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If the communication/tracking system of an underground mine is severely damaged in a large mine accident or explosion, a surface based seismic system could be the only available tool for locating any trapped miners. This paper documents a field test of a seismic system at a room-and-pillar coal mine in Eastern Kentucky. Testing was performed at 6 different depths (450, 575, 750, 1175, 1525 and 1700 ft) above the mine. For each location underground, the miners pounded a ?set? of 5 ?repetitions? on the roof with each repetition being about one second apart. Over the 3 day field test, 63 sets of underground miners? pounding were detected by the seismic system at depths up to 1175 ft and at horizontal offsets up to 890 ft. Also during the testing, the observed signal strength generated by pounding with a crib blocks was seen to average 180% stronger than the observed signal strength generated by pounding with a sledgehammer. Ultimately, this field test was very successful and definitively demonstrated the ability of the seismic system to detect potential trapped miners? pounding up to a depth of 1175 ft.

Feb 23, 2014

By Edita Vircíková, J. B. Hiskey, Ludovít Molnár, Peter Lech, B. J. Scheiner

This paper describes the results of a study of hydrometallurgical methods of producing sodium arsenate for the glass industry from arsenic oxide wastes occurring in carbon dioxide washing. This paper addresses the following aspects: theoretical assumptions for leaching arsenic and its oxides, experimental results of As(III) oxidation to As(V) in aqueous solutions, sodium arsenate crystallization (the system As2O5-Na2O-H2O), characteristics of the crystalline product, and pilot-plant tests using sodium arsenate in the glass industry.

Jan 1, 1993

By Madan M. Singh

Increasingly, geotechnical data are being collected for various types of coal development projects. In many cases, a specific design concern is addressed. However, many data collection programs are not intended to immediately support mine design activities or to resolve a specific concern. The following discussion describes some current geotechnical approaches in mine planning, development of reserves, and peripheral activities. Types of Data Collection Programs Geotechnical data collection is increasingly becoming a part of standard coal exploration programs, performed along with stratigraphic evaluations and coal quality tests. The aims of such programs vary. The purpose of the exploration may be to fill out the portfolio on a block of reserves that is to be sold, leased, or held for potential future development. In such a case, a generic suite of geotechnical data are collected. The resulting engineering reports may touch on the more well known mining problems of the area, but detail may be lacking. The geotechnical data are mostly intended to enhance the saleability of the package. Mine design alternatives are generally not addressed.

Jan 1, 1985

By S. S. Klima, H. Jiang, T. W. Beck, Y. Zheng

Researchers at the National Institute for Occupational Safety and Health (NIOSH) performed a series of lab tests to evaluate the respirable dust removal capacity of an industrial air-cleaning fan. Limestone and coal dust were tested separately in NIOSH’s full-scale drill table simulator at the Pittsburgh Mining Research Division (PMRD). Gravimetric samplers with Dorr-Oliver Cyclones and 37-mm filters were used at two upstream and four downstream locations inside and outside of the drill shroud chamber. There were six tests performed for both the limestone and coal dust experiments. In the limestone tests, an average respirable dust concentration of 98.86 mg/m3 was achieved upstream of the air-cleaning fan. The filter results show that the averaged respirable limestone dust reductions were 7.84%, 8.81%, 10.94%, and 18.02% at the four sampling locations downstream of the fan. In the coal tests, upstream samplers achieved an average of 129.03 mg/m3 of respirable coal dust. The averaged dust reductions were 9.54%, 9.83%, 18.54%, and 19.21% at the four downstream sampling points. The results indicate limited cost benefits of using this technology because of the relatively low dust reductions determined from this laboratory study.

Feb 1, 2023

By Keith Whitworth

The USSR, over the last 20 years, has continued to increase its out-put year by year and it is now almost four times what it was at the end of the Second World War. In 1975, it exceeded 700 million tons of run-oi-mine coal (all ranks) which amounts to over 20 percent of world output. This rapid progress has been due to modernization of the industry, by means of increased mechanization and automation and the development of new machines and systems for underground workings and by the expansion of open-pit workings and the development and implementation of larger earthmoving machines.

