Kinetics and thermodynamic parameters for the manufacturing of anhydrous zirconium tetrafluoride with ammonium acid fluoride as fluorinating agent

More than 30 percent of the global demand for zircon (ZrSiO4) is supplied by South Africa. A significant amount of the zircon is exported, and beneficiated products are then imported for industrial applications locally. Beneficiating the zircon locally could have a positive impact on the local market, since zircon is only one of many such cases. Ammonium acid fluoride serves as an alternative anhydrous fluorinating agent for zircon in the synthesis of several metal fluorides1,2. It provides an effective dry fluorinating method and is easier to handle than hydrogen fluoride or fluorine gas. Zircon exposed to extreme plasma temperatures dissociates and becomes more reactive. The reaction of the plasma-dissociated zircon (ZrO2·SiO2) with the ammonium acid fluoride (NH4F·xHF, where x = 1 to 5) forms two main intermediate compounds (NH4)3ZrF7(s) and (NH4)2SiF6(s), the latter decomposing to form volatile products at relatively low temperatures, providing easy separation of the silicon and zirconium compounds. The ammonium zirconate compound decomposes to form zirconium tetrafluoride (ZrF4), which can be further manufactured into zirconium metal, to name but one product. Data on the kinetics of the reaction of ammonium acid fluoride with zircon and plasma-dissociated zircon, combined with the thermodynamic parameters of the reaction, is essential for the development of an industrial process for the production of a precursor for the manufacturing of zirconium metal, namely anhydrous ZrF4. Both the reaction kinetics and reaction parameters will be included in this study, as well as some proof that the reaction proceeds to ZrF4 on a small batch scale. If the exact reaction parameters can be pinned down, a wide spectrum of anhydrous metal fluorides can be synthesized through this fluorination route.Financial assistance from the Advanced Metals Initiative of the Department of Science and Technology through the New Metals Development Network.http://www.saimm.co.za/am2013ai201

Treatment of TRISO-coated particles with CF4 in a low temperature plasma

An alternative recovery method to the mechanical crushing of off-specification tri-structural-isotropic (TRISO) coated fuel microspheres is demonstrated. It is shown that the inert SiC layer can be completely removed by etching with the active fluorine species from an inductively coupled radio-frequency CF4 glow-discharge impinging a static bed from the top, at a working pressure of 1 kPa. At this pressure mass transport does not have a rate limiting role and the chemical reaction itself is rate determining. A treatment time of roughly 4 h is required for the conditions reported hereThe South African National Research Foundationhttp://www.elsevier.com/locate/jnucmatai201

A Framework to Support the Selection of an Appropriate Water Allocation Planning and Decision Support Scheme

Water is becoming a scarce resource in many parts of the world, leading to increased competition amongst water users. Optimized water allocation is increasingly important to balance the growing demand for water and the limited supply of accessible clean water. The literature on water allocation schemes and decision support systems, developed for application in specific water management areas or watersheds, was critically reviewed. Although the literature is rich in studies on the application of a broad range of water allocation schemes, there is a lack of information available on the methodology and process of selecting the most applicable scheme that balances the local realities and requirements of stakeholders while considering the local context with regard to the economic, social and environmental impact of water usage. In this article, a framework is presented that water management practitioners can use to select applicable water allocation planning schemes and associated decision support systems based on the characteristics and requirements of the specific water management situation. The framework was used to analyse the water supply situation in South Africa (SA), taking broader factors into account. Based on this, a generic conceptualized water allocation planning and decision support framework for a typical SA water management area is proposed

The treatment of TRISO coated particles with CF4 in a low temperature plasma

An alternative recovery method to the mechanical crushing of off-specification tri-structural-isotropic (TRISO) coated fuel microspheres is demonstrated. It is shown that the inert SiC layer can be completely removed by etching with the active fluorine species from an inductively coupled radio-frequency CF4 glow-discharge impinging a static bed from the top, at a working pressure of 1 kPa. At this pressure mass transport does not have a rate limiting role and the chemical reaction itself is rate determining. A treatment time of roughly 4 h is required for the conditions reported hereThe South African National Research Foundationhttp://www.elsevier.com/locate/jnucmatai201

Soft Sovereignty, Rising Powers, and Subnational Foreign Policy-Making: The Case of India

Published online: 21 Jan 2015The rise of 'new powers' in international politics has been frequently associated with a re-emergence of traditional notions of sovereignty as a backlash against the weakening of nation-state sovereignty related to globalization. We argue that the coexistence of these trends has led to new forms of 'soft sovereignty'. Soft sovereignty means that rising powers both gain and lose authority: From above, their freedom from interference within the international state system is strengthened due to their new status and influence. At the same time, rising powers’ governments are losing authority due to the rise of a multiplicity of sub and transnational actors from below. We apply the concept of soft sovereignty to the analysis of foreign policy-making in India as a least-likely case of a weakening of sovereignty from within a sovereignty-oriented rising power. The analysis of India's relations with Bangladesh and Sri Lanka reveals the huge impact that subnational governments have had on India's policies towards its South Asian neighbours over the past years. The dynamics observed in the case of India reflect many of the traits of current globalization processes, from regionalization to identity politics to the multiplication of actors in the conduct of foreign politics