Abstract:

Iron oxides in pyrite cinder are difficult to be recycled efficiently for its poor activity, and there are some disadvantages in the presently reported intensified acid leaching methods, such as high dosage of auxiliary agent, production of harmful H₂S and low leaching rate of iron. On the basis of the as-proposed selection principles of auxiliary agents, oxalic acid was selected as the more suitable auxiliary agent in the leaching process to overcome the above disadvantages and its action mechanism on the acid leaching was preliminarily discussed. Taking the leaching rate of iron in pyrite cinder as the main index, the leaching conditions were investigated through single-factor experiments and orthogonal experiments and the leaching condition was optimized as follows: reaction time 7.5h, addition of oxalic acid 20%, the mass fraction of sulfuric acid 50%, reaction temperature 98℃, under which the leaching rate of iron could reach 95.7%. The XRD patterns and EDS spectrum of the sample showed that when adding oxalic acid, the content of iron in the leaching residue decreased significantly compared to that without addition of oxalic acid, which suggesting that the addition of oxalic acid obviously promoted the extraction of iron from pyrite cinder.

Key words: pyrite cinder, acid leaching, oxalic acid, iron oxide

摘要：

硫酸烧渣中铁氧化物活性较差，难以高效回收利用，且目前所报道的助剂强化酸浸法存在着诸如助剂用量大、易产生H₂S等有害气体、铁的浸取率仍有待于进一步提高等不足。为了解决上述问题，本文依据所提出的助剂选择原则，筛选并确定草酸为较适宜的酸浸助剂，并对其作为酸浸助剂的作用机理进行了初步探讨。通过单因素条件实验和正交实验，考察并确定了较适宜的酸浸工艺条件：反应时间7.5h，草酸助剂加入量20%，硫酸浸液质量分数50%，反应温度98℃。此条件下，硫酸烧渣中铁的浸取率可达95.7%。样品的XRD、EDS分析结果显示：相比于未添加草酸助剂的酸浸残渣，添加草酸助剂后的酸浸残渣中铁含量明显降低，说明草酸助剂的添加明显促进了硫酸烧渣中铁的浸出。

关键词: 硫酸烧渣, 酸浸, 草酸, 铁氧化物