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By Antonio Jorge de Sousa

In order to compare several mining variants, on the point of view of the variability of the ore quality parameters, a conditional simulation technique is applied to a complex pyrite deposit (FEITAIS orebody, Portugal). Exploitation methods such as cut and fill and sublevel stoping are studied by the a.m. methodology. For each mining variant, it is assessed the influence of several mining operators on the variability of grades.

Jan 1, 1982

By S. Gupta

Froth flotation is a process commonly employed for the selective separation of phosphate from unwanted mineral. Column flotation has become widely accepted in the mineral processing industry, including phosphate industries, due to its ability to improve selectivity, lower operating cost, lower capital cost, and superior control. In this work, a hybrid model is developed that combines a physicochemical model with artificial neural networks. The physicochemical model is based on axial dispersion with first order collection rates. A new approach, in which both frankolite (the desired mineral containing phosphate) and gangue (undesired product) are modeled, enables prediction of grade of the recovered product. Thus, two basic parameters are required in this model: flotation rate constants for frankolite and gangue. Artificial neural networks are used to predict flotation rate constants. The model also takes into account the particle size distribution and predicts grade and recovery for each particle size range. The model then combines grade and recovery for each particle size range to determine the overall grade and recovery of the column. The model is validated against laboratory column data.

Jan 1, 1998

By Robert T. Beckman

Education of inspection and operating personnel is essential to protection from radiation hazards in the mining industry. For over 10 years, MSHA has presented the only formal course on radiation measurements and control available to the mining community. Course objectives and content are described in this paper.

Jan 1, 1981

By Kenneth M. Reim

In 1971, United States Borax & Chemical Corporation (U.S.Borax) initiated a mineral exploration program on federal lands in Southeast Alaska, with the commitment that any possible development would be done with great care for the environment. This program resulted in the discovery of a molybdenum deposit and the location of mining claims in 1974, in an area 45 miles east of Ketchikan, now called the Quartz Hill Molybdenum Project (Figure 1). At the time of this mineral discovery, the area was part of the Tongass National Forest, managed by the Forest Service, United States Department of Agriculture, and open to mineral entry and multiple use. In late 1978, the area was designated Misty Fjords National Monument and closed to mineral entry, and in late 1980 the area surrounding Quartz Hill was classified as Wilderness. These new laws and regulations, as well as the special interest environmental groups which oppose resource development, have significantly delayed and increased the costs of developing Quartz Hill.

Jan 1, 1983

By Michael Drozd

The operation of an activated charcoal system has five separate unit operations. These unit operations have common points for CIP, CIL and CIS system, which vary widely in application. a. Absorption b. Desorption (Stripping) c. Acid Washing d. Reactivation e. Carbon Handling ( carbon transportation, sizing, de­watering, etc.) Cost optimization starts with the basic operating parameters (design philosophy) set down at the time of engineering design. This parameters undergo almost immediate change due to site specific ore requirements, throughput changes, operator requirements or reagent availability. Activated charcoal is sometimes viewed as simple, uncomplicated reagent that requires not optimization. To some extent, this statement is true, but under most circumstances, if the time necessary to optimize the use of activated charcoal is available, the effort is rewarded with significant savings. CPL-Carbon Link has embarked upon a program of supplying technical support with its activated charcoal. Several operation in the United States have under taken to have CPL-Carbon Link do an operational survey to determine if potential savings are possible. CPL-Carbon Link has offered to do these surveys for projects that are clients or simply would like to have CPL-Carbon Link review their operation. The information accumulated by CPL-Carbon Link is being used to attempt to fashion industry standards so that a common reference point came be establish for activated charcoal usage.

