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By V. E. Ross

A model has been developed that describes the behavior of mineral particles and water in the cleaning zone of flotation columns. The possible detachment of particles from their sites of attachment at the bubble surfaces is related to the flux of bubble surface area with increasing distance from the interface between the collection and cleaning zones and the late at which floated particles are transported into the cleaning zone. The drainage velocities of floated and entrained particles are calculated from the drainage velocity of water and the properties of the particles. The effects of wash water and inhibited drainage in the froth are also explicitly accounted for.

Jan 1, 1988

In engineering applications of explosives for rock breaking, the released energy is expended mainly into heat, rock crushing and fracturing, seismic waves, air blast, and noise. Those parts of energy which pass into seismic waves and air wave create environmental problems since they are transmitted away from the blast site. In order to predict the environmental effects accurately, one must be able to predict the energy distribution at the source. The energy distribution at the source is significantly controlled by the blast constriction. Consequently, the accuracy of prediction and control of ground vibrations generated by blasting is affected by various matrices of blasting constriction.

Jan 1, 1986

By Gary L. Mowrey, William D. Monaghan, George F. Persetic, Gregory M. Molinda

Ground penetrating radar (GPR) has been investigated by the U.S. Bureau of Mines Pittsburgh Research Center for its potential to determine rod hazards in underground mines. GPR surveys were conducted at four field sites with accompanying ground truth to determine the value of GPR for roof hazard detection. The resolution of the current systems allows detection of gross roof fractures (>6A mm (>0.25 in) zone) or rider beds in coal measure roof. Data quality is not yet sufficient to detect small bed separations or subtle lithologics changes in the roof. Differences in data quality are discussed, as well as suggestion for collecting improved data.

Jan 1, 1996

By James A. Soles

Concrete is a complex, multicomponent mass whose stability is dependent on three principal variables: quality of the mix, its composition, and environment of the site. The aggregate is only one component, but its constituent minerals may react in unfavorable regimes and, given sufficient time, destroy the concrete. Therefore, besides ensuring that a concrete will meet the strength requirements of a structure, the concrete engineer must be confident that the mortar and aggregates will resist destructive processes. This paper reviews the principal causes and effects of aggregate instability, notes reactions of certain phases, and suggests precautionary measures that can be taken to extend the useful life of concrete structures.

Jan 1, 1984

By Jerome S. Nelson, William S. Johnson

Seismic investigations at pre-construction sites commonly are limited to obtaining velocities and thicknesses of subsurface intervals which are useful in estimating construction costs, but are sometimes difficult to apply to project designing. This paper shows through a case history of the San Bernardino Tunnel Intake Tower, a part of the California State Water Project, that dynamic rock properties and dynamic resonant frequencies can be determined and velocity models constructed from in situ field studies and that these are theoretically correct after simplifying assumptions are made. These data can be used to confirm and extend information obtained by conventional methods such as drilling and laboratory static testing.

Jan 1, 1971

By J. M. Scharer, Bruce E. Halbert, Lysane Bouduc, Douglas B. Chambers, Jennifer L. Kirkaldy, Carol M. Pettit

Io contrast to acid mine drainage (AMD), neutral mine drainage (NMD) has not yet received widespread attention. Metal and sulphate concentrations can be elevated and of concern in neutral drainage from waste rock and tailings. In the present paper, metal release in high ionic strength mine drainage at neutral pH is evaluated at several mine sites. Specific factors including oxidation rates, buffering capacity, and hydrology are also addressed and their effect on the production of contaminated NMD from mine wastes is evaluated. Case studies are presented involving current seepage water quality and predictive geochemical modelling to illustrate the possible time frame and magnitude of the contamination.

