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By K. E. Waters, J. E. Nesset, F. Rosenblum, J. A. Finch

An advanced laboratory-scale weathering apparatus has been developed at McGill University to study the effects of weathering (ambient temperature oxidation) on the self-heating of sulphides. Previous work by the authors has shown that the problematic self-heating of sulphides is inherently linked to the degree of oxidation (weathering) of the minerals: un-oxidized active sulphides exhibit little or no self-heating while the same material when weathered can generate extensive self-heating bringing temperatures well above 100 0C. In this study the effects of environmental conditions (weathering time, ambient temperature, sample moisture, relative humidity, and oxygen content) were evaluated with respect to the self-heating response of a pentlandite-pyrrhotite nickel sulphide concentrate.

Jan 1, 2015

When it comes to processing industries, speed matters. More precisely, the faster/greater the throughput of finished product out the door, the more quickly money can flow back into the corporate coffers. In this quest for greater output, no processor can afford any weak links in the chain. Especially in the case of bulk solids operations, any one piece of equipment that slows the process down jeopardizes the profitability of the entire plant. However, one clay processor uncorked a pre-existing bottleneck by replacing its outdated separating equipment with a new design that immediately improved output.

Jan 1, 2007

By John D. Bardill

A cooperative project between the Bureau of Mines, Department of the Interior, and the Montana School of Mines, investigating results of hydraulic systems for transporting sand slurries for emplacement, was begun in August 1955. In such circumstances, the Bureau provides funds for a fellowship leading to a Master of Science degree as well as available instruments, tools, supplies and equipment. The School provides the ore-beneficiating laboratory with its equipment for use as a pilot plant. The success of a hydraulic backfilling method employing mill tailings depends largely upon the physical characteristics of the tailings. One of these characteristics is size distribution, especially in the finer size ranges. When being emplaced underground, almost impervious layers of slimes separate from some types of mill tailings containing a high percentage of slimes and settle on the top of the sand fill. These coatings may be so dense that the water in the slurry cannot percolate through them for proper drainage. Successive layers of fill in a stope, each with an impervious coating on top, sometimes build up a hydrostatic head, creating pressure on the bulkheads. This may cause breaks in the lining material, inducing sand runs and flooding the level and sumps below. Deleterious slimes flocculated and disseminated throughout the sands should help prevent the formation of impervious slime layers, increasing percolation and settling rates.

Jan 1, 1960

By Jack E. Fraley

In this Bureau of Mines study, sealants containing mineral wool, cement, etc, were sprayed through dry-process equipment that propels dry material pneumatically to the water-adding nozzle. Advantages over slurry applications include no mixing, no extensive cleanup, and freedom from hardened cement in equipment should power be lost. Sealants with large mineral wool nodules (>l-inch) were sprayable at rates to 900 square feet per hour for 1/2-inch thickness with little dust and smooth material flow through equipment, but they were weak for mine use, Materials containing small wool nodules (1/4-inch) were stronger but tended to plug lines because the nodules were inadequately separated in the shredder. Increasing the dedusting oil also increased line plugging by holding the nodules together in larger lumps. Best results were obtained using a 3/4-inch-nodule wool with cement binder, which provided both smooth flow through the machine and adequate strength.

Jan 1, 1977

Jan 1, 1885

By Sir Stopford Brunton

Gold was first found in Nova Scotia about 1830-40, but its significance at that time was not appreciated. Probably the first discovery that resulted in any work was made by Lieut. C. !'Estrange, at Mooseland, on the Tangier river, in 1858.1 Since that time gold has been mined with varying success until now, and from 1868 onwards work has never altogether ceased. Gold mining in Nova Scotia is at the moment under a cloud, and the idea generally accepted by most people is that it has failed in the past, and that there is no prospect for it in the future. The actual reasons for the present situation have never been carefully analysed, and it seems a good thing to see what really is the state of the case and whether or not this general idea is worthy of credence. It is the purpose of the present paper to analyse the situation in the light of present knowledge, and to set forth some data which may assist in the future development of the Province.

