Abstract: The flotation separation of fluorite and calcite is challenging due to their similar surface physicochemical properties,while traditional inorganic depressants suffer from poor selectivity and environmental pollution. In order to better achieve the flotation separation of fluorite and calcite,environmentally friendly carboxymethyl chitosan was employed as an organic depressant,and the impact of carboxymethyl chitosan on the flotation behavior of fluorite and calcite was investigated through single-mineral flotation experiments. Furthermore,the adsorption mechanism of carboxymethyl chitosan on the surfaces of fluorite and calcite was elucidated using zeta potential,Fourier-transform infrared spectroscopy (FTIR),and X-ray photoelectron spectroscopy (XPS) analytical techniques. The flotation experiments reveal that at a pulp pH of 7,with a sodium oleate concentration of 1. 5×10 -4 mol / L and a carboxymethyl chitosan concentration of 2. 5 mg / L,the recoveries for fluorite and calcite are 90. 59% and 49. 79%,respectively. This suggests that carboxymethyl chitosan selectively inhibits the flotation of calcite. Zeta potential measurements demonstrate that carboxymethyl chitosan significantly impedes the adsorption of sodium oleate on calcite surfaces compared to fluorite. FTIR analysis indicates the weak adsorption of carboxymethyl chitosan on fluorite and strong adsorption on calcite. XPS analysis confirms that carboxymethyl chitosan interacts with the active Ca 2+ sites on the surfaces of both fluorite and calcite through its COO - groups. 

Key words: 萤石　 方解石　 羧甲基壳聚糖　 浮选