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The floatability of a bituminous coal in NaG solutions was evaluated using a modified Hallimond tube to delineate the role of the electrostatic interaction between bubbles and particles in determining the coal hydrophobicity. Zeta potential measurements showed that bubbles are negatively charged in the entire pH range tested, while coal particles are positively charged below pH 6.0 and negatively charged above it. Also, both sodium and chloride ions were confirmed to act as indifferent ions without any specific effects for both coal particles and bubbles. Flotation as a function of pH exhibited a maximum and minimum at low salt concentrations which is shown to be determined mainly by the coal hydrophobicity as measured by a new hydrophobic levitation technique. At high salt concentrations (above 0.1 mole/dm3), the flotation without such maximum or minimum is controlled by the electrostatic interaction between the bubble and the particle.

Jan 1, 1992

The purpose of this paper is to present validation studies of the mine-fire simulator using data gathered from an actual mine fire which occurred in November 1991 at the Pattiki Mine. To develop the model of the ventilation system with the fire in this validation study, the following adjustments were made: (1) flow and gas distribution in the entire ventilation network, and (2) fire parameters matching the data recorded by the monitoring system. After close correlations between simulation and real data were achieved, additional analysis of the ventilation system with the mine fire was performed. Presented and discussed in this paper are the following stages of the fire at the Pattiki Mine: (1) early fire (before the fire was detected), (2) preparation for and fire fighting with water, (3) fire sealing, and (4) fire extinguishing. This study evaluates the suitability of the computer software package for modeling underground fires. The paper also discusses the importance of the on-line monitoring system for the validation process.

Jan 1, 1995

By Peter J. Szabo

In 1980, a caravan of representatives of Japanese trading companies debarked on the shores of the United States bearing gifts of watches, electronic games, and radios. In early 1983, we find in a parking lot of a major U.S. coal company, a haggard general manager of marketing returning to the Orient with a box under his arm of trinkets of his own; cross pens with company logos, alarm clocks, etc. The tables have turned, but our fellow sitting in a jet plane over the Pacific Ocean had only to heed the warning of the famous 19th Century poet well familiar with the ways of the Far East. Kipling said; "And the End of the Fight is a tombstone white and with the name of the late deceased, And the epitaph drear, a fool lies here who tried to hustle the East."

Jan 1, 1984

By R. K. Agarwal

In this paper a simple three-layered medium is considered. A circular hole is centrally located in the intermediate layer. The layered sheet is loaded uniaxially perpendicular to the stratification. The Young's modulus of the intermediate layer is lower than that of the outer layers. The stress distribution around the circular hole in a stratified medium is significantly different when compared to the case of a continuous homogeneous medium. The distribution depends upon the ratio of the height of [the] intermediate layer and [the] hole diameter. A comparison of stress the distribution and procedures for preparation and testing of [the] model are given. The potential of the technique is outlined.

Jan 1, 1968

By Jack J. K. Daemen

A wide variety of subsidence prediction methods exist. They can be classified into empirical methods and mechanistic models. The empirical methods include profile functions and influence functions (Brzuner, 1973a,b; Kratzsch, 1974; Berry, 1978; Hood et al., 1981), the two empirical approaches of most practical value, if only be- cause they are readily programmed on calculators or computers. The profile functions have the advantage that they allow for ready determination of the necessary empirical parameters from field observations. They have the disadvantage of being restricted to subsidence calculations at a very limited number of points or lines above very simple (rectangular) mine geometries. This reduces greatly their practical applicability for damage predictions, which usually require estimates of strains, slopes or curvatures at structures that have arbitrary position and orientation with respect to planned mine excavations. Influence functions can be used to calculate subsidence at any point near an excavation of any in- seam outline. The main difficulty associated with empirical influence functions is the lack of uniqueness in the relation between subsidence and its cause, the convergence distribution over a mined excavation and its immediate surroundings. A secondary practical difficulty is the need for fairly arbitrary adjustments near the excavation edges, usually in the form of compensation zones (e.g. Brsuner, 1973; Hood et al., 1981). Determination of the appropriate empirical constants in influence functions is facilitated greatly when a direct mathematical connection exists between influence and profile function (several examples are given by Brauner, 1973 and by Hood et al., 1981), so that field data can be used to determine the parameters through backfitting of the profile functions, which is considerably simpler and more direct than backfitting of influence functions.

