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By David E. Nicholas

Design of underground openings is becoming more critical as the mine deposits become lower in grade, initial investments increase, ore depth increases, additional safety regulations come into law, and increased ore recovery is required for conservation of minerals. Stability of these openings is dependent on the strength of the rock mass and the pre-mine stress field. The rock mass is composed of solid blocks of rock (rock sub- stance) and structural features (faults, joints, bedding, etc.). Methods of testing the rock mass strength are improving and be- coming more common, however it is difficult to justify the high cost of large scale testing for an initial mine design. An alternative to testing the rock mass is to measure the rock substance and the structural features separately, and then combine them to estimate the rock mass strength. The rock mass strength will vary depending on the orientation of the opening with respect to the structural features. The other factor affecting the stability of underground open- ings is the pre-mine stress field. Methods are available to measure "directly" the pre-mine stress in competent and relatively massive rock. These methods are costly to employ, therefore, they may not be justified in an initial study. The pre-mine stress field can be estimated based on the structural relationships formed from past tectonic events.

Jan 1, 1976

By G. V. Campbell, O. T. Holdsworth, M. G. Nelson

A senior design project is required by all accredited mining engineering degree programs. Often referred to as the capstone of a student’s education, this project is expected to include all the important components of the preliminary economic assessment of a mineral prospect, including orebody modeling, grade and reserve estimation, selection of mining and processing methods, preliminary mine design, access and utilities, environmental compliance and reclamation, and financial analysis. Two of the authors (Campbell and Holdsworth) completed a senior project in 2021. They analyzed the Akie zinc deposit located in Canada. This paper summarizes the economic analysis portion of that project. The two primary objectives of this economic analysis were risk reduction and integration of economics and engineering. Addressing risk is important as risk is one of the primary concerns in mining investments. Risk reduction was the primary concern through the entirety of this economic analysis. Integration of financial analysis and engineering design was the first component of a risk reduction design. This allowed for financial and engineering design to be optimized in conjunction with one another. This produced benefits from both a financial and an engineering prospective. From a market, economic, and financial risk perspective, risk was reduced by forecasting multiple metal price scenarios, and then addressing the Akie project’s economic viability at each price point. Lastly, risk was address through consideration of nontraditional financing options. The project also sought to minimize financial and human capital risk, by proposing mutually beneficial cooperative social relationships and favorable work, schedules. Description of that work is not included in this paper.

Mar 2, 2022

By Keith G. Wallace

The effect of face resistance on ventilation air leakage through stoppings was measured in a twin development heading. Face resistance was varied by alternately tightening or loosening the face line brattice to change the line brattice leakage. Results indicated that tight brattice lines are necessary to maintain acceptable airflow at the face but result in higher leakage throughout the entire system, reduced overall ventilation efficiency, and higher operating costs. Conversely, a low face resistance which simulated an auxiliary fan/duct system gave reduced stopping leakage losses, higher quantities of air at the last open cross-cut and greater entire system efficiencies

Jan 1, 1984

By S. C. O?Brien

This paper develops the procedure for simulating the special locked-cycle Work Index laboratory test using the kinetic parameters obtained by conducting standard size-mass balance (SMB) grinding tests and presents the results for three materials - quartz, a taconite iron ore and a bituminous coal. It was found that the WI could be determined by simulation; however, if a material breaks abnormally, a full description of its abnormal breakage is necessary. It was also found that the sensitivity of the WI test procedure to the sieving process and the estimating of the 80% passing size of the sieve undersize is sufficient to question the practice of quoting a WI to two or more decimal places. Finally, if a material grinds abnormally in the Work Index mill, then the WI test should not be conducted.

