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By David Crouthamel, Raymond Henn

"The need to fill the void space or annulus created between an excavated tunnel or shaft and the final lining system has long been a requirement in underground construction. Most of those types of voids are created as a result of employing the two pass tunneling lining method. Filling of this void is called backfilling. For many years the materials used as backfill were primarily reinforced and non-reinforced concrete, sanded grout, neat cement grout, or blown-in sand/pea gravel. However, in the past 20 years the use of cellular grouts/cellular concrete as the backfill material has greatly increased. Most cellular grout is made of a mixture of water, Portland cement (with or without the addition of fly ash), a foaming agent and admixtures such as a water-reducer or superplasticizer.It is the authors’ preference to use the term cellular grout as opposed to cellular concrete since by ACI Concrete Terminology an ACI Standard (ACI CT 13), concrete contains aggregates. Normally cellular grout does not contain sand (finite aggregate), but almost never contain course aggregates.The authors believe there are several reasons for this increased use of cellular grout as backfill, such as:• The increase utilization of the various trenchless tunneling methods. Tunnels constructed using trenchless method tend to be smaller in size, excavated diameter or cross sectional area. Making man-entry for placing backfill from inside the secondary liner, utilizing pre-installed grout posts, more difficult if not impossible. It is these workspace restrictions that are the drivers as to when to utilize grout ports installed during the pipe/liner fabrication versus grout delivery pipes installed within the void/annulus space.• The ability of cellular backfills to be pumped and flow longer distances.• The unit weight of cellular grouts can be controlled by mix design and generally can range from 560 Kg/m3 (35 lbs/CF) to 1040 Kg/m3 (65 lbs/CF)."

Jan 12, 2017

By George R. Schottler

The objective of this research is to find the extent of the range of applicability of previously developed statistical methods for determining grade and tonnage of ore to bedded uranium deposits. Uranium assays obtained from gamma-ray logs of exploratory drill holes are used to compute grade and tonnage of ore in the deposit by a standard polygonal method and by statistical analysis. The results obtained by the two methods are compared. The uranium-assay frequency distributions are shown to be lognormal and a simple transformation permits the use of standard normal curve statistics. The effects on the assay frequency distributions of stratified sampling, a required minimum mining thickness, and increased assay-interval length are investigated. The addition of low-grade mineralization to make up the required minimum mining thickness results in a distinct change in the skewness of the assay frequency distribution. Any statistical inference regarding grade-tonnage relationships that will be produced, using the minimum mining thickness, should be made on the basis of this "revised" assay frequency distribution.

Jan 1, 1965

By B. C. Parks

This paper is a report on the relationships between petrographic composition, chemical composition, physical properties, and thermal behavior of banded bituminous coal. It describes the relationships between petrographic composition, behavior in various laboratory tests, and carbonizing properties of different petrographic types of coal that occur in relatively thick benches in a single bed of high-volatile A bituminous coal - the Hernshaw bed of Boone County, W. Va. Thin-section microscopic analysis and free-swelling index determinations of the thin-section samples were made of a standard column sample. A standard face sample, a representative channel sample, and representative samples of two prominent petrographic benches of bright and dull coal were subjected to chemical analyses and free-swelling-index, plasticity, dilation, agglutinating, low-temperature carbonization, and BM-AGA retort tests. A float-and-sink separation was also made of part of the standard face sample. The fractions from this gravity separation were subjected to petrographic and chemical analysis and free-swelling-index, plasticity, and dilatation tests.

Jan 1, 1959

By W. J. Mcgaughey

A crosshole seismic imaging (tomography) experiment has been carried out in an underground mine in order to delineate waste rock within a massive sulphide ore body. Data comprising 1526 travel time measurements were inverted to yield a compressional wave speed image consistent with, and adding to, knowledge of the extent of the waste inclusions. An effective method of resolving travel time discrepancies measured on reversed ray paths is presented.

Jan 1, 1989

By Robert B. Hopler

The hazards which naturally prevail in underground coal mines, always severe and unpredictable due to the loosely-consolidated strata in which coal is frequently found, are increased by the commonly-occurring combination of coal dust, methane, and explosives. It was recognized by the mid-nineteenth century that coal dust was the basic factor contributing to disastrous explosions killing hundreds of miners, and that the ignition of methane gas was often the source of the coal dust explosions. It was apparent that preventing the ignition of methane was a critical part of avoiding these disasters, and it was also apparent that one cause of such ignitions was the firing of explosives. In addition, it was found that dust explosions were often initiated by blown-out shots of explosives in the absence of methane.

