| Dong Anshan Sintering Plant is one of those process refractory iron ore in China. With an increase in mining depth, the content of carbonaceous iron ore (main siderite) goes up significantly, which deteriorates the regular floatation of hematite and affects the production of Donganshan Sintering Plant dramatically, so about100million ton such minerals must be piled up each year because can’t be dealed with well. According to the properties of such minerals, Northeastern University developed a two-step flotation process to recover them effectivly, which siderite is removed in the first-step floatation and hematite is separated by conventional flotation in the second step. Good results have been obtained both in laboratory and industrial tests, which can provide a base for utilization of the ore. By the first step, the product with iron grade around40%is still worthwhile to recover. The sintering experimental research of the middlings containing siderite showed that, the sinter quality will be seriously affected when middlings used as sintering ingredients directly. To improve its quality to meet the requirements as sintering ingredients, the subject adopted flotation method for its iron increase and silicon reduction.Because the nature of mixed magnetic concentrate given into the two-step flotation process is not stable, there is a big difference between iron grades of middlings which obtained in different time also. The paper studied on two iron grade middlings gained in different period of stable production. The results of technological mineralogy of the middlings indicated that, the iron grades of the two middlings were42.96%and37.20%respectively, and the characteristics of both were similar, in which major iron ore contents were both hematite, magnetite and siderite, and the gangue minerals were quartz and little chlorite, dolomite, etc. At the same time, they both belong to low P and S ore samples, with superfine granularity.Through the exploration, the topic introduced a dispersant with special effects named YJ, which can make particles of ore samples just in uniform and stable decentralized state, and be helpful for separation.Through research on anionic reverse flotation condition tests of middlings containing siderite with grade of42.96%, suitable rougher flotation conditions were got, then open-circuit and closed-circuit tests were carried out separately, in which the concentrate with grade of56.20%and recovery of57.10%was gained in finally, And its content of SiO2was8.14%.Based on the suitable flotation condition results of middlings with grade of42.96%, a coarse-a concentrating open-circuit condition tests of middlings with grade of37.20%were conducted. Then small closed-circuit test in laboratory was carried out, from which a concentrate with grade of56.89%and recovery of43.50%was obtained, and its content of SiO2was in less than9%.Flotation tests on two kinds of middlings containing siderite indicated that, a coarse-a concentrating flow could deal with them well, so it’s the rational flow for the middlings recovering. And the suitable flotation conditions of middlings with grade of37.20%were got from improvement on the basis of conditions of middlings with grade of42.96%, so they could be used as industrial experiment reference conditions for dealing with the middlings.In addition, thermogravimetric analysis, XRD analysis and scanning electron microscope analysis were implemented to investigate the recycle mechanism of the middlings containing siderite. And the flotation kinetics study was put into effect on the flotation process, through which a very anastomotic recovery double model was established, and therefore a theoretical basis can be provided for comprehensive utilization of this kind of ore. |
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