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By Taner Sumer, H Altay Guvenir

Fragmentation in rock quarries is tried to be achieved by changing the specific charge, drill pattern and bore hole diameters by different experts. This paper is a brief summary consisting of the utilization of practical experiences of the other group on cost optimization procedure that takes into account blasting, transportation and crushing as a whole process and optimize the cost by defining the optimum gelatin based explosives to be used as a main primer of anfo in three different limestone and granite quarries, with similar rock characteristics.

Jan 1, 1993

By S. Al-Hassan

The deposit has been exploited for Mn oxide and carbonate since 1916. Known reserves of MnO, however, are almost depleted and the survival of the mine will depend on the exploitation of the carbonate. Kriging, inverse distance weighting (IDW) and cross-sectional methods have been applied to the evaluation of the carbonate resources and reconciliation of the estimates obtained shows that kriging and IDW give almost identical block values. A comparison using conditional probability indicates that there is virtually no difference between the global reserve estimates derived from the cross-sectional and kriging methods. The physical causes of these similarities are highlighted and the problems of dealing with multimodal distributions are discussed together with the difficulties of semi-variogram modelling

Jun 19, 1905

By L. F. Contreras

In open pit mine design, it is customary for geotechnical engineers to define the appropriate slope design angles within practical limits. The conventional approach to slope angle design is based on the comparison of calculated stability indicators, such as the factor of safety (FS) and the probability of failure (PF), with generic acceptability criteria not directly related to the impacts of failure. A major drawback of this type of approach is related to the difficulty of defining meaningful acceptability criteria. An alternative methodology of pit slope design is proposed, where the economic impacts of potential slope failures are calculated and used as the elements on which to apply the acceptability criteria for design. The methodology is based on the construction of a graph, referred to as a risk map, that relates the probability of exceeding the economic impact of slope failure to the magnitude of the impact measured in monetary terms. The process includes the analysis of a selected number of representative years of the mine plan and slope sections of the pit areas to define the required inputs for the construction of the risk map. The paper discusses the concepts used in interpreting the probability of slope failure, and describes the approach followed for the estimation of the economic impacts of slope failure and the construction of the risk map. Finally, the two main uses of the risk map are discussed, including the comparison with acceptability criteria for the evaluation of a specific open pit design and the comparative analysis of open pit design options in terms of value and risk to identify optimum pit layouts.

Jan 1, 2015

By E. Pizarro, A. Videla, G. Compan

One of the main problems related to mining investment decisions is the use of accurate prediction models. Metallurgical recovery is a major source of variability, and in this regard, the Chuquicamata processing plant recovery was modelled as a function of geomining-metallurgical data and ore characteristics obtained from a historical database. In particular, the dataset gathered contains information related to feed grades, ore hardness, particle size, mineralogy, pH, and flotation reagents. A systemic approach was applied to fit a multivariate regression model representing the copper recovery in the plant. The systemic approach consists of an initial projection of the characteristic grinding product size (P80), based upon energy consumption at the particle size reduction step, followed by a flotation recovery model. The model allows for an improvement in the investment decision process by predicting performance and risk. The final geometallurgical model uses eight operational variables and is a significant improvement over conventional prediction models. A validation was performed using a recent data-set, and this showed a high correlation coefficient with a low mean absolute error, which reveals that the geometallurgical model is able to predict, with acceptable accuracy, the actual copper recovery in the plant.

Jan 1, 2015

By Paul Morrison

The paper describes the design process, trial testing and contract pile installation of 772 pre­cast concrete piles at a site in Surrey, South East England. Recommendations on how to improve the design, construction trials and main contract piling phases of the project are made. The building layout is shown in Figure 1 and is comprised of a central circulation area with five office wings radiating out from its southern side (only three of these wings were constructed in Phase 1 of the project). Approximately 60% of the circulation area and one office wing were built with a single level basement. The basement was constructed "bottom-up" in open cut with the void between the basement walls and the cut slope being back-filled with compacted site won soil above a perimeter drainage system at basement slab level. The building has up to 3 stories above basement level and is a reinforced concrete structure. The client for the project is Pfizer Ltd. Pfizer Ltd was represented on site by Laing Project Management (Laing). The consulting engineer was Ove Arup and Partners (Arup) while the piling contractor was Roger Bullivant Ltd (RBL).

