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By Michael Elliot-Jones

The fundamental competitive structure in world coal markets will be modified by the entry of such new participants as Colombia and the newer mines in South Africa. The US will, in most markets remain the swing producer, although a number of low cost US mines will continue to compete in world markets. Exchange rate swings will persist as a major hazard for coal exporters.

Jan 1, 1986

By Werner Wenzel

Methods to increase the gas penetration through sinter layers. In the field of agglomeration, sintering has gained importance, specially in Europe; in Best-Europe this trend will continue till the year 1980, since it is quite probable that in the blast furnace burdens with 50-60 sinter, 10-20 % pellets and 20-25 % ore lumps will be employed. In order to meet this demand for sinter, new sinter bands with reaction areas between 300-400 m2 will be constructed. Chemical and physical phenomena during the Suction-Draught-sinter process. Iron ore sintering is generally considered as a burning process where the material contains 90-95 % ash i.e. non-combustible ingredients. Sintering represents a heterogeneous exothermic reaction in which the chemical phenomena as combustion, calcination, hydration, reduction and oxydation are superposed by physical phenomena. The physical phenomena are devided into material transport and simultaniously occurring heat transport processes. The velocity of these combined physico-chemical reactions i.e. the change in the reaction site per unit time determine the efficiency of the sinter process. The gas permeability as an important criterion of heat transport during the Suction-Draught sinter process.

Jan 1, 1971

By W. K. Collins, C. L. Dahlin, D. C. Dahlin, W. K. O’Connor, G. E. Rush

Direct mineral carbonation was investigated as a process to convert gaseous CO2, into a geologically stable final form. The process utilizes a slurry of water, with bicarbonate and salt additions, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, resulting in dissolution of the mineral and precipitation of magnesium carbonate (MgCO3). Optimum results were achieved using heat-pretreated serpentine feed material and a high partial pressure of CO2 (Pc02). Specific conditions include 155°C, PC02 = 185 atm and 15% solids. Under these conditions, a 78% conversion of the silicate to the carbonate was achieved in 30 minutes. Process mineralogy was utilized to investigate the appropriate feed characteristics, identify the process products and interpret the mineral dissolution and carbonate precipitation reaction paths. Key words: Mineral carbonation, Carbon dioxide sequestration, Carbonates

Jan 1, 2003

By A. J. Nugent

Investigations were undertaken to evaluate peroxygen compounds for effective­ness in alkaline cyanide leaching of gold. The addition of peroxygens improved the leach results. Calcium peroxide was the best performed reagent to be employed. Improved reagent consumption followed the trend of calcium peroxide> hydrogen peroxide> no peroxygen addition. In general, preaeration stages could be eliminated, and improved leach rates achieved with no detrimental impact on leach perfor­mance. Interox has not developed an Au Plus (Trade Mark pending) system to utilise this new leach reagent. Initial plant trials are verifying its potential to give additional benefits.

Jan 1, 1990

By V. Nasri, P. Jarast, M. Bakhshi

The Montreal metro Blue Line Extension toward the northeast consists of the construction of five new underground stations. The project includes 6 kilometers of the tunnel which will be constructed using a Tunnel Boring Machine (TBM). In line with the commitment to integrating sustainability best practices, Envision verification is pursued this project. The Envision reference framework was developed to cover all the sustainable development aspects of an infrastructure project and each phase of its life cycle (planning, design, construction, operations and maintenance, and end-of-life). As a part of this endeavor, low-carbon concrete and shotcrete mixtures are proposed for the linings of TBM and SEM tunnels as well as stations and auxiliary structures. The CO2 emission of the low-carbon concrete and shotcrete mixtures were compared with their typical mixtures and the total CO2 emissions reduction related to the tunnel lining is determined. The study is of strategic significance for achieving emission reduction in the tunnel industry.

Jun 13, 2023

By A. Kaczmarek

As the mining industry is enjoying a much needed and long awaited increase in demand for natural resources, consolidations in both the mining and mining service industries and a generational departure of experienced industry professionals is challenging today’s mining companies, not only in maintaining their existing operations, but also in securing qualified resources for developing new projects. These challenges are compounded for junior mining companies, oftentimes lacking in operating properties to draw from for experienced professionals and having to compete with the majors’ “mega-projects” for experienced project personnel from the reduced ranks of engineering companies. This paper discusses some strategies developed by Anatolia Minerals Development Limited in developing its Çöpler Gold Project in central Turkey.

