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By John Mitchell, Mark K. Jorgensen

Newmont Mining’s Ahafo Mine is located in Ghana approximately 300 km (190 miles) northwest of the capital city of Accra in the Brong-Ahafo region. The nearest city is Sunyani, located 45 km (28 miles) to the north. The Ahafo Mine will process ore from seven major pits that extend along a 40-km (25-mile) strike. Four pits are in the south and three pits are in the north. The resource is currently stated at 373 t (12 million oz). But it still has the potential for growth both from new discoveries and the development of underground operations.

Jan 1, 2007

By B. M. Nyombolo

Mintek has been involved in the development of bioleach technology for many years, initially for refractory gold extraction, and more recently also for base metals extraction. Mintek, in collaboration with its Australian technology partner (BacTech), is the technology provider for the Beaconsfield refractory gold bioleach plant. At present Mintek, BacTech and Peñoles are constructing a demonstration bioleach plant for copper-zinc concentrate treatment. Bioleach liquors produced in all applications have to be neutralized. In the copper-zinc case, neutralization is required for bleeding iron from the circuit and for adjusting the pH value ahead of solvent extraction. In the refractory gold bioleach circuit, neutralization is required for producing a stable iron-arsenic residue. Some of the challenges encountered in each of these neutralization applications are discussed, and examples of results obtained are presented.

Jan 1, 2000

By Noel Dent

Increasing interest is being expressed in the development and availability of Electronic Delay Detonators throughout the world. Particularly in open-cast mining, the benefits associated with precise, reliable initiation systems are perceived to be considerable. Many of the systems currently being developed have sophisticated programming requirements associated with them, or are numbered systems that require predetermined layouts to determine timing patterns, and importantly are far more expensive than existing initiation systems.

Jan 1, 1994

By Qingzhu Li

The brewing industry byproduct, spent grain (SG), was evaluated for its ability to adsorb Ag(I) from aqueous solutions. Ag(I) adsorption was dependent on solution pH, contact time, adsorbent dose, initial Ag(I) concentration and temperature. The kinetic data were well described by pseudo-second-order kinetic model, indicating that chemical adsorption was the rate-controlling step. The equilibrium data followed Freundlich isotherm rather than Langmuir isotherm, suggesting heterogenity of the adsorption sites on spent grain. Ag(I) desorbed from Ag(I)-loaded spent grain was also evaluated in this study. HCl, NaOH, Na2S2O3 and ultrapure water were chosen as eluants and desorbed Ag(I)-loaded spent grain for 30min, Ag(I)-loaded spent grain desorbed in 0.1M Na2S2O3 exhibited higher elution efficiency as compared with other eluants. The results indicated that application of spent grain for adsorption and recovery of silver from aqueous solutions was feasible.

Jan 1, 2009

By Aleksandar D. Bugarski, Robert J. Timko

Despite extensive research efforts conducted in the past decades, occupational health risks associated with exposure to nano and ultrafine aerosols emitted by diesel power equipment are still not completely understood. The complexity of physical and chemical properties of diesel aerosols, constantly changing with the implementation of advanced diesel emissions control technologies, make this task rather challenging. The objective of this paper is to identify and characterize nanometer and ultrafine aerosols emitted by diesel engines in the underground environment and evaluate the effects of selected contemporary control technologies on physical properties, chemical composition, and in-vitro toxicology of diesel aerosols. The physical and chemical properties of the nanometer and ultrafine diesel aerosols are to be characterized through a test series in the NIOSH Lake Lynn Laboratory experimental mine. The crucial part of the study has been development of a facility that allows researchers to generate field results with precision and accuracy characteristics of a laboratory environment. The knowledge obtained from this study should strengthen our understanding of the health implications related to exposure to diesel particulate matter and aid in assessing the potential of various control technologies for reducing this exposure.

