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By H. W. Glen

The National Institute for Metallurgy - usually referred to as NIM - has become the Council for Mineral Technology, or Mintek. The Honourable F. W. de Klerk, Minister of Mineral and Energy Affairs, announced the change of name at the official opening of the main entrance to Mintek's premises on 30th October, 1981. Awards for bravery Two men who disregarded the dangers of fiercely burning timber and falling rocks to douse an underground fire, using their hard hats to scoop water from a drain, received the Chamber of Mines Award for bravery at a ceremony held at West Driefontein Gold Mine near the end of October.

Jan 1, 1981

By L. Roux

This review was initially motivated by the author’s own experience in attempting to reconcile run-of mine production tons with the Coal Resource and Reserve estimation of mineable, in-situ tonnages. The primary scientific measurements and observations that are collected during exploration at the beginning of the value chain will have a profound effect on the future of the mining operation. Due diligence must be exercised during the planning of a new mine and during the life of an existing mine. The comments provided by the technical and economic assessment group of Venmyn Deloitte confirmed the need for this critical review. They found the reporting of Coal Resources in South Africa to be inconsistent. This was particularly problematic in the Waterberg Coalfield in Limpopo Province. In this coalfield there are two types of coal deposit present. The first is comprised of the thick intercalated, cyclic coal and shale/mudstone sequences of the Volksrust Formation. This overlies multiple coal seams within the Vryheid Formation, each of which is thick enough to be extracted as an individual raw coal unit. On the other hand, the interbedded coal and shale seams of the Volksrust Formation require beneficiation to separate the coal from the shale. The review examines practices and methods, investigates alternatives, provides checks and balances, and tests these against actual production reconciliations. In conclusion, the best estimates of the mineable, in-situ tonnage will be obtained from the air-dry raw material density. These estimates should be adjusted afterwards to allow for free moisture content. The adjustments are derived from reconciliation data. The greatest contributing factor to the over-estimation of Reserve tonnages is the moisture content of the raw material. This fluctuates significantly under varying conditions in situ, as well as upon exposure to the natural environment. The air-dried density of the raw material includes inherent (structurally bound) moisture within the matrix. It provides credible tonnage estimations of raw material available while also providing an indication of voids within the volume of material being assessed. The calculated solids percentage can be used to adjust the specific gravity, which is determined via the Archimedes principle. This will supply a representative estimate of the material to be mined.

Nov 1, 2021

By M. Z. Emad, A. Khan, N. Abbas, K. G. Li

Probability-based empirical methods were employed as an alternative approach to predicting uncertainties associated with rock mass properties. The focus was on developing probabilistic spreadsheets to forecast rock mass classification indexes. Histograms were constructed to describe the best distribution in predicting rock mass properties. The developed models also offer utility in predicting the impact of discontinuities within the rock mass on rock strength and rock mass classification systems. Statistical analyses identified volumetric joint count, joint spacing, joint frequency, and rock strength as the most influential parameters. Moreover, the statistical analysis revealed varying degrees of correlation among different rock mass properties. While some properties demonstrated significant correlations suitable for modelling, others did not align well with any correlation model. The results highlight the need for a comprehensive approach to rock mass characterization, considering multiple factors beyond volumetric joint count. Geological complexities, including tectonic activity and weathering processes, may obscure direct correlations. These results emphasize the importance of empirical modelling and detailed site investigations for accurate assessment of rock mass quality and stability in the Himalaya.

Jun 10, 2024

Introduction to high temperature oxidation of metals, by N. Birks and G. H. Meier, London, Edward Arnold, 1983. 19S pp. R30,25. Reviewers: M. B. Cortie and G. G. Garrett Seam gas drainage with particular reference to the working seam, edited by A. J. Hargraves. Woollongong, The Australasian Institute of Mining and Metallurgy. 370 pp. $A30. Reviewer: C. J. Fauconnier New books Solvent extraction Part I, by G. M. Ritcey and A. Ashbrook. Amsterdam, Elsevier, 1983. Elektronishche Steuerungen und Mikroprozessoren im Bergbau. Sicherheit und Zuverlassigkeit Environmental impact control. Philosophical and procedural guidelines for the planning professions Mineral processing and extractive metallurgy. Reagents in the minerals industry.

