Search Documents

By Jozef S. Stachulak, Bruce R. Conard

INTRODUCTION The concern of occupational exposure to diesel exhaust pollutants is an important workplace issue for the mining industry. During the last three decades of diesel operations at Inco, a significant amount of research and improvement has been made in the area of work environment, and effective diesel operation. This paper will review the experience gained by Inco's Ontario Division from the implementation and the use of modern engines, improved fuel quality, and the exhaust control technology, coupled with adherence to proper maintenance and ventilation design and practices. Past monitoring practices and the current occupational monitoring program at lnco are outlined. A major new research initiative involving multi-stake holders in diesel performance is described. MINING IN THE SUDBURY AREA The discovery of nickel-copper ore in the Sudbury area dates back to the year 1856. The existence of this orebody was noticed when a strong compass deflection was observed by a provincial surveyor. This discovery, even though documented in official re- ports, failed to arouse any public attention at that time. In 1884, a rock-cut was blasted through a small hill near the village of Sudbury to permit laying track for the Canadian Pacific Railway (Boldt 1967). The rock-cut uncovered a body of massive sulfides with a copper content of over nine percent. The mineralization is concentrated along the outer margin of the Sudbury Basin, an oval-shaped structure having a dimension of 55 x 95 kilometres. The ore extends down-dip to to at least 3000 metres below the surface. The mining methods at lnco can be divided into two categories: "filled-stope" and 'bulk" mining. This division, in the broad sense, may also reflect the environmental conditions of the mine. In the past, the selection of a mining method was based on the size, shape, grade and the strength of the ore and its surroundings. The recent development of improved technology and mining equipment permitted wider application of low cost bulk mining methods. UNDERGROUND DIESEL EQUIPMENT The first diesel-powered machine, a 145-horsepower scooptram, was put into operation in March 1966, in a cut-and-fill stoping complex at Frood Mine. The number of diesel machines underground in the Inco, Ontario Division, mines was increased to 360 units by 1971,550 in 1977 (Rutherford 1978), and over 830 diesel-powered units in 1995. The following list indicates current mobile diesel equipment. LHD 194 Loaders 81 Trucks 28 Jumbo Drills 78 Personnel Carrier 101 Service Equipment 155 Locomotives 50 Bolters 30 Scissor Lift 113 About 20 percent of the LHD and truck units are equipped with electronic fuel controlled engines. COMPOSITION OF DIESEL EXHAUST Diesel exhaust contains hundreds of pollutants (Watts 19921, including components of unburned fuel and lubricating oil and products of incomplete combustion of the fuel and oil. These pollutants are emitted either as gases or as particles. Gaseous pollutants include carbon monoxide, nitrogen oxides, and sulfur ox- ides, as well as a variety of organic compounds, such as hydro- carbons, aldehydes, and polynuclear aromatic hydrocarbons. The particle phase, also known as diesel particulate matter (DPM), is the filterable portion of diesel exhaust. Figure 1 depicts the trimodal particle size distribution that arises from different mechanisms of aerosol generation (Cantrell and Rubow 1992). Primary combustion aerosols, including diesel exhaust aerosol, are formed as very small particles (in the 0.001 to 0.08 micrometre range), but physical mechanisms such as condensation and coagulation quickly transfer the aerosol mass from the nuclei mode to the accumulation mode. These processes result in a mass median diameter of approximately 0.2 micrometres for diesel particulate matter, and 90% of the particles are less than 1.0 micrometre in size. These particles have a high surface area, permitting the adsorption of different substances produced during combustion. Mechanically generated aerosols, on the other hand, typically contain particles greater than 1 micrometre in diameter. The particle phases of diesel exhaust contain three components (Bagley, et al, 1996) shown by Figure 2, namely: a carbon- aceous fraction composed mainly of solid-carbon particles, a sulfate fraction containing small hydrated sulfate particles, and a soluble fraction that contains compounds that are soluble in organic solvents and are adsorbed or condensed onto carbon core particles. These compounds consist primarily of higher molecular weight hydrocarbons and PAH's and may contribute 15% to 45% of the weight of the total particulate matter (Schuetzle, 1983). The control of these pollutants is necessary to ensure a healthy work environment. Proper engine maintenance, engine design modifications, improved fuel quality, and use of exhaust control technology, coupled with good ventilation practices, all