Jan 1, 1926

By W. Mark Hart

The current Automatic Data Acquisition system developed by some support manufacturers make it possible to monitor and record changes in leg pressure, DA RAM stroke in every shield and shearer position at any moment during mining operation. But how can these massive data (more than 1 MB for every 3 hrs for the current scanning option) be effectively used for improving production and maintenance management as well as providing better roof control at a longwall face? The research currently conducted jointly by WWU and Cyprus Amax Minerals at Emerald Mine and Twentymile Mine attempts to answer this question and make the data, especially leg pressure, more meaningful. A computer software package has been being developed to (1) determine mining cycles, cycle time, face advance rate, production rates, machinery delays, and production delays for each shift; (2) identify defective sensors, check valves, yield valves, by-passing leg and DA RAM cylinders, and other hydraulic and electrical abnormalities; (3) determine the roof weighting period; (4) evaluate the performance of the current shield support design - demand relationships; and (5) predict and overcome ensuing encroaching problems and roof conditions ahead of the face.

Jan 1, 1994

By C. Liliane Carvalho

In the current study, bio-oxidation tests were carried out in shaking flasks with a flotation concentrate containing the sulphides pyrite, arsenopyrite and gudmidite. The tests were performed with mesophilic microorganisms (At. ferrooxidans) at 30 °C and also with the moderate thermophile S. thermosulfidooxidans, at 50 °C. The effects of (i) previous adaptation of the microorganisms to the concentrate, (ii) ferrous iron concentration and (iii) pulp density (2%, 4% and 6% (w/v)) on the dissolution of the sulphide were studied through arsenic extractions. S. thermosulfidooxidans was more sensitive to the pulp density in comparison to At. ferrooxidans as a reduction in sulphide oxidation was observed with the increase in the solid content to 6%. Therefore, the mesophilic strain was selected for further work, which comprised a rolling bottle experiment at 10% solids. After 40 days of bio-oxidation, the solid material was subjected to cyanidation, which revealed 85% gold extraction as compared to 21% from the original concentrate. The antimony sulphide grains in the bio-oxidized product showed similarity to what was observed in the original sample, suggesting such particles were not susceptible to the bio-oxidation process.

By Robert C. Bates

Published information on costs of radon daughter control in uranium mines was analyzed to develop estimates of the cost per ton for any level of radiation exposure control. All data were converted to 1967 cost of living index to provide a common analysis base. Re- of the analysis show that the cost per ton increases exponentially as the radiation level is lowered. A linear relationship with the cost of living index is assumed, and equations and graphs are provided to estimate control cost per ton for any exposure control level and cost of living index.

Jan 1, 1982

By Willard J. Tesch

The borehole surveying system described is used to measure ground movement over and near operating mines. The magnitude of any movement is con-trolled by the ground conditions, the mining method, and the mine progress. By correlating these factors with the measured movement, equations can be determined for predicting the effect of mine progress on the surrounding ground. These equations can also be used to predict the effect of mining a similar deposit with similar ground conditions. The borehole surveying system is used in cased boreholes to measure the inclination of the hole in two perpendicular planes. Grooved casing with an inside diameter of 3 inches is grouted in the hole. Two probes are used to obtain the data necessary to calculate the hole position versus depth. One of the probes contains a gyroscope, and the other contains a biaxial force-balance [s]ervoaccelerometer. Readings from the transducers in the probe are punched on paper tape by an automatic data acquisition system as the probe is pulled up the hole at 30 feet per minute by an electric winch. Readings from the inclinometer probe containing the accelerometer are used as input data to an on-line programmable calculator as they are punched on tape. The calculator computes preliminary results of the survey being made. The paper tapes obtained during the survey runs are later used as input to a computer that computes the offsets of the drill hole versus depth in true north-south and east-west planes. These offsets are printed for each foot of depth. Changes in these offsets between the first survey and subsequent surveys are a measure of the horizontal ground movement between the surveys.

