Michael Mooiman

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• Doctor of Engineering
• Professor at Franklin Pierce University

The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium–ion batteries. With an official 2017 production of 64 kt, the Democratic Republic of Congo produces more than half of the world’s cobalt. African Copperbelt operations have traditionally focused on copper production; however, it has now...

The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium-ion batteries, which are in widespread use in consumer electronics and increasingly required for electric vehicles. There are limited alternatives to cobalt in these batteries at present. With an official production of 64 000 t in 2017,...

Ion exchange has traditionally been employed for water purification and the removal of metal contaminants from dilute waste streams. More recently, its use in removing trace metallic impurities from hydrometallurgical process streams (with typical background metal concentrations of 50–100 g/L) has increased substantially. It is also used as a prima...

The industry structure, operations, and business transactions involved in the refining of gold- and silver-bearing doré are described. The pyro- and hydrometallurgical processing approaches to refining doré materials are illustrated and compared with those for non-doré materials. In contrast to the refining of industrial precious metals scrap and o...

As energy demand grows, energy efficiency initiatives represent one of the most important ways to moderate increased energy consumption. Botswana in presently engaged at government level in the development of a countrywide Energy Efficiency Plan. This paper serves to review past energy initiatives in Botswana, with a view to understanding successes...

Botswana, with its high solar irradiance levels and vast expanses of thinly populated and available land, has enormous potential for solar power generation. However, the amount of installed solar electricity production in Botswana is surprisingly low. An investigation of the reasons for this situation has been conducted, along with an examination o...

The Mmokolodi Village solar project in Botswana is a 20 kW European and African Union-funded solar photovoltaic installation located near Gaborone. The project is supervised and administered by the Clean Energy Centre at the University of Botswana and is an important first step in implementing small-scale bidirectional solar installations in Botswa...

The precious metals industry differs considerably from those for most other metals and minerals in being driven mainly by the high prices and special properties of these metals. Precious metals (comprising gold, silver, platinum, palladium, rhodium, and iridium) occur rarely in nature and typically in only trace concentrations, requiring complex an...

Ion exchange has traditionally been employed for water purification and for the removal of metal contaminants from waste-waters or dilute streams. In the last 25 years, however, its use for removing various trace metallic impurities from hydrometallurgical process streams (with background metal concentrations typically ranging from 50 to 100 g/L) h...

During the past 20 years, the hydrometallurgist's role in industry has changed considerably. Flowsheet development and technical troubleshooting are now smaller components of the job and, more often than not, issues of operations management, environmental regulations, worker safety, risk assessment, and finances are more important. From an industry...

The demand for high purity precious metals began with certain industrial applications having uncompromising requirements for quality and performance. As industrial uses proliferated and as the jewelry industry became increasingly sophisticated, the demand for high purity gold has reached the point where 99.99% is now the standard in the marketplace...

The paper focuses on the application of hydrometallurgy to the recovery of valuable or toxic metals from waste materials, the production of inert wastes, and the cleanup or remediation of contaminated sites. As the field of hydrometallurgy or aqueous processing broadens, it is worth considering the application of aqueous solutions and chemistry in...

Reviews of aqueous processing in JOM have traditionally focused on hydrometallurgical process routes. This article, however, addresses the application of aqueous processing in materials engineering and presents some promising developments that employ aqueous-based routes for the manufacture of high-tech components and specialty products. Such appli...

The chemistry of gold extraction from alkaline cyanide solution by solvating extractants, particularly TBP and DBBP, is described. Undiluted TBP is an effective extractant for gold at high ionic strengths, whereas undiluted DBBP needs little ionic strength adjustment in order to extract gold. Other alkyl phosphorus esters, phosphine oxides, sulfoxi...

The oxidation of anhydrous CrCl3 pellets is studied in the temp. range 350-630 °C and at mole fractions of O2 between 0.1 and 1.0 using SEM as well as isothermal and temp.-programmed TG.

The kinetic behaviour of anhydrous chromium(III) chloride pellets in oxygen in the temperature range 350–630 °C has been examined by isothermal and temperature-programmed thermogravimetry and scanning electron microscopy. The reaction starts at ca. 400 °C under non-isothermal conditions and exhibits a deceleratory rate. Cr2O3 is usually the only so...

Research efforts have shown that solvation extraction of gold from alkaline cyanide solution is possible by alkyl phosphorus esters. Both tributyl phosphate (TBP) and dibutyl butyl phosphonate (DBBP) appear to be effective extractants for gold and exhibit high loading capacities exceeding 30 gpl. Selective solvation extraction of gold from alkaline...

The concept of amine basicity is discussed and used to explain the selective extraction of gold from alkaline cyanide solution. The apparent basicity of simple weak base amines with respect to Au(CN)2 can be increased as much as 5 orders of magnitude by the addition of organic phosphorus oxide compounds (TBP, DBBP, etc.). It has been shown that the...

The kinetics of the reaction between copper(II) and salicylaldoxime were studied in various ethanol-water mixtures. The rate of reaction was found to be first order in both copper(II) and the neutral ligand. Deviations from this behaviour at low pH can be accounted for if allowance is made for the reverse reaction and for protonation of the ligand....

Amine extractants, regardless of structure, have been of limited utility for the extraction of complex metallic anions from alkaline solution due to an inability to increase the amine's basicity. This situation is contrasted to acid extractants in which case such control of extractant strength is possible. Recent studies with amine extractants have...

It has been discovered that gold can be extracted from alkaline cyanide solution with primary, secondary, and tertiary amines by adding certain Lewis base modifiers, such as organic phosphorus oxides. Under these circumstances, gold can be extracted at about pH 10, commensurate with the pH of cyanide leach liquors. The selectivity of the amines and...

Summary The relative intensities of the Co–H/D stretching vibrations in the precipitated products show that the reaction of H2 with [COII5]3–(L = CN–) in D2O produces equal amounts of [CoIIIL5H]3– and [CoIIIL5D]3– which, taken together with kinetic and electrochemical data, indicates that H2 reacts with a binuclear [CO2L10]6– ion by heterolytic fis...