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By Zong-Xian Zhang, Charlie C. Li

It has been observed that the rock debris of a strain burst event are often in the mode of tensile fracture. Seismic waves could create tensile fractures in the material nearby reflecting surfaces, such as at the boundary of the fracture zone and the rock surface of an underground space. The fractured rock could be ejected to the space when the seismic waves are powerful enough. The average ejection velocity of the ejected rock is a measure of the magnitude of a burst event. The ejection velocity is directly associated with the released energy from the seismic waves and with the strain energy stored in the rock prior to the burst. In some cases, the seismic wave induced tensile fracture and the energy conversion occur in successive moments during bursting. In this paper, tensile fracture caused by seismic waves is investigated through an 1D model. The relationship of the average ejection velocity of the ejected rock in a rockburst event is analytically established with the energy of the seismic waves and the strain energy stored in the rock.

Apr 26, 2022

By Ulf Marklund, Manfred Lindvall

Fighting the challenge of diminishing ore grades, low base metal prices and a changing pattern of ore supply, Boliden has now taken the second generation of the fully­autogenous grinding concept on stream, Using new design and a highly-developed process control system the benefits of conventional two stage autogenous grinding technology are obtained with a wide range of ore types. The APC grinding system has been developed further. A new design of the Boliden Pebble Extractor together with an advanced control strategy make the performance of the APC concept superior to all other grinding systems with any ore quality. The capacity and simplicity of the autogenous grinding concept is equivalent to the best SAG installations but the operational costs are up to 25 % lower than for SAG or other primary ball or rod mill systems. The concept is as flexible as conventional crushing and rod mill installations but investment and operating costs are of the order of 25 % lower. Also, from the metallurgical point of view, the different types of autogenous grinding system outperform all other comminution systems including SAG. From 1989 to 1991 four fully autogenous grinding sections have been installed at various concentrators at the Boliden company. Old crushing plants and rod and pebble grinding circuits have finally been replaced by highly productive and cost-efficient autogenous grinding equipment. Significant savings in operational costs have already been reported. Power consumption and maintenance costs have been reduced significantly. Productivity expressed as milled tonnes per operator has been improved. Metallurgical results have developed favourably.

Jan 1, 1992

By Mario E. Rossi

Often geometallurgical models are prepared at various project stages from very few data and are assumed to be representative of very large tonnages. These may include recovery models; crushing and grinding parameters and models; models of concentrate grades; models of acid consumption; etc. These models commonly do not carry a measure of uncertainty or variability, and are taken at face value at the time of design and planning. This paper proposes a proactive approach to modelling variability, providing uncertainty estimates and thus allowing for risk analysis and mitigation of geometallurgical models. The variability model is built up by understanding the limitations of the pillars of a geometallurgical model: data uncertainty; geologic model uncertainty; domain definition uncertainty; and parameter estimation uncertainty. Of these factors, typically domain definition is the most significant contributor to geometallurgical model variability. First, the fundamental supports for these models are briefly discussed, with domain definition emphasized. Second, two methods for uncertainty modelling are proposed. The first, more applicable to conceptual or early-stage projects, is a simpler and more expedient alternative that provides initial assessments of variability. This is intended to aid management in decision-making related to budgeting, including further sampling and testing. The second, a block-by-block approach that allows a detailed assessment of risk for specific designs and mine plans, thus providing further opportunities for mitigation. In the example provided, emphasis is placed in communicating this variability to both management and technical personnel in the form of “measured-indicated-inferred” indicators and also block-by-block confidence intervals.

Jun 25, 2023

By James W. Guider

Of all the technology available to the iron blast furnace operator, raw materials preparation is by far the most important. Superior raw materials have been basic to the success of the Japanese steel industry, and they are just as essential to the American steel industry in winning its competitive battle against foreign government subsidized steel imports. Therefore, the mine operator and the ore beneficiation engineer must strive to produce the highest quality raw materials possible to meet the precise demands of the modern blast furnace and steel plant.

