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By W. F. A. T. Meihack

The scope of this paper is confined to gas-fluidized beds in pyrometalurgical applications. After considering the general characteristics of these fluidized beds, the author deals with their potential applications, using the following processes, which are currently under investigation, as examples: pretreatment of chromite, prereduction of manganese-ore and iron-ore fines, roasting and prereduction of ilmenite, and roasting and pyrolysis of gold-bearing pyrite. He concludes that fluidized beds are potentially of great benefit to the metallurgical industry, although much developmental work remains to be done.

Jan 1, 1986

By R. L. Grayson

"Compliance standards for respirable dust, which are reduced because of high quart: concentrations, have become an industry-wide problem. Research on the physical and chemical character of quart-classified particles in respirable coal mine dusts indicates that they may exist in intermixed layers or may be coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quart: particles of a mine dust are ""pure,"" then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should be lowered. lf, however, quart: is locked inside another material matrix, or coated, a reduced compliance standard may not be appropriate.Although much research has been done on coal workers' pneumoconiosis (CWP) over the past decades, the etiologic agents of the disease still have not been pinpointed. The predominant methods of characterizing respirable coal mine dusts were bulk analysis techniques for determination of elemental and mineralogical concentrations, the results of which were used in statistical analyses to determine relationships between dust composition and the occurrence of CWP. These methods are incapable of finding the etiologic agents in the dust primarily because of complicated and confounding physiochemical factors, which may be discovered if the focus of characterization was done on a dust particle level.The SEM/EDXA-based research discussed here shows a significant difference in the number of ""pure"" quartz particles in respirable dusts collected from different mines. Some of the results have been reported previously (Grayson, Andre, and Simonyi, 1988). Concurrent research by other investigators (Wallace et al., 1989) demonstrates an SEM/EDXA-based methodology to pinpoint the location of the ""contaminating"" substance(s ) in a quartz-classified particle. The research of the European Economic Community has also begun analyses on the respirable-dust-particle level (Robock and Bauer, 1988).Since the compensatory and intangible costs of CWP are substantial in the United States, it is important that the etiologic agents be determined and then either controlled or neutralized in a cost-effective way. This line of research is especially important consid-ering the forecasted. near-term growth of coal production and the evolution of high productivity longwall panels (an immediate problem in compliance) and continuous mining sections ( a probable future problem).This need has been accentuated now that nearly all respirable dust samples submitted to MSHA are analyzed for free silica (Tomb, Parobeck, and Gem, 1986). Today a real problem exists in the coal industry, both underground and surface, because of high quartz levels in respirable dusts causing substantially reduced compliance standards (Murphy, 1989).The combined results of the respirable dust particle investigators indicate that conventional bulk sample analyses may not faithfully represent the amount of biologically available or active quartz in all mines with a high level (greater than 5% ) of quartz in the dust For example, some mine dusts might contain predominantly occluded (or coated) quartz particles where bulk analysis would result in anomalously high ""free silica"" measurements. The same result would occur when quartz particles are intermixed substantially with other minerals that can alter the surface of the composite particle away from a quartz-behaving character."

Mar 1, 1992

By R. L. Grayson

Compliance standards for respirable dust which are reduced because of high quartz concentrations have become an industry-wide problem. Research on the physical and chemical character of quartz-classified particles in respirable coal mine dusts indicates that they may exist in intermixed layers or may be coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quartz particles of a mine dust are "pure," then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should be lowered. If, however, the quartz is locked inside another material matrix, or coated, a reduced compliance standard may not be appropriate.

Jan 1, 1990

By D Millette, F Gay

Surface tailings are finely ground waste materials produced in all mines after the mineral or metal has been removed from the metallurgical process. Current methods for disposal of tailings involve constructing dams, dumping into existing waterways, and depositing as backfill underground. Each method has its drawbacks in terms of cost, level of complexity, safety and environmental concerns. Backfilling is the process whereby waste material (generally metallurgical tailings, prepared aggregates or a combination) is placed from the surface back underground into open mine workings via conveyor belts, hydraulic or pneumatic pipes or gravity. In the backfill process common difficulties are expensive placement costs, equipment wear and the ability to meet early and long-term strength requirements. Traditional tailings transportation in pipes involves the use of water as the transport medium. Foam technology involves the introduction of micro-air bubbles that replace the water as the main transport medium. This air can be removed after placement if necessary, by the addition of a defoaming agent. This could produce an under-saturated stable cake. Foam technology has the potential to revolutionise surface tailings disposal and backfilling by providing a less expensive and environmentally safe alternative to those just described.