By Stefan Larsson, Jan Ekström, Jennie Kock-Larsen, Håkan Garin

"This paper describes the testing procedure (or protocols) for quality control of dry deep mixing columns in a major ground improvement project carried out in Sweden. Quality control was mainly based on column penetration tests performed at different stages in the project and on two occasions after installation. In the paper, the results from the tests are compared with tests on the unimproved clay. As expected, the results show that the correlation between undrained shear strength in the columns and in the unimproved soft soil depends mainly on the in-situ stress. However, the correlation probably depends on when the tests were performed after mixing. When the influence of the in-situ stress was excluded from the analysis, no significant correlation could be identified. This means that the undrained shear strength in the columns and in the unimproved soft can be considered to be uncorrelated when the strengths and the corresponding variability are evaluated with depth from groups of tests.INTRODUCTIONQuality control and quality assessment of deep mixing (QC/QA) constitute a key component in verification of the limit state design. Due to the complex mixing process and varying geological conditions, it is normally not possible to sufficiently assess the strength and deformation properties in advance. In Sweden, the most commonly used QC/QA method for verification of the limit state is the column penetration test (Axelsson and Larsson 2003; Bergman et al. 2013). The method works well but is time-consuming and requires many tests since property variability is normally high. The column penetration test can be used to assess the undrained shear strength Cu,col. However, it is not clear how the strength correlates to the undrained shear strength of the unimproved soil Cu,soil. There are common factors such as the in-situ stress state and the natural water content, which makes a positive correlation probable, i.e. as Cu,soil decreases, Cu,col also decreases and vice versa. The unimproved soil has a natural spatial variability, but it is not known if the improved soil follows the same variation. The mixing process has a substantial influence on the strength variability and may supersede the influence of other factors. However, if a sufficiently good correlation exists between Cu,col and Cu,soil, information from the geotechnical ground investigations can be used in the design and planning of QC/QA of deep mixing in a more stringent manner. Information about the correlation is also essential in reliability based design, where a strong positive correlation may have a negative influence on reliability. However, as discussed by Al-Naqshabandy and Larsson (2013), this correlation may be weak or insignificant for a representative failure domain where the mixing process may have a dominant influence on the strength variability. It is thus of interest to assess the correlation."

Jan 1, 2015

By L Stitz, S Kinnear, L D. Fabbro

Sensitive and tolerant species of macroinvertebrates were present across a wide range of conductivity concentrations in the Isaac River catchment in Central Queensland, indicating the need for further ecological studies in the field to underpin the development of regionally-tailored guidelines for conductivity. The Isaac catchment has naturally high conductivity, but there is also increasing pressure on resource companies to ameliorate saline mine water discharge. Recently, catchment management efforts have included a revision of the water quality guidelines that are specific for the broader Fitzroy catchment. These guidelines include the use of macroinvertebrates as indicators of ecosystem health, but developing and applying such guidelines first requires a good understanding of macroinvertebrate ecology and population dynamics, ideally from field validation. To date, studies of macroinvertebrate tolerance to conductivity in southern freshwaters, as well as in laboratory-based ecotoxicological tests conducted in Queensland, have suggested that ranges exceeding 1000 ¦S/cm are likely to have negative impacts on survivorship of all taxa. However, these results may not be transferable to natural populations of macroinvertebrates from the Isaac, where the naturally high-conductivity water may allow the opportunity for adaptation. To test this, macroinvertebrate assemblages were examined at a series of sites in the upper Isaac River catchment at the end of the dry season in 2012. Patterns in the assemblages were examined together with water quality parameters, in order to gauge the ability of macroinvertebrates to survive at conductivity concentrations exceeding 1000 ¦S/cm. The specific conductance of the field sites ranged from 477 ¦S/cm to 9791 ¦S/cm and a total of 39 families from 13 orders were identified. Species richness was not significantly different between sites of differing conductivity. Macroinvertebrate populations were dominated by Dipterans as well as the traditionally more pollution-sensitive families Ephemeroptera and Trichoptera. There was an absence of any correlation between conductivity and species richness (P > 0.050), suggesting that macroinvertebrate taxa richness occurs independently of conductivity, at least in this particular cohort of mining and/or grazing influenced ephemeral systems in Central Queensland.CITATION:Stitz, L, Fabbro, L D and Kinnear, S, 2013. Macroinvertebrate tolerance across a range of conductivities in the Isaac River Catchment (Central Queensland), in Proceedings Water in Mining 2013 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By R. J. Durheim

