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By M. J. Hrebar

A study was conducted to evaluate the applicability of large wheel loaders (Caterpillar 994 Class) for use as primary loading equipment in open pit iron-ore operations. Field visits were made to taconite and gold mines that used large wheel loaders. Information was gathered on loader selection rationale; operation and maintenance experience; and production, availability and costs. Brief time studies were conducted to indicate machine performance and utilization. This paper summarizes the field data that was collected including an economic comparison of wheel loaders and cable shovels in an iron-ore application.

Jan 1, 1997

By D. R. Zeni

Today's mine development requires the safe, expedient and economical construction of vertical shafts for both ventilation and access. This construction must be accomplished within diverse ground conditions. Advancements in large-diameter shaft drilling have led to many exceptional mechanical refinements in shaft-drilling technology. The author traces the history of the equipment and methods employed by the large-diameter shaft-drilling industry and explores the likely paths of future development. Case histories that illustrate the adaptability of shaft drilling as a versatile tool for advanced, worldwide mining operations are cited. Safety, scheduling, costs, environmental impacts and capabilities are discussed.

Jan 1, 1996

By Bradford F. Townsend

A study was made on six collapses that occurred during large-diameter tunnelling through weak sedimentary rocks and soil using SES methods in three stages?top heading, bench and invert. The collapsed lengths are between 20 m and 277 m. The collapses were re-mined using essentially the same tunnel-ling method with larger excavation profiles to accommodate the designed remedial measures consisting of ground treatment, pre-support and stronger initial support/outer lining required to carry higher ground loads acting in the collapsed lengths. The paper presents information on the collapses and the design and execution of the remedial measures.

Jan 1, 2008

By R. Hildebrandt, K. Cybulski, G. V. Goodman, Z. Dyduch, M. L. Harris, M. J. Sapko

Past research showed that bituminous coal dust remains dry and dispersible in the presence of moisture. Rock dust must disperse with the coal dust to effectively inert a propagating coal dust explosion. Non-treated rock dust readily absorbs moisture, limiting its dispersibility, while anti-caking treated rock dusts can remain dry. The National Institute for Occupational Safety and Health contracted the Central Mining Institute in Poland to conduct large-scale testing in their Experimental Mine Barbara to determine if a treated rock dust can be as effective as non-treated rock dust in attenuating or quenching coal dust explosions under the same experimental conditions. INTRODUCTION One of the goals of the National Institute for Occupational Safety and Health (NIOSH) is to conduct research to reduce the risk of mine disasters and provide workplace solutions to reduce the risks associated with accumulations of combustible and explosible materials; the most common form of which is the generation of coal dust during the mining process and its subsequent distribution downwind. Dispersible rock dust is a primary defense for preventing coal dust explosion propagation in underground coal mines, and its properties are defined in 30 CFR 75.2. “Pulverized limestone, dolomite, gypsum, anhydrite, shale, adobe, or other inert material, preferably light colored, 100 percent of which will pass through a sieve having 20 meshes per linear inch and 70 percent or more of which will pass through a sieve having 200 meshes per linear inch; the particles of which when wetted and dried will not cohere to form a cake which will not be dispersed into separate particles by a light blast of air; and which does not contain more than 5 percent combustible matter or more than a total of 4 percent free and combined silica (SiO2), or, where the Secretary finds that such silica concentrations are not available, which does not contain more than 5 percent of free and combined silica.” An earlier NIOSH investigation of rock dust revealed two significant concerns with the supply of rock dust to U.S. coal mines: 1) insufficient particles <200 mesh (75 μm) and 2) all rock dusts when wetted and dried formed cakes and were not easily dispersed with a light blast of air (1). Past research by the U.S. Bureau of Mines and others showed that bituminous coal dust remains dry and dispersible in the presence of moisture (2). Rock dust must also be dispersible in concert with the coal dust to effectively inert a propagating coal dust explosion (3, 4, 5, 6). Non-treated rock dust, however, readily absorbs moisture, limiting its dispersibility, while a rock dust treated with long-chain fatty acids (such as stearic acid) can remain dry and dispersible. Stearin-treated rock dust has been used in British coal mines (7) and is commonly used in Polish coal mines.

