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By M. A. Islam, H. Mischo, G. Barakos

Among the thirty-five declared critical raw materials (CRM) in the United States, there is no sustainable domestic production for the fourteen of them, while for some others domestic supply does not meet the national demand. Numerous potential critical raw material projects are in advanced exploration stages. However, the price uncertainties for many of these commodities put feasible future production into question and come into contrast with overly optimistic price forecasts published in all feasibility studies related to such exploration projects. Thus, in this work, a newly developed smart computational tool is used to evaluate the real perspectives of several CRM exploration projects implementing actual commodity prices, and to conduct reverse calculations in order to find the prices at which each project can be viable.

Mar 2, 2022

By B. Arvidson

Computer-controlled machine sorting may, if properly applied, have a dramatic effect on overall economics of a mine operation. Radiometric and photometric sorters have been used for many years and new developments will be reported, such as a sorter for fine particles and a conductivity/magnetic sorter. Application examples with emphasis on precious metals will be given. Economics for some of the projects will be reviewed and discussed. Sorting underground is shown to be particularly attractive, but machine sorting would be profitable in most cases based on savings in transportation and milling/beneficiation costs only.

Jan 1, 1987

By R. L. Virta

Four companies ? H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co., and Unimin Corp. ? mined ball clay in four states in 2013. On the basis of preliminary data, production was 1 Mt (1.1 million st) with an estimated value of $47 million. Production increased by 3 percent in tonnage from 973 kt (1.1 million st) with a value of $45.1 million in 2012. Tennessee was the leading producer accounting for 64 percent of domestic production, followed by Texas, Mississippi and Kentucky. About 67 percent of total ball clay production was airfloat, 22 percent was crude or shredded and 11 percent was water-slurried.

By James Corcoran, Richard McLane, Joseph DeMello, Eric Carlson, Hans van de Vrugt

The Los Angeles County Transportation Authority’s Purple Line Extension Phase 1 is a $3.12 billion (USD) design-build, underground heavy rail project, connecting an existing station at Wilshire Boulevard and Western Avenue and extending west 3.92 miles under Wilshire Boulevard and terminating approximately 550 feet west of Wilshire/La Cienega Station. The project alignment runs through the heart of the world famous La Brea Tar Pits and one of the world’s largest urban oil elds. This paper presents a case history of the planning, design, and construction efforts to achieve successful construction of the bored tunnels through Reach 3 of the alignment. Further, this paper outlines the proactive partnership between the owner, Los Angeles County Metro (Metro), the Design Builder, Skanska-Traylor-Shea oint enture (STS), and Southwest Geophysics who provided the geophysical services. Specically, the project included background review of historic site data (e.g., oil eld maps, building foundation plans, historic aerial photographs, etc.), geophysical demonstration testing to ascertain the capability of borehole magnetics to detect oil wells, directional drilling of thousands of feet of horizontal and vertical boreholes, collection of high resolution magnetic gradiometer data along vertically and horizontally cased boreholes as well as the collection of surface magnetometer data, discovery (“ground truthing”) of detected geophysical anomalies, and abatement of potential obstructions within the tunnel alignment.

Jun 23, 2024

By Donald Towse

Geothermal heat might become an important fuel for several reasons: (1) To substitute for other scarce and critical fuels. (2) Because it may be less costly to the user than alternate fuels. (3) Because its production may be more profitable than production of other fuels. (4) Or for a number of other more or less non-economic reasons such as convenience or because of less environmental impact. In competition with conventional and other non-conventional fuels, geothermal heat must score well on one or more of those points. This study first considers projections of energy needs in several United States economic sectors and the technical possibility of geothermal heat substituting for other fuels in those sectors. Then, reported and projected costs of energy from geothermal heat are compared with costs of other fuels to show the relative costs of fuels in several economic sectors. Relative costs are reported from a sample of real and hypothetical geothermal projects. The actual cost of energy will vary with each application and the particular circumstances of each geographic location.

