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By K. Freytag

The extraction of lignite in open-cast mines has a severe impact on the landscape. Proper landscaping after the shut-down of the mines has always been the statutory responsibility of the mine operator. The large area of the land used for open-cast lignite mining requires special regional planning procedures well in advance of the permitting procedure stipulated in the mining law. The lignite plan determines, among other things, the objectives of land reclamation. These objectives will then be outlined in more detail in the mine operation plans and implemented accordingly. Apart from the actual mining laws and regulations, a large number of environmental laws also determine the process of land reclamation. The success achieved in the field of land reclamation in all mining regions during the recent decades has shown that the lignite mining industry creates new landscapes that do not leave any scars in the countryside and merge very well with it.

Jan 1, 2005

By Detlef Ehlert

With the proven “Plug & Work” concept developed by SMS Siemag, automation systems are tested and optimized in the test field in a near-reality environment before being shipped and commissioned at a customer’s site. The process and production simulations provide scenes showing the specific mechanical equipment, the drive systems and the technology of the corresponding customer plant. Beside the technological simulation of the plant and the IO-simulation with the automation system, the production simulation is one of the three important parts of the Plug & Work simulation environment. It serves two important additional purposes: the 3D visualization of the entire customer plant on the one hand and the mapping of the logistic procedures in the plant on the other. In order to provide a close-to-reality visualization of the plant, the original design data of the individual customer plant are used for creating the visualization and prepared using an appropriate export filter. In this way, it is ensured that production sequences can be optimized in advance together with the customer, so that each customer can be trained on his own future plant.

Aug 16, 2017

By P. Cienfuegos, J. Loredo, J. J. Fernández, F. Pendás

This coal basin is a fore-deep basin with a lot of similarities with the Appalachian basin in the U.S.A., where throughout the 1990s, the research in coalbed methane grew rapidly due to a combination of factors, including the high prices for gas and electricity. In the Asturian Central Coal Basin 129 coal beds with thickness ranging from 0.8 to 1.5 m have been recognised in the productive carboniferous in an area bigger than 1500 km2. The maturation grade of these coals varies from the external zones of the basin where the volatile content ranges from 35%-40% to 20%-30%, to the internal zones of the basin where the volatile content ranges from 20% to 10%. In this context a sustainable exploration for fossil fuel is currently being undertaken in the most favourable areas of the basin in order to evaluate the real possibilities for coalbed methane (CBM) resources.

Jan 1, 2005

Experiments on High Efficiency Separation of Mixed Plastic Wastes by Vortex-Tube Separator

Sep 13, 2010

By S. N. Opperman

Testwork at Goedehoop Colliery showed that fine coal, essentially?150 microns can be successfully beneficiated using froth flotation. Both conventional and column flotation were tested. It was found that the traditional stirred tank type of flotation machines used in conventional flotation produced the best recovery of fine coal. After extensive testwork it was decided to develop a flotation machine on Goedehoop Colliery that would combine stirred tank and quiescent column technology. It was thought that this design would give the best combination of recovery and selectivity. The Multicell was developed and is producing results acceptable for Witbank coal flotation. Keywords: Multicell, Witbank coal flotation, froth, stirred tank, quiescent column.

Jan 1, 2002

By William J. Krisko

This contract final report summarizes the design, fabrication and testing of canopy air curtain devices under Bureau of Mines Contract H0232067. The canopy air curtain device is designed to reduce the level of respirable dust exposure to a continuous mining machine operator while having a minimum effect on operator safety, mobility and comfort and being compatible with mining equipment. This contract was devoted to the development of a device which utilizes an invisible curtain of air to envelope a mining machine operator's breathing zone with filtered air to provide respiratory protection. Various concepts were evaluated by means of laboratory tests. One concept was selected and was tested on various mining machines at underground sites by means of MSA personal samplers. The canopy air curtain was found to be effective. The percent reductions over the ambient dust concentrations were about 30 to 75 percent depending on the amount of time the operator spent under the air curtain. At one test site, the device enabled the mining machine to operate within compliance. Donaldson Company is presently working on the commercial production of the device.

