Copper Smelting Ash Alkaline Leaching Arsenic Off Pretreatment And Comprehensive Recycling Valuable Metals

On the basis of the review of arsenic secondary resources treatment and comprehensive utilization of copper smelting dusts, the technique of arsenic removal by alkaline leaching-two-stage countercurrent acidic oxidative leaching is proposed to achieve the harmless disposal of arsenic and resourcization of copper dusts. The main subjects in this dissertation are as follows:The phase analysis on copper smelting dusts was carried out by mineralogical methods such as scanning electron microscope (SEM) and the existence form of arsenic was also quantitative analyzed, which laid the foundation for the harmless disposal of arsenic and resourcization of copper dusts.The thermodynamic possibility of the separation of arsenic from valuable metals such as copper, lead and zinc was studied based on the leaching thermodynamics of copper smelting dusts in alkaline system at298K.The leaching rate of arsenic in the system of NaOH and NaOH+Na2S under the temperature ranged from303K to363K was compared. The kinetic results show that the inner diffusion is the controlling step in the leaching of arsenic in NaOH+Na2S system under the temperature ranged from303K to363K and the kinetic equation follows the unreacted shrinking core model.The technique of arsenic removal in NaOH+Na2S system under room temperature was developed and further optimized. The leaching efficiency of arsenic remains around94%and the arsenic content in the leaching residue is about0.5%～0.6%. Arsenic can be successfully separated from valuable metals such as copper, lead and zinc by this technique and the process is stable. The residual alkali in the leaching solutions can be recycled and reused after the removal of arsenic by the process of lime precipitation-flocculation settlement.The technique of two-stage countercurrent acidic oxidative leaching is further developed after the alkali leaching of arsenic and the leaching efficiency of copper and zinc can be achived at94.66%and99.06%respectively. The process is stable and the valuabe metals such as copper, zinc, lead, bismuth, indium and so on can be further highly recovered step by step.