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摘要: 提出采用煤較低溫度下選擇性還原選銅尾礦中的鐵, 還原球團磁選回收鐵的技術, 并考察了還原溫度、還原劑用量、還原時間、活化劑用量對選銅尾礦選擇性還原回收鐵的影響, 得出最佳工藝條件: 還原溫度為1200℃, 還原劑用量為原料質量25%, 還原時間為2 h, 活化劑用量為原料質量5%;在最佳工藝條件下, 磁選精礦中鐵質量分數超過90%, 鐵回收率大于95%.借助X射線衍射儀、光學顯微鏡和掃描電子顯微鏡等檢測手段對原料、還原球團、磁選礦的礦相組成和結構進行分析, 揭示了鐵礦相還原及金屬相生成/融合演變規律: 升高溫度促進金屬相的還原、融合兼并和生長; 增加還原劑用量使金屬顆粒的融合兼并變得更加普遍; 延長還原時間促進金屬粒子的融合和鐵橄欖石相的還原; 活化劑促進金屬粒子的擴散和融合.金屬顆粒的兼并生長促使其粒度增大, 粗粒金屬顆粒在磁選工序裹夾帶入磁選精礦的渣相量相對較少, 磁選精礦鐵含量顯著提高.Abstract: Copper tailings are potential resources rich in iron minerals and their long-term stockpiling not only cause resource waste but also bring serious pressure to the ecological environment. Therefore, the resource utilization of copper tailings has attracted considerable attention and becomes the key to the sustainable development of the copper industry. In this study, the technology of the selective reduction of iron from copper tailings at low temperature using coal and recovery of iron from reduction pellets using magnetic separation was proposed. The effects of several factors, such as reduction temperature, reducing agent dosage, reduction time, and activator dosage, on the selective reduction and recovery of iron from copper tailings were investigated. The following optimum process conditions are determined through single-factor experiments: the reduction temperature is 1200℃, the reducing agent dosage is 25% of the mass of copper tailings, the reduction time is 2 h, and the activator dosage is 5% of the mass of copper tailings. Under the optimum process conditions, the iron mass fraction of the magnetic concentrate exceeds 90%, and the iron recovery rate is greater than 95%. The composition and structure of copper tailings, reduction pellets, and magnetic ores were determined via X-ray diffraction, optical microscopy, and scanning electron microscopy. Moreover, the mechanism of mineral phase reduction and metal phase generation/merging was revealed. The results show that increase in temperature is beneficial for the reduction, merging, and growth of the metal phase. Merging the metal particles becomes common by increasing the reducing agent dosage. Prolonging the reduction time promotes the merging of metal particles and reduction of fayalite. The activator promotes the diffusion and merging of metal particles. The merging and growth of metal particles promote the increase in particle size. The amount of slag wrapped by coarse metal particles in the magnetic concentrate is relatively small in the magnetic separation process, and the iron grade of the magnetic concentrate is significantly improved.
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Key words:
- copper tailings /
- reduction /
- mineral phase /
- metal particles /
- merging
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圖 2 原料光學顯微鏡照片. (a) 鐵酸鹽和鐵橄欖石共生; (b) 鐵酸鹽和玻璃相共生
Figure 2. Optical microscopy images of copper tailings: (a) intergrowth of ferrite and fayalite; (b) intergrowth of ferrite and glass phase
圖 3 不同還原溫度時還原球團的光學顯微鏡照片. (a) 800℃; (b) 900℃; (c) 1000℃; (d) 1200℃
Figure 3. Optical microscopy images of pellets reduced at different temperatures: (a) 800℃; (b) 900℃; (c) 1000℃; (d) 1200℃
圖 4 不同還原劑用量時還原球團的光學顯微鏡照片. (a) 15%; (b) 25%
Figure 4. Optical microscopy images of pellets reduced at different reducing agent dosages: (a) 15%; (b) 25%
圖 5 不同還原時間時還原球團的光學顯微鏡照片. (a) 0.5 h; (b) 1 h; (c) 1.5 h; (d) 2 h
Figure 5. Optical microscopy images of pellets reduced at different reduction times: (a) 0.5 h; (b) 1 h; (c) 1.5 h; (d) 2 h
圖 6 不同活化劑質量分數時還原球團的掃描電鏡照片. (a) 0; (b) 5%
Figure 6. SEM photographs of pellets reduced at different activator mass dosages: (a) 0; (b) 5%
圖 8 磁選礦光學顯微鏡照片. (a) 磁選精礦; (b) 磁選尾礦
Figure 8. Optical microscopy images of magnetic ores: (a) magnetic concentrate; (b) magnetic tailings
表 1 選銅尾礦化學組成半定量分析結果(質量分數)
Table 1. Chemical composition of copper tailings ?
% Fe Si Ca Cu Pb Zn As S 其他 41. 19 11. 88 12. 87 0. 38 0. 47 3. 79 0. 02 0. 13 29. 27 
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表 2 選銅尾礦篩析結果
Table 2. Screening and analysis results of copper tailings
粒度尺寸/mm 占比/% Fe質量分數/% 0. 074 ~ 0. 15 6. 40 36. 04 0. 05 ~ 0. 074 19. 10 39. 85 0 ~ 0. 05 74. 50 41. 55
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表 3 褐煤成分分析結果(質量分數)
Table 3. Composition analysis results of lignite ?
% 固定碳 灰分 揮發分 硫 磷 水分 52. 06 12. 20 28. 32 0. 26 0. 07 7. 09
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表 4 還原溫度對選銅尾礦還原回收鐵的影響
Table 4. Effect of reduction temperature on the grade and recovery of iron
還原溫度/℃ 精礦Fe質量分數/% Fe回收率/% 800 56. 38 29. 64 900 79. 93 73. 17 1000 77. 16 82. 76 1100 80. 91 93. 71 1200 92. 08 96. 14
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表 5 還原劑用量對選銅尾礦還原回收鐵的影響
Table 5. Effect of reducing agent dosage on the grade and recovery of iron
還原劑質量分數/% 精礦Fe質量分數/% Fe回收率/% 15 80.46 96. 85 25 92.08 96. 14
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表 6 還原時間對選銅尾礦還原回收鐵的影響
Table 6. Effect of reduction time on the grade and recovery of iron
還原時間/h 精礦Fe質量分數/% Fe回收率/% 0. 5 75.87 91. 97 1 79. 06 92. 12 1. 5 81. 19 95. 50 2 92. 08 96. 14
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表 7 活化劑用量對選銅尾礦還原回收鐵的影響
Table 7. Effect of activator dosage on the grade and recovery of iron
活化劑質量分數/% 精礦Fe質量分數/% Fe回收率/% 0 87.22 92.40 2.5 85.20 95. 95 5.0 92.08 96.14
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中文字幕在线观看表 8 綜合條件試驗結果
Table 8. Results of comprehensive conditional experiments
組別 精礦Fe質量分數/% Fe回收率/% 1 92. 08 96. 14 2 90. 43 95. 26 3 92. 76 96. 53 平均 91. 76 95. 98
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