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By M. S. Diederichs, G. Walton

"Developments in understanding the brittle fracture of rock over the past two decades ultimately led to the acceptance of a cohesion-weakening-friction-strengthening model as an appropriate strategy for the modelling of spalling using a continuum approach. This strength model has been used to replicate observed failure depths and geometries for a number of case studies in the literature, most notably the AECL Underground Research Laboratory in Manitoba. One thing which these case studies typically ignore, however, is the influence of rock dilatancy on the evolution of brittle failure. Physically, this phenomenon is the volumetric expansion of the rock due to fracture opening; numerically, this phenomenon is captured by the flow rule, which is often characterized by the dilation angle, ?. Accurately modelling rock dilatancy in conjunction with strength evolution is necessary both to predict the magnitude and distribution of ground displacements, as well as the exact depth and shape of the fracturing zone. Both of these factors can have significant implications for support design. This paper is focussed on presenting some of the recent developments in this field in the context of a number of numerical modelling case studies. Initially, a new model for the dilatancy of brittle rock is presented, as well as some representative data and model parameters for different rock types. Next, several case studies of highly stressed tunnels and shafts are presented. The results of continuum numerical models are presented to demonstrate the ability of the back analyses to match observed in-situ measurements and obtained. The predictive capabilities of the material model are also highlighted for cases where sufficient “a priori” information (such as laboratory compression testing data) are available. The issues of model nonuniqueness and strain-localization/bifurcation are also addressed."

Jan 1, 2015

By H. Mengbing, A. Potokin, A. Usov

"Revealed and analyzed in the study are the ways of significant perfection of specific characteristics of the equipment, such as use of high-frequency voltage transformation to create a charger; use of pulse transformers, with core made of materials with high magnetic permeability, in pulse generating circuits; as well as use of special ways to produce voltage pulses with a short front. The experiments have proved the possibility to adapt these technological solutions for electric-pulse installations, and suggested on this base is a strategy of further development and application of electric-pulse technologies. The different applications joint work schemes of voltage sources with two levels voltage and energy in electric pulse technologies are investigated. The possibility of increasing energy efficiency of destruction is shown."

Jan 1, 2014

By M de Freitas Silva

One of the main steps during the decision-making process of long-term mine planning is the definition of the optimal sequence of extraction, which usually is synonymous with maximising the discounted cash flow of the project subjected to several constraints arising from aspects of technical, physical, and economic limits.Open pit mine production scheduling (OPMPS) comprises several intricacies related to its size and uncertainty of input parameters. Due to its complexity and prohibitive size, traditional mine planning usually relies on heuristic or metaheuristic methodologies which are able to provide good solutions in a reasonable amount of time. However, most of the uncertainty that surrounds the mining complex is ignored leading to non-realistic results.In this paper, a new heuristic approach is explored in order to solve a stochastic version of the OPMPS problem accounting for geological uncertainty in terms of metal content, multiple processing streams, and stockpiling option. The methodology involves generating an initial solution by solving a series of subproblems and this initial solution is improved using a network flow based algorithm.The algorithm was applied to a relatively large gold deposit with more than 119 thousands blocks. Results have shown that the methodology is promising to deal with large-size mine instances in reasonable time.CITATION:de Freitas Silva, M, 2014. Solving a large stochastic integer programming model for production scheduling at a gold mine with multiple processing streams and uncertain geology, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 389–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By William Gleason

