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By D. E. Kirby

The electrochemical reduction of AlC13 was investigated as a process for the production of aluminum. An externally heated, single-compartment cell with a rammed refractory lining was used with molten KCl-NaCl-AlC13 electrolyte. Aluminum was deposited qt 700° to 760° C with a current of 100 to 200 amperes on a molten aluminum cathode. Chlorine was evolved at a graphite anode and collected and measured to provide a quantitative evaluation of the AlC13 reduction. Aluminum was removed from the cell by siphoning or ladling. Granular AlC13 was added periodically to replenish that depleted from the electrolyte. Concentrations of 7.5 to 17.5 percent AlC13 in the electrolyte were optimum for operation. Anode current efficiencies of 83 to 85 percent were attained, using anode current densities of 5.9 amperes per square inch and an anode-cathode distance of 4 inches. The chemically bonded, alumina liner was resistant to attack by aluminum and chlorine but susceptible to erosion at the surface of the electrolyte. Titanium diboride proved suitable for the electrical connection to the molten aluminum cathode. Aluminum of a purity equal to or better than 1100 series metal was electrowon continuously from commercial AlC13 for a period of 4-1/2 months.

Jan 1, 1970

By T. Sakaguehi

Some attempts were made to recover and remove of uranium that may be present in refining effluents, mine waste Water, and other waste sources by using microbial biomass. To establish which microorganisms accumulate the most uranium, 135 species of microorganisms (42 bacteria, 26 yeasts, 34 fungi and 33 actinomycetes) were screened. Of these 135 species of microorganisms tested, extremely high uranium absorbing ability was found in Pseudomonas stuzeri, Neurospora sitophila, Streptomyces albus and Streptomvces viridochromogenes. In addition to the research on uranium uptake, thorium recovery by using microorganisms was investigated. High abilities were found in Streptomyces levoris and Bacillus subtilis. The selective accumulation of heavy metal ions by various microorganisms has also been examined. Uranyl, mercury and lead ions were readily accumulated by almost all of the species of microorganisms tested. Actinomycetes and fungi differ from many bacteria and most yeasts in their selective accumulation of uranium, and mercury. The basic features of uranium uptake by Streptomyces viridochromogenes, a microorganisms with high uranium-uptake ability, were investigated systematically. Synthesizing these results, we suggested that the accumulation of uranium into these microbial cells is not directly mediated by any metabolic process:, but almost completely dependent upon physicochemical adsorption on the cell components. In addition to this fundamental research, uranium recovery was investigated in immobilized Streptomyces viridochromogenes. These immobilized cells adsorbed, uranium readily and selectively. The immobilized cells recovered uranium almost quantitatively and almost all uranium adsorbed was desorbed with 0.1 N Na2CO3, These results showed that microbial cells are more stable after Immobilization and can be used repeatedly for the process of uranium adsorption-desorption. These results suggested that these microbial cells can be used for the recovery and removal of nuclear fuel elements, such as uranium and thorium, from refining effluents and mine waste water.

Jan 1, 1991

By Brenda J. Wolfe

Following successful laboratory and pilot plant investigation of dewatering characteristics of molybdenum concentrate produced by a Chilean copper/moly producer, two (2) DENVER SALA 500 Series Tube Press Filters were installed in 1994 to handle the total production volume. Moisture requirements in the filter cake have been consistently met, eliminating the need for thermal drying after filtration. Operating data and Tube Press Filter are described herein.

Jan 1, 1995

By Cudmore JF, Rowlands D

Incidents associated with spontaneous combustion of coal have resulted in the loss of many lives and considerable capital and equip- ment. Nevertheless, the factors controlling the propensity of coal to spontaneous combustion are not clearly understood and there is a need for research to study the effects of rank, petrog- raphy, moisture contents, etc. This has been attempted in a study of the propensities of selected Queensland coals to spontaneous combustion. An adiabatic calori- meter was constructed to study the self-heating of a large number of coals. Chemical and petro- graphic analyses of the coals were determined and an attempt was made to relate these propert- ies to the self-heating characteristics of the coal. The results show a strong relationship between rank and self-heating characteristics and that petrographic composition of coal may also be of importance. Some observations on the application of the laboratory results to the practical situation are made as are recommendations for future research.