Jan 1, 2006

By Robert E. Goodwin

There are four main requirements which must be considered when selecting a wire rope for the best serviceability. A proper choice is made by correctly estimating the relative importance of each of these requirements and selecting s rope which has those qualities best suited to withstand the combination of destructive forces expected under continued service. A wire rope should possess: 1. Strength sufficient to support the maximum load expected and with s proper safety factor. 2. Ability to withstand bending and to resist bending fatigue without failure of the wires. 3. Ability to withstand surface abuse such so abrasive wear, pounding, and wire scrubbing. 4. Ability to withstand abuse such as crushing and distortion.

Jan 1, 1968

By Yasushi Arai

"Among Tokyo Metro’s approximately 200km of subway lines, the Tozai Line that connects Chiba Prefecture and mid-Tokyo experiences congestion of up to 199% at worst and relief of this has become urgent. Therefore, as it is imperative to increase the number of trains operating in the exceptionally congested area from mid-Tokyo going east, a large-scale renovation work is planned between Iidabashi Station and Kudanshita Station that will facilitate turn-back via 3 tracks. While ensuring the safe and stable operation responsible for about 1.35 million passengers daily, this highly difficult work of inner wall demolition and reinforcement of the side walls and floor slabs will only be implemented for 3 hours during late night. This paper discusses large-scale plans to improve turn-back facilities, and the methods of construction therein as an example of operational improvement of a subway network. 1) INTRODUCTION The Tokyo Metro Tozai Line (“Tozai Line”) opened over the entire 30.8 km distance from Nakano to Nishi-funabashi on March 29, 1969. It has the longest operating length of the nine Tokyo Metro lines, and was the first subway line to extend past the borders of the Tokyo Metropolis. Through train services with two other railway companies are available from the Tozai Line. Tozai Line trains join the Sobu Line of the East Japan Railway Company (“JR East”) and the Toyo Rapid Railway Line of Toyo Rapid Railway (“TR”) from Nishi-funabashi Station, and the JR Chuo Line from Nakano Station. The line is structurally distinctive in that 51% of it was built using the open-cut method, 43% of it is elevated and the remaining 6% was built when we used the shield method for the first time 1)2)3)."

Jan 1, 2016

By Paul M. Bommer

Abstract. This cater presents the development of and results from a computer model of in-situ uranium leaching. This model uses a streamline-concentration balance approach and is useful with a vide range of reservoirs. It can be used with any type of veil system, in a reservoir with or without boundaries, and with any form of descriptive kinetics. The model also includes the effects of dispersion and consumption of oxidant by minerals other than uranium. The effects of areal sweep, variable uranium concentrations, variable permeability, and the presence of oxidant consumers on uranium production are shown and discussed.

Jan 1, 1979

By B. Kendall

"ISSUES ASSOCIATED WITH HAND DRILLING/JACKLEGS In coal mines, hand held air, electric, and hydraulic powered drills are used along belt conveyors, in single entry development, in entries where there are obstructions, and in long wall recovering bolting. In hard rock mines pneumatically powered “jack leg” drills are typically used in narrow vein mining. Drilling and bolting in narrow confines has traditionally been performed with pneumatically or hydraulically powered hand-held drills or newer electrically powered hand held hammer due to their low cost, simplicity of operation, and extreme flexibility due to their small size. Mechanized equipment has typically been too large, too expensive, inefficient due to the confined space, and too restrictive due to lack of flexibility for use in narrow confines. Although the hand-held equipment is effective, it requires operator exposure to certain inherent hazardous conditions in use. These include falling rock from the roof, rib, and face; tripping hazards; bending twisting lifting hazards; high noise levels; and chemical fumes from the pneumatic exhaust. The operation of the hand held equipment can adversely affect the long-term health of the operator – continual jackleg operation frequently results in long term damage to hearing, shoulders, arm and wrist joints, and back injuries. This results in a reduction in life style for the operator and higher personnel turnover rates for the mining company. Hand held drills also typically have limited thrust and torque capability which limits their ability to push long resin bolts, inadequate torque to properly install resin bolts, or to properly torque mechanical or tensioned rebar bolts. Hand held drills do not offer any type of protection for the operator from roof or rib falls. They do not offer any means for handling roof or rib mesh. Since the operator stands on the ground the maximum safe drilling height without use of a ladder or “riding the drill” is limited to 8’ (2.44M)."

