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By Taghi Sharizadeh, MAURICE SUNKPAL, ELAHEH TALEBI, PEDRAM ROGHANCHI

Excessive heat exposure is among the health and safety hazards that have adverse effects on the mine workers. The very nature of the underground climate makes it a convenient avenue for heat generation and accumulation from several heat sources including autocompression, equipment, and heat from strata. This study investigated the effects of clothing insulation and acclimation on the thermal comfort ofmineworkers who are exposed to heat in underground working environments. Several clothing ensembles have been considered to analyze the effect of the thermal resistance of clothing on the thermal comfort of workers. To investigate the impact of the clothing insulation, the thermal comfort limit of an underground miner was calculated in the form of maximum allowable exposure time for an 8-h shift. Parametric analyses were subsequently performed using an already developed thermal comfort model using MATLAB software. The results demonstrate that clothing insulation has a significant effect on the thermal comfort of mine workers. Increase in the clothing insulation decreases the maximum allowable exposure time of mine workers. This is especially true for the new and non-acclimated workers. Since acclimatized workers can tolerate a higher level of the dehydration and are capable of losing more water by sweat per shift, the maximum allowable exposure time for the acclimated workers are higher than non-acclimated workers. These analyses have shown that acclimated workers can have more continuous work per shift compared with non-acclimated workers. For example, in an environmental condition with clothing that a nonacclimated worker cannot work more than 5 h, an acclimated worker can work a full 8-h shift.

Jun 29, 2020

By F. Ansheng

Though it becomes increasingly important with the valuable minerals in their deposits tending to be fine and poor, the solid and liquid separation remains difficult especially when the particles are of micrometer size and of low density. Almost of all conventional thickeners result in that fine particles lose into overflows which often costitutes a loss of potentially valuable resources as well as an environmental hazard. The addition of flocculations may improve the settling of solids but may also not work well for the final removal of fine particles from the overflows (Ref.1).

Jan 1, 1990

By J. Kalliokoski

As part of a funded project we have completed a comparative literature survey of the US regional Proterozoic geology. For our com¬parative study model we used the geological settings of the very large pitchblende deposits in Saskatchewan, Canada and the Northern Terri¬tory of Australia. These occur in a variety of Archean and Lower Proterozoic host rocks, at and below a regional unconformity that is capped by subhorizontal Middle to Upper Proterozoic conti¬nental sedimentary rocks. We find that there have been recorded in some parts of the US similar unconformable sequences of Middle to Upper Proterozoic continental sedimentary rocks that overlie older basement rocks.

Jan 1, 1979

By K. S. Gritton

The U.S. Bureau of Mines has investigated methods for extracting metals from a variety of arsenic-containing smelter flue dusts. One proposed flowsheet includes a sulfuric acid leach, a cooling step to precipitate hydrated copper sulfate, and a reduction-precipitation of As2O3. Arsenic extractions greater than 90 pct were achieved, while copper extraction ranged from 50 to 85 pct under the conditions examined. Copper was removed from the leach solutions by crystallization followed by SO2 precipitation of arsenic which resulted in a 98 to 99.9 pct As2O3 product. Other metals, such as lead and zinc, were concentrated in the leach residue or in other byproduct streams for recovery of their valuable metal contents.

Jan 1, 1990

By R. R. Unterberger

This paper addresses the problem of seeing into rock. We will consider two methods, first to use radar, or electromagnetic wave pulses, to probe into rock ahead of mining and second to use sonar, or sound wave pulses, to probe into rock. Both are non destructive and capable of giving information on hazards ahead of mining. Such hazards might be a borehole full of water possibly leading to a high pressure aquifer somewhere above the mine level, changes in rock type, or the edge or top of a salt dome. Most of the work described in this paper deals with probing through rock salt which we have done successfully to over 2000 meters maximum range. We discuss first the radar probing and then the sonar probing. RADAR PROBING OF ROCK SALT Theory All electrodynamics are based on Maxwell's equations, which are in vector form [D = P (1) •B = 0 (2) aB V x E _ -(3) at aD •x H = J + - (4) at] where D and E are the electric displacement and electric field intensity vectors respectively, B is the magnetic induction or flux density

Jan 1, 1979

By W. M. Cross

The hydrophobic character of sapphire surfaces in SDS solutions was examined with respect to the aggregative nature of the adsorbed surfactant phase. It was found that, at equilibrium, sapphire surfaces having adsorbed SDS bi-layers exhibited no contact angle. Conversely, when the adsorbed SDS was found to be mi-cellar in nature, sapphire surfaces developed significant hydrophobic character. The surface states as detected by Fr -IRIIRS conformational analysis were found to be reversible with temperature. The variation in adsorption density with temperature was studied by in situ Fr-IRIIRS. The isosteric heat of adsorption was calculated to be -1.6 kcal/mole. Although the adsorbed SDS was found to undergo a reversible phase change between 25 and 32°C, similar to SDS in solution, the extent of adsorption was not reversible with temperature.

