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By Wilson Blake

A mathematical model based on the finite element method of stress analysis has been used to describe the behavior of the western wall of the Kimbley Pit as its slope was steepened from 45 degrees to 57 degrees. Theoretical stress changes because of slope modification are slight except at the toe of the modified slope. Magnitudes of stress created are small when compared with the strength of a competent rock. Resulting displacement patterns point out the need for determining the in situ state of stress at a site prior to excavation or modification. A comparison of model results with field measurements shows that, in general, the model has described the measured behavior of the west wall of the Kimbley Pit remarkably well.

Jan 1, 1968

By Gu Guohua, Hu Yuehua, Zhang Qin

The flotation behavior of pyrrhotite was investigated by using ethyl xanthate as a collector. Results showed that pyrrhotite had good floatability from pH 2 to pH 11, and poor floatability when pH was >12. The flotation of pyrrhotite was dependent on pulp potential on various pH values. The potential-pH range for pyrrhotite flotation was established. Cyclic voltammeny and FTIR spectroscopic analysis showed that the major adsorption product of ethyl xanthate on pyrrhotite was dixanthogen. The intensity of FTIR signals of dixanthogen adsorption on pyrrhotite and the anode current of a pyrrhotite electrode and flotation response of pyrrhotite are correlated with pulp potentials.

Jan 1, 2005

By John W. Rozelle, David S. Bolin

INTRODUCTION During the normal course of a mining project, a feasibility study will be prepared that addresses all the aspects of the project including geology and mineral inventories, mining and geo- technical, metallurgical processing, infrastructure, environmental considerations and economic analyses. These studies are prepared for various reasons. Occasionally, a feasibility study will be prepared solely for use within a company as justification for development expenditures, however, these documents are frequently submitted outside the company either to raise funds from financial institutions or from public financing on one of the various securities exchanges. Mineral industry consultants are often called upon to participate in the preparation of feasibility studies or to conduct an independent audit and review of an internally prepared study. As the recoverable mineral resources form the foundation upon which the balance of a feasibility study is based, including the economic analysis of the project, the resource aspect of the study is examined very carefully by financial and securities organizations. The balance of this discussion is directed toward the various geological and resource estimation aspects of feasibility studies that experience has shown to be of particular importance. Much of this discussion will be directed toward open pit gold operations, although the principles are applicable to any type of deposit. 2.0 GEOLOGIC RESPONSIBILITIES IN FEASIBILITY STUDIES The principal geological effort in the preparation of a feasibility study is generally dedicated to the following areas: - Preparation of Geologic Reserve/Resource Estimates - Condemnation of Sites for Facilities, Access Roads, Leach Pads, Waste Dumps and Tailings Disposal - Collection of Geotechnical Data - Provision of Mineralogical and Petrological Data Pertinent to Metallurgical Processing - Selection of Appropriate Bulk Sampling Sites for Collection of Metallurgical Samples Each of these items will be addressed in detail in the following sections. 3.0 RESERVE/RESOURCE ESTIMATION An ore reserve estimate consists of the determination of a volume, or tonnage, and a grade for the deposit. There are numerous cases in the mining industry of projects that have experienced severe difficulties when operational ore grade, tonnage or metallurgical amenability have proven to be deficient compared to predicted estimates. An error in estimation of tonnage generally leads to more long term problems affecting mine life and production schedules. However, a significant error in the estimation of grade, particularly if mined grade is lower than anticipated, can have an immediate, and often disastrous, effect upon a project. The geologic preparation leading to an ore reserve estimate generally follows a logical sequence familiar to

Jan 1, 1987

By P. Wearden, K. Bryner, K. Vrana, V. Castranova, R. Dey, R. Reist, J. Blackford

