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By Levent Ozdemir, Bjorn Nilsen

For several recent TBM tunnel projects, unexpected ground conditions have been encountered, causing extra cost, considerable delay, and in some cases major claims. Undoubtedly, insufficient and/or irrelevant site investigation and testing are among the main causes of such incidents. The purpose of this paper is to review the main investigations and tests relevant for hard rock TBM projects, with particular emphasis on the considerable development that has taken place over the last few years. Also, guidelines for defining optimum scope and extent of site investigations and testing are discussed, as well as the importance of adjusting the investigations and tests according to complexity of the ground conditions and project type.

Jan 1, 1999

By Raquel Costa, Aldino Campos, Frederico Carvalho Dias, Pedro Madureira, Patrícia Conceição, Ana Filipa Marques, Andreia Afonso, Maria Ana Martins, António Calado, Luísa Pinto Ribeiro

Since its formation in 2004, the Task Group for the Extension of the Continental Shelf (EMEPC) has been collecting hydrographic, geological and geophysical data to support the extension of the continental shelf beyond 200 NM. In 2008, the EMEPC acquired a 6,000 m rated ROV named "Luso" and has been cooperating with several national and international institutions to increase and improve its operational capabilities to conduct research on deep-sea minerals. The Portuguese continental shelf corresponds to a broad area of the seafloor encompassing different physiographic domains: the mid-Atlantic ridge system, abyssal plains and numerous seamounts. From 2008 to the present, the mid- Atlantic ridge and seamounts have been the most visited sites with the ROV "Luso". Several hydrothermal vent sites are known to occur along the mid-Atlantic ridge to the south of the Azores archipelago and mostly within the Portuguese EEZ. Vent fields were also discovered in the extended continental shelf, namely the Rainbow and the Moytirra sites located to south and to the north of the Azores archipelago, respectively. The most studied seamounts correspond to those forming the Great Meteor chain and the Madeira- Tore rise. All these visited sites are related either with the occurrence of polymetallic sulphides or cobalt rich Fe-Mn crusts and the opportunities to further pursue their exploration will be discussed.

Sep 1, 2014

By Earl L. Rau

At the present time, whether an electric utility uses high-sulfur coal is largely determined by geographical location, clean air legislation, and the age of the power plant. Acid rain legislation may well be the new force to change the use of high-sulfur coal. A number of coal papers were presented at the SME Fall Meeting in St. Louis, MO, Sept. 1986. These papers discussed high-sulfur coal in relation to its economics, trends and prospects, value of cleaned coal, and coal-cleaning technology. The Clean Air Act of 1970 required the reduction of SO, emissions from most stationary electric-generating plant to 0.5 kg (1.2 lbs) SO2, per million Btu of heat input. It was possible for many plants to utilize lower-sulfur coal or a mixture of high-sulfur and low-sulfur coal to meet this emission requirement. This 1970 act greatly increased the use of low-sulfur western coal. The 1978 amendment to the Clean Air Act required all new plants to use Flue Gas Desulfurization (FGD) to meet a requirement of 70% reduction of potential SO2 emissions to 0.3 kg (0.6 lb) SO2 per million Btu of heat input. With the requirement to use FGD, there was little or no demand for low-sulfur western coal in new eastern power plants. If' new acid rain legislation is enacted, it likely will require sizeable reductions in SO2, emissions by existing coal users. There might then be a shift to greater use of low-sulfur coals. The low-sulfur coals could come from either western or eastern mines or from cleaned eastern coals. Economics will dictate the approach older power plants will take to meet new regulationsuse FGD or low-sulfur coal. Coal use for electric power generation has changed from 1970 to 1985. Table 1, (Land, preprint 86-333) shows the change. The table shows that in 1985, US utilities used about 255 Mt (280 million st) of high-sulfur coal. Some 45 to 54 Mt (50 to 60 million st) of high-sulfur coal is being used in plants equipped with FGD and most of this use is in eastern states. This leaves 200 to 209 Mt/a (220 to 230 million st) of high-sulfur coal being used without FGD treatment. These plants are at risk if acid rain legislation is passed. Most of these plants are in the east and are more difficult to supply with low-sulfur coal. Estimates range from $20 to $30 billion capital investment and from $5 to $9 billion dollars per year operating costs to reduce SO2, emissions from those old medium-to-high-sulfur coal-burning plants. G. W. Land, (preprint 86-333), also presents tables relating to power generating costs and coal types. The author's tables are extracted from Land's tables IV and V. Table 2 here presents costs for a new plant. This includes the impact of different heat rates, fuel costs, fuel qualities, operating and maintenance costs, labor costs, and waste disposal costs. Table 3 compares estimated costs to retrofit an older plant with a limestone scrubber versus switching the same plant to low-sulfur eastern or western coal. Costs of switching include upgrading the electrostatic precipitator and - with western coal - costs of derating. Bhagwat, (preprint 86-325), details the trends in high-sulfur coal markets from 1974 to 1984. He also gives some prospects for high-sulfur coal markets, 1984 to 1994. The prospect depends mostly on whether acid rain legislation is enacted. By 1994, if New Source Performance Standards (NSPS) continue to be applied, high-sulfur coal demand from six mid-west and eastern states is expected to increase by 27 Mt (30 million st). • L. A. Khan and J. W. Baxter, (preprint 86-373), discuss several coal cleaning technologies such as froth flotation of fines, bulk oil separation and oil agglomeration, oil agglomeration/flotation, and air-floc flotation. ? (Space limitations preclude listing references. A complete list is available from the author.)

