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The Montgary pegmatite is located at Bernic Lake in the southeastern Manitoba pegmatite district. 'It has a complex internal structure with several contrasting mineral assemblages. The pegmatite contains a number of potentially valuable miners including spodumene, amblygonite,. lepidolite, zinnwaidite, pollucite and beryl.. The distribution of each of these within the pegmatite is related to the internal structure and controlled by a specific mineral assemblage. Parts of the pegmatite contain a high concentration of spodumene. The pollucite occurrence is of unique character and is one of the largest known deposits of this mineral. The pegmatite is still-like in attitude with a maximum dip of about 15 degrees. Its contents with the amphibolitic wall rocks are sharp and tourmalinized. Mineral assemblages present include perthite-plagioclase-quartz-muscovite, spodumene-microcline perthite-plagioclase-quartz-muscovite, cleavelandite-lithia micas-quartz, quartz-amblygonite, albite, lepidolite, pollucite, and quartz assemblages. The occurrence and relationships of these are described and possible relationships between attitude and internal structure are discussed. Many features of the pegmatite suggest that the deposit formed by crystallization and differentiation of a pegmatitic fluid in a restricted system. These features are discussed. The nature and occurrence of the pollucite, lepidolite and albite assemblages are such, however that it is difficult to visualize them resulting from such a system. These assemblages may be of later replacement origin. The source of the, late, alkali-rich replacing solutions may be unmixing of soda and the rarer alkalis (lithium, rubidium, caesium) from earlier-formed silicates in a manner analogous to the unmixing of soda feldspar in perthites. Various aspects of this hypothesis are examined.

Jan 1, 1959

By Lu Yang

In the last two decades, acid iron ore pellets have established their predominant position as the iron-bearing burden material for blast furnace ironmaking in North America. It is a general practice that pelletization plants are asked to produce pellets of certain chemical composition and in a narrow range of sizes. A minimum amount of fines created during handling and transportation is desirable. Such a requirement is often expressed indirectly by the minimum compression load causing a pellet to break. The behavior of pellets inside a blast furnace, of course, is very important for a smooth and efficient operation. Before its melting in the lower part of a blast furnace during this period of several hours the behavior of pellets depends on their properties after induration as well as conditions inside each furnace. Among properties of indurated pellets, the ability to maintain their physical integrity in the burden and to be reducible are most important. To maintain the integrity of pellets (i.e., minimal low temperature breakdown, swelling and softening) so that there will be adequate overall permeability for certain wind rate and local permeability for gas/solid contact for reduction. A higher reducibility will moderate the adverse effects of swelling and softening and contribute to a smooth operation and efficient use of heat and reductants in a blast furnace. An article devoted to the relationships between the quality of iron ore pellets and blast furnace practice has been published elsewhere(1); therefore, no further discussion is needed here. The mechanism of strengthening of iron ore pellets during firing has been the subject of investigation of many authors(2). There is no doubt that the bridging of the growing hematite grains, particularly starting with magnetite concentrates, is very significant in the production of strong pellets. Recently, there are many reports from blast furnace operators that they have noticed the adverse effect of LTB in their plants. It is obvious that the strength derived from bridged hematite grains may disappear when hematite is converted to magnetite with thorough breakdown of grain structures. It is suggested that some other strengthening mechanism may be required in order to improve the LTB index of acid pellets. The influence of porosity on both compression strength and reducibility follows regular patterns. It has been suggested(1) that the amount of liquid slag in pellets during firing determines to a large extent the porosity, hence, indirectly, strength and reducibility.

