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By William A. Kneller

A considerable range of composition exists in rocks that have been described as chert, jasper, or flint. Their composition may be opaline, chalcedonic, quartzose, or mixed. Certain cherts, when incorporated in concrete, are known to possess nondesirable thermal and chemical properties. The inability of chert to withstand thermal shock above the freezing temperature of water is an example of such a property. Cryothermal reactions may cause disintegration of concrete, due to repeated cycles of freeze and thaw. Thermal properties are significant because small temperature changes may cause inordinate expansion and resultant fissuring of concrete. Freezing of entrained water in chert may cause excessive physical failure in concrete. Some cherts react chemically with alkalies liberated during the hydration of the cement, with resultant cracking and deterioration. Sources of concrete aggregate in Ohio have been viewed with suspicion because they contain considerable chert derived from Middle Devonian and Pennsylvanian carbonate rocks. Light-colored porous cherts from the Middle-Devonian Colum- bus Limestone exhibit the least freeze-thaw durability of the samples studied. Denser cherts may also yield to freeze-thaw stresses, but tend to be more susceptible to thermal shock. Cherts rich in opaline and chalcedonic silica usually exhibit alkali-aggregate reactivity.

Jan 1, 1966

By V. Srajer

The loading and hauling equipment simulation model was developed to satisfy, the requirements and need of the mining industry in western Canada. It is expected the model will be used to determine the' impact of various combina¬tion of loading and hauling equipment, company policies and maintenance procedures, haulage requirement, to evaluate possibilities, of the use of truck monitoring and dispatch systems, and to access loading and hauling equipment productivities. To evaluate the model, and to access its capabilities in addressing the above requirements, the model was validated. The validation was based on the following: 1. Running the model in-house to evaluate its structure, 2. Running the "test case" by timing models developed elsewhere to compare the results of simulation, 3. Soliciting of model critique from outside agencies, and 4. Comparison of calculated data with real time study data. The presented paper provide overview of the validation processes and summarize" results obtained during comparison and evaluation studies.

Jan 1, 1989

By Chen Chuanqing

The Mining design system is a CAE (Computer Aided Engineering) software and was developed as designer-oriented, interactive mode software to perform geological and mining design calculation and graphics. To perform geology and mining design, the deposit model files created by the software "Deposit Modelling System", are transferred to the environment of graphics support software, then a specially developed drafting submodule can be selected to proceed to interactive graphics design. If it is necessary to calculate the grade and quantity of a particular part of the ore-body, another submodule will be called and run. The resulting file is 'transferred back, and the recalculation program takes the data from the file and refers to the deposit model file to create a summary reserve report: The minimum hardware configuration of the system are IBM-AT Basic work station with high resolution graphic monitor and peripherals needed are digitizer, plotter, printer.

Jan 1, 1989

By A. Marabini, G. Belardi, N. Sheau, F. Veglio

The present paper deals with the modelling of a Multi-gravity separator in the treatment of chromite fines. A first screening study was carried out by 2" full-factorial experiments in order to check the main effects and interactions among the investigated factors: shake frequency, shake amplitude, tilt angle and washwater flowrate were taken in consideration in the study. Two size fractions were employed in the experimental tests. Successively, considering the factor with larger influence on the Cr203 and SiO2 grade and Cr203 recovery in the concentrate, a further improvement of the experimental design was performed to determine empirical models to describe the behaviour of the MGS in the mineral treatment. The results show how intrinsic interaction among the factors take place, highlighting that an optimization study must be carried out considering all the MGS setting parameters.

Jan 1, 1995

By R. N. Chakravorty, R. J. Kolada

Explosions of methane in coal silos and coal ships is an ever present hazard. Recent investigations have shown beyond question that considerable accumulations of methane do occur in coal storage silos and numerous recent explosions in coal transport shipping strongly indicates that the same conditions also exist in ship storage holds. Investigations have shown that the main concentrations of methane occur within the actual coal pile. Within this region normal silo and ship ventilation systems are ineffective. The main 1ine of defence is therefore to exclude potential sources of ignition or to place the coal in an inert atmosphere, or both. This paper presents the results of a methane survey of all operating silos in Western Canada. These results demonstrate that a serious and widespread hazard of explosion exists. This paper also discusses various methods by which this hazard may be reduced including methods of venti1ation, inertization, microbiological control and early warning systems.

