【作者】 高淑玲；

【导师】 魏德洲； 李晓安；

【作者基本信息】 东北大学 ， 矿物粉体材料与工程， 2009， 博士

【摘要】 作为生产氧化铝的主要原料,铝土矿的矿石特征及其加工技术直接影响着该资源的综合利用率。在中国,铝土矿以一水硬铝石型为主,其主要特征是高铝、高硅、低铝硅比、矿物组成复杂且铝、硅矿物间的嵌布关系密切。这使得氧化铝的生产成本高、产品质量差。对我国储量巨大的一水硬铝石型低品位铝土矿进行经济有效的分选脱硅,从而为氧化铝生产提供优质原料,是一个摆在我们面前的重大研究课题。本文以铝硅比为4.39的一水硬铝石型铝土矿为处理对象,系统地研究了不同因素对其旋流分选和旋流-反浮选效果的影响,并对旋流器内部流场进行了多个参数条件下的数值模拟,依此分析了结构参数和操作参数对铝土矿旋流分选的影响机理。主要研究工作包括以下几个方面：(1)系统考察了在不同锥角条件下改变底流口直径和给矿压强对铝土矿旋流分离效果的影响。结果表明,增大底流口直径使液相在溢流的分配比例减小,溢流产物的粒度变细,铝硅比降低,底流产物的铝硅比也不断下降,而其中Al2O3的回收率提高；锥角和底流口直径对分级效果具有一定的交互作用；在不同锥角条件下增大给矿压强,液相在溢流的分配比例基本保持恒定,但分级效率呈现不同程度的下降,溢流的粒度变细,分级作用有所减弱；给矿压强和锥角对铝土矿的旋流分选存在交互作用,在特定的锥角条件下增大给矿压强可以强化分选作用；增大锥角还可使矿浆进入溢流的量增加,溢流的固体产率和分级效率相应提高。当锥角为11°,底流口直径为6mm,给矿压强为0.4MPa时,获得了较好的分选指标：底流产物的A/S为7.33,其中Al2O3的回收率为70.52%；溢流产物的A/S为2.30,其中SiO2的回收率为57.14%。(2)考察了给矿浓度、入料粒度、分散剂用量对铝土矿旋流分离效果的影响。结果表明,给矿浓度的增大不利于旋流分选过程的进行,其对分选指标的负面影响在10%～20%范围内尤为明显；铝土矿以较粗的入料粒度,即-0.074mm粒级占60%左右时更有利于改善旋流分选指标；添加适量的分散剂可以明显改善旋流器内部的分选环境,提高铝硅矿物的分选效果。(3)脱泥-旋流分选试验结果表明,在小锥角、大底流口直径的条件下,对铝土矿进行脱泥的适宜给矿压强为0.3～0.4MPa；采用7°锥角的旋流器脱泥、11°锥角的旋流器分选,所得精矿的铝硅比达到7.54,精矿中Al2O3的回收率达到71.11%,分选指标与不脱泥直接进行旋流分选相比有所改善。(4)系统地考察了充气量、浮选药剂、入料粒度等因素对铝土矿旋流-反浮选分离效果的影响。结果表明,充气量对流场和矿物颗粒间的分离效果具有一定程度的影响,充气量较低(0～0.8m3/h)时,增大充气量会使轴向零速包络面向轴心轻微收缩,削弱了分级作用,但却在一定程度上强化了分选作用,分选指标与不充气相比得到了一定程度的改善；经添加一定量的改性淀粉和十二胺醋酸盐,分选指标优于同样结构参数与操作条件下的旋流分选指标；入料粒度对旋流—反浮选的分选指标具有显著的影响,而且仍以-0.074mm占60%为宜。(5)对旋流器内部流场进行了多个参数条件下的数值模拟,并依此分析了不同因素对铝土矿旋流分选的影响机理。结果表明,结构参数主要通过改变流场的轴向零速包络面致使溢流和底流的体积产率及矿物颗粒的分离行为发生变化,而对有效分离区域内的速度场分布几乎没有影响,这与根据旋流分选试验结果的推断相一致；由于锥角不同时,流场的压强分布特征随底流口直径的增大而产生细微的变化,导致颗粒在径向的受力、运动行为及其分布特征发生改变,所以出现了锥角与底流口直径对铝土矿分级效果的交互影响；当结构参数一定时,增大给矿压强对轴向零速包络面没有明显影响,但可以使有效分离区域内的轴向速度和切向速度增大,从而可以改变颗粒在旋流器径向上的受力及其在旋流场内的分布,最终改善了矿物颗粒的分离效果。更多还原

