【作者】 李慧；

【导师】 刘晓荣；

【作者基本信息】 东华大学 ， 环境工程， 2014， 硕士

【摘要】 随着高品位易处理的矿产资源不断消耗,人类面临着越来越严重的资源危机,合理充分的开采利用矿产资源刻不容缓。低品位难处理铜矿的利用越来越受到重视。生物冶金技术具有能处理低品位矿、难处理矿、生产成本低、投资少、流程简单和环保等特点,在国内外得到广泛应用。生物浸出-溶剂萃取-电积工艺为典型的生物提铜技术。该技术应用的关键限制环节是细菌浸出效率过低。实际上,萃余液中夹带和溶解的有机相会危害浸矿微生物的活性,进而影响整个生物浸出工艺的效率。本课题以此为切入点,深入研究铜萃取有机相及其有毒成分对A.ferrooxidans菌生长代谢和浸矿能力的影响,这对优化浸矿菌种、提高提铜生产效率具有重要的意义。随萃取工艺操作条件不同,A.ferrooxidans生长代谢和浸矿能力受到萃取有机相的抑制作用也不同。其中萃取剂浓度对细菌的影响最大,随萃取剂浓度升高、A.ferrooxidans代谢和浸矿能力逐渐减弱,当LIX984N浓度达到15%(v/v)时,细菌活性降低了75%；有机相对A. ferrooxidans的抑制作用随萃取循环次数增加逐渐减小,有机相在第一次投入使用之初抑菌作用最大；搅拌强度不同,夹带有机相的抑菌影响不同,其中300rpm搅拌强度对A.ferrooxidans菌的生长影响最大。流失于萃余液中的有机相至少包含有LIX984N的有效成分,这些有毒物质会使A.ferrooxidans菌体变粗变短,胞内出现空洞和细胞质聚集现象,细胞质壁变模糊,影响细菌的正常生长和代谢能量。有机相与强酸长期接触时会发生降解反应,故萃余液中夹带的有机相对A.ferrooxidans生长的影响随有机相与酸接触时间的不同而不同,随与酸接触时间延长有机相的抑菌作用表现为先降低再升高,有机相与酸接触时间为40-50h时,夹带有机相对细菌生长抑制影响最小。这是由于随有机相与强酸混合接触时间越长,其中抑菌物质降解消失越多,其抑菌作用逐渐减弱；但随着降解产生含羰基、羧基、羟基及酰胺等基团的极性两亲分子增多,亲脂成分会破坏细胞膜结构,将抑菌影响再次加强。萃余液中夹带和溶解的有机相在静置存放过程中会破乳、挥发、降解,故随存放时间增加,残留的有机相对细菌的抑制作用减小,但即使萃余液存放30天后,夹带的有机相对细菌生长和浸矿能力的影响仍不能消除,说明实际生产中,萃余液经集液池过渡周转时间也无法避免夹带和溶解有极相对浸矿微生物的抑制作用。壬基酚以改质剂的形式存在于萃取剂LIX984N中,研究表明,壬基酚明显降低A.ferrooxidans活性和浸矿能力,A.ferrooxidans培养过程中加入的壬基酚浓度越高,细菌受到的抑制作用越大。当壬基酚浓度为4.3×10-5mol/L时,细菌生长达到稳定期和Fe2+完全氧化的时间延迟了48h,细菌浸出黄铜矿27天的浸铜效率下降了近10%。壬基酚使细菌胞壁和质膜边界变得极其模糊,细胞质高度聚集于细胞中央,细胞结构的改变是壬基酚抑制A.ferrooxidans菌正常生长的原因之一。综上所示,铜溶剂萃取工艺控制的合理性与浸矿微生物的正常生长代谢及提高生物浸矿效率直接相关,意义重大。更多还原

【Abstract】 With the consumption of high-grade and manageable mineral resources, the resources crisis become more and more serious, reasonable full exploitation of mineral resources is significance. Hydrometallurgy operations have developed rapidly due to being environmentally friendly and low production costs, simple process handling etc.Biological leaching-solvent extraction-electrowinning operation is a typical technology of bioleaching copper. However the key limiting of the application of this technology is the leaching efficiency is too low. In fact, the circulation of the raffinate which loaded organic chemicals will definitely reach and pollute the bioleaching environment inhibiting the metabolism and bioleaching ability of the bacteria. In this paper, we study the effect of organic chemicals and the toxic component from copper solvent extraction on Acidithio-bacillus ferrooxidans in depth. It is great important to optimize bioleaching bacteria and improve bioleaching copper efficiency.With the increase of extractant concentration and extraction time, the metabolism of A.ferrooxidans and its bioleaching ability gradually decreased. The Fe2+-oxidation rate decreased by 75% in the presence of 15% extraction solvent. The strongest inhibition effect was shown after the first extraction cycle and 300rpm stirring extraction. Cells grown in culture solutions with solvent extraction chemicals exhibited differences in cell morphology and ultrastructure as compared to control cells. The cells were shortened and intracellular vacuoles increased.Being long-term touched with the acidic aqueous feed and strip reagent, Lix984N can be degraded gradually by such reaction mechanisms as Beckmann rearrange, hydrolyzing, oxidizing and sulfonating. With the increase of touched time between organic phase and acid, the bacteriostatic action of organic phase on A.ferrooxidans performance first reduce and then rise. The inhibition effect of organic phase touched acid 40-50 hours on A.ferrooxidans was minimum. This is due to that the antibiotic substances are degraded gradually after long term touch, so the inhibitions become reduce. Many kinds of amphiphiles containing such hydrophilic group as carbonyl, carboxyl, hydroxyl or acylamine are produced during the reagent degradations completely. The amphiphiles can destroy the cell membrane structure, so the inhibition of organic would strengthen.With the standing of raffinate, the entrained and dissolved organic phase will decrease because demulsification, volatilization and degradation. However the bacteriostasis of organic phase still can’t eliminate with the standing of raffinate.4-Nonylphenol which formed as modifier exists in LIX984N, studies have shown that with the increase of 4-Nonylphenol concentration, the metabolism of A.ferrooxidans and its bioleaching ability gradually decreased. The time of Fe2+oxidation completely delayed 48 hours in the presence of 4.3×10-5mol/L 4-NP, and the Cu bioleaching efficiency decrease by 10%. Cells grown in the culture solutions with 4-NP exhibited differences in cell ultrastructure as compared to control cells. The cell wall and plasma membrane become extremely blurred, The cell cytoplasm were highly clustered in the middle.The results suggest that the extraction process must consider its effect on bioleaching in practice. This may help to improve the whole bioleaching process.更多还原