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By R. H. Seraphim

"Western Mines Limited produces gold, silver, copper, lead and zinc from a number of Paleozoic volcanogenic deposits near Buttle Lake on Vancouver Island. The deposits were emplaced along a series of submarine linear volcanic ridges that extended for at least 6,000 metres in a northwesterly direction.Rock types mapped include: andesitic, dacitic and rhyolitic flow s and volcanic breccias; detrital breccias, tuffs and hematitic silts; black and green cherts; and a variety of dykes and sills, including quartz porphyry and diorite. Orebodies are associated invariably, and in places intimately, with quartzsericite schist and rhyolitic rocks. The ore is complex, varying in mineralogy and tenor both within each deposit and from one deposit to another.Recent studies have increased our knowledge of the structure and left no doubt that the orebodies were deposited both within the throats of the linear vents and on paleoslopes adjacent to these vents.IntroductionWestern Mines Limited operates an 850-tonne-per-day mine, located 85 km south of Campbell River, B.C. The mine is at approximately 400 metres elevation, near the south end of Buttle Lake on Vancouver Island (Fig . I). It has operated since early 1967 and produced 3,650,000 tonnes with an average grade of 1.9 g (0.06 oz) gold, 93 g (3.0 oz) silver, 1.6 per cent copper, 1.0 per cent lead and 7.5 per cent zinc per tonne by the end of 1978. Current reserves are 1,157,000 tonnes of 2.7 g (0.09 oz) gold, 117 g (3 .8 oz) silver , 1.2 per cent copper, 1.2 per cent lead and 8.0 percent zinc per tonne (December 31, 1978).Ore from one zone, known as Myra High-Grade, is mined and milled separately because of its grade. Ore milled prior to December 31,1978, plus reserves, 180,715 tonnes of6.6 g (0.21 oz) gold, 554.5 g (17 .7 oz) silver, 0 .8 per cent copper, 3.2 per cent lead and 10.6 per cent zinc are included in the figures listed in the preceding paragraphs."

Jan 1, 1980

By Olaf Andersen

Crucible melt extraction yields short metal fibers with eqivalent diameters as low as 50 µm from almost arbitrary metals and alloys. Highly porous components can be made from such fibers by suitable deposition and sintering methods. This technology is being developed at the Dresden based Department of Powder Metallurgy and Composite Materials of the Fraunhofer Institute for Manufacturing and Advanced Materials (IFAM) and has been applied to gold alloys and iron-base alloys containing small additions of precious metals. From the manufactured gold fibers, sintered structures were made for decorative applications. Additionally, it was found that due to rapid solidification during the fiber formation, precious metals can be finely dispersed in ironchromium- aluminum (FeCrAl) and FeAl20 alloys. Good catalytic activity at elevated temperatures was found in compositions containing 3 wt.-% Ce and 0.5 wt.-% Pt.

Oct 1, 2003

By L. R. Raymond

With the trend toward deeper and consequently hotter holes, measurements of drilling mud properties at atmospheric temperatures are becoming increasingly inadequate.' Both the prediction and control of down-hole mud properties depend in part upon our knowledge of temperatures in the wellbore. Consequently, a better understanding of factors that affect temperatures during circulation and trips could improve drilling operations. It was toward the goal of obtaining this understanding that this study was directed. Other investigators2 have studied the response of fluid temperature in the borehole during trips. However, all of these studies have used an assumed formation temperature profile at the conclusion of circulation and have provided no means to calculate this profile directly. In this study, the formation profile during circulation was calculated. Other investiga-tors3-5 have also studied bottom-hole temperature during circulation. However, they have developed neither general techniques for calculating the entire temperature profile in the system nor generalized methods for predicting bottom-hole fluid temperatures during circulation. Such techniques and methods have been developed and are discussed briefly in the following pages. Temperature Behavior During Circulation Circulation of fluid during the drilling operation is represented schematically in Fig. 1. The process of circulation has three distinct phases: (1) fluid enters the drill pipe at the surface and passes down the drill pipe; (2) fluid exits the drill pipe through the bit and enters the annulus at the bottom; and (3) fluid passes up the annulus and exits the annulus at the surface. To simulate the thermal behavior of the fluid in the system, each of the phases of circulation must be described mathematically. In Phase 1, the fluid enters the drill pipe at a specified temperature, TDo. As the fluid passes down the pipe, its temperature is determined by the rate of heat convection down the drill pipe, the rate of heat exchange between the drill pipe and the annulus, and time. Phase 2 of the circulating process merely requires that the fluid temperature at the exit of the drill pipe be the same as the fluid temperature at the entrance of the annulus; i.e., TD(L,t) = TA(L,l). Thus in Phase 3, the fluid enters the annulus at TD(L, t). As the fluid flows up the annulus, its temperature is determined by the rate of heat convection up the annulus, the rate of heat exchange between the annulus and the drill pipe, the rate of heat exchange between the formation adjacent to the annulus and the fluid in the annulus, and time. These rates of heat exchange and the time dependency of mud temperature are described by well known heat-flow equation.6 Consequently, as shown in the Appendix, the temperature profiles in the drill pipe, annulus, and formation can be obtained by solving Eqs. 1 through

