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Pillars in underground limestone mines are required to support the overburden and provide a safe, stable working environment for mining personnel and equipment. Pillar stability was assessed by the National Institute for Occupational Safety and Health in underground limestone mines in the Eastern and Midwestern United States. It was found that current mine layouts have been successful in providing support to the overburden, while a small number of isolated pillar failures were observed. The stable pillar layouts and failed pillars were plotted on a chart that demonstrates the relationship between pillar width-to-height ratio and pillar stress. The results show that pillar failures occurred at the lower range of width-to-height ratios and can occur at relatively low stress levels. Zones indicating the potential risk of pillar instability are shown on the chart, based on hazards associated with the onset of rib spalling, large angular discontinuities and unconfined pillars. The chart can assist limestone mine planners to evaluate potential instability in current or new pillar layouts that are similar to those included on the stability chart.

Jan 1, 2008

By H. M. Lizama, R. L. Stephens

Secondary leaching of previously leached supergene copper ore has been developed and implemented at Teck’s Quebrada Blanca operations. This consists of using in-situ leaching techniques aided by geophysics to recover the residual metal value from dormant copper leaching heaps. These heaps of crushed and agglomerated ore had been leached 20 years previously but still contained significant copper values. The concept was first tested on a 3,200 m² sector, where injection wells introduced leaching solution into a production zone and electro-resistivity tomography was used to track solution movement within. Operating parameters such as well spacing and injection flow rates were determined. Copper recovery and leaching performance were evaluated based on solution and metallurgical balances. Both ferric leaching and bacterial leaching were enhanced through strategies to pull air into the heap. Positive results from the initial test prompted a larger, industrial pilot test on a 60,000 m² area and 97 injection wells. This larger test obtained a copper recovery of 30% in 457 days. Secondary recovery is now being implemented to all of the abandoned heaps at Quebrada Blanca and has become a production stream. This technology has the potential of wide application to mature copper heap leach operations, and Teck has patented the process and associated methodologies. INTRODUCTION Heap leaching of copper secondary sulphides has been carried out at Quebrada Blanca (QB) since 1994. Ore from the supergene deposit was crushed and agglomerated prior to leaching. Originally, the ore was leached in 6 m lifts stacked one on top of another, known as a static pad configuration. However, in 1998, after the second lift, the operation changed to a dynamic pad configuration; the ore was leached in a single lift and the resulting residues were removed to make way for fresh ore (Yáñez, Ahlborn, & Ramos, 2007). The first two static lifts were left in place and served as a foundation for the dynamic lifts above. Those two buried lifts of leached residues, some 16.8 million tonnes and covering an area of approximately 0.71 million m², remained buried under the dynamic pad.

Jan 1, 2019

By M Dandeneau, P I. Rajic, K D. Murphy, M B. Johnson, T J. Tope

"Manufacturers and users of energetic material [i.e., propellants, explosives, pyrotechnics (PEP)] generate unserviceable, obsolete, off-specification, and damaged items that are characterized as reactive waste. These items must be safely treated and disposed of or reclaimed/recycled, thereby controlling existing waste inventories at manageable levels. The most commonly used disposal and treatment method, particularly at U.S. Department of Defense (DoD) installations, is open burning/open detonation (OB/OD). However, regulatory constraints and the inability of operators toobtain permits required for treating these waste has led to the recent reductions and limited use of OB/OD treatment at many installations."

Jan 1, 1995

By U. S. Sawant

During the last few years, Process Machinery Division, Rexnord, has conducted extensive research on the effects of cone crusher variables such as speed, throw and cavity design on the productivity of the crushers. Simultaneously, Rexnord's engineers have developed advanced design and testing techniques and criteria that assure efficient and reliable crusher designs. The combination of these two has resulted in a design of the 2390 Omnicone (1000 hp) crusher which fits on an existing 7 ft. Symons foundation and yet is capable of producing twice the tonnage compared to our 7 ft. super heavy duty (500 hp) crusher. Both speed and throw can be varied to give a wide application flexibility from making twice the tonnage to the finest product. The 2390 Omnicone also incorporates innovative features such as full balance, cavity clearing, adjusting under load with automation capability, maintenance-free seals, one head for all cavities, ease of maintenance and servicing, etc.

