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By Russell J. Miller

A high-pressure intensifier system was designed, constructed and field tested as part of a program to determining the feasibility of applying high-pressure water jets on conventional mechanical rock excavation equipment to increase advance rates. Also developed were a high-volume swivel, capable of transferring the high-pressure water to a rotating cutterhead and manifold system for locating and protecting the jets on the cutterhead. Field tests were conducted in a granite quarry near Skykomish, WA, approximately 90 miles east of Seattle. The concept of improving excavation rates by using water jets to assist mechanical cutting was proven to be successful, with an average increase in excavation mete of 50 to 60%. For some tests, the excavation rate was more than doubled. Machine torque requirements were reduced approximately 25% when the water jets were used. It was suggested this was due to reduced cutterhead friction in the presence of the water jets. A comprehensive economic analysis was undertaken as part of a concurrent study to determine the degree of cost benefits attainable from increased advance rates. Very significant savings were seen to be possible. It was concluded that the basic concept of combining a water jet capability with a mechanical excavating machine is definitely possible.

Jan 1, 1976

By Timothy P. Smirnoff, Tracy K. Lundin

INTRODUCTION The City of Phoenix, Arizona is located in the Phoenix Basin watershed which is prone to flash flooding several times each year. The runoff from these storms moves from the mountains in the north to the Salt River in the south. An extension of Interstate Highway 10 (1-10) will pass through the city east to west to form an Inner Loop through the downtown business district. PROJECT DESCRIPTION The I-10 Inner Loop extension will be a depressed roadway which would intercept the surface drainage of the Phoenix Basin and separate the watershed into two regions. To prevent flooding of the depressed roadway, runoff storm water collected from the northern half of the drainage area will be conveyed beneath the roadway to its natural outlet at the Salt River. A conveyance system composed of pressure tunnels beneath the city, shown in Figure 1, was proposed to achieve this goal . Table A presents the prominent features of each of the tunnels. This paper will describe geologic and engineering parameters specific to Phoenix which were used in the design of a series of tunnels to convey storm water from the I-10 Inner Loop to the Salt River. The design of tunnel initial and final support is described along with support and construction methods used by the Contractor.

Jan 1, 1985

By J. C. Gibson, C. H. Stockwell

"The San Antonio gold mine is at Bissett, Manitoba, on the north shore of Rice lake, 100 miles northeast of Winnipeg. Gold was discovered on the property in 1911, but intensive exploration was not undertaken until 1926. Milling commenced on May 1st, 1932. Total amount of ore milled from that time until the end of 1946 was 1,766,670 tons, having a value of $18,378,317.GENERAL GEOLOGYThe rocks in the vicinity of the mine are Precambrian and include three groups, namely, the Rice Lake series of volcanic and sedimentary rocks, basic and acidic intrusions, and a younger formation of sediments known as the San Antonio formation (Fig. 1). The lower part of the Rice Lake series, consisting of flows of rhyolite, trachyte, and andesite with interstratified beds of agglomerate, occupies an area extending southward from Rice lake. The lake itself and the country to both east and west of its northern end is underlain by the next succeeding beds of the series, which are chiefly tuffs, arkose, and conglomerate, but include a thin band of basalt. Northward from the lake, these are succeeded by the upper beds of the series, first a thin band of basalt and, overlying this, porphyritic andesite flows interlayered with beds of volcanic breccia or agglomerate.The Rice Lake series has been invaded on the east side of the lake by a body of basic rock ranging in composition from gabbro to diorite and quartz diorite, now much altered. This is cut by younger sills and dykes of basic rock, probably diabase, the original texture of which is largely destroyed by alteration. Numerous dykes of feldspar porphyry, quartzfeldspar porphyry, and a few of a rhyolite-like rock, occur south of the lake, but are uncommon to the north. They cut the diabase and older rocks.Extending westward from Rice lake and lying with marked angular unconformity against all of these rocks is the San Antonio formation, consisting of cross-bedded, arkosic quartzite."

