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By J V. Lawless

Mineralisation processes in epithermal deposits in the North Island of New Zealand are best illustrated by considering the two most productive deposits: Waihi and the Thames Bonanza Zone (TBZ), which have different mineralogies and ore shoots geometries. These two deposits can be taken as typical of certain styles of epithermal deposits worldwide, and recognition of their differences can be used to develop mineralisation models of predictive value. Waihi, the major economic producer in the Coromandel Volcanic Zone (CVZ), has laterally near-continuous ore shoots over a vertical interval of 600 m which consist of quartz, chalcedony, pyrite, base metal sulphides and electrum. They are found in the foot wall of earlier quartz veins which contain quartz pseudomorphs after platy calcite and adularia. The Thames Bonanza Zone which was the second biggest producer in the CVZ has discrete near-vertical ore shoots over 300 m vertically, which consist of quartz, pyrite, base metal sulphides, electrum and in their upper parts barite, that are enclosed in veins of quartz.   The gold mineralisation in both deposits is considered to be a co-precipitate with pyrite, with that at Waihi produced by prolonged boiling in an upflow of a hydrothermal system. That at the TBZ was produced by mixing a deep water primed for gold deposition by prior limited boiling, with an oxidised condensate of the steam released by the boiling, in an outflow proximal to the system's upflow.

Jan 1, 1997

Particles of a complex nickel sulphide concentrate (containing pyrite, pyrrhotite, pentIandite, and violarite as the major mineralogical constituents) were entrained in a stream of hot gas the temperature of which was varied from 500 to -1000°C. Chemical analysis of the particulates collected from the furnace was used to detect the rapid change in sulphur content which accompanied the ignition temperature jump. X-ray diffraction analysis was used to characterize the oxidized material.These techniques showed that ignition was dependent on the mineralogical composition and occurred over the temperature range 500-900°C. Pyrite ignited first in the range 500-600°C; pyrrhotite was the least reactivemineral and required temperatures in excess of 800°C for ignition. The nickel minerals <pentIandite and violarite decomposed before ignition and ignited at temperatures intermediate to those required for the pyrite and pyrrhotite. The ignition temperature for the pyrite was found to be independent of particle size and concentration of oxygen in the atmosphere.Ignition temperatures determined by the simulated flash smelting method were compared with the results of differential thermal analysis (DTA) measurements performed on the same concentrate. Temperaturesdetermined in the DTA test as corresponding to the start of exothermic activity were shown to be at least 100°C below those determined by the simulation test.

Jan 1, 1978

By Peter J. Nicholson

Since the reintroduction of soil mixing to the United States over 10 years ago, the work installed by soil mixing technology has grown dramatically. From an annual turnover of less than ten million dollars per year the volume of soil mixing put in place has grown to an estimated $40 million per year in the year 2000. The majority of work done to date has involved walls, either for excavation support, permanent retaining structures or hydraulic cut-off walls. The other major use for soil mixing has been for mass stabilization of soils whether for isolation of contaminants or for retaining structures. This paper will discuss the uses of and costs of typical soil mix structures. BACKGROUND Soil mixing is defined as the in-situ combining of reagents, typically cement, with native soils, the purpose being to modify or improve the ground. This history of soil mixing covers only the use of cement slurry, aggregated with soil in-situ by mechanical mixing methods only. Soil mixing by use of high-pressure hydraulic means, also known as Jet Grouting, will not be discussed. In addition this will not cover ex-situ (above ground) mixing, or mixing dry reagents with soil. Only mixing applications for building, civil and heavy construction applications will be discussed, with only passing reference made to uses of soil mixing for environmental remediation work.

Jan 1, 2001

By N. S. Yet

This paper shall present the design and construction of bored pile and diaphragm wall for the proposed MHA complex in Singapore. The work was carried out by L&M Foundation Specialist Pte Ltd and PWD Consultants Pte Ltd was the consultant for this project. A brief description of the project is first presented to illustrate the scope and scale of the work involved, which includes the construction of bored piles and diaphragm walls and installation of steel stanchions in the bored piles. This is followed by a description of the methodology used to analyse and design the wall and bored piles. As both towers in this project are supported on bored piled foundation and are constructed by top down construction method, the analysis of the wall has taken into consideration the sequence of work phase by phase and this was carried out by means of a commercial finite element program called CRISP. Modelling of the problem will be briefly described and the findings from the numerical analysis will be presented. This is followed by a description of the structural and geotechnical design aspects of bored piles. The paper shall then describe the difficulties encountered for this project and solution used to solve the problem. The subsoil condition will be described with special mention on the encounter of very strong granitic rock at depth above the maximum excavation level of the basement at certain locations, hence necessitating the drilling of rock for a considerable depth for both bored piles and diaphragm wall. At this juncture, the construction method used to drill through the rock will be briefly described. For construction of bored piles, penetration of rock was carried out by chiselling or drilling using reverse circulation rigs. For construction of diaphragm wall, it requires the employment of Bauer hard rock cutter which uses cutting wheels fitted with roller bits and are capable of excavating into granitic rock of compressive strengths more than 100 MPa.

