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By Loren G. Thompsen

The first high pressure grinding roll in a copper mine was commissioned at Cyprus Sierrita in July 1995. This grinding roll is the world's biggest operating unit. It has a roll diameter of 2.4 meters and a face width of 1.4 meters. It is driven by two, 2250 KW (3,000 HP) motors. This paper will discuss the development of the grinding roll at Cyprus Sierrita and what it has done for comminution of Sierrita ore. Maintenance and operating performance will be discussed as well as testwork including size reduction, power input, work index, and throughput.

Jan 1, 1997

By P. Somasundaran, F. F. Aplan

The Formative Years Douglas Winston Fuerstenau was born December 6, 1928 in Hazel, SD to Edwin Arnold and Hazel Pauline (Karterud) Fuerstenau. His father, of German extraction, was a farmer and, later, a cabinet maker, while his mother, of Norwegian lineage, was a school teacher. His parents are still alive today at ages 91 and 88, respectively. Two younger brothers, Richard and Maurice and a sister, Jean, completed the family. The family first lived near Watertown and later in Lemmon and Mobridge, SD. The 1930's were a difficult period for any family in South Dakota. A decade-long drought made this a part of the dust bowl, which together with a serious infestation of grasshoppers (the locust plague described in The Bible), and the world-wide depression, made living difficult for all. In spite of these privations, Doug has many happy memories of his childhood which can be attributed to the resilience of youth and a strong family structure. He has fond memories of summers spent with his cousins on family farms where the children were introduced to farm chores at an early age. When he was old enough, he worked in a grocery store after school. At the age of 14 he spent the summer hearding 2,000 sheep near Lemmon, SD as his contribution to the war effort in that labor-short period. He remembers well the dust storms of the 1930ts, the destruction at his grandmother's farm by tornado, pulling weeds on the farm, threshing grain with a monstrous steam-driven machine and such pleasant childhood activi- ties as fishing for bullheads, hunting for rabbits, searching for arrowheads in newly plowed fields, and ice skating in the winter. Early in life his parents instilled in him a strong work ethic, a love of learning and the need for a good education. In 1943, the family moved to Rapid City, SD. With a population of 13,000, it was

Jan 1, 1989

By K. Y. Haramy, B. T. Brady

A scale-invariant theory of the strength and deformability, of rock masses in static equilibrium and at incipient failure is proposed The theory provides a rationale, for designing structures in rock. This paper presents results of experiments conducted by the US Bureau of Mines and presents theoretical methods to determine and interpret the in situ strength of rock masses using the borehole shear tester.

Jan 1, 1996

By L. F. Zeiler

In the past, health concerns in coal mines have primarily centered on those elements which have been essentially inherent to the mining environment. These would include respirable coal mine dust, respirable crystalline silica, excessive noise levels, and diesel exhaust particulates. Commercially-available chemical products are prevalent on mine property. These potentially toxic materials are chemical formulations that can degrease, clean, and lubricate metal parts, separate coal from rock in float/sink operations, and aid in roof consolidation, among other uses. As the general public has become more aware of the hazards of chemical exposures, miners have likewise become more concerned about working with an ever-expanding variety of chemical products on the job. Often, product or chemical specific hazard communication training is inadequate or ineffective, and miners do not know exactly what the ingredients are in the products they handle, or the health hazards involved with their use or misuse. Currently, the Mine Safety and Health Administration (MSHA), by law, enforces 1972 Threshold Limit Values (TLV). MSHA is making preparations to adopt new personal exposure limits for enforcement. The values given throughout the article are 1994 TLV's and are not enforcement standards, but are used for discussion purposes. They reflect the current scientific thinking regarding personal exposure to these chemical agents. An overview of these products is presented, and the potential health hazards associated with their use are discussed. Controls needed to prevent overexposures, such as proper handling procedures and personal protective equipment, are covered. Methods used to collect and identify contaminants are presented.

