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By M. England

A method for the analysis and prediction of single pile displacement behaviour is described. It is the displacement in time, under constant load, based on the use of hyperbolic functions to characterise individual constituents of the displacement-time behaviour. Extensive use of this technique has confirmed its validity in a variety of soils and that consolidation and creep settlement appear to be indistinguishable. The algorithms employed are suitable to model the displacement behaviour from the onset of load to infinite time for all types of piles and surface foundations. Until the advent of computer controlled static load testing, analysis of the displacement-time characteristic during pile load tests has been hindered by the quality of the data recorded and inconsistency of loading. This has hitherto made the development of suitable behavioural models very difficult. Understanding the soil deformation within a proper time framework allows the subject of pile instrumentation and testing to be developed. The equipment required is basically a computer controlled loading and pile head displacement measuring system which allows accurate analysis of the settlement characteristic in almost every situation.

Jan 1, 1993

By W. M. Cross

The hydrophobic character of sapphire surfaces in SDS solutions was examined with respect to the aggregative nature of the adsorbed surfactant phase. It was found that, at equilibrium, sapphire surfaces having adsorbed SDS bi-layers exhibited no contact angle. Conversely, when the adsorbed SDS was found to be mi-cellar in nature, sapphire surfaces developed significant hydrophobic character. The surface states as detected by Fr -IRIIRS conformational analysis were found to be reversible with temperature. The variation in adsorption density with temperature was studied by in situ Fr-IRIIRS. The isosteric heat of adsorption was calculated to be -1.6 kcal/mole. Although the adsorbed SDS was found to undergo a reversible phase change between 25 and 32°C, similar to SDS in solution, the extent of adsorption was not reversible with temperature.

Jan 1, 1993

By Gonzalez-Dominguez J. A, Dreisinger D. B

At Cominco's Zinc Refinery at Trail, British Columbia impurities are removed from zinc sulphate electrolyte by a two-stage purification process using zinc dust. Copper, cadmium and thallium are removed in the first stage whereas cobalt is removed in the second stage. Cobalt removal kinetics are affected by soluble antimony and copper additions to the electrolyte. This study was focused on the kinetics of cobalt removal by zinc powder cementation. Experimental variables included copper and antimony concentrations, pH and temperature. Common organic additives employed in zinc plants were studied to determine potential interactions with the cobalt removal process. Cementation products obtained from laboratory experiments and plant practice were studied using SEM. A number of significant results were obtained: 1. Copper and antimony ions were sustantially removed from solution during the early stages of the cementation reaction (within the first 15 minutes). Cobalt cementation kinetics are slow and follow a first order kinetic regime. 2. A drop in the cobalt removal rates can be correlated with a rise in the Eh of the slurry. 3. Ligninsulphonate, Percol 351 and animal glue at levels of 2 mg/L significantly impede cobalt cementation.

Jan 1, 1993

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the quantitative procedures that have been developed for the mine-specific analyses of accident/injury experience data are presented and their applications are demonstrated in a summary form through case study examples. The quantitative procedures will aid mine safety management personnel to develop focused accident prevention strategies including training, as well as to justify the investment in such proactive programs through cost-benefit analyses.

Jan 1, 1993

Mining software systems have provided a basis for integration of resource, survey, and design functions. They can similarly provide a basis for incorporating ground conditions into the process.Exploration and mine geologists have a prime role to play in this process, extending their responsibilities further across the geological spectrum, into exploration of ground conditions, analyses of results, and assessments of their implications for mining. Ground conditions are as much a part of the geology of a prospect or mine as its mineralisation, and can have critical imnlicationa for mining.