Jan 1, 1970

By Firth B. A

The classification performance of a Dutch State Mines (DSM) Rapped Sieve Bend has been investigated in a series of experiments. Coal slurries of a nominal 0.5 mm size were classified in the separation range of 0.10 to 0.14 mm at pulp densities from 6 to 21 per cent by mass of solids, and flow rates of 110 to 1375 litre min-1.The results obtained showed that the partition curve and water split io oversize was dependent on the solids flow rather than slurry flow rate or pulp density. For most of the operating conditions considered an accurate classification of the fine coal was obtained. The undersize efficiency was susceptible to solids flow rate, and was less than 70 per cent for solids flow rates greater than 16.7 tonne hour-1 metre-1 width of screen.

Jan 1, 1983

By Xiang-dong and Zhu, Xia-jie Hao, Yi-lin Fan, Quan Jiang, Lian-xing Hu, Xia-Ting Feng, Shao-jun Li

"Columnar jointed basalt (CJB), which typically originates from lava flows, is characterized by a special geological structure. The joint network inside the CJB is self-organized into a rough hexagonal arrangement. The field test and measurement during the unloading excavation showed that the columnar joint sets and other internal joint sets not only are important for determining the mechanical properties of the CJB, but also induced its asymmetric unloading deformation and failure. A constitutive model, which considered mechanical deterioration of both the joint sets and rock blocks, was also developed to simulate the unloading behaviour of the CJB. The crack-confinement supporting method for surrounding CJB was developed to overcome the failure of columnar jointed rock mass in the diversion tunnel. Application to the CJB segments of the diversion tunnels in the Baihetan project indicated that this supporting method was reasonable and efficient. INTRODUCTIONColumnar jointed basalt (CJB) rock mass, which typically originates from lava flow, is characterized by a special joint structure. The joint network of the CJB is self-organized into a roughly hexagonal arrangement and leaves behind an ordered colonnade. The widely accepted current view regarding the formation of columnar jointing involves a thermally induced contraction–cooling mechanism (Peck and Minakami, 1968; Degraff and Aydin, 1987; Budkewitsch and Robin, 1994; Lore et al., 2000; Goehring et al., 2006). Although the columnar basalt formation mechanism is fairly understood, the geotechnical characteristics of such rock mass are not well established. In practice, joint sets always induce the multi- failure modes of surrounding rock in the tunneling space (Ibarra et al., 1996; Waltham and Swift, 2004; Mahendra and Bhawani, 2008).According to conventional wisdom in rock mechanics, structural joints affect the mechanical response of rock mass by introducing strong anisotropic effects (Barton and Bandis, 1980; Hudson and Priest, 1983; Brady and Brown, 1985). The columnar jointed rock mass should be considered an anisotropic material given that the joint sets are distributed with some principal directions and characteristic spacing distributions (Cundall and Fairhurst, 1987; Hoek et al., 1998; Wu and Wang, 2001; Budetta and Nappi, 2011; Fortsakis et al.,2012). Columnar jointed rock mass would result in structurally controlled failure patterns, even serious disasters during underground excavation because of the low shear and tensile strengths of intensely joints (Gencer,1985 ;Ishida and Uchita, 2000; Jia and Tang, 2008). The CJB rock mass in the Baihetan hydropower station has exhibited serious stability issues, including sliding, fracturing and even collapse (Shi et al.,2008). Therefore, the geotechnical and geomechanical characteristics of such rock mass should be assessed through in situ investigation and numerical analysis to minimize future accidents during underground unloading excavation."

