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By Carl Lee

OXYGEN-FREE high-conductivity copper (OFHC brand) that is now being commercially offered for the first time represents a notable achievement in electro-metallurgy and is the outcome of endeavors that have extended over a long period. Its manufacture is novel in that electrolytically refined copper is melted in electric furnaces and cast into vertical water-cooled molds. The ingots show the "pipe" characteristic of sound gas-free metal and microscopic examination even at high magnification reveals no cuprous oxide in the copper. Owing to the patent situation, the United States Metals Refining Co., the producers, cannot at this time divulge the details of manufacture, but the operations are under precise control so that the castings are of great uniformity and the copper contains no residual deoxidant. Figs. 1 and 2 show photographs of cross-sections of a wirebar and a billet, both vertically cast.

Jan 1, 1933

By Haibin Wang, Kaile Tang, Chenn Q. Zhou, Guangwu Tang, Zhixiang Cui, Ping Zhou, Armin K. Silaen, Hongjie Yan, Zhi Wang

The submerged lance smelting furnace (SLS) for copper smelting has been developed and used by Dongying Fangyuan Nonferrous Metals Co., Ltd. The technology has shown advantages such as high oxygen enrichment, good feed adaptability, short processing time, high SO2 concentration for acid plant, and auto-thermal operation. In this study, computational fluid dynamics (CFD) was used to investigate the gas/matte two-phase flow characteristics and the chemical reactions in the SLS during typical operational conditions. The Eulerian-Eulerian approach was employed to model the phase interactions. The chemical reactions were modeled by calculating the mass transfer coef ficients and using the eddy-dissipation model. The simulation was conducted using the commercial software ANSYS Fluent®. The developed CFD model is able to predict the flow, temperature, and species distributions inside the SLS under various operating conditions.

Mar 1, 2018

By J. W. Choung, T. Fu, Z. A. Zhou

An on-line visualization technique and methodology was developed to investigate the role of fine sphalerite (< 10 um) aggregation in flotation. The images of particle aggregates under different operating conditions were recorded and analyzed. The effect of impeller design on particle aggregation was demonstrated. This difference was not mainly due to the energy input into the system, but due to the resultant hydrodynamic conditions created by the impeller and their effect on particle interactions. The recorded image showed that adding fine silica (- 5 um) did not interfere with fine sphalerite aggregation, thereby showing no effect on the sphalerite recovery. Effect of the enlarged aggregate size on increasing flotation recovery was confirmed. Although Malvern Mastersizer produced consistently lower estimates of aggregate size than those by the image analysis, both methods responded to the changes in operating conditions in the similar trend. It was shown from this study that on-line visualization technique is a powerful tool for studying fine particle aggregation and morphology in the context of diagnosis for the flotation separation.

Jan 1, 2004

By George Nekoksa

The biofilm activity monitoring probes measure applied current during intermittent short-term polarization of the probe electrodes and current or potential between the electrodes after removal of the polarization. The probe polarization mimics conditions at crevices, welds and inclusions where the biofilm activity and microbially influenced corrosion usually concentrate. Monitoring of AC resistance between the probe electrodes can provide infornation about the thickness of deposits.