Jan 1, 1983

By D. E. Cameron

The Cannon mine, located in north-central Washington is mining gold hosted in silicified Eocene-age arkosic sediments arrayed along a regional strike-slip fault system. Branches of the Eagle Creek fault have broken the Chumstick Formation into blocks and wedges, and have caused intense deformation of stratigraphy in the mine. Mineralization at the Cannon mine (B-Reef) and O-Reef (L-O mine) is a bulk silicification with high grade cross-cutting veins containing principally electrum, silver sulfosalts and pyrite in a gangue of quartz, adularia and calcite. Orebodies have very irregular shapes, but tend to follow stratigraphy and high-angle pre-mineral fault breccias and splays developed adjacent to the major faults. Both B-Reef and O-Reef occur at significant bends in the regional trend of major fault strands. Mean gold grades decrease upward from near sea level to the 300 m elevation at the Cannon mine. A new discovery, the A-Reef is hosted by a moderately dipping structure which is at a low angle to bedding. Fluid inclusion studies of B-Reef ore zones indicate dilute ore-bearing fluids boiled at temperatures between 185 and 2850 C at a depth of 1 km. Many ore zones are bounded by sheared mudstone and claystone and a much broader halo of argillic alteration comprising illite, smectite and sericite. Trace and major element analysis by ICP-ES for 33 elements, LECO for S, Hg by CVAA and gold by AA-FA shows dispersion patterns hundreds of meters outward from the known orebodies in the Cannon mine. Geometric mean comparisons, hierarchical R-mode cluster analysis and single element spatial plots show that Hg, As, Sb, S and K/Al compose a suite of elements which are significantly dispersed away from, and increase toward mineralization. Ba, Ca, Na, Mn, V and Zr decrease toward mineralization. The suite is more selective than gold with respect to known mineralization within the exploration area.

Jan 1, 1992

By J. B. Davis

Isotope analyses distinguish biogenic sulfur ores from non-biogenic ores, but do not distinguish bioepigenetic from biosyngenetic ores. Sulfur deposits of salt dome caprocks and of bedded Permian evaporites of west Texas, however, are clearly bioepigenetic. Anhydrite, introduced by salt diapirs into geologically younger sediments, is converted biogenically to sulfur and calcite in the presence of petroleum; for example, in Challenger Knoll, a salt dome at a water depth of 3600 m in the Gulf of Mexico. Bedded evaporites of west Texas in association with petroleum show an obvious epigenetic replacement of the anhydrite layers by biogenic sulfur and calcite

Jan 1, 1978

By D. Weston

During recent years there has been a great deal of confusion in the North American mining industry with the introduction of new comminution terminology and claims (without substantiative evidence), for various types of equipment in this field. The authors will attempt to clarify the terminology used, and where possible, give illustrations of plant practice with actual operational and pilot plant data. This is considered necessary in order to obtain a clear picture of the comparison of such equipment to the revolutionary change that the Aerofall Mill has brought to the mining industry.

Jan 1, 1964

By Kot F. Unrug

When reading different studies discussing trends in coal mining, it appears that a substantial expansion of output by the year 2000 is predicted, even in the most pessimistic forecasts. Depletion of shallow, easy-to-mine deposits is only a matter of time, and the future average mining depth will increase. The proportion of slope to shaft mines operated during the next decades will change in favor of the shaft mines. Since an increasing amount of shafts in new nine developments seems to be inevitable, it appears appropriate to focus more attention on shaft design criteria. Some valuable papers have recently been published (1) that emphasize geotechnical aspects of shaft design. In the discussion that follows some other aspects of design criteria will be evaluated.

Jan 1, 1984

Mill #4 processes mildly refractory ore from Carlin Trend deposits. Diagnostic analysis of plant operating data was used to generate a mathematical model containing the key parameters influencing the gold recovery. The model was used to direct modifications to plant operating practice. The cyanide dosing strategy was changed to reduce preg-rob gold masses and cut reagent consumption A finer grind was achieved without capital investment. The density in CIL was lowered, and tighter control was exercised over plant throughput. These changes resulted in a recovery increase of at least 2%, worth $111,000/month at $300/oz, and concomitant reagent cost savings of $55,000/month.

Jan 1, 1999

By J. W. Leonard, D. A. Newman

By using physical and chemical means to increase the bulk density of newly broken coal freed from the mine face, the potential to improve coal mine productivity is significantly enhanced. It is estimated that by increasing bulk density, greater tonnages can be placed in fixed volume scoops and shuttles cars to improve production by as much as 10% to 20%. Such improved packaging to achieve new levels of volumetric efficiency might require only small and easy to implement changes to present downstream mining operations. Opportunities exist for improving broken coal bulk density from the moment of breakage, during transport across the continuous miner or loading machine, during discharge into the haulage unit, and after placement in the haulage unit. Physical/chemical methods for broken coal compaction in mobile, fixed volume units in underground operations are discussed.