"Caterpillar is the largest manufacturer of mining equipment in the world. In hundreds of surface mines around the globe, Caterpillar’s flagship 793 haul trucks can be found moving material for copper, coal, gold, iron ore and other mines. Likewise, its iconic yellow bulldozers are at mine sites the world over — the company recently announced the sale of its 40,000th large dozer. And since its acquisition of Bucyrus in 2011, Caterpillar has positioned itself to become a worldwide leader in the underground mining sector as well.But don’t think that the company is resting on its reputation. As evidence of its commitment to the global mining sector, as well as its confidence in the future of mining, Caterpillar invited mining trade press, including Mining Engineering, to its Tinaja Hills Training Center near Tucson, AZ in November to introduce the latest editions to its mining portfolio. The two-day event focused mostly on the newest electric drive haul trucks, the Cat 796 AC, which will operate in the 326-t (360-st) class, and the 798 AC in the 360 t (400 st) weight class.Caterpillar representatives also spoke about new offerings in the underground space as well as the newest version of the D11 large dozer.“It has been 10 years since we launched the F Series,” Jean Savage, Caterpillar’s vice president, surface mining and technology said. “Since then, we have been on a journey to serve our mining customers and we wanted to have trucks in every application. Today, we are launching two new trucks that will allow us to fill out our portfolio.”While Caterpillar previously offered the broadest range of off-highway haul trucks to the mining industry, it was noticeably absent from the 326-t (360- st) and 360-t (400-st) weight classes."

Dec 1, 2018

By J. Coffin, M. Muinonen, D. Fragomeni, R. Multani, C. Deredin

"Rejection of pyrrhotite from pentlandite is of critical importance to the economics of nickel concentrate production and the main goal of the Strathcona milling operations. A joint team of XPS, Glencore Technology and Strathcona Mill personnel executed a comprehensive program of work to develop and implement strategies for increased Po rejection with focus on challenging ores containing high feed Po/Pn ratios (> 7) and significant hexagonal Po content (> 40% of total Po). This paper describes the team results including minerology, bench-scale flotation tests, and plant validation tests and modeling that have defined the path forward to improving the metallurgical performance and economics of the mill operation. Techniques to quantify hexagonal and monoclinic pyrrhotites were developed at XPS to assess the differences in their metallurgical behavior since their flotation responses are quite different. Mineralogical tools including QEMScan were extensively used to determine mineral liberation, associations, optimum grind size, and nickel deportment into pentlandite, pyrrhotite and non-sulphide gangue. Several reagents/strategies were evaluated during bench-scale flotation testing to significantly increase Po rejection. A significant shift in the Po-Pn selectivity and grade recovery curves was achieved using several strategies including the use of DETA and sodium metabisulfite, and regrind of the rougher concentrate and rougher cleaner/rougher tails.INTRODUCTION The Strathcona Mill is owned and operated by Glencore Nickel – Sudbury Integrated Nickel Operations and has been processing Ni-Cu ores from the Sudbury Basin since 1968 (valuable sulphides: pentlandite (Pn) – (Ni,Fe)9S8 and chalcopyrite (Cp) – CuFeS2). Currently Strathcona Mill receives ore mined from two main sources in the Sudbury area and produces two concentrate streams – a nickel-copper concentrate that is shipped to the Sudbury Smelter and a copper concentrate that is sent to the Fonderie Horne (Glencore Copper, Rouyn-Noranda). The general flowsheet currently used at Strathcona is displayed in Figure 1. It is highlighted by separate feed circuits for regular grade Ni ores and high grade copper ores. The copper circuit has a preflotation stage prior to a rougher-scavenger stage, a copper-nickel separation circuit, and a pyrrhotite (Po) rejection circuit."

Jan 1, 2018

By M. J. Shulman

The exploration geologist is frequently confronted with the problem of allocating his resources, i.e., exploration effort, among various areas. Although geologic, financial and logistic considerations influence the allocations, no objective criterion is usually given which determines the optimal allocation. Maximizing the gain in information, subject to the constraint of a limited exploration budget, is used as the objective criterion to allocate reconnaissance effort. The information function, I(x), quantifies the expected gain in information, where x is the scale of exploration. To calculate the information function the following data are necessary: 1. The probability that an area contains a target must be estimated. 2. For each scale of exploration, four probabilities must be estimated: the probability that an anomaly is produced by the target; the probability that an anomaly is not produced by the target; the probability that an anomaly is produced by a barren area (false signal); and the probability that an anomaly is not produced by a barren area. Alternatively, the barren area can be replaced by other targets. To illustrate the allocation model, the optimal number of line kilometers/line spacing per area is determined for an aeromagnetic survey for iron in Egypt.

