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By R. P. Proulx

The Meikle Mine is a high grade, underground goldmine utilizing primary-secondary longhole open stoping with delayed backfill to produce 2700 tpd(3000 stpd) of ore. Hot and reactive ground conditions were encountered early on in the mine life. Ground temperatures up to 166°C (330°F) were measured. In the early stages of mining, the mine experienced premature detonations using different explosive products. The learning curve to safely mine this high-grade gold deposit in hot and severely reactive ground was indeed very steep. Currently, the Meikle Mine uses a special buffered bulk emulsion in all blasts to address hot and reactive ground concerns. In addition, exacting procedures are also followed to ensure safe work with explosives. The combination of new explosives technology and strict loading procedures permits high mine productivity with the highest degree of safety.

Jan 1, 2000

By L. A. Bakhvalov

According to the practice of mining management in the system of industrial complexes, the Kazakhstan gold mines are part of the mine processing industrial concerns providing ore-mining and ore-dressing. The cycle technology of winning operations used at the mining of vein deposits in the mines of the industrial concern is mainly provided by the systems of scrapping, scipping and electric locomotion. At present the information and computer system, elaborated on the basis of the Maikain underground mine is intended for creation of the system of automatic operation for the industrial complex mines. The information and computer system includes: - parametres characterising the accepted technology of works; - the main parametres characterising the technical devices of operation and control ; - information about the material, technical and personnel resources available at the mine; - mining and geological conditions of the deposit; - the facilities of the subsidiary units, of the mine; - the direct parametres and technico-economical indices in which the mine efficacy and activity is estimated. The suggested structure of the automatic operation system can be sensibly realized with the application of the microprocessor on the first level, the personal computer IBM PC/XT or PC/AT on the second level. For the complete realization of the project each mine will need 4-5 computers (as PC/XT), one IBM PC/AT and each mine complex - one super IBM for creation of the distributed information bank and its including in the integral world communication system.

Jan 1, 1992

By Jason Morrison

The Norwegian Lake Tap Method was successfully used to tap into the side of Lake Dorothy 36.5 m (120') below the lake surface. The lake tap allows water to flowinto an access tunnel from the lake lowering the water elevation below its natural out-fall. When the lake reaches a predetermined elevation below the outfall, a 1.5 m (60?) valve in the tunnel will be shut and discharge from Lake Dorothy will stop temporarily allowing construction of a dam located 2.9 km (1.8 miles) downstream at Bart Lake. The lake tap and tunnel were one phase of the $64 million Lake Dorothy Hydroelectric Project, owned and operated by Alaska Electric Light & Power Company (AEL&P), a private utility located in Juneau, AK. The Lake Dorothy portal site and tunnel are located approximately 25.7 km (16 miles) southeast of Juneau, AK, in the remote Tongass National Forest at an elevation of 701 m (2,300') above sea level in the mountains above the Taku Inlet. Thirty degree snow covered mountainsides and limited access by helicopter were just two of the many factors which challenged this unique project. The lake tap and tunnel development consisted of 250 m (820') of horizontal tun-nel, averaging 3.6 m x 3.6 m (12' × 12'), excavated using conventional drill and blast methods in highly competent Granodiorite and Tonalite rock, placement of one 3.9 m (13') long concrete plug, or bulkhead, located at the tunnel midpoint, and one 3 m (10') diameter lake tap into the side of Lake Dorothy. This paper will provide an analysis of the logistical and engineering challenges involved in the development of one of only a handful of lake taps in North America. AEL&P and contractor J. S. Redpath Corporation worked together to complete this critical project phase safely and on schedule, in a location accessible only by helicopter and plagued by constantly changing, harsh weather conditions. A strict schedule had to be maintained to ensure the timely operation of the downstream dam and power plant.

