Search Documents

By J. J. Crowhurst

The modem open pit-heap leach operation by Pegasus Gold Ltd. at Zortman and Landusky in Phillips County, Montana, is a new chapter in the mining of gold in these districts. The discovery of bulk tonnage ore bodies and their development and ultimate production was based on a long history of mining and exploration in that part of Montana. Gold was originally discovered in the Little Rocky Mountains as placer deposits by Pike Landusky and Lou Myers. This discovery in the 1880s was not significant, but Pike Landusky continued prospecting for lode deposits, and he eventually located the Gold Bug and Little Ben, two of the larger Au-Ag producers in the district. Eventually two camps, Landusky and Zortman, grew in the LittleRocky Mountains. By the time Landusky was killed in 1894 by Kid Curry, the district was still a discontinuous small producer. Steady production commenced in 1907 with the organization of the August Gold Mining Co. Eventually high grade ores on specific veins were exhausted by selective underground mining and the district was idle by May 1942. After World War II in the early 1950s. E.A. Scholz tried to continue selective underground mining, but he realized the stockworks surrounding the larger veins constituted bulk tonnage targets. Ultimately in the 1976- 1979 period he organized two exploration efforts, one each for the Landusky and Zortman areas, and brought these into production as the Argo and Pegasus gold mines. By the time of his death, Apr. 8, 1980, both operations were producing gold. Later the two companies were merged as Pegasus Gold Ltd. Upon the death of Scholz, V.F. Hollister continued as the geological consultant, Ed Roper was engaged as general manager, and J. J. Crowhurst was given the responsibility of executive vice president. The discovery of open pittable ores and the application of heap leach technology was important in the development of mining. Both contributed to the low cost operation that continues to this day. The attached article by L.M. Rogers, then chief geologist, and M.S. Enders, his assistant, describes the geology of the deposit. It was presented at the Northwest Mining Association meeting in 1982.

Jan 1, 1990

By Thibaut Pannetier, Damien Rogat, Catherine Larive, André Regnard, David Chamoley

"INTRODUCTION For several decades, the use of fibre-reinforced sprayed concrete (FRSC) has been becoming increasingly widespread, either as a replacement for or in addition to traditional reinforcements. Macro-synthetic fibres appeared on the market at the same time as metal fibres (in the 1980s), but their use has developed more recently in France, starting in the early 2000s. While their properties are attractive for underground operations, their long-term performance remains the subject of some controversy, particularly with regard to the phenomenon of creep [1-5]. Unfortunately, the many differences of protocol among the studies carried out (materials, metering, spraying equipment and test methods, etc.) mean that, in general, the results cannot be compared. Although several methods have been developed to assess the bending creep behaviour of fibre-reinforced concrete, the majority of them test notched beams resting on isostatic supports. There are currently no standardised test methods adapted to FRSC on hyperstatic supports (as is the case for FRSC used for underground support). The Asquapro association has thus developed a new test specially designed for this type of concrete. Slabs of thickness 10cm, measuring 60 x 60 cm in plan have been sprayed and tested under bending stress according to a test procedure inspired by the standardised test of energy absorption capacity (NF EN 14488-5). An experimental campaign was launched in October 2014 to study the behaviour of seven types of sprayed concrete, manufactured using the same concrete matrix: six of them were reinforced with different metal or macrosynthetic fibres and the seventh with a welded wire mesh. Fourteen slabs were sprayed for each type of concrete and also for the non-reinforced concrete with the same matrix. The types of mechanical performances measured were the compressive strength and energy absorption capacity (at seven and twenty-eight days), in addition to the creep behaviour of these seven types of concrete, placed under stress on the seventh day. This article follows on from that published in the WTC 2015 congress proceedings [6]: the programme and the test methods are briefly described here and the results available at the time of writing are presented and discussed."

