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| 黄沙坪碳酸盐型尾矿氧化剖面特征及酸化机制 |
| Characteristics of Oxidation Profile and Acidification Mechanism of a Carbonate Type Tailings, Huangshaping Pb-Zn mine (Hunan Province, China) |
| 投稿时间：2014-06-13 修订日期：2014-08-25 |
| DOI：10.14050/j.cnki.1672-9250.2015.02.006 |
| 中文关键词: 碳酸盐型尾矿;尾矿组构;酸中和能力;酸化作用 |
| 英文关键词: carbonate type tailings;tailings fabric;acid neutralizing capacity;acidification |
| 基金项目:国家自然科学基金面上项目(41272394,40972220)。 |
| 作者 | 单位 | | 雷良奇, 史振环, 莫佳, 陈斯耐, 林哲琼 | 桂林理工大学地球科学学院, 广西桂林 541004 |
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| 中文摘要: |
| 湖南黄沙坪铅锌矿尾矿富含碳酸盐及金属硫化物,属于碳酸盐型尾矿。通过对该尾矿铅垂剖面的结构构造,以及尾矿的矿物成分、化学成分、Paste pH值和Carb-ANC (酸中和能力)等分析,探讨碳酸盐型尾矿的酸化特征及其机制。研究表明:黄沙坪尾矿发育层状构造,即表面为胶结硬化层(hardpan),之下依次为弱胶结层、尾砂层及底层(接近尾矿潜水面)。尾矿的酸中和矿物主要为方解石;尾矿的产酸矿物以黄铁矿和磁黄铁矿为主,但黄铁矿的抗氧化能力和产酸能力均较强于磁黄铁矿。尾矿剖面自下而上(或由早至晚),氧化作用逐渐增强,磁黄铁矿先于黄铁矿氧化(蚀变)分解并逐渐消失,此时尾矿的酸中和能力仍较强,尾矿保持近中性环境;之后,黄铁矿开始氧化产酸并大量消耗方解石,尾矿开始酸化;至尾矿表层方解石消耗殆尽,而黄铁矿仍持续释酸,尾矿酸化加剧。表层强氧化环境使纤铁矿大量沉淀并胶结尾矿颗粒形成硬层。黄沙坪尾矿由于含有大量的抗氧化能力和产酸能力均较强的黄铁矿,其酸水(+重金属)释放的潜力较大并且持续的时间也较长。 |
| 英文摘要: |
The paper is focused on a carbonate type tailings rich in carbonate and sulfide, situated in Huangshaping Pb-Zn mine (Hunan Province, China). The characteristics and acidification mechanism of the tailings were studied by analyzing the structure, mineral and chemical composition, paste pH values and acid neutralizing capacity (Carb-ANC) of a vertical profile of the tailing heap. Results show that there is a layer structure on the profile, namely a strong cementation layer/hardpan on the top of the profile, followed by a weak cementation layer, a sand-like layer and the bottom layer (near the water table of the tailings reservoir) successively. In the tailings, mineral neutralizing acid is calcite mainly; minerals producing acids are pyrite and pyrrhotite mainly, but pyrite is stronger than pyrrhotite in both oxidation resistance and acid generation. From the bottom to the top of the profile (or from early to late stage), associated with the gradual increasing oxidation degree, pyrrhotite oxidized (altered) prior to pyrite and gradually disappears. At this early stage, the acid neutralizing capacity of tailings is stronger, and the tailings remain near neutral circumstance. Since then, pyrite started to oxidize and produce acid, and calcite in the tailings was consumed in large quantities, resulting in decrease of the acid neutralizing capacity and the tailings generating acid. Up to the top of the profile, calcite in the tailings is consumed almost entirely, while pyrites alteration is further enhanced, resulting in acidification intensifying. Under stronger oxidizing circumstance at the top tailings, lepidocrocite (γ-FeOOH) precipitates largely and cement/enwrap the tailings particles (including calcite residual particles), so the hardpan forms.
Huangshaping carbonate type tailings, due to containing a lot of pyrite with strong antioxidant capacity and acid producing ability, have a great potential to release acid and heavy water and the release may last for a long time. |
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