Jan 1, 1987

By Paul D. Tomlingson

World class performance is the ultimate objective of many maintenance organizations. It marks the organization as a leader in its industry and sets it apart as the ultimate achiever. But what is a “world class” standard and how can it be achieved? Is there a yardstick by which an industrial organization can measure the relative performance of its maintenance activity and compare it with performance levels that universally identify “world class” status? Are there financial formulas, achievements, evaluation techniques or indices that provide this yardstick?

Jan 1, 2006

By G. J. Joy

Although rates of pneumoconiosis in coal miners have declined substantially in the United States since the passage of the Federal Coal Mine Health and Safety Act of 1969, new cases continue to occur, including cases of rapidly progressive disease. In contrast, Australia?s underground coal mining industry has reported few new cases of pneumoconiosis for over twenty years. Mortality from Coal Workers? Pneumoconiosis in official health statistics and the prevalence of pneumoconiosis among miners screened in x-ray surveillance programs are also lower in Australia. To understand this disparity, the National Institute for Occupational Safety and Health was requested by both industry and labor stakeholders to examine this issue, with the ultimate aim of reducing the rate of pneumoconiosis among United States coal miners. A number of factors, including coal dust exposure, silica exposure, and coal rank were examined as potential contributors to the above observed differences. Comparison of coal rank data from each country did not show any significant differences. Air sample data from the coal mining industries in both countries show that coal dust levels in Australian mines are somewhat higher than those reported in similar U.S. mines; however, quartz exposure for Australian miners is lower than for many U.S. miners. Assuming that quartz is contributing to the greater number of cases of advanced pneumoconiosis in the U.S., more effective dust control measures, as well an independent exposure standard for respirable quartz in coal mining, need to be implemented to prevent this potentially disabling condition.

Jan 1, 2011

By G. Delagrammatikas, M. Karmis, J. Mastoris

The evaluation of raw materials in terms of quality profile, mineralogical character and mechanical properties is of great importance to the cement industry. The variability of their chemistry and structure is among the decisive design parameters in the choice of any mining, handling and preblending systems. Furthermore, clinker and cement production require sound estimates of the above parameters, to help produce some appropriate and realistic raw mix configurations and achieve minimum standard deviation of the major components. This paper addresses this subject from the perspective of a cement producer and presents the principles of a methodology aimed at optimizing mine planning and process design. Finally, results from case studies on actual sedimentary deposits currently in operation are discussed.