Jan 1, 2015

By Werner Burger

The Hallandsås project with a long history, first started in 1991, is well known in the tunneling community. In the past it has been stopped twice for technical and environmental reasons. The third attempt started in 2004 using a dual mode rock TBM. The heterogeneous highly fractured and abrasive rock mass as well as large areas of water bearing zones present most difficult subsurface conditions. The tunneling concept is based on the use of watertight segmental lining and a TBM able to operate in open mode, possibilities for extensive pre excavation grouting and high pressure closed mode operation up to 13 bar to cover exceptional conditions.

By C Agreda

The Cushion Blasting Technique applied to solve the high risk case history represented by a 10,704 TM rock locate at 120 M from the hydroelectrical plants of 350 KV each, is described, analyzed and discussed. The generation and distribution of 700 KV produced by two hydroelectrical plants must not be interrupted by any reason, because the 26 district of the province of cajatambo, of the Lima department; would not have electrical power. The search of the best alternative and methodology, the drilling and blasting pattern calculations, charge design and loading, connections and initiations of the 50 blasts are described, analyzed and discussed. Finally, the excellent results from a technical, economical, enviromental and safety point of view of the 50 primary blasts are discussed and emphasized.

Jan 1, 2005

While SME is hosting its Annual Meeting at the Phoenix Convention Center, Feb. 28 to March 3, one of the finest collections of mining history will be on display just 15 blocks away at the Arizona Mining and Mineral Museum. Inside the museum, visitors will be treated to a treasure trove of minerals, gems, me¬teorites, rocks, fossils, mining artifacts, historical exhibits and interactive displays on modern mining. The museum is located at 1502 West Washington. For SME Annual Meeting attendees, this is a free, eight-minute Dash bus ride 15 blocks west of the Phoenix Convention Center.

Jan 1, 2010

Vein swarms in metamorphic terranes such as the Otago Schist Belt, New Zealand provide evidence of past hydrothermal flow systems leading to fault initiation and reactivation. A major episode of hydrofracturing and fluid redistribution occurred during early Cretaceous exhumation of the schist belt. As a result, presently exposed lower greenschist facies greyschists in NW Otago are pervaded by abundant quartz-filled hydraulic extension fractures with associated normal faults hosting quartz¦scheelite¦gold mineralisation. Once the effects of Cenozoic folding have been removed, a regional subhorizontal schist foliation contains an aligned array of subvertical hydrofractures striking NNW, striking parallel to a set of low-slip conjugate normal faults; the array extends over an area >1500 km2 and over a depth interval >5 km. The hydrofracture array comprises a mesh of interlinked extensional-shear and pure extension veins. These veins show mutually cross-cutting relations. Extensional hydrofracturing apparently preceded the development of major throughgoing normal faults. Low-displacement normal faults are infilled with laminated quartz (¦ scheelite) veins (

Jan 1, 2002

By Franciszek Letowski

"Recovery of precious metals associated with a sulphidic matrix has an important economic effect on complex sulphide ore treatment. Because a significant portion of the silver and gold associated with pyrite are rejected to tailings during the selective flotation of pyritic Zn-Pb-Cu ore, other ore processing routes have been investigated.Direct leaching of the ore with ferric sulphate solution followed by separation of different components of the solid suspension by flotation was applied. Such a process allows for: production of zinc sulphate solution; transformation of galena PbS to insoluble lead sulphate PbS04 and its accumulation in a non-floatable fraction together with precipitated geothite FeOOH and other insoluble gangue minerals; separation of sulphur and non-decomposed sulphides in the floatable fraction.Laboratory research carried out on the ore samples from an Alaskan pyritic deposit from the Delta region indicates that gold and silver are mostly concentrated in the floatable fraction.Total recovery of zinc from the ore attains 96.5% to 98.5% after ferric sulphate leaching. About 85% of copper was extracted from the ore during the ferric sulphate and subsequent ferric chloride leaching, and about 6% of the copper remained in the non-floatable fraction and mixed fraction during the leaching-flotation step. Extraction of lead from the nonfloatable fraction during leaching with calcium chloride solution attained 98% to 99%. Extraction of silver from the floatable fraction during leaching with ferric chloride solution reached 98%. Extraction of gold from the floatable fraction during cyanide or thiourea leaching reached 71% to 89%. The results of the laboratory research are presented."