Jan 1, 2000

By Eamonn F. Maher

Superconductivity is one of the most remarkable scientific phenomena ever investigated. It is the phenomenon whereby some materials exhibit zero resistance to the passage of an electric current when cooled to low temperatures, and requires a quantum mechanical explanation. Four Nobel prizes in physics have been awarded specifically on the subject of superconductivity, with many more enabled by superconducting technology. For example, particle beams are generated in accelerators and manipulated in ?particle beam lines? in the ?Big Physics? projects around the world eg. at CERN, Geneva, leading to major discoveries in fundamental particle physics. Similarly, at the JET Propulsion laboratory near Oxford, U.K, controlled nuclear fusion has been demonstrated, and magnetic containment of plasmas is key. In the chemical and biological sciences high field NMR spectroscopy has become indispensable for examining organic matter, revealing the mysteries of the workings of cells, genetics, and in the development of new polymers and pharmaceuticals. With all these very advanced uses for superconducting magnets, it is easy to forget that superconductivity is big business, not just a scientific curiosity. MRI (Magnetic Resonance Imaging) superconducting magnets, the key component of high resolution body scanners, use approximately half of the world?s superconducting wire ? the other half being mostly used in accelerator magnets. The MRI market is about 3 billion dollars per annum, and one MRI magnet uses 200km of wire. New applications for superconducting magnets are now appearing including ?Catheter steering?, enabling much shorter timescales for life-saving brain tumour removals and ?Functional MRI?, a whole new area in patient diagnostics. Whilst the use of low temperature superconductors (LTS) is now well established commercially in superconducting magnets and niche electronic applications, the application of LTS in electric power distribution and transport has been very limited to date. It is now more than fifteen years since the so-called High Temperature Superconductor (HTS) materials were discovered: these can be operated at liquid nitrogen temperatures rather than liquid helium temperatures. However, materials processing and scale-up issues have prevented their widespread use, and in particular the required price/performance criteria are only beginning to be reached except in certain niche markets. BSCCO (Bismuth Strontium Calcium Copper Oxide) tapes up to one km long are now readily available, and have been demonstrated in high current cables for power distribution networks, but the general consensus is that 1) it is difficult to reduce the price much further because of the silver matrix required and 2) in applications where coils are required eg. motors, generators, transformers etc the properties of BSCCO are rather poor because of the critical current dependence on magnetic field. Magnetic fields are always associated with coils and windings, and such fields are of course fundamental to the operation of all electrical machines. YBCO (Yttrium Barium Copper Oxide) however, has good characteristics in field and for the last few years there has been intensive research and development costing several tens of millions of dollars worldwide into the scale-up of production of so-called ?coated conductor?. This ?second generation? tape can be produced by any of many different film deposition techniques, with more or less success for short lengths, but as yet it is unavailable in lengths more than a few tens of metres.

Oct 1, 2003

By C Slaughter, J C. Tien

Commonly held ideas about effective training have long emphasised the importance of realism. Realistic training builds better experience among the trainees and a better perspective on the training material, making training more effective. While great strides have been made in this realm for mine safety and mine rescue training there are still areas that can be improved. One possible area is the expanded use of a mine fire simulation program where the migration of gases and smoke can be realistically displayed in an emergency, and outcomes varied as different conditions are being simulated. The use of mine fire simulation software potentially allows for the creation of more realistic scenarios in that smoke advance rates can be measured and recreated in evacuation scenarios, or that gas readings in mine rescue training can be dynamically and realistically changed to show the effect that time has on the fire scenario.CITATION:Slaughter, C and Tien, J C, 2015. The potential use of mine fire simulation software as an enhancement for mine safety and mine rescue training, in Proceedings The Australian Mine Ventilation Conference, pp 285–290 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By G T. Hefter, P Singh

Sulphur dioxide oxidation is an attractive alternative anodic reaction to the evolution of oxygen in copper electrowinning. Accordingly, the electrochemical oxidation of SO2 in aqueous 1.0 x 10-1 mol/L NaClO4 has been studied at pH 2.3 using platinum and glassy carbon electrodes. On the platinum electrode SO2 oxidation occurred on the forward scan at 0.96 V and on the reverse scan at 0.63 V. For GC, a single SO2 oxidation peak occurred at 1.40 V on the forward scan. SO2 oxidation on both electrode substrates was hampered by oxide layer formation. The electrode could be reactivated however, by oxide layer reduction. Although reactivation was most successful for platinum, SO2 oxidation on platinum is quite complex, with this evidenced by the reverse scan anodic peak. Glassy carbon shows simpler behaviour and thus, is the preferred substrate for SO2 oxidation.

