مطالعه آزمايشگاهي و مدلسازي رياضي فرايند بازيابي پلاتين از كاتاليست‌هاي مستعمل به روش استخراج جامد-مايع سيانوري در دما و فشار بالا

چكيده انگليسي :

Abstract One of the methods of the platinum recovery from industrial wastes is the solid liquidextraction by cyanide solution at high temperatures and pressures So far few studies havebeen conducted in the field of scientific survey of this process so that some aspects of thisprocess such as the kinetics of the reaction of platinum with sodium cyanide arecompletely unknown Accordingly this research was conducted to study the platinumrecovery process from spent catalysts in a fixed bed reactor using solid liquid extraction bycyanide solution At the first step kinetics of thermal decomposition of the cyanide ions ina sodium cyanide solution at high temperatures was studied The kinetics experiments werecarried out under various operating conditions including the temperature of the solution 120 140 and 160 C and the initial concentration of the cyanide solution 1 and 3 5wt The obtained kinetic data were fitted into an empirical power law rate equation andkinetic model parameters were evaluated using the experimental data via a non linearregression analysis The values of reaction rate order with respect to the cyanide ion andactivation energy are 1 63 and 115 9 kJ mol respectively The average error of kineticmodel in predicting the experimental data is 9 7 At the second step the kinetics ofplatinum extraction from spent catalyst in cyanide solution at temperatures between 100and 180 C was experimentally studied Based on the design of experiments via responsesurface methodology RSM by computer simulating software Minitab 16 experimentswere carried out at operating conditions including five solution temperatures five initialconcentrations of cyanide solution and five liquid solid weight ratios The obtained kineticsdata were fitted into an empirical power law rate equation and the kinetics modelparameters were evaluated by using experimental data via non linear regression analysis The reaction orders with respect to platinum and cyanide ions were calculated to be 3 62and 0 192 respectively Also the activation energy for this reaction was calculated to be39 54 kJ mol The average error of kinetic model in predicting the experimental data is 16 73 At the final step and for surveying the dynamic behavior of a fixed bed reactorwith continuous operation experiments were carried out in a fixed bed reactor in differentconditions at varying leaching temperature cyanide solution concentration and volumeflow rate of solution Next a dynamic mathematical model was developed for platinumextraction in a fixed bed reactor and the model was programmed and coded for simulationof the process through a homemade modeling environment in Matlab 7 11 0 R2010b software The predicted results by the model are in good agreement with the experimentaldata with a relative absolute error of less than 10 This model was applied in assessingthe effect of operating parameters The results show that the optimum values of the inletsodium cyanide solution temperature and concentration are 160 C and 1 wt respectively Also varying the volume ow rate of solution and Distribution of cyanidesolution along the length of the reactor through side stream have no effect on platinumrecovery efficiency

نقوي، زهراسادات

مطالعه آزمايشگاهي و مدلسازي رياضي فرايند بازيابي پلاتين از كاتاليست‌هاي مستعمل به روش استخراج جامد-مايع سيانوري در دما و فشار بالا