Red Mud Minimization by Iron Removal

[9714594]施莱辛格本研究的目的是证明使用部分还原作为从使用拜耳法提纯铝时产生的“赤泥”中去除铁的一种手段。赤泥含有高氧化铁，因此得名，同时还含有大量氧化铝、苏打、二氧化硅、石灰和二氧化钛，可能被证明是这些材料的宝贵来源。目前，赤泥是在海上或沿海岸或河岸的浅泻湖中处理的。由于赤泥的危险性较低，因此很少有研究关注减少处置材料的体积或其成分的回收。赤泥的一些特性使得开发经济上可行的处理方法变得困难，例如，其含水量，极细的粒度和其大部分成分的难熔性。最具挑战性的方面之一是找到一种方法来分离它所含的铁（以赤铁矿的形式）。已经尝试了几种技术，但都没有成功，因为它们的能量要求高，因为它们产生的渣难以进一步处理。本研究旨在将赤铁矿还原为磁铁矿或浮氏体，这些磁铁矿具有铁磁性，可通过低梯度磁选工艺回收。这将需要更低的炉温，降低能源成本，并最大限度地减少泥浆中其他成分之间的相互作用。研究计划将侧重于改变泥浆类型、还原温度、还原剂的选择和用量的实验规模的还原实验；定量过程矿物学技术将用于评估已达到的还原程度，并生成美国赤泥的特征概况。第二个重点涉及演示使用低梯度磁分离从部分还原的材料中回收铁。磁选技术的最新进展显示了从其他细粒度工艺废物中回收铁的希望，将其整合到赤泥处理过程中将有助于创造一种可行的替代现有处理和回收技术。* * *

9714594 Schlesinger The objective of this research is to demonstrate the use of partial reduction as a means of removing the iron from "red mud", produced in the purification of aluminum using the Bayer process. Red mud contains high ferric-oxide, resulting in its name, as well as significant percentages of alumina, soda, silica, lime and titania, and might prove a valuable source of these materials. Currently red mud is disposed of at sea or in shallow lagoons along ocean shores or river banks. Because of the less-hazardous nature of red mud, little research attention has been given to reducing the volume of disposed material or the recovery of its constituents. Several characteristics of red mud make the development of an economically viable treatment process difficult, e.g. the moisture content, the extremely fine particle size and the refractory nature of most of its constituents. One of the most challenging aspects lies in finding a way of separating the iron it contains (in the form of hematite). Several techniques have been attempted, but they have been unsuccessful because of their high energy requirements and because they produce a slag which is difficult to process further. This research is aimed at reducing the hematite to magetite or wustite, which are ferromagnetic and can be recovered by low-gradient magnetic separation processes. This would require lower furnace temperatures, reducing energy costs and minimizing interaction among the other constituents in the mud. The research program will focus on bench-scale reduction experiments varying the type of mud, reduction temperature and the choice and amount of reducing agent; quantitative process mineralogy techniques will be used to assess the degree of reduction achieved and to generate a characterization profile of U.S. red muds. A second focus involves demonstrating the use of low-gradient magnetic separation in recovering iron from the partially reduced materials. Recent advances in magnetic separation have shown promise in iron recovery from other fine-grained process wastes and their integration into a red mud treatment process will help create a viable alternative to present disposal and recovery techniques. ***