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The limit of pressure to which an underground dam may with safety be subjected, is a question that-as far as the writer knows has not received the same attention from authorities on engineering construction, or practical mining, that has been accorded to questions on which the design and strength of other structures or machines in connection with a mine are based. That dams may, under certain conditions, be constructed to resist water under great pressure is a known fact. But the difficulty of demonstrating beforehand that any proposed structure of this kind will withstand the pressure and be effective is, owing to the indeterminate nature of some of the risks to be provided against, very great. In the present state of our knowledge it may almost be laid down as a rule, that a dam of this kind should not be undertaken where grave consequences would attend failure until experience of structures where the physical conditions are similar, but where there are no such risks, has given assurance that such work would stand.In Mines and Minerals for May, 1900, there is published a paper by Mr. James McNaughton describing the construction of three underground dams in the iron mining district of Michigan.The first of these was put in to hold back a flow of 750 gallons per minute, which when pent up created a pressure of 276 pounds per square inch, showing that the height of the sustained column was about 635 ·feet. The hole through which the water issued was in the bottom of the cross cut it was enlarged by removing all loose rock for a depth of 18 ft...

Jan 1, 1901

By J. Kretschmann

Southeast Asian countries cannot maintain their economic growth rate without the development of their mining industries. To make this development as sustainable as possible requires sound fundamentals securing not only economic progress and environment protection but also improvements in occupational safety and health (OSH) for the miners. Mining in South East Asia is still very labor intense and dangerous. Tremendous achievements from world class mining operations in advanced mining countries can be used as role models to improve the status quo of the Southeast Asian countries in OSH management. Know-how transfer, therefore, is a key factor for major improvements. Effects of this transfer based on a multi-level approach will be discussed based on a case study. It describes the transfer from German to Vietnamese hard coal mining industry. Crucial requisites for excellent achievements in OSH in Southeast Asian mining countries are also mentioned.

Feb 23, 2014

By N. Kumar Kittusamy

A field study was conducted to evaluate seat designs on shuttle cars. Eight operators participated in evaluating seat designs on the basis of perceived levels of vehicle jarring/jolting and discomfort. Researchers also measured the levels of vehicle jarring/jolting. Four basic seat designs were compared on low and mid-coal seam shuttle cars during production operations at two underground coal mines. Two seats were currently used on the shuttle cars and another two were NIOSH designs. Objective data were collected using accelerometers with pre-amplifiers and filters connected to a data recorder; whereas subjective data were gathered with a visual analog scale (VAS) and a questionnaire. Results from measured levels of jarring/jolting showed that the NIOSH Seat L2A smoothed out bumps better than any other seats. Using the VAS, mid-seam and low-seam shuttle car operators rated the levels of jarring/jolting and discomfort lower with the NIOSH seat than the other seats. Questionnaire responses indicated that operators rated NIOSH seat designs as more comfortable. This research will provide the industry with better seat designs for isolating jarring/jolting in vehicles. Furthermore, researchers plan to improve the NIOSH seats using information gathered in this study.

