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By F. T. Cawood

Despite economic law and policy instruments with righteous intentions, the politics of resource nationalism could render these instruments unworkable. South Africa is a case in point. After the establishment of democracy, the country's outdated law and policy framework was replaced with a modern system, and in many respects an exemplary one. Converting the privately-owned mineral right system into a scheme of state custodianship allowed for several resource nationalism instruments, in addition to a resources royalty structure that first, compensates for the loss of a non-renewable resource; second, provides for optimal resource use through encouraging value addition to mineral production; and third, effectively targets economic rents. However, despite these improvements, the country went through a process of fierce debate on whether or not mines should be nationalized: the debate was fuelled by public anger with claims of political non-delivery. The result was considerable noise because of public unawareness of facts and distortion of the facts in political rhetoric. The purpose of this article is, first, to establish the status of resource nationalism in South Africa's mineral and fiscal frameworks; second, to give an opinion on the findings of the African National Congress's document on state intervention (Maximising the Developmental Impact of the People's Mineral Assets: State Intervention in the Minerals Sector (SIMS), 2012); and third, to fruitfully contribute to the fundamental discussion on how South Africans benefit from their mineral riches. The methodology is to start with explaining resource nationalism as an international issue for the extractive industries; then to offer an overview of existing resource nationalism instruments in South Africa-along with their effectiveness in attracting rents and investment. The major finding is that South Africa has resource nationalism firmly ingrained in its current suite of instruments. However, it is necessary to address the perceptions of bad governance, and above all, maintain the stability of the rules governing mineral development in South Africa.

Jan 1, 2013

By R. J. Davidson, M. V. Nkosi, V. Veronsee

When activated carbon is used for the recovery of gold and silver from Witwatersrand gold-plant solutions, severe fouling of the carbon by calcium carbonate is experienced. Also, difficulty is encountered in the retention of the adsorbed silver on the carbon because it is displaced by gold. The acidification of plant pregnant solutions before they are contacted with carbon was therefore investigated as a means of overcoming these shortcomings. The results from batch laboratory experiments on the effect of pH on gold adsorption from plant solutions and from synthetic solutions of high ionic strength indicated reaction rate optima in the region of pH 5 and below pH I. The effect of pH on the equilibrium capacity constant for gold adsorption onto activated carbon was also studied, using both a plant solution and a synthetic solution of high ionic strength. In the case of the plant solution, the results suggested only a marginal change in carbon capacity for gold in the pH range 12 to 6, with significant increases in capacity at lower pH values. In the case of the synthetic solution of high ionic strength, the capacity constant was found to increase steadily as the pH was lowered from 12 to I. It was also found that the gold adsorption capacity of the carbon was significantly better for the synthetic solution. No precipitation of gold from the pregnant solution (gold content approximately 6 g/t) was noted as the pH was decreased to values as low as ,. However, about 25 per cent of the 0,6 g/t silver content was found to have precipitated when a pH value of 3,0 was attained. Further substantial precipitation of silver took place as the pH was lowered further. The investigation was extended by the passing of suitably acidified gold-plant solutions through one or more columns containing activated carbon. Preliminary results showed that the particle size of the carbon had a significant effect on the rate of gold adsorption. No displacement of adsorbed silver by gold was observed to take place at an influent pH of 5. In a typical continuous 'merry-go-round' operation involving three columns in which gold was eluted from the lead column every 48 hours, effluent values averaging 0,001 g/t gold could be consistently achieved under simulated plant-operating conditions. The results were obtained at relatively high velocities of influent solution, resulting in very little hold-up of gold in the carbon-recovery circuit. More than 99,9 per cent of the gold and more than 99,8 per cent of the silver was recovered in the adsorption circuit, while the elution data indicated an average elution recovery of 99,8 per cent of the adsorbed gold and 98,2 per cent of the adsorbed silver. Elution of the carbon was carried out at 91 QC. This involved pretreatment of the carbon with a sodium cyanide solution, followed by elution with deionized water. At a loading flowrate of 66 bed volumes per hour, the indicated take-up of metals on the carbon in the lead column was as follows; 53 k g/t gold, 6 k g/t silver, 57 k g/t copper, 14 k g/t nickel, and I k g/t zinc. Only a trace of cobalt was adsorbed. At an elution rate of 1,7 bed volumes per hour, the lead column was found to be completely stripped in under 5 hours, with concentrations of gold in the eluate reaching 6 to 7 g/l. Besides the excellent adsorption and elution results obtained when acidified pregnant solution was used, no fouling of the carbon was indicated, and the pressure drop across the three columns was considered to be well within practical limits. When compared with conventional zinc precipitation, the carbon process would appear to have considerable economic merit, with strong indications that significant savings would be possible both in capital and operating costs. Further pilot-plant experiments, preferably on a gold plant, would be required before a meaningful cost comparison could be made with the existing process.