By G. Wahl, H. Danilkewich, T. Mann

Developers of advanced mining projects face the challenge of how to craft a “Request for Proposal for a Feasibility Study” that will result in bids that are comparable and will lead to a successful execution of the study. Mining engineering consulting firms are challenged by “Request for Proposals” that may consist of a limited description of the Scope of Services and other items, which could present difficulties in the subsequent financing and/or development of the project. Changes in international disclosure requirements have also changed the landscape on how resources and reserves are reported by introducing new disclosure requirements and concepts such as qualified persons. This paper lays out a strategy for preparing a Feasibility Study “Request for Proposal” based on the experiences of a mining engineering consulting firm working on a diversity of projects around the world, and in light of the recent changes in international reporting standards for reserves.

Jan 1, 2002

By Joseph A. Dos Santos

The largest TBM (Tunnel Boring Machine) tunnels are typically along modest slopes, but not always. Occasionally high slope angles are required beyond the capabilities of conventional open trough trailing conveyors. A 2019 project required a large TBM to ascend to an incline angle of 25°. A Sandwich Belt high angle conveyor could easily solve the high angle conveying problem but such a system must include all of the features of the conventional trailing conveyor, particularly the ability to extend with the TBM advance. The writer responded to the challenge and developed a TBM trailing Sandwich Belt high angle conveyor with all of the needed features. The invention (U.S.A. patents awarded October, 2021 and November, 2022) however goes beyond the 2019 project requirements and extends to any high angle incline. This writing first presents the broad Sandwich Belt high angle conveyor development, then its use in various construction and tunneling projects prior to this TBM Sandwich Belt trailing conveyor invention. Finally we present the new TBM Trailing Sandwich Belt high angle conveyor with all of its features and implications.

Jun 13, 2023

By Leroy O. Gieseke, John B. Begley

If the particles produced and transported in your plant are as chunky as rough crushed coal or as fine as cement, there are probably several conveying and elevating systems suitable for your operation. The problem is deciding which is most suitable in terms of space, energy cost, allowable product degradation, productivity, and angle of movement. Each conveying and elevating method should be fit to the products it can handle successfully, to desirable economics, and to suitability for the overall operating scheme. Matching along these lines will result in selection guides that should be useful for many years, although design evolution is expected for the materials handling equipment involved. There are several common bulk material handling devices for moving solids: belt conveyors, screw conveyors, bucket elevators, chain conveyors, and en-masse conveyors/ elevators. En-masse conveyor/elevator equipment is commonly compared and contrasted with the other devices. These comparisons often involve en-masse versus all others. En-masse has developed into a versatile technique because the machines can move materials horizontally, vertically, or in closed circuit. Such machines unload, elevate, store, reclaim, and distribute materials-all without ancillary equipment except for chutes and gates. Bulk material can be carried, as with a belt conveyor or bucket elevator; pushed, as with a flight or screw conveyor; bumped, as with a vibrating conveyor; blown, as with a pneumatic conveyor; fluidized, as with a dense phase pneumatic conveyor; or by applying internal forces to it to induce "en-masse" flow. Conveying en-masse is analogous to the flow of a fluid in an open channel, and elevating en-masse is analogous to the flow of fluid in a pipe. In the case of a fluid, flow is caused by a differential in pressure. With en-masse movement, flow results from resistance to shear induced by the movement of chain and flights.

Jan 12, 1980

By S. Holtermann

Through the process of Riverbank Filtration (RBF), the Louisville Water Company plans to obtain a higher quality source of water for their B.E. Payne Water Treatment Plant (WTP) by means of four collector wells located in the alluvial aquifer along the bank of the Ohio River. The collector wells are connected to a 2,850 L/s (65 mgd) pumping station by a 2,362 m (7,750 ft) long, 3 m (10 ft) finished diameter tunnel located in limestone and shale bedrock, which is approximately 45 m (150 ft) below the surface. High tunnel boring machine (TBM) production rates were achieved in this moderately weak bedrock; most of the tunnel only required support in the crown. An unanticipated water-bearing fault and unanticipated ground behavior proved challenging and required quick thinking to minimize impacts to construction. Tunneling conditions are discussed in detail, together with the methods used for overcoming the groundwater and ground behavior challenges. The tunnel is expected to be completed in April 2009.