Jan 1, 2019

By Inoka E. Perera, Robert Hildebrandt, Gerrit V. R. Goodman, Krzysztof Cybulski, Zdzisław Dyduch, Michael J. Sapko, Marcia L. Harris

To prevent coal dust explosion propagations, rock dust needs to be lifted and suspended in the air with the coal dust during an explosion. The addition of anti-caking agents prevents caking of rock dust in the presence of water. Mining and rock dusting processes can frequently create alternating layers of rock dust and float coal dust on mine surfaces. For this test series, a thin layer of coal dust was distributed on top of a layer of either treated or non-treated rock dust in the Experimental Mine Barbara, Poland. The experimental results compare the effectiveness of treated and non-treated rock dusts to attenuate a propagating coal dust explosion initiated with either strong or weak methane explosions. Experimental results indicate that the treated rock dust performs better than non-treated rock dust in arresting a propagating explosion, especially in the presence of moisture.

Jan 20, 2020

By Yasushi Arai

"Among Tokyo Metro’s approximately 200km of subway lines, the Tozai Line that connects Chiba Prefecture and mid-Tokyo experiences congestion of up to 199% at worst and relief of this has become urgent. Therefore, as it is imperative to increase the number of trains operating in the exceptionally congested area from mid-Tokyo going east, a large-scale renovation work is planned between Iidabashi Station and Kudanshita Station that will facilitate turn-back via 3 tracks. While ensuring the safe and stable operation responsible for about 1.35 million passengers daily, this highly difficult work of inner wall demolition and reinforcement of the side walls and floor slabs will only be implemented for 3 hours during late night. This paper discusses large-scale plans to improve turn-back facilities, and the methods of construction therein as an example of operational improvement of a subway network. 1) INTRODUCTION The Tokyo Metro Tozai Line (“Tozai Line”) opened over the entire 30.8 km distance from Nakano to Nishi-funabashi on March 29, 1969. It has the longest operating length of the nine Tokyo Metro lines, and was the first subway line to extend past the borders of the Tokyo Metropolis. Through train services with two other railway companies are available from the Tozai Line. Tozai Line trains join the Sobu Line of the East Japan Railway Company (“JR East”) and the Toyo Rapid Railway Line of Toyo Rapid Railway (“TR”) from Nishi-funabashi Station, and the JR Chuo Line from Nakano Station. The line is structurally distinctive in that 51% of it was built using the open-cut method, 43% of it is elevated and the remaining 6% was built when we used the shield method for the first time 1)2)3)."

Jan 1, 2016

By Michael Schmalzel

Freeport-McMoRan Copper & Gold, Inc. (FMI) will soon begin copper production from the Dos Pobres and San Juan deposits near Safford, Arizona. Ore reserves total 615 M tons grading 0.36% copper, predominantly as chrysocolla. Copper extraction will be by leaching with sulfuric acid. Fluor Canada Ltd. provided EPCM services to design an ore handling and conventional SWEW facility capable of producing a nominal 240 million pounds per year of cathode copper. The ore handling facility will process 114,000 tons per day of ore through three-stage, open-circuit crushing followed by agglomeration and product placement on the permanent leach pad. Stacking of ore on the leach pad will utilize Terra Nova Technologies&apos; "Super Portable" mobile stacking system. The stacking system fleet consists of 13 self- propelled, crawler-mounted mobile conveyor units, each with 72-inch-wide belting and a capacity of 6,800 tons per hour, including ten 250-foot-long portable conveyors, a horizontal feed conveyor, a 285-foot-long horizontal conveyor and a 220-foot-long radial stacker. PROJECT BACKGROUND Project History The Safford Leach Project is located in the Safford mining district in Graham County, Arizona, approximately eight miles northeast of the town of Safford and 170 miles east of Phoenix. The 3,360-acre property is located in the Gila River Valley, immediately south of the Gila Mountains, at elevations between approximately 3,000 and 5,400 feet above sea level. The Safford Leach Project is comprised of the Dos Pobres and San Juan deposits, two of five known copper ore deposits in the Safford mining district.

