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By Michael V. Wolski, Ryan O. McCarter, Kenneth A. Johnson

"The Central Subway is Phase 2 of the San Francisco Municipal Transportation Agency’s (SFMTA) Third Street Light Rail project and will extend the existing Phase 1 initial operating segment from its current connection to the Embarcadero line at Fourth and King streets along Fourth Street to Market Street, under the Bay Area Rapid Transit (BART) and Muni Metro tunnels and then north beneath Stockton Street to Chinatown (Fig. 1).Total new track to be constructed as part of the Phase 2 work consists of approximately 734 m (2,410 ft) of surface track and 2,636 m (8,650 ft) of tunnels. The tunnels were constructed as twin, singletrack bores by two tunnel boring machines (TBMs) (Johnson, 2014) moving north from the southern end of the launch box under the I 80 freeway between Bryant and Harrison streets. North of Chinatown Station the TBMs continued another approximately 683 m (2,240 ft) to a retrieval shaft near Columbus Ave. at Washington Square. The project also includes five cross passages to connect the two tunnels, and three underground stations (the Yerba Buena/ Moscone Station, Union Square/Market Street Station and Chinatown Station.)Excavation of the twin tunnels was performed with two TBMs, with both TBMs driving northward from the launch box. TBM excavation was performed such that the location of the machines was staggered to separate the active excavation faces by a minimum of 91 m (300 ft) between headings. This minimum separation was maintained until the first TBM arrived at the retrieval shaft plug, at which time the separation requirement was relaxed.Excavation began with the “southbound” (SB) tunnel which will ultimately accommodate the southbound TBM light rail trains followed by the second TBM in the “northbound” (NB) tunnel. With the completion of the drives in June 2014, cross passage excavation then began and was completed in April 2015. Overall, construction of the Central Subway tunnels was a success considering the nature and complexity of the project. Additional details of the completion of the Central Subway tunnels are presented in another paper from the RETC 2015 conference (Leong et al., 2015)."

Jan 1, 2015

"Block caving is the preferred underground mining method to profitably extract massive, low-grade orebodies; however, lack of cave access inhibits understanding the rockmass response to mining, which is needed for safer, more productive operations. Combining large datasets from multiple sources with virtual reality scientific visualization (VRSV) is an alternative method for understanding complex cave behaviour, by providing virtual access to the cave. A customized VRSV module was developed at UNSW Australia to investigate rockmass response to undercut developments at a case-study block caving operation. Time/sequence effects are investigated in rockmass response to blasting, which is an important factor in hard-rock mines.RÉSUMÉ La méthode d’extraction souterraine par blocs foudroyés est la méthode préférentielle pour extraire rentablement des gisements massifs à faible teneur. Toutefois, le manque d’accès à la chambre restreint la compréhension de la réponse de la masse rocheuse à l’exploitation, ce qui est nécessaire pour obtenir des opérations plus sécuritaires et plus productives. La combinaison de grands ensembles de données de multiples sources avec la visualisation scientifique par réalité virtuelle (VRSV) constitue un autre moyen de comprendre le comportement complexe de la chambre en fournissant un accès virtuel à la chambre. Un module de VRSV sur mesure a été développé à l’Université de Nouvelles-Galles du Sud (UNSW) en Australie afin d’étudier, dans une étude de cas d’une exploitation par blocs foudroyés, la réponse de la masse rocheuse aux développements de galeries de sous-cavage. Les effets de temps/séquence sont étudiés dans la réponse de la masse rocheuse au sautage, ce qui est un facteur important dans les mines de roches dures."

Jan 1, 2016

By Dr. Ralph W. Edie

The limestone reef reservoir at Swan Hills consists essentially of a "buildup" of successively smaller atoll-like layers. Precipitation of calcium carbonate within the lagoonal area of each layer essentially kept pace with growth of the outer organic lattice. Within the reef mass, six de-positional environments characterized by specific suites of fossils (or fossil fragments) and associated limestone textures are recognized as follows: ( 1) Aerated moderately agitated water of normal marine salinity (widespread shelf or submerged reef-built platform). Thamnopora-type corals, Amphipora, "pancake" stroma-toporoids, crinoids, articulate bra-chiopods, rare rugose cup corals, and ostracods occurs in light gray-buff skeletal microgranular limestone of low permeability. (2) Semi-stagnant quiet water of normal marine salinity (leeward side of reef). Crinoids, articulate brachio-pods, rare thamnopora-type corals, Amphipora, pancake and bulbous stromatoporoids, rugose cup corals, ostracods and gastropods occur in impermeable dark brown argillaceous skeletal calcilutite with thin black bituminous shale beds and rare dark chert nodules.

