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By D. Legg

This is the first in a series of studies commissioned by the European Environment Agency that aim to raise awareness of the use of economic instruments and assess their effectiveness. The emphasis is on sharing good practice and increasing knowledge and understanding across European countries in this emerging policy area. A methodology for evaluating the effectiveness of economic instruments has been developed and this will examine whether the inclusion of economic instruments in complex policy packages can improve the overall performance, particularly as a prevention tool in terms of resource use and waste generation The focus for this initial study is the use of aggregate taxes in four EU countries which include the Czech Republic, Italy, Sweden and the UK so that a range of experiences (e.g. geographical, political etc.) can be included. The findings will be used to inform and influence future policy development in other EEA countries. The methodological approach is divided into two main sections: - Technical analysis, which covers quantitative and qualitative analysis. - Process design, i.e. who should be involved when, where and how. Process design is essential if the full learning benefits are to be gained from the technical analysis, which is the ultimate objective of these evaluations.

Jan 1, 2007

By C. A. Fleming, C. J. Ferron, E. S. Makande, P. Mason

Several small mines are producing refractory gold concentrates in Zimbabwe and, owing to the small scale of most of these operations, their output is processed in a central custom roaster in Kwekwe. Owing to the wide variations in the feed to the roaster, the efficiency of the old Edwards roaster is deemed unsatisfactory with gold recovery from concentrate as low as 70%, and alternative processes were evaluated to improve this situation. Various processes for oxidizing refractory arsenopyrite/pyrite concentrates to liberate gold prior to cyanidation are known. In practice, only two have to date met with wide industrial acceptance, pressure oxidation and roasting. Owing to the ·high arsenic and antimony levels of some concentrates in Zimbabwe, the only viable roasting alternative would be two-stage air-roasting of concentrates in two reactors, as practiced at Giant Yellowknife, Campbell Red Lake and New Consort. This process, however, creates an arsenic disposal problem, and produces gas of fairly low SO2 content, requiring a large gas handling system for acid production. On the other hand, there are currently four commercial pressure oxidation plants treating refractory gold ores (McLaughlin, Mercur, Getchell and Goldstrike) and three treating concentrates (Sao Bento, Porgera, Campbell). One other concentrate oxidation plant is being constructed (Con), and several more are being considered.

Jan 1, 1992

By P. V. Avotins, D. R. Nagaraj, S. S. Wang

Xanthates and dithiophosphates are the most commonly used collectors in the flotation of sulfide minerals. Other reagents such as thionocarbamates, mercaptobenzothiazoles (MBT), mercaptans and xanthogen formates occupy niche positions in industrial collector use. Over the last ten years there has been much activity by chemical companies to develop new collector compositions. The new collectors are aimed at meeting specific process needs such as recovering an increment of valuable metals, improved sulfide separations, increased flotation kinetics, and reducing reagents costs. A review of the patent literature shows that American Cyanamid (Cytec), Dow Chemical, Phillips Petroleum, Sentrachem Ltd., Henkel, Montan Chemicals and Elf Aquitaine, among others, have been active in sulfide collector research. Several companies have achieved considerable success in laboratory and plant tests of the new collectors; however, commercial acceptance for plant usage has been slow. Those most advanced have been plant tested extensively and some are in day-to-day use. The new collector types in this category are: Modified thionocarbamates, dithiophosphinates, organic sulfides, trithiocarbonates, monothiophosphates, and modified thioureas. Others such as substituted mercaptobenzothiazoles and monothiophosphinates have been tested in the laboratory. The chemistry of collectors developed in the last 10 years, their preparation, physical properties and their potential for commercial use are reviewed in this paper.

