Research On Recovery Of Iron Minerals From Tailings Of Meishan Iron Ore

The processes of Meishan plant whose capacity is 4 million tons per year mainly recover strong magnetic iron minerals,so weak magnetic minerals containing iron carbonate and iron oxide are lost in the tailings,which results in the low iron recovery and magnitude waste of resources. To recover the iron minerals in Meishan tailing,tests were carried out based on the process mineralogy of tailing to obtain an appropriate tailing reconcentrate process.Chemical component analysis and X-ray diffraction analysis on tailings of Meishan showed that iron grade of tailing was 14.34%. The iron minerals in the tailings were mainly siderite and hematite(or limonite), while the gangue mineral was mainly quartz. There is little impurities S or P in the tailings. Size analysis suggested that the coarse grain dominated in tailings, and metal distribution was high, so prescreening was not necessary to set.Aiming to iron minerals preconcentration from the tailings, the high intensity magnetic separation, gravity separation and magnetic separation-gravity separation tests were conducted. By comparing the test results, high intensity magnetic separation was selected as enrichment process iron grade of 24.33% and recovery of 84.16% were obtained. Subsequently, the grinding fineness test and secondary-stage high intensity magnetic separation (HIMS) condition test were carried out, determining that suitable grinding fineness was -0.074mm 90% and the background magnetic field strength was 398.1kA/m. Of which, the grade of secondary-stage high intensity magnetic concentrate was 30.71%, and total recovery was 72.42%.For the secondary-stage HIMS concentrate, step- flotation, dispersion flotation and step-dispersion flotation were tested. And dispersant was respectively sodium silicate, sodium hexametaphosphate and sodium carboxyl methyl cellulose(CMC). Owing to the high content of siderite in secondary-stage HIMS concentrate, direct flotation results obtained from the test were not ideal.The secondary-stage HIMS concentrate was then separated by shaking table, the grade was 46.18% and total recovery was 39.64%. Through the iron chemical phase analysis results, the content of siderite in shaking table concentrate was significantly reduced, which was benefical to the subsequent separation. Shaking table concentrate was separated by step-flotation, reverse flotation and reverse flotation-dispersion flotation, determining to employ the "one roughing, one cleaning" two step "reverse flotation-dispersion flotation" flow ultimately. In roughing stage, pH was 6.5, starch and sodium oleate dosage was 1000g/t and 800g/t respectively. While in cleaning stage, pH remained unchanged, starch and sodium oleate dosage were both reduced to 600g/t. According to the laboratory closed-circuit test, final iron concentrate grade was 52.13%, and the recovery was 34.67%.Finally, flotation concentrate and tailings were observed by SEM in view of the sodium oleate system, and adopted infrared spectrum scanning to analyze the surface of siderite, hematite and quartz before and after effected by reagents. Adsorption behavior and manner of reagents on different mineral surface was made clear, and the influence factors of the grade of flotation concentrate were analyzed in mechanism.The research results of the paper have certain guiding significance to the recovery of iron minerals from the tailings of Meishan.