The installation of instruments and devices required to fully automate a laboratory flotation column, and the configuration of the software required to drive the column from a PC terminal was accomplished. Beside the normal Input/Output link required, and as an application, the system was configured to perform stabilizing level control through feedback control loops. Three parallel software control loops were built, manipulating, alternatively, the underflow, feed or washwater streams to control the level. / The level was calculated through the readings of up to three pressure transducers Proportional, Proportional-Integral and Proportional-Integral-Derivative control were used in the feedback loops. In the process, problems related to the accuracy and range of valid level calculation, and to the use of washwater as the manipulated variable were identified. Some changes to current industrial practice are suggested in order to correct these problems.

<p> An ever-present challenge at most active mining operations is controlling blast-induced damage beyond design limits. Implementing more effective wall control during blasting activities requires (1) understanding the damage mechanisms involved and (2) reasonably predicting the extent of blast-induced damage. While a common consensus on blast damage mechanisms in rock exists within the scientific community, there is much work to be done in the area of predicting overbreak. A new method was developed for observing near-field fracturing with a borescope. A field test was conducted in which a confined explosive charge was detonated in a body of competent rhyolite rock. Three instrumented monitoring holes filled with quick-setting cement were positioned in close proximity to the blasthole. Vibration transducers were secured downhole and on the surface to measure near-field vibrations. Clear acrylic tubing was positioned downhole and a borescope was lowered through it to view fractures in the grout. Thin, two-conductor, twisted wires were placed downhole and analyzed using a time-domain reflectometer (TDR) to assess rock displacement. Fracturing in the grout was easily observed with the borescope up to 3.78 m (12.4 ft) from the blasthole, with moderate fracturing visible up to 2.10 m (6.9 ft). Measured peak particle velocities (PPV) at these distances were 310 mm/s (12.2 in./s) and 1,490 mm/s (58.5 in./s), respectively, although no fracturing was observed near the depth of the vibration transducers located 3.78 m (12.4 ft) from the blasthole. TDR readings were difficult to interpret but indicated rock displacement in two of the monitoring holes. Three methods were used to predict the radial extent of tensile damage around the blasthole: a modified Holmberg&ndash;Persson (HP) model, a shockwave transfer (SWT) model, and a dynamic finite element simulation using ANSYS Autodyn^TM. The extent of damage predicted by the HP and SWT models is similar to field measurements when using static material properties of the rock, but is underestimated using dynamic material properties. The Autodyn^TM model significantly overpredicted the region of damage but realistically simulated the zones of crushing and radial cracking. Calibration of material parameters for the Autodyn^TM model would be needed to yield more accurate results.</p>

<p> Attaining an accurate understanding of airflow distribution at the continuous miner face is instrumental in maintaining a safe mining environment. Currently, continuous miner face air readings can be taken in the last open crosscut and at the curtain mouth. By measuring airflow in a pre-determined area it is accepted that an adequate quantity of that air sweeps the face of harmful dust and gasses. Unfortunately, due to the location inaccessibility, precise face velocity readings can only be determined in a laboratory setting or through computer-simulated programs verified by laboratory models. The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) ventilation gallery was used to simulate common ventilation scenarios and measure air velocities utilizing ultrasonic anemometers. The ventilation gallery simulates a full-scale mining face similar to a continuous miner (CM) room and pillar operation and provides a means to obtain representative air velocities in areas typically inaccessible on an actual CM face. Methane gas was also released from pipes located at the face to simulate realistic face gas emissions and dilutions.</p><p> Improving upon previous empty gallery testing and to more effectively determine representative face methane readings, a mockup of a continuous miner with water sprays and a scrubber fan was used to further refine face airflow conditions that would be closer to actual mining conditions. Throughout testing, methane was monitored along the face and at the machine-mounted monitor location allowing direct comparisons of concentrations at these critical locations. Multiple laboratory tests were run, varying parameters such as airflow quantity, entry width (sump or slab cut), and face ventilation configuration (blowing or exhausting curtain). Test data showed a similar pattern of methane concentrations at both low and high airflow quantities, but a difference in the distribution of methane concentrations between narrow and wide entry widths. As verified in previous research, most tests showed that blowing face ventilation was more efficient in diluting methane than exhausting ventilation. The patterns of airflow and methane concentrations observed in this testing can further improve the understanding of airflow in and around the CM and face, promoting effective use of face ventilation to improve the health and safety of miner. </p>

