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By R. K. Singhal, H. Sahay

Introduction In terms of the world's recoverable coal reserves, Canada ranks 10th, providing 0.6% of the world's total. The US is first with 27.8% and the Soviet Union follows with 24.1%. Figure 1 shows the principal coal mines in Canada. Several provinces contain substantial coal deposits, but the largest deposits are found in the western provinces of Alberta, British Columbia, and Saskatchewan. Conservatively, 90% of the lignitic, 80% of high volatile bituminous, and nearly 100% of subbituminous, and low and medium volatile bituminous coals are located in these three provinces. During the past decade, Canadian coal production of all types increased from 18.8 Mt (2 million st) in 1972, to 25 Mt (28 million st) in 1975, to 61 Mt (66 million st) in 1984. About 38 Mt (43 million st) of this output was classified at thermal and 23 Mt (25 million st) as coking and metallurgical coal (Table 1). The three western provinces currently produce 57 Mt (62 million st) of coal - 95% of Canada's total. The remaining 3.6 Mt (4 million st) (5%) is produced in Nova Scotia and New Brunswick on the east coast. The majority of western coal (98%) is produced by surface mining methods. On the east coast, though, mining is predominantly underground and only 15% is produced on the surface. In 1985, Canada exported close to 28 Mt (30 million st) of metallurgical coal and thermal coal. During the same period, 15 Mt (16 million st) of coal were imported, mostly from western US for use in Ontario and Quebec. Almost 60% of the imported coal was used for thermal applications. The remaining 40% was metallurgical coal for the steel industry. It is generally cheaper to import coal into central and eastern Canada from the eastern US to augment local supplies rather than from western Canada. This is mainly because of high transportation costs. Mining methods The suitability of mining methods in a particular area depends largely on the geological setting. Geology, therefore, simplifies or adds complexities to mining operations, directly affecting the economics. It also influences the flexibility required from the min-

Jan 9, 1986

By J. D. Lowell, L. Quevedo

I will talk today about a porphyry copper exploration program now underway in the Amazon jungle in the southeastern part of Ecuador near the border with Peru. The project is unusual for two reasons: first the deposits are of Jurassic age, 153 m.y.o., which is unusually old for porphyry copper deposits and they may be the most significant pre-Tertiary age porphyry deposits known. Second, the district was found only six years ago which makes this the most recent discovery of a totally new porphyry copper district. The new porphyry district, known as the Zamora River Copper Belt, or the Corriente Copper Belt, is a north trending area 50 km long by 10-15 km wide, which is nearly aligned with the axis of the Jurassic age Zamora batholith and with the course of the Zamora river. Gencor in 1994 initiated a regional grassroots gold exploration program based on reconnaissance geologic mapping and geochem sampling which did not find a gold mine, but which identified the San Carlos porphyry copper system in April, 1995. In a later reorganization between Gencore and Billiton the Ecuador project was transferred to Billiton and between the Gencore work and Billiton’s a total of 10 porphyry copper systems were found over the next four years. In the period of 1997 - 1999 Billiton drilled a total of 11,000 meters of wide spaced core holes in the San Carlos, Panantza and Kutukus prospects. In October 1999 Billiton concluded a farm-out, joint venture agreement with Corriente Resources and Lowell Mineral Exploration for additional exploration of the Zamora property. This is funded by Corriente and managed by Lowell Mineral Exploration and a total of 28,000 m of core drilling was completed through August 2001. An immediate result of the Corriente Lowell project was the discovery of potentially commercial ore reserves in two new deposits at Mirador and Warintza. Additional closer spaced drilling was done in the Panantza deposit and additional drilling is planned at San Carlos, in targets related to Warintza, and elsewhere.

Jan 1, 2002

By M. S. Klima, A. P. Pinkerton

Solid-bowl (decanter) centrifuges are used extensively to dewater slurries in a wide range of industries. However, the application of decanters as classification devices is not as common. In this study, the performance of a continuous, pilot-scale, solid-bowl centrifuge was evaluated when classifying an ultrafine coal slurry containing nearly 60% material less than 10µm. The current study examined the effects of operating conditions on centrifuge performance. The test conditions included centrifuge bowl and scroll speeds, volumetric feed rates, solids concentration, and pond depth. Centrifuge performance was evaluated using partition curves, along with product yields and solids concentrations.