Jan 1, 2002

By R. E. Ray

In an effort to reduce the risks to underground miners of health hazards associated with exposure to high concentrations of diesel particulate matter(dpm), the Mine Safety and Health Administration(MSHA) published proposed rules in 1998 limiting dpm exposure in both underground coal and metal and nonmetal mines. The proposed rule for underground coal mines would require removal of 95% of dpm by mass, while the rule for metal and nonmetal mines would eventually limit total carbon exposure from dpm to 160 micrograms per cubic meter of air over an eight-hour shift. The comment period for both proposed standards ended on July 26, 1999.In this session, representatives from MSHA, the National Institute for Occupational Safety and Health (NIOSH), equipment manufacturers, labor and industry will discuss the impact of the proposed regulations on mine operations and worker health. Questions will be taken from the audience after brief presentations from each panelist. This paper provides a compilation of written summaries of each panelist’s opening presentation.

Jan 1, 2000

By M. C. Roberts

Currently, mineral producers are suffering through a major downturn in prices for their products, even though it has only been a few years since they were enjoying high prices. From an historical perspective, the current situation is another of the cyclical down-turns that often reoccur every 5 to 7 years or so. This paper uses time trend decomposition techniques to identify the cycles and statistical methods to find the duration of these cycles for a variety of mineral prices. Given some idea of how long and severe these cycles typically are, the mining industry can better plan to weather the downturns and take advantage of the upturns. For example, timing investments in new projects to take advantage of the cyclical upturns can dramatically improve project profitability.

Jan 1, 2000

By Jack E. Bailey

From a start in 1957, milling 3,000 TPD of copper ore, the Cyprus Pima Mining Company, which is located 20 miles south of Tucson, has expanded its operations four times, and is currently treating over 55,000 TPD of ore.1 The most recent expansion added a 14,000 TPD semi-autogenous concentrator to the operation. Shortly after startup in January, 1972, the semi -autogenous plant exceeded the designed tonnage rate.2 Ore from the mine is delivered to a 54 inch gyratory crusher and is reduced to a minus 8 inch product. From the crusher the ore is stacked on a surge pile and then reclaimed and fed to the two parallel grinding circuits. A 28 ft. diameter by 12 ft. long semi-autogenous mill and a 16.5 ft. diameter by 19 ft. long ball mill make up each grinding circuit. The semi-autogenous mills are in closed circuit with screens and the ball mill circuits are closed with hydro- cyclones. Rougher flotation follows the grinding operation. Concentrate regrinding and cleaner flotation is performed in Mill I, the older mill. The generalized flowsheet is shown in Figure 1.

Jan 1, 1975

By D. E. Cameron

"INTRODUCTION Grade control requirements for base and precious metal projects are an important input to both conceptual and feasibility mine plans. It’s the author’s experience that grade control input is insufficient at these critical stages. The few exceptions are a stimulus for this paper. A significant portion of CRC’s practice has involved assisting operations to solve grade control issues which were finally recognized as contributing to negative production variances. Even in operations perceived to be successful, deficiencies in grade control are often masked by measures taken by an operation to compensate a deficiency in one area with outperformance in another. The advantages in having a realistic and adequate grade control plan developed at an early project stage by a geologist(s) with considerable operations experience are manifold. It’s important for the geologist to prepare clear inputs into the mine plan backed by detailed supporting information in usable, flexible formats. When the decision is made to advance a project, the exploration team passes its model to a mine planner. The team doesn’t usually provide a detailed grade control plan with the block model, thus the planner tends to treat grade control as an activity to be rolled into a broader operating category. The consequences of highly compartmentalized mine planning can be severe in the long run. Once a plan is tabled, and especially once production begins, it is very difficult to improve grade control outside the fixed parameters of the operation. Major fixes tend to be costly in terms of time and dollars. Implementing needed changes to the grade control practices and culture in an established mine can present almost insurmountable difficulties. Hypothetical examples of grade control planning are presented to illustrate the author’s points. The diagrams are conceptual and schematic; any resemblance to actual deposits is coincidental. BEYOND 50¢/TON In more than a few cases, grade control cost is buried in a subcategory of mining cost with little more consideration than a plugged number. It is possible to do a word search in 43-101 Technical Reports on advanced projects and without finding reference to “ore control” or “grade control”. The idea is to reach the orebody by the shortest and least expensive means, achieving production and investor payback at the earliest possible occasion. This entails a low stripping ratio pit or a decline ramp with sills on ore to prepare the first stopes. The processes to achieve the target production, one of which is grade control, will fit into this framework. After all, there is a block model and the planner can see the grade and tons in each block. The exploration geologist whose responsibility was to bring a large percentage of the deposit into mineral resource owns the model and has released it to planning. Now comes the planning stage. Mine geologists haven’t been hired yet and they will be phased in with production. What could go wrong? Larger companies may have the geologists with operating depth who will be inserted into the mine planning discussions, but it’s not a given. Junior companies must often delegate the conceptual and detailed planning tasks to consultant groups. Is a senior-level grade control review part of the scope of work for the mine planning? If a good grade control plan is in place before the mine geology team is staffed, a key element of success is assured."