Jan 1, 1994

By Travis Davidsavor, David Provost

A segment of high-pressure steel petroleum pipeline needed to be replaced on a hillside and beneath a waterway within an existing right-of-way containing multiple petroleum pipelines. The pipeline replacement required excavation of sedimentary rock to allow placement of the new pipe. As a result of an existing right-of-way limitation, steep slopes, and hard rock, blasting would be required as close as 7.8 meters (25 feet) from two operating pipelines. Existing pipeline company standards would have effectively precluded the construction of the replacement pipe by blasting rock. To facilitate the required construction and evaluate actual pipe stress during blasting to ensure pipeline integrity, a comprehensive evaluation methodology was developed by a team of pipeline, mechanical, geotechnical, instrumentation, and blasting engineers. A total of 60 strain gages were affixed to the steel pipe and seismographs were buried at the surface near the blasting area. Test blasting allowed pipe stresses with corresponding ground motion to be monitored. A conservative analysis approach evaluated individual peak strains and revealed that only small pipeline strains, and therefore stresses, were induced in the pipeline as a result of blasting. This evaluation allowed specific procedures to be developed to inform the blasting operation of maximum explosive loading and minimum charge distances. Additionally, this effort provided the pipeline operator with appropriate pipeline operating pressures during blasting activities to limit total stresses in the pipeline to be below allowable stresses imposed by code, regulators, and company operational limitations. Recommendations were developed to measure the blast generated ground vibrations with seismographs buried at the depth of the pipe, near the pipe, and limit the ground vibrations from blasting to 150 mm/s (6 in/s). If ground vibration intensities of 120 mm/s (4 in/s) or more were observed, additional engineering review is recommended. Finally, all blasting would be suspended and all activities reviewed at peak ground vibration intensities of 230 mm/s (9 in/s). The evaluation effort resulted in effective and efficient construction of the pipeline replacement and allowed the pipeline operator to better understand blasting induced stresses on their assets.

By G. S. Hume

FOR MANY YEARS Canada lived in the hope of attaining a substantial production of petroleum and natural gas that, to geologists familiar with the sedimentary basins of this country, seemed an entirely reasonable expectation. There have been surges of exploration activity stimulated by oil and gas discoveries and development such as occurred in Turner Valley. However, it was not until the Leduc field in Alberta was found in 1947, and the significance of that discovery was realized, that the search became really intensive and continuons. Expansion now has become a matter-of-fact attitude based on results which would have been considered impossible of achievement a few years ago.

Jan 1, 1957

By Frank L. Hess

In the first cart of that little space of time that we have designated as the nineteenth century, chemistry had reached a wonderful stride. Viewed from the present heights attained by the efforts of innumerable chemists with perfected apparatus, mire reagents, air under pressure, water, gas, and electricity conducted to the desk, and. numberless other helps, it seems marvelous that chemists of that day obtained such results. In 1820, about half of the elements had. been discovered; of these discoveries, Swedes had made 15 or more, about once-third of the elements then known and nearly half of those discovered after 1700.

Jan 1, 1939

By J. Ji

Oxygen requirement during acidic pressure oxidation of sulphide concentrates can he as high as 800 kg/(m3.h) in the first compartment of an autoclave when the total oxidation residence time is shortened to 30 minutes. To achieve such a high oxygen transfer rate while maintaining satisfactory oxygen utilization, a pilot plant campaign was launched at the Placer Dome Research Centre in 1998 to measure the oxygen mass transfer coefficient in a 5 m3 pressure vessel at a total pressure close to 500 psig with a 30 HP gassing agitator. Maximum oxygen flowrate to the pressure vessel was designed at 3 600 kg/h. In this paper, a great deal of information is provided on the gassing agitator, pressure vessel. measurement procedure and results. Without oxygen sparging, the oxygen mass transfer coefficient is 2 600 h-1 with a mixing power input of 5.0 kW/m3 in solution. With oxygen sparging, the oxygen mass transfer coefficient increases to 3 500 h-1 with a mixing power input of 4.0 kW/m3 in solution.

Jan 1, 2004

By Donald J. Barnes

Gold was found in samples collected from Pleistocene and Holocene stream and terrace deposits. Approximately 15,000 cu yd (11,400 cu m) of small and discontinuous terrace and stream gravel deposits in the study area are composed of material derived from sedimentary and granitic rocks. The detritus is subangular to subrounded, and poorly sorted, ranging from boulder to sand size. Gold values in samples collected averaged 8.2 cents per cu yd (gold value of $500 per oz). Pan concentrates and rock chip samples collected from reported mineralized zones showed an absence of economic minerals. Stream placer deposits are uneconomic. No potential was observed for metallic or nonmetallic minerals in the La Panza study area. No potential exists for gas, oil, or coal resources.

