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By Yinan Zhang, Yi Luo

The widely used R70 method is modified to measure the self-heating propensity of low-rank coals. This modified R70 method enables the introduction of controlled amount of moist oxygen into the reaction vessel. Three coal lumps were collected from three different locations in a surface mine in the Powder River Basin. The coal samples were tested in oxygen flow with controlled moisture content under adiabatic condition. By measuring the relative humidity at the exhaust exit point of the testing setup, the flux and cumulative wetting heat that is consumed by coal samples can be determined. Through a better way of determining the coal’s specific heat, the total heat, including heat of wetting and coal’s oxidation heat, required to raise coal to a given temperature can be determined. Then, the contribution of heat of wetting at the different stages of the testing is quantified. The effects of evaporative heat through a group of tests have also been quantified. From this research, a better understanding of the effect of wetting heat on inducing low-rank coal’s spontaneous combustion can be acquired.

Nov 30, 2022

By R. Kahrger

This paper is written to convey the latest developments in compact bucket wheel excavators (BWE's) operating in medium-hard rock and will serve to indicate that BWE and compact machines in particular do in fact have application in materials other than loose sandy soils and soft rock. A recently run extensive three month field test in hard marl, which was previously considered too hard and difficult to be handled by a BWE, is used as an example to explain some of the design requirements and problems associated with digging harder materials.

Jan 1, 1990

By Larry S. Diaz

The paper considers the selection of control instrumentation for a modern flotation plant, as well as the best interpretation and most effective use of the process data obtained. Process control computer availability is considered from the outset. A general philosophy of control is proposed which leads toward a system that is its own reliability monitor. The bulk of the problems are in grinding and classification. Alternative control methods are described that use particle size measuring devices. Flotation controls, based to a large extent upon on-stream X-ray analysis, are reviewed in detail. Reagent control methods are also examined. Methods to analyze the data obtained from the various measurement devices are introduced. These methods would enable an estimate of the validity of the data and require some redundant information. Another objective of these methods is the protection of operating equipment from possible control malfunctions. Although the discussion generally considers some degree of computer usage, this paper attempts to describe instrumentation and data analysis methods that enable control with or without the process control computer.

Jan 1, 1972

The Yanacocha Project is the first foreign investment in Peruvian mining since Cuajone (1976). Three years after the project began, it has become the largest producer of gold from heap leach operations in the world and the top producer in Latin America. The success of Minera Yanacocha (MYSA) opens a new chapter in Peruvian mining with the exploitation of its widely spread gold deposits and has attracted the interest of foreign investors in Peru's ample mineral resources. Construction began on August 1, 1992 and after twelve months of arduous work, the first gold bar was poured on August 7, 1993 from ore from the Carachugo mine. In 1993, Minera Yanacocha produced 81,000 ounces of gold and 304,000 ounces in 1994 (40% above budget). Production is expected to exceed 500,000 ounces in 1995 with the start-up of operations in the Maqui Maqui mine. This paper presents a summary of MYSA's experiences during its first two years of operations in the areas of mining, ore processing, environmental protection, loss control and community assistance. The paper also shows that MYSA's successes are not only due to the richness of the deposit, but also to the combination of a number of factors basic to the project's success, such as: an economic policy favoring investment in Peru, the availability of highly qualified local personnel to facilitate the transfer of technology from the United States and the desire and determination of the partners to carry the project forward in an initial atmosphere of uncertainty and terrorism.

Jan 1, 1996

The implementation of NAFTA in January of 1994 was expected to have small but beneficial effects for the Mexican economy, mostly through increased investment flows. Mexico's mining industry was especially likely to benefit, as mineral investment funds would be diverted to the now safer Mexico and away from similarly endowed but more risky Latin American mineral economies. The results of the past two years have shown that it is governments and macroeconomic factors that influence investment flows, rather than the fine-tuning of trade flows through so called "free-trade" agreements.

