Knowledge Management System Of Institute of process engineering,CAS
我国为钼资源大国，储量居世界第一位。辉钼矿为自然界中工业价值最高、分布最广的含钼矿物，也是制备金属钼和钼系化合物产品的初级原料。传统辉钼矿氧化焙烧分解工艺存在资源利用率低、排放的低浓度二氧化硫气体回收成本高等弊端，而现有酸碱介质氧压浸出分解辉钼矿工艺存在浸出介质消耗量大、液相中的钼回收成本高等问题。为实现辉钼矿的高效分解和钼硫资源的综合利用，本论文提出氧压水浸法分解辉钼矿综合利用钼硫资源的新工艺，以辉钼矿在H2O-O2体系下的氧化分解和离子交换法回收浸出液中的钼为主线，重点研究了辉钼矿在H2O-O2体系中氧化分解的热力学、分解规律和动力学，分析了氧化产物在固液两相的分配规律，探讨了离子交换法回收酸性浸出液中钼组份的工艺条件和动力学，并探索了浸出液中硫酸资源的综合利用。本论文取得了如下创新性进展： (1) 讨论了辉钼矿在H2O-O2体系中的氧化分解热力学。通过分析在H2O-O2体系中辉钼矿主成分MoS2及FeS2、Cu2S等杂质组份可能发生化学反应的热力学趋势和热量变化，明确了辉钼矿氧压水浸分解过程中Mo和S的可能存在物相及反应路径。(2) 研究了辉钼矿在H2O-O2体系中氧化分解的工艺与动力学。在液固比6:1、氧气分压1 MPa、搅拌速率600 rpm、辉钼矿粒度-250目、反应温度200 °C等最优工艺条件下，经120 min的反应时间后，钼转化率可达到99%以上。在180 °C ~ 220 °C，辉钼矿的氧压分解过程符合未反应收缩核模型，其速率控制步骤为表面化学反应。辉钼矿中的杂质铜和铝较易被浸出，而只有41.7% ~ 57.4%的镁在氧化分解过程中被浸出。(3) 分析了辉钼矿氧压水浸过程的机理。研究结果表明，氧压水浸过程主要由辉钼矿的氧化分解和氧化产物的溶解两部分组成。氧化分解过程中Mo被氧化为MoO3·2H2O与Mg3Si4O10(OH)2进入渣相，S被氧化为SO42-和HSO4-进入液相。氧化产物MoO3·2H2O在浸出液中溶解量和存在形式与浸出液的酸度有关：随着酸度的增加，溶液中的Mo从MoO42-和H2Mo7O244-转变为MoO22+和Mo36O1128-；Mo在溶液中的溶解量随着酸度的增加呈现先降低后增加的抛物线趋势，温度、氧气分压、搅拌强度和矿物粒度只影响氧化产物溶解的速率，并不影响溶解能力，而液固比通过影响浸出体系中钼的总含量和浸出液的酸度既影响溶解过程的速率，也影响Mo在浸出液的溶解度。(4) 探讨了离子交换法回收酸性浸出液中钼组份的工艺条件和动力学。使用D301离子交换树脂直接吸附酸性浸出液中的钼离子，通过静态吸附实验确定了树脂在酸性浸出液中的饱和吸附容量为499.6 mg/g；中断法和无限浴吸附实验表明，吸附过程受树脂内扩散控制，树脂粒度为0.9 ~ 1.2 mm和0.6 ~ 0.9 mm吸附过程的表观活化能分别为25.47 kJ/mol和20.38 kJ/mol；连续上柱吸附实验表明逆流的进料方式可以强化吸附效果，使树脂的工作容量从顺流吸附时的142.83 mg/g提高到285.66 mg/g；通过解吸实验确定了载钼树脂的解吸条件，为大规模连续实验和生产提供理论依据。(5) 开展了辉钼矿氧压水浸法分解工艺的全流程优化。采取循环浸出的方法降低了氧压水浸工艺用水量。由于氧压水浸渣洗水中钼含量少，酸度小，成分稳定，可以保证循环浸出率在96%以上，适合作为循环浸出介质。氧压水浸渣中杂质Cu，Al和Mg的含量低，氨浸后固液分离得到的钼酸铵溶液的浓度在300~350 g/L，且杂质含量低，Cu和Al含量在10 mg/L以下，可以直接制备钼酸铵产品；得到的氨浸渣为无毒无害的硅镁渣，可直接堆存或排放。(6) 探索了浸出液中硫资源综合利用新方法。开展了黄铜矿和辉钼矿、软锰矿（二氧化锰）和辉钼矿在H2O-O2体系中联合浸出的工艺研究，提出了将辉钼矿在H2O-O2体系中氧化浸出的酸性浸出液作为氧化铜矿浸取剂的新思路，为辉钼矿中硫资源的综合利用提供了新途径。;China is a major country in molybdenum resources and its reserves of molybdenum ranks the first in the world. Molybdenite is the most valuable and widely distributed molybdenum mineral in nature, and is also a primary raw material for the preparation of molybdenum and molybdenum compounds. The well-known disadvantages of pyrometallurgical roasting process of molybdenite are the low metal recovery ratio, high cost of recovering low concentration sulfur dioxide emissions. And for hydrometallurgical method such as acid or alkaline leaching under oxygen pressure, the existing problems are the large consumption of leaching medium, the difficulty in recovery the molybdenum in the liquid phase, which makes it difficult to be applied in the current industrial process. The research project ‘Comprehensive Utilization of Molybdenum and Sulfur Resources through Decomposing Molybdenite by Oxygen Pressure Leaching in Water’ was proposed to realize comprehensive utilization of molybdenum resources and sulfur resources in molybdenite. Oxidation decomposition of molybdenite in H2O-O2 system and recovery of molybdenum from leach solution by ion exchange method constituted the two main lines of the study. The study focused on thermodynamics, decomposition law and kinetics of the decomposition of molybdenite in the H2O-O2 system. The distribution of oxidation products in solid and liquid two phase and the existence form of molybdenum in acidic leaching solution were analyzed. Based on the existence form of molybdenum, direct adsorption of Mo (Ⅵ) by ion exchange resin in acidic leach solution of molybdenite was proposed. The comprehensive utilization of sulphuric acid resources in the leaching solution was also explored. The following achievements and progress were exhibited:(1) The thermodynamic calculation of the oxidation decomposition of molybdenite in the H2O-O2 system was carried out. By analyzing the thermodynamic trend and the