Jan 1, 1995

By H. Wu, V. Izaxon

Intensive ventilation is required during the excavation of a mine opening and the subsequent exploitation of the mineral resources. The exchange of heat between the ventilation air and the rock mass has a major influence on the thermal regime of a mine, especially in the initial segment of the airway. In frozen ground, heat flow into the rock mass from the ventilation air can result in the eventual thawing of the permafrost, which can result in roof-rock instability. This paper presents a mathematical analysis of the dispersion process of ventilation-induced heat by thermosyphons placed on the surface of the mine. The principal uses of thermosyphons in the Arctic are to reduce the ground temperature to prevent potentially unstable permafrost from thawing and to increase the bearing strength of the material. The mathematical model of the physical problem, generally known as "the Stephan problem," takes into account the varying thermo-physical properties of air and the frozen and thawed rock mass, the thermal properties of the freeing fluid in the thermosyphons and the phase change of water. Finite-difference techniques were employed to determine the temperature isotherms around the thermosyphons. It was found that two rows of thermosyphons on a 10- x 10-m grid provide an acceptable design spacing for reducing the ground temperature around the mine airway.

Jan 1, 1997

By H. L. Ehrlich

Marine manganese nodules harbor a mixed population of manganese-oxidizing and -reducing bacteria, as well as bacteria that do not act on manganese. They also host phagotrophic protozoa. Out of several laboratory studies, one line of investigation indicates that some kinds of bacteria found on nodules can catalyze the oxidation of Mn2+ bound to Mn(IV) oxide at the surface of nodules at in situ temperature and pressure. In the absence of appropriate bacteria, the rate of oxidation of the surface-bound Mn2+ is significantly slower. How Fe(III) is incorporated is still unclear. Base metals such as Cu, Ni and Co, which are usually found in marine nodules in various quantities, may be incorporated through scavenging by Mn(IV) oxide. Laboratory evidence shows that some other bacteria on nodules can reduce the Mn(IV) oxide to Mn2+ in the presence of an appropriate source of reducing power in the form of organic carbon. The reduction of Mn(IV) oxide mobilizes manganese and trace metals such as Cu, Ni, and Co in the nodules. These bacteria reduce Mn(IV) whether oxygen is present or not. They could be harnessed in the bioleaching of nodules. The manganese(IV)-reducing bacteria and the bacteria that neither oxidize nor reduce manganese are thought to keep the organic matter in the nodule environment sufficiently low to favor bacterial manganese-oxidation, which in laboratory tests is inhibited by excess organic carbon. The preying by the protozoa on the different kinds of bacteria is thought to control the bacterial population on nodules and ensure continued growth of the manganese-oxidizing bacteria and the nodules. To eliminate interference from seawater salts in the bioleaching of Mn, Cu, Ni and Co, it may be more advantageous to use terrestrial Mn(IV)-reducing bacteria than the Mn(IV)-reducing bacteria resident on nodules. The terrestrial bacteria would allow bioleaching in fresh water. Unlike the marine bacteria, most terrestrial bacteria studied to date reduce Mn(IV) oxide only anaerobically. A general outline for an anaerobic bioleach process of marine nodules with freshwater bacteria is discussed.

Jan 1, 2000

By Lennart Malmqvist

Decision-making in exploration deals with experience, knowledge, and sometimes faith, but very often financing and profit, mineral resource aspects, employment, and general political ambitions are parts of the scene. At one end of this spectrum, there is the prospector and his decision on the actual project. The exploration business now expands from its pioneering phase for the benefit of a single company to a wider spectrum which includes the benefit of the large mining consortium and a national development program. Its objectives are also to maintain employment and to favor long-term stability in a mining district or a mining company. The prospector then has new aspects and questions to consider such as, what to do in mining districts where there is a shortage of ore resources but there are still useful investments in mines, processing plants, etc. To analyze the exploration process, therefore, seems to be of great importance in a time of rapidly changing conditions. As in other areas of complex decision-making, for example, in the fields of investments, of production, and of the armed forces, computers most certainly have an important role to play in future exploration decision-making systems. However, we must first analyze our own business as closely as possible to find out what kind of information we need, i.e., why we recommend an exploration program as a good or a poor one. An important part of the debate about exploration is the case study. Case studies on exploration are few and most of those written are only about successful exploration programs. Where are the case studies of the failures and the not so successful programs? Every prospector knows that the majority of exploration projects fail. Consequently, the most important experience seems to be hidden in the failures.

