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By John R. Koehler

Available barrier pillar design methods do not adequately account for overburden caving characteristics, the timing and magnitude of associated load transfers, the occurrence of unusual geologic features, or the effects of multiple-panel/multiple-seam mining. To address this problem, the Bureau of Mines, in cooperation with Cyprus Plateau Mining Corporation, conducted a barrier pillar study in a multiple-seam mine setting. Insufficient barrier width resulted in excessive load transfer to an adjacent/underlying section. Consequent entry and pillar deterioration resulted in the section being prematurely abandoned. This paper proposes an approach based on in situ measurements, which includes mine-specific loading conditions in the barrier design process.

Jan 1, 1989

By Jilai Xue

Oxygen gas bubbles generate on anode during Pb electro-deposition process in PbSiF6-H2SiF6 aqueous solutions at room temperature. Cell voltage varies as the bubbles formed on the anodes surface. The bubble layer on the anode makes a voltage drop that consumes energy in the Pb process, which can be reduced by applying ultrasound on the anode. The effects of ultrasound frequency and anodic current density were investigated with ultrasound on and off, alternatively during the Pb electrode-position process. The removing of the gas bubbles were recorded in association with a drop in the cell voltage. The cell voltage can be lowered by 4% - 6% with ultrasound, which has potential for energy saving in Pb production.

Jan 1, 2010

Effect of Hydrophobicity and Frother Concentration on Bubble-Particle Interactions in Turbulent Flow

Sep 13, 2010

By George A. Roberts, Arthur H. Grobe

H. H. Hausner (Sylvania Electric Products Inc., Bayside, N. Y.)—I tested the 18-8 stainless steel powder described by Grobe and Roberts and the results were excellent. The powder was compacted and sintered in purified hydrogen to a very low density (approximately 20 pct and more porosity). Where the other powders show very little ductility when sintered to such a low density, the described stainless steel was surprisingly high in ductility. I would appreciate it if the authors could give us some data on a similar powder but without silicon and also data on 430 stainless steel powder. H. S. Kalish (Sylvania Electric Products lnc., Bay-side, N. Y.)—I should like to verify the excellent results obtained by Grobe and Roberts with their pre-alloyed stainless steel powder. It seems to me, however, that their data are conservative and that even better densities and higher tensile strength can be obtained with these powders by the selection of proper particle size fractions. The accompanying data were obtained by sintering compacts pressed from the powder made by Vanadium-Alloys Steel Co. to 0.8 in. in diam about % in. high in a cylindrical double action die without the use of lubricant. The compacts were sintered for 1 hr at 2370°F in hydrogen purified by passing it through a Deoxo unit (palladium catalyst) and a Lectrodryer. Even the density obtained using the as-received (—100 mesh) compacted at 40 tsi was quite high as was the hardness. This indicates that by increasing the sintering temperature slightly above 2350°F the coining and subsequent secondary sintering operation can be avoided. With the — 325 mesh fraction, however, very much higher density can be obtained and a high hardness. I have no tensile data to present, but I feel that it is not too optimistic to expect. that unusually high tensile strengths and good ductility can be obtained in this sintered material on the basis of the density and hardness data. The sintered stainless steel made by the above-described methods came out of the furnace very bright and clean. The purified hydrogen atmosphere is important in sintering stainless steel to reduce the oxide present in the powder. The result of such a sintering is good densification and good ductility of the sintered product. G. A. Roberts (authors' reply)—We are greatly indebted to Messrs. Hausner and Kalish for their discussions of our paper. Their encouraging remarks are greatly appreciated and their confirmatory data will do much to add to the value of the paper. At the present time it is impossible to provide complete data on a similar stainless steel powder without silicon, but we do know that, in general, the properties are slightly inferior. Data on such a powder and on other stainless steel types are to be published in the near future.

Jan 1, 1952

By K B. Holm

This paper deals with the advances made at Syferfontein Colliery in the calculation and control of dragline methodology. The high capital outlay and operating cost of a dragline necessitates strict control of all aspects of the dragline operation. Before purchasing a dragline, a complete evaluation of all the parameters that can affect the viability, now and in the future, of the dragline operation needs to be completed. Such parameters as thickness of burden, material properties (swell), “castability”, pit width and pit length, etc. need to be considered.

