Processing of industrial minerals through bio-leaching of iron

铁是工业矿物产品的常见污染物，这些产品因其白度而有价值，包括高岭土，硅砂，石灰石和白垩。目前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，这些技术都不能应用于碳酸盐。通过其他手段从工业矿物中去除铁杂质的能力可以降低成本，允许开采较低等级的材料，并提高矿物加工的效率。拟议的研究旨在开发和测试实用的精炼方法，该方法基于微生物将铁还原为易于通过洗涤去除的形式。拟议的项目将在2年内完成，将涉及小规模的微观实验到更大规模的生物反应器研究，使微观实验确定的最佳条件能够扩大规模。首先将鉴定待调查矿物中天然存在的微生物，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，以测试本地和商业上可获得的铁还原细菌在各种外部控制条件下（包括营养供应、pH值和生长培养基的化学性质）对高岭土、硅砂和石灰石中铁浸出速率和程度的效率。然后，将为每种待研究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沥滤技术的质量、商业和环境效益。特别是，将把取得的成果与同工业伙伴商定的成功标准进行比较，并将评估实现某些产品特性的时间成本和效益。新的精炼技术预计每年将节省7- 1亿美元的资金，主要是通过降低能源成本。预计该项目还将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.