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By M. P. Miano

Matching the productivity gains of continuous mining machines with the ever increasing performance levels achieved by longwall units has required creative thinking to assure that development is completed in time for uninterrupted longwall production. By using management information systems to coordinate support operations, the most productive planning decisions can be made. This paper focuses on the role of computer technology tools in achieving improved productivity from both longwall and continuous miner sections. The primary emphasis is on the planning process and the methodology developed to guarantee the best allocation of management and manpower resources.

Jan 1, 1993

By Mary Nelima Ondiaka, Oladunni Oyelola Alabi, Fatai Olufemi Aramide, Francis Gitau, Talabi Henry Kayode

Iron ore is essential in steelmaking but high-grade ores have diminished, making it necessary to turn to low-grade ores, which need further beneficiation to upgrade the iron content. Biobeneficiation techniques such as bioleaching, bioflotation and bioflocculation have proven successful in iron ore processing. Consequently, these methods have emerged as sustainable alternatives to conventional beneficiation. The biobeneficiation processes occur in mild conditions using bioreagents and biosurfactants derived from microbes, and offer a reduction of chemicals used in processing. This potentially offers methods that are relatively energy efficient, cost effective and environmentally friendly while tackling the constraints of dwindling high-grade iron ore resources.

Sep 1, 2024

By David E. Sims

Asarco has been using computer-aided open-pit mine design since 1966. The in-house developed program package includes drill-hole analysis programs, interpolation routines, and three-dimensional open-pit design programs. The financial analysis step after pit design required that a reasonably accurate schedule be produced so that a good cash flow model could assess the feasibility of a project. The manual method of scheduling was too time-consuming for feasibility work, so a computerized scheduler was required. Since no computerized mine scheduling programs existed, we requested proposals from consulting firms to develop such a program. The selection of a consulting firm, the formulation of the contract and design specifications required about three years to accomplish. The consulting firm, Systems Control Inc. (SCI), of Palo Alto, spent over one year doing the programming and testing alone. The details of the program development were reported in "Computerized Year-by-Year Open-Pit Mine Scheduling," SME-AIME Transactions, December 1974. In June of 1973 the program, which SCI dubbed Optimum Resource Extraction or ORE, was installed. Version 1 of ORE was utilized successfully on three separate properties over a period of two years. During this time it became obvious that some of the original design specifications were restrictive, and certain modifications were required. The ORE program was submitted for modification, and after one year version 2 was operational in May of 1976. The program now consists of approximately 20,000 lines of FORTRAN source statements grouped into 190 subprograms, and runs in a 450K region of Asarco's 370/148 in Cranford, NJ. The Tucson com¬puter (370/115) is tied to the Cranford computer via a 9600 baud leased T.P. line, for running mine scheduling and other large mine planning programs.

Jan 1, 1979

An information system (I/S) plan is a means for establishing and communicating the direction the organization intends to take to provide the information required for achievement of organizational goals and objectives. The rapid advancements in information technology, the increasing complexity of systems, and the growing dependence of mining companies on these information systems have emphasized the need for more comprehensive I/S planning. This subsection explores this need, the role I/S planning can play within a mining company, and finally describes a methodology for development of an I/S plan.

Jan 1, 1979

By J. Swensen, R. Brandon, A. Wallstein, S. Bessinger, J. Pile

It is generally agreed that C.C. White was the first to describe and market coal mine roof trusses beginning as early as 1967. White was issued a patent in 1969 1. Coal mine roof trusses were extensively used in the 1970’s, and their use has proven valuable in many difficult conditions. Beginning in the mid 1990’s, several types of bar/cable trusses have been introduced. A new and innovative bar/cable truss recently introduced offers several advantages. By eliminating many small parts, and simplifying the installation, these new trusses are much easier and faster to install, thereby increasing operator safety.

