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By Yanmin Wang, Eric Forssberg

This paper presents recent experimental results in wet ultra-fine grinding and classification of industrial minerals carbonates and kaolin clays using a stirred ball mill and a high performance centrifuge. The studies have been focused on the effect of beads (size, density and load) on the grinding efficiency. The use of chemical additives for the control of slurry rheology in the stirred ball milling is presented. The role of pre-crushing with a high-pressure roller mill on subsequent ultra-fine grinding is discussed for energy saving and size reduction. The use of a disc-stack nozzle centrifuge for ultra-fine classification duties at high solids contents is presented.

Jan 1, 1998

By S. Ouyang

The four most important parameters controlling the flow of as in coal are the gas content, permeability, diffusion coefficient and clear characteristics. Estimates of these and, more importantly, a good knowledge about the variations in their values over time are important for proper simulation of long-term gas production. This paper describes experimental techniques for the estimation of diffusion-coefficient and permeability values, along with their time dependency under simulated in situ conditions. It is shown that the permeability and diffusion-coefficient values are not constant, as they are usually assumed to be. There is a significant variation in their values, probably as a result of changes in the microstructures of coal associated with release and flow of gas. Finally, a technique to estimate clear parameter is presented.

Jan 1, 1997

By B. J. Arnold, F. F. Aplan, R. R. Klimpel, E. C. Jr. Dowling

Residence-time distribution techniques are useful tools in the analysis, characterization and modeling of the performance of processing equipment and circuits. This paper presents the results of both conventional and more-sophisticated residence-time distribution techniques for industrial copper-flotation-circuit data. While conventional techniques provide a description that is sufficient for macroengineering design requirements, the more sophisticated tracer-technique methods give more realistic descriptions of process flows and system effectiveness. It is demonstrated that these approaches can provide highly useful information about different equipment, as well as its configuration and performance.

Jan 1, 2000

By D. H. H. Quon, A. Ahamd, G. Pouskouleli, T. A. Wheat

An outline of the contributions of hydro- metallurgical techniques such as sol-gel processing, direct precipitation and hydro- thermal decamposition for the development of high-quality ceramics is given and examples drawn from recent work on both structural (engineering) and functional (electrical) ceramics are discussed.

Jan 1, 1990

Early experiences suggested autogenous mills were difficult to operate and consumed substantially more energy than conventional rod/ball mill circuits. As our understanding has increased and the technology has matured this perception has changed to the point where most new comminution circuits are ag/sag based. In addition many operators have replaced existing conventional circuits with this technology. The JKMRC has been studying ag/sag mills for over 20 years. During this time it has amassed what is probably the single largest and most detailed data base of pilot and full scale mill operations in the world. This has been used to help develop and refine its cur- rent commercially available mathematical model of ag/sag mills. A decade of its application has greatly helped simplify both design and operation of ag/sag milling circuits as well as helping to promote the effective use of recycle crushing, secondary crushing and closed-circuit operation. This paper describes the development of ag and sag milling in terms of our understanding and the evolution of the technology. In addition the application of mathematical modelling and simulation in designing and operating efficient circuits is described with the aid of practical examples.

Jan 1, 1998

By J de Cuyper, E. J. Parkins, H. L. Shergold, W. Freyberger

The paper is divided into two parts. The first part describes an investigation of the effect of temperature on the conditioning and flotation of an ilmenite ore with a 1:l oleic acid-fuel oil mixture as collector. During conditioning the pulp underwent characteristic changes of flocculation, deflocculation and dispersion which were monitored by measuring the power consumption of the conditioner motor. Optimum flotation results were obtained at the end of the deflocculation period. High ilmenite recoveries were obtained at high temperatures and high concentrate grades at low temperatures. The second part of the paper describes a study of the effect of temperature on the adsorption of oleic acid at the ilmenite/water interface. At high adsorption densities it was chemical and exothermic. Contact angles showed that the hydrophobicity of the collector-coated minerals increased with an increase in temperature.

Jan 1, 1976

By Sergey G. Pushkin, Eugeny L. Schastlivtsev, Anatoly A. Bykov

Three years ago the authors and a group of assistants began to develop a GIs-system for integration of comprehensive eco- logical information to be linked to geographical maps of Kuzbass region. And now we have got the working system and some first results that the present paper deals with.

