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By J. M. Ortiz

Mineral resource evaluation requires defining geological domains that differentiate the types of mineralogy, alteration and lithology. Usual practice is to consider the domain boundaries as hard, i.e. data from across the boundaries are disregarded when estimating the grades within a given domain. This practice may hinder the quality of the estimates when a significant spatial correlation of the grades exists across the domain boundaries. In this paper, several geostatistical methodologies to handle soft geological boundaries are compared through a case study on a copper mine in Chile. The estimation methods considered are: ordinary kriging using hard boundaries between geological domains; ordinary kriging omitting the geological boundaries; traditional and standardized ordinary cokriging of the grades assayed in different domains; ordinary kriging within dilated geological domains, that is, incorporating samples from adjacent domains up to a given radius from the boundary of the domain being considered. The estimations are performed using a set of exploration data (drill hole samples) and are validated using a set of production data (blast hole samples collected for grade control). Results indicate that kriging with dilated domains performs better than ordinary kriging using hard boundaries or no boundaries and better than the ordinary cokriging approaches. It therefore appears as a simple alternative to global kriging (without considering the geological domains) and allows accounting for changes in the grade average, dispersion and spatial continuity with the geological characteristics of the deposit, via the use of grade variograms proper to each geological domain. The maximal distance for searching samples from adjacent domains should be chosen according to the spatial correlation of the grades across the domain boundaries, or via a cross-validation at an early stage of the mine or a jack-knife if production data are available. Keywords: Kriging; cokriging; soft boundaries; hard boundaries; geological control; geological domains.

Jan 1, 2006

By E. T. Boshoff

Paper written on project work carried out in partial fulfilment of B. Eng. (Metallurgical Engineering) The weathering of kimberlite can be accelerated with cations in solution if swelling of the kimberlite occurs in contact with the weathering medium. The type and amount of swelling clays present, along with the surface charge and cation valence, determine the degree of swelling that can occur. Crystalline swelling occurs by the incorporation of cations in the interlayer spacing of the silica sheets. Kimberlite exposed to cupric cations showed very strong weathering, indicating that this type of weathering may be considered a viable process option. Kimberlite fines generated after weathering with monovalent cations showed poor settling behaviour compared to kimberlite weathered with di-, and trivalent cations.

Jan 1, 2005

By Mary F. Koehler

Continuing a program of thermochemical investigation of compounds of to ferroalloy elements, this paper contains ins values of the heats of formation of two sodium molybdates (Na2Mo04 and Na2Mo207) and three sodium tungstates (NO2W4, Na2W207, and NA2W207, and Na2W4013). The experimental method was solution calorimetry. The solution medium was sodium hydroxide solution, except that hydrofluoric acid solution was used for sodium tetratungstate. The heat of formation values are given with reference both to the constit¬uent elements and to the constituent oxides. These data are of prime impor¬tance in the thermodynamic consideration of these substances, as their accumulation includes the most difficult and time-consuming steps toward evaluating the free energies of formation and thus the potential reactivities and thermal stabilities. Except for values for sodium monomolybdate and monotungstate, no previous similar data were contained in literature sources.

Jan 1, 1962

By J. A. Cooper, M. R. Petersen, P. O. Jackson, J. C. Langford

The organic, inorganic, and radiological characteristics of airborne aerosols have been measured as a function of particle size in controlled atmosphere test chambers and operating uranium mines. Concentrations of benzo(a)pyrene in two mines ranged from 26 to 57 ng/m3 of air. The carbon chain length of adsorbed n-alkanes was correlated with particle size. Normal mining activities produced an ore dust aerosol with mass median aerodynamic diameter (MMAD) greater than 2 µm. The elements Na, Al, Si, K, Ca, Ti, V, Fe, and U exhibited elemental ratios similar to bulk ore and had comparable MMAD's. The S, Zn, and Pb were higher in aerosols than bulk ore and were associated with smaller MMAD particulates. Radon daughter particle size distributions were influenced by the kinds of particulates

Jan 1, 1981

By Wayne Trudel, Lloyd McEvers, Lori Clarke, Eric Saderholm, Charles Lynn Bolin, Leroy Schutz

