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By F. M. Doyle, Jun Li, Milton E. Wadsworth, E. Peters

The Raman spectroscopic technique was used to study electrochernically oxidized pyrite in-situ. It was found that Raman-active sulfur oxidation products could be detected after a proper potential was applied to the pyrite electrode for a threshold period of time. There existed a minimum potential below which sulfur could not be observed. However, when the applied potential exceeded a certain limit, the intensity of the sulfur spectra decreased. The minimum potential at which sulfur could be observed changed with solution pH. For both acid (pH 2.7) and weak alkaline (pH 9.2) solutions, the minimum potential was 0.8 V/SCE, whereas for neutral (pH 6.5) solutions the value was 0.4 V/SCE. In strong alkaline solutions (pH 12.5) surface sulfur oxidation products could not be detected at any potential.

Jan 1, 1993

By B. J. Arnold, F. F. Aplan

A model incorporating rate and residence time to describe the froth flotation process was used to provide data for the evaluation of various kinetic flotation models and to provide scale-up information from laboratory to industrial scale coal froth flotation. Rate constants were determined in laboratory and plant froth flotation tests and the residence time distribution was measured for a bank of four 21 ft 3 (0.6 m3 ) WEMCO cells treating Upper Freeport seam coal and a bank of four 300 ft 3 (8.5 m3 ) cells treating Lower Kittanning seam coal. It was found that a lag time for continuous flotation should be incorporated into scale up models and that a kinetic froth factor ratio of between about 2.0 and 2.8 should also be used to scale up data from laboratory to plant scale.

Jan 1, 1989

By G. Myers, C. J. Wendt, W. H. Wilkinson, M. D. Dennis

Precious metal mineralization at Mt. Hamilton, NV is associated with a polymetallic, garnet-pyroxene skarn system developed in middle to upper Cambrian calcareous shale, limestone, and dolomite. The skarn is developed around the Cretaceous Seligman and Monte Cristo calc-alkaline stocks. Gold is associated with intense retrograde alteration. Later epithermal quartz veins contain gold, silver, base-metal sulfides, and sulfosalts cross-cut skarn alteration. Westmont Mining Inc. is currently developing two mineralized zones containing a geologic resource of about 7 Mt (7.7 million st) that averages 1.7 g/t (0.05 oz per st) gold and 17.2 g/t (0.5 oz per st) silver. The project will have an estimated mine life of seven years, with a planned annual production rate of I t (35,000 oz) of gold and 9.3 t (300,000 oz) of silver.

Jan 1, 1990

By G. R. Coonan

A number of famous studies have shown that house damage relates better to peak particle velocity than to acceleration or displacement. The relationship is true but doesn't go far enough. Why, for example, can construction shots go well above 1.0 or 2.0 inches per second without reportable damage? Recent studies have shown that vie must look at frequency and duration of an event in addition to amplitude. The complexity of measuring frequency, duration, and amplitude makes the average blaster in the field shudder. An even more excruciating problem is the need to obtain such data inside the building or residence in order to accurately predict the damage potential or human response to nearby blasting. The author reviews current research programs and suggests new areas of research necessary to help maintain a balance between complicated research requirements and simple field measurements.

Jan 1, 1980

By C. G. Tester

Automatic tripper control systems can be reliable and as such are suitable for use in the mining industry. Proper application of fundamental engineering principles provides the means for the reliability. Some of the principles are: (1) Be sure the system designer designs a system that does the job operations people want done; (2) Use sound logic design practices to avoid internal electrical problems; (3) The design must be maintenance oriented; and (4) Use good quality components. I would like to discuss a tripper control installation at Kennecott Copper Corporation, Chino Mines Division, in Hurley, New Mexico, and how these principles apply to this tripper control system. First, however, I will expand on the principles to clarify just what is meant. First, "Be sure the system designer designs a system that does the job operations people want done.? Operator acceptance is often the key to the success or failure of an automatic control system. One of the best ways I know of to get operator acceptance is to give him a system that he wants. I don't mean to imply that if bad practices or procedures exist that they should be incorporated in the control system. I do think that many designers feel they haven't done their job if the control system doesn't do things drastically different than the old manual method. Good engineering principles dictate that the job should be done right and if the manual method was right it can very likely be right for the automatic method.

