【作者】 刘艳艳；

【导师】 陈咏梅；

【作者基本信息】 北京化工大学 ， 化学， 2014， 硕士

【摘要】 本论文围绕氧化铝工业关注的高硫高有机物铝土矿预处理和赤泥资源化利用两大问题开展研究。具体内容如下：(1)为了使我国贵州等地蕴藏的硫含量和有机物含量高的铝土矿(硫含量高于1.2%,有机碳含量大于0.2%)能够适合拜耳法氧化铝生产,提出氧化焙烧法预处理技术。本文系统考察了焙烧条件对铝土矿中硫化物、有机物的去除效果,评价了焙烧处理后铝土矿的碱溶出率及赤泥沉降性能。研究结果表明,选择较低的焙烧温度(450℃-620℃)可以在脱硫的同时避免一水硬铝石的大量脱水,因而铝溶出率基本未受影响；经过450℃以上的氧化焙烧,铝土矿中有机物含量降低至0.03%以下,赤泥沉降性能得到显著改善。综上,低温氧化焙烧法预处理技术可有效去除贵州铝土矿中的硫和有机物,对拜耳法氧化铝生产的碱溶出工序无负影响,对赤泥沉降工序有改善作用。(2)本文针对赤泥因铁含量过高限制了其作为耐火砖原料的大规模应用问题,提出将赤泥与黄铁矿(FeS2)在无氧条件下共混焙烧,使赤泥中的赤铁矿(Fe203)转化为磁铁矿(Fe304),再借助磁选分离技术实现赤泥中铁的去除和铁资源的回收。论文利用热分析技术详细讨论了该转化过程的反应机理,证实黄铁矿的无氧分解产物(FeS和S)均可实现赤铁矿至磁铁矿的转化,从而确定了共混焙烧的最低温度为600℃,黄铁矿最低添加比为1：16(黄铁矿与赤泥中Fe203的摩尔比)。论文还对国内不同生产工艺产生的赤泥样品进行了应用研究,铁回收率达到预期效果。更多还原

【Abstract】 Pretreatment technology of bauxite with high sulfur and organics and utilization of red mud were studied, both of which were widely noted in the alumina industry. The main point includes the following two parts:(1) To address the problem of the high sulfur and organics of bauxite in the bayer process of alumina production in Guizhou and other places in China, in which the sulfur content was more than1.2%and the organic content was more than0.2%, roasting pretreatment technology was put forward. The effect of roasting condition on sulfide and organics removal efficiency of the bauxite was researched scientifically. The alkali dissolution properties of the bauxite and sedimentation performance of red mud after roasting process were evaluated. The results show that because of diaspor dehydration being avoided at low roasting temperature, the aluminium dissolution rate was not affected when the bauxite roasted at450-620℃. The organic content of the bauxite roasted at the temperature higher than450℃was less than0.03%. At the same time, red mud sedimentation performance was improved due to the removal of organics. In short, roasting pretreatment of bauxite at low temperature can remove sulfer and organics efficiently, and improve red mud sedimentation performance without affecting the aluminium digestion.(2) Due to the high iron content of red mud limiting its large-scale application in producing refractory materials, we put forward that roast the red mud mixed with pyrite (FeS2) under anaerobic condition to transform hematite (Fe2O3) in red mud into magnetite (Fe3O4), and separate magnetite by magnetic separation technology to reduce iron content of red mud and realize the recycling of useful resource. The reaction mechanism of the transformation process is discussed in detail with thermal analysis technique, which confirmed that the decomposition products (FeS and S) of pyrite in anaerobic condition could transform hematite to magnetite. The lowest roasting temperature was600℃, and the minimum ratio of pyrite and hematite was1:16. Red mud samples from different production technology in domestic were tested in the application research and the effect of iron recovery could meet the requirement.更多还原