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At the meeting of the American Institute of Mining and Metallurgical Engineers, G. S. Rice, Chief Mining Engineer of the U. S. Bureau of Mines, announced the definition of a gassy mine. This definition has been awaited with much interest, especially by the Safety Committee of the Rocky Mountain Coal Mining Institute. It applies to the whole area of all mines, any part of which is on the public domain of the United States. Consequently it will be of wide application in the western part of this country. The safety committee of the R. M. C. M. I. has been hopeful that the Institute would adopt this definition without exception as the codes of rules to be recommended at all mines in the Rocky Mountain area. The statement follows: "The U. S. Bureau of Mines believes that all coal mines are potentially gassy; but for purposes of administration in respect to prevention of explosions and fires, the Bureau recommends the following classification: "Class 1 coal mine-A practically non-gassy mine in which flammable gas in excess of 0.05 per cent cannot be found by systematic search. "Class 2. coal mine-A slightly gassy mine in which (a) flammable gas has been found, ? but in quantity less than two per cent in still air in any active or unsealed-abandoned workings; or (b) flammable gas can be found, but in quantity less than four per cent, in some place from which the ventilating current has been shut off for a period of one hour; or (c) flammable gas can be found,* but in quantity less than one-fourth per cent in a split** of the ventilating current; or (d) flamamble gas is found in quantity greater than' specified rate*** of not more than 25 cu. ft. per minute. "Class 3 coal mine- A gassy mine in which flammable gas is found in quantity greater than specified for a Class 22 coal mine. GENERAL NOTES REGARDING DECISION NO. 3 "(A) Flammable gas found in coal mines is, with rare exceptions, methane. In coal-mining fields where natural gas is found in lower geologic horizons by deep wells which pass through or nearby the coal mines, there have been rare instances of la leakage from the well. Natural gas is chiefly methane; that constituent almost always forms more than 85 per cent of the whole, but it usually contains ethane, propane and traces of butane also. Therefore if the latter gases are found in mine air it is an indication of leakage. The lower limit of explosibility of methane-air mixture when there is turbulence of five per cent and of natural-gas-air mixtures with about ten per cent ethane and associated hydro-carbon gases is 4.6 per cent. The limit therefore varies with the character of the mixture. " (B) To determine the proper classification of a coal mine, it is advisable that systematic testing and sampling be done at least three times in a period of not less than 72 hours. All tests and samples of the mine air, except one, must show an inflammable-gas content less than the maximum limit of the class to which the mine is assigned. In other words, a tolerance of one test or analysis may be permitted to provide for a mistake or a very exceptional occurrence. "(C) When a new mine is being opened in a coal field where existing mines are generally gassy, it is common sense to assume that similar conditions will be found in the new mine, and its development and equipment should be based upon the expectation that it will be assigned to Class 3."

Jan 1, 1926

This paper presents a case study where Cenozoic age detritals and an ancient buried landslide have been modelled in the final walls of an iron ore pit. Orebody 25 is located in Western Australia’s Pilbara region and is an operating pit where a redesign of the final wall cutback was required. The existing slope design utilised a simplistic geological model of mixed conglomeratic, calcretic and clay –dominated detritals overlying deformed bedrock sequences. This simplicity resulted in a conservative design that was not reflective of the slopes performance to that point. Further field investigation was carried out with the results assessed in conjunction with historic drilling, mapping and laboratory testing. A detailed geotechnical model was developed including three conglomerate and two clay dominated units and laterstage calcrete overprinting. The clay units were of significant importance to the stability assessment and resulting slope design due to the thickness and poor strength conditions indicated by the laboratory and field testing. However, the drilling investigation shed only limited understanding as to the origin of the clays and thereby how they should be treated as a component in the stability analysis. A comparison of the ratio of various geochemical elements measured by assay was made between the clays and 1) shale bedrock and 2) clays of known detrital origin from other nearby sites. This indicated the clays had a strong affinity with weathered bedrock. This and other textural features resulted in the interpretation that the clay units were relic debris preserved following ancient landslides in bedrock shale. Using laboratory testing data and calibration of results for a landslide origin, stability analyses were run, resulting in a steeper slope design being implemented. Excavation of the final cutback is now in progress with the model confirmed as appropriate.