Jan 1, 2000

By N. C. Matheson

The West's Shell Pile has been used on sites with very soft ground conditions for over 60 years. Fibre reinforced precast concrete shells 900mm long are threadled onto an internal mandrel which can be extended according to the depth driven to attain the load bearing resistance. On completion of driving the mandrel is removed leaving the precast shells to form a permanent lining to the cast insitu concrete core. To give resistance to high contamination, a tar based epoxy coat is sprayed on the outside of the shells or a flexible PVC liner is installed inside the shells to protect the core. Fundamental to the resistance to contamination is the quality of the precast fibre reinforced concrete shell, the mix design and method of manufacture. A series of detailed laboratory experiments were carried out using samples immersed in concentrated acid and sulphate solution. The long term effects of exposure to contamination is recorded in the case studies of existing piles at two gasworks sites.

Jan 1, 1989

By R G. Barker

This paper reviews the annual status of the New Zealand mining industry (metallic minerals and coal) including key aspects such as mineral production, mineral exploration expenditure, commodity price trends, key industry players, market activity and other significant commercial factors.   Strong commodity prices during 2006 have been underpinned by a number of key factors including US dollar weakness and emerging market demand, particularly from countries such as China and India. In real terms commodity prices have recovered significantly since 2002 and are currently at 20-year highs.   New Zealand exploration spending on metallic minerals (predominantly gold) is at a 15 year high driven by rising global commodity prices. New Zealand gold production in 2006 was about 340,000 oz and is expected to grow in 2007 as new mines at Frasers and Globe-Progress (Oceania Gold) and Favona (Newmont) come on stream. Gold production broadly lags 10 years behind exploration spending and exploration activity over the last five years remains well below that seen in the early 1980Æs. Expenditure on coal exploration shows a similar trend with strong growth from a low base over the last five years, reaching over $11 M in 2006. Total coal production in 2006 was 5.9 Mt, an increase of 10% on 2005 with imports from Indonesia adding a further $1.1 Mt.   Newmont and Oceana Gold are by far the largest public gold mining companies operating in New Zealand, although only Oceana Gold maintains a presence on the local stock exchange. Other metals explorers with New Zealand projects include a range of public-listed Juniors (market capitalisation less than NZ$50m) domiciled largely in New Zealand, Australia and/or Canada. Capital-raising on public markets directed towards New Zealand exploration is estimated at around NZ$12 M for 2006, the bulk of this coming via Glass EarthÆs NZ$10 M IPO on the NZAX in October.   The New Zealand Coal sector is dominated by the state-owned enterprise Solid Energy with around 80% market share by production. Other domestic coal competition remains limited, and includes the L&M Group, Pike River Coal, Eastern Corporation, and New Vale (acquired by Solid Energy in 2007). Pricing parity comes mainly from imported coal and global thermal coal prices have remained strong during 2006 at around US$45-55/t, driven by continued expansion in Chinese demand. Coking coal prices have eased 16% since 2005 to around US$98/t in 2007.   Although recent increases in exploration spending suggest a renaissance in the New Zealand minerals sector, long-run trends indicate that we have simply rebounded from a low base over the last five years and much work is still to be done to stimulate further growth in the mining industry to maintain minerals production at current levels. Key industry challenges include marketing exploration opportunities to local and overseas investors, building a critical mass of NZX-listed explorers and providing an internationally competitive environment to attract further capital and expertise.

