Search Documents

By Vincent A. Scovazzo

During the winter months of late 1985 and early 1986, residents along Dry Fork near Grundy, Virginia (United States) experienced seismic events that they attributed to longwall mining at Island Creek Corporation’s (Island Creek) Virginia Pocahontas Mine No. 3 (VP-3 mine). Island Creek contacted STS D’Appolonia Ltd. (STSDL) on March 7, 1986, to investigate these events. An STSDL representative, Vincent Scovazzo, interviewed residents of Dry Fork on March 10, 1986. It was noted that only people within a residential structure felt the events they described as house shaking, vibrating walls, and ceramics falling from shelves. STSDL representative installed a blast monitor at a residence. Within 2 days, various events were recorded. Some could be attributed to truck and heavy equipment movement. Eight events had no obvious cause but appeared on resident’s written logs as earthquakes caused by mining. STSDL contacted Utah Geophysical, Inc. who had developed a technique to determine the mode of rock failure using the seismic record. Utah Geophysical was engaged to install and monitor a microseismic network, locate the epicenter of the events, and work with STSDL in determining modes of failure. The network was comprised of six geophones located at five stations. Data was recorded for 24 days from May 20 through June 13, 1986. The data was filtered to eliminate events determined to have an origin other than the longwall panels’ overburden and under-burden. The larger events from this filtered data set were selected and analyzed to determine their hypocenter locations, time of occurrence, magnitudes, and failure mode. Processed data was interpreted, tabulated, and plotted by STSDL to provide information relative to the sources of the seismic vibrations and their possible relationship to the mining operation.

Jul 1, 2023

By Joseph W. Johnson

General Electric introduced electric drive systems on 85 ton Off-Highway mining trucks in the early sixties. Due to favorable economics, trucks have increased in size to handle larger payloads. Series Motorized Wheel systems were developed to meet this demand. When the technology was available, General Electric switched from use of Series motors to separately excited motors with the added benefits of static exciters and simplified control. Over 20 years of electric drive experience have been incorporated in the STATEX drive systems, which covers truck sizes from 85 to 220 tons. This paper traces the drive system developments from the early stages to the present and takes a look at what's ahead.

Jan 1, 1983

By R. R. Klimpel

The industrial processing of ores containing precious metals such as gold is generally very mining site specific, e. g. McQuiston and Shoemaker (1985), vanZyl et. a1. (1988), Fuerstenau and Hendrix (1990), and Hausen et. a1. (1990). The variety of various mineral processing techniques employed is extensive and includes size reduction, size classification, gravity separation, roasting, cyanidation, chemical and/or bacterial leaching, ion exchange and/or solvent extraction, and froth flotation. Gold occurs in the earth's crust on the average in very low concentration estimated by various sources to be between two and five parts per billion. For a specific ore deposit to be considered as an economic source of gold, generally a concentration of near one part-per million (one gram / Mton) or more is required. From a mineralogical viewpoint, gold often occurs in its native or free form. However, it can also occur as gold compounds of telluride, antimony, and selenium contained within either sulfide minerals such as pyrite, arsenopyrite. and pyrrhotite or, to a less extent, within silicate, oxide, and carbonate minerals. In many locations, alloying of gold with silver is found. The optimal processing method for recovering gold is determined by many factors such as the mineralogy of the gold bearing minerals as well as the associated mineralogy of the gangue minerals, the type of liberation profile of the gold bearing minerals upon' size reduction, and the particle size of the gold itself. Free or native gold particles can vary in size from the extreme of large nuggets to very finely disseminated gold associated in a complex sulfide mineral matrix. Typically free gold particles of several hundred microns or larger are efficiently recovered by one or more of a number of gravity based techniques due to the large specific gravity differential of gold (19.3 to 15) versus typical gangue minerals (5 to 2.7). When gold is associated with a sulfide (usually pyrite) matrix, historically most industrial plants involving size reduction and subsequent liberation have operated in a size range of 50 to 80 percent less than 75 microns. Grinding finer than this has been normally not economical unless the ore has a high gold content in the feed ore.

