Search Documents

By Sutham Niyomwas

Silicon-Silicon Carbide (Si-SiC) composites were synthesized by self-propagating high temperature synthesis (SHS) from a powder mixture of SiO2-C-Mg. The reaction was carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The effects of silica sources and carbon mole ratio in precursor mixture on the Si-SiC conversion were investigated using X-ray diffraction and scanning electron microscope technique. The as-synthesized products of Si-SiC-MgO powders were leached with 0.1M HCl acid solution to obtain the Si-SiC composite powders.

Jan 1, 2009

By J. Gordon Parr, D. H. Polonis

IN a previous study of hypereutectoid Ti-Ni alloys' a substructure was observed in quenched powder specimens when the constitution was 100 pet retained ß body-centered-cubic phase. The alloy powders were quenched from 1000°C by a blast of helium gas and precautions already described were observed throughout the work, to minimize contamination. Ogden et al.2 have previously observed subboundaries in the ß phase of a Ti-Mn-N alloy; but this structure was attributed to nitrogen-rich a precipitation. The nitrogen content of the Ti-Ni alloys does not exceed 0.02 pet and the quenching rate was sufficiently rapid to suppress precipitation reactions. Since X-ray diffraction results have confirmed the absence of any second phase which might account for this phenomenon, it seems unlikely that this substructure is explicable in terms of nitrogen content. Fig. 1 shows the substructure in adjacent grains of 100 pet ß phase in a quenched 6 atomic pet Ni alloy. Fig. 2 shows adjacent ß grains in a similarly treated alloy; one grain contains marked intracrys-talline boundaries and the other is completely free from any substructure. The suberystals appear to have fairly regular shapes, suggesting a regular orientation relationship among them. Tempering the retained ß structure at temperatures below the eutectoid eliminates the substructure at an early stage of ß decomposition. At the present time it is possible only to guess at an explanation for this subboundary phenomenon, since very little work has been reported on substructures resulting from phase changes. It is believed that the present phenomenon is due to poly-gonization resulting from unrelieved stresses set up

Jan 1, 1957

By T. Stauffer, B. McGunegle, A. Adu-Acheampong

The Fairmount Minerals, Inc., Maiden Rock underground sand mine historically delivered air to ventilate diesel-powered equipment at its working faces through high-resistance, 15-inch-diameter PVC distribution lines. In support of plans for expanded production, three new, low-resistance ventilation design alternatives were analyzed. The study determined that adequate ventilation for expanded production was possible with various commercially-available, high-volume/low-pressure fans combined with a systematic layout of control structures. The recommended re-design was implemented in 2001, resulting in a significant increase in flow volumes and a noticeable improvement in the mine environment.

Jan 1, 2007

By M. Drozd, M. Somppi, Z. Yamak

"Granular activated carbon is widely used in the gold mining industry for gold extraction from aurocyanide-containing slurry. The extraction process can employ carbon as part of the gold recovery operation for various circuit designs including carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) circuits. However, various qualities of activated carbon exist and the durability of the material can change significantly from source to source. Handling this expensive reagent can pose challenges when fine carbon losses occur in the CIP, CIC, and CIL circuits. Additionally, any gold that is adsorbed to these carbon fines can also be lost by various mechanisms including carbon attrition and fracturing, inefficient coarse-fine separation, and poor carbon fines capture. With the above in mind, a series of tests were conducted to investigate standardizing simple laboratory methods for testing carbon quality. A standard procedure beyond or enhancing ASTM methods can serve as additional starting points for evaluating carbon specific to the gold industry. The investigation focused on size distribution, flatness, wet attrition resistance, surface area, gold kinetics, and gold loading. The final results provided information to generate an equation for ranking carbon samples to plant performance.IntroductionActivated carbon for use in gold extraction is amongst the most commonly found processes in modern gold-milling plants. Although gold losses are inevitable in the milling process, operators often focus on the importance of maximizing gold recovery. One focus area that is important in gold recovery is optimizing the use of activated carbon and examining potential changes to realize improved economics for carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes."

