Abstract: The study is made on the crucial technical bottlenecks that restrict the sharpness of separation of coarse coal slime, with the 1-0.25 mm size slime produced by Taixi Coal Preparation Plant as the object of study.Based on the study result, a combined separation process using high-precision classifying cyclone and TPS is adopted for fine separation of the slime.In this process, the middling product of TPS is sent back to the separator for secondary separation.because of the use of new equipment and new technology as well as the optimization of the structural and operating parameters of the 3-product TPS, a clean coal product with a ultralow ash of < 3.00% is produced.The successful industrial application of the technology shows the size range of separation of coarse slime can be further expanded.