Jan 1, 1987

By T. A. de Almeida, M. de Paiva Bueno, M. Powell

The mining industry is one of the foundations of modern society, providing not only the raw materials needed to maintain a contemporary lifestyle, but also serving as a basis for the development of future technologies. From the most basic components of an appliance to the materials needed to design an electric car or a space rocket, each raw material has gone through a painstaking procedure of extraction and processing, and ways to make this process more efficient will be of great help to meet an ever-increasing demand for minerals. One of the biggest challenges when extracting mineral resources is to measure the variability of the mineral body prior to processing. Comminution is the most power-demanding stage, and the lack of geometallurgical testing, often for financial reasons, may result in an inefficient operation. The Geopyörä Rock Breakage test was developed with the objective of making mineral variability data more accessible by providing both standard comminution parameters and rock mechanical properties at low cost, and with a modest sample size, allowing a larger number of samples to be tested to reduce uncertainties and assure productivity. The objective of this paper is to present the results of an extensive validation of this new rock breakage method against two of the main tests currently in use, namely the SMC® and Bond ball mill work index tests. More than 100 samples have been tested and the results compared, showing that the new method can accurately estimate the parameters of the traditional tests. This confirms that the new test is a reliable tool for comminution and geometallurgical tests.

Feb 1, 2023

By David Conover

The El Boleo Copper Project is currently in the final design stages for development of a 3-MM-tonne/yr underground copper mine located in Baja California, Mexico. The nearly horizontal mineralized zones are amenable to exploitation by conventional mechanized coal mining technology using continuous miners, shuttle cars, and belt haulage. The mine design resembles a typical full-extraction coal mining operation utilizing a sequence of mains, sub-mains and production panels. Due to numerous faults, mining will be conducted as several small adjacent mines accessed through adits from large arroyos cutting through the mine area. Up to four seams may be mined in some areas with a maximum overburden depth of about 250 m. The ore zone is relatively weak and plastic, subject to extensive creep over time. The mine workings will pass through areas of historical shortwall mining panels where the ground has flowed into old entries and gob areas, and then reconsolidated. A small test mine was developed to evaluate mechanical cutting performance, roof-bolt anchorage capacities, roof and pillar stability and caving behavior. In-mine measurements were combined with two- and three-dimensional FLAC models to evaluate alternative development and production pillar designs. The paper will discuss the various factors influencing ground stability at the El Boleo project and the strategies employed in developing a suitable ground control design.

Jan 1, 2009

By Michael Hood

Subsidence profiles above two adjacent panels in Illinois are compared with pro- files predicting subsidence behavior obtained using the (i) National Coal Board (NCB, 1975) method, (ii) the profile function method and (iii) the influence function method. The NCB method predicts the maximum subsidence values at the center of the troughs accurately, but, the overall shapes of these predicted profiles do not match the profiles from the measured data well. Consistent values for the angles of draw were measured but these angles were different in the transverse (average value 43 degrees) and in the longitudinal (average value 17.5 degrees) directions. Time dependent subsidence effects are shown to be small but measurable. These displacements continue at a linear rate for at least a 12 month period. A comparison of measured horizontal distances, interpreted as horizontal strain, and the NCB predictions for strain shows that the peak measured strains are greater by a factor f about four than the predicted strains. The relationship between surface curvature and strain is investigated. Problems associated with calculation of surface curvatures from vertical displacement data are highlighted and a recommendation is made for future studies to consider direct measurement of this parameter. Surface curvatures above a moving face are found to be about three times less than the curvatures at the stationary end of the panel. On the other hand, a hyperbolic tangent profile function is shown to serve as an accurate predictive tool for subsidence behavior in two adjacent longwall panels at Old Ben Number 24 mine in Illinois. This function predicts not only the vertical displacements but also the surface curvatures above both panels. Influence functions are shown to be more problematic, although potentially more flexible, in their application than the profile functions.