Jan 1, 1975

By C J. Kruger, E le Roux

Anglo American Platinum has adopted a strategy of Best Practice Principles (BPP) for sampling, mass measurement, analysis and metal accounting for more than a decade now. When new plants are designed, the most suitable sampling equipment and sampling protocols are implemented and material flows and plant layouts are designed around sampling strategies. A few years ago, a crushing plant for a high-grade matte stream was commissioned.The design called for the high-grade material to be crushed to 95 per cent passing 2 mm and the design allowed for a single cutter primary Vezin sampler, increments taken from a gravity flowing stream at regular intervals, whilst filling a tanker for the pneumatic offload at our base metal refinery. This was a single point of sampling and analysis that would measure the wanted output from our smelting complex and the input to our refineries. In addition, the design incorporated the functionality to collect increments in an ‘interleaved’ fashion from the Vezin sampler for internal precision checks.The metal accounting strategy for Anglo Platinum is the ongoing measurement of all inputs, outputs and stock levels for all our operations for platinum group metal (PGM) and base metal (BM) content. Included are yearly stocktakes, usually done on 1 February every year, across the smelters and refineries (at least the base metal refinery). A trend was developing in the accounting period immediately following the introduction of the new crushing and sampling facility, whereby the absolute difference between the physical stock and theoretical stock (PGMs predominantly) increased for the two respective sites on an ongoing basis. The smelter (sender) showed an increase in physical stock compared to the theoretical stock and the base metal refinery (receiver) showed that their theoretical stock increased against their physical stock. Because of this anomaly, an additional stocktake was held in September for the period in question and it was confirmed through the physical stock measurement results, that the PGM accounting problem was indeed pointing towards the evaluation of the high-grade matte stream.This paper showcases parts of the process that took place to explain the poor accountabilities for the respective sites. Previous results from the sampler ratification process (of the interleaved sampling design) were analysed again, a physical inspection was carried out on the sampling system again and the sampler performance was monitored (quality control parameters) for the period.From these investigations, it was found that airflows present inside the Vezin introduced the sampling bias and a change in sampling protocol was introduced as well as physical changes to the sampling equipment were made to eliminate the airflow and thus the bias conditions significantly. The accounting period which followed, after a phased upgrading process, showed that the accounting between our smelter and base metal refinery had been restored to within statistical limits (difference between physical and theoretical stock below five per cent relative to theoretical stock).CITATION:Kruger, C J and le Roux, E, 2017. Pitfalls in Vezin sampling for finely crushed materials, in Proceedings Eighth World Conference on Sampling and Blending , pp 151–158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By J. A. Finch, Zhenghe Xu, Z. A. Zhou

A particle-bubble collision model was used to investigate the minimum recovery zone height, H(r,min) required for flotation columns. The criterion used to define H(r,min) is that height which gives unit collision probability. It is shown that H(r,min) is determined by particle and bubble size, gas hold-up and bubble-bubble interaction. Under typical operating conditions, for flotation of particles less that 10 micrometres in size H(r,min) is greater than 10 m, but it reduces to less than 1 m for particles greater than 100 micrometres

Aug 1, 1995

AUSTRALIA CHAPMAN Gary JOHN WAGSTAFF CONTSRUCTIONS PTY. LTD. 1 Ashgrove Crescent 4060 ASHGROVE BRISBANE HILLAR Jaaes Director J.A. HILLAR & ASSOCIATES 99 Woolwich Road WOOLWICH, NSW 2110 WAGSTAFF John Managing Director JOHN WAGSTAFF CONSTRUCTIONS PTY. LTD. 1 Ashgrove Crescent 4060 ASHGROVE, BRISBANE AUSTRIA FUCHSBERGER M. TECHNISCHE UNIVERSITAT INSTITUT FUR BODENMECHANIK Rechbauerstrasse 12 8010 GRAZ

