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By T. Hackett

Western underground coal reserves are tremendous, but recovery in western seams can be poor because of mining problems caused by deep cover, geologic anomalies, and thick seams. For instance, many seams contain a rock parting too thick to be extracted economically with the coal. This forces the operator to mine the coal above or below the parting. Subsequently, the rock pressures induced by mining make the part left difficult or impossible to extract by standard mining methods. Because upper and lower parts of the seam are frequently of minable thickness, the presence of rock partings can result in a significant loss of coal. Given a longwall recovery of 60 pct and equal thickness for the two parts of the seam, overall recovery is reduced to less than 30 pct if one part only is mined. The coal left in place is unavailable to meet the nation's energy needs, or to produce revenues for coal companies or government. [ ] Multi-slice longwall mining has the potential to recover the portion of split seams that are now left in the mine. Using superimposed standard longwalls with chain pillars, overall recovery could be doubled, depending on panel and pillar widths. Using a combination of advancing and retreating longwalls in descending slices, overall recovery could be improved to more than 80 pct. Because of the potential for improved recovery, the Bureau of Mines is analyzing the ground control factors affecting multi-slice longwall under western mining conditions and is conducting field trials at a planned multi-slice operation.

Jan 1, 1987

By Carlos Viramontes Aldana

Mining in Mexico is one of its post traditional activities, whose influence in the development of important cities and communications has been decisive. Precious metals and, to some extent, copper and tin were known and used before the Colonial period, but from the sixteenth century to tie end of the nineteenth century, mining and metallurgical industries were concentrated in the precious metals, mainly silver. This silver was exported to Spain and other countries under the Spanish. Rule, Mexican peso was known world wide since the end of the sixteenth century and Mexico ranked as the first silver producer since the eighteenth century.

Jan 1, 1985

By Robert D. Deister

The Buick Concentrator represents state-of- the-art technology in automated digital process control operation utilizing a centralized computer. The process control strategies implemented at Buick are no longer new to the industry but the successful application of these developments is still rather unique in North America. Productivity improvements, determined to be a direct result of the process control developments, are the primary topics of this paper. Emphasis is placed on metallurgical benefits including both lead and zinc recoveries, lead concentrate grade and reductions realized in reagent consumptions, operating costs and personnel. The productivity improvement discussion is preceded by a concentrator description and a brief history of the process control development at Buick. Current control strategies and future applications are presented afterward.

Jan 1, 1985

By E. A. Noble

In the Western Coal Region, successful reclamation of surface-mined areas includes the protection of groundwater sources. To accomplish this, a complete understanding of the geohydrology of the affected area is imperative. Successful mine design also calls for careful attention to geohydrology. Because the Western Coal Region is semi-arid land used mainly for farming and grazing, groundwater is a particularly sensitive topic. It is especially sensitive where the lignite scheduled for mining is itself the aquifer supplying the farms and ranches. Such is the case throughout much of the Western Coal Region, particularly where there are no near-surface sand and gravel aquifers that are commonly found in the glaciated portions of the Region. Just as mining can adversely affect groundwater supply, so can groundwater adversely affect mining. Mine flooding and highwall instability are examples of this. But, mine operators must realize that procedures they use to remedy geohydrologically-related mining problems can have a dramatic effect upon ground- water conditions in areas adjacent to the mine. A logical precaution is to require the acquisition of complete baseline data prior to making the first cut. We recommend that the mining plan not only incorporate the reclamation plan, but that they be developed as one plan.

Jan 1, 1976

By Paul M. Bommer

Abstract. This cater presents the development of and results from a computer model of in-situ uranium leaching. This model uses a streamline-concentration balance approach and is useful with a vide range of reservoirs. It can be used with any type of veil system, in a reservoir with or without boundaries, and with any form of descriptive kinetics. The model also includes the effects of dispersion and consumption of oxidant by minerals other than uranium. The effects of areal sweep, variable uranium concentrations, variable permeability, and the presence of oxidant consumers on uranium production are shown and discussed.

