The paper studies the kinetics of sulfuric acid leaching of nickel, the main component of grinding waste of ZhS-32VI rheniumcontaining heat-resistant superalloy formed during mechanical processing of products and containing such impurities as abrasive materials, oils, ceramics and other contaminants with refractory metal concentration in a solid residue, in agitation mode. The nickel content is 60 %. In addition to nickel, grinding waste contains other metals such as rhenium, chromium, cobalt, tungsten, tantalum, molybdenum, hafnium, titanium, and aluminum. The process of nickel leaching from waste with a sulfuric acid solution was carried out in a thermostated cell at an elevated temperature (55–85 °С), waste : 3 M H2SO4 solution phase ratio of 1 g : 10 ml, and stirring rate of 200 min–1. Kinetics was studied using a fraction of –0.071 mm with the highest yield (49.2 wt.%) in grinding waste. Convex kinetic curves of nickel leaching from waste were obtained. It was found that when the temperature changes from 55 to 85 °С, the time until leaching stops decreases from 220 to 140 min, and nickel recovery from the solution increases from 45 to 99 %. The data of the obtained kinetic curves were linearized according to the «contracting sphere» equation, Gistling–Braunstein and Kazeev–Erofeev equations (the latter is most suitable for description). Taking into account the assessment of anamorphosis correlation coefficients, it was found that nickel leaching from grinding waste is limited by the chemical reaction, and the process proceeds in the kinetic region of the reaction. The apparent activation energy calculated using the Arrhenius equation and rate constants obtained by processing linearized kinetic curves according to the «contracting sphere» model, was 47.5±0.5 kJ/mol. This value confirms the course of the process in the kinetic region where the process can be intensified by increasing its temperature.
The possibility of using the short-lived radioisotope 188Re (16.9 h) in the radioactive-tracer technique for estimation of the losses occurred during sample preparation and for analysis of the solutions with a low rhenium content is shown. The radioisotope was obtained in an 188Re generator, which is a glass column filled with aluminum oxide with a pre-adsorbed parent isotope 188W (69.4 days) that forms 188Re during β-decay. The latter in the form of a perrhenate ion was selectively washed into an aqueous solution, which was used to obtain a labeled solution. The values of rhenium losses and their distribution over the stages of sample preparation of carbon-containing raw materials (e.g., high-viscosity oil) including sintering, leaching, filtration and evaporation are estimated. It is shown that the greatest amount of rhenium is lost at the stage of sintering. However, the use of MgO + KMnO4 mixture minimize the losses occurred at this stage and, hence, the total losses of rhenium. A rapid procedure of rhenium determination using the method of radiometric correction with substoichiometric separation is described. The method is based on the quantitative extraction of a stable complex of tetraphenylphosphonium cation (TPhPh) with the perrhenate ion by dichloroethane. The extraction constant of (C6H5)4PReO4 complex is (3.03 ± 0.75) × 106. The extraction of the perrhenate ion not complexing with TPhPh does not exceed 1 – 2 %. The developed method provides rhenium determination in the sample at a level of 1 – 100 μg. A 10-fold excess of Zn2+ and Ni2+ present in a chloride-containing medium affects the determination of rhenium. The anions , , and have the most pronounced interfering effect whereas , , and Cl– do not interfere with the determination.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.