Jan 1, 1987

By Albert Ladd Colby

PAGE I. Introduction,...........577 11. PRocess of Manufacture. 1. American Specifications. 2. Foreign Specifications, . ......... 580 III. Chemical Properties. I. Chemical Composition: (a) American Specifications ; (b) Foreign Specifications. 2. Chemical Analysis: (a) American Specifications ; (b) Foreign Specifications ; (c) Number of Analyses Required ; (d) Sample for Analysis ; (e) Check-Analyses Impracticable ; (f) Rejection Solely on Variation in Com-' position,............581 IV. Physical Properties. 1. Drop-Test and Drop-Testing Hachine: (a) American Specifications ; (b) Foreign Specifications ; (c) Limits in Deflection. 2. Tensile Test: (a) American Specifications; (b) Foreign Specifications ; (c) Test-Pieces are not Representative ; (d) Specified Tensile Strength is Affected by the Section ; (e) BpeciBed Tensile Strength is Often Inconsistent with Specified Chemistry ; (f) Specified Tensile Strength is Often Inconsistent with Specified Elongation ; (g) Amount of Tensile Testing Required is Excessive ; (11) Conclusions. 3. Dead-Weight Test: (a) American Specifications; (b) Foreign Specifications; (c) Number of Tests Specified. 4. Bending-Test: ((1) American Specifications ; (b) Foreign Specifications,..........589 V. Section. 1. American Specifications. 2. Foreign Specifications: (a) Templets ; (b) Sample Piece of Rail; (c) Allowable Variation from Templet,...........601 VI. Weight. 1. American Specifications. 2. Foreign Specifications,. . 603 VII. Length. 1. American Specifications. 2. Foreign Specifications, . . 604 VIII. Drilling. 1. American Specifications. 2. Foreign Specifications, . 604 IX. Finish. 1. American Specifications. 2. Foreign Specifications, . . 50.5 X. Branding. 1. American Specifications. 2. Foreign Specifications : (a) Data to be Rolled in Raised Letters on Web of Rail ; (b) Marking of the Blow-Number on Each Rail; (c) Additional Marking and Painting of Rails,........605 XI. Inspection. 1. American Specifications. 2. Foreign Specifications: (a) Prior Notice of Rolling; (b) Free Access to the Works ; (c) Cost of Inspection, Analyses and Tests to be Borne by the Manufacturer ; (d) Rails after Inspection by Manufacturer to be Sorted into Lots Prior to Inspection by the Engineer ; (e) Disposition of Rejected

Jan 1, 1907

By R H. Sibson

The gold province of Otago occupies an area of upwarped basement, the Otago Schist, comprising predominantly quartzofeldspathic and volcanogenic metasediments. This assemblage is the product of collisional tectonic deformation and associated metamorphism, mainly to lower greenschist facies, during the Rangitata Orogeny (200-100 Ma). Historically this region has produced 240 tonnes of gold, 4% (10 t.) of which was from the mining of Cretaceous goldquartz mineralised vein systems. Auriferous vein systems in the Otago Schist are mainly hosted within NW trending normal fault-fracture arrays, however NW trending reverse fault-hosted vein systems also occur. We propose that the Late Cretaceous-mid Tertiary Otago Schist structure represents a regional anticlinorium containing flexural folds of at least two wavelengths. The anticlinorium structure has been quantified by determining variations in angular discordance between schistosity and the Otago Peneplain, a Late Cretaceous-mid Tertiary erosion surface covering most of the Otago district. A structural model for the evolution of the post-collisional anticlinorium requires the cooling surficial zone (carapace) of a retrograding metamorphic belt to behave as an elastic lid. Erosion of topographic load on the carapace drove isostatic uplift, which was greatest in the tectonically thickened core of the orogen. In this way differential uplift produced flexural deformation in the elastic carapace, expressed as a large scale arching of the orogenic belt. Flexure created tangential longitudinal strains in the outer-arc, leading to extension and the formation of mineralised normal faults. These structures are separated by a neutral surface from shortening and associated mineralised reverse faults in the inner-arc. Our structural model predicts that the distribution of auriferous lodes should be localised about zones of maximum flexural curvature, where the tangential longitudinal strains are highest. As a result, NW-SE hinge regions separating schistosity dip domains in the Otago gold province may have new found significance as potential exploration targets.