Jan 1, 1998

By K. J. Shelswell

This work describes the design, analysis, and comparison of discrete simulation and static spreadsheet models developed to compare the oreflow efficiency of two conveyor-based material handling systems; one approach with a conveyor stream in series and one with parallel conveyor streams. Analysis and comparison indicated that daily rates were significantly affected by random conveyor failures in both designs. The compound effect of random failures limited the effectiveness of long belt assemblies in series, while the parallel conveyor stream design partially alleviated this constraint. The static spreadsheet model predicted a lower average daily oreflow rate for the series conveyor stream design and a higher average daily oreflow rate for the design with parallel conveyor streams when compared to the discrete simulation results. These discrepancies were the product of model sensitivity to operational factors incorporated in the system and provided the opportunity to further use the discrete simulation models for trade-off comparisons and sensitivity breakdowns of mine operating practices and material handling system efficiencies in both the series and parallel belt stream designs

Feb 23, 2014

By K. E. Harrison

Acid rain legislation as proposed by President Bush [1], if enacted, will immediately refocus current thinking on the economic decision-making as related to coal preparation facilities. Unit operations currently ignored because of their costs, will become mandatory to coal plant designers and operators to ensure maximum energy recovery and sulfur reduction in the entire coal stream. In anticipation of this need, the U.S. Department of Energy, The Ohio Coal Development Office, EPRI and others are sponsoring research in several areas of coal preparation, and coal plant designers are beginning to consider more innovative techniques as they configure their flowsheets for plants of the future. Preparation plants then will have recleaning

Jan 1, 1990

By Yi Luo, FENGLIANG WU

Explosions and fires originated from longwall gob due to the formation of methane-air mixture have been a severe threat to coal miner’s lives.Many numerical studies on coalmine fire and explosion hazards have focused on the airflow in roadways and mine gobs. However, most of these studies isolate the gob from its surrounding roadways, and the network analysis and the CFD method are applied independently tomodel the two classes of airflows. This approach greatly limits the ability of simulatingmine ventilation flow, especially unable to consider the effects of gob boundary conditions on air exchange between the gob and the surrounding airways. An innovative finite tube method (FTM) is developed to couple the one-dimensional mine ventilation network (MVN) and the 2D/3D gob flow field (GFF). In FTM, GFF is discretized into a finite number of flow tubes each of which is formed by any two adjacent stream lines. These tubes, representing the gob’s field flow, connect the MVN into a new coupling network. To solve the coupling model betweenMVN and GFF, an iterative solution technique is developed inwhich the MVN analysis is used to evaluate the boundary pressures for GFF simulation and in turn the FTM feeds the GFF results back to the coupling network. Based on the FTM approach, a model for gas migration in gob has been established for delineating the hazard zones of explosive methane concentration and spontaneous combustion. A computer program is developed to implement the FTM simulation. An illustrative example with five flow tubes representing the GFF is created to verify the stability and convergence of the FTM solution process. A simulation example also indicates that the accuracy of FTM is improved by 12% compared with previous method. Results of an application case show that the program is capable of quantitatively evaluating the gob’s risk zones prone for spontaneous combustion and gas explosion as well as performing risk analysis for various ventilation scenarios.

Jul 10, 2020

By W. W. Kephart

The glass container industry is the largest producer of glass in the United States. As of this writing, there are approximately 89 active domestic production locations. In 1984, the industry shipped 11.8 million tons of glass containers. Approximately 70% of this production was clear or flint glass, 20% amber, 7% green, and the remainder miscellaneous colors. Although the production of nearly 12 million tons of glass is impressive, anyone following the industry over the last five years is aware that the industry has changed from a pattern of growth in the 1970's to one of maturity in the 1980's. Some observers, less generous, perhaps, have described the 1980's as a period of decline. In 1981, there were 119 production facilities which produced 13.2 million tons of glass the previous year. This equates to a 10% reduction in glass container production from 1980 to 1984, with a corresponding impact on the segment of the industrial minerals producers serving the container glass industry, as shown in Figures 1 and 2.

Jan 1, 1986

By Xiaohong He, Qing Yu, Kaixiang Zhang, Rui Guo, Minghua Lin, Haoyu Miao

With the increasing depth of coal mining, the coal mine shaft traverses’ strata conditions become more and more complex. Shafts are often located in deep thick strata with unstable aquifers, and coal mining requires short-term rapid drainage of aquifers; the additional stress caused by aquifer water drainage is the direct cause of the shaft-lining failure. Over the years, many experts have conducted research on the shaft-lining damage caused by the consolidation and subsidence of the soil layer induced by the long-term drainage of the aquifer. On this basis, this paper conducts an in-depth study of the dynamic change of the pore water pressure of the aquifer in the short-term drainage and its influence on the response of shaft-lining strain and surface subsidence. The result shows that the Mandel effect of pore water pressure around the shaft-lining is obvious at the beginning of drainage, and the pore water pressure suddenly increases; the increase is independent of the drainage rate, which leads to the sudden increase of the shaft-lining strain value unrelated to the drainage rate. The result also shows that with the gradual dissipation of pore water pressure, the increase of shaft-lining strain is positively related to the drainage rate and negatively related to the drainage distance, and the variation trend of horizontal strain is greater than that of vertical strain, which appoints the main cause of shaft-lining damage.

