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By David J. Akers

In past years, water drainage control in coal mines has been primarily directed on the basis of water quantity rather than quality. Due to the recent intense interest in total ecology and environment, emphasis has shifted to the point where the water exiting from a mining operation may be of better quality than when it enters. In most operations this has meant the use of treatment methods (neutralization) while the technology for the prevention of acid drainage is being developed or refined. To date, underground abatement of acid formation has generally been less expensive but also less effective than surface treatment of the mine water. It seems probable that total mine water pollution control will have to include both underground abatement and surface treatment methods. The general acid producing reaction involving the oxidation of pyrite - 2FeS2 (pyrite) + 702 + 2H20 ? 2Fe2S04 + 2H2SO4 - is well known, even though the individual steps are not clearly understood. The major implication of this reaction, that acid production can be eliminated by not allowing the contact of pyrite with free oxygen or water, has been well substantiated both in the laboratory (1,2) and in practice. (3) Underground abatement or control processes can be generally classified into two types: (1) the effective control or elimination of acid causing reactions within the mine, and/or (2) the reduction or prevention of water flow into and out of the mine. Recognizing the fact that these two types may be directly inter-related, this paper will, for the purposes of clarity and simplification, discuss each separately.

Jan 1, 1973

By Y. Luo, S. S. Peng

Based on the concept of slope-stability analysis, a formula for determining an important parameter required in the mathematical model for the prediction of mining subsidence in hilly terrain is proposed. The slope geometry and the physical and mechanical properties of the soil at the surface of the natural slope can all be considered in the formula. Incorporation of this new formula into an existing mathematical model provides an integrated approach for the study of ground movement in hilly regions.

Jan 1, 2000

By Andy Thompson, Frank Perrone

"As part of the Metropolitan Transportation Authority’s $10.5bn East Side Access Project in New York, 3,200 m of tunnel had to be constructed in rock, mix face and soft ground conditions beneath one of the largest passenger railroad junctions in North America, handling over 780 trains per day. The use of risk based decision making tools was essential in developing the bespoke contract framework that was adopted as well as making informed decisions once excavation commenced. This paper will outline the risk management process adopted, discuss the risks and mitigation strategies adopted and comment on the impacts of this approach on the as built Project cost and schedule. In particular, the paper will outline the unique approach used to establish the baseline against which the Contractors performance would be measured as the selection of a Slurry TBM to excavate the tunnels was considered to compromise the effective use of a Geotechnical Baseline Report. BACKGROUND AND CHALLENGES Contract CQ031, Queens bored Tunnels and Structures was awarded in September 2009 to a joint venture of Granite Northeast/Traylor Brothers/Frontier Kemper (GTF JV) for $717.6m following a negotiated procurement process. A robust approach was taken with regard to the management and payment for risks associated with the construction of these tunnels. Risk assessments were carried out during the design phase and a risk register was developed prior to procurement. During the procurement phase close attention was paid to ensuring that the allocation and pricing of known risks, together with mechanisms for managing future risks were clearly defined between the MTA and GTF JV.In comparison to the excavation work in Manhattan, which was performed in competent hard Manhattan schist, the tunnels in Queens were excavated predominantly through soft ground with a high water table and complex environmental conditions. Not only did this require the use of pressurized face TBM technology, a first in New York, but also a re-evaluation of the contractual mechanisms used to manage the hard rock excavation contracts for their appropriateness to the soft ground tunnel work."

