Investigating the possibility of removing lead (Pb) from copper melt during the smelting process in Sarcheshmeh copper complex

This research focused on optimizing the removal process of the harmful element lead (Pb) in various stages of copper production (flash smelting, copper converting, and thermal refining. The present study used a factorial design of experiments to investigate the effects of various parameters, including reheating and the use of various slag-forming agents, including CaO, MgO, SiO۲, Na۲CO۳, and Na۲SO۴, on the removal rate of this harmful element. Initially, thermodynamic calculations showed that increasing the temperature does not significantly accelerate Pb removal, and the use of slag-forming agents for this purpose is essential. In the flash furnace, the results showed that adding Na۲SO۴ has the greatest effect on reducing the amount of Pb in the matte, followed by MgO. Microstructural studies of blister copper and converter furnace slag indicated that although a portion of Pb can be removed through the slag, the remaining amounts of this element in blister copper are still significant. Therefore, relying on reheating or slag-forming agents alone is not sufficient at this stage. In the matte blowing stage, the presence of slag-forming agents SiO۲ and Na۲SO۴ helped reduce Pb by forming stable compounds in the slag, and therefore, the use of this combination was introduced as an effective method for separating Pb due to the creation of favorable chemical reactions and the formation of sodium Pb silicate. In the anode furnace, SiO۲ had the greatest effect on Pb removal, and the simultaneous presence of CaO-MgO-Na۲CO۳ and MgO-Na۲SO۴-SiO۲ also produced very good results. Experimental studies and statistical analyses showed that the anode furnace is the best stage for removing the element Pb before electrolytic refining due to the process conditions. The optimal levels of slag-forming agents were also determined in this stage. The results showed that in the presence of slag-forming agents CaO-MgO-Na۲CO۳ and MgO-Na۲SO۴-SiO۲, very good results in terms of lead reduction (more than ۷۹%) were achieved. Overall, this research provided valuable information on how to remove the element Pb from copper in various stages of production and can be used to optimize copper production processes and improve the quality of the final product.

کلیدواژه ها:

Copper ، Thermal refining ، Converter furnace ، Harmful elements ، Lead (Pb) ، Flux agents