Study on the separation and quality improvement of <6 mm low rank high sulfur lignite by vibration airflow dry separation bed

• Published in: Separation science and technology Vol. 60; no. 13; pp. 1821 - 1838
• Main Authors: Zhou, Hejun, Li, Bochao, Yu, Xiaodong, Luo, Zhenfu, Geng, Shaowei
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 02.09.2025
• Subjects: airflow distribution; desulfurization and ash reduction; low rank high sulfur lignite; particle migration; Vibrating air dry sorting bed
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1080/01496395.2025.2512353

Coal, as a crucial primary energy source, plays a significant role in global economic development and human society. In recent years, due to the sharp decline in high-quality coal resources, lignite has been extensively exploited and utilized. This study employs a vibration airflow dry separation bed to upgrade and desulfurize low-rank, high-sulfur lignite within the particle size range of 6-0 mm. The research primarily focuses on the characteristics of airflow distribution in the bed surface areas and its impact on the sulfur content distribution of materials on the bed surface. A systematic analysis is conducted to examine the influence of amplitude and frequency on the diffusion behavior of density-differentiated particles. Furthermore, the distribution pattern of product quality across transverse sections of the bed under optimal operating conditions is explored. Experimental results indicate that when the inlet airflow velocity is U = 2.06 m/s, the airflow velocities in areas I, II, and III of the bed surface are U I  = 2.06 m/s, U II  = 1.89 m/s, and U III = 0.87 m/s, respectively, exhibiting a stepped distribution pattern. Along the OX axis of the bed surface, the sulfur content distribution in the material within the 0-500 mm, 500-600 mm, and 600-1000 mm areas is 0.91-1.13%, 4.67-5.34%, and 15.32-22.16%, respectively. When the amplitude is A = 2.4 mm and the frequency is 0f = 20 hz, the sulfur content distribution ranges within the 0-400 mm, 400-600 mm, and 600-1000 mm areas along the OX axis are 0.91-1.12%, 4.87-6.45%, and 15.87-18.40%, respectively, with the corresponding sulfur segregation degree of S sulfur  = 1.03-1.12. At this stage, the spatial density gradient distribution of the bed layer within the separation bed is distinctly evident, yielding optimal separation performance. Separation experiments conducted under the optimal parameters resulted in a clean coal yield of 70.91%, with a sulfur content of 0.98% and an ash content of 9.89%. Meanwhile, the gangue yield was 29.09%, with a sulfur content of 17.95% and an ash content of 62.27%. The probable error value was E p  = 0.055 g/cm 3 , successfully achieving efficient upgrading of low-rank, high-sulfur lignite.