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By G. M. Ritcey, M. J. Slater, B. H. Lucas

The recovery of uranium from acid leach slurries by continuous ion exchange, or solvent extraction using sieve-plate pulse columns, is compared. Differences in processing costs are of prime concern and can be related to differences in the unit operations of the two methods, as well as the chemical and physical properties of the slurry. Parameters are defined for the operation of the solvent-in-pulp process and the design of the continuous ion exchange column. Pilot plant operating experience with both recovery systems is described, and an overall assessment of the relative costs is presented.

Jan 1, 1973

By Kevin Connor

The Government's ban on all commercial mining operations, except for small-scale artisan exploitation of alluvial gold deposits, continued throughout 1985. Minerals produced were kaolin and lime for agricultural uses, and experimental peat harvesting for energy applications. The total value of the minerals produced during the year was estimated at $1.1 million .2 In early 1985, an agreement between the Government and Amoco International Oil Co. was ratified for a petroleum exploration concession covering 248,000 hectares of Lake Tanganyika. Onshore exploration in the Ruzizi Plain was already under way the last half of 1985. By yearend, enough seismic information was available that Amoco hoped to complete data analyses, determine onshore drilling sites, and begin drilling operations before the end of 1986. Also to begin in the latter part of 1986 were seismic studies of Lake Tanganyika. Throughout 1985, Amoco officials were negotiating with the Government of Zaire for expanding the exploration acreage into that country's portion of northern Lake Tanganyika and the Ruzizi Plain. An agreement between Amoco and Zaire could have important beneficial economic implications for both Zaire and Burundi, and onshore seismic work in Zaire logistically supported from Bujumburi could begin almost immediately.

Jan 1, 1987

By Adrian Moore, Alan Richards

A real-time system for prediction of the effect of meteorological conditions on airblast overpressure levels has been established in the Hunter Valley Coalfield in Australia. Real-time meteorological data from continuously operating sounding equipment and a predictive meteorological model is input to an atmospheric refraction model that enables the effect of meteorology on airblast overpressure levels in the area surrounding the blast site to be evaluated. Graphical outputs from the model, which are superimposed over a scaled airphoto of the mine and surrounding area, show the extent that airblast levels will be increased. When combined with inputs that quantify the effect of blasting specifications, the airblast levels that will result in the surrounding area from the combined effect of blasting specifications is determined. The model permits those responsible for blasting to make more accurate decisions on suitable times that blasting may take place to conform with applicable airblast limits.

Jan 1, 2009

By W. M. Weigel

WHILE electric lamps both of the cap and hand type are being introduced into many mines requiring the use of safety lamps, the oil-burning safety lamp is still used in the great majority of cases, and even where the former are used the latter must continue to be employed when testing for gas. It is not the intention to discuss here the relative merits of the two types, but simply to give a comparison of the illuminating effect or candlepower of several kinds of ordinary safety lamps used for general work and for testing. Few data have been published in recent years on this subject and because of this it is hoped that the following information may be of some interest and value. The lamps tested were in all cases. of standard size and in good condition, all practically new, and were selected from a collection of about 100 with a view to obtaining results on as many different common types as possible. With the exception of the gasoline-burning lamps, five different oils were used in each lamp to determine whether -particular oils were suited to particular lamps and whether there was any great difference in the illuminating power of the different oils, or whether some oils would maintain their illuminating power better than others throughout a working period of 8 hr. No attempt was made to determine the amount or cost of oil burned by each lamp, but the condition of the lamp, wick, glass, and gauzes was noted after each test.

