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By F. W. Brackebusch

A unique machine has been designed for mining narrow veins. The machine, called the NONN, walks on the walls of the stope and carries a boom-mounted hydraulic impact breaker. The concept of walking on the walls allows an existing muck handling system such as LHDs to operate beneath the NOMN. The NOMM has four sets of legs which can be manipulated independently or concurrently to cause the carrier to walk in any direction and to turn sharp corners. The mining rate using the breasting method is targeted to be 25 t/hr.

Jan 1, 1990

By J. J. Whittaker

Zaldivar is an open pit copper mine operation located in the Atacama Desert, in northern Chile. The plant produces Cu cathodes using 4 solvent extraction trains. The plant was started up May 1995. Since 1996 the plant has been using on-stream analyzers based on X-ray fluorescence and titration for process monitoring and control. Elemental analyzer alone is not able to provide the critical information for plant operation, it has to be complemented by on-stream titrators integrated to one sampling system. The analyzers are located in a prefabricated shelter. The analyzer system project, operation and performance issues are the main topic of this paper.

Jan 1, 1999

By R. C. Freas

The physical and chemical properties of mica are unique relative to most other industrial minerals. As such, mica is suitable for a variety of functional applications in new and emerging markets. This paper examines some of these applications and particularly the contribution mica makes in end product performance.

Jan 1, 1997

By J. A. Lombardi

"EXECUTIVE SUMMARY The use of membranes for the treatment of Acid-Mine-Drainage (AMD) water has been a 35 year mining industry quest that has only recently produced commercial scale Zero-Liquid-Discharge (ZLD) plants. The process of development of the membrane treatment of AMD has been defined by the water treatment industry’s efforts to control gypsum scaling of the membranes, an artifact of the concentration of calcium and sulfate ions on the concentrate or “brine” side of the membranes. Improved anti-scalants, changes to membrane surface geometry and a lowered permeate flux rate were all part of solving the calcium sulfate (gypsum) scale formation problem. Whether used singly or as part of a multi-stage membrane treatment process, the production of “left over” membrane concentrate or brine, in any volume large or small, was a second barrier to adoption of the method by the mining industry. The two identified “final brine” treatments were a) solar evaporation ponds and b) mechanical evaporators. Brine disposal by solar means is typically site limited to flat terrains or high net evaporation locations. Mechanical evaporation-crystallization is applicable at all sites but, typically, at onerously high ownership and operating costs. Miwatek, a South African water treatment start-up, has entered the mining AMD ZLD marketplace with two new, pilot-scale tested, processes, both of which are predicated on the innovative treatment of a reasonably concentrated AMD and neither of which produces a final brine that requires disposal. In the Miwatek Brine Treatment, MBT, method the membrane brine is caustic pH adjusted and de-calcified precedent to passage through a second membrane plant. The caustic is generated on-site by a lime treatment of the second-membrane concentrate. The first- and second-stage permeates are blended for discharge. The process usually yields no “final brine” for disposal. In the Miwatek Ettringite Treatment, MET, method a low pH first-stage membrane brine is lime treated in two or three steps in the presence of aluminum in a way that metal hydroxide and calcium sulfate solids are formed and purged from the system. Sufficient aluminum is often present in the feed water to, with judicious recycling, enable operation of the lime-aluminum treatment without the purchase of outside aluminum reagent. The first-stage membrane permeate is blended with the lime-aluminum treated membrane concentrate for discharge. The indications are that the method can comfortably meet the low 250 -500 ppm SO4 discharge water quality standards that have most recently been proposed in South America. The process yields no “final brine” that requires disposal. Projected own-operate costs for the MBT and MET systems are less than the estimated costs for all identified alternative treatments."