INTRODUCTION Proliferation and enhanced synthesis of collagen by pulmonary fibroblasts have been shown to be key steps in the development of chronic silicosis (Goldstein and Fine, 1986). The regulation of lung fibroblast proliferation by cytokines released from alveolar macrophages may be an important pathogenetic mechanism in the development of the fibrotic process (Kelley, 1990). One cytokine, platelet-derived growth factor (PDGF), promotes fibroblast proliferation by inducing the movement of quiescent (Go) cells into the C1 phase of the cell cycle (Chen and Rabinovitch, 1989). Others regulate the rate of transition of fibroblasts from Gl into the S phase (Leof et al., 1982). These two classes of cytokines have been termed, respectively, competence and progression factors. One approach used to examine the release of cytokines from macrophages is the fibroblast proliferation assay in which fibroblasts are exposed to culture supernatants from macrophages exposed to various stimuli. In most of these assays, the supernatant contains fetal calf serum which provides the competence factor(s) necessary to facilitate the proliferation of fibroblasts (Bitterman et al., 1982; Bitterman et al., 1983; Elias et al., 1988). Recently, a fibroblast proliferation assay using plateletpoor plasma (lacking competence factor(s)) as a substitute for fetal calf serum has been described (Kuman et al., 1988; Bauman et al., 1990). In this assay, the release of a competence-inducing PDGF-like growth factor from rat and human macrophages can be distinguished from other cytokines that act as progression factors. In order to obtain more consistent results and with the ultimate goal to be able to discriminate between the effects of competence factors as opposed to progression factors, we have conducted experiments to determine the appropriate concentrations of plasma and PDGF required for imparting competence in the fibroblast proliferation assay. We tested lung fibroblast cells obtained from explants of rat lung tissue and also a fetal human lung fibroblast cell line obtained from American Tissue Culture Collection (ATCC153). MATERIALS AND METHODS Fibroblasts Specific pathogen-free, male Sprague-Dawley rats were use in some studies. Animals were given a lethal intraperitoneal dose of sodium pentobarbital. Fibroblasts were isolated by chopping the lung in enzymes that digest the connective tissue but liberate lung cells for further study (Rabovsky et al., 1989). After digestion, the remaining lung tissue suspension was filtered through two layers of sterile gauze and centrifuged to recover lung fibroblasts. These were resuspended in culture medium that contained 10% fetal calf serum and distributed to culture plates for growth. In other experiments, a human fetal lung fibroblast cell line, obtained from American Type Culture Collection, Rockville, MD, 20852, was used instead of rat lung fibroblasts. In these cases, a 1 ml ampule containing human fetal fibroblasts was plated into a tissue culture flask containing medium plus 10% fetal calf serum. For both types of fibroblasts, culture medium was changed 3 times per week and cultures were incubated at 37°C until confluent. Harvested rat and human lung fibroblasts were quantified using an electronic cell counter equipped with a cell sizing attachment (Coulter Electronics, Inc., Hialeah, Florida). Tritiated Thymidine Incorporation The basic procedural outline of Kumar et al. (1988) was used with modifications to evaluate tritiated thymidine incorporation into fibroblast DNA following exposure to PDGF and plasma. Both rat and human lung fibroblasts were plated at 50,000 cells/ml at a density of 250,000 cells/25cm2 culture plate. Cells were quiesced for 4 days with 2% rat plasma. As the assay was refined, fibroblasts were quiesced in plasma-free media for 48 hrs, since the mitogenic activity of 2% plasma was variable. Test medium was applied for a period of 6 hrs, followed by a 24 hr tritiated thymidine (lµCi/ml) labelling period in plasma-free media. Medium alone was used as a negative control and media with 10 or 20% fetal calf serum was used as the positive control for rat and human fibroblasts, respectively. Cell Quantification and Measurement of Mitogenesis Twenty-four hours after the addition of tritiated thymidine, the fibroblasts were washed with 5ml of fresh serum-free media, centrifuged and resuspended in phosphate-buffered saline. The cells were dissolved in 0.5m1 of O.1N NaOH and radioactivity determined in a beta counter. Incorporation of trititaed thymidine as an index of DNA synthesis was expressed as DPM/fibroblast. RESULTS In the present study, we quantified mitogenic potential by monitoring the incorporation of tritiated thymidine as