Jan 1, 2015

By B. J. Arnold, F. F. Aplan

Prior laboratory work has demonstrated that much of the fine ash forming minerals entering a flotation froth are there as a result of water carryover- from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 8.5 m3 (300 cu ft) Wemco flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent solids in the froth). Reagent changes that result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1991

By J. M. Scharer, Bruce E. Halbert, Pettit. Carol M., Lysane Bolduc

The ratio of neutralization potential (NP) to acid production (AP) ratio is often employed for predicting acidic discharges from waste rock dumps. The available NP was evaluated in laboratory studies of limestone dissolution in simulated acidic mine water. The available neutralization potential strongly depended on the particle size. Using limestone particles of 114" (6.4 mm) or greater, less than 20% of the total neutralization potential was exhausted at the onset of acid conditions. Apparently, the dissolution of limestone became mass transfer limited. Under mass transfer limitations, the rate of pyrite oxidation may exceed the rate of neutralization by buffering minerals. The implications concerning the controls on limestone dissolution were examined using a geochemical predictive model for sulphide mineral oxidation in waste rock. The results have shown that in case of heterogeneous waste rock piles the NP/AP ratio is a reliable indicator for short-tam predictions only. Kinetic data on the depletion rate of the neutralizing minerals and geochemical modelling suggest that waste rock environments with NP/AP ratios as high as 5.0 may turn acidic in the long term.

Jan 1, 2000

By M. P. Murphy

The state of Illinois is committed to direct support of the Illinois coal industry. The Illinois Department of Commerce and Community Affairs’(DCCA) Office of Coal Development (OCD) provides incentive programs for coal and energy development. Illinois coal programs include tax and financing incentives for new coal-fired generation, infrastructure grants to expand coal mining and transportation systems, research and development grants to initiate and advance clean-coal technologies and demonstration grants to bring advanced coal utilization technologies to commercial-scale readiness. As a result of these efforts, the Illinois coal industry is reinventing itself and is now more productive and competitive than ever before.

Jan 1, 2003

By K. Fuenkajorn, S. Serata

Discussion by S. Serata and K. Fuenkajorn Background Results of the above study in the August 1991 issue of Mining Engineering offer valuable lessons in the solution of cutter-roof problems. The original study plan was initiated by the discussion authors to solve the problems using the "stress control method" of mining (Serata 1976, 1982; Serata, Carr and Martin, 1984; Serata and Gardner, 1986; Serata, Gardner and Preston, 1986; Serata, Gardnerand Shrinivasan, 1986; Serata and Kikuchi, 1986; Serata, Preston and Galagoda, 1987) However, the plan and the planner were changed to the arrangement reported in the paper. The change was considered reasonable at the time due to the mine engineers' uncertainties about the stress control method. Consequently, the basic principle of the study was shifted from the original stress control method to the method described in the paper, which will be called the "yield pillar method" for the purposes of this discussion. The paper convinces the reader that the yield pillar method fails to solve the cutter-roof problems. This doesn't mean that the stress control method also fails. Actually the contrary is true, as discussed below. Limitation of the yield pillar method The paper illustrates clearly how poorly the yield pillar method performs in solving the problem. The reason for this failure is the lack of the protective stress envelope needed to stabilize the cutter roof. Unfortunately, the protective envelope cannot be formed properly without utilizing the stress control method of mining. Changing the pillar size does not make much difference in the roof stability. Stress measurement The key issue is how to form the global stress envelope to make the gate entries safe for production. Therefore, measuring the stress condition of the ground around the mine opening is critically important to solving the cutter-roof problem, regardless of the method applied. With regard to the stress measurement, there is a serious question as to the reported stress state of [6 i = -51.7 MPa (-7499 psi), G2 = -44.5 MPa (-6458 psi) and 63 = -30.8 MPa (-4465 psi)]. It is mechanically impossible to have such a stress state at any location in the mine ground since the known initial vertical stress [o,,] is less than or equal to 800 psi. There may be a large stress state in the [61] direction, but that is possible only at the expense of the [63] value. Having the above stress tensors in the mine is simply impossible. The questionable, reported stress values could be attributed to the application of the overcoring method, which tends to produce erroneously large stress values in the extremely nonelastic mine ground. Stress control method The paper should be considered as a major contribution demonstrating the limitation of the yield pillar method. At the same time, the paper does not disprove the stress control method. However, in comparing the paper with stress control studies conducted in other similar failing grounds, the stress control method appears to be able to solve the problem more effectively. Therefore it is advisable that the mine not give up its efforts to solve the problem. [•] References Serata, S., 1976, "Stress control technique - An alternative to roof bolting?," Mining Engineering, May. Serata, S., 1982, "Stress control methods: Quantitative approach to stabilizing mine openings in weak ground," Proceedings, 1st International Conference on Stability in Underground Mining, Vancouver, BC, Aug. 16-18. Serata, S., Carr, F., and Martin, E., 1984, "Stress control method applied to stabilization of underground coal mine openings," Proceedings, 25th US Symposium on Rock Mechanics, Northwestern University, June, pp. 583-590. Serata, S., and Gardner, B.H., 1986, "Benefits of the stress control method," invited paper, American Mining Congress Coal Convention, Pittsburgh, PA, May 7. Serata, S., Gardner, B.H., and Shrinivasan, K., 1986, "Integrated instrumentation method of stress state, material property and deformation measurement for stress control method of mining," invited paper, 5th Conference on Ground Control in Mining, West Virginia University, Morgantown, WV, June 11-13. Serata, S., and Kikuchi, S., 1986, "A diametral deformation method for in situ stress and rock property measurement," International Journal of Mining and Geological Engineering, Vol. 4, pp. 15-38. Serata, S., Preston, M., and Galagoda, H.M., 1987, "Integration of finite element analysis and field instrumentation for application of the stress control method in underground coal mining," Proceedings, 28th US Symposium on Rock Mechanics, Tucson, AZ, pp. 265-272.

