Abstract: This study addresses the challenge of high moisture content in coal slime filter cakes and the difficulties associated with their resource utilization by proposing a low-cost deep dewatering process utilizing ambient air drying. Using coal slime from the Jining No. 2 Coal mine as the raw material, the research systematically investigates the effects of material layer thickness, through-flow air velocity, air temperature, and relative humidity on dewatering efficiency. The results indicate that thinner material layers, higher air velocities, elevated air temperatures, and lower humidity levels contribute to increased dewatering rates. Under conditions of 6 m/s air velocity, 25 ℃, and 50% humidity, the moisture content of the coal slime can be reduced from 28.5% to below 20% in just 22 minutes, and to below 15% in 36 minutes. Compared to high-temperature drying methods, this process poses no explosion risk, consumes less energy, and generates less dust. This study presents a cost-effective, safe, and easily implementable approach for the deep dewatering of coal slime in coal preparation plants.