Search

In this paper, the effect of the combustion and turbulence Sub-Grid Scale (SGS) model on simulation of a pool fire turbulence field has been studied in open source Cumputational Fluid Dynamic (CFD) software, OpenFOAM. Two combustion models: Eddy Dissipation Model (EDM) and infinite fast chemistry, with the one-equation and Smagorinsky SGS model, are evaluated for a large-scale pool fire. In general, fast kineticbased combustion models predict excessive heat release rate. The mean squared of the velocity uctuations is over-predicted. In this simulation, the turbulence models have no significant effect on the results. In fact, the effect of the combustion model is dominant. The EDM combustion model is more compatible when used with the one-equation SGS model and improves the results compared to other cases. In addition, the infinite fast chemistry combustion model is not a suitable model for fire simulation. [ABSTRACT FROM AUTHOR]

Solvent extraction of yttrium (Y) from different aqueous solutions using the organic extractant 2- ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A) diluted in kerosene was investigated. Solution chemistry considerations were proposed to identify the predominant species in different aqueous media (H2SO4, HCl and HNO3). In general, nitric and hydrochloric acids were found to be more efficient than sulfuric acid for yttrium extraction. Separation studies showed that nitric acid provide higher separation of Y(III) from light REES while sulfuric acid works better when separation of Y(III) from heavy REEs is desired. [ABSTRACT FROM AUTHOR]

While predominance area diagrams (PADs) are useful for the determination of the stable phases in the metal-sulfur-oxygen system, they are constructed at constant temperature. Varying the temperature results in shifting of the equilibrium lines and the stability areas thereof. Since the available tools in hands of an extractive metallurgist are temperature and oxygen potential, a more useful diagram would be one that shows the stability areas of different phases as a function of temperature and percent of oxygen in the roast gas. Such diagrams, called ‘roaster’ diagrams, derive directly from PADs. Although such diagrams are used by extractive practitioners, this type of diagram is unavailable in the open literature. In this paper, the relationship between the PADs and roaster diagrams is discussed and PADs and roaster diagrams for the Zn-S-O and Pb-S-O ternary systems are constructed. This information will serve as the foundation for more complex four-component systems to follow in subsequent publications. [ABSTRACT FROM AUTHOR]

Porphyry copper and mixed copper-gold sulfide deposits contain varying amounts of precious (gold and silver) and platinum group metals (PGMs). Currently, milling and froth flotation is the most common processing route for the treatment of high-grade base metal sulfide ores. During this process, the precious metals and PGMs are also concentrated and represent a possible opportunity for the beneficiation of these metals to increase the overall economic value of the ore. Although not yet commercialized, the high temperature pressure oxidation (POX) of copper concentrates provides an alternative processing route to traditional smelting technology. With increasingly aggressive air quality standards and rising upstream processing costs for smelting, hydrometallurgical processing options become progressively attractive. The treatment of POX residues for the recovery of precious metals has seen significant attention and multiple processing routes have been developed on various scales. Extraction and beneficiation of PGMs from copper concentrate POX residue has garnered significantly less attention and mechanistic questions remain to be answered. Based on a review of the processing options for PGM ores and concentrates, hydrometallurgical processing routes for the extraction of PGMs from copper concentrate POX residues are envisioned. [ABSTRACT FROM PUBLISHER]