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By W. H. Ode

An investigation of standard methods for determining ash in low-rank* coals showed that generally 60 to 95 percent of the total sulfur in the coal is retained in the ash as SO3. This large sulfur retention causes a positive error in the determined mount of ash of as much as 6 percentage points for the coals examined, although it usually is 2 to 3 percentage points for lignites and about 1 for subbituminous coals. Unless the sulfur content is low or unless a correction is made for the SO3 retained, the fixed carbon and oxygen have an equivalent negative error when determined by difference; also other inaccurate analytical values occur when the data are calculated on an ash- free bas is. No simple modification of the ashing procedure was found that would reduce the sulfur retention to a point where its effect on the ash determination would not be significant, Therefore, for accurate analytical work on law-rank coals, the SO3 should be deducted from the determined ash to obtain a "corrected" ash value.

Jan 1, 1962

By Martín Reyes

Iron concentration by ion flotation techniques, from sulfate solutions in presence of zinc was studied in a laboratory flotation column by continuous mode using a synthesized sand shell plate sparger, an anionic collector, promoters, and surfactant propylenglicol 400. Effects of experimental parameters, such as the concentration of reagent: potassium amyl xanthate and dithiophosphate, superficial gas velocity, and superficial liquid velocity were studied in terms of the recovery and enrichment of Fe (III). The results show that the iron elimination from the solution in the presence and absence of zinc (II) are of 59 % and 72 % respectively. The flotation efficiencies decrease with an increase of the concentration of xanthate and air flow rate. The best recovery was achieved, at Jg 0.1 cm/s, Jl 0.72 cm/s and a mixture of xanthate and dithiophosphate as promoter. It was also demonstrated that it is possible to selectively separate and concentrate iron (III) from solutions containing zinc. The behavior of iron ion flotation in a flotation column is reported in this research as a gas hold up, superficial gas velocity, bubble size and superficial bubbles area flux function. The results show that the extraction of aqueous ions of metal iron by ion flotation is strongly affected by: [C], Jg (cm/s), eg (%), Db (mm), Jl (cm/s), y Sb (s-1).

Jan 1, 2009

By E. Rigopoulos

Mining disturbs the environment, even when the ores or the minerals extracted are non-toxic. Silver & Baryte Ores Mining Co S.A (S&B) is committed to minimizing the environmental impacts of its mining activities, by implementing an integrated rehabilitation program wherever it operates. The paper discusses the principles for mining-disturbed land restoration activities on Milos Island for a successful outcome.

Jan 1, 2003

By Jochen Petersen, David G. Dixon

"Although heap leaching may be perceived as a somewhat low-tech route for the extraction of low-grade minerals, the underlying physical, chemical and biological processes are in fact extremely complex. There has been increased interest in heap leaching of sulphide minerals in recent years with the advent of controlled bio-heap leaching, and the need to mine more marginal ore deposits.A detailed investigation into the dynamics of heap leach processes has provided much insight into the underlying complexities, and has led to the development of a sophisticated modelling tool. Some of the features include mineral kinetics, particle level effects, bacterial growth, oxidation and adsorption, gas adsorption, pore diffusion, bulk advection, gas balance and heat conservation.Two case studies are presented which illustrate specific features of the model for different applications and how these have helped to identify key areas of concern. In each case the model has proved as an invaluable tool either for the improvement of existing heap leach practice or for the development and assessment of novel applications."

