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By M. Springett

Organization of teams for rapid and effective evaluation of international mining properties requires special considerations beyond those needed for domestic activities. Experience, technical ability, a sense of perspective, humor and self-discipline are vital characteristics to look for in the selection of individuals for forming an efficient and productive team.

Jan 1, 1994

By Dermot M. Ross-Brown

The objectives of this generic study were to use numerical modeling techniques to determine under what conditions seismic waves generated by an earthquake might cause instability to an underground opening, or cause fracturing and joint movement that would lead to an increase in the permeability of the rock mass. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass. An artificial rock-burst tremor with high accelerations, however, was found to be amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In shale, even moderate seismic loading resulted in tunnel collapse.

Jan 1, 1981

By K. A. Foo

Minproc Resources Inc. is developing a tailings retreatment project in Bolivia at the Colquiri zinc-tin-silver mine, in the Bolivian Andes. Mining at Colquiri has been continuous since 1940 and COMIBOL, the Bolivian state mining company, has owned and operated the underground mine since 1964. There are 10 million tonnes of tailings at Colquiri containing 0.51% Sn, 4.21% Zn and 50 g/t Ag. Minproc plans to mine and concentrate the tailings at 1.15 million tonnes per year to produce feed for pyrometallurgical upgrading. The tailings are moderately complex, with cassiterite grain size ranging from 200 to 5 pm. The marmatite (ZnFeS) in the tailings is relatively easily recovered, with zinc recovery of 80% to a 40%-45% Zn concentrate. The major problem with the zinc metallurgy is that the marmatite is complexed with iron, which results in iron contents of 14%-17% Fe in concentrate. This makes the product very difficult to sell because of the low Zn:Fe ratio. Most zinc smelters require a Zn:Fe ratio of 6:1 or 7:1, whereas this concentrate has a 3:1 ratio. Concentrate sale terms are therefore unfavorable, and the high cost of transportation from Bolivia to the smelters is an additional burden.

Jan 1, 1992

By James W. Echerd

Anthracite preparation developments, particularly in the early days of the anthracite industry, formed the basis for the modern coal preparation plants that have become so essential to the coal industry today. The anthracite industry, from early in the 19th century until relatively recently, was a leader in mining, preparation and marketing of coal, and played a leading role in the development of the industrial America we know today. Anthracite was discovered in America in about 1760--the story of Necho Allen is well known--but the rediscoveries leading to mining operations took place about 50 years later. The Wurtz brothers in 1815 at Scranton, the Smith brothers at Wilkes-Barre in 1807, Beach in Hazleton in about 1814, and Boyd in 1816 at Shamokin were all instrumental in promoting early mining and marketing of anthracite (J3. The early canals and railroads were built for the specific purpose of moving anthracite to the market areas. Eventually, the industry grew until, in 1917, it reached a production zenith of a little over 100,000,000 tons, representing about 20 percent of the total coal output in the United States. Almost half of the anthracite produced that year was consumed for domestic heating, a utilization that had dominated the industry for almost 100 years. Initially, anthracite had to be used by gunsmiths and blacksmiths, after which had followed the consumption of extensive quantities for railroads, blast furnaces and foundries, and electric power generation. Most of the markets have been lost to coke, oil, and natural gas. Near the anthracite regions, however, significant quantities are still used for domestic heating, power generation, carbon black manufacture, blending with bituminous coal to make metallurgical coke and fuel, and for other industrial purposes. Thus, anthracite production has not been entirely committed to history, but remains an active industry that follows modern practices in the mining, preparation, shipping, and utilization of a fuel that is still a valuable adjunct to the national economy. In fact, its inherent low sulfur content may make it an important fuel of the future. Estimates indicate there are reserves of anthracite to last for 300 years at a consumption rate of 50,000,000 tons/year. Anthracite Preparation Yesterday A 170-year history of the anthracite industry obviously is not the purpose of this discussion. A complete history of anthracite preparation, the rather unglamorous step in the processing of "mine run" hard coal to make it suitable for the user, is also not practical. Hence, the purpose of this report is to trace the development of some of the most important processes used through the years to meet a part of the demand for energy developed by our modern society. Anthracite preparation in the early days of the industry consisted solely of separating slate from the coal, by hand, underground (Z). This method prevailed for almost 20 years until wrought iron hand rakes were introduced to separate the large and small sizes. Shortly thereafter, the first attempts were made to size and clean the coal aboveground. The coal was dumped on a perforated cast iron plate, and men used sledge hammers to break the larger pieces into smaller sizes suitable for the market. The smallest sizes--that is, the material that went through the plate--were thrown away because they had no value at that time--a concept that existed for many years and actually was the basis for the subsequent "river" coal production and the many silt banks which are landmarks in the anthracite region. The larger sizes, at that time, sold for 50 cents per ton. The Batten breaker, or roll crusher, was invented in 1844, followed soon thereafter by the Snell-Diehm breaker (A). The latter had disadvantages, including excessive waste and fixed product size, but it later was improved in these respects. A breaker was also developed at Minersville, Pa., at about the same time that processed 200 tons of coal per day, using roll crushers and circular screens (1). Handpicking, from the beginning of anthracite preparation, was an important part of the cleaning process and was still being practiced as late as 1950. It was this process that involved the "breaker" boys of coal region lore. How much good handpicking accomplished depended on how much impurity was present in the coal--the more the impurities, the greater the reduction in ash. Thus, high-impurity streams were significantly improved, whereas picking of relatively clean coal was mainly to show an effort to make a quality product. As indicated, picking is largely a visual operation. It was and is wasteful of coal in the larger sizes since some good coal is always associated with the bad. However, it was probably much more effective' in the larger than the smaller sizes.

