【作者】 刘长淼；

【导师】 胡岳华； 曹学锋；

【作者基本信息】 中南大学 ， 矿物加工工程， 2009， 博士

【摘要】 本论文以铝硅矿物的晶体结构和浮选药剂分子设计理论为基础,设计并合成了六种叔胺捕收剂；通过单矿物浮选试验,查明了合成药剂对一水硬铝石和高岭石的捕收行为；通过动电位测试、红外光谱测试、溶液化学计算、量子化学计算和分子动力学模拟等,探讨了十二系列叔胺与一水硬铝石和高岭石的作用机理,分析确定了叔胺分子中取代基的取代基效应与其浮选性能之间的关系。主要内容如下：(1)破碎时,一水硬铝石主要沿(001)晶面解离,亲水性较强；高岭石沿(001)晶面完全解理,沿(110)与(010)晶面不完全解理,也有较强亲水性。一水硬铝石和高岭石的荷电机理相似,主要由断裂晶面对H+的吸附或解离引起,且电荷随pH不断变化；此外金属离子的晶格取代使高岭石的层面荷永久负电。捕收剂的极性基团设计以N为主体；选定捕收剂的极性基为取代叔胺型,即-NR2型,取代基选用CH3、C2H5、C3H7、C7H7。(2)以脂肪胺、醛、甲酸为原料,采用还原烷基法,制备合成出两个系列6种叔胺化合物,合成产率较高,纯度在80%以上。(3)叔胺捕收剂对一水硬铝石和高岭石的浮选性能如下：当浮选一水硬铝石时,六种叔胺捕收能力普遍不高,DRN12、DPN12、DBN12和DRN16的回收率最大值分别只有：52%、61%、6%和62%。当增大叔胺用量时,一水硬铝石的回收率呈增长趋势。当浮选高岭石时,除了取代苄基叔胺(DBN12)以外,其他五种叔胺的捕收能力普遍较好,pH=2-3.5时,高岭石的回收率都在85%以上,当增大叔胺用量时,回收率会逐渐增加。十二系列叔胺对高岭石具有更好的选择性捕收能力,其中DRN12、DEN12和DPN12捕收高岭石和一水硬铝石的最大回收率差(Rkaolinite-Rdiaspore)分别可达42%、41%和42%。十二系列叔胺对一水硬铝石和高岭石的浮选性能表现出相同的规律性：DEN12>DPN12>DRN12>DBN12。(4)十二系列叔胺与铝硅矿物表面的作用机理研究表明：十二系列叔胺与铝硅矿物表面的作用形式为物理吸附,且无力吸附是由静电作用引起的,与铝硅矿物表面作用后,叔胺能显著增加它们的表面电位；同时十二系列叔胺改变铝硅矿物的表面电位的大小顺序为：DEN12>DPN12>DRN12>DBN12。酸性条件下,一水硬铝石表面主要是Al-OH,阳离子态的叔胺难以与其发生静电作用；高岭石表面主要是Al-OH和Si-OH,但由于高岭石颗粒带永久负电,因此阳离子态的叔胺可以与其产生静电作用。碱性条件下,一水硬铝石表面主要是Al-O,叔胺阳离子易与其产生静电作用,当pH>pHs以后,静电作用开始逐渐减弱；高岭石表面主要是Al-O和Si-O,叔胺阳离子易与高岭石产生静电作用,但由于高岭石颗粒荷电较多而使溶液中颗粒极度分散,以及叔胺的疏水碳链可能发生的疏水缔合,使浮选效果反而变差。(5)十二系列叔胺的取代基效应与其浮选性能的关系研究表明：四种十二叔胺中取代基的诱导效应对叔胺的EHOMO及N原子上的净电荷的影响大小顺序为：DPN12>DEN12>DRN12>DBN12；取代基的诱导效应对叔胺的阳离子的头基端的正电荷的影响大小顺序为：DPN12>DEN12>DRN12>DBN12。四种叔胺中取代基的空间效应大小顺序为：DBN12>DPN12>DEN12>DRN12。叔胺阳离子与高岭石(001)面发生静电作用,叔胺阳离子逐步靠近(001)面,并最终吸附于(001)面；在靠近(001)面的过程中,叔胺阳离子中的取代基会因空间位阻效应而发生偏转扭曲,其中某些键间的键角发生变化。模拟过程稳定后,DRN12H+、DEN12H+和DPN12H+中N原子距(001)面的距离分别为：2.99A、2.94A和3.001A。四种叔胺与高岭石之间的静电相互作用强弱顺序为：DEN12>DPN12>DRN12>DBN12；叔胺中的取代基的诱导效应和空间效应的综合效果,使其浮选性能表现应有的规律：DEN12>DPN12>DRN12>DBN12。更多还原