Jan 1, 1977

By A. H. Srnallbone

Over the past few years the rising production costs, shortage of skilled labor, and increased use of lower grade ore bodies have all added justification for the use of on-stream analysis. A rise in the number of on-stream units indicates that this type of assay is now being accepted as a necessity. On-stream analysis is a much more rapid means of obtaining true assays of a flowing product when compared to wet chemistry or "grab" samples dried, briquetted and assayed by x-ray. In contrast, on-stream analysis uses real time samples assayed every 30 seconds while each stream is assayed every 5 to 15 minutes. It is very important not only to know that a change has occurred in the process, but to know what caused the change and how to correct for the change. For example, in a tailing sample the elements of interest comprise between 1% and 10% of the sample. The remainder is water and gangue. Previously the gangue was not assayed nor were the low atomic number elements used for corrections. In addition to the demand for higher accuracies some concentrators were being penalized for excessive Ca or in some cases 5i in their concentrates. This penalty was being imposed by the smelter in order that they could better cope with pollution problems and prolong the life of their furnaces. But until Ca, 5i, and S are measured on-line, nothing can be done about their control. By accurately measuring these light elements on-line, a complete assay is obtained of the total sample providing improved accuracy for the important products. The justification for complete accuracy assays is now even more obvious because they are possible at very 1ittle increased cost and at no increase in analytical time.

Jan 1, 1977

By E. Farrokh

CSM and NTNU models are among the most commonly used models in TBM performance evaluation. Due to increasing application of TBM in different tunneling conditions, modification became necessary for these models. Sensitivity analyses on these two models indicate that both models are very sensitive to machine characteristics. Analyses performed on CSM database for cutter load and penetration rate prediction indicate while the r-square of the CSM model is reasonably high for the predicted cutterload, the r-square value for the penetration is low. In order to increase prediction capability of CSM model for penetration rate the model was reevaluated using non-dimensional analysis and the original database of Colorado school of mines. NTNU model is evaluated using Monte Carlo simulation and regression analysis. The results of analyses indicate that the majority of the variation of the penetration in NTNU model can be explained by only three parameters. This might indicate that the effects of other factors are overshadowed and it is worthy to reevaluate NTNU model using original database and more updated statistical methods to avoid overlapping of different parameters correlations.

Feb 23, 2014

By D. D. Harbuck

The U.S. Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent such as 502 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage counter-current leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with 502 or sulfuric acid.

Jan 1, 1991

By W. A. Crosby

All mine operators using explosives want to maximize explosive performance while minimizing blasting costs. Use of bulk explosive products such as AN/FO, heavy AN/FO, slurries and emulsions has greatly improved blasting efficiency over the years. Many operators have improved energy output from these products by adding aluminum. A major problem facing them is the fluctuation in aluminum price. The question therefore becomes, when is it economically advantageous to use aluminum in bulk products? This paper answers this question by first reviewing the energy output from the main types of aluminized and non aluminized bulk mixed explosives and then by showing the relationship between the different products on a cost and energy basis. The paper finally presents examples of charts and tables which will aid mine operators to conveniently select the most economically correct bulk explosive, including the level of aluminum addition.

Jan 1, 1991

By R. Patterson

Tracer gas sampling methods are useful for monitoring ventilation systems, especially in remote or inaccessible areas, and can be utilized for analysis of the ventilation system immediately following a mine emergency. However, the success of this technique is largely dependent on the accuracy of release and sampling methods. Analysis of sampling methods is crucial for rapid response and dependable results during emergencies. For the purpose of this study, four well-accepted sampling techniques currently used in the mining industry were compared using solid-phase microextraction (SPMe) fibers with sulfur hexafluoride (SF6), an industry standard, as the tracer gas. Current sample collection techniques include plastic syringes, glass syringes, Tedlar bags and vacutainers. SPMe fibers are used in a variety of industries, from forensics to environmental sampling, and are a solventless method of sampling analytes. To analyze these sampling methods, samples were taken from a 0.01 % standard mixture of SF6 and nitrogen and analyzed using electron capture gas chromatography. A relative standard error of less than 10% validated results to compare the accuracy of various methods. The technical and practical issues surrounding each sampling method were also observed and discussed.