Jan 1, 1997

By Kugan Kuganathan

Pastefill is being increasingly considered as a viable fill by underground mine operators. Mount Isa Mines (MIM) chose pastefill to fill their deep copper mine (>1200m deep) after considering various other types of fill in the feasibility studies. During the development of pastefill at Mount Isa (1996 - to date) the Mining research of MIM developed two cost effective, reliable and simple testing methods and used. With the help of these tests the behaviour of MIM pastefill was studied thoroughly and the most optimum mix design for pastefill was achieved. The MIM's pastefill plant, the largest in the world with a capacity of 450rph continuous pastefill production and unique in the process used, has been built (1998-1999) to produce pastefill to the specification developed through extensive testing program using the Flow Cone and Mini Slump cone Tests. As a consequence, it is now possible to select the optimum pastefill mix designs and predict their flow behaviour in bore holes or pipe lines using only these tests. MIM Blended Tailings Pastefill (BTPF) uses 3-3.55 Portland cement and the cost of pastefill is much lower than the total tailings pastefill, that could be produced from the same tailings.

Jan 1, 2001

By Alvaro Souviron, W. W. Atkinson

The porphyry copper deposit at Los Pelambres is a resource exceeding 2 Gt (2.2 billion st) of 0.7% copper and 0.02% molybdenum. It includes a high-grade zone of +1% copper that is amenable to open-pit mining with a low stripping ratio. Metallurgical testing has indicated that the ore has exceptional characteristics, and that recoveries of 96% for copper and 93% for molybdenum can be obtained by conventional flotation methods. This paper summarizes the history of the prospect, the geology of the ore body and the surrounding area, and the procedures and results of exploration.

Jan 1, 1987

By Trevor A. Moss

Installation of equipment and structures at mines often requires mine planners to evaluate unique loading and operating conditions. Consideration of these unusual features is required throughout design and construction and into operation. Most planners understand the necessity of employing sound civil, structural and mechanical engineering techniques to design these structures and equipment. However, the influence of geotechnical factors on the overall progress of construction and operation is less appreciated. Mine operators routinely perform exploratory drilling to define ore deposits. These exploration activities can be extensive and often include provisions for assessment of subsurface conditions as they relate to the mining operation - requirements for ground support. All of these factors are important to the economics of the mine and are well justified. Surface facilities are provided to access and service the mine, and they play an important role in the successful development and operation of a project. Headframes, hoist foundations and shaft collars, in particular, are examples of unique installations encountered at underground mine sites. The design and above-surface behavior of these facilities can be analyzed with the usual fundamental engineering practices employed throughout the engineering professions. However, near surface exploration for the purposes of assessing soil and rock conditions for foundations is often given a reduced priority and less consideration. This article provides an outline of the benefits and importance of performing such exploration. References here relate particularly to shaft headframes, hoists and shaft collars. But the issues raised apply equally to other installations of a similar nature, including milling equipment.

Jan 1, 1992

By D. W. Park

Longwall mining is considered the most efficient underground coal mining technique in terms of coal extraction ratio, production rate, and safety standards. Due to the increasing demand for higher coal production, wider panel and faster face movement have become the recent trends. Thus, longwall mining can create unexpected threats such as roof falls, excessive face convergence, shield damage and numerous maintenance problems causing sudden interruption of coal production and serious safety hazards. A recent study at the University of Alabama is dedicated to develop LoSCoMS (Longwall Strata Control and Maintenance System) which integrates real-time shield monitoring, data presentation, analysis, forecasting, and warning modules. The main objectives of this system is to provide the stability and maintenance information, at every minute, such as high load, low setting pressure, leg leakage, etc., analysis of various mining and geological parameters to determine past and present roof characteristics and forecasting of loading patterns for the following mining cycles, next periodic weighting, etc. Using this unique system, mine operating personnel are well aware of past, present and future roof loading patterns at the longwall face, and thus, proper safety measures can be taken ahead of time.