Jan 1, 1979

The results of small-scale resin-in-pulp pilot-plant investigations at Grootvlei Proprietary Mines Ltd, President Brand Gold Mining Co. Ltd, and Western Areas Gold Mine Co. Ltd are reported. At each mine, a pulp was fed simultaneously to a carbon-in-pulp plant, allowing a direct comparison of the metallurgical performance of the two processes. With the Grootvlei pulp, gold was extracted more efficiently by resin than by carbon owing to the Iow concentration of competing base-metal cyanide complexes in solution. With the Western Areas pulp, the reverse was true because of the high concentrations of copper and nickel in solution. Finally, with the President Brand pulp, resin-inpulp was significantly superior to carbon-in-pulp owing mainly to the inherently slow rate of gold extraction from calcine by activated carbon. Results are presented that show the efficiency of the elution of gold and other elements with a variety of reagents from the loaded resins arising from these three campaigns. At Western Areas, a detailed investigation enabled a preliminary cost evaluation to be made of three techniques for the elution of strong-base resins.

Jan 1, 1984

Cutting strong rock with a drag bit assisted by high-pressure water jets By M. HOOD. B.Sc. Hons. (Min. Eng.). B.Sc. (Mech. Eng.). A.M.I.M.M. (Visitor) Experiments are described that led to the discovery that coherent high-pressure water jets directed immediately ahead of drag bits while they are cutting strong rock reduce the magnitudes of the forces on the bits significantly. Tests were carried out to assess the effects of the pressure of the water jets on bit-cutting performance. The pressure was varied between 10 MPa and 50 MPa, the water flow rate being a constant 30 I/min. Over this pressure range, the force on the bit was reduced to the extent that the depth of cut of the bit was at least doubled with the point of impingement of the jets optimized. Forces on the bit were found to be particularly sensitive to the point of impingement of the water jets relative to the bit. The optimum configuration was found to be with two jets, one directed towards each corner of the bit and impinging on the rock approximately 2 mm ahead of the leading edge of the bit. Experiments in which a drag bit and high-pressure water jets were used to cut strong abrasive quartzite in the underground mining situation have demonstrated a potential increase of up to five times in the average depth of cut due to reduction of the forces on the bit. The results from the underground tests indicate that the life of the bit is improved significantly - by a factor of approximately two - when highpressure water jets are used.