Jan 1, 1998

By S M. C Verryn

The amount of raw material used in the production of cement can be reduced by partially supplementing it by pozzolanic waste material without changing its properties negatively. This paper discusses results of an investigation using slag from the Pt industry, from the production of steel using Midrex processes as well as fly ashes from different coal power plants in South Africa. These are blended in a 20 per cent slag or fly ash to 80 per cent cement ratio. The properties of the mixtures depend on the phase composition, chemistry, grain size and the sources of the materials. The results are promising, but show variable behaviour depending on slag and cement composition. Compressive strength tests as well have heat flow curves showing the hydration behaviour, indicating that 20 per cent addition of slag or fly ash to ordinary Portland cement is viable. There is a large potential to use slag in cement mixtures and this study can be used to develop cements that will positively influence CO2 emissions and help to reduce large slag and fly ash stockpiles.

Jan 1, 2008

By Thomas C. Poulter

Abstract The Poulter seismic method of geophysical exploration is an attempt to obtain an increased efficiency in the conversion of the energy of an m~pl06ion into useful energy which has directive properties and which contains a minimum of random frequency and random phase relations. Very little effort has been made in the past to simplify OT even control the uniformity of the seismic energy being introduced into the ground. The Poulter seismic method is also an attempt to improve the signal-to-noise ratio not merely by trying to complete the impartial filtering done by the earth on ,the continuous spectrum of primarily high-frequency energy radiated from a shot point but by applying a frequency control at the point of origin of the seismic wave. The energy from a shot-hole charge is peaked in a frequency which is much higher than will be transmitted through the ground, and its absorption introduces background interference. Only 10 to 20 per cent of the seismic energy of a shot-hole charge .is directed downward in a 90-degree vertical cone, whereas, from a pattern of charges detonated above the surface of the ground, 85 per cent of the seismic energy is included in a 90-degree cone and in some cases it is even confined to as small as a 30-degree cone. This greatly reduces the horizontally distributed energy, thereby producing a marked improvement in the signal-to-noise ratio. The frequency of the signal energy may be peaked in a rather narrow range by the proper application of two or more impulses upon the surface of the ground controlled as to direction, magnitude, and timing. These impulses may be controlled by the reflection shock wave technique, the pressure pulse technique, and the sequence firing technique, using the primary controls as outlined. The information obtained from the study of directivity of seismic energy in a high velocity, uniform material such as the ice on Taku glacier, in the Juneau ice field in Alaska, has been of great assistance in the application of the method to oilfield and mining problems.

Jan 1, 1950

By J. H. Hodgson

"Those of us who have been concerned with the problem of geophysical exploration in southwestern Ontario have followed the development of the Poulter method with much interest. I have much appreciated the opportunity of reading an advance copy of Dr. Poulter's clear exposition and of preparing the following brief remarks on the probable applicability of the method to the Palaeozoic area of southwestern Ontario.During the years 1944 to 1946, the Ontario Department of Mines, in co-operation with the Union Gas Company and the Dominion Natural Gas Company, operated an experimental party in the hope of establishing a seismic technique appropriate to the •area. The results were completely negative. During two summers' field work, no reflections whatever were obtained except in one area near Windsor. It is the •purpose of these remarks to inquire whether Dr. Poulter's techniques might yield favourable results.It was the conclusion of the report on our work that two principal causes contributed to the failure of the method. In the first place, the geological column possesses few elastic discontinuities and those that exist appear to have low reflection coefficients. In the second place, the area is drift-covered in general. This drift complicates the situation by absorbing seismic energy and by giving rise to groups of complicating refracted phases which obscure the entire interesting section of the record. The situation is further complicated by the high reflection velocities and the relative shortness of the Palaeozoic section, these factors combining to bring in a reflection from the basement in about half a second."

