Study on Calcination Catalysis and the Desilication Mechanism for Coal Gangue

Abstract

Coal gangue is a solid waste discharged during coal mining, which not only occupies large land resources but also brings about certain risks to the environment. The alumina and silica minerals in coal gangue are the major resources and difficult to separate from each other, which hinders the resource utilization of coal gangue. The catalytic effect of various additives on the phase transformation process of coal gangue is studied in this paper to strengthen the separation of silica from alumina minerals and to increase the resource utilization rate of coal gangue. The study results show that the silica-containing minerals in coal gangue can be promoted to transform into mullite by alumina-based additives. The soluble active silica is released during phase transformation in the calcination process, which has a positive effect on the caustic desilication after calcination. The secondary aluminum dross has a positive catalytic effect on the active silica released during calcination. The alumina to silica ratio of the desilication product can be increased from 0.91 to 1.94 and the desilication rate can be increased from 42.99 to 56.16% by 6% secondary aluminum dross addition. The solid slag after desilication can be used to extract an alumina source for the synthesis of molecular sieve products with the silica source obtained by the desilication process so that the high-value resource utilization of coal gangue can be realized.

Porous alkali‐activated material from hypergolic coal gangue by microwave foaming for methylene blue removal

“…[1][2][3] Owing to the rapid growth of the coal mining industry, the total amount of CG is rising sharply and gradually becoming one of the most significant industrial solid residues; global CG production was about 0.7-1.5 billion tons in 2020. 4 According to the Guizhou Energy Administration, owing to the rapid expansion of coal production capacity, the quality of raw coal in China has decreased, and the ash content has increased since 2016. At the same time, the degree of coal mining mechanization and the scale of raw coal washing have gradually expanded.…”

Self-Combustion–Depolymerization Approach to Activate Solid-Waste Coal Gangue Minerals for Fluid Catalytic Cracking Catalyst Synthesis

“…10–20% of the coal production . In 2020, approximately 0.7–1.5 billion tons of coal gangue was discharged globally . Due to its low calorific value, coal gangue is usually discarded on-site, leading to the occupation of large land areas and the waste of natural mineral resources.…”

“…Despite all of these efforts, it is still challenging to achieve the high-value use of coal gangue. Coal gangue contains more than 90% of SiO 2 , Al 2 O 3 , and carbon, among which carbon accounts for 2–20% . The mineral composition of coal gangue mainly includes kaolinite, quartz, and illite, which closely depends on its geographical origin.…”

Compressive and Flexural Properties of Ultra-Fine Coal Gangue-Based Geopolymer Gels and Microscopic Mechanism Analysis

“…Coal gangue is a solid waste generated in the process of coal mining and washing, accounting for approximately 10% to 15% of the total coal output [ 6 ]. Global coal production was about 7.4 billion tons, and coal gangue emissions were about 15–70 million tons [ 7 ]. The total amount of coal gangue in China has reached 6 billion, with an annual generation of 5–8 million tons [ 8 , 9 ].…”