Jan 1, 2016

By PATRICK R. TAYLOR, NICHOLAS BELLUSCI, D. ERIK SPILLER, VICTOR BRAMAN

Most of the world’s production of natural soda ash comes from the mining and processing of trona found near Green River, WY. The processing of trona ores to ultimately yield a high-quality dense soda ash product and reject the insoluble gangue species, primarily in the form of oil shale, is water and energy intensive. It is speculated, however, that the glass-manufacturing industry, which is the largest consumer of soda ash, may be able to use product of a lower grade and consistent level of the insoluble constituents. Thus, the viability of using sensor-based sorting to produce a beneficiated trona stream that would be fed to calcination was investigated. The study encompassed the preparation of a run-of-mine (ROM) Green River ore sample; selection of specimens sized 25 to 75 mm; imaging of the specimens by sensors based on X-ray transmission (XRT), color and laser-induced fluorescence (LIF); insolubles analysis of the specimens; and a bench-scale sorting test. Results of the study established that a correlation between the color of the individual ore particles and their insoluble content exists, and that a surface-detection-based sensor, particularly LIF, is apparently more suitable than XRT to produce a beneficiated trona stream. The bench-scale sorting test demonstrated that a 65 percent separation efficiency and a 70 percent recovery of trona could be achieved.

Feb 1, 2023

By Christian F. III Baiz

Introduction A new mining agenda is before us. Born of government policies and world economies, the years ahead will show reduced growth. Metals, mining, and most other natural resource industries are inflation dependant and capital intensive. For these, a long period of contraction of outmoded and costly capacity will evolve. In some cases, this will be supplanted by new, lower cost capacity. But this will occur only if the cost of production - including cash operating and debt service costs - comes in at or below current market conditions. The industrial outlook for metals mining can be characterized as bearish. A US bank economist said mining companies planning their five-year forecasts should take current market conditions and straight-line them to the end of the decade. With low growth and low inflation, the real price of metals will remain flat or decline slightly. As a result, capital funding will be problematic. The low-cost producer will succeed. That means only the producer with low cash costs and low principal and interest costs per unit of production, will succeed. Gaining a perspective One must look back 30 years to see the evolution of the capital markets, for metal mine financing. This period can be divided into two economic periods. The 1950s were a time of stable economics. Mining companies earned and reported good profits. They had good corporate creditworthiness. In essence, mining companies of the 1950s were highly self-reliant. When equity infusions were needed, they were easily obtained. Financial management kept long-term debt low. Fixed rate, long-term financing was readily available in the long-term bond markets. The commercial banks of the 1950s were rarely used by the mining industry. When necessary, mining companies went to the banks for short-term financing - the kind that was needed for working capital requirements. Changing rhythms In the old rhythm there was an orderly market. Even into the mid-1960s, 75% of world annual copper production was controlled by eight companies: two in the UK, one in Belgium, and five in the US. During times of poor market demand, these producers would control supplies to the market. They took their losses out of retained earnings. Capital was easily restored during the ensuing good times. The new rhythm called for copper to be an economic means to a political end. Third World copper producers brushed aside the market fundamentals of commodity economics. Yet, the political solutions of these countries - their lack of response to the market - have seldom achieved their original objectives. Each commodity has its own old and new rhythm. Aluminum may have a similar rhythm, coming 10 to 20 years later than copper. By the late 1960s, changes were occurring. Inflation was on the rise. Ore reserve quality was falling. As a result, capital expenditures were necessary to maintain existing output. These costs created an increase in corporate leverage, thus adding to inflation and rising interest rates. Indicators A comparison of the gross national product (GNP) deflator index, consumer price index, and the metal mining deflator index is instructive. (Fig. 1 and Table 1). With 1972 equal to 1, note that the metal mining deflator reached its lowest point in 1967. From that point, the metal mining deflator has accelerated severely for 16 years. Only two minor downturns occurred during the business recessions of the mid-1970s and the early 1980s. In essence, Fig. 1 shows that while GNP has grown modestly, a miner's dollar in 1972 would require $3.48 in 1980. This is an almost 17% compounded growth rate over that eight-year period. Beginning in the late 1960s, for the first time in mine financing, the risk of success shifted from the corporate balance sheet to third parties. Limited-resource financings were taken up by banking syndicates that accepted certain of these risks. The lender needed to be well acquainted with the types of risks to be evaluated. These include resource quality and quantity, construction and completion, capital and operations costs, market risks, force majeure, and political and exchange rate risks. Project financings became the basis whereby mining companies were able to maintain their borrowing capacities. In essence, the lender was willing to share some of the project risk while only receiving lenders' returns on these investments. Over the last two decades, mineral project financings have become highly complex transactions involving multicurrency, multi-

