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By J. C. Purcupile

In this time of increased coal demand, a faster and safer method for roof support is needed. This report outlines the preparation and testing of a machine which we feel will help answer this need. The results of the tests are encouraging, and indicate that further exploration of the method should be continued.

Jan 1, 1975

By Robert K. Jones

Filter media can be defined as that material which effects the removal of finely divided solids from a fluid. Thus the removal of dust from air or turbidity from water, for example, can be the result of passing the fluid through a properly supported filter media. Since filtration in one form or another has been practiced since pre¬historic times filter media have been made from an extremely wide variety of materials. Vegetable and synthetic fibers (used loose, or formed into papers, felts or cloth) sand, ground coal, diatomite, perlite, wire cloth, porous metal, and bonded aluminum oxide are among the more important materials used today.

Jan 1, 1961

By Leland L. Mink

Open-pit mining is sometimes conducted in areas where the artesian pressures contained in aquifers underlying the pit's floor are great enough to cause floor heave. In order to reduce this pressure several methods are commonly used. One of these methods is a pressure relief well or depressurization wick. The wick consists of a borehole which is filled with gravel and cased at the surface. The wick is allowed to flow freely, thus reducing pressure near its location. The spacing and depth of these wicks can be determined by a simple analytical and graphical technique which considers the weight of material overlying the aquifer and the artesian force within the aquifer. An example of the technique using data from a Colombian coal mine is presented.

Jan 1, 1986

By James J. Scott

Three dimensional photoelastic techniques have been developed which provide information on the state of stress at any point in a model investigated. This investigation utilizes these techniques to determine the stress distributions in the pillars and the roof of a room and pillar mine model. Castolite plastic was used for the construction of the model in which a stress pattern was developed by the stress freezing process. Analysis of the stress pattern was accomplished by use of data obtained by observing points in slices from the model with a polariscope and solving data obtained by' the shear-difference method. Slices through the centerline, edge of pillar and centerline of span were investigated. Results of this work provide information on the overall stress distribution on points of stress concentration in compression, shear and tension, show relative magnitude of stress throughout the model and indicate directions of the most important stress values. A generalized roof bolt pattern is developed for room and pillar mines based on the stress distribution. A digital computer was used in the reduction of data and proved to be extremely useful for investigation of this type.

Jan 1, 1963

By L. E. Garner

Aggregate resources should be considered primary factors in urban development. Resource planning is essential because land values, previous construction, or zoning restrictions often preempt exploitation of aggregate deposits within an urban area. Sequential land use practices allow development of areas prior to urban development. Population and aggregate consumption trends in Austin, Texas, indicate that substantial quantities of reserves will be lost to future development. Aggregate materials are present in nearby seas. However, a comparison of transportation and reclamation costs indicates that reclaiming land after mineral extraction can be significantly cheaper than transporting materials longer distances.

Jan 1, 1979

By J. Kallioinen

Theoretical considerations, experimental results and plant experience have lead to a new design concept called the unit reactor approach. It has been successfully implemented to the largest flotation cell on the market, the 4000 cu ft OK TankCell. The work has also lead to a new operating idea called size specific flotation. The paper discusses these concepts in the view of full scale field experiments. In large scale porphyry copper flotation experiments conducted in Chile the new large TankCell with its new low energy input Free Flow mechanism out-performed the more conventional designs. The recovery was substantially better, especially in the coarse fractions. In some experiments the difference in total recovery was up to 10%-units and the savings in total energy consumption at the same time over 40%.

Jan 1, 1995

By T. P. McNulty

During the last decade, many exhaustive studies have been made of process energy requirements for the production of various metals and materials. Some excellent technical papers and text books have resulted, and some of these are included in the bibliography of this paper. These studies were, of course, prompted by the economic pressures which resulted from the beginning of the "Energy Crisis" in 1973. Our intensified consciousness of the cost of energy led, then, to a greatly improved understanding of the energy consumption attributable to individual mining, processing, and refining steps. It is worth noting, however, that an awareness of the cost of energy is not new and that efforts to minimize this cost were an important part of sound mine and plant management practice throughout the earlier days of our industry. One only has to read a few accounts of mining operations around the beginning of this century to develop an appreciation for the cost of supplying wood, coal, fuel oil, or electric power to remote locations.

