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By P. Pages, J. Lombard, F. Fagnant, G. Bresson

This study is devoted to the improvement of the decision-making process in occupational protection of uranium miners in France. Its purpose is to apply the principles which are recommended by the I.C.R.P. in the field of radiation hazards. These principles, which have introduced the notion of "optimization" in standard setting, suggest the importance of applying cost-benefit and cost-effectiveness analysis to this sector. The objectives here are twofold : to evaluate the present organization of radiation protection on the basis of a simulation model of polluted air flow in the mine (due to the decay of a radioactive gas, radon) and to develop cost-effectiveness analysis of the various radiation protection policies.

Jan 1, 1981

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 9 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY; PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2;1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AROUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11;1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS 0F THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION.

Jan 1, 1977

By Mikael Ramström

In 2002 Atlas Copco Rock Drills AB released the new RCS technology for all of its drill rig types. RCS opened the way for a new generation of computerized drill rigs based on modern, standard PC-computer technology. Drilling accuracy, information logging and reduction in manpower in some types and serviceability, have all taken a quantum leap forward when compared with previous generations of drill rigs. The RCS (Rig Control System) is modularised and distributed is accomplished by means of CAN-bus technology. This technology, which is well proven in automobile applications, forms the communication backbone of the rig. The modularity facilitates almost unlimited possibilities for the expansion and adaptation of drill rig functions.

May 1, 2003

By W. W. Roepke, B. D. Hanson

A major problem facing the coal mining industry today is the need to meet more stringent dust standards due to quartz. When secondary suppress ion is not adequate, the time-consuming and costly cut-and-try method of modifying the mining machine is used in the hope that it will reduce dust generation. The Coal Cutting Technology Group, at the Bureau of Mines' Twin Cities Research Center, has developed an inter-active computer program for drum- type cutting systems to help identify, in advance, modifications that offer the best potential for reducing dust. The program, Relative Dustiness Indicator (REDI), evaluates machine dimensions, seam characteristics, and operator-controllable variables for dust generaton, energy, forces, and product ion.

Jan 1, 1986

By S. Kurama

Incorporation of de-watering sieve waste of borax (TSW) from Etibor Kirka Borax Company (Turkey) on the mechanical and physical properties of a commercial floor tile composition was investigated. In order to achieve this aim, TSW was partially employed in place of feldspar in the standard composition up to 20 wt %. The formulated compositions were wet milled, dried, shaped and then fired at 1190C for a total firing time of 38 minutes (from cold to cold) under industrial conditions. It was found that using of TSW up to 15 wt % improved the physical and mechanical properties of final product. The results indicated a good prospect for TSW as a co-flux in floor tile formulations.

Jan 1, 2006

By Hill McDonald

Sand and gravel deposits may be explored by many different methods. The methods used by The Standard Slag Company are primarily two in nature. One is using an auger which is limited in depth by various soil conditions. The other is a heavy wall dry sampler and a heavy wall wet sampler. The heavy wall dry sampler takes continuous uncontaminated samples up to seven inches in diameter. The heavy wall wet sampler takes continuous uncontaminated samples up to six inches in diameter. For us, the maximum depth of the heavy wall samplers has been two hundred fifty feet of which one hundred feet was above the water table and one hundred fifty feet was below the water table.

Jan 1, 1972

By John J. Elango

Strain gage load cells, the most widely used type of nonmechanical weight sensor, are capable of taking measurements between 0.45-4.5 million kg (1-1 million lb) with an accuracy of 0.05%. They are available in a wide range of standard capacities, configurations, and accuracies, and special load cells may be custom-manufactured to meet unusual requirements. Typical applications include automated batch processing, process monitoring and control, mixing of powders and liquids, weighing coal or other materials in silos, and in large platform systems that weigh trucks and railcars. Because the strain gage load cell produces an electrical signal proportional to the applied load, it readily interfaces with readouts, keyboards, computer terminals, and alarm systems.