By Carl Pinches

Underground or surface mining is only the first stage in the ore mining process. Once the ore is mined, it is transported to the surface for further processing. Generally, this is done to extract the particular metal or other component of the ore that has commercial value in its purified form. In its raw state, there are typically between 4 and 7 g/t (0.12 and 0.2 oz/st) of valuable material from rock mined. Once on the surface, the ore is crushed and milled in order to obtain smaller rock particles and to expose the minerals that contain the desired metal or component. Mixing the milled ore with water, a process known as ?froth flotation,? can be employed. This technique consists of a series of tanks, or ?cells? through which the process liquid flows. To obtain the maximum recovery, the milling and flotation process will often be repeated a second time. An increase between 100 and 1,000 g/t (2.9 and 29 oz/st) of rock following this stage of the process is typical. Efficient recovery is key to maintaining a profitable mining operation. The measurement and control of the froth flotation process is vital.

Jan 1, 2010

By Clifford B. Farris

Introduction Shale Mining Problems The mining problems an oil shale operator will face are largely determined by the process. Candidate oil recovery processes are surface (above ground processing of mined oil shale), modified in situ (underground with some shale removed), and true in situ (completely underground with no shale removed). The shale removed for modified in situ (MIS) is generally processed by surface techniques. The mining problems are different for each category. Fig. 1 depicts the diversity of western shale deposits. Mining for surface operations will employ underground mining techniques in common use but the scale will be larger. A typical oil shale operation is expected to require 75,000 to 250,000 st (68 000 to 226 800 tons) a stream day of crushed oil shale. This is above the upper limit of current mining operations. Major problems include: (1) lack of good engineering design properties for oil shale, especially when interbedded with saline minerals at depths below 1,000 ft (305 m); (2) presence of water, hydrogen sulfide, and methane in some areas; (3) necessity for mine disposal of as much retorted oil shale waste as possible; and (4) control of environmental impacts of mining. Portions of the oil shale deposits in Colorado, Wyoming, and Utah and significant portions of the Devonian shales in the eastern U.S. are adapted to surface mining. No major technological problems are apparent outside overburden thicknesses up to 1,000 ft in the West. However, numerous political and environmental difficulties have arisen. One major oil shale developer cancelled a planned surface mining operation and currently is pursuing a modified in-situ plan. The eastern shales are closer to the surface than the western, but suffer from many of the same environmental and political problems. Modified in-situ operations face much more severe mining problems than surface efforts. Because the mined stope (called an in-situ "retort" by processors) acts as a retorting process vessel subject to gas flow, combustion, and temperatures between 1,500° and 2,000°F, mining is under highly restrictive limitations. This processing method involves removing between 20 and 40% of the shale deposit and then blasting the roof and walls into the mined space, where the oil is recovered by retorting. Major problems are: (1) swell factor severely limited; (2) need for consistent size distribution of blasted shale; (3) even filling of stope (in-situ retort) by blasted shale with consistent permeability throughout; (4) scaleup of blasting techniques, after optimization; (5) protection of retort pillars and roof during and after retorting; (6) prevention of groundwater percolation; (7)use of ANFO explosive in wet holes; (8) disposing of surface-retorted shale waste in stope; and (9) restoration of site. True in-situ operations are less well developed than surface or MIS processes. No actual mining is done, as the true in-situ processes generate permeability in the highly

