伴生矿物及水分对煤的黏结性的影响

Influence of associated minerals and moisture on the cohesion characteristics of coal

潮湿煤炭因黏结团聚给选煤厂分级作业带来了极大困难.应用拉断法对原煤进行了黏结性研究,借助于液桥理论研究了煤中伴生矿物及水分对煤的黏结性的影响机制.研究结果表明:当煤与伴生矿物混合时,矿物质含量越高,接触角越小,液桥力越大,煤越容易团聚;混合物的实际抗剪切强度系数并不是线性叠加,体现了煤与伴生矿物之间的协同强化增大黏结性的作用;煤与伴生矿物混合样品的抗剪切系数均随水分的增加而增加;随着粒度的增大,液桥力逐渐增大,对周边的小颗粒煤样吸附量增多,加剧煤粒间的团聚效果,随着水分的增加,钳角增大,液桥体积也随之增大,致使煤样液桥力增大,煤样团聚效果加剧;煤与伴生矿物混合时,随着粒径的减小,黏结性变弱.

The agglomeration of wet coal has brought great difficulties to the classification operation of the coal preparation plant. The pull-off method was used to study the cohesiveness of raw coal. The influence mechanism of associated minerals and moisture in coal on the cohesive properties of coal was studied with the aid of liquid bridge theory. The results show that when coal is mixed with associated minerals, the higher the mineral content, the smaller the contact angle, the greater the hydraulic bridge force, and the easier the coal is to agglomerate. The actual shear strength coefficient of the mixture is not linearly superimposed, which reflects the synergistic strengthening between coal and associated minerals to increase the cohesiveness. The shear resistance of samples mixed with coal and associated minerals all increase with the increase of water content. As the particle size increases, the liquid bridge force gradually increases, and the amount of adsorption on the surrounding small coal samples increases, which intensifies the agglomeration effect between coal particles. With the increase of water content, the clamp angle increases, and the volume of the liquid bridge also increases, resulting in the increase of the coal sample liquid bridge force of coal sample and the agglomeration effect of the coal sample. When coal is mixed with associated minerals, as the particle size decreases, the cohesiveness becomes weak with the decrease of particle size.