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By R. L. Shaw, D. W. Alexander

Consolidation Coal Company's Loveridge Mine operates the only coarse coal hoisting and overland slurry transport system in North America. The system has been in operation since April 1980 and according to current haulage levels will have handled over two million tons by this conference date. Original performance goals have been exceeded. The systems will be described and their application to rapid excavation and tunneling haulage needs will be discussed. Manuscript not received in time for publication.

Jan 1, 1983

Microwave pretreatment can improve grindability by weakening brittle particulate material prior to size reduction. The differential thermal expansion experienced by multiphase materials during rapid heating can also promote damage in the grain-boundary region, which may ultimately translate into enhanced liberation. The effect of microwave pretreatment on the breakage characteristics of different ores has been studied using the Ultrafast Load Cell. The energy accumulated during impact (fracture energy) and the particle stiffness have been measured for untreated and microwaved ore samples. It has been observed that microwave pretreatment can weaken brittle multiphase particulate material, as observed by reductions in fracture energy and increase in damage.

Jan 1, 1996

By J. E. Gebhardt, S. Chander

Significant advances have occurred in the use of electrochemical techniques for sulfide mineral flotation research. The techniques have been used singly or jointly with other characterization methods. When used in combination with other methods, the electrochemical methods provide a means to control the state of oxidation of the surface. Various analytical methods are employed for characterization. The methods that have been used include wetting, x-ray photoelectron and fourier transform infrared spectroscopies. The electrochemical methods include voltammetry and transient electrochemical techniques of galvanostatic polarization and AC impedance spectroscopy. The challenge for the future lies in the utilization of this knowledge in plant operations so as to increase the overall efficiency of flotation separations.

Jan 1, 1989

By Jeffrey M. Listak, Gregory J. Chekan

The U.S. Bureau of Mines, in an effort to improve coal conservation and utilization is currently investigating longwall panel layouts to maximize coal recovery and minimize interactive problems in multiple-seam operations. When longwalling coalbeds in descending order, the transfer of stress from overlying gate roads is a major design constraint affecting pillar stability in the lower mine. The lower mine gate road pillars must be properly designed to withstand the additional load transfer if gate roads are superpositioned in successive seams. The Bureau's MULSIM/NL model was used to analyze load transfer mechanics for superpositioned gate road pillars. Analysis of Longwall Pillar Stability (ALPS), which is an empirically based design method for longwall gate road pillars, was used to calibrate model input parameters. The attributes of both the MULSIM/NL model and ALPS were combined to develop a modified method for estimating pillar stress for multiple-seam cases. The modified method uses a multiple-seam (MS) factor to estimate the stress on the lower mine gate road pillars when superpositioning is practiced. Numerical analysis shows that the MS factor is dependent upon the interburden thickness and pillar width and is presented in a series of graphs relating these two parameters. Several examples are included to illustrate the use of the MS factor for estimating lower mine pillar stress and resulting stability factors.

Jan 1, 1992

By Yves Picot

Construction of new installations was recently completed in the Port of Tubarao, Brazil, With this expansion the port, operated by Companhia Vale do Rio Doce (CVRD), has become the largest iron ore port in the world, with an annual throughput capacity of 60 million long tons. GROWTH OR IRON ORE EXPORTS Since its formation CVRD has steadily increased the shipment of iron ore to overseas markets. Starting with less than 100,000 tons in 1942, the yearly export volume grew to 1,500,000 tons in 1951, 5,000,000 tons in 1961 and 25,000,000 tons in 1971. The number of different grades of ore also increased during this period. Production of high grade pellets, starting in 1970, further increased the number of ore products to be shipped. In the same period the size of ore carriers increased twenty-fold to over 250,000 DWT.