Jan 8, 1985

By André Vervoort

After the systematic closure of Europe’s coalfields in the late twentieth century, the emphasis is now clearly on industry’s environmental legacy. One aspect of the latter is the longterm surface movement above abandoned coal mines. The analysis of satellite data shows that the subsidence lasts longer than generally assumed. However, a few years after the flooding of the abandoned underground coal mines, a new phenomenon was observed, i.e., the direction of the surface movement was reversed. The phase of upsidence has already lasted for several decades, and only future measurements will tell how long it continues. A key conclusion is that the regions with maximum subsidence do not necessarily correspond to the greatest upsidence. In other words, buildings and infrastructure are subjected to a different loading from this upsidence than during the subsidence phase. The longterm surface movements have an impact on vulnerable structures in the densely populated regions of the former deep coal mining areas in Europe. These movements create additional damage. This new knowledge is also relevant for mines that are still in operation or future mines that are planned.

Feb 1, 2024

By Duk-Won Park

A new gage for monitoring fractures in underground openings was successfully developed utilizing the reflection photo-elastic technique. The gage may be used to detect crack initiation in mine openings or tunnels so that remedial action may be taken to prevent further deterioration. Fringes concentrated around the cracks were spread by the use of rubber backing. Crack growth as little as 0.003 inch up to as much as 0.1 inch width were detected in this study. Variation of gage materials will provide alternative ranges. The feasibility of the method was tested and calibration was made in the laboratory study. Field study successfully demonstrated the capability of applications in detecting mine roof crack development.

Jan 1, 1982

By Stephen H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, New Mexico area. The first four shafts sunk at international Minerals and Chemical Corporation's property have been located in competent and essentially dry conditions, while other shafts on adjacent properties have had such adverse conditions that ground freezing has been chosen as the water and ground control technique for shaft sinking. At the location of the IMC No. 5 Shaft there has been extensive-erosion and salt dissolution in the Rustler Formation which has led to collapse of some zones of the strata. Both ground freezing and pregrouting were considered as alternative methods of stabilizing the extremely poor ground conditions and controlling the potentially very heavy water inflows it was decided that pregrouting the shaft was feasible and would offer substantial cost and time saving over a ground freezing technique. This paper describes the pregrouting techniques used and illustrates the requirement for flexibility in a grouting program so that it can be codified to reflect any new or additional information which is obtained during the progress of the grouting.

Jan 1, 1984

By Gary S. Brierley, John W. Critchfield

This paper is a case history of a subsurface exploration program conducted for a system of sewer tunnels in upstate New York. The focus of the discussion is a non-technical outline of how the exploration process was organized to efficiently produce a large body of geological and geotechnical data. A brief description of the project and geological setting is provided, the scope of the exploration program is summarized, the logistics of collecting, processing and reporting subsurface data is outlined, and recommendations for management of explorations applicable to any rock tunnel are provided.

Jan 1, 1983

By Gary P. Marshall, Jeffery S. Thompson, Robert E. Jenkins

The effectiveness of the new DuPont Passivation Technology in eliminating acid generation from iron sulfides is presented. Passivation is achieved by treatment with a dilute basic perman­ganate solution. This treatment produces a thin impervious layer of iron/manganese oxide on the sulfide surface, providing a bar­rier to the environment so that the sulfide is not available for undesirable reactions such as the production of acid.