Jan 1, 1954

By D N. B Skinner

Changes in the configuration of late Cenozoic volcanic arcs related to Pacific-Australian plate convergence in northern New Zealand may have localised large-scale epithermal gold-silver mineralisation to a particular part of the volcanic arc system, the Coromandel Volcanic Zone (CVZ). The history of arc-type volcanism in northern New Zealand began with the development of the continental margin Northland Volcanic Arc from early-mid Miocene (26-15 Ma). From 18-15 Ma the Northland Volcanic Arc extended south into the northern and western part of the CVZ where it is dominantly composed of andesite with lesser dacite and very minor rhyodacite. In the south, centre and east of the CVZ, younger andesite-dacite volcanism overlapped in space and time (14-5 Ma) with voluminous rhyolitic volcanism associated with rift-hosted calderas and minor basaltic eruptions. This change to bimodal rhyolitic-basaltic volcanism and extensional tectonics was a result of southwest (SW)-directed propagation of the Colville-Lau oceanic island+ arc into the north-northwest (NNW) trending Northland Volcanic Arc and its underlying continental crust. The extensional tectonic regime created in the collision zone between the two arcs is also the site of the 14-6 Ma Coromandel epithermal gold-silver province, which contains some 50 separate deposits and has a production (1862-1996) of about 300 t Au and 1150 t Ag. Extensional tectonics facilitated the emplacement of silicic magma at shallow crustal level and led to reactivation of deep basement faults. The resulting enhanced heat flow and fault-focused fluid flow localised large hydrothermal systems and associated extensive low-sulphidation epithermal gold-silver deposits in the southern part of the province, as at Waihi, Golden Cross and Karangahake.

Jan 1, 1997

By D Crequer

A Peer Review Panel for the Golden Cross Mine in the upperWaitekauri Valley, Coromandel was initiated in December 1989, before mining, as a requirement of the conditions of the Mining Licence and Water Rights. The panel's function is as a technical audit and advisory team - to provide independent technical review of design, construction, and execution of mining operations, slope remediation works, and reclamation/mine closure activities. The primary role of the panel is to act in the public interest by providing assurance to regulating authorities that the design and application of on-site mining operations accords with 'good industry practice'. Panellists are not involved in design nor as advisers, although until 1997 when explicit terms of reference were written, the panellists were a sounding board for some operational proposals. The panel functions to ensure that best mining industry technical standards are met. The costs of the peer review process are met by the mining company. Review of mining operations includes environmental matters such as land rehabilitation and water quality. The focus of this paper is on the process of peer review for environmental management factors rather than for structural and mine engineering.

Jan 1, 1998

In this study, the flotation performances of ethoxycarbonyl thionocarbamate (ECTC), dialkyl thionocarbamate (DATC) and xanthate copper sulfide collectors are compared by the structure-reactivity relationship using generalized perturbation theory and density functional calculation at the B3PW91/6-31G(D) level. The electron-donating power of xanthates is strong and, therefore, xanthates can strongly react with metal cation on the surfaces of copper and iron sulfide minerals through the formation of normal covalent bonds. This explains the poor selectivity of xanthates and also the high pH levels (above 13) required for the flotation separation of copper/iron sulfide minerals. DATCs are more selective for copper sulfide flotation, particularly against gangue iron sulfides. Although less powerful than xanthates, DATCs can perform copper/iron flotation separation at lower operating pH (commonly at pH levels below 11.5). ECTCs use an ethoxycarbonyl replacing an alkyl N-substituent in DATCs. The presence of the ethoxycarbonyl group effectively changes the functional group of collector from -C(=S)NH- to -C(=S)NHC(=O)-. The strong electron-withdrawing ethoxycarbonyl group adjacent to the C=S group decreases the electron density of the sulfur atom, which improves ECTC?s selectivity against iron sulfide minerals at slightly alkaline conditions. The lowest unoccupied molecular orbit (LUMO) of ECTC, which is constituted by the pz-orbit of every atoms in the conjugate -O-C(=O)-N-C(=S)-O- group and which is pleased with accepting richly d-orbital electrons (feedback electrons) from the (t2g)6(eg)3Cu(II) or t6e4Cu(I) configuration of copper cation on the surfaces of copper sulfide minerals, resulted in the formation of dative p-bond. The iron atom, which has a (t2g)6Fe(II) or (t2ga)3(ega)2 Fe(III) configuration on the surfaces of iron sulfide minerals (Fe(III) is the predominant composition at alkaline conditions), has difficulty in offering its d-orbital electrons (feedback electrons) to ECTC?s LUMO. ECTC collectors are powerful for copper sulfide minerals and very selective against iron sulfides, which has been further confirmed by UV spectra and bench-scale and industrial-scale flotation tests.