Jan 1, 1983

In 1989, United States mine production of barite decreased 13% while world mine production decreased by 8.6%, according to the US Bureau of Mines. Consumption, sold or used by grinding plants, decreased by 21.2%. And imports decreased by 12.8%. The value of domestically produced barite, fob mine, increased 17.4%, according to the Bureau. The declared value cif US port of all imported crude barite during 1989 increased from $38.10/t ($34.56 per st) in 1988 to $40.27/t($36.54 per st). Nevada continued to be the leading producer of barite with 77% of the total, followed by Georgia and Missouri. The Bureau of Mines estimates 75% of the domestic mine production was used as a weighting agent in drilling fluids. The remaining 25% was used in barium chemicals, glass, or as a filler. Most of the production from Missouri, Georgia, and Tennessee was used in the nonoilfield sector. Of the total consumption used by grinding plants and chemical manufacturers, it is estimated that 80% was used in drilling fluids. The other 20% was used in the non-oilfield sector, including barium chemicals and fillers in paper, plastics, and glass. The tonnage consumed in the drilling fluids market decreased due to the lower average rig count during 1989. The average number of rotary rigs operating was 869, 7.2% less than the average of 936 in 1988. Crude barite imports were down 12.8% from 1988. Imports accounted for 73.8% of the barite consumed (apparent) in the US. China continued to be the leading exporter of crude barite ore to the United States with 63% of total crude ore imports. India followed with 27.4%, Peru 4.3%, Chile 2.9%, and Canada and Mexico, each with 1.1 %. About 97% of the imported barite ore was used in the oilfield sector.

Jan 1, 1990

By Jerry M. Whiting, Landy A. Stinnett

The subject of this paper is broad and complex. Secondly, it is near and dear to the authors' hearts. Therefore, it doesn't seem possible to deal with every aspect of it in less space than a good size textbook. Also, if we dealt with all of the basics of feasibility studies and report preparation, we would cover a lot of material available in the literature, and would have to minimize our editorial comments. In view of these limiting realities, we have chosen to discuss selected facets of the subject, and to provide several comments which stem from our personal experiences during the past 20 years. "Think Ahead" hen someone is undergoing training to command a large ship, the following short phrase is engraved in his memory: "Think Ahead." The reason is simple enough. A battleship, aircraft carrier or oil tanker cannot change directions quickly, and if one waits to a what the other ship is going to do, there may be twisted metal and bodies scattered all over the ocean floor. The commanding officer has to use radar, forward rind aft lookouts, experience, common sense, intuition, weather forecasts, and everything else available to him to avoid trouble. Remember the USS Stark, and the fate of its captain? The fact the Stark was hit by a "friendly" missile didn't lessen the damage. How about running into a mine? Is it an excuse that no one thought about the possibility of a minefield ahead of the ship? The point is, relative to feasibility studies, that its prospective authors, and especially the commander of the efforts required to create it, must "think ahead" from the moment of their association with 4 mining activity. They must

