How to Address Significant Fine Sand Loss

In the sand washing industry, is an essential piece of equipment in any . During wet sand washing, fine and surface sand are inevitably lost with the wastewater flow, resulting in a loss of 5% to 25% per production line. Recovering these lost materials can significantly boost profitability. This article outlines four effective methods for recovery.

Regardless of the type of , agitation during the washing process causes most sand particles to be carried away by the water, leading to unclear separation and inevitable material loss.

Four Methods for Fine Sand Recovery

1. Implement a Multi-Stage Sedimentation Tank

Sand washing wastewater flows into the sedimentation tank, which is preferably equipped with three layers to allow for gradual layer-by-layer settling over time. Due to the higher specific gravity of sand and mud, they can be effectively separated after prolonged precipitation. However, this method has notable drawbacks: the extended sedimentation process requires a large footprint for the tanks, and subsequent manual excavation of settled sand and mud is both time-consuming and labor-intensive.

2. Equipped with dewatering screen equipment

Sand washing wastewater is discharged directly onto the surface of the linear dewatering screen to recover lost fine sand.
The limitation of this approach is that it works well only if the raw material contains little or no mud. If the mud content is too high, the final stage becomes ineffective, preventing any meaningful recovery; instead, the output remains a mixture of mud and sand.

3. Configure fine sand recovery machine

The wastewater from sand washing is discharged directly into the lower water tank of the fine sand recovery unit. The mixture of sand and muddy water is then pumped to the cyclone separator and discharged onto the screen surface by the slurry pump. Fine sand is discharged along the screen surface, while mud and water are separated. The water flows back to the lower tank to form a closed loop, continuously recovering sand from the wastewater.

4. Add chemical agents

Discharge the lost sand and water into the settling tank and add chemical agents that cause the mud and sand to rapidly coagulate into flocs, achieving quick separation of sand and water. However, this method is primarily used in the coal slime industry for the recovery and utilization of refined coal and fine coal. Its application in sand and gravel plants has certain limitations and cannot be widely adopted at present.