Search Documents

By A. B. Cecala

Enclosed cabs have been used for many years to isolate workers on mobile equipment in the mining industry for health and safety reasons. These enclosed cabs create a microenvironment for workers where they can be either more protected or more vulnerable to contaminants. Over the past decade, the National Institute for Occupational Safety and Health (NIOSH) has performed substantial research efforts to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment. In these efforts, NIOSH has partnered with mining companies, original equipment manufacturers (OEMs), and manufacturers of filtrations and pressurizations systems in a synergistic effort to reduce respirable dust and improve the air quality inside these enclosed cabs. Various field studies over this time have shown an array of results ranging from very minor to very significant reductions (protection factor: 3 ? 89) in respirable dust levels inside these enclosed cabs. In addition to and concurrent to the field work, NIOSH also performed a comprehensive laboratory study to evaluate all the factors involved in cab filtration and pressurization systems and identified those factors that were most significant for an effective system. From this comprehensive research effort, the key components for an effective filtration and pressurization system have been identified in an effort to provide the best air quality, thus minimizing the respirable dust exposure, to equipment operators inside of enclosed cabs of mobile mining equipment.

Feb 27, 2013

By James W. Babcock

Introduction Geologic ore deposit models are key to any exploration program. In the search for ore deposits, the geologist first tries to understand the genesis of known ore bodies. During reconnaissance and evaluation of a prospect, a valid exploration model of a known ore body can help the explorationist focus on critical geologic attributes of the target area. Exploration models can conserve exploration funds that might otherwise be spent collecting data not critical to delineating an ore body. This article examines the benefits of using models, factors to be considered in developing models, and examples of the way recent models have evolved. New exploration concepts and techniques are developed in response to increased competition in the mining industry. New techniques can give an exploration group a slight edge that may translate into a discovery. Mine geology staffs may find previously unlooked for extensions to the ore body by applying new genetic concepts. When all appropriate techniques are applied to exploration and mining efforts, greater efficiency and increased profits may result. Before the 1950s, scientists speculated on the genesis of ore deposits and other natural phenomena. But they presented their results as if universal and final, even though they applied to only a few deposits. Because it did not provide sufficient criteria to distinguish the genetic processes, the classic conflict between hydrothermalists, epitomized by Lindgren, and nonhydrothermalists did not help the minerals explorationist much. Important information about individual ore deposits, such as age of the host rocks and mineralization, composition of the mineralizing fluids, and separation of mineralizing and nonmineralizing events in the paragenetic sequence, could not be gathered with past equipment and methods. But these early concepts of ore genesis contained excellent empirical observations, perhaps the most useful parts of these hypotheses. Through the years, prospectors have found most of the ore deposits in the world using direct observations and their collective empirical wisdom - an empirical model. The geologist's contribution becomes increasingly important after the more obvious surficial ore deposits have been discovered. In Europe and North America that time has arrived. With the introduction of sophisticated equipment and matching techniques in the 1950s in geochronology, geochemistry, geophysics, remote sensing, and computers, many previously equivocal genetic questions can be resolved. This proliferation of highly technical data has allowed the construction of many well-founded genetic models.