Jan 1, 1975

By Robert L. Zook

Coal refuse slurry impoundments are dams constructed of coarse coal refuse to impound fine refuse (slurry) and water (25-30% solids). Both products are waste from coal preparation plants. A number of these structures in West Virginia, Pennsylvania and Kentucky were investigated to determine embankment stability. During the investigation a variety of embankment designs were encountered. The investigation determined the soil and geological characteristics of the embankments and the sites. This was accomplished by a test drilling and monitor installation (observation wells and piezometers) program, geologic study, and large scale mapping which allowed sub-surface profiles of the embankments to be constructed. The laboratory testing program concentrated on textural classification of the coal refuse, permeability and determining strength parameters to be utilized in the stability analyses. For the stability analyses, the Modified Fellinius Slip Circle, Simplified Bishop Slip Circle and Analysis for Translational Failure -were utilized. In all stability analyses hydrostatic pressure and earthquake were considered. This investigation indicated that 62% of the embankments analyzed are in a stable condition. The coal seam mined, the type of roof rock, and the gradation of the refuse influence the degree of compaction obtainable and the permeability of refuse. The shear strength of coal refuse appears to be controlled by its composition, moisture content, degree of compaction, amount and grain size of fines present. This investigation demonstrated these em¬bankments should not be treated as pure state-of-the-art dams; consideration must be given to the particular properties of coal refuse and the total refuse disposal system. Refuse dim slurry impoundments generally lack the site se- lection phase that is standard practice with siting most other types of dams.

Jan 1, 1974

Previous models describing the aggregation of polymer coated particles fail to take into account the fact that there are a limited number of sites onto which a polymer segment can adsorb, called ?active? sites. Thus, the collision efficiency is a factor not only of the fractional surface coverage, but also of the number of active sites. In this study, a physical model of the flocculation system was devised in which the number of these sites could be varied, in order to study the effect on particle aggregation.

Jan 1, 1987

By K. K. Bhattacharyya

Vast deposits of lignite occur in the Gulf Coast states and northern plain states. Lignite resources are cited to be over 43 billion tons in the Gulf Coast states. An additional resource of 16 billion tons are reported in North Dakota (Jackson, Smith, 1981). All lignite in the U.S. is mined at present by the open pit method. Draglines and scrapers are primarily used to remove the overburden. Bucket-wheel excavators are also being considered for new mines in the planning stages. Lignite seams are mined using front-end loaders, shovels and trucks, or Easi-miners. The depositional environment of lignite is weak sedimentary soils and rock. Ground water is often encountered within the mining depth. Surface water resulting from heavy rainfall or snow melt contributes to the problems of mining. Mining depths of up to 60 m (200 ft) are under consideration. Draglines exert additional loads on the highwalls and spoil piles. The combination of any number of these factors may cause instability of the slopes. Bearing pressure, trafficability, and settlement can also be a problem for excavation and loading equipment.

Jan 1, 1982

By M. E. Buzon, M. E. Gunter

Talc has been the focus of recent civil litigation based on claims that asbestos minerals exist in talc deposits and therefore have caused asbestos-related diseases in those who have regularly used talc products. Such litigation, and ensuing confusion over the petrology and asbestos content of these deposits, challenges the talc mining industry in Montana and elsewhere in the world. The talc deposits in southwest Montana were formed by hydrothermal alteration of dolomitic marbles and are still actively mined. In general, talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic and lacking in amphiboles. This paper includes data from analyses of representative ore samples from this mining region in southwest Montana. The results conclude that the presence of asbestos minerals — both amphiboles and chrysotile — is unlikely and that the ores are nearly monomineralic, as expected. Samples were characterized using a suite of analytical methods, namely, powder X-ray diffraction, X-ray fluorescence spectroscopy and electron microprobe analyses, which allowed us to determine the minerals present and the formation process. Our data and interpretations suggest that previous identification of asbestos minerals in these deposits is not accurate.