Jan 1, 2004

By D. R. Dixon

Since the critical role of oxygen in xanthate flotation of sulphides was established (1) subsequent studies have been concerned mainly with the galena-xanthate system. It is therefore surprising to find at the conclusion of a comprehensive review of the topic by Granville, Finkelstein and Allison (2) that it was not possible for them to draw unequivocable conclusions on the mechanism of xanthate adsorption. It was apparent that some new advances were likely if systems other than galena-xanthate (Pbs/x-) were examined. (2) Specifically a less reactive sulphide such as ZnS may interact with flotation reagents at a slower rate than PbS and more information per unit time gathered. Again ZnS is far less reactive electrochemically than PbS or stated equivalently, it is a poorer semiconductor than PbS. More importantly, the ability of ZnS to act as a semi-conductor can be controlled photochemically rather than by direct doping reactions for which it is difficult to assess the uniformity of doping. Thus the conductivity of ZnS can be made the same as that of PbS by irradiating the ZnS with ultraviolet light at circa 360 n.m. (3)

Jan 1, 1974

By D. A. Dahlstrom

Crushing and grinding consumes about 1.3% of the nations produced electrical energy.( Furthermore, only one in the first ten highest consumers comes from an industry other than mineral processing. This is the grinding of wheat to make flour. The other nine are all in the metallurgical industry and are easily the largest consumers.

Jan 1, 1988

By Sanja Zlatanic, Michael P. Della Posta

New York State’s Metropolitan Transportation Authority (MTA) has undertaken the largest transportation project in New York City. The East Side Access Project (ESA) will introduce MTA’s Long Island Rail Road (LIRR) service to the East Side of Manhattan, to a new terminal located beneath the existing, landmark Grand Central Terminal(GCT). Construction of the Manhattan Segment of the project will affect overlying operating facilities of two other MTA entities, Metro-North Railroad (MNR) and New York City Transit (NYCT) and major Midtown Manhattan buildings. The paper describes the evolution of the GCT concept at Manhattan from a shallow alternative proposed by a Major Investment Study (MIS), that would require extensive underpinning of multi-story buildings and have considerable impact on MNR and NYCT operations, to a deep alternative with lesser risk and potential for disruption.

Jan 1, 2001

From some of the largest tunnel projects in the some of the most vibrant cities, to smaller projects in remote corners of the globe, the Robbins Co. announced two tunneling projects in which its tunnel boring machines will be used. Robbins earth pressure balance (EPB) machines undercut Downtown Zhengzhou. Zhengzhou, a city of 7 million people, is set to become a crossroads for rail commerce in China. The country?s future main routes, traveling between Beijing and Guangzhou (North-South), and between Xuzhou and Lanzhou (East-West), will intersect in the city. The plan includes up to four rail lines in Zhengzhou itself, which will eventually link up to the national lines. Excavation of Zhengzhou Metro?s new Line 1 tunnels began on Sept. 28, 2010, when the first of two 6.3-m (20.7-ft) diameter Robbins earth pressure balance (EPB) machines was launched from a 16-m- (52-ft-) deep shaft.