Jan 1, 2011

By R. H. Parker, B. A. Wills, D. G. Binns

Introduction With the increasing need to mine lower grade ores, high energy-related costs in comminution are of major concern. Very fine grinding is needed to liberate the fine mineral particles in these ores. Not only is this expensive, but it leads to greater losses in slimes. Gravity concentration techniques become unacceptably inefficient for particle treatment below 25 to 50 µm, and even flotation fails in the ultra-fine range. Ore from the South Crofty mine near Redruth, Cornwall, was subjected to thermal pretreatment in the hope that differential thermal expansion of the minerals would lead to intergranular cracking, and thus enhanced liberation. South Crofty ore contains about 1% tin as cassiterite associated with a complex assemblage of quartz, chlorite, tourmaline, and hema¬tite in granite and slate. Recovery of cassiterite can be as low as 70%, as overgrinding occurs during stage reduction of the material to 1 mm (primary grinding) and 180 µm (regrinding). Cassiterite is present in grain sizes ranging from submicroscopic to + 10 mm, the bulk being predominantly in the range of 50 µm to 3 mm. Experimental Flat polished sections of the ore were photographed in reflected light using a Vickers M17 microscope. The sections were then heated in a Carbolite LMF4 muffle furnace. The heating rate and temperature were monitored by a thermocouple immersed in the bed of particles. Previous work by Sherring (1981) on the same material showed that a 55% reduction in grinding resistance occurred when the material was rapidly heated and cooled through the quartz inversion tem¬perature (573°C), where a volumetric expansion of 0.86% occurs. The samples were therefore heated to 650°C at 26°/min, and were then water-quenched to room temperature. The effect of heat treatment on the mineralogy and fracture network was assessed by examining the same area after treatment. Results Most of the sections examined showed that extensive transgranular cracking occurred as a result of heat treatment. Such cracking, although weakening the rock and hence reducing the work index, would in no way enhance the liberation of the cassiterite from the host minerals. Intergranular cracking, which would lead to enhanced liberation, was difficult to discern under reflected light, but there was evidence of such cracking in some of the sections examined. Figures 1 and 2 are examples of typical sections before and after heat treatment. Figures la and lb - show cassiterite in hematite, Fig. lb, in normal incident illumination, illustrating clearly that after heat treatment, transgranular fracture is evident in the cassiterite. If any intergranular cracking has occurred, it is not evident in this photograph. Figures 2a and 2b show cassiterite in quartz before and after treatment. Fracturing in both minerals after treatment can clearly be seen, and there is evidence of intergranular fracturing. However, protruding "arms" of cassiterite are severed by transgranular fracture. Subgrains of quartz have also been isolated by trans¬granular fracture. There is major transgranular cracking across the wider sections of cassiterite. Discussion The effect of rapidly heating South Crofty tin ore to 650°C, followed by water-quenching to room temperature, has been studied by observing the fracture networks in mineral grains. The choice of 650°C as the heating temperature was influenced by the work of Sherring (1981), who found considerable reduction in grinding resistance after thermal pretreatment of the same ore. Scheding et al. (1981), however, have shown, by means of a crude calculation, that heat treatment cannot be justified solely on the basis of reduced grinding costs. The cost of heat treatment far out-weighs that of grinding, resulting in the combined costs for heat treatment being over six times that for grinding unheated material. The most economically attractive aspect of heat treatment is the possibility of enhanced liberation of the valuable mineral due to increased intergranular rather than transgranular fracture. Grinding costs would be greatly reduced by improved liberation at coarser sizes, and the costs of ancillary processes, such as dewatering and tailings disposal, would be reduced. The most significant economic effect, however, would be in improved metallurgical efficiency. Improved liberation would increase concentrate grades, and recoveries would be higher, particularly in the case of ores where high slime losses are produced due to the excessively fine grinding required to produce adequate liberation. Manser (1983) has shown that only a 1% increase in tin recovery, at the same concentrate grade, would be sufficient to offset heat treatment costs on South Crofty ore. Heavy liquid analysis and shaking table separation have been used to evaluate the effect of thermal treatment on processing (Binns, 1984; Scheding, 1981; Sherring, 1981). However, treatment of unheated and heated samples of South Crofty ore, ground to the same product size, by such methods have shown little evidence of improved metallurgical efficiency after thermal pretreatment. The large amount of transgranular fracturing revealed by reflected light studies helps to explain this lack of improvement. Nevertheless, from the evidence of some of the fracture work, it is surprising that no improvements in metallurgical

Jan 1, 1988

By W. Petruk

Mineral liberations that would be obtained by grinding an ore to a specific size can be predicted by analyzing unbroken ore pieces, and mineral liberations in ground ores and mill products can be determined directly by image analysis. Predictions of mineral liberations are made by measuring size distributions and textures of mineral grains by image analysis, and using liberation models. Ground ores and mill products are analyzed to determine the proportion of mineral that is liberated, and the data are used to evaluate mineral behaviour during mineral beneficiation. The liberation data for minerals in a suite of mill products from a circuit are processed by a materials balancing technique to calculate recoveries of minerals in different types of particles throughout the circuit. The liberation-materials balance data define mineral recoveries; define the behaviour of an ore in a concentrator, pilot plant or bench test; and indicate whether recovery improvements are possible and/or feasible.