Jan 1, 1997

By Thomas D. Kaufmann, Robert C. Drury

Few factors are as important as fluctuations in aggregate economic activity and exchange rates in determining the profitability of mineral investments. Macroeconamic theory explains how the two factors are interconnected in today's world and in tomorrow's. We can use macro¬economic theory to lessen some of the risks in mineral investments. And in the current state of the world the risks are high. The above paragraph summarizes our argument. Our goal in this paper is to examine the nature of contemporary business cycles so as to explain their implications for the metal industries, particularly the implications for capacity. Thus, our first section examines the workings, causes, and history of the recent economic fluc¬tuations. In doing so we must understand how current world economy is interconnected, that is, how economic events in one country are trans¬mitted to the rest of the world. Our view is that governments and central banks are key actors in the creating of economic fluctuations. Then, in section two, we work out the implications of section one for the metal industries focussing on comparative advantage, trade, and capacity decisions. Over the last fifteen years the world economic system has had slow overall economic growth and has had strangely unpleasant recessions. While future business cycle will not repeat the de¬tailed pattern we have seen, there will be similarities. The similarities need to be under¬stood before investment occurs. The slow growth in the world economy since the early 1970s has aggravated the problems from business cycles, created its own problems, and has partially hidden the effects of other events. Major realignments of currencies are likely to take place over a business cycle. The nature of the causes of the cycle will determine the direc¬tion of change in the exchange rates. For example, whether a USA recession will be accompanied by a weaker or a stronger dollar will be determined by the cause of the recession. The realignment of currencies over a business cycle leads to a realignment of comparative advantage in the metal industries. Thus, not only will world metal consumption vary over the business cycle but the impact on various countries' metals industries will differ consi¬derably. Competitiveness often depends more on the value of the dollar than it does on inherent efficiency and wage rates. Capacity decisions are inherently riskier due to the country specific nature of exchange rate risk. A realignment of currencies changes the pattern of trade if and only if the country with the cheaper currency also has idle capacity. The importance of our topic is indicated by Table 1 which shows the impact of cyclical and exchange rate shocks on the USA metal industry. In the cyclical downturn, from the peak of 1979 to the trough of 1982, consumption dropped by a fifth to a third. Metal price moved in the same

Jan 1, 1989

By M. J. Virnig, Peihao Qi, J. Brent Hiskey

The mechanism of gold uptake from iodide solutions by carbon has been investigated. Adsorption isotherms for gold and iodine were established. For activated carbon, approximately 300 mg of gold and 1000 mg of iodine were extracted per gram of carbon at maximum loading. Examination of loaded activated carbon particles by scanning electron microscopy reveals isolated patches of gold deposited on the carbon surface. High-resolution transmission electron microscopy shows that fine gold particles (1-4 nm diameter) are uniformly distributed within the carbon. Iodine was also observed throughout the matrix. The uptake of gold by carbon from iodide solution involves a combined reduction and adsorption process, where the gold iodide species is reduced to the metallic state superficially and adsorbed in the porous structure of carbon. A few experiments for the gold-chloride and gold-bromide systems were carried out for comparison.

Jan 1, 1993

By Arthur W. Ruff

Estimated reserves of high-grade iron ore at Serra dos Carajás total 16 billion metric tons and have an average grade of 66.7 percent iron, 2.2 percent combined silica and alumina, and 0.05 percent phosphorous on a dry basis. Hematite is predominant and no significant sulfur or other deleterious elements are present. Figure 1 illustrates the comparative magnitude of the Carajás reserves. Serra dos Carajás is located in northern Brazil, about 550 kilometers southwest of Belém, Pará. It is six degrees south of the equator between the Xingu and Tocantins Rivers. Both rivers flow northward toward the Amazon River. The greater part of the area is covered by thick jungle, and the most practical means of access is by air. Figures 2 and 3 show the location of Serra dos Carajás. Figure 4 shows the distribution of the major iron-ore deposits.