Jan 1, 1985

By M C. Evans

"Mine decommissioning is the final phase in a mining project. Planning for decommissioning must commence for a proposed mine even before the government approves it. Queensland mining approvals require proponents to commit to completion (or closure) criteria defining successful rehabilitation. Queensland mining project statutory environmental authorities must also specify how progressive rehabilitation is to occur throughout the mining project. Final landforms with graded banks together with creek and run-off diversions are often required and constructed early in the life of a mining project. At closure, mining projects must demonstrate that future medium-term risks are not significant, or failing this, a residual risk financial payment must be made to the state. CSIRO climate change projections indicate that Queensland is likely to become warmer this century with less rainfall in parts and with extreme rainfall events likely to occur more frequently. This project was undertaken to?determine: if current rehabilitation planning tools assist in determining the environmental risks from mining closure not adequately addressing climate change if these risks are addressed by current rehabilitation outcomes.The north-west Queensland mining region and the central Queensland coalfields were represented in this project by five study sites. Local data sets for temperature, rainfall and rainfall intensity were produced using conservative greenhouse gas emission scenarios representing likely future atmospheres, and using the SimCLIM climate model, Evaporation data sets were also derived from available climate parameters. These projected climate variables supported equations and models used in Queensland to determine mining project rehabilitation completion criteria. Storm intensities and return intervals were directly applied to assess the likelihood of failure of engineered structures such as stormwater diversions and banks. Plant cover change determined by an existing growth model together with rainfall intensity and changes in the R and C factors of the universal soil loss equation (USLE) erosion model enabled estimates of long-term erosion rates. Flood estimates were undertaken using regional rated catchments.The study found that stormwater diversions and banks on recontoured rehabilitated landforms, if constructed to currently accepted completion criteria, would likely fail within 30 years and with the likelihood of failure steadily increasing thereafter. The change in likelihood of failure was able to be estimated and could be applied to the determination of residual environmental risk for approval of a surrender application involving rehabilitation. The USLE model showed that long-term erosion rates increased as a consequence of climate change from north to south across the Queensland mining precincts. Because the growth model did not consider carbon dioxide fertilisation affects, results would likely be worse-case.Likely climate change outcomes have consequential residual environmental risks of mining project rehabilitation failure. This increased risk may result in increased payments to the state from mining projects where high consequences exist. The liability to the state and risk to the environment can be avoided if today’s completion criteria address tomorrow’s climate change impacts.CITATION:Evans, M C, 2014. Queensland mines should consider climate change impacts for decommissioning, in Proceedings Life-of-Mine 2014, pp 535–562 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 16, 2014

This Bureau of Mines report reviews the development of the world potash industry. The trends leading to the present market situation of oversupply arid low prices, which threaten; the domestic potash industry, are presented and analyzed. Because the major threat to the domestic industry comes from Canadian imports, the report focuses on the comparative economics of United States and Canadian production. The study resulted in these major conclusions: 1. Balance of world supply and demand is foreseeable in 1975, but it could be delayed by planned expansion. 2. Balance of U.S. supply and demand could occur as early as 1974-75 or as late as 1981. 3. Nearly all U. S. production capacity vis-a-vis Canadian competition is now uneconomic. Prices cover out-of -pocket costs for only 30 percent of U.S. production. 4. U.S. producers will be undersold by Canadians in 60 to 90 percent of the U.S. market. Canadians also will have the edge over United States and European producers in export markets. 5. U.S. firms have invested in 60 percent of the planned 1971 Canadian production, and they have large holdings in Saskatchewan. 6. The decline in the U.S. potash industry probably reduced personal income in Carlsbad, Eddy County, N. Mex, the chief potash-producing area in the United States, about $21.5 million between 1966 and 1969.

