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By Harry Holle, Gary Johnson

A plant trial was conducted at the Paddy's Flat plant of Dominion Mining Limited with the aim of comparing the ef evenness of oxygen and hydrogen peroxide as leaching oxidants. The Paddy's Flat plant is designed such that the leach train can be divided into two parallel streams, allowing the same or lurry to be eated in two identical trains. By effectively ehminatmg the influence of the ore variations on the results subtle differences in the performance of the two reagents hav been identified. . . The results of the plant trial indicate that the two reagents act m different ways, and that each may be more suitable than the other _for _the treatment of certain types of ore. In some cases a co bmation of the two reagents may be the most cost effective option. . or t e same chemical conditions in the leach pulp, including dissolved oxygen levels , the reagents achieve different gold leaching rates, and in some cases different ultimate leach extraction.

Jan 1, 1992

By B. K. Mishra, R. K. Rajamani, P. Songfack

Primary grinding in SAG mills is gaining more importance with respect to the conventional crushing, rod and ball milling operations. This is due to the reduced operating costs generated by lower steel consumption. However. SAG milling is inherently susceptible to more severe risks and problems since it attempts to combine several stages of the conventional crushing and grinding into a single stage. This paper analyzes the SAG milling operation by predicting the motion of rocks and steel balls. The well-known discrete element method (DEM) is used to calculate the trajectories of individual entities, and their collision with one another. A computer code previously used for studying the motion of grinding media in ball mills is enhanced to handle the interaction between heavy spherical steel balls and light chunks of rocks, usually ellipsoidal in shape. The DEM based software called MILLSOFT can animate the charge motion for different design of liners. A case study of a 9.75-m diameter SAG mill is presented and the effects of lifter bar height and configuration on the overall dynamics of the charge are discussed. Also the effect of spacing between liners on lifting the charge is presented. This new approach has a large potential because it shows in detail the effect of each design or operating parameter on the performance of SAG mills.

Jan 1, 1998

By Claus Becker

Waterbearing, cohesive or non-cohesive grounds with glacial stone deposits are found very often in Europe. The problem consists of destroying the boulders and supporting the face simultaneously. At the example Grauholztunnel Bern ( outer diameter 11,60 m ) the theoretical attempt of solutions for the big machines is described: destroying of the boulders with roller discs, hydraulical support of the front. The problem of coming out of stones of a certain size from the surrounding matrix will be discussed. Further diminishing to the size that can be handled by pumps is executed by a crusher, situated in the center of the machine. At the same example the theoretical attempt for headings in cohesive soil with stone deposits are shown. Surface structure of the cutting wheel and working chamber as well as controllable current movements are the solution here. The danger of clogging discs and stone crusher has to be encountered by right positioning of the tools and jetting nozzles. At the example Sewer MoosstraBe Salzburg the same problems are discussed for the Mikro-Tunnels. The pipe-jacked sewer lines have outer diameters from 485 and 805 mm. With this method, the stones have to be holed through. The wear of the cutting tools determines the [ ]

Jan 1, 1989

By C. Orf. Chukabarah

Acoustic pollution (noise) is a significant mine environmental system problem. The U.S. Bureau of Mines (USBM), Environmental Protection Agency (EPA), Department of Labor (DOL) and other researchers have all performed contributory research on noise in mining environments. The present study addressed the problem of unavailability of a computerized, practical, routine, user-friendly, and user-editable, prose-styled application program with which one can determine (a) the noise exposure indices among mine workers, (b) mine system noise exposure level on time-weighted average basis, and (c) predictive relationships among mine workers' age, prior exposure to abnormal noise levels, prior auditory pathologies and the risk/degree of mining-induced hearing impairment. Results showed that such a program ("NEIL") is accomplishable. Additional results revealed that most U.S. mines operate within the statutory noise exposure levels. Furthermore, the mine worker's age was statistically confirmed to be the main predictive risk factor for mining-induced occupational hearing impairment.

Jan 1, 1992

By Theodore H. Eyde

The porphyry copper province of the southwestern United States and northern Mexico, is the largest copper producing region in the world. Most of the deposits occur in Arizona which now produces over 54% of the newly mined copper in the United" States. As the many recent discoveries are brought into production, Arizona's share of the nation's copper production will increase. The term "porphyry copper" as used in this paper includes all deposits of generally low grade disseminated copper mineralization amenable to bulk mining techniques. Therefore, copper deposits such as Pima-Mission, Twin Buttes, and Vekol where the copper mineralization occurs principally in the intruded rocks will be considered as "porphyry copper" deposits. Most of the deposits have been discovered since World War II, consequently, the southwest, and particularly southern Arizona is perhaps the most intensively explored area for copper deposits on earth. Most of the major natural resource companies in the United States and Canada maintain exploration offices in southern Arizona. To illustrate the success of exploration efforts, the location of porphyry copper deposits either known or producing prior to World War II are shown on figure 1 and the deposits discovered since World War II which are either in production or in the exploration and development stage are shown on figure 2.