Jan 1, 1973

By Donald S. Bubar

The Separation Rapids property, located approximately 60 km (37 miles) north of Kenora, Ontario, Canada, is host to one of the largest rare metal pegmatite deposits in the world. This pegmatite was named the Big Whopper by its discoverer, Dr. Fred Breaks of the Ontario Geological Survey, because of the exceptional length and width of the surface exposure. The property is readily accessible from a main, all-weather road via a network of secondary logging roads. The main line of the Canadian National Railway passes through the village of Redditt, just 40 km (24 miles) south of the property. The Big Whopper is one of the complex-type (petalite sub-type) class of rare metal pegmatites that are geochemically the most highly evolved in the spectrum of granitic pegmatites. Such deposits are economically important as resources for the rare metals lithium, tantalum, cesium, and rubidium. While complex-type pegmatites are found in many areas of the world, most are too small to be profitably mined, however, with an inferred resource in excess of 15 million metric tons (mt) (17 million short tons [st]), the Big Whopper is only the fourth deposit of its type in the world with the size required to be of major economic importance. The other three deposits, which are currently in production, are the Tanco mine in Manitoba, the Bikita mine in Zimbabwe, and the Greenbushes mine in Western Australia. The Big Whopper is situated in the eastern continuation of the Archean Bird River greenstone belt which also hosts the Tanco pegmatite, approximately 60 km (37 miles) to the west. The principal commodities identified in the portions of the Big Whopper pegmatite explored to date are petalite (LiAlSi4010) and rubidium-rich K-feldspar. These are industrial minerals with important applications in the glass and ceramics industries. The Big Whopper also contains substantial quantities of lepidolite, a lithium, rubidium-mica which is the principal ore mineral for rubidium metal. Tantalum and cesium occur in anomalous levels with the petalite mineralization, and the possibility of finding zones of high enrichment in these valuable high-tech metals elsewhere in the deposit is excellent. Such enriched zones are typical of pegmatites as highly evolved as the Big Whopper. To date, the geological mapping and diamond drilling work completed by Avalon have delineated the Big Whopper pegmatite system over a strike length exceeding 1.5 km (0.9 miles), over widths ranging from 10 m to 80 m (30 feet to 260 feet) in thickness, and to a vertical depth of close to 300 m (1,000 feet), where it remains open. The pegmatite system consists of a vertically oriented massive petalite pegmatite dyke striking 280 degrees that is flanked by amphibolites containing a swarm of narrower albite and petalite dykes which have all undergone intense deformation in a high strain zone resulting in folding and intense shearing. The Big Whopper exhibits a mineralogical zonation pattern which is complicated by the superimposed deformation that has both folded and stretched the deposit. Drilling has defined a dilute geological resource totaling 7.1 million mt (7.8 million st) grading 1.283 percent Li20, 0.346 percent Rb20, and .007 percent Ta205 over a strike length of 600 m (2,000 feet), and to a vertical depth of 250 m (820 feet), where it remains open. The petalite and rubidium-rich-K-feldspars contained in the Big Whopper all appear to be of superior quality. The grades are consistent with a petalite content averaging 25-30 percent and a rubidium-rich-K feldspar content averaging 15-20 percent. The remainder of the rock consists mainly of albite, several types of mica, and quartz. Accessory minerals include columbitetantalite, cassiterite, apatite, garnet, and gahnite. Market studies show that the deposit is located close enough to existing transportation infrastructure to access rapidly growing, major markets in the glass and ceramics industries, both in the northeastern U.S. and Europe. There are only three competing lithium minerals producers in the world with the Bikita mine in Zimbabwe being the only major producer of petalite. The other lithium deposits produce spodumene, a less desirable lithium mineral. Lakefield Research Limited has successfully designed a process to produce an ultra-pure petalite concentrate containing up to 4.65 percent lithium oxide, and as little as 0.014 percent iron oxide, low levels of soda and potash, and negligible amounts of other trace elements. With these specifications, Avalon will have an excellent quality product for glass-ceramics applications such as Corningware®, CERAN® stove tops, and other thermal shock-resistant products. Lakefield is presently designing the balance of the flowsheet to produce separate concentrates of rubidium-rich K-feldspar, albite, mica, tantalum, tin, and high-purity quartz. Initial test work indicates that the feldspar products will be of exceptional quality. The K-feldspar concentrates contain 11-12 percent K20 and 1 percent Rb20, while the sodaspar contains over 10 percent Na20, and both have very low iron (0.01 percent Fe203). A preliminary economic model shows that with an initial production rate of 90,000 mt (100,000 st) per year, expanding to 170,000 mt (190,000 st) per year over 5 years, the project is capable of generating over CDN $10 million per year in pre-tax cash flow by year 5 on a capital cost of approximately CDN $30 million.

Jan 1, 2001

By P. A. Plunkert, D. E. Morse, L. McCartan, S. F. Sibley

Following the recession of 2001, restrained consumer spending, declines in domestic manufacturing and industrial output, and increased unemployment led to a lack-luster year in the domestic economy. In 2002, the U.S. real gross domestic product (GPD) grew only 2.4%. Significant production declines in the U.S. metals industry were registered by copper, lead and zinc producers. Steel producers, despite a slight improvement in shipments, continued to face strong foreign competition, higher energy costs and lower prices for their products. Homebuilding and other domestic construction sectors— major consumers of nonmetallic mineral products such as cement, brick, glass and stone — remained strong enough to help raise the output of industrial mineral materials slightly above 2001 levels. A strong U.S. dollar relative to other national currencies continued to weaken the competitive stance of U.S. metal and non-metal mineral materials companies alike against foreign producers in markets at home and abroad.