Jan 1, 1974

By D. E. Munson

To assure the safety of a radioactive-waste repository, the performance of the repository must be predicted far into the future. The Waste Isolation Pilot Plant (WIPP) Program is responsible for developing the technology for such performance predictions in bedded salt. An important technology-development activity concerns the, fielding of very large-scale in situ tests to determine the time-dependent deformation of underground openings in salt as a basis for validation of the predictive technology. This technology is necessary to predict repository seal performance and final closure times of rooms and may be of value to the salt and potash mining community, as well.

Jan 1, 1992

By M. Ahmadiantehrani

The concept of hypochlorite treatment prior to cyanidation in the heap leaching of low grade carbonaceous gold ores is discussed. Laboratory column leach tests using a low grade carbonaceous ore were performed to investigate the effects of pH, concentration, hypochlorite consumption, and bed height on the total gold extraction. At high pH, the hypochlorite stability increases and thus, hypochlorite consumption is decreased. At room temperature, the total gold extraction is proportional to the hypochlorite consumption. However, at some point additional hypochlorite consumption does not increase gold extraction. Gold recoveries of 10 and 80 percent are obtained for 12 and 167 lbs/ton hypochlorite consumption, respectively. Increasing hypochlorite concentration increases the rate of extraction. For a given hypochlorite consumption gold extraction was increased by shortening the ore column height. Finally, calcium hypochlorite is more effective than sodium hypochlorite.

Jan 1, 1990

By Michael G. Li

Prediction of acid rock drainage (ARD) for low-sulphide, low-neutralisation potential (LSLNP) mine wastes is methodologically different from that for normal sulphidic mining wastes. In this paper. LSLNP wastes are conveniently defined as those with S2 < 1% and ABA-NP2 < 20 kg CaCO3 eq/t. The distinctiveness of ARD prediction for LSLNP materials originates from their frequently low oxidation rates and is mainly attributable to two reasons. First, the utilisation efficiency of available carbonate neutralisation potential (CNP2) rapidly deteriorates when the sulphide oxidation rate per unit mass of waste drops below a certain level. Reducing the flushing rate of a waste has the same effect as increasing the oxidation rate. Second, silicate neutralisation becomes increasingly important as oxidation rates diminish, and can no longer be ignored in LSLNP materials as it often is for normal sulphidic mine wastes. In this paper, the effects of oxidation rate, pore gas CO2 partial pressure, and flushing rate on ARD prediction for LSLNP materials are theoretically demonstrated with the help of modelling using the computer program MINTEQA2. A new methodology for ARD prediction for LSLNP materials is presented in terms of a prediction procedure. Finally, a case study is given to validate some of theoretical aspects discussed and to illustrate the use of the newly proposed ARD prediction procedure.

Jan 1, 2000

By M. N. Herrera

The bioleaching of mineral sulfide pulps in a bench-scale rotating drum reactor has been studied. The reactor includes horizontal paddles in the inner wall for lifting of the mineral pulp. The performance of the reactor was tested in the bioleaching of a refractory pyritic gold concentrate in the presence of pure Thiobacillus ferrooxidans strain (ATCC 19859). The concentrate was efficiently bioleached at 50% pulp density with the drum operating at 0.5 -1.0 rpm Attempts of bioleaching the concentrate at the same pulp density in conventional stirred reactor showed severe inhibition of bacterial activity. The results demonstrated that the drum reactor allows to operate at much higher pulp densities than the conventional stirred tank reactor. This behavior is explained in terms of an improvement of the bacterial activity due to a better control of the attrition of the mineral particles.

Jan 1, 1997

By D. Morin, J. Villeneuve, S. Foucher

The development of new processes has to follow "best practice" rules in order to be technically and economically as efficient as possible. However, innovations, new process routes and new rules are continuously emerging to minimize financial risk and maximize environmental compliance. Process simulation, which offers a complete overview of the flowsheet, makes it possible to cope with this new challenge-minimizing waste production and water consumption. Furthermore, simulation provides an estimate, at the early stage, of the cost of alternative technical routes. Four examples involving biotechnological circuits are presented, both at the design and commissioning stages.

