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By Shaning Yu, Yosry A. Attia

The purpose of this work was to investigate the feasibility of using column flotation as a floc separation technique. In this study, the ultrafine coal (minus 25 microns) slurries were cleaned by using the Integration of column flotation with selective flocculation. It was found that using column flotation as a floc separation technique during the "cleaning" stage, achieved much better results than that either using column flotation as a rougher separation technique for coal flocs, or using It directly to recover the ultrafine coal from the slurries without adding selective flocculant. Thus, the ultrafine coal slurries were first separated by selective flocculation process to reject a certain amount of the dispersed ultrafine ash minerals, and to aggregate the ultrafine coal particles as flocs. Thus, the entrainment of ultrafine ash minerals Into the coal floc-froth concentrate during flotation could be considerably reduced. Subsequently, the coal flocs were further "cleaned" by column flotation. The experimental results Indicated that this approach was technically feasible and particularly suitable for a slurry containing a large amount of ultrafine particles. The effect of flotation time, and collector dosage on column flotation of coal flocs were also Investigated and reported In this article.

Jan 1, 1988

By Sinha D. K.

As the main source of indigineous energy, coal has a big role to play in the development of national economy of India. Nationalization of the coal mining has brought the entire industry under the unit control of the Central Government following which an ambitious plan for increasing the coal production in the next few five year plans has been undertaken. In order to achieve best all round results, economy-mathematical models of Planning the total system, right from the highest to lowest hierarchial levels of decision making, have been proposed through a Global Model which is detailed in Local Models in stages right up to a mine. Optimum obtained by computer solution of the models would provide basis for objective decision making in the fields of selection of optimum plan for developing the industry, the coal fields and the mines with construction and/or reconstruction of mines, capacity optimization of enterprises and mines therein. Different types of Models and the optimization processes are presented.

Jan 1, 1977

By Melvin H. Podwysocki

Lineament and fracture analysis have enjoyed a resurgence of interest over the last several years, particularly since the advent of the Landsat series of Earth resources satellites. Some applications for lineament analysis include mineral, petroleum and ground- water exploration, engineering studies such as highway routing, mine roof stability, dam and power plant siting and general tectonic studies. The needs of each study may be different, but the general problem of large masses of data is common to all. Methods for efficient handling of the information and some statistical methods for its evaluation are discussed. These include comparing the lengths of the fracture population against known distributions, trend surface analysis of fracture lengths and number per unit area and multivariate analysis of rose diagrams. Examples are shown in an experimental program for predicting the presence of reef structures, areas of potential petroleum production.

Jan 1, 1977

By Lo-Sun Jen

Introduction ? Canada is one of the largest miners and explorers in the world and is a world leader in the production and export of many key mineral commodities ? Canada has a stable political regime and a competitive investment and business climate ? Canada is endowed with mineral resources, advanced technology and management know-how ? Canadian stock exchanges are the world?s leading centres for raising equity financing for exploration and mining projects anywhere on the globe As with some other countries, Canada has experienced a recent decline in major mining developments

May 1, 2002

In deposits in which the secondary zones are well defined a layer of rich oxidized ore is frequently found immediately to overlie the enriched sulphides, from which it is derived by direct oxidation in place. In deposits that contain oxidizing precipitants particles and masses of residual oxidized ore are likely to be scattered through the leached zone, having been precipitated during migration before reaching the zone of enrichment. This precipitation hinders secondary enrichment and in extreme cases prevents the formation of such concentrations. Residual ores are precipitated by various reagents. Carbonates are formed through the action of the carbonic acid contained in surface waters, and also directly through the replacement of calcite, especially where the containing rock is limestone. Native metals, such as copper, gold, and silver, are formed by the action of reducing agents, among which organic matter and ferrous sulphate are prominent. Kaolin, gouge, and certain shales occasionally act as powerful precipitants through adsorption. Silver is often found as residual chloride, formed through precipitation by the chlorine contained in surface waters. Residual ores are often the result of incomplete solution, the relatively insoluble minerals being left behind during the migration of associated metals; incomplete oxidation and solution often leave residual masses of unaltered, or partly altered, sulphides in the oxidized zone. Such residual particles or masses have commonly been enriched by additions from circulating, metal-bearing solutions. During oxidation under conditions that permit reprecipitation, such as the oxidation of sulphide deposits in limestone, a scat-

Jan 1, 1932

By Michael K. Phang, Thomas A. Simpson

Field studies at an underground mine site were conducted to evaluate and monitor blast-induced vibrations on an underground coal mine roof. The vibration data were evaluated so that a suitable damage criteria or guidelines from which a safe operating distance between surface blasting and underground mine operations can be established.

