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By M. A. Girts

Wetlands can be constructed inexpensively on mined lands to treat small flows of acid mine water. Metals are removed from the water by the wetland vegetation and indigenous bacteria. Full-scale field tests initiated at over 20 mine sites during 1984 and 1985 indicate that water quality can be upgraded to meet discharge standards with relatively minor maintenance requirements. Iron concentrations of 25-85 mg/L in the influent water fall to less than 2 mg/L during flow through a small wetland. Manganese can also be removed, though somewhat less efficiently. At the discharge, pH is easily raised to 6 by flow over limestone.

Jan 1, 1986

By Greg Corbett

The paper point out the styles of Pacific Rim epithermal gold mineralization. Some characteristics of differing styles of epithermal gold mineralization influence investment decisions (metallurgy, metal ratios, mining style), while others should be taken into account during prospecting (pyrite content and resistivity govern geophysical techniques, vein/breccia styles control drilling, gold distribution influences ore reserve determinations). Two groups of epithermal deposits are distinguished by the fluid style which controls ore and gangue mineralogy. High sulfidation systems develop from the reaction of hot acidic magmatic fluids with host rocks to produce characteristic zoned alteration and later sulfide (dominantly enargite-pyrite) and Au-Ag-Cu deposition. Ore systems display permeably controls governed by lithology, structure and breccias, typically phreatomagmatic breccia pipes, and should be distinguished from a group of generally non-economic acidic alteration including: steam heated alteration, lithocaps or barren shoulders, acid sulfate, and magmatic solfatara alteration.

Apr 24, 2001

By Josef K. Alter

Long-term performance and behavior of post-tensioned ground anchors subjected to axial cyclic loading constitutes an important aspect of the stability, reliability and overall performance of wind turbine deep foundations. Axial cyclic loading of post-tensioned (PT) ground anchors in soils has not been thoroughly investigated as evidenced by the research conducted for this topic. This paper evaluates research test data, available literature, and industry expert opinion on the current status and problems of deep foundation post-tensioned ground anchor (PTGA) technology, as applicable to the wind energy industry. It also introduces a proposed design solution that addresses the problems of construction cost and long-term performance of wind turbine deep foundations in soils subjected to dynamic cyclic axial loading. Deep foundations using ground anchors for wind turbines have only recently gained attention as a possible viable alternative to the mass spread footings currently in use. One of the primary problems with general acceptance of current PTGA designs is the need for long-term anchor maintenance. The research that was conducted for this study indicates that current literature only partially addresses the many factors influencing load capacity and pullout performance of ground anchors. The lack of information indicates the deep foundation industry has fallen behind in designing and implementing new technology to improve safety and performance, ensure sustainability, reduce costs, and address environmental responsibility. This paper describes the significance of this problem as it applies to the wind energy market, and proposes a new technology solution. The research, expert opinion, and analysis presented by the author is used to support the premise that ground anchor construction cost and long-term maintenance can be reduced with PTGA systems using the Con-Tech Systems (CTS) patent-pending Groutable Void Form (GVF) technology.

Jan 1, 2010

By A Fyans, B Ghahreman-Nejad

This paper discusses the method and results of an options study into selection of the optimal form for a 130 m high tailings/water retaining dam, located in a region of high seismicity in central Iran. The proposed dam is part of a planned expansion project for Sarcheshmeh Copper Mine (SCM), which after construction will provide 550 million tonnes of additional tailings storage over the next 27 years. Geotechnical investigation at the proposed site indicated that adequate suitable low permeability materials (i.e. clay) were not available in the immediate vicinity of the dam site and would need to be imported from a distance of well over 10 km (direct). Given the magnitude of the estimated quantity of material and construction cost it was considered prudent to compare the cost of alternative dam design options for the proposed storage. A total of five dam design options are considered including a conventional rockfill embankment dam with an upstream sloping earth core (ECRD), a geomembrane face rockfill embankment dam (GFRD), a sloping asphalt core rockfill embankment dam (ACRD), a roller compacted concrete dam (RCCD), and a filter rockfill embankment dam for tailings storage together with a separate smaller earthfill core rockfill dam (ECRD) located downstream for storage of decant water. The risks, costing and design of all options are discussed in detail and the outcome of the study is presented.CITATION:Ghahreman-Nejad, B and Fyans, A, 2018. Optimum embankment design for a tailings dam, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 427–438 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By F. Chiesa

