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The Penetrating Cone Fracture (PCF) technology 1 is a new method of rock excavation developed by Sunburst Excavation, Inc. of Denver, Colorado. PCF is a rock excavation method which employs tensile breakage mechanisms under controlled conditions to enable the continuous excavation of rock?in underground and some surface applications. The technology has developed rapidly over the last two years to the point where it is now being prepared for commercial application in the mining and civil construction industries. The initial commercial application of PCF will be undertaken at the Perseverance Nickel Mine of Western Mining Corporation Limited in Western Australia beginning in May, 1994.

Jan 1, 1994

By L. H. Monaco

"The evolutional process is always about solving existent problems in order to provide further achievements. But the more something evolves, the more challenges it faces towards greater evolution. Industrial automation systems in Mining have also evolved a lot in the past decades, but they now face new challenges about integration: how to integrate different locations and systems, in a way to reduce costs and increase overall mine efficiency and safety for the operation. This paper compares conventional mining process automation architectures vs. a state-of-the-art, completely integrated system using Electrical Integration based on IEC 61850 standard for Substation Automation Systems. Emphasis is placed on the benefits to manage the entire mining plant as a whole, not only looking at the production rates, but also at the energy consumption for each part of process. In addition, it is discussed how an integrated system approach unlocks safety and productivity gains such as overall process optimizations, improved operator effectiveness, increased plant availability, and reduced maintenance costs. INTRODUCTION The world is constantly changing, and evolution is a natural part of mankind history. The role of evolutional process is to solve existent problems, but usually these solutions create new issues that need to be addressed. This scenario is also applicable to the industrial environment, in which the demand for higher profitability and efficiency on their processes requires solutions with more productivity using less resource. This is not different when it comes to energy consumption: how to optimize production rates and reduce energy costs at the same time? Regarding automation systems, the trend for the industries is to focus on four main challenges: how to provide safety for personnel; how to reduce initial investment for new plants; how to connect remote and in harsh locations; and above all how to deal with the lack of integration between several systems."

Jan 1, 2018

By G. W. Luxbacher

With the advent of acid rain legislation included within the Clean Air Act Amendments of 1990, a great deal of uncertainty with regard to price, source and production quantities has been cast into the coal market. Powder River Basin and other western coals continue a rapidly accelerating migration eastward, South American coals move into the northern markets, states propose legislation to assist utilities in complying with the new regulations in hopes of maintaining their own coal industries, while some utilities question the long term availability of eastern compliance coal. Any major coal producer must make decisions now to assure their continuing presence in the market place; several companies have adopted a strategy to acquire eastern compliance reserves while others have invested in technology to compete as a low cost producer. This paper discusses some of these options in light of the uncertainties of the market place, from an eastern coal producer?s viewpoint.

Jan 1, 1992

By I. Yu. Melekestseva

Two types of hydrothermal massive sulfide fields were discovered in the Mid-Atlantic ridge (MAR) in the last twenty years. The first type associates with basalts and includes the TAG, Snakepit, Broken Spur, Lucky Strike and Krasnov hydrothermal fields. The second type is related to ultramafic rocks and represented by the Logatchev, Rainbow and Ashadze hydrothermal fields. In 2007 a new, probably, the largest cluster of hydrothermal massive sulfide field on the MAR (Fig. 1), related both to basaltic and ultramafic rocks, was discovered at 13°31'N of the MAR (Beltenev et al., 2007). [ ]

Jan 1, 2008

By QU Hong-lue, YANG Lin-han

Aiming at the subjective impact caused by subjective weighting method in the establishment of rockburst risk attribute identification and prediction model, the combined weighting method was introduced to eliminate the influence of unreasonable weight of each index. Eight discriminant indexes affecting the risk of rockburst were selected. Through the literature review, relevant rockburst cases were collected and 8 index rockburst sample sets were established. A variety of machine learning methods were used to analyze the feature importance of discriminant indexes in the samples, and then to determine the objective weight values of different methods. Combined with the subjective weights determined by the Analytic Hierarchy Process, the combination of weights were successively carried out. Based on the attribute recognition theory, the combination weights with different objective weight methods were established to identify the rockburst risk attributes, and verified by the confidence criterion. The results show that the objective weight value determined by the feature importance analysis of machine learning reduces the subjectivity of the weight of Analytic Hierarchy Process method, improves the prediction accuracy, and makes the prediction result closer to the fact.