Jan 1, 1984

By M. Rhodes

The Sukari project, which is owned by Centamin Egypt Ltd, is located in southern Egypt, 770 km south of Cairo but close to the Red Sea. The project is the first new gold development in Egypt and was commissioned in the middle of 2009. In 2007, Centamin purchased the CIL plant from the Kori Kollo mine in Bolivia. This plant was originally designed to treat 6.5 Mtpa of oxide ore. The Sukari deposit contains an oxide zone close to surface with a thick zone of mixed oxide and sulphides below this. The sulphides contain relatively coarse pyrite and arsenopyrite with fine <10 µm gold inclusions. Eventually, the sulphide ore will be mined from underground. Metplant Engineering Pty Ltd, a subsidiary of Bateman Engineering Pty Ltd was contracted to design modifications and additions to the Kori Kollo plant to enable it to treat the Sukari ores. The plant was designed to treat the three ore types in stages. Throughput was set to 4 Mtpa, dueto Sukari ore being harder, at a head grade of 1.7 g/t to produce 200 000 oz of gold. The oxide circuit was based on the use of the Kori Kollo plant and the difference with mixed ore was that the oxide circuit would treat flotation tailings rather than ore. This circuit has a leach capacity of 26 000 m3 and residence time of 24 hrs The main feature of the upgraded mixed ore plant was the addition of a flotation circuit to produce a concentrate which would be reground and treated in a separate leach and elution circuit. Ore is crushed in a gyratory crusher and the comminution circuit uses a conventional SABC producing a product with a P80 of 150 microns. The throughput of 580 tph of oxide ore and 500tph of mixed ore was set to match the mills from Kori Kollo, with the addition of the pebble crusher to accommodate the more competent Sukari ore. The flotation circuit comprises a single rougher circuit to maximize recovery. The concentrate is thickened prior to regrinding which is carried out in a tower mill and two SMD mills operating in series. The final product, with a P80 of 12 microns, from the regrind circuit is leached in a CIL circuit with a total capacity of 2 550 m3. Gold is recovered through a conventional pressure Zadra circuit. Tailings from both circuits report to separate tailings thickeners and are pumped to a tailings storage facility. The circuit is designed to maximize the recovery of water. The project lies in one of the driest deserts in the world and a feature of the operation is the use of sea water from the Red Sea. This water is pumped 25 km from the coast.

Jan 1, 2009

By J. J. Taute, G. Chisakuta, P. Bwando, G. Mitshabu

"BASF Mining Solutions have developed a new generation of copper solvent-extraction reagents that offer significant benefits over the existing reagents available to the industry today. Initial laboratory studies and pilot-plant trials have shown that these new reagents offer the benefits of a dramatic increase in resistance to degradation and are nitration-proof. This paper details a recent pilot-plant campaign at a commercial solvent-extraction plant. The main focus was to evaluate the copper/iron selectivity, copper recovery and net transfer of the new reagent compared with the conventional oxime reagents. The new reagent displays similar copper recovery and net transfer capabilities from typical agitation leach solutions. The pilot-plant results show a step change improvement in copper/iron selectivity in comparison with the existing modified and non-modified hydroxyoxime reagents used on the commercial plant. INTRODUCTION Copper solvent extraction (SX) from an acidic aqueous solution is typically accomplished using a hydroxyoxime extractant (Jergensen, 1999; Kordosky, 2000; Szymanowski, 1993). There are three hydroxyoximes from which all standard formulations are derived: 5-nonyl salicylaldoxime (NSAO), 5-dodecyl salicylaldoxime (DSAO) and 2-hydroxy-5-nonyl acetophenone oxime (HNAO). In the case of NSAO, it is necessary to use equilibrium modifiers in order to increase the copper stripped from the extractant (Kordosky & Virnig, 2003). Blends of DSAO, NSAO and HNAO are used to cover a wide spectrum of conditions (Kordosky, 2008). Use of modified aldoximes and reagent blends over the last 30 years has influenced the way copper producers and equipment manufacturers have approached the operation of copper plants. Existing solvent-extraction reagents cater for typical pregnant leach solutions (PLS) of copper mining systems which do not have significant effects on the reagent. Table I illustrates the range of copper concentration, pH values, temperature and iron concentrations for different leaching operations. As conditions become increasingly aggressive (i.e., higher PLS temperatures in primary sulfide leach or high iron content), current reagents become less capable of functioning according to expectations. One example is the effect of high iron (Fe3+) concentration in PLS and operating SX to achieve high copper recoveries. The ferric is partially chemically extracted and is transferred to elctrowinning (EW) during the stripping stage. To avoid a build-up of iron in electrolyte, which negatively affects current efficiency, a bleed of electrolyte is required. This bleed leads to excessive consumption of reagents, such as cobalt added to the EW process, and thus increases operational cost."