Experimental results on thin and thick castings poured in aluminum A356 and magnesium AZ91E by the low pressure permanent mold process have been compared to the result of filling simulations for thin and thick castings. If the results of modeling is reliable when the liquid remains above the liquidus temperature, this is no longer the case when partial solidification occurs. The visco-elastic behavior of a partially solidified liquid is difficult to put into equation as it depends on the amount of shear it has been been subjected to. Attempts to predict misruns with a commercial software has been proven to be very difficult if not impossible; divergence of the numerical solution has been observed unless prohibitively long computing times are used. In order to overcome these difficulties from a practical standpoint, a simple method is proposed which consists in tracking the temperature of the advancing liquid metal front so as to make sure it will always be above so-called `Misrun Critical Temperature' (MCT) determined experimentally for thin and thick aluminum A356 and magnesium AZ91E castings. If the liquid metal front falls below this temperature, a cold-shut or misrun is likely to happen at this location. The values of MCT for thin and thick in aluminum A356 and magnesium AZ91E were determined experimentally on misrun castings of extreme geometries (a thin 2.5 mm wall cover and a 6mm to 25 mm thick bell housing). MCT was found to be lower for magnesium AZ91E and for the thicker castings.

Jan 1, 2011

Not quite a year ago, during a speech to a group of mining professionals in Washington, DC, the subject centered around the long-range importance of conducting research projects and how much that research needs to specifically apply to health and safety matters in our industry. The point was made about the critical need to work together with government, private industry, labor organizations and academia speaking with a unified voice as we all march into the future together. The fundamental benefits of competitive research were mentioned --to improve our quality of life, to develop our energy resources, to achieve a safe and healthy environment and to ensure long-term economic growth. Very importantly, emphasis was given to the natural link that makes my agency, the Mine Safety and Health Administration, and the National Institute for Occupational Safety and Health --NIOSH --the beneficiaries of each other's findings. Unquestionably, there are lines of separation. The main responsibility of the agency I represent, MSHA, is enforcement of the nation's mine safety and health laws. But we also have an additional responsibility and that is to coordinate and give priority to research in a never-ending hunt for answers.

Jan 1, 1999

By W. W. Scott

Measurements of the absolute value of electromagnetic noise and attenuation along a hoist rope were made in an operating hard-rock mine, Lucky Friday Mine, located near Wallace, Idaho. Spectra of electromagnetic noise generated by various pieces of equipment, spectra of specific noise signals at various depths, and noise and attenuation on the 4250 foot (1295 meter) hoist, were measured. Three techniques were used to make the measurements. First, noise was measured over the entire electromagnetic spectrum of interest for brief time periods. Data were recorded using broadband analog magnetic tape for later transformation to spectral plots. Second, noise amplitudes were recorded at several discrete frequencies for a sufficient amount of time to provide data for amplitude probability distributions. A third technique gave attenuation data through the direct measurement of field strength at various depths. The specific measured results are given in a number of spectral plots, amplitude probability distribution plots and amplitude curves as a function of depth.

Jan 1, 1974

By W. J. Schlittler

Auxiliary Equipment pumping systems to support primary, secondary and regrind grinding circuits will be the primary focus of this paper. Every grinding system is unique and requires special design considerations for proper application of pumps to transport mill discharge. To satisfy the majority of applications, a new series of pumps has been developed by Svedala, known as World Class Pumps. Selection of these newly developed pumps for each type of grinding circuit will be presented. Specific components of selection are materials of construction, piping system, classification method, material characteristics and slurry characteristics. Both horizontal and vertical pump applications will be reviewed with emphasis on rules of pump piping and sump design.