Jan 1, 1982

By M Ali, E Satriawan, M Napitupulu, A Munandar

The Deep Mill Level Zone (DMLZ) panel cave mine is one of three active caving mines at PT Freeport Indonesia’s Grasberg Underground Mining Complex. The DMLZ mine is located at a depth of approximately 1,500-1800 m below the surface, making it one of the world’s deepest panel cave mining operations. This depth results in both high in-situ and induced stress that acts on the hard and massive rock mass, triggering rockburst conditions. As a result of the bursting conditions, ground support and maintaining the support capacity are an essential part of operating the DMLZ mine in an efficient and safe manner.

Apr 26, 2022

By Joel Lööw, Johan Larsson, Stig Vinberg, Malin Mattson Molnar, Mats Jakobsson, Jan Johansson

The mining industry is undergoing rapid transformation, driven by technological advancements, sustainability concerns and demographic shifts. This transformation will put more younger people in management positions. This study provides valuable insights into the leadership behaviors of younger and older managers within a large Swedish mining company, highlighting the importance of managerial experience and targeted training programs to foster effective leadership, particularly in the context of change management. The findings emphasize the need to create work environments that support managers to develop their leadership, contributing to improved employee well-being, operational efficiency, and adaptation to the changing demands of the modern mining sector.

May 1, 2025

By S. W. Arambur

INTRODUCTION "Mujeres Roca" is a program developed by OMA in association with the Chamber of Commerce Canada Peru inspired in “Women who Rock”, a Canadian initiative to promote a greater participation of women in the mining industry. The program includes a coaching workshop called “Kallpa Warmi”, that means “Woman Strength”, to reinforce basic skills and values and 8 mentoring sessions with top executives of the mining industry who share their experiences and knowledge with a group of 10 selected young professional women from around the country. HISTORY OMA is a nonprofit association founded in 2014 dedicated to contributing to the education of low-income university students with high academic performance in careers related to mining and earth sciences. Our mission is to empower the future professionals by strengthening their soft skills and enhancing their capacity to become leaders and agents of change in their own regions. The Chamber of Commerce Canada Peru has a long-standing commitment to gender equality and promotes women participation in male dominated industries. As it is well known, the mining sector is and has always been key to Peru’s economy, representing about 10% of the country’s GDP. Thus, mining can contribute significantly to our economic development and we believe that women can make a positive difference. A study prepared by PwC and "Women in Mining” provided indicators on the advantages that mining companies have when including women in their executive’s positions. These indicators sustain that when a mining company includes women in its management staff, its net profit increases by 6%. This information clearly shows that women participation is not only a matter of human rights and gender equality, but of productivity and profitability. Nevertheless, the mining sector has the fewer number of women on boards of any industry group in the world. Having this in mind, OMA decided to expand its activities and create together with the Chamber of Commerce Canada Peru, the program “Mujeres Roca”, in order to inspire and attract young women to the mining sector, a traditionally masculine industry. The program also aims to encourage mining companies to more actively recruit and keep women in their boards. The program was launched in 2016 within the framework of EXPOMINA PERU, the largest international mining exhibition that take place in Lima every two years.

Jan 1, 2019

By JUAN DIAZ, Kray Luxbacher, Steven Schafrik, Dionissios T. Hristopulos, Zach Agioutantis

Methane gas is emitted during both underground and surface coal mining. Underground coal mines need to monitor methane gas emissions to ensure adequate ventilation is provided to guarantee that methane concentrations remain low under different production and environmental conditions. Prediction of methane concentrations in underground mines can also contribute towards the successful management of methane gas emissions. The main objective of this research is to develop a forecasting methodology for methane gas emissions based on time series analysis. Methane time series data were retrieved from atmospheric monitoring systems (AMS) of three underground coal mines in the USA. The AMS data were stored and pre-processed using an Atmospheric Monitoring Analysis and Database Management system. Furthermore, different statistical dependence measures such as cross-correlation, autocorrelation, cross-covariance, and variograms were implemented to investigate the potential autocorrelations of methane gas as well as its association with auxiliary variables (barometric pressure and coal production). The autoregressive integrated moving average (ARIMA) time series model which is based on auto-correlations of the methane gas is investigated. It is established that ARIMA used in the one-step-ahead forecasting mode provides accurate estimates that match the direction (increase/decrease) of the methane gas emission data.