Jan 1, 1993

By Richard C. Travis, Edward C. Dowling

A detailed kinetic study of the flotation installation at the Metcalf Concentrator revealed a rougher flotation circuit operating under less than optimal conditions. Based on these results, a project was initiated to approximately double the rougher flotation capacity by increasing the installed volume from 780 cubic meters to 1,560 cubic meters. This project, which was completed in early 1991, replaced the existing cells with larger capacity cells. A comprehensive analysis of results demonstrates significant metallurgical benefits. INTRODUCTION/BACKGROUND The Metcalf Concentrator is located in Morenci, Arizona and is part of Phelps Dodge Morenci, Incorporated. Sumitomo Metal Mining of Arizona is a minority partner in the operation with 15% interest. The Metcalf Concentrator is the newer and smaller concentrator and operates in conjunction with the Morenci Concentrator. Operating capacity at Metcalf is currently 48,000 TPD of ore on a 365 days per year basis. The Metcalf Concentrator was commissioned in 1974 at a 30,000 TPD operating rate for the purpose of treating ores originating in the Metcalf Mine. The mine takes its name from the former town of Metcalf which was named for Robert Metcalf who was credited with discovery of the mineral district. The predominant ore mineral is chalcocite which occurs as a secondary enrichment closely associated with iron pyrite. The host rock is largely granodiorite and quartz monzonite. The original rougher flotation circuit consisted of a total of six rows of Wemco 8.5 cu. meter (300 cu.ft.) flotation machines treating pulp from the two grinding sections (Sections A and B). Each row was configured in a 4-4-4 arrangement. Shortly after startup the throughput rate was increased significantly without sustaining a recovery loss. This increase was achieved by raising the target value for the particle size of the cyclone overflow which is the rougher flotation feed. Shortly thereafter, the capacity of the pump and cyclone began to restrict further increases in throughput. After testing, two 66 cm. (26-in.) cyclones and a 12-in. X 12-in. centrifugal pump replaced the original classification equipment. As a result of these modifications, the grinding section could routinely process in excess of 42,000 TPD. Due to the increased tonnage rates, limitations in the rougher flotation circuit performance were observed. In an effort to improve the performance of rougher flotation with this higher throughput, the speed of the flotation mechanisms was increased from 230 RPM to 250 RPM. This change improved the suspension of the coarser feed and induced additional air into the pulp. It did, however, apply additional strain to the motors, shortening their life. At these elevated processing rates, it was found that the dart valves operated almost entirely at the top end of the control range and could not efficiently handle upsets from the grinding section. This was remedied by lowering the end overflow weir and allowing some of the tailings to overflow the end weir. However, in order to obtain acceptable recovery levels, the flotation pulp was maintained at a high level, adversely influencing the rougher concentrate grade.

Jan 1, 1993

By N E. Whitehead

An application to mine an ilmenite-rich sand deposit in Westland led to public concern about potential radioactive hazards should the ore be further processed to recover zircon or monazite. A review recommended that any material involved in the heavy mineral sand industry containing more than 0.05% thorium, uranium or their mixture should be considered a radioactive substance and, for mining purposes, a notifiable product. Safeguards for those occupationally exposed would operate via the Radiation Protection Regulations. The major safety requirement would be the minimisation of dust in certain operations.

Jan 1, 1993

By J. C. Johnson, W. G. Pariseau, D. F. Scott, F. M. Jenkins

In situ stresses are important input data for the design of safe, stable stope layouts and extraction sequences. However, it is commonly assumed that normal and shear stress gradients in a stress field are negligible and, consequently, that stresses are uniform throughout the region of analysis. To evaluate these assumptions and to provide input data for an analysis of a shaft pillar mining plan, in situ stresses were measured at the Homestake Mine, Lead, SD, using overcoring on hollow inclusion cells and borehole deformation gauges. These measurements were used with conventional least squares, best fit data reduction schemes. The results showed that normal stresses within the shaft pillar were less than, but comparable to, those estimated from finite-element modeling. Shear stresses were an order of magnitude less than normal stresses and varied considerably from site to site. Possible causes of this variability include effects of scale, elastic moduli, anisotropy, and axial strain. Because of the variability, it is not possible to determine the magnitude of horizontal stress gradients.

Jan 1, 1993

By M. G. Stamatakis, C. Zagouroglou, C. Helvaci, J. Kanaris

"Abstract -Borate minerals, such as colemanite, ulexite and borax, have been reported in Tertiary continental basins of West Anatolia, Turkey, and Samos Island, Greece.Tuffaceous rocks interbedded with the borates are rich in authigenic silicate minerals such as zeolites, potassium feldspar and opal-CT, all of which have a genetic association with the borates. Chemical analyses of the tuffaceous rocks show variation in major elements due to the varying percentage of carbonaceous, detrital, and volcanic derived material.The volcanic activity in the vicinity of each particular lacustrine basin created ion-rich fluids from which a series of borates were precipitated under arid climate. Additionally, the saline-alkaline character of these fluids was responsible for the diagenesis of the silicic glass of the tuffaceous rocks, altering them to silicates and silica polymorphs."

