Search Documents

By Dana C. Reinke, David K. I Ingram

Researchers at the National Institute for Occupational Safety and Health partnered with the water well industry to develop engi­neering control technologies and training products to address noise exposure at the job site. Noise­induced hearing loss continues to be a problem in the well drilling industry. Research con­ducted by NIOSH found that air rotary drill rigs produce sound levels more than 90 dB(A) over the course of an eight­hour workday. Sounds levels above 90 dB(A), identified during hammer drilling and the hammering of casing, exposes workers to levels that can damage hearing. A typical air rotary drill rig provides no barrier, for noise and dust pro­tection, between the drill’s control panel and the drill stem. The development of a partial cab is the clearest example of NIOSH’s research partnership with the water well industry. NIOSH researchers determined that an engineering noise control to protect the oper­ator at the rig’s control panel would be effective, based on typical work site conditions. Many surface rigs do not have full cabs as a result of the original equipment manufacturer design or the high cost of aftermarket products. Developed as a partial cab, the NIOSH engineer­ing noise control design addressed stakeholders’ needs associated with cost, transport, and worker usage (Figure 1). Field tests found the partial cab effective in reducing sound levels at the rig’s control panel, a typical location for a drill rig operator. Sound levels at the control panel were reduced from 104 to 96 dB(A) (Figure 2). Coupled with continued use of personal protective equipment, such as hear­ing protection devices, the partial cab can help to reduce noise exposure. NIOSH researchers created a CD with informa­tion about noise exposure and the partial cab. Most important to well drilling companies is information on how to construct and attach the partial cab to drill rigs. The CD can be viewed on a standard computer and includes a video of the partial cab in use on a work site. Computer­aided design drawings are included on the CD and provide detail of the cab design as well as information on construction mate­rials and design details. Additionally, the CD provides background infor­mation on noise­induced hearing loss and hearing protection devices to increase knowledge about this occupational health concern. This information can be viewed by all company employees to help promote the partial cab’s importance to workers using the cab. More information on the partial cab noise control technology can be downloaded from www.cdc.gov/ niosh/mining NIOSH researchers also examined the health and safety training needs of workers in the ground water industry. It was quickly realized that most workers learn health and safety on the job and do not attend any sort of formal training. In addition, there is not a lot of time for daily “tailgate talks” or “shop talks” on health and safety issues. As a small business industry, the owner is often operating a drill rig along with his other employees. In general, new employees learn the job in an apprentice style sys­tem. As a result, workers and owners have few opportunities to access uniform health and safety information based upon the job — an outdoor work environment with daily change in work sites. With this information, NIOSH researchers devel­oped two products that deliver health and safety information to fit into the daily work of well drillers. Both are information circulars and are available through download at www.cdc.gov/niosh/mining and the NGWA Web site at www.ngwa.org/publication/ publications.cfm. These circulars are: Water Well Safety Bits. This booklet provides information in a “quick bites” style. It is pre­sented in a magazine format and can be left on

By A. E. Taylor, A. S. Judge, P. T. Lafleche

"Resource development in northern Canada has special requirements which derive from the unique environmental and eco-logical nature of the northern environment. In this paper several case histories in which the Permafrost Research Section of the Geological Survey of Canada (GSC) has participated are used to illustrate how geophysical methods may be used to address some of these considerations. Although some of these examples were developed while examining problems directly related to oil and gas development and transport in frontier regions, such or similar methods also have application to mining problems.IntroductionA critical parameter is the distribution and thickness of permafrost, which in northern Canada varies from being a few metres and discontinuous at the southern limit to thicknesses in excess of 700 m in the Arctic Islands'!'. Figure I is a schematic diagram of typical ground thermal conditions in a permafrost zone. The upper zone is defined by an active layer which undergoes a seasonal freeze/thaw cycle. In the simplest case, the ground remains permanently frozen below the active layer to the depth of the O°C isotherm, which is defined as the base of the permafrost. Water chemistry, pore structure and pore or grain size may cause the base of the frozen ground to be above the permafrost by up to 100 m(2). Ice can be found within the permafrost in the pores of solid rock or sediments, as massive ice within unconsolidated sediments or as ice lenses within fissures in a solid rock mass. The mining technique used in these conditions, whether open pit or underground, can differ considerably from that used in southern Canada. In the high Arctic, for instance, the dry drift method is feasible underground in the permanently frozen host rock. The frozen nature of the wall rocks can obviate water-related problems."