Jan 12, 1984

By John Corcoran

INTRODUCTION Content of this Report The 1300m long twin-bore 8.1m diameter Airside Road Tunnels (ART) were excavated beneath the busy taxiways and stands of Heathrow Airport between 2002and 2003. The tunnels were fully completed and handed over to the client for use early in 2005. This paper will describe the purpose of the tunnels, and the measures put in place to minimize the impact of construction on the daily activities involved in running an international airport. Terminal 5 Construction Heathrow Airport is the busiest international airport in the World, with a current capacity of circa 67 million passengers per year, based on existing infrastructure of4 passenger terminals, 1 cargo terminal, 2 runways and 170 aircraft stands. Terminal 5(T5) is being built to increase Heathrow’s passenger capacity by providing the following: 12 additional aircraft stands through redevelopment of the south apron area, in the autumn of 2004 A main terminal building (T5A) and a first satellite (T5B), and 43 additional stands by the spring of 2008, most of which will be able to receive the new generation large aircraft (Airbus A380) A second optional satellite (T5C) by year 2010 A third optional satellite (T5D) by year 2015 The total value of the project is approximately 4.2 billion pounds for the main phase of the works spanning from 2000 to 2007. Purpose of the Airside Road Tunnel The ART has been constructed to support the internal road traffic of the airport between terminals, aircraft stands, runways and taxiways, for passenger buses, service and technical vehicles. The majority of the traffic will be buses transporting passengers between the terminals and their aircraft.

Jan 1, 2005

Overland conveyor belts that exhibit tracking problems under loaded and unloaded conditions can be tested to' determine the root cause of the mistracking. Moveable conveyors are more prone to mistracking due to structure alignment requirements. In addition, belting quality, splice straightness and carcass condition has a dramatic effect on the performance of a belt in relation to tracking. Methods are discussed that are proven to reduce belt mistracking and improve the operational reliability of the conveyor system.

Jan 1, 1995

By R. Bokotko, J. D. Miller, J. Hupka

Laboratory results from an initial study on the removal of SO2 from gas mixtures are reported using air-sparged hydrocyclone (ASH) technology. Tap water and alkaline solutions were used for absorption and the influence of gas flow rate, water flow rate and length of the ASH unit were investigated. Complete removal of SO2 was possible with very favorable kinetics. The efficiency of sulfur dioxide absorption from air using the ASH is compared with the efficiency of conventional technology.

Jan 1, 2002

By R. R. Dorfler

The existing regrind circuit at the Climax Operations uses sodium cyanide and Nokes reagent to reject pyrite, copper, and lead minerals. Laboratory flotation studies were performed using feed to flotation following first-stage regrinding. The effects of conditioning time, pH, and the concentration of depressants such as Nokes reagent and sodium cyanide on the rejection of pyrite, lead, and copper minerals were investigated. The metallurgical results indicate that, in the presence of depressants, the rejection of copper is strongly dependent on the pH. Preliminary mill testing confirmed the finding. The rejection of impurities is also dependent on conditioning time. The recovery of molybdenite is independent of the variables investigated.

Jan 1, 1981

By Anibal Gajardo

Because of the Chilean Ministry of Mining's interest in the development of industrial minerals, the Chilean Geological and Mining Service (Servicio Nacional de Geología y Minería, SERNAGEOMIN) has carried out a research program during the last two years to identify projects that represent interesting investment opportunities for small- to medium-scale operations in Chile. Most important of these projects are: (1) Quebrada Lluta aluminum sulphate, for drinking- and industrial-water treatment, with a potential domestic and foreign mar- ket of almost 43,000 tonnes per year and investments of about US$1.8 million; (2) Quebrada Lluta-Quebrada Cardones pumice, for abrasives, filters, fillers, and light- weight aggregates, with a potential market of about 30,000 tonnes per year, and in- vestments of US$2.0 million; (3) El Maule dolomite, for soil conditioner and iron smelting, with a total potential domestic market of some 60,000 tonnes per year, and estimated investments of US$2.0 million; (4) Las Escaleras bentonite, for animal feed, pelletising, and oil absorbents, with a potential market of almost 6,000 tonnes per year, and investments of about US$2.4 million; (5) Laraquete-Carampangue andalucite, for alumina refractories, with a future total domestic and foreign demand of about 15,000 tonnes per year, and estimated investments of US$2-2.5 million; (6) Rio Lía garnet, for fillers and sand-blasting abrasives, whose domestic market represents 10,000 tonnes per year, with investments of US$2.3 million; and (7) Munilque pumice, for building bricks and panels, with a potential domestic market of 250,000 tonnes per year, and investments of US$1.4 million. The development of these projects will represent an important increase and a significant diversification in Chilean industrial-minerals production.