Jan 1, 2007

By G. E. S. Valadao, J. D. Miller, C. L. Lin

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake poremicro structure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 m, length of 500 m and height of 4000 m. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: 1) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method,2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4)some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By J. S. Stachulak

The Diesel Emissions Evaluation Program (DEEP), a research consortium formed in 1997 by Canadian mining companies, labour unions, and provincial and federal government departments, completed its work by mid-2006. This program, in which Vale Inco participated with both direct funding and in-kind contributions, investigated the ability of currently available technology to significantly reduce underground concentrations of diesel particulate matter (DPM) with high efficiency and low maintenance over a long-term period (years of life).While DEEP?s testing showed that engine maintenance is a critical component for lowering DPM, it was clear that reduction of DPM to the very low target levels of ~0.05 mg/m3 was not possible with maintenance alone. The best candidate technology for achieving low DPM levels was particulate filter systems. Furthermore, successful deployment of such systems was highly dependent on removing them from having to rely on human intervention for their regeneration. The search continues within Vale Inco to identify a reliable and rugged system.

Jan 1, 2009

By Brigitte Lacouture, Yeen Shien Hwang, David Lin

"A baseline survey of the partially open lead regrind circuit at Red Dog Mine indicated poor regrind efficiencies for the three parallel 450 HP tower mills. Driven by the high energy cost and the potential metallurgical gain brought by improved mineral liberation, the Red Dog lead regrind circuit was optimized in two stages.In the first optimization stage, different circuit layouts were evaluated in two plant trials. In June 2003, the regrind circuit was changed to a fully closed circuit. This reduced the tower mill requirement from three to two mills. The circuit modification payback was 11 days through power savings alone.The second stage of optimization was the evaluation of reagent addition. To improve pyrite depression, sodium cyanide was added to the feed of the lead regrind tower mills and tested in a series of plant trials over several mill feed stockpiles. Galena selectivity against pyrite was found to improve in these plant trials. Due to environmental sensitivities, no net increase in cyanide addition to the plant occurred and thus no increase in the cyanide concentrations in the tailings pond or the environment will result.The lead regrind optimization work improved the overall lead metallurgical performance and reduced energy and reagent costs. Economic analysis showed that annual profit increased by as much as US$3.0 M."

Jan 1, 2005

By Brent Duncan, Doug Harding, Bob Stier

The 73rd Street Tunnel Project is part of “The Tunnel and Reservoir Plan” (TARP)also known as the Deep Tunnel Project, and is located in the Village of Bedford Park, County of McCook, State of Illinois. The project consists of a ø 4.42 meter × 2,060 meter long (14´-6? bore, 6,760 foot)tunnel. The completed tunnel is used as a bypass tunnel for the McCook Cup Reservoir Project. The project was awarded to Affholder Inc. of St. Louis, in 2000. The paper describes the project in which a new, high-powered open gripper type main beam machine was used in which high advance rates have been achieved using conventional muck haulage techniques. Features of the project include the installation of rock support consisting of counter-sunk rock bolts that are required to be pull-tested for strength per project specifications. Installation and testing of the bolts are done during the boring cycle. Muck haulage was done by conventional muck car train and hoisting at the construction shaft. As the site layout did not include a tail tunnel, the trains needed to be shuttled at the shaft bottom. Even with the bolting requirements and the muck haulage without a tail tunnel, the Affholder site personnel still achieved high advance rates on the 73rd Street Project.

Jan 1, 2003

By P. Chaddock

The Thompson Mill has a capacity of 15,000 T ID of ore and produces two grades of nickel concentrate, copper concentrate and occasionally graphite concentrate. Up to July of 1985 we processed two distinct ore types: T-1 ore, averaging 2. 8% Ni and . 2% Cu and Pipe Open Pit ore, averaging . 8% Ni associated with peridotite and serpentine. Presently our ores from T-1 mine and Thompson Open Pit are of the same type and are processed together. (Figure 1)! n October, 1982, we decided to install an Outokumpu Courier 300 on-stream analyser on an initial 6 streams. The equipment was delivered to the mill on May 2, 1983 and the first analyses were generated by June 17th. The calibrations were 35% complete by the mid-July summer shutdown and were completed in the fall. 1. 2 Analyser Slurry Feed System:The key to successful on-stream analysis is delivery of the sample streams to the analyser.Our system uses pressure-thief sampling for collection. (Figure 2) Initially we used thief samplers modelled after the Outokumpu design, with turbulence bars upstream of the collection point. These units have been replaced with simple laterals as they have worn out. Our thief samplers are mounted vertically on pump discharges and we believe sufficient turbulence exists to ensure representative sampling.