Jan 1, 1981

By J. S. Ross

The significance and role of industrial minerals in Canada differ from those in the United States, The smaller Canadian industry has recently become well diversified and self-sufficient in most commodities, However, it depends on exports, principally to the United States, for much of its market, Imports are small, but imports of several basic products manufactured from industrial minerals are large. This nation is a leading world producer of asbestos, gypsum, sulphur, nepheline syenite, titania slag, potash and barite. It has reserves in asbestos for at least 30 years enough potash to supply the current world's needs for 2,000 years and sulphur reserves for 40 years of current world demand, One of the ilmenite deposits contains enough titania to supply the current world demand for at least, 25 years.

Jan 1, 1964

By P. A. Rona

The first hydrothermal mineral deposits found at a seafloor spreading center were discovered in the Red Sea by multi-national research vessels between 1963 and 1965. At that time, the deposits were considered a special case related to continental rifting and an early stage of opening of an ocean basin. Since that time, examples of almost all major varieties of volcanic- and sediment-hosted hydrothermal deposits associated with basaltic rocks in the geologic record have been found at present spreading centers. Review of over 100 hydrothermal mineral occurrences presently known at oceanic ridges and rifts indicates that a range of deposit sizes from small to large (> 1 x 106 tonnes) occurs at all seafloor spreading rates. However, larger deposits but fewer per unit length of spreading axis appear to form at slow- than at intermediate- to fast-spreading centers based on available data. Larger deposits are more common in sediment-hosted than in volcanic-hosted settings regardless of spreading rate. A spectrum of hydrothermal deposit varieties (stratiform, stockwork and disseminated sulfides; various forms of sulfate, carbonate, silicate, oxide and hydroxide deposits) occurs in almost all of the tectonic settings. High-intensity, ore-forming, subseafloor, hydrothermal convection systems that conserve heat and mass and concentrate hydrothermal precipitates are extremely localized by anomalous physical and chemical conditions relative to nearly ubiquitous low-intensity hydrothermal activity at and flanking seafloor spreading axes at all spreading rates. Two distinct shapes of volcanic-hosted

Jan 1, 1989

By Rodrigo Perito Cardoso

Low-temperature nitriding of stainless steels is applied to obtain wear resistant surfaces without losing its corrosion resistance. The treatment consists in introducing nitrogen into the steel surface avoiding chromium nitride precipitation. The corrosion resistance of martensitic stainless steels is expected to be improved if the treatment parameters are correctly selected. It can be related to ?Fe2-3N and a'N phase formation on the treated surface. In the present work the influence of the pretreatment and treatment temperature on corrosion resistance of plasma nitrided AISI 420 steel samples is studied. Annealed, as-quenched and 400ºC-tempered samples were nitrided at 300, 350, 400, 450 and 500°C, for 6 h at 600 V. The pressure was 3 Torr and the gas mixture was composed of 70%N2, 20%H2 and 10%Ar, at a gas flow rate of 3.34×106 Nm3s-1. Plasma was generated using a square-wave pulsed DC power supply and the sample temperature was controlled by the duty cycle. The modified layers were characterized by optical microscopy, X-ray diffraction and microhardness measurement. The corrosion resistance was studied by electrochemical characterization, by means of Open circuit potential and Anodic polarization curves. The maximum surface hardness was achieved at 400°C. This temperature seems to be near the limit temperature for low-temperature treatment aiming to improve or at least to keep unaltered the corrosion resistance in relation to that verified for non-treated steel samples. Results confirm that the pretreatment and treatment temperature significantly affects the corrosion resistance of the treated surface.

Aug 8, 2018

By A. K. Bhowmick

Size reduction is very energy intensive and is the single most power-intensive operation in mineral processing plants. Research has shown that only a small part of the energy is utilized efficiently. One of the major thrusts of all equipment manufacturers has been to improve this efficiency. Choosing the right equipment to maximize energy utilization in any comminution application has always been the utmost criteria. Due to the high energy cost and depletion of good grade minerals, it is becoming essential to optimize all the subsystems within a given comminution system for the overall economic success of such ventures. Bradley Pulverizer Company of Allentown, Pennsylvania recognized this and started offering its Feeder Controller in 1988 for automatic feed control. After its first successful operation, Bradley made this as a part of all of their grinding system standard offering. It was also recognized that the Feeder Controller was just a beginning and more automation and controls would be required for an overall, efficient grinding system.