Jan 1, 1994

By John E. Tilton

Real copper prices during the past several decades display two striking characteristics. First, they are highly volatile. Within a year or two, copper prices can rise or fall by 30% or more. Second, over the longer term, they are falling. Indeed, since 1970, the secular trend price for copper is down by more than 50%. Figure 1 highlights both of these characteristics. It shows the average annual US producer price for copper since 1970 measured in constant 2001 US dollars. While the London Metal Exchange (LME) copper price is not shown, it and the US producer price have for some time moved more or less together. So pronounced short-run fluctuations around a significant long-run decline describe copper prices, not only in the United States, but around the world.

Jan 1, 2002

By Kenji Koga

In order to derive the population distribution of gold nanoparticle morphologies as a function of size, highresolution electron microscopic (HREM) observations and structural analyses were done for over 4000 particles (3-18 nm) grown by an inert gas aggregation (IGA) source using helium. To obtain structural features threedimensionally and not to skip high-contrast images, twenty photos were taken for each particle by changing tilting angle of a specimen holder in combination with the through-focus procedure. For the reliable structural determinations, HREM images and their tilting sequences were directly compared with multislice-simulation results for icosahedral, decahedral and face-centered cubic morphologies, and finally the population distribution of each morphology was obtained as a function of size. In the present sample, icosahedral particles were dominantly populated over the whole observed size range and decahedral particles with non-spherical truncated bi-pyramid shape were secondly dominant. Even though a large number of sampling has been done, few crystalline particles were observed.

Oct 1, 2003

By Laurance L. Oden

The Bureau of Mines is developing nickel catalysts for converting synthesis gas derived from coal to synthetic natural gas. The present report describes the relationship between the composition of aluminum-nickel alloys in the composition range NiAl3 to Ni2Al3 equilibrated at 840° C and the properties of catalysts obtained from them. Methanation activity was determined in the temperature range of 300° to 360° C in a flowing gas stream containing 1 pct CO, 8 pct H2, and the remainder He. One part per million of H2S was added to the gas stream at 400° C to evaluate the susceptibility of catalysts to sulfur poisoning. The total surface area was measured by the adsorption of nitrogen at liquid nitrogen temperature, and the active surface area was measured by the adsorption of hydrogen at room temperature. Total surface area and active surface area were found to increase with increasing proportion of aluminum-saturated Ni2Al3 in the precursor alloy, but methanation activity and resistance to poisoning by H2S were nearly constant. However, the methanation activity of the catalyst prepared from stoichiometric Ni2Al3 was less than half that of the other catalysts.

Jan 1, 1978

By Frederick H. Raab

A power-line proximity-warning (PLPW) system must have a high probability of detection (alarm activation at a specific distance), low probability of false alarm, and minimal set-up and maintenance. Tests of electric-field sensors have not demonstrated a dependable alarm distance. Alternative sensing methods such as microwave radar, optical radar, and sonar can meet the requirements by direct measurement of the range from the boom to the power line. Suitable microwave techniques include RF pulse, chirp FM/CW, and baseband pulse. Baseband-pulse radar has adequate range capability and does not require expensive microwave components. The radar cross section of a power-transmission cable is adequate for its detection optical-radar systems based upon LEDs and photodiodes are inexpensive, but can achieve only marginal performance in this application because of their limited modulation bandwidth. Since laser diodes and cryogenically cooled photosensors must be used to achieve the desired range resolution, the cost of an optical-radar system is greater than that of a microwave radar system. Sonar systems are feasible, but are not as precise and cost at least as much as baseband-pulse-radar systems. The performance of both optical-radar and sonar systems is degraded by dirt, necessitating the inclusion of a "windshield wiper.' Baseband radar appears well suited to the PLPW application. The cost of a baseband-pulse radar PLPW system is expected to be comparable to that of an electric-field PLPW system. Development and testing of an experimental model are therefore recommended.

Jan 1, 1982

By Vidyaranya Bandi, Madhav Madhira, Kota Vijay Kiran

"Using hyperbolic relationships for the non-linear responses of shaft and base resistances, a method is proposed for estimating initial shaft and base stiffnesses and ultimate shaft and base resistances of a pile from pile load test results. An iterative procedure is used to arrive at the values of shaft-soil and base stiffnesses and the ultimate shaft and base resistances. The method is applied to load - displacement data available from pile load test results to illustrate its efficacy.INTRODUCTIONA pile foundation is the most effective and economical solution in transferring large vertical loads to deeper depths. As the pile is subjected to axial load, the soil mass surrounding the pile is vital in providing vertical support for the pile. The nature of pile–soil interaction is three dimensional and to complicate the problem further, response of soil is nonlinear. Finding a closed form solution to such problem is extremely difficult. Several methods were developed to study and predict the response of the composite pile–soil system. Faruque and Desai (1982) implemented both numerical and geometric non-linearities in their three dimensional finite element model. Rajashree and Sitharam (2001) developed a nonlinear finite element model of batter piles under lateral loading using a hyperbolic relation for static load condition and modified hyperbolic relation, including degradation and gap for cyclic load condition.The ultimate capacity of the pile is estimated considering the strengths and unit weights of soil layers with depth, overburden pressure and other relevant parameters. The estimated capacities always need to be validated by conducting initial maintained load test. The estimated capacity may differ with the actual at site since the values of strength, stiffness, interface resistance between pile and soil, lateral earth pressure coefficient with depth and soil stratification, etc., differ from the design parameters considered for estimating the ultimate capacity of pile. The estimation of axial capacity of piles involves considerable uncertainties in selection of appropriate design parameters and the design rules are not always consistent with the installation procedures/processes involved."