Jan 1, 1987

By T. R. Curr, R. T. Jones

Keywords: Pyrometallurgy, Mintek, DC arc furnace, plasma, smelting, chromite, ilmenite, cobalt, slag, zinc fuming, dust, magnesium, laterite, ferronickel, arc modelling, Pyrosim, thermodynamics The Pyrometallurgy discipline at Mintek was initiated in the early 1970s, to support a growing ferroalloy industry in South Africa. In addition to a range of pyrometallurgical options, Mintek specialises in DC arc furnace technology and has pilot plant facilities up to 5.6 MVA, as well as a strong base in process and arc modelling. Industrial processes have been developed for ferrochromium production, ilmenite smelting, and cobalt recovery from slag. Recent work has been done on such processes as the production of ferronickel from laterite ores, the fuming and condensation of magnesium, and the recovery of platinum group metals from 'difficult' feedstocks.

Jan 1, 2006

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions that have allowed these objectives to be realised, e.g., furnace cooling systems, and numerical modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimise components of the crucible design to match process requirements are the key motivators for modelling. This paper provides an overview of recent applications of numerical modelling to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath modelling, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.

Jan 1, 2004

By M. McWha

Laboratory bias is a universal problem in all branches of analytical science. It results from differences in methods, techniques, equipment, and calibrations between laboratories. Notwithstanding that it is a property that can be measured by the use of standards or by inter-laboratory testing, laboratory bias remains a material issue for the mining industry. There is extensive literature and clear guidelines on measurement from the International Organization for Standardization (ISO) and its worldwide federation of national standards bodies (ISO member bodies) and from the science of metrology. ISO guides cover the manufacture and use of standards. An accessible source of literature covering laboratory quality control comes from the public health sector, particularly pathology. There is little doubt in financial reporting rules about the meaning of materiality. Public reporting guidelines are clear that material matters need to be disclosed for investors. Unfortunately there is currently no clear guidance what to do about biased assay results in mineral industry public reporting guidelines. This paper reviews the requirements for the manufacture and use of reference materials, public reporting requirements in the mining industry, and presents proposals to improve management and reporting of laboratory biases. Keywords laboratory bias, reference materials, ISO Guides, financial reporting, materiality.

Jan 1, 2014

By Murali M. Gadde

Welded wire mesh is the most commonly used skin control technique in the United States underground coal mines. Currently, selection of the mesh is based on trial and error rather than any rigorous design methodology. Several factors affect a wire mesh?s performance including the amount of rock material to be supported and how the load is distributed, wire gauge, aperture size, grade of steel, weld strength, bolting pattern and sheet size. Although the best way to choose the mesh is to conduct full-scale physical load tests, because of the limitations on the number of variables that can be considered in such tests and the requirement of an elaborate test set-up, it may not always be possible to use this option. An alternative would be to use numerical modeling to study the load-deformation behavior of a wire mesh. In addition to providing a very detailed stress, strain distribution in the entire mesh, the advantage of this approach is the ease with which parametric studies can be conducted. In this paper it is shown that the load-deformation curves generated by nonlinear numerical models match closely with laboratory derived ones. Then, based on parametric studies, design guidelines are developed to choose the mesh appropriate for different loading conditions. The modeling studies also bring forth the limitations of the current lab studies. For example, under some conditions it was noticed that the small sheet size considered in lab tests would produce higher mesh deformations than a full-size one used in actual practice.