Jan 1, 1971

By Ross Goodman, Jean-Luc des Rivières

The Ohio River Tunnel Project encountered multiple unexpected geotechnical challenges which, continuing to develop over time, hampered excavation completion and impacted the cast-in-place final lining technique and work execution sequence for the entire project. The continued degradation of the excavated hard rock tunnel conditions led to a unique, dynamic, geologic setting that forced the project to innovate new and adaptable measures allowing for a conventional cast-in-place liner to be completed in a safe and timely manner and minimize delay.

Jun 13, 2023

By PAITIP THIRAVETYAN, KANJANA KUDPENG

The aim of this study is to compare amino acids and organic acids in the extraction of gold from silicate ore. Amino acids were found to have higher efficiency of gold extraction than organic acids at the same acid concentration, which is likely due to amino acids having both carboxylic and amine groups in their structure, while organic acids only have carboxylic groups. Five amino acids (glycine, aspartic acid, glutamic acid, lysine and tryptophan) and seven organic acids (citric, malic, tataric, fumaric, oxalic, succinic and ascorbic acids) were selected to investigate gold extraction efficiency. Aspartic acid was found to have greater capacity to extract gold than succinic acid. The optimal gold to aspartic acid molar ratio was 1:6, and low concentrations of aspartic acid extracted 35 to 42 percent of gold from silicate ore within 15 days. Further studies are needed to increase gold leaching and reduce incubation time. The results imply that aspartic acid can be used as an alternative reagent to traditional methods for extracting gold from ore. This method is nontoxic to humans, is environmentally friendly and can have real applications.

By S. L. Crouch

The general term "coal mine burp" refers to the sudden and violent failure of in situ coal. Coal bumps occur in most countries where coal is worked by underground methods, and are related to both geological factors and mining tech¬niques. Although no single set of circumstances is solely responsible for causing coal bumps, it is generally agreed that at least one of five conditions is necessary in order for then to occur: 1,2,3,4 (1) the depth of cover exceeds 500-ft., (2) the overlying strata are relatively strong and stiff, (3) the coal is structurally strong, (4) the floor does not heave readily, and (5) the mining method produces high stresses over a large area of the seam. Except for the last, these conditions relate to geological factors that are impractical to control. Consequently, methods of controlling or minimizing the occurrence of coal bumps usually are concerned with mining techniques. Coal bumps have been successfully controlled by both longwall and 'yielding pillar' mining systems 4. The longwall system is particularly effective in controlling bumps, but does not eliminate them completely, especially in strong coal seams being worked at comparatively great depths, say in excess of 2000-ft.5. Under such conditions, auger drilling or water infusion often prove helpful 5,6. These techniques are used to destress or otherwise alter the mechanical properties of the coal in an attempt to shift the peak "abutment pressure" away from the immediate vicinity of the face. Under 'normal' conditions, however, it can be expected that the coal near the face will be crushed under the prevailing high stress conditions and that the peak abutment pressure will automatically be shifted into the solid coal. In this context, coal mine bumps can be characterized as unstable releases of energy associated with successive yielding of portions of the coal seam with progressive mining. Longwall and yielding pillar mining systems are effective in controlling coal bumps because they ordinarily do not allow the zone of peak abutment pressure to become 'surrounded' by destressed coal.