Jan 1, 1987

By Rashmi Ramesh

Zinc oxide nanoparticles and nanostructures form an active area of research in the recent years. It can be doped to modify electronic, optical and other properties. Synthesis and characterization of zinc oxide is of extreme importance in order to understand the structure property relationship in this material which is now being considered of importance next to carbon nanotubes. Microstructure of zinc oxide nanomaterial is extremely sensitive to the preparation conditions. Nanocrystalline pure and Mn and Mg doped zinc oxide samples were prepared by wet-chemical method under different growth conditions. The samples were investigated for crystalline phase, microstructure, morphology and luminescence characteristics. The effect of Mn and Mg doping on the characteristics of ZnO have been discussed.

Jan 1, 2010

By Leonard J. Prosser, Dennis R. Dolinar, John L. Ellenberger, Gabriel S. Esterhuizen, Anthony T. Iannacchione

The room-and-pillar mining method is used extensively in underground limestone mines in the Eastern and Midwestern U.S. The rock mass is typically a near-horizontal, bedded deposit at relatively shallow depth. A survey of 34 mines was conducted in which data on roof spans, rock mass properties and support practices were collected as part of a National Institute for Occupational Safety and Health research project into ground control in limestone mines. The average room width is 13.5 m (44 ft), accommodating large mechanized equipment. The results show that the immediate roof beam can consist of many individual layers and can contain several near-vertical joints. In spite of the room widths, the roof is naturally stable in many mines. Observed roof instabilities can generally be related to excessive horizontal stresses or unfavorable geological structures that cause block fallout or beam failure of the bedded roof rocks. The survey showed that the rock mass quality of the limestone does not vary significantly throughout the Eastern and Midwestern U.S. Roof conditions and the need for support were found to be closely related to the thickness and competence of the first layer of limestone in the roof. The findings highlight the need to identify local geological structures and the roof beam characteristics so that support alternatives can be evaluated. Monitoring and observational technologies that are available for identifying potentially unstable roof are presented, which include: roof characterization using the Rock Fall Risk Index, automated logging of roofbolt hole drilling, microseismic monitoring and displacement monitoring.

By Peter Townsend, Sergei Diachenko, Allan Moss

The Palabora Mining Company has successfully extended the life of its operation by developing a 30,000tpd block cave underground mine below the now closed open pit. The process of transitioning from surface to underground mining has been technically, operationally and managerially challenging. This has been due to a number of factors; in particular, the development of a block cave in a very competent rock mass. The competence of the rock mass is clearly demonstrated in the open pit that preceded the block cave, one of the steepest deep open pit excavations in the world. With cave breakthrough, however, the pit was ?instantaneously? deepened by 400m causing a major failure of the northwest wall involving close to 100Mt of waste material.

Jan 1, 2006

By Robert Benedetti

This paper describes various mitigation methods in order to reduce the maximum acceleration of the floorboard of hulled vehicles when explosive charges buried in water saturated sand were detonated beneath them. The effects on floorboard acceleration of adding a vehicle hull, several types of floorboard bracing, the use of foam to fill the gap between the floorboard and hull, and the use of foam to isolate the floorboard from the hull have been investigated. Small scale testing was conducted, which used bar magnet velocity gages to measure the velocity as a function of time of the center of the floorboard, directly over the charge, where the acceleration was expected to be greatest.

