Experimental research on combined magnetic separation and flotation for coal gasification fine slag

ABSTRACT

To address the challenging issue of achieving high-precision carbon-ash separation in coal gasification fine slag, magnetic separation and flotation techniques were employed to study their respective separation effect. Optimization tests were conducted to determine the optimal magnetic field gradient and magnetic field intensity, and the ash content of magnetic separation concentrates was 72.18%, with a reduction of 7.28% compared to the sample. Additionally, the magnetic separation tailings exhibited an ash content of 93.99%. Through flotation tests, the optimum conditions for kerosene and composite collector was established. The ash content of flotation concentrates decreased by 16.39% compared to the sample, and the ash content of flotation tailings was 95.83%. A comparative analysis revealed that the combined separation process outperforms single separation methods in reducing the ash content of the concentrates, and realize the further quality improvement and separation effect. Detailed analysis of magnetic characteristics and XRD, XPS analysis studies on the sample and the products, indicated that the magnetic separation effectively pre-removes a certain amount of magnetic high ash minerals. Furthermore, the collector treatment significantly increased hydrophobicity difference between residual carbon and ash matter, which ultimately enhancing the flotation effect.

KEYWORDS:

• Solid waste
• coal gasification slag
• magnetic separation
• flotation
• separation process

Acknowledgments

This research was financially supported by grants from the National Natural Science Foundation of China (52104262), the Joint Funds of the National Natural Science Foundation of China (U23A20131), and the National Key Research and Development Plan (2023YFB4103501, 2022YFB4101604). This work thanks the Instrument Sharing Service Platform of Taiyuan University of Technology for the assistance of the SEM tests and the laser particle size analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Key Program of the National Natural Science Foundation of China [U23A20131]; National Key Research and Development Program of China [2023YFB4103501]; National Key Research and Development Plan [2022YFB4101604]; Natural Science Foundation of China [52104262].