Jan 1, 1973

By Thomas M. Turner

Open pit mining, always a demanding task, faces two relatively new problems today: 1. Availability of equipment. Moderate to large draglines can take as long as 6 years from date of contract to date of operation. 2. Environmental restrictions. Strip mining in the minds of environmentalists compares unfavorably on the scale of social desirability to the activities of Jack the Ripper and Attila the Hun. Specifically, lowering of the water table to allow strip mining in the dry is being looked upon with increasing disfavor. The modern dredge offers relief in both problem areas. Delivery on a major dredge might run 18-24 months rather than 60; and lowering of the water table is precluded, thus minimizing environmental objections. In addition, a lower first cost and potentially increased efficiency may offer real advantages to the miner who is forced away from his traditional mining methods. This talk is dedicated to acquainting the miner with dredge types, advantages, and limitations.

Jan 1, 1975

By J. F. Kvitfkovich, R. L. Bate

Coal production in the Central Appalachian region has a long history, and it remains a major US coal-producing region. The coal industry consensus is that the region is in a state of decline as evidenced by the recent lower regional output. Are Central Appalachian coal reserves adequate for the region to continue as a major supplier of low sulfur coal? To answer that question, this paper focuses on the Central Appalachian coal reserve base estimates and production trends. Central Appalachian (CAPP) reserve evaluations face the difficulty that there are no publicly available databases that provide a thorough analysis of remaining CAPP reserves. Based on best available Energy Information Administration (EIA) data, a coal reserve estimate of 17.6 billion tons is developed. This estimate appears high according to industry perception. Recent United States Geological Survey (USGS), and other state agency coal reserve estimation projects are evaluated as alternative approaches to the re-serve estimation problem. Using the conclusions from these studies, the CAPP reserve base is estimated at 7.1 billion tons. Another perspective on the CAPP reserve base is provided by reserve holdings of major CAPP operating companies reported at 5.2 billion tons. A conceptual mining cost analysis indicates substantial price increases will be necessary to offset this deterioration in the economic viability of the reserve base.

Jan 1, 2004

By C. J. Hall

An investigation of multi-shaft airflow problems by the author in 1976 (1) was presented in the hope of arousing considerable written comment, but in fact-. only one contribution (2) was forthcoming. The investigation in this paper is taken several stages fur¬ther, because the matter is of major importance in many American hard rock mines with complex networks extending over thousands of meters vertically. The examples used have all been generated thermodynamical¬ly and checked by motive column (denisty) calculations. Dry air has been used to reduce the amount of time spent on the rather complex calculations, but it has been shown (3) that the principals developed apply equally well to air/vapor/water mixtures. Initially the subject is investigated using both thermodynamic and motive column analyses. The latter part of the paper concentrates on a motive column presentation. Both methods are, of course, equally valid and give identical answers to any situation when correctly applied, as is shown in the worked examples.

Jan 1, 1980

Throughout the 1970s, the US Bureau of Mines rode an ebb tide in Washington political circles. In rapid fire succession, the agency lost its mine health and safety enforcement responsibility (1973), a large portion of its energy research responsibility (1975), and then its fuel statistics functions plus a sizable portion of its coal R&D (1977). By 1978, johnny-come-latelies in the Energy, Labor, and Interior Departments had siphoned away from the Bureau some $125 million in program responsibilities as well as 900 of its employees. The bruising decade came to a close with a Department of Natural Resources proposal that, in its original form, would have scattered the Bureau’s responsibilities to the winds. There is no doubt in my wind,” said Lindsay Norman, acting director of the Bureau of Mines (see box), “that were the Bureau to continue down the path it was on, the next step was closing the doors and going out of business.” The doors are still open, but erosion of responsibilities had a devastating effect on the resources available to fulfill the Bureau’s mission. Devastating,too, in terms of internal morale, considering the Bureau had six directors in a 10-year span. “When the troops are in the trenches and are being shot at,” Norman said, “they need a leader—hopefully, a permanent one— that can get them advancing. This is something the Bureau did not consistently have in the 1970s.” In September 1978, Roger Markle climbed aboard as director of the Bureau to rejuvenate the 70-year-old agency. He resigned only six months later* but the program Markle set in motion is being carried through by Lindsay Norman. Since Norman’s appointment as acting director, he has spent considerable time on the road explaining his agency’s redefined goals. At one such stop in Duluth, Norman and his two deputy directors, Charles Kenahan and Mike Kaas, answered the following questions.