Jan 1, 1981

By Joel L. Morrison

Wet bituminous coal fines from active and abandoned slurry impoundments are currently being examined as a recoverable feedstock for the production of coal water slurry fuel (CWSF). Preliminary analysis indicates that these coal fines can be converted into low solids, low viscosity CWSF with acceptable stability without the use of viscosity modifiers (dispersants) or stabilizers. Efforts are now underway to determine if the impounded coal fines can be economically cleaned by froth flotation to an ash level of < 12 wt. % and a total sulfur content of 1.2 wt. %.

Jan 1, 1995

By M. S. Moats, W. C. Hartzell

The stable domestic supply of gallium, indium, and germanium has been identified as a critical need for the United States. Electric arc furnace dusts, processed to recover zinc, produce a residue that could be a potential source of these critical materials. An industrial zinc leach residue was characterized to determine its particle size, chemical composition, and predominant mineral phases. Heated, atmospheric, agitated leaching using sulfuric acid and hydrochloric acid was examined to determine the extractions of gallium, indium, and germanium as a function of concentration and temperature. Extractions of gallium were found to be similar to iron in all experiments. The maximum percentage of Ga, Ge, and In leached into solution were 71%, 63%, and 48%, respectively.

Feb 1, 2023

By MUSTAFA ERKAYAOGLU, ENVER YILMAZ

Coal is still a part of energy generation worldwide and has a significant role in the sustainable development of countries. The amount of shallow coal deposits is getting scarce, making efficient underground mining operations crucial for both local and global economies. In underground mining operations, longwall mining is a commonly utilized method to extract deep coal deposits. One of the leading engineering goals in longwall mining is increasing the efficiency of the system by investigating the effects of operational factors on equipment. This paper investigates the shearer performance for a longwall top coal caving operation by discrete event simulation that includes modeling the double-drum shearer, belt conveyors, stage loader, and armored face conveyors (AFC) to evaluate system performance by considering the amount of daily coal production of the shearer. As a result, the most influential factor on mine production is determined and a data-based framework is developed. This study suggests a framework for data collection, data analysis, and the interpretation of the operational data to evaluate the primary production unit’s performance. The models developed for the face coal extraction operations in a longwall top coal caving (LTCC) mine have a bi-directional cutting system and can be implemented in other operations readily.

Jul 2, 2021

By D J. Williams, S Islam

Worldwide production of black coal amounts to about 8 billion tonnes. Perhaps 20% of this annual production is washed to improve its quality, generating perhaps 250 million tonnes of coal tailings annually, generally in the form of a slurry. The coal tailings slurry is typically thickened to about 25% solids by mass prior to disposal to a tailings storage facility (TSF), and hence comprise mostly water (about 85% by volume), plus sand, silt and clay-sized mineral particles and carbonaceous material. While the tailings settle and consolidate on deposition in the storage facility, their high moisture content makes them prone to run-out should the tailings dam fail, and makes rehabilitation of the tailings difficult. Hence, it is important to understand the consolidation and shear strength of coal tailings. Laboratory consolidation testing of coal tailings from a slurry to a soil-like state has been carried out in a purpose-built, large-scale, slurry consolidometer, instrumented with load cells and pore water pressure (PWP) transducers. Laboratory vane shear testing of coal tailings produced at different gravimetric moisture contents has also been carried out. The test results have allowed a regression model to be developed relating the peak vane shear strength of the coal tailings to their gravimetric moisture content.CITATION:Islam, S and Williams, D J, 2018. Consolidation and shear strength of coal tailings slurries, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 62–71 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Ellis Thomson