Jan 1, 2000

By A. D. S. Gillies, A. Haghighat

"A study has been undertaken at the Missouri University of Science and Technology (MS&T) limestone Experimental Mine to determine new fans set up and wiring options.to install additional mine ventilation capacity. Selection for main fans has been undertaken according to the mine’s required performance specifications and fan characteristics. Available fans for ventilating the mine are Joy and Alphair axial fans each of 24 kW each and two Spendrup booster fans of 12 kW each. The installation of main mine fans on the surface and underground entails numerous considerations. Design of a ventilation network for the Experimental Mine incorporating surface and booster fans has been accomplished using Ventsim Visual program software. The ventilation network has been separated into two segregated parts. A main surface fan and a booster fan have been used in each segregated part of the network. The mine has had a vane axial Joy fan in place for many years. The Alphair 4800 VAX 1800 full blade adjustable pitch vane axial fan was selected and installed as the other surface fan and eventual replacement for the Joy fan. Main surface fans have been connected individually to booster fans in series. The Alphair main surface fan has been installed vertically. Four different wiring options and related cost estimations for addition of the new main fans to the ventilation network have been considered. The analysis resulted in an innovative steel frame design used to allow the fans, when necessary, to be moved to the side of the shaft so that blast pressures do not damage the blades. INTRODUCTION Main fans are the heart of a mine’s ventilation network and play a key role in supplying required airflow (Haghighat, 2014). The Missouri S&T Experimental Mine has been developed in uniform limestone with few stratigraphic features. The mine floor is approximately horizontal and water drains well. A study has been carried out on MS&T Experimental Mine. Selection of main fans has been undertaken according to the mine’s required performance specifications and fan characteristics. Ventsim Visual computer simulation has been used to assist in design of the ventilation network. Wiring circuits, fan foundations and flexibility have been considered as the three main parameters for surface fan installation at the Experimental Mine. Two surface and two underground wiring options and three surface set up options and related cost estimates for the new surface fan system were investigated. Frequent use of explosives in the mine occurs throughout each year. Flexibility in changing the position of a surface fan is important. A number of options have been considered for the location of a vertical main fan positioned on the upcasting shaft. The mine is used for a variety of purposes and flexibility has a high priority amongst design considerations."

Jan 1, 2015

By P. Songfack

In this work, the slurry flow in the ball mill is solved with Navier-Stokes&apos; equations and the marker and cell technique (MAC), which tracks the fluid-free surface. Considering different planes in the radial and axial directions, this numerical approach leads to the direct calculation of the slurry velocity profile, mill holdup, and volumetric flow in the ball charge and pool. The MAC technique takes as input, the results of a direct three-dimensional simulation of the motion of grinding media, and in turn, provides a detailed knowledge of the hydrodynamics of slurry flow through the porous structure of ball load. This technique is a new approach to the mass transport problem that overcomes the limitations of indirect studies such as residence time analysis and holdup measurements.

Jan 1, 1994

By E. C. Grunsky

Spatial auto- and crosscorrelation assessment of variables can be carried out using quadratic function estimates. From the function estimates, multivariate relationships of the variables can be determined in the form of spatial factors. The calculation of the spatial factors requires computation of the corresponding amplitude vectors from the eigenvalue solution. This vector reflects the relative amplitudes by which the variables follow the spatial factors. Instability of some of the eigenvalue solutions requires that caution be used in interpreting the resulting factor pat- terns. A measure of the predictive power of the spatial factors can be determined from the auto- correlation coefficients and squared multiple correlation co-efficients which indicate which of the variables are significant in any given factor. The use of unconditional simulations provides a basis by which geological variables of varying spatial ranges can be modelled using the spatial factor technique. Simulations were generated for a variety of ranges and variables were created that form single or multiple combinations of the spatial patterns. The success of the spatial factor technique depends on the amount of associated noise, and the size of the neighbourhood relative to the spatial range of the variable. The predictive power of the components is dependent on these two factors. Problems with collinearity of variables can result in unrealistic eigenvalues and result in the failure of the method. Application of this method to spatial data in mineral exploration can assist in outlining spatially continuous zones of alteration associated with mineralization.