Jan 1, 1991

By Jaime E. Sepúlveda

Semiautogenous grinding (SAG) operators have been realizing the very significant impact of fresh feed particle size distribution on the mill grinding capacity. In actual practice, this impact may be quite difficult to assess because of the natural process variability that may also involve- concurrently other critical factors such as ore hardness. Recognizing the limitations of the empirical approach, the current publication proposes the use of mathematical models and simulators to explore and assess the net effect of feed particle size only, independent of any other factors. The simulation analysis here reported provides a basis to claim that the size distribution of the particles being ground (simply characterized by a % - 2" or similar measurement) is one of the most relevant controlling variables of the overall mill performance, regardless of the SAG circuit configuration.

Jan 1, 2005

By Jim Armbrust

JAMIE DAVIS: Our next speaker is Jim Armbrust, maintenance manager at Phelps Dodge, Morenci. Jim's presentation is titled "We Need More Training-How to Get the Biggest Bang for the Buck." We've talked a lot about preventative maintenance and we've heard several people talk about training. How do we train to use all these systems? How do we educate people? This will be a nice little wrap-up for us. JIM ARMBRUST: One common theme from this morning's talk is that we need more training. That's exactly what we'll be talking about for the next few minutes.

Jan 1, 1998

By J. A. Hrabik

The feasibility of mining deep phosphate deposits by a borehole mining system was compared with mining by proven conventional techniques. An economic comparison of the borehole mining system with conventional dragline and bucket wheel excavator mining systems was completed at various mining depths and production rates. Hypothetical phosphate deposits, with various overburden thicknesses and reserve tonnages, were defined. Geologic conditions necessary for the application of the borehole system were identified. Discounted cash flow analyses based on derived capital and operating costs were used to generate rates of return and product prices. Borehole mining was found to be more economical where overburden thickness was 46 m (150 ft) or greater. However, at 15- and 30-m (50- and 100-ft) thicknesses, conventional surface mining was more economical. Overburden thickness has a great effect on the economic feasibility of the conventional mining systems but less effect on the economics of borehole mining. Economies of scale are only realized in conventional mining, since larger equipment is used to achieve greater production, whereas increased production from borehole mining is achieved using additional equipment units. A comparison of the environmental effects of borehole and conventional surface mining systems showed that borehole mining is environmentally more desirable.