Detailed investigations have been conducted into 21 rockbursts which caused damage to excavations in deep South African gold mines, in many instances resulting in the death or serious injury of workers. The objective of this study is to determine the principal factors controlling the severity and distribution of damage, so that strategies to reduce the hazard of rockbursts may be developed. It was found that the source mechanism is often controlled by the mine layout, and regional structures such as faults and dykes; while local rock conditions and support systems strongly influence the location and severity of damage. In the short term the most important lever for reducing the rockburst hazard is the effective implementation of existing rock engineering knowledge and technology.

Jan 1, 1998

The development of a robust belt sampling strategy and protocol inunderground gold mines is a fundamental requirement for effective grade quality control, ore accounting and mine-mill reconciliations. As part of the ore management system, a belt sampling system has been developed by the author, which is used to predict monthly gold grade and its error for underground/belt/mill reconciliation and grade control. This paper presents the step-by-step development of the belt samplingstrategy and sample preparation protocol at Target, an underground gold mine in South Africa. The belt sampling system at Target consists of an underground belt transporting run-of-mine material into an underground transfer point, a weightometer, a two stage crushing system, a tube splitter and a catchment device. The design allows run-of-mine ore on the belt to be sampled automatically by a go-belt sampler. GyÆs sampling theory of particulate materials forms the basicframework of the belt sampling strategy. The theory is used to quantify the optimum sample mass of broken material to be taken from the belt and to predict its reliability. It is also employed to determine the Fundamental Sampling Error (FSE), time interval between samples and particle size requirements of the final underground belt sample. Further, GyÆs sampling theory provides the means of analysing the crushing processes, splitting, segregation error, analytical variance, and the best sample preparation protocol. Although the belt sampling strategy developed in this study was forWitwaterstrand gold ore, the process is entirely general and may be very successfully used in any underground or surface mine.

Jan 1, 1999

By Q. Lui, J. Oxenford

The occurrence of heavy minerals in the oil sands of Alberta has long been known and has been well documented in the literature. Unfortunately most of the researchers working on this resource have been unable to produce products that meet acceptable market specifications. This has resulted in many misconceptions about this resource. Recent efforts have shown that with some innovative approaches, marketable material can be produced and as a result it might finally be possible to realize the potential of this immense resource that, some have estimated, could contain in excess of 20% of the world demand by 2010. This paper highlights the uniqueness of this mineral assemblage and the mineral processing challenges it presents. It shows the most recent work that has resulted in the production of marketable titanium and zircon products. This paper also focuses on some of the special problems resulting from the variability in the heavy mineral suite. Of special interest is the occurrence and removal of bitumen and pyrite without adding to the sulphur dioxide loading in the regional airshed. The trend by the mining industry to develop various positions on ‘sustainable mining’ has some significance for the heavy mineral industry. Although the industry generally has an excellent track record of eventually rehabilitating disturbed ground in an acceptable manner, heavy mineral mining operations tend to have a relatively large footprint of disturbance and the industry is under considerable pressure to develop options that are more environmentally acceptable. In addition, as operators move to exploit deposits that are lower grade and/or are further from a port site, the emissions per unit of sold product will also rise and the industry will be under pressure to address this issue as well. Because heavy minerals from oil sands are by-products of existing operations, there are virtually no incremental disturbances or emissions that would be associated with heavy mineral production. All mining and tailings remediation issues are accounted for by the oil sand operation. The only incremental emissions would be those associated with the mineral processing operations and transport of finished products to a port site. This paper discusses the environmental and cost implications of this situation.