Jan 1, 2010

By M. M. Botz, F. W. DeVries

Discussion by F.W. DeVries Comments on natural cyanide attenuation. The paper by Botz and Mudder in the November 2000 issue of Minerals and Metallurgical Processing had one disappointing aspect. Table 1 (p. 229) failed to include a significant species - neutral copper cyanide (CuCN). This compound has been most trouble-some in many plant-scale cyanide cleanup processes, includ- ing acidification-volatilization- reneutralization (AVR), hy- drogen peroxide cleanup and air/SO2 cleanup. It has also plagued many pilot efforts to use ion-exchange (IX) resin technology. This author elucidated the concept that, under some conditions, copper cyanide failed to precipitate out of treated effluents and appeared to exist as a filterable colloid that reported as copper and cyanide, with the latter measured as WAD (weak-acid-dissociable) cyanide in that analytical method. The concentrations measured were very near the levels of 0.2 ppm, often the regulatory limit for WAD cyanide. The copper concentration, using the 1 : 1 ratio for this com- pound, would then be more than 0.4 ppm, which could also be unacceptable. We discovered that it was unsafe to assume that the Cu(CN),- would surrender both cyanide ions simultaneously and allow cupric copper to be removed subsequently as, say, cupric ferrocyanide (Hatchett's Brown). This compound could be ignored as safely as the "iron blues," as essentially an inert solid, stable in geologic time if not exposed to sunlight. Under poorly controlled oxidation of the cyanocuprite ions (copper with four, three or two cyanides complexed to the copper), CuCN could well be formed and could not be assumed to precipitate out as a solid. The authors of the paper, by failing to include the CuCN species in their model, may have left users of the model prone to ignore the possible occurrence of the colloidal(?) form in the discharge, thus finding an effluent that failed to meet regulatory limits. (See addendum below.) This somewhat ephemeral material may well have been responsible for some large-scale failures of cyanide destruction technology to succeed at sites in North America and elsewhere. Two specific references alluding to this occurrence may be found: Griffiths et al., 1987, "The detoxification of gold-mill tailings with hydrogen peroxide," Journal of the South African Institute of Mining and Metallurgy, September, p. 282. DeVries, 1989, "Improved understanding in detoxification of cyanide leach liquors using peroxide" Rand01 Gold Conference, Sacramento CA, p. 15 1. It is advisable for workers in this area of cyanide removal or recycle to avoid assuming that CuCN will, with certainty, precipitate out of solution, or that the dicyanocuprite ion will part simultaneously with both cyanide ions and allow cupric copper to be dealt with by other reactions. One further piece of work may be incomplete. That is, a definitive study of the long-term behavior of CuCN that does precipitate when exposed to other compounds present in neutralized tailings. Addendum. The extremely complex reaction of cupric ion on cyanide- which, of course, results in oxidation of cyanide to cyanate, probably through the intermediate stage of forming cyanogen [(CN)2] from oxidation of HCN with its hydrolysis to cyanate and cyanide ion - involves two cyanide moieties and the reduction of the cupric ion back again to the cuprous state. This, then, can form the CuCN potential "solid" that was already the undesirable species. In cyanide cleanup, with either air/SO2 or hydrogen peroxide, copper is generally employed as the catalyst, so it is unclear what happens when the CU(CN)2-1 is ultimately exhausted. Certainly, the field evidence is quite clear that all

Jan 1, 2002

By William G. Fischer

Basic laboratory tests initiated the. Rock Mechanics program. The stress-strain curve, modulus of elasticity, Poisson's ratio, the uniaxial rock strengths, Mohr's envelope, the stress at failure, and creep were investigated. A series of underground problems were then approached using this information; and various field measuring devices, most of which were developed by the Bureau of Mines. Initially, stress concentrations near mine openings were evaluated using the stress relief technique. This required an accurate determination of the pre-mining stress field. Later, stress concentrations associated with the cave line .sere studied. After about thirty stress reliefs over an appropriate time interval the effects of one type of mining could be compared against another. The microseismic technique was used to investigate a possible application of warning devices near the cave line. A study of mane reorientation was made Problems related to the shape and size of pillars and barriers were studied. Partial extraction mining systems were evaluated. The effectiveness of roof bolting patterns were examined. Control of roof stresses was attempted. A new system of mining in heavy ground has been developed using the information secured in the Rock Mechanics program without this system, mining in more than one instance would Nave been next to impossible. Indeed; from this one discovery alone, the Rock Mechanics program has paid off in improved safety as well as in dollars.

Jan 1, 1964

By Andy Ingriselli, Andrew Famiglietti, John Westland, Greg Landry

Atlas Dewatering was contracted to install and maintain a groundwater control system for the new Bessarion Subway Station and the Tail Track Structure on the Toronto Transit Commission’s new Sheppard Subway Line. Atlas met the challenges presented by the project by closely reviewing the contract documentation provided by the Program Geotechnical Consultant, Golder Associates and by working with the general contractors, Bondfield Construction Company and PCL Constructors Eastern, inc., throughout the duration of both projects. In addition to concerns about soil loss, excessive settlement and seepage, the consultant was concerned about spreading hydrocarbon-contaminated groundwater between the two aquifers present at the Bessarion Station site. By installing a system of multi-level vacuum eductor wells around the perimeter of the excavation, Atlas was not only able to provide a dry excavation for construction, but, due to a unique well design was also able to prevent cross-contamination of the aquifers.