Jan 1, 1970

By S Nkwanyana, I Govender

Batch experiments in a 0.6 m diameter mill have shown that improvements of about 13 per cent in the efficiency of energy utilisation can be realised in ball mills by replacing 25 per cent of the ball charge by an equivalent volume of cost-free critical size pebbles from AG/SAG mills. For a mill of a given size, speed and charge filling, the rate of size reduction of ore particles depends on (i) the frequency of grinding media collisions (ii) the probability of capture of ore particles between the colliding grinding media (iii) the probability of fracture of the captured particles. The probability of fracture depends on the magnitude of collision energy. The distribution of collision energy into shear and impact events determines the relative strengths of attrition breakage and impact breakage. The efficiency of energy utilisation depends on which of the two mechanisms of breakage is more desirable in a particular milling stage. In this paper collision data from a series of DEM simulations of a mill charged with steel media and a mixture of steel media and pebbles is presented in energy spectra and spatial distribution maps. The data provides the necessary detail to elucidate the improvements in the efficiency of energy utilisation in ball mills when using a mixture of pebbles and steel media.

Aug 24, 2022

Researchers, medical organizations, statisticians, and others often use data on the nature and rate of occurrence of occupational diseases in directing their efforts and plans. Very often this information is developed from the reports of the States which describe the nature of work¬men's compensation claims and awards and the frequency with which they are made. To be meaningful, the statis¬tical information must be viewed in the context of the State laws involved. There is considerable variation among the laws of the different States. The Bureau of Mines has responsibilities for protecting the health of persons employed in the mineral industries and for the development of useful mineral products. To assist the Bureau in the accomplishment of its objectives, this compilation has been undertaken. For the benefit of the mineral industries, and any others who may have a similar interest, this volume is made available. An earlier compilation of the Bureau of Mines on this subject was published in 1952.4 However, during the intervening years, sufficient changes have been made in State laws to warrant completely recompiling the information. This publication includes the laws of the States, the District of Columbia, Puerto Rico, and the Virgin Is¬lands through 1964. Only those portions of the workmen's compensation laws which apply to or as ' related to occupational diseases are presented, and in each case enacted additions to and deletions from the basic law have been incorporated into the text of the law, thus snak¬ing it unnecessary to search out the various amendments made each year.

Jan 1, 1967

By C. Anderson, H. Huang, P. Miranda, E. Dahlgren, I. Chandra, M. Jeffrey

The latter part of the 20th century saw great advances in the treatment of refractory gold ores coupled with increased reliance on the use of cyanide for gold processing. Now, in many parts of the world, there is social pressure to limit or eliminate the use of cyanide. As well, treatment of some refractory ores or concentrates which have excessive cyanide consumption, gold cyanide pregrobbing or significant sulfide content remain difficult. This paper will outline the history of the development of alkaline sulfide leaching as an ancillary process to nitrogen species catalyzed (NSC) pressure leaching. Electrochemical fundamentals and the applicable thermodynamics of the alkaline sulfide hydrometallurgical system will be outlined. As well, examples of refractory gold recovery with alkaline sulfide hydrometallurgy such as an arsenopyrite gold concentrate application, a chalcopyrite gold concentrate application, a pregrobbing gold ore application, and a cyanide consuming gold ore application will be delineated in this paper.

Jan 1, 2005

By A. L. Mular

Some specific cases of the collection of data from industrial grinding and classifying operations, and the development of models from the data so obtained, will be described. The problems encountered, the effort involved, and the value of the derived models in improving the plant efficiencies will be discussed and documented where possible.

Jan 1, 1971

By Walter K. Utt

The vibration levels of the heavy machines used in surface mining are much greater than for vehicles used on highways. In order to assure the proper functioning of electronic equipment placed on the surface mining vehicles, the U.S. Bureau of Mines has conducted a program of field measurements to define their vibration environment. The information in this report is for a class of vehicle that has a blade for scraping and wheels with rubber tires. The statistical information derived from these measurements can be used as a basis for laboratory testing to qualify equipment for a surface mining vehicle of this class. The envelope that would encompass 99 pct of the vibrations encountered in normal operations is presented for each location on the vehicle. The five locations for which data were recorded are the floor of the cab, the engine, the frame, the drive train (gear, differential, and torque converter), and the axle. Tabulated data are provided for those who wish to use a different probability level. The appropriate test profile for the laboratory testing can be determined from the information presented in this report.