Aug 2, 2022

By Robert Hochscheid

A patent issued to J.N.J. Leeman (1957) described the change in performance that takes place when a cyclone is installed in the horizontal position rather than the vertical position. Although this patent was directed more toward improvements that could be realized in the heavy medium cleaning of coal, it contained specific references to reducing the quantity of fine solids that would report in the underflow, and an example for fine sand classification is also included. The three cyclone installations for which data is given in this paper demonstrate that horizontal mounting of large cyclones can improve classification efficiency, eliminate some operational difficulties, and reduce cyclone maintenance requirements in closed circuit grinding installations. Cyclone Experience at Serrana S.A. Each of four grinding circuits at the Serrana S.A. de Mineracao Apatite flotation plant in Brazil have a 2.7 X 4.6 meter (9 X 15 foot) rod mill and each originally operated in closed circuit with two vertically mounted Model D20B (500m nominal diameter) Krebs Cyclones. New feed size is 25mm. The Apatite is liberated at a relatively coarse 35 to 28 mesh grind, but the 500mm cyclones had to be fed at 66 pct. solids in order to obtain an overflow analyzing 12 pct. coarser than 42 mesh. Because dilution water in the cyclone feed had to be limited, classification was inefficient, and there were other significant circuit difficulties as summarized in a recent article by C. A. Busnardo (1984):

Jan 1, 1985

By Ronald L. Wiegel

In the 2000 page Handbook of Mineral Dressing by A. F. Taggart, the subject of material or metallurgical balances is covered in only six pages of eve-straining type. Although Taggart's work was compiled before 1945, and there has been significant progress since then in most areas of mineral processing, the practicing metallurgist's approach to metallurgical balances remains exactly the same as described in those six pages. There are several portions of Taggart's text appropriate to introduce the subject of this paper which I would like to quote: "Milling Calculations. Computations of per¬formance in milling are complicated by the fact that it is a continuous rather than a batch operation, that the quantities of solid materials handled are large and usually mixed with water, hence difficult or impos¬sible to weigh. Fortunately it is possible to determine many facts concerning perfor¬mance without knowing weights, if the value of various constituents is known in some common unit, e.g., the content of some par¬ticular metal or mineral, or of water, or some ingredient soluble therein, or of par¬ticles of a particular size or falling within some particular size range, or the like."

Jan 1, 1979

By William Gleason

"While the American Exploration & Mining Association (AEMA) was preparing to close one chapter and begin another during its annual conference in Spokane, WA Dec. 3-7, word of a significant victory on an issue that has been important to the association for many years came from the halls of Washington, D.C.During a keynote address on Dec. 6, Joe Balash, assistant secretary of Land and Minerals Management for the U.S. Department of the Interior (DOI), told a sold-out lunch crowd that the DOI had released final drafts of proposed revisions to the Obama-era greater sage grouse conservation plans. The revisions suggest removing hundreds of thousands of acres of federally protected habitat in Utah, and easing restrictions on energy development and other activities, including mining, in Colorado, Idaho and Wyoming.The protections of the sage grouse were put in place by the Obama administration in 2015. The sage grouse, a prairie fowl, is considered by conservationists to be a key indicator species for the health of America’s sagebrush ecosystem. The previous plan to protect the ground-dwelling bird imposed restrictions to development in sage grouse habitat, but did not place the birds on the endangered species list — a move that many believed would have imposed far more rigid rules.AEMA, and its executive director Laura Skaer, led the way in the fight against the Obama-era greater sage grouse plan, arguing that the plan unnecessarily hurt economic development.“We were the first organization to point out that the greater sage grouse was being used to stop mining, oil and gas production and grazing on public lands in the interior mountain west,” said Skaer who is retiring from AEMA with a significant legal win on this front. “Early on, we cautioned that the proposed Land Use Plan Amendments would be worse than a listing (of the sage grouse) under the Endangered Species Act. Very few believed us until they saw the plans with all of the restrictions and the recommendation for a 4-million-ha (10-million-acre) withdrawal from mineral entry. We were the only organization that filed comments on all 88 Land Use Plan Amendments in 11 states covering more than 24.2 million ha (60 million acres).”"