Apr 26, 2022

By G. E. Maryniak

To date, human space exploration has been almost completely dependent on the use of resources carried with astronauts and cosmonauts from the surface of the Earth. The only exception to this has been the harvesting of solar energy to power space stations like Skylab, Salyut and Mir for long-duration missions. This dependence on materials which must be transported into orbit at costs in excess of $5000 per pound is the fundamental limiting factor in space exploration and operations. It is likely that launch costs can eventually be greatly reduced by means of such innovations as true single stage to orbit vehicles, aerospace planes, or serial electromagnetic or laser launch systems. However, the Earth will always remain an expensive source of materials for space construction and for basic commodities such as propellant and life support liquids and gasses. Fortunately, abundant sources of materials exist which are already in space, outside of the Earth's deep gravity well.

Jan 1, 1992

By Samuel W. Woods

The Tacoma, Washington plant is one of six plants in the United States Gypsum Company's Acoustical and Mineral Fiber Division. The Tacoma facility was acquired in 1959 along with six other mineral wool plants from the American Rock Wool Company. Originally, the Tacoma plant was built as a carbide plant during the Second World War and after that was converted and operated as a mineral wool plant by several insulation companies. Through these early years, the use of raw materials at Tacoma consisted primarily of slags along with small percentages and various combinations of silica (in various forms such as gravel), limestone and basalt. These raw materials were melted in cupolas using coke as the heat source. Raw material usage and types as well as mineral wool production methods and equipment remained without major changes for many years.

Jan 1, 1983

By Luisa Alfieri, Giorgio Fantauzzi, Sergio Notarianni, Spencer Cavagnet, Alessandro Damiani

"The new tunnels of the Copenhagen ""Cityringen"" will be excavated, at Kongens Nytorv square, crossing over the existing M1 and M2 metro lines. After the crossing, the tunnels will underpass the historical building of the Magasin du Nord and adjacent masonry buildings, with a minimum tunnel cover of about 4.5 m. The tunnels have an internal diameter of 4.9m and are being excavated through earth pressure balanced Tunnel Boring Machines in mixed face.The Magasin du Nord estate is characterized by a very complex structure, with different blocks built in different times. An assessment of the condition of the building and its sensitivity to tunnellinginduced ground movements has been conducted through a fully coupled soil-structure interaction analysis; based on the results of this analysis, mitigation measures have been designed.INTRODUCTIONThe Copenhagen Metro Cityringen is expected to be running in July 2019 and will consist of two single tracks in a twin tunnels, each approximately 16 km in length, for transporting up to 243,000 passengers on an average work day. The Cityringen includes 17 underground stations with island platforms, 4 crossover facilities and 3 construction and ventilation shafts. The tunnels is being excavated using earth pressure balanced Tunnel Boring Machines and have an internal diameter of 4.90 m.The intersection with the existing M1 and M2 metro-line will take place at Kongens Nytorv and at Frederiksberg. According to the design alignment, in Kongens Nytorv the new tunnels will pass over the existing M1 and M2 ones; as a result of this, the tunnels will underpass the historical building of the Magasin du Nord and the adjacent masonry building hosting a Mc Donald’s with a minimum cover of about 4.5m.In the framework of Risk Assessment for sensitive buildings, the effects of tunneling-induced ground movements on the Estates ØS0437 (McDonald’s building), ØS0428 (Magasin du Nord) and ØS0004 (Hviids Vinstue) were evaluated. To achieve this goal a fully coupled soil-structure interaction has been considered and the entire excavation process has been reproduced in a 3D model where the abovementioned buildings have been modeled. In this way, a risk assessment analysis was performed evaluating directly the effects of the excavation in terms of settlements and variations of the internal forces as far as the excavation process proceeds. In figure 1, a picture of the construction of Kongens Nytorv station, with Magasin du Nord and Mc Donald’s building on the background, is presented."

Jan 1, 2016

By Adrian Fleming

Adrian Fleming is Executive Vice President of Exploration for Golden Star Resources Ltd., Denver. Adrian is an Australian who graduated in 1973 with an honors degree in geology from Newcastle University, New South Wales. His extensive international experience has spanned exploration, project development, and operations for both large and small companies in Australasia, Southeast Asia, North and South America, and Africa. Adrian has been with the Golden Star group of companies for four years and he is responsible for all exploration activity. ABSTRACT Golden Star acquired the rights to the Omai prospect in 1985 at a time when the country of Guyana was out of favor with the exploration fraternity. Subsequently in the late 1980s and early 1990s, Golden Star acquired exploration properties in Suriname and French Guiana well ahead of its competitors. Golden Star's strategy entailed identifying windows of opportunity and aggressively pursuing them. We also recognized that the Guiana Shield hosted a significant area of highly prospective greenstones which were comparable in metallogenic potential to similar terrains in eastern Canada, western Australia and west Africa. The geological skills Golden Star developed and the exploration techniques employed to explore deeply weathered rocks are described. The paper highlights the key elements of Golden Star's strategy and illustrates how some of the milestones reached by the company led Golden Star to establish an enviable portfolio of gold and diamond properties in the Guiana Shield.