Jan 1, 1995

By D J. Williams, S Islam

Worldwide production of black coal amounts to about 8 billion tonnes. Perhaps 20% of this annual production is washed to improve its quality, generating perhaps 250 million tonnes of coal tailings annually, generally in the form of a slurry. The coal tailings slurry is typically thickened to about 25% solids by mass prior to disposal to a tailings storage facility (TSF), and hence comprise mostly water (about 85% by volume), plus sand, silt and clay-sized mineral particles and carbonaceous material. While the tailings settle and consolidate on deposition in the storage facility, their high moisture content makes them prone to run-out should the tailings dam fail, and makes rehabilitation of the tailings difficult. Hence, it is important to understand the consolidation and shear strength of coal tailings. Laboratory consolidation testing of coal tailings from a slurry to a soil-like state has been carried out in a purpose-built, large-scale, slurry consolidometer, instrumented with load cells and pore water pressure (PWP) transducers. Laboratory vane shear testing of coal tailings produced at different gravimetric moisture contents has also been carried out. The test results have allowed a regression model to be developed relating the peak vane shear strength of the coal tailings to their gravimetric moisture content.CITATION:Islam, S and Williams, D J, 2018. Consolidation and shear strength of coal tailings slurries, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 62–71 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Roberto J. Guardia, Robert A. Robinson, John Wilkerson, Wick Haxton

Several candidate sites have been proposed for the Deep Underground Science and Engineering Laboratory (DUSEL), a facility that would provide over 2000 meters of overburden to screen out cosmic rays that would otherwise interfere with experiments. Types of anticipated experiments include: detection of dark matter and stellar neutrinos, and evaluation of deep microbial life forms. Engineering experiments might include more refined scanning devices to “see” rock defects ahead of tunneling, improved predictive models for groundwater inflows and tunnel support requirements, and improved instrumentation for monitoring in-situ stresses, rock deformations, and pore water pressures. Spin-offs from this research might include more sensitive security detectors for scrutinizing shipping containers, new drugs based on new microbes, and improved sensor systems for tunneling. A site near Leavenworth, WA, was assessed and shown to have numerous topographic and geotechnical advantages. Rock cover is on the order of 2250 meters. The granitic bedrock is suitable for tunneling a variety of large underground openings.

Jan 1, 2005

By Zwaan J, Kepa J

Ok Tedi mine has become one of the major copper producers in the world. In the process of becoming of age, it overcame the challenges of operating in a locality which is young in geological terms, experiences very high rainfall and has a topography which gives rise to frequent landslides. This paper discusses some of the geological, mine and geotechnical engin- eering aspects of the Mt Fubilan ore deposit.

Jan 1, 1991

By Guido Huillca, Gerardo Gonzales

Este documento presenta los resultados de un caso de estudio, que fue el producto de una ingeniería conceptual del diseño de la mezcla de relleno en pasta realizado para una mina polimetálica en el sur de Perú. El relleno en pasta es una mezcla de agua, cemento y relaves con alta densidad, que se utiliza en minas subterráneas como relleno en cavidades resultantes de la extracción de rocas (galerías, chimeneas, pozos, entre otros), proporcionando soporte para continuar con la minería y evitar un posible colapso

Sep 29, 2023

By B. J. Kloppers, J. V. Z. Visser, C. J. Horn

"The long-term plan (LTP) in a mineral resource company is defined by the quality of the mineral resource and represents the result of a series of trade-offs to fulfil internal organizational as well as external business and legislative requirements, ensuring ultimate delivery on the defined organizational strategy.The LTP should as a whole align to a coherent and well-defined organizational strategy, working towards a clearly defined objective while still allowing a tactical response to short-term requirements of the organization. The ability to respond tactically to changes in environment, like the unprecedented five-month strike in 2014 on the platinum belt following the 2012 Marikana incident, is a measure of the flexibility of the plan given the agreed strategy.This paper describes the Lonmin process of linking company strategy with long-term planning, tactical planning, and the execution of the plan through an annual planning cycle to maximize organizational flexibility. This flexibility enables mining companies to respond to the many internal and external forces that impact on both strategy formulation and delivery of results that meet shareholder expectations."