Jan 1, 1979

By Takaji Kusakawa

In Japan, almost no natural gypsum is mined for industrial uses of gypsum, and almost all gypsum is synthetic gypsum, that is desulphogypsum, produced by waste sulphur dioxide gas from metal smelters and power plants, and other industrial waste sources. The amount of such sythetic gypsum production has reached more than six million metric tons per year (1979). Major uses are for cements and building materials. Other uses are soil conditioner, investment casting mold, organic composite materials, etc and sulphur recovery by gypsum decomposition is being examined. This paper summarizes present Japanese production and uses of sythetic gypsun produced from industrial waste.

Jan 1, 1982

By George A. Desborough

Marine black shales of Paleozoic age in the Western United States that exceed 10 weight percent organic carbon contain as much as 5,000 ppm vanadium, 1,000 ppm molybdenum, 1,300 ppm nickel, 600 ppm cobalt, 16 ppm silver, 7,000 ppm chromium, 18,000 ppm zinc, 280 ppm cadmium, and 350 ppm selenium. Depositional settings include: (1) continental-rise and marginal-ocean basins, (2) continental-shelf and foreland basins, and (3) cratonic-platform embayments. Most of these metalliferous organic-rich shales have not been examined for resources because of rapid weathering and poor exposures which preclude easy sampling of unoxidized rock necessary to determine actual concentration and residence of indigenous metals. Generally, the marine black shales of Paleozoic age in the Western United States are richer in metals than marine Paleozoic black shales in the Eastern United States.

Jan 1, 1982

By C. C. Hatch

As part of a general project to simulate a concentrator, the Brenda Mines Limited secondary crushing plant, located near Peachland, B. C., was sampled during the summer and winter of 1975 to develop a digital crushing plant simulator specific to the Brenda operation. The purpose of this simulator was to study the influence of manipulable process variables on important responses and to permit study of alternative circuit configurations if desired. This paper describes the simulation methodology employed and presents the results of a computer study of the secondary crushing plant (1).

Jan 1, 1979

By Bates H. Murphy

There is one quick way to substantially reduce the operating cost of a great many pining operations. It is to cut the demand charge on the use of electricity and gas. Demand charge is the utility company's charge for the maximum rate of energy usage which is in addition to the charge for the total amount of energy used. Energy demand is reduced by prohibiting simultaneous operation of devices, especially those that consume large amounts of energy, or by deferring the use of such equipment as air conditioners from one demand period to a subsequent period. To achieve that end, a control system can continuously measure the demand and turn off selected loads in accordance with established rules. Because of the complexity of most industrial plants, a computer is the best means of storing, measuring, calculating, and controlling the many variables associated with the many devices involved. A computer system for that use has been developed by the Westinghouse Computer and Instrumentation Division in Orlando, Florida. For most applications, this demand control system can be installed and operated by industrial plant engineering personnel with no special knowledge of computer technology. It can be used with both electrical and gas service. For clarity, let us examine electrical demand first.

Jan 1, 1974

By E. J. Freech

In this part of the two-part paper we discuss briefly the adaptation of the comminution model to describe the observed behavior of an industrial grinding circuit. Although reported verification of comminution models for continuous systems is limited, some interesting work has been reported 1,2 recently. The data acquisition and modeling efforts are described first, followed by discussion of some of the simulation results. Observations pertinent to steady-state operation are presented followed by a description of the application of a dynamic model of the grinding circuit for synthesis and evaluation of grinding-circuit control. The pilot-scale work indicated the comminution model should be capable of describing an industrial size-reduction process. Recognizing the broad utility of a process model based on first- principles, the Industrial Nucleonics Corporation of Columbus, Ohio, embarked on a joint program with the Duval Corporation of Tucson, Arizona, to evaluate the industrial applicability of the models described in Part I. This program was conducted in a grinding circuit, which included a rod mill 12.5 feet in diameter and 16 feet long and a ball mill 12.5 feet in diameter and 14 feet long, at Duval Corporation's Esperanza property3. The rod mill was operated in open circuit and the ball mill in closed circuit with cyclone classifiers.

Jan 1, 1970

By Alan S. Peck

Chemisorbed oleate films on the surfaces of fluorite, barite, and calcite were studied by means of infrared spectrophotometry. Evidence is presented which indicates the mineral anions, i.e., fluoride, sulfate, and carbonate, are displaced from the mineral surfaces as a result of the adsorption from aqueous solutions. Also, chemisorption reactions between oleic acid and fluorite or calcite occurred spontaneously in the absence of water. Carbon dioxide was identified as a reaction product when dry calcite was contacted with oleic acid. There was no evidence of reaction between oleic acid and barite in the absence of water.