Jan 1, 2001

By E. Medina, W. Callupe, R. Sharon

Slope stability in Barrick’s Pierina Mine open pit is significantly influenced by the structural geology, the variably argillized rock mass, and locally by perched groundwater. Development of an extensive surface water diversion network continues at Pierina, which is necessary to minimize highwall and adjacent natural landslide movement and erosion during the wet season. Slope movements are effectively monitored using optical survey methods, strobe light extensometers, gap monitors, and piezometers. The slope stability program at Pierina is focused on improving the understanding of the stability mechanisms in order to ensure continuous safe operating conditions. Priorities are placed on developing an accurate detailed engineering geological model, enhancing groundwater depressurization, and optimizing highwall controlled blasting procedures.

Jan 1, 2003

By C. J. B. Dreyer, H. A. Robinson

Only South Africa can be considered in terms of resources of amphibole asbestos. There are two asbestos producing fields, one in the Northern Cape Province (producing only crocidolite), and one in the Eastern Transvaal (producing only amosite). This chapter discusses the banded ironstone sequence in which amphibole asbestos occurs, and the genesis of the fiber is briefly reviewed. Also, the properties and characteristics of amphibole asbestos are discussed and compared to those of chrysotile. Approximately 300 000 t of arnosite and crocidolite are produced annually. Crocidolite has a potential for a fivefold increase of production chat could be sustained beyond the year 2000. An estimate of the resources of the various producing fields in South Africa is made. The mining methods are also reviewed and evaluation techniques are discussed. The only two types of amphibole asbestos exploited at present in South Africa are amosite [the white colored amphibole asbestos) and crocidolite (the blue colored asbestos). As is well known, crocidolite has been mined in South Africa from the early part of this century, and amosite since the early 1930's. Since these dates, asbestos mining has developed into a significant mining industry. The annual production of crocidolite is approximately 170 000 to 200 000 t. and amosite production is in the region of 80 000 to 100 000 t. CLASSIFICATION OF AMPHIBOLE ASBESTOS Four types of amphibole asbestos are produced economically in the world today: (1) crocidolite, the fibrous equivalent of riebeckite, (2) arnosite, the fibrous equivalent of grunerite, (3) trernolite, and (4) anthophylite. The names trernolite and grunerite apply equally to the crystal and fibrous forms of these minerals. For comparison and clarification purposes, the six known varieties of asbestiform minerals known in the world are shown in Table 1. All the asbestos minerals were originally developed as cross fiber seams in veins or fractures, or were controlled by the lithology. Post- fiber effects caused slip, sheared, and folded fiber seams. Crocidolite and amosite occur in banded ironstone of early Proterozoic age of the Transvaal Supergroup. The fiber seams are developed in certain defined lithological units in the banded ironstone sequence. The lithological units have a remarkable lateral persistence with respect to their chemical nature and physical appearance. Vertically, the banded ironstone sequence displays a heterogeneous nature. Commercial Applications The features and properties that make amphibole asbestos commercially attractive are: 1) The long average length of the fibers is good for greater wet strength in composites. 2) The high tensile strength of crocidolite makes it superior to all other types of asbestos. 3) It is characterized by dispersion in most liquid media, particularly amosite in water. 4) Since the surface charge of amosite and crocidolite is negative, the fibers produce an open lattice work in water with a high bulk volume giving excellent filtration rates and rapid drainage in a wet asbestos cement mix. 5) The insulating properties of amphibole asbestos mats are still important, particularly in a corrosive environment, despite the introduction of many other synthetic insulating materials. 6) Corrosion resistance, particularly acid corrosion resistance. 7) Due to the high modulus of amphibole fibers, resins reinforced with these fibers exhibit