Jan 1, 2017

By Alvin J. F

Tin in ores containing 0·025 to 1·5 per cent tin can be determined polarographically by the reduction of the chlorostannite ion at the dropping mercury electrode in 2M hydrochloric acid solution containing 15 per cent ammonium chloride. The tin is separated from interfering elements by distillation as the tetrabromide and collected from the distillate by co-precipitation with aluminium hydroxide. The method can detect 0·01 per cent tin in ore.INTRODUCTIONAn iodimetric method, suitable for routine analysis of titrating tin in concentrations down to 1 per cent, has been available for some years (Low, Weinig, and Schoder, 1939).As concentrations fall below 1 per cent tin, there is increasing difficulty in obtaining a distinct end point due to large amounts of iron and silica normally present after fusion of the ore. Since concentrations of tin down to 0·02 per cent are significant in ore dressing products it was necessary to examine methods to determine such low concentrations, and to adapt these to tin ores containing a wide variety of other minerals.EXPERIMENTALDigestion and separationCassiterite, the principal tin mineral, is refractory but readily attacked by a sodium peroxide flux to yield soluble sodium stannate. In a recognized procedure, a sample of ore is mixed with up to 15 g of sodium peroxide in an iron crucible and swirled over the full heat of a Meker burner for 7 min. The fusion is leached with water and acidified.This solution then contains tin, silica, and other soluble...

Jan 1, 1962

By J. F. Barkley

Smoke abatement is a subject of which fuel technology, although absolutely essential, is only a part. Its successful accomplishment starts and ends with human factors that must be given thorough consideration; between this "start" and "end" fuel technology is applied. Smoke abatement usually starts from the desire of some person or persons to be free from uncleanness caused by the stack of someone else and ends with the sincere desire of the operator of the fuel-burning equipment to maintain a clear stack. Although "smoke abatement been discussed for many years, it is only recently that the public has been mindful of such expressions as "air pollution" and "air hygiene." The subject has duel in common with that of supplying pure water but is more complicated. The public desires pure water, expects pure water, is willing to pay for pure water, and expects to continue to pay for it indefinitely; it is a development of civilization. It is doubtless correct to say, however, that people in general do not et realize the detriment of air pollution to their well-being or give the question enough serious consideration. This is illustrated by the fact that in city smoke abatement it is the mass of small householders that sins the most and is the hardest to handle. It is rather difficult to assemble a group of people in a room without the air becoming contaminated with smoke. Smoke abatement will lag with the lack of desire for pure air - probably the biggest human factor involved in its accomplishment.

Jan 1, 1939

By Thomas J. Peters

Tungsten, silver, lead, zinc, and placer gold occur in the Cucamonga B RARE II area (no. B5174). A strata-bound, scheelite-bearing zone at the Blue Diamond prospect (fig. 1, no. 1) contains an estimated 16,000 tons (15,000 t) of identified, subeconomic resources averaging 0.16 percent tungsten trioxide (W03). There is a high potential for discovering additional tungsten resources at this property. The California-Hercules prospect (fig. 1, no. 5) ha; a mineral occurrence which contains an estimated 1,000 tons (900 t) of tactite averaging 1.3 oz silver per ton (45 g/t), 0.75 percent lead, and 0.72 percent zinc. Another occurrence, at the Blew Jordam Prospect (fig. 1, no. 4) has an estimated 100 tons (90 t) of tactite averaging 10 oz silver per ton (340 ,/t), 3.75 percent zinc, and 2.3 percent lead. There is a moderate potential for discovering silver, lead, and zinc resources at these prospects, which are in metamorphic pendants. There are a few lode gold prospects in the area (fig. 1, nos. 3, 11, 14) are on geologic structures which parallel the San Andreas Fault, northeast of the area. These deposits are not well exposed and have been historically unproductive. Placer gold in area B occurs locally in the beds of intermittent tributaries to Lytle Creek (fig. 1, nos. 10, 12, 13) in concentrations as high as $1.17 per cu yd ($1.53/cu m, at a gold price of $450 per troy oz). The deposits have no significant volume, but could be utilized for recreational panning and suction dredging. In the Cucamonga C RARE II area (No. C5174) placer gold occurrences locally contain as much as $1.23 per cu yd ($1.61/cu m). However, gravel containing the gold appears to be limited to stream beds, and does not occur in sufficient quantity to constitute resources. Recreational panning and dredging also may occur in this area.