Jan 1, 2017

By M. Shapiro, L. A. le Grange, B. Henning

A paper was presented by Bateman Minerals and Metals at INFACONX (2004) describing a simplified Computational Fluid Dynamics (CFD) Model for predicting the temperature and velocity distributions in all the fluid zones of a single electrode DC Furnace simultaneously with the temperature distributions in the refractory lining of the vessel. The boundary conditions imposed on the model consisted of the arc current, external surface film coefficients and ambient temperatures. The temperature and velocity distributions in the free-board, slag and metal were solved simultaneously by coupling across the interfaces between the fluids and transportation phenomena developing in the plasma arc. A simplified model was used to describe the ex-change of energy by radiation between the arc and surfaces enclosing the freeboard region. The strengths of this model were reported as being the ability to: ?Solve the different zones and transportation phenomena simultaneously without the need to transfer partial numerical results between different numerical analysis applications. ?Solve velocity and temperature distributions without assumptions regarding internal film coefficients and additional internal temperature boundary conditions. One of the disadvantages of the model was that the energy absorbed by the process was not modelled, resulting in vessel performance predictions under heat loss conditions only. Whilst this allowed potential problem areas such as localized refractory heating to be identified, the model was only capable of predicting how these could be improved by varying the overall geometry and materials of construction. This paper presents improvements in the application software and user defined subroutines of the model as follows: ?Incorporation of surface to gas, gas to gas and gas to surface radiation models to improve the accuracy of radiative heat transfer mechanisms within the freeboard. ?Incorporation of a process energy absorption model based on a theoretical temperature dependant enthalpy curve which incorporates melting, smelting and superheating in selected areas of the bath. This enables the effect of feed distribution and power to feed ratio changes to be estimated. The effects of a commercial arc at full power on the freeboard and slag can now be simulated with increased accuracy.

Jan 1, 2007

By Samuel J. Sims

The Grace mine magnetite deposit, located 2 miles north of Morgantown in Berks County, Pennsylvania, was discovered in 1948 by an aerial magnetometer survey. It is situated on the southern border of the Triassic lowlands section of the Piedmont province. Cambrian sandstones, shales, and limestones overlie Precambrian crystalline rock and were folded and thrust-faulted during the late Paleozoic Appalachian revolution. Late Triassic continental sediments were deposited on the deformed basement rocks and were intruded by Late Triassic diabase dikes and sills before regional tilting and normal faulting occurred. The Grace mine magnetite ore is characteristic of the Cornwall type. The ore has replaced a Cambrian limestone lens isolated between Triassic diabase footwall and Triassic sedimentary rock hanging wall. The ore body is roughly tabular in shape, dips 20° to 30°NE and plunges about 20°N80°E. The ore is granular, fine- to medium-grained, typically consisting of unevenly distributed magnetite in a matrix of light green to white serpentine gangue. Magnetite is the major ore mineral, pyrite and chalcopyrite are common accessory minerals, and pyrrhotite occurs locally. Sphalerite, marcasite, galena, hematite, digenite, and goethite are uncommon. Serpentine, talc, and chlorite are the major gangue minerals; calcite and dolomite are common, and phlogopite, tremolite, and biotite are present locally. Apatite is a common accessory; sphene is rare. Calcium-magnesium silicates were formed first by contact metamorphism of impure limestone by the intruding diabase. Later, the silicates were altered hydrothermally to the serpentine- talc-chlorite assemblage now present. Magnetite, the first ore mineral, formed by replacing serpentine and was followed by pyritepyrrhotite and then by chalcopyrite-galenasphalerite. Marcasite, secondary pyrite, goethite, and hematite are secondary minerals resulting from alteration of pyrrhotite and magnetite. It is estimated that confining pressure was about 1500 bars and the temperature range was 500° to 675°C during ore formation.

Jan 1, 1968

By Carlton E. Brown

Sand, which is used widely under the wheels of mine locomotives to prevent slipping, is an important source of silica dust breathed by some employees of certain mines, such as those having appreciable grades on haulageways. The sand, as received, contains dust, and other dust is produced by passage of wheels of the train over the sand. Dust is disseminated into the air by such means as handling during unloading, drying, transporting, underground, sprinkling on the rails, passage of trains over Sections where sand is being or has been used, and walking over deposits of sand (or the dust thereof) on the haulageway. The disseminated dust is inhaled not only by persons in the immediate vicinity but also by others to whom the contaminated air travels. The inhalation of this must should be prevented to eliminate any possibility of the material causing silicosis (sometimes referred to as miners' consumption, miners' asthma, miners' phthiris, or miners' lung) and defined by the American Public Health Association4/ as: A disease due to breathing air containing silica (Si02), characterized anatomically by generalized fibrotic changes and the development of miliary nodulation in both lungs, and clinically by shortness of breath, decreased chest expansion, lessened capacity for worm, absence of fever, increased susceptibility to tuberculosis (some or all of which symptoms may be present), and by characteristic X-ray finding.