Jan 1, 2016

By Edmund W. Murphy

At the first workshop on Surface Subsidence Due to Underground Mining (1 981 ) , Yarbrough delivered a paper (1 ) describing the mine subsidence insurance program in Illinois operated as the Illinois Mine Subsidence Insurance Fund (IMSIF) . In this paper we will present claims data and describe changes that have occurred in the Illinois Insurance Code during the first six years the IMSIF has been in existence. The change in the original Illinois Public Act 80-1 41 3 that most affected the public was an amendment increasing the maximum amount of mine subsidence insurance avail- able on a structure from $50,000 to $100,000. Seventy-two counties in Illinois have been undermined for minerals, primarily bituminous coal. In Franklin County (.in the southern part of the state) 36 percent of the land area has been undermined for coal extraction. In St. Clair and Madison Counties , two counties that include the St. Louis Metropolitan area along the western border of the state, 10 percent and 7 percent of the land surface have been undermined. Most of the undermined area in the two counties is beneath urbanized land. In 34 counties, approximately 1 percent or more of the land surface has been undermined (2). The first shaft mine in Illinois was sunk in the city of Belleville (east of St. Louis) in 1842, and the mines of early vintage have initiated the majority of the mine subsidence claims. Data compiled from the first six years reveals that most Illinois mine subsidence events that affect structures occur over abandoned mines where early methods of high- extraction mining practices were used. Maps of these mines operated in the 1800s reveal irregular development of room and pillar areas and poorly defined production areas (panels). Rooms in the mines varied from 15 to 40 feet in width and the pillars varied in width from 5 to 40 feet. The pillars were often long and narrow. Recovery rates in mines that operated prior to 1900 generally averaged 50 per- cent, and extraction rates as high as 80 percent have been documented (2). Some pillar robbing occurred.

Jan 1, 1986

By J. Lorengo, C. H. Bucknam

"Standardization of the Inductively Coupled Plasma Mass Spectrometry (ICPMS) method for gold in cyanide solutions was undertaken to provide a more sensitive method to quantify the gold content than the atomic absorption method standardized in 1994 (E1600). The gold concentration range covered is from 0.001 mg/L Au - 0.3 mg/L Au (0.00005 toz/t Au – 0.009 toz/t Au). Interlaboratory testing was carried out with the assistance of the American Society of Testing and Materials (ASTM) International on two committees to determine the within laboratory and between laboratory reproducibility. Three barren solutions from metallurgical operations were measured in triplicate to satisfy statistical requirements for Committee E1 on Analytical Chemistry of Metals, Ores and Related Materials. A synthetically prepared matrix representing the metallurgical processing solutions was used to prepare Youden pairs to satisfy the requirements of Committee D19 on Water. Results of the standardization program are presented. INTRODUCTION Analysis of process solutions for gold concentration requires accurate and sensitive analytical methods in order to manage process control and metallurgical accounting. Flame atomic absorption spectrophotometry (FAAS) has been the work horse of the assay lab for this duty for decades. In 1994 the FAAS standard method was approved by the American Society for Testing and Materials (ASTM) (1). Six process solutions were collected and preserved by measuring the pH and adjusting to greater than pH 10, if necessary. Duplicate solutions were provided to eight laboratories in random order for analysis by FAAS covering the gold concentration range of 0.19 µg/mL (0.006 toz/t.) to 10.7 µg/mL (0.312 toz/t). A high precision method was used, which involved bracketing the sample with the higher and lower standards nearest to its concentration repeating readings three times and averaging the results. The optimum precision for the FAAS gold method was found to be at the 1.00 µg/mL (0.029 toz/t) and lower scope limit 0.3 µg/mL (0.009 toz/t) gold concentration. Since tailings solutions typically have concentrations below the lower scope limit, use of ICPMS was developed at Newmont USA Limited (Newmont) to assay the lower range solutions."