Jan 1, 1999

By H. Manurung, I. M. Bendiayasa, W. Astuti, and H. T. B. M. Petrus, F Anggara, K. C. Wanta

The leaching kinetics of cerium (Ce) and yttrium (Y) in sodium-hydroxide-digested non-magnetic coal fly ash using acetic acid were investigated. The variables analysed were pH, solid-to-liquid ratio (S/L), and temperature. The results show that cerium and yttrium's maximum recovery was 57.33% and 58.36%, respectively, under leaching temperature of 90°C for Ce and 60°C for Y at pH of 1,74 and 10 g/mL solid-liquid ratio in 240 minutes. Increasing the leaching time to more than 120 minutes did not significantly improve the results. After the magnetic separation process, the ICP-OES analysis shows a slight increase in the concentration of cerium and yttrium on nonmagnetic components. The XRD and ICP-OES analysis for the sample before and after silicate digestion shows that 40% silicate was dissolved. The calculation of apparent activation energies of leaching using the Arrhenius law for the leaching of cerium and yttrium gives 22.72 kJ/mol and 35.84 kJ/mol, respectively. The kinetic leaching model of cerium and yttrium all fit Dickinson's new shrinking core model. The calculation results show that the leaching reaction is controlled by combining interface transfer and diffusion across the product layer.

Nov 6, 2024

By R. V. Higgins

The, large volumes of low A. P. I. gravity oil that will remain in many shallow fields of California when such oils no longer can be recovered profitably by pumping are important potential sources of oil when ways and means are found to remove them from the reservoir sands. Estimated ultimate oil recoveries in many of the "low-gravity fields" of the San Joaquin Valley in California indicate that less than 25 percent (on the average) of the original oil will be recovered. These oils have viscosities of 1,000 or more centipoises at reservoir temperatures and, because of their high viscosity and low intensity of the reservoir pressure, the quantities that will be retained in the sands ultimately are so large and their recovery is such a challenge to petroleum engineers that the Bureau of Mines has made the study of their possible recovery one of its major projects. The fact that a slight increase of temperature materially reduces the viscosity of low A. P. I. gravity oils has 'prompted the use of various means for increasing the temperature of the oil in the reservoir sands and hence the rate of flow and Completeness of recovery of the oil. Hot oil, hot water, heated air, and natural gas, steam, super-heated steam, and the products of combustion have been circulated in wells to raise the temperature of the oil it the sands; electric heaters have been installed in wells, and butane and air have been intermittently exploded and the flames propagated through the tubing to the "pay" zones. None of the methods, however, have been entirely satisfactory for the recovery of large quantities of oil.

Jan 1, 1949

By Odette Corbu

The Canadian Trade Commissioner Service: Who we are ? A worldwide network of professionals in international business development, with preferred access to business knowledge and contacts, committed to advancing Canada?s interest ? Our global presence ?At home: 17 Regional Offices with over 100 trade officers ? Abroad: 149 offices in 101 countries with over 900 trade officers.

May 1, 2009

By Matthew John M. Krane, Christopher J. Vreeman, J. David Schloz

"A continuum mixture model of the direct chill casting process is used to model the transport phenomena and solidification behavior in the Direct Chill casting of an Al - 6 wt% Cu billet using Wagstaffs AirslipTM process. The model, which includes the transport of free-floating solid particles, can simulate the effect of a grain refiner on macrosegregation and fluid flow. Numerical predictions of sump profiles and composition and temperature fields are presented. Two 45 cm diameter billets were cast under production conditions with and without grain refiner. Temperature and composition measurements and sump profiles are compared to the numerical results. The comparison shows excellent agreement for the grain refined case. It is believed that an incorrect model assumption prevents good agreement in the non-grain refined billet. IntroductionDirect chill casting is a semi-continuous process in which molten aluminum enters the top of a water-cooled mold, is cooled, and forms a solid ingot drawn out below (Figure l(b)). The molten aluminum begins to solidify due to the cooling effect of the mold wall. As the ingot is withdrawn from the bottom of the mold, water jets impinge on the surface, directly cooling the billet and forming a solid layer around a liquid melt, commonly referred to as the sump.A particular defect that occurs in a wide range of casting processes, including the direct chill (DC) casting of aluminum alloys, is macrosegregation, the uncontrolled redistribution of alloying elements on the scale of the ingot during solidification. Macrosegregation in DC cast ingots can produce non-uniform mechanical properties [l], which affects the behavior of the metal during downstream forming and heat treat operations."

