Search Documents

By S. E. Clay, P. R. Taylor

A physical model for the diffusion and flow of gases through porous solids, which accounts for the random nature of individual gas molecules moving through a solid of definite structure, has been formulated. The model was solved using' the Monte-Carlo technique. It was then used to evaluate specific constants related to the dusty gas model and to describe the gas-porous solid diffusion phenomena. Experimental results were used to validate the stochastic model.

Jan 1, 1988

By Y. J. Wang

In the mathematical analysis of electrical networks, the electrical devices are often modeled using idealized network elements such as current sources, voltage sources, and resistors. An analogous approach is outlined here for the modeling of mine ventilation networks, which can be considered nonlinear resistive networks. The modeling technique proposed uses five basic (non-reducible) elements: the H element, the Q element, the D element, the R element, and the N element. These elements are characterized by their (a) pressure gain or loss, (b) air quantity, and (c) pressure-versus-quantity relationship, each of which may be known or unknown. In addition to the definition of the basic elements, the necessary conditions for which there exists a unique solution are discussed. This is performed using theoretical developments derived from electrical circuit theory and illustrated in example networks. The proposed procedures are useful in the solution and characterization of mine ventilation networks.

Jan 1, 1996

By D. R. Spears

The Bureau of Mines has investigated the fundamental aspects of shear-flocculation using a rapid, in-situ particle size analyzer. Silica was stirred in the presence of an aliphatic amine to determine the effects of collector coverage, stirring speed, and solids concentration on the kinetics of shear-flocculation. The results showed that shear-flocculation is a two-stage process. In the first stage, mean particle size increased rapidly in the first 1-2 min of reaction; in the second stage, an equilibrium was set up between the rate of floc growth and floc decay. Collector dosage affected the position of the equilibrium by altering the number of surface sites for particle-particle attachment. A minimum stirring speed was necessary for shear-flocculation to occur and was dependent on solids concentration and collector dosage. This speed was the minimum necessary for particles to overcome the electrostatic energy barrier which kept conditioned particles dispersed. Larger particles flocculated more rapidly. At very high stirring speeds, large flocs became unstable, resulting in a narrowed particle size distribution in the slurry.

Jan 1, 1993

By H. H. Kleizen

The operation range and efficiency of dewatering apparatus are important factors in the selection of an apparatus for a given purpose. In this paper theories are presented allowing to predict these basic characteristics for different dewatering apparatus and compared with experimental and practical data obtained on coal and ore slurries.

Jan 1, 1989

By M. van Elp, R. Saitua Nistal, P. J. M. Groot

Demand for construction raw materials depends on investment in housing, other buildings and infrastructure. The provision of these materials requires early knowledge of future trends in construction investment. By using scenarios possible future developments and bandwidths can be explored. Policy makers in government organisations as well as in the private sector can base their policy decisions upon these insights. In this paper we discuss the case of sand and gravel in the Netherlands. We will show that, depending on the future role of government and the degree of internationalisation, the long term demand for construction raw materials will strongly diverge. Nevertheless there are some common developments such as a decreasing population growth, a smaller share of the labour force in total population and a growing wealth. In different scenarios we will encounter different conditions for minerals provision and for sustainable development.

Jan 1, 2011

By A. Sinha, C. Sawmliana, P. Pal Roy

Using the newly developed and permitted explosive Pentadyne-HP (Gulf Oil Corporation Ltd., Hyderabad), the Blasting Department of the Central Institute of Mining and Fuel Research, Dhanbad experimented at the GDK-5 Incline, RG-1 Area of the Singareni Collieries Company Ltd. (SCCL) to establish one modified angular cut blasting pattern as an alternative to conventional solid blasting in India to obtain longer pull, as well as to achieve at least 40 t of coal in a single blast round for the deployment of diesel load-haul-dump units at the face. This permitted explosive satisfied the statutory requirements of incendivity characteristics applicable to P5 explosives of the regulatory agency Directorate General of Mines Safety (DGMS) of India. The present paper summarizes the development of this new blasting pattern and its possible use in Indian coal mines.