Jan 1, 2003

By David van Cleave, David L. Rome

Whether you buy your minicomputer from a manufacturer or another vendor, the first thing you must do is define your needs. With good planning, the initial cost will be low and your return on investment will be maximized over the long term. Involving all members of your staff who will he using the new computer in the planning phase is also important. Their participation will alleviate any potential concerns they may have about new equipment, and their suggestions will provide valuable input for your specifications. After you define your proposed system, survey available hardware and software. The survey will help you in the next step, preparation of specifications. The specifications, along with a quote request, are then sent to various manufacturers. Consider the Manufacturer When selecting your minicomputer, one important item to consider is the manufacturer. Remember, when you buy a computer, you're also buying the services of a computer company. A firm that makes a commitment to its customers and provides a product that is field tested before releasing it for sale is preferable. Examine the company's maintenance and support packages, since every machine requires preventive maintenance. Does your manufacturer or original equipment manufacturer (OEM) support service sites in your area? Has their service record been commendable? Will they provide training for your personnel and a supply of circuit boards so you can retain a degree of self-service autonomy? Three methods of buying a computer involve the manufacturer, an OEM, and the systems house. Buying direct from the manufacturer means you go straight to the source, using no middleman. This gives you maximum flexibility; you can consider every alternative and many possible combinations of computers, peripherals, and software until you find exactly the right system for you. The OEM buys computers direct from the manufacturer and builds them into his own computerized, special purpose product. He usually sells a complete package, including software and hardware, and often noncompetitive equipment as well (a scientific or engineering instrument, for example), designed for the mining market. Because he offers a packaged product, the OEM can often charge less for the system than if you put the pieces together yourself. In many ways, the OEM also provides a unique system. And while the OEM sells a packaged solution, he also usually has the special market knowledge necessary to modify the system to meet your unique needs, if necessary.

Jan 11, 1981

By Richard P. Killmeyer

In 1985 the Pittsburgh Energy Technology Center (PETC) of the U.S. Department of Energy (DOE) conducted a study to evaluate the emerging selective agglomeration processes (Killmeyer, 1985). This paper covers a recent similar study evaluating an associated technology, the emerging advanced froth flotation processes. This study has goals similar to those of the 1985 study: to evaluate the emerging froth flotation technologies collectively and determine how far they have progressed in their ability to clean ultrafine coal, and to assess the differences among the participants. The major concern again in this study was not the level of development, nor the economics of each individual process but only the current technical performance.

Jan 1, 1989

By G. W. McCaa

Plans for a large industrial development in the Upper Ohio Valley between Moundsville and New Martinsville, West Virginia, were announced in the Fall of 1955. This development consisted of a large aluminum plant to be .built by Olin-Mathieson; a 675,000 KW power plant to be constructed by the American Electric Power Service; and a large coal mine adjacent to the power plant to be developed by the Hanna Coal Company Division of Consolidation Coal Company. The Ireland Mine was designed to efficiently supply fuel for the power plant, and this was the first consideration in the location of facilities, design, and development of plant and the selection of the equipment. The first problem was to find a suitable area for the surface facilities. A level bottom area south of the power plant was reserved for future industrial plants and this area was also blocked off from the coal reserves by an old abandoned and flooded mine. The coal storage facilities of the power plant were on the north side of the plant and it was decided to locate the coal mine preparation plant on-the shoulder of a hill above the power plant. This location required the excavation of 70,000 yards of rock but permitted the driving of a belt slope from the plant at an angle so that the haulage roads underground would miss the abandoned Cresap Mine. This location also permitted the plant to be located at an elevation so that the conveyors leaving the plant were horizontal and had sufficient clearance above the highway and railroad tracks. The other surface facilities consisting of air shafts, supply slope, supply yard, office, bathhouse, shop and warehouse were located in the valley some distance north of the preparation plant. This location placed these facilities one mile nearer to the working area. Plans for design and development of the mine were started in November 1955; grading and clearing of surface area was started in January 1956; the air shafts and slopes were started in the Spring and Summer of 1956; and the first coal was produced from the supply slope in October 1956. The preparation plant was put in operation in March 1958, and by July 1959 was producing 8,000 tons per day.

Jan 1, 1959

By J. A. Beesley

This paper reviews contemporary international law concerning the seabed, current developments in the United Nations on the seabed, and the main outstanding problems. It emphasizes the importance that the Canadian government attaches to this area.

