A comprehensive copper stockpile leach model: background and model formulation

The first phase in the sign, development and implementation of a comprehensive computational model of a copper stockpile leach process is presented. The model accounts for transport phenomena through the stockpile, reaction kinetics for the important mineral species, oxgen and bacterial effects on the leach reactions, plus heat, energy and acid balances for the overall leach process. The paper describes the formulation of the leach process model and its implementation in PHYSICA+, a computational fluid dynamic (CFD) software environment. The model draws on a number of phenomena to represent the competing physical and chemical features active in the process model. The phenomena are essentially represented by a three-phased (solid liquid gas) multi-component transport system; novel algorithms and procedures are required to solve the model equations, including a methodology for dealing with multiple chemical species with different reaction rates in ore represented by multiple particle size fractions. Some initial validation results and application simulations are shown to illustrate the potential of the model.

A comprehensive copper stockpile leach model: background and parameter sensitivity

The design and development of a comprehensive computational model of a copper stockpile leach process is summarized. The computational fluid dynamic software framework PHYSICA+ and various phenomena were used to model transport phenomena, mineral reaction kinetics, bacterial effects, and heat, energy and acid balances for the overall leach process. In this paper, the performance of the model is investigated, in particular its sensitvity to particle size and ore permeability. A combination of literature and laboratory sources was used to parameterize the model. The simulation results from the leach model are compared with closely controlled column pilot scale tests. The main performance characteristics (e.g. copper recovery rate) predicted by the model compare reasonably well with the experimental data and clearly reflect the qualitiative behavior of the process in many respects. The model is used to provide a measure of the sensitivity of ore permeability on leach behavior, and simulation results are examined for several different particle size distributions.

Healthcare: rejection of privatisation and patient fees in Central Europe

Since 2006, there have been successful campaigns against commercialisation of public health services in the four central European countries – Czech Republic, Hungary, Poland and Slovakia.

Debating the division of labour in healthcare in France and England

As Larson (1990) states, professions are historically specific and ‘there is no pattern of social closure around an occupation that is not inflected by the latter’s past, its specific activity and typical context of performance or…the political context in which closure is obtained.’ Larson’s work focuses particularly on the differences between the establishment of professions in France, where there was considerable state intervention, with that in the US and UK, both of which were more market-oriented. This paper is based on data from an evaluation of a large European exchange programme of staff between Kent and Lille, from 2005 to 2008 and discusses the division of labour in healthcare between two occupational groups, medicine and nursing, in England and in France. This division of labour has been extensively discussed in the UK, particularly since from the mid 1990s the nursing role has been extended and innovations such as nurse prescribing have been introduced, whereas such extended roles have not been introduced in France. The paper draws particularly on interview data from mental health practitioners, in which it is argued that whilst the English nurses may on the surface seem to have a wider range of competences and autonomy, in reality they are more constrained, as they operate under protocols and therefore do not exercise professional judgement. Not only do these data illustrate the centrality of professional judgement in discussions about practice, they also demonstrate the circularity of many debates on extended roles.

Learning and practising supply chain management strategies from a business simulation game: a comprehensive supply chain simulation

An Internet based supply chain simulation game (ISCS) is introduced and demonstrated in this paper. Different from other games and extended from the Beer Game, a comprehensive set of supply chain (SC) management strategies can be tested in the game, and these strategies can be evaluated and appraised based on the built-in Management Information System (MIS). The key functionalities of ISCS are designed to increase players SC awareness, facilitate understanding on various SC strategies and challenges, foster collaboration between partners, and improve problem solving skills. It is concluded that an ISCS can be used as an efficient and effective teaching tool as well as a research tool in operations research and management science. Problems and obstacles have been observed while engaging in the SC business scenario game. The actions proposed and implemented to solve these problems have resulted in improved SC performance.