Jan 1, 1961

By M. Westerstrand

It is known that the water chemistry of the process water during ore refinement can affect product quality, such as iron pellet strength. The main objective of this study was to quantify the amounts of major elements, such as Ca, Mg, Na, S and Cl carried by process water and by magnetite grain surfaces to the end product, iron ore pellets made from magnetite ore from the Kiirunavaara Mine in northern Sweden. In addition, the amount of colloids (0.22µm ? 1kD) in the process water was examined by ultrafiltration. The amounts of various elements sorbed to the magnetite surfaces were estimated by leaching with Milli-Q water, MgCl2, NH4-acetate and Na-acetate. Total dissolved solids were between 1,446 and 1,775 mg/l, dominated by Ca, S, Na and Cl (89%). The colloidal fraction was less than 3% for major ions. For Ca and Mg, sorption to magnetite surfaces was a much more important transport mechanism for the pelletizing process than evaporated process water, but for Na, Cl and S process water was an important carrier.

Jan 1, 2010

By Kafui Nyavor

Acid mine drainage (AMD) is presently the biggest single environmental problem facing the mining industry. New and expanding metal mines in most parts of the world have to demonstrate their ability to contain this problem to obtain operating permits. Conventional methods of controlling acid mine drainage have primarily been limited to collecting the drainage and neutralizing with alkaline materials which do not provide a permanent solution to the AMD problem. Since acid mine drainage results from the oxidation of sulfides in the presence of oxygen, water and iron-oxidizing bacteria, controlling any of these three factors contributing to pyrite oxidation provides a potential at-source remedy for reducing or preventing acid mine drainage formation. Physical properties such as hydrophobicity also play an important role in the attachment of bacteria, adsorption of oxygen, water, and other ions that subsequently lead to the oxidation of pyrite. In this communication, the suppression of pyrite oxidation by treatment with fatty acid amines (FAA) was investigated. The FAA treated pyrite samples were tested at various conditions of temperature and pressure. At an elevated oxygen pressure of 500 psi and a temperature of 600 C, less than 0.2% oxidation was obtained for the FAA treated pyrite samples, while over 1.2% oxidation was obtained for the untreated samples in 10 hours of oxidation time. Accelerated column oxidation tests at ambient condition showed that FAA mated samples reduced pyrite oxidation by at least 75% in 81 days.

Jan 1, 1994

By C L. Briend, O&apos

This paper presents the main features of coal mining in Japan, as determined by the author while attending the International Coal Conference in October of 1963. The general economy of the country is considered, and the requirements for coking coal are outlined. Statistics and comments on production and consumption are then given, with accompanying cost figures, and the characteristics of Japanese coal mining are compared with those of Canada. Mining methods and underground transportation are covered, with emphasis on undersea mining. Finally, a description is given of a visit to the Miike colliery, the largest in Japan. I T was my privilege to attend the International Coal Conference held in Tokyo in October, 1963, to meet many prominent members of the Japan Coal Association and to visit one of the major coal fields. This is probably the reason why I was asked to present this review of the coal situation in Japan. In doing so, it must be pointed out that I am not an expert in coal mining, that my

Jan 1, 1965

By James A. Wasson

The Mitchell and Berea sands were cored and logged in Fred Link well K-l, Lower Newport field, Washington County, Ohio. Core and reservoir fluid analyses and available field data were studied to determine if these sands could be successfully waterflooded. The results of the study indicate that there is insufficient oil in place to form an oilbank in either the western Mitchell pool or the Berea sand, and that no commercial recovery of oil by waterflooding can be obtained in these reservoirs.