Jan 1, 1984

By Jose F. Agapito

This paper describes part of a geotechnical program which was instrumental in obtaining information for the design of large oil shale pillars. The work was carried out during 1971 and 1972 in the experimental mine of the Colony Development Operation. Colony is an oil shale venture formed between Atlantic Richfield Company, Operator; The Oil Shale Corporation, Cleveland-Cliffs Iron Company, and Sohio Petroleum Company to conduct research and development in mining and retorting of oil shale. The property is located in the southern edge of the Piceance Creek Basin in northwestern Colorado, approximately 250 miles west of Denver. Mining was conducted by the room-and-pillar method in a 60-ft high portion of the Green River formation at a depth of 600 to 850 ft. Pillar dimensions are approximately 60 ft by 60 ft. The mine site is in the eastern face of the canyon containing the Middle Fork of Parachute Creek. The distance from the mine to the side of the mountain varies from 500 to 1200 ft, and its height above the stream floor is approximately 700 ft.

Jan 5, 1974

By Thomas M. Tharp, Mark A. Travers

A new method is presented for precracking three-point bending specimens for fracture toughness testing. A notched specimen of rectangular cross section is placed on a flat loading platen, with paper between specimen and platen. The specimen is loaded from above through a roller placed directly over the crack. The thin, high compliance joint between specimen and platen causes a distributed load on the bottom of the specimen. This results in bending at the cracked section and crack initiation at the notch tip. Since the joint is thin, its stiffness increases rapidly with deflection and crack propagation in the specimen generally remains stable and controllable. Fracture toughness KIC in a sandstone directly overlying the No. V coal was measured to be 0.27 MPa m 1/2. Even for cracks 1 cm long this value of KIC results in substantially lower effective tensile strength (modulus of rupture) in roof beams than is expected from intact rock strength.

Jan 1, 1986

By D. S. Cronan, S. P. Varnavas

Abstract - Metalliferous precipitates from submarine hydrothermal discharges have been investigated at four inshore locations off Milos in the Hellenic Volcanic Arc. The fine fraction of the sediments shows considerable variability in the concentrations of elements frequently associated with hydrothermal activity. Manganese varies from 30 ppm to 2500 ppm, encompassing the entire range of values found off Santorini also in the Hellenic Arc. Iron occurs in lower concentrations than off Santorini and Yali, while other elements often associated with hydrothermal activity such as Pb, Zn, As, and Cu also show enrichments in sediments from the hydrothermal vent areas. Selective leaching studies have shown that most elements are variably distributed between the different phases of the sediments but with enriched Pb, Zn, and Mn mainly in easily soluble secondary phases. Hydrothermal inputs are strongest at Palaeochori Bay, less at Voudia Bay and lowest at the Airport Springs and Rivari. The weathering of sulfide and possibly other orebodies is also thought to contribute to some of the elements enriched, while background concentrations are largely supplied from detrital sources.

Jan 1, 1999

By D S. Stewart, K W. Keskimaki

In 1999, the Henderson Mine commissioned the Henderson 2000 project - a new truck haulage level, a new underground crusher and a 24 kilometre conveyor system to replace a 23-year old rail haulage system. Henderson has been able to continuously improve in almost all aspects of its rubber-tired mining. The rail haulage system represented one of the last barriers to continuous improvement to the overall plant performance. Many of the lessons learned in other areas of the mine were utilised to design the truck level. This paper chronicles the benchmarking, equipment selection and design of the level. Areas covered will include haulage trucks, level layout, ore chute design, traffic control, road design and crusher layout.