The microscope is now used extensively not only in the examination of solid ore but also in the determination of fragmental mill products. It has therefore become a matter of paramount importance to be able to mount and polish fragmental as well as solid specimens in the easiest and most efficient way, so that the minerals present may be readily determined. In the case of the solid ore the ordinary mount of plasticine set on a glass or metal slide serves for most practical purposes. An improvement on this is furnished by the small brass container inside of which the specimen is mounted in a cementing medium of sealing wax. The latter is the method in use at Harvard University. It has the advantage of uniform height, thus obviating the necessity of a slide of any sort. It is also easily catalogued as the brass holder may be stamped with a convenient series of letters and numbers that will serve as a label. Other advantages of this type are the ease with which any particular part of the section may be re-located, the excellent storing facilities afforded by mounts of uniform size, and the possibility of polishing ten or a dozen sections at the same time by means of a holder which is placed over the polishing wheel, is geared with it, but revolves the opposite way.

Jan 1, 1926

By James W. Townsend

[The Harrington-Hickory mine in the Star raining district, Beaver County, Utah, has produced approximately 20,000 tons of lead-zinc-silver ores since 1910. Production previous to 1910 is not known. The mine is owned by the New Majestic Mining Co. The property was rehabilitated and operated by James D. Williams under a 10-year lease with option to purchase from April 1943 to May 1949, Loans from the Reconstruction Finance Corporation in the aggregate of $41,000 wore used in construction of an access road, rehabilitation of the mine, and purchase of equipment for full-scale operation. The improved, all-weather access road extends from loading ramps on the Union Pacific Railroad at Milord to the urine storage bins 5 miles west o f town. The mine is serviced electrically by a. 5,000-volt line owned by Telluride Power Co. Mine transformers step the voltage down to 440/220/110 for surface and underground service.]

Jan 1, 1953

By M. D. Riegel, P. B. Pizzimenti, E. M. Zamiskie, Britain A. Materek

"The Skanska/Kiewit/ECCO III team (SKE) in association with HNTB was awarded the design-build contract for Phase I of the Kosciuszko Bridge Replacement Project. As lead designer for the SKE team, HNTB was responsible for the design of the Brooklyn Connector which includes construction of approximately 2000 feet of new staged earth-filled embankments utilizing prefabricated modular retaining walls (T-Walls®). The proposed embankments will be constructed adjacent to and beneath the existing Brooklyn Queens Expressway (BQE) viaduct while the existing viaduct remains in service. Critical aspects of the settlement assessment relating to the soils supporting the existing BQE will be addressed, as their behavior drives the deformation of the viaduct. Furthermore, a construction monitoring program was used to enable the designer to assess settlement predictions and allow SKE to mitigate potential impacts to the existing BQE during construction. Additionally, the methodology for installation of the embankments in a limited access area underneath an active viaduct supported on settlement sensitive shallow foundations will be presented.INTRODUCTIONSkanska-Kiewit-ECCO III Joint Venture, in association with HNTB was contracted by the New York State Department of Transportation (NYSDOT) to design and construct the Phase 1 replacement of the Kosciuszko Bridge Design-Build Project. Phase 1 of the project involves the design and construction of the new eastbound structures of Interstate 278 over Newtown Creek from Brooklyn to Queens. The project runs between Morgan Avenue in Brooklyn and the Long Island Expressway Interchange in Queens (approx. 1.1 miles) and includes the staged demolition of the existing structures."

Jan 1, 2016

By S A. Ravishankar, W Perez

Flotation is one of the main concentration processes to purify kaolin clay via the removal of naturally occurring impurity minerals containing Ti and Fe. Currently, there are two types of collector chemistries used in the industry to float coloured impurity minerals. These are traditional tall oil fatty acids (TOFA) and specialty hydroxamate (AHX) based collectors. AHX based collectors have long been known to be the most selective collectors to float Ti and Fe based coloured impurity minerals (CIMs) as compared to TOFA based systems. AHX based collectors provide, not only improved selectivity and simplified process, but also more importantly, make it possible to treat certain kaolin resources that do not respond to standard TOFA systems. However, the relatively higher cost of straight AHX collectors has restricted broader application of these collectors in kaolin clay and other oxide flotation applications for a long time. Recent technological advancements, in both making and formulating AHX products more economically, increased the usage of these collectors in kaolin applications. Modified AHX products offer more economical alternatives and process options to provide high purity kaolin clay products for specialty applications based on cost-performance criteria. In this paper, the flotation performance of a series of newly developed AHX formulations is provided along with the characteristics of AHX flotation in general. In addition, flotation performance of earlier AHX collectors is provided based on published literature as background data.