Jan 6, 1979

The low grade Mount Charlotte orebody was first mined with minimum capital expenditure by mechanised cut and fill stoping. The lower block was prepared simultaneously for open stoping by shaft sinking and installing another crusher and services. Similar development for the third block was discouraged by economic factors and reduced tonnage. Decline develop- ment required less capital and opened up ore reserves commensurate with advance, providing flexibility to stop operations without commit- ment: A 1 in 7 decline measuring 4.25m x 5.5m to accommodate standard Euclid 25 tonne dump trucks was developed south of the orebody. A fleet of four trucks average 12 loads each per shift over a haul distance of 700m.

Jan 1, 1973

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 11 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY, PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2, 1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AFCUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11, 1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS OF THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION.

Jan 1, 1977

By Michael J. Pyrcz, Clayton V. Deutsch

Strategic project decisions are based on the distributions global variables, for example, total mineable resource, or recoverable oil volume. These global variables distributions are very sensitive to the input one point statistic, that is, histogram and rock type proportions. Representivity in the one point statistic retains significance in all spatial models. Spatial sampling bias and nonrepresentative sampling complicate this process of building representative one point statistics. This work outlines the cause of bias, the inability of standard declustering to correct for this bias and two methods for correcting bias in the one point statistics: "trend modeling for debiasing" and "debiasing by qualitative data". An example is presented of each technique based on a poly metallic data set.

Jan 1, 2002

By Hodkinson I, Slight M

Over the last five years Mt Leyshon has matured into a sizeable gold mine by Australian Standards. In the later part of 1990, after commissioning of the 3.5 mtpa CIP Plant upgrade, experience indicated there was potentially additional Mill capacity beyond that being utilised at the 3.5 mtpa rate. Overall throughput was limited by crushing plant performance and high operating costs resulting from the age and condition of the main crushing plant.In addition, mining was being carried out using a mining contractor who utilised relatively small, high cost mining equipment, and on-going exploration success was also indicating that the then current mine plan would result in only a portion of the available resource being exploited.

Jan 1, 1992

By P. I. Brooker

The semi-variogram, the basic tool of geostatistical estimation procedures, must itself be estimated from the available data. From a numerically simulated two-dimensional deposit, with known variability expressed through its semi-variogram, the standard arithmetic mean estimator is used to calculate experimental semi-variograms. These are determined on a series of data sets obtained from the deposit with various sampling grids that cover different areas of the deposit and have a mite range in the number of available data. The orders of discrepancies between estimated and theoretical semi-variograms are determined in this idealized situation; and this provides a basis against which to assess experimental semi-variograms made on field data.

Jan 1, 1984

A simple and rapid method for delennining gold and silver in carbon samples is described. The method involves dissolution of carbon ash in a strong oxidising medium of aqua regia and hydrofluoric acid. Gold and silver are determined in the resultant solution using atomic absorption speetrometry (AAS). The method is efficient and reproducible. Gold results are comparable to the standard fire assay results, with agreement of results within ± 5 per cent. The co-efficients of variation for gold and silver are 0.37 and 0.39 per cent respectively for six replicate analyses. The analysis of gold and silver in a batch of ten carbon samples can be completed in approximately four hours.

Jan 1, 1992

By Frank Clowes

This lamp has been devised to burn oil from a flat wick in the usual way for lighting-purposes ; and also to burn a hydrogen-flame of standard size instead of the oil-flame, when delicate and accurate gas-testing is to be carried out. The change from the oil-flame to the hydrogen-flame, and vice versa, can be made with great rapidity, and without opening the lamp or running any risk in the presence of gas. The oil-flame serves for illumination; and when the wick is drawn down by the " pricker," so as to abolish the light, the pale blue reduced oil-flame serves to detect fire-damp or "gas," in any propor

