腐殖酸改良脱碱赤泥的环境风险评估

处理过酸性矿涌水的赤泥如果未经处理大量堆存会对环境造成严重的危害，对其进行土壤化改良是实现其大宗消纳的一种可行性方法。腐殖酸呈酸性，是自然界中广泛存在的大分子有机物质，其对土壤的修复和改良作用十分明显。为研究腐殖酸改良脱碱赤泥的环境风险，通过腐殖酸联合脱碱赤泥试验，对脱碱赤泥及其浸出液的理化性质进行了分析，并对添加腐殖酸后脱碱赤泥的浸出风险进行了评估。结果表明：添加质量百分比（腐殖酸:赤泥）为10%的腐殖酸改良脱碱赤泥效果最好。此时，脱碱赤泥pH由9.1降至7.8左右；脱碱赤泥在pH较高时电动电位（Zeta电位）绝对值由20增大到28；腐殖酸中的富里酸类物质会逐渐转变成更加稳定的胡敏酸类物质；脱碱赤泥浸出液金属离子浓度降低，对赤泥金属离子固定有一定积极作用。综上，腐殖酸改良脱碱赤泥可以降低脱碱赤泥的环境风险。

Environmental risk assessment of humic acid modified dealkalized red mud

Untreated accumulation of red mud that has been treated with acid mine drainage can cause serious harm to the environment. Soil improvement is a feasible method to consume it on a large scale. Humic acid is acidic and is a large molecular organic substance widely present in nature, and its effect on soil restoration and improvement is significant. To study the environmental risk of humic acid modified dealkalized red mud, humic acid combined with dealkalized red mud experiment was carried out. The physicochemical properties of the dealkalized red mud and its leachate were analyzed, and the leaching risk of dealkalized red mud after adding humic acid was evaluated. The results showed that the best effect of improving dealkalized red mud by humic acid with a mass percentage (humic acid/red mud) of 10% was achieved. Adding 10% mass percentage of humic acid could reduce pH of dealkalized red mud from 9.1 to around 7.8. It could increase the absolute value of the electric potential (Zeta potential) of dealkalized red mud from 20 to 28 at higher pH. The fulvic acid substances in humic acid would gradually transform into more stable humic acid substances. Humic acid could reduce the concentration of metal ions in the leachate of dealkalized red mud and had a positive effect on fixing metal ions in red mud. In summary, humic acid could improve dealkalized red mud and reduce its environmental risk.