Jan 1, 1994

Controlled-blasting experiments in small development drifts were conducted at CANMET's Experimental Mine in 1992 and 1993. The objective of these experiments was to develop suitable controlled-blasting techniques for small development headings that are drilled by jackleg with 32-mm-diam holes. The experimentation was also aimed at providing insight into blast-damage mechanisms. Particular attention was given to the physical-mechanical properties of the rock and the rock-mass structural data. The drift faces were approximately 2.4 by 2.4 m (7.9 x 7.9 ft) in size with 36 to 43 holes drilled to a depth of 2.4 m (7.9 ft). Cartridged water gels, emulsions and semigelatin dynamite were used in the cuts and as primers, ANFO was used as the main explosive and decoupled 19-mm (0.75 in.) diam semigelatin dynamite charges were used in the perimeter holes. Smooth-blasting techniques and presplitting were tested in the underground mine. All of the blasts were monitored with a multichannel blast-vibration monitor, to which was attached sets of high frequency geophones and accelerometers. These experiments demonstrated the efficiency of controlled-blasting techniques for the reduction of blast damage and also demonstrated the need to improve the safety and efficiency of using explosives.

Jan 1, 1997

By T. X. Ren, J. S. Edwards

Although much work has been carried out in order to understand the mechanism of spontaneous combustion and hence minimise its potential risk, the spontaneous combustion of coal continues to be a problem in coal mining. The Department of Mineral Resources Engineering of Nottingham University has been active in conducting fundamental research into the problem of spontaneous combustion of coal. For years standardised adiabatic oxidation tests have been used to identify coals and other carbonaceous materials liable to spontaneous combustion. Recently the apparatus has been computerised and coupled with an expert system known as ESSH to evaluate the potential of self-heating of coal on the basis of intrinsic coal properties, geological settings and mining techniques. A numerical model has been developed to study the aerodynamics of airflow in the wastes of longwall coal faces. The Computational Fluid Dynamics approach is being explored to simulate airflow behaviour and nitrogen inertisation processes within the goaf. Such a model would be used in locating the areas most liable to spontaneous combustion and improving the utilisation of nitrogen. It would also be possible to determine the most likely path ways of combustion/heating products so as to provide an indication of the most appropriate locations for fire detectors.

Jan 1, 1997

By T. N. Moore, E. M. De Souza

Vibratory hand-tools can produce Hand Arm Vibration (HAV) Syndrome in their operators. This disease, often called Vibration White Finger, can cause varying levels of hand-arm discomfort and, in severe cases, impairment. In addition to the human suffering, there are also significant economic repercussions for industry. These include reduced operator efficiency, lost time through increased absenteeism and increasing compensation awards. In the mining industry, jackleg rock drills are a particularly troublesome source of hand vibration exposure. As a result, a significant amount of work has focused on redesigning rock drill handles to minimize hand-transmitted vibration. This paper details the results of a study undertaken to determine the effectiveness of using elastomer covered ("cushioned") handles in place of the standard steel design. The results indicate that, for a particular cushioned design, the overall acceleration level experienced at the hand-handle interface can be reduced by as much as a factor of three, relative to the steel handle. It is also shown that this reduction takes place predominantly in the frequency range above 500 Hz, with performance improving with increasing frequency. Qualitative evaluation of the cushioned handles by the drill operator indicates a significant increase in comfort over the standard steel handle.

Jan 1, 1992

By A. Peppas

Perlite is a naturally occurring siliceous rock, which can be expanded from four to twenty times its original volume when heated at a temperature close to its softening point. The expanded perlite is characterized by increased sound and thermal insulating properties. However, the conventionally expanded perlite products have high porosity and low mechanical properties that limit the range of their applications in the construction and chemical industry. The present work aims at the development of new closed porous microcellular material from perlite with enhanced mechanical and physical properties to be applied in new applications, like joint compounds, functional fillers for special paint types, special blasters and mortars, artificial marble. For the production of these new materials a vertical electrically heated furnace with six different heating zones and controlled gradient temperature profile was used. The effect of major process parameters, like temperature and air flow, on the quality of the produced materials was studied using Greek perlite from Milos Island. The quality of the new products was evaluated in terms of their bulk density, compression strength, water and oil absorption, surface area and pore volume. The experimental results show that the produced materials are characterised by improved mechanical and physical properties compared to the conventionally expanded perlite products.