Jan 1, 1994

By Steve Massman, Edward Wipf, Gary Beerkircher

"As mine size and tonnage continues to increase, material handling/processing equipment has also increased in size with 400 MT haul trucks, 2000 KW crushers, 12 M SAG/AG mills, 8.5 M ball mills, 3000 M3 flotation cells and 12.5 MW HPGR’s all with planned designs to increase in size further. Related equipment including vibrating screens have also increased in size with screens seeing feed rates of 3000 MTPH. Open circuit SAG Pre-Crush and closed circuit HPGR flowsheets are becoming more common with large screening requirements. Large multi-slope (banana) or horizontal screens are commonly used for these applications, however as the size of these screens has increased, the number and size of the brute force/overhead exciters has increased but with limitations. An example is a SAG discharge screen that will see surges of material from the SAG mill which overload the screen, reducing the screen stroke or throw causing a large reduction in screen efficiency with excessive fines & moisture in the screen oversize feed to the pebble crushing circuit. This paper will present some actual examples of the use of Two-Mass screens as a solution to these overloading problems and the advantages of Two-Mass screens in other high tonnage applications.Brute Force Drive Compared to Two Mass Drive Vibrating ScreensThe standard single mass screen as depicted by figure 1 is generally recognized in the mining industry. It is characterized by the screen body – labeled as the single mass (Mt) that is supported by isolation springs (Kiso). The stroke needed to process material is obtained by incorporating large eccentric wheels and/or drive boxes (Fb) directly mounted to the screen body via a drive tube."

Jan 1, 2017

By David Bendersky

The principal objectives of this study are to: (1) survey electrical practices in metal and non-metal mines, (2) survey electrical practices in metal and non-metal mills, (3) clarify the federal regulations governing electrical practices in metal and non-metal mines/mills, (4) analyze electrical accidents, and (5) make recommendations aimed at improvement of the safety of electrical practices in metal and non-metal mines. Information was obtained from literature searches, accident reports, visits to 27 mines and 12 mills, and discussions with knowledgeable industry and government people. The various electrical power systems and practices at the mines and mills visited are described. Similarities and differences based on the type of mining and the minerals being mined or milled are presented. The federal regulations governing metal/non-metal mine/mill electrical practices (Code of Federal Regulations, Title 30, Sections 55.12, 56.12, and 57.12) are presented and discussed. Explanations of each regulation are provided in an appendix. The attitudes of mine/mill operators towards the federal regulations are described. An analysis of the electrical accidents in metal/non-metal mines and mills during the period 1972-1978 is presented. Recommendations, including specific research and development activities, aimed at improvement of electrical safety in metal/non-metal mines are submitted.

Jan 1, 1980

By LUIS ALBERTO TORRES-CRUZ

The assessment of liquefaction vulnerability is crucial to understanding the potential consequences of a tailings dam failure. The “Plewes method” is a relatively well-known and simple screening method to assess liquefaction potential based on results of cone penetration testing (CPT) which may be complemented with laboratory testing. The objective of the current work is to emphasise the screening nature of the method and its uncertainties when applied in tailings deposits. Specifically, the paper highlights the difficulties in assessing the intrinsic uncertainty of the method and the additional uncertainty that results from variations of the slope of the critical state line (λ10) along the depth of the CPT sounding. The results of the method are too uncertain for detailed characterisation of tailings even when a relatively low intrinsic uncertainty is assumed. However, the method characterises weaker soils with lower uncertainty (although still too high for detailed characterisation) than stronger soils. The uncertainty of the method is negatively affected by the relatively low λ10 values that are typical of nonplastic tailings. It is suggested that the results of the method should be presented in scatter plots in which the spread of the data is consistent with the uncertainty of the method.

Jan 28, 2021

By O. F. Ochonogor

Laser metal deposition (LMD) is an additive manufacturing technique whereby a stream of metal powder is consolidated by a focused laser beam on the surface of a substrate or engineering component. The interaction zone between the laser beam and powder particles is scanned superficially, generating tracks of deposited material. The tracks are overlapped in a deposition strategy in accordance with slices of a CAD model. Successive layers of material are built up to fabricate a near net shape part. In this work, the technique is used to fabricate metal matrix composites (MMCs) by using an elementally blended feedstock combining metal and ceramic powders in the melt pool, which melt and solidify to create the required morphology. Ti6Al4V + TiC MMCs were produced with 10, 20, and 30 vol.% reinforcing ceramic, and Zr + TiC MMCs were fabricated with 10, 20, and 30 vol.% TiC. The deposited thin walls were analysed using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and indentation testing. In both systems, the analysis revealed the presence of partially melted TiC particles embedded in the metal matrix along with fine dendrites of re-solidified ceramic. The dendritic structures in the Ti-based composites were confirmed as TiC, whereas in the Zr-based composite the Zr metal reacts with theTiC to form ZrC, leaving Ti in solid solution. Both the MMCs show an increase in microhardness with increasing ceramic (carbide)content, reaching a peak HV0.1 value of 500 in the Zr- based MMC and HV0.1 of 550 in the Ti based MMC.