Jan 1, 1979

By K. Norrena, E. Magri

An important problem in mine operations is the classification of material as waste, low-grade stockpile and ore. This classification must often be made with blasthole data that are widely spaced and that have sampling errors. Geostatistical-simulation techniques combined with basic economic principles allow a procedure for classification that maximizes the expected profit. Geostatistical-simulation methods (Gaussian, indicator or annealing-based) allow the integration of hard and soft data in the creation of alternative, equally probable realizations of the mineral grades. At each location, for each realization one calculates the "profit" if the block were to be classified as ore or waste. The optimal classification is the one that maximizes expected profit (a maximum profit selec¬tion or MPS procedure). In this paper, the authors discuss the theoretical justification of the method and implementation details. The use of blasthole data from different types of mineral deposits, that is, different levels of continuity, are considered. The authors also show the efficacy of the procedure with different levels of sampling error. The increased revenue due to the MPS procedure and improved sampling is shown. The paper shows the geostatistical-simulation procedure and the uncertainty in block grades that result from incomplete and imperfect sampling. The optimal classification is presented. Optimal block classifications are transferred to realizable dig limits by hand-drawing polygonal boundaries. The results of the proposed method are compared to classification based on kriging. Limitations and areas of future work are identified.

Jan 1, 2000

By Xintan Chang

A computer software package, named CFIRE, for the general ventilation network analysis and fire control, mine fire and/or coal spontaneous combustion, has been developed at Xian Mining Institute in China. It is a multipurpose package with adequate capacities of ventilation map drawing, ventilation network analysis, gob fire simulation, steady state ventilation simulation and transient state ventilation simulation. It was written in a user-friendly style, driven by menus, facilitated by on-screen messages and supported by the allowance of user interferences. CFIRE has used up-to-date research findings focussing on the practical needs of coal mines. This paper discusses briefly also the relevant theoretical principles on which this package has been perceived.

Jan 1, 1989

By Richard R. Klimpel

In this paper, the old and the new commercially available reagent chemistries for the improved flotation of sulfide minerals will be summarized. The reagent classes discussed are those that meet three criteria: 1) they are being commercially used and/or large scale plant tested in North America in the last few years; 2) they are clearly different in chemical structure than commonly used commercial reagents of the last few decades and are not simply mixtures of existing reagents and/or simple changes in cation, alkyl group size, etc. and 3) the structural formulae are clearly specified in the public literature.

Jan 1, 1994

By R. S. Kramer

A bulk compositional chemical analysis often provides incomplete information to help the mineral processor when faced with the problem of removing troublesome contaminants in low concentrations. Michigan Tech has developed a unique approach for addressing this problem. A combination of Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and image analysis was successfully used to characterize the species responsible for phosphorus contamination of less than . 05 weight percent in iron ore. An automated routine acquired the chemical signature of each particle on a back scattered electron image. The few particles containing phosphorus were identified from the hundreds of particles examined, and the phosphate phases present were easily characterized.

