高硅锌矿高温酸转化沉硅基础理论及工艺研究

【作者】 徐红胜；

【导师】 魏昶；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2014， 博士

【摘要】 随着优质锌矿资源的日益枯竭,在我国分布较为广泛的难选难冶高硅锌矿资源的开发利用越来越受到人们的重视。发展高硅锌矿全湿法炼锌的工艺方法对于提高我国湿法炼锌工艺水平,扩大可供矿源有重要意义。因此,探索解决高硅锌矿酸浸矿浆中可溶硅带来的矿浆过滤难问题的方法以及实现锌与硅的高效分离已成为该领域的关键课题之一。本论文从高硅锌矿中随锌一同浸出进入溶液的H4Si04入手,围绕依据酸性体系中H4Si04的高温热力学性质使其在胶凝前转化成易过滤SiO2沉淀的思路展开研究工作,以不同类型高硅锌矿为研究对象,以优化酸性体系中锌与硅高效分离的高温酸转化环境和提高锌浸出回收率为目的,对高硅锌矿高温酸转化基础理论和调控技术进行研究,为解决高硅锌矿在常规湿法炼锌中酸浸矿浆液固分离难的问题并为实现高硅锌矿的工业化应用奠定基础。本论文开展的主要研究工作及研究成果如下：(1)采用化学物相组成、XRD、SEM-EDS等分析手段对三种不同类型的高硅锌矿—异极矿、硅锌矿和高硅硫氧混合锌矿进行了工艺矿物学分析。异极矿矿样中主要物相为异极矿和石英,各占矿物成分的44.31%和41.41%。硅锌矿矿样中主要的锌矿物为硅锌矿,脉石矿物主要为石英。高硅硫氧混合锌矿组成复杂,矿物种类繁多,矿样中锌主要以异极矿和闪锌矿形态存在；其它伴生矿物有方铅矿、白铅矿、黄铁矿、陨硫铁等；脉石矿物主要为石英,并伴有少量方解石、白云母等。(2)分析了高硅锌矿高温酸转化过程热力学趋势。异极矿和硅锌矿在高温酸转化体系中发生化学反应的热力学趋势很大,且其热力学趋势依次为异极矿>硅锌矿。异极矿和硅锌矿浸出时进入溶液的H4Si04的热力学稳定区随温度的升高逐渐变小直至消失,而由其转化形成的Si02热力学稳定区则扩大,高温条件有利于H4Si04转化成Si02。在温度超过392K的温度场作用下,H4Si04在热力学上是可以自发地转化形成二氧化硅的。SiO2的热力学稳定区随可溶硅活度的提高亦明显扩大,且在高温水溶液中Si02能在很宽的E-pH范围稳定存在。提高温度和可溶硅活度将使H4SiO4转化形成SiO2的反应更容易进行。(3)研究了高硅锌矿高温酸转化过程的动力学机理。异极矿高温酸转化过程遵循固膜扩散控制,其表观活化能为44.9kJ/mol。纯硅锌矿高温酸转化过程的总速率受单个微粒周围固态产物层扩散控制,其表观活化能为22.06kJ/moo1。硅锌矿和异极矿高温酸转化过程中锌浸出的总速率受固相内扩散控制。高温酸转化体系下,硅锌矿和异极矿分解释放出可溶硅和锌,而以H4SiO4形态进入溶液中的可溶硅在393K的温度场作用下转化形成易过滤的二氧化硅沉淀,极大地改善了矿浆的液固分离性能,实现了高硅锌矿高温酸转化过程中锌与硅的高效分离。(4)研究了高硅锌矿的高温酸转化行为。高硅锌矿中以异极矿和硅锌矿形态存在的可溶硅随锌一同浸出,进入溶液的H4SiO4转化形成SiO2沉淀的主要影响因素为温度,在温度达到413～433K范围,溶液中H4SiO4转化形成SiO2沉淀的效果最佳。在优化工艺技术参数下,不同类型高硅锌矿中锌的浸出率均达97%以上,而铁和二氧化硅在转化产物中得以富集,实现了锌的可控提取。高温酸转化技术是处理高硅锌矿的有效方法。(5)开展了高温酸转化体系下多组元溶液逆流循环浸出锌富集实验,探讨了溶液中锌的富集规律,以及铁、硅等元素的变化规律。通过4次逆流循环浸出高温酸转化实验,溶液中主金属锌浓度得到了较好的富集,其含量达125.62g/L；铁、硅等浓度变化不明显,二者含量均在0.5g/L左右；且矿浆过滤性能良好。更多还原