Jan 1, 1991

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Mar 12, 2021

By G. Kemp Williams, Peter H. Dohms, Barry A. Hillman, Laurie A. Williams

Introduction In 1969, the US devalued the dollar. This action, over the ensuing four years, resulted in the deregulation of the price of gold. It also resulted in the rebirth of the US gold mining industry. The extreme inflation of the 1970s led to a dramatic increase in the price of precious metals. Consequently an increased interest in the exploration for and mining of gold has occurred. The enthusiasm began among the few existing producers who had survived on marginal profits during a prolonged period of fixed prices and constantly rising costs. Then came the newcomers. They saw the opportunity to enter an industry that historically had been characterized by small operations with low capital costs. It was not until the late 1970s that large mining companies recognized that investment in gold projects could generate cash flows that previously were associated only with world class deposits. Today, gold mining has tremendous appeal for the entire mining community, despite the dramatic price drop from 1980-81 levels. There are even major firms with no mining experience attempting to gain a foothold. But how easy is it to enter the US gold mining industry? What are the basic factors that influence the economics, and what are they likely to be for the remainder of the decade? How has the industry changed, and what is the composition of the active companies? An examination of the industry will help to answer these questions. US Gold Mining History The current gold rush is actually the fifth in the 208-year history of the US. The first recorded commercial mining of gold occurred in the Southeast in 1799. It produced from small, yet relatively rich placer deposits. The famous California gold rush of 1848 placed the US as a major producer with 62.2 t (2 million oz) of output by 1850. More than 93.3 t (3 million oz) was mined by 1853, equivalent to 63% of world production. But the richest placers were soon depleted. By the end of the Civil War, annual production had declined to well below 62.2 t (2 million oz). The government then relaxed prices and the industry again began to recover. The 1870-80s saw the great mines of the California Mother Lode and Grass Valley brought into production. This was followed by development of Nevada's Comstock, which later became one of the world's largest producers. Discovery of gold at Cripple Creek in 1892, coupled with technological advances in the use of large dredges in the California placers, resulted in significant production increases. And, with the expansion of the Homestake mine at Lead, SD, in 1898, US output again surpassed the 93.3-t (3 million-oz) level. By 1905, produc¬tion climbed to 124.4 t (4 million oz) with the addition of the Alaskan deposits, new output at Goldfields, NV, and the introduction of the cyanidation process. During World War I, the government forced the shutdown of gold mines. By 1920, total production had dropped to little more than 62.2 t (2 million oz). Many mines remained closed until the Great Depression. This, combined with the devaluation of the US dollar in 1934, resulted in a gold price increase to about $1.13/g ($35 per oz). Then began the fourth gold rush. By 1937, output had again surpassed 124.4 t (4 million oz). This was due to an increase in primary production and new byproduct production from base metal operations. Unlike the previous period of growth, however, this period was short-lived. The imposition of Executive Order L-208 in 1942 once again forced the shutdown of most mines. At the end of World War II, cumulative US gold production had

Jan 12, 1984

By G. B. Amicucci

A Denver Autometrics Particle Size Monitor, PSM-400, was installed at Golden Sunlight Mines, Inc. in October 1988. The PSM-400 measures the grind product's particle size and percent solids. The particle size is used to control grind size by automatically adjusting mill feed rate. The PSM's continuous response to ore changes has improved grind product uniformity and mill throughput. Metallurgical testing has shown the PSM's accuracy to be +/-1 % + 150 µm (100 mesh).