Jan 1, 1983

By B. Hart, J. Marois

"Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDX), and Time of flight secondary ion mass spectroscopy (TOF-SIMS)were used to analyze pyrochlore grains from Niobec froth flotation plant. Samples from the mill feed, pyrochlore rougher feed, pyrochlore rougher concentrate, and tail were analyzed in order to identify a potential relationship between pyrochlore matrix composition and selective separation. SEM-EDX analyses indicate that pyrochlore grains with high Fe content appear to be less recoverable than those with a lower Fe content and that the flotation response is related to matrix Fe rather than Fe occurring as inclusions. TOF-SIMS was used to analyse the surface of high Fe and low Fe pyrochlore, in order to identify a potential relationship between pyrochlore matrix composition and the related effect on cationic collector adsorption (tallow diamine). Surface analyses of pyrochlore from a conditioning test show that species indicative of the collector favour the surface of Fe poor pyrochlore relative to the Fe rich variety. The results from the conditioning test illustrate a negative relationship between collector loading and the presence of Fe and related oxidation species. This study identifies the link between pyrochlore matrix Fe content and, the presence of surface oxidation products, to collector loading. Poor Fe rich pyrochlore recovery noted in the Niobec froth flotation plant may be partially explained by this mechanism.INTRODUCTIONPyrochlore, the most abundant niobium containing mineral (Perrault and Manker, 1981) is economically recovered in Brazil, China, and Canada (Niobec) (Kouptsidis et al., 2008). Since 1974 Niobec has been extracting niobium from the St-Honorécarbonatite deposit. Niobec is the only operating Nb extraction facility in North American and one of the three major world producers of ferroniobium (Dufresne and Goyette, 2004; Belzile, 2009).Flotation is the preferred and most cost-effective method for pyrochlore recovery (Burks, 1958; Shapolov and Polkin, 1958; Zakharov et al., 1967; Razvozzhaev and Nikiforov, 1972; Bogdanov et al., 1973; Abeidu, 1974; Raby and Desrochers, 1975; Wilson, 1979; Biss and Nadeau, 1982; Biss, 1985). With the aim of optimising the flotation process for the Niobec ore, numerous experiments were performed on the influence of surfactants and type of water to optimise pyrochlore recovery and grade during flotation (Gomez et al., 1987; Rao et al., 1988; Dufresne and Goyette, 2004; Belzile, 2009)."

Jan 1, 2013

By Robert H. Peters

This U.S. Bureau of Mines report identifies the types of serious accidents that occur most frequently at small underground coal mines and describes the strategies that could help prevent these accidents. A wide variety of methods for improving safety are suggested, including improvements in the design of equipment, work procedures, work schedules, safety programs, and emergency response plans, as well as techniques for diagnosing the potential hazards associated with new technologies and work procedures. Some of the papers in this volume focus on preventing specific types of mining accidents--ones associated with materials handling (primarily back injuries), equipment maintenance, improper machine guarding, and ground failure during retreat mining. Although the recommendations in this volume are heavily influenced by research performed at underground coal mines in the Appalachian coalfields, most of the papers contain advice that is equally pertinent to almost any type of mine.

Jan 1, 1994

By Jiwen Zhang

Abstract Due to the blocking nature at the crusher station, straightforward application of queuing theory cannot give realistic results on the performance of a shovel-truck-crusher system. A new queuing network-based model has been developed in which, the crusher station is formulated into an open queuing network and the whole shovel-truck-crusher system into a closed queuing network with the crusher station as a special server. To fully account for the influence of blocking, Monte Carlo simulation is first used to obtain the performance parameters of the open queuing network for the crusher station. The closed queuing network for the entire system is solved by applying the Extended Summation Method (ESUM), in which the crusher server is described by the simulation results. The model has been applied to the Yuanbaoshan open-pit coal mine to analyze its shovel-truck-crusher system and to improve its efficiency. Results indicate that the blocking at the crusher is an important factor affecting the crusher output and in turn the efficiency of the whole system, and prove that the model can realistically describe the behavior of such systems.