Jan 1, 2012

By József Faitli, Barnabás Csoke, Károly Solymár, Zoltán Hatvani, Dimitri Papanastassiou

In most cases, the sizing of dry or wet mills for ore processing is primarily based on the determination of the Bond grindability index, using the Bond-Kjos-Rowland relations. In several cases, grinding takes place under conditions different from these and the grinding conditions have a great influence on the postgrinding process. This is particularly true for the grinding of bauxites where grinding takes place in alkali, often in higher temperature in alkali Liquor. So it is necessary to develop a testing method providing a reliable grindability index even under these special circumstances and allowing a more precise mill sizing. Therefore we surrounded the grinding crucible of the Hardgrove mill with a crucible furnace to heat it. The new heated mill is suitable to determine the grindability index under temperature-controlled circumstances, in liquids (water and alkali) with different temperatures. The required heating power is 2000 W. In the implemented equipment we installed four 230V/500W electric heating wires made from heat-resistant alloyed material and surrounded by ceramic insulators. The temperature and temperature-gradient are measured by four PT100 platinum thermal resistors. The data acquisition and control program written in the C language in the Lab Windows CVI program environment measures the voltage proportional to the temperature. Determining the grindability indices of hungarian and greek bauxites experimentally, first dry grinding tests were carried out under standard conditions. During wet and alkaline grinding, to 50 g of dry bauxite 85.5 g of industrial alkali with a concentration of about 200 g/l was added. As grinding aid 2 g of CaO (4 % of dry bauxite) was dosed. From the data it can be concluded: - The tested bauxites show a similar behaviour against temperature change. However, the extent of grindability change is different for different bauxites. - Soft Hungarian boehmitic bauxite can be ground in a high-temperature alkaline medium better than hard Greek one. The increase of grindability according to the high-temperature Hardgrove indices: (kHT = Dry o HT,alkaline H /H ): for hard Greek and soft Hungarian boehmitic bauxites: kHT = 1.7 and 2.4 respectively; according to estimated Bond indices (kB,HT =Wi,dry/Wi,HT, alkaline ): kB,HT = 1.6 and 2.1. - The increase of grindability is the most important factor the reaction of kaolinite with caustic liquor and lime and the loosing of the textural structure at 80 ºC and especially at 100 ºC.

Jan 1, 2003

By F. A. Penning

Improved skips, with lightweight cylindrical bodies, have made a significant contribution to advancing mine hoisting technology. New concept skips of aluminum bodies with rubber lining; fiberglas bodies with polyurethane liners have been designed and fabricated for field testing at an operating mine. New design, adjustable guide rollers have shown improved ride characteristics with noticeably less wear. Major reductions have been made in stress levels and stress concentrations. Field experience has shown the practicality of the approach. Guide alignment has been measured using the Guide Alignment Measuring System (GAMS). Analysis has been applied to interpret the data. Field measurements in an operating shaft and a test tower have shown the agreement in data from GAMS and plumb wires. Reproducibility has been demonstrated. The data are useful to realign shafts, to use as s maintenance tool, and to evaluate the maximum safe hoisting speeds. The surveys are made at several hundred feet per minute and the system is self-contained. Dynamics of skip-guide interaction has been analyzed using the computer program SKIP II. The effects of speed, weight, type of guides, kind of misalignment have been studied. Resonance has been demonstrated and factors that eliminate resonance have been identified. Data from the GAMS surveys are applicable to the SKIP II program. Interaction between the hoist rope and the mine conveyance has also been studied. Computer programs and closed-form solutions are presented. Economic impact of lightweight skips is presented for an existing mine and for a new mine. Reduction in rope size has a profound effect when using a lightweight skip for the same capacity. Increased productivity can be realized by keeping maximum rope pull the same while increasing skip capacity. Examples and charts project the significant savings in capital expenditure for new installations.

Jan 1, 1985

By Gary B. Petersen

The author has developed a seven-step process called the Applied Rock Mechanics (ARM) Protocol that the author has used to solve numerous roof stability problems in mines throughout North America since 1975. It is a practical evaluation process using trained observation, innovative data collection instrumentation, video borehole cameras, analytical processes, and controlled testing methods that have become highly effective in solving ground control problems in every type of underground mine. This paper will describe each of the steps of the protocol and how the rock mechanics engineer applies them to resolve a typical ground control problem.