Jan 1, 2000

By S. A. Falconer

This paper deals with the practical application of the Dutch State Mines cyclone separator for fine-coal cleaning. The more important operating variables are discussed, and results of a number of continuous- scale tests on various fine coals with a 6-in. cyclone separator are given. Descriptions of the Cyanamid Pilot Plant and the 50 tph Cyclone Separator Plant at the Emma Washery in Holland are included.

Jan 7, 1950

By Ennio Bonetti

The technological applications of MgH2 hydrides for hydrogen storage demand the overcoming of some critical issues: an improvement of the reaction kinetics and a reduction of the desorption temperature. The synthesis of nanocrystalline MgH2 by reactive milling and inert gas condensation and a proper metal catalyst addition, constitute recently employed strategies. In the investigation of the hydrogen short and long-range dynamics, sorption kinetics and nanostructure stability, the mechanical spectroscopy offers some specific advantages. In the present research this technique was employed with other experimental approaches (XRD DSC) to investigate relaxational and structural damping processes in nanocrystalline MgH2 with added catalysts (Fe). Time/temperature variation of the dynamic elasticity moduli and mechanical quality factor are correlated to hydrogen anelastic relaxation processes and concomitant structural transformation of MgH2 to Mg associated to long range H diffusion. Results are discussed with reference to microstructural modification strategies able to assist hydrogen release.

Jan 1, 2006

By J. J. Pavlica, I. Iwasaki

Grinding in steel milk adversely affects the flotation removal of pyrrhotite from magnetite ores. To elucidate the effect of grinding media on the floatability of pyrrhotite, rest potential and galmic current measurements were made on electrode combinations of pyrrhotite-mild steel and pvhotite- stainless steel. Galvanic contact of pyrrhotite with mild steel increased the rate of surface reactions on pyrrhotite in air-exposed and oxygenated solutions. It was postulated that the formation of an iron hydroxide coating on the pyrrhotite adversely affected its floatability. Its formation was minimal when pyrrhotite was contacted with stainless steel. Fine magnetite particles cawed slime coating on pyrrhotite surfaces by magnetic interaction and impaired the flotation of pyrrhotite.

Jan 1, 1983

By R. Poulin, A. Lamontagne, N. Tassé

This paper presents the results of a laboratory investigation aiming to verify the concept of co-mingling of waste rock with layers of compacted tailings. Overall, co-mingling is expected to delay the onset and reduce the magnitude of acid mine drainage (AMD) production in waste rock. To denionstrate the efficiency of the method proposed, five different column tests have been set-up. Columns were fed with deionized water at the top and drainage waters were collected and analyzed. Bacteria counts were done on the tailings and waste rock after the column tests. Permeability in saturated conditions and capillary parameters were measured for the tailings. The results obtained show that the co-mingling method would be effective in mitigating AMD by maintaining nearly water-saturated conditions in compacted tailings, thus reducing oxygen supply in waste rock by preventing thermal air convection and minimizing oxygen advection and diffusion.

Jan 1, 2000

By S. S. Vasan, K. A. Natarajan, J. M. Modak

The biological removal of calcium from a bauxite ore in the presence of the soil bacterium Paenibacillus polymyxa is demonstrated. A column bioreactor that can be either operated in a fluidized-bed (FB) mode for coarser particles or in a total-recycle-slurry (TRS) mode for finer particles was designed, fabricated and tested for this purpose. For the efficient removal of calcium from the ore to the required levels, leach solution should not be allowed to accumulate in the reactor. Therefore, the solution needs to be drained out periodically. Cascade leaching was found to be more effi¬cient. A direct correlation between pH changes in the leach solution and calcium solubility could be made. More than 85% of the calcium could be removed through cascade leaching.

