Search Documents

By T. C. Green

A two-phase program evaluated commercial proximity warning devices and then served to design and develop an automatic electrostatic field strength measurement device with improved performance. The Phase I program consisted of test and evaluation of three commercial proximity warning devices, all of which operate on the principle of electrostatic field intensity measurement for determining proximity to high voltage power lines. Performance testing of these devices utilized full-scale cranes and power line systems and a scale model facility. The evaluation results were reported in the Phase I report entitled "Evaluation of Proximity Warning Devices" dated 22 February 1980. Under the Phase II program, a microproressor-based data acquisition system was designed and developed to collect and measure field strength at distributed points around the crane boom. This unit (referred to as the Distributed Sensor AC Electrometer) measures the field strength about a crane boom using 17 distributed sensors. Keyboard control is provided for the equipment operator. Measured field strength values are displayed on a line printer and recorded on magnetic tape. Laboratory testing of this unit demonstrated performance characteristics and field strength measurement accuracy within the design goals. A Phase III measurements program is proposed using the AC Electrometer to map the field strength contours about power line configurations.

Jan 1, 1981

By William R. Archibald

This report presents the results of a program demonstrating the technical and economic feasibility of hydraulic borehole mining of uraniferous sandstone. This mining technique involves the drilling of a borehole from the surface down into the ore body. A borehole mining tool consisting of a high-pressure cutting jet and a slurry jet pump is lowered down the borehole. Water from the high-pressure cutting jet cuts into the sandstone formation generating a water-sand slurry which flows to the slurry jet pump and is pumped to the surface. The cutting jet is rotated and moved up and down from the surface, thereby generating a cavity in the formation. When the cavity size reaches a point beyond the effective radius of the cutting jet, the mining tool is moved to an adjacent borehole and the process is started again. This program was carried out in four phases. Phase I included modifications to the borehole mining system (built and tested under a previous contract, No. H0252007, for the mining of coal) and factory tests of the jetting system. Phase II covered the field tests and a public demonstration. Phase III involved nozzle and equipment modifications and factory tests. Field testing continued under Phase IV along with an evaluation of this method. The field tests were conducted successfully on Rocky Mountain Energy Company's Nine Mile Lake property near Casper, Wyoming. Results indicate that; hydraulic borehole mining of uranium is technically feasible (300 tons of uraniferous sandstone were mined from a depth of 90 ft) and the hydraulic borehole method is economically attractive. However, additional testing is required to clearly define the economic feasibility.

Jan 1, 1978

By Matthew A. Perras

With growing populations, infrastructure projects are utilizing underground space to expand transportation networks, water supply and sewer disposal systems and hydropower facilities. These new projects require large diameter tunnels to meet the growing demands. As the tunnel diameter increases, not all rock mass properties are scalable and precedent experience becomes less reliable. One such non-scaleable property is lamination thickness. Numerical modelling was conducted to determine the influence of lamination thicknesses on a 16 m diameter tunnel. Five different areas of excavation response were found to exist for laminations ranging between 0.16 to 16 metres in thickness. For this tunnel diameter, critical lamination thicknesses of 6 metre and 1 metre were found to exist. Above 6 metres the excavation response was similar to isotropic models. Below 6 metres the stresses and yield are channeled by the lamination boundaries, increasing plastic deformation. Below 1m multiple lamination units become unstable and the displacements increase significantly and the shape and extent of the yield zone size changes dramatically. The yield zone is controlled by bed deflections and bed parallel shear. As the lamination thickness decreases tensile failure first begins in the haunch area and progressively extends above the crown until a self-limiting plastic yield zone shape is reach at lamination thicknesses below 0.4 metres. Conclusions drawn from observations at the Niagara Tunnel Project are those of the authors.