Jan 1, 1982

By J. P. Morgan

The Vesta Preparation Plant of the Jones & Laughlin Steel Corporation is located on the Monongahela River, eight miles south of Brownsville, Pennsylvania. This plant is capable of cleaning 2400 NT/hr of a mixture of Pittsburgh seam high volatile coals from the Vesta and Shannopin mines to produce a metallurgical coal of 6.75% ash and a steam coal containing 14% ash. Heavy media vessels are utilized to upgrade the coarse coal while launders and tables. handle the -1/4" fraction of the raw coal feed. Cleaned -coal goes to boot classifiers where the +48 mesh material settles and is removed by bucket elevators. This 1/4 x 48 mesh material is then sent to centrifugal driers for dewatering. As designed, the minus 48 mesh fraction overflows the boot as a 7 to 8% solids slurry and is recovered by cyclones and a thickener and dewatered by filtration. The-products of the heavy media circuit, the launder-table-boot-drier circuit and the cyclone-thickener-filter circuit are combined to constitute the shipped metallurgical coal. This Vesta-Shannopin mix is combined at J&L's Pittsburgh and Aliquippa Works with purchased low and medium volatile coals for the production of metallurgical coke.

Jan 1, 1962

By Eugene E. Brucker

In recent years, there has been increased interest in construction problems presented by karst topography. Twenty-five years ago, karst areas were by-passed for development. Today, the high cost of land and population pressures are requiring utilization of karst areas. Areas exhibiting karst features can be satisfactorily developed so that construction can proceed in a normal manner; or the areas may be left undeveloped and the underground drainage system abused by improper use causing or contributing to structural collapse, excessive erosion, and a grave threat to the stability of land development and the environment. The term "karst" is a comprehensive term applied to areas underlain by soluble rock that possess a topography formed chiefly by the dissolving of rock and the diversion of surface waters to underground routes. There are four features which contribute to the maximum development of karst. 1. A soluble rock, preferably limestone, must be present at or near the surface of the ground. Occasionally, dolomite will suffice.

Jan 1, 1970

By Yuanhong Qi, Xun Fu Wang, Tao Fu, Kunkun Cui, Yingyi Zhang, Jie Wang, Junmao Qie

With the sharp decrease of sulfide nickel resources, the nickel laterite is becoming more attractive as nickel oxide, nickel matte, and nickel-iron. This study investigated the mineral phase structure, chemical analysis, thermal properties, and element distribution characteristics of the rotten rock layer deposited in the Southeast Sulawesi Ophiolite Belt. The results show that the nickel laterite deposited in Southeast Sulawesi Island, Indonesia, belongs to the typical high-nickel and low-iron garnierite-type laterite. The concentrations of nickel and iron of the nickel laterite are 1.99 wt% and 17.55 wt%, respectively. The serpentine, olivine, clay, chlorite, hematite, and magnetite are the major minerals, and the pyroxene, actinolite, limonite, and chromite are the minor minerals in the nickel laterite in Southeast Sulawesi, Indonesia. Serpentine and olivine are the main nickel minerals with an average nickel concentration of 3.65 wt% and 1.73 wt%, respectively. The Fe and Ni have homogeneity and symbiosis in the serpentine and olivine, and their concentrations are often positively correlated.

By T. M. Barton

Coal mine bumps the violent failures of over-stressed coal', present a safety hazard to miners when mining is conducted in deep, bump prone coal mines. Two different longwall gate entry systems were evaluated in a Southern Appalachian coal mine located in the Pocahontas No. 3 Coalbed under approximately 610 m of overburden which included a massive sandstone member. Both gate entry systems employed a center abutment pillar flanked by yield pillars. The original design employed a 24.4 m square abutment pillar' while the new design employed a 36.6 by 54.9 m' abutment pillar. Rock mechanics instrumentation data analysis and in-mine observations indicated that this increase in abutment pillar size significantly decreased bump potential. The new design in worse case conditions increased effective bearing area 62 pct with only a 9 pct increase in gate entry system width and eliminated face bumps that wer7 experienced with the original gate entry design.

