M Wadsley - Academia.edu (original) (raw)
Papers by M Wadsley
A bibliographic data base on the thermodynamic properties of slags, mattes, alloys and other meta... more A bibliographic data base on the thermodynamic properties of slags, mattes, alloys and other metallurgical solutions has been created on a microcomputer, using a data base management system. The data base currently contains 800 data sets drawn from 1300 references covering 18 thermodynamic properties and 32 experimental methods. A system for abstracting from the literature has been developed for input to the data base. Output from the data base includes indexes, bibliographies, searches and reports as well as collections of standardized data sheets on individual solutions.
Consideration is given to the propagation of fractures as a potential hazard when handling high p... more Consideration is given to the propagation of fractures as a potential hazard when handling high pressure fluids. The inspection of pressure - entropy diagrams is appraised as a preliminary method for predicting the potential for a high-pressure fluid to support the propagation of a fracture in pipe lines or high-pressure equipment. For pure fluids, diagrams have been constructed using tabular data from published compilations. For fluid mixtures, diagrams have been constructed using data calculated by an equation of state. These diagrams are used to indicate potentially hazardous combinations of fluid composition and pressure.
The use of chemical thermodynamic modelling to screen both organic and inorganic supercritical fl... more The use of chemical thermodynamic modelling to screen both organic and inorganic supercritical fluid extraction systems for possible chemical reactions is presented. The energy changes associated with identified reactions are used to identify potentially hazardous situations. The potential for the generation of unwanted by-product species is also demonstrated by this technique.
Reference Module in Materials Science and Materials Engineering, 2016
Since the beginning of civilization metal extraction has been a field of interest for the mankind... more Since the beginning of civilization metal extraction has been a field of interest for the mankind. The ores of the metals as obtained from the nature must undergo a number of steps to be retrieved as metal in usable form. The general steps that follow are reduction, separation and refining processes. Thus to optimize the end product quality and reduction of environmentally harmful gases Phase Stability Diagrams (PSD) were developed. They provide information regarding the phase stability of the metal as well as impurities and other components involved in order to set the optimal variable conditions like pressure, temperature etc. and the design a reaction path. Therefore, some of the developments in the use of PSD have been discussed in this article briefly.
Encyclopedia of Materials: Science and Technology, 2001
Metallurgical and Materials Transactions B, 2011
The cost of maintaining and eventually replacing refractories as a result of slag attack is a sig... more The cost of maintaining and eventually replacing refractories as a result of slag attack is a significant cost component in the copper industry. Converting matte to blister copper takes place in reactors lined with direct-bonded magnesia-chrome refractories, and several continuous converting operations use calcium ferrite slag. Unfortunately, the low viscosity of calcium ferrite slag makes it aggressive toward the refractories. Ferrous calcium silicate (FCS) slag has been proposed as a replacement; however, the effect of this slag on magnesia-chrome refractories has not been studied. In this work, the interactions between FCS slag and magnesia-chrome refractory at 1573 K (1300°C) with an oxygen partial pressure of 10 À6 atm were studied and compared with that experienced with calcium ferrite slag under the same conditions. Both slags penetrated the pores in the refractory and caused compositional change in the chromite spinel intergranular bonding phase through cation interdiffusion, which resulted in cracking and debonding of periclase grains. It was observed that the refractory was penetrated much more deeply by calcium ferrite slag than FCS slag because of the higher surface tension and lower viscosity of calcium ferrite slag. As a result, the refractory was attacked less by FCS slag than it was by calcium ferrite slag. It is concluded that the use of FCS slag in continuous copper converting is likely to extend refractory life.
Journal of Applied Electrochemistry, 1996
ABSTRACT The oxidation reactivity of arsenopyrite FeAsS in dilute acid determines the recovery of... more ABSTRACT The oxidation reactivity of arsenopyrite FeAsS in dilute acid determines the recovery of gold from arsenopyritic gold ores by slurry electrolysis. Stoichiometric,sulfur- and arsenic- deficient arsenopyrite have practically the same oxidation rate. Arsenopyrite is covered with a metal deficient sulfide layer which appears to determine the restpotential of the electrode. This layer can be separately oxidized and reduced during bulk-oxidation of arsenopyrite. Arsenopyrite oxidation is accelerated by dissolved Na2SO4 and by high electrode potentials and solution acidity. The rate is controlled by a surface reaction with an apparent activation energy of 33kJmol–1.
Hydrometallurgy, 1992
Aqueous stability diagrams are frequently used to assist in interpreting the chemical mechanism o... more Aqueous stability diagrams are frequently used to assist in interpreting the chemical mechanism of many hydrometallurgicai systems. It has been found that, for multi-element diagrams, when chemical species containing more than one element, other than oxygen or hydrogen, are stable, more than one diagram is required to describe the system. The structure of multi-element diagrams was found to be primarily dependent on restrictions placed on the relative quantities of the component elements. The restrictions are determined by the stoichiometry of stable, multi-element species. Aqueous stability diagrams, calculated by the CSIRO-Monash Thermochemistry System for the iron-sulfur-water system at 523.15 K, and including a representation of the pyrrhotite solid-solution phase, are used to illustrate these features. Use of these diagrams in tlae interpretation of the mechanism of hydrometallurgical processes is discussed.