Jan 1, 1996

By James S. Goff, Stephen J. Navin, Wesley W. Moulton

The White River Shale Oil Corporation (WRSOC), as agent for Phillips Petroleum Company, Sohio Shale Oil Company, and Sun Shale Oil Company, is developing a prototype oil shale facility on Federal Lease Tracts Ua and Ub, located in northeastern Utah and known as the White River Shale Project (WRSP). The Ralph M. Parsons Company (Parsons) has been retained as the design engineer/constructor for the project. This paper covers the successful pregrouting of the Bird's Nest Aquifer in conjunction with the sinking of a 9.2-m (30-ft)-diameter shaft and driving of a 3.89-m by 5.64-m (18.5-ft by 12.75-ft) decline. The Bird's Nest Aquifer derives its name from the ellipsidal solution cavities caused by leaching of random-size nacholite nodules. The sodium bicarbonate nodules occur as persistent bands within a matrix of siltstone and marlstone. The team, made up of the owner, engineer/contractor, and subcontractor successfully grouted the shaft down to an inflow of less than 0.06 lps (1 gmp) and the decline down to less than 0.12 lps (2 gpm) by injecting a total of 213.190 kg (470,000 lb) of Celtite Terraseal, 113,400 kg (250,000 lb) of limestone dust, and 41,730 kg (92,000 lb) of cement into the formation.

Jan 1, 1985

By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012). This research will be presented in a series of papers, this one and two more that will be published on Mining Engineering?s web site, www.me.smenet.com. This paper identifies the variables associated with risk in mining projects, and their effects. The second paper discusses methods of assessing the overall risk associated with those variables, and presents a statistical model based on a survey of 31 experts. The third paper presents an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved. There are several major competing entities, including BHP Billiton, Rio Tinto, Anglo American, Xstrata, Freeport-McMoRan, Chinese government- run companies and Japanese trading companies, that have large foreign holdings, controlling deposits in most of the world?s established and productive mining districts. In general, the mining industry considers the United States, Canada, Australia and the European countries to have good mining investment environments, but because the major companies have already achieved market dominance in those countries, large investments are required there. Newcomers seeking to enter the industry, either as producing companies or as investing partners, often have difficulty breaking into these established markets. Thus newcomers are increasingly turning to new areas like South America and Africa, which are relatively less developed. The competition among businesses to secure a share of the new market is intense, but there are still good investment opportunities. However, because most of the countries in these areas are not well developed, several additional risks are associated with participation in mining projects in those areas.

Oct 1, 2013

By James Diekmann

The Disputes Potential Index (DPI) is a computer program designed to help team mem¬bers assess the likelihood of contract disputes on a construction project. The program's predictions are based on data from 159 construction projects that encompass a variety of public and private projects. The impact of three categories of project characteristics are included in the DPI program, specifically, people, process and project characteristics. Ultimately, DPI returns an overall project score that indicates the likelihood of exces¬sive contract disputes. The output of a DPI analysis can be used as part of a contract readiness review or to define the need for extraordinary dispute avoidance procedures. This paper examines the development of DPI and presents the results of DPI analyses on several tunneling projects.

Jan 1, 1995

By W. R. Reed, G. W. Luxbacher

Mine worker exposure to respirable coal dust and silica dust can result in coal workers’ pneumoconiosis and silicosis which are occupational respiratory diseases that have no cure and are ultimately fatal. In 2021 the Mine Safety and Health Administration reported just over 11,000 operating metal/nonmetal mines with the potential for silica dust exposure for just under 200,000 miners. The National Institute for Occupational Safety and Health (NIOSH) conducts respirable coal and silica dust research associated with mining through its Office of Mine Safety and Health Research. NIOSH respirable coal and silica dust research began under the U.S. Bureau of Mines (USBM), which initially examined silica dust, progressing to include coal dust, with a stronger focus after 1969 with the passage of the Federal Coal Mine Health and Safety Act. A review of extramural research to develop real-time respirable silica dust monitor is presented along with a brief history of silica dust regulation.

