Hydrometallurgical Operations Research Articles

Selective Recovery of Nickel and Cobalt from Electromachining Sludge Materials

ABSTRACT The recovery of nickel and cobalt from electromachining sludge in the form of relatively high-purity marketable products has been investigated. The investigation has shown that a series of hydrometallurgical unit operations can be performed to recover nickel and cobalt from electromachining sludge in the form of nickelic hydroxide and cobalt sulfate/cobalt metal, respectively. The recovery unit operations for nickel include high pH cyanide complexation, followed by oxidation and precipitation of nickelic hydroxide. The resultant filtrate can be treated for cobalt concentration and recovery by precipitation of a cobaltous/cobaltic double cyanide salt and cobaltous hydroxide. This concentrated form of cobalt can then be converted to cobalt sulfate by acid baking; then redissolved and electrowon as high purity cobalt metal. Product purity rivals that of conventional multistage solvent extraction processes. First order cost estimation indicates the possibility of excellent return on investment.

Technology for the extraction of rare and radioactive metals from ores without environmental pollution

Autoclave processes make it possible to increase the extraction of radioactive metals, process ores not prepared for ordinary technological schemes, intensify hydrometallurgical operations, and reduce the reagent consumption, without harming the environment. When hydrometallurgical operations are carried out at an elevated temperature with the gaseous reagent at a partial pressure of more than 0.i MPa, the thermodynamic equilibria shift in favorable ways and the kinetic constants change.

Process-data Acquisition in Hydrometallurgy

Current and future methods of data acquisition In hydrometallurgy are reviewed. Hydrometallurgical operations involve a wide range of chemical and physical processes for the recovery of metals and other products from ores and concentrates. Control of such operations requires information on the different liquid/solid and liquid/liquid mixtures being processed. Continuous data acquisition for the liquid phases uses procedures already commercially exploited in other types of chemical plant. The major problem is the lack, of robustness of measuring probes. Continuous analysis of the solid phases is much more difficult to achieve because of the sampling and analytical techniques involved

Coupled ionic equilibria in copper sulfate-sulfuric acid solutions

The coupling of the copper sulfate ion pair dissociation and the bisulfate ion dissociation in aqueous solutions is modeled mathematically. The problem is reduced to a cubic equation in the copper ion. Results for solutions representative of hydrometallurgical operations indicate that these ion interactions can significantly change the ionic concentrations, which could lead to errors in the evaluation of copper extraction kinetic data. The effect of temperature is also investigated and the hydrogen ion concentration is found to vary significantly with temperature.

On the role of analytical chemistry in solvent extraction processing

Analytical chemistry plays a vital role in both the development and operation of any chemical process, and the process of solvent extraction as applied in hydrometallurgical operations is no exception. Because of the increasing attention being given today to solvent extraction as a means of separating metals in solution, it seemed appropriate that the analytical chemistry associated with solvent extraction studies, process development, and operations be reviewed. In this review, consideration is given only to analysis of the aqueous and organic phases for the determination of solvent components, rather than to the determination of metals in these phases. Furthermore, the major emphasis is placed on analytical methods which are applicable to process studie and plant control, and which require a minimum of instrumentation and operator skill. The importance of sampling is discussed first, and problems encountered in obtaining representative samples from the solvent, aqueous, and slurry phases are considered in some detail. This is followed by a review of methods of analysis which are directly applicable, or are considered as having application, to the analysis of the organic and the aqueous phases of the solvent extraction process. Analytical methods for the determination of the various extractants, modifiers, and diluents presently being used, or considered for use, in commercial solvent extraction processes are surveyed. First, those methods which are applicable to the determination of reagents in the solvent phase are considered, followed by those which are available for analysis of the aqueous phase for the determination of soluble components of the solvent phase. In both cases extractants, modifiers, and diluents are considered separately. Finally, some of the more obvious analytical needs, and areas where research is required in order that a more complete understanding of the solvent extraction process can be obtained, are discussed.