Jan 1, 2015

By J. R. Heberger, B. H. Ngo

The Safety Pays in Mining v2.0 web application, developed by the National Institute for Occupational Safety and Health (NIOSH) Mining Program, helps mines determine the potential costs associated with mining injuries. This web app categorizes injury cost by part of body injured, by the cause of the injury, or by the nature of the injury. When the user selects one of over 150 common types of mining injuries, the app provides information on the distribution of costs of workers’ compensation claims for that type of injury. Based on other user inputs, Safety Pays in Mining v2.0 will estimate the total costs of the selected injuries and the estimated impact of total injury costs on mining company profits and will provide some examples of services and personal protective equipment on which companies could spend the savings that result from the prevention of injuries. This paper reviews the Safety Pays in Mining version 2.0 web application by discussing the development and updates to the app, how it is used to show the true costs of mining injuries, and how mines can benefit from using this app.

Feb 1, 2024

By M. A. Mahtab

This paper presents the results of a parametric study of the influence of natural features (stress field, rock strength, and strength and orientation of fractures) as well as the influence of induced features (undercut span, boundary slot, and other boundary-weakening measures) on the cavability of an undercut block of ore in mining by the block-caving method. The two-dimensional finite element analysis technique was used for this study. A coarse "mesh," along with linear homogeneous assumptions for rock properties, was used to model the problem of initiation of caving in a block of ore. Interpretation of the test results suggests that weakening the "abutments" of the block as well as certain orientations of natural fractures exercise significant influence on cavability. These findings hold promise for immediate application to known situations in block-caving mines.

Jan 1, 1975

By Tatsunori Matsumoto

In order to investigate the variation of the load-displacement relations of piles in a site, vertical load tests were carried out on 25 small diameter steel pipe piles. Out of 25 piles, 15 piles were close-ended pipe piles attached with a blade at the pile toe and 10 piles were open-ended pipe piles. To carry out these load tests in a short period, two types of rapid load test methods, Spring hammer load test and Falling mass load test, were employed. The load tests of all piles were completed in two days with 180 blows in total. In order to estimate a static load-displacement of a pile, non-linear damping method was used. It is shown from the test results that the performance of the pipe piles such as the ultimate pile resistance and the initial pile head stiffness is improved by re-driving.

Jan 1, 2006

By E. D. Musin, S. S. Gudkov, A. V. Epiforov, S. V. Balikov

The standard technology for processing of gold-bearing sulfide raw material has many problems associated with the use of cyanide as a gold lixiviant. Therefore, many tests to find alternative gold recovery methods are being undertaken. This paper describes some technological solutions, which can become alternatives to cyanide technology in the future. Pressure oxidation (POX) of refractory gold-bearing sulfide concentrates from five different Russian gold deposits were investigated. Concentrate 1 was gold-copper concentrate. Concentrate 2 was gold-pyrite concentrate. Concentrates 3-5 were pyrite-arsenopyrite double refractory concentrates. The POX tests were at temperatures of 110, 200 and 220 °C and oxygen pressures of 1.5, 2.4 and 3.0 MPa were carried out. Gold lixiviants, such as chloride, thiosulfate, sulfite and thiocyanate were tested. The recovery of gold from sulfide gold-bearing concentrates by non-cyanide methods was 97- 99%, and from double refractory concentrates, 86-93%. The tested reagents are less toxic than cyanide, and their use will reduce of the cost of gold production. These methods make it possible to recover gold in acidic media, and eliminate the washing operation and POX slurry neutralisation. In addition, precious metals recovery from POX cakes using lead reduction smelting was investigated. It was shown that the “POX-pyrometallurgical” technology for double refractory concentrates processing could be used with recoveries of gold and silver of 97 and 96%, respectively. Keywords: Recovery of gold, refractory sulfide gold-bearing concentrates, double refractory concentrates, pressure oxidation, non-cyanide lixiviants of gold, chloride autoclave leaching, thiosulfate leaching, thiocyanate leaching, sulfite leaching, reduction smelting, POX-pyrometallurgical technology

Jan 1, 2020

By J. Haynes

Coal mines in the eastern US often use sloped shafts as production beltways for ore removal, as means of access for supplies, and for ventilation. These structures are usually completed with the help of a contractor. In late 2011, Frontier-Kemper Constructors was engaged to build a slope for a coal mine in southern Indiana. Although the site was located in familiar Illinois basin formations, the geology proved to be very difficult. This paper describes some of the challenges faced during excavation of this slope and the methods used to overcome them, including changing the method from conventional drill and blast to cutting with a continuous miner.

