Separation Mechanism And Process Of Antimony And Bismuth In HCl-NaCl Complex System

Antimony and bismuth are important strategic metals in China.It is of great significance to ensure the balanced supply of antimony and bismuth.In recent years,with the decrease of antimony and bismuth ore,the byproducts containing antimony and bismuth produced by copper and lead smelting,such as copper anode slime,have gradually become important raw materials for the extraction of antimony and bismuth.Based on the new process of H₂SO₄-HCl-NaCl composite leaching of copper anode slime proposed by our research group,in order to efficiently separate antimony and bismuth from copper anode slime composite acid leaching solution by hydrolysis,the mechanism of hydrolysis separation of antimony and bismuth in this complex system was systematically studied in depth.The E-p H diagram of antimony and bismuth was plotted by thermodynamic calculation.The results show that antimony is hydrolyzed prior to bismuth,and effective separation of antimony and bismuth can be achieved by controlling certain p H and potential.It is found that Sb₄O₅Cl₂ and Bi OCl are easily generated by the hydrolysis of antimony and bismuth in HCl-NaCl system.With the increase of the initial Cl^-concentration in the solution,the p H of both the starting point and the end point of the hydrolysis of antimony and bismuth increase.The experimental results are consistent with the theoretical analysis.In the Sb-Bi-Cl-H₂O system,when the solution p H is 1.0,the hydrolysis temperature is 25°C,and the hydrolysis time is 30 min,the separation effect of antimony and bismuth is better,and the hydrolysis rate of antimony and bismuth is98.78%and 8.49%,respectively.In the Bi-Cu-Pb-Cl-H₂O system,when the p H of solution is 2.5,the hydrolysis temperature is 25°C,and the hydrolysis time is 60 min,the separation effect of bismuth and copper is better,but the lead will partially enter the precipitation.The hydrolysis rates of bismuth,copper and lead are 99.61%,5.37%and 63.59%,respectively.In the Sb-Bi-Cu-Cl-H₂O system,when the solution p H is1.0,the hydrolysis temperature is 25°C,and the hydrolysis time is 30 min,the separation effect of antimony from bismuth and copper is better.The hydrolysis rates of antimony,bismuth and copper are 99.00%,11.29%and 5.33%,respectively.In the Sb-Bi-Cu-Pb-Cl-H₂O system,when the solution p H is 1.0,the hydrolysis temperature is 25°C,and the hydrolysis time is 60 min,the separation effect of antimony from bismuth and copper is better.However,some lead falls into the precipitation,and the hydrolysis rates of antimony,bismuth,copper and lead are99.10%,13.90%,5.22%and 39.54%,respectively.Based on the study of the hydrolysis rule of antimony and bismuth in HCl-NaCl system,the antimony and bismuth in the leaching solution of copper anode slime H₂SO₄-HCl-NaCl were separated.At p H 0.5,hydrolysis temperature 25°C and hydrolysis time 60 min,the hydrolysis rates of antimony and bismuth are 98.73%and4.69%,respectively.After antimony precipitation,the solution was adjusted to p H 2.5,hydrolysis temperature 25°C and hydrolysis time 30 min.The hydrolysis rate of bismuth reached 99.72%.At the same time,some lead and a small amount of copper entered the bismuth precipitation.Therefore,high efficiency separation and recovery of antimony and bismuth can be achieved by controlling certain hydrolysis conditions.