Jan 1, 2015

By J. W. Gunnett

Abstract. The Surface Mining Control and Reclamation Act of 1977 (PL-95-87), Section 522, establishes requirements for state regulatory authorities to designate lands unsuitable for all or certain types of surface coal mining. Any party having an interest in an area that may be affected can petition for it to be designated unsuitable for mining. Section 522 could present major obstacles to the mining industry by typing up an area in an endless round of petitions. The program under development for Kentucky is examined and analyzed as an example for determining the hidden impacts of Section 522.

Jan 1, 1980

By Ann G. Kim

The Bureau of Mines investigated factors that influence the formation of methane and other hydrocarbon gases in coal, which is an integral part of the coalification process. Coalification begins with a biogenetic stage in which plant debris decomposes and peat is formed; methane and CO2 are the predominant gases produced during this stage. During the diagenetic stage of coalification hydrogen and the hydrocarbon gases methane, ethane, ethylene, propane, propylene, butene, iso- and normal butane, and pentane are formed by dissociation of the organic material. Methane may also be produced by a secondary reaction of hydrogen with unsaturates or by the reduction of CO2. The gas contained in coalbeds is a mixture of methane, C2 through C5 alkanes, CO2, 02, N2, H2, and H2; its heating value is equivalent to that of natural gas. The gas content of coal depends on many variables, but an empirical relationship between adsorptive capacity, rank, and depth has been observed.

Jan 1, 1978

By I M. Platten, C J. S Sangster, Y Xie

The Cononish gold-silver deposit is a steep, relatively narrow quartz-vein system, with a current total mineral resource of 154 000 oz Au and 589 000 oz Ag. The northeast-southwest trending system was emplaced into late Proterozoic metasediments, and postdates metamorphism and associated Caledonian Orogenic foliations. Assay and mineralogical data show that gold and silver is spatially associated with sulfides in quartz. The main sulfide is pyrite, but galena, chalcopyrite and sphalerite occur in small amounts. Gold occurs as electrum, with minor native gold, and silver occurs additionally as tellurides and native metal. The gold/electrum is fine-grained, generally less than 100 microns in size. The main ore shoots plunge 45¦ south-west, have a 40 m to 80 m intersection with the existing underground development and extend between 40 m and 260 m down plunge. Small-scale sulfide-bearing domains within the vein carry the highest gold grades. They collectively define the ore shoots, where one or two, and rarely three, of the domains are present at an individual site in the vein. Discontinuity of individual domains, variation in domain thickness and internal heterogeneity results in short scale variation in grade across the structure. Geological mapping along a 1.2 km exploration adit has provided critical æconditioningÆ data to support resource evaluation based on development and relatively wide spaced drilling. In addition, it has provided an indication of potential challenges that could be encountered during production.

Jan 1, 2009

By M. E. Tyrrell

Despits its high melting point (2,135° C.), resistance to attack by molten metals, and its hardness (8), spinel (MgO?Al203) synthesized by the fusion of alumina (Al 2 0.) and magnesia (MgO) is not used on a large scale as a commercial furnace lining, mainly because of the prohibitive cost. This investigation by the Federal Bureau of Mines was prompted by the possibility of producing synthetic spinel from inexpensive raw materials by methods outlined in U.S. Patent 2,029,773, "Process for Obtaining Products Containing Spinets," dated February 4, 1936. In this patent Ture B. Haglund described a process for recovering crystalline spinels from melts in the system Mg0?Al203-2CaO-SiO2, a system well suited to the use of starting materials such as dolomite CaMg(C03)2, olivine [2(Mg?Fe)0.Si02], and bauxite (Al203?2H20) which are abundant in the southeastern United States. Compositions, ranging from a low content in the eutectic mixture of 35 percent spinal and 65 percent dicalcium silicate (2 CaO?SiO2) to a high of 75 percent spinel and 25 percent dicalcium silicate, were fused in electric furnaces of the arc-resistance and internal-resistance types. So long as members of the system were in proper chemical balance, "dusting" slags could be produced over the entire range of spinel concentration.