Jan 1, 1973

By C. Patrick

Longwall face-to-face transfers can cost over $100 per minute in lost production potential and $100,000 for personnel and supplies. Such high cost makes extensive planning and control of the transfer process a critical necessity for the economic feasibility of longwall operations. This paper reports operations research techniques used for the analysis and modeling of longwall face-to-face transfers. Transfer data has been collected from companies who operate over 30% of the total U.S. longwall faces. Comprehensive sequence networks of existing longwall transfers were developed; simulation models of transfers under varying conditions were generated; and, the economics of general transfers and time-cost tradeoffs in the transfer procedure were investigated.

Jan 1, 1993

By Jon C. Volkwein

The U. S. Bureau of Mines investigated a method of using inert gas to prevent the formation of explosive gas mixtures in auger highwall mining of coal. A combination of gasoline and diesel engine exhaust gases was introduced into the auger drill hole using a short section of pipe located at the collar. Gas samples were taken and analyzed on site with infrared detectors for oxygen, carbon dioxide, methane, and carbon monoxide. Evacuated bottle samples were also taken and analyzed by gas chromatography at the Pittsburgh Research Center. These gas results were analyzed for explosibility. Personal exposure to carbon monoxide was also monitored. The highest methane level observed was 9.55 pct. The Inert gas levels, (carbon dioxide and nitrogen) were sufficiently high to prevent any ignition of the methane. Results showed that for all conditions during mining, gas concentrations were non-explosive. The maximum personal time weighted average sample for carbon monoxide was 20 ppm. This system provides a safe, inexpensive, simple method for preventing explosions during auger mining. INTRODUCTION The auger highwall mining method is an effective method to recover coal from a reserve when removal of the overburden by surface mining equipment becomes uneconomical. In this method of mining, a horizontal auger enters the coal seam from the surface mine bench under the highwall and the coal is drilled in a series of parallel holes. Historically, coal mined from the surface is relatively shallow, and over time, methane associated with the coal has dissipated through the surface. In most circumstances, little methane has been found associated with auger mining. However, mining technology has enabled surface mining of deeper reserves of coal. Furthermore, environmental constraints have forced the highwall extraction method to be used to remove coal under wetlands, further increasing the chances of encountering methane. Recently incidents of methane explosions at a few auger mining operations have resulted in injuries and increased testing for methane at the collars of auger holes. The fuel source of the reported explosions was not necessarily limited to methane, but may also have involved coal dust. The Mine Safety and Health Administration (MSHA) met with the Bureau to discuss what technology might be available to enable the safe resumption of mining. The discussion included the difficulty of ventilating through the solid shafts of the augers, that steel bits probably created the ignition source, and that perhaps inerting the holes with low oxygen and high carbon dioxide concentrations from the machine's diesel exhaust was a potential solution. Considering the ventilation aspects of the problem, it was not clear If ventilation could be reliably established. If some degree of ventilation to the front of the mining head is achieved, it may combine with methane to bring the hole atmosphere from a rich, nonexplosive mixture to an explosive mixture. Furthermore, it may not prevent a dust explosion in such a mining configuration. Lack of access through the shafts of auger type mining machines further limits the ability to add water or air to cool bits to prevent an ignition source from developing. Either of these approaches would also be expensive. The process of mining coal In an inert atmosphere has been considered in the past, but to our knowledge, never implemented (Department of Interior, 1970). Clearly, implementation in underground mining would be more complicated. On a mine bench open to the atmosphere, however, adding inert gas to the mining head could provide a quick, feasible method to prevent explosions at auger highwall mining operations. Also the problem of how to move the inert gas to the cutting head of the machine had to be considered. Preventing explosions on auger mining machines using inert gas requires three primary considerations: first is the source of inert gas; second, placing the inert gas at the cutter head; and third, monitoring the hole atmosphere. Any gas source having an effective inert gas concentration of 34 volume pct or greater will prevent methane from Igniting (Zabetakis, 1965). Sources of inert gas considered for this application included liquid nitrogen, modified shipboard inert gas generators (for hydrocarbon shipping and transfer), jet turbine engine (Paczkowski, et. al., 1982), the auger's diesel engine and a gasoline engine. Operation cost, purchase cost and availability limited our testing to the diesel and gasoline engines. This work tested each engine, separately and combined. To ensure effectiveness, both company and enforcement personnel need to know how to monitor the condition of the inerted hole. Measurements at depth inside the hole are possible by remote sampling through rigid tubing, but this method is Impractical for routine monitoring. Continuous monitoring of the exhaust gas stream is an alternative. The U. S. Bureau of Mines evaluated an inert gas system at an auger mining operation at a surface mine near Owensboro, KY. Coal was mined from the Number 9 Coalbed in Henderson Co. KY. Tests were conducted in January and March of 1992.