Jan 6, 1980

By Jean-Michel M. Rendu

Increasingly, geologists use geostatistical methods to evaluate drilling programs. The complexity of the methods varies with the nature of the available sample information, the objective of the statistical analysis and the geologist's experience. Occasionally, estimating the average sample grade is all that is required. In other instances a semivariogram calculation may be considered. If sufficient data is available, the geologist may wish to estimate blocks or panels of complex shape, using the kriging method of evaluation. Historically, the use of geostatistics by geologists has been limited by a number of factors, most significant being the difficulty in accessing and using computer programs needed to complete the necessary studies. Geologists are often working in remote areas from which electronic communication is unreliable, if not impossible. Even when access to computer programs is technically possible, the costs incurred in accessing and using these programs are often considered prohibitive. In many instances using the programs requires an understanding of computer systems far beyond that which a field geologist can justifiably be interested in acquiring and maintaining.

Jan 1, 1984

By Raj K. Singhal

Three principal activities are involved in planning and developing a surface mine. These are 1) definition of economic and technical feasibility, 2) design, procurement and construction, and 3) mining and reclamation. The last is the only activity which begins in the feasibility study and continues throughout the life of a mine. It is also the activity which depends heavily on use of computers. This paper deals with a method of selecting mining software and dwells on the recent progress, made in this area. Discussed also is the status of computerized equipment management and information systems: a microprocessor based technology applied to dispatch systems, monitoring of equipment health and performance, wireless data transmission to a centralized data processing unit, and mine- wide information and reporting system. Reference has been made to upcoming developments which offer the potential- of transforming the surface mine of the year 2000 into a "manless pit". Canadian achievements in all of these areas have been highlighted at appropriate places in the text.

Jan 1, 1989

By Eleanora I. Robbins, Motoaki Sato

Many problems associated with acid mine drainage (AMD) are caused by the complex way molecular oxygen (O2) oxidizes reduced matter at surface temperatures. In aqueous solution, O2 kinetically "prefers" to go through the formation of hydrogen peroxide (H2O2) as an intermediate. Being innately unstable, H2O2 is quickly decomposed back to water and oxygen in the presence of dissolved Fe and Mn, both catalysts for the decomposition. Direct addition of H2O2 to AMD produced similar results. Ozone (O3) is a much faster and stronger oxidizer than either O2 or H2O2. In the laboratory, O3 rapidly precipitated Mn, Fe, Ni, Co, Pb, and Ag even in acidic solutions. The experiments indicate that AMD can probably be processed with ozone and metal oxides/hydroxide recovered in flow systems using only septic-tank-size reactors and small sedimentation ponds.

Jan 1, 2000

By David A. Holmes

Zeolites are crystalline, hydrated aluminosilicates of the alkali and alkaline-earth metals. Their crystalline framework is based on a three dimensional network of SiO4 tetrahedra with all four oxygens shared by adjacent tetrahedra. The alkali and alkaline-earth cations are loosely bound within this framework structure and may be exchanged, to varying degrees, with other cations or molecular water. Most zeolites can be reversibly dehydrated. At present, close to 40 natural zeolite minerals have been identified and over 100 zeolites have been synthesized. Zeolites are a family of hydrous aluminosilicate minerals whose physical properties provide unique features for a wide variety of practical applications. Zeolites have been known for more than 200 years, but it was not until the middle of this century that their economic potential and widespread occurrence in sedimentary rocks were known. Since 1950, literally thousands of articles and patents have appeared in technical literature, and commercial pro¬duction of natural zeolites may now exceed 1 Mt worldwide an¬nually. In the past 40 years, the zeolite mineral group has changed from that of a museum curiosity to one of an established industrial mineral commodity. According to Breck (1974), zeolites are characterized by the following properties: 1) High degree of hydration, 2) Low density and large void volume when dehydrated, 3) Stability of the crystal structure of many zeolites when dehydrated, 4) Cation exchange properties, 5) Uniform molecular-sized channels in the dehydrated crys¬tals, 6) Ability to adsorb gases and vapors, 7) Catalytic properties. All zeolites are molecular sieves, but not all molecular sieves are zeolites. Activated carbon, activated clays, alumina powder, and silica gels are also molecular sieves. Molecular sieves are materials that can selectively adsorb molecules on the basis of their size, shape, or electrical charge (Clifton, 1987). Commercial application of zeolites is based on the following physical properties: molecular sieving, ion exchange, adsorption, and catalysis. Potential commercial utilization includes hundreds of possible applications. The principal uses at this time, however, are as fol¬lows: -Ammonium-ion removal in waste stream treatment, sewage treat¬ment, pet litter, and aquaculture, -Odor control, -Heavy metal ion removal from nuclear, mine and industrial wastes, -Agricultural use, such as soil conditioner and animal feed supplement. An estimated 800 kt to 1 Mt of natural zeolites were produced and consumed worldwide in 1991. Eight small operators reported collective production and consumption of an estimated 18 kt of natural zeolites in the United States during 1991, mostly for feed additives and for odor control, aquacultural, agricultural, catalytic, and ion exchange applications (Eyde, 1992).