Jan 1, 1991

By S. E. Valji

Clay slurries are normally dewatered using flocculents like sulfuric acid or aluminum sulfate. This type of flocculation is based on the electrolytic mechanism. For certain clay dewatering applications, this method of flocculation is unsatisfactory. Flocculation, based on the bridging mechanism, using organic polymers has been utilized to overcome such problem situations. This method of flocculation offers solutions not possible by previous methods. Normally these flocculents are used to assist dewatering. In this case, not only is dewatering promoted, but also further processing is assisted by a change in the dilatant character of the filter cake that is formed. Discharge of filter cake is easier, extrusion of filter cake on to conveyor dryer is possible or improved, and heat transfer and drying rates of the extruded filter cake are substantially higher. Both natural and synthetic organic polymers have been utilized for this purpose. Selection, application techniques, and economics are described.

Jan 1, 1965

By K. N. Santini

Natural zeolites are gaining recognition as an important commodity with an increasing number of industrial and consumer applications. This potential has prompted the Anaconda Minerals Company and other firms to investigate occurrences and markets for zeolites. The deposits of mordenite-rich tuff at Rome are of interest for their economic potential and for the excellent opportunity they provide to study a zeolite deposit formed in a hydrologically closed basin. Location The Rome property is located approximately 9 km west of Rome, Oregon, in Townships 31S. and 32S., Range 41E., Malheur County. It lies within the Owyhee Uplands of the northern Basin and Range physiographic province (Figure 1). The area discussed here includes a major portion of the depositional basin in which the zeolitic tuffs occur.

Jan 1, 1982

"Mine ventilation is in every underground mine a crucial process to ensure mine safety as well as acceptable working conditions. On the other hand is also a major cost factor depending on air requirement and air resistance. Due to the fact that the special layout of mines develop over time, ventilation systems change as well. This may result in complex systems which are suffering severe problems and low efficiency. With attention to the mine safety and costs, ventilation systems have to be controlled repeatedly and optimized continuously to fit changing conditions. The project “Improvement of ventilation systems in narrow vein mines” has been commenced with measuring and data collection in the Bogala Mine, Sri Lanka. This over 150 year’s old graphite mine consists of about 20 levels. The resulting ventilation system is highly complex and suffers problems like high temperatures and humidity as well as a mixing of fresh and used air on lower levels. To solve these problems and to optimize the system the complete ventilation system had been measured on-site first. The gained data have been used for simulations to develop and select an optimal and cost efficient solution. OBJECTIVE As an important process in mining ventilation is a major cost factor and can determine the economic feasibility of a mine. Due to the production mine layouts develop over time and mines increase in size and depth while the ventilation system becomes more complex and may suffer severe problems and inefficiency. Therefore mine ventilation systems have to be controlled and optimized regarding the general requirement of mine safety and health of the miners as well as the costs. Depending on the deposit type, depth, mining method, climate and as well corresponding laws and regulations the possible solutions are varying strongly. The work carried out paid special attention to the improvement of ventilation in narrow vein mines in tropical climate, in this case the graphite mine “Bogala” in Sri Lanka, South Asia."

Jan 1, 2015

By S. Makni, R. E. McIvor

Grate discharges historically outnumbered the overflow type of industrial wet ball mills. However, overflow discharge mills now strongly dominate. In order to understand their comparative advantages and disadvantages, Corem carried out a broad review of this topic. Where the data made it possible, the Functional Performance Equation was used to separate circuit classification from mill grinding effects. Batch tests were conducted in a torque-metered mill at different slurry levels. This paper presents the outcome of these investigations, which is a very strong case for the industry to once again consider grate discharges.

Feb 1, 2023

By T. Emery, D. Sweet, J. Bourgeois, B. Seymour, D. Porter

Cemented rockfill (CRF) is being used to backfill primary and secondary stopes at the Eagle Mine, an underground nickel and copper mine operated by Lundin Mining. National Institute for Occupational Safety and Health (NIOSH) researchers from the Spokane Mining Research Division (SMRD) are conducting cooperative research with the mine staff to determine if the size of a CRF sample affects its measured strength properties. Based on previous research by NIOSH, cylindrical samples of CRF ranging in size from six to eighteen inches in diameter were cast at the mine and cured underground. The samples were later transported to the SMRD laboratory and the Michigan Technological University where tests were conducted to determine the strength and elastic properties of the CRF. To further analyze the relationship between backfill density and compressive strength, different ASTM International compaction techniques were used to cast the samples. For comparison, tests were also conducted on in-situ core samples that were drilled from a stope which had been backfilled with the same CRF mix. The data collected from this study not only improves our understanding of CRF in-situ properties but also helps optimize Quality Assurance/Quality Control (QA/QC) methods for backfill preparation and testing.

Feb 1, 2023