Fluid Phase Equilibria, 1993
Canadian Metallurgical Quarterly, 1991
A bibliographic data base on the thermodynamic properties of slags, mattes, alloys and other meta... more A bibliographic data base on the thermodynamic properties of slags, mattes, alloys and other metallurgical solutions has been created on a microcomputer, using a data base management system. The data base currently contains 800 data sets drawn from 1300 references covering 18 thermodynamic properties and 32 experimental methods. A system for abstracting from the literature has been developed for input to the data base. Output from the data base includes indexes, bibliographies, searches and reports as well as collections of standardized data sheets on individual solutions.
Consideration is given to the propagation of fractures as a potential hazard when handling high p... more Consideration is given to the propagation of fractures as a potential hazard when handling high pressure fluids. The inspection of pressure - entropy diagrams is appraised as a preliminary method for predicting the potential for a high-pressure fluid to support the propagation of a fracture in pipe lines or high-pressure equipment. For pure fluids, diagrams have been constructed using tabular data from published compilations. For fluid mixtures, diagrams have been constructed using data calculated by an equation of state. These diagrams are used to indicate potentially hazardous combinations of fluid composition and pressure.
The use of chemical thermodynamic modelling to screen both organic and inorganic supercritical fl... more The use of chemical thermodynamic modelling to screen both organic and inorganic supercritical fluid extraction systems for possible chemical reactions is presented. The energy changes associated with identified reactions are used to identify potentially hazardous situations. The potential for the generation of unwanted by-product species is also demonstrated by this technique.
Reference Module in Materials Science and Materials Engineering, 2016
Since the beginning of civilization metal extraction has been a field of interest for the mankind... more Since the beginning of civilization metal extraction has been a field of interest for the mankind. The ores of the metals as obtained from the nature must undergo a number of steps to be retrieved as metal in usable form. The general steps that follow are reduction, separation and refining processes. Thus to optimize the end product quality and reduction of environmentally harmful gases Phase Stability Diagrams (PSD) were developed. They provide information regarding the phase stability of the metal as well as impurities and other components involved in order to set the optimal variable conditions like pressure, temperature etc. and the design a reaction path. Therefore, some of the developments in the use of PSD have been discussed in this article briefly.
Encyclopedia of Materials: Science and Technology, 2001
Metallurgical and Materials Transactions B, 2011
The cost of maintaining and eventually replacing refractories as a result of slag attack is a sig... more The cost of maintaining and eventually replacing refractories as a result of slag attack is a significant cost component in the copper industry. Converting matte to blister copper takes place in reactors lined with direct-bonded magnesia-chrome refractories, and several continuous converting operations use calcium ferrite slag. Unfortunately, the low viscosity of calcium ferrite slag makes it aggressive toward the refractories. Ferrous calcium silicate (FCS) slag has been proposed as a replacement; however, the effect of this slag on magnesia-chrome refractories has not been studied. In this work, the interactions between FCS slag and magnesia-chrome refractory at 1573 K (1300°C) with an oxygen partial pressure of 10 À6 atm were studied and compared with that experienced with calcium ferrite slag under the same conditions. Both slags penetrated the pores in the refractory and caused compositional change in the chromite spinel intergranular bonding phase through cation interdiffusion, which resulted in cracking and debonding of periclase grains. It was observed that the refractory was penetrated much more deeply by calcium ferrite slag than FCS slag because of the higher surface tension and lower viscosity of calcium ferrite slag. As a result, the refractory was attacked less by FCS slag than it was by calcium ferrite slag. It is concluded that the use of FCS slag in continuous copper converting is likely to extend refractory life.
Journal of Applied Electrochemistry, 1996
ABSTRACT The oxidation reactivity of arsenopyrite FeAsS in dilute acid determines the recovery of... more ABSTRACT The oxidation reactivity of arsenopyrite FeAsS in dilute acid determines the recovery of gold from arsenopyritic gold ores by slurry electrolysis. Stoichiometric,sulfur- and arsenic- deficient arsenopyrite have practically the same oxidation rate. Arsenopyrite is covered with a metal deficient sulfide layer which appears to determine the restpotential of the electrode. This layer can be separately oxidized and reduced during bulk-oxidation of arsenopyrite. Arsenopyrite oxidation is accelerated by dissolved Na2SO4 and by high electrode potentials and solution acidity. The rate is controlled by a surface reaction with an apparent activation energy of 33kJmol–1.
Hydrometallurgy, 1992
Aqueous stability diagrams are frequently used to assist in interpreting the chemical mechanism o... more Aqueous stability diagrams are frequently used to assist in interpreting the chemical mechanism of many hydrometallurgicai systems. It has been found that, for multi-element diagrams, when chemical species containing more than one element, other than oxygen or hydrogen, are stable, more than one diagram is required to describe the system. The structure of multi-element diagrams was found to be primarily dependent on restrictions placed on the relative quantities of the component elements. The restrictions are determined by the stoichiometry of stable, multi-element species. Aqueous stability diagrams, calculated by the CSIRO-Monash Thermochemistry System for the iron-sulfur-water system at 523.15 K, and including a representation of the pyrrhotite solid-solution phase, are used to illustrate these features. Use of these diagrams in tlae interpretation of the mechanism of hydrometallurgical processes is discussed.
Fluid Phase Equilibria, 1993
Canadian Metallurgical Quarterly, 1991