Feb 1, 2019

By A. J. Kwitowski

Teleoperation is a technology that can provide significant health and safety improvements in mining, by relocating machine operators hundreds of meters away from the face area. The U. S. Bureau of Mines (USBM) has recently developed a teleoperation system for continuous mining and haulage equipment. This system features near-real-time closed-loop control. A prototype system was developed and demonstrated on the surface. This system could be used in thin-seam applications down to 914 mm. Details are provided on the developed teleoperation system, results of testing, and expected, future applications of this technology for improved safety.

Jan 1, 1994

By R. J. Miller

The current National commitment to expanding the human presence into the solar system will clearly require major facilities in Earth orbit or possibly on the moon. Such facilities will need large amounts of materials for structural modules, life support, propulsion, and shielding. The heavy transportation costs in fuel required to lift materials from the Earth's surface make a terrestrial-based space system inherently inefficient. A more cost-effective approach would be to provide as much of the required materials as possible from other bodies in space not having the high cost of Earth launch. This paper identifies potential targets for space-based resource utilization, constraints on exploitation, and relative benefits of various sources.

Jan 1, 1992

By Alan C. Richter

Introduction The East-West Gateway Coordinating Council is an organization of local governments formed in 1965 to identify regional problems and to formulate policies, plans and programs to resolve them. The major goal of the Gateway Council is to improve the quality of life for the citizens of the St. Louis Region. While East-West Gateway Coordinating Council is the organization I represent and it only deals with the St. Louis Metropolitan Area, you will find one or more similar organizations in each of our nation's urbanized areas. As a result, for illustrative purposes, I will use my organization to portray what is happening nationwide. For example, in order to eliminate duplication, the Council reviews local applications for approximately 100 federally funded programs in such areas as highways, mass transit, parks, water treatment, and sewers before they can be sent to the appropriate funding agency. The Council's varied functions place it in a unique position of receiving more and more responsibility for developing strategies of implementation of various environmental regulations. This is due to the fact that environmental control is a relatively new field and we, as a country, are relatively inexperienced. The resulting regulations and guidelines will depend, to a great extent, on what the general public is willing to accept in terms of controls and what price they are willing to pay in terms of taxes and increased costs. Land Use: Growth vs No Growth This is perhaps the most encompassing environmental issue. We, as a nation, are beginning to realize that land is a limited natural resource and that the way we choose to use 'this resource affects many other aspects of our lives--whether we can catch edible fish in the Mississippi, how much we pay for sewer services, if we can swim in a

Jan 1, 1977

By J. E. Garlanger

Each year, Florida mines approximately 40 million tons of phosphorite, most of which is ultimately converted to various commercial fertilizers. The phosphorite is mined from within the bottom portion of the 40-to 60-ft. thick surficial aquifer, using open pit mining techniques. The ore zone or "matrix" is generally overlain by relatively permeable fine sand to silty and slightly clayey fine sand. The ore itself is highly variable in nature but, in Central Florida, typically consists of less permeable clayey phosphatic sands and sandy clays with stringers of permeable sand. The ore is much more sandy in the north Florida mining area.