Jan 1, 2018

By M. E. Buzon, M. E. Gunter

Talc has been the focus of recent civil litigation based on claims that asbestos minerals exist in talc deposits and therefore have caused asbestos-related diseases in those who have regularly used talc products. Such litigation, and ensuing confusion over the petrology and asbestos content of these deposits, challenges the talc mining industry in Montana and elsewhere in the world. The talc deposits in southwest Montana were formed by hydrothermal alteration of dolomitic marbles and are still actively mined. In general, talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic and lacking in amphiboles. This paper includes data from analyses of representative ore samples from this mining region in southwest Montana. The results conclude that the presence of asbestos minerals — both amphiboles and chrysotile — is unlikely and that the ores are nearly monomineralic, as expected. Samples were characterized using a suite of analytical methods, namely, powder X-ray diffraction, X-ray fluorescence spectroscopy and electron microprobe analyses, which allowed us to determine the minerals present and the formation process. Our data and interpretations suggest that previous identification of asbestos minerals in these deposits is not accurate.

Jan 1, 2017

By Montaser S. El‑Salmawy, AHMED A. S. SEIFELNASSR, Ahmed Al‑Abady, Abdeaziem M. Abdelaal, Amr F. M. Ibrahim

Iron is a key detrimental impurity in silica sands that determines their contribution to high-technology industries. Herein, a simple ecologically sound approach is investigated for iron removal from a silica sand sample obtained from the El-Zaafarana area-Egypt. The sample was subjected to a detailed microscopic mineralogical study supported by XRD and XRF characterization. The sample was beneficiated using distilled water attrition scrubbing and screening over a 25 μm sieve followed by leaching using a mixture of equal amounts of phosphoric and oxalic acids. Leaching experiments were designed and analyzed using the Box-Behnken design (BBD) methodology. A model was developed and evaluated using the analysis of variance technique to map the relationship between the residual iron oxide in the produced concentrate and selected variables such as leaching temperature, oxalic acid, and phosphoric acid concentrations. XRD and mineralogical analysis reveal that quartz is the most dominant constituent of the studied sand and other minerals such as kaolinite, iron oxide, rutile, and zircon exist in trace amounts. The head sample shows a silica and iron oxide content of 95.69% and 2379 ppm, respectively. Attrition and separation over a 25 μm sieve increase the silica content to 97.05% and decreases the residual iron oxide to 455 ppm. The final product after leaching under optimized conditions shows 99.82% silica and 55 ppm iron oxide.

Aug 30, 2022

By Dermot M. Winters, Brent T. Wahlquist, C. Y. Chen

The enactment of the Surface Mining Control and Reclamation Act (SMCRA) in August 1977 addressed subsidence resulting from underground mines, in addition to creating the requirements for reclamation of surface coal mines. Subsidence control regulations pursuant to SMCRA were initially promulgated in March 1979. Several revisions have since been made. In addition, due to court challenges some regulations have been remanded and others are still on appeal. In the meantime the Secretary has agreed to initiate rulemaking on some issues. It is yet to be determined how the prohibition of certain areas from surface coal mining operations under Section 522(e) of the Act applies to subsidence. This presentation discusses the status of the regulations and issues related to or affecting the subsidence regulations.

Jan 1, 1986

By M. William Lallman

Potash production from natural brines of the Bonneville Salt Flats has a comparatively long history dating back to the start of World War I. However, it vas sot until the late 1930's that a successful commercial potash operation was achieved by a firm known as Bonneville Ltd. While improvements in operating techniques, pond design and equipment have been incorporated as they became available it should he understood that the basic technology developed in the late 30's and early 1940's by Bonneville Ltd, for potash production has not been changed significantly. The purpose of this paper is to present a brief review of the history, geology and hydrology of the Bonneville Potash operations and discuss the cur¬rent methods employed for brine collection, solar evaporation and the recovery of potash and other brine chemicals. A detailed study of the hydrogeology of the Bonneville Salt Flats wan made by L. J. Turk,1 Ph.D. thesis for Stanford University in 1969, under the auspices, of Kaiser Chemicals the Industrial Chemicals Division of Kaiser Aluminum & Chemical Corporation. Turk's thesis furnished much of the information presented in this paper.