Jan 1, 1964

By Ralph W. Barbaro

This paper presents a cyclic queueing model which evaluates the productivity of a shovel-truck materials haulage system. For a cyclic queueing problem with exponentially distributed service times, a cyclic queueing model provides exact solutions in a fraction of the time that simulation takes to produce an approximate solution. The model is applied to an example problem, and the results are validated with simulation. Simulation is used to show that the assumptions of exponentially distributed service times and steady-state are not serious problems. A cyclic queueing model can be used to quickly obtain an accurate assessment of the productivity of a shovel-truck system.

Jan 1, 1986

By Jim V. Rouse

The mining, beneficiation, and processing of phosphate rock in the Florida phosphate district constitutes a large portion of the southeastern mining industry. For example, 1973 production is reported to have been approximately 35 million tons of phosphate rock (Guimond and Windham, August 1975) and production has increased to over 45 million tons in recent years. The 1973 activity involved the movement of approximately 127 mil lion tons of material. From the hydrologic standpoint, this mining and beneficiation requires the dewatering of ore horizons, pumpage of large quanitites of water for mining and processing operations, and the entrainment of immense quantities of water in waste slurries. Also of significance is the fact that the cited 1973 production involved the disruption of approximately 3200 curies of radium and over 6000 curies of uranium. Much of this material reported with waste products, with the potential for contamination of area ground waters. However, natural removal mechanisms active within the area have generally been effective in preventing significant contamination of the ground-water resource.

Jan 1, 1983

By J. D. Kennedy

The alchemists of old are remembered well for their tireless efforts in attempting to convert various common metals, such as lead, into gold. Not so well known generally, but no less intense, have been the efforts of certain individuals who attempted to manufacture diamonds over the last 100 years. Diamond, the most glamorous and permanent of gems and the hardest industrial abrasive, is carbon in a high-density unique crystalline form with a cubic structure and a density of 3.5. This contrasts with graphite at a theoretical density of 2.2 and possessing a hexagonal structure. Diamond is the hardest natural, material known and until very recently had no close competitor, natural or otherwise, with respect to hardness. The hardness of diamond exceeds that of any other industrial abrasive by a factor of approximately five. The early theories of diamond synthesis were rather vague. Since diamonds occurred in nature, man then looked to nature for clues as to how this might be accomplished. The original known diamond deposits of India are alluvial in character and provided little insight as to how diamond had been formed by nature, for in, these locales the diamonds have been washed by streams or carried by the glaciers long distances from the areas in which they occurred originally in the earth's crust. As a matter of fact, we are told that even today the locations of the mother ground for the Indian alluvial deposits are not known.

Jan 1, 1959

By Salam Moubarak, Thomas Camus

"INTRODUCTION Since the introduction, several decades ago, of the first concepts of tunnel boring machines (TBMs), the unremitting increase of mechanized and automated tasks and the reduction of manual tasks carried out by human operators have gone hand in hand with the continuous improvement of these machines. In the present state of TBMs, the replacement of worn cutting tools is a critical, tedious, and dangerous manual operation especially for earth pressure balanced (EPB) and slurry TBMs. For such pressurized TBMs, hyperbaric interventions are used. They consist in replacing the pressurized soil/mud inside the chamber with compressed air that balances the face pressure. The operators can then ""dive"" into the chamber; however, because the human body cannot naturally undergo pressure changes, they have to follow strict procedures that have been developed for subsea divers, based on decompression stops. Indeed such interventions are actually quite often performed by professional deep-sea divers. The pressurized TBMS are consequently equipped with a manlock that allows for the required compression and decompression cycles. Hyperbaric interventions increase risk to the operators and require long decompression procedures that increase the TBM idle time and reduce its efficiency. At higher pressures, over 3.5 bar (ITA Report No 10, 2011), specific equipment and special gas mixes and/or saturation techniques are recommended (Lamont, 2012). Such procedures are even more expensive and time consuming although the duration of work in the pressurized area can be very limited for health and safety reasons. Contractors are therefore increasingly interested in automating these operations to reduce the risks to human workers and improve the TBMs performance. Moreover, the demand for new, ambitious and challenging tunneling projects (very deep, high pressure boring) is ever increasing, but the supply of suitable TBMs is limited and the risk from working in the hyperbaric environments becomes increasingly unacceptable. Impact of hyperbaric interventions The UK Health & Safety Executive has analyzed the consequences of working in intermediate pressure compressed air. The retrospective study of decompression illness (DCI) indicated that at certain pressures its incidence was around 2% of all exposures. More worryingly it showed that over 20% of the exposures commonly undertaken by shift workers in tunneling (those over 1 bar pressure for 4 hours or more) resulted in DCI. It was concluded that on some contracts up to 50% of shift production workers experienced DCI at some time during the contract, a situation which was considered to be wholly unacceptable (Lamont, 2006)."

