粒度级配对制备高浓度水煤浆的影响

选取典型低变质程度神木柠条塔(NTT)煤,进行球磨式连续型粒度级配提高水煤浆浓度(一定量的水煤浆试样在105℃~110℃干燥至恒重,干燥后试样质量占原样质量的百分数)和成浆性的研究。在不同球磨条件下,考察球磨时间、球磨速度对成浆浓度、流变特性和稳定性能的影响规律,研究粒度级配前后浆体表面润湿性、表面电负性、微观形貌的性能变化对NTT煤成浆性的影响,利用分形维数的计算,进一步探究了粒度级配对提高NTT煤制浆浓度的影响机理。结果表明:在级配M煤样(D50=79.02μm)与M₆煤样(D50=8.727μm)的质量比为8∶2时,成浆浓度与未级配煤样相比提高了约4%;不同球磨条件下的煤样按照不同的质量比进行混合制浆时,初始添加细颗粒使浆体表面的润湿性增强,降低了浆体的性能,当粗细颗粒的质量比大于6∶4时,表面润湿性的变化较小;级配样的成浆浓度与Zeta电位的绝对值呈正相关;当级配煤样之间粒径相差逐渐变大,小颗粒填充到大颗粒孔隙中,增加了空间堆积率,提高了制浆浓度,但随着细颗粒的质量分数增大,大颗粒孔隙被撑开,煤粒空间堆积率下降,制浆浓度降低;M煤样与M₆煤样在质量比为8∶2时,相比于其他级配浆体,分形维数达到最大(2.460),成浆浓度达到最高(63.03%)。

Effects of Particle Size Matching on Preparation of High Concentration Coal Water Slurry

Investigation on the improvement of slurry concentration as well as the slurry properties of coal water slurry by continuous size grading in the ball mill was conducted in this paper.A typical low-degradation Shenmu Ningtiaota(NTT)coal was selected as the research objective.In different milling conditions,the effects of milling time and milling speed on the slurry concentration,rheological properties and stability were discussed.The surface wettability,surface electronegativity and particle microstructure can vary before and after size grading,and their effects on the slurry properties of NTT coal were also investigated.In addition,the influencing mechanism of particle size grading to improve the slurry concentration of NTT coal slurry was further analyzed by using fractal theory.The results show that when the mass ratio of graded coal sample M(D50=79.02μm)to M₆(D50=8.727μm)is 8∶2,the slurry concentration is increased by 4%compared with the ungraded coal sample,approximately.The coal samples in different ball milling conditions were mixed and pulped according to different ratios.The initial addition of fine particles evidently increases the wettability of the slurry surface and reduces the performance of the slurry.When the mass ratio of coarse and fine particles is greater than 6∶4,the surface wettability was excepted to have small influence.The slurry concentration of grading samples shows a positive correlation with the absolute value of Zeta potential.When the difference in particle size among graded coal samples gradually increases,the small particles can fill into the pores of large particles,leading to the increase of the space accumulation rate as well as the slurry concentration.Nevertheless,as the content of fine particles increases,the pores of large particles may open,thus the space accumulation rate of coal particles decreases and the slurry concentration decreases.When the mass ratio of M to M₆ is controlled at 8∶2,compare with other graded slurries,the fractal dimension reaches a maximum of 2.460,and a maximum slurry concentration can be obtained(63.03%).