May 1, 2009

By S. Agarwal, S. Frimpong

The creation and maintenance of a healthy working environment in surface mining operations require sustained efforts in pursuing advanced research initiatives toward the development and deployment of powered haulage technologies. This paper contains progress summary on a frontier research in truck dynamic control, vision and collision avoidance. This research is required to provide solutions to challenging problems regarding operator visibility in truck haulage in a surface mining environment. The paper focuses on truck control kinematics and dynamics, truck-haul road interactions, intelligent truck sensing, intelligent truck collision avoidance system, integrated system for situational awareness, augmented visualization and operator interface, and field testing and error variance modeling of developed technologies. A sensor suite of four subsystems, including front-side stereo-camera, front-side Doppler radar, close range sonar proximity sensors, and rear-side camera system have been recommended for developing a 360° truck operator vision to allow safe operations. This research initiative is significant because it will provide a strong basis for developing technologies to improve truck haulage safety in surface mines and construction sites.

Jan 1, 2007

By F. De Lucio

Para la aplicación de la instalación de un sistema de relleno hidráulico es necesario evaluar las funciones que el relleno debe contener y determinar si el material a usar cumpla con las funciones especificadas. En ese sentido, el objetivo del texto presenta una interpretación científica sobre tal método para especificar las funciones que el relleno deba cumplir y la metodología experimental adecuada que evalúe cuantitativamente a un relleno hidráulico.. Asimismo, se describen sus propiedades estructurales como la densidad relativa, reducción de volumen y estabilidad de tajeos contínuos, así como los métodos indirectos para inferir dichas propiedades y las posibles consecuencias secundarias que pueda generar el empleo de relleno hidráulico.

Nov 20, 1972

By M. D. Aldridge

The results of a two-year research effort aimed at improving communication systems in coal mines is reported. A review of communication methods presently used in coal mines is presented. Theoretical and-experimental results of a four pronged effort in the areas of (1) through-the-earth propagation, (2) paging system design, (3) improvement of wired telephone systems, and (4) carrier current systems are described. Auxiliary systems not included in the above are considered briefly. Various conclusions are drawn in light of practical constraints and the needs of the mining industry. The study clearly demonstrated the need for nine communications to be designed on system basis. The viability of new technology for providing reliable mine communication for improving mine safety and operating efficiency is shown.

Jan 1, 1973

By F Gervilla, J Laukkanen

The Kevitsa Ni-Cu-PGE deposit in northern Finland contains disseminated Ni-Cu-Fe sulfides, and platinum-group minerals (PGM). The 2.05 Ga-old ultramafic-mafic, funnel-shaped intrusion is intruded into a volcanosedimentary sequence. The major ore minerals are pentlandite, hexagonal pyrrhotite and troilite, chalcopyrite, cubanite and magnetite. Pyrrhotite and pentlandite are replaced by pyrite, millerite and heazelwoodite near the surface. Nickeline, maucherite and gersdorffite are locally abundant. A pilot feed sample of 575 t of the main orebody at Kevitsa had average grades 0.45 per cent Cu, 0.36 per cent Ni, 1.85 per cent S, 0.33 g/t Pt, 0.34 g/t Pd and 0.19 g/t Au, with 0.06 per cent Ni contained in silicates. Higher PGE contents (2 - 27 ppm) occur in a vertical N-S bearing fault zone. The PGM (n = 6022) mapped in specimens of four drill holes, consist of sperrylite 34.7 vol per cent, braggite and cooperite 18.5 vol per cent, geversite 17.2 vol per cent, moncheite 14.7 vol per cent, merenskyite 6.7 vol per cent, stibiopalladinite 4.3 vol per cent, sobolevskite 1.9 vol per cent, kotulskite 0.7 vol per cent, michenerite 0.6 vol per cent, keithconnite 0.3 vol per cent, rustenburgite 0.1 vol per cent, melonite, froodite, laurite together 0.1 vol per cent and only a few grains of sudburyite, irarsite, vysotskite, erlichmanite, hongishiite, Pt-Cu-alloys, three undefined Pd and Pt bismuthinides and antimonides and a Pd-Cu-bearing Pt-Ni-Fe sulfide. Most of the PGM, 62 per cent, are enclosed in silicates, 29 per cent are intergrown with sulfides, nine per cent are within sulfides. A portion of the PGE occurs in solid solution in sulfides and arsenides. Ni flotation yielded smelter-grade concentrates averaging 12.2 per cent nickel. The average sulfide Ni recovery is 78.8 per cent and total Ni recovery is 65.3 per cent. The average Pt is 10 g/t at 55 per cent recovery, Pd 7.7 g/t at 38 per cent recovery and Au 1.6 g/t at ten per cent recovery. Cu concentrates averaged 28.6 per cent Cu with an average recovery of 78 per cent and further 11 per cent in the nickel concentrate. The copper concentrate contains 4 g/t Au at 24 per cent recovery. The average Fe to MgO ratio 17.9 is well above the targeted minimum of 4.5. The pilot results show that the previously used TETA (triethylene tetramine) can be avoided and good quality, smelter-grade concentrates can be produced from the Kevitsa ore at economical levels of recovery by conventional flotation methods.