Jan 1, 2006

By Y. C. Kim

For the past few years, the Cyprus Bagdad Copper Company began experiencing a significant "ore-dilution" problem from its low grade open- pit copper mine located at Bagdad, Arizona. To pinpoint the causes of this dilution, a study was initiated to investigate as well as to improve in-pit ore-waste selection-procedures using conditionally simulated ore-bodies. Prior to the actual use of conditional simulation; a comparison of different estimation methods for a mined-out area in the pit was performed. Specifically, kriging estimates were compared against the original estimates of the company which were based on the polygonal approach. The results of this comparison clearly identified part of the so- called "ore-dilution" problem, which was the initial over-estimation of average ore grades from blast rounds, using the polygonal approach. The results from the use of conditionally simulated orebodies demonstrated that the "ore-dilution" problem can be reduced by more than half if in-pit ore- waste selection is based on the kriged estimates rather than the polygonal estimates. This simulation study also showed that the current use of the polygonal approach has the effect of shipping a larger tonnage of lower grade material to the mill.

Jan 1, 1982

To maintain its brand position in the competitive market of mining equipment, the Volvo Construction Equipment (Volvo CE) engineers were challenged to develop top-performing wheel loaders and articulated haulers even faster than before. To start, this meant reducing prototype test cycles by two-thirds. The final goal? Chopping in half the virtual prototyping time in early design phases. Creating a unified co-simulation solution In this ground-breaking project, the Volvo Construction Equipment design team in Eskilstuna, Sweden, replaced its piecemeal department-by-department process with a single solution based on LMS Imagine.Lab AMESim. With one unified model, they could simulate the behavior of four major vehicle subsystems in wheel loaders and articulated haulers: hydraulics, powertrain, thermal management and the actual driver. Subsystem models exchanged data seamlessly.

Jan 1, 2011

By J. E. Powell

Introduction The disposal of mine tailings, development rock, and other unwanted refuse material underground in mines by using pneumatic conveying techniques has been undertaken in the coal industry for many years. Similar equipment has been utilized for backfilling hard rock mines and is currently being applied in a gold mine in South Africa where development rock is being stowed in the mined-out stopes to help reduce the incidence of rock outbursts. On a limited scale, pneumatic conveying has been applied for backfilling uranium mines and one particular mine in New Mexico, U.S.A., has used this technique for 8 years. Other uranium mines in this area are now considerinq the dry backfill technique to eliminate the problems associated with hydraulic fill. The need to backfill in uranium mines is primarily of importance to improve ventilation, stabilize the pillars and roof, and possibly to extract a larger percentage of the uranium ore. If this can be achieved by utilizing the tailings from the beneficiation plant and using rock from the development headings which in itself may be slightly radioactive, then a greater benefit can be derived. Backfill can be achieved with hydraulic fill methods by running slurry into the stopes and allowing the water to decant and return through the footwall development entries to sumps for pumping to the surface. However there are several disadvantages associated with this method in that water is percolating throough the mine workings; it is necessary to build bulk heads in flat lying deposits; it is difficult to fill right to the back; and the decanted water takes with it quantities of the finer sand particles which results in maintenance problems with the mine pumps. Pneumatic conveying can overcome these problems in that the voids can be completely filled with high degree of compaction, heavy bulk heads are not necessary, the development rock can be added to the pneumatic system for disposal underground so eliminating hoisting cost to the surface, and cement can be added to the wetted material. To

Jan 1, 1980

By Lawrence A. Browning

In recent years, there has been a growing realization of the importance of ground water as a national resource and increasing concern that this resource be properly managed and protected from a variety of pervasive practices that endanger it. Aquifers have been adversely affected in every region of the country. In dealing w.ith the underground water program, EPA will have the following objectives: to protect human health, and to protect and conserve an important national resource. In pursuing these objectives, EPA will take economic consequences and other national objectives (e.g., energy) into account. EPA intends to pursue these objectives in full partnership with the States. Generally the States should retain the lead in protecting ground water.