Jan 1, 2003

By J. S. Phipps, D. R. Skuse

"Aqueous slurries of fine particle size calcium carbonate are used in a diverse range of end-use products. In many cases, the end use performance is governed by the fineness of the particle size distribution. In turn, the maximum fineness of the particle size distribution is primarily determined by the efficiency of the dispersants used during the production process. Here we report the sodium polyacrylate mediated dispersion of calcite and kaolin. Firstly, we report a colloid chemical description of the dispersant behaviour and attribute the stabilisation to both steric and electrostatic mechanisms. Secondly, we describe how the understanding developed in the first part of the study can be utilised to produce more effective dispersant systems which allow the preparation of, added value, higher solids and finer particle size calcium carbonate slurry products.INTRODUCTIONConcentrated aqueous dispersions of fine, particulate kaolin and calcium carbonate are used extensively in the coating of paper. Currently more than 10 million tonnes of such dispersions are used annually in North America and Europe alone, and worldwide consumption is growing at around 3% per year.Generally, paper is coated to enhance its visual appearance. Firstly, coatings improve the optical properties of the blank sheet, i.e. its brightness (or whiteness), opacity and gloss. Secondly, they improve the physical properties of the sheet that will influence the quality of the final printed image, such as surface smoothness, porosity, and ink absorption. In order to achieve these aims economically, paper coatings must be applied at high speeds and with minimal drying costs.Kaolin and calcium carbonate pigments are the major components of most paper coating formulations. Particle size distributions are chosen to maximise the optical benefits that they confer, and to allow the production of formulations that can be easily pumped, handled and coated. Coating pigments are generally produced and transported as slurries, and so it is important to obtain dispersions with the highest possible solids content, both to minimise drying costs and the quantity of water transported. This paper examines the dispersant technology that is currently used in the industry and the mechanisms by which it functions, and illustrates ways in which this technology has developed and could be further improved in the future."

Jan 1, 2003

"Air Products approached LAC Minerals in 1987 to initiate trials with pure oxygen in the leach circuit at several LAC facilities in Canada. This paper gives an overview of oxygen use and covers specific operating data from the Doyon and Terrains Aurifères mills near Val D'Or in northwestern Quebec. LAC also uses oxygen at the Macassa mill in Kirkland Lake, Ontario.In addition to the LAC facilities, oxygen is currently in use for test purposes at the Holt McDermott mine in Kirkland Lake, Ontario and the Camflo mine near Val D'Or.There are two requirements for oxygen in the cyanide leach mill. Firstly, oxygen is required in the familiar gold dissolution reaction as follows:(1) 4 AU (s) + 8 NaCN (aq) + 02 (aq)+ 2H 20(aq) - 4NaAu(CN) 2(aq)+ 4Na OH(aq)Of the reagents on the left side of the equation, the availability of gold is fixed by the ore in question. Obviously, water is available in excess, 1eaving cyanide and oxygen as the limiting constituents in the process. Most mills operate with an excess of cyanide, which is fairly closely monitored. Dissolved oxygen levels, however, are not normally watched very closely and find their own level based on the temperature, the availability of compressed air and the ability of the ore to consume oxygen.Typical D.O. levels are in the 3-8 ppm range, however levels less than 1 ppm are not uncommon for refractory ores.With pure oxygen, dissolved oxygen levels as high as 30 ppm can be achieved. (Figure #1). This greatly accelerates the kinetics of the leach reaction and may also shift the reaction further towards completion thus increasing gold dissolution slightly."

Jan 1, 1990

Coagulation-Neutralisation Technology to Treat Wastewater from Lead-Zinc Concentrator

Sep 13, 2010

By P Allen, E Gleeson, D Boakye, R Chesher, S Konopa

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Not only do epithermal gold deposits provide many challenges in estimating mineral resources, the complexities of these deposits also provide technical challenges in assessing appropriate mining and processing strategies, as well as social and environmental planning and management. The characteristics of epithermal gold deposits include being highly variable with respect to geometry and gold grade distribution, the presence of other economic contributors, mineralogy, texture, rock strength, weathering and alteration overprint. These characteristics influence the economic value of mining projects in an interlinked manner. Consequently, successful exploitation of epithermal deposits requires a holistic approach, coupled with the effective integration of geological data to meet all aspects of mine development decision-making. This paper presents examples of the key technical challenges encountered in estimating and mining epithermal deposits. It also highlights why these issues need to be addressed from the viewpoint of geology, sampling, resource estimation, mine planning, mineral processing and social and environmental planning for the true value of the mining project to be realised.CITATION:Konopa, S, Chesher, R, Gleeson, E, Allen, P and Boakye, D, 2015. Challenges in maximising the value from epithermal gold deposits, in Proceedings PACRIM 2015 Congress, pp 127–132 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By A. Martikainen

Field tests concerning a fog mesh method for fog removal are discussed. The first tests were performed at the Pyhäsalmi Mine, Finland. As this study gave promising results, further studies were completed at the Orivesi Mine. The results of these most recent field tests are presented and the two studies are compared. The Orivesi test set consisted of four materials. These included air filter fabric, fibrous filter fabric, a plastic greenhouse mesh, and an aluminium mosquito net. The variation of the Orivesi results was more noticeable than what was found previously. The best fog removal effect of all tests was achieved with the aluminium mosquito net, while the plastic green-house mesh performed worst. The humidity reduction by aluminium net was more profound than any of its precedents. More mesh materials will be tested in the near future.

