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EN
In this paper, the influence of sodium hexametaphosphate (SHMP) in coal slime flotation was studied, and the interaction between SHMP and coal slime flotation particles was revealed through XRD test, contact angle measurement, zeta potential test, scanning electron microscopy analysis, XPS analysis, and DLVO theoretical calculation. The experimental results show that when the dosage of SHMP is 1500 g/t, the recovery rate of clean coal combustibles increases by 9.61 %. SHMP reduces the hydrophobicity of clay minerals (kaolinite) in coal slime flotation and also enhances the dispersibility of coal slime particle. Scanning electron microscopy and energy dispersive analysis showed that SHMP reduced the number of clay particles (kaolinite) on the coal surface, thereby reducing the ash content of the clean coal. In this paper, SHMP is mainly used to modify the surface of kaolinite so as to reduce the hydrophobicity of the mineral, that is, to improve the recovery rate of clean coal combustibles in coal slime flotation.
EN
Fluorite and calcite have similar surface properties and natural floatability, so their flotation separation has always been a problem faced by the beneficiation industry. The key to flotation separation is the choice of depressants. Sodium hexametaphosphate (SHMP) has a good effect on fluorite calcite selective inhibition. In this paper, the effects of Zn2+ on the selective inhibition of SHMP in the flotation process of fluorite and calcite were studied through single mineral and artificial mixed mineral flotation experiments. Solution chemical calculation, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared spectroscopy (FT-IR) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analyses investigated the mechanism of action of Zn2+, which had the most significant negative effect on the selective inhibition of SHMP. The results show that the main components of SHMP inhibiting minerals are HPO42- and H2PO4-, which can react with Ca active sites on the mineral surface to form hydrophilic Ca(H22PO4)2 and CaHPO4, while Zn2+ The presence of HPO42- in solution resulted in the formation of stable ZnHPO4 complexes, thereby weakening the inhibitory effect of SHMP on minerals.
EN
Flotation using sea water has been considered as a promising alternative to concentrate molybdenite (MoS2) under alkaline conditions due to scarcity of fresh water and increasingly strict regulations on the quality of discharged water. However, the MoS2 recovery with sea water during flotation has not been satisfactory, owing to the depressing effects from the hydrophilic metallic species onto MoS2 surface. This study combines experimental and theoretical studies of MoS2 flotation to investigate how the physicochemical properties of MoS2 vary with the addition of a dispersant, sodium hexametaphosphate (SHMP), and in sea and fresh water. Our experimental results show that the addition of SHMP during flotation has increased the recovery of MoS2, via reducing the adsorption of the hydrophilic metallic precipitation onto MoS2 surface. The DLVO calculation confirms that the addition of SHMP increases the floatability of MoS2 by dispersing the formed hydrophilic metallic precipitation (Mg(OH)2 colloids) from the MoS2 surface, via reversing attraction force to repulsion force, thereby improving MoS2 flotation recovery.
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