Recovery And Utilization Of Lead In Lead-Containing Waste Residue From Electrolytic Manganese Production

As a metallurgical and chemical raw material,electrolytic manganese is an important strategic resource.At present,China has become the world’s largest producer,consumer and exporter of electrolytic manganese.However,with the rapid development of the electrolytic manganese industry,the correct disposal of anode slime has become a serious problem.At present,most enterprises only store electrolytic manganese anode slime as hazardous waste,which will cause environmental pollution and waste of resources.In recent years,some companies have used hydrogen peroxide to leach manganese from electrolytic manganese anode slime,and the tailings are rich in lead,and there is still no good treatment method.The purpose of this experiment is to reduce the occupation of land resources by the lead-containing waste residue of electrolytic manganese,reduce the pollution caused by the lead-containing waste residue to the environment,reduce the production cost of enterprises,and provide a reference for the research on the treatment technology and resource utilization of lead-containing waste residue in my country.In this experiment,a special process was studied for the composition characteristics of lead-containing waste residues produced by electrolytic manganese.The acid leaching-enrichment-membrane electrolysis process was used to recover the lead in the lead-containing waste residues of electrolytic manganese and to recover the acid,so as to maximize the utilization of resources.In this experiment,the ground,sieved and dried lead-containing waste residues were subjected to acid leaching,and the effects of the type of leaching solution,solid-liquid ratio,leaching time,leaching solution concentration and leaching temperature on the leaching effect of lead-containing waste residues were investigated respectively.The results show that the main component of lead-containing waste residue is PbSO₄,which can undergo complex reaction with HNO₃;an appropriate amount of leaching solution can fully react with lead-containing waste residue;increasing the concentration of NO₃^-ions in the leaching solution can significantly increase the leaching of lead from lead-containing waste residue At the same time,in a certain temperature range,the complexation constant of the complex increases with the increase of temperature.To sum up,the optimal leaching conditions of electrolytic manganese lead-containing waste residues are as follows:using 2mol/L HNO₃ as the leaching solution,the solid-liquid ratio is 4g/L,and the leaching temperature of Pb²⁺is leaching for 70min at 80℃.The best effect was obtained.At this time,the concentration of Pb²⁺in the solution was 2456.76 mg/L,and the leaching efficiency was 85.7%.Then,the acid leaching solution of lead-containing waste residue was used as the initial solution,and the ion exchange column was filled with pretreated 732 H-type cation exchange resin to enrich and concentrate Pb²⁺.The flow rate,pH value,resin layer height,initial Pb²⁺were investigated respectively.The adsorption effect of parameters such as concentration on Pb²⁺,and then the enrichment of Pb²⁺was achieved through the resin elution regeneration experiment.The experimental results are as follows:the appropriate flow rate is very important for the adsorption of Pb²⁺;when the pH is too low,too much H⁺will compete with Pb²⁺,while too high will form Pb（OH）₂ precipitation;the ion exchange resin has a higher concentration of Pb²⁺.When the concentration is low,the adsorption amount is less,but the adsorption rate is high.With the increase of the concentration,the adsorption rate shows a downward trend,but the adsorption amount increases greatly.Therefore,the optimal conditions for the adsorption of Pb²⁺on the ion exchange column are as follows:the flow rate is 9 m/h,the pH is 4.0,the height of the resin layer is 80 cm,and the initial Pb²⁺concentration is 150 mg/L.At this time,the Pb²⁺adsorption rate can reach 93.3%.Subsequently,2L 3mol/L HNO₃ solution was used to elute Pb²⁺,the concentration of Pb²⁺after enrichment could reach 33.8g/L,and the elution efficiency was over 99%.Finally,the enriched Pb²⁺solution was used as the catholyte,and the dilute nitric acid was used as the anolyte to carry out the experiment of recovering lead by membrane electrolysis.The lead plate was used as the cathode,and the best anion exchange membrane and anode electrolysis material were selected,and then the lead was recovered respectively.Rate,acid recovery rate,current efficiency,voltage and electric energy consumption were used as the inspection indicators,and factors such as Pb²⁺concentration,current density,electrolysis reaction temperature,catholyte pH,anolyte HNO₃ concentration,and catholyte ammonium nitrate concentration were investigated to analyze the experimental results.In this way,the optimal membrane electrolysis process parameters are determined.The test results are as follows:Firstly,it is determined by test that TRJAM-10W is an anion exchange membrane and titanium-based ruthenium-iridium is an anode material.In subsequent experiments,it was found that the Pb²⁺concentration and current density had a greater impact on the current efficiency and acid recovery rate,and the acid recovery rate was more dependent on the reaction temperature and the anolyte HNO₃ concentration;the appropriate catholyte pH is also crucial.If the pH is too low,a more intense hydrogen evolution side reaction will occur on the cathode,and H⁺and Pb²⁺will form a competitive relationship,which will affect the precipitation of lead.If the pH exceeds 4.0,Pb（OH）₂ will be precipitated.By adding ammonium nitrate to the catholyte,the voltage and electric energy consumption can be greatly reduced,and the quality of the recovered lead can be improved.On the whole,it is determined that the optimal process parameters for the recovery of lead by membrane electrolysis are:Pb²⁺concentration of 40g/L,current density of 30m A/cm²,reaction temperature of 60℃,catholyte pH value of 4.0,anolyte HNO₃ concentration of 0.5 mol/L,and the concentration of ammonium nitrate in the catholyte was 50 g/L.Under the optimal conditions,the current efficiency is 85.6%,the acid recovery rate is 73.03%,the lead recovery rate is 99.2%,the voltage is 3.8V,and the power consumption is 1148.4kW·h·t^-1.Through the SEM and XRD analysis of the lead recovered from the cathode under the best conditions,it is concluded that the lead recovered by electrolysis is leaf-like,formed by irregular stacking layer by layer,with silver-white metallic luster as a whole,and the surface of the metal lead is smooth and compact.crystal structure.The electrolysis product is pure lead,but there is a small amount of PbO formed after the metal lead is oxidized in the air.Through the three steps of acid leaching-enrichment-membrane electrolysis,the lead-containing waste residue of electrolytic manganese can recover 78.53%of Pb²⁺in the original lead-containing waste residue in the form of metallic lead,and the HNO₃ recovered in the anode chamber can also be recycled in acid again Used in the leaching process,while solving the problem of environmental pollution caused by lead-containing waste residues,it realizes the recycling of resources,and has good social and economic benefits.