Jan 1, 2008

Application of Gy?s formula is appropriate for calculation of the Fundamental Error (FE) prior to samples being collected at any stage of the minerals process, provided that sampling parameters K and a (alpha) have been determined by calibration of the ores. Two types of calibration procedure are well established in the industry, the Hetrogeneity test and the 32-piece sampling tree experiment. The sampling tree experiment uses the variance and average grade of metal analyses from four series of samples at different nominal fragment size, as the basic input data. Pierre Gy suggested the cube as an appropriate exponent of the nominal fragment size for use in his equation. More recent work suggests that this exponent is variable and characteristic of specific ores and therefore requires calibration. The method described here explains the experimental procedure of the calibration. It is then possible to calculate a sampling nomogram using the sampling parameters K and a. This allows the sampler to determine a suitable protocol for the sampling event that will ensure that the FE does not exceed a predetermined precision at any point in the sampling procedure.

Jan 1, 2007

By R. J. Kendall

As we enter the new millennium, the South African mining industry has to ensure that it becomes more competitive if it is to survive in the ever more demanding global environment. Traditionally, mechanization in narrow stopes has been limited to the use of scraper winches, and numerous mechanization attempts have been restricted to pilot projects operated on an extremely limited scale (with varying degrees of success). The benefits of hydropower are well documented, and Northam Platinum has shown these benefits to be achievable on a mine-wide basis. However, the equipment originally developed for hydropower systems has followed the traditional labour-intensive approach commonly used in deep level narrow stoping operations. The problems experienced with the hydropower system are discussed and the rationale for developing alternate technologies is explored. The hydropower system has shown to be a versatile powering medium which can be harnessed for a diversity of uses. It (hydropower) enables the mining engineer to change traditional paradigms and to design an entirely new approach for optimizing the mining operation based on explosive techniques. The system developed for Northam consists of the following: ?Purpose-built stope drill rig operated off the hydropower system with special features to ensure accurate drilling patterns throughout the length of the blast hole ?Purpose-built high rate cleaning system for rapid transfer of fractured ore to the stope orepass ?Redesigned stope layout to facilitate in-stope water control and to recover fines from the run-off water ?Purpose-built drill rig for rapid establishment of reef raises and advanced strike gullies ?Purpose-built drill rig for flat end development. On both types of development end rig, emphasis is placed on ensuring accurate drilling patterns throughout the length of the hole to maximize linear advance per blast. The paper discusses the implementation of the Northam system on a large scale as well as current initiatives to further improve on the efficiencies of mining operations. It concludes by emphasizing that mechanized hydropowered stope technologies are in their infancy and thus offer unlimited scope in progressing beyond today?s paradigms to present as yet unthought of solutions for optimizing deep level ore extraction.