Oct 1, 2009

By Jiwen Zhang

Due to the blocking nature at the crusher station, straightforward application of queuing theory cannot give realistic results on the performance of a shovel-truck-crusher system. A new queuing network-based model has been developed in which, the crusher station is formulated into an open queuing network and the whole shovel-truck-crusher system into a closed queuing network with the crusher station as a special server. To fully account for the influence of blocking, Monte Carlo simulation is first used to obtain the performance parameters of the open queuing network for the crusher station. The closed queuing network for the entire system is solved by applying the Extended Summation Method (ESUM), in which the crusher server is described by the simulation results. The model has been applied to the Yuanbaoshan open-pit coal mine to analyze its shovel-truck-crusher system and to improve its efficiency. Results indicate that the blocking at the crusher is an important factor affecting the crusher output and in turn the efficiency of the whole system, and prove that the model can realistically describe the behavior of such systems.

Oct 1, 2009

After considerable input from the mining industry, the Canadian Securities Administrators (CSA) finalised National Instrument 43-101: Standards of Disclosure for Mineral Projects. This Instrument, which became law across Canada on 1 February 2001, applies to all technical public disclosure on mineral projects and requires all technical disclosure to be based on the work of a æqualified personÆ (QP). While the QP is quite similar to the Competent Person in Australia there are important differences when it comes to all disclosure. This paper will summarise the main areas in which the Instrument introduces major changes to Canadian disclosure standards on mineral projects including the role and responsibility of the qualified person; the increased requirements to file technical reports; the incorporation by reference of the October 2000 CIM definitions of resources and reserves and additional rules governing written disclosure of scientific and technical information. In October 2001, eight months after the implementation of NI 43-101, the CSA compiled a list of frequently asked questions (FAQs) and CSA responses to assist mining industry participants and their advisors in understanding and applying NI-43-101. This document has been well received by industry. The CSA plans to update the FAQs when further guidance is requested. Two industry committees have been established to provide the CSA with technical advice on the application of NI 43-101. As recommended by the Ontario Securities Commission/Toronto Stock Exchange Mining Standards Task Force, the CSA has established an external industry advisory committee û the Mining Technical Advisory and Monitoring Committee (MTAMC) û to monitor the application of NI 43-101 and advise the CSA on industry and professional developments. The role of the CSA-Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Working Committee on Reserves and Resources is to ensure that the future changes and updates to the CIM Standards can be efficiently and effectively incorporated in NI 43-101. During this first year, the Canadian securities regulators have seen an improvement in the quality of disclosure on mineral projects, which will increase investor confidence in the industry.

Jan 1, 2002

By R. M. Owens, J. F. Lupo

The Shirley Basin Uranium mine, located in southeastern Wyoming, USA, was an open pit mining operation consisting of a series of several open pit mines excavated into poorly consolidated sandstones, siltstones, and claystones. Since the initial open pits were developed in 1969, slope failures have plagued the mine and mining operations. These slope failures have persisted into the current mine reclamation period. When the mine was first developed, the open pit slopes were designed to range between 45 to 55 degrees. Numerous slope failures during mine development required the pit slopes to be redesigned with slopes as shallow as 26 degrees. At present, movements are occurring within the open pits on reclaimed slopes that are shallow as 12 degrees. Several detailed slope studies were conducted at the mine in the early 1970s. These studies, combined with more recent geotechnical investigations, provide a unique detailed history of pit slope failures on shallow slopes. This paper presents an evaluation of the slope failures at the Shirley Basin mine, highlighting important mechanisms causing slope failures on very shallow slopes. The evaluation demonstrates important key parameters for shallow slope design.

Jan 1, 2001

By A. C. T. Bigg, Y. Kocak, N. K. Bodur

The Gumuskoy silver mine, owned by the Etibank, in the province of Kutahya, Turkey, has been operating since 1987 with primary, secondary and tertiary crushers, and two parallel single stage ball mill circuits. Continuing problems with crushing and feeding of the ore to the ball mills, because of the moisture retaining and sticky nature of the ore, prompted an investigation into the possibility of converting the grinding circuit to an autogenous or semiautogenous grinding circuit. This would remove the bottleneck associated with the secondary and tertiary crushing. At the same time the target feedrate is to be raised from 140 t/h to 175 t/h. This paper demonstrates the response of five ore types, and blends of ore types in an onsite pilot plant test program, and also suggests how the variations can be handled in a SAG mill/ball mill circuit incorporating just one of the present ball mills.

Jan 1, 2000