| A large amount of acid sludge is produced during the non-ferrous smelting process,which is a hazardous waste due to its highly toxic metal mercury.According to the mercury content,mercury-containing acid sludge can be divided into high-mercury acid sludge(mercury content greater than 10%)and low-mercury acid sludge(mercury content of 0.5-2%).Among them,wet leaching reduction technology is the main recovery technology for mercury-containing acid sludge.Based on this,this topic focuses on the wet leaching process of mercury in low-mercury acid mud,and uses ICP-OES,XRD,XPS and other methods to analyze the element content,material composition and main metal valence state in low-mercury acid mud;The key process parameters that affect the mercury leaching efficiency in the mercury leaching process in the low-mercury acid slime were explored in the previous section.Leaching efficiency of elemental mercury and its application in industrial practice.The specific results are as follows:(1)The low-mercury acid mud needs to be obtained by on-site sampling and analyzed after simple treatment.The results show that most substances in the lowmercury acid mud have no obvious X-ray diffraction phenomenon,and the crystalline material is not obvious;at the same time,The valence states of the substances in the low-mercury acid mud are stable and present in the stable valence states in nature.(2)The applicability of wet acid leaching and wet alkali leaching process to low mercury acid mud was systematically compared,and the wet acid leaching process of sodium chlorate hydrochloride was selected,and the concentration of hydrochloric acid,liquid-solid ratio,and sodium chlorate dosage were explored.The influence of factors such as addition amount(Mass ratio meter with low mercury acid sludge),reaction time and reaction temperature on mercury leaching efficiency of low mercury acid mud.On this basis,the factors that have a great influence on the mercury leaching rate of low mercury acid mud are screened out.Under the process system,when the concentration of hydrochloric acid is 158.637 g/L,the liquid-solid ratio is 2,and the specific gravity of sodium chlorate is 8.396%,the highest leaching rate of mercury in the low-mercury acid mud is 99.205%.(3)The kinetics of mercury leaching process of low-mercury acid sludge in the sodium chlorate wet acid leaching system was studied.The whole reaction process approached the peak leaching rate at about 8 min,and then the mercury leaching rate did not increase significantly.The Arrhenius equation curve was drawn according to isotherm fitting at 30,40,and 50 °C,and the kinetic equation of mercury leaching was calculated.(4)The results of industrial practice found that in the process application before optimization,the mercury leaching rate was 92.00%,and the mercury recovery rate was90.14%;while in the post-optimization process application,the mercury leaching rate was 94.21%,and the mercury recovery rate was 92.43%..The mercury leaching rate was optimized and applied by optimizing and applying the process and process parameters.The mercury leaching rate was increased by more than 2% by using the sodium chlorate wet acid leaching process,and the final mercury recovery rate was increased by 2.29%.Project income can be increased by 300,000 yuan/a.In summary,the research results of this topic can provide data support and theoretical guidance for improving the recovery efficiency of subsequent mercury reduction and precipitation. |
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