Jan 1, 2015

By FJ. Johnson

Polymer utilization has increased steadily over the past several decades; however, their usefulness is sometimes limited by natural forces. For example, polymers tend to degrade when subjected to elevated temperatures. This degradation can release toxic fumes, create excess smoke, and aid in the spread of fire. For these reasons, many polymers are filled with various compounds which impart flame retardancy (FR) properties. These fillers do not make polymers non-combustible; rather, they increase resistance to ignition and reduce bum rate. Also, they suppress smoke generation, which is important as up to 80% of fire-related deaths are due to smoke inhalation [1]. Therefore, methods to impart flame retardancy in polymers are industrially important. The early flame retardants used in polymers were halogen-based, working on the principle of inhibiting free radical formation in the vapour phase thus impeding combustion propagation [2]. Usually these were combined with antimony compounds such as Sb203 to decrease loading, yet provide the same FR qualities. However, questions have arisen recently concerning toxicity of halogenated flame retardants. Possible release of toxic compounds (such as dioxins) upon combustion has been reported [3]. Fear of future regulations concerning halogen addition has led to the search for different FR fillers. Two of the more common replacements for halogen-based systems are alumina trihydrate (Al(OH)3 or ATH), and magnesium hydroxide (Mg(OH)2)' These systems impart flame retardancy through heat absorption and by release of water of hydration upon their decomposition. ATH has a low decomposition temperature (230°C), limiting its use to unsaturated polymers, epoxies, urethanes, and some wire and cable formulations. However, some advantages of ATH over halogenated FR are that it is relatively cheap, doesn't generate toxic gases, is non-volatile, and is impervious to moisture [2].

Jan 1, 1997

By Remo Grandori

"INTRODUCTIONDouble Shield TBMs were introduced in the market in the early seventies with three main targets:• Increase the TBM performances in term of advance per day thanks to the ability to erect a segmental lining simultaneously with the excavation phase.• Be able to advance through unstable and disturbed rocks under the protection of the shields• Provide a finished tunnel by installing a precast lining as the TBM advance.In 2003 SELI developed the design of the Double Shield Universal (DSU) TBM as an evolution of the original Double Shield TBM design.This new TBM design was targeted to improve: the TBM capability to advance through squeezing/converging rock formations under high cover, the telescopic joint design (allowing by such to operate the machine in double shield mode in very weak rock), the capability of the TBM to investigate and treat the ground around and ahead of the tunnel face.In the same lapse of time Single Shield TBMs, originally utilized for soft ground tunnelling, extended progressively their range of application to mix rocks and finally to hard rock tunnelling with increasing performances.This also thanks to the substantial reduction in the installation time of the segmental lining ring that contributed to minimize the TBM stand by time between two consecutive boring strokes.Today the choice between the two types of TBMs needs to be carefully evaluated project by project since one type of TBM may “prevail” in certain geologies and diameters and vice versa.THE VISHNUGAD PIPALKOTI TUNNELThe Vishnugad Pipalkoti Tunnel is part of the 444 MW Vishnugad Pipalkoti Hydro Electric Project (VPHEP) on Alaknanda river in Uttarakhand (India).The Owner is the Indian electric company “Tehry Hydro Development Corporation” (THDC) and the World Bank finances the project.The Headrace Tunnel total length is 13.4 Km and a section of about 12,3km will be excavated by TBM by SELI Overseas (Italy) in subcontract to HCC (India) the General Contractor for the project. The TBM will be delivered ex workshop in March 2016 and it is foreseen to start boring in the second half of 2016.Figure 1 below shows the location of the project and the following Table 1 summarizes the geometrical characteristics of the TBM tunnel."

Jan 1, 2016

By R. Debkowski

The current underground infrastructure of an old monumental salt mine along with using it as a tourist, museum, nature, resort, conference and cultural events place is presented in the paper. At present, mainly in the monumental part of mine, only a small part of the historical chambers, which together with galleries form a tourist route available to visitors. Moreover, the essential activities aimed to make the tourist route more attractive and to change the decor of the underground sites are discussed.

