Search Documents

By W. L. O?Connell

[Patent Issue No. Date Issued To Subject 386,504 July 24, G. Sweanor The separation of quartz from a 1588 metal with a liquid such as CS2 or CHC13 under water by introducing mixture into water layer. Quartz will stay in water layer while metal sinks through organic.]

Jan 1, 1963

By Y. Numata

2-Mercaptobenzothiazole (MBT) is a heterocyclic-mercaptan and belongs to a group of molecules containing nitrogen and sulfur as electron donor atoms. MBT has been employed as a collector in flotation under names of MBT, Captax, and Flotagen. It is a major constituent of reagents in the 400 series of the American Cyanamid Co. Current applications of the reagent include flotation of copper minerals, tarnished or oxidized lead, copper activated sphalerite, and nickel ores. It has been used successfully in the flotation of pyrite in acid circuits in the range of 4 to 5.

Jan 1, 1990

The dissolution kinetics of cobalt in iodine/iodide solutions was investigated using a rotating disc technique. Variables studied here included temperature, rotating speed, concentration of lixiviants, and pH of the solution. The overall dissolution reaction was found to be limited by mass transfer of tri-iodide through the diffusion boundary layer with Arrhenius activation energy of less than 16.2 kJ/mol (4 kcal/mol) over the temperature range, 2-42°C. The pH of the solution had little effect as long as the pH of the solution was less than 8. However, when the pH of the solution became greater than 8, the dissolution rate decreased dramatically due to passivation. The rate of dissolution was in good agreement with the dissolution model developed by the authors earlier.

Jan 1, 1994

By R. Fields

Nevada is primarily known today for its nation-leading production of gold and silver. However, industrial mineral production continues to play an important role in providing construction materials to help make the state the fastest growing in the United States. Aggregate production in Nevada was about 20 million tons in 1991. Most of that was used in construction in the fast-growing Las Vegas area. The state leads the nation in the production of barite and mined magnesite and has significant production of lithium carbonate, diatomite and gypsum. Other industrial minerals produced in the state include specialty clays, silica, lime and dolomite and relatively small production in salt, perlite and dimension stone. Industrial minerals operations are subject to state and federal permitting requirements, especially in the areas of air and water quality and mined land reclamation. As in all segments of the mineral producing industries throughout the nation, the amount and complexity of regulations affecting industrial minerals has increased significantly in recent years. Nevada is no exception.

Jan 1, 1993

By M. Nambiar

Due to the remote locations of mining projects and the need for long transmission lines to provide electrical power, mining sites often operate with poor network power quality and low short-circuit capacity. To cope with this situation, more and more mining operators are considering the installation of appropriately designed synchronous condensers together with power factor correction and harmonic filter systems (PFC & HFS). The installation of such power quality equipment is viewed as a technological advancement in the mining application. An adequate level of short-circuit power is essential and has to be ensured for the safe and reliable operation of especially large cycloconverter-driven gearless mill drive systems (GMDs) used for grinding. This paper explores the impact, technical advantage and reasoning for the selection of this advanced hybrid technology to cope with the power system challenges of future mining projects. It also delves into the potential problems and how to address them.

By M. Kaya

This paper presents an experimental method to determine the degree of gangue entrainment in mechanical flotation cells and proposes new and inexpensive methods to lessen it. The applicability of froth washing and vibration was studied in laboratory, pilot plant, and plant scales. The effect of wash water on metallurgical performance was tested with various streams from the Falconbridge Strathcona mill at laboratory, pilot, and plant scales, with the 2nd cleaner at the Eastmaque Kirkland Lake mill, and with the 2nd and 3rd zinc and 3rd and 4th copper cleaners at Les Mines Selbaie mill. It was found that gangue recovery was closely related to water recovery in all systems. Wash water at an optimum superficial rate from 0.03 to 0.07 cm/s reduced entrainment by anywhere from 30X to 70X. Wash water can be further assisted by mechanical and ultrasonic vibration of the froth. A further rejection of 10 to 20X becomes possible. As a result of this work, a number of plants in Canada and in the United States have evaluated and/or are now using froth washing.