Jan 1, 1950

By Pol Duwez, Howard E. Martens

INTRODUCTION THE high temperatures encountered in the operation of jet engines have imposed most drastic requirements upon the materials used in their construction. There are two different approaches to the materials problem connected with the design of parts in contact with high temperature gases. The first approach is to use a material which will perform satisfactorily at a temperature comparable to that of the gas. The second approach is to use a cooling system so that the material is maintained at a temperature appreciably lower than that of the gas. Besides the conventional method .of cooling by means of a liquid in contact with the material exposed to a high rate of heat transfer, a less orthodox method consists of making the part to be cooled of a porous material, so that the cooling fluid can be forced through the pores. In this scheme, the temperature of the coolant moving in a direction opposite to that of the heat flow increases gradually while passing through the porous material, and the coolant forms a protective layer on the surface exposed to heat. This method, referred to as "sweat cooling," was proposed at the jet Propulsion Laboratory in September 1944, and the experimental work on the preparation of porous metals was started early in 1945. The sweat cooling method opens new lines of research in powder metallurgy by extending the field of application of porous metals. The porous metals available at the present time are used mostly as bearings or filters, and a rather limited number of alloys are made for these applications. In addition, the fabrication of bearings or filters does not require a very dose control of the permeability, while in the case of sweat cooling such a control is of primary importance. In designing a sweat cooled part it is imperative to assure a given rate of flow of coolant under certain conditions of pressure drop. Generally, the proper pressure drop and the rate of flow of coolant are deduced from heat transfer and design considerations, and consequently the permeability of the porous metal to be used is also determined. It is therefore necessary for the designer to have available a continuous series of porous metals covering a range of permeability as wide as possible. Contrary to the requirements established in the fabrication of filters, the actual pore size of a porous metal intended for sweat cooling is of little consequence, except for its effect on permeability. The tensile strength is likely to be of great importance for some applications. Since the tensile strength of a porous alloy decreases with increasing porosity, an important problem is to develop porous alloys having the maximum permeability with minimum porosity.

Jan 1, 1948

By L. Alan Weakly

The Powder River Basin is the largest strippable reserve of compliant coal in the United States. It is the mother lode, for this Basin is currently supplying 25 percent of the coal produced in the US annually. This paper updates what has happened in the Basin since 1993 in terms of increased production, higher productivity, changes in mine ownership, safety statistics, new equipment, latest coal technologies, and electrical deregulation ramifications.

Jan 1, 1998

By Luis Tondo, Gary Johnson, Steve Morell

High pressure grinding rolls have been demonstrated by numerous researchers, and at a number of commercial installa­tions to be power efficient comminution devices. They have become almost "standard equipment" in the grinding of cement clinker. However, the technology has been relatively slow to catch on in the mineral processing industry. Part of this may be due to the fact that this relatively expensive machine has not been incorporated into the plant flowsheet so as to fully exploit its power efficiency, and therefore realise the maximum economic benefit. This paper describes the results of a pilot scale test program designed to evaluate the performance of the device with the aim of developing a circuit configuration that better exploits the inherent power efficiency of the machine. The results of the test program clearly show that power savings of about 50% over conventional technology are achievable when the machine is made to produce the final product grind size.

Jan 1, 1995

By Andre Vien, Frank Laroche, David Di Sandro

Back in 1994, Claude Bazin presented a novel method for linking size data from milling models to the feed input of flotation models. It was achieved with the simple addition of a metal/mineral distribution—size distribution relationship. This allows grade and recovery predictions from a varying mine plan via product size distribution predictions. This paper presents a case study where this elegant method has been used to build a very powerful forecaster at a process plant, built from historic operating data. The methodology has been used by this operation to forecast production on a quarterly, annual, and life-of-mine basis since the late 1990s. It has been upgraded several times to incorporate new drivers as the complexity of feedstocks has increased over the years.

By Andre Vien, SANDRO DAVID DI, Frank Laroche

In 1994, Claude Bazin presented a novel method for linking size data from milling models to the feed input of flotation models. It was achieved with the simple addition of a metal/mineral distribution–size distribution relationship. This allows grade and recovery predictions from a varying mine plan through product size distribution predictions. 