Jan 1, 1978

By D. W. Frommer

In continuing its long range studies of methods of treating low-grade iron ores, the Bureau of Mines has developed a new selective flocculation, desliming, and flotation procedure that enables effective beneficiation of the finely disseminated ferruginous jaspers of the Marquette range, Mich. The process, developed on a bench scale and later confirmed in the 800-lb/hr pilot plant, comprises dispersion, selective flocculation, desliming to reject fine silica and clay, and flotation of silica from the remainder of minus 400-mesh pulps. Pilot plant flotation of two Marquette range ores, using the selective flocculation procedure on feeds containing 36 percent Fe, yielded iron recoveries of about 84 percent in concentrates containing 65 to 66 percent Fe and 4 to 5 percent silica. These results were metallurgically superior to those obtained when selective flocculation was not used. Also operating characteristics were better, and reagent costs were lower.

Jan 1, 1964

By Ralph Musick, Brian Briggs

The U1h Shaft Project is a design/build subcontract to construct one 6.1 meter(m) (20 feet [ft.]) finished diameter shaft to a depth of 321.6 meters (m) (1055 ft.) at the Nevada Test Site (NTS). Atkinson Construction was subcontracted by Bechtel Nevada(BN) to construct the U1h Shaft for the Department of Energy (DOE). The project consists of furnishing and installing the sinking plant, construction of the 321.6 m(1055 ft.) of concrete lined shaft, development of a shaft station at a depth of 297.5 m(976 ft.), and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper will describe the design phase, the excavation and lining operation, shaft station construction and the contractual challenges encountered on this project.

Jan 1, 2001

By M. Javier

Mining is most vital to our civilization. The current model of extraction technologies was designed without an expiration date and therefore generates environmental effects that are severe. Mining results-effects have been traditionally accepted and promoted around the world since Agricola described mining. Mining’s extractive technology is outmoded and standardized and inflicts negative results-effects on nature. Those results are liabilities dimensioned in legacy and type of nature able to provide to the next generation. In order to design, build, and transform mining effectively we must ask: What is the vision of mining? Mining has exhausted its antiquated mindset of over 200 years. Now it merely pilots us into crisis. The challenge today is to resolve the socio-environmental conflicts globally with a radical transformation of the mining business at its core. This paper illustrates that old mindsets must be radically updated or the concept of mining will continue to be trapped. Changing the mindset will enable discourse toward a new destiny. These changes will change mining for the better. We are able to evolve and get different results than in the past by pursuing a new legacy to live in harmony with nature for many more years. INTRODUCTION Minerals are supported by the law of conservation of mass. They have the unique characteristics of being finite, exhaustible, unsustainable, and have an unlimited recycling. Minerals are also hard to find because we have explored and virtually exhausted the whole crust of this planet. Orebodies that used to be considered world class are almost exhausted. In the short-term, it would be almost impossible to find new world class orebodies unless they could be extracted from the ocean, the moon or other planets like Mars. Mining is designed to extract minerals for profit and to keep civilizations functioning. Subsequently, mining has a social issue that is an economic issue. Thus, mining must be seen as a real and urgent subject matter that must be protected in thought and in fact. The actual mining extractive technologies produce disequilibrium in nature that has unknowable effects in the course of time. History is filled with the negative consequences to nature due to the model of mining. The evidence of these effects from mining’s model is apparent in repetitive liabilities around the world. The effects negatively impact nature without any consideration to how these impacts will manifest themselves in the future. This model of mining is widespread and extolled in every corner of the planet because it is old and familiar and although wasteful and outdated, we do not want to expend financial resources from profit or elsewhere to explore newer ideas, methods, or technologies that would help us keep a sustainable harmony between extraction and nature. We need a new vision for mining today and to explore in what way academia can and must play a social role in the teaching of mining methods. We need to question why we continue to support the old model of mining and to ask ourselves what prevents us from updating and modernizing the method of mining to meet the current needs not just of civilization but the urgent needs to undo some of the damage to the earth. This paper hopes to develop a method to change our minds about how we conduct the business of mining in order to control the destiny of it.