Jan 1, 1987

By S. Y. B. Subbarao, K. Ravindranath

Lead and Zinc concentrates are being recovered at Rajpura- Dariba (Distt. Rajsamand, Rajasthan, India) from a complex multi metal sulphide deposit since 1984 by selective flotation employing a large number of reagents. The cost of concentrates' production has been high. Due to the increased availability of concentrates world over and to be competitive, it is necessary to reduce cost of production. An effort has been made by the R.D. Department of Hindustan Zinc Limited to bring down the cost by resorting to production of Bulk Pb + Zn concentrate with enough Ag to make it attractive to the smelters. This paper gives an account of open cycle testing and locked cycle testing in the Dowa Continous Mini Flotation unit. The metallurgical data generated in the mini flotation unit indicate the possibility of obtaining smelter-acceptable bulk concentrates containing Pb+Zn 45%, Ag 400 ppm and graphite carbon about 3%. An in-plant trial in the 3000 TPD concentrator indicated that there would be savings through dispensing with and reduction in some reagents, lower power requirement, etc. Also, a substantial increase in revenue is expected due to higher recoveries by resorting to bulk concentrate production as against individual concentrates.

Jan 1, 1995

By Erich U. Petersen, J. B. Hiskey, William J. Tafuri, Donald M. Hausen, X. H. Jiang, Douglas N. Halbe, G. Ramadorai

The extraction of gold from chloride solutions with activated carbon is examined. It is shown that the uptake of gold by activated carbon from chloride solution follows a mechanism whereby gold is reduced to the metallic state. Metallic gold appears as deposits both on the carbon surface and in pore space within the carbon particle. The deposition rate is dependant on the carbon particle size and pH. At low initial gold concentrations, the initial rate is insensitive to gold concentration. Sodium hypochlorite exhibits an adverse effect on the reduction reaction. The overall loading and initial rate of reduction are both decreased in the presence of NaC10. The effect of iodide on the loading of gold was also examined in an attempt to overcome the superficial deposition of gold on carbon.

Jan 1, 1990

By R. Gong, R. Bhaskar

A coal mine study was conducted to evaluate the effectiveness of a compressed-air, foam spray system installed under a continuous miner boom and directed to cover the pan and the gathering arm. The study's objectives were to evaluate the foam, underboom sprays' effect on: • the respirable dust concentration in the ambient air, and • the quartz concentration in the airborne, respirable dust. The foam generation and delivery system's engineering design is described in the paper, followed by descriptions of the mine and the dust sampling strategy. The data were analyzed to study the foam's effects on respirable dust and quartz concentrations at the continuous miner cab, the face return and the intake. The data indicate reductions in the dust's quartz content, ranging from 19.7% to 64.6%, in eight of 11 comparisons of the foam vs. no foam cuts. In addition, airborne intake dust reductions were observed in eight of 11 comparisons.

Jan 1, 1993

By S. K. Kawatra, S. T. Bagley, T. C. Eisele

The use of the bacteria Thiobacillus ferroxidans to catalyze pyrite dissolution in coal is well known, and recent investigations have shown that T. ferrooxidans are also capable of rapidly altering the pyrite surface to facilitate its removal from coal by froth flotation and oil agglomeration. However, the effect of reactor design on the bacterial leaching rate is poorly documented, and the ability of bacteria other than T. ferrooxidans to affect pyrite flotation has been unknown. In this study, the effect of a number of different microorganisms on the flotation of unoxidized pure mineral pyrite has been investigated, and it was shown that organisms other than T. ferrooxidans are also capable of depressing pyrite flotation. In addition, comparative studies of leaching in shake-flasks and pachuca tanks have shown that the pachuca tanks allow leaching to proceed to a greater degree and at a significantly accelerated rate.