Feb 1, 2024

By Francis X. Cannaday

The purpose of this investigation was to find whether the moduli of elasticity obtained were the same for the following methods : ( 1 ) Deformation of a borehole in a prism subjected to uniaxial stress ; ( 2 ) deflection of a thin beam of uniform cross section uniformly loaded ; ( 3 ) sonic - pulse velocity measurements , and ( 4 ) strain measurements on a prism under uniaxial stress . The rock tested was chosen for its good elastic behavior and relatively good homogeneity and elastic isotropism . The same rock was used for all methods . Results indicate that for given environmental and stress conditions the moduli obtained by each of the four methods check one another within the limits of experimental error and that the differences introduced which are characteristic for each method are smaller than physical variations within the rock tested .

Jan 1, 1964

By J. N. Van der Merwe

"A major shortcoming of the statistical back-analysis of coal pillar strength is that it relies on the asmined pillar dimensions, not taking into account time-related pillar scaling with subsequent reduction in pillar width. The paper describes an investigation where the rate of pillar scaling was applied to the pillars in the databases of failed and unfailed pillars. The reduced pillar sizes were then used in the same method of statistical back-analysis that had been used in the past.This resulted in an equation for pillar strength which predicts significantly greater pillar strength than the previous statistical analyses, which is similar to the strength which had been found earlier by direct testing of large specimens underground. It is concluded that the lower strengths found by previous statistical analyses are due to the incorrect pillar width being used and that by adjusting the pillar sizes to compensate for scaling, more credible results that correspond to direct testing are obtained.As the newly derived strength equation is time-dependent, it follows that the safety factors and probabilities of failure are likewise time-dependant. An equation to determine the probability of failure is also developed. This results in the safety factor being close to unity at a probability of failure of 50%, which is aligned to statistical expectation. IntroductionSince the Coalbrook mine disaster, caused by massive pillar collapse, there have been several attempts at analysing and defining the strength of coal pillars. It was realized in the very beginning that performing classical strength tests on coal specimens in a laboratory and then transferring those results to real coal pillars could not be successful. The scatter of results is one problem and, more seriously, there is a size effect (at least for small specimens) that made the transformation of strength results to much larger coal pillars underground all but impossible.Two main schools of thought then emerged. Some researchers preferred to perform direct strength tests on large specimens underground, while others relied on statistical back-analysis of failed and unfailed pillar cases, attempting to determine the differences in size and shape that would allow a satisfactory prediction of failure. The latter school of thought resulted in the method that was widely accepted by the South African coal mining industry, described in the landmark publication by Salamon and Munro (1967)."

Jul 1, 2019

By G. M. Mason

History Due to its strong affinity for oxygen, aluminium as an element was isolated only after many other rarer metals had been prepared and studied. It was just over one hundred years ago that two scientists, Hans Christian Oersted and Friedrich Wohler, produced the first few pellets of aluminium and determined its physical properties. These early investigators used metallic potassium as a reducing agent. Later, St. Claire Deville, by using sodium instead of potassium, improved the yield in the reduction and produced some pounds of aluminium. From a figure of about $110 per pound in 1855, the price had fallen to about $4 per pound by 1886. In that year, a very important discovery was made independently by Charles Martin Hall in Oberlin , Ohio, and Paul . Heroult in France. Stated in its simplest terms, the discovery of Hall and Heroult was that aluminium could be produced by electrolyzing a solution of the oxide in molten cryolite. The application of the Hall-Heroult process made the metal immediately available in commercial quantities and, by 1900, the price had fallen to 23 cents per pound. The growth of the industry in the past fifty years is well known, and is outside the scope of this paper. It is, perhaps, not generally known that aluminium was first produced in Canada at Shawinigan Falls in 1901. Since that time, production has been continuous at one or more smelters in the Province of Quebec. The largest of these smelters, which is also the largest aluminium smelter in the world, is at Arvida, Quebec, on the Saguenay river. A large power potential and access to ocean shipping were the two principal reasons for the establishment of aluminium production facilities in the Saguenay district. It is interesting to note that the aluminium industry, as a large user of power, took an active part in the early industrial development at Niagara Falls and Shawinigan Falls, and is now repeating the process in the Saguenay valley.