Jan 1, 2019

By J. Herhold, S. Plaum

"Increasing worldwide energy demands, coupled with desires for cleaner energy, have led to greater research of renewable energies. Strongly weather-dependent energy sources, e.g. solar and wind energy, are unable to provide a constant control energy to withstand the fluctuation of the extensive power systems during peak hours. The pump storage plant Nant de Drance in Switzerland will not only have the capacity of a nuclear power plant, producing 900 MW, but will also combine the environmental aspect and the demand for controlled energy. Nant de Drance is one of the pioneer projects for upcoming energy challenges and serves as a model for future pump storage plants. This paper focuses on the planning process and the project execution of interdisciplinary large-scale projects such as Nant de Drance, including project related data handling, communication systems and project handling skills. Furthermore, the paper discusses mining excavation in the context of large scale projects and their regional environmental challenges, e.g. high alpine rock mass on the site of Nant de Drance. PROJECT BACKGROUND Project Overview Nant de Drance is a 900 MW pump storage plant located in the Swiss Alps. To provide such a high energy storage, six turbines (reversible Francis type), each with a capacity of 150 MW, were installed. Due to the efficiency factor of 80% the pump storage plant is able to provide an energy production of 2500 GWh per annum. Construction of the pump storage plant, which has been selected as “Major Tunneling Project of the Year” in 2014 by NCE and ITA-AITES, will be completed over 10 years. Therefore, the project has been divided in six major phases outlined below: - Launch: 2008 - Access Gallery: 2010 – 2012 - Excavation KMA, KTR: 2011 – 2014 - Concreting KMA, KTR: 2014 – 2016 - Installation of HEM equipment: 2014 – 2018 - Tests & entry into service: 2017 – 2018 Figure 1 outlines the single process phases of the project. For the construction of the shafts, galleries and caverns, 1.7 million m³ of metamorphic rock with sedimentary origin (mica schist & paragneiss of the massif „Aiguilles Rouges“) were excavated. A tunnel network with a total length of 15 km was created. The machine cavern measures 194 m long, 32 m wide and 52 m tall."

Jan 1, 2016

By Ademar Lopes, Victor Silva, Heitor Silva, Gustavo Usero, Roberto Rolo, Lucas Pereira, Gabriel Moreira, João Lague, Arthur Endlein, Matheus Feitosa

Grade control models are supposed to provide a higher resolution than long-term or interim models. However, available grids from diamond or reverse circulation drilling do not provide that required resolution. In this study, a geostatistical workflow is proposed to integrate available grade data from production blastholes with its operational parameters taken when drilling downhole. The step of geological logging can be replaced by machine learning models for classifying blastholes into lithologies and hardness classes. Next, indicator and ordinary kriging use the classified blastholes and previous data for estimating the model domains and the grades within each one. The workflow is applied in a world class iron ore mine in Brazil.

Jun 25, 2023

By Peter Johnson, David Barber, Lachlan Henderson

"Within underground portions of metro rail networks the traditional approach to a design fire has been to assume a worst credible railcar fire and develop ventilation and egress measures for life safety. This approach is being challenged as a rail network approach to design fires becomes a more practical and realistic approach. The network approach is based on utilizing an in-depth hazard analysis, to understand ignition and fire load sources in tunnels, above and below the floor of the railcar and within stations, and then utilizing a quantitative risk assessment to determine sets of fire scenarios. The process allows small, medium and large fires to be considered, with the consequences also being quantified. The selection of design fires has a significant influence on fire protection measures within a metro network and hence, is a major cost input. The rail network approach provides more robust decisions on fires, based on the hazards present. INTRODUCTION A fire within a rail car or one that occurs as part of a rail system can threaten the lives of users, maintenance staff and emergency services personnel. Fires in metro systems are rare events but can have severe consequences. As a result, any analysis of a potential fire must be thorough and rigorous and address not only regular accidents and small fires, but also very low probability, high consequence scenarios. The fire safety design process for a tunnel and station must start with the design engineers, contractor and operators making a number of key decisions related to fire protection measures, which may have significant cost considerations. One of the key aspects that influences the required fire protection is the design fire and the design fire scenarios, which is a key input for analysis. This paper provides an overview of the author’s experience in designing fire protection measures for rail networks in Europe, Australia and NZ, where a risk based framework is used to develop design fires and scenarios for the whole rail system – trains, stations and tunnels. This system wide approach is innovative, challenges the norms, but provides significantly more informed outcomes. The range of design fires will include small fires that may halt the network, larger fires for smoke hazard system design and significant post-flashover fires to assess the structural response."