Jan 1, 1987

By M. Kalin, H. D. Sharma

INTRODUCTION The inactive uranium mill tailings investigated in this study are located in two mining districts, Elliot Lake and Bancroft, Ontario, Canada. The sites exhibit a mixture of surface features consisting of dry areas, with or without vegetation and areas covered with water. On the edges of the water bodies, indigenous vegetation has invaded the tailings beaches [ Typha] spp. (Tourn.) L. a dominant plant on these tailings beaches, has been studied for the uptake of radium-226 and lead-210 (Kalin and Sharma, 1981b) from the tailings. It was found that most of the radium-226 remains in the roots of the plants, and that the solubility of radium-226 in control soil differs from that in tailings. The uptake of radium226 by vegetation and other biota is related to the solubility of the element in water. Factors controlling the solubility of radium-226 in uranium mill tailings are of interest in assessing the environments effects of these wastes. Rusanova (1962) found that the soluble or extractable amount of radium from the soil is inversely related to the total concentration of calcium and magnesium in the soil. Experimental work has clarified some aspects of the leachability of radium from uranium mill tailings (Levins, et al., 1978; Wiles, 1978, and others). Halvik, et al., (1967) studied the effects of pH and chemical composition of surface water on the liberation of radium from uranium mill tailings and uranium ore. He found that an increase in pH, up to a value of pH 9, decreases the amount of radium released from the tailings and the ore. A positive effect of calcium chloride was noted on the leachability of radium. Benes (1981) reviewed the physicochemical forms of radium and its migration in water. Based on experimental work, he identifies primary factors which determine leaching of radium from uranium mill tailings. The ratio of the volume of the leaching solution to the weight of the leached sample; the composition of the leached solids and the leaching solution, and finally the pH of the leaching mixture are of importance. He emphasized that a scarcity of field data exists, which would relate experimental work to the actual situation in the tailings ponds. Inactive tailings ponds in Ontario are 16 to 23 years old, and processes which are of importance in evaluating the long term effects of uranium mill tailings in the environment can be studied. The objective of this work was to investigate the leachability of radium-226 from the tailings under field conditions. MATERIALS AND METHODS Sample Collection A description of inactive tailings sites in Ontario, where the tailings and the water for this study were collected, can be found in a report by Kalin (1981). [Typha] spp. specimens were excavated from 16 different locations along with the tailings attached to the roots of the plants. A tailings sample from the surface area, around the plant, was secured before the excavation. Tailings samples were also collected from dry areas free of vegetation in the vicinity of the wetland stand. Surface samples (depth 0-5 cm) and samples at a depth of 20-25 cm were secured. Water was collected from the shallow tailings beaches around the vegetation stands. Sample Preparation The roots of the plants were washed free of tailings with distilled water. The resulting thick slurry of tailings was allowed to settle in the wash basin for five minutes and the supernatant water was decanted. The remaining saturated tailings were brought to 400 ml volume with distilled water in a beaker. The slurry was mixed with a magnetic stirrer for two 24-hour periods. After the first 24-hours, the slurry was allowed to settle for 20 minutes and the supernatant water was removed. The remaining sediments were suspended again in distilled water (400 ml total mixture) and leached for a second 24hour period. The tailings slurries from the different locations had a solid to liquid ratio, which ranged from 0.5 to 1.4 grams of dry tailings material per millilitre. The variations in the ratios are the result of differing fractions of coarse and fine tailings on the sites. In the final leachates, the solid to liquid ratios of the samples were 0.17 (±0.1) g/ml. The pH of the surface water and the leachate was determined with an I.L. Portomatic pH meter. All the tailings samples were homogenized in a mortar and brought to dryness at 75 to 85°C. Approximately 0.5 g of tailings were

Jan 1, 1981

By G. G. O. O. Uwadiale

Starting from a crude ore assaying 45.6% Fe, a fine-grained oolitic iron ore was concentrated by the oil agglomeration technique to 90% Fe recovery and 65% Fe assay. The ore required grinding to minus 5 µm to effect adequate liberation, and the technique yielded optimum results at pH 9. The roles of pH, collector, and bridging liquid concentrations on selectivity and yield of iron minerals in the concentrates are discussed.