A P&H 2800XP electric mining shovel working in a Western Canadian surface coal mine was instrumented with microprocessor-based monitoring equipment, and its performance monitored as it excavated a series of test blasts. Hoist and crowd motor armature voltages and currents, dipper trajectories, cycle times and load weights were recorded. A diggability index has been established based on the responses of the hoist motor. Values of the diggability index correlated well with digging conditions as observed during monitoring and with muckpile fragmentation size distributions as determined by a photographic survey. This correlation establishes the ability of an instrumented shovel to diagnose the efficiency of ground preparation practices (blasting) by identifying variations in muckpile diggability. The data on dipper trajectory has demonstrated that variations in digging practices do exist amongst an experienced group of shovel operators, and that variation in trajectory significantly influences values of the recorded motor performance parameters. An approach is described to account for variations in digging practice on assessments of diggability. An allied investigation into the ability of time studies to define diggability, revealed dig cycle times to be operator dependant, and unrelated to levels of digging effort.

In recent years the disposal and the treatment of mine waste has been increasingly causing concern to the mining industry. One of the biggest challenges today is acid mine drainage (AMD), which is associated in particular with sulfide bearing tailings. As a consequence of AMD, heavy metals and sulfates are released into the environment. / This project has studied the effect of lime-based treatments in the stabilization of two sulfide tailings, one waste predominately containing pyrite minerals and the second containing pyrrhotite minerals. Different proportions of pozzolans (fly ash and slag) were also added to the lime-tailings mixtures. The physical properties of the mixtures have been evaluated, using several tests such as strength (unconfined compressive strength), permeability and durability. The mineralogical changes in the treated wastes were also examined. The stabilization process and the treatment validity would not be complete without a chemical analysis of the treated waste; therefore a quantitative analysis was performed, including leaching and extraction tests for some elements (Zn, Mg, Ca, and Fe), and also sulfate measurement. The samples were tested after 1 and 28 days of curing time. (Abstract shortened by UMI.)

This thesis discusses approaches to evaluate the health of mining machinery, based on monitored vibration data. The objective was to develop a means to determine machine health, while operating on-line, without reference to an expert. This approach is based on processing acquired vibration data with artificial neural networks (ANN's). A case study, based on data obtained from the monitoring of locomotives at the Iron Ore Company (IOCC). Real time data patterns, profiles and trends, obtained by processing vibration signals from various points on locomotives, were used to test the developed technique. The results indicate that observed patterns and trends can be classified into categories that reliably indicate the mechanical state of the equipment. An implemented system will assist maintenance personnel at this mine to identify the trends of a developing component problem in advance of catastrophic failure. In addition the system will be able to predict its remaining life prior to catastrophic failure. Thus, a machine could be reliably and safely operated until just prior to failure of a component. / The thesis work is a sub-component of a larger project at IOCC, to implement a mine-wide predictive/preventative maintenance program for pumps, locomotives, trucks, shovels and drills at their open-pit mine in Labrador City, Newfoundland. This system will use intermittent on- and off-line, condition monitoring based on ANNs and expert systems (ES). A functional overview is discussed. The data would identify where and what is the particular machine alarm condition. Such an approach would allow improved fault detection of machine components, especially in mines where trained personnel are not readily available. (Abstract shortened by UMI.)

Fragmentation by blasting is distinct from other method of rock breakage due mainly to the short time scale involved in the application of stresses. In the present work, the dynamic rock properties, applicable to non-static fragmentation process have been measured and compared with measured values of other fracture related properties. Further, these are examined to establish correlation with respect to their physical, mineralogical and micro-structural characteristics. The rock types selected for the present work ranged from nearly homogenous isotropic rock to an-isotropic rocks. The nearly isotropic rock were represented by three different types of granites. The an-isotropic rocks consisted of gneissic granite, gneiss, marbles, limestone, and quartz. / The dynamic compressive strength, measured under a strain rate of 10 3/sec, has been found to be about 2.5--4.6 times the compressive strength measured under static conditions (strain rate of 10-6 /sec) for similar dimensions of rock samples in a wide variety of rock types. It has also been found that this ratio is higher for low strength rocks, and lower for high strength rocks. / The particle size distribution resulting from high velocity impact breakage is much smaller than in the static case. The degree of fineness (50% passing) generated under dynamic breakage is well correlated with the dynamic compressive strength; however, there appears to be no correlation between static compressive strength and the corresponding fragment size distribution. / Except for static compressive strength, the dynamic strength was found to have no significant correlation with the measured values of fracture toughness, tensile strength, or comminution work index. / The fracture toughness value is found to be controlled by the largest crack or grain size and to some extent, by porosity. The effect of crack density appeared to be non-linear; the fracture toughness initially decreases with increase in crack density, but further increase in the latter results an increase in toughness. This suggests the behaviour of rocks in dynamic compressive breakage is different than that due to static single crack growth. / The work index (WI), which represents a fracture process at an intermediate strain rate correlates better with the Brazilian tensile strength than the static and high strain rate compressive strengths. (Abstract shortened by UMI.)