Jan 1, 1999

By L. C. de Kooker, K. Esmaeili, I. Musonda, M. Ferentinou

This paper presents the results of an investigation into the effect of pore pressure regime on the factor of safety (FS) and the anticipated critical failure mechanism for a fly ash storage facility. In this study, pore pressure measurements from standpipe piezometers and pore pressure estimated from seepage analysis were used for a comparison of the estimated FS for a fly ash slope. This comparison was applied for static and seismic scenarios. To account for the uncertainties resulting from the limited data available and support a qualitative risk assessment evaluation, a probabilistic analysis was performed. The slope stability analysis was conducted in 2D and 3D, adopting the limit equilibrium analysis approach, and a finite element seepage analysis. The results suggest consistency of failure surfaces for 2D and 3D and an increase in FS values of 5 percent for the 3D approach, limitations of standpipe piezometers. The study demonstrated the sensitivity of the FS value, and the implication of adopting representative material properties, and water table levels, especially in cases where limited data are available, and assumptions need to be made to assess the long-term stability of a fly ash dam facility.

Aug 1, 2024

By Stephen Krickovic

"Bleeding", as used in mine ventilation language, has a number of meanings among mining men and is regarded with different degrees of importance. This lack of uniformity stems from a number of specific situations. A method that is adequate in a mildly gaseous mine may fall short in a very gaseous mine. Projected bleeders could be dependable under a certain type of roof, and totally unsatisfactory under a different type. Similarly a plan of bleeders can be rendered useless due to undulations of seam and water in one mine and function well in another. Finally, what is effective in a mining system with partial recovery will not suffice with full recovery. You may wonder, then, if there is a common denominator for the essential function of "bleeding". In my opinion, there is, and it can be defined as controlled movement of air across an active pillar line toward the back and outby ends of the adjacent gob area into the headings provided for the purpose. The objective is to maintain as methane-free as practicable a belt adjacent to the working places, so that, if face ventilation is interrupted temporarily, the gas will not accumulate in dangerous volumes at the working faces before ventilation is restored. It's possible for these temporary interruptions to be unnoticed in time or at all. In such cases, ineffective bleeding could cause a disaster. This has happened. To control, there must be power. That is to say, there must be adequate air, pressure differential between the front and back ends of a pillar line to facilitate proper regulation for diverting of air to the various portions of the gob and as far away from the active section as is practicable. As an indication of the importance of pressure, it is noteworthy that one may provide and maintain in a reasonably open condition a heading or two for a bleeder system and fail to obtain effective bleeding .because air pressure differential is inadequate. On the other hand, you are all familiar with the fact that pillar lines in some seams can be ventilated adequately by air flow straight across the gob when the section is near a main return shaft and thus obtains a heavy pressure differential.