Jan 1, 2001

By B Stump

Reliable particle size analysis in minerals processing plants is a critical factor to the economic return of a plant. As recovery of valuable minerals is compromised for particles outside the optimal size range, effective and reliable particle size analysis is more crucial than ever, particularly in the current upswing of the global commodities market. Inefficient particle size analysis can lead to excessive over-grinding, thereby significantly increasing energy consumption and reagent costs, whilst negatively affecting process operation, thickening capacity, water recovery and tailings disposal.Australia’s first installation of a particle size analyser in Iron Ore has been monitored with great interest by the industry. Previously, manual size sampling at Rio Tinto’s Paraburdoo fines processing plant involved off-site sample analysis, with a turnaround measured in days. The Outotec PSI® 500 particle size indicator, commissioned in July 2009, takes approximately three minutes per line at site.The paper will include details on the following:• plant description,• sampling design,• PSI® 500 analyser functionality description, and• key learnings from site.

Jul 11, 2011

By Walter I. Enderlin

To economically extract ore from great depths in the earth while sustaining an acceptable working environment will require the development of new technology and equipment, involving large capital expenditures. Moreover, careful analysis and advance planning will be required. But, the literature is lacking in data pertaining; to the thermal properties of various host rocks and to quantities of heat generated by various underground heat sources. This types, of data is required to forecast nine heat loads during advanced planning and design. This thesis sets forth a practical method for evaluating underground sources of heat in deep mines and provides an improved information base. Moreover, seven topics for further research are recommended. The heat sources considered are: wall-rock, ground water, adiabatic compression, equipment, service lines, blasting, metabolism, curing of cement, and oxidation of sulfides and timber. Seven deep metal mines with high production rates and high heat loads were visited to obtain data necessary to assess their thermal environments. Mine records were examined, wall-roc:, temperatures were measured and a survey of the mine ventilating air and mine drainage was performed. Also, the thermal conductivity of wet and dry specimens of the host rock were measured in the laboratory. Data analysis disclosed that rock heat and adiabatic compression account for stout 60 per cent of the mine heat load at depth. Equipment currently contributes approximately 20 per cent; however, to offset increasing costs with depth, increased mechanization is anticipated. The treat from ground water averages 19 per cent and the contribution from blasting, metabolism and cement is negligible. Also, approximately [0] per cent of the increase in the enthalpy of the ventilation air is in the form of latent heat. Moisture, however, did not significantly affect the thermal conductivity of the rock specimens measured in the laboratory. Also, from the data, it is evident that a negative correlation exists between the thermal conductivity of the host rocks and the per cent of the heat load derived from the wail-rock. Furthemore, steady state heat flow renditions may be assumed in airways where there has been no major changes in the ventilation system for a period of two years or more. Under these conditions, the author found it more convenient and reliable to compute heat influx using the steady state equation for heat flow into a cylinder, rather than Carrier's method for transient heat flow, which is so often used.

Jan 1, 1973

By M. Ziegler

The article deals with the use of a digital twin in the assessment and optimization of a conveyor system in the Chilean copper mine. This example shows that a digital twin is initially just a new (albeit powerful) tool with which the system behavior can be examined. The benefits for the customer arise through the system identification and automatic detection of critical deviations from the target state. This knowledge allows mine management to react and coordinate operational and/or maintenance counter measures to insure optimal performance of their conveyor system. The information derived from the BeltGenius digital twin also allows mine management to gain a clear perspective of the overall efficiency of their conveyors, which will be invaluable for future conveyor component selections.

Mar 2, 2022

[ENGLISH active earth pressure adapter additive adhesion admixture, addition adsorbed water aggregate air air entrainment air hose allowable bearing value allowable pile bearing load]