Jan 9, 1980

By Clifford B. Farris

Introduction Shale Mining Problems The mining problems an oil shale operator will face are largely determined by the process. Candidate oil recovery processes are surface (above ground processing of mined oil shale), modified in situ (underground with some shale removed), and true in situ (completely underground with no shale removed). The shale removed for modified in situ (MIS) is generally processed by surface techniques. The mining problems are different for each category. Fig. 1 depicts the diversity of western shale deposits. Mining for surface operations will employ underground mining techniques in common use but the scale will be larger. A typical oil shale operation is expected to require 75,000 to 250,000 st (68 000 to 226 800 tons) a stream day of crushed oil shale. This is above the upper limit of current mining operations. Major problems in¬clude: (1) lack of good engineering design properties for oil shale, especially when interbedded with saline minerals at depths below 1,000 ft (305 m); (2) presence of water, hydrogen sulfide, and methane in some areas; (3) necessity for mine disposal of as much retorted oil shale waste as possible; and (4) control of en¬vironmental impacts of mining. Portions of the oil shale deposits in Colorado, Wyoming, and Utah and significant portions of the Devonian shales in the eastern U.S. are adapted to surface mining. No major technological problems are apparent outside overburden thicknesses up to 1,000 ft in the West. However, numerous political and environmental dif¬ficulties have arisen. One major oil shale developer cancelled a planned surface mining operation and currently is pursuing a modified in-situ plan. The eastern shales are closer to the surface than the western, but suffer from many of the same environmental and political problems. Modified in-situ operations face much more severe mining problems than surface efforts. Because the mined stope (called an in-situ "retort" by processors) acts as a retorting process vessel subject to gas flow, combustion, and temperatures between 1,500° and 2,000°F, mining is under highly restrictive limitations. This processing method involves removing between 20 and 40% of the shale deposit and then blasting the roof and walls into the mined space, where the oil is recovered by retorting. Major problems are: (1) swell factor severely limited; (2) need for consistent size distribution of blasted shale; (3) even filling of stope (in-situ retort) by blasted shale with consistent permeability throughout; (4) scaleup of blasting techniques, after optimization; (5) protection of retort pillars and roof during and after retorting; (6) prevention of groundwater percolation; (7)use of ANFO explosive in wet holes; (8) disposing of surface-retorted shale waste in stope; and (9) restoration of site. True in-situ operations are less well developed than surface or MIS processes. No actual mining is done, as the true in-situ processes generate permeability in the highly

Jan 1, 1980

By Christa Overby

As part of the City of Portland, Oregon?s East Side Combined Sewer Overflow Tunnel Project, nine separate 2,130 mm (84-inch) diameter reinforced concrete pipe microtunnel drives totaling approximately 2,380 m (7,808 ft) are being constructed to divert flows from several of the existing outfalls to the main tunnel. The drives were constructed in challenging ground conditions that include soft soils under the ground-water table, large amounts of wood and metal debris, and close proximity to sensitive structures. While all of the drives will be addressed, the focus of the paper will be on the 931 m (3,055 ft) continuous drive connecting Outfall 46, currently the longest microtunnel driven in North America.

By S. Rupprecht

"This article addresses the prevalence of poor public reporting practices of coal exploration results, coal resources and coal reserves in southern Africa. Currently, the reporting of coal tonnage without supporting coal qualities or saleable tonnes and quality is a poor reporting practice that occurs far too often. Not all coal is equal — therefore it is extremely important that investors or potential investors are provided with the full details of both run-of-mine (ROM) and saleable coal tonnage, their associated qualities and other material and relevant information.Competent or qualified persons should note that publicly reported information should be sufficient to enable an informed reader to make a reasonable and balanced assessment of the significance of the information provided. “Companies are encouraged to provide information in their public reports, which is as comprehensive as possible (CRIRSCO, 2013).” However, too often this isn’t the case, and material matters are either not reported or inadequately disclosed.According to the South African National Standard (SANS) 10320:2014 draft document, “tonnage and coal quality that will be available for sale, either in the raw ROM state (raw saleable) at a specified moisture content, or after beneficiation of the ROM coal by processing operations to produce materials at specified qualities, size ranges and moisture contents. The assessments must demonstrate that at the time of reporting, the marketing of the products is reasonably justified. The basis of the predicted practical product yield to achieve the saleable coal reserve must be stated. The moisture basis of reporting shall be stated.” An example as to why coal qualities are so important to the public, the requirements of South Africa’s electric public utility (Eskom) power stations are detailed in the followint paragraphs. The Kendal power station, commissioned in 1988, operates at a calorific value (CV) range of 19 to 20 MJ/ kg, an ash content between 29 and 34 percent and volatiles between 20 to 21 percent. Other power stations, such as Kriel or Hendrina, may require different qualities, such as a CV range of 22 to 23 MJ/kg, an ash content between 20 and 28 percent and volatiles between 22 to 23 percent. Thus, in terms of domestic saleable coal, it is not just about reporting the coal qualities but also informing the investor as to which power station the coal is intended to be sold as “boilers are designed to burn particular qualities of coal” and “it is not always possible to transfer coal between stations because of different quality requirements at each station (Chetty, 2010).” Sulfur content is another important quality with the ideal coal content having a quality of less than 1 percent sulfur."