Jan 1, 1976

By E. T. Turkdogan, Klaus Schwerdtfeger

OelSEN and Maetz1 detected some 20 years ago the existence of a miscibility gap in iron oxide-CaO-P2O5 slags melted in iron crucibles at about 1400°C. Because of the importance of this system for the dephos-phorization of steel in the basic Bessemer process, equilibria between liquid iron and selected iron oxide-CaO-P2Q slags have been measured since by numerous investigators.2-5 When in equilibrium with metallic iron, the iron oxide of the slag is present mainly as FeO. In connection with oxygen-blowing steelmaking processes, it is useful to know the phase relations in the slag system at higher oxygen pressure, when major parts of the iron oxide are present as Fe2O3. This problem was investigated by Turkdogan and Bills7 by equilibrating the oxide mixtures contained in platinum crucibles with CO2-CO mixtures at 1550°C. It was found that increasing the Fe2O3 content decreases the composition range of the miscibility gap strongly so that the miscibility gap has almost disappeared at pco2/pco = 75. This result was refuted by the careful work of Olette et a1.,''' who equilibrated their slags with controlled Ha-H2-Ar gas mixtures. Their equilibrium measurements, at 1600°C and at oxygen pressures of 5 x 10"* and 10"5 atm, showed that the oxidation state of the iron has almost no influence on the formation of the miscibility gap. The present experiments were undertaken to check the previous results of Turkdogan and Bills. The experiments were performed at 1625°C in the strongly oxidizing atmosphere of air (PO2 = 0.20 atm) for which no experimental data are available. About 10 g of slag were melted in platinum crucibles and held at constant temperature for 1 hr. After equilibration, the crucible was rapidly pulled out of the furnace and cooled in air. The platinum crucible was removed from the sample. The two slag layers were carefully separated with a small diamond disc, and the surface of the top layer, which may have changed its oxidation state during cooling, was removed. The slags were crushed and analyzed chemically for CaO, P2O5, Fe2+, and Fetotal. The starting mixtures were prepared by sintering the desired amounts of reagent-grade 2CaO . P2O5 - H2O, CaCO3, and Fe2O3. Sintering and subsequent crushing were done three times to ensure homogenization. Molybdenum wire resistance heating was used. The furnace was provided with a recrystallized alumina reaction tube which was left open to air at the top. The temperature was controlled electronically. The reported temperature was measured with a Pt/Pt-10 pct Rh thermocouple and is estimated to be accurate within +5°C. The composition of the equilibrated melts is given in Table I. For the graphical illustration of these quaternary slags the type of projection suggested by Trömel and Fritze10 was used. In this representation, Fig. 1, the composition point of a mixture within the tetrahedron Fe2O3-CaO-P2O5-FeO is projected into the Fe2O3-CaO-P2O5, triangle (triangle I) so that the direction of projection is parallel to the side FeO-Fe2O3, and into the triangle Fe2O3-P2O,-Fe0 (triangle 11) so that the direction of projection is parallel to the side CaO-P2O5, of the tetrahedron. The projected point has the coordinates wt pct CaO, wt pct P205, and wt pct (FeO + Fe2O3) in triangle I and wt pct FeO, wt pct Fe2O3, and wt pct (CaO + PzO5) in triangle 11. Both triangles are turned into the same plane around the Fe203-P20, side of the tetrahedron. An illustration of the projection of a quaternary point in the present system is shown in Fig. 1. The advantage of this type of projection is that all four components for an equilibrium curve can be read directly from the diagram. The present results are shown graphically in Fig. 2. The curves depicting the miscibility gap are dashed in parts where no experimental points were obtained. The composition range covered by the miscibility gap

Jan 1, 1968

By T Kitajima, T Kawaguchi, T Nakamura

Carbothermic reduction of iron oxide is an attractive mechanism to produce metallic iron, since it can directly utilise coal as both reductant and fuel. To improve energy efficiency and productivity of the metallic iron production based on this mechanism, the combustion bed process packed with the composites of iron oxide and coal powder was experimentally evaluated. The process has a potential of high heat efficiency since it can automatically utilise the heat of reduced materials as that necessary to the subsequent reduction of the composite by a large heat exchange rate between the packed particles and gas flowed across the bed. However, it is hard to perfectly prevent the reoxidation of formed metallic iron in the bed. The present paper reports the effect of coal content, pellet size and so forth on the reduction/metallisation degrees of the samples after the reduction experiment. It also discusses the effect of pretreatment of the composite pellets using CaO bearing materials to suppress the reoxidation of formed metallic iron in the bed.