Jan 8, 1916

By R. L. Wiegel

The two questions considered in this study are: (1) what similarity is there in the liberation of magnetite from various iron formations, and (2) how is this liberation affected by the size reduction technique employed. Twelve sample suites were obtained from commercial concentrators processing magnetite iron formation in the United States, Canada, and Australia. These samples have grades in the range 15 to 45% magnetite iron and approximate mineral grain sizes o f 50 to 2000 microns. Efforts were directed at measuring the liberation characteristics of the samples obtained from the concentrators primary grinding mills. The Davis tube, a laboratory magnetic separator, was used to concentrate individual size fractions of the size reduction product to determine liberation data. These liberation data were compared with relationships calculated from a highly idealized mathematical model of liberation in a binary mineral system. The results of these comparisons have been encouraging for nine or ten of the twelve samples tested. This leads to the conclusion that for most commercial iron formations, at least with conventional rod mill size reduction, it is possible to quantitatively characterize liberation with two parameters: an effective mineral grain size and ore grade. Limited laboratory size reduction tests as well as one of two sets of liberation data from commercial primary autogenous grinding lend some support to the contention that autogenous grinding can affect mineral liberation.

Jan 1, 1976

By A. Holder

A major mud push occurred on the 870 m production level, scraper drift block cave at Dutoitspan diamond mine in November 2011, during which it is estimated that more than 4 400 m3 of mud engulfed the west cave. The production level was successfully evacuated during the mud push with no loss of life or injury to personnel, thanks largely to mine employees being well trained in and adhering to on-mine mud rush evacuation procedures. All access to the west cave was lost as a result of the mud push. Clean-up operations are currently under way to regain access to the production level, to establish the extent of damage to scraper drifts and equipment, and to evaluate what remedial works may be required to resume production. The magnitude of the Dutoitspan mud push necessitated a detailed investigation into the key contributing factors leading up to the incident, which are discussed in this paper. Mud rush mitigation measures in place on scraper drift block caving operations at Dutoitspan, Bultfontein, and Wesselton diamond mines in the Kimberley area are critically reviewed. Recommendations are furthermore made for enhanced mitigation based on mud rush risk profiles derived for different production areas in these old scraper drift block caves. Keywords mud push, mud rush, scraper drift, block cave, mitigation factors, risk profiles, risk management structure.

Jul 1, 2013

By D. Vogt

"Rock has been cut in the process of mining since before the invention of explosives. Today, we seek to return to cutting to reap the benefits of continuous operations for South African underground hard-rock mines, to improve speed of access to the orebody, and to improve the efficiency of mining operations.Development of new technology fits within a framework of engineering knowledge. By understanding the characteristics of the rock, the tools we use to cut it with, and the history of mining and rock cutting, we can see the genesis of the road-header, the longwall, and the continuous miner, all drag bit cutters. They have emerged as the solutions of choice for underground mining of softer materials such as coal and potash. In hard rock, the challenges are the forces required to break the rock, and the wear of the tools caused by the rock’s abrasiveness. Only disc cutters currently handle the challenges, and even then, often not economically. New materials like thermally stable diamond composite will help, as will combinations of mechanical cutters and other methods such as high-pressure water or high temperatures.It is not clear what will emerge as the consensus technique for hardrock cutting. Experience teaches that development is expensive and the market is small. Will mining companies partner with equipment developers to make the technological leap? Or will the solution come from a systems approach, not considered here?IntroductionBlasting is the dominant method of breaking rock for the purposes of mining. When used underground, blasting is part of a batch process. If rock can be cut rather than blasted, mining can become continuous, leading to process and efficiency improvements.Coal produced from underground mines is now predominantly excavated using mechanical means, but underground hard rock is still broken primarily by explosives.This paper traces the history of rock cutting, reviews the main physical processes that are or could be used, and comments on the future. It is written from the perspective of narrow-stope hard-rock mining typical of South African gold and platinum mines."

Jan 1, 2016

By Pradhan GK

Blasting is one of the most important operations involved in surface coal mining. The removal of over-burden waste in surface coal mines of India had experienced many improvements in terms of blasting, explosives selection, blast design, equipment selection, deployment. etc. Two case studies of very large surface coal mines have particular importance in their blasting operations. Both these units have been equipped with large capacity excavating machines, hauling units and also have some difficult mining situations. Blasting is done in benches in close proximity to human dwellings and over coal seams developed by underground methods with problems of high wall stability etc, as well. The various steps taken to improve the blasting operations ensure smooth operation of the equipment to meet the targetted coal production.