Jan 1, 2003

By Andrew B. Allen, Charles W. Robinson, Robert L. Schneider

In April, the US Synthetic Fuels Corp. broke a three-year silence and made its first financial award by approving a $820,750 loan for the First Colony peat-to-methanol project in North Carolina (ME, May, page 403). Peat Methanol Associates (PMA), a partnership between Koppers Co., ETCO Methanol Inc., Transco, Peat Methanol Co., and l. B. Sunderland, broke ground at First Colony last year and plans to begin production in Dec. 1985. Although the award is only a small part of Synthetic Fuels Corp.'s $15-billion budget, it does signal the corporation's intention to move aggressively ahead. It also is a positive indication that First Colony will be completed and operated successfully. This article describes the methods and equipment that will be used to harvest peat at First Colony, as well as how the peat will be converted to methanol. Introduction Peat deposits found along North Carolina's coastal plain contain high-quality fuel-grade peat with an average heating value of more than 23.3 MJ/kg (10,000 Btu/lb) (dry), with a low sulfur and ash content. The deposits differ from other US peats in that they contain large, sound Atlantic White Cedar and Cypress logs, stumps, and roots that may extend throughout the full depth of the deposit. A second difference is that these deposits are much more highly decomposed and, in the raw state, have the appearance and feel of a heavy, reddish-brown grease. These factors make it impractical to use standard production equipment so a new line was developed. Also, because of these conditions, techniques were modified to facilitate production. First Colony Farms, located near Creswell, NC, developed and evaluated a milled peat program. Equipment for this production method was designed and built, production rates were established from field operations, drying rates were established, weather data were analyzed, and total operating and capital costs were estimated. The method depends on the sun and wind for drying peat to the desired moisture content, in this case around 40%. Therefore, field preparation is actually the construction of a large solar collector to dry the peat so it can be harvested and stockpiled. It is essential that this collector be properly profiled initially and maintained during production to prevent precipitation from ponding. Initial Field Preparation Initial field preparation includes cleaning existing canals and constructing ditches and water control structures for proper drainage of rainwater run-off, building adequate roads for site access, removing surface vegetation, and profiling and sloping the fields. At First Colony, the 60.7-km2 (15,000-acre) harvesting area was divided into 129.5-hm2 (320-acre) blocks about 1.6 km (1 mile) long and 805 m (0.5 mile) wide. This was accomplished by cleaning main outfall canals with adjacent roads built from canal spoil at 1.6-km (1-mile) intervals. Existing intermediate canals that feed into main outfall canals at 805-m (0.5-mile) intervals also are cleaned. Headland roads are constructed from canal spoil along each side of each intermediate canal. This 129.5-hm2 (320-acre) block is then divided into 32 harvest strips by small V-ditches constructed at 50-m (165-ft) intervals. At the end of the field with the lowest elevation, corrugated steel pipe culverts are installed under the headland road in each V-ditch to control rainwater runoff into intermediate canals. Runoff water from the fields is diverted to a holding pond to prevent any increase in peak water runoff rates and to allow for more uniform drainage rate than experienced to date. After the drainage system is installed, harvest strips are ready for grinding and sloping operations. Surface vegetation, made up of small, waxy-leafed shrubs such as Gallberry, Bayberry, Magnolia, and scattered pond pine, can be effectively ground and incorporated into the upper surface of the peat layer. Here, it will rapidly decompose and have little effect on overall peat quality, thus eliminating the standard practice of pushing the vegetation and upper wood layer into long windrows with bulldozers and hauling this debris from the fields. Incorporating vegetation into the upper surface is known as the initial 102-mm (4-in.) surface vegetation grind and is accomplished by using a modified Bros Rota Mixer. Following this operation, and by using the same unit, a sec¬ond grind with a depth of 200-255 mm (8-10 in.) is made. This reduces the debris to a finer consistency, mixes it with the upper peat layer, and grinds any wood found in the upper 200-255 mm (8-10 in.). After initial grinding operations are completed, the augering or sloping operations can be accomplished with little or no hin-