Jan 1, 2016

By Greg T. Saretzky, Wilson G. Ward

A comprehensive hydrologic study was completed far the waste rock dump at Equity Silver Mine, BC. Characterization of the hydrologic system included geologic structure. topography, surface hydrology and groundwater systems. The results of the study conclude that the cover system is restricting net infiltration to approximately 5%. However, significant discharge continues to occur from the perimeter of the dump. A three dimensional seepage analysis was carried out to illustrate the influence of groundwater discharge associated with the regional topography and geologic structures. The results of the modelling program show that groundwater discharge occurs from the waste rock dumps when high recharge rates are specified for the surrounding topography- This groundwater discharge strongly influenced by the high hydraulic conductivity assumed far the fractured bedrock. The modelling results are considered preliminary and field drilling and piezometer installation is being conducted to determine the groundwater regime in the vicinity of the waste rock dump.

Jan 1, 2000

By P. Worley

With Utah Power & Light Mining Division's commitment to operate the safest and most productive mines possible, a decision was made to purchase and install mine-wide monitoring systems for use in the mines. After review of several different systems the Conspec Senturion 200 system was chosen. Three separate systems were ordered to fulfill the monitoring requirements of the six mines in operation: one system for the Deer Creek Mine one for the Wilberg/Cottonwood complex, and one for the Deseret, Beehive and Little Dove complex.

Jan 1, 1989

By Taghi Sherizadeh, Paul Brooks, Dogukan Guner, Samuel Nowak

Large excavations are well known to result in rock mass deformations which can present challenging situations for mine personnel. Most of the currently available ground movement monitoring devices fail to adequately provide mine operators with highly accurate and meaningful insights into rock mass deformation or displacement. The use of distributed fiber optic sensors (DFOS) in industries such as oil and gas and civil engineering has shown the potential of these sensors to deliver real-time, highly accurate, and long-range distributed strain measurements with great success. However, the use of these sensors in underground mining is limited to a few case studies.

Bauxite mine rehabilitation is an important stage of today’s bauxite mining activities. To get an overall picture on those activities the International Aluminum Institute (IAI) has been carrying out Bauxite Mine Rehabilitation Surveys since 1991. The most recent survey from 2003 covers 70% of the world’s bauxite production and 23 corresponding companies from 12 countries. The survey activities show that nearly all operations refer to a sophisticated environmental management strategy. By setting up a review scheme based on the principles of the Global Reporting Initiative the compliance of this survey to aspects of Sustainable Development has been reviewed. The Clarification of a multitude of aspects based on the GRI guidelines helped to structure recommendations and relate them to the survey as such but also to the different stakeholders involved.

Jan 1, 2005

By W. S. Fyfe, R. J. Puddephatt, S. Zhou

Gold is easily mobilized at temperatures within range 600-11OO°C by gases such as Cl2, CO, H2S, in gas mixtures, at low pressures. Such gases are relevant to conditions of granulite facies metaomorphism in environments of magma underplating. These observations suggest an efficient mechanism for moving gold to the upper crust during major thermal events. The efficiency of precipitation of gold at lower temperatures is related to available mineral surfaces and pyrite appears to be an excellent substrate for gold precipitation.

