非水溶性钾矿与真菌相互作用及钾浸出机理研究

In China, the soluble potassium resources are great shortage,so the production capacities of potassium salts ( KCl, K2SO4 et.al) do not satisfy the requirements of potassium fertilizers for the agricultural sustainable development. On the other hand, the nonsoluble potassium mineral resources, such as potassium feldspar, are very gigantic. It has a strategic significance for the agriculture sustainable development if potassium fertilizers will be producted from these nonsoluble potassium minerals. Based on the research of bioleaching by Penicillium , the objective of this project is to study the mechanism of microbial release of potassium from K-bearing minerals by fungi, in order to provide the fundamental theory for the development of the bioleaching technology of k-bearing minerals, including (1) several kinds of fungi will be collected from soil, plants and the weathering surface of k-bearing minerals in the potassium mine field, and new fungi with a high bioleaching efficiency will be sorted out and domesticated for the application of the microbal release of potassium from K-bearing minerals.(2) According to research on the interfacial reactions of mineral-fungus-soluntion system and the interaction of fungus-minernal system, the mechanism of microbial release of potassium from K-bearing minerals by fungi is explored in detail. (3) The experiemnts with the domesticated fungi bioleaching k-bearing minerals are carried out under the controllable operating conditions (pH value, temperature, pressure, metabolite concertration et. al), the concertrations of K, Si, Al elements in the bioleaching solution are analyzed by ICP instrument, and the bioleaching dynamics of K-bearing minerals with new fungi is modelled.(4) The new domensticated fungi are used to bioleach k-bearing minerals in a wringing microbial reactors with or without rotarying designed in our lab, and the operating conditions of the bioleaching process are optimized to produce the soluble potassium salt with a high efficiency. A new bioleaching technology of k-bearing minerals by fungi will be developed for the potential utilization of the nonsoluble potassium mineral resources in China.

我国可溶性钾资源极为匮乏,已探明的钾储量不能满足农业发展需求。但我国非水溶性钾资源如钾长石、黑云母、明矾石却非常丰富，如能利用此类钾矿资源制取钾肥，对保障我国农业可持续发展具有战略意义。本课题基于前期对青霉菌等真菌浸出实验的研究，旨在探讨真菌与非水溶性钾矿的相互作用及钾浸出机理，为探求含钾矿石生物浸出制备钾肥新途径奠定扎实基础。研究内容包括：（1）对含钾矿区采集驯化得到的不同真菌的解钾效率进行研究，优选高效菌种，丰富我国解钾微生物的种类；（2）基于矿物-真菌-流体三元复合体系的界面反应以及在微环境内真菌与矿物的相互作用研究，揭示真菌浸矿提钾机理；（3）对优选的菌群，调控操作参数和代谢产物，研究可控条件下真菌解钾过程，结合产物变化规律建立解钾动力学模型；（4）采用淋湿式（旋转）反应器强化真菌与含钾矿物的相互作用，优化生物浸出操作参数，为真菌浸取非水溶性钾矿制备钾肥提供经济可行新方法。

利用不溶性含钾岩石制备水溶性钾肥是大多数可溶性钾资源匮乏国家非常重视的问题。我国从50年代起，开始探索利用含钾岩石制取农用钾肥，但一直局限于试验研究阶段，未形成规模化生产。因为传统工艺多采用高温热解或水热活化技术，能耗大、 物耗大、产品含钾量低，而且引起环境污染等问题。本课题的研究目标聚焦解钾真菌菌种优化筛选、矿物-真菌复合体系的界面反应、微环境内真菌与矿物相互作用等基础性研究工作，力图发现、驯化并大规模培养高效解钾菌株，为实现可工业应用的含钾矿石生物浸出法制备钾肥新途径奠定扎实的理论基础。研究工作分为三个阶段进行，第一阶段，非水溶性钾矿晶相结构分析，同时到钾矿区采集真菌，进行分离与鉴定，获得高效释钾菌种；第二阶段，研究钾矿-真菌复合体系的界面反应、微环境内真菌与矿物相互作用，揭示真菌释钾机理；第三阶段，真菌钾矿浸取反应器的设计，研究真菌与钾矿的接触方式，提高释钾效率，并从微生物浸取液中获取硫酸钾产品，为工业化应用提供依据。本课题按计划完成，取得阶段性成果。采集8种优势释钾菌种，分别为黑曲霉、黑曲霉某属、黄曲霉、出芽短梗霉、烟曲霉、斜卧青霉、产紫青霉和篮状某属真菌。实验和分子模拟研究结果表明钾矿真菌释钾过程涉及如下几个关键步骤：真菌对钾矿物的粘附形成“真菌-钾矿复合体”；钾矿表面脆弱易风化部位优先溶蚀；微环境内胞外多糖络合有机酸使有机酸富集以及风化有益代谢产物的积累；被侵蚀的一些钾矿颗粒晶格在H+等的作用下逐步变形甚至崩解，矿质元素离子K，Al和Si等得以释放；释放的Al离子被有机酸络合，降低了其离子浓度，打破矿物溶解平衡使反应向正方向进行，释放更多的钾离子。本课题申请发明专利3项，发表科技论文9篇，参加国际学术会议3次，自制一台实验室用的真菌钾矿浸取反应器，构建了微生物分离鉴定实验平台，人才培养十二名，包括2名博士后、4名博士生和6名研究生，形成很好的研究非水溶性钾矿资源利用的团队。