Jan 1, 1989

By Hans von Michaelis

Gold metallurgy has advanced remarkably over the last decade. Even more significant progress will be made over the next five years, particularly in the application of advanced comminution techniques and control, preconcentration (flotation, ore sorting and coal gold agglomeration), enhancement of cyanide leaching technology, non- cyanide leaching, treatment of refractory ores and concentrates, and improved recovery systems. Carbon adsorption processes have become standard practice for ores with relatively high gold/silver ratios, but ion exchange potentially offers distinct advantages and has recently been demonstrated to perform better in at least one application. Even in the established zinc precipitation and CIP processes several important practical improvements are emerging as experience is gained at the ever increasing number of operating plants. Improved process control and reduction of reagent consumption costs are two important goals of industry at this time.

Jan 1, 1989

By Trent A. Tempel

In 1989 Newmont Gold company initiated a project to develop a treatment process for higher grade refractory gold ores to be mined from deposits along the Carlin Trend in Nevada. Extensive laboratory and pilot testing have identified a unique whole ore roasting process for oxidizing these ores prior to gold recovery by conventional cyanidation techniques. Subsequent detailed engineering studies by Fluor Daniel evaluated three different dry grinding flowsheets for feed preparation to this roasting circuit. The selected flowsheet will incorporate a two compartment ball mill with an attached drying chamber that is driven by a 11.2 MW (15,000 hp) wrap-around motor.

Jan 1, 1993

By C. Newman, N. Schaefer

"As underground mining continues to operate at deeper depths and in more complex geologic and geometric conditions, there has been an increased demand for mine designs to better reflect site-specific conditions, measurements, and observations with respect to ground control safety and stability. During the past 20 years, the National Institute for Occupational Safety and Health (NIOSH) has developed, validated and distributed a number of free software packages (ALPS, ARMPS, AMSS, ARBS, etc.) specifically aimed at providing the industry with ground control design tools for the evaluation of underground stability in coal mines. While these programs were initially developed as stand-alone software packages where all data reside on an individual or workgroup computer, modern day web applications have begun to migrate toward a “multiple-tier” architecture, allowing multiple users to access an application by means of an Internet connection.This article introduces a new Web-based platform for ground control software applications, webGroundControl (webGC). webGC provides users with a platform through which one can access NIOSH and other ground control design software utilizing a Webbased, multiple-tier architecture. This provides users with easy access to ground control designs, the ability to perform on-demand calculations, as well as increase online collaboration between operational personnel and engineers through a web server. The basic framework and, more specifically, the user-interface of webGC are defined and outlined within this paper. It is expected that the mining industry will rapidly embrace this new product and webGroundControl will be a new paradigm for mining engineering computer applications. Platform architectureAs Web-based computing technologies continue to advance and cloud computing gains momentum, web-based platforms for software applications are growing in popularity across all industries due to ease of product accessibility and distribution as well as data security. With the expansion of Internet connectivity on the surface and underground, there is an industry need to develop Internet-based applications for mine and ground control design (Barczak et al., 2016). Cloud-based products are already available for many industries and are slowly being developed for the mining and geotechnical industry. A notable example is the drillysis package, which is a cloud-based borehole logging database (Geosysta, 2017) or the Dynonobel package for on the fly blasting calculations (Dyno Nobel, 2013)."

