| 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(KePt)with TOA is evaluated as4.56×105 in o-xylene and 1.17×106 in cyclohexane, The extractionconstants of Pd (KePd)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(kf) and converse extraction rate constant (kb) 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(Dr) 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(Dr) 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(kf) and converse extraction rate constant(kb) 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.
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