Mar 16, 2023

By Bijan Taheri, Behrouz Maghsodi, Monireh Heshami, Reza Kohan

A common problem recently encountered with the increase in the rate of input feed at Enrichment Plant 2 of the Sarcheshmeh Copper Complex is the loss of value to the tails, translating to lower recoveries. The feasibility of the direct transfer of part of the high-grade concentrate from rougher stages to an appropriate position along the circuit was studied, and two positions were proposed for direct transfer of the concentrate. One position was the feed flow into cleaner cells, and the other was the feed flow into the recleaner cell. The results indicated that transferring the concentrate from the first unit of the rougher stage to the feed flow into the cleaner cells was feasible, with no limitations, while the second position required the installation of a set of hydrocyclones. It was found that the transfer of concentrate to the proposed positions not only addressed the problem of limited cell capacity, resulting in debottlenecking of the circuit, but also improved metallurgical separation efficiency up to 1.4%.

A kinetic model for leaching of various metals with different lixiviants in a batch system has been developed. Material balances for reactants and products at the solid/liquid interface were formulated and solutions to these balances were obtained in view of practical conditions. Special emphasis has been given to examine mixed controlled reaction systems where both heterogenous reaction and mass transfer play important role on the overall rate expression. The resulting kinetic expressions for either powder or rotating disc are discussed in light of experimental findings for various metals. Examples of the metal dissolution systems considered in this study include cobalt, nickel, copper and gold in acid, cyanide or ammoniacal solutions.

Jan 1, 1992

By Mahmud Esad Uluer, Seyed Hassan Amini, Aaron Noble, Matt Shigo

Airborne coal mine dust is an unintended and unavoidable result of coal extraction operations that raises notable health and safety concerns. Modern mining techniques utilize several dust mitigation strategies, and the flooded-bed dust scrubber (FBS) is one such technology used extensively on continuous miners. The conventional static panel filter, instrumental in most scrubber designs, is fundamentally limited in collection efficiencies due to a high clogging rate and a tradeoff between mesh density and airflow rate. To overcome these deficiencies, a novel vibrating mesh panel is proposed. In this study, a laboratory-scale dust scrubber unit was used to investigate the efficacy of concept as compared to that of a static mesh. A statistical design of experiments study was first used to determine the effective vibrational parameters and scrubber operational parameters on dust collection and clogging mitigation. Optimized results from this study were then evaluated against those of a static mesh to determine performance improvement while investigating the mechanisms controlling dust collection and particle department through the scrubber system. Results show that the vibrating mesh conditions and higher water flow rates led to an improvement in the collection efficiency of the scrubber system. Compares to a static-mesh, the vibrating mesh FBS showed a significant reduction in pressure drop across the mesh screen indicating lower air loss through the test duration. Overall, the findings confirm that vibrating filter mesh reduces filter clogging while maintaining high collection efficiencies. This research supports further technological advancement in mine dust mitigation technologies.

Dec 27, 2023

By Y. C. Kim

The strongly skewed grade distributions and the need to estimate the local recoverable reserves in a selective mining environment are the two problems that Ordinary Kriging (OK) cannot easily handle. With the recent introduction of the nonparametric, distribution-free technique of Indicator Kriging (IK), the above problems can be solved. This paper describes the results of performance evaluation of IK in an open-pit gold-silver deposit. For performance evaluation, the predictions of local recoverable reserves using IK were compared with the actual reserves based on blast hole information. The IK estimator, although a bit optimistic, performed very well in predicting the total recoverable ounces of gold from each panel on a test bench. The OK estimator was also used to try to predict local recoverable reserves, by treating each panel as either waste or ore, depending on the panel's average grade. Under this criterion. OK was found to be very biased and pessimistic.