Jan 1, 1967

By R. L. Grayson

Evidence has accumulated indicating that cultural change toward safer workplace behaviors is beginning to occur systematically in the coal industry. Through a range of programmatic mining company successes, enforcement and litigative actions, economic responses to competition, and integrated efforts by federal and state agencies, a broader participation of safety and training professionals is being achieved to address prioritized workplace problems at mines. Small steps in workplace-related improvements have been realized already, but the trends in industry safety statistics, coupled with focused programmatic initiatives, indicate that more definitive and systematic steps are occurring to improve safe behavior in the workplace routinely.

Jan 1, 1996

By Timothy Batchler

"Pumpable roof supports are currently being used to provide a safe working environment for longwall mining. Because different pumpable supports are visually similar and installed fundamentally in the same manner as other supports, there is a tendency to believe they all perform the same way. However, there are several design parameters that can affect their performance, including the cementitious material properties and the bag construction practices that influence the degree of confinement provided. A full understanding of the impact of these design parameters is necessary to optimize the support application and to provide a foundation for making further improvements in the support performance.This paper evaluates the impact of various support design parameters by examining full-scale performance tests conducted using the National Institute for Occupational Safety and Health (NIOSH) Mine Roof Simulator (MRS) as part of manufactures' developmental and quality control testing. These tests were analyzed to identify correlations between the support design parameters and the resulting performance. Based on more than 160 tests over 7 years, quantifiable patterns were examined to assess the correlation between the support dimensions, cementitious material type, wire pitch, and single-wall vs dual-walled bag designs to the support capacity, stiffuess, load shedding events, and yield characteristics.INTRODUCTIONDeveloped in the 1990s, the first major use of pumpable supports systems in U.S. longwall operations was in the support of bleeder entries (Barczak, Tadolini, 2008). Since then, they have been utilized as yieldable concrete supports to provide a safe working environment for longwall mining gateroads, bleeders, and emergency escapeways while also maintaining adequate ventilation pathways. The basic structure of pumpable roof supports has remained unchanged over the years. Formed in place with a twopart fast-setting grout, the support material can be pumped into a containment bag from several thousand feet away often through surface boreholes. The containment bag then acts as a form to fill the support and provides confinement to the grout during loading and after failure. Pumpable roof supports provide full contact with the mine roof and floor, which eliminates the need for secondary material to establish proper roof contact (see Figure 1). They provide a high peak load capacity and a sustained, confinement controlled yield behavior while maintaining stable ground conditions, which is essential to underground mining operations."

Jan 1, 2016

By Richard W. Brummett, Robert L. Dubms

Located some 180 miles east of Los Angeles in Riverside County, California, the Eagle Mountain mine supplies iron ore concentrates for the Kaiser Steel Corporation steel plant in Fontana, California, and for export to Japan. Although the deposits were first discovered in the early 1890's, no production was realized from the area until 1948 when Kaiser Steel Corporation commenced operations. A part of the large Basin and Range province, the Eagle Mountain area's geologic column comprises a thick series of metasediments resting on Precambrian gneisses and schists that have been intruded by sill-like masses of porphyritic quartz monzonite. The metasediments are composed of three quartzite units that are separated by a schistose meta-arkose and by two ore zones. They have been folded into a large east-west trending anticlinal structure that extends completely across the Eagle Mountains. The iron ore deposits occur in two well-defined horizons in the metasedimentary series, and they are found only along the north limb of the major anticline. Host rocks for the ore zones were a series of limestones and dolomites with associated quartzites. Magnetite plus pyrite comprised the primary mineralization that formed many replacement lenses and stringers of ore within the ore zones. The primary ore has been oxidized to hematite and goethite in a broad zone at higher elevations in the deposits. Hydrothermal alteration formed actinolite- tremolite granofels, local phlogopite, and minor tourmaline in the ore zones. This alteration and the ore deposition seem related to the same magmatic event that formed the porphyritic quartz monzonite intrusion