Jan 1, 1973

By R. Berton, M. Walden, S. Melberg, N. Rocco

Recent tailings dam failures around the globe have influenced many mining industry regulators to reassess their requirements for the numerical modelling of tailings dam failures. This type or forward modelling is associated with overarching uncertainties as the model cannot be calibrated against a physical result. Dam breach analyses that meet the requirements of current industry standards and guidance typically begin with identification of credible failure modes and selection of appropriate topographic data set to represent the study area. The breach parameters and the volume of tailings released are then determined using available methodologies and empirical relationships. Subsequently, when the breach hydrograph is developed and the hydrology of stream networks are complete, the runout simulation is implemented. Due to the uncertainty involved in the process, sensitivity analyses are recommended to quantify variations in model inputs on the inundation extent and the flow characteristics. This paper outlines some common methodologies utilized for development of dam breach models, summarizes associated uncertainties with these methodologies and inputs, and provides guidance on how sensitivity analyses can address a wide array of uncertainties inherent in tailings breach analyses. This paper provides an understanding of how selecting appropriate breach parameters can result in reasonably conservative inundation extents consistent with the identified credible failure modes.

Mar 2, 2022

By K. Lang

The use of high-efficiency electrical submersible pumps (ESPs) for large scale, open pit mine dewatering operations provides a good example of how technology, products and services from the oil and gas industry can be adapted to the mining industry. In this case, the mine is Goldcorp?s Peñasquito in the Zacatecas state of Mexico, at the Peñasco and Chile Colorado open pit deposits. The technology, products and services are from Schlumberger artificial lift (AL) and Schlumberger industrial water services (IWS). Overview of high-efficiency ESPs This section provides a brief description of the basic components, specifications and operating capacity ranges for the ESPs compared with traditional or conventional dewatering well pumps. This information helps to establish how ESPs provide certain functional and economic advantages over conventional pumps in a mine dewatering application. A schematic of a high-efficiency ESP in an oil and gas (O&G) application is shown in Fig. 1.

Sep 1, 2013

By J. Iannicelli

Spray drying is the principal drying method used in the production of over six million tons annually of beneficiated kaolin in Georgia. Thirty-three dryers in the Georgia Kaolin belt comprise the highest concentration of large tonnage spray dryers in the world. The steady growth of spray drying in the U.S. kaolin industry is paced by advances in design and development of large spray dryers which have led to large scale new applications in mining and related industries.

Jan 1, 1982

By David L. Kuck

Siderophyle platinum-group metals and sane gold are a thousand times more abundant in metal and chondritic meteorites than in terrestrial or lunar rocks. Type I and II carbonaceous chondrites contain granules of the high boiling point metals W, Re, Mo, Ir and Os. Metal meteorites and the metal fractions of other chondrites contain siderophyle Pt, Pd, Ru, Rh, Os, Ir and Au. Spectra of sunlight reflected from asteroids, when compared with those of meteorites and specific minerals, provide a rough classification and guide to sources of precious platin-group metals.

Jan 1, 1982

By Jürgen Brune

This is a shortened version of the paper ?The Methane-Air Explosion Hazard Within Coal Mine Gobs published in the 2013 volume of SME Transactions (Brune, 2013, pp. 376-390). This paper analyzes the explosion hazard resulting from the formation of methane-air mixtures in the mined-out gobs of underground longwall coal mines. Evidence from numerous mine explosions suggests that explosive methane zones can form within longwall gobs. Explosions and fires resulting from these methane accumulations have led to severe and fatal injuries to the miners, including the explosion of the Upper Big Branch Mine in West Virginia, where 29 miners lost their lives April 5, 2010.The paper also reviews current research on numerical modeling of gas flows in longwall gobs and outlines how targeted injection of nitrogen into gobs can effectively reduce the volume of such explosive methane zones. The paper concludes that comprehensive monitoring of gas compositions, along the accessible fringes of the gobs along with inertization, improved ventilation schemes and further research are necessary to control this explosion hazard and make mining operations safe. Keywords: Longwall, gob, methane, EGZ, explosive gas zones, underground, coal, explosion, fire

