【作者】 张国范；

【导师】 冯其明；

【作者基本信息】 中南大学 ， 矿物加工工程， 2001， 博士

【摘要】 论文以铝土矿组成矿物的晶体结构差异为基础，通过量子化学计算、溶液化学计算、光电子能谱、X射线衍射、吸附量测试以及浮选试验等各种方法，系统地研究了高岭石和一水硬铝石的晶体结构、表面性质和浮选行为三者之间的关系，研究了正、反浮选体系中铝、硅矿物的浮选行为，以及阴离子捕收剂（以油酸钠为代表）和阳离子捕收剂（以十二胺为代表）在一水硬铝石和高岭石矿物表面的吸附机理。研究内容与结果如下： 1 一水硬铝石和高岭石晶体结构和表面性质主要存在以下差异： 一水硬铝石晶体结构中铝氧八面体形成双链，双链间以角顶相连，链内八面体共棱连结。高岭石为硅氧四面体的六方网层与“氢氧铝石”八面体按1：1结合而成的层状硅酸盐矿物； 矿物表面铝离子为中间酸，硅离子为软酸： 一水硬铝石表面的铝离子丰度为高岭石表面铝离子丰度的1．7倍； 一水硬铝石表面荷电机理为表面氢离子的吸附和电离，其表面的动电位随溶液pH值的变化而改变。高岭石的荷电机理有两种：端面为氢离子的吸附和电离，其端面的动电位随溶液pH值的变化而改变；层面为金属离子晶格取代造成，荷负电，不随溶液pH值变化而改变。动电位测试结果表明，一水硬铝石零电点为pH5．5，高岭石零电点为pH3．0。 2 阴离子捕收剂正浮选体系 一水硬铝石和高岭石两种矿物表面铝离子丰度的差异是导致它们可浮性不同的主要原因。油酸钠易与铝离子发生受电荷控制的化学作用，不易与矿物表面的硅离子发生受电荷控制的化学作用。而一水硬铝石表面的铝离子丰度是高岭石表面的1．7倍，因而油酸钠易于吸附于一水硬铝石表面，不易吸附于高岭石表面。 采用油酸钠为捕收剂时，加强对矿泥的分散是实现铝土矿正浮选工艺的关键。各种研究结果表明，以油酸钠为捕收剂时，一水硬铝石和高岭石两种矿物的可浮性差异较大，抑制剂的添加对两种单矿物的分离效果没有产生明显的作用。对于铝土矿正浮选脱硅工艺，选择合适的调整剂，加强对矿泥的分散，可以提高脱硅指标。 研究提出了铝土矿选择性疏水聚团正浮选脱硅新工艺。该工艺采用组合阴离子捕收剂KL，添加碳酸钠和六偏磷酸钠加强对矿泥的分散。 实际矿石小型闭路试验结果为：精矿Al₂O₃品位70．74％，回收率90．52％，精矿中SiO₂含量从11．4％降低到6．37％，精矿铝硅比达到11．11，超过国家九五攻关指标（Al₂O₃回收率78％，铝硅比10）。 规模为日处理量1吨连选试验结果为：精矿Al₂O₃品位70．17％，SiO₂含量6．37％，精矿铝硅比为11．02，回收率88．47％。规模为日处理量50吨工业试验。工业试验中药剂匹配试验结果再次表明，强调对矿浆分散是铝土矿正浮选脱硅的关键。工业试验结果为，精矿铝硅比 11．39，A12O3回收率为 86．45％。浮选精矿满足拜耳法生产氧化铝要求。 3 阳离子捕收剂反浮选体系 在阳离子捕收剂浮选体系中，矿物表面荷电机理的不同是导致高岭石和一水硬铝石可浮性差异的主要原因。采用十二烷基醋酸胺为捕收剂时，一水硬铝石浮选行为受溶液。pH值的影响，当 pH＜5．5，一水硬铝石可浮性差；当 pH＞5．5，一水硬铝石可浮性较好。高岭石由于端面与层面的荷电机理不同，在酸性条件下，端面荷正电，层面荷负电，高岭石发生聚团，总表面积减小，表面药剂吸附密度相对增加：而在碱性条件下，矿浆中捕收剂的残余浓度较低，表明对药剂的吸附总量增大，但由于高岭石层面和端面都荷负电，处于分散状态，总表面积增大，因而高岭石表面的捕收剂吸附密度并不高，导致高岭石表面疏水性相对降低，通过加大捕收剂用量可以提高高岭石在碱性条件下的可浮性。 预先脱泥和矿泥的分散与抑制是实现铝土矿阳离子捕收剂反浮选脱硅工艺的关键。试验研究表明，阳离子捕收剂对一水硬铝石和高岭石的选择性较差，需要添加合适的抑制剂增强分选效果；淀粉和 DW两种药剂具有较好的选择性和抑制能力，可以作为反浮选脱硅中一水硬铝石矿物的抑制剂。矿泥对阳离子捕收剂浮选影响较大，预先脱泥和强．化矿泥分散是实现铝土矿阳离子捕收剂反浮选脱硅工艺的关键。 提出了铝土矿选择性脱泥一反浮选脱硅新工艺c采用NazCO3调矿浆为弱碱性，以分散剂六偏磷酸钠WazsiF。实现矿浆的有效分散，以 DW和淀粉为抑制剂、1827为捕收剂，通过选择性脱泥与反浮选相结合的技术路线，进行了两种方案的实际矿石试验。两种试验方案均取得了满意的指标，精矿铝硅比为 9叶，AI。O。回收率 85－89％。 4 捕收剂与矿物表面作用机理研究结果表明： 对于铝土矿阴离子捕收剂正浮选体系，在常温条件下，油酸钠在 pH值 4—10之间主要以油酸根离子形式吸附在矿物表面，以氢键形式相连，同时还存在油酸根离子直接与铝离子以离子键相互作用的化学吸附，但后者需要有一定的药剂浓度和温度条件。 对于铝土矿阳离子捕收剂反浮选体系，十二烷基醋酸胺与矿物表面主要是以静电力作用的物理吸附。更多还原