Jan 1, 2005

By R Wedmaier

Henty Gold Mine is an underground operation producing 100 000 ounces of gold per annum. The original mining method used was flatbacking with paste fill. However, a non-entry method û uphole benching û was introduced in 1998 to recover the deteriorating crown pillars. Initial challenges were encountered, including poor drilling accuracy, difficulty in charging holes and poor rise performance. These challenges were overcome by a Continuous Improvement Team, consisting of mining engineers, supervisors and miners. Following this, the Team implemented further changes aimed at reducing ore loss and dilution. A second area addressed by the Team was development blasting, where innovative detonator technology known as the ExelTM DevelDetTM was introduced and rapidly accepted by the operators. Continued use of the ExelTM DevelDetTM resulted in a number of benefits, such as easier bogging, less perimeter damage, faster charging and hook-up and decreased wastage. Finally, improvements were made in the area of explosive handling, where competency-based training of operators was conducted and manual handling of ANFO has been significantly reduced by the introduction of the MiniMoverTM into the underground magazine.

Jan 1, 2001

By M. Dupuis

It has been previously demonstrated [1,2] that using selective collector bar rodding has a big impact on the uniformity of the current density at the top surface of the cathode block and hence on the intensity of the horizontal current in the metal pad, The present study investigates the impact of using selective collector bar rodding on the MHD stability of a 500 kA aluminium electrolysis cell, For this purpose the recently developed MHD package for the aluminium reduction cell time dependent behavior is used.

Jan 1, 2005

By Raja V. Ramani, Sachin Shankar

"Re-entrainment refers to dislodgement of particles deposited by both atmospheric and nonatmospheric processes and their subsequent insertion into a flowing field. Formation of sand dunes, snow drifts, soil erosion and fugitive dust emissions are a few examples of the natural occurrence of re-entrainment. Re-entrainment studies have been done for the estimation of potential hazards from nuclear fallouts. The phenomenon of re-entrainment has been utilized for the cleaning of wafers and filters. Re-entrainment is associated with both surface and underground mining activities. However, studies on dust re-entrainment in mine atmospheres are limited. Understanding the re-entrainment phenomenon is important because dust particles lying seemingly harmless on the ground and adhering to numerous surfaces can get re-entrained and become a health and safety hazard.There are significant differences in the kind of re-entrainment encountered in underground mines and those in other fields of interest. These major differences are air velocity, direction of air flow, particle size, amount of particles, and time of exposure. While numerous studies have been done in other fields to identify the role of interacting variables and their contribution to the mechanisms of re-entrainment, no similar reported work is available for dust in mine atmospheres.In this paper, recent research efforts on re-entrainment are reviewed. The most suitable form of representing re-entrainment in underground coal mine atmosphere is presented. Various approaches to studying re-entrainment phenomenon in mines are also outlined.In the mineral industries, formation of dust particles of widely varying sizes is a natural outcome of the fragmentation required in mining the solid resources. Fine particles in mine atmospheres, particularly in the respirable size range, are a threat to the health and safety of the miners when present in high concentrations. In 1980 the National Academy of Sciences (NAS) Committee on the Measurement and Control of Respirable Dust in Mines recommended that the spatial and temporal characteristics (of fragments produced in coal mining) need to be understood so that the exposure of workers to the dust can be controlled. Recently several studies have been performed to understand the fundamental behavior of the airborne respirable dust in mine airways (Bhaskar, 1987; Qin, 1988; Polat, 1989; Bode, 1990)."

Mar 1, 1992