Jan 1, 1998

By I. Weir-Jones

[Currently the cost of carrying out 'in situ' geotechnical investigation programmes or installing and operating monitoring systems at construction or mining sites is rising var." rapidly. This is primarily because of our ever increasing labour rates. As a result of this problem efforts are no,, being made develop techniques for the economical; collection of large quantities of geotechnical data relating, to such problems as done stability evaluation, the behaviour of underground openings, or 'in situ' testing procedures. The efforts to reduce the labour content. are particularly apparent in those procedures which have traditionally been manpower intensive e.g. 'in situ' permeability testing where an entire drilling crew and their associated eguipment have been on standby while testis has been carried out; or data collection in underground construction operations where much tine is typically wasted obtaining or maintaining access to instrument sites. In an attempt to illustrate one specialist consulting company's approach to the problem of reducing investigation costs, this rarer examines four recent developments in the field of geotechnical investigation and monitoring which have come about during the last two Years as a result of cur research and development programme. Although these techniques and devices have been developed for specific projects, they all have broad applications in the geotechnical field and they are indicative of the direction in which this company feels developments will take place.]

Jan 1, 1975

By Gerald P. Kelton

Hydrocyclones have emerged as successful classification devices In closed circuit grinding applications However, their use for ultrafine particles separation is a relatively new application For ultrafine particles separation In small diameter (51 mm or smaller) cyclones, the cyclone diameter, feed pulp density or viscosity, pressure drop, and configuration play an important role Most often commercial application of the small diameter cyclones suffers from plugging problems resulting from the presence of fibres, wood chips, paper scraps, etc This paper describes important design features of small cyclones, followed by examples of case studies of commercial application of these cyclones

Jan 1, 1983

By M. Tapper

If one considers that prehistoric man's first house may have been a limestone cave, calcium carbonate may be the most timeless of all building materials. Fanciful history aside, CaCO3 has been used for countless applications in human habitats. After all, tine marble block and tiles have always been the hallmark of eloquents and style. Mortars and cements derived from limestone have held together the very blocks of our civilization. In modem times, synthetic polymers are blended with ground limestone to produce everything from pipe, floor tile, cultured marble and house siding. All of these miracles of our technology contain CacO3 of various sizes and in varying amounts. This paper will discuss some of the critical attributes of CaCO3 which make it suitable for the new building products that have helped increase our standard of living. The vehicle of discussion will be a residential, single family house.

Jan 1, 1993

By S. Gupta

Froth flotation is a process commonly employed for the selective separation of phosphate from unwanted mineral. Column flotation has become widely accepted in the mineral processing industry, including phosphate industries, due to its ability to improve selectivity, lower operating cost, lower capital cost, and superior control. In this work, a hybrid model is developed that combines a physicochemical model with artificial neural networks. The physicochemical model is based on axial dispersion with first order collection rates. A new approach, in which both frankolite (the desired mineral containing phosphate) and gangue (undesired product) are modeled, enables prediction of grade of the recovered product. Thus, two basic parameters are required in this model: flotation rate constants for frankolite and gangue. Artificial neural networks are used to predict flotation rate constants. The model also takes into account the particle size distribution and predicts grade and recovery for each particle size range. The model then combines grade and recovery for each particle size range to determine the overall grade and recovery of the column. The model is validated against laboratory column data.

Jan 1, 1998

By Richard Giffen, Martha Gross, Luca Pellegrini, Pa Ousman Njie

The Hampton Roads Bridge-Tunnel (HRBT) Expansion project in Virginia includes parallel 1.5- mile (2.4 km) tunnels constructed using a tunnel boring machine (TBM). The TBM launching and receiving shafts were excavated within the footprint of two reclaimed islands abutting the navigation channel for the Port of Virginia. The shaft excavations—a circular tri-cell shaft at South Island, and a circular-rectangular twin-cell shaft at North Island—were supported by slurry walls up to 190 feet (58 meters) below the island surfaces. This paper describes specic design considerations for these shafts, as well as construction and uality-oversight aspects of their excavation and construction.