Jan 1, 1961

By Christopher B. Vierrether

Reflected light microscopy, scanning electron microscopy, and electron microprobe analysis have been used to determine the mineralogy, phase percentages, grain sizes, textures, and partitioning of cobalt and nickel in two cobalt-nickel rich mattes. These mattes were prepared by submerged bath smelting from a flotation cobalt-nickel concentrate containing 4.8% cobalt and 5.1% nickel. The concentrate was derived from lead-zinc-copper ores of the Viburnum Trend, southeast Missouri. Eleven discrete phases have been distinguished in the matte samples, three of which contain significant cobalt and nickel. The phases are cobaltpentlandite ((Co,Ni,Fe)9S8), cobalt-bearing marmatite ((Co,Fe,Zn)S), shandite (Ni3Pb2S2), bornite (Cu5FeS4), galena (PbS), magnetite (Fe3O4), pyrrhotite ((Co,Ni,Cu,Fe)1_xS), chalcocite (Cu2S), CuPbS phase, metallic copper, and metallic silver. Cobaltpentlandite and cobalt-bearing marmatite- occur in coarse grains (50 µm) that would separate readily during grinding, but shandite contains small (5 - 10um), abundant inclusions of pyrrhotite and bornite.. Some mineralogical variations between the two matte samples were due to differing degrees of oxidation during smelting,

Jan 1, 1988

By D. E. Wolfson

As part of its overall program of coal carbonization, the Bureau of Mines is studying the coking properties of coals that may be used for metallurgical purposes. The objectives of this study were given in detail in a previous report.2/ The suitability of coal for metallurgical use depends primarily on (1) chemical composition, (2) preparation characteristics, and (3) carbonization behavior. The first two factors, as well as the available reserves, are considered in selecting coals for carbonization tests. According to the estimate of reserves by Dowd,3/ the recoverable coal in Raleigh County in beds 28 inches or more thick, in thousand tons, is: [ ]

Jan 1, 1957

By Mark Cross, Andrew P. Campbell, Koulis A. Pericleous

"Computational Fluid Dynamics (CFD) modelling is being used to simulate the freeze layers formed within direct smelting processes. There has been some concern whether water-cooled elements can withstand the p~ocess conditions and in particular abnormal cases where they may be splashed in molten metal.To validate the models being developed, two cases from literature have been modelled for solidification and stress analysis. The solidification case is presented in detail and is for hot molten metal flowing through a cylindrical pipe. The walls are at a temperature below the melting point for the metal. The resulting solid (or freeze) layer is within 3% of the value calculated by Sampson & Gibson9 •Preliminary modelling of the refractory-slag interactions is presented. Although three basic mechanisms: Penetration; Corrosion; and Erosion will eventually be modelled, only the penetration is considered here. The corrosion mechanism is to be modelled by tracking the time that the penetrated refractory is at the required temperature.Future work, after adding all the required physics, will focus on the modelling of a water-cooled element placed lower in the smelter. Process perturbations will be simulated to examine what these elements will withstand."

Jan 1, 2001

By Sacha Neven

Submerged lance technologies combine high intensity processing characterized by rapid mixing and reaction rates using a simple reactor design. The Isasmelt technology uses a central submerged lance to inject oxygen-enriched air and fuel into a bath thus creating large gas bubbles and intensive turbulence and splash. The lance is equipped with swirlers to increase gas velocity and heat transfer. This enables the formation of a frozen slag layer on the lance which protects it from the aggressive environment. Water models as well as high temperature reactors were used to validate the Davidson-Schiiler model on bubbling. Frequencies and pressure amplitudes were measured in a wide range of gas flow rates: from m3/sec using a water model to more than 30 m3/sec in an industrial process. Agreement with the model was satisfactory. The experiments however also clearly showed that cross-flow and bubble wake induce slightly higher frequencies. No influence of the use of swirlers on the bubbling frequency was observed in the water models.

Jan 1, 2002

By Tingkan Lu

To understand the reinforcing mechanisms of the fully grouted resin bolt and clarify its performance in weak roof strata, the field monitoring investigation using instrumented bolts has been conducted in a coal mine. The total time of monitoring was around ten months. In the first 8 month period, the rock bolt performance relates to the initial development of the gateroad and subsequent time dependent strata response. After 8 months, the rock bolt performance relates to the effect of the approaching longwall mining operation, up to the point where the measuring station was destroyed due to the mining operation.