Jan 1, 1990

By Jian Liu

The study aims to leach copper from a low-grade flotation middling by optimizing the leaching process using response surface methodology. The effect of key parameters, i.e., sulfuric acid concentration, nitric acid concentration and leaching time, on the leaching efficiency was investigated and a quadratic model was suggested by the methodology to correlate the variables to the efficiency. The results indicate that the model is in good agreement with the experimental data at a correlation coefficient (R2) of 0.97 and the most influential parameter on efficiency was identified as sulfuric acid concentration. The optimum conditions for copper leaching from the middling were identified as sulfuric acid concentration at 103.74 g/L, nitric acid concentration at 12.50 g/L and leaching time of 30.98 min; under such a condition, an average leaching efficiency of 93.16% was achieved from the middling.

Jan 1, 2011

By J. M. King

A crucial step in the acquisition by one company of the assets of another, the acquisition of the stock of another company, or the merger of two com-ponies, is the legal due diligence which needs to be performed in order for the acquirer to ascertain or confirm the obligations, liabilities and exposures to risk that are being assumed along with the assets or corporate stock being acquired. Where the obligations, liabilities, or exposures to risk arise from existing contracts, or from pending lawsuits, administrative proceedings, or threats of these actions, those matters are relatively straightforward to discover by careful review of the files of the party whose assets or stock is being acquired. However, where a company is engaged in ongoing mining or processing operations and has operated or owned mining proper-. ties, there are many sources of liability and exposure to risk which could have major adverse economic consequences to the acquiring party and which are not revealed, or at least are not clearly delineated, by the records of the company whose stock or assets are being acquired.

Jan 1, 1990

By Frank H. Buchella

Principal factors influencing equipment selection can be grouped into five basic categories. Tonnage Requirements, Ore and Waste Loading, transporting, and ground preparation equipment are largely determined by tonnage requirements. Generally, the greater the tonnage requirements, the larger the equipment size selected. Large size equipment is appropriate for a production of about six million tons (total) per month, medium size for three mil- lion tons, and small size for one million tons or less.

Jan 1, 1973

By Robert H. Oliver

Flowsheet flexibility in new 750 TPH coal cleaning plant provides three unusual capabilities. Two compartment drum coarse H.M. washer can be adapted to provide two stage separation. Coarse section of plant can be operated without fine section when washing surface mined coal. Fine section can operate with flotation cells bypassed if strip coal oxidation kills the froth. Plant can be fed by belt from bulk storage, front end loader from storage piles and truck from the mines. Raw coal and each of four washed products can be fed by belts to three separate loading points on two separate railroads.

Jan 1, 1979

By J. C. Draper

This subject was introduced last April in a paper presented in Birmingham, Alabama, by James E. Elkin, General Superintendent of Duquesne's Coal Department. This paper will cover some of the same data and in addition it will update and further describe our experience. Our Portal No. 3 was started in June 1965 with battery tractor-trailer face haulage. This mine is operating in the Sewickley seam in Dunkard Township, Greene County, in Southwestern Pennsylvania as shown on Fig. 1. The Warwick group of mines fronts on the Monongahela River and extends westward for some ten miles as shown on Fig. 2.