Jan 1, 1969

By David Hatem, Michael Vitale, Joseph Gildner, Michael Roach, Fred Dunham

Dispute Review/Resolution Boards (DRB’s) are a highly successful dispute avoidance and resolution tool. In a joint effort between the UCA of SME and the Dispute Resolution Board Foundation (DRBF), the authors embarked on an informal assessment of the state of the DRB practice in the tunnel industry from the point of view of the Contractor, Owner, DRB Practitioner, and Attorney. The results of this assessment were presented in a panel discussion at the Rapid Excavation and Tunneling Conference (RETC) in June of 2021. This paper presents the results of that session with recommendations for further industry discussion and implementation

Dec 1, 2022

This publication summarizes the in-house and contract research projects programmed for fiscal year 1984 by the Bureau of Mines under its Conservation and Development activity. The document provides a mechanism for interested parties to gain insight into projects of the Bureau's Conservation and Development research program. The objective of the Conservation and Development Program is to provide the technological advances needed to stimulate the mining of domestic deposits containing critical, strategic, and other essential minerals in compliance with existing regulations and at costs sufficiently low to be competitive in world markets. Research efforts are directed toward improving the fundamental understanding of processes and procedures involved in the production of minerals. The overall goals will be accomplished by investigating alternative mining methods to increase domestic production of critical and strategic minerals from low-grade deposits; expanding the technology for the economic and efficient extraction of minerals consistent with cost-effective compliance with environmental regulations; and advancing the technologies needed to insure an adequate supply of coal.

Jan 1, 1984

By Lloyd Buckingham

Barrick Gold Corporation (Barrick) has undertaken innovative methods of evaluating and improving the performance of grinding mills in several of its operations around the world. The results have been positive with some of the mines showing more than 20% net energy improvement leading to more than 43,000 tonnes per year reduction in CO2 emissions in four of the operations reviewed.

Jan 1, 2012

By E. J. Dulis, R. M. Fisher, K. G. Carroll

IT is well known that ferritic steels containing more than 15 pct Cr when subjected to temperatures in the range of 700" to 1000°F exhibit increasing hardness and decreasing ductility. The phenomenon has been widely termed the "885 °F embrittlement," after the temperature of most marked effect.'.' In view of the excellent review articles available in the literature3-6 only a brief account of experimentally established facts need be given here. The extent of changes in physical characteristics during embrittlement depends on chromium concentration and time at temperature, higher alloy content and longer time both promoting more rapid and extensive changes. In a 27 pct Cr steel, changes in impact strength and in angle of fracture in bending can be detected after only a 1 hr exposure at 885°F; after 50 hr this steel becomes quite brittle. Hardness increases slowly with time during thousands of hours exposure and may attain a maximum hardness number twice as large as that of the unexposed steel. Microstructural changes accompanying embrittlement have been described as an initial widening of grain boundaries followed by eventual darkening of ferrite grains. Embrittled steels etch more readily, e.g., the weight loss of a 27 pct Cr steel in acid solution may occur at a rate one hundred fold greater following exposure at 885 OF. Marked changes which accompany embrittlement have been observed in electrical resistivity, specific gravity, and magnetic coercive force. Changes in physical properties may be readily removed by heating at temperatures above the embrittling range, such as a treatment at 1100°F for 1 hr. It has frequently been noted that the 885 °F embrittlement suggests precipitation on a submicro-scopic scale of a chromium-rich constituent, the nature of which has not been revealed by X-ray diffraction. Progressive broadening of the body-centered cubic diffraction lines during embrittlement has been observed," and recent observations by Lena and Hawkes' upon single crystals have shown early asterism in X-ray photographs, disappearing within an hour at 900 °F. Many workers have ascribed8-13 the phenomenon to a precipitation of a phase (FeCr), which is known to cause embrittling effects at temperatures much higher than 885°F. Two general observations, however. suggest that a precipitation cannot be responsible for the 885°F phenomenon: 1—prior cold work greatly enhances a formation, whereas it scarcely affects the 885 °F embrittlement, and 2—the presence of an alloying element such as nickel or manganese may have an effect on the 885 °F embrittlement which is opposed to its effect upon a formation. The slight enhancement of a formation and 885°F embrittlement observed in the presence of elements with strong carbide and nitride forming tendencies' is probably a consequence of lessened chromium depletion of the matrix. The bar graph in Fig. 1 shows a typical example, taken from two 27 pct Cr steels used in this work, of the hardness after exposure for 10,000 hr at 900°, 1050°, and 1200°F. Steel A (0.03 pct C, 3.13 pct Mn) showed marked hardening at 900" and 1200°F, whereas steel B (0.12 pct C, 0.63 pct Mn) exhibited only the 900°F hardening. The cr phase was found in steel A at the higher temperatures but not in steel B. Presumably a formation is enhanced by the low-carbon and high-manganese concentrations in A," Thus there are two distinctly different hardening phenomena present which cannot both be ascribed to v precipitation without invoking a transition phase possessing remarkable properties. Materials A number of chromium steels exposed for long periods (5000 to 34,000 hr) at 900°F, as well as unexposed samples of one of the steels, were available for this investigation. Table I gives the chemical compositions and aging treatments of these steels. In addition to these steels exposed in the elevated temperature test furnaces of the National Tube Division, a number of high-chromium steels were heated for short periods in small laboratory air furnaces and lead baths. Supplementing these commercial steels, a sample of high-purity (0.018 pct C, 0.002 pct N) 28 pct Cr iron, exposed 1000 hr at 887°F. was furnished by the Union Carbide and Carbon Corp. In addition, an alloy of iron and chromium of high purity containing 46 pct Cr was used. This