Jan 1, 1991

By Floyd L. Prestridge

A test of a solvent extraction (SX) pilot plant featuring electrostatic coalescence has been performed by C-E Natco at the United Nuclear uranium mill in Church Rock, New Mexico. Operating in parallel with the United Nuclear SX system, the C-E Natco electrostatic SX pilot plant exhibited comparable extraction efficiency to the United Nuclear system which utilizes conventional mixer-settlers. The C-E Natco pilot, however, operated at much higher liquid loading rates and exhibited less communication between the aqueous phases of the extraction and stripping circuits.

Jan 1, 1983

By Andrew Trusiak

Brunswick Mining, employing approximately 1600 employees, is located 40 km south of the city of Bathurst in north eastern New Brunswick. The mine has operated as two lead-zinc operations - the underground mine(No.12) and the open pit mine (No.6). The open pit orebody is presently being' mined by underground methods. It is expected that the No.12 mine will furnish the entire ore supply by the end of 1981. The flotation practice prior to 1971 has been described by Neumann and Schnarr(1) and by Erskine (2). More recently, the current flotation practice has been described by McTavish(3) and deals with some major circuit modifications between 1972 and 1978. The period 1978 to 1980 has seen the completion of. a major flotation cell replacement and expansion program for the No.6 concentrator, and the implementation of computer control in the No. 12 CuPb and Zn flotation circuits.

Jan 1, 1981

By Steven W. Hunt, Glen R. Frank

Assessment of abrasivity and cutter life are necessary to properly manage risks when tunneling in mixed face ground which includes ground with cobbles and boulders. Maximizing cutter life requires: (1) abrasivity and strength parameters for soil matrix and rock clasts, (2) methods of combining both, (3) proper selection of cutters and (4) modified TBM operation including use of boulder detection methods from the TBM to help make operation decisions. This paper presents approaches for addressing these factors sufficiently to improve tunneling success in mixed-face and cobbly-bouldery ground. Current laboratory abrasivity testing will be assessed along with equivalent quartz content correlations to soil matrix and rock clast abrasivity. New approaches to combining abrasivity testing of both the soil matrix and rock clasts for various cobble and boulder volume ratios will be suggested to estimate cutter life and intervention intervals. Methods for detecting boulders and using detection data to modify TBM operations to minimize boulder impacts are provided.

Jun 13, 2021

By S. G. Britton

Microcomputer analysis has long been a technique for engineering professionals to improve the theoretical and practical design of continuous mining systems. Such work has been typically composed of modeling observed events and then introducing a variety of known elements with predicted results to compare against the results of the model. Programs written in BASIC, Cobol, Fortran, or other language dominated such efforts. These programs have taken years to develop and prove out. This paper explores a new management tool used at TMC on a daily basis to track and improve continuous mining systems through the use of microcomputers and Lotus 1-2-3 software. By analyzing data provided by section foreman, shift foreman, and maintenance personnel against predetermined goals, new production targets are developed, weaknesses in the current mining systems are identified, and the results of changes are measured. The results of this system on the productive output of TMC systems are on the order of ten percent improvement.

Jan 1, 1991

By Denys B. Smith

Electric logs and cuttings records from Zechstein 3 and 4 strata in boreholes in the British Sector of have been interpreted in the light of numerous cored boreholes through this sequence in north-east England. This interpretation shows that potash salts in the two cycles are thickest and most consistent in a belt 20 to 40 km wide parallel with and a few kilometres from the present basin margin, and are here generally similar in grade to those known onshore. The potash ores in both cycles are mainly of sylvinite in onshore areas, the layered Upper the Southern North Sea Potash of the fourth cycle being rather less variable but generally of appreciably lower average grade than the Boulby Potash of the third cycle. Potash salts in both cycles are highly variable in thickness and grade in basin centre areas where they have been grossly affected by diapirism of the thick second cycle salts.