Jan 1, 1949

By J B. Collier, R M. Fraser, O Dahl, I M. Platten

Grade control is a process of maximising value and reducing risk, through the delivery of quality tonnes to the mill via the accurate definition of ore and waste. It essentially comprises data collection, integration and interpretation; local resource estimation; stope design; supervision of mining and stockpile management. The foundation of all grade control programs should be that of geological understanding led by high-quality mapping and sampling to drive appropriate estimation strategies and mining. Gold veins show various complex features relating to erratic grade distribution (nugget effect), variable geometry and internal architecture. These include variations in dip, strike and width, late-stage faulting/shearing effects and geometallurgy. Such variations generally require close geological understanding to ensure optimum grade, minimal dilution and maximum mining recovery. A well designed grade control program will prove to management and stakeholders that by applying geological knowledge, the mining process can be more efficient and cost effective. This paper reviews the issues of grade control in underground gold mines and focuses on integrated mapping and sampling through three case studies.

Jan 1, 2009

By John Gittins

Lots 11 and 12, Range IX, Calumet island, are underlain by a Grenville metamorphic complex into which sills of tourmaline granite pegmatite have been injected. The pegmatite has an average mode-potash feldspar 65 per cent, sodic plagicdase 10 to 20 per cent, quartz 5 to 20 per cent, tourmaline 10 to 15 per cent, accessory minerals < 5 per cent; it is unzoned except for a narrow border zone. Some of the feldspar has been replaced by calcite. Microcline has been ?partially replaced by sodic plagioclase. Three varieties of tourmaline are present (black, blue, and green) and spectrographic analysis suggests progressive compositional changes during its crystallization. The presence of U- and Th-bearing minerals in the pegmatite prompted the Quebec Nickel Cor,porat10n, Ltd., to explore the possibility of developing the pegmatite but it does not appear that this is economically possible at the ? present time. Tt\e Grenville metamorphic complex consists of recrystallized limestones and calcsilicate rocks of the albite-epidoteamphibolite facies and the amphibolite facies, which were derived from sedimentary rocks. Several of these are dis-equilibrium assemblages, and retrograde metamorphism has probably formed biotite and epidote from hornblende. The schistosity of the gneisses dips steeply eastward. Numerous strike faults are roughly parallel to the schistosity and one of the pegmatite sills is bounded by such a fault, dipping at 60 ° with about one foot of fault breccia. The general structure of the map-area seems to be an asymmetrical syncline ?overturned to the west. The emplacement of the pegmatite is associated with a period of folding, metamorphism, and igneous intrusion.

Jan 1, 1956

By F. J. Sotillo

The reduction in energy consumption has been always important for beneficiation plants. Also gravity separation processes have gained lately great importance due to environmental concerns, especially in the gold and silver Industries. In this sense, the paper point out how to reduce the energy consumption in grinding, and increase efficiency in both grinding and gravity separation are of utmost importance to optimize the use of the country’s resources. For these purposes, chemical additives, such as rheology modifiers have shown great potential, and deserved careful consideration.

Sep 9, 2007

On the more important mines it is almost essential to have a general plan of the surface. A special feature of this plan should be the indication thereon of a suitable arrangement of contour lines, either wholly over the surface of the property or at parts where may seem most useful. The importance of having these contours marked on the plan will be best appreciated by the engineer, in selecting the best available site for a proposed new plant, in locating a tramway, in connecting the surface with the underground workings to the best advantage, or in solving many similar problems that come within his province. The closer the contours are together vertically the better, the limitation being the trouble and expense of getting them on to the plan. They may range from five to fifty feet apart but a distance of ten feet will be found, in most cases, to be the most useful.In deciding the datum level from which these contours are to be measured, it is best to depart from the ordinary sea level datum, and use instead the highest available point on the property. This datum will be called zero and all levels will be reckoned so many feet below it; thus by a contour marked 160 on the plan, it will be understood that the level of the plane of the contour is 160 feet below the highest available point on the property. This system of measuring levels downward is readily suggested from measuring the depths of shafts from the brace or of excavations from the original surface.

