【作者】 邓传宏；

【导师】 冯其明；

【作者基本信息】 中南大学 ， 矿物加工工程， 2010， 博士

【摘要】 我国广西、云南等地区赋存有丰富的堆积型铝土矿,目前单纯以洗矿作为脱硅手段,与之相关的选别技术研究甚少。本文以云南文山堆积型铝土矿为研究对象开展选矿脱硅的理论与工艺研究,以矿石的结构构造为基础,借助镜下观察、X射线衍射分析、EDS能谱分析,研究了碎解过程中铝硅矿物的走向及碎解产品各粒级中铝硅矿物的解离特性,并通过红外光谱分析、动电位分析、吸附量测试和粒度分析等手段,考查了堆积型铝土矿组成矿物的可浮性及其机理,进而开发了“堆积型铝土矿选择性解离-聚团浮选”工艺原型。主要研究内容及结果如下：1.堆积型铝土矿矿石性质堆积型铝土矿以沉积型铝土矿为矿源,经长期的岩溶作用和改造作用而形成。堆积型铝土矿中,铝、硅、铁为主要元素,相应主要赋存于一水硬铝石、高岭石和褐铁矿等矿物中,具有高铝、高硅、高铁、低硫的特点。铝硅矿物的嵌布特征存在差异,相对高岭石集合体,一水硬铝石集合体嵌布粒度较粗,硬度较大。结构致密的堆积型铝土矿矿石铝含量高,结构疏松的矿石铝含量低。堆积型铝土矿中,粗粒级铝硅比明显高于细粒级。2.堆积型铝土矿的选择性解离矿粉胶结型与粘土胶结型两种堆积型铝土矿矿石在磨矿过程中选择性解离现象明显,铝矿物在粗粒级中富集,解离程度的提高有利于提高粗粒级的铝硅比。对于铝硅比较低的原矿,破碎后直接分级所得粗粒产品难以满足拜耳法氧化铝生产要求。当磨矿细度为-0.074mm含量50-55%时,两种矿样+0.074mm粒级产品中铝硅比均在9以上,满足拜耳法对铝土矿精矿的要求,铝回收率为40-50%。磨矿细度的增加有利于提高粗粒级的铝硅比,但铝矿物在粗粒级中的回收率降低。结合镜下观察、X射线衍射分析、EDS能谱分析,磨矿后粗粒级单体解离度较高,一水硬铝石主要与铁矿物共生,细粒级虽然铝硅比较低,但仍有大量一水硬铝石富连生体存在,且铝矿物与硅矿物之间基本实现解离。3.堆积型铝土矿组成矿物的可浮性堆积型铝土矿中一水硬铝石和高岭石的可浮性与沉积型矿床中相近；pH为6-9是两种矿物可浮性较好的pH区间,在此pH范围内,一水硬铝石的可浮性好于高岭石；+0.038mm各粒级的一水硬铝石可浮性较好,-0.038mm粒级可浮性差；一定用量的铝离子和铁离子对一水硬铝石的浮选有活化作用。油酸钠可在一水硬铝石表面发生化学作用生成油酸铝,且油酸钠在一水硬铝石表面的吸附量是在高岭石表面的两倍以上,从而造成两种矿物的可浮性差异。适量的活化剂TK可使细粒级一水硬铝石产生选择性疏水聚团,提高矿物回收率。六偏磷酸钠的加入可增大一水硬铝石和高岭石的可浮性差异,且其在矿物表面的吸附可增大动电位负值,有利于矿泥的分散从而优化浮选过程。4.堆积型铝土矿的浮选脱硅文山铝土矿可以采用浮选方法实现选矿脱硅。由于堆积型铝土矿中存在大量矿泥,对矿浆的强化分散和对细粒铝矿物的选择性活化是堆积型铝土矿浮选脱硅的关键。采用高效活化剂TK进行堆积型铝土矿的活化浮选,可以在不降低精矿铝硅比的前提下大幅提高铝回收率。针对云南文山堆积型铝土矿,“选择性解离-聚团浮选”流程可取得明显优于洗矿工艺的选别效果。该工艺可由铝硅比5.97的原矿,得到铝硅比11.30的精矿,全流程Al2O3回收率达到81%。5.“洗矿-拜耳法”和“选矿-拜耳法”两种流程技术经济对比采用本研究开发的“选择性解离-聚团浮选”技术作为选矿工艺,可形成堆积型铝土矿生产氧化铝的“选矿-拜耳法”流程。对云南文山800kt/a氧化铝厂从采矿至氧化铝生产全过程的有限因素进行技术经济对比分析和社会效益对比分析表明,“选矿-拜耳法”流程与“洗矿-拜耳法”流程相比,每年可节约成本／增加利税总额1.15亿元,显著提高项目的盈利能力和抗风险能力；且由于大幅提高了资源利用效率,在现有探明储量基础上,可将文山州资源保障年限由50年延长至99年。因此,该技术为云南省铝工业的可持续发展和持续带动当地经济社会进步创造了良好的条件,具有良好的推广应用前景。更多还原