Jan 1, 2000

By Farzad Mohammadi, Patrick Littlejohn, David Sanguinetti

Arsenic levels in metal concentrates are increasing as mining companies turn to developing low grade and complex ores. When arsenic bearing minerals are smelted, arsenic deports as gases which must be neutralized by a scrubber system. The resulting scrubber effluent is high in dissolved arsenic and requires treatment before the wastewater can be discharged or re-used. Conventional arsenic removal relies on lime addition followed by calcium arsenate formation and precipitation as hydroxides. As an alternative, arsenic removal with sulphide precipitation is receiving more attention due to potential advantages of the technology. Process streams high in arsenic often contain concentrations of dissolved metals that may be selectively recovered during sulphidization, producing a product that can be reprocessed and reducing waste generation. This paper will review laboratory testing completed for arsenic removal through sulphide addition and precipitation of arsenic (III) sulphide in combination with metals recovery to offset arsenic removal costs.

Jan 1, 2014

By F. G. Miller, M. Polat, S. Chander

Flotation was used to achieve improved separation of magnetite from the float and sink products obtained from heavy medium separation and to reduce the load of the medium cleaning circuit. The investigation was carried out in two successive phases. In the first phase, tests were performed on in-plant samples from the Homer City Coal Perdition plant to determine what effects variables such as medium density, particle size and magnetite source had on the efficiency of the process. In the second phase, the optimum conditions determined in the first phase were used to determine the applicability of the process to other selected coals from central Pennsylvania. It was observed that flotation was very effective in the separation of magnetite from coal. In most of the cases investigated, the magnetite recovery was approximately 99% with a magnetite grade ranging from 95 to 99%. The grade of the magnetite decreased as the ash content of the coal increased and the particle size of the magnetite decreased.

Jan 1, 1994

By Robert A. Campbell, Robert J. Brison

The problem of optimizing from an economic standpoint the capacity of grinding equipment in the design of a new concentrator is discussed. Although directed specifically to copper flotation mills employing conventional wet, grinding, the material presented is considered applicable with modifications to other types of ores and other grinding methods. A general approach to optimizing the grinding capacity is outlined and illustrated by an example. The' interrelation between grinding capacity and other aspects of the project is considered. The problem of regrind capacity and its relation to preceeding and subsequent processing steps is also discussed. Finally, factors are considered that may, in certain cases, dictate modifications of the suggested approach.

Jan 1, 1974

By Bernard Lallement

INTRODUCTION Geostatistics have been used for five years at the B. R. G. M. to compute the ore reserve estimation. At present this technic is also used at the beginning of the exploration project to determine the best way to prove the orebody. The best way is a compromise between the cost of the exploration and the precision of the estimation. It is clear that geostatistics cannot be used without any data, but very often an exploration project is decided on an orebody which has already been drilled. Old data can therefore be used. This was the case this year for two orebodies: an iron deposit and a lead deposit. The iron deposit was explored by drifts and has now to be proved. We used geostatistics to determine the best drilling pattern. The variograms computed with these old data showed that an anisotropy existed between the two directions of the orebody, which meant that the drill pattern had to be rectangular. The lead deposit was explored by drill holes and a short drift in part of the orebcdy. The problem was to choose between a regular pattern of drill holes or a long drift and some added drill holes. The case of this study will be exposed afterwards. On the other hand, if the orebody is completely unknown, the exploration project generally forecasts two exploration steps (the first step

Jan 1, 1977

By R. McEwen, G. W. Hansen, G. F. Lee

The effect of using an anionic collector, Reagent 308, a sodium petroleum sulfonate, with a cationic collector, Armac T, a tallow, fatty acid amine acetate, was studied in a series of monomineralic flotation trials with the alkali feldspars and heavy minerals, ilmenite, rutile, garnet, and monazite. This combination of cationic and anionic collectors is employed to float feldspar and heavy minerals from quartz in the beneficiation of sand in Normanville, South Australia, to produce a suitable quartz sand for glassmaking. In the alkali feldspar trials, Armac T additions were held constant, while the 308 additions were varied. In the heavy mineral trials, the 308 was held constant while the Armac T was varied. Peak enhancement of the feldspar recovery was noted when the 308 additions were between 25% and 150% that of the Armac T additions. At higher 308 addition, depression of feldspar flotation occurred. This appears to be due to a neutralizing effect in the combined collector system and to the formation of a nondissociating complex of both collectors. This variability in flotation response when Armac T is used with 308 suggests that the two collectors do not act independently of each other.

Jan 1, 1977