Jan 1, 1998

By Masanori Abe, Yoshitaka Kitamoto, Kazuhiro Nishimura

"Ferrite plating is a chemical processing which utilizes Fe2+ - Fe3+ oxidation to synthesizing polycrystalline films of ferromagnetic spinels (MFe20 4, M = Fe, Co, Ni, Zn, Al, Cr, TI, etc:) directly from an aqueous solution at 24 - 100°C. This low temperature process allows us to fabricate new ferrite film devices on · substrates of such non-heat-resistant materials as plastics, GaAs integrated circuits, and biomaterials. Synthesized from an aqueous solution the ferrite plated ·films are highly biocompatible. Thus various magnetic device and biomedical applications have been proposed and realized using ferrite-plated films. Ferrite-encapsulated polymer microspheres are applied to antibody carries for enzyme immunoassay, and also to toners/carriers for photocopying. Perpendicular magnetic recording media utilizing plated CoNi ferrite films are proposed. The low-temperature synthesized films of NiZn and Co ferrites are potentially used as soft-magnetic and/or insulating layers, respectively at high/microwave frequencies.IntroductionFerrite plating is a processing which facilitates the formation of crystalline spinel ferrite films with various compositions, (Fe, M)30 4 (M = Fe, Co, Ni, Zn, Al, Cr, TI, etc.), directly from an aqueous solution at 60 - 100°C [1]. This opened the door to fabricating novel ferrite-film devices using substrates of such non-heat-resistant materials as plastics and GaAs integrated circuits [2-4]; conventional ferrite film preparation techniques such as sputtering, vacuum evaporation, MBE, LPE, etc., require high temperatures(> -600°C) for crystallization of ferrites, which deteriorates the non-heat-resistant substrates. Recently we extended ferrite plating to be preformed at room temperature [5, 6]. This enables us to use as substrates such organic materials as biomaterials (e.g. enzymes) having very low heat-resistance."

Jan 1, 2000

By Walter G. Dupree

When the original version of this study was published in 1972 it was evident that a problem was developing on the energy scene. The ability of the United States to find the energy supplies it needed within its own boundaries--at least in the forms desired--was declining. Production of crude oil in the United States had peaked in 1970 and was declining slowly; environmental restrictions had begun to hamper the production and consumption of high sulfur coal; natural gas reserves were beginning to dwindle; and the development of nuclear power was proceeding more slowly than originally planned. Shortfalls in energy supply were being met through the importation of increasingly larger quantities of petroleum, but supplies were adequate and the price of the imports was below that of domestic production. The energy problem was more prospective than current. In October of 1973 the prospective problem became the "Energy Crisis' when the Arab petroleum exporting countries reduced crude oil production, imposed an embargo on the shipment of crude oil to the United States, and then raised the price of crude oil in a series of large steps. This crisis was a clear demonstration of the dangers of the dependence of the United States on imported petroleum, and of the Nation's vulnerability to the actions of the oil exporting countries. After the embargo was lifted, attention shifted to the immediate hardships resulting from the higher prices for gasoline, fuel, and electricity,

Jan 1, 1975

By W. L. Josey

The Stibnite Project is an open pit/cyanide heap leach gold property located in the Yellow Pine mining district of central Idaho. The gold ore is in an oxidized zone of an epithermal deposit which is associated with a fault system related to Tertiary igneous activity of the region. The faults transect a roof pendant of metamorphosed sediments within crystalline rocks of the Idaho Batholith. Seasonal mining is at a rate of 3900 mt/d (4300 st/d) of ore with a 2:l waste to ore ratio. Gold and silver are recovered through a process of cyanidation, carbon adsorption and desorption, and electrowinning. Disposal of the leached ore requires chlorination of the residual cyanide.