Jan 1, 1944

By N Stoitis, L Lien, B Tapley

The treatment of hypersaline waters originating from numerous gold projects within the Western Australian Goldfields region via membrane technology has been assessed. A combination of Ultra-filtration (UF) and Nano-filtration (NF) using Ecotechnol’s modified elements effectively removes the polyvalent ions responsible for the high lime and cyanide consumption as well as the prevalence of scale formation characteristic of gold operations in this region. Through removing up to 98% magnesium, 94% calcium and 99.7% sulfates from hypersaline water with total dissolved solids from 40,000mg/L to 250,000mg/L, Ecotechnol and subsequent independent tests have demonstrated up to an 87% reduction in lime consumption and through the ability to increase the operating leach pH, reduce cyanide consumption by up to 28%.CITATION:Tapley, B, Stoitis, N and Lien, L, 2015. Modified nano-filtration membrane treatment of hyper-saline goldfields water – an overview and benefits to gold plant operation and economics, in Proceedings MetPlant 2015, pp 431–463 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Michael K. Phang

The use of explosives to fragment rock generates ground vibrations which may have a detrimental effect on contiguous underground coal mine openings. Increased surface blasting by a burgeoning number of surface coal mines and quarries has caused considerable concern among underground mine operators. Ground vibration effects generated from surface mine blasting are also causing public concern. In response to this concern, the U.S. Bureau of Mines (Stagg and Engler, 1980) has measured and analyzed ground vibrations and their effects on underground and surface structures. Some of the complaints registered against the mining industry are claims of substantial material damage from vibrations generated by the blasting; others are nuisance complaints of minor damage or annoyance. In general, allegations of damage from surface blasting have been sufficiently numerous to constitute a major problem for mine operators engaged in blasting operations. They have recognized the need for more technological data to evaluate the vibration problems associated with blasting. Both the operators and the general public need adequate safeguards based upon factual data to protect their specific interests. The coal mine industry needs reliable information from which to change blasting operations to reduce the number and severity of major damage claims and eliminate the growing number of nuisance complaints. The problem is of major concern not only to coal mine operators and nearby property owners, but also to federal, state and local governments. At the same time, environmental control agencies responsible for blasting and explosives use require reasonable and appropriate guidelines to protect the miners' lives.

Jan 1, 1984

By Derek Ettie

"In the Hydrometallurgical processes, the presence of the so-called "crud" is a constant challenge in solvent extraction. Crud is a stable emulsion which forms along the interface between the aqueous and organic phase. The spread is influenced by the following parameters: first, wind blows the dust and impurities into the open sedimentation tanks. Second, the undissolved solids such as sand transported in the PLS causing problems in conjunction with incorrect agitator design.The crud fraction can decisively impact the efficiency of the hydrometallurgical extraction because the phase interface can constitute a large fraction and the sedimentation tanks cannot react flexibly to it. In the downstream process of the series-connected sedimentation tanks, they are thus all contaminated with crud. At the same time, the necessary mass transport is significantly impeded at the phase boundary between organic phase and aqueous phase due to the crud formation.The transfer of the organic phase into the electrolysis cell can result in a "burnout" of the cathode. The carryover of this electrolyte into the extraction can cause problems with the pH regulation. The carry-over of the organic components into the raffinate also leads to contamination of the leaching circuit. The continuous treatment of the crud with a 3-phase decanter centrifuge is extremely effective in combating this problem. This technology splits all three phases from each other and they are consequently continuously separated. All subsequent process steps exhibit a stable, uniform effectiveness. The main advantage for the customer is that fluctuations in the process are eliminated and the organic phase can be recirculated back to the extraction. The recycling of the solvent alone justifies the investment in less than 6 months as examples from South Africa and Chile show.To operate solvent recovery in daily operation fully automated online at the optimum limit, the decanter centrifuge is equipped with a concentration-dependent pond adjustment called DControl® by this means, we can guarantee our customers the maximum possible solvent recovery and minimize the solvent costs in this process step. This system is presented in detail in this paper."