Jan 1, 2015

By S. M. Rupprecht

A deposit to be mined by underground methods can be accessed by a number of methods: ? Adit ? Decline or ramp ? Inclined shaft ? Vertical shaft. Adits are an economical approach when the orebody is above the general floor elevation i.e. suitable in hilly or mountainous terrain. Incline shafts are limited to relatively shallow deposits, and because they are developed on an incline, development lengths for a given depth are the three to five times longer than for a vertical shaft. Vertical shafts are the preferred method for deposits deeper than 300 m but the development rate is slow and construction costs are very high. Declines or ramps offer early access to shallow deposits, which develops the ore body expediently, but are generally developed at a gradient of approximately 12 per cent. Decline haulages have become an attractive alternative to shaft hoisting, and over recent years the role of decline access has become more widespread throughout South Africa. Traditionally, South Africa has enjoyed the use of shaft systems, largely due to the large knowledge base of mining the Witwatersrand Basin, where vertical and inclined shafts were the norm. South Africa has also had the advantage of cheap electricity, giving shafts a definite economic advantage. However, in recent years the national power utility ESKOM has undergone an expansion programme that has led to tariff increases of nearly 100% over a three-year period. Based on the changes in electricity tariffs and technological improvements to underground haulage trucks, the economic inputs to access development have changed. This paper reviews mine access for shallow deposits as currently applied in South Africa. Based on current economic inputs, the paper investigates at what point a vertical shaft would be more economical than a decline system utilizing typical South African mining equipment.

Jan 1, 2012

By Kedikilwe Oageng

Effective perimeter control during drilling and blasting is critical not only to blasting results but also to the overall stability of the pit over its entire life span. A pit where perimeter control is not given enough attention when conducting drilling and blasting operations, often experiences over-break or back break beyond final pit wall limits, and therefore has a relatively high probability of failure. Such a pit also becomes unsafe, sometimes not easily accessible, has increased loading costs due to production of oversize, longer cycle times and often problems are encountered when blasting subsequent benches. All these are undesirable consequences, which have negative cost implications. Specialised blasting techniques such as trim blasting and pre-splitting have over the years proved to be effective perimeter control measures. However, the success of these techniques is directly attributable to the time and effort given to the processes. This paper presents results of a project undertaken to monitor, review and optimize the trim blasting and pre-splitting processes at Orapa Diamond Mine in Botswana. The project was specifically incepted to improve the final wall conditions, which continued to deteriorate due to persistent over-break during blasting. The paper also analyses the results obtained against a benchmark of results taken prior to project implementation. Specific blast design parameters which are critical to blasting results were identified as problem areas after auditing of the pre-implementation drilling and blasting practices. These include drill-hole depth, spacing, splitting factor for pre-splits and timing of trim blasts. The impact of different rock types on the results was also studied, and recommendations were made at different phases of the project and results obtained after implementation analysed until optimum results were achieved.

Jan 1, 2008

By K. Lomberg

In this paper the process of sampling and assaying as it relates in particular to the platinum group elements (PGEs) is presented. A discussion of the geology of PGE deposits is included to provide an understanding of the mineralization that is considered necessary prior to sampling, as this has a direct bearing on the mineral resource estimate and also the selection of an appropriate mining cut. The discussion includes the selection of the sampling technique (drilling or face sampling), the size of the sample relating to the requirements of the laboratory, the potential mining cut, as well as a reference to sampling theory. The selection of an assay technique that is appropriate and will yield the optimal result based on sample turnaround, precision, accuracy, and cost is then considered. Examples are drawn from work undertaken on the Bushveld Complex (Merensky Reef, UG2 Chromitite Layer, Platreef) and Great Dyke (Main Sulphide Zone). A discussion of the appropriate QA/QC programme includes the chain of custody, CRM selection and the QA/QC process. Keywords sampling, assaying, QA/QC, platinum group elements.