Jan 1, 2010

By Thomas A. Earl

Strip mining of coal, and to a lesser extent limestone, gravel and other mineral deposits in the Appalachian region of the eastern United States has left many large and small areas of devastated land where mining predated reclamation requirements. In Pennsylvania alone, there are between 250,000 and 370,000 acres of strip-mined land 1,2/. A higher percentage, and a greater total acreage of land in Pennsylvania is in need of some form of reclamation than any other state, with the neighboring states of Ohio and Nest Virginia also having nearly the same magnitude of mining.2/ Recent legislation governing strip mining of coal proposed royalties to cover reclamation of such presently unusable land. However, in Pennsylvania and other states some progress has already been realized by utilizing abandoned strip mines and gravel pits for waste disposal sites. Given acceptable hydrogeologic settings, such use of these mined areas for landfilling has provided the incentive for ultimately restoring unreclaimed land to beneficial use, at no cost to the general public.

Jan 1, 1975

By M. S. Riyazulla

A model of a new laboratory magnetic separator has been conceived to cater the needs of process engineers and mineralogists world over engaged in mineral characterization and beneficiation. It would be essentially a laboratory instrument for the separation and concentration of various ferro and non-magnetic minerals. Based on the basic concept of Frantz Isodynamic Magnetic Separator, the new separator conceived would not only speed up the work of a process mineralogist and save the energy, but it would effectively separate and sequentially produce about fourteen fractions at a time. In the present paper, the probable operational procedures and the design have been discussed in detail for the various mining companies to assess its economic feasibility. If it could be fabricated, it would have a worldwide market The concept has been patented in author?s name in India.

Jan 1, 2009

By Yinan Zhang, Y. Luo

Most of the reported coal spontaneous combustion events occur in surface and underground mines where low rank coals (i.e., subbituminous and lower for this particular studies) are extracted indicating their high propensities for spontaneous combustion. Low rank coals have high moisture content (15 to 45%) and are capable of absorbing more moisture in dried condition. However, it is hard to induce the initial stage of self-heating process for the low rank coal using the current laboratory R70 testing method — a method widely used in the coal industry. Like a sponge, dry low rank coals can absorb water vapor in the air while the heat contained in the moist air is transferred to coal and served as the required activation energy to initiate the coal self-heating process. In order to prove this theorem and quantify the effects, the R70 adiabatic oxidation testing method has been improved to introduce a controlled moist flow into the coal reaction vessel. Tests using the new method and its setup on low rank coals showed that the initial self-heating process of coal sample can be greatly accelerated by the added water vapor — impossible with the regular R70 method. Once the self-heating is sustained, the removal of air moisture can further accelerate the process.

Sep 17, 2021

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 P. Guliov

In the first part of this paper the authors present an overview of industrial minerals produced in the Canadian provinces of British Columbia, Alberta and Saskatchewan, and supplied to the Pacific Rim countries. The second part outlines some of the unique opportunities for industrial minerals that exist in the three western Canadian provinces and those minerals we feel have development potential for overseas markets. Because of time constraints, it is not an exhaustive presentation on industrial minerals, but is focused on a few selected minerals that we believe have high potential.

Jan 1, 1990

By K. Lang

The use of high-efficiency electrical submersible pumps (ESPs) for large scale, open pit mine dewatering operations provides a good example of how technology, products and services from the oil and gas industry can be adapted to the mining industry. In this case, the mine is Goldcorp?s Peñasquito in the Zacatecas state of Mexico, at the Peñasco and Chile Colorado open pit deposits. The technology, products and services are from Schlumberger artificial lift (AL) and Schlumberger industrial water services (IWS). Overview of high-efficiency ESPs This section provides a brief description of the basic components, specifications and operating capacity ranges for the ESPs compared with traditional or conventional dewatering well pumps. This information helps to establish how ESPs provide certain functional and economic advantages over conventional pumps in a mine dewatering application. A schematic of a high-efficiency ESP in an oil and gas (O&G) application is shown in Fig. 1.