Jul 1, 2019

By Daryl E. Radcliffe, Raymond M. Stateham

The Bureau of Mines, under a Cooperative Agreement with the Bear Coal Company, Somerset, Colorado, conducted a large scale evaluation of the effect of time lapse on roof stability. Time lapse in this study is the interval between exposure and permanent support of the mine roof. The study indicates that time lapse is not a critical factor in roof stability provided permanent support is installed before catastrophic failure begins. Concurrently with the time lapse study, investigations were made of stress distribution around resin-grouted bolts, the regional stress field, and anomalous geologic conditions. The behavior of the resin-grouted bolts, at least in the Bear mine, appears to fit the Coulomb-Navier Theory. Geologic conditions are primary factors in trends of roof stability that extend across the mine.

Jan 1, 1982

By David Van Horsen

Operation and maintenance of California?s water tunnels is an important factor and vital link in California?s infrastructure. These tunnels are owned and operated by a variety of large and small private and public water and power utility companies, municipal agencies, and irrigation districts. Visionary pioneers such as Michael O?Shaughnessy (San Francisco Hetch Hetchy Water Supply System), William Mulholland (Los Angeles Department of Water and Power and Metropolitan Water District of Southern California?s Colorado River Aqueduct), and John Eastwood (Southern California Edison Big Creek Hydroelectric Project) built large and small water supply, irrigation and hydroelectric tunnels, which have supplied environmentally friendly-water supply, renewable electricity, and uninterrupted service to a burgeoning population and economy. This paper introduces these pioneers and describes several case histories and lessons learned during condition assessment and rehabilitation of tunnels providing enlightenment of California?s vital water projects.

Jan 1, 2008

Outokumpu Technology’s HSC Chemistry process calculation software enables the user to simulate an entire chemical or physical process. The HSC Chemistry 6.0 contains 21 calculation modules and 11 databases for reaction, equilibrium, heat balance, heat transfer, petrological and simulation applications. Most of the calculation modules automatically utilize the same extensive thermochemical database which contains enthalpy (H), entropy (S) and heat capacity (C) data. This database has been expanded to include more than 20,000 species.

Jan 1, 2007

By D. E. Pollock

Recent NIOSH published information has shown an increase of rapidly progressive coal workers? pneumoconiosis (CWP) in the southern Appalachian coal region (SAR) of the U.S., despite the fact that compliance data indicates that most coal miners have been exposed to coal mine dust concentrations below the statutory limit of 2.0 mg/m³. While the exact cause of these elevated CWP levels in the SAR has not been established, several factors may be contributing to the increase in occupational lung disease among coal miners. The mining of high rank coal is known to lead to higher CWP rates, and this type of coal is mined in a portion of this region. Also, a high percentage of the mines in the region are on reduced dust standards because of the high silica content of the airborne dust resulting in miners possibly being exposed to excessive amounts of respirable silica dust. Exposure to excessive amounts of respirable silica dust can lead to silicosis, a disabling and potentially fatal lung disease. NIOSH's Respiratory Hazards Control Branch has been investigating the possible causes that would account for the observed higher trends in disease progression through literature review, data analysis, and in-mine surveying. The investigation to date has revealed that underground mines are faced with cutting large amounts of rock in order to maintain haulage clearances. Cutting rock not only increases the potential for silica exposure, it increases the requirement for machine maintenance which was a concern observed during dust surveys conducted by NIOSH. Over half of the mines operating in the SAR are on reduced standards due to high silica content. Adequate face ventilation of the continuous miner and roof bolter and limited down-wind operations from the miner are also issues of concern and items which require the constant attention of miners operating in these conditions. Disclaimer: Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health.

