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控电位下粒径对辉铜矿化学和生物柱浸动力学的影响研究
HTET AUNG PHYO
Thesis Advisor阮仁满
2020-07-01
Degree Grantor中国科学院大学
Degree Name硕士
Degree Discipline化学工程
Keyword粒径,柱浸,收缩核模型,Ct
Abstract

辉铜矿(Cu2S)是最为常见的次生硫化铜矿物之一,也是重要的铜资源。自上世纪 80 年代以来,由于环保和经济上的优势,生物堆浸工艺处理低品位辉铜矿得以在世界范围内广泛应用。尽管该工艺已在工业上广泛应用,仍然存在铜浸出速率慢,铜回收率低,浸出周期长,酸耗成本高等问题。破碎粒径是重要的工艺参数之一,破碎粒径过粗影响铜回收率,破碎粒径过细则影响成本和渗滤性。尽管有许多研究报道了辉铜矿在酸性Fe2(SO4)3介质中的浸出动力学,但是缺乏控电位条件下,粒度对辉铜矿柱浸动力学影响的研究。本论文针对辉铜矿生物堆浸过程中破碎粒径对浸出速率及生产成本影响较大的问题,开展了不同粒级的辉铜矿“第一阶段”和“第二阶段”的浸出动力学研究,对优化辉铜矿生物堆浸工程实践具有借鉴意义。本论文在恒电位(Eh),恒温和恒 pH 的条件下,研究了粒度对辉铜矿纯矿物柱浸动力学的影响。此外,为了模拟堆浸,采用萃余液喷淋研究了粗粒级的低品位铜矿的柱浸动力学。本论文旨在探究不同粒级(0.054-200 mm)对辉铜矿柱浸动力学的影响,并利用未反应收缩核模型研究速率控制步骤。实验结果表明,粒度对辉铜矿第一阶段浸出动力学影响显著,由于硫层阻碍作用,粒度对第二阶段浸出速率影响较小。CT 和 SEM-EDS 结果表明辉铜矿浸出后孔隙和裂缝明显增加。“第二阶段”动力学分析表明细粒级(0.054-31 mm)浸出同时受化学反应和扩散控制,而粗粒级(31-200 mm)浸出主要受扩散过程控制。通过粒度对辉铜矿浸出动力学的影响,进一步明确了微生物强化辉铜矿浸出的作用:嗜酸铁氧化菌除了维持溶液电位平衡,更重要体现在提高Fe3+和Fe2+的扩散推动力;嗜酸硫氧化菌主要作用体现在氧化S0层,减少扩散阻碍。本论文为生物堆浸应用中选择合理的破碎粒径提供了基础数据支持,为优化生物堆浸实践提供参考。;Chalcocite (Cu2S) is one of the most common secondary copper sulfide mineral and important copper resources which can be treated by hydrometallurgical method such as heap bioleaching. Since the 1980s, the bio-heap leaching process for low-grade chalcocite ore has been used worldwide due to its environmental and economic benefits. Although this method has been widely used in industry, there are some limitations such as slow leaching kinetics, low recoveries, longer extraction time, and high operation cost due to acid consumption. The particle size is one of the most important parameters as the particle size affects the copper recovery rate and excessive crushing affects cost and leaching process. Although many studies have reported on the leaching kinetics of chalcocite in acidic Fe2(SO4)3 media, there is a lack of research on the influence of particle size on the kinetics of chalcocite column leaching under controlled potential conditions. In order to identify the effect of particle size on the leaching rate and production cost during the bio-heap leaching of chalcocite, the kinetics analysis on the first stage and second stage of chalcocite of different particle sizes have been conducted. This research can give the helpful information for optimizing the engineering practice for heap bioleaching of chalcocite.In this study, natural high-grade chalcocite samples were leached in columns under controlled Eh, constant temperature and solution pH to investigate the effect of particle size. Moreover, low-grade ore of larger size fraction was leached in the column using raffinate from the industrial heap as an irrigation solution to simulate the real heap conditions. This study aimed to investigate the effect of particle size and identify the rate-controlling steps for leaching of different particle sizes (0.054-200 mm) using shrinking core model. The experimental results showed that the particle size has a significant effect on the first stage kinetics of the chalcocite dissolution. However, the particle size has slight effect on the leaching rate in the second stage due to the hindrance of the sulfur layer. X-ray CT and SEM-EDS results showed that pores and cracks increased significantly after leaching of chalcocite. The kinetic analysis of second stage showed that the leaching of small particles (0.054-31 mm) was controlled by both chemical reaction and product layer diffusion while the leaching of large particles (31-200 mm) was mainly controlled by the diffusion process. In addition to the influence of particle size on the leaching kinetics of chalcocite, the role of microorganisms in enhancing the leaching of chalcocite is further clarified. Maintaining the solution potential and acidophilic iron oxidizing bacteria are more importantly played in increasing the driving force for diffusion of Fe3+ and Fe2+. The main role of sulfur oxidizing bacteria is to oxidize the S0 layer for reducing diffusion barriers. This paper provides basic information for selecting a reasonable particle size used for the heap bioleaching and provides a reference for optimizing the industrial practice. 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/49650
Collection中国科学院过程工程研究所
Recommended Citation
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HTET AUNG PHYO. 控电位下粒径对辉铜矿化学和生物柱浸动力学的影响研究[D]. 中国科学院大学,2020.
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