Jan 11, 1976

By D. Farrow

Future development of kimberlite mines is now focused on mining at deeper levels. The consequences are increased difficulty and costs of the mining operations. The decisions on investments require accurate resource evaluation and quantification of the risk. In the decision process the first step consists in choosing the number of boreholes sampling the pipe relative to the level of uncertainty that can be accepted. The uncertainty in the volumes of rocks of different types can be assessed as soon as we can estimate these volumes from a given borehole layout and calculate the error by means of its variance for instance. In theory this can be achieved by using geostatistical techniques (‘transitive theory’), but in practice the calculation of the error on volumes can be achieved in very particular cases, assuming some regular sampling patterns. A different approach has been chosen based on simulations, giving maximum flexibility to reproduce the reality of the sampling procedure. The idea is to simulate the geometry of several ‘possible’ pipes with their internal geology and estimate them by kriging. Several experimental errors are obtained on which risk analysis can be performed. The aim is to find a feasible method to perform the simulations with reasonable chance to correctly represent the reality, without data on the pipe extension. The methodology applied is based on some hypotheses that can be assessed by the geologist as well as by the geostatistician. The procedure assumes a geological model based on current knowledge including appropriate geostatistical variation. What make these simulations specific and powerful in this case comes from the fact that the boundaries between the different rock-types can be simulated using a transformation of the real 3D space into a 2D space defined by means of polar coordinates. Ultimate transformations to account for smoother variations with morphological transformations allow the generation of realistic pipe geometries on which sampling pattern can be used to evaluate the estimation errors. By estimating the simulated pipe geometries with different boreholes layouts a risk curve expressing the uncertainty in the volumes of the different rock-types versus the number of holes can be developed.

Jan 1, 2003

By G. Mitchell

Much debate has ensued over the past few years on the speed of transformation in the mining industry. By transformation is meant the degree to which the industry has met the requirements of the Mining Charter. In response to this, the Department of Mineral Resources (DMR) commissioned a research study in 2009 to ascertain the degree of industry compliance. The mining industry in response made a presentation to the Minerals Portfolio Committee in Parliament in 2011, during which it released aggregated figures on industry compliance to the Mining Charter. The conclusions of both of the studies are widely divergent. It is argued in this paper that both processes are flawed. The government-sponsored research is empirically and methodologically weak and the results therefore have to be taken with a great degree of caution. The Chamber of Mines figures, on the other hand, while faithful to the reporting of the Chamber member companies, do not represent the entire span of the industry but only the larger mining companies. It is further argued that in order to ascertain a true reflection of the industry an independent audit be undertaken using recognized social scientific survey methods.

Jan 1, 2013

Scrap printed circuit boards were selectively smelted at 1 200°C to produce a metallic alloy having three phases. These phases were identified as a lead-rich phase, a low tin content alpha bronze phase, and a high tin delta phase. Electrochemical leaching studies on this alloy were done in 1 mol/dm3 sulfuric acid or in 2 mol/dm3 hydrochloric acid (adjusted to an ionic strength of 3 mol/dm3). The lead rich phase was more strongly passivated in sulfate media, and in this medium the high tin content delta bronze was more resistant to corrosion than the lower tin alpha bronze phase. In chloride medium the lead phase and both bronze phases corroded readily, but with current densities about an order of magnitude lower than in sulfate medium (static conditions) for the bronze phases. The high tin delta bronze phase was found to form a passivating layer in sulfate media. A similar layer was not seen in chloride medium. The leaching studies in sulfate medium also showed the existence of an alpha bronze phase of lower tin content in the centres of the alpha phase grains. This phase was quite resistant to leaching in sulfate medium.

Jan 1, 2009

By G. J. Krige

The extent of ground movements and stress concentrations in the vicinity of the reef in the deep mine-shafts used in the South 4frican gold-mining industry have led to the requirement that special tower structures be developed to span the reef intersection zone in several new shafts. So that structural engineers are able to design these towers, it is necessary to model the dynamic behavior of conveyances traversing them in some way, to provide a means to determine the magnitude of the forces generated. This paper describes the development of two such procedures. The first is a numerical method, utilizing a step by- step integration technique to track the motion of a conveyance through a tower. This technique has been implemented in a computer program, and some results are given.

Jan 1, 1995

Blasting in a gold mine has to satisfy the following set of techno economic conditions: good fragmentation, minimum stopped width, minimum number of rock falls, cost effectiveness. Results of a comparative study of the performance of a Low Density Anfo (LDA) and a conventional Anfo (ANFEX) are discussed. LDA appears to be more cost effective. The same borehole volume can be charged with material of reduced specific gravity. The velocity of detonation (VOD) is increased in the case of LDA resulting in more breakage as a result of shock energy than from the energy in the gas phase. This leads to less damage to the excavation and more favourable breakage of the excavated rock. As a result the overall economics of the mining operation is improved.

