Study On Modification Of Anode Slime And Removal Of Excess Organic Matter In Zinc Hydrometallurgy System

Organic matter has become one of the key harmful impurities that currently affect the efficient operation of zinc hydrometallurgy systems.Excessive organic matter not only causes problems such as reduced current efficiency,electrolytic plate burning,and anode corrosion in zinc electrowinning,but also leads to decreased quality of cathode zinc and deterioration of technical and economic indicators.Currently,there is no specific organic matter removal process in the zinc hydrometallurgy system,making the cumulative upward trend of organic matter more obvious,leading to increasingly significant harm.In response to this situation,this article has carried out research on the modification methods of anode slime and the removal of organic substances from zinc hydrometallurgy oxygen pressure acid leaching solution and germanium precipitation solution by the modified products.Using characterization methods such as TOC,infrared spectroscopy,and gas chromatography-mass spectrometry,the effects of modification conditions and removal process parameters on the removal of organic compounds from modified anode slime were investigated,and the mechanism of removal of organic compounds from solution by modified anode slime was revealed.The theoretical calculation results show that compared to Mn（Ⅳ）,Mn（Ⅲ）has a higher redox potential and stronger oxidability.Therefore,converting Mn O₂into Mn₂O₃or Mn OOH is more advantageous for the degradation of organic compounds.The thermodynamic results of organic degradation also confirmed this point,namely,the reaction Gibbs free energy of Mn OOH and organic degradation reaction is lower,and the reverse trend of degradation is stronger.The organic substances in the acid leaching solution are mainly phenols,olefins,and esters containing benzene ring structures that remain after the preliminary decomposition of lignosulfonate.The experimental results show that the removal effect of activated carbon and unmodified anode slime on the organic matter in the acid leaching solution is not good,and the modified anode slime can effectively remove the organic matter in the acid leaching solution.Among the two modification methods,sulfuric acid has a better modification effect,and the acid to material ratio and temperature have a significant impact on the modification effect of anode slime.With the increase of the acid to material ratio,the removal effect of the obtained modified anode slime on organic matters gradually improves,and the removal rate reaches the highest when the acid to material ratio reaches 14 m L/100g.With the increase of temperature,the removal effect of the obtained modified anode slime on organic matters increases,reaching the best at 80℃;When the temperature is further increased,the removal effect decreases instead.The optimal conditions for the removal of organic compounds from the acid leaching solution obtained in the experiment are:the solid-liquid ratio of anode slime to acid leaching solution is 20g/L,the reaction time is 1 h,and the reaction temperature is 80℃.Under these conditions,the TOC removal rate can reach 57.83%.The organic substances in the solution after germanium precipitation are mainly the decomposition products of tannic acid and gallic acid.The experimental results of organic matter removal show that the removal effect of modified anode slime on organic matter is related to the phase transformation of manganese.When the proportion of oxides in the form of Mn（Ⅲ）in the modified product is the highest,the removal effect of modified anode slime on organic matters reaches the best.The TOC removal rate can reach 76.00%under the condition of roasting modification under vacuum conditions and reaching a temperature of 500℃.Modified anode slime has a good effect on phenolic,olefin,and ester organic compounds in solution.During the degradation process,the modified anode slime gradually decomposes organic macromolecules into short carbon chain small molecule organics,and even completely degrades into CO₂and H₂O.