Research on the differences in physicochemical properties and flotation behavior of pyrolusite, quartz, and diaspore before and after phase transformation

• Upon reduction roasting, pyrolusite was converted into new generated manganosite, diaspore was transformed into new generated aluminium oxide, while quartz remained unaltered. • The phase transformation of diaspore to new generated aluminium oxide was accompanied by an increase in both porosity and pore size. • For pyrolusite, the surface of the roasted product became smoother and denser compared to that of the raw ore. • Reduction roasting enhanced the surface hydrophilicity of the minerals, making them more difficult to float. The initiation of the reduction process induces intricate alterations in the surface properties of the minerals, thereby exerting a pronounced influence on their flotation performance. The chemical bonds on the quartz surface display partial ionic and partial covalent character. The Al–O bonds on the surfaces of diaspore and the Mn–O bonds in new generated manganosite exhibited a higher ionic character and this results in an increase in active sited and enhanced adsorption reactivity. Quartz underwent no lattice reconstruction during roasting. The phase transformation of diaspore to new generated aluminium oxide was accompanied by an increase in both porosity and pore size. These structural modifications were likely responsible for the higher reagent consumption observed during the flotation of the roasted product. For pyrolusite, the surface of the roasted product became smoother and denser compared to that of the raw ore. The decreased specific surface area and the altered pore structure hindered the formation of a stable hydrophobic film, adversely affecting flotation performance. The contact angles of the roasted products were consistently smaller than those of the raw ore, confirming that reduction roasting enhanced the surface hydrophilicity of the minerals, making them more difficult to float.