Jan 1, 1993

By A. W. Gauger

SMELTING of iron ore, manufacture of steel, and the fabrication of ferrous metal products are all processes that require energy. Charcoal was adequate, to supply this energy for the relatively simple processes of the early iron-masters. In the fourth decade of the nineteenth century, anthracite and bituminous coal and later coke supplanted charcoal for the smelting of iron. So far as the chemical phases of the process were concerned, charcoal was an ideal iron-furnace fuel. It had practically no sulphur, and its ash, besides being low in quantity, consisted chiefly of lime and alkalies, thus supplying a part of the flux required for smelting the ore. The ash of coal and coke on the other hand, being largely silica, had itself to be fluxed with bases added to the charge. Physically, however, coke proved to have many advantages over charcoal, which could not be used in the furnaces of today. The chief reason, however, for the change from charcoal to coke was the impossibility of maintaining an adequate wood supply.

Jan 1, 1941

By Kelly GD

Prior to 1986, users of satellite based remotely sensed data were almost exclusively reliant on the United States Landsat series of satellites to monitor our Earth's resources. This situation changed when France, Belgium and Sweden launched SPOT-1 in 1986. The year of 1988 saw the Japanese also enter into the earth resource satellite business. The Japanese launched an earth resource monitoring satellite with an emphasis on marine resources, hence the name MOS-1 (Marine Observation Satellite). Many more remote sensing instruments are planned for launch by these nations and others in the next 10 years.

Jan 1, 1990

By D. E. Thomas

Oxidation rate constants were determined for Cu-Pd and Cu-Pt alloys as a function of alloy composition and temperature. Reaction products were identified. Relationship between oxidation rate constants and diffusion constants in the reaction zones is discussed. THE mechanism of oxidation of alloys is consider--'¦ ably more complex and not so well understood as that of pure metals. The oxidation of a one-phase binary alloy of which one component is a noble metal should logically be the simplest case of alloy oxidation, for in this case one is concerned presumably only with the oxidation of the base metal and the diffusion process by which it reaches the reaction site. This had led a number of investigators to study such systems. Probably the earliest work was that of Tammann and Rienacker' on the tarnishing of Cu-Au alloys at temperatures up to 300°C. These alloys oxidize according to the logarithmic law, that is, the film thickness is proportional to the logarithm of the time. The rate of film formation was found to decrease with increasing gold content. Raub and Engel² investigated the oxidation of Au-Cu, Cu-Pd, Au-Ag-Cu, Au-Pd-Cu, and Ag-Pd-Cu alloys at 750°C in air. These alloy systems form a continuous series of solid solutions at the temperature of oxidation with the exception of those containing silver. Au-Cu alloys oxidize parabolically, the rate constant decreasing slowly with increasing gold content up to about 15 atomic pct* Au, and more rapidly thereafter. An alloy with 14 pct Cu forms only a very thin layer of CuO on the surface and probably also a subscale.† Alloys containing more than 14 pct Cu have scales consisting of CuO and subscales of Cu,O embedded in nearly pure gold. The Cu-Pd alloys obey the parabolic law except for slight deviations for alloys containing 53 and 84 pct Cu. The overall oxidation rate decreases rather smoothly with increasing palladium content. A scale consisting of a thin layer of CuO and a thick layer of Cu²O and a subscale of Cu²O embedded in nearly pure palladium was observed for alloys containing 84, 53, and 30 pct Cu. An alloy with 19 pct Cu formed only a subscale of CuO embedded in nearly pure palladium, and an 8 pct Cu alloy formed only a thin film which was presumed to be PdO. The ternary alloys considered by Raub and Engel oxidized in much the same way as did the binaries. Wagner and Grunewald³ found that Ni-Au alloys, oxidized at 900°C in oxygen, formed a scale of NiO and a subscale containing NiO and gold. The overall oxidation rate increases with increasing gold content, passes through a maximum and then decreases to zero for pure gold. The fact that gold increases the oxidation rate was attributed to "pores" in the scale. Kubaschewski' investigated the air oxidation of alloys of platinum or gold with up to 10 pct Cu or Ni at temperatures in the range 300" to 1550°C. Parabolic behavior was noted for all alloys except Au-Ni, with rates decreasing in the order Au-Cu, Au-Ni, Pt-Ni, Pt-Cu. The diffusion coefficients for the latter three systems are known, and they decrease in the same order. However, activation energies for the oxidation of these alloys do not agree with the activation energies for diffusion in the respective alloy systems. Kubaschewski and Goldbeck7 nvestigated the oxidation of Ni-Pt alloys in air at temperatures of 600"