By Samantha Smith

Nautilus Minerals (Nautilus) is following the lead of the petroleum industry as it strives to tap vast offshore resources. Planning is well underway for the Solwara 1 Project in the Bismarck Sea, Papua New Guinea (PNG) to recover high-grade seafloor massive sulphide deposits in 1600 m water depth. The deposit contains an average copper grade >10 times higher than a typical land-based porphyry copper mine. The high grades combined with a relatively small amount of overburden ensure the Solwara 1 Project will have a significantly smaller physical footprint than its land-based counterparts. Offshore minerals production also has the advantage of minimal social disturbance. Nautilus is dedicated to setting a high environmental and social responsibility standard. Nautilus recognises the importance of transparent and inclusive stakeholder engagement and has taken a proactive approach to involve as many key stakeholders as possible. One of the first steps in the permitting process in PNG is the preparation of the Environmental Inception Report, which describes the project, its envisaged impacts and the proposed studies for the Environmental Impact Assessment (EIA). Local (PNG-based) and international environmental scientists, anthropologists, NGOs and other experts were involved in the definition of studies conducted for the Solwara 1 EIA and a team of world-leading experts was involved with carrying out the studies, culminating in the preparation of the Environmental Impact Statement (EIS). To ensure transparency, collaborating researchers are free to publish their findings. Following its submission, the EIS was made available for public review and public hearings were held at several locations. The EIS has also undergone a rigorous independent review by PNG government-engaged consultants. Outside the permitting process, Nautilus works alongside government officials to carry out ongoing community consultations. Information dissemination and feedback acquisition has also occurred through the Nautilus website and attendance at a number of international conferences, workshops, and meetings. This paper will outline the leading edge approach Nautilus has taken in completing the environmental impact statement for the world?s first deep seafloor copper-gold mine. In addition, this paper will review the permitting process and the government and stakeholder engagement undertaken as part of Nautilus? desire to ?do it right? in this exciting new industry.

Jan 1, 2010

By John E. Good

A new coal boom is under way in western Canada. As recently as the mid-1960&apos;s, the coal industry in western Canada was considered stagnant and, by some people, dying. But Japan&apos;s growing need for coking coal, which became more pronounced in 1966, sparked great interest in western Canadian reserves.&apos; As a result of a rapidly expanding export market and growth in domestic demand, Canadian coal production spurted to 16.6 million tons in 1970. Production in 1965 was 11.5 million tons. Today, about 60 percent of Canada&apos;s output comes from western Canada, but by 1975, 87 percent (23.1 million tons) is expected to come from this area, and 96 percent (68.3 million tons) by 1990. Opening, developing and operating new coal mines to meet the needs of a rapidly expanding market for western Canadian metallurgical coals pose some unique and difficult problems. Covering nearly every aspect of opening properties in remote areas, the problems are met in exploration, transportation, construction, mine operations, coal preparation, manpower and ecology. Paul Weir Company has been involved as coal consultants on various projects in western Canada for some years. In presenting this paper, we make no attempt to present an in-depth or detailed analysis of any one specific situation. Each has, or would have, its own peculiarities or characteristics, both physical and economic. Instead, the objective is to provide for those not intimately

Jan 1, 1972

By A. C. Legg, M. T. Malema

Keywords: Pyrometallurgy, flash, smelting, furnace, nickel, copper, Botswana BCL Limited operates the only Flash Smelting Furnace on the African continent, at Selebi-Phikwe, situated in north-eastern Botswana. The furnace was commissioned in 1973 and produces a high-grade sulphide matte containing nickel, copper and cobalt, which is shipped to refineries in Zimbabwe and Norway for further processing. This paper outlines the recent process improvements and plant expansions that have resulted in a capacity increase from 40 000 to 60 000 tons per annum of metal production.

Jan 1, 2006

By G. K. Derby

The Bureau of Mines investigated methods for removing dragline bucket wire rope terminations with the objective of finding efficient methods that are safer than the method most commonly used at U.S. surface mines, which is to use the explosive impact of a projectile fired from a cannon to remove the rope termination. Removal of a wire rope termination for repair or replacement requires separation of the wedge and socket that lock together to secure the rope end. The Bureau investigated currently used methods and improved upon and tested two safer alternate methods for removing wire rope terminations. A cannon test program was conducted, using 40-and 50-gr primer (detonating) cord, to establish the possible force produced with a 4-in-bore cannon and a 55-lb projectile. Wedge and socket units supplied from cooperating mines were separated under controlled conditions to establish data on separation force requirements. The two alternate methods investigated were use of the force generated by (1) a pendulum ram and by (2) a portable hydraulic pusher. Both methods are capable of providing sufficient force to effect wedge and socket separations on draglines with up to 78-yd3 buckets under normal conditions.

Jan 1, 1984