【Abstract】 In this dissertation, the differences in crystal structures, surface properties and floatability of kaolinite and diaspore were studied. Some factors effecting on the process of bauxite floatation were found by investigating the flotation behavior of the two minerals on single mineral test under different reagent conditions. Corresponding measures were put forward. At the same time, the action mechanisms between collector and minerals had been researched in details. Main conclusions are obtained as following:1. There are four differences of kaolinite and diaspore on crystal structures and surface properties.In the crystal lattice of diaspore, aluminum-oxygen octahedron forms double chain. In the crystal lattice of kaolinite , aluminum-oxygen octahedron and silicon-oxygen tetrahedron forms Isyer type silicate mineral in a ratio of 1:1;The acidity of aluminum ion on mineral surface is medium, and the acidity of silicon-ion on mineral surface is weak;Abundance of aluminum atom on the surface of diaspore is 1.7 times larger than that on the surface of kaolinite;Absorbing or ionizing H* result in charging on surface of diaspore; Zata-potential of diaspore is variable with pH in the solution. Charging mechanism of on surface of kaolinite are two kind. The charge of lateral surface of kaolinite results from absorbing or ionizing H*, and the charge of layer surface of kaonilite owe to crystal lattice displacement of cation. The latter is related to the degree of displacement and independent of pH value in solution. The point of zero charge (P.Z.C) of diaspore is pH5.5, and pH3.4 for kaolinite.2. Obverse floatation of bauxite using anion collectorOn the obverse floatation of bauxite, the primary factor to result in difference on floatability for kaolinite and diaspore is the difference on abundance of aluminum atom on minerals surface. Because of the difference of acidity for kaolinite and diaspore, sodium oleate tends to take action with aluminum ion but not silicon ion, which is controlled by electric charge. Abundance of aluminum atom on the surface of diaspore is 1.7 times larger than that of kaolinite, so sodium oleate tends to absorb on surface of diaspore.To enhance the dispersion on slurry is the key for obverse floatation of bauxite using anion collector. The results of single mineral flotation with collectors and depressors indicate: there are obvious difference on floating behavior of kaolinite and diaspore, and depressors make no effect on the process of separation. Using appropriate dispersant to enhance theindispersion effect on slurry, satisfactory results of desilication can be obtained by obverse floatation.The new technique of bauxite floatation, selective hydrophobic agglomeration floatation, was put forward in this paper. On the new technique of bauxite floatation, anion collector was KL, and modifiers Na2CO3 and (NaPO3)6 was used to enhance the dispersion on slurry ..The concentrate Al/Si 11.11 and the recovery of Al2O3 90.52% were obtained through closed-circuit test on the ore. The concentrate Al/Si 11.02 and the recovery of Al2O3 88.47% were obtained through the test on bauxite ore (1 ton ore was processed every day).Using Na2CO3 and HZT as modifiers, HZB as collector, 470.39 tons bauxite (Al/Si 5.90) had been processed to produce 402 tons concentrate (Al/Si 11.39) by pilot plant, and recovery of Al2O3 was 86.45%. The results of the matching test on reagents had indicated again that to enhance the dispersion on slurry is the key for obverse floatation of bauxite.3. Reverse floatation using cation collectorOn the reverse floatation of bauxite, the primary factor to result in difference on floatability for kaolinite and diaspore is the different charging mechanism on the mineral surfaces. Using cation collector, the floatability of diaspore in the range of pH less than 5.5, is not as good as in the range of pH over than 5.5. Because of the different charging mechanism on the layer and lateral surface, In acidity and neutral condition, kaolinite is in更多还原