Jan 1, 1986

By Roger S. Dewey

1.1. INTRODUCTION Despite indications of a general economic recovery in the U.S. during the mid-19801s, mine operators have not generally shared in the benefits of these reported better times. Budgets have not rebounded, borrowing is tougher, parent companies' pockets are not as deep as in previous years, and margins are not any better -- if there is any left over at all. Managing capital equipment budgets is always a challenge, and the last five years of stretched equipment lives make these decisions more tenuous. Delays and avoidance of replacements due to tough times inevitably makes those decisions increasingly difficult and usually more expensive The purposes of this paper are to present. a brief refresher outline of the fundamentals of equipment replacement analysis, to suggest a number of papers where analysis methods are explained in greater detail. and to recommend the use of a widespread microcomputer software capability (1-2-3) as the easiest path to a much-needed solution for a very difficult, and usually under-supported management decision problem 2. REPLACEMENT DECISION POLICY Investments in equipment replacements must compete for capital with all other investment alternatives. Capital for replacements of ten represents a greater commitment than do the new projects which a company might handle in a given year. But. sadly, formal policies for standardized analysis of replacements rarely exist, even in major companies. Yet this policy can be very significant in determining the competitiveness of a firm. Whereas many replacement decisions are based on cost minimization, economists and financial analysts agree that wealth maximization or return on investment is the superior criterion. Though the difference may seem slight, agreement on a firm's financial objective is vital. Replacement policy should be straight- forward. have a logical basis, and a proper level of sophistication. There are several reasons to develop a policy for replacement decision-making: [I] 1 - equipment's optimal economic life is nearly always shorter than its physical life; 2 - mine life often exceeds equipment life, so management must face these decisions routinly 3 - replacement capital costs, on an undiscounted basis, can run 25 to 75% of original capital 4 - technological changes may result in a newer machine or system which can operate more efficiently, more safely. or less expensively 5 - estimates should be made consistently in the fundamental areas of life expectancy, availability, utilization. price escalation, taxes 6 - long-term and short-term budgeting without decent data and analytical capability is nearly impossible, or at least ineffective Policy development assumptions which must be considered include: the planning horizon, cost patterns, interest rates, availability of capital, replacement vs. expansion, technology advances.

Jan 1, 1987

By Werner A. Dürrfeld

The Bullflex® System was introduced as a substitute for timber and debris lagging in mines and to create an in-situ early-stage interlocking effect between steel supports and the rock wall. As deplacement and/or disintegration of strata and of rock beds is to be avoided under all circumstances - following the ideas of NATM-steel support can only be loaded to the maximum when point load is avoided and ideal bedding of the rock is maintained.

Jan 1, 1981

By J. Jordan, D. K. Denton, D. Tesarik, D. F. Scott, T. J. Williams

Personnel from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health integrated the results of studies from a seismic tomographic survey, a finite-difference analysis, laboratory measurements of compression wave (ultrasonic) velocities in rock cores, and site geology to evaluate the use of seismic tomography for identifying induced pressures in an underground pillar at the Edgar Mine, Idaho Springs, CO. The key findings were that (1) the seismic tomograms showed that seismic velocities in rock adjacent to mine openings were low, (2) a difference tomogram in which in situ stresses on the east and west sides of the slot were compared showed that velocities increased west of the slot but decreased east of the slot, (3) geologic features (rock types and a fault) identified through geologic mapping were recognizable in the seismic tomograms, (4) ultrasonic velocity measurements on the rock cores agreed with seismic velocity measurements in the tomograms, and (5) results from a finite-difference analysis compared well to the seismic tomograms west of the slot but not east of the slot. The significance of this research is that seismic tomography is a useful tool for determining relative stress in underground pillars.

Jan 1, 2004

By Ted Budd, Vladimir Goubanov

The East Central Interceptor Sewer, commonly known as the ECIS Project, is the largest public works construction project awarded by the City of Los Angeles. The complexity of this $240 million project, together with the challenge created by the mandated 1,000 calendar days for construction completion, make this project a major interest for the tunneling industry. This paper will describe the ECIS tunnel project, currently under construction by the Joint Venture of Kenny (Sponsor) / Shea / Traylor / Frontier-Kemper. Mining of the18.5 km (about 11 miles) long and 4.7 m (15ft-4in) diameter tunnel is underway with four Tunnel Boring Machines mining at the same time. Details on the mining machines, muck handling systems, innovative construction sequence, together with mining progress will be given.

