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This paper presents the latest developments in the flotation model being developed collaboratively between the Julius Kruttschnitt Mineral Research Centre in Brisbane, Australia, and the Mineral Processing Research Unit of the University of Cape Town in South Africa as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. It includes: - characterisation of flotation cells using the bubble surface area flux, Sb; - relationship of Sb to the overall flotation rate constant; - determination of the froth recovery factor; - evaluation of ore floatability; - modelling of entrainment - development of the Floatability Characterisation Test Rig (FCTR); - use of the model in design and optimization of flotation plants; and - current and future work.

Jan 1, 1999

By W. G. Pariseau, S. C. Schmelter

The destabilizing effect of water pressure on rock-mass stability is examined quantitatively by the finite element method. A coupled code that accounts for the simultaneous effects of rock-mass deformation and transient fluid flow is used for this purpose. The traditional soil-mechanics assumption of an incompressible fluid is shown to be untenable for the analysis of porous, fractured rock slopes. A Mandel-Cryer effect, whish is a transitory but elevated and potentially destabilizing water pressure following a cut, was not observed.

Jan 1, 1999

By B. M. Ghadiali, J. B. Putnam, T. P. Smirnoff, M. A. Elioff, P. F. Ryan

Geotechnical investigations for the Mid-City Extension of the Los Angeles Metro revealed high concentrations of toxic hydrogen sulfide (H2S) gas as well as methane. Testing techniques employed to determine the extent of gasses, and to identify potential treatment measures, included gas sampling with cone penetrometers and soil-gas extraction with air injection testing. A gas reservoir model was developed to predict inflows into excavations. Other studies included a hazard evaluation and a general data search for other H2S occurrences and geologic conditions that could facilitate the accumulation of H2S. The paper describes the investigations and proposed design and construction alternatives.

Jan 1, 1995

By Nikolay M. Sirakov, Michael L. Feves, Rumen P. Mironov, Daniel R. Hack

Subsurface investigation of sand and gravel deposits has generally been limited to test pits and borings. These techniques are problematic in terms of the accuracy, usability, and cost of the final data. Innovations in the application of geophysics have been gaining acceptance in the aggregate industry, especially to determine depth to bedrock and the extent of uneconomic inclusions. This paper presents a system to optimize the processing and evaluation of electrical resistivity data. The system uses 3D separation, geometrical reconstruction, and visualization of subsurface objects.

Jan 1, 2002

By Robert Irvine

Exploration activity for diamonds in Canada has recently experienced a dramatic increase. Disclosure of a diamond discovery exhibiting features of a potentially economic deposit contained in a kimberlite pipe in the Lac de Gras area of Canada's Northwest Territories has sparked substantial interest in-Canada and abroad and has triggered the largest staking rush in terms of area in the history of Canadian exploration. In this paper, we report on the nature and extent of current exploration activity in Canada for diamonds (with special attention to Arctic regions), the results of this activity to date, and the context in terms of current world markets for diamonds.

Jan 1, 1995

By Nora M. Hutt, Kevin A. Morin

One technique for controlling ongoing acidic drainage is to relocate and submerge net-acid-generating waste rock in a lake or water-retaining impoundment. This can lead to the overall improvement of water quality and the reduction In short-term environmental liabilities. A case study of this technique is the Eskay Creek Mine in northern British Columbia. Some findings of the study are: (1) the addition of lime to each truckload of rock, based on its rinse pH, neutralized the accumulated acidity and suppressed the accumulated-metal release, (2) only 10-20% of the dump's neutralization potential had been consumed when acidic drainage appeared, (3) water chemistry in the watershed recovered roughly three years after relocation, and (4) environmental liability was reduced due to the cessation of on-land acidic drainage with no degradation of lake chemistry.

Jan 1, 2000

By A. J. Friedrich

Conveyor belts are designed to go unnoticed. When they work well, they attract little attention. When they are not doing the job right, it is noticeable, and they need to be fixed immediately. Vulcanising contractors compete for the maintenance of belts in mining/quarrying and general materials handling worldwide. Damage repair is approached in similar fashion. The damaged section of belting is normally cut out and discarded, and the belt re-spliced using hot vulcanising, Cold splicing, or mechanical fasteners/clip joints. However, there is a cost-effective alternative, alleviating the need to remove damaged sections which are often perfectly recoverable. This is the use of cold-curing repair resins and adhesives.