【Abstract】 China’s Guangxi and Yunnan, etc. are rich in accumulative bauxite ores. At present ore washing is the only way been used to desiliconize for the separation of accumulative bauxite ores due to less relevant separation technologies. Targeted at Wenshan accumulative bauxite in Yunnan Province, theory and technology of beneficiation-desiliconization are probed in this dissertation on the basis of the ore structure, with the help of microscopical observation, x-ray diffraction analysis, EDS spectrum analysis. The trend of aluminum minerals and silicate minerals during the process of crushing and dissociation characteristics of aluminum minerals and silicate minerals in various grain sizes of crushed products are also studied. Flotability and its mechanism of accumulative bauxite have been examined through infrared spectrum analysis, electrokinetic potential analysis, adsorptive capacity test and grain size analysis and so on. As a result, a prototype of "accumulative bauxite selective dissociation agglomeration floatation process" is developed. The main study contents and results are shown as follows:1. Properties of accumulative bauxite oresAccumulative bauxite ores have been formed through long-term karstification and transformation based on the mineral source of sedimentary bauxite. In the accumulative bauxite, the aluminum, silicon and iron are the principal elements which mainly exsit in such minerals as diasporite, kaolinite and limonite, etc. correspondingly with the features of higher-content aluminum, higher-content silicon, higher-content iron and lower-content sulfur. There exist differences in embedded characters among aluminum minerals and silicate minerals. Compared with kaolinite, diasporite aggregate is coarser in disseminated grain size and harder in hardness.The aluminum content is higher in the compact-structure accumulative bauxite ores while that is lower in loose-structure ones. In the accumulative bauxite, A/S value of coarser sizes is obviously higher than that in the fine size.2. Selective dissociation of accumulative bauxite oresDuring the grinding process, obvious selective dissociation phenomenon happens in powder cemented accumulative bauxite ores and clay cemented ones. Aluminum minerals are enriched in the coarse sizes. As a result, the improvement of dissociation facilitates higher A/S value in the coarse sizes.As for the crude ores with lower A/S value, it is difficult for the coarse-size products obtained from direct classification after crushing to meet the requirements of the Bayer process. When the grinding fineness is 50-55% content of-0.074mm size, the A/S value of +0.074mm size products from the powder cemented accumulative bauxite and clay cemented ones samples are all over 9, which satisfies the requirements of Bayer process on the bauxite concentrates. The recovery of aluminum is 40-50%. The increment of grinding fineness is in favor of improving the A/S value of the coarse-size products, but the recovery of aluminum reduces in the coarse-size products.Combined with microscopical observation, x-ray diffraction analysis and EDS spectrum analysis, it is found out that the liberation degree is higher in the coarse-size monomer after grinding, diasporite is mainly intergrowth with iron ore. Although the A/S is low in the fine-size ores, there still exists massive diasporite intergrowth, and aluminum minerals can be basically liberated from silicate minerals as well.3. Floatability of minerals in accumulative bauxiteThe floatability of diasporite and kaolinite in accumulative bauxite deposite is very close to that in the sedimentary one. It’s a good pulp condition for the floatability of two kinds of minerals when the pH is between 6 to 9, in which the floatability of diasporite is higher than that of kaolinite. The floatability of diasporite is good at the size of+0.038mm while bad at -0.038mm. A certain amount of aluminum ions and iron ions can be used to activate the diasporite behavour in floatation.Aluminum oleate can be formed when chemical action of sodium oleate takes place with the surface of diasporite. The adsorption of sodium oleate on the surface of diasporite is two times more than that on the kaolinite, resulting in the difference in the floatability of the two kinds of minerals-diasporite and kaolinite. Appropriate amount of activator TK can selectively make fine-size diasporite produce the hydrophobic aggregate and improve the mineral recovery. Addition of sodium hexametaphosphate can increase the difference in floatability between diasporite and kaolinite. The adorption of it can enlarge the negative value of Zeta potential of mineral particles, so it is beneficial to the dispersion of slime.4. Desiliconization of accumulative bauxite by floatation processDesiliconization of Wenshan bauxite can be realized by means of the floatation process. Considering of the plenty of mine slime in the accumulative bauxite, selective activation of minor diasporite particles and strengthened pulp dispersion are the key to the desiliconization of the by floatation process. Highly effective activator TK can be used to activate the floatation of the accumulative bauxite and can greatly improve the recovery of aluminum under the premise of not lowering the A/S of the concentrates.In view of Yunnan Wenshan accumulative bauxite, the flowsheet of "Selective Dissociation-Agglomeration Floatation Process" is obviously much more better than the process of ore washing in the separation effect. By the former, concentrates of A/S= 11.30 can be obtained with the recovery of Al2O3 up to 81% in the entire flow.5. Comparison of technical economy between two flowsheets of "Ore washing-Bayer process" and "Floatation-Bayer process"The flowsheet of "Floatation-Bayer Process" for producing aluminum oxide with accumulative bauxite can be formed by using "Selective Dissociation-Agglomeration Floatation Process" developed in this research as a mineral processing technology. For Yunnan Wenshan Aluminum Oxide Factory with the capacity of 800kt/year, comparison and analysis of technical economy and social efficiency in terms of limit factors in the whole process from mining to the production of aluminum oxide indicate that compared with the flowsheet of "Ore washing-Bayer Process", the flowsheet of "Floatation-Bayer Process" can save the cost /or increase the total amount of profits by RMB 115 million Yuan per year, which has obviously improved the capacity to earn profits and to resist risks. Furthermore, the guaranteed life of the mineral resources in Wenshan Prefecture can be prolonged from 50 years to 99 years based on the existing proven reserves because of the greatly increased utilization efficiency of the resources. Therefore, this "Floatation-Bayer Process" has a good prospect for popularization, which will be of great advantage to the sustainable development of aluminum industry in Yunnan Province and to the sustainable advancement of local economy and society.更多还原