Jan 1, 1996

By Charles A. Beasley

Increased technical and legislative analysis by all parties of interest could result in more efficientand better directed regulatory legislation in the mining industry. Efforts to forestall or frustrate legislation through massive lobbying and public relations efforts are seldom effective over time and often lead to more stringent and far reaching legislation than necessary. The Federal Coal Mine Health and Safety Act of 1969 is perhaps an outstanding example of such insufficiences; a future example may well be regulatory surface mine legislation. Although a lack of extensive hard data seldom enables rapid or sophisticated analysis early in the legislative process, even preliminary analysis may be sufficient. Simple statistical analyses of available data, assessment of the legislative rationale, and subjective appraisal of other non-quantifiable constraints to improved mine safety. An average of 115 underground fatalities at an exposure frequency rate of 0.67 can be reasonably expected in the immediate future, under existing levels of technology, degree of regulation, and economic conditions. If gross unrefined estimates of 6 preparation plant, 5 surface, and 30 strip mining fatalities are assumed, the total fatality industry level could be expected to approximate 156 Serious professional, economic, and technical constraints within the the industry probably preclude any major decrease of these accident levels within the near future

Jan 1, 1972

By N. Edmonson

Apart from its role as an essential input to a wide array of agricultural chemicals and industrial processes, sulfur is interesting in that its supply involves competition between primary product and by-product. This general production structure is found repeatedly among markets for metals and other industrial minerals, and research results from the sulfur market potentially carry over to other markets with similar structures. The purpose of this paper is to present an analysis of the recent and prospective market for sulfur. The analysis will rely heavily on simulation using a comprehensive model of the North American sulfur market developed by the author. A brief description of the model is offered by way of introduction

Jan 1, 1993

By W. H. W. Husband

Rock salt has been mined by the solution method for many years in many countries. Attempts have been made in the past in Canada and various other countries to produce potash by the' same method. However, only Kalium Chemicals Limited (1) has been successful, possibly because the conditions in Saskatchewan are the most favorable conditions to be found so far for the development of a solution mining method for potash. There are significant differences in solution mining of rock salt and solution mining of potash. First, rock salt deposits are relatively pure in respect to soluble minerals, whereas potash is never found in the pure state and contains Substantial amounts of other soluble minerals, particularly rock salt. In comparison to rock salt, much less potash is dissolved and brought to the surface for the same amount of water circulated through the orebody. The amount of water to be evaporated per unit weight of product is a major difference. Much greater amounts of water must be evaporated when producing potash and the treatment of the brine is more complicated because other dissolved salts have to be separated. Secondly, the rock salt deposits, particularly the domes, are much thicker. Bed thickness is of prime importance because it determines the yield of a well and consequently the economics of the process. Furthermore, as rock salt provides a strong roof structure, larger cavities can be developed and this prolongs the life of the rock salt well.

Jan 1, 1971

By R. Rodgers

The Pinto Valley Concentrator of BHP Copper Inc. restarted its sulphide mining operations in September 2007 to produce copper and moly concentrates. During the plant production ramp up, the copper/moly circuit quickly reached the copper grade and recovery targets, but the production and quality of the moly concentrate continued to be a challenge. Even though several improvements in the moly circuit were completed, the final moly concentrate did not meet contractual specifications. After reviewing several options to improve grade and reduce contaminants, the installation of three flotation columns was chosen. The column design and construction were done utilizing in-house craftsmen and engineers. Ten days after commissioning, the columns successfully reached a steady operation and began producing moly concentrate to the required specifications, that is, high moly tenors and low copper and iron content. In this paper, the operating parameters, mass balance, design, installation, commissioning and operation of the new flotation columns will be discussed.

Jan 1, 2010

By B. Simser, T. Butler, A. Hall

The longterm future of Glencores’ mining operations in the Sudbury basin area of Ontario, Canada likely depends on mining deposits at depths below two kilometres. To gain a better insight into the rockmass response to mining, a geological scouthole program has been implemented at Glencores’ Nickel Rim Deep and Onaping Depth Project to gain insight into rockmass conditions ahead of the devel-opment face. The scouthole program involves drilling long (up to 600 m) subhorizontal boreholes drilled ahead of the development end and collecting data about the rockmass conditions from various geophysi-cal and mechanical tools (in addition to conventional core logging). Once all data has been collected and the borehole is available, seismic sensors are installed up to 450 m down the hole as part of the micro-seismic monitoring program with the leading sensor always located ahead of the development end. The recorded seismic data is used to provide realtime insight into the rockmass response to mining. On May 20, 2017 a flurry of seismicity with a maximum moment magnitude (Mw) of 0.7 occurred causing damage to the ramp heading. Data from the microseismic monitoring system had indicated that conditions at the development end were changing prior to the rockburst. A back analysis of the scouthole data indicated a clear anomaly in the rockmass at the location of the rockburst. The scouthole data also provided sufficient information to suggest that once this anomalous zone was exited, mining conditions would improve. With the microseismic monitoring system providing realtime information from the rockmass, the area was re-habilitated and ramp development continued successfully. Details of the rehabilitation and adjustments to the ramp development are discussed. Some correlations between the scouthole data and recorded micro-seismicity are also presented.

