| Abstract:The present study aims to characterize the variation of the product and process conditions of zinc-iron separation in Zn-Fe(Ⅱ)-SO42--H2O system by hydrothermal process, due to the importance of such information to the metallurgical industry. Using the hot-acid leaching pregnant solution as the raw material, technical studies on arsenic removal by sulfide precipitation and separation between zinc and iron by hydrothermal process were carried out, respectively.The experimental results of arsenic removal by sulfide precipitation, which was analyzed by the range analysis process, show that the consumption of Na2S> reaction temperature> sodium sulfide charging time, which represents the effects of different factors on the ratio of arsenic removal. The optimum conditions were determined as follows:reaction temperature of30℃, sodium sulfide charging time of45min and the consumption of Na2S is11.55g per liter solution. Under above mentioned optimum conditions, the average removal ratio of arsenic could reach99.86%. What’s more, the removal ratio of copper and cadmium could reach99.66%and84.52%, apparently. The sulfide precipitation is an effective process for removing impurities in the solution.Research on the separation between zinc and iron mechanism in the zinc leach solution by hydrothermal process has been investigated, in which the solution was treated by arsenic removal and traditional purifying technology. The experimental results show that the reaction temperature is the most important factor in this study, when the stirring rate was fixed at800r/min, oxygen pressure was fixed at2.0MPa. Firstly, the goethite was obtained below150℃, then the hematite was formed at150℃. Furthermore, the hematite was obtained as the final products, when the reaction temperature was raised above180℃. Besides, the phase composition of products at different solution pH value is changed obviously. Some complex mixtures, like sulfate hydrate of iron, were formed within pH<1.0, and hematite was obtained at pH>1.0. Although, the reaction time has little influence on the products structure, the crystallization property and morphology of products could be effected under different duration.The process of separation between zinc and iron by hydrothermal process has been investigated. The optimum conditions were determined as follows, when the stirring rate was fixed at800r/min, oxygen pressure was fixed at2.0MPa:the minimum reaction temperature is180℃, pH≥1.0,1h. Under above conditions, the ratio of iron-precipitation could reach95%, and the spherical nanometer hematite could be obtained. |
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