Jan 1, 1998

By G. J. Hartman

A presentation of this project was given previously at the SHE Annual Meeting, Denver Colorado February 23-27, 1987. The project concerns the development of in situ recovery of borate products from a deep-seated colemanite deposit in California. The deposit contains some 147 million tons of borate ore containing 6.4% boron oxide (B2O3). This paper involves the numerous changes in the process that has taken place since that first presentation. This paper further explains the reasons for these changes which are primarily environmentally based and secondarily capital requirements related.

Jan 1, 1994

By Kim McKnight

Dupont has successfully incorporated a Floatex Density Separator into its wet-gravity operations for the recovery of zircon from titanium tailings. Results indicate that the Floatex achieved a zircon recovery of approximately 95% while rejecting similar amounts of quartz and other gangue minerals. Additionally, a unit capacity approaching 16 tonnes/hr/m2 was achieved. Results also show that the alumino-silicates can be separated into other product streams that will further improve process economics and minimize waste material. The improved plant feed grade provided by the Floatex has allowed for either an increase in overall plant capacity and/or final product grade. This paper will present the findings from the in-plant study.

Jan 1, 1996

By Y. K. Yen

The most serious problem for on-line coarse particle size measurement from a conveyor belt by image analysis is the overlap phenomenon that occurs between adjacent particles. A methodology is developed and described in this paper to estimate the sieve size distribution from the overlapped projected particle images as might be obtained from a conveyor belt. Two aspects of the overlap problem have been taken into consideration. First, several image processing algorithms were studied to find the most suitable technique to separate the projected overlapped particle images for narrow sized particles. These image segmentation algorithms include two-dimensional thresholding, edge detection and Watershed discrimination techniques. The other aspect of the overlap problem is related to the determination of the general kernel function for the partial particle images obtained from the projection of the overlapped particle bed. In this regard, a computer simulation technique was applied to mimic the overlapped particle bed for narrow sized particles, then the general kernel functions of the partial particle images were determined.

Jan 1, 1994

By T. Wisdom, D. Romo, G. Seale, R. Jansen

Thickening remains relatively misunderstood since it is typically near the end of the process and not directly involved in metal recovery. When operating well, thickeners are ignored and left to run independently, the ‘out of sight, out of mind’ phenomena. However, when operating poorly, there is a lack of basic understanding and remedial actions to solve issues are reactionary rather than proactively addressing shortcomings. This series of papers breaks down in sequential order the stepped phases required to gain an appreciation and thorough understanding of the science behind thickeners, and key thickener components, and basic troubleshooting skills. This second paper starts with identifying the different approaches to thickener test work including static and dynamic settling tests followed by high-rate versus paste thickening. Complimentary to test work, the mechanisms surrounding coagulation and flocculation are presented and explained. The basic mechanisms for coagulation and flocculation are discussed to support the different test work approaches and provide the reader with the basic background.

Mar 2, 2022

By O. Guyot, A. Broussaud, J. Björkman, P. Söderman, P. O. Samskog

Model-Based Expert Control systems (MBEC) are on-line supervisory dynamic optimization systems which combine the ability of a phenomenological model to generate a large amount of information about the state of the process and predict its evolution, with the flexibility of a rules-based approach to take plant constraints into account and apply a complex control strategy. For its new concentrator started in 1995 in Kiruna (Sweden), LKAB has implemented a progressive grinding flowsheet with closed-circuit autogenous grinding followed by closed-circuit pebble grinding with ore pebbles. The standard for instrumentation in this new plant is very high. The control hardware consists of a Distributed Control System (DCS) through which the operators interact with the plant, supplemented by a site-level Management Information System (MIS). A state-of-the-art MBEC system was imbedded in the MIS by the authors before plant start-up. It consists of several modeling and expertise software modules: a phenomenological process model and a Kalman filter estimate continuously the state of the process, an optimizer calculates an optimum feedrate, while rules-based modules establish production targets and key process set-points. The decision to install the MBEC system as an integral part of the new plant before start-up illustrates the current maturity of the technology, i.e., enough know-how was accumulated through former projects to design and develop the system to a large extent without accessing the plant. The feasibility and the power of dynamic optimization systems were previously demonstrated in Kiruna pre-existing concentrator by the authors. First, a MBEC system was installed on the three existing pebble mill circuits, providing both an increase in quality (stabilised size distribution) and a 10% increase in capacity. An on-line expert control system with limited modeling capabilities was also installed in the existing flotation plant, with the aim of stabilizing phosphorous content in the concentrate and optimizing collector additions. Both objectives have been achieved.