Jan 1, 1987

By Nora M. Hutt, Kevin A. Morin

Geochemical static tests are a basic component of geochemical assessments and predictions for acidic drainage, and include acid-base accounting and total-metal contents. A key database for such information is the International Static Database (ISD), which currently contains more than 45,000 static-test analyses from over 200 minesites. Such large databases are useful in identifying general trends and, just as important, the percentage of exceptions. General trends and significant exceptions can be seen in the ISD by comparing one parameter against another. This paper shows that bulk neutralization potential (bulk NP) obtained from acid titration is often a good indicator of neutralizing capacity above values of 10 t CaCO3/1000 t. Other types of calculated neutralizing capacity are then compared to bulk NP to determine if they, in fact, reliably represent actual neutralizing capacity and if they can substitute for the more time-consuming and expensive bulk NP. For example, bulk NP correlates better with Carbonate NP (from carbonate analyses) and Total-carbon NP (from total-carbon analyses) than with (Ca+Mg) CaNP (from solid-phase analyses of calcium and magnesium). This means that, in general, (Ca+Mg) CaNP is a less accurate substitute for bulk NP than the other types, and thus requires intensive site-specific justification if a substitution is attempted. This also means that measurement of the frequently less-expensive parameters of total carbon and carbonate can often substitute, within site-specific error bars, for the bulk-NP titration. However, the ISD also shows that non-carbonate minerals make the primary contribution to neutralization in up to 20% of samples, so Carbonate CaNP and Total-carbon CaNP do not always reveal the full neutralizing capacity of a sample.

Jan 1, 2000

From a gathering storm of climate change based legislation that could potentially overwhelm the mining industry, to the nuts and bolts of mineral processing and just about everything in between, about 100 mining and mineral processing professionals heard it at all at the 60th annual Colorado MPD Meeting April 22-24 at the Broadmoor in Colorado Springs, CO. With a sweeping agenda under the banner ?What in the world is new in mining and metallurgy? attendees were treated to four sessions and 21 presentations that covered the range of mining industry issues. Bill Reid, president, chief executive officer and director of Gold Resources Corp., spoke about his company?s El Aquila gold project in Mexico. With five projects in Mexico, Gold Resources Corps. is aiming to become a low-cost gold and silver producer. Its flagship property, the El Aguila gold project, is a high-grade gold and silver property with significant base metal credits of copper, lead and zinc. Production of the El Aguila project was targeted for mid-2009. Reid said that three high-grade deposits have been discovered at the El Aguila project. They include the high-grade ?manto? style El Aguila openpit deposit, the El Aire high-grade polyme-tallic vein system, which is underground, and the underground La Arista high-grade polymetallic vein system. The project is located 120 km (75 miles) south-east of the capital city of Oaxaca, Mexico. Reid said the property has yielded several exceptional gold and silver surface samples, including a 36-g/t (1.1 oz/st) gold sample and a 3,100-g/t (90 oz/st) silver sample. Other properties that Gold Resource Corp. has are:

Jul 1, 2010

By Daniel J. Turk, William R. Banning, John Paterson, Thomas J. Weitz, Michael L. Clark

Introduction Pegasus Gold's Montana Tunnels mine is a large surface gold, silver, lead, and zinc mine located 37 km (23 miles) south of Helena in southwestern Montana. Milling operations commenced in late March 1987. The concentrator achieved full production in May that year after undergo¬ing several modifications and improvements. Production for 1988 is projected to be 2.48 t ,80,000 oz) of gold, 34.2 t (1.1 million oz) of silver, along with 8.5 kt (9400 st) of lead, and 22.6 kt (25,000 st) of zinc from lead and zinc concentrates. Mill throughput currently averages 11.7 kt/d (12,900 stpd), compared to the origi¬nally designed capacity of 11.3 kt/d (12,500 stpd). Cash production costs, net of bypro¬duct revenues for the third quarter 1988, were below $3.20/g ($100 per oz). The introduction of ore to the concen¬trator marked the culmination of 12 years ex¬ploration, evaluation, and development. Initial milling operations encountered diffi¬culties with the circuit as designed. As a result, several modifications and improve¬ments were made to the plant. This article is intended to assist other companies developing projects of this type and complexity. It discusses the mine's de¬velopment from feasibility and construction through start-up. The operation, as it exists today, is reviewed including the modifica¬tions and improvements made since start-up. History The mine is situated in Jefferson County, MT within the historic Corbin-Wickes min¬ing district. Underground mining began in 1864 and flourished until the early 1900s. Between 1864 and 1900 the vein deposits in the district produced about $41 million dol¬lars worth of lead and silver ores containing subordinate amounts of zinc, copper, and gold. At various times, three smelters were operated in the area.