Jan 1, 1991

By B. J. S. Sceresini

The Filblast Cyanidation Process incorporates the advantages of intense high shear mixing, high dissolved oxygen concentra­tion and high pressure to achieve extremely rapid gold dissolu­tion rates. This is made possible without suffering from high energy or wear rates by the unique design of the Filblast gas shear reactor. The reactor is a rugged and compact in-line device which can be constructed from a variety of wear and chemical resistant materials. High temperature tolerance is also possible so that the device can be incorporated into a pressure leach circuit with significant capital cost savings because of the high capacity to volume ratio that is an inherent feature of the device. For cyanidation applications the outer casing is protected by a polyurethane coating and the internal parts are of wear resistant polymer. The largest unit built to date has overall dimensions of 1200 mm length by 300 mm diameter and has a capacity of about 150 dry tonnes per hour at 40-45 % solids. Service life at this throughput is at least three months. Six mines are currently employing the Filblast Process and another six are conducting plant trials. The ore types range from highly reactive, almost impossible to treat, pyrrhotite/ arsenopy­rite to deeply weathered clay ore which forms a highly viscous pulp. It has been found that the effect of shear thinning has resulted in improved leaching and adsorption kinetics resulting in higher carbon loading and reduced soluble gold loss. Total tonnage treated is approximately eight million tonnes per annum. This paper presents the operating benefits and cost savings which have been achieved in four plants, two treating oxide/ sulphide ore blends and two treating highly reactive sulphide ore and concentrate. Filblast leasing and maintenance charges and pump operating costs are about ten percent of the benefits. A conceptual cyanidation circuit based on the Filblast Cyanidation Process is also discussed. The Filblast System is an in-line pressure leach aerator/ reactor which generates very high shear and greatly enhances mass transfer rate by generating extremely small gas particles where oxygen gas is required for oxidation reactions and/or utilising the high shear characteristics to minimise the diffusion boundary layer. Both of these rate limiting factors effect the rate mechanism for gold cyanidation. Initially two multi-stage Filblast aerator cartridges formed a leach train but now the trend is to install a single submersible cartridge of equivalent perfor­mance. This design simplifies installation and minimises change-out times. However the in-line concept can be employed where high pressure leaching or pressure oxidation is required. The reactor is submerged in the leach tank so that the mass of gas micro-bubbles contained in the discharging slurry is entrained in the agitator vortex and is thoroughly dispersed throughout the tank. A diagrammatic representation of a leaching circuit incorpo­rating the Filblast Reactor is shown in Figure 1. The recirculation pump takes new feed directly from the cyclone overflow trash screen either under gravity or pump fed and recirculates the balance to maintain 250 - 270 m3/h total slurry flow. All of the leach feed slurry gets at least one pass through the Filblast thereby eliminating short-circuiting. Typically a 6/4 EAH Warman pump drawing 60-70 kW is required to circulate 250 m3/h through the system. The back pressure generated by the Filblast is in the range of 400-500 kPa depending upon pumping rate, pulp density and slurry rheology. The high shearing rate effectively negates the viscous effect of slurries and the addition of a gas further reduces the pulp density by virtue of the intensely aerated, homogeneous medium. The gold leaching Filblast cartridge elements are made of polyurethane but stainless steel, ni-hard, rubber or ceramics can be used depending on the operating temperature and design duty. The efficiency of the Filblast Leach Reactor in gold cyani­dation is due to the extremely efficient mixing, oxygen dissolu­tion and surface polishing action of the Filblast design. Either air or oxygen may be used but Atomaer recommend the use of oxygen because of the rate benefits gained from cyaniding at [02] significantly > 20 ppm D O in the reactor. Very high DO concentrations have been measured; in excess of 50 ppm. There is some debate as to whether the value is a true measure of the DO or the oxygen meter sensor is measuring the effect of a mass of very fine bubbles of free oxygen. Regardless of the fact the reactor has registered some amazing gold dissolution rates commonly in excess of 80 % during transit of the pulp through the reactor. The elapsed time is less than half a second!

Jan 1, 1995

By Rudolf E. Greuer, Xintan Chang

Mine fires have always been of great concern to mining engineers and their behavior has been studied for a long time. Although an abundance of observations exist, no satisfactory mathematical model for their interpretation and extrapolation has become known. The paper presented here tries to close this gap, making use of the laws of chemical kinetics, energy and momentum conservation. To overcome the mathematical difficulties, the fire zone is axially divided into segments and radially into sections, each one with an extension of only a few inches. Conditions in segments and sections are updated in time intervals of one second or less. To solve the large number of resulting equations, a numerical solution is performed. The model has so far been tried on timber fires. It confirms experimental observations on the ignition phases and equilibria of these fires.