Jan 1, 1978

By Werner Burger, Marcus Lübbers

TBM development in recent decades has been dominated by increased face pressures, larger diameters and multi-mode functionality paving the way to realize projects deemed impossible before. In addition, the trend towards digitalization does not stop at the tunnel portal. A shortage of skilled personnel and the ever-present wish to increase workplace safety, quality and system performance automation, operatorassist or even autonomous systems have become key development targets. The paper will present the current state of the art in light of these special conditions.

Jun 13, 2023

By Emily Wortman-Wunder

While the mood at the 2013 annual joint meeting between the Pittsburgh Coal Mining Institute of America (127th Annual Meeting) and SME Pittsburgh Section (68th Annual Off-the-Record Meeting) in Canonsburg, PA was subdued following a rocky year in the coal industry, attendance was down only slightly, to 300, and overall, the meeting?s focus was optimistic about the future of coal. The conference began by addressing one of the central challenges of coal mining head-on with a keynote address on the status of safety in the mining industry. Noting that two more U.S. miners had died in 2013 than by the same date in 2012, the National Mining Association?s (NMA) Senior Vice President of Regulatory Affairs Bruce Watzman made a plea for a new approach to safety. He described the NMA CORESafety initiative, a program that promotes proactive safety measures versus a compliance-driven model. CORESafety, described in more detail on pp. 29 of this issue, focuses on developing successful ways to change company cultures of safety and behavior. Other industries that have adopted this approach have seen dramatic drops in fatalities, including the Australian mining industry, which has seen its annual fatality rate drop to nearly zero even while the number of people employed in the industry has soared. The rest of the morning?s sessions explored what is arguably the industry?s biggest challenge right now ? maintaining the social license to operate.

Jan 1, 2014

By E. A. Metz

Ergonomics is the art and science that tries to understand the complex interrelationships among employees, their work environment, equipment, work methods and job demands. Coal and metal/nonmetal miners are exposed to a higher number of ergonomic risk factors than in non-mining occupations. In addition, studies have shown that these miners experience more degenerative disc disease and osteoarthritis than comparable industrial populations. A general discussion of the risk factors that cause overexertion injuries and disorders will be presented. In addition, the basic principles of ergonomics will be discussed with specific cases to show how successful programs have been developed. A successful ergonomics program should simultaneously improve health and enhance productivity.

Jan 1, 2002

By Manoj Khandelwal, Bright Akuinor Tsidi, Newton Amegbey, Daniel Mireku-Gyimah

This study emphasizes the importance of understanding the factors that influence the throwing of flyrock in mining operations, a significant hazard to both workers and nearby structures. Moreover, it highlights how blasting engineers, when estimating flyrock occurrences and their travel distance, typically rely on input parameters such as powder factor (PF), hole length (HL), subdrill (SD), spacing (S), hole diameter (D), burden (B) and stemming length (ST), while overlooking crucial factors like velocity of detonation (VOD) and charge per bank cubic meter (CPBCM). Through analysis using support vector machine (SVM) modeling in MATLAB, the study underscores the impact of including or excluding VOD and CPBCM on flyrock throw distance.