Jan 7, 1983

By Robert J. Henning

The term olivine was first used in 1790 by J. Werner, and the corresponding mineral was so named because of its olive-green color (Hunter, 1941). Olivine is the principal component of the rock known as dunite. While by classic definition dunite is composed of 90% or more olivine, commercial use of these terms has resulted in more specific definitions. Commercially, the term olivine is used to designate a material that consists of 85% or more forsterite and contains 45 to 50% MgO, 39 to 42% SiO2, 5 to 8% Fe2O3, and has an ignition loss (LOI) of 1 to 2%. The term dunite designates a rock that contains 36 to 45% MgO, 36 to 39% SiO2, and has an ignition loss of as much as 10% (Teague, 1983). GEOLOGY Olivine is found in basic igneous and basic metamorphic rocks whose age varies from pre-Ordovician to Tertiary. Economic deposits are of magmatic origin and are restricted to the dunite variety of the peridotite group of ultrabasic igneous rocks. Olivine also occurs in basic igneous rocks such as gabbro, basalt, and diabase and more rarely as an accessory mineral in granite and metamorphosed crystalline limestones. Mineralogy The term olivine refers to a group of orthosilicate minerals in isomorphous series with magnesium-rich forsterite (Mg2Si04) as one end member and iron-rich fayalite (Fe,SiO,) as the other. In most olivines the ratio of magnesium to iron varies from 16: 1 to 2: 1. Commercial olivine deposits contain a mixture of forsterite and fayalite with the fayalite content restricted to less than 15% (Reed, 1959; Teague, 1983). Accessory constituents may include primary minerals such as ilmenite, magnetite, diopside, chromite, and garnet and secondary minerals such as chlorite, serpentine, talc, and vermiculite as alteration products. Chemical and Physical Properties The chemical composition of olivine can be expressed as either (Mg, Fe), SiO, or 2(Mg, Fe)O.SiO,. Table 1 presents chemical analyses for some commercial olivines. The physical properties of olivine are shown in Table 2. Distribution of Major Deposits Commercial olivine and dunite deposits are found in Norway, Japan, Spain, India, Italy, the United States, Sweden, Austria, Pakistan, and Mexico. Noncommercial deposits have been reported in New Zealand, Zimbabwe, South Africa, New Caledonia, Greece, Brazil, and Canada (Teague, 1983). The present markets for olivine are characterized by low unit value, high volume, and high sensitivity to freight costs, so few deposits are commercially viable. Literature from the USSR indicates that considerable research on olivine refractories is being done. (Afansa'ev, 1988), lending credibility to the conjecture that commercial deposits are being mined there. In eastern Canada synthetic olivine is being produced by calcining chrysotile asbestos mine tailings. In the United States numerous lenses of olivine extend in a belt from northeast Georgia northeastward across western North Carolina. Total reserves in North Carolina and Georgia are estimated at between 125 and 200 Mt. The largest US deposit is Twin Sisters Mountain, located in Whatcom and Skagit Counties in the state of Washington. This deposit, which has an outcrop area of 93 km2 and a relief of about 1 525 m. is estimated to contain 1 800 Mt of fresh, unaltered olivine (Teague, 1983). In addition, the US Bureau of Mines reports reserves of 50 Mt on Cypress Island in the state of Washington, and the literature reports eight complexes in southeastern Alaska, some containing cores of olivine as large as 1.6 km in diameter (Taylor, Jr., 1967). The world's largest deposit of olivine occurs in the Aaheim area of Norway, where reserves are estimated at a 2 000 Mt. Several other Norwegian deposits contain as much as 5 Mt each. In Japan the production of ultrabasic rocks is currently about 6 Mtpy, but the bulk of this output is serpentinite. Olivineldunite accounts for only 17% of this production. The major olivine deposit in Japan is located at Horoman Hill on the northern island of Hokkaido. Reserves at this deposit are estimated at 100 Mt (Anon., 1990). Spain is one of the largest producers of dunite. Reserves in the La Coruna District in northwestern Spain are estimated at 100 Mt. India, also a major dunite producer, has a large deposit at Salem in Tamil Nadu. In Italy olivine/dunite is mined from a deposit near Turin. In Sweden the largest deposit is at Arutats and is reported to be comparable in size to the Twin Sisters deposit in the United States. At present the only production in Sweden is from a deposit 30 km south of the town of Gallivare. Reserves at this deposit are reported to be between 1 and 2 Mt. Other significant deposits are: 1) in Austria at St. Stefan near Leoben, 2) in the Swat District of the North West Frontier Province in Pakistan, and 3) in Mexico at Cuidad Victoria in Tamaulipas (Anon., 1990).

