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By P. R. Desam, J. D. Miller, A. Datta

The flow behavior of bubble-particle aggregates in separation tanks is important for many flotation systems, particularly for wastewater treatment. These aggregates can be considered as the dispersed phase in a continuous liquid phase of water and the flow characteristics determine the efficiency of the bubble separation process. In this work, a general methodology for the computational fluid dynamics (CFD) simulation of a bubble separation tank is described. This system is analyzed by Eulerian-Lagrangian approach. The momentum transfer from the dispersed phase to the continuous phase is quantified using the Particle-Source-In Cell (PSI-Cell) method. With CFD simulations, the effectiveness of different tank design parameters are evaluated in terms of the extent of bubble separation.

Jan 1, 2000

By R. Abel, T. Wildeman, N. Heflin

A study was conducted to assess environmental effects of waste rock piles on water in the Russell Gulch area. Each pile was rated on physical characteristics of proximity to an ephemeral gulch, extensiveness of erosion features, size, presence of vegetation, and presence of a kill zone. Chemical assessments focused on three leachate tests performed on waste rock samples. Ratings were based on pH, conductivity, acidity, and analysis for 31 metals using inductively coupled plasma emission spectroscopy. The chemical and physical assessment of each site is used to make a rating of each pile on its overall potential to deliver contaminants.

Jan 1, 2004

By G. Hausen, H. Micka

"Modern signal and power electronics made adjustable-speed AC drives technically feasible and reliable and economically attractive. Cycloconverters are discussed as a proven technology for mine hoists. \IntroductionUntil rather recent technical and commercial advances in power and signal electronics, DC motors were used almost exclusively for applications requiring continuously adjustable operating speeds and torques. More recently, the significantly higher efficiency and the accordingly lower operating costs of AC motors gained importance. An effective and efficient speed control of AC motors requires the control of AC voltage and frequency. Table 1 shows typical applications of adjustable-speed AC drives.CycloconvertersOf particular interest to the mining industry are cycloconverters for hoist drives. The cycloconverter represents by far the simplest, most efficient and most economical means of converting a constant-voltage, constant-frequency supply into an adjustable-voltage, adjustable-frequency supply as required for the speed control of AC drives operating in the frequency range to half of the utility frequency.Cycloconverters feeding synchronous motors or induction motors are ideally suited for slow-speed direct-coupled drives."

Jan 1, 1988

By Nicholas J. Grant, H. C. Chang

TRANSCRYSTALLINE fracture surfaces of the cleavage type have been examined by microscopy and X-rays for several metals.' These investigations revealed that the fractured surfaces were not flat and invariably had cleavage and other deformation markings on them. On the other hand, the study of inter crystalline fracture surfaces has been limited. Perryman, in a recently published paper on the inter crystalline fracture of ß-brasses,' found that a thin layer of heavily deformed metal was invariably associated with these surfaces. Furthermore, the thickness of this layer was found to depend on the orientation of the grain boundary surface with respect to the applied stress. The mechanisms of grain boundary sliding and intercrystalline fracture have been presented in two previous papers,which described certain aspects of the deformation of a 20 pct Zn-A1 alloy. It is the purpose of this paper to present some observations on the structure of intercrystalline fracture surfaces and to correlate the structure of such surfaces with the mechanism of intercrystalline fracture. Experimental Techniques—The high purity 20 pct Zn-Al alloy was generously supplied by the Research Laboratories of the Aluminum Co. of America. Two sizes of specimen were used; the first had two parallel flat surfaces of dimensions 1x0.17x0.09 in. and the second was round with a 0.25 in. diam. A grain diameter of 1 to 3 mm was obtained by annealing the specimens at 1000°F for 24 hr. The specimens were then air cooled. The specimens were subjected to creep at 500°F and 2300 psi. The rupture times ranged from % to 3 hr, with one room temperature tensile test. It has been mentioned previous1y" that the intercrystalline fracture surfaces of this alloy, when tested under the conditions given above, are sharply defined. In the optical examination of the fracture surfaces, whenever possible, magnifications of at least X250 were used. The locations of the regions examined, both optically and by X-rays, were selected to give several fracture surface orientations with respect to the stress axis and to the specimen surfaces. This was possible for the X-ray studies since the grain diameters were large compared to the X-ray beam. A film to specimen distance of 3 cm, a 1 mm pinhole and Cr radiation were used for the Laue back reflection pictures.

