【作者】 张英；

【导师】 胡岳华； 王毓华；

【作者基本信息】 中南大学 ， 矿业工程， 2012， 博士

【摘要】 白钨矿与含钙脉石矿物的浮选分离一直是选矿工作者研究的热点,其难点在于矿物的晶体性质、物理化学性质等相似,浮选过程中彼此间相互干扰,且可浮性相近,这就需要在浮选过程中强化白钨矿的选择性捕收,同时强化对含钙脉石矿物的选择性抑制。论文借助单矿物浮选试验,以及动电位、红外光谱、X射线光电子能谱等表面测试技术,系统研究了不同抑制剂对白钨矿、萤石和方解石浮选的抑制性能及与矿物间的作用机理；同时借助量子化学及能带理论,计算分析了三种矿物的结构,以及矿物与水和抑制剂间的作用机理,研究的主要内容如下：通过单矿物浮选试验,研究了硅酸钠、硅胶、硅酸钠与硅胶组合抑制剂对白钨矿、萤石和方解石浮选行为的影响。油酸钠和731作捕收剂、pH=9.7～10.3时,采用硅酸钠与硅胶组合抑制剂,硅胶比例的增加对白钨矿、萤石和方解石的浮选行为的影响很小。组合抑制剂的最佳浓度为2.5g/L,且三种矿物浮选回收率的大小顺序为白钨矿>方解石>萤石；采用单一硅酸钠为抑制剂时,硅酸钠对白钨矿、萤石和方解石浮选的影响规律基本一致。731浓度为75mg/L、pH=9.7～10.3时,Al3+、Pb2+、K+、Ca2+等四种金属离子均能增强硅酸钠的抑制能力。相对于白钨矿：方解石=1：1混合矿,硅酸钠更易于实现白钨矿：萤石=1：1混合矿的浮选分离；对白钨矿：萤石：方解石=1：1：1的三元混合矿有一定的分选性。有机抑制剂对白钨矿、萤石和方解石浮选选择性抑制能力大小顺序为：大分子量聚丙烯酸钠>柠檬酸>栲胶>淀粉。油酸钠浓度为5×104mol/L、pH=8.7～9.3时,PA-Na-2对三种矿物的浮选分离的选择性抑制效果最好,最佳浓度为37.5mg／L。731浓度为75mg/L、pH=8.7～9.3时,PA-Na-2和PA-Na-3对萤石和方解石的抑制能力很强,二者的回收率均低于20%,而白钨矿的回收率保持在70%左右。PA-Na-2和PA-Na-3均可能实现白钨矿与萤石、方解石浮选分离,且最佳浓度范围分别为37.5～50mg/L和22.5～30mg/L；在PA-Na-2作用下,金属离子Pb2+能促进白钨矿在弱碱性条件下的浮选,提高二元及三元混合矿浮选分离的选择性。白钨矿、萤石和方解石与药剂作用前后红外光谱图的变化表明：硅酸钠基团中的Si-O键振动使得白钨矿、萤石和方解石的特征峰均发生了位移,说明硅酸钠在三种矿物表面均发生了吸附；与聚丙烯酸钠作用后,白钨矿、萤石和方解石表面均出现了羧酸根(COO-)的反对称振动的特征峰和对称振动吸收峰,由此可见,聚丙烯酸钠在三种矿物表面发生了化学吸附。动电位研究表明,硅酸钠和聚丙烯酸钠对白钨矿表面电位的影响较小,而萤石和方解石的表面电位负移程度均较大。两种抑制剂作用下,矿物表面电位负移程度强弱顺序分别为：萤石>方解石>白钨矿、萤石≈方解石>白钨矿,这与矿物的浮选行为一致。X射线光电子能谱分析表明,硅酸钠和聚丙烯酸钠与矿物作用后,矿物表面的Ca2p结合能均向高能方向位移,大小顺序均为方解石>萤石>白钨矿,硅酸钠和聚丙烯酸钠在白钨矿表面的作用均最弱。说明硅酸钠和聚丙烯酸钠在三种矿物表面均发生了吸附,且在萤石和方解石表面的吸附强于白钨矿。通过矿物的量子化学计算及矿物与水和聚丙烯酸钠作用的能量计算,水溶液中聚丙烯酸钠在与三种矿物表面作用的吸附能的绝对值大小分别为萤石(293.29eV)>方解石(178.54eV)>白钨矿(133.57eV),与聚丙烯酸钠对三种矿物浮选的抑制能力强弱顺序一致。在处理江西某白钨选矿厂预先脱硫后的产品(含WO30.55%)时,粗选选用硅酸钠做抑制剂,经一粗五精(二次空白精选后精矿浓缩至50%,添加6000g/t硅酸钠并强搅拌45min)三扫的浮选开路流程,可获得浮选精矿含WO357.93%、回收率62%的指标。当粗选抑制剂为聚丙烯酸钠时,采用一粗六精(二次空白精选后精矿浓缩至50%,添加6000g/t硅酸钠并强搅拌45min)三扫的浮选开路流程,浮选精矿含W0353.06%,回收率52.75%。更多还原