Jan 1, 2012

The ability to track miners and communicate with them while they work in underground coal mines is important during normal daily operation, and critical in emergency conditions. This was evident during recent incidents at underground coal mines worldwide. Communication with miners and the knowledge of their location is of great importance for rescue efforts and the preservation of life. Numerous technologies have been developed, adapted and deployed to meet tracking requirements of the Mine Improvement and New Emergency Response (MINER) Act of 2006. Evaluating the performance of these systems has proven to be dif?cult for mine operators, system manufacturers and regulatory agencies. The MINER Act requires operators to improve accident preparedness by developing an emergency response plan speci?c to each mine. With the recent implementation of the provisions of the MINER Act of 2006, all underground coal mines in the United States are subject to the mandates of legislation concerning communication and tracking system installation. As of June 2011, 203 new or revised tracking and/or communication systems had been approved by the U.S. Mine Safety and Health Administration (MSHA), with nearly 50 other systems or revisions in the approval process (MSHA, 2011). At that time, the available approved systems for underground coal mine use included these types: ? Leaky feeder communication systems. ? Fixed node-based communications and/or tracking systems. ? Wireless node-based communications and/or tracking systems. ? Medium frequency (MF) communication systems. ? Communication system peripherals. Other types of tracking systems have since been developed and some manufacturers are seeking approval for use in this application. Some of the new products include through-the-earth (TTE) systems and various radio frequency (RF) adaptations. New technologies that are currently being developed and deployed in other industrial applications should also be considered, including acoustical, optical, inertial and hybrid technologies. To date, no uniform method has been employed in the industry to effectively compare and evaluate the performance of installed systems. Neither industry operators nor regulatory agencies can accurately assess the capabilities of installed systems in the continuously changing mine environment. There is a need for a uniform evaluation method that provides the ability to assess how different systems and technologies perform in various mining applications, and whether they can satisfy the regulatory requirements.

By Gennaro Di Lauro, Laura Meraviglia, Demostenes Efstratiadis, Danilo Coppe

This paper presentation regards the European Union’s project “I.C.E.A. - Identification Colors of Explosives and Blasting Accessories (Agreement number – HOME/2010/ISEC/AG/071 – 30 – CE – 0447240/00-11), submitted under the call for proposal “ISEC 2010 ACTION GRANT” of the “Prevention and Fight against Crime” Program of European Commission. The main objective of the project is to simplify counter-terrorism security measures and the procedures for visual identification of blasting devices.

Jan 1, 2015

By Sergio Neves Monteiro

In the present work, a ceramic foam elaborated with illitic clays was characterized. Properties related to density and compression strength were determined in samples fired at 1300oC, a temperature that permits the clay structure to generate and retain gases that will produce the foamy structure. The microstructure of the ceramic foam was studied by X-ray diffraction, scanning electron microscopy and mercury porosimetry. The results showed that the ceramic foam presents a bulk density of 0.38 g/cm3. The microstructure is formed by large open pores, quartz particles and vitreous phase.

Jan 1, 2006

By K. R. Griffin

Explosions in underground coal mines have been a serious safety concern since the advent of mining; despite significant technological advances, they are still occurring. Parameters such as barometric pressure, geological changes, and changes in ventilation can contribute to an explosion. These factors can be monitored with available and developing technologies to create algorithms that predict when explosions are more likely to occur. This paper reviews current underground atmospheric monitoring systems and related regulations around the world. In addition, suggestions for improvement and implications for explosion prevention are discussed.

Jan 1, 2011

By Adriana Gómez

White dross is a result of the aluminum oxidation during its primary production and is mainly composed of metallic aluminum, Al2O3, with minor amounts of AlN and some other oxides. Because of the great variety of phases, the quantitative characterization is complicated. This work shows a quantitative method to determine the main phases of white aluminum drosses by means of X-ray diffraction (the Rietveld method). Nowadays the Rietveld method is maybe the most useful method for obtaining quantitative phases information in multicomponent mixtures, this method permits relatively quick quantitative phase analysis by fitting the calculated X-ray diffraction profile with the observed one. The analysis were done using powder with a grain size less than 45 µm; to obtain the suitable material size the aluminum dross was grounded by ten minutes, several times. The grounded material was screened, and the material smaller than 45 µm was taken to quantitative XRD analysis. Keywords: Rietveld Method, Characterization, Aluminum dross.