Jan 1, 2009

Sequential and evolutionary changes through time are recognizable in many, perhaps most major families of ore deposits and their geological environments. These changes are additional useful indicators of the evolutionary history of the earth and its tectonic processes. They are important in mineral exploration because they involve consideration of time as a fourth dimension, thereby indicating the most favorable ages, rather than types of rock for investigation. Many of the changes are analogous to those recognized in faunal evolution. Some primitive, unspecialized types of ore deposits occur nearly unchanged through rocks of widely differing age. Others diversify into several, more specialized variants, whereas still others become extinct. The place of these is taken by new, younger types, some of which undergo sudden proliferations and later diversifications of their own. In Archean greenstone belts irrlportant iron, nickel, gold, and base metal deposits occur co-regionally, but in different stratigraphic positions in the same, thick volcano-sedimentary successions. Here their close temporal and spatial associations suggest common genetic exhalative hydrothermal processes. The massive base metal sulfide family of ore deposits provides an excellent example of evolutionary changes, exhibiting distinct variations through both time and space. Deposits belonging to this family span the entire range of time, occurring in rocks of ancient Archean to Recent age, and specific types within the family also span the entire range of spatial environments from ensimatic to ensialic. Moreover there are possible evolutionary metallogenic links between certain types of massive base metal sulfide deposits and other important base metal ores, noteably Mississippi Valley-type and porphyry copper deposits.

Jan 1, 2013

By Juan L. Yarmuch, Gonzalo Sepulveda

This article presents a novel approach to address the mining width-constrained open pit mine production scheduling problem in the context of medium-term planning. A mathematical formulation is proposed to incorporate mining width constraints into the production scheduling process, aiming to maximize the NPV of the schedule while ensuring enough room for the operation of mining equipment. To tackle the computational challenges posed by large-scale instances of the problem, we propose a method based on variable fixing and horizontal precedence generation. In this study, we apply the developed model to real-world scenarios from Radomiro Tomic short-term mine planning problems such as optimizing the timing of major truck maintenance and the impact of external factors, like the delay in the production of the Chuquicamata underground project. Remarkable improvements are observed with the mining width-constrained model. Specifically, the mining width satisfiability is enhanced from 2 to 60% compared to the traditional open pit mine production scheduling model, underscoring the significance of incorporating these constraints. The proposed method showed good results reaching optimality gaps within 5%.

Mar 28, 2024

By G. France

The Blair Athol Coal Mine (BAC) is a large open cut operation in the Bowen Basin of Queensland, Australia. Current mine capacity is about 11 million tonnes per annum(Mtpa) of export coal. On-line analysis at BAC consists of two Coalscan 9500s installed directly on the output of the crusher plant and immediately before the product stockpiles, while a third Coalscan 9500 is installed on the transfer conveyor feeding the train loading bin. The two product Coalscans have a dual purpose. The first is to provide real time coal quality data directly back to the mining operations. The second is that of modeling the product stockpile with accurate on-line information. This modeling enables both production and coal quality personnel to accurately examine the coal quality of each stockpile with a degree of resolution which previously had never been achieved.

Jan 1, 1999

By Steve Kral

In 2002, many in the mining industry — companies, academia and government — realized that the industry would soon be facing a serious shortfall in salaried and hourly employees. Depending on whose numbers are to be believed, 20 percent to 50 percent of current mining professionals are expected to retire within five to 10 years. And there are not enough students currently enrolled in mineral-related programs to the fill the need. Part of the impending shortage in professionals was brought on by the industry’s negative image, which discouraged students from enrolling in mining engineering programs. Another part was that the industry was in the doldrums and was seen by the public as a dying industry.

Jan 1, 2006