Jan 1, 1952

By J. W. Leonard, C. L. Jiang, B. K. Parekh, X. H. Wang

The selective depression of pyrite from the Kentucky No. 9 coal seam was systematically examined using various kinds of inorganic and organic chemicals. Most of the organic chemicals tested showed little selectivity in pyrite depression. It was found that both orthophosphate and pyrophosphate were effective for the selective depression of coal pyrite in coal flotation using fuel oil as a collector. At substantially low concentrations of pyrophosphate, the flotation of coal pyrite was completely depressed over a wide pH range, while the coal flotation remained unaffected. The mechanism of the selective depression of pyrite by phosphates was explained with the help of thermodynamic calculations of iron-phosphate-water systems and zeta-potential measurements. It was shown that pyrophosphate reacts strongly with the iron ions of pyrite to form stable hydrophilic iron pyrophosphate complexes on pyrite surfaces.

Jan 1, 1999

By Ben DiFiore, Richard DePew, Nate Long, Adrian Naranjo-Castillo, Chris Petta, Robert Auber

The Walworth Run stream was brick-culverted in the 1800s, converting it to a 16-ft diameter sewer. This Cuyahoga River tributary contributed to the infamous burning river that became the catalyst for USA’s environmental movement. The NEORSD has been working hard to reduce CSOs here, most recently by diverting Walworth Run’s 882 MGD of flow to the new Westerly Tunnel. This had to consider structure age/size, alluvial/glaciolacustrine deposits (requiring several ground support systems, groundwater control), and maintenance of massive flows. This paper examines challenges identified during design that supported the contractor in development of a risk-mitigating plan, culminating to successful implementation.

Dec 1, 2022

By P. Louis

Although cobalt is known and used for its hardness and wear resistance, ductile cobalt can be obtained by electrolysis in chloride solutions, under the following conditions : pH : 1.5 - 2, Co++ : 30 - 60 g/l, current density : 100 - 500 A/m2, temperature 40 - 70°C. No explanation was found for the ductility of the deposit under these conditions. Indeed the ductile P (FCC) cobalt and the hydrogen contents in the cobalt deposits are nearly the same as those obtained in a sulfate media, which gives brittle depo¬sits under equivalent electrolysis conditions. Malleable cobalt sheets can be easily obtained under the proposed conditions which could lead to new applications for cobalt.

Jan 1, 1988

By Steve Tadolini

Underground roof falls can have devastating effects on the safety of operations personnel, and equipment, and seriously impact production. Immediate steps are usually taken to danger off and secure the area while clean-up efforts are designed and implemented. A critical step, often overlooked due to production demand, is the determination of - why the roof fall occurred so that additional occurrences can be avoided in future developments or what measures can be taken to identify areas that have similar ?symptoms?? Forensic engineering includes the investigation of materials, products, structures or components that fail or do not operate/function as intended. The authors define forensics in ground control engineering as the study of evidence discovered while examining underground roof falls by applying expert observational techniques and established mining engineering principles to determine the probable cause, hypothesize solutions, and design engineering safeguards to prevent reoccurrences. Simply stated, the primary steps in the forensics of underground roof fall techniques are: ? Assess regional and local conditions prior to the event. ? Assess post-event conditions. ? Hypothesize plausible ways in which the pre-event conditions ? became the post-event conditions.Search for evidence that either denies or supports the various ? hypotheses.Apply engineering skill to relate the various facts and evidence into a cohesive scenario of how the event may have occurred. This paper details the proposed technique by utilizing a roof fall case study that required the examination of five primary factors: mine design parameters, excavation geology, method of excavation, method of support, and mining cycle times.

Jan 1, 2009

By C. A. Lavery

A DISCUSSION is presented of natural gas production and field processing equipment as now utilized in the gas producing areas of the United States, with reference to use of such equipment in Canadian gas areas. The scope of the paper is confined to a general description of various types and methods of using surface production equipment. The discussion is divided under two general groups: well-head production equipment, and field processing. The first will be concerned primarily with indirect heaters, separators, knockouts, and special versions of this equipment. The second major group includes the field processing equipment for handling natural gas. A delineation should be made here as to the meaning of field processing as used in this discussion. We will limit our term to mean such processing equipment as may be used in producing fields to process gas or its by products in a manner that does not require conventional plant practices either in operation or supervision. This covers such equipment as is necessary to complete preparation of gas for sale to pipeline and/ or is necessary to recover valuable components. Under this heading we will discuss glycol dehydration, solid desiccant dehydration, low-temperature separation, mechanical refrigeration, and desorbtion-stabilization. These are all processes involved in preparing gas for final sale or disposal. They do not include the more conventional and large-scale plant process systems.