Jan 1, 1968

By Ben E. Lindsly

The study of "bottom-hole samples follows in natural sequence the study of samples obtained under high pressures at the well heads of flowing wells. The principal object of this phase of gas-solubility research, started actively in January, 1930, was to gain a more accurate knowledge of the physical and chemical characteristics of the oil-gas mixtures that exist in natural reservoirs.. In possession of actual data regarding the condition of the oil; the quantity of gas liberated from solution upon dimunition of pressure; and the relative volumetric proportions of gas to oil at various pressures throughout the flow string in a well, it should be possible to predict, with a fair degree of accuracy, That physical changes these mixtures would undergo throughout the life of a pool. Such information not only is important in designing flow strings in flowing Tells but is important also in solving problems relating to pumping efficiency and the power required for pumping. Although certain fundamental data were obtained in the study of samples taken at the well head, "bottom-hole" samples are more representative of subsurface mixtures of oil and gas because they are obtained at reservoir temperatures, and before the oil has had the opportunity of intermingling with extraneous gas; that is, gas which either was not in solution originally, or which was liberated from solution at higher pressure, and later became mixed with the original undissolved gas.

Jan 1, 1933

By Walter Kawa

Coals of various rank were reacted by the Bureau of Nines in plasma jets generated from argon and argon-hydrogen mixtures containing up to 33 volume-percent hydrogen. Average plasma temperatures ranged from about 3,400° to 12,000° C. Products were a solid residue and a gas containing hydrogen, methane, acetylene, diacetylene, and oxides of carbon. The highest yield of acetylene obtained with argon plasmas was 15 percent by weight of moisture- and ash-free coal. The data indicated that acetylene yields of 40 percent or higher can be obtained from the reaction of coal in argon-hydrogen plasmas, although results from these experiments could not be correlated with operating variables because of low recoveries plasma contained sufficient energy to heat the coal to temperatures as high 9,000 or 10,000° C, but complete devolatilization did not occur in any experiment.

Jan 1, 1966

By M. Louarrat, G. Enaime, A. Yaacoubi, A. Baçaoui, J. Blin

"The purpose of this study is to prepare a new activated carbon from olive stones for use in gold recovery by carbon-in-leach (CIL) and carbon-inpulp (CIP). The preparation method chosen was physical activation using steam. The effect of four process parameters: the residence time for carbonization, the activation temperature, the residence time for activation, and steam flow, were studied by the mean of response surface method (RSM) in order to optimize the yield, iodine index, and attrition characteristics. These two last responses were used as primary indicators of gold recovery capacity and mechanical strength. The results obtained show that optimal activated carbon can be prepared under the following conditions: a carbonization time of 157 minutes, activation at 921°C for 53 minutes, and a water vapour flow of 0.18 mL/min. This optimum carbon has an iodine value greater than 1100 mg/g and an attrition index in the order of 0.74%. These values reflect the quality of the precursor (olive stones) as a raw material for the development of an effective new activated carbon for the gold mining industry. IntroductionActivated carbon is an effective adsorbent widely used in industry due to its high surface area, well-developed reproducible microporous structure, and high degree of surface reactivity and adsorption capacity. World consumption of activated carbon is steadily increasing. It is primarily used in industrial wastewater and gas treatment and also for silver and gold recovery from cyanide solutions (Syna and Valix, 2003; Soleimani and Kaghazchi, 2008; Buah and Williams, 2010; Eddy et al., 2011). However, activated carbon is expensive and it needs to be regenerated after each adsorption cycle. In order to decrease the cost of manufacturing activated carbon, low-cost forest and agricultural wastes are considered promising new materials. In recent years considerable research has been reported on activated carbon from agricultural wastes, such as olive stones (Yavu et al., 2010), acorn shells (Sahin and Saka, 2013), peanut shells (Wu, Guo, and Fu, 2013), grape seeds (Jimenez-Cordero, 2014), coconut shells (Yalcin and Arol, 2002; Gratuito, 2008), palm shells (Sumathi, 2009), cherry stones (Jaramilloa, Gomez-Serrano, and A´lvareza, 2009), macadamia nut shells (Eddy, 2011), apricot stones (Soleimani and Kaghazchi, 2008), and bagass (Syna and Valix, 2003)."