Jan 1, 1991

By C. L. Reichardt

Pressure exerted on gold producers by regulators, project financiers and civil society in the wake of the Baia Mare tailings spill in Romania during 2000 prompted most responsible gold companies to sign up to the International Cyanide Management Code for the Manufacture, Transport and Use of Cyanide in the Production of Gold (the Code). The Code stipulates a ?cradle to grave? approach more comprehensive than that applied to any other mining reagent and poses particular challenges for operators who use cyanide-bearing tailings for backfill. This paper examine some of the challenges for Code compliance facing deep underground gold mines that employ backfill technology, most particularly the requirement to demonstrate that the potential migration of cyanide (and its degradation products) from emplaced backfill will not have an unacceptable impact on worker health and safety or the receiving environment, either during mine life or after closure. Although the Code only contains a single reference to backfill, more careful consideration confirms that most sections of the Code that deal with tailings management are potentially applicable to mines where tailings material is used for backfill, as are certain principles pertaining to aspects of operations, worker safety, emergency response, training and dialogue with stakeholders. For gold mines of the Far West Rand, the most significant cyanide-related risks associated with backfill operations relate to worker exposure to cyanide-bearing seepage and HCN gas. There is potential for seepage of cyanide-bearing water from backfill to compromise the beneficial use of surface and groundwater, and thus impact on downstream users and ecosystems. However, the extreme depth of mining and the specific geological and hydrological controls on the Far West Rand suggest that the potential environmental risks associated with backfill are likely to be considerably less significant than the cyanide-related risks to the workforce.

May 1, 2007

To develop a system which will effectively detect and extinguish fires in underground fueling areas while also providing a warning for nearby miners. Approach A system involving optical fire sensors. automatically-released dry chemical and aqueous film-forming fluid (AFFF) fire suppressants, and automatic alarms was designed from off-the-shelf, state-of-the-art components, and was in-mine tested at two mines in the two typical underground fueling area situations: fuel transfer areas and fuel storage areas. How It Works As mines become more mechanized, the number of fire hazards increases since fueling areas are more abundant. Fire hazards are especially serious in deep mines, since escape time is longer. To help solve this growing problem, the Bureau of Mines, in cooperation with the Mine Safety and Health Administration (MSHA) and the National Fire Protection Association (NFPA), has developed and in-mine tested a cost-effective fueling area fire protection system. The system was designed to be rugged enough for reliable, long-term use, yet to utilize state-of-the-art, off-the-shelf components to maintain cost-effectiveness. The system consists of cross-zoned, ultraviolet flame sensors used for quick response to fire, and a dual-agent fire suppression subsystem. A dry chemical is used for fast fire -knockdown," and AFFF (or "light water") is used for long-term, fire-securing capability. The basic components of the system are shown in the schematic illustration.

Jan 1, 1982

By G. A. Tret’yakov, V. A. Simonov, I. Yu. Melekestseva, V. V. Zaykov, N. N. Ankusheva

The Kyzyl-Tashtyg massive sulfide polymetallic deposit is situated 120 km north-east of Kyzyl (the capital of Tuva Republic, Russia). It is located in the Ulug-O volcanic zone which is interpreted as the northern segment of the Kaa-Khem rift in Sayano-Tuva marginal sea, one of the Paleoasian Ocean margin (Fig. 1) [Zaykov, 2006]. Since its discovery in 1946 the deposit has been studied by many researchers. Significant information was published by Kuzebny et al. [2001] and Zaykov [2006] who proposed volcanogenic-sedimentary genesis. A single reference in English about Kyzyl-Tashtyg is available [Herrington et al., 1999].