Jan 1, 1984

By AIME AIME

N OW THAT the war is over it is possible to release data and correct some erroneous statements and impressions relative to the use of manganese-steel armor and helmets, which heretofore have been carefully guarded. The material of the helmets furnished to the English, American, and Belgian armies was invented by Sir Robert Hadfield, Bart., F.R.S., and was described in a paper read by him at the International Engineering Congress in August, 1893. The French helmet was 2 oz. lighter than the English but had a greatly inferior resistance. Tests showed that it was perforable at as low a velocity as 350 ft.- sec. impact of the standard shrapnel bullets. Helmets made of the Hadfield "Era" manganese steel kept out standard shrapnel bullets of the same quality at no less than from 750 to 950 ft.-sec. impact velocity. The respective energies were, in the case of the French helmet, only 0.021 ft.-tons, 46 ft.-lb., and in the British 0.095 ft.-tons, 213 ft.-lb. The German helmet was made of nickel-chromium steel and, although 12 oz. heavier and 12 per cent. thicker than the Hadfield, was not only perforate

Jan 1, 1920

By F. Agterberg

In his 1978 monograph ‘Lognormal-de Wijsian Geostatistics for Ore Evaluation’, Professor Danie Krige emphasized the scale-independence of gold and uranium determinations in the Witwatersrand goldfields. It was later established in nonlinear process theory that the original model of de Wijs used by Krige was the earliest example of a multifractal generated by a multiplicative cascade process. Its end product is an assemblage of chemical element concentration values for blocks that are both lognormally distributed and spatially correlated. Variants of de Wijsian geostatistics had already been used by Professor Georges Matheron to explain Krige’s original formula for the relationship between the block variances as well as permanence of frequency distributions for element concentration in blocks of different sizes. Further extensions of this basic approach are concerned with modelling the three-parameter lognormal distribution, the ‘sampling error’, as well as the ‘nugget effect’ and ‘range’ in variogram modelling. This paper is mainly a review of recent multifractal theory, which throws new light on the original findings by Professor Krige on self-similarity of gold and uranium patterns at different scales for blocks of ore by (a) generalizing the original model of de Wijs to account for random cuts; (b) using an accelerated dispersion model to explain the appearance of a third parameter in the lognormal distribution of Witwatersrand gold determinations; and (c) considering that Krige’s sampling error is caused by shape differences between single ore sections and reef areas.

Jan 1, 2015

By George J. Karcas, Raimo Kuusisto, Pertti Pekkala

Ongoing Outokumpu development in Solvent Extraction and Electrowinning Technology, involving all aspects of process chemistry, equipment and control, extends over a period of close to 30 years. The development in SX started with molybdenum and rhenium, continued with zinc, manganese, cobalt and nickel and is now focusing on copper. The OutoCompact VSF? SX concept, which has been recently introduced, is a honed version of earlier VSF? technology. The Outokumpu VSF? ("Vertical Smooth Flow") SX package includes the DOP ("Dispersion Overflow Pump") units, the Spirok Mixers, the OutoCompact Settlers including their DDG ("Dispersion Depletor Gate") fences and tank farm equipment such as the LOS ("Loaded Organic Scrubbing") tank as well as the CEP ("Copper Electrolyte Purifying") tank. Although the VSF? SX package can be implemented according to several optional lay-outs, the so-called Track version has lately been introduced to the advantage of new plants. The new OutoCompact SX technology decreases the footprint of future VSF? plants. The lay-out, including plant size flexibility, have further been improved by Outokumpu?s new OutoReverse settler technology. Two of several SX plants currently under construction rely on reverse settlers in order to maximize their performance. The Outokumpu EW technology includes process know-how as well as proprietary equipment. The copper EW package consists of permanent stainless steel cathodes based on wax-less technology and lead anodes utilising polymer concrete cells with the double contact bus bar system and ventilation hoods fitted for efficient mist control. The lifting of cell hoods, as well as cathode washing, is done by the cathode pulling crane. Proper electrolyte flows and matching current density further ensure high productivity of LME grade copper cathodes.