Jan 1, 1995

By J. Levin, I. J. Corrans

Wet high-intensity magnetic separation (WHIMS) for the concentration of gold and uranium was tested on many Witwatersrand cyanidation residues, and on some ores and flotation tailings. The results varied, but many indicated recoveries of over 60 per cent of the gold and uranium. The main source of loss is the inefficiency of WHIMS for material of smaller particle size than 20fLm. The recoveries in the continuous tests were lower than those in the batch tests. The continuous tests indicated an operational difficulty that could be experienced in practice, namely the tendency for wood chips and ferromagnetic particles to block the matrix of the separator. It was decided that a solution to the problem lies in the modification of the separator to allow continuous removal of the matrix for cleaning. A system has been developed for this purpose and is being demonstrated on a pilot-plant scale. Promising results were obtained in tests on a process that combines a coarse grind, gravity concentration, and WHIMS. In the gravity-concentration step, considerable recoveries, generally over SO per cent, of high-grade pyrite. were obtained, together with high recoveries of gold and moderate, but possibly important, recoveries of uranium. A simple model describing the operation of the WHIMS machine in terms of the operating parameters is described. This should reduce the amount of empirical test work required for the optimization of operating conditions and should provide a basis for scale-up calculations. The economics of the WHIMS process is discussed.

Jan 1, 1979

By M. R. Khalesi, S. Arfania

"Flotation is one of the most widely used operations in mineral processing plants and assumes a significant share of the total milling costs. The purpose of this paper is to introduce a new set of capital and operating cost models for major flotation machines based on the application of single (SRA) and multiple regression analysis (MRA). Thirty-seven major flotation machines were analysed for this purpose. Depending on the machinery type, different technical variables such as diameter, required air flow rate, required floor space, cell volume, required air pressure, and power were considered as predictor variables, individually (in SRA) or simultaneously (in MRA). Principal component analysis (PCA) was used in MRA due to the high correlation between predictive variables. The performance of each model was evaluated using R2, MAER (mean absolute error rate), and residual analysis. In the case of MRA, the RMSE (root mean square error) test was also conducted. Maximum obtained MAER of 13.5% and minimum R2 of 0.86 indicated that these models could be applied as credible tools in estimation of capital and operating costs of flotation machines for design and feasibility studies.IntroductionMineral processing is a vital part of mining projects and mainly involves comminution, sizing, concentration, extractive metallurgical processes, and dewatering. Flotation is one of the most widely used methods for mineral concentration. Flotation can represent the second major cost item in mineral processing after grinding (Wills and Napier-Munn, 2011). Accordingly, it is a main concern of mining project managers to select and optimize flotation circuits in order to decrease costs and increase productivity. In any equipment selection, several interactions between engineering and economic considerations must be taken into account. Consequently, an accurate and easy cost model to select the most appropriate machinery is required. Moreover, cost models could be used in flow sheet simulations applied in design and optimization. Models of unit operations built into the simulators could be improved by linking the equipment cost models (Khalesi et al., 2015)."

Jan 1, 2017

By J. Rowe

The attrition of activated carbon, and the loss of gold associated with it, is of significant economic importance to the operation of a CIP/CIL circuit The focus of this study was on activated carbon recovered from an elution circuit which was deemed too fine for reuse. Results of cyclosizer and laser particle size analysis identified that most of the carbon was contained in the larger size fraction suggesting formation by abrasion. Digestion and AAS analysis of the individual size fractions identified a disproportionate concentration of gold in the finer size fractions which was identified by scanning electron microscopy to be due to the presence of fine metallic gold formed as a result of the acid washing process. Attempts to strip the remaining gold using sodium hydroxide or sodium sulphide based solutions proved unsuccessful due to poor elution efficiencies and re adsorption of gold. Upgrading of the material by froth flotation was also investigated using various conventional flotation reagents which had some success in concentrating the free metallic gold, however, grade and/or recoveries were considered less than desirable. Greater success was ultimately found in the transfer of gold from the fine carbon material onto coarser virgin activated carbon using a caustic cyanide solution. Sodium sulphide, sodium chloride and ammonium chloride based solutions were also trialled but proved less successful owing to their inability to mobilise metallic gold or gold cyanide species. Repetition of the transfer process proved capable of stripping 97% of the gold contained on the carbon fines for abed volume ratio of 6:1.