Jan 1, 1993

By F. T. Paleari

Radial gas holdup profiles have been measured in a 50x400 cm flotation column using a multi-cell conductivity probe. Three different bubble generation systems were examined: up to eight vertical filter cloth spargers, three horizontal filter cloth spargers, and three (horizontal) Cominco-type spargers. The variables tested were: number of spargers, symmetry of their arrangement, and height above spargers. Batch water with up to 20ppm frother concentration was used. The general observation is that the profiles tend to be uniform (i.e. flat) with some exhibiting a slight wavy shape. The vertical sparger arrangement proved the most difficult to achieve profile symmetry. The horizontal spargers gave uniform profiles at right angle to their length but a decreasing gas holdup along their length; the Cominco-type spargers gave slightly less scatter in the data. Switching off selected spargers (to simulate malfunction) did not produce strong asymmetry in the profiles.

Jan 1, 1993

By D. Raghavan

In recent years, the environmental issues related to the landfill shortage received considerable importance. Many polymeric solid wastes have high resistivity to chemical and biological degradation, and options are sought by which these wastes can be recycled and reused, or reduced in volume. The present study investigated the biodegradation of polyethylene by Aspergillus niger, and biodesulfurization of rubber by pure and mixed cultures of Thiobacillus thiooxidans and Thiobacillus ferrooxidans. The fungus, A. niger, was found to metabolize portions of polyethylene. Quantitative calorimetric measurements revealed that the amorphocity of the sample decreased during biodegradation. Removal of sulfur from synthetic rubber samples containing 2 to 15% sulfur, was studied in shake flask experiments and the associated oxygen consumption was studied in Warburg respirometers. The mixed bacterial cultures were more effective in the desulfurization of rubber samples than the pure cultures of T. thiooxidans and T. ferrooxidans. The data obtained in these studies may have far reaching consequence for the development of new effective processes regarding the remediation and management of discarded polymeric packaging wastes and car tire rubber materials.

Jan 1, 1993

By S. Lu

The particle-bubble attachment and the rupture of formed aggregates in flotation cell were investigated in terms of turbulent regime. It was found that the particle-bubble collision rate is closely correlated to the energy barrier between particles and bubbles, and no adhesion takes place for the hydrophilic particle-bubble system due to the introduced ?capture efficiency? f(a) being zero. The values of an especially defined Weber number, i.e. the ratios of turbulent stress to aggregate strength in the inertial subrange of turbulence were estimated, the results showed that the detachment of a particle from a bubble involved in an aggregate is mainly caused by the turbulent stress only in the impeller zone, no bubble splitting occurs both in the impeller zone and in the bulk zone.

Jan 1, 1993

By Michel Jébrak, Claude Bellehumeur

Abstract - Regional and orientation geochemical stream sediment surveys were carried out by the Quebec Department of Energy and Resources in southwestern Quebec, over a part of the Mont­ Laurier Terrane of the Grenville Province. The area contains some small stratiform zinc deposits. The response of Zn mineralization to geochemical surveys is weak; the known mineralization is not defined by anomalous samples and consistent patterns. This study uses a technique that increases the geochemical signature of Zn mineralization in filtering out geochemical background components related to lithologies and surficial conditions. The background variations were modelled using principal component analysis, and the filtering technique consists of the partial reconstruction of the data matrix from results of principal component analysis . The filtering procedure considerably enhances the Zn anomalies located in the catchment basins of Zn deposits, and defines some new anomalies in proximity to the marbles of the Mont-Laurier Terrane, the principal metallotect of Zn mineralization.

Jan 1, 1993

By Behl S

Flocculation behaviour of six different dolomite samples, four from the Florida mining district, one from Perry, South Georgia and another from New Jersey was examined using polyethylene oxide (PEO) as a flocculant. The samples were similar in chemical composition, however the porosity of the samples from the Florida mining district was higher than the others. FT-IR, adsorption and surface modification by leaching revealed that flocculation was directly related to the presence of isolated hydroxyl groups on the surface. The adsorption mechanism was believed to be hydrogen bonding of the ether oxygen of PEO with isolated -OH sites on the solid.

