| Iron ore is the most important raw materials in iron and steel production, however, the iron ore production in china is difficult to meet the demand of iron and steel industry currently. Therefore, it is the significant object for iron ore resource development and utilization in our county that make the part untapped iron ore resource reserves into iron ore supply. Iron ore in china with the characteristics of poor, fine, complex can result in complex mineral processing technology and difficultly processing. One of the reasons is due to the interaction among minerals, which lead to decrease in processing differences and difficult separation.Interactive effect among minerals in flotation system is the influence on flotation separation because of mineral dissolution, adsorption and covering with each other, which leads to activation or depression for other minerals in flotation system with complex ores. In this paper, hematite, siderite, magnetite, limonite, dolomite and quartz are research objects, and six minerals surface properties, flotability of different paricle size minerals and the influence of regulators on flotation of minerals are studied on the base of mineral crystal structure, chemical compositon. On this basis, the influence of different particle size minerals on flotation of hematite, siderite or quartz are researched, mechanisms of interactive effect among minerals are discussed on the base of flotation solution chemistry, mineral crystal chemistry and EDLVO theory and using these means such as SEM, UV, FTIR, ICP, XPS, in order to find the methods of weakening or enhancing the interactive effect among minerals and the methods of complex iron ore separation.The analysis of mineral crytal structure, chemical composition and bonds broken calculation showed that the PZC of hematite, siderite, magnetite, limonite and dolomite could be high, and the PZC of quartz could be low. The PZC measured of hematite, siderite, magnetite, limonite, dolomite and quartz were 5.6,7.6,6.2,7.9,4.6,2.3 respectively. The surface element concentration analysis of different particle size minerals by means of XPS found that the smaller particle size was, the more surface element concentration was, which was in favor of reagent adsorption.In sodium oleate flotation system, the results of study on flotability of minerals and on relationships between that and particle size of minerals showed that the flotability of hematite, siderite, magnetite and dolomite were best, that of limonite was better, and that of quartz was worst. The flotability of minerals had a close relationship with particle size of minerals. In alkaline conditions, CaCl2 had inhibition effect on hematite, siderite, magnetite, limonite and dolomite, and had activation effect on quartz. FeCl3, FeCl2 or starch had different effect on minerals with particle size of- 106+45μm and -18μm In the conditions of pH value of about 11.2 and adding reagents of sodium oleate. starch and CaCl2, the flotability of different particle size minerals was different. In the conditions of pH value of about 11.5, starch, sodium silicate or few citric acid had little effect on flotation of quartz activated by CaCl2, but CMC had strong inhibition effect on itThe results of research on interactive effect between two minerals showed that in the flotation process of hematite with particle size of -106+45μm, in conditions of pH value of about 9 and adding reagent of sodium oleate, the hematite recovery was reduced to some extent when different particle size minerals were added, and that was obvious when magnetite with particle size of -45μm or limonite with particle size of-18μm were added. In the flotation process of hematite with particle size of -106+45μm, in conditions of adding reagent of sodium oleate, starch and CaCll2, adding minerals except quartz had negative effect on Fe grade of concentrate, and had little effect on Fe recovery of concentrate, and adding quartz had little impact on Fe recovery of concentrate, while adding quartz with particle size of-45μm had strong impact on Fe grade of concentrate. In the flotation process of siderite with particle size of -106+45μm, in conditions of pH value of about 9 and adding reagent of sodium oleate, the siderite recovery was greatly improved when minerals with particle size of-18μm, namely, hematie, siderite, limonite, dolomite were added, the fine particles acting like "frother" could be the mineral activator of siderite flotation. In the flotation process of siderite with particle size of -18μm, in conditions of pH value of about 9 and adding reagent of sodium oleate, the siderite recovery was improved in some ways when all minerals except magnetite were added. In the flotation process of quartz with particle size of-106+45μm, in conditions of pH value of about 11 and adding reagent of sodium oleat, starch and CaCll2, adding siderite with particle size of + 18μm had most significant impact on quartz flotation, followed by adding dolomite and magnetite with particle size of-18μm, adding other minerals had little impact on quartz flotation. The recovery of quartz with paricle size of-18μm was slightly reduced when all minerals were added.The results of research on interactive effect among three minerals showed that in conditions of pH value of about 11.4 and adding reagent of sodium oleate, starch and CaCl2, adding different particle size siderite, dolomite or magnetite with particle size of-18μm had strong impact on reverse flotation of hematite, especially adding siderite. Adding sodium silicat, few citric acid or properly improving the impeller speed was helpful to improve the flotation index.The results of research on mechanism of interactive effect among minerals showed that the interaction forms among minerals contained two forms in complex minerals system. The one was indirect interaction form, namely, reagent consumption, mineral dissolution and improvement of foam stability. The other one was direct interaction form, namely, adhesive or covering among minerals. In the flotation process of hematite with particle size of-106+45μm, in conditions of pH value of about 9 and adding reagent of sodium oleate, the hematite recovery was reduced caused by sodium oleate consumption when siderite with different particle size, magnetite with particle size of-45μm or limonite with particle size of-18μm were added, and the hematite recovery was reduced caused by mineral dissolution in addition when siderite were added. Meanwhile, adding dolomite with different particle size could affect the hematite recovery caused by both sodium oleate consumption and dissolved metal ions. In the flotation process of siderite with particle size of-18μm, in conditions of pH value of about 9 and adding reagent of sodium oleate, adding hematite with different particle size could slightly improve the siderite recovery caused by hydrophobic attractive fore. In the flotation process of quartz with particle size of-106+45μm, in conditions of pH value of about 11.4 and adding reagent of sodium oleate, starch and CaCl2, adding siderite could affect the quartz recovery caused by both starch and siderite dissolution, and adding magnetite with particle size of-18μm could affect the quartz recovery caused by covering among mineals. The impact on flotation of quartz had become weakened to a certain extent by adding little citric acid caused by dispersion of citric acid, reducement of OH" concentrate and consumption of CO32- The effect differences of FeCl3 or FeCl2 on flotation of siderite with different particle size or of limonite with different particle size were related to chemical adsorption.Finally, the experiment research on flotation separation of magnetic separation concentrate of carbonate-containing refractory iron ore from Dong Anshan were carried out, and a good experiment result had been achieved through weakening interactive effect among minerals by adding little citric acid. Under the best conditions, a iron concentrate with Fe grade of 66.37% and Fe recovery of 75.00% was obtained by adopting the closed-circuit flowsheet. The results showed that the product quality was improved, the technological process was simplified, and the production cost was reduced by adding little citric acid in flotation.The research results in this paper had enriched the theory system of iron ore flotation and a set of research method of interaction among minerals in flotation system was formed, which had the reference value in the research of interaction amongs other minerals in flotation system. |
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