Research On New Process And Mechanism In Low-temperature Molten Salt Smelting Of Jamesonite

Jamesonite(Fe Pb₄Sb₆S₁₄)is a complex antimony lead sulfide mineral.China is the largest producer of jamesonite,mainly concentrated in the Hechi Nandan area of Guangxi.The smelting methods of jamesonite are divided into two types:hydrometallurgy and pyrometallurgy.Currently,most smelting methods are pyrometallurgy.However,there are many problems in the pyrometallurgical process,such as high energy consumption,large pollution,and cumbersome steps.With the proposal of the concept of green development in heavy industry,there is an urgent need for a low-temperature,clean,and convenient smelting method of jamesonite.In this paper,using zinc oxide as a sulfur fixing agent,carbon powder as a reducing agent,and sodium carbonate sodium chloride as a mixed molten salt,the antimony lead alloy was prepared by smelting the molten salt of jamesonite.The possible reactions of jamesonite and associated minerals in molten salt were analyzed by thermodynamics,and verified by XRD,TGA,and other methods.The results show that when the temperature rises to 600℃,Fe Pb₄Sb₆S₁₄ decomposes to form Pb S,Sb₂S₃,and Fe S;Displacement reduction reaction occurs in Sb₂S₃-Zn O-C system at 682～756℃;The reaction also began to occur in the Pb S-Zn O-C system when the temperature rose to883℃.A single factor experiment was conducted on the smelting of jamesonite in molten salt,and the optimal process parameters were determined.Under the conditions of smelting temperature 900℃,smelting time 90 min,adding zinc oxide with a mass of1.05 times the mass of the concentrate,carbon powder with a mass of 0.3 times the mass of the concentrate,molten salt with a mass ratio of 3 times the total mass of the concentrate,Zn O,and carbon powder,and sodium carbonate sodium chloride with a mass ratio of 6:4,the direct yield of antimony lead alloy can reach 79%,and the mass fraction of antimony in the antimony lead alloy is 41.48%,The mass fraction of lead is46.21%.The reaction behavior of associated minerals such as Fe compounds in jamesonite lead concentrate during molten salt smelting was investigated.The results showed that Fe S₂ reacted at 700℃to form Fe S and Na₂S;Under 800℃,Fe S reacts with Zn O and carbon powder to form elemental Fe through oxidation and reduction,and the temperature rises to 900℃,where Fe is oxidized to Fe₂O₃ and Fe₃O₄.S in Fe S and Fe S₂ ultimately exists as Zn S and Na₂SO₄.During the solidification process of antimony lead alloy,slag impurities are gradually discharged from the liquid phase of antimony lead alloy,and some slag such as Zn S and Fe adhere to the surface of antimony lead alloy.An attempt was made to electrolyze the antimony lead alloy obtained by smelting in a low eutectic solvent to prepare antimony lead.Using choline chloride ethylene glycol as a eutectic solvent,the antimony recovery was 26.62%and the antimony mass fraction was 99.57%at a current density of 60 m A·cm^-2 and an electrolysis time of 8 h;Lead was prepared using acetamide glycol as a low eutectic solvent under the conditions of current density of 6 m A·cm^-2 and electrolysis time of 8 h.The lead recovery was 25.39%and the lead mass fraction was 99.24%.In this paper,the binding force of Zn and S is greater than that of Sb and Pb and S,so that S in metal sulfides is fixed in the form of Zn S,avoiding the production and emission of SO₂;Using sodium carbonate sodium chloride as a molten salt provides a weak alkaline environment for the reaction system,effectively reducing the reaction temperature.In general,the oxidation reduction reaction is completed at one time,reducing energy consumption,and simplifying the process steps.It is a low temperature,clean,and efficient new process for smelting jamesonite.