Jan 1, 1990

By R. R. Young

Prior to 1903, the world's supply of sulphur was primarily from surface deposits in Sicily. The discovery of the first salt dome sulphur deposit in 1867 and successful development of the Frasch process for recovering the sulphur resulted in a large part of this essential element being supplied from these mines since 1920. Although the basic process is the same today, engineering and technological developments have evolved to allow its application under many adverse conditions. These and other challenges for the industry in today's environment will be discussed in the paper.

Jan 1, 1979

By B. R. Pothini, H. von Schonfeldt

In underground coal mining many excavated openings have a relatively short projected life span. To ensure safety for men and materials at a minimum cost over the projected operating life, only pillars for overburden support and roof bolts for support of the openings are used extensively. Mining activity constantly changes the geometry of the mine producing load changes on the structural support members of the openings that often induce unstable deformations which can lead to roof falls or pillar failures. The paper describes how simple deformation measurements can be used to design primary and supplementary roof supports and to predict roof falls and possibly pillar bumps. Specifically, bed separations in the roof measured directly with the help of borescopes and calculated from differential convergence data are used to optimize bolt links or support requirements for chemical stabilization of mine roofs. Roof falls are predicted on the basis of admissible values for cumulative convergence between roof and floor, convergence rate, and the change of the rate of convergence. The pillar extraction operations convergence anomalies detected from contouring identify bump prone pillars, while convergence and pillar dilation determine the yield zone in a pillar to verify pillar softening and de-stressing. Manuscript not received in time for publication.

Jan 1, 1983

By A. K. Sheik

A small underground mine in northern Idaho was used as an experimental facility for studying the role of water in the analysis of mine opening stability. Laboratory test data, borehole measurements and geological mapping assisted in constructing a coupled finite element model of the rock mass. The model was used to make quantitative estimates of: 1) rock stress, strain and displacement changes, and 2) water pressure and flow velocity changes that occurred during historical mining. Stope cuts and wet fills were included in the analysis. Stability of crown pillars between stopes was of particular interest. The relatively low effective stress and high rock mass strength showed that water pressure changes were of no great consequence in agreement with experience. The computational tools used in the analysis may be applied to other wet mines with appropriate changes to site-specific input data.