Jan 1, 2000

By Terry M. Hertel

The chemistry of waters processed by Acid Rock Drainage water treatment plants can affect the Total Suspended Solids quality of the plant effluents. The sulfate ions in the ARD water will combine with the calcium ions from the lime that is used to adjust pH to form calcium sulfate. When the sulfate content of the waters to be treated is greater than about 1400 parts per mil­lion, the resulting calcium sulfate concentration will be approx­imately 2100 parts per million. This concentration is above the saturation point for calcium sulfate, and the salt will drop out of solution until the concentration falls below the saturation point. This "salting" phenomenon affects the total suspended solids of the treatment plant effluents by virtue of the fact that the salts will report to the filtration apparatus used for the analy­sis. This scenario is exacerbated as an effluent sample ages. Zortman Mining's water treatment plant effluent was being affected by "salting" during the spring and summer of 1995, and it seemed as though the effluents were exceeding the TSS lim­its; for no obvious reason. A testing program was initiated to verify an observation that "salting' was taking place. Treatment plant samples were collected and allowed to age, with TSS analyses being performed every day that the samples aged. Synthetic solutions were also prepared to study the "salting" phenomenon.

Jan 1, 1996

By Vinton A. Garbesi

The construction involved in the Washington Metropolitan Area Transit Authority (WMATA), Contract No. lK0011 (K-1), encompassed some 2,621 meters of single track parallel tube rapid transit tunnels, 335 meters of cut-cover subway station and appurtenant ventilation structures at each end, and a fan shaft at approximately the mid point of the tunnels. The construction contract was awarded June 7, 1974 to a Joint Venture consisting of Intercounty Construction Corporation, Hyattsville, Maryland, and S $ M Constructors, Inc., Solon, Ohio. The former being responsible for performing the cut and cover construction, and the latter being charged with constructing the running tunnels and fan shaft at their mid point. (See Fig. 1) The problems of mining and supporting, the 183 meters of twin tunnels just east of Court House Square Station, by unique mixed face and soft ground mining methods is the main subject of this report, although a general review of the tunnels in their entirety, as well as the geology encountered in the excavations, is presented to give a better overall setting for the problems encountered. GEOLOGIC SETTING The tunnels for the K-1 contract are located in three general types of material; the first being fractured and metamorphosed ignious rock (quartz-hornblende-biotite gneiss), the transition zone between weathered and competent rock, and in ground consisting of the weathered

Jan 1, 1979

By Russell W. Hunt

The cave man of ages past took his wife-and family from the cave pointing to a fire he had built and beating on his breast said, "Look what I have done". Today man is taking his family back to a cave saying, "Come enter in because of what I have done". At the close of World War II Germany said if they had gone underground one year earlier with more of their operations, the war could have lasted four years longer with perhaps much of Britain devastated. The protection of the home front no longer rests with the soldier in actual combat. The battle will be won at home with the most careful kind of protection against missiles. After Nagasaki-Hiroshima Sir Winston Churchill said in substance "Up to now the Almighty has mercifully withheld from man the knowledge of these terrible weapons of destruction."

Jan 1, 1959

By William J. Bronkala

One of the oldest tools used in mineral concentrating is the magnetic separator. Virtually every mineral handling system has need for some type of magnetic equipment in two types of basic usage. 1. Equipment protection through tramp iron removal. 2. Mineral concentration based on magnetic properties of the minerals contained in the ore.

Jan 1, 1969

By C. E. Stack

For the purposes of this presentation, "refractory clay" is intended to include any clay suitable for refractory products and thus represents a description based on industrial application. Other common examples based on use would be white-ware clay, bleaching clay, paper clay, or cement clay. Most users and producers of refractories have specific quality requirements which determine the quality or type of clay that can be utilized. Many clays can however be interchanged or substituted in use by changing manufacturing processes or upgrading less desirable clays. U.S. Bureau of Mines publications (Ampian, 1985) categorize days into six groups. These are kaolin, fire clay, ball clay, bentonite, fuller's earth, and common clay. These are practical groupings based on clay production and usage in the United States. Among these groups bentonite, fuller's earth, and common clay are primarily composed of the minerals, smectite, illite, or chlorite, and are non-refractory. Kaolin, ball clay, and fire clay are commonly used in refractories and thus qualify as refractory clays.