Jan 1, 2000

The 1981 Review: In the late 1970s there was an upsurge of interest in the prospecting and mining of this countryÆs mineral resources. That upsurge of interest was accompanied by a mounting public concern over the damage mining operations might do to the environment. Concern was also expressed about what some people perceived as inadequacies in the legislation which regulates mining and the grant of mining privileges, and inconsistencies in the relationship of that legislation to other legislation regulating land use and the use of resources.

Jan 1, 1984

By Verne E. Hooker

Near-surface temperature measurements in two granite quarries show that diurnal temperature variations are significant to a depth of 1 or 2 feet, and annual temperature variations are significant to a depth of at least 25 feet. As a result, ground stress anomalies due to temperature exist near the surface, and their magnitude depends upon the time of day and the time of year. Rock stress and corresponding temperature measurements were made in one granite quarry over a rock temperature range of 33° to 81° F. Measured rock temperatures show good agreement with values predicted from one-dimensional heat flow theory. Calculated and measured stress-temperature coefficients for the two granites in this study are given. Thermally induced stress variations in near-surface rocks tested were as large as 1,690 psi from combined daily and seasonal temperature changes.

Jan 1, 1971

By D. B. Lovett

The work described in this report was directed toward identifying and devising methods to minimize the previously observed variability between working level hour exposures and the alpha particle track densities resulting on Track Etch films exposed to mine atmospheres containing radon and radon daughters. The disequilibrium between radon and its daughters was shown to directly affect this Track Etch film calibration factor. The wide range of disequilibrium states possible in mine situations amply explains the variability in the previous tests. A file of published mine atmosphere composition data was compiled and was used, along with atmospheric compositions derived from several theoretical models ref the atmospheric behavior, to evaluate the variability of several dosimeter configurations and concepts. A nonlinear, iterative regression analyse; was formulated that successfully predicted working levels to within 8 to 10% from only the alpha particle activities (Rn, RA, and RaC') data such as are obtainable from Track Etch films over a wide range of disequrlibrium conditions. A model expressing atmospheric concentrations as a function of radon source strength, plate out rate factor, ventilation rate and the fractional re-entry by recoil of previously platted-out daughters was derived and used in the regression program in addition to preparing a set of reference tables and graphs showing the disequilibrium behavior of the atmosphere. Other factors that can affect the Track Etch Film response writ considered and shown to he less crutial than the disequilibrium state. The results of a series of exposures of a dosimeter concept fixture in the Denver Mining Research Center radon chamber air presented and discussed.

Jan 1, 1976

By J. W. Howland

A demonstration of dozer blades, designed for recontouring area-mined spoil and shown effective at Kansas and East Texas surface mine sites, was conducted at a Northeast Arizona surface coal mine to determine their effectiveness in different climate and soil conditions. The specialized tools were: 48-ft angle blade (on side-by-side tractor), 24-ft grading bar, modified 24-ft "U" blade (on side-by-side tractor), and a 13-ft deep "U" blade. Interest in the increased dirt-handling capacity of a previously built 22-ft blade, resulted in the design of a new Centerflow Blade of good versatility, able to maintain increased flow in otherwise difficult-to-move spoil. The demonstration involved 263 acres and showed a reduction of 50% in reclamation costs and 20% in fuel requirements for this mine site over conventional equipment. This savings resulted from improved technology, trained operators, and rigorous application of supervisory and monitoring techniques. Procedures and results of the demonstration are presented and analyzed here, along with guidelines for application of findings.