heat change of the main components of molybdenite, such as MoS2 and FeS2, Cu2S and other impurities in H2O-O2 system, the possible phases and reaction paths of Mo and S were ascertained. (2) The oxidation process and kinetics of molybdenite in the H2O-O2 system were studied. The recommended optimal reaction conditions were: an LTS ratio of 6:1, oxygen partial pressure of 1 MPa, stirring speed of 600 rpm, particle size below 250 mesh and leaching temperature of 200 °C. Under these conditions, conversion rate of molybdenum could reach 99% after 120 min leaching. The kinetic investigation results revealed that the rate-controlling step was the chemical reaction. Copper and aluminum in molybdenite were easier to leach in the process of oxidative decomposition. The leaching rate of magnesium was 41.7%~57.4% during the decomposition process.(3) The mechanism of oxygen pressure leaching in water was analyzed. The leaching process was mainly composed of the decomposition of molybdenite and the dissolution of the product. During decomposition, Mo was oxidized into MoO3 2H2O and stayed in slag phase with Mg3Si4O10(OH)2, and S was oxidized into SO42- and HSO4- dissolved into the liquid phase. The amount and form of Mo in the leaching solution were related to the acidity of the leaching solution: with the increase of acidity, the Mo ion in the solution changed from MoO42? and H2Mo7O244- to MoO22+ and Mo36O1128-; The amount of the dissolved Mo exhibited a parabolic trend with the increase of the acid concentration. The kinetic conditions, such as temperature, oxygen partial pressure, stirring rate, and mineral grain size, only affected the rate of distribution, but not affect the amount of solid liquid distribution. However, the ratio of liquid to solid affects both the rate and amount of distribution.(4) The process conditions and kinetics of the recovery of molybdenum in acidic leaching solution by ion exchange method were discussed. The loading capacity of D301 for molybdenum from high acidic leach solution was up to 499.6 mg/g. The adsorption process was controlled by the particle diffusion, and the activation energy decreased from 25.47 to 20.38 kJ/mol, with the resin particles sizes reducing from 0.9 - 1.2 mm to 0.6 - 0.9 mm. Continuous column experiments verified direct extraction of molybdenum from acidic leach solutions by ion exchange resin D301 and the upstream flow improved absorption from 142.83 mg/g to 285.66 mg/g. Elution conditions were used to determine elution conditions, providing the theoretical basis for the large-scale continuous production.(5) The cyclic leaching method was used to reduce the water consumption and optimize the process. Washing water of the oxidized residue had less molybdenum content, less acid and was stable at composition, which can make the cyclic leaching rate over 96%. The content of impurity Cu, Al and Mg in oxygen pressure water leaching residue was low. The concentration of ammonium molybdate solution was 300~350 g/L with little impurity and could be directly used in the preparation of molybdate ammonium. Ammonia leaching residue was nontoxic and harmless and could be directly discharged.(6) Comprehensive utilization of sulphur resources in the leaching solution was explored. Combined leaching of chalcopyrite and molybdenite, pyrolusite (manganese dioxide) and molybdenite in H2O-O2 system were explored. Using acidic leaching solution as a leaching agent for copper oxide ore was proposed, providing a new way for comprehensive utilization of sulfur resources in molybdenite.
|付云枫. 氧压水浸法分解辉钼矿提取分离钼硫资源的应用基础研究[D]. 中国科学院研究生院,2018.|
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