Jan 1, 1993

By Robert L. Kranz

Mining-induced microseismicity data collected by the U.S. Bureau of Mines in a hard-rock mine were analyzed for spatial and temporal patterns that might prove useful for prediction of rock bursts or assessment of rock mass damage changes. Pattern attributes described and illustrated in the previous report (part 1) were applied to the study of aftershock sequences associated with two different stopes. The aftershock sequences were spatially and temporally fractal, and the fractality was maintained for up to 16 h following a sequence progenitor. This suggests mechanical interdependency among the after-shocks. No statistical difference was found in the distributions of fractal dimensions when comparing two different stopes or when comparing aftershock sequences initiated by blasts or bumps. This suggests a lack of sensitivity to both stress perturbation mechanism and local damage states. However, differences between the two stopes were found in other sequence attributes that support inferred differences in the magnitude of stress concentrations and damage near each stope, and over time as a stope is developed.

Jan 1, 2010

By T. R. Jolley

This publication describes the control of fires in inactive coal deposits in the Western United States, including Alaska by the Bureau of Mines. Material presented should contribute to a better understanding of the purpose, process, and benefits of the program. Forty fires were extinguished or controlled in the Western United States and Alaska from 1948 to 1958 under a national program directed by the Bureau's Health and Safety activity. Thirty-five fires were controlled by smothering; three were controlled by the isolation method; and two were extinguished by removing the burning coal, smothering it with incombustible material, and backfilling the fire zone. The fire-control projects were distributed as follows: Alaska 2, Arizona 1, Colorado 9, Montana 9, New Mexico 4, Utah 2, and Wyoming 13. The total cost of the 40 fires extinguished or controlled was $1,203,957. Of this cost, 12.8 percent was engineering and administrative and 87.2 percent was contractual services.

Jan 1, 1959

By William T. Reid

Low-temperature carbonization of coal in Japan served as an important source of liquid fuels during the war. Six plants operating in Japan Proper produced 203,069 KL (53.7 million gallons) of liquid fuel from 1940 until the end of the war in August 1945, while four additional plants in Karafuto and Korea produced 211,943 KL (56.0 million gallons) for a total of 415,012 KL (109.7 million gallons) of liquid products. Semicoke produced in these plants was used for domestic fuel, for gasi- fication in portable gas producers on automotive vehicles, and to replace imported low-volatile bituminous coal in the manufacture of metallurgical coke. Since 1936 one plant had produced more than 300,000 metric tons of semicoke for blending with bituminous coal to form coke, while the total production of semicoke since the beginning of the industry in 1923 is approxi- mately 2,000,000 metric tons. Despite an apparent annual carbonizing capacity of about 2,000,000 metric tons of coal for the entire country, the maximum amount of scmicoke produced during the peak year, 1943, was 468,446 metric tons. The equipment used is primarily of Gorman design. Just before the end of the war, 6 plants using 20 Lurgi carbonizers were operating with a total rated capacity of more than 1,500,000 metric tons of coal per year, while 2 Koppors units had a combined annual rated capacity of 400,000 metric tons of coal. One plant using the Japanese-designed Mimura system was in service but with so much mechanical trouble that its output was small, while in another plant 4 Wanisht carbonizers of Japanese design but based on an early German development were running satisfactorily, and carbonizing about 100,000 metric tons of coal per year. A single installation of 15 American-designed Knowles ovens was operating near Tokyo but was carbonizing pitch for electrode carbon. ..! No true low-temperature process used in Japan could carbonize strongly. caking coals satisfactorily. The Mimura process designed for this purpose was unsuccessful, as was the Shimomura process before it, while the Lurgi, Koppers, and Wanishi systems operated only with noncaking or very weakly caking coals. The Knowles ovens, really a medium-temperature process, could carbonize-caking coal without difficulty...