Jan 1, 1968

By Mike Lewis

"Descending several stories down a metal staircase into a shaft spanning a quarter city block -- soon to become Roosevelt Light Rail Station in Seattle, WA -- visitors are greeted with four perfectly round, precast concrete-lined horizontal holes leading deep into the earth. The sound of water trickling out from a small drainage trough can be heard over the faint echoes of construction within. Upon entering, the light is dim, but the air is clear with barely a dust particle flowing through the sunbeams. This type of air quality is only accomplished with diligent controls, and JCM Northlink, the company in charge of building the Northgate Link Extension Project, is taking those measures seriously.Commissioned by Sound Transit, JCM is a joint venture of three companies: Jay Dee Contractors, Frank Coluccio Construction Co. and Michels Corp. The tunnels JCM constructed are intended to provide fast, reliable underground rail service, as well as relieve one of the region’s most congested traffic areas. The $440 million project will connect the Northgate, Roosevelt and University District neighborhoods north of Seattle to the downtown corridor and SeaTac airport further south.The scope of this project includes excavation for two light rail stations, boring of two parallel 5 km- (3.3-mile) long light rail tunnels in six runs and the construction of 23 cross passages. Begun in 2014, Sound Transit estimates that crews excavated more than 382,000 m3 (500,000 cu yds) of soil and installed 7,352 precast concrete tunnel liner rings during the shaft construction and boring phase. Now that tunnel boring is complete, JCM is in the process of constructing the cross passages, which act as maintenance areas and escape routes for passengers. Throughout the entire process, the company has utilized atomized mist to control particle emissions.“Our dust control needs change at every phase of the project and don’t go away until the project is fully complete,” said a JCM safety representative. “We found that different dust suppression technologies were needed at different intervals, but atomized mist seemed to fulfill our needs at every step.”"

Jan 9, 2017

By R. S. Kasper

This paper reviews the procedure used to quantify the conveyor frictional resistance on a 3.9 km (2.4 mile) long overland conveyor belt. Field torque measurements of the three drives were used to help fine tune a computer simulation of the conveyor. This enabled the prediction of the effect on various conveyor components that cold temperatures will have on increasing the throughput tonnage.

Jan 1, 1995

By Roger Malmström, H. Heden, Kjell Lidin

INTRODUCTION LKAB was formed at the turn of the century when the railways between the ore fields and harbors were built. The mines are situated north of the Arctic Circle in Sweden. Kiirunavaara is the largest mine, with a pro¬duction capacity of approximately 30 Mt/a. Malm¬berget has a capacity of about 12 Mt/ a. Both are under¬ground mines. Svappavaara, the only opencast mine currently in operation, has a capacity of about 4.5 Mt/a. The ore harbors are at Narvik for the Kiruna and Svappavaara mines and at Lulea for the Malmberget mine (see Fig. 1). Production in the form of finished products is shown in Fig. 2a, b, c, and d. Due to poor ore markets in re¬cent years, production and shipments have been cut back, but there was a positive swing in 1978. LKAB has been 96% state-owned since 1957. In addition to the iron mines in northern Sweden, LKAB has subsidiaries in central Sweden which produce sulfide ores, quartz sand, and uranium (Fig. 3). The mining methods employed are opencast bench stoping at Svappavaara and sublevel caving at Kiirunavaara and Malmberget. GEOLOGY The Kiirunavaara ore body is 4000 m long and av¬erages about 90 m wide, with variations in width from a few meters to around 150 m. The ore has been ex¬plored by deep drilling down to about 1000 m, but mag¬netic measurements indicate a depth of at least 1500 m. The Kiirunavaara ore is oriented in a north-northeasterly direction with a number of ores in the boundaries be¬tween the wall rock types. The ore in Kiirunavaara is mainly a fine-grained magnetite with a varying content of fine-grained apatite. The apatite content of the ore decreases with increasing depth. The other ores are all apatite-bearing and a couple are hematite ores (Fig. 4a, b). The ores are sedimentary, tilted, and tectonically de¬formed. They have a lateral dip of 0.87 to 1.2 rad (50 to 70°). The contacts between ore and wall rock are distinct and sharp, but both the hanging wall and the footwall are brecciated and impregnated with magnetite. The footwall of the Kiirunavaara ore consists of syenite porphyry with a low quartz content and rela¬tively good strength; the hanging wall consists of quartz porphyry. Both types are known as Kiruna porphyries. The ore at the boundary with the hanging wall is often rich in kaolin. There are a few veins of syenite porphyry running through the ore, which has a few major faults (Fig. 4c, d). There are two sharply delineated ore grades in Kiirunavaara: low phosphorus ore with less than 0.1 % phosphorus (about one-third of the ore) and high phos¬phorus ore with greater than 0.5% phosphorus. The iron content is 67% in the low phosphorus ore and 60% in the high phosphorus ore. These ore types are sold as different grades and so are kept separate during mining. MINING AT KIIRUNAVAARA The Kiirunavaara and Luossavaara ores were first mined using opencast bench stoping in 1902. When mining costs rose owing to higher waste removal, under¬ground methods were adopted. In the mid-1950s, the ores were still being mined on the surface at the same