Jan 1, 1994

State of California, Division of Mines, Ferry bldg., San Francisco, Calif. Walter W. Bradley, State Mineralogist. A list of publications available will be sent upon request. Bulletin 77 is a list of publications complete from 1880 to 1917 and contains synopses It is sent free. Bulletin 105, California mineral production and directory of mineral producers for 1930, brings the complete list up to date, sent free on request The Division of Mines issues principally (1) A series of Reports, (2) Bulletins, (3) Preliminary Reports, and (4) maps. The Reports were first issued biennially, later annually, and for the past few years they have taken the form of quarterly reports. The yearly subscription price for the quarterly reports is $1, payable in advance Reports and separate chapters available are Report 2, First Biennial (1892), $1, 14 (1913-1914), Chapter on mines and mineral resources of Colusa, Glenn, Lake, Mann, Napa, Solano, Sonoma, and Yolo counties, 50 cents, 15 (1915?1916), Mines and mineral resources of Butte, Lassen, Modoc, Sutter and Tehama counties, 50 cents, and Mines and mineral resources of Monterey, San Benito, San Luis Obispo, Santa Barbara and Ventura counties, 65 cents, 16 (1917-1918), Nevada County, 75 cents, Plumas County, 50 cents, Sierra County, 50 cents; 17 (1920), Mining in California during 1920, $1 75, 18 (1922), Mining m California, chapters for Aug , Sept , Oct , Dec , free, 19 (1923), Mining in California, chapters for Jan , Feb , Mar, Sept , free, 20 (1924), Quarterly chapters on mining in California (except July, out of print), 25 cents, 21 (1925), Quarterly chapters containing county reports- Jan (Sarcramento, Monterey, Orange) 25 cents, April (Calaveras, Merced, San Joaquin, Stanislaus, Ventura), 25 cents, July (Del Norte, Humboldt, San Diego) 25 cents, Oct (Siskiyou, San Luis Obispo, Santa Barbara), 25 cents; 22 (1926), Quarterly county reports: Jan. (Santa Cruz, Trinity), 25 cents, April (Shasta, San Benito, Imperial), 25 cents, July (Mann, Sonoma) and Copper in California, 25 cents, Oct (El Dorado, Inyo) Minarets District, 25 cents, 23 (1927), Quarterly county reports- Jan (Contra Costa), 25 cents, April (Aniador, Solano) Bibliography of clay

Jan 1, 1933

By E. E. Mueser

As Mr. Lundberg has already ably covered the theory of various methods of electrical prospecting, I shall confine my remarks to a consideration of the features which must obtain in an electrical prospecting method in order that it may be useful from a practical standpoint. These remarks I shall make with particular reference to the Elbof method. The successful application of all these methods rests, in the first place, upon the possibility of correlating theory, or empirically established facts, with the field data. Their practical usefulness, however, requires that the technique of making the field observations, and the procedure itself, be such that the method may be applied to large areas, under normal average conditions. The method, therefore, should not involve excessive preliminary labour costs to prepare the ground for actual prospecting work, nor should the prospecting work itself be so slow that its cost, when applied to extensive areas, becomes prohibitive. Moreover, it should be possible to apply the method even under difficult terrain conditions, such as rough topography and dense vegetation. It may be said of most of the methods referred to in the preceding paper, that, while they are interesting and theoretically sound, they fail to meet such practical requirements as I have outlined.

Jan 1, 1926

By R. C. Ellman

This report presents results of a series of tests on grindability of lignites and factors that influence grindability determination. All grindability tests in this investigation were made in the standard Hardgrove test apparatus. In addition to tests on standard samples of equilibrium moisture content, grindability determinations were made on air-and oven-dried samples of lignite representing the complete range of moisture content from normal bed moisture to nearly moisture-free conditions. Grindability index for all tests was calculated both by standard method and by an alternate or "corrected" method of calculation based on directly measured weight of fine-particle material produced in the grindability test. The second method of calculation allows more satisfactorily for loss of moisture during testing of high-moisture samples.

Jan 1, 1955

By Wm. A. Haven

ON the northern part of the globe, almost since the earliest days of mankind's history. ironmaking has been practiced in one form or another. Some investigators question the generally accepted belief that copper and bronze were in earlier general use than iron, explaining the greater age and abundance of copper relics by their greater resistance to natural oxidation. However, the occurrence of copper in its natural state and its greater ease of reduction from the simpler copper minerals is a strong argument that the making and use of copper came first. Nevertheless, good evidence exists that ironmaking was practiced in ancient India and China, as well as in ancient European countries. Some interesting vestiges of those early operations still survive and have a place, in the background at least, of a discussion of modern blast-furnace practice.

Jan 1, 1940