Feb 1, 1948

By N Herault

PT Freeport Indonesia recently completed preproduction development and construction of the Big Gossan underground copper and gold mine, located in the Ertsberg mining district of Papua, Indonesia. Production has commenced with an expected ramp-up to full production of 7000 tonnes per day in 2012. The Big Gossan utilises an open stoping mine method with paste backfill.In order to deliver ore to the mill, which sits in a valley above the ore deposit, an underground production shaft and hoisting facility was designed and constructed as the key component of ore haulage. The design and construction of the Big Gossan shaft posed many challenges to the project team. Available shaft design and construction expertise were limited as this was the first shaft of its kind in Indonesia and the project was undertaken during a time of high industry demand for new shaft systems. Construction resources were also limited due to the remote location and competition with existing, producing mines for these resources and skills. The project also taxed the ability of Freeport to provide services and resources to this as well as their other projects.Completion of the Big Gossan shaft was a milestone in PT Freeport Indonesia’s plan to fully transition ore production to the underground environment in this decade.This paper deals with the various challenges faced by PT Freeport Indonesia and shaft contractor, PT Redpath Indonesia, during the construction of the Big Gossan shaft and offers suggestions to improve future shaft projects of a similar nature.

Mar 21, 2011

By Laurence Whitty-Léveillé

Proper handling of the radioactive fraction associated with the production of rare earth elements (REEs) in the mining industry is essential for a sustainable environment and human health. Actinides, such as uranium and thorium, have similar chemical properties to REEs, and are often co-dissolved in current hydrometallurgical processes. This causes radioactive contamination of the infrastructure through the extraction cycle. The present study optimizes, through experimental design, a sequential leaching procedure with Na2CO3/NaHCO3 and HCl for the rapid and selective dissolution of REEs and actinides. Optimization focuses on the main operating parameters (time, temperature, and concentration); different types of minerals, REE composites, and ores; on achieving maximal leaching yield; and on minimizing dissolution of the gangue metals (Fe, Si, and Ca). The final sequential procedure was rapid (1 h), effective, and led to the segregation of Th, U, and REEs with limited dissolution of the gangue metals.

By Cynthia Belt

"Before energy can be saved in the materials industry, the process must be understood. At the same time, baby boomers are starting to retire. New people are entering the field without experience and training especially in methods to save energy. Various classroom courses, seminars, books, software, and websites are available for the professional to better understand the industry with the ultimate goal to reduce energy use. This paper is a review of what is currently available with some comments on potential needs.IntroductionEnergy use is high within the materials industry. For the United States, the primary metal industry uses 8% of all energy used in manufacturing (Figure 1 )1 or 1, 736 trillion BTUs per year. Sadly, while energy use is high, energy management is not universal within the industry. Counting both internal programs and external such as the utility supplier, equipment manufacturers, federal and state programs, only 66% of primary metals companies participate in an energy management activity1.For the materials field, process heating is the majority of the energy use in a plant2. Understanding and optimizing process heating is a critical need for materials energy professionals. Surprisingly, process heating is not necessarily the work addressed within an energy program. The U.S. 2006 Manufacturing Energy Consumption Survey (see Table 1) found more primary metal companies addressing lighting with 31 % participation versus 15% with process heating work even though energy used in lighting tends to be a minor (in the range ofl-3% ofa typical plant's energy use)."

Jan 1, 2013

By Xun Zhang, Hang Qiu, Andrea R. Gerson4, Shaomin Lei, Yubiao Li, Yu Meng, Zhenyu Pei, Min Lin

Efficient separation of trace muscovite from the surface/interface of quartz grains was accomplished during oxidizing calcination and catalytic pressure leaching of the hydrothermal quartz. Experimental results suggest that 98.97% or more of the muscovite was separated when quartz sand was calcined at 900 °C for 5 h and then leached by hydrochloric acid and ammonium chloride solutions as substitutes for leaching agents containing fluorides. The chemical processing techniques show high selectivity in purifying quartz sand by transforming mineral muscovite into active structures during oxidizing calcination, and then dissolving the active substances during catalytic pressure leaching