Jan 1, 2000

By S. Noll

Ventilation is an essential part of any underground mining operation. It provides fresh air for workers and machinery, keeps up an adequate mine climate and dilutes and dissipates noxious gases. Possible changes in the economic environment for mining in the future, e.g. increasing energy costs, will necessitate optimization of distribution of airflow within most mines. This paper discusses the scientific set-up for measurements as well as the behavior and influence of parameters of ventilation according to airflow distribution under consideration of technically possible set-ups of mine fans. This study was done in an underground mine with a flat seam room and pillar mining method.

Feb 27, 2013

By Jim Nickerson, James McCleish, Tom Abkemeier, Nicholas Willig

The purpose of this project is to convey sanitary sewage from an existing pump station to a new waste water treatment plant. This paper will discuss the design and construction aspects of the project. The scope includes construction of three main shafts ranging from 34 to 100 feet in diameter at depths of 200 to 230 feet and 21,000feet of tunnel. Shaft construction consisted of slurry wall excavations keyed into claystone and limestone at depths ranging from 114 to 130 feet, followed by rock excavation utilizing drill and blast methods. The tunnel is being excavated in the Warsaw and Salem shale and limestone formations utilizing a 12'-6" diameter Wirth hard rock TBM.

Jan 1, 2005

A glance at the accompanying table reveals that for the first time in many years the industrial minerals field did not post significant gains in production. Gypsum, cement, sand and gravel, and crushed stone production-which are very sensitive to construction industry performance-barely managed to stay even, or in fact, declined slightly. Even barite production, in spite of increased oil and gas drilling, was off 5% in 1979 from 1978. Domestic fluorspar production continued to decline while imports, primarily from Mexico, South Africa, and Spain, rose 11%. Worldwide production of iodine (which is used primarily as a catalyst, animal feed additive, and in ink and colorants, stabilizers, pharmaceuticals, photographic film, and disinfectants) grew about 9% on a worldwide basis-from 10.75 Tg to 11.16 Tg. This does not include US production. The two US producers increased demand as apparent domestic production increased about 5%. Increasing energy costs and the transportation situation have had a prohibitive effect on the industrial minerals field. The critical shortage of railroad cars, according to consultant Neil Johnson, is due to several factors: • High capital investment rind interest rates needed to build new equipment, • Accidents, obsolescence, and failure to repair equipment reduced car availability, •Reduction in some train schedules due to fuel economy, and •Increased turnaround time as a result of new safety regulations. Railroad rates have increased an average of 7% per year for the past 10 years. Last year's increases were about 11.1% due to fuel costs and surcharges. Truck shipments have increased their penetration in certain areas of the southeast because of the shortage of box cars and the producers' demand for quick shipment. Some producers report a 15-20% increase in truck use. In the feldspar-mica area, which formerly made most shipments by rail, trucks are now used for about half the shipments. Marketing prices, as expected, increased due to higher costs for energy, power, labor, and supplies used in production. Estimated average price increases were about 10% which, in many cases, did not cover increased production costs. These factors-rising energy costs and the critical transportation situation-resulted in an unsatisfactory year for industrial minerals. Stanley J. Lefond Cnntrihuting Editor

Jan 5, 1980

By S. Frimpong

Cable shovels are used for primary excavation in in-situ and/or pre-fragmented formations in surface mining operations. Poorly fragmented hard rock formations and random occurrence of hard boulders in soft formations cause extreme variability of material diggability, resulting in varying shovel stress loading. The stress loading of a shovel’s front-end assembly could result in fatigue failure. Conventional design process, which uses physical shovel simulation studies, is very costly and time consuming for achieving statistically significant results. In this paper, rigid and flexible multi-body dynamic theories are used to develop component stress loading and deformation models of the cable shovel, and solved in the ADAMS/NASTRAN/FLEX environments. Detailed simulation experiments are carried out to examine the performance, reliability, durability and efficiency of the P&H 4100A under varying in-situ formation conditions. The results show areas of high stress fields with a maximum stress of 313.31 MPa at node 441 within the hoist rope. The reliability of the results is confirmed by comparing existing test data. The study is significant because it provides a solid foundation for further study of failure life analysis of the cable shovel components.

Jan 1, 2007

By L. K. Marshall

Last month's engineering fundamentals article discussed some general considerations of underground mine ventilation. This month's article takes a look at auxiliary ventilation-brattice, fans, and ducting-in underground mines. The need for good, efficient auxiliary ventilation increases as mines get deeper and move farther from ventilation shafts. New mining methods and equipment resulted in faster work area advances, liberating more dust, gas, and heat. As a result, worker health and safety requirements in the face area have become more stringent. For all these reasons the safety and efficiency of any underground mine depends heavily on its auxiliary ventilation. The purpose of such ventilation is to supply sufficient quantities of clean air to the face of the drift and to maintain air quality within desired limits until expelled from the mine.