Jan 1, 2000

By Thomas M. Barczak

The era of the shield-supported longwall face began in the United States a little over 25 years ago. The most fundamental development of the shield in the past 25 years has been an increase in size and capacity and a progression toward two-legged designs in favor over four-legged shields. Is the “bigger-the-better” design philosophy justified? The advantage of the two-legged design is largely attributed to its active horizontal force caused by the forward orientation of the leg cylinders. How do we know this? You might be surprised to learn that shield loading data may suggest otherwise. In addition, what about setting pressures? Should they be set as high as possible? Some people have advocated that setting pressures should equal the yield pressure. Does this make any sense? Is yielding a good or bad thing? These are some questions still worthy of investigation that are addressed in this paper. The first major change in gateroad support was the use of cable bolts to replace conventional wood cribbing particularly in Western mines. Standing support changed very little until the mid-1990s, when Strata Products1 introduced the Hercules and Propsetter supports in Eastern mines and Burrell Mining Products introduced the Can support in Western mines. Since then, there has been a dramatic increase in new roof support technologies for longwall gateroad support. Historically, standing support, including shield supports, have been designed based on a simplistic model requiring the support to have sufficient capacity to support the gravity loading of a perceived detached rock mass. This approach ignores the stiffness of the support and the resulting ground deformation that is known to be critical to roof stability. Recently, a new approach based on the ground reaction concept has been promoted by the National Institute for Occupational Safety and Health (NIOSH) to account for the interaction of the support with the rock mass behavior in achieving ground stability. In addition to gateroad support design, this concept has ramifications for shield capacities, setting pressures, and recovery room support design that challenge current practices in these areas. Although longwall mining has matured into the safest and most productive underground mining method used today, traditional concepts of roof support design and practice should still be evaluated and challenged. Ultimately, advancements in the science of ground control are made by recognizing deficiencies in current theories and thinking outside the box.

By Scott Turner

The present rapid growth of coal stripping in the United States is a curious reversal of the tendency of mining to proceed from outcrop to depth. A combination of technical and economic factors bas stimulated the use of stripping methods until today many million tons of coal We being recovered by open cuts from sites that an earlier generation of engineers would have passed by as not commercially mineable or, if workable at all, only by underground methods. The total quantity of bituminous coal and lignite mined in the United States by stripping in 1928, the latest year for which detailed figures are available, was 19,789,000 short tons. Of this, 71,000 tons came from small workings not equipped with power shovels and 587,000 tons from properties in which stripping and underground work were carried on at the same mine; but as neither of these types is representative of modern stripping practice, they will be omitted in the discussion that follows. The total from strip pits proper in 1928 was 19,131,000 tons, produced by 176 pits employing 385 steam or electric shovels.3 Figures by States are given in Table 1. Detailed statistics will be found in Economics of Strip Coal Mining; a study by O. E. Kiessling, to be published by the United States Bureau of Mines.

Jan 1, 1930

By R. Khanna, M. Dubikova

A variety of carbonaceous reducing materials are being used for the production of ferroalloys. Reductant materials include not just carbons such as coke, coal, char but also bio-carbons in form of charcoal produced from different types of wood. This paper discusses critical properties and reactions of carbonaceous materials and their significance in dictating reductant performance. Main considerations include among others, gasification of reductant, dissolution of carbon into molten metal, and direct reduction of slag by solid carbon. These are discussed in relation to material properties such as structural order, mineral matter content, composition, physical characteristics etc. A brief review of both conventional and novel approaches towards characterisation of carbonaceous materials has been included. Due to complexity and heterogeneity of carbonaceous reducing materials and a wide range of process requirements, the selection of the most appropriate reducing agent will depend on a number of considerations such as the availability of raw material and associated costs, product and process requirements and environmental aspects of waste gas emissions.

Jan 1, 2004

By C. A. Geffen-Fowler

This report, sponsored by the Bureau of Mines, presents the results of an examination of the safety of the Blind Shaft Borer (BSB) shaft sinking system and an alternative modified BSB design concept in comparison to conventional shaft sinking technology. Detailed study of the two systems was also performed to identify and recommend design changes for optimum safety conditions. A comparison of the BSB systems with conventional shaft sinking was made on the basis of relative risk levels. Risk incorporates both the frequency and the potential consequence of accidents. A safety evaluation of the component operations of the two BSB systems was performed using a Failure Modes and Effects Analysis (FMEA) methodology. The results of this analysis show generally that both BSB systems are safer than conventional shaft sinking. The potential risk of conventional shaft Sinking operations could be reduced by over 30%, on the average with the use of the original BSB system, and by an average of about 10% with the modified BSB. Design change recommendations to further improve the safety of these systems include a better fire suppression system, improved man haulage systems and more compact hydraulics. An operational safety manual was also developed for the modified BSB system.