Newmont mine geologists in Nevada are most proficient when applying technical expertise with multi-departmental teams in three main settings. The first is value creation through near-mine discovery, development and reserve conversion. Since 1986, geologists have created substantial net asset value in developing more than 1.35 kt (43 million oz) into quality Nevada surface and underground gold reserves. The second setting is value realization by supporting mine operations with ore control, selective mining, reconciliation investigations and strategic planning. The investment of technical research on reconciliation investigations led to new concepts and practices that highlighted opportunities for large revenue and reserve gains. In 2002, more than $65 million in projected revenue was added to the Gold Quarry south layback. Kriged mine polygon construction and controlled blast heave at the Lone Tree Mine provided millions of dollars in mining efficiencies. High-quality geologic advice in selective mining at the Twin Creeks Mine helped obtain $4.3 million revenue gains throughout 2002-2003.

Jan 1, 2004

By Rudy Tenbergen, Dick Farmery, Jim Naylor

"Paste backfill has replaced cemented rock fill as one of the components to improve ground · control and mine safety at the Macassa Operation of Kinross Gold Corporation in Kirkland Lake, Ontario. It is the first operation to utilize "" flash thickening ""of very fine gold tailings to a paste consistency in the ""Paste Production and Storage Mechanism"", a joint technical development of Inco and GL&V. The tailings paste is mixed with alluvial sand to produce an engineered quality paste backfill. The development leading up to the decision to proceed with this novel technology is discussed, as well as commissioning of the backfill operation.IntroductionThe occurrence of a major rockburst on November 23, 1993 prompted a review of mining and backfill procedures at the Macassa No 3 shaft . This shaft is some 7238 ft deep and lies in a mining belt that is prone to seismic events. The recommendations were to change the mining from underhand cut and fill to mechanized long hole stopping and to look at alternatives to the rockfill backfill system in place. The Macassa cemented rock backfill operation, while producing the desired fill stiffness had drawbacks as compared to paste fill. With paste fill, placement rates are faster, more openings can be filled, it is less expensive and less prone to the occurrences of compensable incidents.Macassa mining personnel visited the Sudbury operations of Inco in 1993, where development on paste backfill was in progress. As some of the R&D was taking place with funding from the Premier's Council Technology Fund of the Ministry of Trade and Technology of the Province of Ontario , Inco personnel at that time did some feasibility and conceptual consulting on the use of paste fill for the industry. Inco had developed the use of alluvial sand paste fill, an engineered blend of alluvial sand and tailings fines and was doing development work to eliminate the ""conventional"" way of producing paste from mill tailing by thickening and filtration. This latter development work was taking place with GL&V Ontario. That work led to the filing of a joint Inca/ GL&V patent application for the PPSM, the Paste Production and Storage Mechanism with all marketing rights being held by GL&V."

Jan 1, 1997

By R J. Merchant

The Hauraki goldfield is located east of Auckland in the North Island of New Zealand. It includes Great Barrier Island, the Coromandel Peninsula and the Coromandel and Kaimai Ranges as far south as the town of Te Aroha and south east to Te Puke. It has a total north-south extent of about 180 km and an area of 3000 km2. The goldfield is the most productive in New Zealand, and while production at present is negligible, the area has undergone continuous exploration over the last seven years.

Jan 1, 1984

By Alcy Dias Rodrigues

O Centro de Operações do Sistema Elétrico da Aperam South América possui um sistema de automação chamado SAE (Sistema de Automação de Energia) para realizar a distribuição e operacionalização da Energia Elétrica na planta em Timóteo, sistema este com mais de 20 anos de implantação. Devido ao alto grau de obsolescência do sistema SAE, a dificuldade de se atualizar todos os componentes do sistema e a complexidade e dificuldade do acesso aos dados, verificou-se a necessidade de encontrar uma forma de disponibilizar os mesmos para os demais sistemas da empresa. Com base nestas necessidades, foi desenvolvido e implantado um GATEWAY capaz de realizar a comunicação com todas UTR’s CORTEX (remotas do sistema), através do protocolo CONITEL 2020, disponibilizando estas informações coletadas em uma camada OPC SERVER para que o sistema PIMS (Sistema de Gerenciamento de Informação da Planta) realize a coleta e armazenamento destas informações, permitindo assim um melhor gerenciamento de energia pelo VIRIDIS (Sistema de Gestão da Eficiência Energética utilizado na APERAM), além de permitir que toda a planta tenha acesso em tempo real às informações de tensão e corrente de todo setor de 13,8 kV, 69 kV e 230 kV.