Sep 1, 2013

By S. B. Patton

A computer model, which quantitatively utilizes the relationship between the interactive and dynamic processes of methane drainage, mining, and ventilation, is presented. The model includes simulation of the coalbed methane reservoir for prediction of gas-emission rates under the influence of degasification wells and longwall mining, ventilation network-generation, and ventilation simulation. As mining progresses step-wise through the coalbed-methane reservoir, the ventilation network is created and subsequently simulated, iteratively determining fan requirements to safely reduce methane concentrations. The model can be used to quantitatively study the effectiveness of methane degasification on the ventilation system in a longwall panel.

Jan 1, 1992

By H. Wen, X. Zhai

"The Jurassic coal fields which lay in west China are the major energy base and contain half of coal resources in China. Due to the gather and degeneration rules, the spontaneous combustion characteristic of Jurassic coal is distinguished with permo-carboniferous coal, which needs to be studied deeply. Programmed heating experiments of five Jurassic coal samples and three permo-carboniferous coal samples from different primal coal fields in West China were conducted to identify the characteristic parameters in the low temperature stage of oxidation and spontaneous combustion. The experiments were carried out under non-isothermal heating conditions up to 180? at the heating rate of 0.33?/min in an air atmosphere. The result showed that oxygen consumption rate, CO gas production rate and heating intensity of all coal samples increased with the rising of the temperature, which of the Jurassic coal was higher than that of Permian-carboniferous coal. The C2H4 gas of Jurassic coal generated earlier, more than that of Permian-carboniferous coal in the process of oxidation and spontaneous combustion. It indicated that the Jurassic coal was easier to be oxidized and spontaneous combustion and the index parameters of spontaneous combustion were different between the Jurassic coal and permo-carboniferous coal.INTRODUCTION Coal was the foundation of industry development, and occupied 70% of primary energy production and consumption structure in China. According to the data of the 3rd coalfield prediction, 39.6% of the total coal resources were located in northwest Jurassic coal field in China [1], where the quality of coal was excellent. The study of northwest Jurassic coal already dated from the 80s of the 20th century, about coal rock composition, coal metamorphism [2], coal-derived hydrocarbons, coal structure [3], etc. The results of these studies showed that the composition and properties of Jurassic coal was obviously different from Permian-carboniferous coal, as well as the characteristic of spontaneous combustion [4]. As a result, the spontaneous combustion characteristic of Jurassic coal particularly needed to be studied. Now more and more methods could be conducted to test the characteristics of coal spontaneous combustion, for example, thermal analysis technology [5-7], programmed heating experiment [8-10] and coal spontaneous combustion experiment [11,12]. In these methods, programmed heating experiment could be conducted to determine the oxygen consumption rate, CO gas production rate and heating intensity quickly."

Jan 1, 2015

By C. McKinnon

Climate change is the central challenge facing the mining industry, wherein producers must simultaneously ramp up production to provide the raw materials for clean technologies while transitioning to carbon neutrality. While transitioning to renewables will take time, mines can start improving energy efficiency while improving productivity today. This paper proposes a novel technology ecosystem that can help. By monitoring mine shovels, loaders, haul truck paths, and conveyor belts, the proposed technology enables particle size measurements throughout the operation, truck and belt volume monitoring, ground engaging tools monitoring, and boulder detection.

Mar 2, 2022

By William T. Griswold

Few metals or industrial minerals can boast a better growth record over the past fifteen years than the borates. This period of growth occurred before the influence of any large-scale use in plastics or high-energy fuels. These new developments not only provide expanding markets, but the programs related to their development are generating research information that will lead to many other new uses. The most dynamic growth areas for refined products of boron or borates are in the acid, the oxide and the reduced forms, such as the metal and the hydrides. Expanding requirements for these products will modify the emphasis on the use of naturally occurring sodium borates. Any borate from which boron can be economically extracted will become a potentially important ore. This is particularly true of the calcium borate, colemanite. Only one large deposit in the Western World has ever been developed where the principal economic minerals are sodium borates, This factor alone would discourage any exploration program directed solely toward the discovery of these ores; on the other hand, ample exploration opportunities for calcium borates exist in the desert regions of California and Nevada. It is therefore reasonable to restrict a program to this region, in spite of geologically favorable areas in foreign countries such as Turkey, Argentina and Chile.