By B. G. Slay, J. P. Pritchard, J. T. Pierce

A short discission is given of the cryotron us a supercozductitzg- switch. The parameters of interest such as gaiz, critical gate current, critical control current, and critical surface current density ave described. The photomask-photoresist process makes possible the study of much narrower dimensioned cryotrons than previously possible using mask stencils. Data is given for the above parameters as a function of width, thickness, temperuture, and crossing ratio. Photographs of the various circuits used are shown. The techniques involved in making connection to the circuits and the precautions taken to avoid side effects in the measurements are discussed. In particular data is given for critical currents of sipercotzducting. lines down to 2X 104 in. A vise in critical surface current density is obserced jor the strallev lines in both lead and tin. A discussion of the ihact of these measurements in the design of future cryotron circuitry is given. In addition to the improvement in device density achieved by simple scale reduction. additonal gains in density may result through improved device form factor. THE cryotron is a superconducting current switch, invented by D. A. Buck.' Fig. 1 shows a typical crossed-film cryotron. Usually the gate is made of tin and the control is made of lead. The critical gate current, is the current that drives the gate resistive with zero current flowing in the control. The critical control current, I is defined as the current in the control necessary to switch the gate resistive with a small monitoring current in the gate. The gain of the device, G, is defined as Since for uniform thin films G should be proportional to the gate width divided by the control width, it is convenient to define the critical surface current density, Jcg, to be the critical gate current divided by the gate wldth. The data which follows will show that, for a given control width, I, is relatively constant. Thus, by measuring Jcg the change in gain as a function of gate width may be measured without measuring I,.

Jan 1, 1967

By Hugh M. Roberts

In the spring of 1915, then a 30-year old geologist in the employ of the E. J. Longyear Co., of Minneapolis, Minn., I accompanied prospectors to ex- amine outcrops of supposed nickel ore situated a mile or two in from the shore of a lake in the Kenora district of northwestern Ontario. The deposit proved to be bog iron ore containing traces of nickel. We were stormbound there for three days, a circumstance which gave rise to a tale that was told at our fire one night. It seems that Sandy and Jock, two prospectors, were crossing the bay of a large lake in a canoe. They were bucking headwinds; the waves grew higher. Jock called out from the stern, "Sandy, can ye na pray a little." Sandy pressed his knees a little closer into the bow and, between strokes of his paddle, sought for words, which came haltingly, "Save us this time . . . Oh Lord . . . and we promise . . ." when Jock, peering through the spray sang out, "I would na commit yourself, Sandy, I think I see lond ahead."

Jan 1, 1965

By Gerrit V. R. Goodman, Charles D. Taylor, Edward D. Thimons

Future coal mining systems will be able to cut from crosscut to crosscut where advances could exceed 100 ft. However, limitations arise when ventilating such mining systems. In deep advance mining, there would be no workers at the face to advance ventilation tubing or curtain manually. Traditional methods also provide no means for maintaining face ventilation after the miner backs away from the face. U.S. Bureau of Mines research is studying means to provide effective ventilation at cut depths beyond the current limit of 40 ft. Several innovative ventilation schemes are currently being considered. One such method is the use of a jet fan to ventilate a deep cut. A jet fan is simply a freestanding fan using little or no ducting to direct the ventilation flow. Jet fan testing in a 90-ft entry revealed that higher exit velocities and greater penetration depth occurred when various configurations were used to confine and direct the air flow. Additional testing also indicated that 2,200 cfm of fresh air was delivered to the face 90 ft distant when a check curtain was used to limit entrainment around the fan. Without this curtain, this quantity dropped to only 1,000 cfm This testing indicated that a jet fan was capable of providing ventilation to a distant face area. It also highlighted potential problems, such as recirculation at the fan and reentrainment in the jet flow. Despite these potential problems, jet fans may be adequate for ventilating cuts exceeding 40 ft.