Apr 26, 2022

By Jill Murray

This study focuses on the amosite mining region in South Africa and associated health effects, compared to other mined asbestos fiber types. Historically, dust and fiber levels were high in the amosite mills and mines, and many miners and members of the surrounding communities were exposed to the fibers. Research has shown that amosite produces both benign and malignant disease. Nevertheless, the mesotheliomagenic potential of amosite is several fold lower than crocidolite. The risk of disease associated with amosite exposure is difficult to quantify. Reasons for this include the scarcity of available information, including fiber measurements, and case ascertainment, as well as the juxtaposition of the amosite and crocidolite asbestos seams in South Africa. © 2007 Elsevier Inc. All rights reserved. Keywords: Amosite; Mesothelioma; Crocidolite; South Africa; Asbestos

Jan 1, 2007

By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By Raymond A. Bradbury

Martin County Coal Corporation operates three underground mines and two surface mines on Wolf Creek in Martin County near Inez, Ky. The original underground development was begun in March of 1970. The property being developed is leased from Pocahontas Land Corporation. The A. T. Massey Coal Company, whose offices are located in Richmond, Virginia, is the parent company and sales agent for Martin County Coal. Duke Power Company is the customer who will take all the production from the mines which ultimately are scheduled to produce 2,500,000 tons annually. The Norfolk and Western Railway Company built a 24-mile railroad into this huge reserve of low-sulfur steam coal. Four coal seams, all above drainage, are included in the lease. The Middle Coalburg and Stockton seams are being deep-mined now and it is in three mines that the diesel haulage equipment is used. Those of you who attended the AIME meeting in Birmingham last October or the Diesel Symposium in Pittsburgh in January of this year are familiar with the introduction of trackless diesel-powered haulage equipment into our Martin County mines. I made a presentation at each of those meetings which dealt with our first experience with Wagner Mining Equipment haulage units. These machines are sold exclusively by Lake Shore, Inc. whose offices are in Iron Mountain, Michigan.

Jan 1, 1973

By C. C. Jobes, J. J. Sammarco, D. L. Anderson

Computer-aided control of a mining machine places its operator in a safe, remote location, thus reducing health and safety risks. Sensing systems that provide machine position (xy coordinates) and heading (yaw) are extremely useful in aiding remote positioning of mining machines. The US Bureau of Mines (Bureau) developed two sensing systems for position and heading information: a scanning laser system based on the Lasernet sensor and a mechanical position and heading system based on linear-position transducers. The Bureau is also investigating a system from Honeywell, the modular azimuth and positioning system (MAPS), that employs ring-laser gyroscopes (RLGs). This paper presents a brief background and status of these sensing systems as applied to a continuous mining machine (CM). Included are field test results off each system operating in a room-and-pillar research section at a cooperating West Virginia mine.

Jan 1, 1993

By R. D. Beard

Puerto Rico lies within the remnants of a deformed Cretaceous island arc system in the northeastern Caribbean. The Island can be divided into three broad geologic provinces: the Central Volcanic-Plutonic Province (Lower Cretaceous to middle Eocene), and the Northern and Southern Limestone Provinces (early Oligocene to middle Miocene). Known precious metal deposits are generally small and occur in veins and shear zones within Lower and Upper Cretaceous volcanic and plutonic rocks. Some Tertiary igneous rocks are also mineralized. Selected indications of disseminated lithology-controlled mineralization could represent larger deposits. Associated metals in some deposits include copper, zinc, and lead. At present, tax policies, population density, political outlook, and lack of proven significant precious metal deposits discourage the establishment of a metal mining industry.

