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低铁中等品位是我国铝矿资源的特点。本文从 Al_2O_3生产的化工原理—除铁、脱硅入手,提出生产 Al_2O_3的合理方案,推荐压浸予脱硅精矿过量石灰拜尔法浸出。试验表明,约含4%Fe_2O_3,A/S=4—5的山西铝士矿,经1000±100℃焙烧以含 Na_2CO_3的 NaOH溶液在3Kg/cm~2压力下浸出15分钟,铝精矿 A/S 可达12—13。精矿用拜尔法浸出,发现在不平衡溶出即赤泥 A/S=1.3—1.5条件下,石灰添加量由常规的4%过量至15—20%,用210—300g/L Na_2O_k 的循环碱液,在60—32Kg/cm~2压力下压煮浸出,Al_2O_3浸出率87.5%,碱耗16—18公斤 Na_2 CO_3/吨Al_2O_3。
Middle-grade low-iron is the characteristics of China’s aluminum resources. In this paper, from the chemical principle of Al_2O_3 production - iron removal and desiliconization, a reasonable scheme for producing Al_2O_3 is proposed. It is recommended to leach excess lime by Bayer process with pressure leaching. Experiments show that the aluminum ore concentrate containing 4% Fe_2O_3 and A / S = 4-5 is leached for 15 minutes under the pressure of 3Kg / cm ~ 2 by NaOH solution containing Na_2CO_3 calcined at 1000 ± 100 ℃. / S up to 12-13. Leaching by the Bayer process, the concentrate was found to have an excess of 4% excess of the amount of lime added to 15-20% with an unbalanced dissolution, ie, red mud A / S = 1.3-1.5, with a circulation of 210-300 g / L Na 2 O_k Lye, pressure cook under 60-32Kg / cm2 pressure leaching, Al_2O_3 leaching rate 87.5%, alkali consumption 16-18 kg Na_2CO_3 / ton Al_2O_3.