Jan 1, 1993

By John Hardy

The performance of five dense-medium washers was evaluated in four preparation plants. Three of the plants were making a two-product separation that produced a clean coal and a refuse; one plant employed dense-medium vessels in series to effect a primary and a secondary separation. The secondary drum-type washer produced a low-ash metallurgical coal and an intermediate-ash product suitable for plant fuel or steam generation. The sharpness-of-separation was excellent for all four primary separations and the secondary separation.

Jan 1, 1966

By Dolf Vos

The balling section of the pelletizing plant at Hoogovens IJmuiden consists of 7 balling drums. Each with an average capacity of 100 tons of green pellets per hour. The balling drums are equipped with rotating scrapers and water-spraying systems. The scrapers are installed in order to restrict the growth of the race to a certain thickness. The spraying system is used to adjust the desired value of the moisture-content of the rewetted ground ore, the pellets and the race. The desired value is the value by which the balling- process is stable, good pellets are formed and surge occurs within certain limits. In October 1980 the construction of one of the balling drums has been modified. The rotating scraper was removed and the inner wall of the drum was supplied with a rubber-lining. In 1982 a second balling drum has been rubber- lined. At the same time the Tyler vibrating screen of this balling circuit has been replaced by a roller(bed)screen. By the end of 1983 all 7 balling circuits will be equipped with rubber-lined drums in combination with roller(bed)screens. The combination of these two modifications will improve the quality and the screen analysis of the green pellets, moreover resulting in savings on energy- and maintenance costs. This paper describes the influence of a rubber- lining on the balling process and the green pellet quality by carrying out in-plant testruns in November/December 1980. The testrun results have been compared with the results of a not modified balling drum.

Jan 1, 1983

By William A. Riggs

Salt, a non-metallic mineral whose use dates back to earliest history of mankind, and whose uses cover the widest range for any mineral raw material, is generally of widespread occurrence in commercially recoverable quantities in the oceans, in certain sedimentary rocks, in certain lakes, and in certain underground waters. Passing over geological detail, it may be said that, generally, all of the salt in the world has, at least once in geological history, been in solution in the oceans. The total salt content of today's oceans, said to equal 4.5 million cubic miles of rock salt, dwarfs the tremendous volume of salt in the sedimentary rocks. In 1958, United States production of salt was about 22 million net tons and world production about 82 million. About 3 percent of United States production is table salt, with chemical, municipal, industrial and agricultural uses taking the remainder. Mississippi River. Figure 1 has been expanded sufficiently to show also those salt occurrences and producing points which might economically ship salt into these states. Although widespread in occurrence, salt deposits and possible production areas generally show very sharp local boundaries. Salt-for non-table use is susceptible to ?place value?, a common problem in low valued raw materials, where transportation costs often exceed the value of the material f.o.b. the production point. Generally only large capacity mechanized salt producing operations can compete in United States markets, as contrasted to the many small local salt evaporators in less industrialized Mexico.

Jan 1, 1962

By Frank Agyemang, Zainab Nasrullah, Richard LaDouceur, Mehran Saddat

To sustain the circular economy, defence applications, and other renewable technologies, recycling rare earth elements (REEs) and other critical elements from their secondary resources is important. This cause has resulted in rigorous research and development for viable extraction and separation of REEs. Previously, Sm-Co recycling has been done with technologies, which fall under the categories of pyrometallurgy, physical separation, and hydrometallurgy. All these methods have limitations associated with energy, cost, and environment. Reportedly, the chemical leaching technology has successfully recovered and separated Sm-Co. Still, it has limitations associated with slow mass transfer and leaching kinetics, and there is a need to intensify the process to make it time efficient. This approach has also adversely impacted the environment by an extensive use of toxic, corrosive, non-selective, and expensive reagents. In this research study, chemical leaching of Sm-Co was performed using this new class of solvents, Deep Eutectic Solvents (DESs), which fall under the category of ion metallurgy. Four different DESs were used, proven to be green, non-toxic, biodegradable, cheap, and selective for cobalt over samarium by 82% leaching conversion. To improve the slow mass transfer and leaching time, this new technology of resonant vibratory mixing (RVM) was also tested. RVM intensifies mixing by establishing near instantaneous, low energy mixing conditions through resonance. It has been shown to improve the adsorption kinetics and was tested for the leaching kinetics. Four combinations of DESs were prepared, which are made up of two quaternary salts: Choline Chloride and Tetra Butyl Ammonium Chloride, and three organic compounds: Oxalic Acid, Urea, and Ethylene Glycol. These combinations were used for chemical leaching of Sm-Co with leaching factors of time, temperature, and type of DESs. After leaching, the samples were tested with and without resonant vibratory mixing with conditions of time, intensity (%), and type of DESs. Samples were analysed with Induced Coupled Plasma - Optical Spectroscopy (ICP - OES). Future work will involve a life-cycle assessment to assess the RVM technology with other conventional mixers, and an extensive study of DES properties to improve selective leaching.