【Abstract】 Bauxite is the main raw material to produce alumina, whose mineralogical characteristic and processing technology affect its general utilization directly. Diasporic bauxite is the major kind in China, charactered by high-aluminum, high-silicon, low ratio of Al2O3 to SiO2, complicated mineral compositions and nearly disseminated associations of aluminous minerals and silicate minerals. These lead to a high production cost and a poor product quality in alumina industry. It’s an important research project to carry out economical and effective beneficiation to desilicate from diasporic low-grade bauxite with great reserves in China and then provide excellent material for alumina production.With diasporic bauxite of A/S 4.39 as samples, the influence of different factors on its cyclonic separation and cyclonic-reverse flotation was studied systemically, and numerical simulation of fluent field in cyclone was carried out in the condition of many factors, according to which the mechanism of structural and operating parameters influence the cyclonic separation of bauxite was analysed. The main work in the present paper includes the following:(1) The influence of apex diameter and feed pressure under different cone angles on the cyclonic separation effect of bauxite was investigated systemically. The results showed the increase of apex diameter can reduce the flow ratio of overflow, particles in overflow becomes finer and the A/S of overflow decreases, and the A/S of underflow also decreases, the recovery of Al2O3 in underflow increases; Cone angle and apex diameter have interaction in classification efficiency; When the feed pressure increases under different cone angles, the flow ratio of overflow keeps invariable basically, but the classification efficiency decrease in different degree, particles in overflow becomes finer, the function of classification was weakened; Feed pressure and cone angle have interaction in cyclonic separation of bauxite, in the condition of special cone angle, the function of separation is strengthened; The increase of cone angle can also increase the flow ratio of overflow, the solid ratio of overflow can be increased accordingly. When cone angle is 11°, apex diameter is 6mm, and feed pressure is 0.4MPa, better separation indexes are obtained:The A/S of underflow is 7.33, the recovery of Al2O3 in underflow is 70.52%; the A/S of overflow is 2.30 and the recovery of SiO2 in overflow is 57.14%.(2) The influence of feed concentration, feed particle size and dispersant dosage on the cyclonic separation effect of bauxite was investigated. The results showed that the increase of feed concentration is disadvantageous to the process of cyclonic separation, it makes the separation indexes worsen obviously especially in the range of 10%～20%; Bigger particle size of bauxite is more advantageous to improve its cyclonic separation indexes, namely-0.074mm 60%; The separation environment and selectivity can be improved obviously by adding dispersant with suitable quantity.(3) The tests of desliming-cyclonic separation showed that in the condition of little cone angle and big apex diameter, feed pressure of 0.3～0.4MPa is suitable to deslime from bauxite; By desliming in hydrocyclone of 7°and separation in hydrocyclone of 11°, the A/S of concentrate is 7.54, the recovery of Al2O3 in it is 71.11%, the indexes are improved than those by cyclonic separation without desliming.(4) The influence of aeration quantity, flotation reagents and feed particle size on the effect of cyclonic-reverse flotation of bauxite was investigated systemically. The results showed that the aeration quantity have some influence on the fluent field and separation effect of mineral particles, when the aeration quantity increases in the range of 0～0.8m3/h, the envelope of zero vertical velocity shrinks to the axis slightly, the classification function is weakened, but the separation function is strengthened, the separation indexes are improved than no aeration; By adding some modified starch and laurylamine acetate, the separation indexes are better than those obtained by cyclonic separation in the same condition of structural and operating parameters; Feed particle size has remarkable influence on the separation indexes of cyclonic-reverse flotation,-0.074mm 60% is also suitable.(5) Numerical simulation of fluent field in cyclone was carried out in the condition of many factors, according to which the mechanism of different factors influence the cyclonic separation of bauxite was analysed. The results showed that structural parameters make the envelope of zero vertical velocity changed, make flow ratio of overflow to underflow accordingly, and the separation behavior of mineral particles changed. However, they have basically no influence on the velocity distribution in the effective separation district, which accords with the inference according to the test results of cyclonic separation; Because the distribution of pressure in different cone angles change finely with apex diameter, which makes the force, motion behavior and distribution characteristics of particles changed in radial, and so the interaction of cone angle and apex diameter on the classification effect of bauxite appears; When the structural parameters is certain, the increase of feed pressure has no obvious influence on the envelope of zero vertical velocity, but can increase the vertical and tangential velocity in the effective separation district, and can change the force and distribution characteristics of particles in the radial of hydrocyclone, finally makes the separation effect of mineral particles improved.更多还原