Jan 1, 2014

By Krishna P. Sinha

An investigation was made to determine the creep behavior of oil shale at elevated temperatures. During the first phase of the investigation, work done on creep behavior of geologic materials was reviewed and triaxial creep tests on oil shale were planned. Tests at temperatures up to 250°C and axial stress up to 3000 psi were conducted at no confinement and at confining pressures equal to 1/3 and 2/3 of axial stress. Wide variations in the elastic properties as well as creep characteristics are exhibited. Creep deformation is more pronounced at elevated temperature but no definite quantitative remarks can be made regarding effect of grade of oil shale due to wide scatter and limited number of data paints. Primary creep can be described by a power law. Secondary creep seems to be an experimental function of deviatoric stress. Teritary creep was not observed within the test duration (24 hours in most tests).

Jan 1, 1983

By Klaus Tietz, Hamish Adam, John Selby, Ian Glazier, Brian Sinfield

"Room-temperature tunable diode laser (TDL) analyzers are gaining in acceptance for highly critical safety monitoring applications in a variety of industries. This paper describes the testing, evaluation and deployment of a laser-based hydrogen cyanide monitoring system at the Campbell Complex of Goldcorp’s Red Lake Gold Mines in Balmertown, Ontario, Canada.A trial, single channel installation was followed by a staged multi-channel installation. Unexpected technical issues with the multi-channel installation were addressed and resolved.INTRODUCTIONLaser-based gas detection has several advantages over existing gas detection techniques (Ballangrud, 1993; Silver, 1992; Bomse, 1995; Table 1). For practical purposes, lasers generate light at a single wavelength. Room temperature tunable diode lasers (TDL) emit light in the near infrared (NIR) part of the electro-magnetic spectrum. Many gases of interest, including HCN, NH3 and others, absorb energy in the near infrared (NIR). Each gas has a unique absorption signature, or spectrum, made up of a large number of individual “absorption lines”. A TDL can be tuned to select a single absorption line of a target gas, which does not overlap with absorption lines from any other gases. Therefore, laser gas sensing is selective and does not suffer from interference from other gases. The single-wavelength nature of laser light also means that laser gas analysers have a linear response over a wide dynamic range.Tunable Diode Lasers (TDL) generate only a few mW of power. However, all this power is concentrated at one wavelength, the wavelength where gas absorption occurs, resulting in high signal-to-noise ratios and short response times, typically of about 1 or 2 seconds (Ballangrud, 1993). This also means that long path lengths can be used, enabling accurate measurements of very low concentrations, even with weakly absorbing gases. Tunable Diode Lasers provide all the advantages of other semiconductor devices: they are small, solid-state devices, operate at room temperature, and have long-term reliability (over 15 years). Currently, they can be obtained for any wavelength throughout the NIR (700nm to 2000nm). Because many gases absorb in the NIR, the technique is widely applicable."

Jan 1, 2011

By Dennis S. Kostick

Salt is a universal mineral commodity used by virtually every person in the world. Although a very common mineral today, at one time, it was considered as precious as gold in certain cultures. This study traces the material flow of salt from its origin through the postconsumer phase of usage. The final disposition of salt in the estimated 14,000 different uses, grouped into several macrocategories, is traced from the dispersive loss of salt into the environment to the ultimate disposal of salt-base products into the waste stream after consumption. The base year for this study is 1990, in which an estimated 196 million short tons of municipal solid waste was discarded by the U.S. population. Approximately three-fourths of domestic salt consumed is released to the environment and unrecovered while about one-fourth is discharged to landfills and incinerators as products derived from salt. Cumulative historical domestic production, trade, and consumption data have been compiled to illustrate the long-term trends within the U.S. salt industry and the cumulative contribution that highway deicing salt has had on the environment.

Jan 1, 1993

Lime-enhanced carbothermic reduction may provide an alternative process for treating low grade chalcopyrite concentrates. To date, most research on lime-enhanced reduction has been on pure, synthetic sulfides. In this study, preliminary experiments were carried out on natural chalcopyrite using a thermal analysis system to assess the rate and extent of reaction at several temperatures and identify the major solid and gaseous reaction products. Calculations were performed to establish the thermodynamic limits of the reactions in the temperature range of interest in order to identify the potential conditions for processing chalcopyrite concentrate. The study found that finely ground chalcopyrite can be reduced carbothermically in the presence of lime at moderate temperatures and in a reasonable time to form metallic copper, with the sulphur reporting virtually entirely to calcium sulfide. At temperatures below about 750?770ºC calcium ferrite is the stable form of iron whereas at higher temperatures metallic iron is stable. Further work is required to demonstrate the reaction on a scale to obtain sufficient sample for evaluation of subsequent processing steps to remove the gangue material and iron products from the copper.