Jan 1, 2000

By James W. Baxter

Underground mining of limestone is becoming increasingly practicable in Illinois. Most quarries are near rivers on the western and southern borders where competition for land use is intensive. Increasing demands for stone can be met by expanded mining with access by adits in existing quarries and by inclines and shafts at downdip sites. Geologic, hydrologic, and engineering conditions indicate that deep mines in the Ste. Genevieve, Salem, Ullin, and basal Burlington limestones of Mississippian age and in the Moredock member of the Dunleith formation of Ordovician age are particularly feasible, but development will require prudent exploration and planning to ensure that the product will be of good quality.

Jan 1, 1981

This paper discusses considerations to be made for the selection of rock tunnelling machines, as opposed to drilling and blasting. A systematic approach is presented in terms of utilizing data frcm site investigations to accurately forecast machine performance for estimating and planning purposes and to help minimise associated risks. Useful rock index properties are identified, and correlations for predicting advance rates for roadheader and full face machines are presented together with a simple method of characteristing rock mass conditions for estimating machine utilization and the savings to be gained in support costs. Finally considerations for tunnelling in adverse ground, for advance probing and for large sized tunnels are outlined.

Jan 1, 1987

By McAuley T. J

Computer software is an integral part of mining operations today with many sites using six or more software packages on a daily basis. However, the use of these different programs generates the need for substantial staff training. The current trend toward large integrated packages to solve this problem is counter-productive because the relatively small companies producing specialised mining software do not have the resources to develop quality software with all the required features. Software standards are being proposed by various parties but recent history indicates these will be unsuccessful. An alternative approach is suggested using the various standards which have been developed for the Windows operating system.

Jan 1, 1995

By Cindi Byrns, Andy Davis, Amy Tisdale

The Robinson district, Ely, Nevada is a hydrogeologically complex system with several distinguishable geologic blocks, each with a distinct background groundwater chemistry. To discriminate between background and mine-impacted groundwater, background wells, monitoring wells, pit lakes, waste rock seeps, and surface water samples were analyzed for a suite of major cations and anions, together with trace and precious metals, rare earth elements, 2H-deuterium and 18O/16O. The data allowed identification of groundwater flow paths, verification of hydrochemical source areas and characterization of natural attenuation mechanisms (e.g., mixing, dilution and mineral precipitation) that control the concentration and migration of metals at the site.

Jan 1, 2000

The Argyle Diamond Mine came on stream late in 1985 as the world's largest diamond producer in terms of carat output. The design of the process plant, including the heavy medium separation (HMS) facility which provides the initial stages for separation of diamonds from gangue, evolved over a lengthy period of feasibility study and site investigation into the final form described in this paper. The commissioning was carefully planned and co-ordinated, and culminated successfully with handover of the plant on schedule and within budget. Problems encountered during .within were minimal and since then the plant has achieved greater than design throughput during its first year of operation. Darvr_ontmn

Jan 1, 1987

Rapidly identify unstable mine waste embankments and similar dam structures. Approach Aerial photography, geotechnical instrumentation, and telephone or satellite data transmission are used to supplement walk-around inspect ions. How It Works Embankment stability and other indicators of structural integrity are evaluated using aerial photography, and on-site unattended instruments and data transmitting systems. Evidence of external movement and water seepage is obtained from aerial photography and photogrammetric evaluation techniques. Surface points marked by stake- mounted targets are monitored photographically at time intervals of several weeks or months. Photographic measurements of x, y, and z coordinates of these points are obtained from flying a series of photo-runs over the dam.

Jan 1, 1979

By Ralph P. Hackl

The Congress gold property, located near Goldbridge, B.C., is extremely refractory with most of the gold disseminated in fine- grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225 cubic meter commercial size bioleach reactor was built and tested at the mine site in 1989. At that time the tank was the largest bioleach reactor ever operated. This paper discusses our experiences in operating the tank, summarizes some of the data obtained and describes the problems encountered.

