Selective depression of low-molecular-weight carboxylated starch in flotation separation of forsterite and ilmenite

Flotation separation of ilmenite and forsterite is challenging owing to their similar natural floatability. In this work, low-molecular-weight carboxylated starch (LMWCS) was prepared as a selective depressant for forsterite and ilmenite separation via flotation. Compared with conventional natural starch, LMWCS has stronger depression on forsterite flotation. X-ray photoelectron spectroscopy analysis confirmed that LMWCS was adsorbed onto the ilmenite surface via the formation of weak hydrogen bonds, whereas it adsorbed onto the forsterite surface via strong chemisorption. The adsorption layer density of LMWCS on the forsterite surface was higher than that on ilmenite according to atomic force microscopy and quartz crystal microbalance with dissipation analyses. Therefore, LMWCS is an effective and promising depressant for forsterite flotation.