Jan 1, 1987

By J. Bruce Clemmer

In the experimental concentration of Vermont talc-magnesite ores, talc concentrates and tailings rich in magnesite were obtained. On account of the possible market value of the magnesite, the tailings are given consideration' in this report along with the talc. After some comments about the talc industry, the magnesite that accrued as tailings will be considered. Then the flotation results will follow.

Jan 1, 1936

The Bureau of Mines is active in programs pertaining to solid waste disposal and land reclamation. Nine reclamation projects of mining companies and six projects of the Commonwealth of Pennsylvania were investigated to provide information on the procedures, costs, and results obtained from reclamation projects of bituminous coal-waste disposal areas. Refuse disposal costs of mining companies ranged from 9 to 28 cents per ton-mile, and quantities disposed of ranged from 600 to 4,500 tons per day. Spreading and compacting the refuse at the dump site ranged from 3 to 20 cents per ton. Cost of covering with soil and planting ranged from $750 to $1,646 per acre. Total costs of reclamation for the Pennsylvania projects ranged from about $1,800 to more than $15,000 per acre. Refuse preparation costs ranged from $772 to $5,550 per acre. Soil covering and planting costs ranged from $1,083 to $5,086 per acre. The best results were obtained by soil preparation and conditioning prior to planting. The type and depth of soil and effect of climate were also factors.

Jan 1, 1973

By Kevin Connor

There was little change during 1988 in the production of minerals in Burundi. The Government of Burundi, which banned all commercial mining operations in the country in 1979, lifted the ban on mining of alluvial gold deposits and started a program of small-scale artisan gold mining in October. Along with the legal mining of gold, licensed gold trading counters were established. Other mineral commodities produced were kaolin clay, lime, and peat. In compliance with the Government ban, the only mineral wealth exploited for commercial sale and export was alluvial gold. Through financial assistance from the International Bank for Reconstruction and Development (World Bank) and the United Nations Development Program (UNDP), a study to inventory the country's mineral resources continued throughout the year. As part of this study, during the year, a West German company undertook a drilling program to further outline the nickel reserves of the Musongati area in central Burundi. Results of the work as of yearend were disappointing, with only 12 million tons of ore identified with better than 2% nickel content proven. Investigations also continued during the year regarding the centrally located deposits of vanadium-bearing titaniferous magnetite. A Norwegian company contracted to prepare a prefeasibility study for developing the deposit. The British Sulphur Corp. Ltd. was nearing completion of its $1.2 million2 study of the phosphatic limestone deposit at Matongo-Bandaga at yearend. Ore reserves of about 17 million tons grading 11% phosphorus pentoxide (P2O3) had been identified. The phosphate zone overlies a carbonatite rock, which could provide the basis for a cement industry. Additional drilling was planned for 1984. Exploration for gold was underway in 19S3 in northern Burundi through UNDP funding. Several primary deposits of shallow semimassive sulfides with gold values ranging from traces to 11 grams per ton had been discovered. With assistance from the Federal Republic of Germany, bastnasite reserves of 5,400 tons, with associated high europium oxide and cerium content, were verified, and the prospects for finding