Jun 23, 2024

By Bernard F. Anderson

INTRODUCTION In this chapter, the term "down-the-hole drill" (DTH drill) is used as a generic name that encompasses the various trade names and other references such as "downhole drill," "in-the-hole drill," etc. This chapter is limited to a description of DTH drills used in stoping large underground ore bodies. DTH drills differ from conventional drills by virtue of the placement of the drill in the drill string. The DTH drill follows immediately behind the bit into the hole, rather than remaining on the feed as with ordinary drifters. Thus, no energy is dissipated through the steel or couplings, and the penetration rate is nearly constant, regardless of the depth of the hole. Since the drill must operate on compressed air and tolerates only small amounts of water, cuttings are flushed either by air with water-mist injection or by standard mine air with a dust collector at the collar. HISTORICAL DEVELOPMENT Mine managers have long known the economies enjoyed by quarry and open-pit operators in producing large quantities of ore. The savings are due primarily to the availability of massive equipment, capable of drilling large blastholes to reduce the amount of drilling, increase the fragmentation, reduce secondary blasting, and im¬prove the flow of the product. In an attempt to reduce underground mining costs, various methods are used for long-hole drilling, includ¬ing standard pneumatic percussion drifters and diamond drills. These systems have their shortcomings; percus¬sion drills are limited to small hole sizes and they ex¬perience excessive deviation and significant loss of energy with increased depth. The diamond drills provide deeper and straighter holes, but only at high cost. Both systems suffer from high noise levels, low penetration rates, and poor explosives distribution, among other problems. When the mining companies approached the drill manufacturers for a compact and portable large-hole jumbo for underground use, they specified not more than 1 % deviation on 60 m (200 ft) of vertical hole and a penetration rate of 15 m/h (50 fph). On Dec. 23, 1960, a test unit was placed in service in Montana and met the performance criteria. Though lacking the so¬phisticated features available today, the economies of surface blasting were brought underground. Unfortunately, the first system did not gain immedi¬ate acceptance in the industry. Among the factors con¬tributing to its demise were resistance to change, the need to alter development methods for the ore bodies, and a lack of flexibility in moving the rig from setup to setup and from level to level. In 1972, the mining industry again challenged the drill manufacturers to provide a workable jumbo that would combine compactness, ease of maintenance, relia¬bility, and efficiency, all on a self-propelled chassis. The manufacturers responded by providing improved jumbos, which have been accepted with enthusiasm throughout the mining industry. Today's DTH jumbos are capable of drilling from 100 to 200 mm (4 to 8 in.) diam holes that can be reamed to even larger diameters. The holes can be drilled to depths of 150 m (500 ft), depending upon ground conditions and the capability of the jumbo to retrieve the steel and drill. Fig. 1 illustrates a typical DTH jumbo. APPLICATIONS The uses to which DTH drill jumbos have been put are quite numerous, with new uses being found regularly. For convenience, these uses may be classified as primary blastholes and nonblasting holes. Primary Blastholes The original purpose for the development of the DTH jumbo was for drilling primary blastholes that could be mined by open-stope methods. Prior to the advent of the DTH jumbo, extensive development was required before production drilling could begin. Sub¬levels were required to allow access for column-and-arm stopers or ring/fan jumbos, to the extent necessary based on the effective penetration of the chosen machine. With the DTH jumbo, the mine engineer is able to reduce preproduction time and development costs. How¬ever, the most significant saving results from an im¬proved cost per ton of broken ore in the production phase. To utilize a DTH system, only a top heading and drawpoints are necessary. The top heading can be the width of the ore body with a 3.7-m (12-ft) back. A drop-raise pattern is drilled and shot to begin the stoping operation, providing a free face for subsequent blasting. A typical layout is illustrated in Fig. 2. The advantages of this system include: 1) Drilling and blasting are independent operations, and blasting can be performed at a rate congruous with the mine's ton-per-day capacity. 2) The development layout is simplified. 3) Good explosive distribution is achieved, provid¬ing more uniform fragmentation. 4) Environmental conditions for operators are im¬proved, including improved safety with all work directed downward (not overhead), lower noise levels, little fog, and a reduced dust count. 5) Improved production per manshift. 6) Simplified and easier operator work cycles. 7) Reduced cost per ton of product. 8) Fewer holes lost due to ground shifts. Nonblasting Holes With the introduction of the compact DTH jumbos, other practical uses became apparent, including the drilling of: 1) Holes for sand fill, from level to level and from level to stope. 2) Drain and dewatering holes. 3) Power and communications cable holes.