Jan 1, 2005

By N. Kyriazi

The U.S. Bureau of Mines subjected the CSE SR-lOO self-contained self-rescuer (SCSR) approved by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) to a series of laboratory treatments designed to simulate various environmental conditions in underground coal mines. The tests were designed to predict the ability of the self-rescuers to withstand those environmental stresses without causing a decrease in wearer protection. The apparatus were heated to 710 C for 48 h, cooled to -450 C for 16 h, vibrated for 9 h, and dropped 1 m on each axis. A critical concern was internal damage to an apparatus, without any obvious external signs, that would cause it to malfunction or seriously degrade its performance. Carbon dioxide (C02) levels in apparatus with combined treatments were higher than in apparatus with individual treatments and untreated apparatus. The higher levels remained within safe limits, however. None of the treatments caused venting of the small oxygen cylinder that provides starter oxygen. Some bottles were found to be empty because of manufacturing defects in the burst disks. This problem was corrected in later models. The heat treatments did make the case ends more difficult to remove and the breathing bag sticky and subsequently more difficult to unfold. An apparatus that was dropped and vibrated had a broken desiccant bag that released some of its contents which compromised the seal of the relief valve. The case was dented from the drops. As with the first-generation self-rescuers, if there is visible damage to the case of the apparatus, the apparatus should be considered to be internally damaged and must be removed from service.

Jan 1, 1990

By R. R. Byran, M. H. Kuryla

The Compania de Real del Monte y Pachuca started a 10-ton pilot plant in March, 1906. The distinctive features of the first cyanide installations at Pachuca were: grinding in cyanide solution, all-sliming and filtration of ore in which silver constituted the major value. Loreto started with a 300-ton " all-sliming" plant, using jaw crushers, grinding in stamps, Chilean mills and pebble mills in cyanide solution, concentrating with Wilfley tables and Johnson vanners, classification by cones and Dorr classifiers, intermittent thickening by decantation, mechanical agitation in flat tanks by stirrers and centrifugal pumps, filtration in Butters filters and precipitation by zinc shavings. The "San Francisco" mill No, 1 was contemporaneous, using a rather similar flow sheet. We shall trace the main developlnents in the three large mills of the district to their present practice. Developments in Large Mills of District Crushing and Grinding.—The trend of development in this part of the work has been the same as throughout the milling world; via., all increase in the degree of comminution of the ore in dry-crushing machines, the advance from pebble mill to rock mill and then to ball mill and the elimination of the stamp battery through the encroachment upon its field on the one side by finer dry crushing and on the other by more efficient wet grinding. The single-stage crushing in jaw type crushers, used at the start, has been replaced by two stages; at first, both stages by gyratory type and later the present practice, which is the same in all three mills, consisting of gyratory as primary followed by cone as secondary and delivering a product that may be rated at 56 to 1 inch. Primary wet grinding, at first performed by stamps and Chilean mills, is now by hall and/or rod mills; present practice differing widely in the three mills. Santa Gertrudis uses a 7 by 15 ft. rod mill, San Rafael

Jan 1, 1935

By M. Gaumont, F. Robichaud

"Agnico Eagle Mines Limited (AEM) is a Canadian-based gold producer with operations in Canada, Finland and Mexico. In 2010, AEM produced its first gold bar in Nunavut, Canada as it started its Meadowbank operation. It is also in 2010 that AEM acquired the Meliadine property, which is located 25 Km North of Rankin Inlet, Nunavut, Canada. The Meliadine gold project is an advanced exploration and development project, comprising of workers camp, underground and open mines, a processing plant and all the services facilities and infrastructures required to sustain operation in a remote arctic environment.Pending formal board approval, production start-up is planned for Q3 2019 and the process flowsheet is based on an ore processing rate of 1.1 million dry tonnes per year (3,000 dry tonnes per day from underground mining) for the first three years, and 1.98 million dry tonnes per year (5,000 dry tonnes per day from both underground and open pit mining) for the remaining years at 92% process plant availability.To the end of 2015, more than 45 metallurgical test programs have been conducted on the Meliadine deposits. Based on the results of these programs, an optimal gold circuit was designed, comprising of crushing, grinding, gravity separation and cyanide leaching with a carbon-in-leach circuit (CIL), followed by cyanide destruction and filtration of the tails for dry stacking. The assumed gold recovery for the reserves averages 96.0% at a 7.44-g/t gold average mill feed grade."

Jan 1, 2016