Cu-Pb-Zn在成矿流体中的化学形态研究

发布时间：2018-01-03 22:13

本文关键词：Cu-Pb-Zn在成矿流体中的化学形态研究　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：成矿流体中金属的迁移、沉淀机制一直是科学家最为关注的内容,由于地壳中成矿物质比较复杂、成矿条件难以控制,对此的研究也仅限于特定的环境下。铜、铅、锌作为地球化学中较易形成矿床的三种贱金属,对它们的研究较多,但苦于实验条件有限,只能得出一些片面结论,还有待进一步研究。GWB(The Geochemist’s Workbench)是一种功能强大的商用地球化学模拟软件。其包含了不同的程序可进行活度-活度、温度-活度、pH值、逸度及Eh-pH的相图模拟,得出物理化学因素对金属在成矿流体中的化学形态影响。本论文运用GWB模拟Cu、Pb、Zn三种金属在成矿流体中的化学形态是一个创新点,并且该模拟省时省力、节源开支、保障安全。此外,实验室研究只能得到部分矿物如铜蓝的溶解度随温度变化的关系,较片面,而GWB模拟可以一次性得出相关迁移物种和形成矿物类型,比较全面。在查阅大量中英文文献的基础上,本课题主要借助于GWB中的Act2、Rxn、Tact等程序模拟不同条件下金属存在的形态,为地质科学研究者找矿工作提供一些帮助。研究表明:温度、离子浓度、pH值、氧逸度及Eh对三种金属在成矿流体中的化学形态影响因素中温度的影响最大,几乎任何一种因素都受温度的影响,在三种金属中,五个因素对铜的迁移影响最大,对铅和锌的影响几乎一致,这也解释了在矿床形成过程中铅锌矿床几乎都是共存的,如MVT型铅锌矿床、矽卡岩铅锌矿床等。在形成矿床类型中,发现赤铜矿、铜矿和辉铜矿的形成不受温度的影响,而孔雀石、黑铜矿、铜蓝受温度影响较大;铅主要形成硫酸铅矿、白铅矿和方铅矿;锌主要形成菱锌矿和闪锌矿。与氯形成配合物的模拟结果表明,三种金属均最多与4个Cl-配合,铜的一价和二价均可形成配合物,铅和锌都能形成四种配合物,具体形式受温度和氯的离子浓度共同影响。Eh对铜这样的变价金属存在形式影响较大,对铅和锌无变价金属无影响。lgk与温度的关系模拟结果表明:大多数铜、铅矿物及全部锌矿物和全部铅、锌配合物的lgk都随温度的升高而减小;但赤铜矿随温度的升高而增大;白铅矿在低温时随温度的升高而增大,中温时随温度的升高而减小;铜的配合物较复杂,CuCl32-随温度的升高而减小,Cu~(2+)、CuCl+、CuCl2随温度的升高而增大,CuCl2-、CuCl3-和CuCl42-随温度的升高先增大后减小。
[Abstract]:The migration and precipitation mechanism of metals in ore-forming fluids have been the most concerned by scientists. Because of the complexity of ore-forming materials in the crust, the ore-forming conditions are difficult to control, and the study is limited to the specific environment. As three base metals in geochemistry, lead and zinc are easy to form ore deposits. They have been studied more widely, but due to the limited experimental conditions, only some one-sided conclusions can be drawn. The Geochemist's Workbench remains to be further studied. It is a powerful commercial geochemical simulation software. It contains different programs to carry out activity-activity. The effects of physical and chemical factors on the chemical form of metal in the ore-forming fluid were obtained by the simulation of temperature activity pH value fugacity and Eh-pH. In this paper GWB was used to simulate the chemical form of metal in the ore-forming fluid. The chemical form of three Zn metals in ore-forming fluid is an innovation point, and the simulation saves time and labor, saves resources and expenses, and ensures safety. The relationship between solubility and temperature of some minerals such as copper blue can be obtained only in laboratory, but the GWB simulation can obtain the related migrating species and forming mineral types at one time. On the basis of consulting a large number of Chinese and English literature, this paper mainly uses the program of Act2Tact in GWB to simulate the shape of metal in different conditions. The results show that the temperature, ion concentration and pH value are the most important factors. Oxygen fugacity and Eh have the greatest influence on the temperature of the three metals in the ore-forming fluid. Almost any factor is affected by the temperature in the three metals. The five factors have the greatest influence on copper migration, and almost the same effect on lead and zinc, which also explains that almost all lead-zinc deposits coexist in the process of deposit formation, such as MVT type lead-zinc deposit. Among the deposit types, it is found that the formation of chalcopyrite, copper ore and chalcopyrite is not affected by temperature, but malachite, black copper and copper blue are greatly affected by temperature. Lead mainly forms lead sulfate, white lead and galena; Zinc is mainly formed in smithsonite and sphalerite. The simulation results of forming complexes with chlorine show that the three metals are all combined with 4 Cl- at most, and copper can form complexes in both valence and bivalent. Lead and zinc can form four kinds of complexes. The specific form is influenced by temperature and chloride ion concentration. Eh has a great influence on the existence of copper. The simulation results show that the lgk of most copper, lead minerals, all zinc minerals and all lead and zinc complexes decrease with the increase of temperature. But the chalcopyrite increases with the increase of temperature. The white lead ore increases with the increase of temperature at low temperature, and decreases with the increase of temperature at medium temperature. The complex of copper complex CuCl32- decreases with the increase of temperature and increases with the increase of temperature. CuCl3- and CuCl42- increase first and then decrease with the increase of temperature.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P612

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