| Black copper sludge is a by-product of the electrolyte purification and electrowinning process in the copper electrolytic refining process,which mainly contains Cu,As,Sb,Bi,Ni,Te and other elements and is classified as hazardous solid waste by the state.At present,the traditional treatment technology of black copper sludge includes oxidation roasting,wet leaching,combined fire-wet leaching and other methods,but there are problems such as high production energy consumption,long process flow,high cost,easy to produce toxic gas,low arsenic removal rate and difficulty in copper recovery.In order to achieve the efficient and recycling of solid waste resources,this paper proposes an oxygen-pressure alkaline leaching process to treat black copper mud,draws the Eh-p H diagram of the Cu-As-H2 O system under high temperature and pressure,carries out thermodynamic calculations of the main chemical reactions in the oxygen-pressure alkaline leaching process of black copper mud,and explores the transformation behaviour of copper and arsenic in black copper mud during the oxygen-pressure alkaline leaching process;and optimises the process parameters through controlled conditions,combined with modern The kinetic behaviour of arsenic leaching from black copper mud in the oxygen-pressure alkaline leaching system was investigated,and the control steps in the leaching process of arsenic were identified.The main research contents and conclusions of the thesis are as follows:(1)Thermodynamic analysis of the black copper clay oxygen-pressure alkaline leaching process was carried out,Eh-p H diagrams of the Cu-As-H2 O system were calculated and plotted at different temperatures and different oxygen partial pressures,the transformation behaviour and change trends of the Cu-As phases in different temperature intervals and oxygen pressure ranges during the oxygen-pressure leaching process were investigated,and the feasibility of one-step separation of Cu and As in black copper clay oxygen-pressure alkaline leaching was analysed.The thermodynamic analysis showed that in the Cu-As-H2 O system,the ΔG of the main chemical reactions in the oxygen-pressure alkaline leaching process of black copper clay was <0 when the temperature was controlled to be in the range of373k~448k and the partial pressure of oxygen was in the range of 0.3Mpa~1.1Mpa,and the copper-arsenic phase could react with sodium hydroxide to form Na3 As O4 and Cu O(Cu2O).(2)The experimental study of the oxygen-pressure alkaline leaching process of black copper mud was carried out,and the effects of different process parameters on the separation effect of copper and arsenic and the transformation pattern of copper and arsenic phases were investigated by combining XRD,SEM and other analytical means,Under these conditions,the leaching rate of arsenic was 99.31%,while the leaching rates of copper,antimony and bismuth were only 0.87%,2.39% and 1.18% respectively,the efficient open circuit separation of arsenic was achieved.After comparison experiments,compared with the atmospheric pressure oxidation alkali leaching process,the black copper mud oxygen pressure alkali leaching process has the advantages of efficient separation of copper and arsenic,low alkali consumption and environmental protection.(3)A study on the kinetics of arsenic in the oxygen-pressure alkaline leaching process of black copper clay was carried out.The kinetic model and the limiting steps of the reaction rate were determined by the kinetic theory of black copper clay leaching,and the results showed that: the kinetics of arsenic leaching was in accordance with the JMA model,and the oxygen-pressure alkaline leaching process of arsenic was controlled by chemical reactions,and factors such as reaction temperature,sodium hydroxide concentration,oxygen partial pressure and liquid-solid ratio would affect the leaching of arsenic during the leaching process.However,the oxygen partial pressure and reaction temperature had the most significant effect on the leaching rate of arsenic.The apparent activation energy of the leaching reaction of arsenic was 22.132 k J/mol calculated from the leaching kinetic equation,and the values of the apparent steps of sodium hydroxide concentration,oxygen partial pressure and liquid-solid ratio in this control process were 0.25,0.46 and-0.63 respectively,and the kinetic equation of the leaching reaction was... |
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