Oct 30, 2017

By Bill Shand

"Placer Dome - Campbell Mine is a gold mine located at Balmertown in the Red Lake District of North Western Ontario. During the last 50 years, the mine has produced over ten million ounces of gold.A change in ball mill grinding media was made in August 1998 from 1.5” diameter forged balls to 1.5” diameter, 18% chrome balls. This was done to reduce grinding media consumption and to potentially help flotation performance.A marked ball test done in September-October 1999 showed that, of the alloys tested, 18% chrome was the optimum for the ore at Campbell Mine. The test showed that consumption of chrome balls should be 3 times less than forged balls.In December 1999, the ball size was increased from 1.5” to 2” in an effort to reduce the amount of oversize rock discharging from the ball mill. This change in size was successful.Grinding media consumption for the ball mill decreased 73% from 1.20 kg/tonne before the use of chrome balls to 0.327 kg/tonne after the use of chrome balls. This clearly indicates that, for the ore at Campbell Mine, there is significant savings in grinding media by using chrome.Grinding ball costs were reduced by 59% from $O.88/tonne of ore milled to $0.36/tonne of ore milled representing a saving of $298,000 per year. This also clearly indicates that using chrome balls is a benefit at Campbell Mine.Test work to show that chrome grinding media is beneficial to flotation has been inconclusive so far but is still ongoing.No tests have been done to see if there would be a benefit with an even higher chrome percentage in the grinding media. Test work in this area is also planned for the future"

Jan 1, 2001

By A. J. Martin, M. J. Peoples, D. J. Adams, A. Opara

"The weathering of coal mine waste rock releases iron, calcium, sulfate and associated trace elements like selenium (Se). Nitrogen species are also found in association with coal-mining drainages mainly due to the leaching of residual blasting compounds. Elevated concentrations of Se are a ubiquitous occurrence in coal-mining environments in British Columbia. A major concern with waterborne Se in British Columbia is the potential for its bioaccumulation in aquatic food chains.Treatment to remove Se from coal-mining waste waters has proven to be challenging for conventional water-treatment technologies. Compounding this challenge, many streams are characterized by high flows and low selenium concentrations. Conventional membrane and ion exchange treatments produce concentrated brine streams that are difficult to treat or require disposal. Conventional biotreatment systems use excess nutrients to provide the required electrons to compensate for inefficient and variable electron availability, as well as to adjust reactor chemistry.This paper's electro-biochemical reactor (EBR) technology provides a controllable and consistent supply of useable electrons to the microbes directly at a low voltage potential (1-3 V) and low current. In this manner, the EBR technology overcomes the shortcomings found in conventional systems, as it reduces the required nutrient addition and provides a more controllable, efficient, economical and robust biotreatment system. Additionally, the EBR process does not produce excess solids or biomass; therefore, solids management post-treatment is not required.Laboratory EBR bench-scale and on-site pilot-scale systems were used to treat five British Columbia coal-mine waste waters; influent Se concentrations ranged from 35 µg/L to 531 µg/L. Se treatment targets for the tested waters ranged from 5 to 10 µg/L. Mean Se concentrations in EBR effluents ranged from 0.5 µg/L to 1.4 µg/L, while reducing sulfate concentrations. The test data demonstrate that the EBR technology is an effective Se removal option for British Columbia’s coal-mining waste waters.IntroductionSelenium in Mining. Selenium (Se) is a naturally occurring trace element, which is an essential nutrient in small amounts (Thompson and Robinson, 1980; Brown and Arthur, 2001). However, it is also toxic to aquatic life, birds, and humans at very low concentrations. A major concern with waterborne Se is the potential for its bioaccumulation in aquatic food chains, resulting in acute and/or chronic toxicity to fish, water birds and amphibians (Besser et al., 1996; Conley et al., 2009)."

Jan 1, 2015

By T. M. Barczak

A primary objective of the Bureau of Mines geomechanics research program is to develop a better understanding of support behavior and interaction of supports with the strata so that supports can be more closely engineered to the geological conditions in which they are employed. Four longwall shield supports were instrumented with an eight-transducer instrumentation array to measure leg, canopy capsule, and compression lemniscate link forces from which resultant shield loading was determined. The instrumented supports were monitored over a 4-month period, producing over 75 shield cycles of resultant shield loading. Resultant loading is the true measure of support resistance, providing both roof-to-floor and face-to-waste support reactions as well as the location of the reaction on the shield canopy. Observed roof support reactions were analyzed, with particular emphasis on horizontal shield loading, since it is the least understood design parameter. Average, peak, and change in shield loading during the mining cycle are discussed. Correlations among data parameters are examined, as is the distribution of support loading at the headgate and midface. Conclusions are drawn as to the effectiveness of the shield support at this installation. Recommendations are made for further research needs.