Feb 1, 2025

By Brenton Cook, Nate Long, Larry Applegate, Aaron K. McCain

"The Northgate Link Extension project is the third phase of the Sound Transit master plan to extend light rail throughout the greater Seattle metropolitan area. When completed, the Northgate Link Extension will extend the existing light rail system north by about 7 km (4.3 miles) from the University of Washington to the Northgate neighborhood. A general overview of the project alignment is provided as Fig. 1. The project was funded by a combination of federal grants and allocations from local taxes. The general contractor on the project was JCM Northlink LLC (JCM), a joint venture between Jay Dee Contractors, Frank Coluccio Construction Company and Michels Corp. SoilFreeze, Inc. was retained as a subcontractor to provide ground freezing design and construction services.The project involved the construction of two parallel 5.5-m, 25-cm (18-ft, 10-in.) (inside) diameter tunnels using earth pressure balance (EPB) tunnel boring machines (TBM) and precast segmental concrete tunnel liners. The two tunnels maintained roughly the same elevation along the alignment and were spaced roughly 12 m (40 ft) apart (centerline to centerline). A total of 23 cross-passages connecting the two tunnels were included at approximate 244-m (800-ft) intervals. Cross passage excavations were elliptical in shape with dimensions of approximately 5.6 m (18.5 ft) in height and 5.3 m (17 ft) in width. The cross-passages were 5.8 to 6.1 m (19 to 20 ft) long as measured between the exterior of the tunnels at springline elevation. Cross passages were intentionally located directly beneath public right-of-ways thus avoiding buildings. Many of the cross passages were located beneath narrow roads in residential neighborhoods with mature vegetation, existing utility structures and piping and limited parking areas. Excavation and support for each cross passage was completed using the sequential excavation method (SEM).The subsurface soil and ground water conditions at the cross-passage locations were described in the Northgate Link Geotechnical Baseline Report (GBR) prepared by Jacobs Associates and the Northgate Link Geotechnical Data Report (GDR) prepared by Shannon and Wilson, Inc. Soils along the project alignment were glacially overridden and characterized as very dense or hard. Subsurface soils consisted of cohesionless sand and gravel (CSG), cohesionless silt and fine sand (CSF), cohesive clay and silt (CCS) and till and till-like deposits (TLD)."

Dec 1, 2018

By J. Stawovy, A. Fourie, J. D. Quaranta

Coal refuse impoundments are disposal facilities specifically designed for the coal mining industry. Re-purposing refuse impoundments for co-disposal with natural gas flowback water and waste rock overburden has been investigated. The aims of this study were to investigate properties of coal refuse classification under the influence of co-disposed wastes as geochemical material exposure pathways from hydraulically exposed sodium and calcium ( Na+, Ca2+) cation loading from disposal of flowback water produced during the development of horizontal drilled natural shale gas frack wells, and waste rock having limestone characteristics. The geotechnical index classification of saturated cohesionless refuse is required to evaluate the liquefaction potential for strain or strength loss contributing to ground movements. This study is relevant to identifying changes in the coal refuse geotechnical index classification as sand-like, clay-like, or a borderline transitional material from the effects of ion and waste exposure in the impoundment’s reservoir porewater. Laboratory geotechnical tests were performed on fine coal refuse blended with different cations to classify the altered plastic behavior and index classification. Following determination of the index classification, the specimen’s stress–strain responses were investigated through isotropically consolidated undrained (ICU) triaxial compression tests. This experimental study culminated with two salient findings: the first is that introduction of ions alone into the refuse tailings or impoundment porewater resulted in significant material changes in property index classification, and the second finding was that the difference in refuse index classification did not correlate into noticeable effects of the monotonic undrained triaxial strength parameters.