Jan 1, 1986

By Elza Burch

Introduction The feeding to zero concept involves feeding 600 µm x 0 (28 mesh x 0) size raw coal to heavy media (magnetite) cyclones along with the +600 µm (+28 mesh) size coal. Traditional circuits employ desliming or removing the 600 µm x 0 (28 mesh x 0) size fraction and feeding the cyclones +600 µm (+28 mesh) size coal. The feeding to zero concept recirculates 600 µm x 0 (28 mesh x 0) fines in the circuit. At the same time, a portion of the fine material is continuously withdrawn and recovered. This, in turn, prevents a fines buildup. This concept eliminates desliming screens and secondary fines circuitry for recovery of 600 x 150 µm (28 mesh x 100 mesh) coal. The result is a very simple circuit. Feeding to zero at Island Creek Island Creek Corp. was the first involved with the new concept in 1976. The company needed a temporary plant for the 9.5 mm x 0 (0.4 in. x 0) raw coal at its Pond Fork mine, near Madison, WV, while a full-scale plant was being designed and built. At that time, the Childress Corp., of Beckley, WV, became interested in the feeding to zero concept. Island Creek awarded a contract to Childress to build a single cyclone modular plant, incorporating this feeding to zero concept. The plant was erected in three months. The Pond Fork modular plant proved successful in attaining the desired feed rate of about 63.5 t/h (70 stph), while maintaining good separating efficiencies and low magnetite consumption rates. The 9.5 mm x 150 µm (0.4 in. x 100 mesh) clean coal was recovered and the 150 µm x 0 (100 mesh x 0) size was disposed of to waste. The full-scale plant was completed about two years later and the Pond Fork modular plant was moved to Holden, WV. There, it was incorporated into the Holden 29 preparation plant as a separate circuit for cleaning -25 mm (-1 in.) coal. In 1976, a similar plant was installed in Virginia by another company. These two plants are believed to be the first two operational plants in the United States incorporating the feeding to zero concept. Island Creek subsequently contracted with Childress for an identical plant at the Coal Mountain operation in West Virginia. The plant operated for three years before the mine was closed. The unit was then moved to the Spurlock mine near Martin, KY where it continues to operate. The successful operation of the Pond Fork and Coal Mountain plants before and after relocation proved both the performance and moveability of this type of circuit when constructed in a modular fashion. Since the first two plants were built, Island Creek has incorporated the feeding to zero circuit in nine additional plants. A grand total of 33 cyclones have been installed using this concept. One is the Providence mine, near Providence. Providence preparation plant Island Creek contracted with J.O. Lively Corp. of Glen White, WV in July 1978 for the construction of the Providence preparation plant. The plant began operation in February 1979. The construction period was about halved by building the plant with modular design concepts. Prefabricated sections, floors, and sides were brought in as units and then bolted in place. The Providence plant has a good track record of processing coal at a feed rate of 454 kt/h (500 stph). Feed coal to the plant has an average ash content of about 18% and sulfur content of about 4.5%. It contains about 22% refuse. The coal product has an average ash content of about 8% and sulfur content is about 3%. Raw West Kentucky No. 9 seam coal is conveyed from a box cut in the Providence mine to a rotary breaker. The breaker is fitted with 74 mm-diam (3 in.-diam) opening breaker plates. Therefore, it is well suited for removing trash, roof bolts, wood, and pyritic balls that are common in Illinois Basin coal. The -75 mm (-3 in.) coal is conveyed from the rotary breaker to

Jan 8, 1987

By E. F. Schnitzer

During 1996 and 1997, Oregon experienced flooding on a scale not seen in many years. Some gravel pits located near rivers experienced erosion and, in several cases, breaches between the gravel pit and the river. Initial evaluation of several sites that experienced breaches indicates that impacts to the river system are complex and vary significantly from site to site. The impacts to the adjacent river system may be viewed as both positive and negative. Several floodplain-mining sites in Oregon located in areas of historic river flow have reverted to active riverbed. In many cases, state and federal fisheries biologists and university researchers see the resulting increase in channel complexity and habitat as favorable. The Oregon Department of Geology and Mineral Industries -Mined Land Reclamation Program (DOGAMI-MLR) is performing additional studies of the impacts to the off-channel areas that resulted from the 1996 floods. More data is needed to make sound floodplain decisions regarding mining.

