鉱物処理

[1308-17-04] Development of Impurities Removal Process for Low-Grade Iron Ore

○Moses Charles Siame¹, Kazutoshi Haga¹, Astushi Shibayama¹ (1. Akita University)

司会：伊藤 真由美（北海道大学）

Keywords:Sanje Iron Ore, Magnetic Separation, Reverse floatation, Silica, Iron Recovery

This study investigates the removal of silica and alumina as impurities from Sanje Iron ore from Zambia, which contains 48.90% mass of hematite (Fe₂O₃) with 34.18% mass iron grade, 31.10% mass silica (SiO₂) and 7.65% mass alumina (Al₂O₃). Wet High-Intensity Magnetic Separation (WHIMS) method was used as the as the first stage impurity removal process using Series L Model 4 laboratory magnetic Separator (L-4 Machine) and the effect of magnetic separation parameters such as magnetic flux density, particle size density and pulp density of the feed were studied. The ore sample having 80% of its particles less than 25 µm and pulp density of 2.5% was concentrated using pulp flow of 7 L/min. The results showed that 93.08% of iron with a grade of 53.22 mass% was recovered at optimum magnetic density inside the pipe matrix of 10 T. The concentrate produced from magnetic separation contained 18.08 mass% of silica and 4.19 mass% alumina and was therefore required treated in the second stage process. Reverse flotation process was therefore investigated and various parameters such as pH, collector dosage, Iron depressant dosage and quartz activator dosage were investigated. The results from a combination of magnetic separation followed by reverse flotation showed that 81.94% of the iron oxide with 67.27 mass% Iron grade was recovered at the concentrate’s pH of 6.8 using 200 g/T of 0.1% calcium oxide (CaO) as silica activator and 1 kg/T of 0.1% alkaline starch as Iron depressant. Sodium Oleate (C₁₈H₃₃NaO₂) and Dodecylamine acetate (C₁₄H₃₁NO₂), each with discrete dosage were used as anionic and cationic collectors respectively. At optimum Sodium Oleate dosage of 250g/T and 250g/T of dodecylamine acetate, alumina was reduced to 1.04 mass% and Silica to 2.04 mass% using 2mls of Methyl Isobutyl Carbinol (C₆H₁₄O) frother. Only 2.02 mass% of silica (SiO₂) and 1.04 mass% of alumina (Al₂O₃) remained in the concentrate with phosphorous observed to be reduced from 0.05 mass% to 0.01 mass%.