Jan 1, 2016

"Iron ore is the source of primary iron for the world’s iron and steel industries. Its production can be reported as crude ore, usable ore or iron content of ore. Historically, the U.S. Geological Survey (USGS) used reported crude ore production from China in tabulations of world iron ore production while other countries have typically reported their production in terms of usable iron ore. When China’s crude ore production was tabulated with usable ore production from other countries, world iron ore production totals have been overestimated by 10 percent to a high of content and may include products such as concentrates, direct-shipping ore, pellets, and sinter.• Iron content, also referred to as metal content or grade, denotes the amount of elemental iron in the crude or usable ore.BackgroundIron ores consumed in the steel industry typically require an iron content greater than 58 percent before being considered commercially usable. Iron ores that are not commercially usable must undergo beneficiation to raise the iron content. Approximately 98 percent of the world’s usable iron ore production is consumed in blast furnaces to make pig iron, which is further processed to make steel.High-grade iron ore mines can supply usable iron ore, known as direct-shipping ore, to blast furnaces, with minimal physical processing and no beneficiation. With direct-shipping ore, the reported production for crude ore and usable ore are the same. Ore from low-grade deposits must undergo beneficiation to increase the iron content before it can be used by the steel industry. In this instance, the mined material is called crude ore and post-beneficiation concentrates are called usable ore; the amount produced will be less than the crude ore amount. With the notable exceptions of countries such as Australia and Brazil, most of the world’s iron ore deposits are low-grade and require beneficiation."

Feb 1, 2017

By G. Southam

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An in vitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold (which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between 80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14% within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%) throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By L. F. McHugh

Molybdenum conversion operations discussed in this paper encompass all major operations commercially used to upgrade molybdenite concentrates to various refined products. More emphasis is placed on discussion of key pyrometallurgical unit operations. These operations conducted at Metec include roasting, sublimation, and hydrogen reduction

Jan 1, 1986

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

This paper describes the vibration transmissibility characteristics of mining vehicle seats under dynamic conditions in an opencast iron ore mine. Magnitude and frequency contents of vibration signals on the seat floor as well as on top of the seats were measured to record the change during transmission. The conventional rigid seats were found to resonate at about 4 Hz, which coincides with the resonance of the human spine. The pneumatic suspension seats also proved to be more efficient in attenuating the overall vibration energy transmitted from the vehicle chassis to the human body.

By Boris CARO VARGAS, Bernard Theron

"In early 2014, Nicholson Construction Company was awarded, together with its tunneling sister company Bessac, the Norris Cut Miami Tunnel Project. The 2.5-meters diameter segmental lined tunnel, 1600-meters long, is aimed to replace the existing 54” force main connecting the Waste Water Treatment Plant (WTP) on Virginia Key to Fisher Island. To overcome project challenges such as the highly permeable limestone of the Fort Thomson Karstic Formation (one of the most permeable formation in the World), the project team has developed State of the Art solutions: The TBM was launched with pipe-jacking technique for the first 70-meters and then converted to segment erection mode. It allows substantial schedule savings and drastically reduces the size of the circular launching shaft. The TBM, jointly designed and manufactured by Bessac and Herrenknecht, can convert from slurry to EPB mode within a few minutes. The cutters can be replaced by wet divers thanks to an innovative application in the TBM industry. PRESENTATION OF THE PROJECT The aim of this project is to replace the existing 54-inch force main pipeline which transmitted all sewage collected from Miami Beach, Surfside, Bal Harbour, Bay Harbor, North Bay Village and Fisher Island to the Central District Wastewater Treatment Plant (CDWWTP) to Fisher Island. The existing pipeline consisted of pre-stressed concrete cylinder pipe which is in poor condition in a number of locations and could be subject to sudden failure. An adjacent portion of this existing force main under the Government Cut (North Fisher Island) has already been replaced as part of a previous design-build contract and involved the installation of a 60-inch diameter fiberglass-reinforced mortar pipe installed inside a micro-tunneled casing."