Jan 1, 1993

The only good news in the exploration sector in 1982-a year plagued by low metal prices and weak demand-was precious metals. Gold in particular remained in the forefront, as it has for at least the past three years. The reason for this is partially due to gold's seeming resilience to conventional supply side factors-such as new production-that normally influence many other metals. Also, with projected production costs of about $6.40-$9.65/g ($200¬$300/oz), modest deposits with average grades can offer an early return on capital investment and good profit potential. Keeping escalating capital costs for new mining ventures within reason has shifted gold exploration efforts in recent years. Many mining companies are seeking relatively low grade, modest tonnage, near-surface gold mineralization. This, of course, leads to lower development costs using open-pit mining methods. Recent refinements in the carbon-in-pulp recovery process also has enhanced the economics of such deposits. Slumping economic conditions certainly played a key role in shaping exploration activity last year. Nearly every major mineral-producing state recorded exploration slowdowns. In Alaska, for example, development expenditures approached the level of exploration spending for the first time in the state's history. This not only reflects major companies' decisions to move toward production but also the economic slowdown. The worldwide recession stopped Nevada's exploration and mining boom "dead in its tracks," said John Schilling, state geologist. The year was one of layoffs and closings for the state's mines and exploration offices, he reported. Similar trends were noted in most other states, especially in the West and Southwest. In the Pacific Northwest, however, exploration appeared to continue at a relatively good pace considering the metals market. In the mining geophysical community, recent advances in telecommunications and microprocessor technology are continuing to provide a positive impact. Many geophysicists have begun using satellite digital communication links to access computer systems from remote sites where using a microcomputer would be difficult. There were also major contributions made in exploration geochemistry last year. Highlights include progress in formulating mineral deposit models, geochemical exploration in glaciated and arid environments, and publication of many informative books. The following state-by-state summary and articles on geophysics and geochemistry provides a detailed view of exploration events throughout the US in 1982.