Feb 1, 2014

By Brad Simser

Several case histories from Glencore’s Sudbury Operations show how passive seismic monitoring data is used for geotechnical decision making. The data comes from three different seismic arrays monitoring two open stoping deposits, and a narrow vein cut and fill/blasthole operation. Mining depths range between 1000 to 1680m below surface. The deposits are hosted in hard igneous rocks typical of the Sudbury basin, with characteristically high horizontal stress (approximately 1.8 times the depth of overburden). Rockbursting is the main geotechnical risk, due to the strong brittle nature of the rock and local high mining extraction. Fault related seismicity includes both fault slip events, and the stress channelling effect as the mining front approaches a major fault structure. Planar data trends generally line up with known faults and often indicate early stage fault activation. The structures are risk ranked based on their seismic response. This has been particularly useful at the Nickel Rim South Mine (NRS) where the structural fabric (jointing and small-scale faulting) is generally parallel to the more through going faults. The persistence of structures is difficult to measure, and the NRS faults generally have low offsets and thin gouge. The visual difference between the more persistent structures that occasionally generate large seismic events (up Mw 2.9 to date) and localised joints/slips is often minor. The seismic monitoring data clearly shows the more active structures. This information is highlighted on mine plans to help guide enhanced ground support and seismic re-entry protocol barricade locations. Pillar loading/yielding is a key element to the blasthole operations where a primary/secondary mining sequence is used. The secondary pillars are mined in a yielded state with just-in-time development. An example of the seismic signature of a secondary stope is shown with emphasis on the need for high location accuracy given the stope widths of 12.5 to 15m. The ratio of the shear wave energy to primary wave energy (Es/Ep) has long been used as a method to estimate source mechanisms; the higher the ratio, the more likely the event is fault slip versus rock fracturing. Data sets are filtered on Es/Ep ratios to highlight both fault slip populations and stress fracturing mechanisms. Examples of seismic data quality checks, high stress development, and re-entry protocols are also shown in the case histories.

Apr 26, 2022

By R. W. Culbertson

During the 1920's, approximately 11,000 small gasifiers were in operation in the United States. They converted about 15 million tons of coal per year into low Btu gas. In some cases, hot raw gas was used for applications such as firing open hearth furnaces or brick kilns. In other cases the gases produced in the gasifiers were cooled, cleaned and desulfurized for various utility and industrial purposes. The steel industry was by far the largest user. The most important fact was that the conversion of coal to a usable fuel gas was demonstrated to be commercial. During the late 1940's and early 1950's, this form of energy was largely replaced by natural gas as the pipeline net work was expanded. Producer gas was no longer economically competitive. Over the past twenty-five (25) years, government controls on the interstate price of natural gas have maintained this situation. At present only three commercial small coal gasifier plants are still in operation in the United States. These facilities are operated by the Glen-Gery Corporation which is located in eastern Pennsylvania; the National Lime and Stone Company which is located at Carey Ohio; and Holston Defense Corporation which is located at Kingsport, Tennessee. There are, however, numerous operating gasifiers in other parts of the world. Recent events indicate that this situation is changing. The quantity of domestic natural gas available to the interstate market has been declining at the same time that demand for all forms of energy has been increasing. The current potential market for gas with a heating value ranging from 100 to 500 Btu per cubic feet has been estimated at sixteen (16) quads (16 x 1015 Btu) per year. This is expected to grow to twenty (20) quads by the year 2000.

Jan 1, 1978

By Ken E. Baylis

Current over-capacity in coal production provides assured and relatively low-cost supplies to coal importers. At the same time, it is of serious concern to coal producers who invested considerable sums in the expectation that overseas demand would continue to grow rapidly. This paper assesses the reserves available for export, the export facilities, the coal supplies which can be put through them, and the market prospects for the future. It assumes, rightly or wrongly, that there will be no major and prolonged disruptions in supply from any major sources of coal. COAL RESERVES FOR EXPORT Economically recoverable reserves in the non-communist world amount to about 470 billion tonnes. These are sufficient to sustain current production levels of 2 billion tonnes a year for 235 years.