Mar 1, 2019

By A. G. Fonseca

The effects of coal cleaning, coal combustion and flue gas particulate removal systems on the partitioning of 12 trace elements were investigated. This study was prepared to help document the fate of trace elements in modern coal preparation plants and coal-fired utility boilers. The coal cleaning data were obtained from several coal preparation plant operations. The CONSOL 1. 5 MM Btu/hr pilot combustion and electrostatic precipitator (particulate removal system) test facility was used to develop the combustion systems data. A comparison with the very limited amount of published data from utility boilers is presented.

Jan 1, 1993

By Abbas H. Mirza

Arsenic and selenium are found in low quantities together with other metals in several nonferrous metallurgical process streams such as scrubber blowdown solution, acid plant wastewater, gas cleaning plant water, etc. Normally, the other metals in these streams are present as cations and can be precipitated by conventional lime treatment and sulfide polishing. However, arsenic and selenium are invariably present as anions, AsO33-and AsO43 in the case of arsenic and SeO32 and SeO42 for selenium. Conventional lime treatment removes most of the arsenic, but it does not remove selenium. The present paper reviews the processes and technologies developed to date on the removal of arsenic and selenium from metallurgical process streams.

Jan 1, 1996

By P F. Hodkiewicz, J de Lacey, M Stewart, R Lane

"Implicit modelling is an approach to spatial modelling in which the distribution of a target variable is described by a unique mathematical function that is derived directly from the underlying data and high-level parametric controls specified by the user. This modelling approach may be applied to discrete variables such as lithology (after converting the discrete codes to numeric values) or to continuous variables such as geochemical grades. This paper discusses the estimation of continuous (grade) variables using implicit modelling.One of the underlying engines of implicit modelling for producing this mathematical function description is the radial basis function (RBF). In essence, the RBF is a weighted sum of functions positioned on each data point. A system of linear equations is solved to derive weights and the coefficients of any underlying drift model coefficients. Once derived, the RBF may be solved for any unsampled point or averaged over any volume to provide an estimate of grade. It is possible, for example, to query the RBF on a regular grid to derive an estimate of block grades. Given the ease of creation of an RBF, and its ability to predict grade, the question arises as to how the grades derived from the solution of an RBF compare with grade estimates derived from conventional geostatistical interpolation methods (eg ordinary kriging (OK)).The purpose of this paper is to describe in lay terms: the basic structure of an RBF the role of parametric choice in the solution of RBFs and how this influences the character of the solution the fundamental similarities and differences between RBFs and conventional geostatistical estimators.Using a high-resolution conditional simulation, we show that in many situations RBF and OK estimates are very similar.CITATION:Stewart, M, de Lacey, J, Hodkiewicz, P F and Lane, R, 2014. Grade estimation from radial basis functions – how does it compare with conventional geostatistical estimation?, in Proceedings Ninth International Mining Geology Conference 2014 , pp 129–140 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

By Edwin G. Sharp, Frank S. Gaunce, George M. Freeman, Denis J. Kemp, Eric Dulson, Paul Salmon, Ernest R. Hamilton, Carl E. Parden

"THE ECSTALL ZINC PLANT was built for the treatment of the Kidd Creek zinc sulphide concentrates. Construction proceeded throughout 1970-71, with operations beginning in April 1972. The two concentrate types treated differ principally in minor impurity and precious metal contents. Processing flexibility was required to allow efficient recovery of the by-products, especially cadmium, copper and silver. The conversion of the zinc sulphide concentrates to end products follows a sequence of operations that are common to most electrolytic zinc plants and typical of the ""Tainton- Jephson"" flowsheet.1. Roasting in air at an elevated temperature to convert the metal sulphides to soluble metal oxides (calcine) and sulphur dioxide. The sulphur dioxide is converted to sulphuric acid in a contad plant and shipped by train to market.2. Leaching of the calcine in spent electrolyte to effect extraction and recovery of zinc as zinc sulphate solution, leaving an insoluble residue.3. Purification of the clarified zinc sulphate solution by cementation with metallic zinc dust to remove impurities detrimental to the electro-deposition of zinc or detrimental to product purity. The solids from cementation are the starting materials for secondary metal recovery.4. Electrolysis of the purified zinc sulphate solution to reduce the zinc to the metallic state while coincidentally regenerating the sulphuric acid for recycle to the leaching step."