Jan 1, 2008

By C. P. Siess, S. L. Paul, E. H. Gaylord

Several types of tunnel supports are being investigated experimentally and analytically at the University of Illinois at Urbana-Champaign under the sponsorship of the Federal Railroad Administration, Department of Transportation. The results of work on two types will be discussed here. These are steel sets and continuous, monolithic steel-fiber-reinforced concrete liners. The latter is a model of a short length of liner that might result from a continuous slip-forming operation in a tunnel excavated with a boring machine. Tests have been performed on both types of support and analyses are being developed which will greatly broaden the scope of the test program. The objective of these studies is to improve the understanding of basic behavior of these supports, and to develop techniques for their analysis. The analyses will then be used to perform parameter studies that will lead to more rational procedures for structural design. The tests provide a check on the accuracy of the analysis and demonstrate the overall behavior and modes of failure. Another part of the project is concerned with the interaction of support and medium, and thus prediction of loads for the supports. These studies are presented in greater detail in a recent report (1). A brief outline of results obtained to date are presented in this paper. STUDIES OF STEEL SETS Description of Set Tests The sets tested were of the horseshoe type with a 5-ft radius arch section and 7-ft straight legs. They had bolted joints at the crown

Jan 1, 1974

By Min Chen, Qinghua Liang, Weishan Yan, Yuan Feng, Shigang Wang

Various coal mine robots (CMRs) and unmanned aerial vehicles (UAVs) are implemented to explore unknown mines for improving the safety and efficiency of mining. It is challenging for CMRs and UAVs to achieve accurate positioning due to the absence of the Global Positioning System (GPS), poor lighting conditions, and similar geometric features in complex mine scenes. LiDAR-based localization and mapping methods are more accurate than others, while long-time running in large-scale scenarios will introduce nonnegligible cumulative errors. This study presents a semantic-aided Li- DAR simultaneous localization and mapping (SLAM) with loop closure, which leverages the uniqueness of mine intersection structure to establish stable semantic loop closure. Specifically, we propose a semantic intersection descriptor of translation and rotation invariance, which encodes 3D point clouds of the same intersection from different positions and viewpoints into a unified image. By using the semantic descriptor, we can construct a constant loop constraint when the same intersection is revisited from different directions to reduce cumulative drift. We provide experimental validation using large data sets collected in two large underground mines, namely, a simulated Edgar mine deployed in ROS Gazebo and a public underground mine data set provided by ETH. Experimental results show that the proposed method has higher localization accuracy and outperforms the existing LiDAR-based SLAM strategies.

Feb 1, 2024

By Min Chen, Qinghua Liang, Weishan Yan, Yuan Feng, Shigang Wang

Various coal mine robots (CMRs) and unmanned aerial vehicles (UAVs) are implemented to explore unknown mines for improving the safety and efficiency of mining. It is challenging for CMRs and UAVs to achieve accurate positioning due to the absence of GPS, poor lighting conditions, and similar geometric features in complex mine scenes. LiDAR-based localization and mapping methods are admittedly more accurate than others, while long-time running in large-scale scenarios will also introduce non-negligible cumulative errors. This study presents a semantic-aided LiDAR simultaneous localization and mapping (SLAM) with loop closure, which leverages the uniqueness of mine intersection structure to establish stable semantic loop closure. Specifically, we propose a semantic intersection descriptor of translation and rotation invariance, which encodes 3D point clouds of the same intersection from different positions and viewpoints into a unified image. By using the semantic descriptor, we can construct a constant loop constraint when the same intersection is revisited from different directions to reduce cumulative drift. We provide experimental validation using large datasets collected in two large underground mines, namely, a simulated Edgar mine deployed in ROS Gazebo and a public underground mine dataset provided by ETH. Experimental results show that the proposed method has higher localization accuracy and outperforms the existing LiDAR-based SLAM strategies.

Aug 10, 2023

By K. L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper reviews the latest primary crushing and large cone crusher designs. It highlights how—in addition to using the larger crushers now available—maximizing the utilization percentages in each of the four stages of the rock size reduction circuit will assist in meeting the larger production requirements of existing and new mining operations. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year. INTRODUCTION Are larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? Boyd (2002) predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available. The rock size reduction process from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized in four stages: • Stage 1: Mining (rock breakage and fragmentation) • Stage 2: Pre-screening (scalping) • Stage 3: Primary crushing • Stage 4: Fine crushing (secondary, tertiary and quaternary) Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once the project design criteria and the mine plan have been established, the circuit’s utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stakeholders in the selection of the final comminution circuit, and both departments should be familiar with and contribute to the design of the circuit. This paper focuses on the four stages of a rock size reduction circuit from the mine to the mill, equipment selection, various ore and waste handling flowsheets, and improvements in crusher station design, all with the purpose of maximizing availability and plant utilization percentages. What is a large tonnage? From 1907 to 1914, the American Panama Canal excavated 300 million tonnes of material in 7 years (History of the Panama Canal, Wikipedia). Today’s large mining operations can move the same material in 10 months, using large crushers or multiple crushers for ore processing and large crushers and a mixture of truck haulage and conveyors for handling the large waste tonnages. Some examples include:"