Jan 1, 1987

By Orville L. Lantto, Bruce K. Cantrell, Keith S. Olson

Approximately 10 to 20 pct of exhaust aerosol mass from diesel equipped vehicles operating without exhaust controls is attributable to particles in the 1.0-10 µm size range. Recent in-mine measurements suggest that, in addition to reducing overall exhaust aerosol mass concentrations, the use of waterbath exhaust conditioners (water scrubbers) may significantly reduce the concentration of diesel exhaust particles larger than approximately 0.5 µm aerodynamic diameter. This implies that a measurement system that discriminates between diesel and mineral dust aerosols on the basis of aerosol size would have different accuracies depending on use of a water scrubber. To test this hypothesis, laboratory measurements were made by the Bureau of Mines to determine diesel exhaust aerosol penetration efficiency through a water scrubber as a function of size and engine operating conditions. Size distributions were determined using a Micro-Orifice, Uniform Deposit Impactor. Concentrations of CO, CO2, NO x, O2 and gas-phase hydrocarbon concentrations were also measured. No significant effect was found for these gases other than a slight decrease in NOx emissions. The water scrubber served as a moderate aerosol control with reductions in mass concentrations of about 29±9 pct under most conditions. This reduction occurred for particles less than 0.2 µm and greater than 0.6 µm aerodynamic diameter. Coal dust aerosols are mostly larger than 0.8 µm aerodynamic diameter. With use of a water scrubber, separating the aerosol into two parts, greater and less than about 0.8 µm aerodynamic diameter during sampling, results in collection of diesel and coal dust aerosol accurate to within 10 pct. Without a water scrubber in operation, such a sampling protocol would only be accurate to approximately 15 pct.

Jan 1, 1991

By Keith G. Wallace, Gary K. Rogers

As a supplement to an analysis involving methodologies for the estimation of airflow resistance in shafts used for both ventilation and hoisting, a detailed shaft characterization survey was distributed worldwide. The survey provided detailed information which enabled verification of recommended velocities and established limitations on fill factors and relative velocities. This paper evaluates the information obtained for 37 shafts and presents a statistical evaluation of the results. Apart from airflow rates, conveyance rates, and physical characteristics, qualitative information regarding means of conveyance stability and velocity control techniques at unloading and loading points are also presented. Calculations of fill coefficient, free area velocity, and most importantly, relative velocity between the airflow and hoist, are conducted. These results are presented by frequency diagrams which illustrate the trends, as well as provide limitations for these parameters. The data illustrates that, commonly, the fill coefficient for two or more conveyances, does not exceed 30 %. A limit of 50% is suggested for a single conveyance shaft. A recommended free area velocity of 10 m/s (1,970 ft/min) for combined ventilation and hoisting shafts, is sup- ported by these results. Relative velocities of 30 m/s (5,905 ft/min) are most frequent and 50 m/s (9,840 ft/min) being a practical maximum.

Jan 1, 1987

By Gun Berglund, Eric Forssberg

Sulphide mineral flotation is known to be affected by oxidation-reduction conditions in the pulp, although there is some doubt as to whether it is the oxidizing environment or the type of oxidant which influences flotation. Variations in the oxidizing conditions of the pulp and their subsequent effect on flotation were examined for two types of natural sulphide ore, a galenasphalerite ore and a complex pyrite ore. Different gas mixtures ranging from pure nitrogen to pure oxygen were used to control the oxidizing conditions. Zinc recovery increased with a more oxidizing environment, and nitrogen gas acted almost as a depressant for sphalerite in the flotation of the Pb-Zn ore. For the complex pyrite ore, the selectivity between chalcopyrite and both gangue and pyrite improved when the environment was oxidizing, resulting in higher Cu recovery in the copper rougher concentrate. The use of an oxygen rich flotation gas was found to be a suitable method for changing the oxidizing conditions and improving flotation under controlled conditions. The flotation results were correlated to the oxygen content and the redox potential, parameters which describe the pulp chemistry conditions.

Jan 1, 1989

By Michael Gauna, William J. Gray, Joseph C. Zelanko

Mechanized mining in the underground coal industry has continued to evolve since the introduction of the remote control mining machine. Remote control continuous mining machines without an onboard operator’s compartment are now the norm in the industry. Extended cuts in excess of 30 ft (9.1 m) are commonplace. Unfortunately, machine operator positioning has become an often unrecognized safety concern, particularly when remote control continuous mining machines excavate a turn (turn a crosscut). From January 2001 through July 2004, remote control continuous mining machine operators or helpers have been involved in ten roof fall fatalities and eight machinery crushing fatalities. The machinery crushing incidents occurred when machines were being repositioned or moved to another place. Of the ten roof fall fatalities, three occurred while a crosscut was being turned and a fourth fatality occurred while mining was being conducted adjacent to the crosscut. The operating time associated with turning crosscuts is a relatively small part of the mining cycle. In recent years, however, a disproportionate number of fatal incidents appear to have been associated with this activity. Procedures for reducing the incidence of operator fatalities while turning crosscuts are discussed. These techniques include: minimizing the number of turn cuts, limiting turn cut depth, establishing no work zones and using visual warning devices to designate them, installing more roof/rib support in the vicinity of the turn cut, using notch cuts prior to initiating a full turn cut, and positioning the remote control miner operator in nontraditional locations.

