一种环境友好的黄铜矿浸出新工艺及理论研究

【作者】 范兴祥；

【导师】 陈景； 彭金辉；

【作者基本信息】 昆明理工大学 ， 有色冶金， 2006， 博士

【摘要】 本文综述了国内外对湿法处理黄铜矿的研究及进展。根据热力学分析和探索性试验研究,首次提出一个拥有自主知识产权的在弱酸性条件下银盐催化过硫酸铵浸出黄铜矿的新工艺。新工艺实现了黄铜矿精矿的清洁浸出,是一种环境友好的浸出方法,也是对不同品位含铜镍复杂硫化矿处理技术的一种创新。本论文研究的主要内容和结论如下: 一、详细地进行了S-H₂O、Ag₂S-H₂O、Ag₂S-NH₃-H₂O、CuFeS₂-H₂O、CuFeS₂-NH₃-H₂O、Cu-S-O-H、ZnS-H₂O、FeS₂-H₂O和PbS-H₂O等体系的热力学计算和研究。 浸出原料除了主要含有黄铜矿外,还含有少量的闪锌矿、辉铜矿、黄铁矿和方铅矿等硫化矿物。为了研究这些硫化矿物在浸出过程中的行为,本文通过热力学计算和分析,分别绘制了Ag₂S-H₂O、Ag₂S-NH₃-H₂O、CuFeS₂-H₂O、CuFeS₂-NH₃-H₂O、Cu-S-O-H、ZnS-H₂O、FeS₂-H₂O和PbS-H₂O等体系的E-pH图,首次绘出了S₂O₈^2-在这些体系E-pH图中的位置,并讨论了S₂O₈^2-浸出黄铜矿、闪锌矿、辉铜矿、黄铁矿和方铅矿等的热力学可行性。另外,为了确定S₂O₈²-（）在S-H₂O系E-pH图中的稳定区域,分别绘制了298K和373K时S-H₂O系的E-pH图,首次绘出了S₂O₈^2-在373K时S-H₂O系的E-pH图中的位置。最后,根据同时平衡原理,利用VB计算机语言程序进行了Cu-NH₃-H₂O系的热力学平衡计算,分别计算出不同温度下溶液与固态铜、氧化亚铜和氧化铜的平衡点。这些E-pH图的绘制为过硫酸铵浸出硫化矿提供了理论依据。 二、系统地进行不同条件下过硫酸铵浸出黄铜矿的试验研究及机理分析。 1、全面地完成了银盐催化过硫酸铵浸出黄铜矿的试验研究和机理分析。结果表明,在相同浸出条件下,不加银盐时,铜的浸出率仅为30%;而加入银盐后,可显著地提高铜的浸出率,其浸出率可超过97%,说明银离子在过硫酸铵浸出黄铜矿过程中起到了积极的催化作用。动力学试验研究表明,银离子催化过硫酸铵浸出黄铜矿的反应受扩散控制,并导出动力学方程为: 1-2/3a-（1-a）^2/3=0.0685（γ_ο）^-2.[Ag⁺]^0.27[S₂O₈^2-]^0.29exp（-25096/RT）t 在银离子的催化作用下,过硫酸铵浸出黄铜矿反应速率常数提高21.18倍。浸出机理分析表明,黄铜矿之所以能被S₂O₈^2-溶解,一方面有S₂O₈^2-与黄铜矿的直接作用,产生Fe²⁺、Cu²⁺和S,另一方面有S₂O₈^2-与黄铜矿的间接作用,即S₂O₈^2-可以氧化Fe²⁺成Fe³⁺,Fe³⁺可以氧化黄铜矿,产生Fe²⁺、Cu²⁺和S。因此,银离子催化过硫酸铵浸出黄铜矿是过硫酸根分别与黄铜矿直接和间接作用的共同结果,但以过硫酸根与黄铜矿直接作用为主。 浸出渣分析表明,浸出渣中铁以黄铁矿的形式存在,说明黄铁矿在浸出过程中没有被氧化浸蚀。浸出过程中产生的元素硫呈多孔镶边结构包裹在残存的黄铜矿周围。元素硫的稳定性研究表明,元素硫在浸出过程中是稳定的,没有被氧化。试验加入的银离子最终以Ag₂S的形式包裹在残存的黄铜矿周围。更多还原