Jan 1, 2009

By J. A. L. Napier

The application of excess shear stress as an aid to the design of mine layout is reviewed, and the critical parameters required to describe slip on a plane of weakness are noted. A design procedure that is required to model the cyclic build-up of excess shear stress is described. A number of simple examples of mine layouts on two reef planes intersecting a fault plane are then considered to illustrate the application of the design concept and to highlight some of the pitfals that may be encountered

Jan 1, 1987

By S. L. Miller

The development of a pilot gold geostatistical ore reserve system proved that geostatistical methods worked well for the routine production of annual ore reserves on gold mines of the Gold Fields of South Africa (GFSA) group, and that the techniques could also be practically implemented, understood and accepted by Survey Department personnel. Many side benefits of the pilot system became apparent, and a variety of useful management information was provided by manipulating the data values that were already captured. It was decided that it was a priority computing project to develop a standard production system (GORS) for routine use by all the GFSA gold mines. Experience with the pilot system enabled detailed functional specifications for GORS to be laid down. These, together with group computing policy determined the terms of reference and constraints for the GORS development. System design could not be finalized until new and appropriate mainframe database software and graphics workstation equipment and software had been found. With these in place the basic system was structured to take best ad- vantage of the interactive features of the workstation, the number-crunching power of the mainframe and the flexibility offered by a relational database and associated 4GL tools. Application sub-systems were developed for data capture, statistical applications, geostatistical calculations, contour plotting and graphical queries. GORS is being introduced to the mines in a phased manner with suitable documentation, training and support structures to enable it to be routinely and effectively used on a day-to-day basis by all group gold mines.

Jan 1, 1987

By O. S. Tinkler, K. C. Sole

"Although the first large-scale application of copper recovery by solvent extraction took place in Zambia in the early 1970s, it is only in the last decade that this technology has become widely employed in this part of the world and is now a mainstay unit operation in copper hydrometallurgical flow sheets. The mineralogy of the ores of the African Copperbelt, and hence the characteristics of African leach liquors, differs significantly from those in Chile and the southwestern USA, where copper solvent extraction has had a long and successful history. These differences provide operators, metallurgists, reagent vendors, and engineers with many challenges: new approaches are needed to adapt solvent-extraction technology for successful implementation in this region. This paper examines typical operating practice in the African Copperbelt, discusses differences compared with other parts of the world, and looks at some of the challenges and opportunities presented by these flow sheets. IntroductionFollowing the success of the Rancher’s Bluebird and Bagdad solvent extraction and electrowinning (SX–EW) operations in Arizona in the late 1960s, the Tailings Leach Plant at Chingola, Zambia, became the first large-scale copper SX plant in the world, commissioned in 1974. Despite the equipment design now being outdated, this plant still continues to operate successfully, indicating the versatility and adaptability of this technology. Today, there are some 75 copper SX operations worldwide with cathode production above 10 kt/a. The top ten producers currently account for about 40% of the global 4.3 Mt/a SX–EW copper production. South America (predominantly Chile and Peru) is the largest copper cathodeproducing region, with annual production of some 2 Mt. The Central African Copperbelt (Zambia and the Democratic Republic of Congo (DRC)) is second, with cathode production of 1.2 Mt/a, and North America (USA and Mexico) third, producing close to 0.8 Mt/a Cu (Solvay Cytec data, 2014). The remaining 0.35 Mt/a comes from all other regions combined (referred to as ‘Rest-of-World’)."

