碱性硫脲浸金影响因素及浸出机理研究

发布时间：2018-03-27 19:18

本文选题：碱性　切入点：硫脲　出处：《北京有色金属研究总院》2017年硕士论文

【摘要】：近年来,随着环保要求的逐步提高,低毒环保的非氰浸金药剂硫脲受到了研究者的关注。目前,硫脲浸金的研究分为酸性体系和碱性体系两大类。与在酸性体系相比,在碱性体系中硫脲浸金具有更好的选择性,且对设备没有腐蚀。但是,碱性硫脲浸金理论还不完善,金浸出率低于氰化浸出指标,氧化剂选择不合适会造成硫脲的大量消耗。本文以埃塞俄比亚NMIC公司提供的金矿石为试验样品,利用常规氰化浸出及酸性硫脲浸出试验对矿样的可浸性进行了研究,在最佳条件下得到的浸出率分别为92.41%和74.50%,可知该矿样属于易浸样品。根据氧化还原电位理论选取空气中氧作为氧化剂,通过碱性体系硫脲浸金试验考察了氧化剂、焙烧预处理、炭浸工艺、充气效果等因素对浸出率的影响规律。试验过程中为了实现不同的充气效果,设计了常规充气、螺旋空气管充气、微孔材料充气三种充气装置,并通过氧总转移系数测定确定了这三种装置的增氧能力依次增大。碱性硫脲浸金试验结果表明,使用微孔材料充气能够将金浸出率提高30%左右,而焙烧预处理、炭浸工艺所能提高的浸出率均在10%左右。在微孔材料充气条件下进行了碱性硫脲浸金的单因素条件试验,考察了硫脲用量、稳定剂用量、矿浆液固比、矿浆初始pH、浸出时间、空气充气量、搅拌桨转速等试验条件对金浸出率的影响规律,得到优化后的试验条件为:硫脲用量1.5 kg/t、六偏磷酸钠用量1.5 kg/t、矿浆液固比3:1、矿浆初始pH为11.5、浸出时间8 h、空气充气量0.8 L/min、搅拌桨转速300 r/min,得到的浸出率为54.27%。在酸碱不同体系中进行了硫脲溶解金箔片试验,采用原子力显微镜、扫描电子显微镜及能谱分析等检测手段对溶金情况进行了分析,并采用两段浸出试验对分析结果进行了验证;在碱性体系中进行了不同气体充气的硫脲浸金试验。结果表明,碱性体系中硫脲溶金的速率远低于酸性体系,碱性体系硫脲浸金更容易形成钝化膜;碱性硫脲浸金过程中,采用氮气、空气、纯氧充气时矿浆溶氧量分别为1.6 mg/L、8.1 mg/L、32.9 mg/L,而浸出率分别为48.64%、52.94%、53.64%,溶氧量差别明显但浸出率变化不大,分析认为除了溶氧量外,充气形成的大量湍流也是浸出率提高的重要原因。
[Abstract]:In recent years, with the improvement of environmental protection requirements, thiourea, a non-cyanide gold leaching agent with low toxicity and environmental protection, has attracted the attention of researchers. At present, the research on gold leaching with thiourea is divided into two categories: acid system and alkaline system. In alkaline system, thiourea leaching of gold has better selectivity and does not corrode the equipment. However, the theory of alkaline thiourea leaching gold is not perfect, and the leaching rate of gold is lower than that of cyanide leaching. Improper selection of oxidants will cause a large amount of consumption of thiourea. In this paper, the leachability of ore samples was studied by conventional cyanide leaching and acid thiourea leaching tests, taking gold ores provided by Ethiopia NMIC Company as test samples. Under the optimum conditions, the leaching rates are 92.41% and 74.50%, respectively. The ore sample is a leachable sample. According to the theory of redox potential, oxygen in air is selected as oxidant. The oxidizing agent and roasting pretreatment are investigated by leaching gold with thiourea in alkaline system. In order to realize different inflatable effect, three kinds of inflatable devices, such as conventional inflating, spiral air tube inflating, microporous material inflating, were designed in order to realize different inflatable effect. The results of alkaline thiourea leaching test show that the gold leaching rate can be increased by about 30% by using microporous material, and the roasting pretreatment can increase the leaching rate of gold by about 30%. Under the condition of aeration of microporous materials, the single factor experiment of alkaline thiourea leaching of gold was carried out. The amount of thiourea, the amount of stabilizer, the ratio of ore slurry to solid, the initial pH of pulp, the leaching time were investigated. The influence of test conditions, such as air volume and impeller speed, on the leaching rate of gold, The optimized conditions are as follows: thiourea 1.5 kg / t, sodium hexametaphosphate 1.5 kg / t, slurry solid ratio 3: 1, initial pH 11.5, leaching time 8 h, air charge 0.8 L / min, impeller speed 300 r / min, leaching rate 54.27%. The experiments of thiourea dissolution of gold foil in different alkali systems were carried out. Atomic force microscope, scanning electron microscope and energy spectrum analysis were used to analyze the gold dissolution, and the results were verified by two-stage leaching test. The gold leaching experiments of different gases filled with thiourea were carried out in alkaline system. The results showed that the gold dissolution rate of thiourea in alkaline system was much lower than that in acid system, and the passivation film was more easily formed in alkaline system, and in the process of leaching gold with alkaline thiourea, The dissolved oxygen content of pulp is 1.6 mg / L ~ 8.1 mg / L ~ (-1) mg 路L ~ (-1) when nitrogen, air and pure oxygen are inflated, and the leaching rate is 48.64% and 52.94% ~ 53.64 respectively. A large amount of turbulence formed by aeration is also an important reason for the increase of leaching rate.
【学位授予单位】：北京有色金属研究总院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD953

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