Jan 1, 1981

By William R. Wessels

This report describes a field survey and laboratory investigation into the causes of failure of resiliently clad screen decks applied to coal preparation plants. Blinding of screen deck perforations and delamination of the resilient cladding are studied and mechanisms responsible for these failure modes are hypothesized. A laboratory test program to simulate the mechanisms was begun and abandoned when it became apparent that meaningful test results would require a substantially redirected effort. No meaningful test data was obtained from the laboratory simulation.

Jan 1, 1982

By W Barry Gregg

The rock blasting and mining industries use a system of detonators and explosives for mining operations. Many detonators use small metal bridgewires, which are heated by passing a current through the wire, heating and igniting the pyrotechnic powder in contact with the wire, Typical bridgewires require a current of at least 3 amps, applied for a few milliseconds, for an explosive output. The semiconductor bridge (SCB), in comparison, initiates an explosive in 0.01 to 0.1 of a millisecond.

Jan 1, 1992

By Syd S. Peng, C. Y. Chen

Introduction The Surface Mining Control and Reclamation Act was passed in 1977 to put an end to the uneven environmental standards and enforcement established by various coal mining states in the US. One year after passage, the Secretary of Interior was directed to promulgate permanent program regulations implementing Title V provisions of the Act. These regulations were to form the basis for state regulatory programs under the Act and to allow states to assume primary regulatory responsibility. To implement the underground mining provision of the Act, the Secretary is directed in section 516(a) of the Act to promulgate rules. But they must take into consideration the differences between surface and underground coal mining. The regulations developed by the Secretary in 1979, with respect to subsidence control, included: • a subsidence control plan as part of the permitting process; • substantive provisions establishing performance standards for subsidence control; and • provisions providing for the prohibition of mining under perennial streams, impoundments larger than 24.6 dam3 (20 acre ft), and certain public facilities and urban areas. Industry challenged the Secretary's regulations implementing the subsidence control provisions. The litigation was consolidated with all other challenges to the permanent program regulations. (Permanent Surface Mining Regulation Litigation, Civil Action No. 79-1144; D. D.C., May 16, 1980.) In two opinions dealing with the multitude of issues raised by both industry and environmental groups, the US District Court of the District of Columbia ruled against industry. It upheld the promulgated subsidence control provisions. The US Court of Appeals stayed the appeals pending the agency's review and revision of its regulations. The regulatory reform was conducted in accordance with the order from the Secretary of Interior and the President in 1981. As a result, the subsidence control regulation was revised, reproposed, and finalized in June 1983 (Federal Register). This regulation, along with others, was again challenged by environmental groups and industry. On Oct. 1, 1984, the court, after finding the Secretary's reading of the Act reasonable, upheld the 1983 subsidence regulation except for one section. On Feb. 21, 1985, in accordance with the court's ruling, the Office of Surface Mining (OSM) suspended a portion of 30 CFR 817.121 (c)(2) concerning the damage correction requirement for structures or facilities and reproposed it on July 8, 1985 (Federal Register). In conjunction with a request for public comments, OSM now also seeks comments on the omission from the 1983 rule of the requirement in the 1979 rule regarding a presubsidence survey and monitoring of damage to structures. Technical issues related to subsidence regulations The subsidence regulations of June 1, 1983, consist mainly of two parts: a subsidence control plan as part of the permitting process; and substantive provisions establishing performance standards. The latter also includes provisions for prohibiting mining under certain areas. Under subsidence control plan section 784.20, minimum require-

Jan 2, 1986

By F. M. C. C. Vieira

The DEEPMINE Research Programme sought to develop the technology and competence to mine gold safely and profitably at depths of 3 to 5 km. Among the many issues addressed was the stability and support of rockpasses at ultra-depth. It was found that high virgin and mining-induced stresses could cause the walls of rockpasses to spall, leading to the deterioration and failure. A comprehensive programme of numerical modelling was conducted to investigate alternative mining layouts and sequences to ameliorate the problem.