Jan 1, 1999

By Utku Gumus, Ertan Bostanci, Hanifi Copur, Ahmet Rüfai Bilgin, Ugur Altay

"Field observations on replacements of 12-inch constant cross-section double disc cutters in Tuzla Wastewater Tunnel excavated by an EPB TBM with 3.151 mm excavation diameter excavating hard rock are summarized. Cutter life is correlated to rock’s uniaxial compressive strength and Cerchar abrasivity index, and TBM operational parameters. Number of cutter replacements, average cutter replacement rates and types of cutter damages are summarized. The relationships between cutter life and rock properties and TBM operational parameters are analyzed by single variable regression method. Detailed analysis between chainages 1+200 and 1+982 km indicates that average cutter consumption rate is 35.7 m3/replacement (4.6 m/replacement). Cerchar abrasivity index and uniaxial compressive strength does not indicate any meaningful relationship with cutter life. Penetration per revolution and field specific energy might be used for predicting lives of constant cross-section double disc cutters. However, additional data is required to generalize the findings of this study. INTRODUCTION Cutter life / replacement and/or consumption rates in terms of cutter cost and replacement time loses is one of the most important parameters affecting excavation performance of mechanical excavators, especially of TBMs used very widely and equipped with usually disc cutters. Predicting cutter cost is a very important task in especially feasibility stage of tunneling projects. Basic parameters affecting cutter life can be classified into 3 general groups as geological and geotechnical, excavation machine (TBM) related, and operational parameters (Bilgin et al., 2013). The geological and geotechnical parameters are the most dominant ones among them. The machine related parameters should be arranged in accordance with the expected geological and geotechnical conditions for the best TBM excavation performance and minimum cost."

Jan 1, 2016

By R. J. Reuss

The ore at this new underground operation is a massive sulfide breccia with high copper values. A major highway and electric transmission line pass directly over the near-surface orebodv. The mining method being used is undercut and fill. A continuous miner together with a single boom, hydraulic jumbo is used for the mining. Backfill is a weakly cemented sand-gravel mixture that is pneumatically placed. The ore is treated by conventional crushing, milling and flotation.

Jan 1, 1992

By G. H. Harris

The flotation behavior of two high sulfur coals using a non-ionic surfactant as collector from two series of compounds containing oxygenated functional groups was studied in detail using a 2-liter Denver flotation cell. The performance of these reagents was compared with that of an oily collector, namely dodecane. The results showed that at the same coal recovery, a much lower dosage of these non-ionic surfactants was required as compared with that of dodecane. More import was the performance of these compounds as promoters for oxidized as well as un oxidized coal. Mechanisms of interaction of these compounds with the coal are suggested.

Jan 1, 1993

By William Gleason

The mining industry is a unique space. It is one in which geologists and chemists can intersect with computer and data science professionals daily. The industry requires expertise in not just mining and metallurgical engineering, but also electrical, mechanical, environmental and more. It requires expertise in worker health and safety, behavioral science, finance and economics, as well as human resources management. The locations of mining operations are often in remote corners, and for underground activities, they are unlike anything else in the world. The industry presents those who join it a wealth of opportunities, but often struggles to overcome incorrect perceptions of safety, labor and environmental standards, making it difficult to recruit and retain employees at a time of increased demand for mined materials.

Dec 1, 2025

By R. E. Williams

University of Idaho scientists research under U.S. Bureau of Mines Cooperative Agreement C0278001 constitutes a complex hydrogeological, hydrochemical and metallurgical mine waste management project at an existing Superfund site. Technologies that may prove useful for the extraction of dissolved metals from acid mine water and solid wastes include lixiviation and biosorption. Acid mine water is the major, long-term problem in the valley. We are attempting to delineate the major sources of ground water recharge which feed the acid mine drainage and their hydraulic properties. Grouting of recharge areas may facilitate minimizing the production of acid mine drainage if recharge pathways can be identified.

Jan 1, 1990

Atlas Copco, a leading supplier of equipment and services to the mining and construction industries, is consistently pursuing its strategy to offer the most productive and economical solutions by continuously offering new innovative products. These are in most cases developed and tested in close cooperation with demanding end users before Being officially launched on the international market. The demands for higher productivity and improved overall economy have resulted in systems for automation of the drilling cycle and also tools for integrating the Drilling equipment to the production control system used by the customer. In terms of improving the blasted material quality, Atlas Copco has placed emphasis on hole straightness and the need for hole logging and positioning. By applying state of the art Technology to today?s computerized drilling rigs, major steps in improving overall drilling and blasting performance have been achieved. This paper will give some examples derived from the latest development of solutions for the Rotary drilling product line.

Jan 1, 2010