Processing of industrial minerals through bio-leaching of iron

铁是工业矿物产品中常见的污染物，这些产品因其白度而受到重视，包括高岭土、硅砂、石灰石和白垩。目前的高岭土和硅砂的精炼技术依赖于酸洗或化学处理来去除铁，产生废物并消耗大量能源。此外，这些技术都不适用于碳酸盐岩。通过其他方法从工业矿物中去除铁杂质的能力可以降低成本，允许开采低品位的材料，提高矿物加工的效率。拟议的研究旨在开发和测试基于铁的微生物还原到易于通过洗涤去除的形式的实用精炼方法。建议项目将于两年内完成，包括小规模的微观实验，直至更大规模的生物反应器研究，以扩大从微观实验中确定的最佳条件。首先要确定在待调查的矿物中自然存在的微生物，并在实验室中分离和培养矿物中发现的任何铁还原细菌。将进行微观实验，以测试本地和市售的铁还原细菌在各种外部控制条件下（包括营养供应、pH值和生长介质的化学性质）从高岭土、硅砂和石灰石中浸出铁的速度和程度的效率。然后将为每一种待调查的矿物设计和建造生物反应器，并将进行若干生物反应器实验，以评价新开发的生物浸出技术的质量、商业和环境效益。特别是，将实现的结果与工业合作伙伴商定的成功标准进行比较，并评估实现某些产品特性的时间成本和收益。新的精炼技术预计每年可节省7-1亿美元的资金，主要是通过降低能源成本。该项目还有望减少目前高岭土加工活动产生的废物。

Iron is a common contaminant of industrial mineral products that are valued for their whiteness, including kaolin, silica sand, limestone and chalk. Current refinement technologies for kaolin and silica sands rely on acid washing or chemical treatment to remove iron, generating waste and consuming large amounts of energy. Also, none of these technologies can be applied to carbonates. The ability to remove iron impurities from industrial minerals by other means may reduce costs, allow lower grade material to be exploited and improve the efficiency of mineral processing. The proposed research aims to develop and test practical refining methods based on the microbial reduction of iron to a form readily removable by washing. The proposed project will be completed in 2 years and will involve small scale microcosm experiments through to larger scale bioreactor studies enabling the optimum conditions identified from the microcosm experiments to be scaled up. Microorganisms naturally present in the minerals to be investigated will first be identified and any iron-reducing bacteria found in the minerals will be isolated and cultured in the laboratory. Microcosm experiments will conducted to test the efficiency of indigenous and commercially available iron-reducing bacteria on the rate and extent of iron leaching from kaolin, silica sands and limestones under various externally-controlled conditions, including nutrient supply, pH and chemistry of the growth medium. Bioreactors will then be designed and built for each of the minerals to be investigated and several bioreactor experiments will be conducted to evaluate the quality, commercial and environmental benefits of the newly developed bioleaching technologies. In particular, the achieved outcomes will be compared against success criteria agreed with the industrial partners and the time cost and benefit of achieving certain product characteristics will be assessed. The new refinement technology is expected to lead to financial savings in the order of 7-100M per year, mostly through reduced energy costs. The project is also expected to lead to a reduction in the waste generated by current kaolin processing activities.