Jan 1, 1987

By A McDowell

Pound Road Quarry is an alluvial gravel quarry owned and operated by Fulton Hogan Ltd. for the supply of aggregate in Canterbury, and is the largest quarry in the South Island in terms of production. It has evolved from three separate quarries, as a result of which extraction has occurred sporadically in a number of areas. Due to this factor, and the need to manage environmental impacts, a detailed quarry management plan was completed in 1995 which formed the basis for implementation of a certified environmental management system.   In December 1997, the quarry was the first in New Zealand to achieve ISO 14001 (TELARC) accreditation for implementation of an environmental management system. The main potential environmental impacts arising from the quarry operation include dust, noise and groundwater contamination, and visual landscape effects associated with gravel extraction, the mitigation of which is achieved by means of æbest practiceÆ methods. All quarry operations are controlled in terms of the environmental management system by means of regular (monthly and yearly) environmental reviews, appropriate auditing of environmental documents, and monitoring of environmental targets in accordance with consent and statutory requirements.

Jan 1, 1998

By L. T. Isaacs, W. H. Traves

A numerical model for analysing the drainage of fill in mine stopes has been described. The model can be used to analyse the process of fill drainage in existing and proposed mine stopes. The validity and potential value of the model have been established by experience with a simpler, 2-dimensional numerical model and by testing the new model against the earlier model. The new model is more useful than the 2-dimensional model because it allows for heterogeneity of fill material within the stope - a factor that has been demonstrated to affect drainage characteristics significantly. The 3-dimensional model is also capable of predicting pore pressures and drainage rates at specific locations in the stope without the need to resort to 2-dimensional generalisations. Such information, integrated with relevant field data as they become available, will provide valuable mine planning information for the scheduling of filling operations and design of fill mixes

May 1, 1991

This paper describes the economic study of longwall versus bord and pillar mining using all continuous miners for a colliery located at the South Coast district of New South Wales, Australia. In this district longwall mining appears to be a better economic proposition than bord and pillar. The internal rate of return on investment is found to remain approximately constant for each method irrespective of life. The economic importance of percentage extraction of coal is shown to be small for high values of minimum rates of return, becoming more significant as the minimum rate of return decreases.

Jan 1, 1980

By Douglas Banks

Construction for the new 2.5 MGPD raw water intake project commenced December 2002. The project, initially designed as a 12' Ø concrete lined intake shaft,145' deep, with two offset 24" lake taps, 520' and 470' long was subsequently “value engineered” running the two lake taps through a single conduit. The offset for summer and winter pools was accomplished via a second shaft located at the lakes edge. Construction involved the use of blind drilling techniques for the shaft development and drill and blast techniques for the tunneling. All works were completed through extremely hard crystallized sandstone. The project came online August 12, 2004.

Jan 1, 2005

By J. M. Pugliese

The Bureau of Mines, in support of its overall goal of helping to meet future U.S. demand for minerals, undertook this study to aid the quarry entrepreneur and/or operator in developing quarries near urban areas. In response to increased environmental concerns, the quarry operator often must take steps beyond those required in the last decade toward gaining permits for quarrying near metropolitan areas. Following the steps suggested in this report should increase the chances to obtain the permits to open and develop a quarry. Each task and question in the general plan flow diagrams are described in detail, with the flow diagrams aimed at the goal of acquiring the necessary permits. The appendixes include (1) types of projects for which Environmental Impact Statements (EIS's) may be prepared and Federal agencies responsible for preparing them, (2) State contacts for information regarding environmental impact assessment requirements and mining and mineral land reclamation laws, (3) a checklist of environmental inventory factors, (4) a tabulation of different regulations that affect mining in Michigan and the number of townships and counties that have each of the listed regulations, and (5) environmental logic associated with site selection. A central recommendation is that the quarry entrepreneur and/or operator coordinate plans at the beginning with local government officials (such as township supervisors and/or city and county planning board members), State and Federal officials, and public groups that will be affected.