Jan 1, 2016

By R. Ciccu

This paper examine the optimization of a beneficiation plant for recovering marketable barites from crude ores of different characteristics. The plant, part of a mining complex in Sardinia, consists of a jig section integrated with a flotation line. The problem has been studied using a suitable model of the process, based upon experimental and field data pertaining to both the characteristics of the feed material and the performance of machinery. Data have been automatically processed with the aid of a computer to find the optimum setting of each section, in order to maximize profit for each kind of ore separately fed to the plant. Moreover, the advantages of blending the various concentrates - not all of them individually marketable - are also demonstrated. The overall economic result can be improved provided suitable proportions of each kind of ore are fed to the plant. Such information is fundamental for the long-term planning of exploitation of available reserves, and provides guidelines for further prospecting. The paper illustrates the washability characteristics of the ore's and describes in detail the model adopted. The results of data processing are then presented in the form of computer graphs and discussed. Finally, conclusions are drawn regarding the advantages of resorting to Operations Research as an aid to management.

Jan 1, 1987

By R. Haldenwang, R. Erasmus, P. T. Slatter, R. P. Chhabra

Notches are used routinely for measuring the flow rate of water with free surface flows. As far as can be ascertained, no work has been done to investigate the performance of these flow rate measurement devices for non-Newtonian suspensions. The Flow Process Research Centre at the Cape Peninsula University of Technology has investigated the flow rate of kaolin and bentonite suspensions from a tank for two notch shapes, namely rectangular and triangular, and for 3 different concentrations of each suspension. The notches were calibrated using water and then the kaolin and bentonite suspensions were tested in them. The rheological characterisation of the fluids was done with a Paar Physica MC-1 rotary viscometer fitted with a cup and roughened bob. Analysis of the results shows a significant increase in discharge coefficient with increase in concentration, and the discharge coefficient has been correlated to the yield stress. This is the first such study, and further investigation is needed to confirm and extend these findings.

Jan 1, 2007

1. Reviews Extraction metallurgy, by J.D. Gilchrist. 3rd ed. Oxford, Pergamon, 1989. 431 pp. £50.00 (hard cover), £14.95 (soft cover). Reviewer. Prof. M.D. Brayshaw. Reviewer. Prof. M.D. Brayshaw This third edition bears testimony to a work that contains much of value for lecturers, students, and practising metallurgists. Mineral processing in the United Kingdom, edited by P.A. Dowd. London, Institution of Mining and Metallurgy, 1988. 223 pp. £25.00. Reviewer: Prof. M.D. Brayshaw It came as both a pleasure and a challenge for a resident of South Africa (with its volume and diversity of minerals) to review a book focusing on the beneficiation of ores from the sparsely endowed mineral chests of the United Kingdom. 2. Recent issues Rock mechanics. Theory and applications with case histories, by W. Wittke. Translated from German by R. Sykes. Berlin, Springer-Verlag, 1990. 1076pp. DM248. McGregor's quick reference to the JSE. Pretoria, Juta & Co., 1990. R39,95. McGregor's economic alternatives. Pretoria, Juta & Co., 1990. 400 pp. R34,95. 3. New journals Journal of Materials Chemistry, edited by A.R. West and J. Leader, and published two-monthly by The Royal Society of Chemistry (Blackhorse Road, Letchworth, Herts SG6 IHN, OK). £195 per year, starting in 1991. New Materials World, published monthly by Lawrence Cooklin (15 Selvage Lane, Mill Hill, London NW? 3SS, OK). £180 per year. Mendeleev Communications 4. Books from The Institute of Metals The following were published recently, or are to be published soon, by The Institute of Metals, 1 Carlton House Terrace, London SWl Y SOB, OK. Illustrated case histories of marine corrosion. 1990. Modern steelmaking methods, by C. Moore and R.I. Marshall. 2nd ed. 1990. Grain boundary fractures, by S.F. Pugh. 1991. 160 pp.