Jan 1, 1957

"Mineral separation by exploiting the differences in mineral or metal specific gravities (sg) has been used since antiquity. In the modern era, this is most commonly seen in the recovery of gold by the use of centrifugal concentrators and the separation of coal (low sg) from waste rock (high sg) using heavy media cyclones and jigs. Other metals, notably oxides of tin and tungsten, are successfully recovered using some combination of jigs, spirals and shaking tables. However, many conventional gravity separation systems are limited to fairly coarse (>1 mm) to medium (>100 micron) particle separations due to the limitations of the gravitational separation forces in conventional equipment.Many of the high specific gravity minerals of interest are friable (e.g. cassiterite, wolframite, etc.) and excessive fines are generated in the grinding/comminution circuits which cannot be recovered with conventional equipment and may be lost directly to the tailings stream. Recent developments in centrifugal gravity separation equipment specifically designed for fine or ultra-fine particle separation and recovery have resulted in heavy mineral particle recoveries as fine as 10-20 microns. Ongoing research work has also identified the benefit of closed-circuit, multi-stage gravity recovery circuits using some combination of centrifugal concentrators and conventional equipment (tables, spirals, flotation, etc.) which can substantially increase overall plant recovery and final concentrate grade.This paper will provide details of the evolution of non-fluidized bed gravity concentrators for high sg mineral recoveries, correlate laboratory scale development work with plant results to confirm scale-up, and show how recent flowsheet developments have contributed to significantly improved plant performance.IntroductionGravity concentration is one of the oldest and most cost effective metal and/or mineral recovery systems, ranging from the classic hand panning of alluvial gold, through to the large scale production of a wide range of metals and minerals, including gold, silver, PGMs, black sands, coal and iron oxides. Conventional gravity recovery systems, comprised of some combination of sluices, spirals, jigs and shaking tables have limited application in fine particle (i.e. <100 microns) recovery, or where there are limited differences in particle specific gravities (sg), e.g. the separation of high sg, high value metal oxides (e.g. those of tin, tantalum or tungsten), from medium sg, lower value metal sulfides such as pyrite and pyrrhotite. These unit operations tend to have limited capacity, and while double and triple turn spirals and multi-deck tables have been developed, extensive floor space is often required in order to process the tonnages incorporated in the modern mineral processing plant."

Jan 1, 2017

By Kent von Maubeuge, Charles R. Landis

The global bentonite industry is a dynamic market balancing a range of end uses with an ever growing number of bentonite producers. In addition, markets in developed countries are elevating the level of detail and transparency for materials reporting in programs, such as the Registration, Evaluation, Authorization and restrictions of Chemicals (REACH) program in the European Union. Bentonite is impacted by programs of this nature. The majority of the bentonite products sold around the world are sodium bentonites. These sodium bentonites consist either of natural sodium bentonites, or naturally occurring bentonite dominated by divalent interlayer cations (Ca+2 andMg+2) subsequently exchanged with sodium cation. The latter variety is often called “sodium-activated“, or “soda-ash treated” bentonite. Once exchanged with sodium, these bentonites are often difficult to distinguish from natural sodium bentonites using common commercial testing protocols. Due to their similar colloidal and bulk chemical properties; the lack of test procedures designed specifically to identify this product feature; and the failure to completely or effectively explain their differences, sodium-activated bentonite is often considered to be identical to natural sodium bentonite in the industry. This article defines both general types of sodium bentonite and presents a technique that could serve the industry as a tool to confirm the variety of sodium bentonite in question. Specifically, geochemical properties such as carbon (C13/C12) and oxygen (O18/O16) isotopic ratios can distinguish activated, even slightly activated bentonites, from bentonites not introduced to additional sodium during manufacture.

Jan 1, 2004

By R. L. Virta

Six companies mined fire clay in Missouri and Ohio during 2004. Production, based on a preliminary survey of the fire clay industry, was estimated to be 398 kt(438,700 st), valued at $9.81 million. This was slightly less than the production and value figures from 2003. Missouri was the leading producer state. It accounted for more than 70 percent of the U.S. production. Consumption Domestic producers sold or used fire clay primarily for refractory applications. This application accounted for 79 percent of the market. Refractory products made using fire clay include firebrick and block, grogs, high-alumina brick and specialties, refractory mortars and mixes, and saggers.

Jan 1, 2005

As part or a programme to raise lead smelter capacity from 65.000 to 140.000 tons bullion per annum. one new 1000 sq. ft. updraught area sintering machine replaced eight small downdraught machines.The metallurgical specifications were based on and laboratory tests at Mount Isa. Existing practice filtering concentrate as part of the charge preparation system and discharging wet filter cake to mixing was retained. This dictated a hot return fines circuit to maintain the required feed moisture content at low return sinter ratios.The engineering specifications provided for cenlralized control of plant and process, minimum operating labour, high plant availabi;lity and highest standardsof hygeine. Crushing and conveying capacity was set to cater for the most optimistic level of sintering capacity.On start-up a number of major engineering and hygiene problems became apparent, in addition to normal teething troubles. These problems have largely been overcome and reliable operation. at less than optimum production rate is now being achieved.