Jan 1, 1976

By M. J. Raffaldi, K. W. Harris, K. A. Perry

"Highwall miners have been widely used to extract additional coal reserves from existing surface operations, particularly on contour operations in the Appalachian coalfields. Using a continuous miner cutting head, coal may be extracted from significant depths (such as 150 m), leaving behind an array of web and barrier pillars with the purpose of maintaining highwall stability. This method inherently involves elevated risks to both equipment and personnel due to proximity to and increased exposure time near highwalls. As a result, modern operations should actively design web and barrier pillars to maximize extraction while providing adequate stability. The ARMPS-HWM software, an empirical-based program created for the design of web and barrier pillars at highwall mining operations, is one such approach. The calculated stability factor is compared with empirically established guidelines produced from examining case histories.The ARMPS-HWM program is a handy tool for initial design, but understanding the site’s structurally significant geologic features and geomechanical behavior is important and may potentially increase extraction. We created a two-dimensional numerical model using FLAC3D and calibrated it to ensure pillar strength, closely following the Mark- Bieniawski formula for a typical range of pillar geometries and overburden properties. The development of pillar stresses along a highwall panel was then numerically investigated as mining progressed, and the stress distribution between barrier pillars was found to be asymmetric, which can result in an over-design of the closeout web pillars if tributary area loading is assumed. Finally, the importance of adequate barrier pillar stability is highlighted."

Jan 1, 2014

By M. S. Fraley

As we compete for close margins in wholesale sales, the effects of both quality and price have a major impact on the cost of producing electricity.SO2 emission allowances have traded as low as$60/ton to as high as $215/ton over the last three years. This price spread in emission allowances clearly demonstrates the correlation between the quality of fuels versus the price utilities will be willing to pay for them. This paper provides an overview of the effects of the qualities of fuel, coupled with transportation as well as environmental concerns on the price of fuel and the ability to compete in a deregulated electric market.

Jan 1, 2000

By D. M. Ziebarth

"During the mid to late 1960s, the underground potash industry in Saskatchewan was born. For the next four decades the industry operated at a steady pace, supporting a large part of the world demand, until 2008 when the potash market heightened. Operators were motivated to capitalize on this increased demand, new mines were proposed while existing mines were planning upgrades. Potash Corp. of Saskatchewan (PCS) was one of the major producers planning upgrades to its production facilities quickly, including modifying the existing headframe and shaft at the PCS Cory Site to accommodate a new 1.5-kt/h (1,650-stph) hoisting plant. Upon completion of the project, the innovative operations group continuously reviewed methods to increase production and reduce operating costs, allowing PCS to continue being competitive on the world market.BackgroundPotash production is a major Saskatchewan industry and has played a significant role in the economy for more than 40 years. Production commenced in 1962 when water problems were overcome at the International Minerals and Chemical (IMC) Mine near Esterhazy, Saskatchewan. A surge of development by other companies resulted in 12 companies opening 10 mines by 1970. In 1975, Potash Corp. of Saskatchewan was created by the government of Saskatchewan, and shortly thereafter purchased several mines in Saskatchewan, including the Cory Mine, near Saskatoon.Cory has been in operation since 1968 and is located 12 km (7.5 miles) west of Saskatoon in central Saskatchewan. The mine is located in the center of the world’s largest potash deposit, 1,000 m (3,300 ft) below surface.PCS has embarked on sizable capital expansions of more than CDN$7 billion.The $1.6-billion Cory expansion was expected to raise operational capability of the site to 2.7 Mt/a (3 million stpy), an increase of 1.9 Mt/a (2.1 million stpy). To achieve 2.7 Mt/a (3 million stpy) of finished product and considering the 22.6 percent average production recovery (Potash Corp, 2013), 12 Mt/a (13.2 million stpy) of ore must be hoisted to the surface for processing. To deliver this rate required upgrading of the hoisting plant to 1.5 kt/h (1,650 stph). To accomplish this ambitious challenge, creative thinking, careful planning and a cohesive team was needed to work together to ensure the schedule, budget and most importantly that the work was completed safely (Potash Corp., 2013)."

