基于富含腐植质褐煤柱式分选的微细粒煤泥分散与沉降行为研究

Lignite is rich in humic substances, which have lots of polar oxygen-containing functional groups. Flotation separation of lignite is difficult because of the improved hydrophilicity of particle surface. The investigation of new theory, technology and process on flotation separation of the lignite containing high levels of humic substances, is of great significance to improve the quality and utilization of resources. Aimed at further investigating on flotation separation of lignite, this project is carried out to study the dispersion and settlment behaviors of low-rank coal slime, by proposing that lignite containing high levels of humic substances instead of oxygen-containing functional groups as inherent mineralogy defect. The main theory and methods used in this project include coal petrography, coal chemistry, coordination chemistry, colloid and surface chemistry, solution chemistry, etc. The following research contents are mainly included: Physicochemical characteristics of humic substances in lignite and their distribution in organic macerals; Dissolving and agglomerating behaviors of water-soluble humic substances on coal surface, and their effects on surface properties, dispersion and settlment behaviors of coal slime; Effects of clay minerals, inorganic electrolytes, organic chemicals on dispersion and settlment behaviors of coal slime, and their distribution in the free and binding states; Dispersion and settlment behaviors of coal slime in the experimental system of micro-bubble flotation column. This project will further provide the theoretical and technical foundation on improving the system of solution chemistry of low rank coal, the effective controlling of selective dispersion and settlment of slime, and the development of technology and process for lignite column separation.

褐煤富含腐植质，含氧官能团多，亲水性强，浮选分离难度大。研究难选褐煤浮选分离的新理论、新技术和新工艺，对提高资源的品质和利用率具有重要意义。本项目针对难选褐煤的细粒浮选关键问题，提出了将褐煤“先天性”矿物学缺陷的原因从富含氧官能团深入到富含腐植质这一共性点的新思路，利用煤岩学、煤化学、配位化学、胶体与表面化学、溶液化学等理论和方法，开展难选低阶煤泥的分散与沉降行为研究。具体内容包括：研究腐植质的物化特性及其在褐煤有机显微组分中的赋存规律；研究溶解性腐植质的溶液行为与褐煤的矿物赋存规律、表面性质及分散沉降行为的关系；研究泥质矿物、无机电解质、有机药剂对煤泥分散沉降行为的影响，以及三者在自由态和结合态之间的分布规律；研究微泡浮选柱组合力场条件下煤泥的分散与沉降行为。本项目将为进一步完善难选低阶煤泥的溶液化学体系，有效控制煤泥选择性的分散和沉降，开发褐煤柱式分选技术和工艺奠定理论和技术基础。

褐煤中腐植质含量高，同时具有大量含氧官能团，导致亲水性强，浮选分离难度增大。因此，开展难选褐煤浮选分离的新理论、新技术和新工艺研究，对提高资源的品质和利用率具有重要意义。针对难选褐煤的细粒浮选关键问题，本项目提出了将褐煤“先天性”矿物学缺陷的原因从富含氧官能团深入到富含腐植质这一共性点的新思路，利用煤岩学、煤化学、配位化学、胶体与表面化学、溶液化学等理论和方法，开展难选低阶煤泥的分散与沉降行为研究。项目研究内容包括：腐植质的物化特性及其在褐煤有机显微组分中的赋存规律；溶解性腐植质的溶液行为与褐煤的矿物赋存规律、表面性质及分散沉降行为的关系；泥质矿物、无机电解质、有机药剂对煤泥分散沉降行为的影响，以及三者在自由态和结合态之间的分布规律；微泡浮选柱组合力场条件下煤泥的分散与沉降行为。研究结果表明，腐植质在褐煤中的赋存状态多样，一部分为游离状团块腐植质，另一部分则与非煤矿物紧密结合。褐煤中腐植酸的溶解行为更符合以内扩散为速率控制步骤的未反应核模型。随着溶液pH的增加，褐煤样品的接触角减小，亲水性增强，褐煤颗粒的分散性增强，不利于褐煤颗粒的沉降。高岭土与褐煤腐植酸的相互作用主要表现为吸附聚沉。随着腐植酸浓度的增加，褐煤、粘土颗粒之间的斥力作用减弱，分散性降低。通过对组合力场（溶液化学、充气速率、压力、气泡大小等）对褐煤分散与沉降行为影响发现，浮选溶液化学体系影响最为显著。随着浮选矿浆pH的增加，褐煤精煤产率下降，灰分逐渐升高。随着起泡剂用量的增加，精煤灰分显著降低，褐煤浮选效率显著提高。本项目将为进一步完善难选低阶煤泥的溶液化学体系，有效控制煤泥选择性的分散和沉降，开发褐煤柱式分选技术和工艺奠定理论和技术基础。