Study On Refining Cycle Process Of Copper Electrolyte For Arsenic Removal And Its Safety Evaluation

During the copper electrolytic refining process,excessive arsenic content in the copper electrolyte will cause problems such as rough crystals and deep stripes on the surface of the copper cathode,which will seriously affect the quality of the cathode copper and also affect the normal operation of electrolysis process.Therefore,the control or removal of excess arsenic in copper electrolyte has a great significance.This paper proposes a copper electrolyte dearsenic refining cycle process:cooling to crystallize copper,and then by dosing the arsenic-removed copper sulfate crystals in separate area to replenish the crystallized copper sulfate crystals the electrolysis ensured the copper concentration to be within the optimal concentration range.This technique lowered power consumption and provided a safe and environmentally friendly way of purification and removal of arsenic.In copper electrolyte cooling crystallization experiment,the cooling crystallization process is studied.The appropriate process conditions were obtained:the sulfuric acid concentration in the copper electrolyte was 370g/L,and the cooling temperature was 10?.Under this experimental condition,the copper concentration in the crystallization solution droped from 36g/L to 12g/L,and the arsenic concentration drops from 40g/L to 39g/L.In electrolytic arsenic experiment,the influence of electrode material,sulfuric acid concentration,current density and electrolysis temperature on the electrolysis process was studied.The best process conditions for arsenic removal after crystallization were determined:the cathode material was copper,and the sulfuric acid concentration was 370g/L,The current density was 500A/m²,and the electrolysis temperature was 40?.Under these experimental conditions,the removal rate of arsenic reached 65.83%,and the concentration of arsenic in the liquid after purification dropped to 13.67g/L which was lower than the production design value(15g/L).In the process of electrolysis of arsenic,the concentration of copper ions determines the reaction sequence and specific reaction process of the electrolysis process,and also determines the type of cathode reaction product.As the electrolysis progresses,first the arsenic acid in the copper electrolyte is reduced to arsenous acid,and then the Cu²⁺concentration continues to decrease especially when it droped to a certain concentration range,the discharge potential of Cu²⁺also decreased,so that As and Cu Together they precipitated at the cathode to form an arsenic-copper alloy.At the end of electrolysis,due to the severe lack of Cu²⁺,a large amount of H₂ and As H₃are produced,and the current efficiency is rapidly reduced,resulting in a great environmental risk.Based on the PHA-LEC method,the safety assessment of the copper electrolyte dearsenic refining cycle process was carried out.The potential hazards in the process were flammable and explosive,poisoning and suffocation,corrosive substances,electric shock,falling from height,mechanical damage,high temperature scalds Class,its hazard grade was?-?,coming from flammable,explosive,poisoning and suffocation.The copper electrolyte purification system should be based on the safety countermeasures proposed by the PHA-LEC method for safety prevention and control.The PHA-LEC method provides a new model for the safety analysis of the copper electrolyte purification system.