Apr 1, 2017

By Qingqing Huang, Mohammad Rezaee

The Mineral & Metallurgical Processing Division (MPD) of the Society for Mining, Metallurgy & Exploration held the 12th MPD Student Poster Contest on March 2, 2022, during the MINEXCHANGE 2022 SME Annual Conference & Expo. The event showcased the work of 32 graduate and undergraduate students from U.S. and international institutions. The contest began in January when the students submitted one‐page abstracts for judging. In February, they prepared and presented posters that explained their research, and each student had five minutes to explain their research to a panel of judges during the conference. Recognizing the students’ efforts in working hard on their research topics and setting aside time to complete the necessary steps to enter the poster contest, the MPD provides monetary rewards to all participants. For graduate students, first place receives $1,000, second place $500, and third through seventh places $200 each, and for undergraduate students, first place receives $1,000 and second place $500. The main authors of nonplacing entries receive $125 each. Participation in the contest includes a free ticket to the MPD Luncheon, where the winners are announced.

Nov 22, 2022

By W. Miles

Introduction From a historical perspective, bentonite is the common rock term for various uses and applications. Its name originates from water-based muds near Fort Benton used for lubrication of wagon wheels during the 19th century migration to western territories (which are presently part of the United States) when the pioneers ran out of axle grease. From a clay mineralogy perspective, bentonite is composed primarily of montmorillonite, an expandable magnesium aluminum silicate clay mineral. When magnesium occupies an octahedral structural site that usually contains an aluminum atom, a negative charge is created. In order to neutralize negative charges, cations are drawn to the interlayer surfaces between clay mineral sheet structures. Modern applications for bentonite depend on the sodium or calcium cation populations and other characteristics of the clay mineral. When sodium is the dominant cation, the material is also called sodium bentonite, also known as swelling bentonite, western bentonite or Wyoming bentonite. When calcium or magnesium is the dominant cation, the material is called calcium bentonite, also known as nonswelling bentonite or southern bentonite. Swelling bentonite is recognized for its rapid hydration of interlayer sodium and subsequent dramatic expansion up to more than 20 times its original volume. Low shear can then disperse the hydrated sodium bentonite to form suspensions that increase viscosity and suspend solids. However, when shear is subsequently eliminated a sodium bentonite slurry gels. Characteristically, nonswelling calcium bentonite has relatively poor hydration properties and thus low expansion of the clay mineral. When subjected to low shear, calcium bentonite exhibits very little viscosity and poor suspension. Additionally, when shear is subsequently eliminated no more than minimal gelling takes place. The domestic and export markets related to both swelling and nonswelling bentonite are discussed below.

Jan 1, 2007

By Donald P. Richards

Is a shaft the same as a tunnel and can it be approached in the same manner for design and construction? The most obvious difference between a shaft and a tunnel is that of orientation; whereas a tunnel is commonly near horizontal or slightly dipping, a shaft is commonly vertical or steeply inclined. As a result, design and construction methods employed for tunneling, in general, cannot be directly applied to shafts, although some of the basic concepts of behavior are quite similar. Many of the shafts that have been sunk in various parts of the world are owned by private mining companies. Each company has generally accumulated years of experience in shaft sinking and mining techniques pertinent to its particular geographic location. When a new shaft is to be sunk or an existing shaft deepened, the tendency often seems to be to continue to use the methods that have been used successfully in the past.

Jan 1, 1979

By JÖRG DEHNERT, PETER WINDISCH, Bernd Schönherrt, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposures of miners in Germany, especially during remediation work in old mines. The QESS is a light-weight, modular, and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil, and expanding foam. It is designed to seal off radon-rich parts of galleries within only a few minutes. Originally, the QESS was developed to protect miners against radon exposures. Then, the QESS found the attention of several mine rescue teams at a German mining conference. The Student Mine Rescue of the Technical University Bergakademie Freiberg and the Wismut Mine Rescue carried out firstmine rescue drills in Freiberg and Schlema. Additionally, a mine rescue drill was carried out by the Front Range Mine Rescue in the Edgar Experimental Mine of the Colorado School of Mines. These drills helped to improve the systemand highlighted its potential for mine rescue operations. Now, the QESS is wellsuited for small-scale mining. The QESS can be used to seal off galleries in only a few minutes to both protect miners fromradon exposures and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.

Jul 23, 2020