Jan 1, 1996

By C. B. Manula

The total systems model for underground coal mine planning and design (Master Design Simulator) is a set of computer programs which encompasses a realistic reproduction of the interaction among the geological, environmental, equipment, methods, and the health and safety aspects of the mining plan (Manula, Rivell, and Ramani, 1975). The total system includes nine major subsystems: geology and reserves, methane generator, roof support, subsidence, production, rail haulage, cost, water generator, and ventilation (Fig. 1). The subsystems themselves are divided into two categories based on the frequency with which they are executed: (1) event-oriented subsystems are executed either independently or at discrete intervals when certain specific events occur; and (2) dynamic subsystems function interactively during the production cycle, transferring data to or requesting data from event-oriented subsystems only when specific events occur (Fig. 2). Each subsystem has been tested and validated independently (Ramani, White, and Sutton, 1974; Ramani and Owili-Eger, 1974; Manula, Mozumdar, and Jeng, 1974a; Manula, Mozumdar, and Jeng, 1974b; Manula, et al., 1974; Manula, Rivell, and Sanford, 1974; Ramani, McClay, and Burgos, 1975; Manula and Owili-Eger, 1975; and Ramani, Owili-Eger, and Manula, 1975).

Jan 1, 1979

By J. A. King, D. R. Weir, P. C. Robinson

The complex mineralogy of the Porgera resource has a pronounced effect on process selection for the recovery of refractory gold and silver. Intimate association of gold with pyrite necessitates a high degree of sulphur preoxidation to achieve acceptable levels of gold recovery. Acid pressure oxidation has been demonstrated to be the only commercially proven process capable of achieving the required level of pyrite oxidation. Gangue mineralization dictates preconcentration of the sulphides to limit the acid consuming capacity and carbon dioxide generation during oxidation. However, the relationship between concentrate sulphur grade and gold recovery to concentrate ultimately governs the optimum degree of sulphide preconcentration. Minipiloting of the preconcentration and oxidation stages of the Porgera flowsheet are described. The influence of these processes on subsequent recovery of precious metals together with the technical and economic necessity of concentrate pretreatment prior to oxidation are discussed.

Jan 1, 1987

By J. A. Brierley, C. L. Brierley, K. A. Prisbrey, R. W. Bartlett, J. G. Harrington

Bacterial oxidation of gold-encapsulating sulfide minerals in low-grade refractory ores was investigated over a period of one year. Crushed ore samples were held in wet, bacteria-inoculated, aerated columns. Sulfide mineral oxidation data were correlated with subsequent gold cyanide extractabilities. Experimental results for both sulfide conversion and gold extraction were compared with a biooxidation kinetics model that incorporates rock size, mineral grain size, and heterogeneous pyrite reaction kinetics. Using the model, extrapolations were made over three years for biooxidation of ore in large stockpiles. Ferric ion (oxidant) diffusion in the solution-filled pores of the rock matrix does not control the biooxidation kinetics of ore crushed to -25 mm.

Jan 1, 1993

By T. R. Ellis

Considerable movement is afoot internationally to rationalize standards and regulations relating to valuations and the qualifications for valuation professionals. In July 2000 the International Valuation Standards Committee released expanded standards, and additional important improvements are planned by 2003. Possible updates to the International Accounting Standards (IAS) and potential adoption of IAS by the United States could significantly impact minerals appraisers. Standards designed specifically for mineral asset valuation are under development in Canada and the United States, with Australia's internationally respected VALMIN Code providing the benchmark. In the United States, the all-encompassing Uniform Standards of Professional Appraisal Practice (USPAP) is annually modified and continues to gain deeper acceptance, while the SEC holds fast to its 1981 rule prohibiting reporting of a quantitative estimate and value for non-reserve mineralization. Some important international trade agreements are driving actions to free the trade in professional services. In July 2000, an international workshop was held to initiate discussion on minimum qualifications for appraisers to work internationally. Pressure for uniform minimum qualifications and rules for professionals internationally will continue to build. The United States is historically among the slowest countries to implement such initiatives, with its state level licensure barriers having the potential to cause some of its professionals to be stranded in an international backwater. Structural change is needed in Australia's VALMIN Code to remove conflict with the latest International Valuation Standards. The mineral valuation standards developers of Australia, Canada and the United States should work jointly on updating VALMIN for global use.

Jan 1, 2003

By William C. Larson

The number of uranium in situ leach operations has increased significantly since 1975. As of May, 1980, there were a total of 27 active projects, including 16 commercial scale operations (or under construction) and 11 pilot scale operations. The south Texas uranium district and Wyoming have been the most prominent areas in early field experiments as well as in commercial application of this new recovery technique, although in situ leach tests are now being conducted in Colorado and New Mexico. The growing number of commercial-scale operations is accepted as prima facie evidence that in situ mining now offers a third option along with open pit and underground mining for winning uranium from sandstone host rocks. It is estimated that in 1979 about 9 percent of the nation's total uranium production was from in situ mining. However in situ mining of uranium is not without its environmental controls. The primary emphasis of environmental controls falls into two catagories; namely, control of the leach solutions during mining and demonstration of ground water restoration. Finally this paper briefly reviews the Bureau of Mines research program in uranium in situ mining.