Jan 1, 2008

By Lars Skogsberg

Work with hand-held power tools can be found in most industries all over the world. This type of work exposes the operators to different kind of loads like gripping-forces, feed-forces, exposure to vibration and noise, holding hot or cold surfaces and the exposure to dust. Designing a power tool with good ergonomics is a matter of finding the best compromise. As a simple example, increasing the mass is not acceptable because it will increase the forces needed to handle the tool. At the same time increased mass will in most cases reduce the vibrations. Vibration disorders related to the use of hand-held power tools has been known and reported since long. It is therefore essential that low vibrating tools are developed and used. The new vibration regulations in Europe, based on the Physical Agents (Vibration) Directive, have put increased focus on the vibration control in industry. Forces acting on the tool cause vibration Tools for industrial use must be of very robust design to withstand the very hard use they are exposed to. Industrial tools are therefore normally designed with the main parts made of metal. From a vibration point of view this means that most tools can be regarded as rigid bodies, especially because the dominating frequency normally is equal to the rotational frequency of the tool spindle or the blow frequency for a percussive tool. These frequencies are with few exceptions below 200 Hz. Handles however can not always be regarded as rigidly connected to the tool. There are several examples of weak suspensions designed to reduce vibration transmitted to the hands of the operator. There are also examples of designs where the handles just happened to be non-rigidly connected and in some cases even in resonance within the frequency region of interest. Oscillating forces act on the tool and the result is vibration. Design principals In all cases forces are the source of vibration. This leads to the three basic principles to control vibration: • Control the magnitude of the vibrating forces. Examples are the balancing unit on a grinder or the differential piston in a chipping hammer. • Make the tool less sensitive to the vibrating forces. Examples can be when the mass of the guard on a grinder is rigidly connected to the tool to increase the inertia of the tool. • Isolate the vibrations in the tool from the grip surfaces. Examples are vibration-dampening handles on grinders or pavement breakers, the air-spring behind the blow-mechanism in a riveting hammer or the mass spring system in a chipping hammer.

Jan 6, 2006

By Terry R. Neumann

In 1987 and 1988, the U.S. Bureau of Mines conducted a mineral resource investigation of the 31,400-acre Muddy Creek Wilderness Study Area (UT-060-007). The investigation was requested by the Bureau of Land Management and authorized by the Federal Land Policy and Management Act of 1976 (Public Law 94-579). The study area is located in Emery County, Utah, about 50 air-miles southwest of Green River, Utah. The wilderness study area is in the San Rafael Swell region of the Colorado Plateau Physiographic Province. Rocks in the area consist of gently dipping sedimentary strata of Permian, Triassic, and Jurassic age.

Jan 1, 1988

By P. G. Claridge, R. A. Tenbergen

"Pipe Open Pit ore is delivered by rail to the Thompson Mill at a rate of 34,000 tons per week. Ore is milled at a rate of 220 tons per hour.Characteristics of the serpentinised peridotite host rock are such that significant deviations from hitherto experienced milling practice became a necessity because of coagulation of the gangue upon cominution.Extensive development work was done in the grinding and classification circuits to better understand the ore characteristics and optimize operating parameters and the use of available equipment. This work ultimately resulted in the change from 30 to 20-inch diameter cyclones.Coagulation of the ore slurry and the characterstics of the sulfide minerals necessitated an ""unconventional approach"" in processing as compared with the beneficiation of Thompson Mine ore.Recent changes in ore characteristics led to testing of antistatic agents to reduce tailing losses."

