Study On The Resource-Oriented Co-Processing Of Electroplatingsludge And Pickling Waste Liquid Based On Electrochemical Methods

With the needs of economic development,the scale of China’s metallic material surface treatment industry has been expanding year by year,and the output of its end products,electroplating sludge and pickling waste liquid,has been increasing day by day.The environment usually suffers from difficulties in the treatment of heavy-metal pollution,such as Cr,Zn,Ni,Cu in the electroplating sludge.The pickling waste liquid contains a large amount of acid,Fe and heavy metals,which is extremely corrosive.The random discharge of it will damage the ecological environment,and wasteresources.This method provides a self-designed electric device to resource-orientedco-process electroplating sludge and hydrochloric acid pickling waste liquid.The single-factor test was used to determine the optimal conditions for heavy-metal removal.The migration and transformation of heavy metals during the experiment and the basic composition of the recovered products were preliminarily studied.（1）The single-factor test of solid-liquid ratio（the mass ratio of electroplating sludge and pickling waste liquid）showed that the removal rate of heavy metals decreases with the increase of solid-liquid ratio as a whole,taking the removal effect of heavy metals per unit mass of pickling waste liquid as an indicator,35:65 was determined as the best solid-liquid ratio.（2）The single-factor test of the current magnitude showed that the increase of the energized current promoted water electrolysis and ion migration.Besides,the sediment on the cationic membrane increased rapidly,which hindered the treatment.The p H value of the anolyte in each test group was finally maintained at 1.4,and the loss of the cationic membrane increased with the increase of the energized current.Taking the comprehensive removal amount of heavy metals as an indicator,0.7A was determined as the optimal energizing current,when Cu,Cr,Ni,Zn,and Fe removal rates were 79.99%,50.11%,72.51%,45.35%and 69.30%,respectively.（3）Analysis of the migration and transformation process of heavy metals in the EK-24 group showed that different heavy metals had different migration and transformation characteristics during treatment,Cr mainly dissolved and no precipitation occurred;Cu and Zn had a large amount of dissolution in the early stage,and mainly migrated and precipitated in the later stage;Ni dissolved and partly migrated and precipitated;Fe is mainlyremoved by migration,and most of it precipitated after migration.When metal ions were precipitated in the cathode region,the rules are the same.Most of the ions were precipitated on the membrane（cathode chamber side）first.The precipitates were uneven and fell off with the progress of the reaction,and anextremely small number of ions left in the solution.The precipitation process was related to the migration process,and had no obvious relationship with the dissolution process.（4）The XRD analysis results of the recovered products of the EK-24 group showed that there was not much difference between the types of the precipitates in the cathode area and the precipitates on the membrane.The possible compounds were Zn CO₃,Fe₂O₃,Fe₃O₄,Ni S,Cu O,Cu CO₃,Cu（OH）₂,Cu₂（OH）₂CO₃ and Ca CO₃with different crystal forms.