Jan 1, 2003

By Guillermo Manrique

El presente texto describe las estrategias planteadas por la empresa Southern para la convivencia pacífica con las comunidades afectadas por el desarrollo de las operaciones mineras. Para ello, se requiere definir los objetivos y la filosofía corporativa (responsabilidad social) que garantice el apoyo de dichas propuestas. Asi también se realiza un estudio base de la comunidad, donde se priorizen las necesidades de las comunidades a través de la estrategia de concertación y así ejecutar proyectos participativos de desarrollo social. Finalmente, la información recolectada se sustenta y validad por las experiencias llevadas a cabo en las 36 comunidades del entorno de las operaciones de SPCC, convirtiéndose en un aporte para el tratamiento comunitario.

Sep 13, 2001

By Z. Duan

A novel concept involving the deployment of chemical stabilization has the potential to eliminate the need of slurry impoundments and significantly reduce the release of trace elements from the high surface area fine coal waste. The process involves mixing the fine waste generated from the underflow of a thickener operation with chemical stabilization agents to tie up the water and to create a solid waste material that can be discharged directly. Portland cement, sodium silicate, F type flyash, C type flyash and hydraulic lime were evaluated as stabilizing agents. A detailed experimental study has been conducted to identify the conditions that provide the maximum compressive strength within a short curing time. Results to date show the ability to achieve compressive strengths adequate for equipment to maneuver on using a Portland cement concentration of around 10% by weight. Quick-setting concrete was not found to enhance stabilization time and compressive strength.

Jan 1, 2012

By J. R. G. Williamson

The Mining Division of Iscor, an integrated minerals and metals company, has recently completed a feasibility study for the establishment of a new heavy minerals mine and smelter in the Richards Bay area of KwaZulu-Natal, South Africa. The mine will produce a heavy mineral concentrate containing ilmenite, zircon, rutile and leucoxene which will be beneficiated at a central processing complex close to Empangeni. The ilmenite will be smelted to produce high-grade titania slag and pig iron for export. The ancient dune containing the mineral deposit is located some distance inland of the coastal dunes, and the sands contain a high proportion of extremely fine material which must be extracted ahead of the gravity separation process. Of the 56 million tonnes to be mined annually over the ten-year life of the mine approximately 23,4%?a total of 13,1 million tonnes of minus 45 micron residue fines?will have to be disposed of in a containment facility. The origin of the fine material is from the weathering of amphibole minerals. The remaining coarse sands will be returned to the mined area to re-create the original dune configuration. A number of options for the disposal of the residue fines have been examined and specialised laboratory tests undertaken to determine the deposition behaviour of the fines. The final solution involved the use of a ?sub-aerial? technique for deposition of fine material in a disposal facility. The resulting arrangement will adequately meet technical and environmental criteria. Upon closure after 10 years of operation, the surface of the disposal facility will be returned to sugar cane cultivation The paper refers to the various options considered and describes the problems associated with competent disposal of the residue fines and the development details of the final disposal facility.

Jan 1, 1997

The 103rd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 16th August, 2000. Welcome The President extended a special welcome to the guests and representatives of our sister institutes and other associations. Also to recipients of awards, senior members of industry, Honorary Life Fellows, Past Presidents, our Members and other guests, among them the following: Reinie Meyer, President, The Geological Society of South Africa Dr Nielen van der Merwe, Chairman, The South African Institute of Rock Engineering Chris Fourie, President, Institute of Mine Surveyors of South Africa

Jan 1, 2000

By D. H. Horswill

The paper point out considerating how mining activities contributed to sustainability, it is important to consider how exploitation of a finite resource can be regarded as sustainable. The now well–recognized concept of sustainable development holds that society’s pursuit of development that meets current needs should not compromise the ability of future generations to meet their own needs. Sustainability, then, contemplates multigenerational enjoyment of a quality of life that includes social and economic benefits and a healthy environment in which to live. In this sense, the benefits of our activities must always exceed the risks. Many other companies are also making significant inroads along the path to sustainability.

