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在模拟拜耳法氧化铝生产溶出条件下合成赤泥中主要含铁组分针铁矿,研究可溶性有机物包括甲酸钠、乙酸钠、草酸钠、水杨酸钠和邻苯二甲酸钠对针铁矿悬浮液沉降性能的影响,考察添加自制聚丙烯酰胺改性氧肟酸型絮凝剂(HCPAM)时针铁矿悬浮液的沉降性能,分别采用傅里叶红外光谱(FT-IR)和X射线光电子能谱(XPS)研究可溶性有机物在针铁矿表面上的吸附机理.结果表明:有机物使针铁矿悬浮液的沉降性能恶化,恶化程度由大到小顺序如下:草酸钠、水杨酸钠(邻苯二甲酸钠)、甲酸钠、乙酸钠.此外,絮凝剂HCPAM能够有效消除甲酸钠、乙酸钠和草酸钠对针铁矿悬浮液沉降的负作用,但只能部分消除水杨酸钠和邻苯二甲酸二钠对针铁矿悬浮液沉降的负作用.FT-IR和XPS光谱分析结果表明:上述有机物在针铁矿表面上的吸附机理为化学吸附.

Goethite, a typical iron-containing monomineral in red mud, was synthesized under the simulated Bayer digestion condition during the alumina production.The effects of dissolved organic compounds including sodium formate, sodium acetate, sodium oxalate, sodium salicylate and disodium phthalate on the settling performance of goethite slurries were studied. The settling performance of the slurries was also investigated with the addition of self-made hydroxamated polyacrylamide flocculant (HCPAM). The adsorption mechanism of dissolved organic compounds on the goethite surfaces was studied by FT-IR and XPS, respectively. The results show that the addition of organic compounds lowers the settling performance of the slurries and a deterioration in settling performance is observed in the order of sodium oxalate > sodium salicylate (~ disodium phthalate) > sodium formate > sodium acetate. Moreover, HCPAM can efficiently eliminate the negative effects of sodium formate, sodium acetate and sodium oxalate on the settling performance of the goethite slurries, but it can only partially improve the settling performance of the goethite slurries containing sodium salicylate or disodium phthalate. FT-IR and XPS results show that these organic compounds are chemically adsorbed on the goethite surface.