Study On Separation Technology And Mechanism Of Siderite And Hematite

In iron mining industry there is a general trend that the content of siderite increases with the depth of iron ore, more importantly, current production practice showed that the high content of siderite had a detrimental influence on reverse iron flotation process.On the basis of the summary and analysis of many related references, some sets of experiments has been carried out with respect to flotation, such as flotation of pure mineral and the real ore, use of new reagents, action mechanism of the reagents and so on; flowsheet structure and reagent system were researched systematically; and the action mechanism was sufficiently proved by dispersion force test, Zeta potential measurement, flotation solution chemistry, X-ray photoelectron spectroscopy testing analysis and infrared spectroscopy.The test results of pure minerals indicate that the depressive effect of a-starch on siderite and hematite had great difference; siderite was depressed slightly while hematite intensively.The test results of the real ore show that an iron concentrate of 65.67% Fe was obtained with a recovery of 60.32% through flotation, and the flotation flowsheet is'selective flotation- reverse flotation'while using Na2CO3 and a-starch as dispersants and W69 as collector. An important technical parameter was determined that the presence of siderite in the reverse flotation feed should be less than 3.8% in terms of mineral content to avoid the bad effect of siderite on reverse flotation.The results of dispersion force tests show that siderite and hematite present remarkedly different dispersion behavior when the dosage of Na2CO3 reached certain concentration in the pulp, and this was beneficial for other reagents to react on the mineral surface.The Zeta potential measurements illustrated that sodium oleate could make the Zeta potential of siderite greatly decreased and correspondingly its PZC shifted from 6.1 to 4.0, which showed that sodium oleate had been adsorbed intensively on the siderite.When pulp pH was above 10, the Zeta potential of siderite raised after a-starch was adsorbed on its surface, and resultantly the collector was able to promote the adsorption of anionic collector on the siderite surface.The results of X-ray photoelectron spectroscopy testing show that only Fe3+ influenced the Zeta potential of siderite intensively. In alkaline aqueous medium, CO32- and Fe2+ hydrolyzed, so the mineral surface was covered by hydroxyl, and parts of Fe(Ⅱ)were turned into Fe(Ⅲ).The results of infrared spectroscopy show that the main adsorption manner ofα-starch on the siderite was chemical adsorption, which generated new characteristic peak on the surface of siderite, and caused a depression of siderite to some extent. Additionally, the adsorption manner ofα-starch on the hematite was also chemical adsorption; and other than Van der Waals forces, there was hydrogen bond, which made the hematite quite hydrophilic, achieving its depression.