Jan 1, 2014

By E. Van Der Lingen

Within the context of the overall gold market industrial demand plays an important role. Industrial demand for gold was 430 tonnes in 2008, approximately 12% of total end-user consumption. The dominant consuming industry in this market for gold remains the electronics sector, consuming an estimated 300 tonnes, primarily through the use of gold bonding wire for computer chips and plated contacts and connectors. Substantial demand also derives from dental applications, with other smaller industrial markets and decorative uses of the metal (non-jewellery) constituting the balance. In each market gold faces tough competition from alternative lower cost materials, such as silver and copper (electronics) and ceramics (dental). As well as the obvious benefits to the gold market resulting from this constant physical demand, there are an umber of additional positive factors concerning the use of gold in industrial applications: ?Price inelasticity: demand for gold from the major consuming industries has so far proven to be relatively robust in the face of significant increases in gold price. ??Stickiness?: the gold consumed by industrial uses tends not to return easily to the market (i.e. the demand is ?sticky?) because it is highly dispersed. ?Image: the beneficial environmental and medical applications of gold (e.g. gold used in the treatment of prostate cancer and in purification of contaminated water) are helpful to the positive image of gold. ?Added-value: new industrial uses for gold can create substantial added value in the supply chain, particularly in gold producing countries.

Jan 1, 2009

By Q. Zhang, X. C. Wang, S. Mao

Phosphate ore is an important strategic mineral resource in which apatite is the main valuable mineral. Flotation is the most commonly used method to separate apatite from middle-low grade phosphate rock. Selective flotation separation is based on the difference of physical and chemical properties of minerals occurring at the three interfaces of mineral/bubble/water. Surface and interface chemistry of mineral have been playing an important role in interpreting and governing its flotation phenomenon. In-situ, visualized and high-precision analytical techniques, such as Time-of-Flight Secondary Ion Mass Spectrometry, Atomic Force Microscopy and Molecular Simulation, have been applied to explore and uncover microscopic nature of apatite flotation. Consequently, a great progress at molecular or atomic level on surface and interface chemistry of apatite flotation has achieved in the past decades. In this paper, the research progress of surface and interface chemistry of apatite flotation such as surface wettability, surface-charging characteristics, surface dissolution behavior, adsorption mechanisms of fatty acid collector and depressor on apatite surface were systematically reviewed. This review will be helpful for the development of more selective reagents and efficient technologies for apatite flotation. Keywords: Apatite, Flotation, Surface and interface chemistry, Surface analysis technology

Jan 1, 2020

By L. Bam, R. Machaka, S. Chikosha, N. S. Muchavi

"Parts manufactured through power metallurgy (PM) typically contain pores that can be detrimental to the final mechanical properties. This paper explores the merits of 3D X-ray computed tomography over traditional microscopy for the characterization of the evolution of porosity in metal injection moulding (MIM) and direct powder rolling (DPR) products. 17-4 PH stainless steel (as-moulded, as-debound and sintered) dog-bone samples produced via MIM and Ti-HDH strips (as-rolled and sintered) produced via DPR and were analysed for porosity. 3D microfocus X-ray tomography (XCT) analysis on specimens from both processes revealed spatial variations in densities and the existence of characteristic moulding and roll compaction defects in agreement with traditional microscopic microstructural analysis. It was concluded that micro-focus XCT scanning can be used to study MIM and DPR parts for the characterization of the amount, position and distribution of porosity and other defects. However, the majority of the sub-micron sized pores could not be clearly resolved even at the highest possible instrument resolution. Higher-resolution scans such as nano-focus XCT could be utilized in order to fully study the porosity in MIM and DPR parts. IntroductionMetal injection moulding (MIM) is a novel process, which combines the advantages of powder metallurgy (PM) and plastic injection moulding. MIM has found widespread applications in the cost-effective production of high-sintered density small parts with complicated shapes and mechanical properties equivalent to those of wrought materials (German and Bose, 1977; Machaka and Chikwanda, 2015; German, 2013). There are four basic processing steps involved in MIM, namely; feedstock preparation, injection moulding, debinding and sintering. These steps are discussed in greater detail elsewhere (Machaka, Seerane and Chikwanda, 2014; German and Bose, 1977; Machaka and Chikwanda, 2015; German, 2013).Feedstock preparation involves mixing metal powder with a carefully selected composition of polymeric binder materials at a specific temperature. The feedstock is then granulated and injected into a predefined mould die with the desired shape. The part produced during the moulding step is referred to as a ‘green’ component. The green component typically contains no porosity since the spaces between adjacent powder particles are readily filled with the binder materials (German and Bose, 1977; Li, Li and Khalil, 2007). Debinding is the systemic removal of the binder components by chemical, catalytic, or/and thermal means while maintaining the shape of the component. The part produced after the debinding step is referred to as a ‘brown’ component. Debinding is known to be the source of porosity in brown components (Ji et al., 2001; Tsai and Cen, 1995). Finally, the brown debound part is sintered to full or nearfull density (Sotomayor, Varez and Levenfeld, 2010). The sintering step and associated densification closes up the majority of the pores. Sintered MIM parts are typically sintered to high density (95–99%) and retain an irreducible amount of residual porosity (Barriere, Liu and Gelin, 2003; German, 1990)."