Jan 5, 1983

By D. Kwak, S. Han, J. Kim, Y. Lee

"INTRODUCTION In carbonate rocks, it is difficult to characterize due to the high degree of heterogeneity in pore geometry. Carbonate rocks have various types of pore systems such as fractures and vugs, and this heterogeneity should be considered for more realistic prediction of oil production in carbonate reservoirs. This study carried out water flooding experiments using five carbonate rock samples in order to observe the change of physical properties. Firstly, qualitative and quantitative analyses were conducted for each carbonate samples by use of XRD and XRF to evaluate the mineral content. All samples are mainly composed of CaCO3 and after that, the ICP experiments were carried out for the water passing through the carbonate. As a result, it was possible to measure the quantity of CaCO3, MgO, Fe2O3 component in water and due to this effect, the permeability of carbonate was altered especially in the front part of the core. Finally, after the carbonate was saturated by 30 API crude oil, water injection to enhance the oil recovery was repeated and it was confirmed that the oil-producing characteristics are different depending on the dissolution characteristics of carbonate rock samples. CORE SAMPLE ANALYSIS Porosity and Permeability Experiment Porosity and permeability were measured. The procedures are as follows (Figure 1). 1. Measure the diameter and length of the dry core using Vernier caliper. 2. Put the core in the core holder, run vacuum pump until the inlet and outlet pressure gauge equal. 3. Saturate the core using ISCO pump to inject water at 650 psi 4. Measure the amount of water and calculate the porosity 5. Set up the outlet pressure at 500 psi. 6. The flow rate measure when the equilibrium 7. Calculate the permeability through Darcy’s Law. 8. Cutting of core upstream and downstream about 13cm, and measure the each of permeability."

Jan 1, 2016

By Carol A. Hill

Native sulfur occurs with barite, celestite, and bioepigenetic calcite in the Culberson, Pokorny , and Leonard Minerals deposits, Delaware basin. The sulfur in these deposits, in "castile" masses, and in deposits of the Fort S tockton district have 6 34s values between +9 and -15. Native sulfur in the caves of the Guadalupe Mountains is somewhat lighter [(634s = -15 to -25)]. Barite in the Culberson, Leonard Minerals, and Comanche Creek sulfur deposits have 63% values of +35 to +73; celestite in the Culberson and Leonard Minerals occurrences have values of +38 and +36, respectively, and 87Sr/86Sr values of 0.707808 and 0.708138, respectively. Barite associated with sulfide, deposits, Guadalupe Mountains, have [634s] values of +41 to +62. Barite at Seven aeart Gap, Apache Mountains, is somewhat less enriched in heavy sulfur [(634s = +14 to +37)].

Jan 1, 1992

By E. J. Hammer

In the crushing and grinding of metallics for beneficiation, the sizing is normally done to liberate the metals or sulphides for further processing to improve recoveries of the basic metals or minerals. The objective is to reduce the ore in size through various closely controlled stages to that degree of fineness which gives an economic liberation of valuable mineral, but which avoids as much as possible the production of sliming fractions. A different philosophy applies to the crushing and grinding of Gypsum. Our requirements normally demand controlled grinding and/or crushing of the material not only to a fineness suitable for further processing of the mineral into end products, but to produce various sizes of material which are them- selves saleable products. The majority of our tonnage ultimately ends up in stucco for Wallboard. Therefore, our mineral reduction is normally designed toward this end, but it is done in a manner that permits drawing off inter- mediate products to meet various Customer requirements. This forces us into compromises at times in our equipment installations, and our equipment must sometimes be more versatile and complex than we would like it to be. We try to process our basic rock, Gypsum, for the most efficient size reduction. We market 5 to 6 different sizes intermediate to the end product, which generally is the fineness of material to be used for stucco for Wallboard, and we do this with controlled crushing, grinding and sizing cycles of the material. To summarize, we use a different philosophy of crushing and grinding than the metallic field which uses comminution or crushing and grinding to improve recovery, whereas we choose our equipment to crush and grind primarily for product performance.

Jan 1, 1969

By G. Orhan, C. Arslan

The possibility of producing metallic chromium from Cr2O3 via the aluminothermic route, with no external energy supply, was the subject of this laboratory-scale research. The experimental study focused on investigating the individual effects and quantitative optimization of the charge contents, i.e., the additions of CrO3, Al powder and CaO (or BaO). The highest chromium recovery of 98% was attained with the additions of 12% CrO3 and 1.2 times the stoichiometrically required amount of Al powder. The optimum CaO addition giving the highest chromium recovery was found when the CaO/Al weight ratio in the charge was equal to 0.3. When BaO was used, however, 95% Cr extraction efficiency was obtained at a BaO/Al weight ratio of 0.15.