Jan 1, 1989

By J. C. Norman

The boron review arrived too late to appear in the June issue. The United States was the world's second largest producer and the largest consumer of boron compounds during 1991. According to the US Bureau of Mines, boron mineral concentrate and chemical production in the US totaled about 1.1 Mt (1.2 million st), yielding about 608 kt (670,000 st) of BO, in 1991. Total estimated value was $440 million. That level of production was equal to 1990 revised production figures. Value was greater by $37 million, however, reflecting a strengthening of boron product prices. The US continued to supply essentially all its own boron while maintaining a strong position as a source to foreign markets of sodium borate products and boric acid. Domestic employment in the mining and beneficiation of boron products in 1991 remained at 1100 people, about the same level as in 1989. The Bureau of Mines estimated total world production of boron in 1991 - mineral concentrate and chemical - at about 2.9 Mt (3.2 million st). That corresponds to about 1.2 Mt (1.3 million st) of BO ,. World production in 1991 was about equal to revised 1990 levels. US production Mines and processing operations in southern California were the only domestic sources of boron mineral concentrates and chemicals in 1991. US producers, in order of quantity of production, were US Borax and Chemical Corp., North American Chemical Co., and American Borate Co.

Jan 1, 1992

By J. S. Walker

Public Law 95-87 enacted by Congress in 1977 and subsequent regulations require coal mine operators to predict the effects of mining on the environment prior to the start of mining. Prediction of the effects of mining on the local groundwater system is a difficult task due to its complex nature and the lack of detailed published information. An investigation of water level fluctuations in five we1 1s positioned over three consecutively mined longwall panels was initiated in conjunction with an intensive subsidence monitoring program. The purpose of this work was to provide detailed information which could be used to predict certain hydrologic effects of longwall mining in the Northern Appalachian Coal Region. The results of this case study indicate that water level fluct- uations in the local ground-water system above longwall panels is associated with subsidence and that the static water level will generally re- establish at or near the pre-mining elevation after mining is completed.

Jan 1, 1986

By E. H. Cho, P. K. Dai

An acid mine drainage sludge sample, containing 3.6% Mn, 0.18% Ni, 0.15% Co and 0.39% Zn, was obtained from central West Virginia. The sample was leached at room temperature with a pH 3 sulfuric acid solution. Air was then bubbled through the leach solution at pH 4.5 to precipitate the iron. The leach solution contained 258 ppm Zn, 105 ppm Ni, 90 ppm Co and 2050 ppm Mn. Three solvent extraction studies were performed to selectively extract these metal ions in a sequential operation with DEHPA. Cyanex 272 and Lix 84. The A/O ratio was one, and the extractants were diluted ten times with kerosene. A study of solvent extraction with DEHPA showed that Zn could be extracted without Ni or Co up to a pH of 2.75. A pH of 2.75 is considered to be the optimum pH to maximize the selective separation of Zn from Mn. The separation factor of Co over manganese suggests that the two metal ions should be extracted together by Cyanex 272. The separation factor of Co over Ni indicates that these two metal ions can be separated most effectively around pH 5.3. Also, Ni can be effectively extracted by Lix 84 above pH 5.5.

Jan 1, 1995

By Hasan Kolayli

Zeolites are common secondary components of a variety of igneous rocks. However it is extremely rare to reach such abundances to form a rock. An unusual rock composed almost entirely of natrolite, a zeolite mineral, has been discovered ; in a mountainous terrain called the Kop mountain range in the eastern Turkey. In the region, country rocks are essentially metamorphic rocks. These unique rocks are resulted through metasomatic changes acted on microdioritic and andesitic parent rocks occurring generally as dikes and stocks in the country rocks consisting chiefly of serpentinized harzburgites. These metasomatic rocks are investigated with respect to their mineralogical, petrographical, and geochemical characteristics. These products consisting dominantly of natrolite are termed "natrolitite" and those containing additional pargasite, an amphibol mineral, are termed "pargasite-bearing natrolitite or pargasitic natrolitite ". The dikes and stocks show concentric zoning, each of which has distinct chemical and mineralogical compositions: Na2O and H2O contents show enrichment outward from the core to chill zones whereas, SiO2 and CaO show depletion. Mineralogically, plagioclase variety, abundance and chemistry change outwards from the center due to partial to complete replacement of natrolite: anorthite contents of plagioclases decrease outward, which is indicated by A1203 and CaO decrease and SiO2 and Na2O increase, showing inverse relationship with increasing natrolite content.