【Abstract】 With the increasing exhaustion of high-quality zinc ore resources, more and more attention has been paid to the exploitation and utilization of refractory high-silicon zinc ore resources that are widespread in China. Developing the new method of zinc hydrometallurgy process for high-silicon zinc ores has important implications for expanding raw material sources of zinc smelting and improving the level of zinc hydrometallurgy process in our country. Thus, realizing the effective separation of zinc and silicon and exploring the method of solving the problem of filtration difficulty that is brought out by the soluble silicon present in acid leaching slurry of high-silicon zinc ores is one of key research subjects in the field. In order to optimize high-temperature acid conversion environments of the effective separation of zinc and silicon in acidic system and improve the leaching and recovery rate of zinc, this paper starts with H4SiO4that can be simultaneously formed and dissolved into leaching solution with the extraction of zinc from high-silicon zinc ores, focusing on this idea that H4SiO4could be transformed into SiO2before gelation based on the high-temperature thermodynamic properties of H4SiO4in acidic system, using the different kinds of high-silicon zinc ores as the main research objects, the research on the basic theory and adjust technology of high-temperature acid conversion for high-silicon zinc ores has been carried out for solving the problem that is brought out by the liquid-solid separation difficulty of acid leaching slurry obtained from the traditional hydrometallurgical process for extracting zinc from high-silicon zinc ores and for laying the basis for realizing the industrial application of high-silicon zinc ores. The main research work and research results are as follows in this dissertation:(1) The analysis of technological mineralogy on the three different kinds of high-silicon zinc ores (hemimorphite, willemite and high-silicon mixed sulphide-oxide zinc ores) was carried out by means of chemical phase composition, XRD and SEM-EDS. The main mineral phases present in the ore sample of hemimorphite include hemimorphite (44.31%) and quartz (41.41%). The major zinc-bearing phase in the ore sample of willemite is willemite, and the gangue mineral is mainly quartz. There are various minerals in the high-silicon mixed sulphide-oxide zinc ores, and its composition is complex. The major zinc-containing phases in the ore sample are sphalerite and hemimorphite, and the main phase composition of lead is galena and cerussite. The iron from the ore sample is presented mainly with the form of pyrite and troilite. Quartz is the main gangue mineral accompanied with a little calcite and muscovite.(2) The thermodynamic trend of high-temperature acid conversion for high-silicon zinc ores was analyzed. The thermodynamic trend in the chemical reaction involved in hemimorphite and willemite is quite significant under the system of high-temperature acid conversion, and the thermodynamic trend in the chemical reaction of hemimorphite is higher than willemite. The thermodynamic stable region for H4SiO4that can be simultaneously formed during leaching of hemimorphite and willemite becomes smaller and eventually vanishes as temperature increases. However, the thermodynamic stable region for SiO2formed by the transformation of H4SiO4increases with the increase of temperature. Higher temperatures may be helpful for turning H4SiO4into SiO2. Thermodynamically, H4SiO4is transformed spontaneously into SiO2under the influence of the temperature field of above392K. The thermodynamic stable region for SiO2becomes larger as the activity of the solute silicon increases, and SiO2present in the high-temperature aqueous solution is stable in a broad range of E-pH. Improving the activity of the solute silicon and temperature will make the conversion of H4SiO4into SiO2easier to occur.(3) The kinetics mechanism of high-temperature acid conversion process was investigated for high-silicon zinc ores. The high-temperature acid conversion reaction of hemimorphite followed a shrinking core model with "ash" layer diffusion as the main rate-controlling step. The apparent activation energy was determined to be44.9kJ/mol. The high-temperature acid conversion process of pure willemite was well interpreted by the grain model with product layer diffusion as the main rate-controlling step and the shrinking core model was used to represent the reaction of each grain. The apparent activation energy was found to be22.06kJ/mol. The total rate of zinc extraction was controlled by solid-state diffusion during high-temperature acid conversion of hemimorphite and willemite. Under the system of high-temperature acid conversion, hemimorphite and willemite broke down quickly and liberated zinc and soluble silicon, and then the soluble silicon entering the solution in the form of H4SiO4was transformed into SIO2precipitation under the influence of the temperature field of393K. The formation of silicon dioxide precipitation having excellent filtration property greatly improved the separative performance of liquid-solid from slurry, and realized the effective separation of zinc and silicon during high-temperature acid conversion of high-silicon zinc ores.(4) The high-temperature acid conversion behavior of high-silicon zinc ores was studied. The soluble silicon in the ore sample of high-silicon zinc ores exists as hemimorphite and willemite and can be simultaneously dissolved in H4SiO4form with the extraction of zinc from high-silicon zinc ores. The main factor influencing the conversion of H4SiO4into SiO2precipitation is temperature. The result for turning H4SiO4into SiO2precipitation is best when investigating at the temperature ranging from413to433K. Under the optimum conditions, the extraction of zinc from the different kinds of high-silicon zinc ores was above97%, and the iron and silica concentrated in the conversion product. The controlled extraction of zinc would be realized based on the said conditions. The high-temperature acid conversion technology is an effective method for the treatment of high-silicon zinc ores.(5) The countercurrent circulating leaching and zinc concentration experiments of multicomponent solution were carried out under the system of high-temperature acid conversion. On the basis, the migration enrichment of zinc, iron and silica in leaching solution and their distributing law were discussed. Through the countercurrent circulating leaching experiments that experienced4cycles under the said system, the zinc concentration of leaching solution got the maximum enrichment, and the zinc content reached to125.62g/L. The change in the concentration of iron and silica was not obvious, and the contents of iron and silica were about0.5g/L in leaching solution. Meantime, the leaching slurry having excellent filtration property was obtained.更多还原