Jan 1, 1994

By Serge Payant, Michael G. Li, Lionel J. J. Catalan

Alkaline solution rinsing for decommissioning of an acid-leached residue was evaluated by column experiments, neutralization tests and solid characterization by XRD and SEM. It was found that consumption of a strong alkali during residue neutralization was much greater than that required to neutralize the soluble acidity. The excess alkalinity was consumed by solid-phase conversions unnecessary for the success of decommissioning. Alkaline rinsing did not reduce the time requirement for decommissioning when compared with plain water rinsing. Since no benefit is gained to compensate for the additional costs associated with excess alkali consumption, we conclude that strong alkaline solution rinsing is in fact inferior to simple water rinsing.

Jan 1, 1998

By G. Norman Owen, Roger E. Scholl, Tor L. Brekke

INTRODUCTION Underground structures are generally regarded to be safer than surface structures during strong seismic motion, except when crossing a causative fault. Recent studies of observed earthquake damage to tunnels generally support this view, although instances of severe damage and, occasionally, collapse are reported. For proposed underground construction of sensitive structures such as nuclear power plants, liquefied natural gas facilities, and nuclear waste repositories, a verification of the seismic response of underground structures will be required.. This paper discusses the stabilization recommendations used in a study of additional costs required to protect tunnels against ground motion caused by earthquakes and underground nuclear explosions (1). The study is a part of the site investigations for possible construction of a nuclear waste repository. The additional costs estimated in the study are not presented here; only the stabilization measures are presented in the present paper. The tunnels, which would constitute the underground facilities of a possible repository, are assumed to be 5.5 m (18 ft) in diameter and to be located at a depth of 600 m (2,000 ft). Three candidate geological materials are considered: argillite (shale), granite, and tuff. Several peak ground accelerations are used: 0.3g, 0.5g, and 0.7g for earthquakes, and 0.5g, 0.7g, and 1.0g for underground nuclear explosions. Potential damage due only to shaking is considered here. This paper does not discuss problems that result from creep or sudden rupture of intersected faults or from ground failures at portals.

Jan 1, 1979

Africa is rich in natural resources, much of which remain untapped. Despite that, international mining companies have largely stayed away from the continent due to political instability in many countries, lack of infrastructure and the inability to gain control of mineral deposits. Today, optimism is growing concerning African mining. Many of its nations are moving toward privatization of their mining industries. They see it as a way to improve the lives of their populations and become politically stronger. Ministers from 22 African nations were Denver, CO in June for the World Bank's Multilateral Investment Guarantee Agency's Fourth Annual African Mining Investment Symposium. The three-day symposium drew more than 400 mining executives and government representatives. Foreign mining investment in Africa is on the increase. In 1996, international mining companies spent about $418 million on exploration. That is more than double the $190 million spent in 1994. Mining executives say the mining climate in Africa is improving because countries are privatizing the industry and rewriting mining laws that encourage natural resource development. They estimate that private mining firms now control about 80% of mining today. Mine development will help lift the living standards for Africans, the ministers said. The average income for ordinary Africans is about $500 a year. If this new mining boom continues, citizens of nearly all African nations will reap the benefits of better infrastructure and government services, as well as more higher paying jobs, the ministers said. They also issued a word of caution to mining companies attempting to join in the African boom. Concerns are being raised about the treatment of villagers and the environment. In the past, foreign companies would "behave about like colonial masters," said Gerald Ssendaula, natural resource minister for Uganda. Africa is in a different position now, he said. "Now we are solving our own problems." Mining companies must respect local communities or risk creating unrest that will threaten fragile new governments, said Akolang Tombale, chief geologist for Botswana. On the other hand, he said villagers must accept that mining development will benefit them. "They feel these are their natural resources. There must be a mutual interaction between the companies and the people."

Jan 1, 1997

By John L. Shafer

Often an in situ leach is the only practical economic method for copper recovery from small low grade oxide deposits. The decision to develop a copper property by an in-situ blast and leach is strongly dependent on ore grade, tonnage, hydrology, and the copper extraction and acid consumption rates. The inherent "leachability" of the ore will in part determine the desired amount of fracturing of the ore deposit by the blast in order to obtain a copper extraction rate that is economical. For the last several years Occidental Research Corporation (ORC), the corporate R&D for Occidental Petroleum has under-taken a modest effort to address the question of "how to best identify and determine the information necessary to predict and control the operation of an in-situ leach for the economic recovery of copper."