Jan 1, 2005

By R. D. Miller, D. W. Steeples

Application of shallow, seismic reflection to problems associated with mineral exploration, mine planning, abandoned-mine detection and environmental evaluation has been successful in many geologic settings. The increased dynamic range of recording equipment and the decreased cost of processing hardware and software have made shallow, seismic reflection a cost-effective means of imaging geologic targets significant to mining operations. Seismic data possess sufficient resolution in many areas to detect faulting with displacement of less than 3 m (10 ft) in coal seams as thin as 2 m (6.5 ft) at depths of 200 m (655 ft). Subsurface voids associated with abandoned mines at depths of less than 20 m (65 ft) can he detected and mapped. Seismic reflection has been successful mapping disturbed subsurface associated with dissolution mining of salt. Complex geologic features associated with deposition of various hydrothermal minerals have been mapped with high-resolution seismic reflection at depths from 80 m (260 ft) to more than 300 m (985 ft). Faults in sulfur-hearing cap rock over salt domes have been accurately located, allowing improved efficiency of the dissolution mining process. Shallow, high-resolution seismic reflection has the potential to enhance the economics and safety of mine operations.

Jan 1, 1996

By G. B. Misra

Though installations of main mine fans vary widely, the commonest installation is of a surface exhaust fan connected to an upcast shaft some distance below its collar by a horizontal fan drift bending sharply. downwards near its junction with the shaft. The junction of the fan drift with the shaft often causes considerable shock pressure loss if not properly designed. In one of the major coal mines in India circulating 180 m3/s of air through the mine a pressure drop of 229 Pa out of the total fan pressure of 568 Pa occurred at this junction while in a smaller gold mine circulating 9.4 m3/s it was 147 Pa out of a fan-drift pressure of 382 Pa. With larger mines circulating larger volumes of air, ill designed fan drifts can lead to considerable wastage of the power of ventilation. Shock loss at the junction of fan drifts with exhaust shafts depends on (1) the angle of deflection of the bend, (2) sharpness of the corners (both inner and outer) at the junction, (3) the degree of contraction of the flow-stream which depends on the cross- sectional area ratio of the shaft and the fan drift as well as the amount of leakage through the shaft collar. It must be noted here that the friction pressure loss in the bend is negligible compared to the shock pressure loss.

Jan 1, 1980

By Mustafa Kumral

The study area is located in the Alpine-Himalayan zone in Turkey. Geologically, this is a very complicated region, and the rock units generally are divided into two groups as either allochthonous and autochthonous. Tectono-stratigraphically, the units are Paleozoic quartzite, black limestone, arkosic sandstone, interlaminated radiolarite and Triassic limestone, thick Jurassic limestone, detritic limestone with alternating Eocene Nummulites beds and cream-green marl, Miocene siltstone, and ophiolite. Trachyte, trachyandesite, feldspathoidal trachyandesite porphyry, tuff, and pumice formed by volcanism during the Plio-Quaternary also are present. Recent alluvium and slope detritus locally cover all the other rock units. A number of sulfur outcrops occur in the area. Among them are outcrops at Keciborlu, Yelliyatak Hill, Buyuk, and Kucuk Kukurt Dere. The most important sulfur deposits are found in volcanic tuff and siltstone-marl, and they include highly organic material. Sulfur may accumulate around recent gas diffusions and also as massive formations. The information about local geology and sulfur isotopes shows that the sulfur originated From the crust and probably comes from organic-rich Paleozoic and Triassic units. The sulfur did not move between Triassic and Pliocene time. However. Plio-Quaternary volcanism did cause movement of the sulfur, and this was followed by formation of the secondary sulfur due to post-tectonic thermal activities and the mixing of other surface waters.