Jan 1, 1999

By R. E. Le Messurier

GENERAL DESCRIPTION The mines are located at Broken Hill in the western part of New South Wales, Australia, 930 km west¬northwest of Sydney. Mining Methods Where pillars must be left between stopes, extraction of a block of ore between two or more levels is carried out in stages: 1) Stopes are mined overhand by horizontal cut¬and-fill stoping, or by long-hole stoping. The various methods of horizontal cut-and-fill stoping used are desig¬nated as: -Loader cut-and-fill stoping with horizontal blast¬holes and diesel load-haul-dump (LHD) units. -Open stoping with horizontal blastholes and com¬pressed air or electric scrapers, or with diesel or electric LHD units. Square-set timber stoping, where ground condition precludes open stoping. The backs are sup¬ported with timber square sets. Pattern rockbolting of the backs may be used as an intermediate stage between open stoping and square-set stoping. 2) Vertical pillars are mined by undercut-and-fill stoping or by vertical crater retreat stoping. 3) Where a horizontal pillar has been formed below the level above the primary stope, this level pillar, usually 6.1 to 8.2 m in depth, may be mined by over¬hand square-set stoping or by undercut-and-fill. Long-hole stoping is used at the Zinc Corp. (ZC) and New Broken Hill Consolidated (NBHC) to mine parts of the zinc-rich A and B lodes. Drilling is carried out from drill drives and, in some cases, sills. Hole sizes used are 165 mm (61/2 in.), 110 mm (4'h in.), and 65 mm (21/2 in.) nominal diam with hole lengths being limited to 50, 30, and 20 m respectively. Ammonium nitrate-fuel oil (ANFO) and water gel explosives are used. Broken ore is loaded from drawpoints at the bottom of the stope using rubber-tired diesel-driven LHD units which deliver ore to an orepass. Annual production at Zinc Corp. and NBHC accord¬ing to mining method is given in Table 1. At Zinc Corp. mining is being carried out at depths varying between 200 and 832 m. At NBHC it ranges from 528 to 915 m below the surface. The average travel time to the stope is 30 to 45 min. GENERAL ORE BODY REQUIREMENTS Size, Shape, and Dip There are six separate lodes which carry minable ore in the mines of Zinc Corp. and New Broken Hill Consolidated. The lowest of these and the main ore bodies presently being mined at Zinc Corp. are the lead lodes, consisting of a siliceous fluoritic ore body (No. 3 lens) and overlying it a calcite rhodonitic ore body (No. 2 lens). Each possesses characteristic ratios of lead, silver, and zinc, although the grade within each lens is variable, in places being as high as 30% Pb. There are also low¬grade portions which consist chiefly of poorly mineral¬ized rhodonitic material. No. 3 lens terminates within the Zinc Corp. leases, while No. 2 lens continues into the NBHC leases where it continues to provide a significant proportion of pro¬duction from the mine. Overlying the No. 2 lens are the various zinc-rich ore bodies. In ascending sequence these are lower No. 1 lens, upper No. 1 lens, A lode, and B lode. A typical assay for the small No. 1 lens group ore bodies is 8% lead, 50 g/t silver, and 20% zinc. The `A' lode is a large low-grade ore body in which the higher grade sections assay 4% lead, 30 g/t silver, and 10% zinc; larger quantities of lower grade ma¬terial also occur. B lode, the main zinc lode, typically assays 5% lead, 30 g/t silver, and 17% zinc. B lode increases in size as it extends south, and in NBHC is a major ore body, contributing about 52% of the production. All the lodes pitch south, the average pitch being 0.52 rad (30°) in the Zinc Corp. leases and rather flatter than this in the NBHC leases (see Figs. 1-3). The ground is all competent rock. Production requirements at Zinc Corp. are 900 000 t and 1 200 000 at NBHC.

Jan 1, 1982

By Summers D. A.

A mining machine has been designed and fabricated to mine coal from room and pillar operations combining high pressure waterjet cutting and mechanical fragmentation. Waterjets are used to slot the coal face with an advancing plow wedge then breaking out larger coal pieces. The machine has the following advantages: - simply built around a disassembled longwall chock and gathering arm loader apron; - few moving parts which are simply and inexpensively maintained; provides immediate roof support in the face working area; - coal produced is larger, with resulting lower preparation cost; - no dust is generated; - risk of spark generation is virtually eliminated.

Jan 1, 1992

The purpose of this paper is to demonstrate how the Computational Fluid Dynamics (CFD) technique can be an attractive approach to evaluate the performance of face ventilation systems. To present the capability of the CFD for such a study and for design purposes, a series of simulations using CFD have been performed at the Department of Mining Engineering, University of Kentucky, for different face ventilation arrangements (e.g. different scrubber geometries, brattice (curtain) and continuous miners locations, airflow quantities, etc.). Results from these simulations are displayed as three dimensional graphs and discussed. Needs for the field validation of these results and refinements of design methodologies are also discussed.