Jan 1, 2000

By Martín A. Encinas-Romero, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, Patricia Guerrero-Germán, José R. Parga-Torres, Luis S. Quiróz-Castillo, JESÚS L. VALENZUELA-GARCÍA

Pressure oxidation is a hydrometallurgical oxidative pretreatment for refractory ores, such as sulfide ores. Here, simultaneous alkaline pressure oxidation and sodium cyanide leaching treatments were carried out on a pyritic ore from the Mulatos Mine located in Sahuaripa, Sonora, Mexico. Mineral characterization, agitation leaching, hot cyanidation under atmospheric pressure conditions, simultaneous moderated pressure oxidation and leaching, and kinetic testing results are shown. The modified variables were temperature, pressure, and cyanide concentration. Characterization indicated that pyrite was the main mineral. Simultaneous pressure oxidation and leaching experiments were conducted at a temperature range of 40–80 °C, oxygen pressure of 87.5–200 psi, and cyanide concentration of 0.8–1.2 wt% in a 2-L Parr pressure reactor. A dissolution rate of 81–86% was achieved under the following conditions: 87.5 psi, 80 °C, 0.8 wt% NaCN, for 1 h.

May 7, 2020

By M. N. Herrera

The bioleaching of mineral sulfide pulps in a bench-scale rotating drum reactor has been studied. The reactor includes horizontal paddles in the inner wall for lifting of the mineral pulp. The performance of the reactor was tested in the bioleaching of a refractory pyritic gold concentrate in the presence of pure Thiobacillus ferrooxidans strain (ATCC 19859). The concentrate was efficiently bioleached at 50% pulp density with the drum operating at 0.5 -1.0 rpm Attempts of bioleaching the concentrate at the same pulp density in conventional stirred reactor showed severe inhibition of bacterial activity. The results demonstrated that the drum reactor allows to operate at much higher pulp densities than the conventional stirred tank reactor. This behavior is explained in terms of an improvement of the bacterial activity due to a better control of the attrition of the mineral particles.

Jan 1, 1997

More than 100,000 people from 110 countries involved in the construction aggregates and ready mix concrete industries are expected to attend Conexpo-Conlagg '99 in Las Vegas, NV March 23-27. The exhibition, the largest of its kind in the Western Hemisphere, takes place every three years. It is held at the Las Vegas Convention Center, Las Vegas Hilton Center and Pavilion. The show serves as a venue for con- tractors and others involved in aggregates construction to view the latest in equipment, technology and services. More than 1,500 exhibitors will use more than 147,200 m2 (1.6 million sq ft) of indoor and outdoor exhibit space. Attendees include presidents and company owners, sales and marketing managers, general managers and project managers. An estimated 20% of the attendees will be from outside of the United States. New for the Conexpo-Conlagg '99 show is a 3,715- m2 (40,000-sq ft) Information Technology Pavilion. This event, organized by AIEIC Systems, will showcase computer technology for the architectural, engineering and construction industries. Shown in the pavilion will be the latest developments in cost management, estimating, bidding, project management and accounting. In addition, the Information Technology Pavilion will demonstrate the latest in computer-aided design software, systems and services. Conexpo-Codagg '99 will also emphasize live demonstrations of exhibitor's products. Individual exhibitors will demonstrate their machinery so attendees can see the latest technology in action. Because the Conexpo-Codagg exposition is so large, "shows within a show" have been created to help attendees locate the products and services best suited to their interests. Seven product concentration areas will be formed. Each area houses suppliers and manufacturers of similar products or services.

Jan 1, 1999

By Paul Soros

Lord Robens, Chairman of the National Coal Board of England announced recently to the world press plans for construction of the largest bulk terminal in Western Europe. This should result in annual freight savings of 22.4 million dollars and between 150 and 190 million dollars of new export business. These are rather substantial amounts for any mining enterprise. Or to put it another way, opportunities to make substantial savings in the delivered price of a highly competitive commodity such as coal are few and far between. One area where such opportunities still exist is in the economical; movement of bulk materials between producer and consumer.