Jan 1, 1954

By V. F. Bannikov, A. P. Kozlov

"The purpose of this study was to develop a theoretical and technology framework for designing new combined technologies for processing tailings containing non-ferrous and noble metals using dry separation. The main goals of the study were: identifying the distribution patterns of valuable components in various fractions in dry separation processes; examining the patterns identified for different types of non-ferrous and noble metal tailings; developing a theoretical and technology foundation for the development of innovative technologies for the efficient processing of tailings with minimal process water consumption. To examine the possibility of efficient recovery of valuable components from refractory tailings using dry separation, an experimental laboratory unit was designed and built, composed of novel or modified lab equipment: plasma unit for increasing the magnetic susceptibility of Fe - containing minerals; magnetic separator supporting isodynamic and polygradient fields; pneumatic separator for the dry separation of finely dispersed mineral mixtures; dielectric separator using the resonant frequency of the electric field. The laboratory unit supports various modifications and combinations of the lab equipment. The experimental studies led to the development of a unified process scheme for lab tests of mature and non-ferrous smelter tailings using dry separation methods.INTRODUCTION The huge amount of waste from mining and processing of mineral resources Russia inherited from the extensive use of mineral resources in the Soviet Union and amount of waste continue to grow. Often the content of valuable non - ferrous, rare and noble metals in waste exceeds the balance contents in natural ores of the developed deposits. The availability of a rich scientific reserve for the creation highly effective innovative technologies for waste processing determines the necessity of the acceleration in the resolution of problems of the complex assessment, capitalization and involvement in the processing of technogenic resources in Russia (Chanturiya and Kozlov, 2014.)."

Jan 1, 2018

By H. J. Coleman

Knowledge of the types of naturally occurring sulfur compounds in petroleum is of both theoretical and practical interest to petroleum chemists and geologists. This knowledge has been extended by the identification of 77 sulfur compounds, including 36 thiols, 23 chain sulfides, and 18 cyclic sulfides in a 111° to 150° C boiling range distillate of Wasson, Texas, crude oil. The characterization procedure used in separating and identifying these compounds included isothermal distillation, vacuum fractionation, liquid-solid chromatography (alumina adsorption), chemical treatment, gas-liquid chromatography, microdesulfurization, and infrared analysis. The procedural steps described represent a systematic method of sulfur compound analysis considered applicable for determining the nature and concentration of the sulfur constituents present in any straight-run petroleum distillate of the above-boiling range.