Jan 2, 1982

By A. J. Romeo

The Old Hickory heavy mineral ore body, which lies within the Fall Zone of south central Virginia, has been mined since 1997. There are many differences in this deposit when compared to humate-laden mineral sands mines of southern Georgia and Florida. These differences include an abundance of kaolin-rich clayey sands, highly concentrated and iron-colored heavy mineral sand units, and a base of mineralization that is undulating. For these reasons, the selective approach of dry mining with track excavators is ideal. Grade control in this deposit uses traditional panning techniques and requires an intimate working knowledge of near-by drilling data. Mine geologists train equipment operators to recognize the base of mineralization by such characteristics as a stark color change, significant changes in grain size, and/or considerable, recognizable shifts in the concentration of heavy minerals. The regular pattern of mine site drilling does not always prepare the geologist and digging crews for occurrences of near-vertical contacts between the saprolite basement and the ore sands. These deformed areas, combined with undulating and pinching ore zones, require close monitoring and flexibility by the geologist and the mine operators.

Jan 1, 2005

By C. C. Clark, D. J. Benton, J. B. Seymour, L. A. Martin

"The U.S. National Institute for Occupational Safety and Health (NIOSH) is conducting research on jackleg use and related accidents in underground metal mines. This paper provides an analysis and overview of jackleg drill usage, accidents, operational characteristics and alternatives, based on information from injury reports, legacy research, stakeholder input and published literature. The results indicate that jackleg drills are involved in more groundfall accidents in underground metal mines than any other drill, and jackleg-drill-related injuries are most prevalent at the face in the course of installing initial ground support. Practical mechanized alternatives to jackleg drills for drilling and bolting under incomplete support in narrow underground openings have not yet been realized. Small, versatile mechanized bolting equipment needs to be developed to address jackleg-drill-related accidents and improve safety at mines where jackleg drills are being used. IntroductionJackleg drill is a generic name for a handheld, rotary, percussion rock drill equipped with an attached reaction leg to provide stability and thrust (Fig. 1). All of the drill and leg controls are located near the operator’s handle at the rear of the head portion of the drill. Jackleg drills are classified according to the bore size of their pneumatic pistons, which normally range from 6.03 to 8.26 cm (2.375 to 3.25 in.) (Kurt, 1982; Clark, 2012). Jackleg drills typically weigh 46.7 kg (103 lb), but the weight can approach 54.4 kg (120 lb) after being fitted for operation with drill steel and air and water hoses (McKibbin and Clark, 2001). In underground mines, jackleg drills are commonly used to drill 3.8-cm (1.5-in.) diameter holes up to 1.83 m (6 ft) deep in rock."

Aug 1, 2016

By J. W. Wilson, P. C. Graham

SUMMARY The Witwatersrand quartzites in which South African gold mining operations are moat exclusively conducted, are notoriously difficult and costly to drill. Despite this situation, however, with the high cost of developing new mines and extending existing mines, together with the rising cost of labour and mining problems resulting from the ever-increasing depths of workings, the demand for raise-boring in these formations is increasing rapidly. Not only is the demand for raises and shafts increasing, but also the length and size of these excavations. Raise-boring studies carried out in South African gold mines have indicated that increased penetration rates and possibly reduced costs could be obtained if higher thrusts were available at the reaming head. Until fairly recently there has been no raise-boring machine suitable for underground use that possessed the thrust and torque characteristics necessary to achieve high penetration rates in hard abrasive quartzite formations and the cutters available were not really developed for high loading. In response to these requirements a raise-borer, the Robbins 83R was designed and built in Seattle, U.S.A. for the Anglo American Corporation. This machine is operating in South African gold mines and is currently being used at a depth of 12 000 ft below surface in one of the. Group's mines. The initial raises bored have substantiated that increased penetration is attainable at high thrust and it is now apparent that the machine is sufficiently versatile to drill raises of up to 12 ft in diameter in quartzite formation over a length of 2 000 ft.