Jan 1, 2016

Mining was the first economic activity carried out in Cuba, by the colonial conquerous, i.e. gold extraction from rivers and use of asphalt to calk their ships; however, due to different historic reasons only a limited development took place in this field during the colonial domination. During the republican period beginning early in this century, other interests lead to a larger scale exploitation of some known deposits. From the beginning of the century up to the triumph of the Revolution in 1959, not less than the following figures were extracted of some Cuban minerals: Refractory Chromium 3,300,000t Manganese 7,650,000 t Copper 9,000,000 t Iron 22,000,000 t Nickel 150,000 t (Ni oxide and sulphide These productions were practically directed to cover the demands of the U.S., industry and some-times these Cuban ores were almost the sole suppliers of the market.

Jan 1, 1978

By J. Carr

Ring gear and pinions used as the final drive on large metallurgical grinding mills are expected to transmit their rated horsepower reliably for long periods of time. Duty is 24 hrs./ day. Life expectancy of such gear sets is of the order of 20 years; that is, each gear and pinion flank is expected to resist failure by pitting for 10 years. This means that for a dual pinion gear set having a ratio of 18.42:1.0 and a mill speed of 10 RPM, every gear tooth will see 105.12 x 106 surface contact stress cycles and every pinion tooth will see 968.15 x 106 surface contact stress cycles in a 10 year period. The allowable surface contact stress on the gear and pinion is determined by the material hardnesses. The rule being the higher the hardness, the higher the allowable surface contact stress may be.

Jan 1, 1985

By Aldo Bellone, Francesca Rossano, Massimiliano Bringiotti

"In 2004 works started for the now completed seven-level automated car park accommodating 480 parking spaces inside the pre-existent “Morelli cave”, located in a strategic area in Naples. Since 470 BC Greeks initiated the growth of the fascinating world of the underground Naples, of which this cave belongs. It seems that once here the god Mithras was worshiped. It’s also became a quarry for tuff extraction and in 1600s it became an aqueduct serving the area. In 1853 the Bourbon Tunnel, a project commissioned by King Ferdinand II of Bourbon to allow easy escape from the Royal Palace in case of riots, was connected to this network of tunnels. The cavern became an air raid shelter during the Second World War, then a deposit of cars and motorcycles in the '50s and' 60s, a disposal area and it has been abandoned in the last 40 years before it’s new utilization. INTRODUCTION Over time, the overcrowding and congestion of major cities’ historic centres has led to seeking spaces underground that can accommodate activities and car parks, as in the case of the Morelli cavity, site of the future car park by that name. Before describing its characteristics, design solutions, and executive problems, it is necessary to introduce the site historically into the broader landscape of the cavities present below ground in the municipality of Naples. The province of Naples, which includes the area of the Municipality of Naples, has a large number of cavities. The existence of “Naples underground” is connected with the morphological and geological conformation of its territory, consisting of tuff stone which has entirely special features of lightness, brittleness, and stability. The first transformations in the territory’s morphology, taking place thanks to the Greeks starting from 470 BC, initiated the growth of the fascinating world of Naples underground. These transformations were dictated by water provision requirements, which led to the creation of underground cisterns to collect rainwater, and by the need to recover construction material to erect the buildings of Neapolis. In subsequent centuries, the city’s expansion led to the construction of a proper aqueduct, which allowed drinking water to be collected and distributed thanks to a series of cisterns linked to a dense network of tunnels. During Roman rule, the existing aqueduct was expanded and perfected, but with the rise of the Angevins in 1266, the city saw great urban expansion, which obviously corresponded with increased extraction of tuff from the subsoil to construct new buildings. This confirmed a particular feature of Naples: that of having been generated from its own innards, with buildings rising directly above the quarry that provided their building material."