Jan 1, 1968

By W. P. Diamond, S. L. Cario, F. Garcia, J. D. Byars, T. P. Mucho

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research at a Pittsburgh Coalbed longwall mine to evaluate and optimize bleeder ventilation and gob gas venthole longwall methane control systems. Gas flow into these two methane control systems was investigated using a combination of Sulphur Hexafluoride (SF6) tracer gas studies and gob venthole pressure monitoring experiments. The insights gained from this research has facilitated the development of along wall subsided strata methane control system conceptual model. This model provides the basis for design suggestions to increase the efficiency of the gob gas venthole system to permit the bleeder ventilation system to become a "safety net" for methane control.

By Eduardo Pimenta de Melo, Rambabu Pothina, Rajive Ganguli

Sensors are everywhere in the mining industry, with sensor information being used to monitor and operate processes. Therefore, when sensor information is wrong, economic losses can occur. Unfortunately, sensor errors are usually not detected till they become large. This is problematic as most calibrate their sensors no more than once a year (Beamex, n.d.). Using principles of data mining, where all relevant information is tapped to glean hidden information, Pothina [8] designed an algorithm to detect errors in temperature sensors in gold stripping circuit in Pogo mine, Alaska. This paper continued his work by analyzing the behavior of the algorithm on baseline data and testing the algorithm in new data and under more rigorous conditions. It also made a change to the algorithm. The modified algorithm performed very well in the new data. It also worked well under the new error conditions. Three types of errors were seeded, a fixed additive error (+ 2%), a fixed subtractive error (− 2%), and a noisy, normally distributed error, with a mean value of + 2%. Artificially seeded errors were detected within about 20 gold stripping cycles. Inherent bias in operation impacted algorithm performance by increasing the number of cycles needed to detect errors. This paper reinforced Pothina’s [8] conclusion that when data mining approach is used, sensor errors can be detected even when they are pretty low. Significant economic losses can thus be minimized.

By J. H. Daniel

This report, summarizing the results of two studies sponsored by the Bureau of Mines, presents information on the types of mobile machines used in surface coal mines in the United States, and the amount of noise to which miners are exposed. Data consist of a calculated value of the probability of noise overexposure caused by specific equipment. These data are extrapolated to estimate the number of overexposed operators. Bulldozers were identified as the major contributors to noise overexposure, and the report presents results of a Bureau-funded program on the feasibility of providing retrofit noise control on bulldozers.

Jan 1, 1980

By Gene F. ] [Faufaul

This contract was concerned with the design, development, fabrication and testing of an improved tamper-proof filter cassette assembly for use in the, collection and evaluation of dust particulates, primarily in mining areas. This report presents the design effort, fabrication and tenting of five- prototypre unit$ as well as the design and production of 1000 filter cassettes with sampling heads. This new improved filter cassette has been tested and approved by NIOSH as meeting the requirements specified in the contract.

Jan 1, 1978

By Robert A. Bradburn

The Bureau of Mines has developed a miniature, portable two-level oxygen-deficiency alarm and produced three prototype models. Each operates from a 4.2-v dc power source, and the highest current drain of any model is 80 ma. An electrochemical cell, which produces an electrical output in proportion to the partial pressure of oxygen to which it is exposed, is used as an oxygen detector. The output of the cell is applied to an electronic circuit that detects two different levels of oxygen percentage below that of normal air, and produces distinct audible signals at these levels. The hazard alarm mode is activated when the oxygen percentage first drops below normal and produces a 500-cps "beep" tone with an intermittency of 1 cps. The danger mode produces a continuous 500-cps audible signal when the oxygen percentage drops still lower.

Jan 1, 1968

By Ali Kahriman, Abdulkadir Karadogan, Deniz Adiquzel, Umit Ozer, Suat Bicer, Mehmet Aksoy

This paper presents the analysis and measurements of blast-induced ground vibrations during the construction of Istanbul Kagithane – Piyalepasa – Dolapdere – Dolmabahçe highway tunnels. These tunnels known as T1 and T2 are being constructed by a joint venture group. Within the scope of the study, the particle velocities and frequencies associated with 126 shots during the advancement of the tunnels were monitored and analyzed by vibration monitors at the test site. During the statistical analysis, three different predictor equations widely used in the literature were used to predict peak particle velocity (PPV) and the results and comparison of the predictor equations are presented in this paper. Finally, the particle velocities and frequency values of all blast events were evaluated according to USBM and German DIN 4150 Norms in order to determine the damage risks of the neighboring buildings and structures.