Jan 1, 1990

By Craig R. Smith, Warren Pfefferle

Tests were conducted utilizing large flat jack devices placed in a vertical slot for high pressure loading of rock to measure in-situ properties of a rock mass. The high pressure flat jack devices were used as a site investigation tool to obtain rock mass properties. Tests were conducted before and after a 100 ton surface high explosive detonation test to assess explosive effects on the rock. It was conclusively demonstrated by these tests that meaningful flat jack tests could be successfully accomplished; also, a significantly different response of the rock medium was measured as larger areas of rock were loaded. Surface jointing was severely disturbed by the explosion.

Jan 1, 1971

By Sathit Tandanand

Geological differences among various coalfields restrain the applicability of subsidence prediction using empirical approaches previously developed. The Bureau of Mines assessed data collected from 16 longwall panels in the Northern Appalachian basin. Attention was focused on the effects of rock lithology, excavation width, and panel depth on the subsidence factor. The results show that the subsidence factor can be expressed in terms of the width-to-depth ratio by a simple exponential equation, which has a coefficient tentatively considered as the subsidence index. This index varies with the lithology of a particular site, and can be expressed in terms of percent distribution of weak and strong rocks in the overburden.

Jan 1, 1982

By Zachary J. Fink

A continuous-monitoring system has been developed for analyses of mine gas concentrations associated with spontaneous combustion, mine fires, and explosive and toxic levels. The analysis center, which is linked to sample locations by polyethylene tubes in bundles, has been successfully field tested by the Federal Bureau of Mines for analyzing carbon monoxide and oxygen; a computational scheme has been developed to process the data at the site. This report contains information on the design, purchase, installation, and maintenance of the tube-bundle system. A brief comparison of the tube-bundle system with the underground-analysis system and plans for future research are also included.

Jan 1, 1975

Since the 1950's drilling has been rapidly mechanised. First from hand held drills with air legs to pneumatic jumbos, then to more effective hydraulic jumbos. Development of underground drilling equipment naturally could not have stopped here. Hydraulic drilling saw an improvement in drilling capacity and efficiency after the introduction of second generation drifters in the early 1980's. Also in the early 1980's a few equipment suppliers started to study how to improve the efficiency in operating the rigs. The first computerised rigs for tunnelling were delivered to work sites in mid 1980's. At the same time a few computerised longhole drills started drilling in mines.

Jan 1, 1988

By A. E. Reisenauer, R. W. Nelson, G. W. Gee

A model assessment was made to evaluate contaminant transport to ground water from clay-lined and unlined tailings pits. The input hydrologic soil characteristics were measured on materials typical of those found at the Morton Ranch uranium mill site in central Wyoming. The assessment involved combined saturated and partially saturated flow and contaminant transport models for two-dimensional cross-sections typical of the proposed Morton Ranch burial pits. Specifically obtained from the models were contaminant flow paths, the advancing contaminant flow fronts for sorbed and non-sorbed constituents, and travel times of contaminants along flow paths. Such results enable evaluation of the environmental consequences for the alternative control methods.

Jan 1, 1980

By S. Chander

A review of the published literature on the mechanism of depression of sulfide minerals shows that a unified theory is not yet available. Various mechanisms that have been postulated include competition between depressants and collectors to adsorb at the surface sites, creation of thermodynamic conditions nonconducive for formation of a metal collector salt, or formation of a hydrophilic coating on the surface. The hydrophilic coating may or may not effect the adsorption of collectors. In another mechanism, the depressant may participate directly in oxidation/reduction reactions between collectors and sulfide minerals. Examples from the literature highlight oxidation/reduction effects in the depression of sulfide minerals.

Jan 1, 1986

By Matthew K. Coy, Paul N. Worsey

The work described in this paper comprised the master’s thesis work of the primary author and was conducted at the Missouri S&T experimental mine. The objective was to determine if rubber tractor treads could be used as an alternative material for blasting mats. These treads are made from steel cable and vulcanized rubber and are very tough. However, once they reach the end of their life on mobile equipment, they are destined for a landfill, or dump site, because they are too tough to recycle. A potential alternative use for them is as blasting mats. Several discarded treads were obtained from Kolb Grading in St. Louis.

Jan 1, 2015