Jan 1, 1993

By B. Stewart, J. R. Warneke

The productivity of underground mines has increased dramatically since the introduction of continuous miners. A variety of new hazards have developed as a result. In the spring of 2004, Mine Health and Safety Administration (MSHA) held a workshop to brainstorm ideas to decrease the number of injuries associated with continuous miners. One of the main areas of discussion at the workshop was “trailing cable-handling injuries.” The method of handling the power cables over the years has changed very little while the technology and uses of continuous miners has advanced dramatically. This paper will discuss the main ideas brainstormed at the MSHA continuous miner (CM) trailing cable handling workshop and the history and root causes of cable-handling injuries, as well as proposed ideas developed at the National Institute for Occupational Safety and Health (NIOSH) to alleviate some of the cable handling issues.

Jan 1, 2006

By W. W. Simpson, S. A. N. Sheya

A procedure was developed by the U.S. Bureau of Mines for recovering gold, silver, cobalt, copper, and zinc from a massive sulfide ore by a hydro-metallurgical process. The procedure consists of (1) oxygen pressure leaching; (2) iron, arsenic, and copper removal from the leach solution by precipitation; (3) selective extraction of cobalt and zinc from solution; (4) electrodeposition of the cobalt and zinc from the strip liquor; and (5) cyanidation of the pressure leach residue to recover gold and silver. The results are discussed in terms of efficiency of metal recovery and conclusions drawn as to possible benefits and broad applications of the process.

Jan 1, 1990

By H. Maleki, G. Tetreault

This study was initiated by the US Bureau of Land Management (BLM) to develop guidelines for determining the maximum economic recovery of resources in coal mines. The work was in response to a requirement in the Mineral Leasing Act of 1920 and Federal regulations. The intent was to address the economic rainability of small, irregular reserves in existing longwall mines. In particular, there was a need to determine if room- and-pillar mining using a continuous miner (CM) was economically sound or whether unconventional (short or odd-shaped) longwalls could be used to recover small coal reserves economically. Small reserves, called "widgets " are left in longwall mines on one side of the mains near outcrops and adverse geological conditions or near any other location where reserve geometry does not lend itself to mining with a rectangular longwall panel. The work included the analysis of the geologic, geotechnical and economic factors that influence the recovery of small coal reserves; the analysis of historic changes in supply, demand and coal prices; the development of typical cost models for room-and-pillar and longwall mines; and the development of a practical methodology for determining maximum economic recovery. The methodology included an evaluation of the ratio of coal mined during longwall mining to that mined for development (LDR), as well as costs of maintaining coal quality depending on market conditions. The LDR is a good indicator of mine efficiency and overall coal recovery in modern longwall mines and, thus, is used to evaluate the increased costs associated with adding new development sections for extraction of small reserves. The study examines the economic feasibility of using unconventional longwalls for the recovery of medium-sized reserves, depending on site-specific geologic and geometric conditions.

