【作者】 张钦发；

【导师】 龚竹青； 陈白珍；

【作者基本信息】 中南大学 ， 冶金物理化学， 2007， 博士

【摘要】 某冶炼厂铜阳极泥分金钯后的铂精矿由于没有合适的提取分离工艺而积累，本论文提出了从铂精矿中提取分离铂、钯、金的新工艺路线：预处理富集Au、Pd、Pt—氯化浸出Au、Pd、Pt—NH₄Cl沉Pt—溶剂萃取分离Au、Pd、Pt。研究得出了最佳工艺条件，并通过工业试验，取得了较好的技术指标。研究了氯化钯制备新工艺和萃取机理。针对铂精矿中Au、Pt、Pd含量低，同时部分Pt、Pd还以化合物状态存在的特点，通过试验研究及比较分析，确定了水合肼还原—氨浸—酸浸的预处理新工艺，得出了最佳工艺条件，预处理除去了93％的杂质元素，使金银铂钯的富集比达14以上，Pt、Pd、Au、Ag的溶解损失率仅分别为0.70％、0.38％，、0.12％和0.60％。为后段的Pt、Pd、Au的提取奠定了基础。在对Au、Pt、Pd相关热力学分析的基础上，研究了金、铂、钯氯化浸出的工艺条件，取得了Au、Pt、Pd浸出率均大于99.5％浸出指标。针对所得的氯化浸出贵液Au含量较低，铂含量较高的特点，通过对工艺流程试验研究和对技术指标的对比分析，确定了从贵液中提取分离铂、钯、金的最佳工艺流程为：NH₄Cl沉Pt—硫醚萃取Au、Pd——三辛胺萃取Pt，研究得出了最佳工艺条件和技术指标，NH₄Cl沉Pt的沉淀率为89.34％，Au、Pd的一级萃取率分别可达99.2％和99.4％，Pt一级萃取率可达94.6％指标。工业试验结果表明：从铂精矿中提取分离Au、Pt、Pd的新工艺路线可行，效果良好。根据TOA的浓度、氯离子浓度、氢离子浓度对TOA萃取Pt（Ⅳ）、Pd（Ⅱ）的萃取分配比影响的试验结果以及对Pt（Ⅳ）、Pd（Ⅱ）萃合物和Pt（Ⅳ）、Pd（Ⅱ）相关化合物的吸光曲线的分析对比，得出TOA萃取Pt（Ⅳ）主要以[（R₃NH⁺）₂PtCl₆]、[（R₃NH⁺）HPtCl₆]和[（R₃NH⁺）PtCl₅]形式萃取，Pd（Ⅱ）主要以[（R₃NH⁺）₂PdCl₄]和[（R₃NH⁺）HPdCl₄]形式萃取，萃取形式主要由Cl^-和H⁺浓度决定，测定了Pt（Ⅳ）Pd（Ⅱ）以[（R₃NH⁺）₂PtCl₆]和[（R₃NH⁺）₂PdCl₄]形式萃取的表观平衡常数分别为：K’_e（Pt）=4.56×10⁵、K’_e（Pd）=2.38×10⁵（邻二甲苯中）和K’₍e（Pt）=1.17×10⁶，K’_e（pd）=5.73×10⁵（环已烷中），邻二甲苯体系中萃取反应焓变分别为24.06KJ·mol^-1、-28.447KJ·mol^-1，熵变分别为28.92J·K^-1、9.04J·K^-1。推导出了萃取分配比与TOA浓度等参数间的理论关系式，理论计算结果与试验测定值相吻合。采用Lewis恒界面池研究了TOA萃取Pt（Ⅳ）、Pd（Ⅱ）动力学，TOA萃取Pt（Ⅳ）、Pd（Ⅱ）的萃取速度基本符合准一级反应，研究得出萃取TOA萃取Pt（Ⅳ）、Pd（Ⅱ）属于界面反应控制类型；在邻二甲苯体系中正向萃取反应活化能分别为39.94KJ·mol^-1、21.15KJ·mol^-1，推导出正逆向萃取速度常数之比与TOA浓度、H⁺浓度和Cl^-浓度间理论关系式，理论计算值与试验测定值吻合。研究了极性稀释剂对TOA萃取Pt（Ⅳ）、Pd（Ⅱ）的影响及影响机理，正辛醇、MIBK、三氯甲烷加入会降低R₃NH⁺的表观电离常数、Pt（Ⅳ）和Pd（Ⅱ）的萃取分配比以及萃取速度，研究得出了正辛醇、MIBK、三氯甲烷对TOA萃取Pt（Ⅳ）、Pd（Ⅱ）影响主要是与R₃NH⁺产生了缔合副反应，降低了有机相中TOA的有效浓度，从而降低了萃取分配比和萃取速率，测定了正辛醇、MIBK和三氯甲烷与R₃NH⁺在邻二甲苯中的缔合表观平衡常数分别为：12.1、0.339和0.22，在环已烷中的缔合表观平衡常数分别为44.57、0.57和0.96，并推导得出萃取分配比和萃取速率常与缔合常数和极性溶剂浓度间的理论关系式，理论计算所得结果与试验测定结果相吻合。研究了由Pd（NH₃）₂Cl₂法制备氯化钯新工艺，以及传统的王水溶解海绵钯法制备氯化钯的赶硝新工艺，制备的氯化钯的钯的含量可达59.4％以上，其中铁的含量在0.002％以下，硝酸盐的含量低于0.04％，均达到化学试剂的分析纯标准。更多还原