Jan 1, 1995

By R. J. Piniazkiewicz

Talc orebodies are mined in Asia, Australia, Europe, North America, and South America. Operators in North America must be efficient quality suppliers to thrive in a talc market in which many overseas suppliers have advantages such as lower hourly wages, shorter distances to ports, and less government regulation and intervention. Continuous improvement through teamwork and innovation is needed in the following areas to thrive amidst worldwide competition: 1) Maximization of the in-place value of ore. 2) Research and development to yield new processes and products. 3) Safe productivity. 4) Involvement in legislative processes. 5) Wellness programs to lower health care costs.

Jan 1, 1993

By D. K. Dysinger

Capital resource budgeting is the means by which managers of publicly held companies fulfill their fiduciary responsibility to maximize the wealth of stockholders. Managers maximize shareholder wealth by allocating investment capital to the most productive of competing alternative projects in a manner that maximizes the net present value of the firm's future cash flow. The techniques of cash flow analysis are the primary tools available for selecting a corporate portfolio of projects that meets or exceeds the rate of return expected by shareholders. The reliability of cash flow analysis hinges on the ability of managers to forecast the future values of individual components. The accuracy and reliability of forecasting determine the soundness of capital investment decisions and, ultimately, determine the value of the firm. The present paper will explore tools for forecasting the spot market price of a commodity, silver, to demonstrate the difficulty and uncertainty involved in forecasting the future. The commodity price is only one of a number of components of the cash flow equation. Each component has a unique and uncertain future and must be individually analyzed and forecast to arrive at a robust cash flow model.

Jan 1, 1997

By E. Yan, M. Mankosa, G. Luttrell

"During the past decade, column flotation cells have become widely accepted for upgrading ultrafine sulfide ores. However, the use of columns has been widely relegated to cleaner circuits due to their comparatively high selectivity derived from the use of wash water dispersed over a deep froth. High tonnage rates and low feed grades make using column technology in roughing and scavenger stages challenging due to the resulting size of the needed equipment. To specifically address this challenge, a new high-intensity flotation system known as the StackCell™ was developed. This technology makes use of a novel pre-aeration method coupled with froth washing to simultaneously provide improved flotation kinetics and selectivity. The novel aeration system provides efficient bubble-particle contacting thereby shortening the residence time required for particle collection. This article reviews the technical design features of this new flotation technology and presents recent data from in-plant pilot testing in a copper-sulfide application. INTRODUCTION Column flotation cells have become very popular in the minerals processing industry for cleaner circuits due to their ability to produce a high-grade froth concentrate via the use of froth washing (Luttrell et al., 1999; Kohmuench et al., 2004). The use of wash water minimizes the nonselective recovery of ultrafine impurities that are normally entrained into the froth product from conventional flotation machines. On the other hand, the unique design of a column cell typically requires a large tank volume. Column cells must be tall to ensure that the pulp residence time is long enough to offset their inherently slow flotation kinetics and to minimize internal mixing that is detrimental to overall cell performance. The tall design minimizes the total floor space required for the column installation, but substantially increases the foundation load. The large size of the column tank can also create issues during fabrication, transportation and installation. To address these concerns, the engineering team at Eriez Manufacturing developed a next-generation flotation technology called the StackCell?. This high-intensity flotation machine was designed to provide column-like separation performance within a very compact volumetric footprint. This article describes the key working features of this new technology and provides data from recent pilot-scale tests conducted in gold and copper-sulfide applications"

Jan 1, 2016

By John E. Dreier

The Pachuca-Real Del Monte district, Hidalgo, Mexico (Figure 1) has produced roughly 1,500,000,000 oz Ag., 6,000,000 oz Au. and minor Pb., Zn, and Cu from about 100,000,000 tons of ore since discovery early in the 16th century. Production has come from epithermal vein deposits that have been up to 8 km in length, 650 m in vertical extent and 45 m in width but which averaged 200-400 m in length and vertical extent and 2-4 m in width. Ore deposits occur through-out an area about 12 km E-W by 10 km N-S (Figure 2) and between the elevations of 2000 and 2800 m above sea level. The deposits occur as shoots in the veins and terminate laterally where the veins narrow, upward where the veins pinch out and downward where the veins decrease in silver con-tent to below the cut-off grade; the veins are known to extend 500 m below the bottoms of the ore bodies and probably extend to much greater depths. The district lies wholly within a mid-to-late Tertiary volcanic rock sequence that is made up principally of andesite and dacite lava flows and flow-breccias. Although the bottom of the sequence is not exposed in the district, stratigraphic constructions indicate the volcanic rocks to have an aggregate thickness of 2000 to 2500 m. Structurally, the area is characterized by gentil warping and normal faulting of the volcanic rocks. Pre-ore modifications to the volcanic rock sequence consisted mainly of faulting along west-trending, south-dipping normal faults and north-trending high-angle faults.