Jan 1, 1999

By L. D. Gehi, A. W. Khair, M. Ahmad

This paper presents an analysis of the dynamics of bit wear on the productivity of continuous miners. Two field surveys were carried out. The first survey assessed the impact of bit wear on productivity and production cost. The second survey studied the wear characteristics of the cutting tool (i.e., magnitude, forms, and mechanisms of bit wear, Primary factors affecting bit wear were identified. Laboratory experiments were carried out to study in detail the effect of some of these primary factors on wear. Results indicate, that bit wear has a significant effect on the productivity a continuous miners. Furthermore, under severe geologic conditions (i.e. cutting rock partings in roof and floor) bit wear not only hampers the productivity, but also increase the production cost due to a higher consumption of bits. This study also indicated that beyond 20% of the conical height loss (which corresponds to 7% of the weight loss) the rate a bit wear accelerates. This increased rate of wear is an indication of higher abrasion between bit body and cutting material, resulting in a dustier environment.

Jan 1, 1995

By D. J. Kennedy, W. G. Klinowski

Over the past few years the Cape Breton Coal Research Laboratory's staff designed, built, tested and proved the necessary hardware, software and methodology of tracer gas based surveying techniques applied in the field of mine ventilation. These methods are now used routinely in a variety of applications where traditional anemometric methods do not provide the required accuracies or cannot be effectively employed. Irregular or highly turbulent flows, leakages, geometrically complicated or highly obstructed airways are just a few examples where traditional anemometry can produce unacceptable errors in calculated ventilation parameters. Tracer gas based ventilation techniques have been used in many problematic situations where the standard ventilation methods are inadequate. One such problem, faced by many mine operators, is the emergency imposed by the ever present threat of a mine fire. An understanding of the propagation of smoke contaminants and the demonstrated integrity of appointed escape routes can save lives and property during a fire. That knowledge can be gained quickly and inexpensively by the application of tracer gas smoke simulation methods. The concept of controlled air recirculation has recently gained considerable attention in the mining industry. While mathematical models can be used to predict performance, the ultimate proof of a ventilation system's performance can best be provided by a tracer gas based simulation of contaminant levels. Fan performance tests and assessment of auxiliary ventilation systems are highly dependent on accurate definition of airflows; precise data can be easily obtained by tracer gas based volumetric surveys. This paper contains a brief description of the equipment and the methodology of tracer gas based ventilation techniques and presents typical examples of their use

Jan 1, 1991

By John T. Gormley, Pressley L. Campbell, Harry L. Crouse

INTRODUCTION This paper summarizes an investigation conducted to determine the relationship, if any, between reported occurrences of abnormal levels of carbon dioxide (C02) gas and the construction of a 2.44meter diameter main sewer tunnel under South Eighty-Fourth Street, West Allis, Milwaukee, Wisconsin. Specific objectives of the study were to determine: (1) the sources of C02, (2) the significance of each C02 source, (3) how C02 could move to areas where it was reported to occur in abnormal concentrations, and (4) what actions could be implemented to eliminate elevated C02 levels associated with the tunneling operation. To accomplish study objectives, expertise from several scientific and engineering disciplines was required including chemistry, geochemistry, microbiology, hydraulics, and hydrology. Pertinent documents were reviewed and field data pertaining to each aspect of the study were collected as required and examined to evaluate existing conditions. Background On or about February 1, 1971, gas with a composition different from normal atmospheric air was reported to enter basements and wells of residences in the vicinity of South Eighty-Fourth Street, West Allis, Wisconsin. Examination of the gas composition revealed that it possessed an elevated concentration of C02 and a depleted concentration of oxygen (02). Public health officials who investigated the appearance of the objectionable gas concluded within reasonable certainty that the elevated C02 concentrations were associated with the tunnel construction under Eighty-Fourth Street.

Jan 1, 1979

By E. Yiğit, M. N. Saridede

Correction to: Mining, Metallurgy & Exploration. https://doi.org/10.1007/BF03402385 The original online article has been revised to correct the author names. Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. The online version of the original article can be found at https://doi.org/ 10.1007/BF03402385 * M. N. Saridede theng@smenet.org 1 Metallurgical and Materials Engineering, Yildiz Technical University, Istanbul,

Dec 23, 2021