Jan 1, 2000

By M. Noaparast, F. Woodcock, A. R. Laplante

A novel methodology for estimating gold recoveries in gravity-separation circuits is presented. The methodology makes use of a population-balance model. The model represents gold liberation, breakage and classification behavior and applies preconcentration and recovery performance curves to gravity-recoverable gold. The derivation of the necessary parameters is explained and demonstrated using data from an actual gravity circuit and from a projected application. The methodology makes it possible to estimate the performance of a gravity circuit having a large gold circulating load and a relatively-low unit recovery (e.g., a jig) or having a high recovery on a bleed of the circulating load (e.g., a Knelson Concentrator).

Jan 1, 1996

By M. A. Cristovici

The use of surfactants as wetting agents to suppress sulfide ore dust has been investigated. Numerous surfactants were examined to determine their characteristics and to investigate their ability to improve the wetting of the sulfide ore dust. However, the surfactants selected as suitable dust suppressors proved to have a negative effect on the flotation of ore contaminated with such reagents. A method was developed to eliminate the detrimental influence of dust-suppressing surfactants. It consisted of surfactant adsorption on activated carbon and separation of loaded carbon prior to flotation. The technique is simple and requires minimal changes in the plant flowsheet.

Jan 1, 1992

By Jay Hilary Kelley

A ventilation system is described using dual aircourses: one zone occupied by working personnel, the other at the active working face. The two zones are separated by a partition or Shroud. The occupied zone to the rear of the face zone is ventilated adequately but with considerably less air because little gas, dust, or fumes are present. The face excavating zone is sealed and maintained at slightly more negative pressure preventing dust and gas generating from within to escape. Explosive mixtures within the face zone is rendered non-explosive by the introduction of inert gas therein. Each zone is vented separately to the outside of the mine. Because less total quantity of air is required for human breathing, etc, the total ventilation system can be drastically reduced in tan capacity, development entries, and air shafts, -- a great savings in costs.

Jan 1, 1991

By Chris Chmura, Ketut Karmawan, Ian J. Duckworth

P.T. Freeport Indonesia operates a mining complex located in the highlands of West Papua, Indonesia. Present production from PTFI’s DOZ Underground Block Cave Mine is approximately 40 thousand tonnes per day (ktpd). This paper describes the design process and recommended ventilation infrastructure necessary to expand the DOZ Mine reserves and to increase sustained daily production above 50 ktpd. The enlarged footprint will feature longer production panels of up to 650 m in length, more active draw points, a second large gyratory crusher, and additional men and mobile equipment. The increased ventilation capacity will be achieved through the development of new, dedicated ventilation drifts, and primary Underground exhaust fans.

Jan 1, 2005

By William Wraith

The availability of computer resources and data management technology, together with the prudent use of scientific management concepts, has made it possible to achieve important improvements in the control of maintenance and materials activities in the mining and minerals processing organization. The introduction of minicomputers and. the greatly improved efficiency of computer systems in general have put the use of computer technology within the reach of even the smaller mining companies which probably could not have afforded them just five to ten years ago. A number of progressive companies have implemented computer-based maintenance, purchasing, and supply inventory control systems. Using modern safety stock, demand forecasting, parts reliability analysis, and other control concepts, these new systems have helped minimize production losses by reducing the frequency and severity of supply shortages and unplanned repairs. At the same time, these systems are helping to conserve scarce capital resources by better utilization of supply inventory investments, reduced expenditures for maintenance, less frequent equipment replacements due to improved maintenance reliability, and greater capacity utilization of existing facilities.

Jan 1, 1979

By Donald P. Spitzer, Peter V. Avotins

The flow properties of thickener underflow slurries can be characterized by their rheological parameters. Most of these slurries exhibit Bingham plastic behavior, characterized by a yield stress, to, and a Bingham viscosity, nB. Red mud is generated as a leach residue in the Bayer process. The use of new Bayer process flocculants which contain hydroxamate functional groups leads to muds which are qua1itatively considerably more fluid than muds generated with conventional polyacrylates or acrylatefamide copolymers. A variety of rheological tests confirm lower yield stresses and less extended floc structures with the new flocculants, at the same solids levels. Conversely, under given viscosity restraints, the new polymers make it possible to operate at higher solids levels, which offers major benefits in processing red muds.