Jan 1, 1989

By Harry M. Conger

Good afternoon, fellow members of the international mining community. I appreciate the opportunity to participate in this special three-day, international gathering, and to join with you in honoring one of my very good friends, Doug Fuerstenau. It couldn't be more fitting to have this kind of event to mark Doug's 60th birthday. You know, in addition to his faculty position at the University of California in Berkeley, Doug is a member of the Board of Directors of our Homestake Mining Company. So it is a double pleasure for me to help pay tribute to one of the outstanding academicians of the mining industry as well as a man with whom I work closely in running Homestake. I have been asked to talk about "The Future of Precious Metals," but I will concentrate my remarks on gold. Since the theme of this Symposium is "Challenges in Mineral Processing," what I'm going to talk about is a challenge that relates especially to a major problem faced by those of us who process ores to recover gold. I noted that in the Scope of this Symposium, it stated: "the mineral industry is currently facing many challenges to improve the economics, operating efficiencies and environmental concerns of the mineral processing system." I couldn't agree more with that statement. I think that a need exists for us to address this situation as it involves gold. And who better to consider this than the worldwide leaders of mineral processing research here assembled. I start with the premise that we need a new method for cyanide use or a chemical to replace sodium cyanide entirely. In the case of using cyanide differently, I see a continuing difficulty in getting general public acceptance regardless of how

Jan 1, 1989

By J. Stachulak

This paper deals with theoretical considerations and practical applications of ventilation network calculations, based on mass flow rates and performed by computer simulation in our deepest operating mine - Creighton. The paper also deals with natural ventilation. In the usually accepted air-flow theory, the air is assumed to behave like an incompresssible medium. This introduces considerable error where temperature and pressure changes are great. Therefore, any study of the air flow in deep mines, must take into account compressibility. Basing ventilation calculations on mass flow allows a distinction to be made between air leakage and such quantity changes which occur due to air density changes. The energy which is required to convey one pound of air through a mine can be obtained by adding all head losses hL (ft-lb) of the ventilation paths through which the air flows. However, this total energy will not be correctly expressed in a compressible fluid by summing all pressure losses PL = hL x d (ft-lb/ft3 = lb/ft2) d = density. There is a law of mass conservation, but no law of volume conservation. Natural ventilation is caused by the conversion of heat into mechanical energy and not by the difference in upcast and downcast densities, as often believed. In an existing mine natural ventilation can be determined correctly by plotting a pressure volume diagram and measuring the area ? [ ] vdP = hN, where v = specific volume, or by measuring the sum of all friction losses and work provided by a fan. These procedures are tedious. The natural ventilation head (hN) can be approximated by the equaticn hN =[ ] tdZ. Where T is the average absolute temperature, t air temperature and Z elevation. In Prof. R. Greuer's computer program this determination of hN is automatically done for every mesh of the network.

