Sand resource extraction from waste soils by hydro-cyclone method assisted with reagents

The generation of waste soils is an inevitable result of engineering construction activities such as foundation excavation and tunnel construction. The effective management and utilization of these waste soils pose significant challenges for engineers. Previous research has explored using a hydro-cyclone separation principle to segregate sand from waste soil, but the efficiency of this method remains limited. This study has developed a technology incorporating chemical reagents to enhance hydro-cyclone separation efficiency. Including these reagents significantly improves the separation effect of sand-clay mixture samples, via sedimentation experiments. A corresponding reagent index evaluation method has been proposed, determining the optimal reagents from three dimensions separation efficiency, reagent concentration, and pH value. These reagents are then subsequently applied to the hydro-cyclone device. The results show that samples added with polycarboxylate can achieve a maximum sand resource separation efficiency of 95.7%. Compared to the sand extraction efficiency without added reagents, the maximum sand extraction efficiency increased by 1.4 times. Predictive equations for sand extraction efficiency and applicable technological processes have been proposed for waste soils to facilitate the application of the technology.