Jan 1, 1984

By J. Drelich

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size and distribution of mineral inclusions in coal on its wettability are briefly reviewed.

Jan 1, 1999

By C. D. Taylor, A. L. Mazzella, A. L. Martikainen

In fluctuating airflow, continuous air velocity recording is the most reliable method of air velocity measurement. It allows for fast recognition of changes and the calculation of long-term averages. Also, it enables the mine operator to identify when the airflow has decreased to a point requiring action. Using ultrasonic anemometers provides an accurate option for continuous air velocity monitoring. This paper provides information about the effect of common obstructions in underground mining on air velocity readings. Stationary and moving obstructions are used to represent workers and equipment that would cause discrepancies in measured airflow. Also, it is important to know how large of a sample size is required to ensure reasonable accuracy of results. Statistical analysis is used to evaluate the required sample size. The sampling procedure is further studied by comparing two different sample rates. The results show that obstructions provide noticeable differences in air velocity measurements. Also, movement of obstructions can be recognized from changes in results. Surprisingly small sample sizes provide reliable air velocity information. Standard sample rates are found to be suitable for the underground environment.

Jan 1, 2011

By José Ricardo Lopes, Alaor Coelho, Marco Gomes, Alfredo Dacio Moraes Filho, Akira Koshima

"Very low strength alluvial peat soil was found under two old drainage galleries with just 4.3m cover above a twin tunnel due to be excavated by a 10.6m diameter EPB Shield for São Paulo Metro’s Line 5. Alignment was required to strengthen soil and drive the TBM through safely without damaging the galleries. The design included six levels of self-drilling forepoling with lengths up to 15m, using 100 mm-diameter SCH160 metal tubing and injection bulbs with estimated 0.20m diameter. Two 6m-diameter circular shafts were excavated along the shield-tunnel axis, one each side of the galleries, and forepoling fanned out under gallery foundations. Given the peculiar soil and confined working space, more data were needed for correct drilling geometry. Ground mass treatment was successfully designed and executed and galleries were fitted with instruments to enable the shield’s advance. DESCRIPTION São Paulo Metro’s Line 5 (aka Lilas or purple line) is adding 11 stations along an 11.5km extension and three EPB TBMs are being used simultaneously (three EPBs on the same job for the first time in Brazil) with one of them excavating a large cross- section twin-track tunnel. Currently the largest work-in-progress for São Paulo Metro, this project has been divided into seven lots and 9km are already operational. This study refers to Lot 6 where the 10.6m - diameter EPB shield excavation is only 4.3m below two galleries running through a 10m layer of very soft peat soil in an old alluvial riverside region ringed by major roads. After recent filling, this area (Parque das Bicicletas) was used for recreation, although temporarily it has become a construction site. This paper will describe the original basic design; precautions in relation to the structural condition of the galleries after inspection; the problem of absence of data for their foundations; subsoil bore tests; evolution of the engineering design for the galleries and conditioning and reinforcing the soft soil below the galleries to ensure safe advance of the EPB shield, and finally the successful outcome of the solution used."

Jan 1, 2016

By R. O. Harma

Wet autogenous grinding is utilized in three iron ore concentrating plants operated by The Cleveland-Cliffs Iron Company (CCI). This paper will trace some of the development in converting from the use of metal grinding mill liners to the use of rubber and will update the current performance of rubber liners in these applications. The Cleveland-Cliffs Iron Company is a natural resources firm with major interests in iron ore mining and processing and oil and gas contract drilling. The company also has interests in oil shale, uranium, forest products, and Great Lakes shipping.

Jan 1, 1982

By Sam Rosenblum

The anomaly ratio is obtained by dividing the analyzed value of an element by the anomaly threshold value of the element. The sum of anomaly ratios for all anomalous elements in a sample may be compared with similar sums for other samples, so that the samples having the greatest anomaly-ratio totals can be recognized easily. In partial or full-suites-of-ore-elements the use of anomaly ratios is more meaningful than analyzed values because the ratios quickly indicate anomalous elements and call attention to samples and localities that should be investigated.

Jan 1, 1980