Jan 1, 1962

By S. Tafazoli, D. Cooper, I. Bell, S. Nouranian, B. Sameti, M. Ramezani

"Image-based rock fragmentation sensing in mines and quarries includes an important rock boundary delineation step, commonly referred to as rock segmentation. This paper presents an artificial intelligence-based solution to this challenge. The proposed technique encodes prior knowledge of previously analyzed images into mathematical/statistical models. Human-labeled images are used as inputs to train neural networks through an optimization process. The networks can then be used in real time for rock delineation. To build the models, special deep artificial neural networks are used as a pixel classifier. The proposed classifier labels each pixel (edge, rock or fine) by analyzing a plurality of pixels within the image. Advances in machine learning allow the network to contain many parameters. The increased number of parameters is a strong factor in the classifier’s ability to correctly classify each pixel. Deep learning-based segmentation, combined with 3D imaging followed by post processing, provides a unified fragmentation sensing solution. Results from automatic segmentation are compared to human labeled segmentation using the percentage passing curves for 64 rock images. INTRODUCTION Mines and quarries can see significant productivity and performance benefits by controlling material sizes (McKee, Chitmobo, & Morrell, 1995; Sellers & Gumede, 2012). During the past decade, image-based fragmentation analysis has been applied to estimate rock size distributions in order to optimize procedures in mines and quarries. Using a roving camera and operator assisted analysis Maerz, Franklin, and Coursen (1987) measured the size distribution of the blasted rock and eliminated the need for manual sieve analysis. Since then, many others have introduced automated and manual methods for fragmentation analysis and improved upon existing approaches (Girdner, Kemeny, Srikant, & McGill, 1996; Smith & Kemeny, 1993; Palangio, Palangio, & Maerz, 2005; Tafazoli & Ziraknejad, 2009; Raina, 2013). In image-based fragmentation, rock boundaries are identified in the image, and an image scaling is applied to transform rock pixel sizes into real world dimensions. Usually geometric references, such as regularly shaped objects (discs and basketballs) (Siddigui, Ali Shah, & Behan, 2009), or the known size of an excavator bucket (Zeng, Chow, Baumann, & Tafazoli, 2012), are used to determine the proper scaling factor. In recent years, 3D imaging and sensing have also been incorporated to improve rock delineation. Specific methods include using camera-laser combinations and stereo imaging to measure rock fragmentation on conveyor belts (Noy, 2013; Thurley, 2013; Dislaire, Illing, Laurent, & Pirard, 2013) as well as portable fragmentation analysis devices with 3D imaging sensors (Sameti, et al., 2014)."

Jan 1, 2018

By Norbert Patzelt, Johann Knecht, Wolfgang Baum

The principle of high-pressure interparticulate comminution has been used very successfully since the mid 1980's for grinding a wide range of different materials. A number of reports about operating experience have already been published. High-pressure grinding rolls (HPGRs) are currently making their debut in the mining industry. Experience is being gained with test machines, particularly for the comminution of hard rock. In the grinding of diamond-bearing ore, (Fig 1) interparticulate comminution has already become the standard for liberating the diamonds from the matrix. The advantages of interparticulate comminution are also recognized for the grinding of concentrates (chrome ore, iron ore). Numerous HPGRs are being used very successfully in this field. A testing plant for first-time industrial grinding of coarse, very hard and highly abrasive copper ore was built at Cyprus Amax's plant in Sieretta, Arizona (Fig. 2). The operating experience gained here showed that the grinding of very hard ores places particularly high mechanical demands on the mill. While the machine itself meets the high availability requirements, the wear-protection system proves to be the most sensitive point. Naturally, the properties of the ore to be ground exert a considerable influence on the lifetime of the grinding rolls. This paper describes the wear mechanisms and the wear­protection systems designed to combat these.

Jan 1, 1997

By Daniel Roy, Danielle Bouffard, Antoine Berton, Simon Gariépy

Commissioning a mineral processing plant has always been a challenging task. The process includes pre- operational verification, dry and wet commissioning, and a gradual ramp-up to full production, all of which must be executed within the shortest possible timeframe, requiring numerous highly interdependent tasks to be conducted concurrently. This phase is under scrutiny by shareholders, corporate management, and other stakeholders who are keen to see a return on investment as the operation starts yielding results. Despite extensive documentation in the literature highlighting its significance, the impact of the commissioning phase remains underestimated in contemporary mining projects. This paper provides an overview of the commissioning process and its associated challenges before focusing on a critical success factor: building a dedicated commissioning team with the required competencies and personality profiles. The roadmap to achieving an efficient plant start-up is outlined. Drawing on over 15 years of experience with more than 20 concentrator commissioning and start-ups, a general framework is presented to maximize success. This method emphasizes the crucial role of the operation and metallurgy team in supporting these projects. Finally, insights from Soutex’s involvement in multiple start-ups are shared, offering lessons learned that emphasize best practices and challenges encountered in expediting the ramp-up process while maintaining high Health, Safety, and Environment (HSE) standards.