Jan 1, 2008

By Mark P. Meyer

A mineral investigation of the Chugach National Forest, Alaska was conducted jointly by the U.S. Geological Survey and the U.S. Bureau of Mines from 1979 to 1983 as part of the RARE II program. The U. S. Geological Survey remapped the geology and distribution of mineral resources. The Bureau investigated mines, prospects, and mineral occurrences. Previously unreported mineralization in three areas, Long Bay, Wells Bay, and Miners River were discovered in the western portion of the SOUND study area. Copper, lead, zinc, gold, silver, nickel, cobalt, fluorite, and arsenic were found in north-northeast to north-northwest trending shear zones, veins, felsic dikes, and granitic intrusives in Tertiary Orca Group metasedimentary rocks.

Jan 1, 2011

During the period 1979 thru 1982, Multi Mineral Corporation conducted a mining research program at the United States Department of the Interior&apos;s Bureau of Mines Oil Shale Mining Environmental Research Facility in the Central Piceance Creek Basin, Rio Blanco County, Colorado. The program consisted of mining, environmental and geotechnical research data and the results are described in this report.

Jan 1, 1983

By J Petrolito

"To improve the economic and environmental performance of underground mining operations, it is common practice to return the metallurgical waste material underground as backfill. This is called hydraulic backfill and is used to fill the mined-out areas not exposed to further mining. To provide mechanical support for underground mining a cemented backfill is normally used. Since its introduction, cemented backfill has allowed mining companies to increase their ore extraction and improve working and environmental conditions. However, cemented backfill represents up to 50% to 85% of the mine’s operating cost compared with 5% to 10% for hydraulic backfill.These economic pressures have led mining companies to carry out research into the partial or total replacement of cement using a variety of alternative materials. The materials are generally site-specific materials, readily available, and cost-effective relative to cement. Such investigations have led to reduced cost of many backfill mixes while maintaining, and in some cases improving, the physical properties of cemented backfill. However, in most cases, cement still remains an integral part of any binder combination. This can be attributed to the alternative binders investigated being either non-binding materials or capable of generating only low-strength backfills, except when used in conjunction with cement.This paper provides a historical review of backfilling binder materials and their characteristics. In particular, it reviews the many alternative materials that have been proposed to either partially or fully replace Portland cement as the main binder."

Jan 1, 2005

By C. C. Walden, A. Bruynesteyn

"Chemical and biological aspects of the formation of acidic effluents from sulfide waste materials are discussed. Test procedures to determine the acid producing potential of waste materials, as well as the characteristics of such acidic effluents, are presented. Practical applications of the test procedures are discussed with reference to predictior of environmentally unacceptable drainage and to estimation of metal recovery by dump leaching.INTRODUCTIONNatural leaching of sulfide minerals, exposed to the atmosphere, has been occurring for geological time. For centuries, man has been aware of the acid drainage originating from coal workings, copper mines and waste dumps. With the advent of the technical sciences, the processes involved in acid mine drainage production were considered to be solely chemical in nature. However, in 1947, it was shown (1) that a specific microorganism, called Thiobacillus ferrooxidans, was responsible for acid mine drainage from coal workings. It was demonstrated that under suitable conditions - this bacterium oxidized pyrite and marcosite in the coal to ferric sulfate and sulfuric acid. Numerous studies have subsequently demonstrated that - under suitable conditions - Thiobacillus ferrooxidans can attack most sulfide minerals, producing weak sulfuric acid, oxidizing ferrous to ferric iron and solubilizing other metals present (notably copper and zinc) as their sulfate salts."

Jan 1, 1980

By Zhang Jiaju

For the highrise buildings with deep foundstion of irregular plane shape, an appropriate calculate model to the heave of foundation soil after excavation is proposed and studied using analytic method and FEM (Finite Element Method) respectively to provide an effective way for solving this kind engineering problem. Also combined with the practice of construction deep foundation of Capital Mansion, calculation of the heave of foundation soil after excavation is given. Compared these results from above two methods with the results measured in situ, it is conformal on the whole, and the results by FEM are much closer with the measured.

Jan 1, 1991

By P. M. Cole

An unprecedented expansion of the global zinc industry is currently under way. While most new projects and plant upgrades remain committed to traditional processing technologies, recent advances in zinc solvent extraction (SX) have created opportunities for new process routes for both primary and secondary materials. The first commercial plant to use zinc SX for the mainstream processing of a low-grade ore is under construction and promises to become one of the lowest cost zinc producers. Several other oxide and sulphide projects in various stages of feasibility are considering the inclusion of SX in their process flowsheet. Zinc SX has also proved advantageous in the reprocessing of secondary materials, particularly for the treatment of zinc residues and furnace dusts. This review focuses on recent installations and projects underdevelopment that feature zinc SZ as the key separation step.

Jan 1, 2002