Jan 1, 1993

By Stephen P. Harrison

The ventilation of coal mines has long been a major challenge for the mining industry. Prior to the 1969 Health and Safety Act, mine ventilation planning was almost entirely handled by individuals in mine operations and engineering who had extensive practical experience. Their background and expertise was sufficient to deal with existing ventilation problems and planning. A recent decline in the number of qualified individuals combined with more stringent state and federal regulations have necessitated a thorough engineering oriented approach to ventilation in mine planning design. To plan for an existing mine, a thorough ventilation survey must be conducted to determine the capabilities of the existing ventilation network. A ventilation survey also provides considerable useful data for long range planning. Essential information such as friction factors, entry resistance, and potential ventilation problem areas is gained from the survey data. With this information a comprehensive computer analysis can be conducted to evaluate alternative mine plans. This evaluation of mine plans is essential to minimize the number of shafts required while still maintaining the quality of mine ventilation. Using an existing mine as an example, this paper outlines a detailed procedure for organizing, con-ducting, and evaluating a ventilation survey. In addition, specific ventilation problem areas are isolated and alternative methods for their solution are considered. Furthermore, a long range mine plan is evaluated and the most feasible variation of the plan is selected.

Jan 1, 1980

By Chris Lynagh, Collin Schroeder

Determining the best excavation method is a critical step in successful tunnel construction. In rock tunneling, several factors can dictate the excavation method, such as: (1) rock characteristics, (2) tunnel size and length, (3) nearby utilities/infrastructure, and (4) contractor’s preferred means and methods. This paper discusses the various rock tunnel excavation methods utilized on the Doan Valley Storage Tunnel Project (DVT), a project constructed as part of the broader Project Clean Lake in Cleveland, Ohio. The differences between each method’s initial and final lining, geology, and cycle sequence will be analyzed and compared.

Jun 13, 2023

By D. W. Hendrickson

Cliffs views the process as extending from mine planning to cargo loading including auxiliary systems such as material handling and plant utilities. Process automation is recognized as an area that can provide significant improvement opportunities with less capital requirement than major flowsheet modifications. This paper discusses the development and results of a strategy to allow and promote implementation of process automation improvements at individual mines based on their economic priorities taking advantage of common systems and concepts for use at multiple mines where practical. Specific process control upgrade projects a Hibbing Taconite Company and the Empire Mine are reviewed in detail.

Jan 1, 1998

By Z. T. Bieniawski, D. A. Newman

The Geomechanics Classijication (RMR System) (Bieniawski, 1979) was modified for entry and roof support design in underground coal mines. Adjustment multipliers were introduced to incorporate the influence of high horizontal stresses and the roof support reinforcement into the existing classification system. Sixty- two case histories of standing and fallen mine roof were collected from two mines in the northern Appalachian coalfield. Twenty-seven engineering and geologic parameters were recorded for each case. A partial correlation analysis was carried out on the cases to establish which parameters have a significant im- pact on the stand-up time of supported coal mine roof. Survival analysis, a statistical technique used in medical research to assess the effect of a drug or treatment on a patient's life expectancy, was conducted together with stepwise multiple regression to derive values for the adjustment multipliers. A practical example is included to illustrate the application of the modified Geomechanics Classification to underground coal mine design.

Jan 1, 1987

The absence of coal face particle management practices heavily penalizes coal transportation from initial loading to final consumption. Penalties include dust problems, significantly reduced mine loading cycle productivity, mine belt spillage, excessively high coal preparation costs and chute and dangerous pulverizer blockages at the final point of utilization. The common environmental and economic enemy is fines. Everyone knows that fines cause safety and environmental dust problems, but few understand that fines also swell broken coal to a point where 5 to 15 percent more time and capacity must be used to deliver the same tonnage. In this paper, methods and rewards for reducing and/or managing fines at the mine face are discussed. Computer-based loading cycle model productivity estimates, viewed from a new perspective, are made on the basis of material volume rather than on the long established and frequently misleading basis of tonnage. After all, it is typically the volume of broken material being transported that defines the capacity of a given transportation system, while the corresponding tonnages are merely a reflection of the specific material densities. Published evidence suggests that the swelling of broken coal can be decreased very significantly using small quantities of certain non-frothing chemicals added to mine face spray water and/or by employing improved mine face breakage practices. In a future paper, the effects on transportation productivity beyond the coal mine will be discussed.