Feb 1, 2025

By S. Donges, P. L. Dunstan, B. J. Huls

The commissioning of a distributed digital control system for the grinding circuit at Cuajone was completed by mid-August 1985. Development of a successful strategy, excellent operator acceptability, and the visual aspects offered by the display of the central console improved mill through- put significantly. The inherent features of a digital system enhanced the flexibility in grinding control and allowed the milk and classifiers to be operated at maximum capacity. This paper discusses the strategy development and the production restrictions encountered, and evaluates the overall performance of the digital control system.

Jan 1, 1988

By D. Buranek, J. G. Wulff, F. W. Gifford

I. INTRODUCTION During the past few years, the state of the art of disposal of solid and liquid waste products from uranium mining and milling operations has experienced some rather interesting and significant changes. Some of these changes have resulted from technological advances in the milling operations and in the engineering aspects of the actual design and construction of the disposal facilities. However, the most significant changes, at least those which have had the greatest impact on the comparative cost and economics of modern disposal systems, have been environmental requirements and regulatory controls, which have become increasingly stringent in recent years. Without delving into the details of the myriad of new laws and regulations which now control the uranium industry, it can be stated with reasonable confidence that one of the principal purposes of more rigid state and federal controls over this industry is the basic desire to promote safer, more reliable and longer term means of effectively controlling and disposing of the potentially objectionable waste products resulting from uranium mining and milling operations. It is difficult to take issue with these basic goals because their need was spawned by past lack of awareness and inattention on the parts of both government and industry to the long term environmental problems and potentially hazardous conditions which can be created by limited planning and ill-conceived or poorly controlled and executed disposal practices. On the other hand, despite the good intentions of those who developed and those who are administering the regulatory controls now in effect, the basic danger exists that overgeneralization of the approach to disposal problems and overrestriction of the potentially acceptable solutions for uranium mine and mill waste disposal could have a significant, adverse economic impact on the mining industry and the ultimate consumers of their products. The regulatory pendulum, which perhaps swung too far toward lack of controls over uranium mill waste disposal in the 1940's, could now well be headed too far in the opposite direction, that is toward over-regulation in the form of restrictions based on technically unrealistic or weakly supportable

Jan 1, 1980

By R. J. Snoby, M. A. Short, A. Jungmann

In processing coal, the low concentrate value requires high capacity production and sharp classification/separation techniques to reduce specific production costs. The allflux separator meets these criteria with a unique two-stage design. Through a combination of rising current and fluidized bed technologies, the allflux has extended the state of the art by expanding the particle size range that can be efficiently processed. Using concepts that have proven successful in processing concrete sands, small-scale industrial testing with coal feed stocks looks very promising. Attractive applications for the allflux are projected in fine coal recovery from old settling ponds or as a retrofit in existing fines circuits.

Jan 1, 2001

By M. P. Meehan

The purpose of this paper is to present the key elements in a system; study of the electrical system for a timing and/or tilling operation. The ability of an electrical system to function in a reliable fashion at its proper levels is essential for an operation to be successful. A system study consists of a load study for determining the capability of the electrical network to provide power to the various loads and a short circuit study for determining the capability of the electrical protective equipment to properly protect against fault conditions. The sequence of events in a system study is data acquisition, determining the electrical parameters and analyzing the ability of the system to meet these requirements. If the system is small, herd calculations will be the manner in which the study will be conducted; if it is large then commuters will be used. A load study has as its objectives the determination of the capability and reliability of the source of power, transformers and conductors to satisfactorily deliver power to the loads at an acceptable voltage level. The Information required is a single line diagram showing the source, transformers, conductors and loads.