Jul 5, 2022

By R. L. Wiegel

Some of the mineral deposits that are being processed today, and especially those expected to be processed in the future, have relatively low compositions of the valuable mineral. With these low-grade ores, it is necessary to be able to design processes that are sufficiently low-cost to permit exploitation. One approach to minimizing the capital and operating costs for these processes is to use the capabilities of computer process simulation in the design phase of development, to make important technical and economic decisions regarding the evaluation of alternative process flow schemes, the selection of equipment and the choice of operating conditions. There are mathematical simulation models for most mineral processing operations, including several each for size reduction, size classification and mineral separations. To be able to tie these individual operating models together in an integrated mineral process simulation, however, it is important, in fact in some cases essential, that there be a model which describes how the mineral system responds to size reduction in making the liberated valuable and waste mineral particles available for concentration or rejection operations and the locked particles available for possible recirculation. This, then, is the role played by the mineral liberation model, showing the relationship between particle size, quantity and composition throughout the process.

Jan 1, 2011

By Timothy C. Smith, S. Andrew Jacobs, Douglas E. Gonzales, Sandy J. Schexnailder, Carl Urban

At the Schwartzwalder Mine (Cotter Corporation, Golden, Colorado) ion exchange resins have been used in mine water treatment experiments. The experiments, initiated in October 1979 and currently in progress, demonstrate that mine water uranium values can be reduced to levels as low as 10 ppb. Duolite® A-101D, a strongly basic anion exchange resin, was tested in laboratory-scale columns (1 inch diameter) initially and then in pilot-scale columns (4 inch diameter), using both co-current and counter-current operational modes. Observations and conclusions resulting from these studies can be summarized as follows: (1) Duolite® A-101D appears to have successfully extracted uranium at influent levels of approximately 2.0 ppm over multiple loading and elution cycles, consistently producing effluent concentrations as low as 10 ppb uranium. (2) Based upon present test data, counter-current regeneration appears to be the key to successful operation. Upflow loading and downflow elution are the preferred modes for service and regeneration, respectively. (3) Filtration is a necessary pretreatment to remove fine clay and inorganic precipitates that will foul the resin, causing excessive pressure drop and poor loading and elution kinetics. (4) This waste treatment application is unique in that it offers the opportunity to recover some or all of the capital investment in the treatment facility

Jan 1, 1980

By William C. Peters

The frustration encountered by exploration crews in connection with land acquisition could be graphed to show a correlation with the natural law that everything tends to become more so. Figure I shows a rather common, situation. The combinations of ingredients are almost limitless and the resulting brew is often poisonous to an exploration man. A single step, that of taking a series of deep soil samples is often delayed until some sense can be made from "floating" unpatented claims which are obscure in orientation as well as position, placer claims overlapping lode claims, location posts with empty Prince Albert cans, and claims with no apparent assessment work for ten years. Add to this some patented claims with¬out monuments, a state or federal withdrawal area which may or may not invalidate pre-existing claims, a loosely defined tunnel site, and some ranchers who understandably resent the separation of surface rights from mineral rights. The picture is familiar to exploration men. One approach to such problems is to ignore them until someone voices an objection -- but then an even more chaotic situation is likely to develop. Another practice is to stake new claims to cover all ground that is "open" at first glance and then find out if there are conflicts so that the new claims can be adjusted accordingly.

Jan 1, 1970

By J. B. Malcolm

The discovery of tungsten-bearing quartz outcroppings in Vance County, N. C., by the Hamme brothers in 1942, made international news in the mining industry and was, in fact, one of the major ore discoveries made in the U.S. during the last 25 years. Operations began at the Hamme mine in 1942, but after 16 years of successful operation, the mine was closed down in 1958 under adverse market conditions. By that time, it had produced nearly 20 million lbs of metallic tungsten. Because of the square-set timber mining method then in use, mine operating expenses were high, actually representing 78% of the total operating expenses at the property. In timber work alone, 160 men were employed. Approximately 500,000 bd ft of timber were placed monthly at a direct supply cost of $1.00 per ton of ore mined. Late in 1959, following a slightly improved position in the tungsten market, company management decided that, by changing the mining method, the operation could be economically feasible. The major premise in this decision was that a reduction of from 25 to 30% of the mining costs could be achieved by the conversion of the mining method from square-sets to horizontal cut and fill. Reopening of the mine began in February 1960, Full production has now been reached and overall mine productivity has been doubled.