Jan 1, 1956

By Ricardo Gaviria, Vincinte Acosta

There are major blast design and field procedures differences between conventional blasting in horizontally bedded coal seams and blasting underneath coal seams in a multi seam deposit with seam inclinations of 14 degrees or more.

Jan 1, 1995

By J. W. Oberholzer

The use of computers in the South African coal mining industry has increased during the 1980s. Applications at mine level commenced in the financial and personnel areas of payroll systems, mine accounting procedures and staff record keeping. More use is made now on mines of technical programs for purposes such as mine planning and mine survey calculations. The Coal Mining Laboratory of the Chamber of Mines Research Organization has provided, for a number of years, a service to Chamber member collieries in regard to the application of technical computer programs. Programs presently in use for simulating production procedures and conveyor belt transport systems are described. In addition, reference is made to the collection, storage and analysis of data concerning the performance of continuous miners over a period of eight years. More recently a computer program for the simulation of the cutting action of continuous miner cutting drums has been developed. The use of this program to assist with drum design is explained. The fact that many requests to make use of the programs are received from collieries is an indication of their acceptance by industry. Their interest in running the programs themselves on their own desktop computers has led to the need to convert the software for microcomputers.

Jan 1, 1987

By J Rutter, D Francois-Bongarcon, M Federov, N Odiar, M Scott

There are two fundamental methods for metalliferous sensing of primary crushed ore available for deployment at operations. These methods can be classed as surface measurement techniques (including XRF, LIBS, NIR, SWIR) or penetrative/semi-penetrative measurement techniques (including PGNAA, PFTNA, GAA, MR). While the individual sensing technologies exploit different physical phenomena to measure metal content, penetrative sensor measurements of grade are often regarded to be superior to surface measurement techniques due to the much larger sampling volume penetrative techniques provide. Surface sensing techniques often utilise simpler, established technologies that have considerable benefits in the speed of analysis, capital costs, ease of deployment, social license to operate and operational safety. This paper investigates whether surface sensing techniques achieve adequate sampling representativity of primary crushed rock mass to provide economic benefit over penetrative sensing technologies for bulk ore sorting applications. The paper details the methodology used to assess whether surface XRF measurements change throughout various stages of comminution, and increased surface exposure, from primary crushed ore (top size of -175mm) to finely crushed product for assay (top size -2mm). The methodology was applied to 2 ore mineralisation styles, across variable metals and grades, to identify any associated opportunities and limitations to surface sensing techniques. The results assist in developing a method to determine if surface sensing and measuring via XRF is an adequate representation of the rock mass for bulk ore sorting applications and identify any associated limitations in particle size distribution, mineralisation or natural deportment strength to guide suitable application of surface sensing techniques.

Nov 10, 2020

By J Wen, P Hou, W Yu, M Hu, Z Jiang, C Bai

Vanadium titano-magnetite (VTM) is one of the important iron ore resources in the world. High viscosity and low fluidity are the basic characteristics of hot metal containing vanadium and titanium during the ironmaking process. Clarifying the influencing mechanism of the melt viscosity would be a significant issue for the high efficiency smelting of VTM. In this paper, a self-developed melt viscometer based on the principle of torsional vibration theory was employed to measure the viscosity of hot metal accurately. Simultaneously, the thermodynamic calculations and some modern detection methods were also used to investigate the precipitation behaviour of high-melting-point phases in hot metal containing vanadium and titanium. The measuring results show that the viscosity of molten iron gradually increases with the increase of titanium content when the mass fraction of titanium is between 0.09 wt per cent – 0.50 wt per cent. Meanwhile, the viscosity of the hot metal was affected significantly by the vanadium content. When the vanadium mass fraction was higher than 0.30 wt per cent, the viscosity of hot metal increased sharply, which will have a serious impact on the fluidity of the hot metal. Furthermore, it was revealed by thermodynamic calculations that an increase in titanium and vanadium content would result in the precipitation of high melting point phases such as TiC, TiN, VC, and VN in the molten iron, ultimately resulting in a decrease in its fluidity. Meanwhile, it was confirmed by Scanning Electron Microscope (SEM) observation that the precipitates in the hot metal were compounds consisting of V, Ti, C, and N elements, which agrees well with the thermodynamic analysis results.

Aug 21, 2024