By Anne Lemnitzer

Experimental data are the cornerstone of scientific research, providing empirical evidence to validate hypotheses, test theories, inform decision-making and help develop innovative design and analysis methods. However, beyond traditional empirical validations, experimental data have also become the most crucial component of AI algorithms, measuring the algorithms' effectiveness, and allowing engineers to ensure their reliability and applicability. The DFI "Rock Socket Project," awarded in the spring of 2018 allowed for the indispensable, experimental data-based validation of structural shear magnitudes, which have been hypothesized and discussed for years within the deep foundations community and cautiously approached by many design engineers. The fundamental project idea, i.e., the investi- gation of pile shear magnitudes through experimental research, was sparked during a heated discussion in the October 2016 Drilled Shaft Committee meeting in New York. Should we design for amplified shear at the rock socket of a drilled shaft or is this merely an artifact of the p-y design approach? Data were needed to provide consensus.

Nov 1, 2023

By Paul Downing

A major component of an effective blasting company safety program is the self-audit. A self-audit can help reveal hazardous conditions that should be corrected and training needs that should be addressed before accidents occur, insurance claims are filed, and/or fines are levied. Such audits, when they lead to appropriate corrective action, can provide significant economic benefits for employers by reducing the costs associated with insurance claims, accidents, and injuries.

Jan 1, 2001

By R. McDonald, B. C. Maine

CERRO'S power system consists of three main hydroelectric plants and one steam-electric plant. These are located on the eastern slope of the main Andes range at altitudes between 12,000 and 13,000 ft. The hydroelectric group utilizes the watershed which extends for about 150 kilometers south from Cerro de Pasco, divided into two catchment areas which lie adjacent. The northern area serve,, the medium-head plant of Mal¬paso. while the southern area provides for the high-head plants at Pachachaca and Oroya. The rainfall, as registered at the rain gauging stations of the three hydroelectric plants, averages 33 in. per year; all these stations are subject to the same hydrological conditions, and the bulk of precipitation occurs between October and March. Rainfall during the dry season, April till September, has no appreciable effect on the total annual runoff. Table 1 shows the storage capacities of the main reservoirs of the hydroelectric group. The four plants are tied together electrically by a 50-kv. transmission network, the system being 3-phase 3-wire at 60 cycles with a solidly grounded

Jan 1, 1945

By F. Sorensen

ABSTRACT Electricity production by the Electricity Supply Commission of South Africa (Eskom) is the most important beneficiation process for South African coal. As one of the world’s lowest cost producers, energy-intensive industries such as ferroalloys and aluminium were introduced. However the poor were neglected. The white paper on energy policy (Department of Minerals and Energy, 1998) sought to redress this. Also, chasing economic growth to generate jobs resulted in high electricity demand and interruptions. Lifespan estimates of South African coal reserves based upon peak theory vary widely. Approaching peak, coal production in the future will be more expensive and, thus, contribute to more expensive electricity, which could inhibit industrial development unless South Africans work smarter.

Jan 1, 2011

By P. Van Marcke, X. Sillen, G. J. Chen, I. Troullinos, A. Dizier, J. Leysens, X. L. Li, J. Verstricht

"In Belgium, Boom Clay is considered as one of the potential host formations for the disposal of the High Level radioactive Waste (HLW). The URL HADES at 223 m depth at Mol site was constructed in order to study the feasibility of HLW disposal in Boom Clay. Since 1995, the URL R&D programme has focused on large scale demonstration tests like the PRACLAY experiment.The PRACLAY in-situ experiments include a set of three tests: The gallery and crossing test, PRACLAY Heater test and PRACLAY seal test. The main aim of the Heater test is to study at a large scale the thermal impact of a HLW repository on the host rock. The test is housed in the PRACLAY gallery. A hydraulic seal, made of compacted swelling and low permeable bentonite annular ring was installed at the intersection between the heated and the non-heated part of the gallery. The primary objective of the seal is to provide undrained hydraulic boundary conditions for the Heater Test.The PRACLAY gallery was constructed in 2007 and the hydraulic seal was installed in 2010. The bentonite is hydrated by natural and artificial process. The swelling, total pressure and pore pressure of the bentonite are continuously measured and analysed by numerical simulations to get a better understanding of this hydration processes. The performance of the seal is tested systematically by means of gas injection breakthrough tests and permeability tests at interface bentonite / Boom Clay and in the Boom Clay around the seal.The PRACLAY Heater will be turned on at the end of Oct. 2014, since a sufficient seal swelling has been attained to fulfill its role for the PRACLAY Heater test. This paper will focus on the PRACLAY Seal test: How we understand the process behind the hydration of the bentonite and how we test the performance of the bentonite seal."

Jan 1, 2015