Jan 1, 2016

By R. Rumpold

The platinum group metals (PGMs) palladium, platinum, and rhodium represent the key materials for automotive exhaust gas treatment. Since there are currently no adequate alternatives, the importance of these metals for the automotive industry is steadily rising. The high value of PGMs in spent catalysts justifies their recycling. The state-of the-art technology is to melt the ceramic carrier and collect the precious fraction in a liquid metal bath. As the feed material has quite high melting points, huge amounts of energy are required for this process. Hydrometallurgical treatments of the spent catalysts offer the possibility to recycle the PGMs with less energy and time demands. Moreover, automotive catalysts contain further valuable materials to improve the exhaust gas treatment. These compounds, like cerium oxide, cannot be recovered in pyrometallurgical processes. This paper deals with a special process that uses hydrometallurgical principles to recycle the valuable metal fraction from spent automotive catalytic converters. Hydrochloric acid in combination with hydrogen peroxide is used as leaching agent. This combination selectively dissolves the PGMs and the cerium, which can be recovered in separate steps. As the leaching solution is regenerated and reused, wastewater generation is minimized. Furthermore, the process residues constitute potential byproducts.

Jan 1, 2012

A high volume of slimes which are separated out during the mining of heavy mineral sands has a high environmental impact and results in great capital as well as operational expenses. The presence of clay minerals drastically increases the slimes volume that needs to be catered for due to its low settling capability as well as swelling characteristics. By adding coagulants in the form of cations and organics, one can improve the settling rate of the minerals as well as the degree of solid bed compaction. The addition of flocculant, which is currently used in industry to improve settling rate, is detrimental to solid bed compaction. By combining the cations and flocculant one can dramatically improve the solid bed compaction. This combination is, however, detrimental to the settling rate of kaolinite-rich slimes but improves the settling rate of smectite-rich slimes. Organics can also be used to produce a clear supernatant and improve the settling rate.

Jan 1, 2010

The vast majority of the roughly 100 million rock anchors installed in mines in the USA each year use resin cartridges1. About 4.5 million of these bolts are installed using a mechanical shell in addition to the resin to create an active (pre-tensioned) bolt. Over 1 million of the bolts are passive cable bolts and typically have an effective grout length of 1.2 m, regardless of the cable length, which could be as long as 6 m. The successful performance of the resin grouted bolts depends on several parameters, including the annular gap between the bolt and hole wall, which should be relatively small, ideally from 3 mm to 5 mm. This requirement, combined with the high viscosity of the resin, produces a high back-pressure that can cause the bolt being installed to buckle or not be installed to standard. It is this back-pressure that limits the effective grout length with passive cable bolts and causes the mechanically anchored bolt failures (typically called ?spinners? where the mechanical shell does not anchor). This creates potentially unsafe conditions and wastes time and money. A purpose, built rig was used to mimic underground installations and record the back-pressures during full scale applications in the laboratory. This information was used, and is still being used, to reduce the failures and sub-standard installations by producing improved designs. In addition, a flow model was calibrated that can act qualitatively to estimate the back-pressures and can be used as a crude screening process before full scale prototypes are built and tested. To date, the results obtained have been used to stop the use of a mechanical shell due to the proven higher rate of failures. A new, improved mechanical shell is being field tested and another system is underdevelopment. The use of the rig is therefore ongoing to develop improved mechanical anchor systems. It is too early for real data; however, anecdotal evidence seems to indicate that significant improvements can and will be made.

Jan 1, 2011

By M. S. Shishvan, J. Sattarvand, R. S. H. Meij

Navigating miners during an evacuation using a smart evacuation technology can significantly decrease the evacuation time of an underground mine in case of an emergency. This paper presents a mathematical programming model to calculate the most efficient escape path for each miner as a critical component of the smart evacuation technology. In this model, the total evacuation distance of the crew is minimised and scenarios with blocked pathways, and stamina categories for the miners are simulated. It was found that all the tested scenarios are technically feasible. Using the feature that filters out blocked pathways has no downsides, as safer routes are calculated, and there is no penalty in the computation time. The paper also discusses the social and technical issues that need to be overcome before the algorithm can be implemented as an actual escape solution.