Jan 1, 2018

By K. T. Lee, M. U. Ozbay, M. D. G. Salamon

Design of yielding chain pillars in deep coal longwall mines is not as well established due mainly to the lack of knowledge in the behavior of coal pillars in the post-peak regime. This study shows that two of the existing strain-softening models have the potential to provide an improved understanding of yielding and, therefore, could form a rational basis for yielding coal pillar design. Analytic and numerical modelings of a row of chain pillars in a two-entry development at a depth of nearly 700 m suggests that yielding pillars are feasible, but the design is very sensitive to the coal’s post-peak behavior.

Jan 1, 2001

By R. L. Virta

Four companies mined ball clay in four States during2004. They were H.C. Spinks Clay (owned by Franklin Minerals) Kentucky-Tennessee Clay (owned by Imerys),Old Hickory Clay and Unimin. Production was estimated to be 1.46 Mt (1.61 million st) valued at about $56.9 million, based on a preliminary survey of the ball clay industry. In 2003, production was 1.31 Mt (1.44 million st) valued at $56.2 million. Tennessee was the leading producer state with 61 percent of production. It was followed by Texas, Kentucky and Mississippi.

Jan 1, 2005

By Maurice Grieves

GC. Waterman Mr. Grieves' paper on "Shaft Sinking Today--A Boring Business Tomorrow" in the Dec. 1981 issue of MINING ENGINEERING is an excellent description of recent improvements in speed and costs of shaft sinking. However, shaft boring techniques are not a recent development. In 1935-36, the Idaho Maryland Co. (gold), Grass Valley, CA, bored the vertical 1.5-m-diam Idaho No. 2 ventilation and supply shaft to a depth of 346 m. The equipment was designed and perfected by Branner Newsome and was, I believe, described in "Transactions." Pickands Mather later bored a 1.8-m-diam shaft to a depth of about 305 m using Newsome's design. The Idaho No. 2 shaft cut through hard gabbro, diabase dikes, soft serpentine, very incompetent ankeritized serpentine and a strong fault zone. The completed shaft did not require timber support; the fault zone was cemented. Equipment consisted of a rotating 1.5-m or 3-m core barrel with a slotted bottom which cut a 76-mm kerf. The cutting agent was chilled steel shot introduced into the slot as needed. The driving mechanism and core barrel were lowered into the shaft, the former secured to the wall and the inshaft "engineer" operated the motors which controlled core barrel rpm and advance. After an advance of 1.5-3 m the equipment was lifted out of the shaft, a half(?) stick of powder cut off the drilled core, and it was hoisted to the surface with a cable attached to an eye bolt at the tope of the core. A "shift" consisted of three men: hoistman, equipment operator (down the shaft), and a surface laborer. Advance was variable as equipment and techniques were perfected. Near the end of the job advance was, as I remember, 1.5-3 m per shift. Costs were, as I recall, about $115/m. Up to 4 m cores were lifted out in one piece and swung to the dump by a stiff leg derrick. The Newsome equipment was relatively inexpensive to build and operate and his method should be (more than?) competetive with the methods described by Grieves. W.E. Hawes The author, in mentioning the South African developments of the cactus grab, ignores the parallel development of the Cryderman mucker in this hemisphere. Perhaps a slightly longer history of blind hold drilling would have been in order. Blind shaft boring got a major boost at the Nevada Test Site, as part of the nuclear weapons development, when it was essential to be able to quickly assess depth for weapons testing. One of the early civilian attempts to utilize this technology occurred when Kerr McGee drilled the shaft at the Section 19 Mine at Ambrosia Lake, NM. This twin masted drill rig