Jan 1, 2005

By S. Zhou

Since the hypothesis of coal and methane outburst mechanism based on elastic mechanics gives no consideration to time, it can not give a satisfactory explanation to the outburst occurrence and its development. A creep mathematical model of coal containing gas has been set up through creep tests and analysis under the condition of tri-axial compression. And the model can explain the phenomena of coal and methane outburst successfully. The tests proved that there is no essential difference between the rheological properties of prone outburst coal and non-prone outburst coal. Outburst can take place in any kind of coal if the rheological conditions of coal containing gas are met. The creep mathematical model provides a basis for establishing a comprehensive index of coal and methane outburst possibility.

Jan 1, 1991

By David M. Mchaina, Allan E. Hall, W. C. H. Kruining, Alan Coode, Stephen Hardcastle

This paper details an investigation into the feasibility of recirculating mine exhaust air in Saskatchewan potash mines. This project was initiated following a previous study at Ruttan Mine, Manitoba, which indicated that recirculation of exhaust air to reduce winter heating costs was feasible. The potash industry was selected for study because the mines use a minimum of blasting in their production methods and the exhaust temperature is significantly higher than that of most metal mines. These factors simplify the monitoring system required and have the potential for greater waste heat recovery. A series of measurements of underground mine pollutants was made at the main exhaust and intake shafts in order to determine the feasibility of introducing controlled recirculation of exhaust air. An experimental recirculation circuit was created by opening two existing doors situated between the return and intake shafts. During this recirculation trial, the air quality parameters at the intake, mixed intake and exhaust measuring stations were monitored. The results obtained from a questionnaire circulated to the regulatory agency and the major potash producers together with results obtained from underground field studies at Central Canada Potash (CCP) Division of Noranda Minerals indicated that controlled recirculation of mine exhaust air has potential application in these mines either to reduce heating costs and/ or to increase the face air quantities. A recirculation system is to be designed in conjunction with CCP and the Saskatchewan Ministry of Labour, Mine Safety Unit to attempt to implement a working recirculation system for CCP.

Jan 1, 1989

By Janine L. Beazley, James H. Kyle

The effects of pH, pH modifier (lime or caustic soda) and cyanide on the pulp rheology of a number of ore types ranging from highly siliceous to highly kaolinitic has been investigated. All experiments were performed in fresh water at solids concentrations of 25 and 45% solids and in the pH range 6 to 11. The kaolinitic ores exhibited greater changes in rheology with pH and calcium ion concentration than did the siliceous ores.

Jan 1, 1989

By Donald Leroux

For the last few years, the grinding model first proposed by Andrews and Mika (1975) has regained attention from the scientific community. Though sophisticated identification algorithms have been developed, the number of its parameters that have to be estimated remains huge. Most of these constants (often more than 90%) are for the breakage function. This paper describes a new method for reducing efficiently the number of the breakage function parameters of the Andrews-Mika grinding model. It makes use of second-order statistics and of a stereostochastic model for liberation (for instance, BooKing).

Jan 1, 1992

By R. L. Wolfrom, R. Hogg, S. Chander

A gravimetric method for measuring rates of capillary rise in powders was explored. Methods to improve reproducibility and consistency of the results were investigated. In particular, the effects of particle size and packing uniformity were addressed. Studies of the wetting behavior of both spherical glass beads and irregularly shaped synthetic graphite particles by various organic liquids were carried out. Standardized procedures for bed preparation will be described. The applicability of the Washburn equation for surface energy evaluation in such systems will be discussed. Key words: Wettability, Powders, Capillary rise, Surface chemistry

Jan 1, 2003