Sep 1, 2021

Mixed integer programming (MIP) has been used for optimizing production schedules of mines since the 1960s. The major problem in the long-term production scheduling for an entire orebody is that the number of integer variables needed to formulate an MIP model is too large to solve the formulation. This number may reach well over one hundred thousand. To overcome this difficulty, this paper presents two new algorithms to reduce the size of the problem. These algorithms assign an earliest and latest possible start date for each machine placement, eliminating the integer variables that correspond to machine placement before its early start date and after its late start date. A case study based on Kiruna Mine, the second largest underground mine in the world, is summarized in the paper. It shows substantial improvement in the solution time required using the new algorithms. This increased efficiency in the solution time of the MIP model allows it to be applied to Kiruna Mine, with the potential to increase substantially the net present value (NPV) of the project.

Jan 1, 2008

The Namakwa Sands heavy mineral deposit is located along the West Coast of South Africa and the mine is a world class producer of high quality zircon, ilmenite and rutile concentrates from essentially unconsolidated marine and aeolian sands of Cainozoic age. The objective of this study was to characterize rutile with respect to distribution, grain size, textures, colour and mineral chemistry within the Namakwa Sands orebody with the aim to explain its overall poor recovery. A representative suite of heavy mineral concentrates from various sections of the orebody and stages in the recovery circuit has been investigated microscopically and by means of SEM-EDS and LA-ICP-MS. The rutile grain size distribution displays a wide range and is directly related to its variable chemistry and consequently density. In placer deposits such as Namakwa Sands, mineral sorting is a function of hydraulic equivalence, and high density grains are smaller than the lighter grains when deposited under similar conditions. Grain size is also a function of sediment maturity, and the highly mature red aeolians and (RAS) component of the deposit has a coarser grain size than the less mature orange feldspathic marine sands (OFS). The above primary characteristics of rutile are responsible for the loss of the coarse-grained fraction during screening and, given the empirically determined relationship that increased substitution elements reduce conductivity, also during electrostatic separation. Provenance studies using geothermometry have shown that the heavy mineral suite has been sourced mainly by the proximal medium-to high-grade Namaqualand Metamorphic Complex. The positive relationship between substitution elements and temperature of formation explains their high concentration in rutile of this deposit. The heterogeneity of rutile, produced by the combination of a high temperature primary source and the typical marine-aeolian placer genesis is deposit specific and unfortunately not conducive to high recovery levels in the current Namakwa Sands beneficiation circuit.

Jan 1, 2010

By M. J. Little

Potgietersrust Platinums Ltd is Anglo Platinum?s only open pit operation and annually extracts 57 million tonnes of rock from 2 open pits. Over the past 3 years ~220 km of exploration drilling has been done, ~1000 km of rock face have been exposed for face mapping and over 7000 laboratory and field tests have been conducted. This has produced large amounts of geotechnical data to be utilised for feasibility studies, initial slope design and ongoing slope optimisation. It was necessary therefore to develop geotechnical databases to manage the vast amounts of data collected. SABLE and MineMapper 3D databases were created for logging and mapping respectively, with rock testing data incorporated into both. A pit inspections database was developed in MS Access and the existing groundwater and slope monitoring database was improved. The databases were linked to AutoCAD and Datamine to ensure that the latest geotechnical data is used for planning, draughting and modelling. The use of geotechnical databases ensures that no data is lost, standards are maintained and analysis can be easily performed. This increases the confidence of the analysis and allows the geotechnical engineers to optimise slope designs and blast designs on a regular basis. This reduces the risk of slope failure thus making the open pits more economical and safe.

Jan 1, 2006

By Bjørn Nilsen, Brian J. Ballou

The Tellnes open pit mine in Southwestern Norway has been operating since 1960. The maximum height of pit walls is currently about 150 meters with the current mine plan extending this distance to 400 meters with slope stability being a major controlling factor. As a result of unfavorable combinations of directions of major joints and faults, local stability problems have occurred several places in the pits walls. Stability problems have affected the reliability of main transport roads on several occasions. Most of such incidents have occurred during heavy rainstorms and during periods of repeated freezing/thawing. This paper reviews some of the stability problems and the measures taken to deal with such stability problems.

Jan 1, 2006