Jan 1, 1985

By B. Denby

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993. The design and scheduling of open pit operations are consistent problems encountered by the surface mining industry. Numerous techniques and algorithms have been developed to assist the mining engineer in the creation of optimum development strategies. Virtually all the practical techniques that have been produced have concentrated on one of the aspects (limit definition or scheduling) at the expense of the other. It has long been recognised, however, that the two activities are intrinsically linked and thus solving either problem independently of the other can only ever produce sub-optimal results as a whole. This has been termed the "circular reasoning problem". It has also been recognised that, for all practical-sized situations, solving both problems simultaneously is virtually impossible using conventional techniques due to the massive size of the search space involved. A technique is presented which is based on a self-learning genetic algorithm, which provides a combined pit limit and extraction schedule simultaneously in order to maximise the NPV (net present value) of the extraction. The theory is developed in two-dimensions and a number of examples of its application are presented. It is proposed that this approach is a highly efficient, heuristic technique offering the potential to transcend the circular reasoning difficulties of separate pit limit and extraction scheduling systems. Extension of the technique into three-dimensions and its application to realistic problem sizes are discussed

Apr 1, 1994

By M. J. Beus

A shaft is truly the "lifelinen of an underground mine. Damage to the shaft lining and guides as a result of ground movement can result in serious loss of production and extensive and continual repair. In some mining districts, annual shaft repair and maintenance costs resulting from high rock stresses and excessive displacement are in the millions of dollars per year. For many years, the Bureau of Mines has conducted research to characterize the rock mass and to develop structural guidelines to improve the design of accessways in deep mines. Much of this work has centered on determining the in situ conditions that affect the structural stability of shafts in the Coeur d'Alene Mining District of northern Idaho. Recent work by Beus and Board (1984) has concentrated on measuring the rock and support behavior during sinking of the Silver Shaft at the Lucky Friday Mine. These results are currently being used as a comparative data base for further basic research as well as to establish structural design criteria. The factors affecting the deign and structural stability of deep mine shafts are numerous. A design approach that use field data as input and directly compares field measurements with numerical models can validate the procedure and provide realistic design criteria. Naturally occurring "fixed? conditions such as magnitude, direction, and ratio of in situ stresses, geologic environment, and physical properties and constitutive relationships of the rock mass ere obviously basic to numerical modeling.

Jan 1, 1989

By Uusna S, Canning R. G, Goodheart B. A

The development of a process for removal of iron oxides from ilmenite is outlined whereby the Ti02 content of Western Australian ilmenites can be upgraded from 55 to approximately 90 per cent. In the first stage, the iron oxides are reduced with solid carbon (coal) to metallic iron. Experimental reductions were carried out in crucibles, a fluidized bed, and a small pilot plant rotary kiln. The reduced ilmenite was then agitated in aerated water, in the presenceof catalysts, so that the iron "rusted" away from the ilmenite grains and the precipitated iron oxide was easily separable by decantation.The influence of variables on the rates of reduction and oxidation are discussed. The oxidation rate was examined for both the physical oxygen transfer characteristics and electrochemically by reference to Pourbaix diagrams, in which redox potential is plotted against solution pH.The upgraded ilmenite is expected to be an attractive material for pigment manufacture, and the iron oxide has prospects of being a marketable by-product. The process may possibly be applied to other ores.INTRODUCTIONThere are extensive deposits of ilmenitic beach sands, Le. iron titanium oxides of the general formula FeTi03, 'occurring in the lower south-west portion of Western Australia, and although there has been considerable commercial development, local producers face keen competition on a freight-cost basis. Thus the removal of the unwanted iron oxide constituent would have the double advantage of reducing the freight differential and presenting a more attractivematerial to pigment manufacturers.

Jan 1, 1965

By Gruenewaldt von

Paper presented at the IAGOD international symposium on mineralization related to mafic and ultramafic rocks held in Orleans, France, 1-3 September 1993. The principles of shear-driven aggregation of particulate matter suspended in fluids, a common industrial method of concentration and separation, were applied to a convecting magma to estimate the time required to sparge or strip the PGE and Cr content and concentrate it into the boundary layers. It was calculated that an ore-grade (e.g. 6 ppm PGE) boundary layer about 1 m thick would require 100 000 years at most to form from a body of magma 500 m deep with a PGE content of 20 ppb. Since concentration would be most vigorous when the magma was warmest, at least half of this concentration would take place in the first 10 000 years. The effect of dispersive pressure in the boundary layer would generate a concentration high of refractories just below the top of each boundary layer and another just above the bottom. If the magma was a double-diffusive system, it might evolve by the downward cascade of enriched boundary-layer material into the hotter, lower magma layers, where depending on saturation levels chromites would equilibrate and sulphides undergo partial or total resorption, enriching PGE levels in any remaining sulphides. This cascade process would in time greatly enrich the lower regions in PGE-bearing sulphides and chromites