Jan 1, 1962

By Zainab Nasrullah, MontanaFrank Agyemang, Mehran Sadat, Richard LaDouceur

Rare earth elements (REEs) are valuable for various modern technological applications, including metallurgy, machine building, radio electronics, instrument engineering, nuclear engineering, and manufacturing. The extraction and separa-tion of rare earth elements (REEs) from their complex ores is challenging due to their distinct physical and chemical properties, contributing to their market scarcity. At present, REE recovery utilizes traditional pyro- or hydrometallurgi-cal processes. The overall process in the recovery and sepa-ration of individual elements from complex REE systems suffers from high energy demands and the use of many haz-ardous chemicals that negatively impact the environment. With the growing trend toward a circular economy aim-ing to balance sustainability, efficiency, and environmental impacts, this research is focused on using deep eutectic sol-vents (DESs): a combination of a quaternary salt: Choline Chloride and five organic acids: Oxalic Acid, Urea, and Ethylene Glycol, Lactic acid and Glycerol for the selective leaching of REEs from their complex ore which is proven to be green, selective, non-toxic, biodegradable, and cheap. The effects of different DESs and leaching time on the REE leaching efficiency were determined, and the optimum DES media were found to be Oxaline and Lactic Acid at which a leaching efficiency of 25% and 15% was achieved at 80°C respectively for cerium.

Feb 1, 2025

By E. A. Metz

Silicon dioxide, silica, is the most common oxide in the earth' s crust. The health effects of silicon dioxide dust have been known since Biblical times. Agricola's book, published in the mid 1500's on occupational medicine, described a lung disease that afflicted miners. He observed a disease in miners that caused shortness of breath, coughing and wasting. Add fever, chest pains and fatigue and we have the current symptom complex of silicosis. As we approached the 21stcentury, the Labor Department began an aggressive campaign to combat silicosis-a preventable disease. Unfortunately, many publications do not clearly differentiate the polymorphs of silica known to mineralogists. Crystalline silica, i.e., alpha quartz, tridymite and cristobalite need to be considered differently from the amorphous forms of silica. Freshly fractured surfaces of the silica and host specific responses will be examined. Recent research focuses on the biologic interactions of free radicals generated by mineral particles. This results in cell injury and DNA damage, in turn leading to fibrogenesis and possibly carcinogenesis. In addition to particle-cell interactions, emphasis is given to lung defense mechanisms.

Jan 1, 1998

By S. G. Mougiakakou

A computerized system (SCAPEVIEWER) based on landscape indices and artificial intelligence techniques is proposed in order to classify landscape images into various categories according to the quality of the pictured scenery. Photographs (totally 108) from various landscapes have been clustered, from seven experts in accordance to the mean estimation of landscape quality, into distinctive (C1), typical or common (C2), and indistinctive (C3). For each of the landscape photographs, ten (10) environmental and operational indices have been selected and determined, corresponding to visibility (V), naturalness (N), relief (R), flora quantity (FC), flora quality (F), water (W), skyline (SL), visual entities (G), season (S), and viewer position (P). These landscape indices are fed to a classifier. The classifier is a feed forward Neural Network (NN) trained by a novel hybrid method combining genetic algorithms and the back-propagation algorithm with adaptive learning rate and momentum. A total classification rate of 93.5% has been achieved, using only 8 input neurons. The discarded input neurons correspond to the indices S, and P. The pilot system SCAPEVIEVER has shown the feasibility of landscape photograph classification into three categories (C1, C2, and C3) according to the landscape quality, selecting simultaneously the most robust indices, by means of a computerized system combining the knowledge of an expert with a NN based classifier.

Jan 1, 2003

By T. Fernandez, V. Juchen, C. Petter, F. Cantini, V. Lenz, V. I. Araújo, R. Petter, R. Darrigo, A. Young, I. G. da Costa, J. Oppermann

There are many methods to estimate costs quickly. One of these is the Parametric Method, where costs are estimated from general algorithms (or curves). Derived from an original tool based on the O’Hara model, a software called MAFMINE was developed. MAFMINE is based on parametric models to estimate investment and operational costs in mining. The software itself is based on the use of a computer model known as client-server. However, the model needs new inputs from advances made by the mining industry, mainly in terms of electrification, automation, digital transformation and preconcentration to face Environmental, Social and Governance (ESG) concerns. Thus, this work was to prepare a new core module ready to incorporate the new technologies aiming to deliver operation and capital costs associated with environmental impact mitigation. The tool generates an order of magnitude estimate for CAPEX and OPEX to establish a very first Discounted Cash Flow (DCF) in a mining venture. For quick evaluations, at a preliminary level, the results are very promising.

Mar 2, 2022