Jan 1, 2000

By Amy B. Cerato, Shawn Allred, Tatiana Vargas

"Helical piles are deep foundation elements that resemble, and are installed like, a large steel soil screw — they have a slender steel shaft with one or more round helix bearing plates welded to the shaft to provide support to the structure they hold. Helical piles are rotated into the ground with a large torque motor and provide support through soil bearing on the helix bearing plates and along the shaft. The piles are available in many lengths and, due to their small footprint along with their ability to create minimal disturbance to surrounding structures, they are often used in urban settings for foundation repair, retrofitting existing buildings and for new construction projects. Helical piles are routinely installed as foundation elements in seismically active areas, such as New Zealand, Japan and the U.S.Anecdotal observations (e.g., from New Zealand, Japan and the U.S.) have shown that piles with a comparatively small cross-section and high anchoring capacity, such as helical piles, are beneficial for seismic resistance. This is presumably due to the pile’s slenderness, higher damping ratios, ductility and resistance to tipping uplift. In New Zealand, it was observed that helical pile foundations fared much better than driven and drilled concrete piles after the 2011 Christchurch earthquake. In a personal communication, Woods (2016) described that, out of the 300 structures in center city Christchurch that were supported by helical piles, fewer than 10 structures suffered significant structural damage. However, many structures supported by driven and drilled concrete piles were damaged to such an extent that they were condemned and subsequently demolished."

Jan 1, 2017

By J. Drelich

The wetting behavior of liquid polymers at solid surfaces and the adhesion forces involved at polymer-filler interfaces should always be considered in the fabrication of high quality polymer composites, including those made with mineral fillers. Spontaneous polymer spreading over the filler surface is a basic condition in the fabrication of the polymer-mineral composites. In this regard, the wetting and adhesion characteristics of polymer-mineral systems are reviewed in this contribution. It appears that several aspects of wetting phenomena at mineral filler surfaces are not well described in the literature and require further systematic study. Specifically, it is clear from this review that efforts should be made to determine the effects of mineral surface contamination (including surface hydration) on wetting and adhesion phenomena, and to determine the wetting characteristics of molten polymers at mineral filler surfaces. It is expected that any improved fundamental understanding of wetting and adhesion phenomena for the polymer-mineral composites will provide the basis for further technological development.

Jan 1, 1995

By R. R. Knuckey

HAVING been associated with the operation of the de Vooys process for coal, which has treated 13,000,000 tons per annum, and recognizing the process as of value in ore sorting, Huntington, Heberlein and Co. Ltd. (Great Britain) in 1936 made an examination of all other existing methods. In none of the pioneer applications had recognition been given to the necessity for maintaining certain conditions that are essential for sorting certain ores if a truly efficient separation by gravity alone is to be assured. Consequently, in 1936-1937 Huntington, Heberlein and Co. Ltd., with Pearson, employing certain ideas connected with the de Vooys application, commenced the development of a separator that would allow conformance with optimum conditions in the zone where separation is effected. Later, Holt and Wade added to the value of the original application by Wuensch, Rakowsky and others, whose conceptions are being successfully operated today. Meantime, Trostler had enhanced the value of the original H-H. process by improvements that are now embodied in operating plants, and today the process incorporates an improved apparatus and a stable medium that produce the optimum conditions for separation. These conditions are: 1. Elimination of disturbing currents in the separating zone; 2. Reduction to a minimum of medium-density differences throughout. the separating zone; 3. Stable medium of minimum viscosity to permit the unretarded fall of mineralized particles; 4. Removal of products of separation with minimum disturbance to the separating zone. DESIGN OF SEPARATOR The H-H. sink-and-float separator consists of a pyramidal tank in which the separation actually takes place, connected at the bottom with an inclined bucket elevator. The tank and the elevator are filled with medium to within a few inches of the top of the tank. Medium is fed into the separator at a variety of points, according to the type of ore being treated, and it is withdrawn from the separator at two points: (1) together with the float product, by means of a variable-speed paddle, at the surface of the medium, and (2) by flowing over an adjustable weir cut in the side of the elevator casing. The prepared ore is fed onto the surface of the medium. The intermediate paddles, which revolve at a slow speed of 2 to 5 r.p.m., move the floating ore across the bath from feed end to float-discharge end. The ore, which is heavier than the medium, sinks below the sweep of the paddles and reaches the boot of the bucket elevator, which discharges it without disturbance of the separating zone. These arrangements for withdrawing medium from the separator allow the use of minimum flows, which connote minimum

Jan 1, 1943

By R. V. Higgins

The Bureau of Mines investigated the use of electronic computers for obtaining more information about relative permeabilities of reservoir rock to oil and water. It was found that there are many possible combinations of relative permeability curves that will result in virtually the same recovery versus injection) but they require different times and rates to recover the oil even with different mobility ratios. Permeability curves obtained by the use of non-viscous oil and employed for calculating the waterfloods of viscous oils can lead to serious inaccuracies. For viscous oils) the wettability characteristics in the middle portion of the permeability curve affect recovery nearly as much as other portions of the curve; this) however) is not true for non-viscous oils in water-wet reservoir rock.

