Owing to insufficient shear force in conventional hydrocyclones, organic matter adhering to the surface of fine inorganic sand cannot be removed, resulting in excessively high organic matter contents in underflow, which hinder secondary utilisation of inorganic sand. This study proposes a combined cone-type hydrocyclone for reducing the organic matter content in underflow by increasing the shear force and expanding the separation space. Experimental testing was conducted to investigate the influences of structural parameters, such as the apex diameter and spherical-cone radius, on the separation performance of the hydrocyclone. Results indicate that reducing the apex diameter decreases the inorganic content in underflow from 81.36% to 73.51%; meanwhile, increasing the sphere-cone radius and step shrinkage distance first increases and then decreases the inorganic content in underflow. A response surface method was used to construct a prediction model for the separation performance. The optimal parameter combination is obtained, with the inorganic yield in underflow reaching as high as 68.97%.