Jan 1, 1974

By K. R. Gardner, P. B. Altringer, R. H. Lien, B. E. Dinsdale

The Bureau of Mines, U.S. Department of the Interior, is investigating chemical and biological decontamination of complex wastewaters such as tailings pond water containing 280 ppm CN and 5 ppm Se as well as significant concentrations of arsenic, copper, iron, silver, and zinc. The most effective chemical procedure involves cyanide oxidation using hydrogen peroxide or sodium hypochlorite followed by selenium reduction using ferrous hydroxide. The effluent contains ?1 ppm CN and 20 ppb Se; concentrations of other - major contaminants meet National Drinking Water Standards. Preliminary research indicates that biological cyanide oxidation is possible even in highly alkaline solutions (pH 10.5) containing high cyanide concentrations; indigenous bacteria destroyed 85% of the cyanide. Exploratory research shows that other bacteria removed up to 79% of the selenium from chemically oxidized, low- cyanide water. These promising results may lead to a final processing scheme that involves a combination of chemical and biological techniques.

Jan 1, 1990

In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By J. D. Miller, C. L. Lin

Filtration of fine particles involves filter cake formation and removal of surface moisture by drawing air through the porous structure. Accurate assessment of the transport properties of porous media (in this case, filter cake) is of major importance in the development of improved filtration processes. Implications from these studies are important in the design and operation of filtration equipment in order to enhance the efficiency of this important solid-liquid separation process. The microstructure and connectivity of pore space are important features necessary to describe detailed fluid flow phenomena in filter cake during fine particle filtration. In this regard, 3D characterization of pore structure is essential. The pore structure has to be described by parameters which are of special relevance to the interpretation of fluid transport phenomena. These parameters should be based on directly measured variables of the pore system and not inferred from indirect variables (such as those determined empirically from transport processes) valid only for a particular pore structure. In this way fundamental relationships between pore structure and fluid transport at the microstructure level can be described. In order to achieve this level of sophistication the three-dimensional interconnected pore structure of filter cake must be determined. Study of fluid transport phenomena in filter cake using x-ray microtomography to characterize the complex three-dimensional pore geometry is discussed. On this basis the Lattice-Boltzmann (LB) method is used to simulate and to establish a fundamental relationship between pore microstructure and effective transport coefficients.

Jan 1, 2002

By J. B. Gwiazda

Introduction Thick seams constitute a considerable portion of Polish coal reserves. In producing mines and those under construction, the reserves where the height is more than 4.5 m (15 ft) total about 24% of all the hard coal reserves. The reserves that are under urban and industrial areas can be extracted using stowing methods for surface protection. About 50% of thick seam reserves can be extracted by caving methods. Thick seam mining methods Thick seams are usually extracted by multilift methods. There are some methods of thick seam mining that generally can be divided into caving and stowing methods. The stowing method is more expensive, but must be used when mining to protect surface features. The more known methods of thick seam mining include • extraction of thick seam in ascending order with stowing ; • thick seam mining in descending order with consolidated stowing; • thick seam mining with gob consolidation; • thick seam mining in descending order with roof caving ; • sublevel caving thick seam mining system; and • thick seam mining system using an artificial roof. Thick seam mining with introduction of an artificial roof The most advantageous method of thick seam mining is the method using an artificial roof. The artificial roof usually consists of wire mesh. Such wire mesh must be durable and must prevent small rock fragments from passing through. The mesh is usually made of steel properly protected against corrosion. The artificial roof is placed on the coal floor of the top slice (Fig. 1). Caving rock falls on the artificial roof and is thus separated from the coal. The next slice is extracted under the artificial roof. The producing face of the next slice must progress within 10 m (33 ft) behind the front of the first slice. As the second producing face progresses, the wire mesh moves down on the coal floor and may be used as an artificial roof for the next slice. Thus, one artificial roof allows the extraction of several consecutive slices. Application of the artificial roof allows for clean extraction and reduces coal losses. It also eliminates the hazard of spontaneous combustion. Introduction of the artificial roof has been limited due to a lack of artificial roof laying equipment. Manual laying of wire mesh is a labor-intensive operation, and it delays face progress, resulting in poor productivity. To eliminate these problems, artificial roof laying equipment was designed at the Polish Central Mining Institute. The support and the method of laying operation is covered by a patent. Artificial roof laying powered support To extract thick seams using an artificial roof, four-leg shield supports with lemniscate linkage were developed (Fig. 2). This shield is used in the first top

Jan 3, 1987

By Christian Maguire

Tunnel contracts in New York have in recent years had few bidders with the bids received being much higher than anticipated. Since 9/11, security has become a key issue in planning key infrastructure projects in New York. This is especially true in the case of large water supply tunnels. Striking the right balance between cost and security was the major factor in determining the best configurationfor the Kensico-City Tunnel. This paper outlines the efforts made to determine realistic probable bid costs for the tunnel contracts, and the innovative approaches taken to deal with security issues.