Jan 1, 1980

By C. M. Jones

Cyprus Sierrita Corp. has developed a training program that has led to several significant improvements in safety performance and productivity. Truck productivity has increased 6% as measured by truck cycle times. Increased skill levels and awareness on the part of the mine's operators are due to the new training effort. Costs associated with productivity training have been about $185,300. This includes program development and execution costs, as well as lost productivity during the training itself. These costs are offset by $1.9 million in savings attributable to the increased skill levels of technicians due to the training effort. Cyprus Sierrita is a subsidiary of Cyprus Amax of Englewood, CO. The company operates a copper and molybdenum mining and processing facility south of Tucson, AZ, near the town of Green Valley. The Cyprus Sierrita operation produces about 109 kt/a (240 million lbs/ year) of copper, 11.3 kt/a (25 million lbs/year) of molybdenum, 31.1 t/a (1 million oz/year) of silver and 1.8 t/a (4,000 lbs/year) of rhenium. The opera¬tion employs 770 people at the site. About 200 of these employees work in the mine operations. Mining at Sierrita uses standard open-pit techniques. Crews of 43 people rotate on 12-hour shifts. Hourly technicians are nonunion and do not use rigid job classifications to define pay. Rather, the system is designed to pay employees for what they are able to do. Administering this effort requires that training opportunities are provided to those people who desire them. Successful training opportunities al¬low people to gain skills. The more skills an employee can demonstrate, the higher his or her "tech level." A technician's pay is commensurate with his or her tech level. Much of Sierrita's training in past years concentrated on building basic

Jan 1, 1998

By L. G. Closs

Gold continued to be the primary focus of minerals exploration worldwide during 1995. Other targets, though, included primary diamonds and base metals, especially copper deposits amenable to solvent-extraction/electrowinning (SX/EW) processing. The discovery of nickel, copper and cobalt at Voisey Bay in Labrador, Canada was an unusual surprise. Meanwhile, exploration geochemistry continues to evolve to meet new challenges. The major event in this category during 1995 was the17th International Geochemical Exploration Symposium (IGES) held in Townsville, Queensland, Australia in May. The meeting was sponsored by the Association of Exploration Geochemists, which celebrated its 25thanniversary of service to the mineral industry, and the Economic Geology Research Unit of James Cook University, Townsville.

Jan 1, 1996

By Alan J. Reed

The Afton copper-gold mine is located in the southern interior of British Columbia, 16 km (10 miles) west of Kamloops and 257 km (160 miles) northeast of Vancouver. 'An aerial view of the property in 1976 is shown in Fig. 1. The Afton copper-gold ore body [27 Mt (30 million tons)] of open pit ore with a grade of 1.0% copper, 0.46 g/t (0.01 6 oz per ton) gold, and 4.1 g/t (0.12 oz per ton) silver, occurs within the Triassic Iron Mask pluton adjacent to its faulted contact with Tertiary rocks. The geological setting of the Afton ore body is described by Carr and Reed (1976). Rocks of the Paleozoic, Mesozoic, and Cenozoic eras outcrop in the vicinity of Kamloops, but the unit with the greatest economic significance is the Upper Triassic Nicola volcanic group and its subvolcanic dioritic intrusion, the Iron Mask pluton. The Afton ore body occurs at the northwesternextremity of the Iron Mask pluton immediately south of a deep graben structure that developed in post-Triassic time (Coast Mountains orogeny) and which was the focus of vigorous sedimentation and volcansim in Tertiary times. The Iron Mask pluton is a lenticular composite intrusion approximately 14.5 km (9 miles) in length in a northwesterly direction. The petrography of the Iron Mask pluton ranges from picrite and serpentinite to latite porphyry. Outcrops of individual petrographic units are generally elongate in a northwesterly direction parallel to the axis of the pluton. The Iron Mask pluton represents the moderately slowly cooled core of an oceanic fissure volcano which built up an island flanked by shallow-water sediments including reef knolls and which, during its later stages, intruded its own volcanic pile.

