Study On Extraction Of Aluminum And Iron Ions From High Iron Content Coal Gangue To Prepare Coagulants And Filter Residue Resource Utilization

The gangue of China’s Yunnan-Guizhou coal base has the characteristics of high iron content,and extracting major elements such as aluminum and iron from it has potentially enormous value.However,people do not have a deep understanding of the resource characteristics of the high iron type gangue in the area,and the gangue in the aluminum,iron element dissolution ratio is low,especially the aluminum element is more difficult to dissolve;leaching liquor and residue are difficult to utilize.In order to solve these problems,the coal gangues in Liupanshui City were taken as a representative,and the resource characteristics of high iron content coal gangue were studied in detail.The relationship between the content of aluminum and iron elements was analyzed,and the kinetics of acid leaching of aluminum and iron ions was discussed.The method of adding Ca F₂ to the system was used to improve their dissolution rate;acid leaching solution was used to prepare efficient coagulants and treat coal mine water;then,silica was extracted from the acid leaching residue and white carbon black was prepared;it achieved the goals of efficient dissolution of silicon,aluminum and iron ions from coal gangue;finally,two types of zeolites were prepared from acid leaching residue,so the methods for high value utilization of acid leaching solution and residue were found.It laid a theoretical and practical foundation for industrial production.The main conclusions are as follows:（1）The samples of the gangue were analyzed by analytical testing,and the results showed that coal gangues mainly contain quartz,kaolinite,anatase,pyrite and other minerals.In this study,the contents of aluminum and iron ions in the calcined gangue powder were analyzed by boxplot and regression analysis method.A linear negative correlation was found between the content of Al₂O₃ and Fe₂O₃ in calcined coal gangue,and the sum of the average contents of Al₂O₃ and Fe₂O₃ was 35.26%.（2）The dissolution kinetics of Al³⁺and Fe³⁺from calcined coal gangue under hydrochloric acid leaching condition was analyzed by the"unreacted nucleus contraction model",it found that the control step affecting the efficient dissolution of Al³⁺and Fe³⁺from calcined coal gangue was"mixing control".For the rate control step,the Ca F₂ was added to the system,and the extraction ratio of Al³⁺was increased from62.96%to 92.10%,and that of Fe³⁺was increased from 85.12%to 95.73%,which successfully solved the problem of difficult to dissolve aluminum and iron ions efficiently.（3）The Al³⁺and Fe³⁺in coal gangue acid leaching solution which were difficult to separate,the method of no separation was used to adjust their ratio directly,and high efficiency coagulants PAFC and PSAFC were prepared by microwave method,the reaction time was only a few minutes which greatly shorted the time,and PSAFC was used for treating coal mine water with excellent performance.（4）The silicon element in the residue was extracted by hydrothermal alkaline solution,the silicon extraction ratio was 90.16%and the Na₂Si O₃ solution was obtained.In the extraction process,there was the dissolution of quartz crystals and the crystallization of fresh Si O₂ crystals.The obtained Na₂Si O₃ solution was used as raw material,CO₂ was used as precipitant,and the secondary carbonization method was used to prepare white carbon black.Compared with the primary carbonization method,this method can promote the nucleation of silicic acid and improve the yield,and the product was nano white carbon black.（5）The acid leaching residue containing inert quartz was used as raw material and activated by Na₂CO₃ and calcined at high temperature to produce soluble Na Al Si O₄and Na₂Si O₃,then Na A and Na P zeolites were prepared,and the laws of phase changes in the preparation process were analyzed by XRD and SEM,and pure zeolites were prepared,which provides another feasible idea for high value utilization of gangue acid leaching residue rich in quartz.