Jan 10, 2017

By M. R. Grundy

The Robinson project is based on the porphyry copper and gold deposits in the Robinson Mining District, near Ely in Eastern Nevada. The district was mined from the late nineteenth century to 1978 by Kennecott Copper Corporation and its predecessors. Operations ceased when falling copper prices in the late 1970&apos;s made their outdated mill and smelter complex at McGill uneconomical. In October 1991, Magma Copper Company (Magma) acquired the many claims that cover the known porphyry copper deposits in the district These occupy a disturbed area about nine miles long and three miles wide between the towns of Ely and Ruth. Magma proposes to build a copper / gold mine and concentrator and expand the existing gold leaching facilities. Several pits, previously mined by Kennecott Copper Corporation, will be enlarged; the use of larger, more modem equipment will result in higher productivity and lower operating costs in general. ICF Kaiser Engineers, of Oakland, California, were awarded the con-tract for detailed design of the process facilities, which was essentially complete by the end of 1993. The project at present is awaiting completion of the environmental permitting process; state air and water permits are in hand, and the Bureau of Land Management&apos;s (BLM) current schedule indicates that the final obstacles to construction will be cleared by early fall of this year.

Jan 1, 1994

By C. Cigna, M. Patrucco, D. Savoca, E. Lovera

The paper deals with the activity program and the preliminary results of a research work commissioned by IReR Research Centre and Regione Lombardia to the Department of Land, Environment and Geotechnologies of Politecnico di Torino. The aim is to define measurement, analysis and control criteria for the emission of chemical and physical pollutants from non-metal mining industries, with particular reference to noise and airborne particulates. Such emissions are related to health risks and annoyance problems, both for the working crews and the neighbouring population, and so, in order to get an effective sustainability of the industry, suitable reduction methods and assessment tools are required. A simple technique for the evaluation and forecasting of both the emission levels and deriving impact has been tested at different mining and quarrying sites, considering their differences in terms of layout and exploitation method, the latter ascribed to a series of main typologies as present in Lombardia region.

Jan 1, 2005

By William R. Beloff, Franklin M. Grynkewicz, Puza

Construction of the MBTA Red Line Extension through Somerville, MA, called for driving twin tube tunnels through a zone of approximately 83m (273 ft) with mixed face conditions. While the majority of the tunnels were driven through competent hard rock using drill and blast techniques, the mixed face zone was advanced using floating crown bars for primary support. The overburden consisted of medium clay, underlain by water bearing glacial till, over a sloping bedrock surface. Due to the unusual nature of the construction techniques, a program was undertaken by the Contractor to monitor ground movement and stresses in the temporary steel supports. This paper presents a description of the instrumentation employed, as well as the measured ground movements and support stresses. Additionally, the tunneling techniques are briefly presented and commented upon. PROJECT DESCRIPTION The Davis Square to Porter Square Tunnel Contract is part of the Massachusetts Bay Transportation Authorities (MBTA) Red Line Extension from Harvard Square in Cambridge to the Alewife Brook Parkway via Somerville. The 5.1km (17,000 ft) Red Line Extension consists of four major new stations, three of which will be interlinked via tunnel construction, and the remaining station will be the last link of an open cut portion, and a terminal point for this phase of the extension. This 866m (2,790 ft) portion began at Porter Square in Cambridge and rose at a 4% slope through Somerville, terminating at the new Davis Square Station. Twin tube tunnels were constructed through 763m (2,517 ft) of rock and 83m (273 ft) of mixed face conditions at the Davis Square end. Figure 1 presents a plan view of the entire contract.

Jan 1, 1981

By Murray Malott

The Sheppard Subway extension is currently being constructed in Toronto, Canada for the Toronto Transit Commission (TTC). McNally International Inc., in a joint venture with PCL and the Foundation Company of Canada were awarded the Twin Tunnels contract of the Sheppard extension. The Twin Tunnels project is approximately 4.4 km in length and consists of two separate twin bore drives each 3.3 km and 650 m in length and approximately 400 m of cut and cover construction. This paper presents a case history of the construction of the soft ground tunnels through the complex Toronto glacial deposits using two 5.9 m outside diameter Lovat earth pressure balance (EPB) tunnel boring machines.

Jan 1, 1999