belonged to a subsidiary of Kerr McGee, not Shaft Drillers. This was a difficult hole, due to bentonitic shales that decomposed. Later advances in drilling fluids eliminated this problem. The Conoco project referred to is not entirely correct, and needs minor amplification: The depth of the development (not pilot) shaft drilled was 684 m, at a diameter of 3.05 m, with a 2.16 m ID hydratatic casing being installed to a depth of 669 m. Conoco Inc., not Challenger, executed the drilling, however Conoco did use Challenger Drilling Company's Rig 14-S. Rig 14-S is unique in that it is specifically designed for shaft drilling, rather than being an oil field rig used for this service. All work was planned and directed by Conoco personnel. Deviation of the aforementioned shaft from vertical was 31 cm. Two smaller shafts (pilot shafts) were drilled with the same rig. These smaller ones were drilled 1.8 m in diameter, to depth of 665 m and cased with .91-m-diam casing, to depth of 650 m to be used as pilot holes for 5.5 m diameter shafts. The total elapsed time for all drilling, casing, cementing, and rig moves was 50 weeks. The constraints mentioned of vertical accuracy, torque, wall collapse, rig set up time, lining time etc., pumping out, etc., may not be as serious as the author implies. First, vertical accuracy: The record achieved by Conoco indicates that with reasonable care, good accuracy can be obtained, primarily by having a fair amount of weight in tension, rather than on the drill bit. Second, the amount of torque that can be applied to the drill stem has been greatly increased by the introduction of larger diameter drill stems, such as the new Hughes rig uses. Third, risk of collapse of shaft walls is minimal with the proper mud program. Basically, the walls are supported by the weight of the mud and it is not removed until some type of casing is installed and grouted in. Here in the real challenge of blind drilling shafts to devise a more economical method of lining bored shafts than using steel casing. The remaining issues were minor at Conoco, provided adequate planning and scheduling takes place. An excellent paper, "Shaft Drilling--Crownpoint Project" by Hassell H. Hunter, presented at the Fifth Uranium Symposium in Albuquerque in Sept. 1981 contains details of this project. A combination of blind boring, with enlargement by either mechanical means (boring machine, or tunneling type shield) or slabbing down, with muck removal through a larger bored shaft would seem to be the future trend in shaft development. The economics, especially for wet conditions, favor this concept over conventional sinking, as has been demonstrated at Kerr McGee --Churchrock, UNC--Churchrock and Conoco at Crownpoint.

Jan 3, 1983

By John D. Morgan

The United States is the world's most productive nation and its citizens enjoy one of the highest material standards of living of any people in the world. Materials and energy are the lifeblood of any industrialized economy. Annually the United States uses over 4 billion tons of mineral materials and fuels, or 40,000 pounds per person as detailed in Figure 1. Domestic processed materials of mineral origin and energy are valued at more than $150 billion annually, and they are derived largely from domestic sources, supplemented by imports, as detailed in Figure 2. In recent years the superior productivity of the United States has also enabled it to give food and manufactured articles to many other less fortunate nations and peoples of the earth. What then is our concern with materials at this time? Seeing the burgeoning increases in our mineral demand: from 2 billion tons in 1950, to over 4 billion tons today, and projected to 11 billion tons by 2000 - we are getting questions concerning our ability to continue to increase production sufficiently for the future.