Jan 1, 1986

By A. E. Raddatz

The U.S. Department of the Interior, Bureau of Mines, is investigating methods for recovering tungsten from domestic resources. A calcine-quench-leach (CQL) technique was developed for the extraction of tungsten from the Golconda, Nevada, hot springs ores. The deposit contains disseminated tungsten, which cannot be beneficiated by conventional techniques and must be treated by hydrometallurgical methods. The CQL procedure consists of calcining the ore at 900° C for 3 hr, quenching in a solution containing 1.5 parts of NazCO3 and 1.5 parts of NaOH per part of WO3 in the ore and at a solution- to-ore ratio of 3 to 1, leaching at 200° C and at 250 psig for 3 hr, and filtering and washing the residue. A series of closed-circuit batch tests showed that 92 pct of the tungsten was extracted from a sample containing 2.32 pct WO3. The pregnant solution contained 11 q of W03/1.

Jan 1, 1982

By W. W. Bristol

The Jerritt Canyon Joint Venture project is located approximately 50 miles (80 km) north of Elko. Nevada, U.S.A. and produces between 250 and 300 thousand ounces of gold annually. The Joint Venture is 70% owned by Independence Mining Company and 30% owned by Meridian Gold Company. Independence Mining Company is the operator. The Jerrin Canyon Joint Venture started operations in 1980 mining a series of open pit mines. Since the early 1990's, the discovery of deeper ores has required the joint venture to develop and mine a significant portion of its annual production utilizing underground mining methods. Underground production started with the West Generator Mine in 1993 followed by the Murray Mine in late 1994. Presently, two additional underground projects are being developed. Underground mining at Jerritt Canyon is budgeted to produce 128 thousand ounces in 1997. This paper documents the major transition/redevelopment of the Jerritt Canyon mining methods.

Jan 1, 1997

By J. Manrique, B. Bustamante, P. Altamirano, J. Mendoza, J. Reyes

With no doubt, Peruvian mining potential is great as well as the energetic one. Unfortunately, this potential is threatened by social unrest. Several methods and strategies from different standpoints have been rehearsed with respect to unrest in Peru, however, the problem goes on without getting the right conflict interpretation and most of all, effective solutions are not achieved. The mining unrest dates from ancient times and has not always had the same stages nor the same demands. In the 20´s and 30´s, conflicts focused on workers’ rights and demands. In the 70´s, conflict focused on mines nationalization that were under foreign control. In the 80´s, conflicts took place because of requesting better wages, better working conditions, better mining profits distribution and more investment in communities that surround mining projects. It is very important to highlight those transversal demands such as land purchase, agricultural property, impacts and water reduction as well as pollution, impact on water systems and disappearance of springs have always been present over the historical period.

Mar 2, 2022

Many investigators believe that column flotation cells offer significant advantages over standard mechanical machines for the flotation of fine particles. However, because of their unique design and operation, conventional techniques for flotation cell scale-up and design cannot be applied to columns. In an attempt to help alleviate this problems a population balance model based on first principles has been developed for fine particle flotation in a column. Two different terms have been considered in the model, i.e., transport and rate. Transport terms, incorporating fluid flow and bouyancy, are used to describe the movement of air bubbles, unattached particles and bubble-particle aggregates along the length of the column. Rate terms, which describe the bubble-particle attachment process, have been derived from first principle considerations. Because the model is based on first principles, it can be useful for the design, control, optimization and scale-up of column flotation cells.

Jan 1, 1987

By Zachary D. Jones

"Construction projects involve a great many risks. The risk that material prices will increase during construction or that the work under construction will be destroyed by fire, storm or some other act of God are just a few examples. In tunneling or other underground projects, one of the most significant risks is that the subsurface conditions encountered during construction will differ from what is expected. Each of these risks must be accounted for, managed and, ultimately, the duty of one party or the other to bear. The primary tool used to allocate the risks among the parties is the construction contract.How construction contracts allocate the risk that subsurface conditions will differ have changed substantially over the past century. Today, construction contracts typically allocate the risk through a series of provisions. The first is the differing site condition or changed condition clause. That clause, when included, typically provides that the owner bears the risk that the subsurface conditions will differ from what is indicated in the contract documents or what is reasonably expected. The second clause is one that provides that the contractor must conduct a reasonable site investigation and bear the risk of any conditions that such an investigation would reveal. The third provision includes disclaimers that are often included in geotechnical data provided by the owner (or the owner’s engineer) to the contractor which attempts to limit the information on which the contractor can rely. Because these risk-allocating devices seem to be somewhat conflicting, a brief discussion of each provides critical insight in understanding how the modern construction contract allocates the risk of differing site conditions.At the start of the 20th century, construction contracts looked substantially different than they do today. For example, one contract for the construction of a public water tunnel in Chicago, IL, drafted around 1895 contained the following clause:The contractor must take the work entirely at his own risk. No extra allowance will be made for quicksand, hardpan or boulders."