【Abstract】 In this paper, based on the crystal structure of diaspore and kaolinite, as well as the designing theory of flotation reagents, six tertiary amines collectors were designed and synthesized. By means of micro-flotation tests of pure minerals, the flotation performances of six tertiary amines on diaspore and kaolinite were investigated and figured out. Using the measurements of zeta-potential and FT-IR, the calculations of solution chemistry and quantum chemistry, and the simulations of molecular dynamics, the interaction mechanisms between tertiary amines and minerals, as well as the relationship between performances of collectors and substituent groups in the molecule of amines, were studied and discussed. The main contents were briefly summarized as follow.(1) When being ground to particles, the liberation of diaspore takes place mainly along the (001) crystal planes, breaking Al-O bonds with high energy and stronger hydrophilicity. The liberation of kaolinite takes place along (001) completly, and along (110) and (010) planes incompletely. Besindes the Al-O bonds whit high energy, there are also the Si-O bonds on these liberation surfaces, which also exhibited the strong hydrophilicity. The surface charging mechanism of diaspore and kaolinite is similarly controlled mainly by the ionization of the surface O-H groups, and this part of charge is dominated by the pH of the pulp. In addition, the isomorphic exchange of kaolinite surface ions is responsible for the permanent negative charge of (001) planes. Under the aim of enhancing the collecting power and selectivity of new collecters on kaolinite, based on the basic structure of flotation reagents and surface characteristics of diaspore and kaolinite, N atom was determined to be the bonding atom of the polar group of new collectors; meanwhile, in order to enlarging the inductive effect of N atom, using the dodecyl amine as the matrix, the polar group was determined to be the tertiary amine group (-NR2), and the substituent groups included CH3, C2H5, C3H7 and C7H7.(2) By using aliphatic amines, aldehyde and formic acid as raw materials, two series and six tertiary amines including DRN12, DEN12, DPN12, DBN12, DRN16 and DEN16 were synthesized and prepared in lab by means of reduction and alkylation to primary amine. The synthetic yield of tertiary amines is considerable high, and near all these amines have the purity of more than 80%.(3) Flotation performances of tertiary amines on diaspore and kaolinite showed that the collecting powers of six tertiary amines on diaspore were weak, the recovery maximum were 52%,61%,6% and 62% respectively, when using DRN12, DPN12, DBN12 and DRN16, and were about 78% when using DEN12 and DEN16.When increasing the dosage of tertiary amines, recoveries of diaspore increased a little. Except for the DBN12, the collecting abilities of other tertiary amines on kaolinite were commonly better. The recoveries of kaolinite were almost more than 85% when using these collectors at pH=2-3.5. After increasing the dosage of these amines, recoveries of kaolinite increased gradually; when the concentration of amines was added up to 4×10-4mol/L, the recoveries of kaolinite were almost more than 95% except the DBN12. DRN12, DEN12 and DPN12 have the stronger selectively collecting power on kaolinite than diaspore, the differences of maximum recovery of kaolinite and diaspore(Rkaolinite-Rdiaspore) were 42%、41%和42%. The flotation performances of sery-12 tertiary amines on diaspore and kaolinite follow the same order of DEN12> DPN12> DRN12> DBN12.(4) Based on the calculation of solution chemistry and measurements of FT-IR and zeta potentials, the interaction mechanisms between tertiary amines and diaspore and kaolinite were investigated.The results showed that the interaction mode between collectors and minerals was physics adsorption controlled by electrostatic power. The physics adsorption between collectors and kaolinite was more remarkable, and that between collectors and diaspore was not remarkable enough. After adsorption on minerals, tertiary amines can increase the zeta potentials of diaspore and kaolinite. The changing amounts of potentials from tertiary amines were in the order of DEN>DPN>DRN>DBN. In the acid pulp, the surface of diaspore are mainly the Al-OH, leading to the cation of tertiary amines difficultly to adsorb onto the surface of diaspore; the surface of kaolinite are mainly the Al-OH and Si-OH, but its surface is partly charged negatively because of the isomorphous replacement, leading to the cation of tertiary amines easily to adsorb onto the surface of kaolinite. In the basic pulp, the surface of diaspore are mainly the Al-O, leading to the cation of tertiary amines easily to adsorb on to the surface of diaspore; and the surface of kaolinite are mainly the Al-O and Si-O, leading to the cation of tertiary amines easily to adsorb on the surface of kaolinite; however, because the negative charged kaolinite particles are extremely dispersed in the pulp, and the hydrophobic carbon chain of tertiary amines may be associated together for the hydrophobic power, the flotation recoveries of kaolinite are lower irregularly.(5) Based on the quantum chemistry and molecular dynamics simulation, the relationships between substituents effects and flotation performance were investigated. Being Influenced by the inductive effect of substituent groups, the EHOMO and net charge of N atom of tertiary amines follow the intensity sequence of DPN12>DEN12> DRN12>DBN12; and the positive charge of the head group of tertiary amines follow the same order of DPN12>DEN12> DRN12>DBN12. The space steric effects of the substituent groups in four tertiary amines follow the order of DBN12>DPN12>DEN12> DRN12. The electrostatic forces between four collectors and kaolinite (001) surface are in the order of DEN12>DPN12>DRN12>DBN12. In one word, these two aspects account for an increase in collecting power according to: DEN12>DPN12>DRN12>DBN12.更多还原