Jan 1, 2003

By J. B. Gwiazda

Maintenance of a constant load setting throughout longwall support units and selection of the proper initial bearing capacity depending on the type of roof strata are the basic factors that ensure good performance of roof support in a longwall. These requirements can only be met by hydraulic support. The greatest advantage of hydraulic support is achieved when uniform pressure is imposed on the roof throughout the length of the longwall. Such support, however, is provided only if each of the support units acts with the same force against the roof, i.e., has the same setting load. In such cases, the roof behaves like a uniform plate without bending and shearing stresses, thereby ensuring an undisturbed structure. Without a positive set value system, achieving an equal setting load for all units of the longwall support is impossible. Due to alterations of the feed line pressure of support units as well as some reasons related to man's psychology, operators extend the height at different setting loads. This produces nonuniform roof stress, and disturbs the structure. Consequently, the roof usually cracks. The author has developed a positive set value system, which is described in this Technical Note. Selection of the setting load Two pressure values in the feed lines are usually applied in longwall hydraulic systems. Lightweight support is fed by 25 MPa (250 bar) liquid, while heavy duty units receive a nominal pressure of 31.5 MPa (315 bar). Such pressure is required not only for the props but also to power the adjust¬ment jacks and the advancing ram. If the feed pressure is too low, there will be difficulty in shifting the unit despite the inversion system of the advancing rams. On the other hand, for many roof types, the feed pressure often appears to be too high when applied as the setting load pressure. An excessive setting load acts too strongly against the roof, crushing weak strata close to the roof. The author has recognized a case where an excessive setting load destroyed not only the nearby roof strata but also the strata above a 2-m (6.6-ft) sandstone layer. In addition, an excessive setting load relieves the side¬walls, increasing the resistance when using cutting machines. As a result, the yield of coarse coal is diminished, and increased fines dominate in the final product, lowering its economic value. As indicated, selection of the proper setting load, depend¬ing on the mining and geological conditions of the extracted seam, is extremely important. In some mines, measures applied to prevent disturbances include reduction of the feed line pressure by adjusting the feed pump valve. The disadvantage accompanying reduced feed line pressure is more difficult operation in advancing the ram. Due to the reduced feed line pressure, the force of the advancing ram is much lower than the designed value. Other designs suggest using a third feed line. However, installation of supplementary valves on the support units is required, a time-consuming and expensive procedure. The disadvantages of the powered supports are eliminated by a system designed by the author. So far, such a method of setting load control has not been used in any type of support. Setting load control unit The designed positive valve set for prop loading and the setting load control correspond to existing control systems for hydraulic powered support. The layout of the unit connected to the hydraulic prop control is presented in Fig. 1. The unit is marked LIDS. It incorporates three valves that may operate separately or connected. Valve A automatically opens and closes with liquid flow in the prop feed circuit. The valve is opened when the canopy touches the roof and closed when the support unit is withdrawn. Valve B serves as the setting load control. Valve C automatically opens and closes the flow in the line connecting the under-piston space of E to the prop F with the separator G. The valve block of each support prop is marked BZ. The UDS unit is connected by the hydraulic lines to the F prop control circuit. A valve is connected by H to pressure line J and by K to the G separator. In the UDS-3 version, line L is connected to M, linking the over-piston space of F prop with the G separator. Valve B is linked with valve A by a connector; it is also connected to the under-piston space E of prop F by line P. Valve C is fixed between lines K and P, connecting space E of prop F with the separator G. When setting the support, the liquid flows from line J through separator G, the BZ valve, and valve C to the space E of prop F. When reaching the roof with the canopy, valve A is opened and C closes. In this way it is impossible for the operator to cause the liquid pressure in space E of prop F to reach the level of line J. The prop pressure is set by valve B of the UDS unit. When withdrawing the support, valve C is automatically opened and A closed. Three UDS units have been fabricated and are designated

Jan 1, 1990

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