Jan 1, 1966

By R. Henley, S. S. Webster, L. Harris

High resolution airborne magnetic and radiometric data have been shown to optimize exploration for epithermal gold deposits in the vicinity of Charters Towers, northeastern Queensland. The radiometric data allow extrapolation of poorly outcropping geology to provide a cost-effective mapping technique, even at exploration scales (eg. 1:25,000). At a regional scale (eg. 1 : 100,000) the magnetic data reflect the regional tectonics and divide the area into domains for the application of different genetic models. For example: 1. the Ravenswood Batholith is characterized by multiple intrusions dating from Ordovician to Permian age. The polarity of the magnetic anomalies implies an age for the intrusions and indicates a deposit style for exploration. 2. extensional and wrench tectonics along the northern margin of the Drummond Basin are interpreted from the magnetic data and indicate favourable blocks for detailed exploration. Genetic exploration models may be tested in favourable environments by the recognition of geophysical signatures. These signatures reflect structural, lithological and alteration patterns arising from controls on ore deposits and can be applied at regional or detailed scales.

Jan 1, 1989

By Martin H. Stanczyk

Under the Solid Waste Disposal Act, the Bureau of Mines initiated several accelerated in-house research programs to develop new and improved methods of proper and economic solid waste disposal. The program being conducted at the Bureau' College Park Metallurgy Research Center is concerned with eliminating the current waste of valuable materials in municipal refuse by developing low-cost methods for reclaiming and recycling the metal and mineral values contained in incinerator residues. Each year the United States must collect and dispose of in some manner or other, about 150 to 200 million tons of municipal solid wastes. The monetary output for this service ranks third among public services, exceeded only by the costs for schools and roads based on population growth projections and materials use patterns, the quantity of refuse generated by the early 1980's may approach 300 million tons annually. Currant estimates indicate that only 10 to 20 percent of the total municipal refuse generated is disposed of by incineration. If all refuse were properly incinerated the residues would contain more than 11 million tons of iron and nearly a million tons of mixed nonferrous metals including aluminum, copper, lend, zinc, and tin.

Jan 1, 1969

By R. Dorey

The Kennecott Ridgeway Mine in South Carolina is scheduled to complete mining and ore processing in the last quarter of 1999. Tailings are disposed in a 300 acre, lined tailings impoundment. To facilitate closure and reclamation, modification of the tailings impoundment operation has been adopted. Mining involved the sequenced development of two open pits. In 1996 mining of the South Pit was completed and backfilling of the pit with waste rock from the North Pit was initiated and will continue until mining ceases. Both pits will be reclaimed as fresh water lakes. This paper presents the physical, geochemical and hydrogeochemical evaluation of the operational and post operational management of the project. Comparison of the operational monitoring data against predicted performance is reviewed.

Jan 1, 1999

By A. F. Barsotti

Apart from jewelry, holistic apparel, and special collections of color and sometimes rare crystal specimens, the average layperson has little or no appreciation of the omnipresence of minerals or mineral derived products in the home. From concrete in the driveway to aspirins in the medicine cabinet, minerals, especially industrial minerals, play a major role in day to day living. For a better appreciation of this let's look into the a day of the life of a fellow named John, and see how much we depend on industrial minerals. The sounds of soft violins nudged John from his sleep. The melodic sounds of Beethoven's Pastoral coming from his radio alarm clock brought him out of his dreams. He reached for the reading light switch, then checked his watch--6:30 a.m., and another day of work. As he got up, the darkness outside reminding him of winter coincided with the soft voice of the all night disk jockey forecasting the fall of four inches of snow. Warm beads of water beating on his face removed all remnants of sleep and, like a stimulant, the morning shower brought thoughts of yesterday and plans for a new day. These carried over as he looked himself in the mirror while shaving and brushing his teeth.

Jan 1, 1993