Jan 1, 1974

By James H. C. Martens

Among the many interesting problems of the pre-Cambrian of the Canadian Shield is that of the origin of certain types of gneisses which are intimately associated with the granites on the one hand and with the metamorphic rocks of known sedimentary origin on the other. The observations recorded in this paper on the structure and composition of these ancient rocks found in a small part of northern Quebec may help to lead to a clearer understanding of the way in which they were formed and also constitute a contribution to the regional geology and petrography of a district for which little detailed information is available. The area considered is located near the Ashuapmuchuan, or Chamuchuan, river about 180 miles north-northwest of the city of Quebec, and therefore well within the Canadian Shield. Although most attention was devoted to the rocks along this river from the 57th to the 70th mile above its entrance into Lake St. John, a few observations on other localities to the north and northwest of that lake will be included. The field work was done in the summer of 1924 in cooperation with L. W. MacNaughton, E. S. Roberts, and B. M. Shaub, all of Cornell University. The party ascended the Ashuapmuchuan river by canoe and spent about a month near the mouth of Stacker, or Brochet, river, the outlet of the lake of the same name, returning by way of Mikoasas river. The writer wishes to express his obligation to his associates for their co-operation in the field and for their permission to publish the results. He is especially indebted to B. M. Shaub for the photographs of rock outcrops. Professor A. C. Gill g:ive many suggestions which were helpful in the laboratory study of specimens and in the preparation of this paper.

Jan 1, 1927

By M Davies, G Theletsane, A H. Gray

Recovery of gold from gold ores has been driven by the available technology and its configuration in the process plant flow sheet.Conventional practice in test work programs has the ore being ground fine (to 106 or 75 microns) to ensure liberation ahead of leaching or flotation. This paper identifies that, in many cases, gold and gold sulfide carriers will liberate and be recovered to a concentrate at much coarser sizes.There is an exponential increase in energy consumption relative to particle size reduction. This impact becomes extreme when comparing crushing a product to 1 mm against grinding to 75?microns.The resultant reduction in energy consumption when liberating and separating at 1 mm or coarser compared to grinding to 75 microns can be in the order of 15 kWh/t or 60 per cent of energy in the comminution circuit.Recovery of free gold and gold sulfide carriers by preconcentration (using continuous gravity devices such as the InLine Pressure Jig), combined with flotation of the fine gold and gold carriers, can result in significant power savings.There are multiple locations within the flow sheet that can be targeted using this process, including recovery in the cyclone underflow of existing plants, preconcentration ahead of the plant or complete greenfield, low-energy process plants designed from first principles based on data from a Gekko developed test work regime.We will describe the process of defining mineralogy in the laboratory and the decision-making process through to actual applications in the field.Several examples will be provided, including a South African Witwatersrand gold ore, several Australian gold ores and others, indicating the benefits of this process and where it has been brought to commercial reality.CITATION:Gray, A H, Davies, M and Theletsane, G, 2014. Coarse liberation and recovery of free gold and gold sulfide carriers for energy reduction in process plants, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 117–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By L. F. Willmott

The production operation of a Kerpely gas producer at Louisiana, Mo., is described. This unit, originally designed for airblown operation was modified to permit using oxygen in the blast in place of air. The first runs J for test purposes, were made in June 1950. After this, seven production runs were made and these are the subject of this report. Total gasification time was 245 days. In each run, Nut or Pea coke or mixtures of both at a rate varying from 1,700 to 2,300 pounds per hour was converted with oxygen and saturated steam to produce synthesis gas - primarily carbon monoxide and hydrogen -approximating a predetermined rate of 80,000 to 95,000 cu. ft. per hour and a predetermined hydrogen-carbon monoxide ratio, The requirements per 1,000 std. cu. ft. of (CO + H2) were 21.6 to 30 pounds of coke, 213 to 267 std. cu. ft. of oxygen, and 3L4 to 47.B pounds of steam.

Jan 1, 1955