Jan 1, 2005

By Joseph Daly

This is the detailed evaluation of the establishment and implementation of an ‘oil recycle plant’ located on site at Boggabri Mine NSW, (Australia); its production, its use and its value. Also discussed in detail is the quality of the raw material produced, and the process and initial application of this raw material generated as well as the analysis of such, as a component within bulk explosive as applied to the mining industry as compiled during analysis. Laboratory analysis prior to field testing is also discussed including independent external laboratory analysis as well as the environmental benefits and a business case for recycled oil in blasting. This paper includes technical details of the product including densities, velocity of detonation and other associated key performance indicators. The intention is to off-set the amount of Distillate (Diesel) utilised as a component of bulk explosives, with a raw recycled oil and thus reducing both the environmental carbon footprint as well as production costs with regard to introduced petrochemical production and utilisation; an oil that is an existing recourse of controlled waste not only difficult but expensive to otherwise dispose of, whilst keeping the entire process ‘on-site’. Though recycled oil in blasting is not an entirely original idea, the key feature of this paper is the ability to complete the entire process on-site.

Jan 1, 2014

By D. E. Wolfson

As a part of its overall program of coal carbonization, the Bureau of Mines is studying the coking properties of coals that may be used for metallurgical purposes. The objectives of this study were given in detail in a previous report.2/ The inherent suitability of coal for metallurgical use depends primarily on (1) chemical composition, (2) preparation characteristics, and (3) carbonization behavior. The first two factors, as well as the available reserves, are considered in selecting coals for carbonization tests. According to the estimate of reserves by Dowd,3/ the recoverable coal in Floyd County in beds 28 inches or more thick, in thousand tons, is as follows: [ ]

Jan 1, 1958

By J. R. Thoenen

This circular is part 5 of the third paper (entitled "Excavation") of a series summarizing the technical problems involved in the production and preparation of sand and gravel. Part 1 discussed the use of power shovels, draglines, and excavator cranes; part 2, power scrapers, slackline cable-way excavators, and hydraulic monitors; part 3, hydraulic, clamshell, ladder, and dipper dredges; and part 4, haulage systems in general, with particular reference to locomotive and car, hoist and car, and remote-control systems. This circular discusses the use of motor trucks, conveyor belts, pumps end pipe lines, barges and towboats, and aerial trams. MOTOR-TRUCK HAULAGE During recent years motor trucks have gained considerable ground as a successful competitor of locomotive haulage for quarries and gravel pits. Often where trucks have displaced locomotives and cars the operators readily admit an increase in both labor and total haulage operating costs but point to some other advantage as offsetting the extra expense. In other instances haulage costs have beep reduced by the use of trucks. In still others operators, having replaced locomotive haul with trucks, have again returned to the earlier method. Obviously gasoline-driven motor trucks cannot successfully compete with other types of haulage under all conditions. The apparent' growth in the number of advocates of truck haulage, however, indicates that it has passed the experimental stage and become a permanent competitor to other tyres.