Jan 1, 1982

By Gloyd M. Wiles

The property of the Park City Consolidated Mines Co. is situated in the northeast part of the Park City dining district 1 mile east of the town of Park City. The elevation at the collar of No. 1 shaft is 7,250 feet. Park City is a town of approximately 4,500 population lying about 30 miles east of Salt Lake City. The two are connected by an oiled State Highway, which is cleared of snow in winter and maintained in first-class con¬dition by the State throughout the year. The district is served by branches of the Denver & Rio Grande Western and Union Pacific Railroads, each operating on a daily' schedule, except Sunday. These two railroads have constructed 1 ½ miles of joint track from the town to the Park City Consolidated Mines Co. loading tipple, located 200 feet from the portal of the adit that leads to No. 1 shaft.

Jan 1, 1936

By S. G. Beattie, N. Mojtabai

A study was carried out which aimed to: determine the effects of blasting on excavation perimeters and nearby slopes; establish a low-cost blast monitoring and field observation programme to determine peak particle velocities and blast damage; and to develop criteria for observable blast damage that are based on the peak particle velocity. Full-scale production blasts in a large open pit copper mine were monitored and studied to develop damage criteria for various rock types. Better blast designs can be achieved by correlating the results of blast monitoring with field observations of damage at the pit walls and on benches. Back-break and damage are related to blast-induced ground vibration. Peak particle velocity is accepted as a reliable measure for the prediction of ground vibration levels. Empirical models for the estimation of rock damage can be developed and used for blast design. The models are used to determine the zones of damage within the rock face. Rock damage models can also be used to design trim shots to achieve further reduction of back-break in more critical areas

Apr 1, 1996

By P. H. Morris

The profile of a delta formed by fine-grained mineral processing wastes, disposed of as aqueous slurries by subaerial deposition from a pipeline, has a significant bearing on the volume that is available for waste and water storage in a given containment structure. Earlier field data and laboratory experiments suggested that mine waste delta profiles could be predicted with high levels of accuracy using data from small-scale laboratory deposition tests. The relationships between the profiles of full-size and laboratory-model deltas were analysed using the principles of kinematic similarity and a recent theory of delta formation based on engineering hydraulics. Measured profiles of full-size and model coal-mine tailings deltas are compared and the prediction of full-size profiles discussed. It is shown that the data-derived laboratory-model deltas are insufficient to allow accurate prediction of full-size delta profiles. Initial slope data or other, equivalent data for the full-size delta are also required

Apr 1, 1996

By David Allen Jones

A depleted county gravel pit was rehabilitated by contracting an artist to convert it into sculpture, rather than using traditional reclamation methods. The sculptor's ideas were generally implemented as designed, but problems arose because of a faulty survey and severe weather. Public reaction was critical. A design symposium was presented by retaining six artists to prepare designs for varied sites. A public forum was offered and video-documented for broadcast. A new art-reclamation project grew out of this project.

Jan 1, 1981

By M. M. Fine

Chalcocite flotation concentrates (26-34 percent Cu and 6-7 percent S) were roasted in air to determine sulfur elimination as a function of temperature, airflow rate, and residence time. Fluosolids roasting was evaluated batchwise and continuously in a 4-inch fluid-bed reactor. Kiln roasting tests were carried out in a 4-inch ID by 6-inch-long rotary drum. Pelletizing the very fine concentrates prior to roasting was essential to minimize dust losses and accretions. Concentrate pellets, sized minus 10 plus 20 mesh and bonded with 2 percent bentonite, were excellent feed for fluosol¬ids roasting and limited dust losses to 10 percent or less. One-fourth-inch pellets were best suited to kiln roasting. Both techniques were capable of producing copper calcines analyzing well under 1 percent residual sulfur when operated at 900° C with average retention times of 3 to 4 hours. Calcined pellets were strong, porous, and readily reducible.

Jan 1, 1970

By Donald R. Corson

The effects of adding varying amounts of type I portland cement to hydraulic backfill are described. Six different fill materials, each with three cement contents, were tested to determine which fill properties have the most significant effect on cemented strength. Two strength prediction equations, based on the physical and mineralogical properties of the fills, were formulated, and these accounted for 96 and 99 percent of the variability of the data. Results of both unconfined compression and triaxial tests of cemented fills are given, and the effects of moist curing and fill densification on the 7-day strength are discussed. Permeability test data are given, and the decreased permeability due to cement content and curing time is shown graphically. A discussion of the limited evaluation of other potential stabilization additives (expansive cement, fly ash, sodium silicate, gypsum, and asphalt) is included in an appendix.