Jan 1, 1894

By Gregg PEH, Horne D, Bolan N, Stewart RB

The Tui mine site is situated on the NW flank of Mt. Te Aroha, at approximately 400 m altitude. During underground mining operations two lead-copper-zinc ore bodies were exploited and processed on site. The legacy of the mining operation is a barren dam containing over 100,000 m3 of sulphide-rich tailings. The Tui mine site is arguably the worst case of environmental degradation resulting from past mining activity in New Zealand. Although the impacted area (approximately 4 ha) is extremely small by international standards, acid mine drainage (AMD) emanating from the abandoned tailings dam and mine adits has severely contaminated local streams and prevented natural plant recolonisation of the site for more than 20 years.

Jan 1, 1995

By Just J, Nguyen G, Dunn J. G, Graham J

A sample of pyritic gold concentrate was investigated by wet chemical and electron optical techniques. Sub-samples were roasted in a laboratory scale fluidized bed roaster in the temperature range 400-700¦C. The calcine was characterised, and cyanide-leached using a standard bottle rolling test. Gold extraction efficiencies varied with roasting temperature. At temperatures of 400 and 450¦C gold ex- tractions of less than 40% were achieved, but between 500-700¦C the extraction had increased to 93--98Z. The surface area of the calcine varied with roasting temperature, reaching a maximum at 500¦C. There was no correlation between the surface area of the calcine and the efficiency of gold extraction.

Jan 1, 1987

By W. J. Birch, R. Farnfield

All shock-tube based initiation systems have a time lag relating to the propagation velocity of the shock-tube itself. This paper examines the exploitation of this inherent time lag to achieve delay blasting with accuracies approaching that achievable with electronic systems albeit over a much shorter delay range. The system employed consists of a combination of standard shock-tube, plain detonators and various shock-tube branching components. The accuracy of the complete system depends on the scatter in delay time induced by each component. In order to quantify this scatter a series of trials were undertaken to determine the variability for each component. These trials are described along with a detail statistical summary of the data recorded.

Jan 1, 2009

By Peter Forschner

Classical Mixing Theory is based on applying many fundamental correlations to standard baffled dished bottomed vertical cylindrical vessels with high degrees of symmetry. Horizontal autoclaves operating at elevated temperatures and pressures have been used for more than two decades. All compartments and especially the first and last compartments are asymmetrical. To date no comparison of the effects of the asymmetric geometry on mixing system design and scale-up has been published. The results of investigating solids suspension, mixing time, momentum transfer from the impeller to feed slurry and feed inlet location in the first autoclave compartment are presented as influences on residence time distribution. CFD modeling was developed and verified with the test apparatus.

Jan 1, 2003

By C. N. Kravig

STANDARD raises at Homestake are 150 ft long. Raises of more than 150 ft, driven with the use of a cage and hoist, are considered long raises- some have been driven more than 900 ft. Long raises have eliminated the need for access drifts on each level when transfer and ventilation raises are driven. These timbered cage raises, 7x9 ft in cross section, include a rock compartment and a combination cage, pipe, and manway compartment. To prevent excessive weight on the timbers, 10x10-in. bearing beams are cemented into hitches cut in the rock at 150-ft intervals. The beams also hold back timber movement caused by daily drawing of rock through the rock compartment.

Jan 6, 1957

By V. W. Skema, M. W. Smith

Pennsylvania has 4,000 km (2,500 miles) of streams that do not meet water-quality standards due to acid mine drainage (AMD), making AMD the greatest cause of water pollution in the state. The problem is mainly caused by abandoned coal mines. To abate AMD, Pennsylvania is using a watershed-based approach that includes remining as a key component of a comprehensive restoration strategy. The Tangascootack Creek Water-shed was targeted for AMD restoration through remining. Geologic mapping and overburden data were analyzed using Earth Vision software to identify areas of coal reserves that could be remined to improve water quality. Incentives are offered to encourage mining in these designated areas.

Jan 1, 2002