Jan 1, 1967

By Lownds C. M

Several classes of commercial explosives and blasting agents behave non-ideally, especially in diameters near their critical diameter. A direct and convenient measure of non-ideal behavior is the detonation velocity (VOD); if the VOD is less than the ideal value, usually obtained by calculation, then the explosive is detonating in the non-ideal mode. Such lowering of the VOD is usually due to both lateral loss of energy and post-CJ release of energy. The second of these factors, namely slow release of chemical energy, is of most interest in blasting. While the observation of a low VOD clearly suggests slow reaction of part of the explosive composition, it does not necessarily mean that the energy is lost to the overall rock-breaking process. The partition of the energy of the explosive into various useful and wasteful categories is considered. Simple models of energy partition in blasting, and of explosive reaction kinetics, are presented. The models consider the effect of explosive type and rock type, the explosive being described in terms of the most common phases namely liquid, air bubbles, porous ammonium nitrate, dense or crystalline ammonium nitrate, and aluminum. Over a range of combinations of the above phases, the model predicts reasonable critical diameters and VOD's. Results are presented which show the effects of non-ideal detonation on fragmentation and heave in different rock types. Conclusions are drawn about those blasting conditions in which ideal behavior is beneficial, or Disadvantageous.

Jan 1, 1990

By M. Ksiazek

Keywords: Thermal conductivity, thermal diffusivity, flash method, specific heat capacity, manganese ore Manganese ferro-alloys manufacturing involves a combination of quality raw materials and an energy source to produce high-quality products with low energy consumption. The thermal properties of manganese raw materials such as ores, sinters, and briquettes, are among the many factors that determine the amount of energy needed for processing. Thermal expansion, thermal diffusivity, conductivity, and apparent specific heat capacity of solid samples and compacted powder samples of manganese ores were examined from room temperature to 1000 °C. The effect of porosity (of the materials used) on the thermal properties was also investigated. The laser flash method and a pushrod dilatometer were used.

Jan 1, 2011

By E. Goodwin

"Maclaren Forest Products Inc.Lime is commonly used for the neutralization of acid, and the removal of heavy metals in mine waste waters. However, the precipitation of heavy metals as hydroxides must take place under conditions of controlled pH, to produce minimum concentrations of dissolved metals. An account is presented explaining the concepts applied to lime-treatment processes at Bell Mine during the period of a supernatant discharge to Babine Lake; October 18, 1982to January 25, 1983. IntroductionBell Mine of Maclaren Forest Products Inc., Babine Mining Division, an open-pit copper mine, is located on Newman Peninsula, Babine Lake approximately 65 kilometres northeast of the town of Smithers, British Columbia (Fig. 1).A depressed market for copper metal in 1982 forced a management decision to suspend operations at the mine for an indefinite period from October 3 I, 1982. For some time prior to the mine closing date, mine management was concerned about the increasing level of supernatant in the tailings pond , and its possible effects on the stability of the dam when cycloning of mill tailings ceased. Consideration of these potential hazards led to an application being filed with the Provincial Waste Management for a permit to discharge the excess water to Babine Lake. This large lake, an important link with several significant salmon spawning sites, is a major contributor to the British Columbia commercial fishing industry. Jurisdiction for the environmental affairs in the area is shared by the Department of Fisheries and Oceans, the Environmental Protection Service, and the Provincial Waste Management Branch. These agencies were directly concerned in the formulation of discharge permit following joint consultation, and exchange of information with the company on environmental concerns. An approval was finally granted to discharge approximately 1,000,000 cubic metres of supernatant from the tailings impoundment at Bell Mine into Hagan Arm, Babine Lake from October 18, 1982 with a daily discharge not to exceed 9000 cubic metres. Provisions were made that a particular discharge procedure be followed, and that the company would be responsible for setting up a sampling and monitoring program to safeguard the quality of the effluent."

Jan 1, 1986

Jan 1, 1931