Jan 1, 2006

By Halter L. Gould

Since the turn of the century there has been a marked increase in population, industrial and economic growth, and in energy requirements in the United States. During this time our energy needs have been met largely by natural gas and petroleum, but as our reserves of these materials are depleted, we are going to depend more and more on our large reserves of coal. The mining of coal for electrical power production has increased at a rapid rate during the past decade. Over half the coal produced in the United States in 1971 came from mines utilizing surface mining operations (Paone, et al, 1974). Surface mining is expected to increase as the rising cost of oil places more demand on coal for energy. About 57 percent of the coal reserves in the United States lie in the area west of the 100th meridian. About one-quarter of this can be mined by current surface methods. This would involve the disturbance of approximately 1.5 million acres (600,000 hectares). By the year 2000, projections indicate disturbance of about 200,000 acres, or 300 square miles, in the West. Mined areas receiving more than 250 mm of annual precipitation can usually be revegetated without irrigation if the spoils are properly shaped, the surface layer consists of suitable plant growth media, and proven techniques in rehabilitating disturbed rangeland are applied. Areas receiving less than 250 mm of annual rainfall or with high evapotranspiration rates pose a more difficult problem. Revegetation of these areas can probably be accomplished only with major inputs of water and good management (National Academy of Science, 1974).

Jan 1, 1978

By J. Stachulak

This paper deals with theoretical considerations and practical applications of ventilation network calculations, based on mass flow rates and performed by computer simulation in our deepest operating mine - Creighton. The paper also deals with natural ventilation. In the usually accepted air-flow theory, the air is assumed to behave like an incompresssible medium. This introduces considerable error where temperature and pressure changes are great. Therefore, any study of the air flow in deep mines, must take into account compressibility. Basing ventilation calculations on mass flow allows a distinction to be made between air leakage and such quantity changes which occur due to air density changes. The energy which is required to convey one pound of air through a mine can be obtained by adding all head losses hL (ft-lb) of the ventilation paths through which the air flows. However, this total energy will not be correctly expressed in a compressible fluid by summing all pressure losses PL = hL x d (ft-lb/ft3 = lb/ft2) d = density. There is a law of mass conservation, but no law of volume conservation. Natural ventilation is caused by the conversion of heat into mechanical energy and not by the difference in upcast and downcast densities, as often believed. In an existing mine natural ventilation can be determined correctly by plotting a pressure volume diagram and measuring the area ? [ ] vdP = hN, where v = specific volume, or by measuring the sum of all friction losses and work provided by a fan. These procedures are tedious. The natural ventilation head (hN) can be approximated by the equaticn hN =[ ] tdZ. Where T is the average absolute temperature, t air temperature and Z elevation. In Prof. R. Greuer's computer program this determination of hN is automatically done for every mesh of the network.

Jan 1, 1980

By Luciano Ramos, Daniel Santos

Igarape Bahia Mine, which is currently the largest gold producer in Brazil, belongs to Companhia Vale do Rio Doce - CVRD and is situated 250 miles south of Belem, state of Para, Brazil. It came into operation in 1992 with the startup of the CIP plant, fed with high grade ore, presently at 3.4gAu/t. The ore is totally oxidized, containing extremely fine particles of free gold. The ore is soft and low cyanide consumer, with a maximum work index of 12kwh/sht. In 1993 a Heap Leaching Plant was set into operation, handling low grade ore of · 1.s g Ault. The Heap Leaching Plant has undergone two major expansions. In 1994 its capacity was raised from lMtpy to 2,2Mtpy and in 1998, with a thorough remodeling of crushing operations, it was raised again to 3.5Mtpy. The CIP plant, which was originally designed with a capacity for l. lMtpy of ore, was expanded to a 2.2Mtpy capacity in 1994. Presently, the CIP plant accounts for most of Igarape Bahia's total gold output, with approximately 220,000oz per year. Igarape Bahia's annual output is around 360.000 oz. Over the last three years, work has been intensified to improve performance of both processes, aiming at maximizing productivity of the two industrial plants. Reduced costs and increased revenues have been given a special emphasis in the unified improvement program. Cost · reduction has involved developing methodologies to rationalize consumption of materials and inputs, while increased productivity has been given top priority as a means of generating increasing revenues. Thus, all of the improvement and development efforts have had a common goal: to increase operating income.

