Resources recovery from coal gasification residue by combined hydrocyclone and vibrating screen and characterization of separated products

Abstract

Coal gasification fine slag (CGFS) is a solid waste rich in residual carbon and various inorganic elements produced in the process of coal gasification, and components separation is a prerequisite for its resourceful utilization and harmless disposal. In this paper, a CGFS sample was separated by a combined process of hydrocyclone and high-frequency vibrating screen (HFVS), and three products were obtained by optimizing separation parameters. The properties of each product were analyzed by XRD, XRF, SEM, BET, and TG-DSC. The results showed that the effective separation of residual carbon and ash in CGFS could be achieved at the hydrocyclone feeding pressure of 0.04 MPa and the HFVS aperture size of 0.074 mm, and LOI of the obtained concentrate, middling, and tailing products were 78.57%, 38.17%, and 20.42%, respectively, with a total recovery of residual carbon in concentrate and middling reaching 88.19%. Concentrate particles are mainly irregular or flocculent carbon with well-developed and comprehensive types of pores, as well as high calorific value and good combustion characteristics, which can be used to prepare porous adsorbent materials or as high-quality fuel. Middling is rich in aluminum and silicon elements, and it contains certain mesoporosity, calorific value and moderate combustibility, which suitable for preparing carbon-silicon composites or firing porous ceramics. Tailings have little residual carbon content but mainly consist of tiny spherical particles rich in inorganic element species and content, and it have fewer internal pores and low calorific value, which are suitable for the preparation of building materials, aluminum/silicon-based materials, or ecological restoration materials. This study provides important guidance for resource recovery and utilization of CGFS.