Jan 1, 1998

By J. M. Wempen, R. D. WEYHER, M. K. McCarter

Beam theory is a proxy for the behavior of intact, deforming roof strata above underground openings. Strong, stiff, intact strata have the ability to store significant strain energy when underground openings have large spans, as is typical of longwall operations. When strata fail, they may release some or all of this strain energy. Released energy is partitioned between fracture, thermal and seismic energy. The tensile failure surface in simply supported beams is predicted to be free of shear stress. This prediction and the kinematic inability of crack slip during fracture make significant dissipation of energy by friction unlikely.  In this study, the failure energy partitioning of specimens from the Nugget Sandstone formation is examined. Tensile fractures in specimens were induced using three-point loading tests. Elastic waves emanating from fracture events were recorded using an array of accelerometers. Accelerometers were placed within two crack lengths of the fracture surface, and the acceleration records are similar to strong motion seismic records. Spectral analysis was performed and used to develop synthetic, well-behaved, acceleration signals. Synthetic velocity signals were used to estimate radiated seismic energy generated by fracture. These estimates of radiated seismic energy demonstrate a potential means to constrain the minimum seismic partition. Fracture testing was performed on additional samples to estimate the fracture toughness of the sandstone. Synthesis of this data demonstrates a potential means to constrain a maximum seismic partition. Bounding the seismic partition for this type of fracture event could aid the detection and evaluation of seismicity emanating from longwall operations. Having better information about the location and magnitude of mining induced seismicity within longwall overburdens could lead to better understanding of extraction sequencing and rock behavior in general. These energy estimates also support the hypothesis that dissipation of thermal energy by friction is small in bending tensile failure.

By M. S. Celik

The principal impurities in some feldspar ores are titanium and iron which impart color and in turn degrade the quality of the ore. The mineralogical investigations indicate that titanium element originates from mainly rutile with small amounts of sphene. Conventionally, fatty acids and particularly sodium oleate are extensively used in the flotation of colored minerals from feldspar ores with reasonable success. In this study, new reagents, oleoyl sarcosine and hydroxamate have been used to float colored impurities before and after magnetic separation. Oleoyl sarcosine is found to exhibit better results compared to fatty acids and hydroxamate. The mechanism of the action is elaborated on the basis of experimental data.

Jan 1, 1999

By Tedd B. Bodimer

Why complicate an already complex machine such as a continuous miner by adding roof drills? Immediate permanent roof support is an immediate thought of the mining engineer just as elimination of frequent time-consuming places changes is a thought of the methods engineer. The realization of those two objectives has the potential for improved safety with increased production is the thought of the general manager. Miner-Bolters Used a Generation Ago These are not new thoughts as the 1CM continous miner equipped with two integral roof drills was introduced twenty-five years ago. Approximately two hundred of these machines were sold in the next five years for use in medium and high seam operations. The 1CM miner chassis that remained stationary in the center of an entry or room while the ripper bar was swung and sumped hydraulically provided an ideal platform for mounting two roof drills that could be operated during the continuous miner's production cycle. Two roof bolts could normally be installed in less time than required for the mining cycle. A typical roof drill unit is shown in Figure I.

Jan 1, 1981

By L. Zhou, D. Bahrami

Mine ventilation is one of the most important aspects of mining operations in underground mines. It is critical to maintain and deliver required fresh air to the active areas to reduce the risk of overexposure to hazardous contaminants or explosive atmospheres. An unexpected or unknown event such as roof collapse, unexpected mine door closure/opening, a fire/explosion, or fan malfunction could adversely alter the airflow distribution within the mine ventilation network that could lead to a hazardous underground environment. Knowing the occurrence and location of such an incident is of critical importance. In this study, the authors developed a novel methodology to assist mine operators in quickly identifying the location of any abnormal airflow change within the network using the airflow changes at monitored airways. The concept is based on a direct derivative method developed by the authors. This paper provides the details of the developed method as well as numerical verification examples. The application of this method can benefit mine operators and safety personnel in making better decisions during a mine emergency response operation to mitigate hazardous conditions arising from an unexpected airflow disturbance

Mar 2, 2022

By Kim Appleby

Epithermal gold-silver (lead-zinc-copper-manganese) mineralization on Misima Island is confined to steep and reactivated flat-lying normal faults in the upper plate of a major, shallowly dipping detachment fault. The hangingwall comprises an Eocene metavolcano-sedimentary sequence that has been extensively intruded byMiocene calc-alkaline granodiorite. It is unconformably overlain by Pliocene sedimentary and volcanic rocks. High-pressure amphibolite facies rocks dominate the footwall and have many characteristics of a metamorphic core complex. Mafic-alkalic lamprophyre dike swarms intrude the hangingwall and footwall sequences. Previous workers attributed the gold-silver mineralization on Misima to the intrusion of the porphyritic granodiorite (Williamson, 1984). This has been proposed for many tertiary gold deposits of the southwest Pacific(Sillitoe, 1989; Leach and Corbett, 1994).