Jan 1, 2016

By C. H. McGuirk

Computerized Preventive Maintenance is important in maintaining consistent and efficient operation in any industry utilizing sophisticated and expensive equipment on a continuous basis. At today's large bulk materials handling facilities, the problems of continuous operation of complex machines with their thousands of components exposed to abrasion, dirt, dust and the elements, are intensified and multiplied. Effective preventive maintenance can increase profits. Yet, the number of tasks to be performed is so staggering that it is beyond error-free human capacity. The computer must be an essential ele¬ment in any efficient and economical preventive maintenance system. Computerized preventive maintenance techniques have been successfully used in many fields, usually involving highly skilled and specialized personnel working under favorable and controlled conditions. Now, The Pittsburgh & Conneaut Dock Company has developed and is applying a computerized preventive maintenance system that is applicable to the bulk materials handling industry. The "system" has taken many years of intensive effort to develop and has been time-tested and proven during the past years on equipment handling materials with rugged physical characteristics and corrosive and abrasive qualities, under some of the most adverse weather conditions on the Great Lakes.

Jan 1, 1976

By S. L. Manske

The Mesquite gold deposit is a recent discovery of Gold Fields Mining Corporation lying 65 kilo- meters northeast of El Centro in Imperial County, California (Figure 1). The deposit is located on the southwestern flank of the Chocolate Mountains and is a bulk-minable, low grade "disseminated" orebody. Although the host rocks of the deposit are part of a regional high-grade metamorphic terrane, abundant brittle fractures, brecciation, and open-space vein fillings indicate that Mesquite mineralization is epithermal. Faulting which postdates the hydrothermal activity has complicated the original geometry of the orebody. Alluvium effectively hides most surface expression of the mineralization, but open-pit mining is now revealing the details of Mesquite geology.

Jan 1, 1987

By James F. Lemons

The potential production of cobalt from nickel sulfide deposits in Canada, from nickel laterite deposits in the Pacific Islands, and from the copper deposits of Zaire and Zambia will be a function of the cost of recovery of the primary nickel and copper products. This cost of production varies significantly for these deposits and is related to the differences in the cost of labor, energy, and supplies, to production technology, and to the grade and recovery of nickel, copper, and cobalt. This Bureau of Mines paper investigates these cost and technology differences as they relate to the cost competitiveness of the deposits in Canada, Zambia, Zaire, and the Pacific Islands.

Jan 1, 1984

By Robert W. Carn

This paper presents the concepts which are presently being utilized in the design of coal export terminals. Criteria for selecting a viable site and establishing the terminal plan are presented. Factors affecting the design of the terminal as well as the present techniques and procedures in use today to determine the optimum use of equipment will be discussed along with the current trends in export terminal control systems. Finally capital and operating costs for a typical export terminal are reviewed.

Jan 1, 1982

By Charles M. Brinckerhoff

Everyone -- especially the engineer -- is aware of the great technological and social changes taking place in our world today, We realize that changes have been taking place since man's beginnings on earth, but the element we now face is the speed of change, rather than change itself. Developments in medicine, in transportation, in space exploration, in global communications, and in many other fields, are constantly being made known. These developments are affecting the lives of each of us, although some may appear remote and unrelated to us as individuals. New developments, almost on a daily basis, affect our work as well as our social, religious and educational lives. The effects are immediate and permanent.

Jan 1, 1967