Jan 1, 2016

By G. W. Phelps

This discussion deals with the geology o£ the Tennessee-Kentucky ball clay deposits; their mineralogy and chemistry; methods of finding, mining and refining; and makes observations on reserves of and future prospects for these clays. Ball clays appear in ceramic formulas for manufacture of vitreous china sanitary-ware, electrical porcelains, floor and wall tile, dinnerware and artwares(l). This type of clay is used for refractory (2) and abrasive products(3), and as a suspending agent for ceramic glazes(4), engobes(5) and porcelain enamel slips(6). Although some ball clay is imported, probably 85-90 percent of ball clay used in the USA(7) is obtained from deposits in Weakley, Henry and Carroll Counties in Tennessee(8), and in adjacent Graves County, Kentucky(9). The term "ball", as applied to clay, probably derives from former mining practice in England whereby conveniently-sized blocks of clay were cut from moist clay beds by spading(10), The expression "ball" has no other technological significance. ASTM(11) defines ball clay as "a secondary clay, commonly characterized by the presence of organic matter, high plasticity, high dry strength, long vitrification range, and a light color when fired." This, and similar(12) definitions, applies to English ball clays but is not satisfactory for many American ball clays. Geology of the Tennessee-Kentucky Ball Clay Deposits Figure 1 shows that most commercial clay areas of the eastern United States lie near the edge of the Coastal Plain; a skew-shaped configuration of its landward boundary outlines the Mississippi Embayment(13), Near the apex of this basin a broad plain, with a rolling, Bullied topography(14), dips gently westward from the Tennessee River to bluffs at the edge of the Mississippi River flood plain.

Jan 1, 1972

By K. E. Laughery

The Nevada Barite industry has experienced a 277% growth over the last five years with a total production of 2,542,000 tons. Total production prior to 1970 approximates 2,700,000 tons dating back to 1907 Annual production, as can be seen in Table 1, has increased from 192,000 tons in 1971 to 723,000 tons in 1975. During this same period U.S production has increased from 825,000 tons to 1,056,000 tons. Nevada is now the leading producer with 69% of the market. The increase in the Nevada barite production is, of course, directly related to the increased demand for weight material coupled with the lack of other sources and the relative economic advantage of the Nevada barite, A significant tonnage of Nevada barite is utilized in the non-oil well market, principally at FMC's barite chemical plant at Modesto, California; however the growth has been in the oil well market.

Jan 1, 1976

By D. Kruse, M. Sanaei

"3D finite element models of the Segmentally Lined Shaft (SLS) structure are simulated as means of numerical analyses of the system’s structural behavior. Top-down constructed rings, comprised of precast concrete segments, create a large diameter, relatively shallow underground space that can be utilized for various applications. To further investigate the effects of soil conditions and different loadings on the shaft structure, the FE model was run under various boundary conditions. Simulations include a) effects of various soil layers on the SLS, including a circumferential boundary of modified ground, b) effects of various soil layers on the SLS without any ground modification, c) Seismic analysis of the SLS with ground modification and d) Seismic analysis of the SLS without any ground modification. Comparing the analyses outcomes emphasizes the significance of the inclusion of the ground modification boundary in the structural performance of the SLS. INTRODUCTION TO SLS Underground structures are classically built rectangular in shape, which normally requires a two-step construction process beginning with installation of temporary shoring to support earth loads during the excavation, followed by the construction of the permanent structure. Attractive and practical alternatives are circular shafts referred to as segmentally lined shafts (SLS). The structure consists of a stacked series of rings formed from an assemblage of precast concrete segments. Top-down constructed systems of large diameter, relatively shallow SLS structures provide both temporary earth support during excavation and permanent structural support for many civil and building applications. The circular shafts sustain the lateral earth pressure mainly through hoop-stress mechanism, resulting in improved stability and structural efficiency. Cylindrical shell structures with large diameter to wall thickness ratios are prone to buckling under external pressure. In typical designs of small diameter shafts and tunnel linings with small diameter to wall thickness ratios, nonlinear buckling analysis (i.e., nonlinear geometric analysis) is usually not considered, since the buckling capacities for those structures are much higher than typical pressures encountered at their design depths. With an economically viable wall thickness, buckling becomes a critical issue, which should be addressed, for circular shafts with very large diameters. In the design and construction of the SLS, the stability of the structure can be improved by modifying the soil surrounding the circumference of the shaft to a limited thickness and to about 10 ft below the finished shaft structure. This thick wall of soil mixed with cement creates a composite integrated structure while serving additional purposes such as ground control and ground water seepage cutoff."