By Georgios Kalamaras, Chiaia Dinu, Platania Paolo, Alessio Carlo, Giampiero Cirvegna, Claudio Santucci

The Project alignment initiates north of Pinerolo, along the State Road 23[S.S. 23] that is one of the principal arteries to the northwestern Alps where a number of Olympic events for the 2006 Winter Games will be held. The 3.5 km ring road bypasses the Porte habitat by traversing twice the Chisone River. It consists of the following principal structures [Figure 1]: San Martino bridge [130 m in four bays] Prarostino viaduct [130 m in four bays] Craviale tunnel [1055 m] Turinella bridge [a 50 m long bridge that connects the two tunnels] Turina tunnel [665 m] Malanaggio viaduct [350 m in 9 bays]. The road section is 13 m wide and is made up of two 3.75 m lanes, a hard shoulder [1.50 m wide] and a 1.25 m wide curb for each lane. The Project maximum velocity is 100 km/h.

Jan 1, 2005

By Remo Grandori, Manfred Jaeger, Fabrizio Antonini, Luis Vigl

The EVINOS-MORNOS tunnel project with its 30 km of length is one of the longest hydraulic tunnel in the world realised with TBM method. The adverse geological conditions, the high cover and the short construction schedule were a great challenge for the successful construction of this tunnel. The paper will describe: the criteria adopted for the tunnel design, the selection of the construction methods and equipment, the productions of the 4 TBMs adopted and the comparison of the behaviour of the different type of TBMs in the various rock conditions, including special conditions, the characteristics of the adopted in situ and precast linings, a comparison between the foreseen and actual construction schedules, the contractual implications of realising a tunnel in such a severe and complex conditions.

Jan 1, 1995

By JOHN HOMER, Jacob L. Carr, Jonathan K. Hrica, Kathleen M. Stabryla, Iman Benbourenane, Jennica L. Bellanca

Given the recent focus on powered haulage incidents within the US mining sector, an appraisal of collision avoidance/warning systems (CXSs) through the lens of the available research literature is timely. This paper describes a rapid review that identifies, characterizes, and classifies the research literature to evaluate the maturity of CXS technology through the application of a Technology Readiness Assessment. Systematic search methods were applied to three electronic databases, and relevant articles were identified through the application of inclusion and exclusion criteria. Sixty-four articles from 2000 to 2020 met these criteria and were categorized into seven CXS technology categories. Review and assessment of the articles indicates that much of the literature-based evidence for CXS technology lies within lower levels of maturity (i.e., components and prototypes tested under laboratory conditions and in relevant environments). However, less evidence exists for CXS technology at higher levels of maturity (i.e., complete systems evaluated within operational environments) despite the existence of commercial products in the marketplace. This lack of evidence at higher maturity levels within the scientific literature highlights the need for systematic peer-reviewed research to evaluate the performance of CXS technologies and demonstrate the efficacy of prototypes or commercial products, which could be fostered by more collaboration between academia, research institutions, manufacturers, and mining companies. Additionally, results of the review reveal that most of the literature relevant to CXS technologies is focused on vehicle-to-vehicle interactions. However, this contrasts with haul truck fatal accident statistics that indicate that most haul truck fatal accidents are due to vehicle-to-environment interactions (e.g., traveling through a berm). Lastly, the relatively small amount of literature and segmented nature of the included studies suggests that there is a need for incremental progress or more stepwise research that would facilitate the improvement of CXS technologies over time. This progression over time could be achieved through continued long-term interest and support for CXS technology research.

Jun 17, 2022

By J. Brent Hiskey

Thiourea is a reagent capable of complexing gold and silver. With the proper oxidant, thiourea can effectively dissolve metallic gold and silver. A thiourea leaching system possesses potential advantages over conventional cyanidation including acidic solutions instead of alkaline, cationic complexes in contrast to metal-cyanide anoionic complexes, and faster leaching rates with acidic solutions of thiourea. Generally, the rate of metal dissolution in thiourea solution is fastest when ferric ion is employed as an oxidant. Acidic thiourea solutions for certain applications could offer a nontoxic and noncorrosive option for processing gold and silver. This paper provides information regarding the fundamental chemistry of the acidic thiourea system, and reviews the dissolution of both silver and gold in acidic solutions of thiourea. The recovery of gold and silver from acidic thiourea solution is discussed.

Jan 1, 1981