【Abstract】 The researches and advances in the hydrometallurgical treatment of chalcopyrite at home and abroad are reviewed. Based on the thermodynamic analysis and explorative experiments, a novel process of weak acid leaching chalcopyrite with ammonium persulfate in the presence of silver ions or silver sulphide as the catalyst is put forward. This process is in possession of independent knowledge property right. The novel process realizes green leaching chalcopyrite concentrate. It is also an environmentally friendly improvement to the hydrometallurgical methods of treating complex sulphide copper ore. At the same times, this process was also an innovation in processing various grades of copper-bearing and nickel-bearing complex sulphide minerals.The main work and conclusions are as follows:Ⅰ、 Systematic thermodynamics calculation and examination of the systems S-H₂O, Ag₂S-H₂O, Ag₂S-NH₃-H₂O, CuFeS₂-H₂O, CuFeS₂-NH₃-H₂O, Cu-S-O-H, ZnS-H₂O, FeS₂-H₂O and PbS-H₂OIn order to investigate the behaviors of chalcopyrite, sphalerite, chalcocite, pyrite and galena, the E-pH diagrams of the systems Ag₂S-H₂O, Ag₂S-NH₃-H₂O, CuFeS₂-H₂O, CuFeS₂-NH₃-H₂O, Cu-S-O-H, ZnS-H₂O, FeS₂-H₂O and PbS-H₂O are constructed, and the positions of S₂O₈^2- in these diagrams are determined for first time. The thermodynamics practicability of leaching Ag₂S, CuFeS₂, Cu₂S, ZnS, FeS₂ and PbS with S₂O₈^2- is studied. The E-pH diagrams of the system S-H₂O at ₂98K and ₃7₃K are also constructed to determine the stable ranges of S₂O₈^2- in the diagrams and the position of S₂O₈^2- in the system S-H₂O 373K is determined for first time. According to the principle of simultaneous equilibrium, the thermodynamics equilibrium calculation of the system Cu-NH₃-H₂O at 298/₃7₃K is carried out by use of VB computer program, and the points at which the solution are in equilibrium with solid Cu, Cu₂O and CuO were determined. These diagrams lay the theoretical foundation for application of ammonium persulfate to leaching sulphide minerals.Ⅱ、 Systematic experimental study and mechanism-analysis of leaching chalcopyrite with ammonium persulfate under different leaching conditions1. The results of experiment show that the leaching efficiency of copper is only ₃0 pct in the absence of silver ion, but it is more than 97 pct in the presence of under the same leaching conditions, which suggests that silver ions ct as an active catalyst in leaching chalcopyrite with ammonium persulfate during leaching. The kinetics experiments indicates that the reaction of leaching chalcopyrite with ammonium persulfate is controlled by diffusion and the kinetics equation is derived as follows:l-|a-（l-a）l =0.0685fr.)"*. [Ag+]°-27[S2082f"The rate constants of leaching chalcopyrite with ammonium persulfate under the catalytic action of silver ions increases by 21.18times. The analysis of leaching mechanism indicates that the direct action of 52Og2" on chalcopyrite, producing Fe2+, Cu2+ and S;plays a dominant role in the dissolution of chalcopyrite, but S2Og can also oxidize Fe2+ to Fe3+ which can, in turn, oxidize chalcopyrite to produce Fe2+, Cu2+ and S. Thus, leaching of chalcopyrite with ammonium persulfate is the common results of the direct and indirect action between 52O82" and chalcopyrite, but the direct action between S2O￡ and chalcopyrite is prevailing during leaching.The analysis results of leach residue show that iron exists in the form of pyrite, which suggests that pyrite is not oxidized and dissolved during leaching process. The unleached chalcopyrite particles are wrapped in the elemental sulfur produced, being of porous and permeable texture, and the Ag2S produced from the added silver ions. The elemental sulfur produced during the leach is stable, and it is not oxidized further.The leaching experiment results show that leaching chalcopyrite with ammonium persulfate in the presence of silver sulfide is practicable and the leaching rate is high. The experiments are also carried out under the conditions of weak acid and relatively low temperature, and the satisfactory leaching rate obtained indicates that leaching chalcopyrite at ambient temperature is practicable. In addition, based on the results of mechanism-analysis of leaching chalcopyrite with ammonium persulfate in the presence of silver sulfide, the experiment of the catalyst replaced by the leach residue obtained from leaching of chalcopyrite with ammonium persulfate in the presence of silver ions was accomplished. The result show leaching chalcopyrite with ammonium persulfate by the leach residue as catalyst at low temperature was practical. 2.The experimental results of leaching chalcopyrite with ammonium persulfate in the presence of silver ion under the ultrasonic irradiation show that the leaching reaction is self-catalyzed reaction, and the rate equation is derived as follows:Under the ultrasonic irradiation, the apparent rate constants increase by 5.81 times. The analysis results of leach residue indicate that the elemental sulfur in the residue is discrete and surface-uneven, which suggests that the sulfur films on the surfaces of chalcopyrite particles are broken by the effect of ultrasonic cavitation effect and fall off the surfaces of unleached chalcopyrite cores <, As the result of that, the exposure of new surfaces of chalcopyrite contracts with oxidant and catalyst, and this facilitates the dissolution of chalcopyrite. 3.The experimental results of leaching chalcopyrite with ammonium persulfate in the presenceof silver ion under the microwave irradiation show that the leaching rate of copper reaches more than twice that under the conditions of conventional heat and in the absence of silver ions. The of results kinetic experiment show that the leaching reaction is chemical controlled, and the apparent rate constants increase by 2.79 times. The overall apparent rate equation is derived as follows:4>=1238.01X r/1The analysis of leaching mechanism shows that the stirring effect produced by microwave irradiation breaks the elemental sulfur films on the surfaces of chalcopyrite particles and makes the elemental sulfur films disperse discretely in the residue. The exposure of unreacted chalcopyrite cores facilitates the dissolution of chalcopyrite. IIIn Examination of treatment of the leach residue and leach solutionProcessing technologies for the leach residue and solution are carried out, and the technology to treat the leaching residue also determined. The cycle use of catalyst silver ions and the oxidant by regeneration is realized. IV > Application of this process to leaching other sulphide mineralsThe experimental results show that leaching complex copper -nickel sulfide ores of various grades with ammonium persulfate in the presence of silver ions at relative low temperature is practicable, which opens up wide prospect for the application of this process.In summary, a novel process of wet chemical leaching chalcopyrite and other sulphide minerals is researched. The advantages of this process are: high leaching rate, simple operation, short flowsheet, regeneration cycle of catalyst and oxidant, and high environmental acceptability. This process meets the requirements of green clean production, and is a new promising hydrometallurgical method of direct leaching sulfide ores.更多还原