Jan 1, 1996

By Joseph M. Zigich

The Anaconda Minerals Company operates a molybdenite and copper producing mine and mill facility near Tonopah, Nevada. Included with the milling facility is a ferric chloride leach plant for removal of copper mineralization from the molybdenite concentrates. Discussed are the engineering and construction schedules associated with the leach plant. The chemistry associated with the process along with a description of the process flow, equipment, and operating parameters are contained in the paper.

Jan 1, 1983

By Davar Abi-Zadeh, Cillian Brown, Deepak Kandra

"Grout backfill strategy for a particular subsurface concrete tunnel (~4.9km long, 3.5m in diameter, carrying 20” gas pipeline) was based on achieving 1:100 slope of the fill in order to progressively fill the tunnel, in a series of 350m section. Grout rheology, particularly its non-Newtonian and thixotropic behavior, determines the final fill slope for given backfill strategy. The objective of this study was to simulate the two-phase grout mix backfill process using Computational Fluid Dynamics (CFD) and determine the slope of the fill to validate and optimize the backfill strategy. Three dimensional CFD study showed that for a 500m long tunnel section with a single injection point of grout, given its rheology, it will likely keep flowing without filling the 500m section height wise. Design optimization for filling was carried out using two dimensional studies to make the backfill process “slope independent” by incorporating a 2.5m high bulkhead at ~1,000m. INTRODUCTION As part of a gas field development a 20” onshore gas pipeline is required from the landfall site to the processing terminal some 8km inland. At the landfall site the gas pipeline is routed in a ~5km underground tunnel underneath a bay. For operational reasons and planning consents as well as to mitigate environmental impact based on an environmental impact study, once the gas pipeline and the associated services and spares have been installed, the subsurface gas tunnel will be fully grouted. There will be no permanent access to the tunnel after construction is completed and the site compounds have been reinstated once works are complete. One of the key requirements is that “full grouting of the tunnel” is desired. The grouting material used is a non-Newtonian and thixotropic fluid mixture of bentonite, cement, plasticizer, retarder/stabilizer and water. The tunnel is filled progressively in 350m sections using a combination of existing and new pipework assuming the grout rheology will yield a fill slope of 1:100 in a 350m section. The proposed grouting system used one pump at the grouting compound to pump the grout into the tunnel using the existing tunneling pipework. For the longer runs a second booster pump was used in series to pump the grout to its final discharge location. The filling process is controlled via a system of flow meters, pressure transmitters and a tunnel CCTV system."

Jan 1, 2016

By Alexander N. Winchell

The construction and erection of the Coleraine concentrating plant was commenced in April, 1909, and was completed (with the machinery installed) ready for use in 1910. Attached to the main building is 'a table house large enough to accommodate con¬centrating tables for five units and space for a small machine shop and supply store. For the handling of the' railroad cars in the upper portion of the mill there is provided on the north side of the main structure a trestle approach 650 feet long, and on the south or opposite side a tail track 300 feet long. The latter is so constructed as to permit its being incorporated directly in a possible future extension of the plant. The building, viaduct approach and tail, trestle, as well as the table house, are con¬structed of steel, the total amount used being 6,100 tons. The building is covered by corrugated' steel sheeting over 2 x 6-inch wood sheathing fastened directly to the structural steel. The north end of the trestle approach is connected with the main road-beds forming the track system for delivery of the crude ore to the plant over an embankment of a maximum height of 110 feet containing over 2,000,000 cubic yards of dirt.

Jan 1, 1920