Jan 1, 1993

By W. P. Barnett

In 1988, the U.S. Department of Energy's Pittsburgh Energy Technology Center identified three coal cleaning options for achieving flexible environmental control strategies aimed at reducing energy-related SO2 emissions. These are selective agglomeration, advanced froth flotation, and advanced cycloning. Each technology relies on maximum liberation of pyrite and other mineral matter through feed coal comminution to fine and ultrafine sizes. Research projects designed to expeditiously develop each of these technologies to the point of commercial viability were initiated. This paper will present the status of these projects and the application potential of each technology to coal beneficiation.

Jan 1, 1992

By Seppo] [Kreula

Outokumpu Oy has acquired considerable experience with on-stream X-ray fluorescence analyzers and with computer control of flotation processes over several years. It became evident at the outset of this work that a reliable and accurate on-stream analyzer was more than a collection of different pieces of hardware linked together. Extensive work was done to develop an integral analyzer system, beginning with process samples through the spectrometer to report typewriters, recorders and the control computer. To date, over ten Courier-300 analyzer systems based on this development have been installed world-wide, several of which provide the key information for successful computer control systems. Computer control of flotation processes has been under development at the Pyhäsalmi concentrator since 1968. Two different control strategies have been implemented. The copper flotation is controlled by means of a mathematical model and economic criteria, whereas the "evolutionary operation principle" is applied to the zinc flotation. The computer control system installed at' the Vuonos-mine has been developed according to the same guidelines. In order to consolidate this wide experience, a flotation computer control system, Proscon-100, was developed by Outokumpu Oy, and the first system was installed at Kotalahti in 1972. In addition to the technological experience, enough information has also been gathered to illustrate the economical, benefits accruing through the use of these advanced tools of automation.

Jan 1, 1973

By Charles E. Dandois

New is a relative term, and, when used with reference to a concept as old as shaft kilns can be applied to a number of designs. In this case the design that is the subject of this paper, is known as the ring or annular shaft kiln as developed by Mr. Karl Beckenbach of West Germany. The first&apos; operating unit was rated 185 tons per day and was installed in 1962. Today, there are approximately 84 units in operation in Western Europe and Japan. Twenty-one additional units are in the process of erection or on order. Developed sizes range from approximately 100 to 330 tons per day. Units of over 500 tons are in the design stage, however, the largest units presently operating are rated 330 tons per day, <the first: of this size having been installed in 1966. "Figure" 1 is an elevation view of the unit. It is a single vertical cylinder to which are attached the required service platforms, combustion chambers, injectors and distribution piping. Auxiliaries such as recuperator, exhaust fan and dust collector are mounted on the appropriate service platform. The charging pan, feed conveyor, etc. are mounted at the kiln top. At the bottom of the kiln is the silo with a vibrator type discharger, and mounted separately is the required blower for injector air and fan for internal cooling.

Jan 1, 1973

By G. A. Shirey

Breakthroughs in software technology and in computer hardware capabilities have opened new opportunities to develop more accurate process simulators and to reduce the operating time to reasonable levels. As a result, there are several new simulation packages being commercialized for modeling coal preparation plants and pulverized coal-fired power plants, and the users of these packages are reporting significant improvements in process efficiency and operating costs by implementing the simulators&apos; results. This paper provides an overview of some of the models currently in use at CQ Inc., including the ASPEN PLUS"" Coal Cleaning Simulator, the Ultramax® process optimization software package, and EPRI&apos;s Coal Quality Impact Model?. Case histories of specific applications are also presented.

Jan 1, 1995

By J. E. Gray

Before specifications are discussed it may be well to define the term "Mineral Aggregates." Professor K. B. Woods (1) defined "Mineral Aggregate--An aggregation of sand, gravel, crushed stone, slag, or other material of mineral composition used in combination with a binding medium to form bituminous and portland cement concrete, macadam, mastic, mortar, plaster, etc., or alone as in railroad ballast, filter beds, and various manufacturing processes, such as fluxing, etc. " This definition is too all inclusive for the purposes of this paper; therefore, this discussion will be confined to specifications for natural aggregates which means sand and gravel and crushed stone, and limited primarily to coarse aggregate which is aggregate larger than one-quarter inch in size. To the uninitiated, this may seem to be a very limited subject on an unimportant material. However, aggregates are essential in all types of construction. The tonnage and value of these two aggregates produced in the United States during 1959 as reported by the Bureau of Mines were as follows: Sand and Gravel 729,895,000 tons valued at $728,527,000 Crushed stone 581,721,000 tons valued at $824,411,000

Jan 1, 1961