Jan 1, 1992

By J. E. Tiffany

FOR blasting in coal mines the U. S. Bureau of Mines recommends that permissible explosives be used exclusively, that these shall be fired electrically, and that where feasible the working place shall be cut or sheared. These recommendations are made to promote safety and prevent mine explosions. Although permissible explosives are not flameless, their lower flame temperature and shorter duration of flame make their use safer than that of non-permissible explosives. Mixtures of air with both methane and bituminous coal dust, which are liable to occur in coal mines, may be ignited by coming in contact with any type of flame or spark of sufficient temperature and duration or by the firing of a blast. In a working place where a blast is to be fired, in addition to the use of permissible explosives, adequate ventilation for the dilution and removal of accumulations or outbursts of flammable gas should be provided. Bituminous coal mines should be rock-dusted as a means of rendering the coal dust harmless. The efficient use of permissible explosives depends upon the proper preparation of the working place, standardized drilling, the strength characteristics of the explosive, and the use of a proper weight of charge. Experienced shotfirers should load, tamp and fire all holes. The major part of the information and data here presented is based on the results of efficiency tests made in large producing mines of Pennsylvania and Illinois. Bureau of Mines Report of Investigations, Serial No. 2697, describes how a standard method of blasting was worked out and put into operation in a mine in southern Illinois.1 This paper contains a description of the methods worked out subsequently in another mine in that district.

Jan 1, 1928

By Shoobridge PH

Operating difficulties during 1977 with the Imperial Smelting Furnace operated by Sulphide Corporation Pty. Limited at their Cockle Creek zinc-lead smelter were found to be caused by premature softening of sinter in the upper shaft of the furnace. This soft- ening was shown to be a consequence of raw materials and operating policies which led to unusually high levels of both lead and silica in a sinter of low basicity. A programme of softening tests and micro-examination of a range of sinters established that premature softening occurred when lead and silica increased to the point where a lead-calcium silicate with a low lime content became the major continuous phase in the sinter. This information was used to define a range of compositions which kept the softening temperature acceptably high for furnace operations.

Jan 1, 1978

By S. J. Mitchell

An analysis of bolting reinforcement of several large [approximately 18 m (60 ft) cube] pillars was performed. The many overcoring stress profiles in pillars at the mine were used to produce generalized stress distributions at various stages in pre- and post-failure. A complete stress-deformation curve was estimated from this data. The effect of pillar bolting on the load-deformation behavior was extrapolated from the observed unbolted behavior. Bolting can increase pillar strength by up to 10 percent. The effect of bolting on general mine stability was examined with a shoW computer analysis. The computer model was calibrated against measurements performed at the mine, and produced good agreement between measured and modeled stresses. The analysis indicated that bolting increases the bolted pillar safety factors in the event of additional pillar failure by a small amount (approximately 5 percent). Progressive pillar failure is unlikely, because arching transfers most load from yielding pillars to large unmined abutments rather than to the smaller panel pillars.

Jan 1, 1984

Tailings facilities tell a story to the public about how the mining industry manages its activities. They also create a risk that must be managed for the long term. All the knowledge and technology is available to safely design, build, operate and decommission tailings facilities.   Tailings at Waikato North Head Minesite are pumped as slurry, over long distances and against high static discharge heads to backfill the excavated area. WNH is, under the mining licence, obliged to reconcile the topography of mined areas to the closest possible resemblance of the original terrain. The active tailings areas are located near main operational facilities and detailed plans and procedures have been developed to ensure a safe and continuous operation.   The concentration plant is designed as two identical and independent plants. Each plant has its own tailings slurry pumping system.   This paper represents a general overview of the tailings disposal practice at WNH mine site. It discusses tailings delivery, construction and water management.

Jan 1, 2004

Jan 1, 1956

By R. Maddin, N. Ujiiye

ALTHOUGH the cold-rolled texture for body-centered-cubic metals and alloys is well known (see, e.g., Barrett'), the pole figure representing the texture may be interpreted in two ways. It may be regarded as consisting of several ideal preferred orientations with an associated spread (a view which is shared among several investigators2), or it may be regarded as consisting of two sets of continuous preferred orientation also with an associated spread."." Recently, Chen and Maddin7 noted a stable (001) [loo] end orientation for molybdenum single crystals rolled at low rates of reduction provided the initial rolling. orientation" was close to the cube ori-

Jan 1, 1957