Jan 1, 1994

By Paul C. Miclea

With the growing urban population and the concern for traffic congestion and pollution (emissions control), public transportation is becoming more and more attractive to both city dwellers and managers. To gain access to the central area of the city, the sub- way remains the most viable alternative, despite its higher cost when compared to above ground or elevated transportation systems. There are relatively few regulations and criteria for subway ventilation, particularly when compared with mine ventilation. The main document that provides guidance and general recommendations for subway ventilation and environmental control is the Sub- way Environmental Design Handbook, published in 1976 (2nd edition) by the U.S. Department of Transportation, Office of Re- search and Development. Many of the subway systems in existence today have been designed and built with ventilation features adequate for normal train operation, but their design does not consider stringent criteria for such emergency conditions as a train fire in a tunnel. The National Fire Protection Association's Standard for Fixed Guideway Transit Systems known as NFPA 130 as well as the ASHRAE Handbook - HVAC Applications (1995) provide specific design and operation requirements for subway ventilation systems. Some of the existing, old subways are upgrading their ventilation systems to comply with the new regulations. The ability of a particular ventilation system design to provide adequate ventilation during normal and emergency conditions can be evaluated using computer modeling and simulation techniques. A train fire will cause a sudden change in the tunnel ventilation pattern by adding an unsteady and fast-growing source of heat. The hot air and gasses created by a fire will tend to flow uphill, possibly against the normal flow, producing a 'backlayering effect." To prevent this effect from happening, enough ventilation must be provided and the governing criterion to establish the required airflow is called 'Critical Velocity." Several software packages are available for special applications on tunnel and station ventilation as well as to model the spread of smoke and heat in case of a major tunnel fire, using Computational Fluid Dynamics. This paper presents the current issues in subway ventilation, as shared by the public transit community around the world, together with modern alternative design concepts vis-à-vis the more stringent emerging Fire-Life Safety criteria. Examples of recent studies and ventilation systems design are provided.

Jan 1, 1997

By P. T. Luckie

The selectivity curve -- a continuous function which predicts the expected proportion of feed material of a particular size that will appear as coarse material -- is the preferred model for describing classification. In a previous paper (I), the authors presented a technique for determining the selectivity curve of a classifier from experimental data. The separation process is defined by a binomial distribution of the form [ ] where s(x), the probability of particles of size x reporting to the coarse stream, is obviously the selectivity value for material of size x.

Jan 1, 1975

By Pierre Ollivier, Dominique Morin

A general study of gold refractory arsenopyrite pyrite concentrate bioleaching has been carried out including two continuous bioleach testworks at different sizes, namely one at a laboratory scale with a 100 1 unit at a 2 kg/d dry solid flowrate and the other at a pilot scale at a 100 kg/d dry solid flowrate. Both tests show a 80% bioleaching of arsenopyrite in about four days of treatment and with the same kinetic. Pyrrhotite is attacked at the earlier stage of the bioleaching but pyrite remains unaffected. The weak potential of oxidation associated with the decomposition of arsenopyrite and the abundance of arsenite leads to a high grade of elemental sulfur in the bioresidue which consumes the major part of the cyanide during the gold recovery, furthermore, the arsenite and ferrous produced in solution have to he oxidized to obtain a stable precipitate in the waste products and as outlined in previous works of other authors on this subject the addition of iron to obtain a Fe/As molar ratio at least above 3 is necessary. The agitation equipment used in the pilot unit allowed an optimisation study calculation for scaling-up the design and power requirements of an industrial installation, For the pretreatment of a gold refractory As high-graded concentrate the reagent cost has the greatest part in the operating cost of the biooxidation step due to the necessary retreatment of the biosolution, In that conditions the power cost is quite marginal, actually it is significant for the treatment of pure pyrite.