Jan 1, 1975

By Martín Antonio Encinas‐Romero, Patricia Guerrero‐Germán, Jesús Leobardo Valenzuela‐García, José R. Parga‐Torres, María A. Bracamontes‐Landavazo, Agustín Gómez‐Alvarez

A study was carried out to process a sulfide mineral concentrate from Norwest of Mexico containing 97 g/t Au, 0.15% Cu, and 15% Fe. An oxidative acid pretreatment was investigated using ferric sulfate as oxidant, followed by leaching of gold with sodium cyanide. Scanning electron microscopy, SEM-EDS, and X-ray diffraction, XRD, the analysis confirms the presence of quartz and pyrite species. First, a leaching was carried out without pretreatment, at ambient conditions, T = 25 °C and P = 1 atm, obtaining only a 45.2% gold extraction. Once the presence of Fe and Cu sulfides had been confirmed, the Eh-pH diagrams were constructed for the Fe-S-H2O and Cu-S-H2O systems, where it is appreciated that pyrite and chalcocite can dissolve with high oxidation potentials and forming sulfur, oxidizing to sulfate at highly acidic conditions. The oxidized concentrate was neutralized and adjusted to pH > 10.5; it was leached at ambient conditions, at different particle sizes, 44, 37, and 26.5μm, achieving an Au extraction of 75% using a concentration of 0.5% NaCN, 26.5μm particle size, 20% solids, and P = 1atm. Then the oxidized material was subjected to different temperatures, 25, 50, and 70 °C, under the same conditions and obtaining Au extractions up to 92% at 70°C. Additionally, the leaching process was compared using an autoclave reactor at moderate pressures, obtaining an increase in the extraction of Au up to 98% in 2 h, at T = 70 °C and P = 0.62 MPa.

Jan 23, 2022

By James D. Eklund

Towards the goal of improving safety, economy and efficiency of scaling in underground metal/nonmetal mines, Battelle developed a combination prying/hammering scaling tool. A prototype was subjected to limited testing 1) to verify its operational functions and 2) to assess its potential capability in future underground testing.

Jan 1, 1983

By Tom Szaraz, Steve Skelhorn

Part of a major sewer expansion for the City of Columbus, Ohio. The Big Walnut Outfall Augmentation Sewer (BWOAS) consists of 4,000m (13,200 ft) of 3.66m (12 ft)diameter tunnel passing mainly through glacial deposits with a water head of up to 2 bar. The project involves many new innovations, including: Slurry wall work shaft with excavation below the water table; Hybrid universal rings combining traditional steel reinforcement with fibers; New, full EPB Lovat TBM; Two component grout system pumped to the TBM from the surface; and, Linabond corrosion protection liner. The paper looks at the planning approach adopted to meet the various challenges presented, combined with an overview of progress to date.

Jan 1, 2007

By D. Gu

Shaft drilling is one of the most useful methods of driving shafts. This paper describes the application and development of the technique in coal mine construction in China.

Jan 1, 1993

By David A. Hill, James R. Wait

This report contains a summary of analytical research on electromagnetic methods of nondestructive testing of cylindrical conductors. The principal objective is to provide theoretical insight to the operation of electromagnetic sensing of the internal properties of wire ropes that are used extensively in mine hoists. An overall review of past work is also included.

Auger operations produced 14 million tons of coal in 1974, or approximately 5% of all surface mined coal. It was the most efficient of all coal mining methods, producing 40.0 tons per man-day. Exhibit 1.1 gives a breakdown of productivity of all coal mining methods. Exhibit 161 PRODUCTIVITY OF COAL MINING METHODS (Short tons per man-day) [Method - 1971 1972 1973 1974 Conventional 11.00 10.00 9.75 9.30 Continuous 13.00 12.50 12.25 11.90 Strip Mines 35.69 35.95 36.00 36.00 Auger Mines 39.00 43.00 45.33 40.00 ] Unlike other surface mining methods, augering produces clean coal, largely uncontaminated by foreign materials, other than those existing in the coal seam itself. However, compared to other methods, the coal recovery rate is relatively low. For example, a triple-headed auger in a 35-inch seam would recover approximately 50% of the coal in the seam as compared to a 90 to 95% recovery rate for strip mining and a 55 to 65% recovery rate for deep-mining. The low auger recovery rate is due to the circular cuts and pillars left in the seam.