Apr 1, 1994

One would anticipate that after 40 years in the mineral industry it would be simple to project the trends at least 5 or 10 years into the future. However the last 20 years, 1950-1970, have been so different in the mineral industry from the years 1930-1950 that I suggest only 20 years or so are relevant to any forward projection.Those, of us that have been about during the last 40 years find it hard to relate the two periods.The first with the depression, low base metal prices, attempts to revive the gold industry, very little export of minerals, and finally World War II and the recovery period.The second, a period of unimagined discoveries and the reappraisal of a wide variety of minerals and metals-iron, coal, bauxite, beach sands, manganese, oil and gas, and nickel, to name but a few.The second period started early in the 1950s and was triggered off by the search for oil in Australia.Rough Range No. 1 was an important milestone in our history because it initiated a series of speculations and the re-examination of much of our thinking about our mineral resources. It lead to the discovery of bauxite and the start of a flourishing aluminium industry.The realization of the extent of the iron ore resources was another, major step and the influx of overseas capital and competence started the large wave of development made effective by the Japanese markets.The momentum of the late 1950s has carried us to where we are today and will undoubtedly carry us further forward in the next few years.All this development in the mineral industry has come at a time when our pastoral industries have reached a difficult period. I have no doubt that if it were not for the mineral industry Australia would at the moment be experiencing one of its blackest eco...

Jan 1, 1971

By Mark Rybak

On August, 31, 2006, Tropical Storm Ernesto hit the City of Richmond, Virginia. The Battery Park area was hit particularly hard, as flooding forced an evacuation of the area. A large sinkhole collapsed a sewer line in the Battery Park area, blocking the pipe and causing more serious flooding. This case history describes the fast track design, bidding, and construction of an emergency tunnel to bypass the collapsed sewer. Innovative value engineering, tunneling and shaft sinking methods, and final lining design all contributed to the success of this project. The storm inundated Richmond, Virginia with up to twelve inches of rain in some areas causing widespread flooding and damage. One of the hardest hit areas of Richmond was Battery Park. A major trunk sewer in the Battery Park area collapsed causing local combined sewer and storm-water flooding. The collapsed sewer was an 8'-3" wide by 9'-6" high arch sewer that was constructed in the nineteen twenties and later filled over with municipal solid waste and a soil fill cap to current elevations. A sinkhole was created in the area of collapse approximately sixty feet deep and one hundred feet in diameter causing the existing arch sewer to become blocked. As a result of this blockage contaminated flood waters reached depths in low lying areas in excess of twenty five feet. [ ]

Jan 1, 2008

Fully mechanized longwall mining with large mining heights (LMHs) in shallow-depth thick coal seams has been widely applied in Shenfu coalfield, China. Dynamic loading and rib spalling is serious when the LMH working face experiences periodic weighting in shallow coal seams. The advanced breaking position (fracturing ahead of the face) in the roof affects the strength of the mine pressure (weighting) when the roof is broken. Based on the theory of the “elastic foundation beam,” this paper presents a mechanical model for the advanced breaking of the roof, including a predictive formula. In an attempt to verify the formula, a field program consisting of multiple-point borehole extensometers installed in the roof in advance of the longwall face was performed in the No. 22201 working face of Zhangjiamao coal mine in the Shenfu mining area, China. The field measurement results show that the roof movement of the LMH working face is detected prior to roof pressure increase, and that the roof breaks approximately 5–8 m ahead of the face. This compares with a calculated value of 6.9 m, indicating that the formula developed in this research is reliable and should have application in predicting roof pressure associated with LMH working faces in shallow coal seams.

Jul 28, 2020