Jan 1, 2017

Semiautogenous (SAG) ball mills are being increasingly used today for the coarse grinding of a range of ores, including gold, copper and iron. Larger mines are demanding mills with larger throughputs. This has led to some remarkable developments in mill diameters and installed powers. Conventional design principles - mills with trunnion bearings - have reached their limitations. This article describes one SAG mill with a slide-shoe arrangement and Krupp Polysius&apos; Combiflex twin drive. In August 1997, the world&apos;s largest SAG mill with a slide-shoe arrangement was commissioned in Queensland, Australia, operating as a wet mill. The inside diameter is 10.4 x 5.1 m (34 x 17 ft) effective grinding length. The 1.36-ktlh (1,500-stph) SAG mill is driven by two Combiflex drives (twin drives with 2 x 5,500-MW or 7,375-hp installed motor power) in conjunction with a girth gear (outside diameter 11,890 mm or 468 in.). Commissioning of the SAG mill was completed with no notable technical difficulties. The plant runs continuously except for planned maintenance stoppages and process-specific reasons. As this article is written, the machine has been in operation for about 8,000 hours without major problems.

Jan 1, 1998

By E. Alan Haley

Accurate and economic control of line and grade on long tunnels, large structures, excavations and waterways, has been a problem to surveyors and engineers for decades. The conventional method of surveying, incorporating a level, transit, and a number of surveying technicians, has proven, in the past, to be a very expensive and time-consuming operation. Alignment with a laser has solved most of the problem. Figure 1. With the advent of the Perkin-Elmer Model 5620 Construction Laser, use of laser light is now both dependable and economically feasible for unlimited applications in modern construction and surveying. The laser projects a continuous, narrow red beam of brilliant light, providing a constant alignment reference, and will not interfere with operations.

Jan 1, 1968

By D. M. S. Bhatia

Five sulfide minerals from the Magiwnt mine, southeast Missouri were analyzed for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1979

By E. Baliktsis

We have searched and analyzed several modern technologies aiming at the best applications of environmental management, the studying of quarrying ? mining as well as the excavation sites ? utilization ? rehabilitation. We have used long-range reflectorless laser surveying systems, so as to achieve the fastest and most accurate surveying of the extractive work sites. We also used them, in order to collect field data, measure distances, surveying monitoring stations and environmental parameters ? data. Furthermore these systems can make the field work quite faster, more reliable and credible and have low cost in collecting data even in dangerous and non-approachable areas. We have used and processed on the field data in G.I.S. applications, in order to create 2-D and 3-D digital ground models. These G.I.S. applications present the existing relief and the management of the final stage of the area. The suggested techniques and works needed, for reclamation and utilization of the areas, could be tried, evaluated and well presented. The evolution and utilization of these ?smart? modern tools for the effective environmental management of quarrying ? mining ? extractive activity sites, will be presented by using case histories from the Hellenic territory.

Jan 1, 2002

By M. Gaft, G. Panczer, R. Reisfeld, L. Nagli

Laser-induced luminescence and breakdown spectroscopy methods appear to be a good tool for real-time evaluation of dolomite content on moving belt. The distinctive feature for time- resolved luminescence is Dy3+ emission in apatite, which is excited by 251 nm laser light and detected with delay time of 5 ms and gate width of 1 ms. The distinctive features for breakdown spectroscopy are 604 nm line of F and P in apatite and 518 nm line of Mg in dolomite. The representative sampling of more than 200 pebbles has been studied by both methods. By luminescence method 100% of dolomite will be identified, while approximately 15-20% of apatite with extremely week Dy3+ luminescence may be mistakenly counted as dolomite. By breakdown spectroscopy the identification is 100% correct both for dolomite and for apatite.