Jan 1, 1989

By Robert A. Haney, Scott G. Vail, Kenneth G. Fields

The Mine Safety and Health Administration, in cooperation with IMC Global Operations, Inc., conducted a joint study to determine the effectiveness of the technology currently in use at the mine to control diesel particulate exposures. IMC Global operates an underground potash mine using diesel-powered equipment to extract minerals. IMC uses a variety of technologies to control worker exposures to diesel particulate. These technologies include: ventilation, low sulfur fuel, oxidation catalytic converters (OCC), maintenance and work practices. The study was conducted over a two-week period, two shifts per day. During the first week (six shifts), baseline data on exposures and diesel particulate emissions were obtained. New OCC's were installed over the weekend on all equipment on the test section. During the second week (six shifts), data were collected to assess the effectiveness of the new OCC devices. In addition to exposure and diesel particulate emissions data, mine ventilation, engine exhaust temperatures and mine operational data were obtained. The primary means of determining diesel particulate concentrations was the respirable combustible dust (RCD) method. Gas concentrations carbon monoxide (CO), carbon dioxide (CO,), and nitrogen dioxide (NO,) were measured using passive dosimeter badges and gas bottles. Results of measurements of diesel particulate, gases, and air- flows were analyzed to determine the effectiveness of airflow and oxidation catalytic converters for controlling diesel particulate exposures. The use of oxidation catalytic converters resulted in reductions of both workers' exposures and diesel emissions.

Jan 1, 1997

Growing concerns of climate change and its potential association with the release of greenhouse gasses to the atmosphere have prompted possible legislation which would require minimization of greenhouse gas emissions. Carbon dioxide and methane, both of which largely contribute to the greenhouse effect, have direct links to the fossil energy industry sector. Specifically, the combustion of one ton of coal produces between one and three tons of carbon dioxide, dependent upon the carbon content and heating value of the combusted coal. Additionally, coal mine methane (CMM) released through a mine?s ventilation system has a radiative trapping impact approximately 20 times greater than that of an equivalent mass of carbon dioxide. The capture of coalbed methane (CBM) prior to the mining process and its utilization as an alternative energy source provides the possibility of a decreased carbon footprint. Domestically, the past 25 years have seen a significant expansion of the CBM industry. Internationally, in developing countries such as China, the need for western coal degasification technology is growing. A collaborative, international effort will be required to initiate a recognizable decrease in global greenhouse gas emissions. This paper identifies the potential decrease in equivalent carbon dioxide emissions through effective degasification at a hypothetical longwall mine located in China. Advanced, three-dimensional gas reservoir simulation software will be utilized to determine the maximum feasible CBM recovery in a low permeability, high gas content reservoir prior to the mining process.

Jan 1, 2010

Since 1992 the Grasberg Mine, located in the remote regions of Indonesia, has utilized the Modular Mining System. Over the last several years, major steps have been taken to maximize this productivity enhancement system. These steps include; the Automated Lineup, the Linear Program upgrade, tracking of Mean Time Between Failure, a MEDS system interface, a VMIS system interface, and implementation of the new Graphical Operator Interface Console with Global Positioning, This application of new technology and innovation has lead to improved performance, understanding and reporting, as well as the quality of the Indonesian Engineers. These efforts have contributed 10 Grasberg achieving one of the lowest mining costs in the copper industry.

Jan 1, 1998

By B. Culkin

The production of fine particle products within the mineral processing industry is a very important market segment. Many of these products are processed in an aqueous state and must ultimately be dewatered. This entails processes which are very energy and capital intensive. The introduction of membrane based dewatering systems has offered great promise in the area of energy saving and operating costs. Unfortunately, membrane separators have not yet had the ability to handle high solids. New Logic introduces a system which can concentrate a low solids stream to a high solids sludge in a one pass, very energy efficient system.

Jan 1, 1993

By Karin Bäppler

Lyon with half a million inhabitants is the third largest city in France. Urban agglomerations such as Greater Lyon demand intelligent underground solutions for the freedom of mobility of its inhabitants. The city and metropolitan area of Lyon provide an example of a city strategy adapted to the changing needs due to demographic and living standard trends. The Lyon Metro Line B with a length of 2.4 km is one of the strategic projects with regard to city planning and future mobility. The paper will highlight on this special area of application in singular diverse geology with sophisticated mechanized tunnelling technology.

Jun 13, 2021