Jan 1, 1990

By William Gleason

With its 2011 acquisition of rival equipment company Bucyrus International, Caterpillar added underground mining and large shovels to its line of products and further solidified its standing as the leading mining equipment manufacturer in the world with solutions for every aspect of mining. When Caterpillar spent $8.8 billion to acquire Bucyrus, the global mining business was flourishing, as mining companies around the world worked to keep up with demands for nearly every commodity. Flash forward to 2013, and the global mining landscape looks very different. Lower demand for raw material from China and India and falling commodity prices have forced most mining companies to pull back on their production. The reductions from the mining industry have hit equipment makers like Caterpillar and Komatsu hard. In October, Caterpillar reported that its quarterly earnings had fallen 44 percent. The changing conditions have also changed the narrative from Caterpillar and other equipment makers to customers from offering solutions to move the most tons per hour, to now offering solutions for the lowest cost per ton. In September, Caterpillar hosted some of its mining customers and the trade press at its Tinaja Hills Demonstration and Learning Center near Tucson, AZ to talk about its range of products, from its MineStar System designed to help increase efficiency through better equipment management and planning, all the way up to the massive Cat 7495 and 7495HF electric rope shovel lines acquired through the Bucyrus takeover

Dec 1, 2013

By Greg Border

Many unique ventilation problems have been faced as Avery Island Mine's large openings have been mined. High humidity of outside air combines with the hygroscopic salt to create a corrosive atmosphere. Massive rooms preclude routine use of brattices to direct air flow to the working faces. Large amounts of explosives are consumed in single blasts. Resulting concussion pounds air control structures and ANFO ignition creates large amounts of nitrogen dioxide in single rooms. Geologic constraints confine new shafts and slopes to areas thought to be free of potential ground water hazards. Dust control techniques are limited by dry product demanded by customers. The Avery Island Mine's ventilation system has evolved to deal practically with the conditions and to dependably provide fresh air to the miners. International Salt Company's Avery Island Salt Mine, a multiple level room and pillar operation, has been mined steadily since about 1900. It is known as one of the "Five Island" salt dome mines of South Louisiana's Gulf Coast. Production from the area places Louisiana first in United States rock salt mined tonnage, according to the United States Bureau of Nines, 1982 (1). International Salt Company is a major force in U.S. salt production, as it also operates mines in Detroit, Michigan; Cleveland, Ohio; and Retsof, New York; a solar salt facility in Bonaire, Netherlands Antilles; and a solution mining plant at Watkins Glen, New York.

Jan 1, 1983

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by the National Institute for Occupational Safety and Health's Pittsburgh Research Laboratory. Investigated were a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal-extraction side of the longwall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. In laboratory experiments and in a longwall field evaluation, the translucent mesh barrier was shown to provide notable dust-control effectiveness for a distance of up to 60 m downstream of the shearer, provided that the mesh barrier remained relatively parallel to the airflow. The staged spray barrier system showed marginal dust-control effectiveness in the laboratory and, therefore, was not field tested.

Jan 1, 2000

By Cyrus W. Field

Chemical, mineralogical, and petrographic data have been obtained for suites of plutonic rock samples from the Guichon Creek Batholith of British Columbia and the Mineral-Iron Mountain-Sturgill Peak- Cuddy Mountain-Peck Mountain areas of western Idaho. Intrusions at these two geographically separate localities represent composite plutons ranging from early gabbro through quartz diorite to late grano- diorite and more silicic-alkalic phases. They are early Mesozoic (200 m.y.) in age, and contain porphyry-type mineralization in close spatial and temporal association with late-stage intrusions of porphyry, aplite, pegmatite, and (or) breccia. Country rocks are eugeo-synclinal assemblages of metasedimentary and metavolcanic greenstones of Permian, Triassic, and Jurassic age. The petrochemical evolution of these intrusions, and the effects of subsequent hydrothermal alteration and metallization, are illustrated by standard ternary diagrams of the major oxide and mineralogical data. Samples plotted on an AFM diagram suggest a calc-alkaline magma trend. However, their distributions on NKC and Qz-Kf-Pf diagram show well-defined trondhjemitic (Na20-rich) and tonalitic (quartz-rich) variants to this trend, which are similar in part to those reported for mineralized island arc plutons of the northern Caribbean and southwest Pacific, but which contrast markedly to those for continental plutons of the Bingham District, Boulder Batholith, districts of southern Arizona, and elsewhere.

Jan 1, 1975