Jan 1, 2007

By Ta M. Li

How will phosphate producers in southeastern Idaho fare with growing governmental regulations and environmentalism of the late 1970's? With a similarity that is reminiscent of the battles between the coal industry and environmental-conservation groups earlier in the decade, Idaho's future growth and a nation's need for phosphate fertilizer products remain uncertain. The catalyst that brought the issue to the forefront was the preparation of an Environmental Impact Statement (EIS) addressing the development of phosphate resources in southeastern Idaho. Although the final EIS was published in August 1977, resolution of rational and orderly growth in this potentially vital region remains stifled as Secretary of the Interior Cecil Andrus virtually "sits" on it.

Jan 1, 1978

By Matthew Wallin

A part of the East Bay Municipal Utility District?s Folsom South Canal Connection Project, 430 feet of raw water pipe was installed using micro tunneling beneath the Mokelumne River. The access shafts for this crossing were constructed 50 and 35 feet deep through very dense sands and soft sandstone and siltstone. High groundwater and the immediate source of recharge from the river required watertight shaft construction methods. The shaft contractor, Drill Tech of Antioch, CA, used a brand new Bauer cutter-soil mixing (CSM) rig to construct the large shafts. The structural concept is similar to secant piles, but instead of creating cylinders of soilcrete, the CSM rig creates interlocking rectangular panels. This technology has been used previously in Europe, Asia, and Canada, but this was the first project to use CSM technology in the United States. Cutter-soil mixing technology has other applications beyond shaft construction, including retaining wall construction and levee reinforcement.

By Seal. Thom

Large heap leach operations around the world contain significant under-leached metal values that present recovery challenges to operators. The first challenge is to find the location of the highest inventory. High resolution resistivity ? has proven sensitive enough to detect such zones in the interior of heap leach pads to target treatment or re-leaching. Newmont Mining Corp. has adapted the high pressure fracturing technology, used in oil wells to stimulate select zones in heap leach pads to add reagents in 3-D for re-leaching, changing zonal chemistry for improved recovery and heap closure. High Resolution Resistivity ? is able to subsequently monitor injected solution flow and determine directional permeability during Hydro-Jex stimulation. The combination of these technologies has shown strong economic success, for selecting targets in the heaps and monitoring solution application. These technologies are now available to the mining industry for adoption.

Jan 1, 2008

By Jorge Oviedo

La planta de lixiviación, extracción por solventes y electrodeposición (L-SX-EW) de Southern Perú es una operación hidrometalúrgica dedicada a la lixiviación ácido – bacteriana de los botaderos de mineral de baja ley de la Mina Toquepala, para la producción de cobre catódico de la más alta pureza. En ese sentido, el presente trabajo describe la evolución del sistema de control y supervisión de esta planta minera en Cuajone. Para ello, dicha planta debe tener una actualización constante de sus sistemas de control y ser capaz de cambiar con la velocidad a la que avanza la tecnología de Control de Procesos. Asimismo, debe contar con personal calificado que permita el desarrollo y modernización de los sistemas sea continuo y no dependa solo de expansiones y ampliaciones ejecutadas por especialistas externos. De forma que este software de supervisión, no solamente considera la capacidad de operar la planta, si no debe ser una ayuda tanto para el operador como para brindar información en la correcta toma de decisiones.