Jan 1, 1975

The Golden Cross Mine will be the first underground gold mine in New Zealand to operate since 1952. The development plans, along with the conditions and circumstances presently found in the now ongoing mine development, will be discussed as well as a brief review of planned stoping activity and stoping results to date.

Jan 1, 1991

By P J. Terbrugge, O K. H Steffen

Open pit slope design has conventionally been effected as a bottom up function utilising available geotechnical information. This results in a decision criterion based on Probability of Failure and Factor of Safety with a risk assessment being carried out on the proposed design slopes. The design approach recommended reverses the process using fault event tree decision methodology. The consequences of this approach are that acceptable risk criteria have to be determined by mine owners. Slopes are then designed by the technical staff to achieve these corporate goals. Benefits that arise from the process are that the owners take a proactive decision on the risk benefit relationship allowing the technical staff to optimise the geotechnical exploration programme and design.

Jan 1, 2006

By Orlando Bernal

El presente texto aborda el aspecto termodinámico del sistema de lixiviación -en tanto predice los fenómenos que ocurren en el interior de la pila para luego continuar con el análisis del mecanismo cinético. La metodología aplicada en cuanto a los mecanismos de lixiviación, difiere de otros trabajos porque aquí se considera los tres mecanismos por separado (óxidos, sulfuros secundarios y primarios) basados en el análisis secuencial del cobre. Asímismo la cinética per se obedece las leyes de la termodinámica ergo, cuyo aspecto no puede ser ignorado en un análisis global. En este sentido, se presenta el modelo de desarrollo matemático como una herramienta óptima que controla y predice este proceso del lixiviación por medio de la simulación utilizando la ecuación de continuidad, la cual supone flujo tipo pistón de la fase líquida en el interior de la pila.

Sep 9, 2007

By Ray Hutton, Darrell Liebno, Taro Nonaka

Background Population growth and increasingly stringent regulatory controls on water quality across North America have resulted in municipal governments investing heavily in infrastructure to control what are known as Combined Sewer Overflows (CSOs).These are events which occur when combined sewers exceed their conveyance capacity during periods of heavy rainfall or snowmelt. The city of Atlanta, Georgia is one such municipality; with a population of over450,000 within city limits and a sewer system servicing 1.2 million including adjacent jurisdictions, the City of Atlanta has a Combined Sewer System (CSS) encompassing approximately 15% of its total 3,540 km (2,200 miles) of sewers. Atlanta’s CSO discharges to local watercourses began to draw fire from environmental groups in the1980s. As a result, in the early 1990s, the City constructed a series of CSO control facilities which provided screening and chlorination at seven CSO discharge points across the CSS watershed. Unfortunately, these facilities were not capable of handling all of the overflows generated due to heavy storm events; frequently, untreated water was bypassed around the treatment facilities. The federal Environmental Protection Agency (EPA) deemed that water quality standards were being violated by these discharges, and a suit was brought against the City to force a higher standard of compliance. As a result, the City entered into a federal Consent Decree which would bring CSOs into compliance with federal standards by 2007. A critical component of this plan was the design and construction of the West Area CSO Tunnels and Pumping Station. In February 2003 the City’s Department of Watershed Management retained the services of Jordan Jones & Goulding/Hatch Mott MacDonald/Delon Hampton Associates (JDH Joint Venture) to design and provide construction management ser-vices for the project, which was designed to capture combined sewage from three of the City’s existing CSO facilities on the northern end of the CSS watershed. The design consisted of two connected tunnels which would convey the wastewater originating from the North Avenue, Clear Creek, and Tanyard Creek CSO facilities to a submersible wet well pumping station located at the R.M. Clayton Water Reclamation Center (WRC). Since the majority of the effluent stream consisted of storm water, the City elected to design and construct a separate treatment plant. This plant was designed under a separate contract, and is currently under construction.

Jan 1, 2007