Jan 1, 1993

By L. L. Rethi

The U.S. Bureau of Mines summarized injury data for independent contractor employees working at all locations of coal and metal-nonmetal mines from 1983 through 1990. During the eight years, the greatest contrast in degree of injury between independent contractor and operator employees was in fatalities. From 1983 through 1990, there were 132 independent contractor employee fatalities in the mining industry. In 1988 though, independent contractor employees accounted for nearly one-fourth of all mining fatalities. The fatality incidence rates of independent contractors were consistently higher than those of operators during the eight years. For instance, in 1990, the contractors' rate was twice that of operator employees in coalmining and nearly five times that of operators in metal-nonmetal mining. Three other salient facts highlight the independent contractor employees' fatality injury data during these years. First, 82% of the independent contractor employee fatalities occurred at surface locations. Second, two job classifications?truck driver and equipment operator?represented 37% of the fatalities throughout the 8-year period. And finally, four accident classifications?powered haulage, slips and falls, machinery, and electrical?accounted for 71% of all independent contractor employee fatalities.

Jan 1, 1993

The individual or company director who ignores his or her obligations under the Resource Management Act 1991 and under the proposed hazardous substances legislation, ignores them at their peril. Two recent cases in Canada and the United Kingdom concerning environmental offences under similar legislation illustrate the risks well.

Jan 1, 1993

By G. Le Bel

The paper proposes three methods to determine optimum lifetime of a mining project1. The conclusion is that the three methods arrive at the same optimum production rate (by coincidence). It is also stated that: "The stochastic and option pricing models, in addition to providing a more realistic optimum mine life than the traditional NPV (net present value) calculation, showed that the example project has the potential for substantially higher return. By explicitly considering a project's potential risks, the stochastic or option pricing techniques can more accurately describe its probable investment performance." This discussion is intended to demonstrate that: • It is no coincidence that the three methods arrive at the same optimum production rate. • The stochastic and option pricing models do not provide a more realistic optimum mine life than the traditional NPV calculation. • The potential for a substantially higher return is misrepresented. First, a review of investment decision theory in mining is needed. Net present value is the preferred performance measure because of the flexibility offered when comparing various alternatives. However, it presents the following disadvantages: • The discount rate selection is not straightforward. • The NPV obtained represents a deterministic characterization of the variables included in the cash flow calculations, i.e. a single-point estimate.

Jan 1, 1993

By John E. Shively, Tracy K. Lundin, Francis Fong

The Superconducting Super Collider (SSC) features two 20 TeV counter rotating proton beams which will be housed in 87 km (54 miles) of tunnel. Four additional lower energy particle accelerators will be housed in 26 km (16 miles) of tunnel and underground structures. Physics experiments will be conducted in two underground detector halls approximately 67 m (220 feet) deep with footprints measuring about 30 m (100 feet) by 100 m (330 feet). Definition and design of underground facilities is advanced with construction of approximately one-third of the SSC program underway. This paper presents an overview and status of the SSC project.

Jan 1, 1993

By Mary E. Cocklan-Vendl

Regulatory processes associated with development of major mining operations in Alaska and British columbia were evaluated using specific case studies. Included were one hard rock mine in Alaska (Red Dog Mine), one hard rock mine In British Columbia (Snip Mine), and one offshore gold dredging project in Alaska (WestGold SIMA). Based on a comparison of the three case studies, it became clear that the primary incentives for cost effective permitting are: 1) early and continuing coordination of proposed project plans, designs and schedules with key regulatory agencies and local area residents and 2) development of a sufficient level of baseline information on air quality, water quality, wetlands, endangered species, fish and wildlife, and socia-cultural conditions to support the required permit application. The U.S. permitting process worked in much the same way as the Canadian permitting process. Disincentives of mine permitting include high initial costs for baseline data gathering. However, a relatively high early investment resulted in more efficient permit acquisition and reduced long-term monitoring requirements. A common problem Identified was the inadequate supply of trained agency personnel with the requisite technical and permitting experience. This sometimes resulted in poor decisions and unnecessary changes in project plans and schedules.

Jan 1, 1993

By H. Y. Sohn

The ignition and combustion of chalcopyrite particles under suspension-smelting conditions, in which the particle-particle interaction is neglected, has been analyzed by considering the intrinsic kinetics of oxidation and heat and mass transfer between the particle and its surroundings. Reasonable agreement has been obtained between the calculated results and experimental results from a laminar-flow furnace reported in the literature. This computation- al procedure has further been applied to flash-smelting conditions. Under suspension-smelting conditions (Sh = Nu = 2), chalcopyrite particles ignite at around 960 K. The effects of various parameters, such as oxygen concentration, particle size, and gas temperature, have also been evaluated. Comparison between calculated results in this work and experimental observations indicates that SO is the important gaseous product that forms at the surface of the particle.

Jan 1, 1993