Sand resource extraction from waste soils based on the hydro-cyclone separation principle

Abstract

For engineering waste soils with a large proportion of sand resources, an effective technique for sand extraction from waste soils still needs to be developed. This study investigates the degree and efficiency of sand resource extraction based on a hydro-cyclone separation principle via a series of experiments. The soil samples in the experiments contained a sand content ranging from 12.56% to 52.75% and a water content ranging from 155.96% to 597.04%. The results show that the water contents of test samples should reach a certain threshold to perform hydro-cyclone separation, and appropriately increasing the water content will have a positive effect on the separation degree, which can achieve a maximum value of 73.26%. However, the separation degree reaches an upper limit value when the water content is greater than approximately 400%, which is revealed by the characteristics of soil viscosity varying with water content, and high-water content for the separation efficiency is not beneficial. To balance the separation degree and efficiency, optimum sample water contents for sand extraction and an evaluation approach for different sand content samples are proposed. Through application of the proposed approach, an average sand extraction efficiency of 135.88 g/s can be achieved.