Jan 1, 1974

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

Jan 1, 2007

By C. Chamberlain

The mining industry continues to underpin the regional economy. Australia, benefiting from a weak currency, receives 27% of the total goods export value from non-energy mining lead by aluminium, iron ore, gold and nickel. Consolidation has eliminated CRA, Comalco, North, Savage, Acacia, Ashton, Great Central, Aberfoyle, Placer Pacific, Plutonic, Normandy and RGC leaving Rio Tinto, BHP-Billiton, WMC, MIM and, increasingly, the South African companies Anglo, Gold Fields and Harmony as dominant players. Exploration stagnates with expenditure dropping 40% in Australia and 80% in PNG from peak levels. Major new regional developments include Rio’s West Angles iron ore project, Newcrest’s Ridgeway gold-copper mine and Inco’s Goro nickel-cobalt project in New Caledonia.

Jan 1, 2002

By F. B. Henderson

1.0 PROLOG Since the "end" of the Cold War, revolutionary new research and commercial remote sensing capabilities are being developed that will dramatically change the way we map the earth and address its environmental problems. The technology challenge is not the growth of new environmental remote sensing technologies themselves. It is, rather, how these new innovative observing systems can be accepted and used to the benefit of both the regulatory and the mining communities in the light of present concerns about unknown risks of discovery and liability. The basis for this paper is an unpublished technology primer prepared for the industry-government Workshop on Advanced Measurement and Site Characterization for Mining Impacts held at Colorado School of Mines, Golden, Colorado, July 14-17, 1997

Jan 1, 1999

By T. J. Lien

AMAX Coal Company's Belle Ayr coal dryer is the first industry attempt to commercialize sub-bituminous coal drying which has been the subject of laboratory and pilot plant tests for almost two decades. This paper presents the historical background, construction, start-up and operation of this adaption of fluidized bed coal drying technology to Powder River Basin coal. The flowsheet and operational problems encountered during plant start-up are discussed together with general material balance and product quality.

Jan 1, 1990

By Herbert H. Einstein

Swelling ground is one of the most feared problem in tunneling. Although usually not causing sudden failures during construction, the very large and long- lasting deformations give contractors and designers the impression of facing an inevitable phenomenon against which there is no technical defense. Examples are concrete liners of up to 1 m that have been cracked or crushed, tunnel inverts that are heaving at a rate of 0.1 m per week during construction and continue to heave during decades. This author (Einstein (1979). Einstein et al. (1972) (1975)) and others (Huller (19761, Grob (1972) (1976). Golta (1967), tienke (19761, Krause (1976). Lee et al. (1976)) have described many cases of swelling tunnels that illustrate the significance and magnitude of the problem. This paper intends to show that tunnels in swelling rock can be built to perform satisfactorily. . For this purpose the tunnel builder needs to know how to determine the existence and specific behavior of swelling ground, how to select appropriate structural characteristics of the tunnel and predict its performance under the specific ground conditions, and finally how to construct the tunnel such that the anticipated performance will be achieved. This concept of a design-construction procedure is the same as that for tunneling in general; it is mentioned here for NO reasons: 1. To point out that design and construction cannot and should not be separated. The way in which the tunnel will be built has to be an integral part of the design. 2. This paper will be structured corresponding to the procedural concept.

Jan 1, 1981

By G. C. Hall, B. E. Hobbs

Giant gold deposits are considered products of crustal-scale systems. Reduced fluids stored in mid to lower crustal reservoirs were discharged into mid to upper crustal sites of deposition. Elements of the architecture include crustal-scale structures, reduced packages of rock and regional seals. Gas-rich aqueous fluids were common but non-aqueous fluids may have been significant in the deeper parts of the systems. Fluid fluxes in over pressured domains were maintained by porosity waves. Abnormal heat input from the mantle may not be required once the systems were perturbed. Fluid-mixing and hypogene enrichment were probably the most significant precipitation processes.

Jan 1, 1999