硫化铋精矿低温碱性熔炼新工艺研究

【作者】 肖剑飞；

【导师】 唐谟堂； 唐朝波；

【作者基本信息】 中南大学 ， 有色金属冶金， 2009， 硕士

【摘要】 本文针对火法炼铋存在的冶炼温度高,能耗大、消耗多、生产成本高、环境污染严重等缺点,提出了低温碱性炼铋新工艺,该工艺采用纯碱、烧碱为主要成分的熔炼体系,在780-830℃温度下进行碱性熔炼,一步产出粗铋,精矿中硫少部分转变为Na₂SO₄,大部分生成Na₂S;精矿中的钼、钨则生成钼酸钠、钨酸钠进入炉渣中,便于回收。对主要元素在低温碱性熔炼中的反应进行了热力学分析:计算结果表明硫化铋精矿的低温碱性熔炼反应自还原和碳还原兼可自发进行,碳还原占主导;碳还原反应的可能途径有三种,通过比较每种途径控制步骤的△G^θ发现900K以下途径（二）为主要通过途径,900K以上途径（三）为主要通过途径;计算结果表明AgS、PbS、Cu₂S碱性熔炼条件发生反应生成金属Ag、Pb、Cu;FeS₂、ZnS在碱性熔炼的条件不发生反应进入渣和锍中。进行了硫化铋精矿低温碱性熔炼的实验室试验,采用单因素试验法考察了W_NaOH/W_Na2CO3、碱量、温度和时间等因素对铋直收率和粗铋质量的影响。最佳工艺条件为:W_NaOH/W_Na2CO3=20/133、碱量为1.64倍理论量、温度780-830℃、时间1.5h。在最佳条件下进行了综合扩大试验和对比试验,综合实验结果良好,金属铋的直收率和铋金属的品位分别为94.43%、98.00%;对比试验表明低温碱性熔炼工艺明显优于传统火法炼铋工艺。试验结果通过投入产出元素硫和铍的分析可知,固硫率达99%,基本消除了二氧化硫对空气的污染;原料中的铍在低温碱性熔炼中其结构没有被破坏,基本全部留在浸出渣中,不会对水造成污染。该工艺熔炼温度大幅降低,这不仅减少能源消耗,而且消除了低浓度SO₂烟气对环境的污染,大幅提高铋的直收率,对铋冶炼的技术进步具有重要意义。更多还原

【Abstract】 A new process for bismuth sulfide concentrate alkaline smelting at low temperature was presented in this paper to avoiding the shortcomings of the traditional pyrometallurgical process for bismuth extraction, which including high smelting temperature, high energy and material consumption, high production cost and severe environmental pollution. In the process, the raw bismuth was produced one step at the temperature of 780℃～830℃in the smelting system of soda and caustic soda. Sulfur in the bismuth sulfide concentrate was partially transformed into Na₂SO₄ and the others mostly transformed into Na₂S. Molybdenum and tungsten in the concentrate could easily be recovered as sodium molybdate and sodium tungstate in the slag.The thermodynamic analysis of major elements in the reaction for alkaline smelting was calculated. The calculation results show that both self-reduction and carbon-reduction can proceed spontaneously in the process of bismuth sulfide alkaline smelting at low temperature, and the carbon-reduction was the main reaction. There were three possible approaches for carbon-reduction. By comparing theΔG^θof each possible approaches, it is found that the reactions follow the second approach and third approach when the temperature was lower and higher than 900K, respectively. The results also shown that AgS, PbS, Cu₂S formed Ag, Pb, Cu in the alkali smelting medium; While the FeS₂, ZnS directly entered into slag and sulfur without any reaction occured.The effects of W_NaOH/W_Na2CO3 solvent, alkaline dosage, temperature, duration on the direct recovery of bismuth and the quality of raw bismuth were investigated using the unitary factor testing in the laboratory scale. The optimal conditions were W_NaOH/W_Na2CO3= 20/133, alkaline dosage of 1.64 times the theoretical value, temperature of 780～830℃, time of 1.5h.The pilot tests and contrast tests have been done under the optimal conditions, and the results showed the tests had good effects, the direct recovery rate of bismuth and the content of bismuth was 94.43%, 98.00%, respectively. The contrast tests show that the new process is significantly superior to the conventional pyro-refining bismuth technology. The analysis of input and output of sulfur and beryllium showed that the efficiency of sulfur retention was 99%, which means that the pollution of sulfur dioxide was basically eliminated; the structure of beryllium in the raw material wasn’t destroyed, mostly reserved in the leaching residue, having no water pollution.The new process has advantage of sharp decrease of smelting temperature, which not only reducing the energy consumption but also eliminating the environmental pollution of low concentration SO₂, greatly increasing the direct recovery rate of bismuth. It has a great importance for the technology of bismuth smelting.更多还原