A numerical study is carried out to predict 3-D fluid flow and heat transfer of confined turbulent single and twin slot jets in the presence of a crossflow. The low Reynolds number k-$ sigma$ turbulence (Launder and Sharma (17)) model was used to calculate the Reynolds stress and the turbulent heat flux. In the present work the following cases were studied: (1) Case I considers an impingement surface heated by a single turbulent slot jet. (2) Case II considers an impingement surface cooled by twin turbulent slot jets. In the latter case the buoyancy effect has been taken into consideration through Boussinesq approximation. In each case, the velocity vector field for the entire calculation domain and the heat transfer rate on the impingement surface are presented. The parameters studied include: the jet Reynolds number, confinement-to-impingement surface spacing, and crossflow-to-jet velocity ratio. In case II, an additional parameter representing the jet-to-jet spacing was also investigated. In both cases, the impingement surfaces was assumed to be at a constant temperature. / The flow field results were found to be in qualitative agreement with most of the past related experimental work. In case I, the average Nusselt numbers were compared with those obtained from Martin's (3) correlation. A good agreement was found in the range of validity of this correlation (low crossflow).

The Jameson cell is a relatively new flotation device that has been successfully used in several applications, ranging from mineral recovery to de-oiling dairy effluents. The cell comprises a plunging jet bubble column (downcomer) which discharges in a separation tank. The effect of operating variables on Jameson cell performance, e.g., gas holdup in the downcomer and interaction between the downcomer and separation tank, was investigated in this thesis. / Gas holdup in the downcomer of the Jameson cell was determined using conductivity measurements with ring-shaped electrodes installed in the interior wall of the downcomer. The Maxwell model was used to calculate the gas holdup from the conductivity measurements. In both two-phase and three-phase tests, the conductivity signal was also shown to be able to detect process disturbances (e.g., changes in flow regime). / Interaction between the downcomer and the separation tank was studied by altering the level in the separation tank. When gas flowrate was not controlled, the level affected the gas flowrate, pressure, pool level/free jet length, mixing zone length, and gas holdup in the downcomer. A pressure technique was used to determine the mixing zone length. / The effect of the superficial gas velocity on the froth/pulp interface position in the separation tank was also studied. Although no relationship could be drawn between gas flowrate and separation tank level, froth flooding or loss of froth interface was observed at a superficial gas rate (with respect to the separation tank) $ ge$1.2 cm/s.

This thesis presents the results of a research project on the effect of geology on the fragmentation of rock excavated by blasting in underground developments. The research was undertaken at CANMET's Experimental Mine in Val-d'Or, Quebec. / A total of thirteen (13) blasts were studied from November 1994 to February 1995. The analysis of each blast was divided into three stages: (1) Pre-blast: includes structural mapping, rockmass characterization, estimation of the in situ block size distribution and documentation of the blast design. (2) Blast: includes blast vibration monitoring and analysis. (3) Post-blast: includes determination of fragment size distribution, half-cast factors and bootlegs. / The blast design was kept as constant as possible throughout the study in order to limit the variation of parameters to the geology-related ones. The results were analyzed to determine any correlation between the rockmass characteristics and the blast results. Only general trends were found: (1) The characteristic size of the fragments obtained after blasting (x$ rm sb{c}$ blast) increases when the characteristic size of the in situ distribution (x$ rm sb{c}$ in situ) increases; (2) The characteristic size of the fragments obtained after blasting (x$ rm sb{c}$ blast) decreases when the adjusted powder factor increases; (3) The half-cast factor (HCF) decreases when the Rock Quality Designation (RQD), RMR and Q values increase; (4) The characteristic size of the fragments obtained after blasting (x$ rm sb{c}$ blast) increases when the RQD, Rock Mass Rating (RMR) and quality index (Q) values increase. / Some of these results confirm basic blasting principles whereas others were unexpected. The fact that no statistical correlation could be found is probably due to the geological environment in which the experiments were completed. The rock types encountered have very similar mechanical properties and the quality of the rockmasses did not vary extensively. Therefore, any variance in the results is best explained by the blast performance itself. (Abstract shortened by UMI.)