Jan 1, 1980

By L. R. Stoiser

The mineral resource potential of the Los Bronces deposit was successfully evaluated by an intense, coordinated field program over a 37-month period (April 1978 - May 1981). This project was part of a much larger study to determine the economic feasibility of expanding the open-pit, mine-mill operation 10-fold to 80 kt/d (88,000 stpd). The resource project included more than 120 km (74 miles) of core drilling and 64 km (40 miles) of drill rig access way construction under adverse topographic and climatic conditions, detailed geological mapping, and other related activities. The Los Bronces deposit is composed of an earlier mineralized porphyry-type body intruded in part by a large complex of mineralized hydrothermal breccia pipes. The mineralization is hosted by intrusive and extrusive igneous rocks. Various stages of erosion, oxidation, leaching, and supergene enrichment of copper are present. Drill hole indicated geologic reserves are estimated at 1.3 Gt (1.4 billion st), averaging 0.81% copper and 0.016% molybdenum at a cutoff grade of 0.6% copper equivalence decreasing to 0.25% over the life of the mine. Trace amounts of silver are also present.

Jan 1, 1987

By C. E. Roessler

Uranium and its decay series are associated with phosphate deposits of marine origin. Uranium concentrations are on the order of 100 to 200 ppm in matrix from the Bone Valley formation of Central Florida and about 25% this value in matrix mined from the Hawthorne formation in North Florida. Occupational radiation exposure due to this source has been under study in Florida since the mid 1970's (Windham, Partridge, Horton 1976; Roessler and Prince 1978). This report is based on findings of an industry-wide scoping survey conducted by the University of Florida during March 1976 through May 1977 and subsequent studies in selected individual facilities. PHOSPHATE MINING OPERATIONS Mining and beneficiation operations are diagramed in Figure 1. At the excavation site, electric powered draglines remove the overburden and expose the phosphate matrix (ore) which is then slurried and pumped to the beneficiation site. At the washer stage of the beneficiation plant, the matrix is subjected to washing and screening. A coarse product, "pebble" is produced and sent to storage piles while the fine fraction is passed through a series of cyclones to remove the clays. The generated clay suspension is sent to settling ponds while the remaining sand-sized fraction is sent to the flotation plant. At the flotation plant, phosphate particles are recovered from the fine sand particles of similar size through several stages of treatment with reagents, agitation and separation of floating and sinking fractions. The high grade concentrate produced is transferred to storage while the sand tailings are discarded. [ ]

Jan 1, 1981

By Frank F. Aplan, Edward C. Dowling, Richard R. Klimpel

Several series of time-instantaneous samples were taken on a cell-by-cell basis in the flotation circuits of the Pinto Valley, AZ copper concentrator. These samples were used to calculate mass flow rates throughout the circuit using standard, deterministic metallurgical formulae and also a variety of more statistically oriented techniques. Because of the magnitude of the errors associated with the individual cell samples, the standard metallurgical formulae are not sufficient. Consequently, it is necessary to utilize some type of statistical technique capable of distributing the individual cell sample errors in such a way so as to provide a physically useful mass balance for the entire circuit. This paper explores the use of linear and least squares programming as one technique to providing credible mass balance calculations. For linear programming this was done by distributing the error using two different criteria involving specific linear programming formulations: least absolute sum minimization (which assumes an underlying double exponential distribution error structure) and minimax (which minimizes the maximum absolute deviation and assumes an underlying rectangular distribution error structure). These results were then compared to the more standard formulation of minimization of the sum of least squares which assumes an underlying normal distribution error structure. The least absolute sum approach was particularly attractive due to its simplicity of use and the ease in which repetitive calculations can be done with no user intervention.

Jan 1, 1990

By D. Robert Weir

The pioneers in pressure hydrometallurgy have provided a solid foundation during the past four decades. The pressure techniques are now capable of being used to push back the frontiers in the winning of metals. Pressure hydrometallurgy has been used to meet the objectives of extracting metals; purifying metal solutions, recovering metals; and rendering waste streams acceptable for disposal to waste repositories and the environment. Some examples of each of these functions are briefly reviewed. The applicability of pressure techniques to the recovery of precious metals is discussed.