Jan 1, 1994

"Foreword by Ren BryceSenior engineer, Freeport-McMoRan, Oro Valley, AZ, USAThe eighth annual Mineral & Metallurgical Processing Division (MPD) student poster contest was held in February at the national SME Annual Conference & Expo in Denver, CO. A total of 33 students presented their work at the poster competition. The competition started in January when the students submitted a one-page abstract for judging. In February, they prepared and presented a poster that explained their research. A panel of judges went to each student and listened as the students explained their research in five minutes.The students worked hard at their research and then set aside time to complete all the necessary steps to enter the competition. The MPD recognizes the effort required to enter and as a result, provides monetary rewards to all participants. The first-place winner receives $1,000; the second, $500; the third, $250; and the fourth through seventh, $200. All remaining students receive $100. All of the students also receive a complimentary ticket to the MPD Luncheon. As in past years, there are separate levels of competition for undergraduates and graduates.Graduate winnersKaustubh Shrimali won first place for researching “The influence of starch in amine adsorption by quartz in the reverse flotation of iron ore.” Venkata Atluri received second for studying “The effect of polysaccharides on bubble attachment at talc surfaces.” Jennifer Galvin placed third for investigating “A novel approach to alkali pug bake for the extraction of rare earth elements from monazite concentrate.” In the fourth through seventh places were Amy Richins, Sumedh Gostu, Brett Carlson and Chris Vass.Undergraduate winnersNestor Santa earned first place for exploring “Copper recovery from waste printed circuit boards.” Cassidy O’Connell received second place for conducting “Performance analysis of CMC in high talc copper sulfide flotation systems.” Catalina Vanegas won third place for examining “Cyanidation tests and pretreatments to recover gold from a refractory ore in Colombia.” Kylie Boyce, Michael Archambo and Pritam Sinha were in the fourth through sixth places.Everyone benefits from attending the student poster competition. The students are able to display their work to future employers, and industry professionals can talk to up-and-coming engineers. Next year, there will be another competition for more posters and networking. Come and enjoy the event and the posters."

Jan 1, 2017

By R. P. Stahura

In many ways, conveyors are the lifeline of mining and processing operations. Like arteries in the human body, they continuously supply materials to and carry finished products and waste away from vital on-going operations. And like arteries, when the conveyors are running with less than maximum efficiency and productivity, it spells serious trouble for the operation's overall health. Inefficient conveyors suffer carryback, leading to the build-up of materials on idlers and other expensive components. They spill and leak material at loading zones and conveyor transfer points, causing accumulations that can damage the belt, wear moving components, and increase both clean-up labor and maintenance expense. They wander or mistrack, spilling material and endangering personnel and conveyor components including the belt itself. And through these inefficiencies, they multiply the operation's hidden costs. These added expenses are created in lost production, increased downtime for service and maintenance, and the cost of the replacement of prematurely worn equipment. In addition, the attitude that inefficiency is "good enough" is recognized elsewhere in the organization; as a result, other departments relax or operate at less than peak performance. Quality goes down and with it employee morale.

Jan 1, 1992

By M. E. Kuchta

Research is currently being conducted at the Colorado School of Mines in the use of high-pressure water for scaling down loose rocks in underground mine openings. In addition to improved miner safety, the adhesion strength of shotcrete applied to rock surfaces treated with high-pressure water is also increased significantly, resulting in improved overall support capabilities of the shotcrete layer. Test results show an increase in adhesion strength by a factor of four on a concrete test wall cleaned with water at 21 MPa (3,000 psi) as compared to a surface cleaned at 0.7 MPa (100 psi).

Jan 1, 2003

By Christopher Haycocks

Subsidence induced innerburden shearing and stress fields, whether active or passive, frequently contribute to significant ground control failures in overlying seams. In this paper proven multi-seam technology is used on upper seams to forecast and quantify the magnitude and severity of damage and the increased mining risk due to interaction. Increased upper seam ground control problems are demonstrated using hazard mapping which provides a viable technique for utilizing damage predictions in design.

Jan 1, 1986