Jan 1, 2006

By Rudolph P. Frizzi

Quality control is essential for augered cast-in-place (ACIP) piles (also known as continuous flight auger (CFA) piles outside the United States) and drilled displacement (DD) piles since the pile is constructed below the ground surface out of the direct sight of the personnel constructing and inspecting the pile. ACIP piles are being successfully constructed to support high-rise structures, hospitals, arenas and stadiums, mass transit systems, and power and industrial facilities. The use of DD pile technology is also gaining ground in the United States, typically utilizing proprietary systems such as Omega (currently utilized by Richard Goettle Inc., and LG Barcus and Sons, Inc.), Berkel, and DeWal (currently utilized by Morris-Shea). Different types of ACIP/DD pile installation equipment are shown in Figures 1 and 2. ACIP piles are installed into granular and cohesive soils, and soft rock to lengths currently approaching 130 ft (39.5 m), with diameters up to 24 to 36 inches (610 to 915 mm), and sustaining design loads approaching 900 kips (4000 kN). Current DD pile installation equipment in the United States is capable of installing up to 79-ft-long (24 m) piles with diameters ranging from 12 to 18 inches (305 mm to 460 mm).

Jan 1, 2004

By Jared M. Green

This paper presents the wall stabilization design and implementation for a 541 linear ft masonry and concrete gravity-type retaining wall flanking the west perimeter of a 7.37 acre parcel in Bronx, New York. This paper will discuss the results of static and dynamic stability analyses performed for the pre- and post excavation phases for the proposed 300 ft wide open-cut of up to 14 ft of contaminated soil below the toe of the retaining wall. The wall stabilization consisted of over 74 inclined drilled and grouted anchor dowels, and 55 tiebacks drilled and grouted to the underlying mica schist bedrock. Three over-lapping rows of jet grout columns were chosen as the foundation solution for the existing retaining wall. This paper focuses on the design, construction and performance of the jet grout curtain wall. The jet grout wall served three purposes: 1) underpinning and excavation support for the removal of contaminated site soils, 2) permanent hydraulic barrier, and 3) resistance against a deep seated failure within the thick clay layer present at the site. The originally designed jet grout wall had unexpected negative effects to the existing retaining wall. The jet grouting program was modified while the Observational Method (Peck 1969) was employed to keep wall movements to a minimum. This paper discusses the diagnostic methods used to determine the cause of retaining wall movement; the implementation of a remedial ground improvement program; the modification to the jet grout installation procedure; and the ultimate performance of the jet grout wall.

Jan 1, 2011

By Henry P. Chandler

[Diamond, because of its extreme hardness and abrasion resistance, has an important function in precision engineering and automation. With the increasing; requirements of modern production for fine tolerances, interchange-ability, and speed, it has become even more important. In spite of the supply of other abrasive and hard materials and of ultrasonic, electrospark rued other substitute grinding, methods, world industry seams likely to absorb large quantities of diamond for industrial purposes. An increasing part of the world's needs will be supplied by manufactured diamond, which was introduced commercially by General Electric Co. in 1957. Use of diamond for glass cutting roes bark several centuries, mid diamond drilling of rock became important to the mining industry M the 1870's. Today, diamond drilling is the most extensively used method of exploring the world's ore reserves; diamond drills two also used to determined the nature of bedrock below the foundations of buildings, dams, and bridges. Diamond drill bits are now used extensively in the petroleum industry, and replacement or steel rock bits with diamond drill bits in hard rock formations has affected substantial savings.]

Jan 1, 1964

By Henry P. Chandler

[Diamond, because of its extreme hardness and abrasion resistance, has an important function in precision engineering and automation. With the increasing; requirements of modern production for fine tolerances, interchangeability, and speed, it has become even hors, important in spite of the supply of other abrasive and hard materials and of ultrasonic, electrospspark rued other substitute grinding methods world industry seems likely to absorb large quantities of diamond for industrial purposes. An increasing part of the world's needs will be supplied by manufactured diamond, which was introduced commercially by General Electric Co. in 1957. Use of diamond for glass cutting goes bark several centuries, mid diamond drilling of rock became important to the mining industry M the 1870's. Today, diamond drilling is the most extensively used method of exploring the world's ore reserves; diamond drills two also used to determine the nature of bedrock below the foundations of buildings, dams, and bridges. Diamond drill bits are now used extensively in the petroleum industry, and replacement or steel rock bits with diamond drill bits in hard rock formations has effected substantial savings.]

Jan 1, 1964