Jan 1, 2005

By Arnaud Faucher, Claude Bazin, Marilène Renaud, Mohamed Mai Manga

"Grinding circuits are operated in the presence of disturbances due to ore changes and equipment malfunctions. One of the challenges faced by the operators is the detection of a disturbance, the identification of its origin and of the action needed to minimize its impact on the process. Hydrocyclones overloading, worn or partly plugged apexes of the units of a nest, surging and internal liner detachment may cause a loss of classification capacity and quality. Recovery losses in downstream leaching or flotation circuits justify the effort in developing techniques for the detection of hydrocyclone malfunction. Two approaches for the detection of hydrocyclone fault are presented in this paper. The first proposed method uses the conventional sensors available in a grinding circuit allowing real time detection of hydrocyclone abnormal operation. The second technique is based on the use of vibration sensors installed on the hydrocyclone of a nest. This last technique enables the classification of the hydrocyclone malfunction as surging, overloading and plugged apex. The two techniques can be combined to increase the robustness of the problem detection.INTRODUCTIONHydrocyclones are used for many purposes ranging from water separation, fines removal and obviously for the preparation of the feed for subsequent concentration circuits in a mineral processing plant. The strategic role of the hydrocyclones for the preparation of the feed to the concentration circuit is often underestimated because of their simplicity of operation and robustness (Napier-Munn et al., 1996; McIvor, 1988). It remains that despite their simplicity, hydrocyclones have been studied extensively from 1970 to 1990 with the objective of developing mathematical models of their operation to be incorporated into grinding circuit simulators (Napier-Munn et al., 1996; Lynch, 1977; Flintoff et al., 1987). Such a development effort is already an acknowledgement of the importance of these units in a mineral processing plant. Several authors (Del Villar et al., 1996; Plitt and Kawatra, 1979; Casali et al., 1998) proposed soft sensors to estimate the classification efficiency of hydrocyclones using sensor measurements. However, few of the proposed sensors are used in the industry. More recently several papers were published to discuss the application of 3-D modelling of the hydrocyclones (Narasimha et al., 2005; Cullivan et al., 2004) and sensors (Bond et al., 1999; Neesse et al., 2003; Hou et al., 1998; Olson and Waterman, 2004; Williams et al., 1995; Willams et al., 1997) to help in the detection of hydrocyclone malfunction."

Jan 1, 2010

By Curtis G. Kremer

"New explosives initiation systems continue to be developed as new technologies make advancements possible. Due to recent initiator developments, explosives users now have the most reliable, accurate, safest and easy to use systems ever offered. Three initiation systems recentlyintroduced which offer significant improvement over standard electric and nonelectric initiation systems include Magnadet, EXEL high-strength shock tube, and Redundant two-Dath surface delay systems. These three systems will be discussed zn cecail with rmpiasis on their functioning, safety characteristics, ani specific application areas."

Jan 1, 1991

By Frank E. Cash

The work of the United States Bureau of, Mines is concerned primarily with the prevention of accidents in the mining, petroleum, and allied industries. This report analyzes the fatal accidents in the coal mines of Tennessee and gives the pertinent factors in tabular and descriptive form, with interpretations and suggestions to operators, workers, and the State Division of Mines for the future prevention or reduction of accidents in coal mines. ACKNOWLEDGMENTS This study was made possible through the cooperation of A. W. Evans, chief mine inspector of Tennessee, and his secretary, Miss Hiliary Penny, who made available the department records and assisted in the segregation and assembly of the data.

Jan 1, 1935

By Louis W. Cope

Mongolia is known in western countries as the location of rich dinosaur fossil fields. However, the country is even richer in mineral resources. The Ministry of Industry and Trade reports 6,000 mineral occurrences of 80 metals and minerals. Mongolia has already attracted much foreign investment in the mining sector. Mining is the country’s largest industry. It is responsible for 17 percent of the gross domestic product, 65 percent of industrial output and 57 percent of export earnings.

Jan 1, 2006