特种石墨制备过程中原料加压湿法高效脱杂机理研究

Isotropic graphite is a strategic resource. As raw material of isotropic graphite, high purity material obtained by purifying petroleum coke(calcined coke) is an important procedure in the process of preparing isotropic graphite. In this project, the petroleum coke is studied by adopting pressure leaching, and controlling thermodynamic conditions and kinetic conditions gains the purpose of desorpting highly efficiently impurity elements especially sulfur in petroleum coke. .The impurity distribution laws of several sources of petroleum coke are studied by means of scanning electron microscope, X-ray diffraction, inductively coupled plasma mass spectrometry and other modern analytical methods. By thermodynamic analysis and optimization experiments, the influence of technical parameters on the impurity removal efficiency is studied, and parameters are optimized in the process of making use of petroleum coke to prepare high purity graphite. The influence of the factors and multicomponent reaction dynamical parameters on purification with hydrometallurgy of petroleum coke is studied under the pressure fields, the controlling steps and reaction mechanisms are revealed in the process of removing impurities especially sulfur element, and dynamic model is built. The electrochemical reaction process of elements removal is studied, and electrochemical characteristics are revealed in the process on purification with hydrometallurgy of petroleum coke under pressure fields. Finally, the technical and theoretical systems of preparing high purity graphite attained by hydrometallurgy process purification of petroleum coke are formed, and this provides theoretical support for the preparation of isotropic graphite.

特种石墨是一种战略资源。以石油焦（煅后焦）为原料脱杂提纯获取高纯石墨原料是特种石墨制备中一个重要的中间环节。本项目以石油焦（煅后焦）为研究对象，采用加压湿法冶金新技术，通过控制热力学和动力学条件，以达到高效脱除石油焦中杂质元素特别是硫元素的目的。采用SEM、XRD、ICP-MS等现代分析测试手段，研究典型的石油焦中杂质分布规律。通过研究杂质元素特别是硫的反应热力学，杂质脱除的微观机理，构建石油焦（煅后焦）中杂质脱除的反应动力学模型，考察杂质进入溶液的工艺特征。研究压力场下各元素在脱除过程中的迁移规律与电化学性能，揭示杂质反应过程的电化学性能特征。研究石油焦（煅后焦）中杂质脱除的传质传热的规律，建立反应过程中可靠的动量传递、热量传递数学模型。形成石油焦压力场下湿法脱杂制备高纯石墨的技术理论体系和技术，为石油焦制备特种石墨提供理论指导。

特种石墨是一种战略资源，广泛应用于冶金、光伏、化工、航天、电子、机械、核能等工业领域，尤其是大规格高质量的高纯石墨，作为替代性材料，在高科技、新技术领域有着宽广的应用空间，具有广泛的应用前景，被誉为21世纪最有前途的材料。但是由于特种石墨的主要生产技术受到了国外封锁，且价格昂贵，我国的石墨材料发展受到了很大的制约。以石油焦为原料脱杂获取高纯度的原料是特种石墨制备中一个重要的中间环节。因此本项目采用加碱焙烧与加压湿法冶金新技术相结合对石油焦进行提纯，研究一种低成本、环境友好的特种石墨高纯度原料制备新工艺是十分有意义的。本课题组借助SEM、XRD、ICP-MS等现代分析测试手段，在石油焦杂质元素分布特征分析的基础上，系统地研究了加压湿法冶金技术脱除杂质元素Fe、Al、Si等元素，并获得了加压湿法冶金技术脱除杂质元素Fe的动力学规律，此外，研究了加碱焙烧与加压湿法冶金技术相结合方式脱除杂质元素S，并对杂质元素S脱除过程动力学规律进行了详细的研究，获得了加碱焙烧有效脱除杂质元素S的作用机理。最后对石油焦脱杂过程中的电化学性能特征进行了探索。本项目形成压力场下石油焦湿法脱杂制备高纯石墨的技术理论体系和技术，为石油焦制备特种石墨提供理论指导。研究工作对于形成拥有自主知识产权的核心技术、打破国外在该领域的技术垄断，都具有重要的科学意义和广阔的工业应用前景。