Jan 1, 2000

By A J. Jonaitis

The DENVER Tube Press is a simple, high pressure (1500 PSI (100 bar» filtration unit, developed for processing difficult-to-dewater materials and to produce a handleable filter cake and clear filtrate product. Lab and pilot testwork conducted in Australia on coal fines (55-70\ -35 micron (400 mesh)) have shown that total moisture contents of less than 20\ are consistently achieved in the final cake products from the Tube Press. Currently, these coal super fines are sent to waste due to uneconomical mechanical dewatering methods, which were only able to reduce total moisture levels in excess of 30%. Calculated, throughput rates for the 500 Series Tube Press exceeded 1700 kg/hr (3750 lbs/hr). Feed solids concentration requirements are between 45 and 50\ to achieve these results.

Jan 1, 1993

A Mark IV surface force apparatus (SF A) was used to conduct direct force measurements in dodecylamine hydrogenchloride collector solution between mica surfaces at varying pHs. It has been found that the long-range hydrophobic forces reach a maximum at pH 9.5, which also corresponds to the maxima attained by the contact angle and flotation recovery of quartz. The charge densities are comparable on both mica and quartz surfaces (0.40-0.48 run2), making it possible to draw conclusions on the flotation of quartz from the direct force measurements conducted on mica. Therefore, it may be suggested that the maximum flotation recovery of quartz m the range of pH 8.0-10.3 may be attributed to the appearance of long-range hydrophobic force, which in turn can be related to the formation of a close-packed monolayer (or hemimicelle) in the presence of neutral amines formed as a result of hydrolysis.

Jan 1, 1996

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By J. H. Daniel

Dust-related respiratory disease remains the major health concern in mining, and health agencies are proposing more stringent standards. The U.S. Bureau of Mines (USBM) is investigating techniques to continuously monitor respirable dust in real-time during the coal or ore extraction process. Continuous monitoring will allow mine operators to evaluate hazardous dust concentrations and adjust the operations to produce less dust. Mine instrumentation applications include machine-mounted and hand-held monitors, personal monitors, and area/environmental monitors. Six dust detection methods have been considered to meet application requirements. These are: light-scattering instruments, a smoke-particle detection technique, correlation of pressure drop across the collection filter with amount of dust deposited, the Tapered-Element Oscillating Microbalance (TEOM) instrument, a method that relates the amount of dust collected on a filter with the vibration of the filter, and beta attenuation measurement of dust. Studies to date have identified the TEOM instrument and the technique of correlating the amount of dust collected with the vibration ofthe filter as having the most promise for success. Development of the machine-mounted monitor is the highest research priority. The application options and progress to date in developing continuous monitoring instrumentation are presented.

Jan 1, 1995

By Kang-Hyun Lee, In-Mo Lee, Byung-Kyu Kim, Parkm Jinho, Seoung-Won Lee

"In this study, the TBM Resistivity Prediction (TRP) system is developed for predicting the location, thickness, permittivity ratio and electrical conductivity of anomalous zones ahead of tunnel face using the measured resistivity of the ground. The applicability of the developed system was verified by performing field tests at a construction site in which an EPB-shield TBM is used for tunnelling work. In the first field test, it was found that the rock around the tunnel face had the same resistivity and permittivity with the rock ahead of the tunnel face indicating no anomaly ahead of the tunnel face. In the second test, a stronger zone 5-m thick was predicted ahead of the tunnel face based on lower permittivity than that of the rock around the tunnel face. The ground condition assessed by the newly developed TRP system matched well with that either predicted from geophysical exploration or directly obtained from drilling boreholes or from daily observed muck conditions. INTRODUCTION During tunneling work, the emergence of unpredicted zones of relatively weaker or stronger ground can lead to delays in construction work or an increase of construction cost. Predicting anomalous zones ahead of tunnel face in advance can thus prevent time and economic loss. For these reasons, various methods to predict the ground condition ahead of the tunnel face have been studied and developed. Prediction methods using various kinds of equipment include tunnel seismic prediction, ground penetrating radar, electromagnetic surveys based on electronic antennas, and electrical resistivity surveys conducted by analyzing electric currents in the ground ahead of the tunnel face (Ryu et al. 2008). However, most of the prediction methods are only applicable to conventional tunneling job sites, which feature free access to the tunnel face. In mechanized tunneling projects, accessibility to the tunnel face is very limited because the tunnel face is occupied by the TBM."