Jul 1, 2024

By M. S. Kabibwa, E. K. C. Chanda

In planning for the future, Nkana Division deepened the Mindola sub-vertical shaft which was commissioned in 1994 in order to access the 30 Mt of ore between 1274 and 1570 m levels. The Nkana Synclinorium which is estimated to contain 250 Mt of ore is being accessed from the vicinity of Central Shaft. These areas are being planned with the intention of maximizing the use of computers in geological modelling and mine design so as to overcome the inadequacies of manual planning techniques. As a result, there is an increased demand for quality output from the computerized mine planning system the division has been developing over the last few years. A new workstation comprising the Hewlett Packard HP 71 51100 MHz and a CRX graphics monitor was acquired in 1995 together with the LYNX (version 3.09 and version 4.0) Mine Modelling System. Currently the workstation is being used for geological modelling and mine design for the Zerofold at Central Shaft and the Mindola mining at depth project. AutoCAD and Mine Works Planner have been added to the sys- tem configuration. Mine Works Planner is likely to replace Lo- tus123 for mine scheduling tasks. Computer applications in the area of mine planning at Nkana has led to considerable time savings and improved efficiency in areas formerly performed manually and has allowed speedy processing of data that would otherwise have proved too time consuming. Nevertheless, a lot of work still needs to be done in the areas of geostatistics, stope design and financial modelling of mining options. For the foreseeable future computer based planning will operate parallel to manual methods until such a time as sufficient personnel are proficient in the use of computer systems. This paper describes the program of computerization at Nkana Division, reviews current applications and the benefits and experience gained and discusses the promise of current and future developments.

Jan 1, 1996

By Verya Nasri

The proposed Second Avenue Subway Project in New York City is approximately 8.5 miles long, up to a depth of 120 feet beneath grade and runs the length of the eastern side of the island of Manhattan from Harlem in the north to the financial district in the south. It will reduce overcrowding and delays on the existing parallel line, improving travel for both city and suburban commuters, and upgrading access to mass transit for residents of the East Side of Manhattan. This subway line will have 16 new stations providing transfers to the existing Metro-North commuter rail service and to New York City Transit subway lines and bus services. The first phase of construction includes two TBM rock tunnels 2.4 miles long and two new large and shallow rock cavern stations with clear span openings ranging from 70 to 100 feet and length in excess of 1000 feet with 615 feet center platform, coupled with low rock cover ranging from 20 feet to 40 feet. The design methodology for these large and shallow rock caverns consists of using well known empirical methods for initial estimate of support requirements and then two and three dimensional continuum and discontinuum analyses for verification of the selected excavation sequence and support system. This paper describes the analysis and design methodologies used for the two large and shallow rock caverns with insight into how to overcome the design complexities and construction challenges of the urban underground.

Jan 1, 2008

By James McManus

The Lornex mine is located on the Southern slope of the Highland Valley in South Central British Columbia. The large low grade deposit was discovered in 1964; stripping began in 1970, and the mill started commercial production in October of 1972. The orebody is classified as a complex porphyry type having as major constituent quartz diorite, with varying amounts of quartz, grano diorite, and porphyry. A substantial degree of alteration is evident in the host rock, and this became the key factor in major equipment selection for the grinding section. A pilot plant was constructed on the property capable of treating 100 TPD of ore. The ore was mined to be as representative as possible of the entire orebody by sinking a shaft and cross cutting the deposit underground.

Jan 1, 1975

By Ellen Amoako Afful, Michael Moats, Guang Xu, Ashish Kakoria

Electrowinning and solvent extraction are crucial steps in the production of high-purity copper. However, safety concerns have been raised regarding the acid mist generated from the electrowinning process. The mist generated results in health risks to workers and damage to machinery and infrastructure. Currently, chemicals and pellets are used to control acid mist. However, the effectiveness of these controls may vary depending on the type of organic solvent used in the solvent extraction process, which can influence the generation of acid mist. This study aims to evaluate the impacts of organic solvents and surfactants on acid mist suppression. In this study, an electrolyte is contacted with organic solvents to simulate the solvent extraction. The electrolyte is dosed with 20 mg/L of surfactant at each contact. Acid mist testing is performed on the electrolyte separated from the organic phase at the end of the solvent extraction step. The mist collected is analyzed to determine the level of acid mist generated. The results of this study indicate that organic solvents and surfactants showed significant acid mist suppression, but with somewhat different suppression efficiencies. After first contact, Licorice and the organic, for instance, showed a suppression efficiency of up to 69.7% but its efficiency gradually decreased as the number of contacts increased.

Feb 1, 2025

By Dale C. Matthews

Pressure oxidation of refractory gold ores is becoming more popular in our environmentally sensitive society. This paper will discuss some specific process problems and solutions involved with starting up and operating an autoclave circuit.

Jan 1, 1991