Jan 1, 1982

By Dan Walker

The success of the heap leaching process for extracting precious metals from low grade ores in many cases depends on successful agglomeration of clay fines. This paper relates the development of a new agglomera­tion agent, named Leachit, that has demon­strated an ability in some ores to decrease leaching time. Data from a commercial test­ing laboratory is presented to illustrate a comparison of leaching efficiencies with other agglomerative agents, such as lime and portland cement. Conclusions will point out certain advantages of Leachit to the heap leaching gold recovery industry.

Jan 1, 1992

By Jan A. Nemcik

Steel mesh has been used successfully for many years to control friable roof conditions and prevent loose roof and rib material from caving into the roadway. Despite its extensive use, the installation of steel mesh is difficult to automate and many other products have been evaluated as an alternative for skin control. Ideally, the properties of these new products should be similar or better than those of the steel mesh. In particular, development of a strong and resistant shell that minimizes movement along the fractured rock and coal surfaces between the bolt anchors is recommended. A strong surface adhesion and the strength of a reinforced polymer skin can provide the necessary toughening mechanism required to enhance roadway surface support by forming a reinforced polymer/rock surface layer. Most of the Thin Spray-on Liners (TSL) evaluated in the mines are weak with slow curing times, and the plastic mesh currently used to support the coal ribs is relatively weak. Therefore, neither material can seriously compete with steel mesh. Currently, a new polymer product that cures in seconds and forms an instantaneous strata binder that surpasses the properties of steel mesh is under development at the University of Wollongong.

Jan 1, 2009

By Russell K. McFarland, Eugene L. Foster

INTRODUCTION The U. S. Department of Transportation has underway an important new program which will have a major impact on rapid excavation technology. The Transportation Tunneling Program, as it is called, is a coordinated, multi-modal research and development effort. Its goals, if realized, will significantly improve our ability to build the underground structures needed for transportation. This, in turn, will improve transport efficiency, environmental impact, and the energy consumption associated with the movement of people and goods. Tunneling technology research and development had its beginning at the Department of Transportation in the Office of High Speed Ground Transportation (OHSGT). The OHSGT developed and implemented a program in 1965 to provide the technology for underground construction needed to support future high speed ground transportation. In 1967, when the OHSGT was transferred from the Department of Commerce to the Federal Railroad Administration (FRA), the program accompanied that office. The thrust of the FRA program has been cost reduction through the development of new materials, innovative designs, and better construction methods. During the late 1960's and early 1970's, other developments were underway which would influence the future of tunneling research at the Department of Transportation. An ad hoc

Jan 1, 1974

By G. Ansong, P. K. Achireko

The authors present a new mineral price model, compare it with time series and naive models, and analyze the effects of the forecasting models on mineral project evaluation. Mineral commodity prices are volatile, which means that the results of evaluation tools that do not treat the stochasticity of metal prices rigorously may be misleading. But, in mine valuation, commodity price forecasts are required to assess the economic viability of a project. In this study, a new mineral forecasting method, called the MNDRVG-MFNN-RM model, which incorporates randomness, neural networks and regression models, is introduced. The MNDRVG-MFNN-RM model, a naive method and time series model were used to forecast gold prices for two successive years for the evaluation of a proposed open-pit mine. The MNDRVG-MFNN-RM model yielded the best results among the three methods. It produced the true optimum pit limits and an optimum pit value slightly less than the true optimum value. The main novelty of the methodology is the simulation and rigorous analysis of the randomness property associated with mineral prices to reduce the estimation and forecast errors, an important contribution to mineral venture evaluation, mine planning and design.

Jan 1, 2000