Jan 1, 2014

By Noel C. Joughin, Orrie Fenn, Brian E. Protheroe

Work has shown that the use of high-pressure water jets enhances the performance of mechanical cutting in very hard rock. To assess the potential of this approach for use in conjunction with free rolling cutters, a series of tests has been conducted using both disc and button type cutters, to determine the relative effects, on cutter performance, of variations in relevant jet and cutting parameters. In these tests it was found that water jet assistance can result in reductions in the forces on a free rolling cutter typically of the order of 40%.

Jan 1, 1985

By William E. Spence

Gold was discovered at the Haile mine in Lancaster County, South Carolina in 1827 or 1828, and since that time the mine has been worked intermittently by both open pit and underground methods until its forced closure in 1942 by World War II. Production figures are incomplete, especially for the early years, but the total gold produced is estimated to have been greater than 200,000 ounces. Thus, the Haile mine has been the most productive gold mine in the eastern United States. The upper, residually enriched ores were relatively rich, but the bulk of the production has come from the mining of lower grade ores.

Jan 1, 1978

By G. E. Slagel

On August 3, 1987, a hearing was held by the House Subcommittee on Energy and the Environment to commemorate the tenth anniversary of the Surface Mining Control and Reclamation Act (SMCRA). Four panels of environmental/citizen group representatives went before the Subcommittee to report on the state of affairs (from their perspective) of the coal industry and the Office of Surface Mining, Reclamation and Enforcement (OSMRE) As expected, these groups had little positive news to report and continued to focus on glaring deficiencies within the surface mining program. They indicated that gross abuse of SMCRA has continued over the past ten years and the states have performed poorly. Congressman Udall's opening comments perhaps best characterized the mood of the group with his statement that "The Act has not accomplished what I or the people of the coalfields had hoped." and " ? a segment of the coal industry has continued in its bitter and implacable opposition to the most basic of environmental controls."

Jan 1, 1988

By Richard Louis Viner, William D. Leech, Walter A. Mergelsberg

With the construction management team established and a full funding agreement secured the Washington Metropolitan Area Transit Authority (WMATA) now has the manpower and the financial resources to continue Metrorail construction into the 1990's. This paper describes WMATA's new role as construction manager after the transition from Bechtel Associates and gaining the full funding agreement with the Urban Mass Transit Administration (UMTA) and regional governments to complete 84.7 Metrorail miles (136km). The authors review the most recent station and line tunneling projects. WMATA's contractors have employed the state of the art soft ground and hard rock tunneling equipment and methods - an earth pressure balance TBM, a closed face TBM, and the New Austrian Tunneling Method (NATM). In final, the paper previews future underground work to be let under the funding agreement.

Jan 1, 1987

By J. E. Murphy, L. A. Walters, F. H. Nehl, G. B. Atkinson

The US Bureau of Mines investigated the selective electrowinning of Ag and Au from cyanide solutions contaminated with Cu with the goal of decreasing the amount of Cu codeposited. Decreasing Cu codeposited will reduce refinery costs. Direct current was applied to the cell in pulsed and square wave voltages at 0.7 A h/150 mL of solution. Times tested for each cycle ranged from 1 to 10,000 msecs. Graphite, lead and stainless steel were evaluated as electrode materials. Square wave electrowinning at 70°C (158° F) gave the best separation of Ag and Au from Cu. Applying 2.5 V during the duty cycle, 0.0 V the rest of the period, a duty cycle of 10% to 30%, and a period of 100 msecs to 1000 msecs gave the following results: Ag concentrations decreased from 34 µg/mL to 0.1 µg/mL. Au concentrations decreased from 54 µg/mL to 0.2 µg/mL and Cu concentrations remained almost constant at 560 µg/mL.

Jan 1, 1995