Feb 27, 2013

By X Hu, J Björkvall, L Sundqvist Ökvist

The metal production industry is a significant contributor to global CO2 emissions due to the use of fossil fuels such as coal and coke. To mitigate these emissions and meet climate goals, innovative and sustainable technologies are required. Molten salt electrolysis is a promising technology that directly produces metals from their precursor sulfides or oxides using electricity. When combined with renewable electricity and an inert anode, the electrolysis process can be carbon neutral. This paper presents the results of two pilot-scale studies on the electrolytic reduction of metal oxides and sulfides in molten salts. The first study focuses on the electrolytic reduction of chalcopyrite in molten NaCl-KCl salt. The results demonstrate that in situ separation of copper, iron, and sulfur is possible, enabling the extraction of all valuable elements without CO2 emissions. Furthermore, the findings underscore the capability to eliminate impurities like zinc, antimony, arsenic, and mercury from the electrolysis product. The second study investigates the electrolytic reduction of pure/synthetic chemicals of wüstite, hematite, and magnetite, as well as a magnetite-type iron ore in molten NaOH salt. The findings reveal a stepwise reduction of iron oxides from high valence to low valence, ultimately leading to the production of metallic iron electrolytically. Notably, this study underscores the challenges associated with the selection of an economically viable and durable inert anode material for efficient oxygen generation. These results indicate that molten salt electrolysis provides a sustainable and green route for base metal production. The use of this technology has the potential to significantly reduce CO2 emissions in the metal production industry, contributing to achieving climate goals.

Jun 19, 2024

By Jorge Vargas Fernández

Con el objetivo de incrementar la productividad de la minería, se plantea la realización de una positiva acción nacional de formación y capacitación en todos los niveles de la industria minera a través de un análisis de la situación actual respecto de los mineros, ingenierios y técnicos. Por ello, el presente texto señala la descripción del sistema "B" en funcionamiento de la productividad minera y la tecnología adecuada a la realidad.

Nov 1, 1972

By D. K. Denton, M. J. Friedel, D. F. Scott, T. J. Williams

Spokane Research Center personnel have been investigating the use of seismic tomography to monitor the behavior of a rock mass, detect hazardous ground conditions, and assess the mechanical integrity of a rock mass affected by mining. Seismic tomography can be a valuable tool for determining relative stress in deep ( > 1220 m) underground pillars. If high-stress areas are detected, they can be destressed prior to development or avoided. High-stress areas can be monitored with successive seismic surveys to determine if stress decreases to a level where development can be initiated safely. There are several benefits to using seismic tomography to identify high stress in deep underground pillars. The technique is reliable, cost-effective, efficient, and non-invasive. Also, investigators can monitor large rock masses, as well as monitor pillars during the mining cycle. By identifying areas of high stress, engineers will be able to assure that miners are working in a safer environment.

Feb 24, 1997

By B. W. Gandrud, G. D. Coe

"INTRODUCTION The Southern Experiment Station of the U.S. Bureau of Mines, cooperating with the University of Alabama and Alabama coal producers, has made a series of investigations of the washability of coal from commercially important bens of Alabama. The results of 13 investigations pertaining to the Mary Lee, Clark, Black Creek, Jefferson, Pratt, Corona, Carter Brookwood, Blue Creek, Thompson, and Woodstock beds have been published. 4/ This report, the fourteenth of the series, deals with run-of-mine coal from the Henry Ellen bed at the Acmar No. 5 mine of the Alabama Fuel & Iron Co.The Acmar mine is 1/2 mile west of Acmar, Saint Clair County, in the northern part of the Cahaba field. Present production at the mine is about 800 tons per day, all of which, accept the lump coal, is treated in jigs. The washability data were obtained by means of screen-sizing and float-and-sink tests. There are included, also, tests showing the extent of liberation of impurities by recrushing the coarser sizes of coal from the top bench and tests showing the flakiness in selected sizes.SAMPLING AT THE MINEThe Henry Ellen bed at Acmar consists of two benches separated by a shale parting. At the point of sampling the top bench was 6 feet 3 inches thick and contained a 1-inch and a 1 1/2-inch band of bone. The bottom bench was 5 feet thick and was separated from the top bench by 20 inches of shale. In taking the samples for the washability study the working face was squared up, and a representative 2-ton section was out from each bench. The shale parting was discarded, according to usual mining practice."

Nov 1, 1936