Jan 1, 1970

[This Bureau of Mines report presents results of a survey of underground mining equipment and of two demonstration programs showing the feasibility If quieting; a load-haul-dump (LHD) machine and a personnel vehicle. Typical noise levels are presented for the major machine types used in underground mines, along with estimates of the noise overexposure of miners who operate or work near these machines. General principles of noise control are explained, and the application of these principles is illustrated in the description of modifications made to the LHD machine and the personnel vehicle. The noise control package installed On the persona of vehicle lowered its noise level by 14 dBA after 4 months of operation, and inspection of the LHD machine after 2 1/2 years of operation with the modifications showed its noise level 7 dBA lower than that of the unmodified machine. Noise dosimeter measurements indicated that both machines were in compliance with Federal noise regulations for a typical shift.]

Jan 1, 1980

By L. A. Haas

In this Bureau of Mines investigation, conditions were determined to form an iron sulfide adherent coating with a metallic golden luster on steel upon anaerobic heat treatment with sulfur. The sulfide formation rate was determined in the temperature range of 105° to 500° C with reaction times up to 68 hours. The optimum temperature and time to form an adhering decorative coating on mild steel was in the range of 105° C for about 70 hours to 285° C for 1 hour. The golden coating consisted of an inner layer of pyrrhotite and an outer layer of pyrite. At temperatures higher than about 300° C, the outer layer thickness decreased owing to the decomposition of pyrite to pyrrhotite.. Small quantities (<0.5 wt-pct) of petroleum oil accelerated the sulfide growth rate. The sulfide coating decreased the corrosion rate of steel in a neutral aqueous medium by a factor of two. The dissolution of pyrite in water was dependent on particle size and surface area with the flat pyrite coatings exhibiting the lowest dissolution rate.

Jan 1, 1974

By Christoph Mueller, Grzegorz Tabak

Basing on five years of experience, this paper discusses modern e-drive systems used in underground transport. This covers Energy distribution and cabling principles, inverters and motors as well as auxiliary aggregates. Also an overview of different regimes for battery charging and the energy management and the method of control of the traction are lined out: This means that throttle and brake are not handled separately, but integrated into “longitudinal control” algorithms which assure that a commanded speed is maintained while synchronizing the multi motor systems and taking into account the constraints imposed by e.g. slope grade and battery parameters.

Jun 25, 2023

By G. Huang, S. Vytla

Computational fluid dynamics (CFD) is a continually developing numerical technique by which complex fluid flow problems can be solved on computers. To be able to transfer CFD expertise to analyze and design a face-ventilation system, a comprehensive validation study of current CFD tools against mining-related benchmark experiments is required. In the last four years, such studies, funded by National In¬stitute for Occupational Safety and Health (NIOSH) under Grant #R01 CCR415822, were conducted in the Department of Mining Engineering at the University of Kentucky. A wide array of ventilation schemes and mining configurations were considered. Recently, an additional study was performed in cooperation with the NIOSH Pittsburgh Research Laboratory. This study was dedicated to the methane behavior in the empty (containing no equipment) face area with a blowing curtain and a 10. 7-m (35-ft) setback. In this paper, the authors present and discuss the computer-simulation data and compare them with data collected during the laboratory studies at the NIOSH lab.

By S. Dicarlo

"In late 1985, B-zone ore was first processed through the Eldor Mines mill at Rabbit Lake. Extensive modifications had been completed in order to mill this ore. In-plant process development was initiated to tune up the new circuits and concentrated on leaching, solvent extraction, impurity and uranium precipitation and tailing and effluent treatment. This process development effort and the results are described.INTRODUCTIONEldor Mines, a division of Eldorado Resources Limited, operates the Rabbit lake mine-mill complex at Collins Bay on the western shore of Wollaston Lake in northeastern Saskatchewan.The first orebody was discovered in 1968 by Gulf Minerals Canada Limited below a small body of water named Rabbit Lake. Ore from the Rabbit Lake (RL) deposit was first processed through the new mill in June, 1975, with depletion scheduled over the next ten years. Continued exploration in the area led to the discovery of four orebodies in the vicinity of Collins Bay: A-zone (1971), B-zone (1977), D-zone (1978) and Eagle Point (1980). Collins Bay is about ten kilometres from the mill facility.In 1982, Gulf Minerals was acquired by Eldorado Nuclear Ltd., who continued the development effort to bring the B-zone deposit into production. The RL pit was mined out in May, 1984 with stockpiled ore providing mill feed until startup on B-zone ore, which was scheduled for November, 1985."

Jan 1, 1988

Old Copper Flotation Tailings Waste Reprocessing

Sep 13, 2010