Jan 1, 1978

By G. Argyris

A number of important studies, ongoing environment monitoring efforts and mining and road construction projects in the lignite based electrical power production area of Amyntaio ? Ptolemais in North West Greece require an accurate and up to date model of the topography. In recognition of the importance of such a model, a project was initiated by the Laboratory of Mining Information Technology and GIS Applications in the Department of Geotechnology and Environmental Engineering of the Technological Educational Institute of Western Macedonia. A massive surface triangulation model was generated from vector data using an optimized Delaunay based method. Combined with aerial and satellite imagery, the triangulation model provides a complete 3D terrain model of the area characterized by high levels of accuracy, detail and realism. The generated model is easy to modify with new data in order to improve its detail and keep it up to date with ongoing earth moving and development operations in the area.

Jan 1, 2008

By D. Gove

All mining operations using trucks have a common need to properly match the number and size of hauling units (trucks. wagons. scrapers. etc.) to a loading unit (wheel loader. hydraulic shovel/excavator, cable shovel. push tractor. etc.) to provide the best possible fleet match. Optimizing fleet match minimizes the cost per unit of material moved by that fleet. As haul conditions change (haul length. grade. or rolling resistance), there may be need to adjust the number of trucks to maintain the optimum fleet match. Fleet Production and Cost is a tool which, among other things, can be used to optimize the truck-loader match.

Jan 1, 1994

By S. V. Krishnan

In the upgrading of finely-disseminated iron ores, selective desliming is the critical step which must be controlled in order to achieve efficient flotation. A prerequisite for selective desliming is a properly-dispersed pulp; sodium silicate is commonly used as a dispersant. The mechanism by which sodium silicate acts as a dispersant in the presence of calcium ions was examined by streaming potential measurements, settling tests, abstraction density determinations, selective flocculation tests and scanning electron microscope observations. The study established that calcium silicate precipitates on the mineral surfaces dispersed the pulp. Although sodium silicate was a nonselective dispersant, the addition of corn starch aided the flocculation of goethite over quartz at low silicate additions, but became ineffective at higher silicate levels. A model is presented to explain the dispersant mechanism of sodium silicate in the presence of calcium ion for selective flocculation of iron ores.

Jan 1, 1982

By William R. Barton

The domestic portland cement industry consumes more than 12 million tons annually of raw materials chemically similar to fly ash. How these materials are used and how fly ash can serve in their place are discussed. Factors influencing whether or not a particular plant will use fly ash in place of an alternate material are discussed.

Jan 1, 1968

By D. A. Fenton

The reliability of large diameter, high horsepower ball mill is paramount when large production and minimum downtime is required. The 17 ft. x 56 ft. double compartment ball mill at St. Lawrence Cement Company has the first gearless drive built in North America and has the world's largest hydrodynamic bearings currently built and running. The machine has seen three years operation and has met its specifications. The mill was designed by Aerofall Mills Limited and the gearless drive built and designed by the Canadian General Electric Company. This paper discusses the operation of the first North American installation of a gearless drive ball mill from the mechanical, electrical and process aspects.

Jan 1, 1977

By A. Ardiant, C. E. F. Mumbunan, I. Irawan

As a part of mine operation’s success key, Community Development nowadays seems to be a rule of thumb. Not only is for a short term need of the company during their operation but also for the national public opinion on the presence of the mining industry to a certain region. Nanggung region which is only a 2-hour drive from Jakarta, brings the challenges to Antam’s gold mine business in the areas such as illegal miner presence, easy access to the mine area as it is very close to the community, and national political sensitivity considering its proximity to Jakarta. The company allocates about 3%of its total operational cost annually for Community Development pro-gram. The program is derived through SWOT analysis and broad involvement of all community components to assure that the allocated fund is addressed to the right place. In the year of 2002, the company has successfully established a conducive-relation with the community.

Jan 1, 2004