Separation And Utilization Of Siderrite From Dong Anshan Refractory Iron Ore

Donganshan Sintering Plant is one of those which process refractory iron ore in China. Its ores, mainly from Donganshan and Xianshan are fine disseminated and of low grade and complex structure. The iron ores are divided into non-oxidized, semi-oxidized, oxidized, ferrous iron ore and iron ores containing siderite or chlorite. The iron ores containing siderite are from eastern and western orebody, with the latter accounting for25%of the total. Owing to siderite, this type of ore can not be separated effectively. With an increase in mining depth, the content of siderite goes up significantly, which affects the production of Donganshan Sintering Plant dramatically, and can even destroy the regular floatation of hematite, without any separation of the concentrate and tailings. So, about one million of this type of ore is piled up. A two-step flotation process has been developed. Siderite is removed in the first-step floatation and hematite is separated by conventional flotation in the second step. Good results have been obtained by continuous dressing in laboratory, which can provide a base for industrial utilization of the ore.By the first step, the product with TFe grade around38%and in which siderite and hematite were main minerals, was worthwhile to recover. In this paper, study on technological mineralogy of the middlings was carried out, including analysis of chemical multielement and iron phase. The results indicated that TFe grade of the middlings was37.66%, and the contents of siderite iron silicate and SiO2were respectively9.42%,14.62%and29.59%. According to the results, siderite and hematite can be recovered.In this paper, investigation on reutilization of the middlings containing siderite was carried out by three means and good results were obtained.(1) Different furnaces were adopted for reduction roasting-magnetic separation. Optimum experimental conditions were determined and iron concentrate with TFe above60%at a recovery of80%was obtained. (2) The middlings containing siderite was processed by neutral roasting and then returned to the reverse floatation of hematite in the second step. Suitable conditions were found out by experiments. Concentrate with TFe grade67.80%at a recovery of73.98%and tailings with TFe grade20.73%at a recovery of26.02%were obtained.(3) By floatation experiments for iron increase and silicon reduction, TFe grade of concentrate reached42.62%and the content of SiO2was decreased to27.41%. Thanks to high iron grade and low yield, it can be used for sintering burden.In addition, thermogravimetric analysis, XRD and scanning electron microscope study were carried out to investigate the mechanism of the recycle of the middlings containing siderite and therefore a theoretical basis can be provided for comprehensive utilization of this kind of ore.