Jan 1, 1992

By E. Marques Coelho

Cationic flotation of quartz is currently utilized in the concentration of iron ores and the cleaning of phosphate concentrates. The present work deals with depression of quartz in the presence of aluminum aqueous species during cationic flotation. It was established that aluminum species depress the flotation of quartz with an amine, especially under neutral and slightly alkaline conditions. With an amine as the collector, studies of the adsorption (abstraction) of Al species on quartz surfaces, as a function of pH, correlated well with the depression of this mineral. The presence of Al species also enhanced the depressant action of corn starch on quartz. In addition, the sodium salt of ethylenediaminotetraacetic (EDTA) was found to be an effective complexing agent to suppress the depression caused by aluminum ions.

Jan 1, 1992

By K. V. S. Sastry

Pelletization, sintering, and pressure compaction are the most common methods used to agglomerate ore concentrates. Over the last 20 years agglomeration has grown enormously in popularity and has become a standard unit operation in the nonferrous, cement, fertilizer, and ceramic industries. However, it is in the processing of iron ores and the preparation of blast furnace feed that agglomeration is used most and its application has grown fastest (Ball, et al., 1973; and Sastry, 1977). This chapter deals with an account of the current practices and future trends in the application of computers relative to an overview of the process design and engineering considerations of the unit operation of agglomeration.

Jan 1, 1979

By P. K. Davis, B. Gharib

The results of a previous basic study of the flow and design characteristics of hydrocyclones demonstrated that a recovery as high as 99% with a product rating* of 0.95 can be achieved on a batch+ basis with a single, water-only cyclone if it is configured properly. The next logical step was to demonstrate continuous processing of gob for the efficient recovery of coal by means of a laboratory-size demonstration system. A project to design and construct such a single-¬cyclone system was sponsored by the US Department of Energy, which also sponsored the initial study. A recovery of 93% with a product rating of 0.89 was demonstrated. The system design and the data taken are discussed.

Jan 1, 1990

By M. S. Klima, M. Fofana

The use of a laboratory-scale magnetic fluid-based separator for coal separations was examined. A Frantz laboratory magnetic separator was modified by fabricating new pole pieces of the appropriate geometry to provide the proper magnetic field gradients. Two separation chambers, which were constructed of Plexiglas, were designed to fit between the pole pieces. A commercially available, water-based, ferromagnetic fluid was used as the separating medium. The separating density was changed by varying the current intensity of the electromagnet coil. Both batch and continuous separations were made using 0.59 x 0.50-mm and 0.18 x 0. 15-mm coal. The results are compared to those obtained using organic liquids.

Jan 1, 1998

By J. Paraszczak

With regards to the cost and profitability of a mining operation, the performance of the equipment employed is one of the key issues. Cost and profitability depend on, among other factors, the reliability and availability of the equipment. In an attempt to reduce equipment downtime, it is indispensable to collect and analyze reliable data and information on failures and maintenance actions. This paper reviews common problems encountered in this respect, with particular emphasis on the lack of uniform terminology and methodology. Recommendations concerning the standardiztion of reliability and maintainability concepts and measures are given. Regarding the benefits that the latter may bring, the paper concludes with a proposal for an industry-wide initiative in this respect.

Jan 1, 2002

By George A. Lawrence

A new super-large 100 m3 (3500 ft3) pneumatic mechanical flotation cell is now available to meet today's mineral processing challenges. Several innovative design concepts represent a marked departure from conventional flotation cell designs. The radial discharge from the pump action rotor and the overhung vane type stator is contained in a conical bottom round tank with no dead comers. Peripheral launders collect froth overflowing the entire circumference of the tank and these launders are of a hexagonal design permitting cells to be nested together in a honeycomb fashion. The mechanism drive is either a customized right angle gear reducer or a conventional Vee belt drive. Both drive systems are available with an optional variable frequency control system that permits infinite speed adjustment of the rotor in each flotation cell or group of cells. Results of side-by-side comparative testing between three major manufacturers of super-large pneumatic mechanical flotation cells are discussed. These results were obtained at a large copper concentrator in Chile during several weeks of commercial scale testing.

Jan 1, 1995

By I. Iwasaki

Rest potential and linear potential sweep techniques were used to study the cathodic-polarization processes on chalcopyrite, simulating chalcopyrite short-circuited with grinding media in a wet grinding mill. Microflotation tests were carried out to investigate the effect of cathodic polarization on the collectorless flotation of chalcopyrite. It was observed that collectorless flotation of a cathodically polarized chalcopyrite sample could he obtained when oxygen was used for aeration, but not if nitrogen was used. A mechanism for the role that oxygen plays in the collectorless flotation of cathodically polarized chalcopyrite is discussed.

Jan 1, 1999