Jan 1, 2012

By J. E. Chilton

A technique for use in underground coal mines measures the response times of machine-mounted methane monitors. This technique uses a calibration cup to deliver gas to the sensor head to measure response times. For comparison, in the current study, response times were measured by placing methane sensor heads in a specially designed test box where they were exposed to an atmosphere containing a constant concentration of methane. Response time readings measured in the test box were shorter than the readings obtained using the calibration cup. The response times measured in the test box were comparable for sensors from three different manufacturers. The effects of dust cap and flame arrestor design on response times were also evaluated using the test box.

By Martin B. Hudson, Daniel Brescia, Zhangwei Ning

Due to the complexity and sensitivity of surrounding environments, instrumentation and monitoring (I&M) is critical for many urban deep excavations. The objects to be monitored include shoring bulkheads, retained embankments, adjacent buildings and roads as well as underground utilities. However, there are also plenty of constraints on the implementation of I&M such as: congested site space, difficult access to instruments, coordination among multiple contractors, and installation permits for private or public properties. Because of these constraints, sometimes the implementation of the initially planned I&M is delayed, its scope is reduced, and/or the continuity of monitoring is interrupted. For these reasons, it is important to implement the I&M with robust and redundant capabilities while providing minimal interference to the project construction and schedule. This paper describes state-of-the-art I&M technologies including automatic motorized total station (AMTS) with camera and automatic leveling device, reflectorless AMTS and IoT- based wireless sensors based on a case study of an on-going deep excavation project. INTRODUCTION In urban environments, deep excavations requiring the construction of temporary shoring bulkheads are becoming increasingly common, with the associated need to provide protection of the surrounding built environment during construction. Protection of the surrounding environment requires planning, engineering, construction, monitoring, and excessive shoring movement mitigation. The I&M is a vital component of the deep shoring implementation. In public projects, geotechnical I&M is often placed within the general contractor’s scope, whereas the majority of deep excavations are privately undertaken. For those private developments, sometimes the developer contracts the geotechnical I&M directly with the project geotechnical engineer or by a geotechnical I&M specialist hired by the project geotechnical engineer. In either the public project or private development case, the effective deployment of the I&M system relies heavily on coordination and collaboration with the project contractor.

Jan 1, 2018

By M. Kalin

"SUMMARYWaste management in general, and the water treatment of mine and mill effluents, has become an ever increasing burden for mining operations. A reduction in these expenditures would undoubtedly be desirable if this could in fact be achieved within effluent guidelines and monitoring requirements.A brief summary is presented of the research which has as its aim the development of methods which would reduce such costs and lead to solutions for environmentally acceptable close-out conditions for acid generating mine waters. The basic concepts of Ecological Engineering and Biological Polishing are presented, together with an indication of the present state of these research efforts. Details are provided of the progress of various experiments which aim to promote reducing conditions, organic matter production and the establishment of biological filters which remove metals from the water which are then retained within the waste management areas. These conditions should lead to a curtailment of acid drainage and an improvement in effluent quality.A description is provided of the first pilot demonstration using this approach to achieve a walk-away condition for the close-out of a massive sulphide tailings resulting from 10 years of operating a copper/zinc concentrator in Northern Ontario.1.0 INTRODUCTION1.1 Waste management and close-outIt is recognized that the achievement of a cost-effective and competitive mining operation, from the commencement of exploration for ore bodies through to the day-to-day efficient operation of the mine, requires a certain expertise and sophistication. However, the environmental effects of these activities are considered peripheral issues and their importance as an integral part of the planning and development of the mine/mill, is not always appreciated."