Jan 1, 2002

By N. Hoffman

Accurate, repeatable density measurements of a coal-magnetite-water slurry are difficult to achieve using a nuclear density gauge. Changes in the coal-to-magnetite solids ratio cause fluctuations in the readings of nuclear gauges. To investigate this problem the Electric Power Research Institute's Coal Cleaning Test Facility compared the performance of a nuclear density gauge on a coal-magnetite-water slurry with the performance of a differential pressure gauge modified with a new pressure sensor. A second aim of these preliminary tests was to determine if the differential pressure gauge is also sensitive to the type of solids in the slurry. This paper explains current slurry density measurement practices, describes the nuclear and differential pressure gauges used in the CCTF tests, and presents test methods and results.

Jan 1, 1986

By M. G. Ayat

Although other methods of mineral concentration have been developed over the years, gravity separation remains one of the most efficient and economical for cleaning coal. The concentrating table and the spiral separator are popular devices used for the separation of minerals by exploiting the differences in specific gravities of the product material and the gangue. While the former device has been servicing the coal industry for over 75 years, the latter seems to have not been employed extensively for coal cleaning purposes in this country. As far as coal preparation is concerned, both separatory devices seem to be most efficient for intermediate to fine size fractions. As it stands there exists a great deal of confusion amongst preparation engineers and plant managers as to whether spirals can have a place in the coal industry. If so, whether their come back is the beginning of the end for concentrating tables, or can they be employed along with concentrating tables to contribute toward more efficient cleaning processes resulting in an improvement in the overall economics of the coal preparation industry. This paper examines the efficiency of both systems for coal processing operations as well as the basic principles, operational variables, economics, advantages and disadvantages associated with each unit operation. Attempts have been made to draw conclusions and make recommendations as to which system would be more beneficial for coals of known characteristics.

Jan 1, 1986

By J. M. Applegate, C. L. Morgan

Introduction In the same way that a blueprint communicates informa¬tion about a structure, a systems architecture should provide information that guides the construction and implementation of a computing system. Taking the blueprint analogy a step further, a plot plan can also show where, in the "bigger picture," a particular design fits (if in fact it does) and what a builder needs to know about the environment in which he or she will operate. In the context of business systems, a meaningful architecture should convey the following: • the primary purpose of computer-based systems rela¬tive to particular tasks or operations, • the relationship of the systems to each other and an indication of their interaction and dependencies, • the relationship of the systems relative to the organiza¬tion and its objectives, • indications of where IS/IT resources can best be allo¬cated to support the organization and • the overall context in which new systems and technolo¬gies can be assessed for both their impacts on current systems and on the organization itself. In theory, a well-designed systems architecture should allow an organization to focus its resources on those aspects of its business that matter most, thus, leveraging investments in information technology to a competitive advantage. In addition, the way that a computing systems architecture is represented should be un¬derstandable to non-IT staff, and it should be eas¬ily recognized by the people it supports. This pa¬per attempts to show that a meaningful systems model exists and that its applica¬tion to mining can achieve the desired results. The following discus¬sion is based on the au¬thors interpretation of a concept referred to as the computer integrated manu¬acturing (CIM) model, as developed by Allen-Bradley. An inherent strength of the CIM approach is that the model combines aspects of business-reporting structures with the manufacturing process itself. What results is a systems frame¬work that is aligned with relevant business processes and is, therefore, easier for non-IS/IT personnel to interpret. The successful application of the CIM model can be seen in a large number of both discrete and process-manufacturing facilities throughout the United States. This paper provides a brief overview of the CIM model and then describes how the model can be applied at a conceptual level to the mining industry. Finally, this paper proposes an extension to the CIM model that the authors believe will make it easier to understand and apply. CIM model As shown on Fig. 1, the CIM model begins with the most detailed levels of process equipment and works its way up to the highest level of consolidated financial reporting. Systems at each level are characterized by common attributes, users, time frames, etc., providing a clear picture of their interac¬tion. Further analysis of the relationships between systems and between levels provides insight into the opportunities for integration. Regardless of the industry or processes involved, the CIM model provides a framework in which the characteristics of systems and the data they manage can be predicted based on the nature of the business function they support. In general, as data moves upward from the lower rungs of the CIM model, it changes from de¬scribing the physical na¬ture of a process to describ¬ing its financial aspects (e.g., from productivity to cost). The time frame to which data applies also transitions from a very short duration, perhaps only milliseconds, to financial or regulatory reporting time frames that may span years. In a simi¬

Jan 1, 2000