Jan 1, 1959

By D. A. Stanley

Researchers at BCD Technologies and the University of Alabama have applied three statistical techniques to the information contained in a large database of measurements from a phosphate ore processing plant. The rust, Principal Components Analysis (PCA), replaces many measured variables with a few fundamental and un-correlated variables. The second technique, Projection to Latent Structures (PLS), is an extension of PCA that explores the relation between variables identified as either independent or dependent. The third technique, Cluster Analysis (CA), is applied to the results of the PCA or the PLS calculations, and identifies individual data clusters that represent uniform operating conditions in the plant. All three statistical methods can be seen as geometrical operations on the data viewed as points in space. A Viewer gives a corresponding graphical presentation of the data points. This paper describes the use of the above three techniques and the Viewer to explore part of the phosphate flotation database.

Jan 1, 1998

By Jon Kellar, Samuel Kessinger, Prasoon Diwakar

Tantalum (Ta) and niobium (Nb) are extracted from many different ore types. The major economic orebody mined for tantalum and niobium consists of tantalite ((FeMn)Ta2O5) and columbite ((FeMnNb2O5)) in a solid-solution mineral commonly referred to as “coltan.” The largest supplying region, The Democratic Republic of the Congo (DRC), is unfortunately also the most ethically compromised source for this critical mineral. Officially, the U.S. government has deemed coltan ore from the DRC a “conflict mineral” [1]. The lack of pragmatic and effective local mining regulation in Central Africa, when coupled with high levels of violence and corruption, has spawned a widespread, illegal, unethical and, most importantly, unsafe economy. This illicit economy is centered around first, illegally mining these valuable conflict minerals and second, smuggling these minerals into the global supply chain. Handheld spectroscopy devices could provide further transparency to these opaque supply chains, giving miners, traders and refiners the ability to authenticate the provenance of the minerals they encounter, and allowing companies to prove compliance with the regulatory agencies attempting to curtail illicit mining.

Mar 1, 2025

By Fun-Den Wang

In underground coal mines, three types of roof failure (2)*, tensile, local, and shear, occur in the development entries and in room-and-pillar extraction areas. Most of the tensile failures in the roof at the center of the mine opening as well as those local failures due to fracture or jointing can be controlled by roof bolts, trusses, and timbering. However, control of the shear failure at the sides of the roof (or the cutter-roof caving) has not been successful with ordinary roof control methods. The only effective method, when there is an indication of cutter-roof caving, is to use cribs, which are costly and make transportation, ventilation, and production difficult. Frequently, the operator allows the cutter roof to cave and then cleans it up rather than trying to stop it. This shear type of roof failure is often associated with large areas which may progressively involve several hundred feet of roof caving at one occurrence. At times, this shear failure occurs suddenly with little or no warning. This can result in buried equipment and great danger to the safety of personnel. This shear failure may be due to one or more of the following: high stress concentrations at the corner of the roof from (1) high horizontal to vertical load ratio, (2) orthotropic elastic properties of rock and coal, (3) greater stiffness of the immediate roof layer than of the secondary roof layer, (4) viscoelastic behavior of rock and coal, and (5) geometry and material properties of the geologic setting. Removing or reducing the high stress concentration should improve the roof stability. The structural analyses of models of two typical

Jan 1, 1972

By Howard W. Earnest

The Rio Blanco Oil Shale Company completed a modified in situ oil shale retorting demonstration at its Tract C-a Lease in the Piceance Creek Basin of northwestern Colorado during the spring of 1982. This demonstration was the first MIS project with shafts rather than adits for access to the mining operation, and it involved several potential hazards which required that particular attention be paid to mine ventilation. Methane was first encountered during shaft sinking and ultimately resulted in the mine being classified gassy by MSHA. Secondly, we encountered hydrogen sulfide in association with the ground water, and this proved to be a more persistent problem than did the methane. Thirdly, in order to burn the underground retorts, it was necessary to provide for potential leakage of retort gases and to obtain a modification to the MSHA standard which forbids fires under- ground. This modification had a significant effect on the ultimate ventilation procedures at Tract C-a. An extensive under- ground air monitoring program was included in the ventilation system.

Jan 1, 1983