Jan 1, 1982

By Mehmet Bugdayci, Onuralp Yücel, Yeliz Demiray Cucurachi, Ahmet Turan

The production of strontium (Sr) metal from its oxide via an aluminothermic process under 1–5 mbar pressure was examined in this study. SrO of 99%purity by weight was used in the experiments. The effects of stoichiometry and the duration of the process on the efficiency ratio of the metallic strontium were examined. The effects of functional additives (BaO, CaO, CaC2) were also examined. Characterization was carried out using X-ray diffraction spectrometry (XRD), atomic absorption spectrometry (AAS) and flame photometry techniques. The highest Sr efficiency ratio obtained was 96.89% in the experiment conducted at 1250 °C with 300% Al stoichiometry and 300% BaO stoichiometry.

Aug 7, 2020

By F. J. Hurst

Phosphate rock, which is a prime source of phosphate used in fertilizer manufacture in the United States, contains uranium. In general, the uranium content of the rock increases with the phosphate content and most high-grade phosphate deposits (>30% P2O5) contain 0.01- 0.02% U3 8. The large tonnages of rock being mined represent a significant potential source of uranium that lends itself to recovery as a by-product of the wet-process phosphate industry. For example, in 1953, the U. S. Geological Survey estimated that recoverable phosphate reserves in the U. S. totaled about 5 billion tons and contained 600,000 tons of uranium. I This estimate did not include any rock from North Carolina which has since been estimated at about 2 billion tons. For the most part, the known, economically mineable U. S. reserves - estimated at about 7 billion tons - are concentrated in a few areas: 43% in the western states of Idaho, Montana, Utah and Wyoming; 28% in each of Florida and North Carolina and less than 1% in Tennessee. In the past, Florida has supplied about 80% of the total U. S. production, practically all of which is land pebble phosphate. All forecasts indicate increased production rates from North Carolina and the western states.

Jan 1, 1976

By Michael R. Grubbs

In most resource recovery plants the incoming solid waste material is first shredded and then air classified into a light and a heavy fraction. The light fraction which contains mostly paper, cardboard, etc., can be used either as a fuel for power generation or in the production of new paper products. The heavy fraction which remains consists mostly of glass, ceramics, wood, ferrous metals and non-ferrous metals. The ferrous metals may be removed from the heavy fraction by conventional magnetic separators. After primary shredding, most of the glass and ceramic is fine in size and may be screened away leaving a residue of wood, cardboard, and non-ferrous metals. This residual heavy fraction is the input material for the separator described in the present paper. A new metal separator was recently reported by t. Schlömann1. The author described the theoretical relationships and presented results of tests on samples of the residual fraction of municipal solid waste. This paper describes the operation of the metal separator and develops the basic separation relationships controlling the process.

Jan 1, 1976

By John Dodd

Advances in the technology of abrasion resistant irons and steels, which could help in combating abrasion and wear in mining operations, are reviewed. Nodular irons alloyed with nickel or copper and molybdenum, with acicular, bainitic or bainitic-martensicic microstructures are described. These alloy irons combine excellent castability and relatively easy machinabilitv with good resistance to wear. Recent progress in the development of high chromium molybdenum alloy irons is outlined, by which high temperature heat treatment of massive castings can be eliminated, alloy costs can be reduced and cracking problems avoided. Data is also given on the erosion-corrosion resistance of these irons. Trends in the development of improved cast steels are outlined. Factors influencing the toughness and abrasion resistance of manganese steels are considered. The 6% Mn 1% Mo manganese steels are shown to have a useful combination of toughness and abrasion resistance. Composite castings are seen as a means of com- bating abrasion in applications involving severe impact. A brief appraisal is given of recently developed martensitic wrought steels with improved weldability.

Jan 1, 1981