Jan 1, 1990

By Alan Boughey

The world's largest grinding mill operates at the Cadia Hill Mine in Australia. Svedala Industries supplied the 12.2-m- (40-ft-) diam, 20-MW Cadia gearless, semiautogenous grinding mill (SAG). This was a leap of more than 40% above the largest operating SAG mill. This article reviews the significant items involved in the development, design, manufacture, installation and operation of this mill. Description of the Cadia project The Cadia Hill Mine is located 25 km (15 miles) southwest of Orange, in the Central Tablelands of New South Wales, Australia. The mining lease covers about 3,100 hm2 (7,660 acres) of the Cadia Valley. The Cadia deposit is a large, homogeneous, low-grade, porphyry-type, gold-copper resource. Current reserves stand at 202 Mt (222 million st), grading 0.73 g/t (0.02 oz/st) gold and 0.17% copper. They contain 146.2 t (4.7 million oz) of gold and 347 Kt (382,500 st) of copper. The operation consists of openpit mining and ore processing to produce gold bullion and a gold/copper concentrate. The operation processes 17 Mt/a (19 millon stpy) of ore to produce 91 kt/a (100,300 stpy) of concentrate and 9.1 t/a (293,000 oz/year) of gold. The plant operates two 12-hour shifts a day and had a targeted availability of 94%. The plant facilities include a copper concentrator, o water supply system, an openpit mine, tailings pipeline and dam, and a concentrate pipeline and dewatering facility located in Blayney, about 35 km (22 miles) from the concentrator. Significant features of the process plant include o primary crusher and stockpile, a reclaim conveyor system feeding, the Cadia SAG mill (Figs. 1 and 2) and two 6.7-m- (22-ft-) diam ball mills (Fig. 3). A portion of the gold is extracted in a gravity circuit. The balance is extracted with the copper in the flotation section of the plant. Concentrate is thickened and piped about 35 km (22 miles) to the filter plant and rail loadout facility located in Blayney. Tailings are pumped to a tailings dam and process water is reclaimed from the tailings dam. The water system is designed to control and capture available runoff from local creeks, and to store these waters in dams and weirs. In addition, a major portion of the water for the process plant is treated effluent from the city of Orange and a smaller portion from Blayney Mill selection. The low-grade ore posed a dilemma for Cadia. To achieve a satisfactory economic operation, large-scale processing was required. The selection of the mills, equal to the largest designed and operated at the time, gave a plant configuration consisting of two 11.1- x 5.8-m (36- x 19-ft) SAG mills and three 6.1- x 9.1-m (20 x 30-ft) ball mills. This configuration did not provide the most satisfactory economic model for the project. A review of the single line configuration indicated that a significant reduction in the overall capital cost of the plant could be achieved by increasing the size of the mills and reducing the quantity. Increasing the size of the mills,

Jan 1, 2001

By Ben W. Burdett

The operation of an electrolytic refining tank house is an art as well as a science. If the electro-refining industry is to progress, a better understanding of the refining process is necessary. This would help to reduce the amount of training necessary to produce competent tank house operators who, in turn, would be able to increase both quantity and quality of the tank house product. To aid in understanding this process, quantitative relationships between the critical tank house variables must be established. The inherent major contributor to inefficiency in most tank houses is short circuits. By quantifying the effect of short circuits on each of the other variables in the system, as well as their effect on over- all system performance, better decisions regarding manpower allocation can be made. Current distribution under short circuit conditions, which has always been somewhat of a mystery, can be studied in detail. The relative importance of electrolyte balance, proper anode-cathode spacing, low contact resistance at points of electrical connection, and other system variables can be determined, With a better understanding of these variables, the steps necessary to increase current efficiency are more easily defined. Relationships between most of these variables are described in qualitative terms in the literature, but quantitative relationships between tank house variables have never been established. A realistic mathematical model of the tank house could be used to test the effect of variations in a single variable on other variables in the system, and thus define the quantitative relationships between tank house variables. It is not the purpose of this paper to establish these relationships, but to describe a recently developed model that can assist in their establishment. A computer program implementing this model has been applied to examine the effect of short circuits on overall current distribution. Some of the results are given here as examples of the utility of this program.

Jan 1, 1973