Jan 1, 2016

By Jackson G. Jenkins

Magma Copper Company's San Manuel SX-EW facility has operated since May, 1986. The original facility had a design capacity of 25,000 tons per year of electrowon copper cathode produced by processing pregnant leach solution from an open pit/heap leach operation. In 1988, the plant was expanded to 50,000 tons per year to incorporate processing in-situ leach solutions. This paper focuses primarily on the heap leaching area with regard to exploration, testing, feasibility, permitting, design and construction, and operating practices. Research utilizing surfactant leaching aids to enhance copper recovery is also discussed.

Jan 1, 1993

By S. G. Axen

Design of wells for in-situ leaching is based on individual mining operation and ore deposit requirements. Major design considerations are well flowrate, depth, fluid composition, expected well life, mine operating plan and cost. A large variety of downhole equipment, materials of construction, contract services and methods of well completion and stimulation are available. A generalized design procedure which allows the engineer to optimize well design for a particular ISL application is described.

Jan 1, 1988

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By L. Alagha, O. Molatlhegi, S. Khatibi

"In the present study, the effect of organic/inorganic (hybrid) polyacrylamide polymer on fine coal flotation was investigated. Raw coal samples contain about 37% of ash-forming mineral at a feed size of -75 + 38 um were subjected to flotation tests in the presence of in-house synthesized hybrid Al(OH)3-PAM at different polymer dosages and pH values. Results show a significant improvement in both combustible recovery and ash rejection at 1 ppm polymer dosage. Further improvement of combustible recovery was obtained when flotation was performed at pH 5. Interfacial properties of coal particles before and after flotation were examined through electrokinetic (zeta potential) measurements of coal/water slurries. Zeta potential vs. pH curve were established and compared. In the case of raw coal/water slurry, zeta potential-pH curve resembles the ash-forming minerals (silica and clays) more than coal. After Al(OH)3-PAM-assisted flotation, the zeta potential of froth/water slurry shifted to more positive values point which strongly indicates significant removal of ash-forming minerals from coal by Al(OH)3-PAM. INTRODUCTION Coal has been a major commodity in meeting the world energy demand during the past several decades (Milici et al., 2013). According to the international energy agency, global coal demand will continue to increase for the coming decades. With increasing world population, the global electricity demand would also increase as more people would get access to basic electricity especially in developing countries (Maggio & Cacciola, 2012). Due to this increase in energy consumption, operations in coal mining and beneficiation processes have been highly mechanized to meet the demands. This mechanization has increased the quantity of raw fine coal particles produced which contain high amount of ash-forming mineral matter (slimes). Aplan et al., have reported that the major constituents of ash-forming minerals in U.S.A coal are clay minerals such as kaolinite, montmorillonite and illite (Aplan, 1997). Conventional froth flotation for fine coal cleaning suffers mainly from two major problems: 1) Low recovery of ultrafine coal particles due to slime coating by ash-forming minerals, and 2) The lack of selectivity, which results in the flotation of middlings and entrainment of mineral fines in the froth (Polat et al., 2003). Slime coating on both valuable and air bubbles have been proposed to explain the observed reduction in flotation recovery especially when fine grinding is required. In this case mineral matter may be degraded to extremely fine or colloidal sizes thereby creating difficulty in the water clarification process such as flotation. Slimes inhibit bubble-particle attachment, and increases reagent consumption due to the increase in solid/liquid interfacial area, resulting in low coal recovery."

Jan 1, 2015

By Neil Runciman, Greg Newson, Nick Vagenas

This paper discusses simulation modelling of underground mining operations at a typical mine in the Sudbury mining area in Ontario, Canada. The PC simulation software, WITNESS Version 7 Release 6.0 by AT&T ISTEL, is used to model the drilling, blasting, hauling and ground support operations. Simulation is used to investigate the development mining cycle and determine the capabilities and flexibility of WITNESS to accurately represent the mining system under consideration. The simulation study discussed in this paper provides a first step in determining the successful application of WITNESS in the underground operational aspects of the mining industry.

Jan 1, 1996