Jan 1, 1936

By Patrick J. Williams, Peter J. Pollard

"Abstract - Enigmatic hydrothermal vein/breccia/replacement Cu-Au deposits with magnetite and/or hematite are well-represented in Australian 1850 Ma to 1500 Ma terrains and associated with different-aged synorogenic intrusions in the Tennant Creek Block (ca. 1850 Ma); the Gawler-Curnamona region (1640 Ma to 1590 Ma); and the Cloncurry district (Mount Isa Eastern Fold Belt, 1540 Ma to 1500 Ma with a possible earlier event at ca. 1600 Ma). No deposits are known to be coeval with various 1780 Ma to 1610 Ma anorogenic intrusions. Deposits are hosted by many different rock-types with varying metamorphic grade including granites and various supracrustal rocks. Depth of mineralization varied from many kilometers in semiductile crust (e.g., Cloncurry deposits) to very shallow (e.g., Olympic Dam). Ore deposition near Cloncurry occurred in brittle-ductile shear zones from geochemically variable and complex, CO2-rich, 300°C to 500°C, high salinity fluids with magmatic stable isotopic signatures. Recently published studies of a giant granitoid-hosted magnetite vein complex at the Lightning Creek prospect (>1000 Mt magnetite) suggest it is a product of internal differentiation and endogenous Fe and Cu-rich hydrous-carbonic fluid phase generation within a quartz monzodiorite-monzogranite intrusion. Coupled with other field relationships, this points to a possible genetic relationship with intermediate (55 to 65 wt% SiO2) members of an alkaline and partly shoshonitic granitoid supersuite which appears to have both mantle and crustal source components from ?Nd evidence. In constrast, main-phase mineralization at Olympic Dam in the Gawler Craton is distinguished by hematite-phyllosilicate alteration and chalcopyrite-bornite-chalcocite zoning, reflecting fluid mixing in a high level (<250°C) system with a probable large component of meteoric water. Early high-temperature parageneses and fluid inclusions imply that the extensive hematitic breccias overprinted an older magnetite system which may have had similarities with those at Lightning Creek and Ernest Henry in the Cloncurry district.Deposits of this family are inherently difficult to find and evaluate as even within a single district, there is no reliable relationship between the location of ore and any specific combination of geophysical characteristics. Diverse alteration assemblages, geochemistry and physical characteristics suggest the deposits reflect the interaction of multi-sourced fluids with different host rocks in a wide range of geological environments. Recent discoveries and research in the Cloncurry district have extended the range of deposit models available and aid the development of a rudimentary classification in which economic and exploration characteristics can be linked to variations in the mechanisms and environments of ore formation."

Jan 1, 2001

By L. H. DeWald

During the examination of various commercial brands of copper wire bars, which had exhibited different degrees of adaptability for being drawn into fine gages of wire by the present-day high speed machine, it was found that each brand had a more or less characteristic crystal macrostructure. The extremes of these macrostructures are similar FIG. 1.-EFFECT OF METAL TEMPERATURE IN CASTING ON CRYSTAL MACROSTRUCTURE OF BAR. Reading from left to right, metal temperatures were 1166" C., 1149" C., 1132" C.. 1121" C., 1093" C. to the maximum variation shown in the photomacrographs reproduced in Fig. 1. As the various brands did not differ materially in chemical composition, it was concluded that the differences in structure were the result of variations in casting technique.

Jan 1, 1931

By M. Reza Saberi, T. Ted Miyake

Driven piles are a common tool in any engineer’s toolbox for supporting large structures over very soft ground, especially in high seismic risk zones. Challenges include achieving sufficient vertical and lateral load capacities within the constraints of pile spacing and geologic conditions. This was the case for a project in Orange County, California with a state-of-the-art, $180 million plant for biosolids processing, biogas management and energy recovery located in marshland next to an existing waste water treatment plant. The new construction for the Irvine Ranch Water District included a 70-foot (21 m) tall building and three closely spaced, 90-foot (27 m) high, 65-foot (20 m) diameter, egg-shaped steel digester tanks. The lower 35-feet (11 m) of the tanks were constructed below ground level. The site was underlain by up to 45 feet (14 m) of highly compressible peat and organic clays with standard penetration test (SPT) blows as low as 2 blows/ft (30 cm). Some of the peat layers had measured in-situ dry densities of less than 30 pcf (480 kg/m3) with moisture contents of over 250 percent. The soft clays and peat were underlain by a dense layer of sand and gravel at depth. Groundwater was very shallow. While nearby sites were designated by others as seismic site class “D”, this site was clearly class “F” (SF) which required site specific seismic hazard and time history analyses. Six recorded time histories were selected from the 1994 Northridge, 1989 Loma Prieta (California) and 1999 Chi Chi (Taiwan) earthquakes for the ground motion analysis considering the magnitude of the earthquake, distance to the source, characteristics of the earthquake source (i.e. type of fault displacement), peak ground acceleration, local site geology, station type (i.e. free-field or small structure stations), and spectral content that was similar to the period range of interest. Following ASCE’s Guideline Document 7-05, a site-specific horizontal acceleration response spectra (ARS) was developed for the maximum credible earthquake (MCE) associated with the site.

Jan 1, 2018