Jan 1, 1978

By David Green

Outokumpu introduced Flash Flotation in the early l 980's for the recovery of floatable material from grinding circuits. The devel­opment came as a result of surveys made in the company's own concentrators, initiated to find ways of improving recoveries with increasingly complex and lower grade feeds. Hydrocyclones make a separation on the basis of particle size and mass, resulting in the "over collection" of fine grained, high S.G. particles. Minerals such as pentlandite, galena and gold are easily caught in the circulating load around the mill until they are overground and rendered more difficult to collect. In the case of downstream flotation this may simply involve a reduction in the rate coefficient due to the finer sizes or, as is commonly experienced in gold operations, the mate­rial is slimed and coated onto non-floating gangue and is eventual­ly lost to tails. At the time of Outokumpu's plant surveys, it was a relatively common practice, particularly in Pb operations, to have a flotation section fed directly from the secondaiy mill discharge. This is called unit flotation and certainly provided an improvement but very high wear rates and frequent sanding out of the cells was com­mon. The development of the SkimAir® Flash Flotation cell by Outokumpu provided a subtle but quite dramatic departure from the unit cell approach. Now it was possible to feed cyclone under­flow into a special purpose-built flotation machine and recover a final grade concentrate from the grinding circuit (see Figure I). The cell was designed to handle the coarse circulating load, per­mitting the coarsest fractions to be short-circuited back to the mill and retain the floatable sizes for a nominal time of 30 seconds to several minutes. The short retention time was possible largely due to the relatively clean content of the cyclone underflow stream. This means that the fine gangue is not present except in small quan­tities and most of the fine to mid-size paiiicles are higher S.G. and more likely represent valuable mineral. This condition provides for very high rate coefficients. Typical operations would recover 40-60% of the valuable mineral in this fashion and improvements in recovery were typically from 2-5% for sulphide minerals to the 5-20% range for gold and silver.

Jan 1, 1998

By N. Prenn

"INTRODUCTION The 2014 SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (the SME Guide) has been adopted by the Society for Mining, Metallurgy, and Exploration, Inc. (SME). The SME Guide is recommended as a minimum standard and a basis for developing industry best practices in the classification of Mineral Resources and Mineral Reserves for public and private purposes. The Guide is therefore strongly recommended to be used by members of this organization. The SME Guide was updated in 2014 to include CRIRSCO (Committee for Mineral Reserve International Standards) core definitions, and it is envisioned that the U. S. Securities and Exchange Commission (SEC) will adopt the SME Guide in 2016. However, as of the end of 2015, the SEC Industry Guide 7 remains the standard for the U.S. reporting of Mineral Reserves. This paper will cover the classification of Mineral Resources and Reserves, a discussion of Modifying Factors, and the classification definitions and guidelines. The definitions and guidelines contained in this report are from the SME Guide. FRAMEWORK FOR MINERAL RESOURCE AND MINERAL RESERVE CLASSIFICATION Figure 1 illustrates the classification of Mineral Resources and Mineral Reserves using the Guide. Mineral Resources are divided into three classifications of Inferred, Indicated, or Measured while Mineral Reserves include Probable and Proven classifications. These classifications reflect improved knowledge and confidence of the deposit from the top of the figure to the bottom. In other terms, the deposit risk also decreases from top to bottom.The relationships in Figure 1 reflect different levels of geoscientific knowledge and different degrees of technical and economic evaluation. Mineral Resources can be estimated on the basis of geoscientific information with input from other disciplines to establish reasonable prospects for eventual economic extraction. It was not too many years ago that the classification of a Mineral Resource was based on the evaluation of a limited set of factors that included spatial drill hole and grade distribution (kriging variance, as example), distance to the closest hole, and number of samples used to estimate a block grade. These are still important considerations, but classification following the Guide must also take into account sample integrity, sample QAQC, database integrity and completeness, geological understanding, and geological and grade or quality continuity. In addition, a general consideration of the Modifying Factors, to establish reasonable prospects for eventual economic extraction, adds complexity to the classification."

Jan 1, 2016