Jan 1, 1966

By J Theiler, B Beamish

Spontaneous combustion hazard assessment from an environmental impact perspective is not well understood and is seldom given due consideration in environmental impact statements. In surface mining operations, self-heating, leading to spontaneous combustion may occur when rock units containing reactive metal sulphides and organic carbon are disturbed by mining operations and exposed to the atmosphere. When these rocks are present self-heating will occur in situations where the rate of heat generated from oxidation reactions exceeds the rate of heat lost to the surroundings. The processes and mechanisms that lead to spontaneous combustion events are varied and generally complex. To effectively manage spontaneous combustion in surface mining operations, it is necessary to characterise the spontaneous combustion propensity of the geological materials involved. Until recently there has been no testing procedure for assessing the propensity of waste rock to spontaneously combust that has been adopted by industry. However, new developments in adiabatic test methods have proven successful in determining the self-heating behaviour of coal (Beamish and Theiler, 2015) and coal containing reactive pyrite (Beamish and Theiler, 2017). These adiabatic test methods have now been modified to assess the incubation behaviour of waste rocks and can be used for their spontaneous combustion characterisation in advance of mining (Beamish and Theiler, 2016). The new method provides a practical means to establish the likelihood of developing a spontaneous combustion event for the specific site conditions. This paper presents examples of the use of a cost effective first pass filter for assessing spontaneous combustion potential of waste rock based on geochemical data from four surface mines. This is supported by adiabatic Incubation Test results for three of the mines and visual examination of cores for one of the mines. CITATION:Theiler, J and Beamish, B, 2018. Valid spontaneous combustion hazard assessment for surface mine environmental impact statements, in Proceedings Life-of-Mine 2018, pp 64–67 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By Shuji Owada, Mayumi Ito, Takehiko Nishimura, Toru Yamashita, Sadayuki Shinozaki, Takashi Ando, Tomoe Ota

Electrical disintegration (ED) was applied to Nantun coal (China) in order to improve liberation of coal substance for the pretreatment of producing “Hyper Coal” of which the combustion gas was planning to inject directly to turbine for power generation. It has been found that many cracks generated in the ED were existent at phase boundaries with mineral matters and liberation of coal substance became much higher than that in mechanical comminution methods such as roll crusher. Since the ED occurred more easily (with lower voltage applied) for the coals of higher mineral content, it is considered that this method could make a better contribution especially to comminute middling coals. We also found that the ED technique could apply not only single particles but also to coal particles assemblage, keeping almost the same or higher disintegration efficiency. In the mineral matters, Si and Al components were preferentially well liberated by the ED.

Jan 1, 2003

By N Yarahmadi

Characterization of pore pressure is critical for appropriate design of tailings dams. Furthermore, if seepage rates through tailing embankments increase unexpectedly or become uncontrolled, undesirable conditions may prevail to progress piping or internal erosion that could lead to the dam’s instability or ultimate failure. A three-dimensional seepage analysis was performed on a tailings dam using finite element method to find the rate of seepage and pore water conditions in the embankment and foundation. The results were then compared to a conventional two-dimensional seepage analysis carried out on the typical cross section of the embankment and the field data acquired from the instrumentation system. Considering the monitoring data, comparison of seepage analyses results for the two and threedimensional models, showed that the results of the conventional two-dimensional seepage analysis are significantly underestimating reality. Relying on two-dimensional seepage analyses might result in underestimation of seepage rates and impact the safe operation of tailings dams. Similarly, unrealistic prediction of pore water pressure conditions, based on simplified seepage analyses, can lead to overestimation of the rate of strength gain of material and consequently safe embankment raising rates.