Jan 1, 1977

By Christopher Hebert, Michael R. King, Mehdi Ghazi

The Inland Feeder project is a critical component of Southern California’s water delivery system, relying on a strategic plan of water transfer and storage to enable the delivery of an additional 650 million gallons of water a day. The Arrowhead West and Arrowhead East tunnels form part of this system, comprising the construction of nearly13 km (8 miles) of bored tunnel under the San Bernardino National Forest. This paper describes the design and manufacture of the 4.88 m (16 ft) diameter precast segmental primary lining that will be used in these tunnels to resist rock loads, and up to 275 m (900 ft) of external hydrostatic head.

Jan 1, 2003

By S. R. Wardwell, M. J. Robison

INTRODUCTION The first phase of the Los Angeles Metro Rail Project consists of 7.1 km of subway and stations running through downtown Los Angeles from Union Station to MacArthur Park. Contract A146, Tunnels from 5th/HILL Station to 7th/Flower Station, involves tunnel construction through the heart of downtown Los Angeles. The alignment of the tunnels passes beneath twelve buildings, ranging from a 3-story below grade parking structure to numerous 12 to 14 story buildings. The soil along the alignment is alluvium, consisting of silts and clays, clean sands and gravels located above the ground water table. Because of unstable ground conditions, which led to excessive ground losses in several instances, and because of the potential for excessive building settlements, it became necessary to design and perform a program of chemical grouting. The chemical grouting program was designed such that tunneling could proceed on a one shift per day basis, with chemical grounting being performed on the remaining two shifts. Each day 21,000 to 31,000 liters of sodium silicate grout were injected through sleeveport grout pipes installed 18 m deep through the tunnel face. Tunnel advance rates of 12 m per day, 60 m per week, under full chemical grout cover were achieved. The chemical grouting program virtually eliminated both ground loss and settlement and permitted successful excavation of the tunnels. The purpose of this paper is to describe the chemical grouting program used to control ground losses and settlement on Los Angeles Metro Rail Contract A146. The paper begins with a description of

Jan 1, 1991

By I. Kapageridis

The mining industry worldwide has recognized in the past the need to apply specific rules and guidelines in the reporting of mineral resources and reserves. The high financial investment and risk associated with any mining project and the ever stricter environmental and social controls were the forces behind this recognition. For years the industry experienced the development and enforcement of several codes for reporting accepted by different countries. The implementation of any code can be a confusing task as the guidelines are sometimes general and open to different interpretation. The use of computers in the estimation and reporting of mineral resources and reserves is necessary, particularly when trying to implement particular code guidelines. This paper discusses ways to implement a reporting code in a computerised resource/re-serve estimation study. The implementation is demonstrated using a gold deposit project as an example. The effects of mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors are taken into consideration. This paper also discusses well established reporting codes and the possibility of reaching a single, universally applied code that could be used by Greek mining companies.

Jan 1, 2007

By John Mastoris, Shkurta Gashi, Kostis Dragasakis, Kostas Kouklidis, Halil Berisha

Water is increasingly recognized as a critical issue for sustainable development, becoming as important as carbon to corporate responsibility and reputation. Although the cement industry’s overall ‘water footprint’ is relatively small compared to other sectors, the Cement Sustainability Initiative of the World Business Council for Sustainable Development (WBCSD/CSI) has recognized the importance of water and the need to take actions towards efficient water management, with developing standardizing practices and employing a risk-based assessment approach, mostly at local level where individual facilities and activities can have implications for other water users in the area. Sharrcem, a member of the Titan Cement Group, has made significant investments to upgrade its production facilities, the technological process and apply environmentally friendly technologies. Under this frame, Sharrcem implemented a project for the construction of a Waste Water Treatment Plant (WWTP) in the Cement Plant facilities, which has been successfully operating since early 2016. This paper discusses the technology applied at the new WWTP and the results achieved already, with significant improvement in the quality of the treated water, as compared to the previous situation where untreated wastewater was directly discharged to the nearby Dimce Stream. The WWTP project is a major investment of Sharrcem that aims to improve the quality of the discharged water effluents and thus prevent potential river pollution and overall protect the environment and the health of Sharrcem employees and local community. The WWTP operates with the Sequencing Batch Reactors (SBR) technology, is fully automated and has been also connected with few households of the neighboring community to treat also their sewage water. The plant can be expanded in the future – to connect with additional households - without increasing the size of the treatment tanks. One of the benefits of this project is that by removing a variety of contaminants from water it becomes usable again, depending on the nature of the contaminants and the end use of the water treated. According to the monitoring results the treated water that comes out of the WWTP fully meets quality requirements according to the EU and local limit values standards

Jan 1, 2017