0mA/cm2,and the electromigration hasbeen strengthened.?3?Under DC and pulsed electric field,part of?NH4?2Mn?SO4?2·6H2O was transformed into?NH4?2Ca?SO4?2·H2O in the electrolytic manganese residue.Part of?NH4?2Mn?SO4?2·6H2O decomposed MnSO4·H2O and?NH4?2SO4 under pulsed electric field.In‘SDBS+pulsed electric field'and‘EDTA+pulsed electric field'systems,the phase of the manganese residue did not change significantly.However,in‘citric acid+pulsed electric field'system promoted the transformation of?NH4?2Mn?SO4?2·6H2O to?NH4?2Ca?SO4?2·H2O.In the microscopic morphology of electrolytic manganese residue,the columnar structure of the electrolytic manganese residue became smaller,and no obvious damage occurred on the surface of electrolytic manganese residue after the treatment of‘SDBS+pulsed electric field'.After the treatment of‘EDTA+pulsed electric field',many obvious pores appeared on the electrolytic manganese residue particles.The columnar and sheet-like structures were corroded and destroyed,and many small needle-like structures appeared after the treatment of‘citric acid+pulsed electric field'.?4?During the leaching of manganese ore,1.5 mmol/L sodium dodecyl benzene sulfonate,1.25 mmol/L dimethyl silicone polymer and 1.25 mmol/L triton X-100 were added to investigate the effect of surfactant on the microstructure of manganese residue.It is found that three kinds of surfactants are beneficial to the reduction of flake structure in manganese residue,and the microstructure of manganese resiude particles tends to be consistent.The order of the effects of the three surfactants on reducing the moisturecontentoftheelectrolyticmanganeseresiduewas:sodium dodecyl benzene sulfonate>dimethyl silicone polymer>Triton X-100. |
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