Jul 1, 2021

By Hugo Barrientos

"The growing need to optimize the mining processes produces a need for users to have a simple, reliable, secure and cost-effective method to monitor the values of the variables measured in field. The solutions described in this paper, we will demonstrate how the implementation of Emerson Smart Wireless technology helps to optimize the leaching and electro winning processes. An effective monitoring of the variables involved in the operation of a heap leach, such as pressure, flow rate, pH, water level control and regulator valves can improve production and optimize the use of sulfuric acid, which results in a more effective management of resources and helps reducing input costs. Moreover, the constant monitoring of variables prevents the risk of landslides, reducing maintenance costs. In electro winning cells, the wireless solution measures variables such as pressure, flow rate, temperature and voltage provides a performance indicator for the entire operation, capable of detecting and predicting shorts, and monitoring the overall functioning of a cell or group of cells. As a result of the applications studied, users can monitor variables in real time, optimizing the use of resources, quickly detecting possible flaws in the process and reducing the risks in the operation. All these factors have a direct impact on company results."

Jan 1, 2014

By C. W. Davis

AN inclined shaft is usually more difficult to sink than a vertical shaft, yet it is often chosen because of the subsequent saving in cross-cuts required to reach an inclined ore body. This paper briefly discusses the factors which led to the choice of an incline and then describes the operations involved in the preparatory work and in the sinking. These operations included a programme of mining out the underground facilities and installing the structures required for a hoist-room, cable-raise, waste-pass, ore pass, two sets of skip dumps, and a collar station equipped with counterbalanced drop-rails. The shaft was sunk 1,000 feet and four stations were cut, each with loading pockets. As the sinking progressed, the rock changed from hard porphyries and dense cherts to blocky limestones and earthy rubble. These conditions called for a change in methods and it is to the red it of the shaft-sinking crew that they overcame the new difficulties as the shaft progressed, while maintaining a satisfactory monthly advance. The section mined out was nine feet six inches by seventeen feet overall. This gave room for three compartments: two skip compartments four feet three inches by five feet nine inches inside the timber, to handle two-ton skips, and a manway three feet six inches by five feet nine inches. The sinking began on December 16th, 1941, and was completed on February 15th, 1943.

Jan 1, 1945

By James G. Ulinski, Sebastian Lobo-Guerrero, Vishal B. Patel

"Recently modified design equations used in the transportation industry to calculate side friction and end bearing capacity for drilled shafts are now providing more realistic estimations of capacities than did previous methods. Using multiple case studies and test results from various projects, a more realistic design approach was formulated by the Federal Highway Administration (FHWA), which resulted in greater values of ultimate capacity for side friction and end bearing and in a more efficient design overall.In 2010, the FHWA published GEC-10 – Drilled Shafts: Construction Procedures and LRFD Design Methods, which illustrates a different method of calculating side friction and end bearing resistance and results in greater values for design. In 2014, the Association of State Highway and Transportation Officials (AASHTO) adopted the method put forth by FHWA, which was included in its LRFD Bridge Design th Specifications, 7 Edition. The Pennsylvania Department of Transportation (PennDOT) recently adopted and incorporated the similar methodology as AASHTO for calculating side friction and end bearing for drilled shafts in rock, and these changes are reflected in the 2015 edition of the PennDOT Design Manual, Part 4 (DM-4). This article discusses the past and current design methodology along with a project case study with results from Osterberg Cell (O-cell) load testing, which presents a comparison between the design resistances of ultimate side friction and end bearing and the measured capacities at failure.The Old and the NewEditions of the AASHTO LRFD Bridge Design Manual from 2012 and earlier estimated ultimate side resistance, qs, in rock using the following equation (modified from Horvath and Kenney, 1979):qs=0.65aEpa(qu/pa)0.5 < 7.8pa(f ’c/pa)0.5 where: qu is the uniaxial compressive strength of the rock in ksf; pa is the atmospheric pressure in ksf; aE is the reduction factor to account for jointing in rock; and f ’c is the compressive strength of the concrete in ksi. For intact rock, previous versions of the AASHTO manual required that the ultimate end bearing resistance, qp, was calculated using the following equation: qp=2.5qu."

Jan 1, 2017