Jan 1, 1985

By [Miroslaw] M. Hajdasinsk

The identification of the real internal rates of return (IRR's) of a project is essential for its economic evaluation. The existing methods for the calculation of IRR's are both cumbersome and unreliable, mainly because of their inability to effectively isolate the real IRR's and incapability of discovering multiple IRR's of even multiplicity. In this paper, a concept of the 'cash flow pattern tree used for isolation of the real IRR's of a project is presented. This concept, combined with the Sturm procedure for counting the real distinct zeros of a polynomial within a specified interval, leads to the development of a method and computer program for isolation and calculation of the real IRR's of a project. The method examines whether or not real IRR's exist, and if they do, isolates them within bounded and narrow intervals in a mathematically founded way. The isolated IRR's, whether simple or multiple, are subsequently calculated either directly or by means of an appropriate approximation procedure. Numerical examples assist the development of the method and the corresponding computer algorithm. Because any Net Present Value treated as a function of interest rate can easily be transformed into a polynomial, the method presented also constitutes a method for finding the real zeros of a polynomial.

Jan 1, 1986

By Michael C. Newbury

For thousands of years gold has been not only a commodity, valued for its comparative scarceness, immutability and homogeneity but also a medium of exchange which has no nationality. Approximately 90% of the gold produced is still accessible in the world, although some of it in museums, galleries, jewellery and dental work is not immediately available for circulation. The majority is held as bars by central banks for their reserves; the balance circulates as coinage or bullion held for investment. The value is further enhanced by the political aspect that gold cannot be debased as paper currency can and, therefore, it always becomes an investment refuge. It has always been possible to buy and sell gold at a price which is readily established by reference to bullion's weight and purity; and it is this fact which makes a loan denominated in gold, rather than one in currency, a viable alternative means of finance. The purpose of this paper is to discuss some general aspects of what is considered to be one of the more effective and presently popular methods of financing the development of a gold mine - the gold loan. This is not intended to discuss all the minute details which must be uniquely designed to fit each individual situation, but rather to provide general guidelines. You will all be aware of the traditional sequence whereby companies primarily finance exploration work by the raising of equity through the sale of shares to the public or by that unique Canadian form.

Jan 1, 1987

By D. Maxton

INTRODUCTION This paper traces the application of High Pressure Grinding Rolls (HPGR) at industrial and pilot scale in Australia. The Argyle Diamond Mine installed the first of two smooth segmented HPGRs during 1990 in an open-circuit secondary-tertiary crushing application to increase throughput. In 2002 a third HPGR was added to improve liberation and so increase the recovery of smaller diamonds. The latest improvements in wear technology (tyre with tungsten carbide studs) were incorporated in the design of this machine. Extensive HPGR pilot-plant trials were undertaken during the 1990s at both the Kalgoorlie Consolidate Gold Mine and the Boddington Gold Mine. The purpose of these trials was to evaluate HPGR as a method to increase throughput, as an alternative to SAG milling, and also to ascertain if downstream benefits existed. One of the challenges for HPGR circuit designers is to translate what occurs at small laboratory and pilot scale into what is likely to happen in a full-scale circuit. Scale-up from pilot machine results is normally recommended by manufacturers. However, such tests need relatively large quantities of material, particularly if meaningful data on wear are to be obtained. Laboratory tests are preferable, as they need relatively small quantities of ore, but may be questioned in terms of how they relate to full-scale operation. Modelling and simulation have played a particularly important role in this respect in Australia. Models are available which have proven to be very accurate at being able to scale throughput and specific energy response from laboratory to industrial machines. More recently, work in Australia has also been done in developing a model which has the potential to scale laboratory wear data as well.

Jan 1, 2004

By A. Pinches, R. Winby, P. J. van Staden, M. K. Rhodes, P. C. Miller

This paper is a progress report on the commercialization of using bioleaching for base-metal concentrates. The paper focuses on bioleach processes for recovering copper from chalcopyrite and nickel/cobalt from pentlandite/pyrrhotite. Data is discussed from pilot-plant trials in which an overall recovery >95% was obtained for the bioleaching of copper from chalcopyrite. The pilot plant was operated in closed circuit with solvent extraction and electrowinning circuits for final metal recovery. For the bioleaching of nickel and cobalt from pentlandite/pyrrhotite, an overall recovery of 97% was achieved. Precipitation routines were used to produce a final nickel/cobalt product. The pilot plants were capable of treating a few kilograms of concentrate per day. Prominent features in the design of a 1-t/day (1.1-stpd) copper-bioleach demonstration plant for the treatment of chalcopyrite concentrate are discussed. The plant, which is now under design, will be constructed and operated based on the results obtained from the laboratory pilot-plant campaigns. Issues of scale-up for the demonstration plant, together with integration into upstream and downstream processing, are also addressed. Independently derived capital and operating costs are presented for a possible commercial plant. These cost studies indicate the principle economic issues in considering the application of bioleaching to the extraction of base metals. The benefits of bioleaching complex concentrates that are not amenable to physical beneficiation and economic treatment by conventional smelting are highlighted. Issues, such as the environmental aspects, that illustrate the benefits of bioleach technology are given.

Jan 1, 2000