Jan 1, 2002

By Alfred Haack, Günter Girnau

INTRODUCTION From 1967 to 1976 in the Federal Republic of Germany about loo km tunnels and 125 underground stations were constructed for municipal and commuter railways solely. Additional a remarkable amount of road tunnels and sewers were built. In 1977/78 a further 27 km railway tunnels, 3.5 km road tunnels and 65 km sewers and utility lines were under construction. This shows an enormous volume of tunnel construction work. In connection with this activity various technical research and development programmes have been carried out. They deal with nearly all fields of underground works as for example soil and ground exploration, excavating and lining techniques, calculation and last but not least waterproofing problems. It is impossible within the framework of this report to touch on all the problems. Therefore, only one problem area with its different aspects will be discussed: waterproofing systems and their last developments in Germany, especially, joint sealing with special consideration of the waterproofing of concrete segmental tunnel lining (1)

Jan 1, 1979

By Joern Katzer

It is vitally important to any tunnel project to have an accurate and reliable survey control network inside the tunnel for layouts, as-built surveys, and to provide guidance to the tunnel boring machine (TBM). However, the concepts and methodology to provide such a survey network are sometimes not well understood. For example, the first anticipated survey task that takes place during the bidding process is often ignored, which is to provide a comprehensive survey network preanalysis for the surface network and tunnel traverse based on survey statistics that will be used to make informed decisions on the survey requirements and methodology. Instead, these steps are often only vaguely based on previous results and prior tunneling experience. But each tunnel is different, and a solution that worked for one tunnel project might be unsuitable for another. The purpose of this paper is to provide tunnel project engineers, managers and surveyors with the general concepts for tunnel survey methodologies and examines several statistical tools for a basic horizontal and vertical tunnel survey preanalysis. These survey statistics tools provide useful estimates of the expected lateral and vertical tunnel traverse accuracies, but are not a replacement for a comprehensive tunnel network preanalysis. The proposed formulas do not take centering errors into account, are using average distances for each traverse leg, and assume that the survey data is free of outliers in the measurements. It is very important that the estimated instrument accuracy is based on true values that are reflective of measurement precisions that are actually achievable inside the tunnel to provide accurate results.

Dec 1, 2022

By Charles Stone, Eric Wang

A method for estimating geotechnical rock loads for shallow cut and cover subway stations is presented. Localized geotechnical conditions lead to extreme variations in rock loading on the walls of subway structures. Actual lateral rock stress on these structures can range from near zero to over four times the vertical in-situ rock stress. The primary factors affecting the actual lateral stress are intact and rock mass mechanical properties, excavation sequence, localized tectonic conditions, and potential future adjacent structures. The authors recommend using the AASHTO code value of 65 pounds per cubic foot (10 kN/m3) during concept design, followed by numerical analysis of rock wedges and stress measurement for final design.

Dec 1, 2022

By Graham Taylor, Mandy Agnew

Hardpans developing in tailings storage facilities (TSF) in Australia have been investigated in relation to Acid Rock Drainage (ARD) generation. This research had three main aims. Firstly it was to obtain an understanding of the physical and chemical characteristics of tailings residues which support the in-situ formation of cemented layers and hardpans. Secondly it was to examine how effective hardpans are at reducing ARD generation, and thirdly it was to investigate the promotion of hardpan formation to inhibit ARD and pollutant generation. This paper presents the data collected during investigations into the effectiveness of hardpans to reduce ARD generation. Three basic types of hardpans have been identified and examined: laterally extensive surface hardpans, laterally extensive cemented layers; and laterally discontinuous hardpans developing in locations of seepage. Their mineralogy, morphology, lateral extent, depth and rate of formation are dictated by sulfide and gangue mineralogy and content, milling and depositional techniques of the tailings and the climate. As the sulfides oxidise, acid and heavy metals are generated, while gangue mineral degradation is enhanced, adding to elemental loads. These liberated ions are then available for precipitation of secondary mineral cements through concentration during evaporation. In TSFs where hardpan development is restricted by mineralogy, grain size or climate, hardpan formation can be enhanced in seepage zones (eg. seepage from waste rock dumps) where tailings are exposed to seepage waters laden with heavy metals and sulfate. The effectiveness of hardpans in the inhibition of ARD generation is dependent on reducing oxygen diffusion and water infiltration into the underlying tailings. A reduction in water infiltration will diminish the transport of contaminants developed during sulfide oxidation and subsequent reactions. Water and gas movement through the hardpans at the CSA (Cu, Zn, Pb) and Elura (Pb, Zn, Ag) mines has been investigated. Permeability tests indicate the hardpans have reduced the infiltration rates by 10 to 100 times that of the fresh tailings. Oxygen diffusion rates were calculated and were shown to be up to 1000 times lower in hardpans than in fresh tailings. Such decreases are explained by persistent elevated &apos;degrees of saturation&apos; within the hardpans. These conditions were verified using a conceptual model of sulfide oxidation reactions, which allowed comparisons of diffusion coefficients with modelled and observed depths of oxidation within the tailings impoundments.

Jan 1, 2000