Aug 25, 2002

By Júlio C. Lúcio

Consider the case of a mining company with N investment opportunities in projects of different commodities. The problem is: since the company has limitation of capital, equipments, technical staffs, etc, what is the best portfolio of production projects in order to maximize expectations from shareholders? In the no-longer past, the traditional method for the selection of portfolio of projects was the rank-an-cut method. But, this does not properly account for the risk to which the company is exposed. The Markowitz?s Mean-Variance is an advance because the risk of the NPV can be estimated at the level of the company or even division of the corporation. The final product of the Markowitz?s model is the efficient frontier, in which, the manager can clearly understand the maximum return from existing assets and the associated risk level - but this model does not recommend which one is the best portfolio. In this paper we present a model to select the best portfolio considering not only economic indicators, but also requirements of production, constraint in investments, etc. We show that if investors are diversified, managers should select projects with highest return, regardless of risk. However, in practice, if bonuses of managers are tied to their performance, the choice for portfolio with lower return and risk can happen. Numerical application considering typical portfolio of large mining company is used as example.

May 1, 2009

By S. K. Murphy, K. B. Le Bron, A. K. Ward, S. Hayes, T. Rangasamy

A process for evaluating different options for extraction of mining blocks is presented. The process is described and an example of the application of the process to a case study is presented. Un procédé pour évaluer différentes options pour l’extraction de blocs d’exploitation est présenté. Le procédé est décrit et un exemple de l’application du procédé à un cas particulier est présenté. Ein Prozeß für das Auswerten der unterschiedlichen Optionen für die Extraktion von Abbaublöcken wird dargestellt. Der Prozeß wird beschrieben und ein Beispiel der Anwendung des Prozesses zu einer Fallstudie wird dargestellt.

Jan 1, 2003

By P. J. Brereton-Stiles, M. S. Rennie, N. Singh

Ferroalloy producers are large-scale users of electrical energy, which in many countries is in short supply and increasingly expensive. Preheating and/or pre-reduction using natural gas, recycled furnace gas or coal fines have lowered the specific use of electricity, but the high energy concentration necessary for most reduction processes can be achieved only by the use of high electric currents. Most countries have insufficient electricity to supply the demands of industry and the domestic consumer, particularly during certain periods of the day and certain times of the year. The generation and distribution of electricity is a large-scale expensive business, which is financed and managed directly or indirectly by government bodies in most countries. Both economic and political imperatives determine how much electrical energy is made available to whom and at what price. In South Africa demand is set to outstrip supply within the next few years, and the local supplier Eskom has moved from a traditional demand tariff pricing structure to a time-of-use tariff pricing so as to limit peak demand usage. This will mean a substantial increase in electricity cost to those users unable or unwilling to reduce consumption during peak periods. The optimal use of the available electrical energy depends both on the process, the furnace size, the configuration and infrastructure of each plant and its cost structure. As the cost and availability of electricity is set to change dynamically, the management of the situation becomes a real time control and optimisation problem. This paper discusses some the process and operational constraints associated with low- or no-load conditions and how to manage the situation. Electrode management will be one of the key issues.

Jan 1, 2004

By J. Hunter, E. Jackson

This paper describes work done by Placer Dome Technical Services Limited, a subsidiary of Barrick Gold, and Nautilus Minerals Inc. in support of the conceptual design of a subsea mining system. It describes an overall concept design plus specific studies into mechanical excavation at depth. The concept design includes one or more subsea excavators connected to a suction riser, which transports the cut material to a shipboard dewatering and offloading system. A multi-phase investigation was performed into the mechanical excavation of seafloor massive sulphides at depths of around 1600m. Rock samples were recovered and tested for rock properties and cutting behaviour. A small pick drum cutter was procured and tested on a representative concrete slab in a lab and tested again while submerged in a test tank. Finally the cutter was tested on a massive sulphide ore body at 1600m depth. The cutting performance results, e.g. pick forces and specific energies, should provide valuable input to the design of future full scale subsea mining systems.