Jan 1, 1980

By E. Woodburn, H. W. Smith, M. C. Fuerstenau, R. Putman

This paper presents a review of developments to date in computer control practice, based in large part on Canadian experience. The basic problem examined is that of stabilizing control; matters considered are control strategies, hardware and software aspects of system implementation, reliability, human factors, and economic results.

Jan 1, 1976

By M. E. Hinkle

Concentrations of He, CO2, and O2 in soil gases were measured regularly for more than a year at a site near Golden, Colorado. Samples were collected from a hollow probe at 0.75-m depth and from a plastic hemisphere on the ground surface. Soil temperature, air temperature, percent humidity, And barometric pressure were also measured. Soil moisture was measured only indirectly as amount of rain or snowfall. Higher concentrations of CO2 in both the 0.75-m and surface samples correlated with higher soil and air temperatures, which suggests that CO2 was produced by bacteria. Lower concentrations of helium in both the 0.75-m and surface samples correlated with higher soil and air temperatures. Rain and snowfall appear to affect helium concentrations. Carbon dioxide concentrations were lowest when snow lay on the ground for extended periods of time. No correlation was seen between barometric pressure or percent humidity and concentrations of He, CO2, or O2 at 0.75-m depth or at the ground surface. No correlation, either positive or negative, was seen between concentrations of CO2 and O2.

Jan 1, 1988

By A. Vilinska

The adhesion of Leptospirillum ferrooxidans bacterial cells onto the sulfide minerals pyrite and chalcopyrite was evaluated using two different physical-chemical approaches; thermodynamic and extended DLVO theory. For the parameters incorporated into calculations, the zeta potentials and contact angles of powdered solids and bacterial cells were acquired experimentally. The Hamaker constants essential for Lifshitz-van der Waals inter-action calculations were calculated following two different methods: macroscopic and microscopic. Adsorption tests were carried out at physiologic conditions to estimate the amount of cells adsorbed onto a mineral surface and the extent of alteration of that mineral surface in biobeneficiation. The free energy of adhesion was found to be negative for both minerals, indicating that the adhesion is energetically favored and preferred. The interaction energy diagrams of the total interacting force was also negative for the cases where the particles were charged oppositely; in the remaining cases, the total force was attractive after overcoming an energetic barrier caused by the repulsive electrostatic forces. Under the conditions of the adsorption test, the experimental results are in agreement with the theoretical; this suggests that the physical-chemical forces are crucial for bacterial adhesion.

Jan 1, 2011

By J. Mattern

Performance monitoring, operational practices and ongoing collection of geologic data in open pit slopes all provide valuable information for quantifying potential steepening of subsequent slopes. Mining at the Goldstrike open pit has been ongoing since the early 1980’s, with its share of slope instabilities. In areas where slopes have remained stable, consideration has been made for potential slope steepening of final walls. With the proper available equipment, steepening of bench face angles via pre-split blasting is not an uncommon method for steepening of inter-ramp slope angles. As an alternative at Goldstrike, the commonly used Modified Ritchie Criteria for empirical catch bench width has been adjusted resulting in quantified, rock specific formulas for bench width and rock fall berm placement. The result is an inter-ramp slope angle increase of 2 degrees on a 300m high slope, without the necessary purchases and procedural changes that would be required for pre-split drilling and blasting. The result has shown significant net benefits through reduction in mined waste tons and an increase in gold reserves. Location The Goldstrike open pit is located on the Carlin Trend gold belt in northeastern Nevada USA (Figure 1). The mine has produced over 43 million ounces (1.2M kg) of gold during the past 30 years. Engineering Geology Stratigraphy Figure 2 is a stratigraphic section of the rocks in the Goldstrike open pit. Quaternary alluvium and Miocene materials typically are poorly indurated stiff soils and are not present in all locations. Bedrock units consist of siltstones, mudstones, sandstones and cherts. From top down the major units exposed in the open pit are the Vinini Formation, the Rodeo Creek Unit, and the Popovich Formation. In general, rock mass strength increases with depth.

Jan 1, 2019