Application and mechanism of DTPMP in flotation separation of fluorite and calcite
Fluorite(CaF2)is an important strategic mineral,which is often closely intergrown with calcite(CaCO3).Froth flotation is the main method for separating the two calcium-bearing minerals,but the selective separation of fluorite and calcite has always been a worldwide problem due to the similar calcium active sites on their surfaces.Sodium silicate is often used in fluorite flotation to depress calcite and enrich fluorite.However,the low selectivity and large amount of sodium silicate will not only lead to some fluorite being depressed and unable to be recovered,but also bring about the problems of difficult settlement for tailings particles and low efficient treatment in tailings wastewater.Therefore,the reverse flotation idea of depressing fluorite and collecting calcite by a green fluorite depressant named diethylene triamine penta methylene phosphonic acid(DTPMP)was proposed.The results of flotation tests of single minerals,binary mixed minerals and real ore indicate that fluorite can be enrich by reverse flotation with sodium oleate(NaOL)as collector and low dosage of DTPMP as depressant at neutral pH.The adsorption capacity test and fourier transform infrared spectroscopy(FTIR)confirm that the adsorption of DTPMP on fluorite surface has more adsorption capacity and stronger adsorption strength than calcite.The density functional theory(DFT)calculation results reveal that DTPMP is more easily adsorbed on the fluorite surface,and the H atom in the phosphonic acid group of DTPMP has a strong hydrogen bonds with the F atom on the fluorite surface.Therefore,as a green and efficient fluorite depressant,DTPMP has a good industrial application prospect in flotation field.
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