High Iron And Low Aluminum Gangue Comprehensive Utilization Of Basic Research

Coal gangue is a kind of solid waste produced in coal production and processing process, is also one of the largest industrial waste emission of our country at the present stage. The stockpiling of coal gangue not only occupy the land, but also on the surrounding environment pollution is very serious, and to a certain extent resulting in a waste of resources. Therefore, comprehensive utilization of coal gangue resources will become the important resources and environmental problems have to be solved for sustainable development in china.At present, the coal gangue has been widely used in power generation, production of building materials and filling reclamation and other aspects. But generally had the low technology content, low added value, economic benefits is not obvious and other issues. Sometimes there are two serious pollution. Rich in iron and aluminum silicon resources in coal gangue, so extracting valuable elements from coal gangue will be the focus of the comprehensive utilization of coal gangue.In this paper, taking coal gangue from Panxian of Guizhou as the research object. Through mechanical activation method to stimulate its activity, with a certain concentration of sulfuric acid leaching of aluminum and iron mineral in the case of heating with coal gangue. Using the coal gangue regulat acid leaching solution pH value to about1.5for acid leaching and solution. And the aluminum and iron of acid leaching in neutral solution were separated by hydrolysis precipitation method, produced the alumina and iron oxide red. Studies showed that:(1) Mechanical activation of coal gangue can increase the specific surface area and the particle surface free energy. Mechanical activation destruct the ordered structure of minerals in coal gangue, the reaction activity increased. It create conditions for the valuable element leaching from coal gangue.(2) After studying on the gangue through mechanical grinding whether need thermal activation treatment, determined that the valuable elements have a higher rate of dissolution without through thermal activation process by acid leaching from coal gangue.(3) Through single factor and orthogonal test, it studied these factors such as acid concentration, acid dipping temperature, acid dipping time and liquid-solid ratio which influenced the dissolution rate of alumina and iron. It detemined the optimum conditions about extracting alumina and iron from coal gangue, that were the acid concentration65%, reaction time4h, temperature125℃, ratio of solid to liquid3:1. On this conditions, the leaching rate of alumina and iron oxide in coal gangue were89.15%and94.24%.(4) Under the conditions of the sulfuric acid concentration of65%, the liquid to solid ratio of3:1, the reaction temperature at35℃to95℃, verify kinetics model of the alumina by acid leaching from coal gangue, the chemical response that alumina from coal gangue by sulfuric acid leaching consistent particle size shrink shrink core model. And the kinetic equation of the chemical reaction is1-(1-ω)2/3=kt, the activation energy Ea=42.78kj/mol.(5) Process conditions of preparation of acid leaching neutral solution using acid leaching solution were obtained by experiment:the amount of coal gangue as reaction liquid quality35%, reaction temperature80℃, reaction time2h.(6) The aluminum and iron of neutral solution of acid leaching were separated by hydrolysis precipitation method, The prepared crude aluminum hydroxide after separating the aluminum was dissolved with sodium hydroxide solution, carbonation, the high purity aluminum hydroxide will be prepared. After high temperature calcined, alumina were obtained. Through chemical composition analysis, its content reached the requirements of two grade product in GB/T24487-2009. Through the XRD figure, alumina characteristic peaks match with γ-Al2O3which was calcined at1000℃.(7) under the conditions that room temperature, stirring and pass into the air oxidation, the acid leaching neutral solution after dealumination prepared Fe(OH)3. It is the excessive product of iron oxide. After the product was calcined half hour at850℃will get red iron oxide. The chemical composition and performance analysis show that the performance indicators of iron oxide red products meet the requirements of first grade in GB1863-89. Its XRD pattern shows that the diffraction peak position and intensity match with the standard pattern and no other impurities peaks. The results explain that the purity of iron oxide is high.(8) The technical and economic analysis showed that there is a huge development potential that prepared alumina and iron oxide with coal gangue by sulfuric acid leaching. This method had good economic and social benefits and provided a broad platform for the coal gangue comprehensive utilization of resources.