Jan 1, 2016

By Bernd Hagenah, Hans-Peter Vetsch, Eric Jones, Sean Cassady, Danielle Johnson, Petr Pospisil

There are a number of issues associated with freight trains in non-electrified tunnels that are fundamental during the planning and operation of a rail tunnel. During uphill operation, increased air temperatures at the air intake locations of diesel trains can reduce diesel motor efficiency (stalling/choking) and affect HVAC systems. Strong airflows can aggravate fire scenarios due to fanning or water-reactive cargo materials. This paper focuses on the impact of freight trains on tunnel safety concepts, strategies to overcome heat issues at locomotive air inlets and air quality in tunnels operating diesel trains.

Dec 1, 2022

By T. Tamagawa, S. H. Tabaian, I. Iwasaki, N. X. Fu, M. Kobayashi

A gaseous chlorination process for the hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low-temperature chlorination -selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide. In this article, the chlorination phase of the process is described. Initially, the chlorination behavior of chalcopyrite concentrate micropellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established were used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 2000

By H. Sevim

The logic and capabilities of a long-term production planning method for open pit mining are presented. This is a new method that can be used to obtain simultaneous solutions to the four interrelated parameters of open pit mining: mine life, specific blocks to be mined each year, the amount of ore and waste to be mined each year, and the ultimate pit limits. An efficient milling cutoff grade can also be obtained through a systematic analysis. A production plan for a real-life gold deposit is given to illustrate the logic and the capabilities of the method.

Jan 1, 1994

By J. D. Crone

Crone Geophysics Limited in co-operation with Newmont Exploration Limited has developed a ground Pulse electromagnetic method. This is the first unit in a planned integrated system of surface and borehole Pulse EM equipment. Newmont had previously developed an operational Pulse EM unit for use in areas of very high surface conductivity. The Newmont equipment was large, heavy apparatus that required motorized transport. It operated in the equivalent frequency spectrum of 10Hz to 2.5Hz. The basic aim of Crone Geophysics was to design a Pulse EM system more portable than Newmont's. We wanted to operate in all types of field conditions including heavily wooded and mountainous terrain areas. We also wanted to record the higher frequency information that is contained in the Pulse EM waveform. There are three reasons why we thought this high frequency information was important in survey applications: (1) Field tests conducted over massive sulphide bodies in the Arizona desert showed that the desert weathering process tended to break down the electrical contact between sulphide crystals. The net effect is to reduce the conductivity of a massive sulphide body, particularly narrow bodies or highly fractured sulphide zones. In order to detect such occurances the higher frequency information is essential. (2) We wanted to be able to detect occurances with sulphide content as low as 5% sulphides that are usually poor to moderate conductors. (3) We also wanted to be able to determine the presence and extent of surficial conductive formations and clay deposits since many airborne EM anomalies are caused by such bodies. If we have the capability of detecting and recognizing these formations we would be able to explain the airborne anomaly.

Jan 1, 1976

By S. J. Page

The personal dust monitor (PDM) is a combined tapered element oscillating microbalance (TEOM) respirable dust monitor and cap lamp, configured to have dimensions and weight similar to those of a lead-acid miner’s cap lamp battery. The Higgins-Dewell (HD) cyclone design operated at 2.2 L min-1 airflow has previously been reported to have low bias relative to the International Organization for Standardization (ISO) convention. Previous reports have described the PDM as meeting the NIOSH Accuracy Criterion. In order to avoid certain analysis anomalies encountered during these evaluations, a different method of establishing the PDM relative standard deviation was employed. Re-analysis of laboratory data for both the early prototype and precommercial PDMs indicates that the PDM still meets the NIOSH accuracy criterion, and that the precommercial PDMs are more accurate than previously reported.

Jan 1, 2011