Jan 1, 1991

"Chairman: Professor B. W. MacKenzieRapporteur: Professor D. A. PretoriusPapers:Optimum spacing for soil sample traverses by W. A. HodgsonEvaluation of geochemical data by C. J. LenzResearch in oil exploration decision-making by J. W. Harbaugh and A. Prelat A drill hole data bank by M. R. AndertonOre reserve estimation and depletion planning for a beach diamond deposit by M. M. OosterveldIn opening the session, the Chairman indicated that the papers and discussions would revolve about quantitative methods of analysis and optimization of various aspects of exploration planning. The five papers would cover a wide range of topics within a general theme of exploration analysis, and it would be appropriate, therefore, to present the. papers as representing a sequential information-gathering process, namely, (i)geochemical and geophysical types of surveying for the location and identification of anomalous zones, (ii) tren¬ching and drilling of the anomalous zones found, and (iii) further refinement of the data for ore reserve calculations and production planning.The first paper, which was presented by Dr W. A. Hodgson, dealt with the optimum spacing between soil sample traverses conducted during geochemical prospecting. The theme of the paper was that the critical sampling interval should be based on the concept of element continuity, and that this interval could be determined by means of a correlogram. Ensuing discussion concerned the probability of the method, designed for areas where dispersion was high, working in localities where dispersion was either low or virtually non-existent. In the latter eases, specific orientation surveys for varying topographic, climatic and geological conditions would possibly be more useful than the preparation of correlograms. A further suggestion was made that cost versus risk should be taken into consideration when deciding upon the spacing between traverses. A balance could be struck by mathematical optimization. If the exploration budget was fixed, then the variance of risk could be minimized.The second paper was a short contribution by Mr C. J. Lenz. Computer-based plotting and evaluation of geochemical prospecting results were carried out because the low cost of analysis in Rhodesia permitted very large volumes of data to be accumulated in mass-coverage operations. Anomalous areas were demarcated within different environments by selecting probability or population boundary values from frequency distributions. In the short discussion which took place it was debated whether the method should be used only in the early high-risk stages of geochemical exploration and whether the introduction of geological bias could influence the actual results of an exploration program."

Jan 1, 2014

By J. T. M. Amphlett, C. A. Sharrad, M. D. Ogden, R. I. Foster

"A renewed interest in nuclear power around the world in order to reduce greenhouse gas emissions is going to increase demand for uranium as fuel. This will result in more uranium being mined, which will in turn increase associated environmental pressures, such as fresh water use. A move to lower quality waters containing impurities such as chloride would help alleviate these pressures. In this work, we determined the uptake characteristics of weakly basic anion exchange resin Ps-EDA towards uranium from saline solutions in a dynamic flow column. Breakthrough curves were produced, with suppression of uptake being observed for chloride concentrations above 5 g L-1. Calculated resin saturation capacities at zero and 5 g L-1 chloride are comparable with literature values for strong-base anion exchange resins, and exceed those published for weak-base resins up to 20 g L-1 chloride. Data has been fitted to multiple breakthrough models, with the modified dose-response model most effectively predicting uranium recovery. The results show that the ethylenediamine functionality could be suitable for use in future uranium processing flow sheets where a high-saline lixiviant is used. IntroductionIon exchange (IX) is a key technology in the uranium mining industry and is well established for the extraction of uranium from both acidic and alkaline leach liquors (Edwards and Oliver, 2000). It was first employed in 1952 at the West Rand mine in South Africa (Ford, 1993; Taylor, 2016). H2SO4 and Na2CO3 are the most commonly employed lixiviants used to solubilize uranium in acidic and alkaline leach conditions respectively. The chemistry of these systems causes uranium to form anionic sulphate or carbonate complexes, which can be taken advantage of by anion exchange resins.Another major technology for the extraction and purification of uranium from leach liquors is solvent extraction (SX). This technique involves the extraction of uranium from the aqueous phase into an immiscible organic layer. Although this is a commonly used method, there are major drawbacks to it, including the use of large volumes of flammable solvents, solvent loss, phase disengagement, third phase formation, and the production of problematic degradation products (Veliscek-Carolan, 2016). These problems can be circumvented through the use of IX resins."

Dec 1, 2018