【Abstract】 Platinum concentrates produced after extracting and separating Au, Ptand Pd from copper anode slime at a smelting plant, had been piled upwithout feasible technology of extraction and separation Pt, Pd and Au.New technology of extracting and separating of Pt, Pd and Au fromplatinum concentration are brought up: the enrichment Pt, Pd and Au bypretreatment of platinum concentration—leaching Pt, Pd and Au withchlorate in acidic solution—precipitating Pt with NH₄Cl-solvent extractingand separating Pt, Pd and Au. Optimal technical parameters are obtained bytests and good results are achieved in plant-scale test. New technology ofpreparation for palladium chloride and mechanism of extraction areinvestigated in this thesis.In consideration of the content of Pt, Pd and Au in platinumconcentrate are lower and the part of Pt and Pd occur in compound, newtechnology of pretreatment of platinum concentration are selected byinvestigation and analysis: reducing with hydrazine—leaching withNH₃H₂O-leaching with H₂SO₄, 93％impurity element are removed andthe content of Pt, Pd and Au in the concentration have been enriched by14 times in pretreatment, only 0.70％Pt, 0.38％Pd, 0.12％Au and0.60％Ag are lost, which establish foundation for the extraction andseparation of Pt, Pd and Au.on the basis of correlative thermodynamic analysis of Pt, Pd andAu, optimal technical parameter of leaching of Pt, Pd and Au areestablished by investigation, leaching ratio of Pt, Pd and Au are allabove 99.5％.considering the content of Au is lower and which of Pt is higher, bythe investigation on technical parameter and analysis on test results, thefeasible technology of Extraction and Separation of Pt, Pd and Au fromacidic aqueous chloride media have been established: precipitating Ptwith NH₄Cl—Extraction of Pd and Au with thioether—extraction of Ptwith tro-n-octylamine （TOA）. optimal technical parameter and satisfactoryresult have been achieved, precipitating ratio of Pt is 89.34％, extractionratio of Pd and Au respectively are 99.2％and 99.4％, extraction ratio of Pt is 94.6％in the first stage.The results obtained in plant-scale prove that the new technology ofextraction and separation of Pt, Pd and Au from platinum concentrate arefeasible to industrial application. The results are satisfactory.The Dependence of distribution ratio of Pt and Pd on TOA, chloride ion,hydrogen ion concentration and absorption spectra of chloropalladate andchloroplatinate complex with TOA suggests that the form of extraction ofPt with TOA is （R₃NH）₂PtCl₆, （R₃NH）HPtCl₆, （R₃NH） PtCl₅, the form ofextraction of Pd with TOA is （R₃NH）₂PdCl₄, （R₃NH）HPdCl₄, the form ofextraction of Pt and Pd depend on chloride ion and hydrogen ionconcentration.The extraction constants of Pt(Ke_Pt)with TOA is evaluated as4.56×10⁵ in o-xylene and 1.17×10⁶ in cyclohexane, The extractionconstants of Pd (Ke_Pd)with TOA is evaluated as 2.38×10⁵ in o-xylene and5.73×10⁵ in cyclohexane. It was found that Pd and Pt extraction areexothermic with enthalpy change of-28.447 KJ·moL^-1 and-24.06KJ·moL^-1respectively, entropy change of Pd and Pt extraction are 28.92J·K^-1and9.04J. K^-1respectively in o-xylene. The theory relation between distributionratio of Pt, Pd and TOA, chloride ion, hydrogen ion concentration havebeen deduced, result obtained by theoretical calculation is in agreementwith one obtained by experiment.The extraction kinetics of Pd and Pt with TOA from acidic aqueouschloride media had been investigated using Lewis constant interface cellin o-xylene, It was found that the extraction rate to confbrm withpseudo-first-order reaction, the extraction mechanism can be explained byinterface reaction model. The theory relation between The ratio of forwardextraction rate constant（k_f） and converse extraction rate constant （k_b） andTOA, chloride ion, hydrogen ion concentration have been deduced, resultobtained by theoretical calculation is in the agreement with oneobtained by experiment. Activation energy of forward extraction of Pt andPd is evaluated as 39.935KJ·moL^-1 and 21.154 KJ·moL^-1 in o-xylenerespectively.The effect of diluents on the extraction of Pt and Pd with TOA havebeen investigated, It was found that apparent ionization constant of R₃NH⁺ （K’_b）, extraction distribution ratio（D_r） and extraction rate of Pt and Pddecrease due to addition of octanol, MIBK and chloroform in o-xylene, theDependence of apparent ionization equilibrium constant of R₃NH⁺ （K’_b）,extraction distribution ratio（D_r） of Pt and Pd on octanol, MIBK andchloroform concentration in o-xylene or cyclohexane and absorptionspectra of chloropalladate and chloroplatinate complex with TOAsuggest that the association reaction of these polarity solvent with R₃NH⁺would reduce R₃NH⁺ concentration, so extraction distribution ratio andextraction rate of Pt and Pd decrease. Apparent equilibrium constant ofassociation reaction of R₃NH⁺ with octanol, MIBK and chloroform isevaluated as 12.1, 0.339 and 0.22 in o-xylene respectively, as 44.57,0.57 and 0.96 in cyclohexane respectively. The relation between the ratioof forward extraction rate constant（k_f） and converse extraction rate constant（k_b） and octanol, MIBK and chloroform concentration have been deducedin o-xylene, result obtained by theoretical calculation is in agreementwith one obtained by the experimentNew technology to be prepared for PdCl₂ by oxidation Pd （NH₃） ₂Cl₂and new technology of removal of nitrate using HCl-H₂O₂ as nitrate-removal agent in conventional to be prepared for PdCl₂ had beeninvestigated, content of Pd is above 59.4％upwards, ferric content isbelow 0.002％, content of nitrate is below 0.05％in PdCl₂ produced, thePdCl₂ meet to analytical chemical reagent standard.更多还原