Abstract:

Coal gasification fine slag (CGFS) is a solid waste produced in the process of coal gasification, and its resource utilization problems restrict the green and low-carbon development of coal chemical industry. The characteristics of CGFS, such as fine particle size, small mass and low momentum, cause serious entrainment of high ash content fine particles in foam products during flotation, which affects the quality of flotation concentrate. In this paper, the graded flotation process was used to optimize the flotation conditions of CGFS. The carrier flotation process was used to study the effect of carrier ratio on the flotation efficiency of CGFS with a particle size of +0.045mm. The research results indicated that increasing the carrier ratio could significantly enhance the flotation effect. Under the designed experimental conditions, the flotation perfection index reached to 71.53%, and the combustible recovery was 87.57%, which was 20.57% higher than the conventional flotation without carrier. The interaction force between carrier and CGFS was calculated using EDLVO theory. During the carrier flotation process, the electrostatic force between carrier and CGFS showed attraction, which was prone to adhesion behavior, promoting the aggregation of fine particles and improving the flotation effect. The flocculation flotation method was adopt for -0.045mm particle size. With the increasing of flocculant dosage, the flotation perfection index of -0.045mm size CGFS showed a trend of increasing first and then decreasing, the highest flotation perfection was 39.61%, and the ash content of flotation concentrate was not significantly reduced. The flocculation analysis showed that the addition of flocculant promoted the non-selective agglomeration between particles, which led to the high ash content of the flotation concentrate, and the selective flocculation effect should be further improved subsequently. The CGFS classification flotation process proposed in this study has certain theoretical guidance for reducing the entrainment of fine and high ash content particles on flotation, and further improving the quality of refined carbon products.

Key words: coal gasification fine slag, flotation, classified flotation, carrier flotation, flocculation flotation, EDLVO theory

摘要：

煤气化渣是煤气化过程中产生的固体废弃物，其资源化利用制约着现代煤化工产业绿色、低碳发展。煤气化细渣粒度细、质量小、动量低的特点造成浮选过程中高灰分微细矿物在浮选泡沫产品中的夹带，严重影响了浮选精炭产品质量。本文采用分级浮选的工艺对煤气化细渣进行了浮选条件优化。+0.045mm粒度级煤气化细渣采用载体浮选，研究了载体添加比例对浮选效果的影响。结果表明，提高载体添加量可显著增强浮选效果，在设计实验条件下，浮选完善度达到71.53%，浮选精炭产品可燃体回收率为87.57%，相较于未添加载体的常规浮选方法提高了20.57%。通过EDLVO理论计算了载体颗粒与煤气化细渣颗粒间的相互作用力，载体浮选过程中，载体颗粒与煤气化渣残炭颗粒之间的静电作用力表现为吸引力，容易发生黏附行为，促进了微细颗粒的团聚，提高了浮选效果。-0.045mm粒度级采用絮凝浮选的方法，随絮凝剂用量的增加，颗粒絮团体积增大，-0.045mm粒度级浮选完善度呈先增大后减小的趋势，最高为39.61%，浮选精炭产品灰分降低不明显。絮团图像分析表明，絮凝剂的加入促进了颗粒之间的团聚，增大了颗粒的表观粒度。但非选择性团聚导致浮选精炭产品灰分偏高，后续应进一步提高絮凝选择性。本研究提出的煤气化渣分级浮选工艺对于降低微细粒高灰颗粒对浮选精炭的夹带作用，进一步提高精炭产品质量具有一定的理论指导意义。

关键词: 煤气化渣, 浮选, 分级浮选, 载体浮选, 絮凝浮选, EDLVO理论