Sep 13, 2001

Jan 1, 1967

By J. T. Furey

"A pilot plant study was conducted to evaluate the performance of column flotation in the recovery of gold from a gold/tellurides bearing sulphide ore, and to compare the performance of column flotation to conventional ""mechanically agitated"" flotation.Tests were conducted in a 60 liter glass column with ground flotation feed split from a concurrently operating conventional pilot plant, thus permitting direct comparison between the two processes. During the test program, the effects of wash water rate, gas holdup, froth depth, residence time and flow bias were examined in detail.The ore had an average ""as tested"" feed grade of about 5 g/t gold and 1 % sulphur, with the gold occurring primarily as inclusions of montbragite (Au2Te3) in pyrite, with minor amounts of native gold. Conventional flotation using 60 minutes residence time across four roughing stages recovered about 97% of the gold into concentrates grading about 50 g/t Au. A single stage of column flotation roughing using 25 minutes residence time matched the conventional circuit recovery of 97%, but produced grades of+ 150 g/t Au. INTRODUCTIONColumn flotation is the most significant innovation that has occurred in the mineral processing industry in recent years and has become an important alternative to mechanical flotation. Column flotation has been most widely accepted and applied in cleaning service where it has frequently proven to be superior to mechanically agitated flotation. Roughing in columns has not been ignored, but early testing indicated that columns may not be capable of achieving adequate recovery and, to date, columns have not been seen as serious competitors for mechanical roughers."

Jan 1, 1990

By S. J. Pearce

The need for a simple, very sensitive, and accurate method for the determination of benzene in blood and urine vas evident throughout a recent study of chronic benzene (C6H6) poisoning conducted cooperatively by the United States Bureau of Mines, The Barrett Company, and the producers of benzene. A combustion method which will be described in a later publication, and a previously described/ adaptation of Smyth's method were developed and used during that investigation. The adaptation of Smyth's method gave satisfactory results when dealing with exposure conditions that produced chronic poisoning in a comparatively few days, but it was time-consuming; and lacked the accuracy necessary for a study of the absorption, distribution, and fate of benzene in the body during exposure to threshold concentrations of benzene vapor in air. The combustion procedure was satisfactory from the standpoint of sensitivity but was cumbersome, intricate, time-consuming, and required the use of special and somewhat expensive Physical and chemical apparatus. Following the termination of this study of chronic poisoning, possibilities ides for developing better methods occurred, and these have been investigated by the Bureau of Mines with the aid of Relief Works Division personnel microcolorimetric method for the determination of benzene in air has been described recently.6/ The present report deals rich the adaptation of this new colorimetric method to the determination

Jan 1, 1936

The Southwest Pacific is a region of active volcanism and geothermal systems. Only in New Zealand have the geothermal systems been exploited for electricity generation and industrial processing. At present, approximately 280 MWe of geothermal electricity is generated in New Zealand. A considerable amount of further exploration work is required before the total geothermal potential of the region can be assessed and before the significance of these resources can be judged against other local energy sources.

Jan 1, 1990

The ability to optimise a concentrator from mill feed to final products requires a simulator which integrates comminution, classification and separation modelling. In order to model this range of processes, such a simulator must handle a variety of information about the ore. The AMIRA P9 project has developed a whole-of-concentrator simulation capability which brings together a texture-based model of mineral liberation, quantitative X-ray micro-tomography analysis to measure the inputs required by this model, and a multi-component simulator software framework. In the context of this approach, the term ?multi-component? implies the ability of the simulation to handle many particle properties simultaneously; for example size, composition, density, floatability etc. The simulation software framework provides the means to manage the flow of data around a circuit flowsheet, allowing each process model to access the information relevant to that particular model. A case study based on plant data from a gold-bearing pyrite concentrator is used to demonstrate the capabilities of the multi-component approach in simulating circuits which contain comminution and separation processes.

Feb 27, 2013