Jan 1, 2009

By Patrick A. Hamilton

This Bureau of Mines report delineates the coal reserve base of anthracite, bituminous and subbituminous coals, and lignite, by mining method and sulfur content, for coal-bearing States west of the Mississippi River. The parameters used to establish the reserve base definition are the result of a joint agreement by the Federal Bureau of Mines and the U.S. Geological Survey. The reserve base of low-sulfur coal, =10 percent sulfur, is 167,324.5 million tons; medium-sulfur coal, 1.1-3.0 percent sulfur, is 37,531.5 million tons; and high-sulfur coal, >3.0 percent sulfur, is 11,244.1 million tons. The reserve base of coal with an unknown sulfur level is 18,323.0 million tons. The percentages of deep and strippable coal are 56 percent and 44 percent, respectively. The basis for reserve base estimates and analytical data for this report was the Fuels Availability System, a Bureau of Mines data bank containing numerous data tin fossil fuels. Information contained in the system was obtained from publications of the Bureau of Mines, U.S. Geological Survey, State agencies, private publications, and company data.

Jan 1, 1975

By A. M. Kiwior

In 1969, the Congress of the United States declared that "the first priority and concern of all in the mining industry must be the health and safety of its most precious resource - the miner," Therefore, Public Law 91-173, Federal Coal Mine Health and Safety Act of 1969, was enacted. Since haulage accidents account for a high percentage of coal mining accidents, Section 314e, ?Hoisting and Mantrips,? was included in the law. This section states: "Each locomotive and haulage car used in an underground coal mine shall be equipped with automatic brakes, when space permits. Where space does not permit automatic brakes, locomotive and haulage cars shall be subject to speed reduction gear, or similar devices approved by the Secretary which are designed to stop the locomotive and haulage cars with the proper margin of safety."

Jan 1, 1975

By Edward Hall Smith

The E1 Indio Mine is located in the Andes mountains about 180 kilometers East of La Serena, capital of the Fourth Region of Chile. It is reached by an international highway running up the Elqui Valley as far as Juntas from where the last 42 kilometers is on a road constructed by the Company. The plant is located at 3.900 meters above sea level among extremely rugged terrain with nearby mountains rising about 5.500 meters. Climatic conditions at these altitudes are severe with winter temperatures down to -20°C. Snow storms lasting several days and leaving up to two meters of snow have been experienced, while fierce winds are corm=.

Jan 1, 1984

By Scott Martin

This paper will discuss the challenges currently facing the mining industry. By sharing experiences gained in the CIM Leading in Mining Course, I will highlight what’s working, what’s not, what are the challenges, what are the concerns, what are the opportunities, what needs to happen. Specifically, I will discuss what is currently happening with leadership and leadership development in members’ own organizations, what skill sets are important to develop in different hierarchical groups and how comprehensive leadership courses like the leading in Mining course can help improve leadership within individuals and the industry. Leadership development is a process not an event.

Jan 1, 2014

By Lachezar Tsotsorkov

Corporate social responsibility Is a principal trend of the corporate strategy for sustainable development of Assarel-Medet JSC ? the largest Bulgarian company for open pit mining and ore processing the production activities of which date back to 1964. Sustainable development Social responsibility is considered as one of the three pillars for sustainable development, together with the economic and environmental responsibility.

Aug 1, 2013

Nuclear power currently produces about 20% of the electricity in the US, with 104 nuclear power plants located in 31 states. The commercial US nuclear industry contributes over $4 billion annually to US workers in salaries and wages. 25,000 new jobs need to be filled in the next 5 years. There are over 30 new power plants under consideration by US utilities. The operating reactors use uranium oxide fuel enriched to about 4% U235 and fission is the process used to generate heat to form steam to drive the turbine generators. Nuclear energy is an important element in the US generation portfolio and represents the largest producer of nearly emission-free electricity. Most, if not all, of the operating plants will secure an extended 20 years of operation or more. The last plant constructed was ordered in 1978. New smaller, modular reactors are under design to provide less expensive, expandable generation options.

Jan 1, 2011