Mechanism Research On The Selective Chlorination And Oxidation Of Fe₂SiO₄-Cu₂O System

There are lots of iron in most copper slags,and the content of iron is over 35%.If the iron can be recycled from copper slags and used for ironmaking,the copper slags can also be used as secondary sources.The content of copper in the recovered slag is still high.It's necessary to remove copper from the copper slags,because there is no way to remove copper in ironmaking and steelmaking process.The recovery rate of iron from copper slag is very low,for the small scale of magnetite,and the iron is mainly exists in fayalite phase.The chlorinating agent will react with copper phase in the roasting process.The Cu₂ O will be chlorinated and volatilized from the system,while the iron is still remained.By controlling the amount of O₂ and CaO in the reaction,the Fe₂SiO₄ can be oxidized and transformed into magnetic Fe₃O₄.It's a effective method to improve the grade of iron ore concentrate.Experimental methods and results are as follows:Thermodynamic analysis and TGA experiments for Cu₂O-FeCl₂ system were researched.The results shows that the chlorination of Cu in this system belongs to first-order reaction.According to the Arrhenius equation,the apparent activation energy is 89.65 kJ/mol,The results show the chemical reaction is the rate-determining step.Chloridizing rosting experiments of Fe₂SiO₄-Cu₂O system were studied.The results show that both FeCl₂ and CaCl₂ can have reactions with Cu₂ O in system.Single-factor experiments were carried out.The influences of the gas flow,the amount of chlorinating agent,calcination temperature,calcination time and preroasting or not on volatilization of chlorinated products were studied,the results show that FeCl₂ has a better effect on chloridizing and volatilization of Cu₂ O at low temperatures.Preroasting measures can significantly improve the volatilization of Cu in system at 600?.Oxidizing roasting experiments of Fe₂SiO₄-CaO system was performed.The adding of CaO is advantageous to combined with SiO₂—the decomposition productof Fe₂SiO₄,making it easier for FeO to be oxidized to magnetic Fe₃O₄.The amount of CaO shouldn't be too much,otherwise it will raise the melting point and increase the viscosity of slag.A dense mass of CaO also have negative impacts on oxidizing and precipitation of magnetite.Increasing temperature helps to improve the fluidity of melt and make the oxidation of Fe evenly.Oxidizing roasting experiments of FeO-SiO₂-CaO-Al₂O₃ system were also performed.The results show that the effect of molten slags are better than those in solid.The peroxidationof Fe is more likely to happen in air.It is necessary to control the amount of oxygen or the partial pressure of oxygen in oxidizing roasting.