Jan 1, 1988

Using mines in Canada, Boart Longyear, a leading provider of drilling services and products, has put its Stage 3 Coring Bit to the test and each time the bit has passed the test with great success. After more than a year in the field at a major mine operation in Sudbury, Canada, the Stage3 coring bit broke life records to become recognized as the most productive design in the industry. In addition to the proven advantage seen in regular bit life increases of as much as 300 percent in some cases, the design is quickly being recognized for its cost-saving operational impact. In Sudbury, the mine operation realized actual cash savings of more than C$45,000 within an eight-month period by making the switch to Stage3 bits. For years, the Sudbury Basin team has relied on the Alpha Extended Crown bit with the Express Waterway geometry option, ordering approximately 500 units per year. This 07 COM ECEX configuration performed well in medium-hard, non-abrasive to ultra-hard, non-abrasive formations with an average bit life of 150 m (490 ft). While satisfied with the performance of the Alpha Ex-tended Crown, the team agreed to put the new Alpha Stage3 to the test. Boart Longyear?s field engineers supplied five drill sites with Alpha Stage3 bits in a 07 COM configuration. After thoroughly testing the Stage3, the results were clear. Even with the well-known performance and versatility offered by the previously preferred configuration, the Stage3 set a new standard of bit performance. The new bit maintained its cutting edge for up to three times longer than the Alpha Extended Crown, a significant performance increase when compared to the 07 COM ECEX.

Jan 1, 2009

Twenty field-scale tests were conducted in a 28 MW pulverized coal power plant in Healy, Alaska, to examine mill power consumption in relation to coal grind size. The intent in this field-scale study was to verify if grind size truly impacted power consumption by a detectable amount. The regression model developed from the data indicates that grind size does impact mill power consumption, with finer grinds consuming significantly more power than coarser grinds. However, other factors such as coal hardness (i.e., the lower the Hardgrove Grindability Index, or the harder the coal, the higher the power consumption) and mill throughput (i.e., the higher the throughput, the higher the power consumption) had to be included before the impact of grind size could be isolated. It was also observed that combining amperage and flow rate into a single parameter, i.e., specific amperage, hurt modeling. Cost analysis based on the regression model indicate a power savings of $19,972 per year if the coal were ground to 50% passing 76 mm rather than the industry standard of 70% passing 76 mm. The study also demonstrated that size reduction constituted a significant portion of the power consumption.

Jan 1, 2008

By D. E. Andrews

The objective of this study was to investigate the environmental effects of slaking of surface mine spoils. To accomplish this, both field and laboratory programs were undertaken, supplemented by a thorough literature search. The field program consisted of drilling the highwall as well as test pitting in recent, two-, five, and ten- year-old spoil piles at four active mining sites in the eastern bituminous coal fields. Pertinent observations were made and samples collected for laboratory analyses which consisted of several standard geotechnical, agronomic, and geochemical tests. Durability tests utilized included jar slake, cyclic wet-dry, rate of slake, and slake durability tests. Correlation between field and laboratory portions was made- and results presented. The report is concluded with a discussion of the slaking process and associated environmental impacts, proposal of a preliminary classification system for use in premine planning, and presentation of management techniques to optimize the slaking process.

Jan 1, 1980

By M. Grodner

Underground excavations exhibit different hangingwall conditions in response to varying geotechnical and mining situations. These differences need to be quantified so as to accurately determine the effectiveness of the mining and/or support strategies. A useful tool for the quantification of these differences is hangingwall profiling. Two methods of hangingwall profile measurement are described?termed irregular and periodic methods. Several data analysis techniques are reviewed for these methods and the suitable ones are discussed in detail. For irregular data the suitable techniques are the determination of the length, the average of the profile and the average absolute deviation from the mean of the profile. All of these techniques as well as determination of the moving average of the height and examination of the spectral image of the profile can be successfully applied to regular data. The effect of preconditioning on the hangingwall is discussed as an example and it is quantitatively shown that it results in improvements of conditions. The techniques described allow the engineer to quantitatively identify the appropriate support type or mining strategy and thus represent a valuable decision-making tool. It is suggested that these techniques should be employed on a routine basis by the rock engineers on the mines as part of their geotechnical classification, as well as support manufacturers to quantify the effectiveness of various support types.

Jan 1, 2000