Jan 1, 1991

By H. Lyn Bourne

The is the 14th consecutive year for this column and the 13th in which the royalty data have been tabulated. Some holes still exist in the list of royalties that readers hopefully will fill. Construction aggregates - either sand and gravel or crushed stone - are the most common mineral commodity. In spite of their pervasive use nationwide, royalty information for these commodities has been difficult to acquire from some states. Readers can help. Share information about these missing states and next year there will be fewer states without information. Dennis Bryan sent a copy of a report, "Regional Appraisal of Mineral Materials: Carson City District, BLM." The report was authored by real-estate appraisers. It contains more than 50 references to leases of various construction materials in Nevada and nearby states. It gives a thumbnail sketch of each lease and is a good reference. However, the authors erroneously imply that the royalty rate and the in-place value are the same. Several of this year's new entries come from the report. However, the royalties for landscaping materials vary from state to state and by rock type. Some boulders used for landscaping in Nevada have a royalty reported at $1.10/t ($1/st). At the other extreme is lava from Idaho. Used for the same purpose, it has a royalty range of $11 to $18.70/t ($10 to $17/st). Chuanming Tian of Beijing, China has shared some information about the changing mineral royalty policies in China. China first implemented an oil and gas royalty in 1984. In 1992, the government expanded that to include iron ore. In 1994, the royalty policy was extended to all mineral commodities. At the same time, the royalty rate for iron ore increased tenfold.

Jan 1, 1995

By Bernhard C. Koch, Richard W. Hutchinson, Bernhard Free

The Tertiary Silverton caldera collapsed asymmetrically to the southwest 27.5 m.y. ago. Resurgent volcanic activity is expressed by a quartz-monzonite stock at the southern caldera margin and by the Red Mountain porphyry stock in the northwest of the caldera which were emplaced at 25 m.y. and 11 m.y. b.p., respectively. The apical Eureka graben formed between 27.5-22.5 m.y. ago and transects the Silverton caldera southwestward. In the northeast it terminates at the 22.5 m.y. Lake City caldera margin. This graben as well as caldera faults provide dominant structural control for base and precious metal deposits. The epithermal gold mineralization of the Gold King mine is proximal to the Red Mountain stock in the north central part of the caldera. Here, west-northwest striking faults related to the collapse of the caldera intersect northeast faults of the Eureka graben. Superimposed upon earlier base metal mineralization at 23 to 22.5 m.y. b.p., the 11 m.y. younger gold metallization was a distinct event at Gold King. Supergene enrichment of the hypogene precious metal assemblage resulted in a metal tenor of up to 3,016 g/t gold and 1,088 g/t silver. The deposit is hosted by quartz-latite tuffs, flows, and flow breccias of the Burns Formation. Veins, up to 5 m wide follow steeply southeast and northwest dipping structures of the Eureka graben. Subsidiary veins up to 2 m wide branch off the main lode and are termed "flat veins" because of their conformable strike but shallow dip of 45' to 50' toward the northwest. Meteoric water-dominated hydrothermal solutions generated by the Red Mountain stock ascended through intensely fractured, ferruginous

Jan 1, 1988

By Glenn E. Craig

The practical and effective pulp distributor here presented is believed to be of a completely new and innovative design. It was developed at the San Nicolas Plant of the Marcona Mining Company in Peru, where it has been thoroughly plant tested using iron ore slurries of a particularly abrasive nature. It has proven to be superior to the apparatus originally installed, or to any observed in operation elsewhere. In plant practice the capacity and efficiency of many process units such as screens, magnetic separators, and jigs are strongly affected by the loading pattern, and for better results the flow of pulp must be proportioned across the receiving lip in equal quantities per unit width. The distributors originally installed on the drum magnetic separators in San Nicolas proved to be unsatisfactory, and several trial modifications failed to show any improvement. As is usually the case, feed rates were being steadily increased, and appreciable losses to tailings resulted. A check of the distributors on the market discloses no reasonable substitute, so efforts were directed toward devising an entirely new type. Required was a positive type of action which would guarantee that the pulp flow be spread equally along the length of the drum. Discussion As indicated, the motivation for development was simple necessity. The plant in San Nicolas crushes, grinds, and concentrates magnetic iron ores of a particularly abrasive nature, and depends largely on magnetic separation to obtain a marketable product. Feed to the numerous drum magnetic cobbers and finishers varies from rod mill discharge at a nominal minus ten mesh to a ball mill fine grind of seventy percent minus three hundred and twenty-five mesh. Operational factors affecting the magnetic separators were well controlled,

Jan 1, 1971