Jan 1, 1979

By Kallioinen Jouko

"Advanced Flotation Technology is the application driven design of Don-Oliver flotation cells to achieve the optimum performance for each type and grind of flotation. Optimum performance is the combination of both recovery and selectivity.Optimized performance is the combined product of optimized mixing and effective froth removal. Optimized mixing is applied to roughers, scavengers, cleaners and specialty cells such as those to float hydrocyclone underflows in both primary and regrind circuits in order to reduce overgrinding. Effective mixing for fine material is easy, but overmixing reduces selectivity in frothbed.Selectivity in flotation is an important target, especially when treating complex ores, and parameters in frothbed have been examined to improve the separation of minerals and eliminate circumstances that reduce separation rate.Advances in process control have been achieved with expert controls and instructive operator information data. This has gained a higher degree of understanding of cell operation and ore type being processed to be used in future process development work. Excellent results of this Advanced Flotation Technology have been achieved and designs through 7000 cu ft (200 m3) are currently available for high capacity concentrators. This paper will detail how flotation cells are more responsive to the exact requirements of the duty specified."

Jan 1, 2000

By W. Pawlak, J. Janiak, C. Rodkiewicz, B. Ignasiak

"There is a general consensus that, in order to widen the utilization of Western Canadian coals, a major effort must be devoted to their transportation, utilization of fines, beneficiation and mining techniques. It is postulated that the concept studied extensively over the last four years at Alberta Research Council (ARC), and based on a combination of hydraulic mining, selective agglomeration with bitumen and/ or heavy oil, pipeline transportation and oil recovery from agglomerates, offers a particularly attractive solution to the problems associated with extraction, beneficiation, transportation and utilization of Western bituminous and subbituminous coals. Results of preliminary experimental work on the feasibility of pipeline agglomeration of metallurgical coal and hydraulic transportation of agglomerates are presented and discussed in the context of conventional agglomeration techniques in stirred tanks. IntroductionAlberta is endowed with enormous reserves of low-sulphur coals which could attract considerable attention of potential customers, but the remote location of this province handicaps its competitiveness on the world market. It is known that Alberta's Cretaceous, particularly metallurgical, coals differ significantly from their Carboniferous counterparts; current R&D work on indigenous coals should continue to expand in order to encourage overseas client s to use these coals more extensively.There is a genera l consensus that, in order to widen the utilization of Western coals, a major effort must be devoted to their transportation, utilization of fines, beneficiation and mining techniques."

Jan 1, 1986

By T Goswami

The conventional practice in open cut coal strip mining has been to blast the overburden or coal layers in separate blast events. This is done in order to maximise the benefits from throw blasting and also to limit coal losses. Each blast event usually has a particular design of hole diameters, burdens and spacings, explosive charges and blast timing in order to achieve the required blast outcome for either the overburden or coal. This means that each blast has to be separately cleaned on the surface after excavation of the previous blast. Hole locations then have to be individually surveyed and marked, holes drilled, explosives and initiators loaded and the blast fired. Each of these actions takes considerable time and resources and therefore impacts on mine productivity. The mine has to be cleared for each blast event and every blast presents a new potential source for noise, dust or vibration disturbance to the neighbouring population. Exposed highwalls are also subjected to vibration and damage from each subsequent blast event

Jan 1, 2006

By H. C. Wade

"Description and UseDischarge liners or pulp lifters as they are sometimes called are a trough type liner used at the discharge end of the mill where ground ore passes to the trunnion.There are basically two methods of discharging pulp. The First and most common is the overflow method. Here ground ore travels from the feed to the discharge end where it exits through the discharge trunnion in an overflowing manner, hence the name ""overflow"". (See Figure I) The second method of discharging pulp is the grate method. With this method you block-off the trunnion and hold the ore inside the mill for a longer period of time. This allows only the desired size of ore out of the mill. Ore passes through the grate liners, into the Vibrathane Discharge liner, and finally down to the trunnion. Greater control of the ore size results wit1 this method as compared to the overflow method and it also eliminates reclassifying and regrinding. (See Figure 2)Types in UsePresently the majority of discharge liners in use today are rubber. (Metal insert and rubber covered) In some extremely course applications steel and nihard are used."

Jan 1, 1980