Jan 1, 2007

Jan 1, 1969

By Adrian Coombs

The York Durham Sewage System (YDSS) Interceptor Tunnel Project is located in the Town of Richmond Hill, Ontario, Canada, just north of Toronto. Construction commenced in September 2006 and completion is planned for early summer, 2008. The project involved public and agency buy-in of construction technologies and methods that minimized dewatering, design and construction of sealed shafts with jet grout break-in and out blocks in order that Earth Pressure Balance (EPB) mode could be maintained by the Tunnel Boring Machine (TBM) during shaft entry and exit. This paper will discuss the advances that were made possible through the opportunity to apply and test these technologies in order to accommodate the aquifer and artesian conditions present on this project.

Jan 1, 2008

By B. Berhe, R. D. Lawrence, J. Hinzer

"The fortunes of mining companies and their implied value are tied to cycles - both economic and commodity – within which they operate. Hence the determination of appropriate future metal prices is one of the most critical factors faced by mineral valuators especially for advanced projects. Price, and hence revenue, is usually the most sensitive input to the valuation model. Empirical studies of past forecasts show that the success rate for commodity price forecasting is very poor. This paper explores various approaches and comments on their strengths and weaknesses. We conclude that careful evaluation of long-term metal prices is a key element and is hardly a luxury that can be left to simple averages or rules of thumb. INTRODUCTION Discounted Cash Flow (""DCF"") analysis, is well suited for the valuation of advanced mineral development assets, for which there are identified mineral resources and some form of economic assessment (Pre-Feasibility or Feasibility Study). The DCF method is also the most commonly used method for determining value for such assets. It provides a means of relating the magnitude of expected future cash flows from profits (or losses) to the magnitude of the initial cash flow (investment) needed for capital expenditures to purchase or to develop an asset for commercial production. The method proves useful in making investment decisions as it allows for the quantification of the Net Present Value (“NPV”), as well as the Internal Rate of Return (IRR) and Payback Period on initial investment capital. Valuation by its very nature is a forward-looking exercise. The DCF method attempts to estimate the NPV of expected future cash flows, by selecting factors that will likely affect future cash flow based on informed analysis. One of the most critical and sensitive factors is the determination of appropriate future commodity prices. “The variables that have the greatest impact on a DCF evaluation are the reserves, the metal prices, and the discount rate.”1 The determination of future commodity prices for valuation purpose or during M&A negotiations is a hotly contested issue. There are a number of analysts, institutions and specialized commercial data suppliers that provide both short and long-term commodities price forecasts. Also, the use of an aggregated mean for all available forecasts, or consensus forecasted prices for valuation purposes is not uncommon. The methods used in making forecasts for each forecaster may vary and in many cases may not be publically disclosed. Nonetheless, the aggregated mean of all forecasted commodity prices of reputed institutions is usually taken to “represent the market’s view of likely future commodity prices.”"

Jan 1, 2016

By G. Barbery

"Particle composition distribution is an essential feature of materials processed by physical separation methods. The amenability to segregate a feed material in a concentrate and a tailings stream depends to a large extent on what is called usually the ""liberation"" of the various mineral phases that are present in an ore. In fact the energy consumed in crushing and grinding has the major justification of producing particles that are as close as possible to monominerallic. Monophasic particles are able to reveal physical differences in mineral properties that make their separation possible. For many years, various authors have insisted on the concept of liberation, without noting that, in practice, it can be a pure concept which does not lead to measurements or predictions. The present paper insists on the concept of particle composition distribution, in which the complete distribution is the information to be obtained, and not the ""liberation·· of various phases, just like for particle size distribution, the complete distribution is an objective commonly desired, and not one or two values representing the coarse or fine fraction.2. NOTATIONS-EQUATIONSFor the purpose of the paper, a particle will be characterized by its volume Vp, and its volumetric composition with respect to a mineral of interest, which will be given the notation ""O"". All the other minerals present will be called ""1"". This notation does not imply that the particles are biphasic, but that we are interested in the composition of particles with respect to one phase only. The volumetric composition will be given the sybol m:"

Jan 1, 1986