Influence of Mechanical Grinding on Particle Characteristics of Coal Gasification Slag

Abstract

Based on the test results of laser particle size analyzer, specific surface area analyzer and infrared spectrometer, the grinding kinetics of coal gasification slag (CGS) was systematically described by using Divas–Aliavden grinding kinetics, Rosin–Rammler–Bennet (RRB) distribution model and particle size fractal theory. The influence of grinding time and particle group of CGS on the strength activity index of mortar was studied by using the strength activity index of mortar and grey correlation analysis. The results show that the particles are gradually refined before mechanical grinding of CGS for 75 min. When the mechanical grinding time is greater than 75 min, the “agglomeration phenomenon” of fine CGS particles led to the decrease in various properties. Divas–Aliavden grinding kinetics, the RRB model and fractal dimension can characterize the change of CGS particle size in the grinding process quantitatively. The strength activity index of CGS at different curing ages is positively correlated with grinding time, and the influence on the later strength activity index is the most obvious. The relationship between CGS particle size distribution and strength activity index were probed using grey correlation analysis. The CGS particle groups with the particle size of 20~30 μm and 10~20 μm have the greatest impact on the early and late strength activity index, respectively. Therefore, the optimal grinding time of CGS as auxiliary cementing material is 75 min, considering factors, such as economy and performance, and the specific surface area (SSA) is 4.4874 m2·g−1.

Experimental Study on Early Strength and Hydration Heat of Spodumene Tailings Cemented Backfill Materials

“…One part is the hydration reaction of tricalcium silicate (C3S) contained in cement (the second exothermic peak of ordinary cement-based materials). The other part is the hydration reaction of tailings, the third exothermic peak, which is similar to the exothermic hydration curve produced by adding blast furnace slag [54] or iron tailings [22] to cement. Second, the new exothermic peak is related to the hydration reaction of C3A.…”

“…The hydration reaction and microstructure evolution of the filling material is the internal driving force for strength formation. The difference in physical and chemical properties of different material components directly affects the hydration process of backfill materials [22,23]. Accurately understanding the change law of the hydration process and the evolution law of microstructure of cemented backfill materials is conducive to analyzing the development law of early strength, thus controlling the backfill material strength formation process and providing reasonable process parameters [24][25][26][27].…”