【Abstract】 The flotation separation of scheelite from fluorite and calcite is one of the interesting issues in the field of minerals processing. The separating difficulty of scheelite from fluorite and calcite is that the similar flotability of these minerals due to the similar crystal and surface chemical properties, therefore, it is necessary to strength the selective collecting of sheelite and the selective depressing of calcareous gangue minerals in the flotation prcess.The depressing behaviors and reaction mechanisms of different depressants on the flotation of scheelite, fluorite and calcite have been investigated by means of flotation test, zeta potential measurement, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. In order to reveal the microscopic mechanisms between depressants and minerals, the structure of minerals and the interaction between minerals and depressants have also been studied using the Quantum Chemistry and Band Theory. The major contents of this study are as follows:The depressing behaviors of sodium silicate, silica gel and the combined depressant of sodium silicate and silica gel on the flotation of scheelite, fluorite and calcite have been investigated by micro-flotation. In the presence of sodium oleate or731, the depressing effect can not be enhanced with increasing the dosage of silica gel in combined depressant for separating sheetite from fluorite and calcite by flotation within the pH range of9.7to10.3, and the optimum dosage of combined depressant is2.5g/L. The flotation recovery of three minerals changes according to the order:scheelite>calcite>fluorite while using combined depressant. In the presences of75mg/L731, the depressing effect of sodium silicate on the flotation of minerals can be strengthed with the addition of Al3+, Pb2+, K+and Ca2+over the pH range from9.7to10.3. The flotation separation of scheelite from artificial mixtures which composed with50%scheelite and50%calcite is easier than that from artificial mixtures which composed with50%scheelite and50%fluorite. The flotation separation of artificial mixtures composed with sheelite, calcite and fluorite had also shown some selectivity.The selective depressing effect of organic depressants on minerals falls in the following order:sodium poly acry late>citric acid>tannin extract>starch. The scheelite can be separated efficiently from fluorite and calcite by flotation in the pH range from8.7to9.3using5×10-4mol/L sodium oleate as collector and37.5mg/L PA-Na-2as depressant.Using75mg/L731as collector, fluorite and calcite can be depressed effectively by PA-Na-2and PA-Na-3in the pH range from8.7to9.3, and the flotation recoveries of these two minerals are below20%, while the flotation recovery of scheelite remaines at about70%. The optimum concentration of PA-Na-2and PA-Na-3for the flotation separation of scheelite from fluorite and calcite is37.5-50.0mg/L and22.5-30.0mg/L respectively. Pb2+can activate the floatability of scheelite in weak alkaline conditions when PA-Na-2is used as depressant, and then the flotation separating selectivity of the artificial mixtures can be improved.The FTIR spectra of minerals treated with sodium silicate were studied. The characteristic peaks of minerals shifted a little wavenumbers due to the stretching vibration of Si-O from sodium silicate, and it shows that sodium silicate adsorbed on three mineral surface. New antisymmetric vibration characteristic peaks and symmetric vibration absorption peaks of COO-were observed on the mineral surface after the reaction with sodium polyacrylate, and it indicates that sodium polyacrylate is bound to the three mineral surface by chemical adsorption.The results of zeta potential measurements show that the zeta potentials of scheelite shift negatively a little, however, the zeta potentials of fluorite and calcite shift to more negative values in the presence of sodium silicate and sodium polyacrylate. The zeta potentials shift negatively abide by the order:fluorite>calcite>scheelite with the adding of sodium silicate, and the order:fluorite≈calcite>scheelite with the adding of sodium polyacrylate, and these results are corresponding with the results of miroc flotation tests.The XPS measurments show that Ca2p binding energy of minerals surface move to the direction of high energy in the following order: calcite>fluorite> scheelite. It indicates that sodium silicate and sodium polyacrylate all adsorb on the surface of scheelite, fluorite and calcite, but the adsorption on the surface of scheelite is the weakest.The quantum chemical simulation indicates that the absolute value of adsorption energy abided by the oreder:fluorite (293.29eV)> calcite (178.54eV)> scheelite (133.57eV) when sodium polyacrylate adsorbs on the three mineral’s surface in aqueous solution. These results are consistent with the results of micro-flotation experiments.Batch flotation tests have been conducted for Jiangxi scheelite ore (WO30.55%) with pre-desulfurization. By adopting a circuit with one stage rougher flotation, five stages of cleaner and three stages of scavenger, the scheelite concentrate was produced with the grade of57.93%WO3and the recovery of62%WO3while using Na2SiO3as rough floatation depressant. When the depressant PA-Na-2was used for rough floatation, the result shows that the WO3grade of scheelite concentrate is53.06%and the recovery of WO3is52.75%by adopting a circuit with one stage rougher flotation, six stages of cleaner and three stages of scavenger. For both batch tests, the concentrate after the twice blank cleaning was condensed to50%wt, and stirred strongly for45min with the addition of6000g/t Na2SiO3.更多还原