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By Lynton Gormely

Oxygen transfer in a stirred tank bioreactor has been modelled mathematically to determine the trends in transfer efficiency (kg transferred per kWh) with transfer rate, tank depth, superficial velocity, and mixer power.

Jan 1, 1990

By D. Robert Weir, Roman M. G. S. Berezowsky

Pressure oxidation of gold containing concentrates and ores is an effective pre- treatment for liberating refractory gold. This is particularly true when an appreciable portion of the gold is associated with sulphides and is not amenable to conventional cyanidation. A brief review of the literature on the pressure oxidation of refractory gold materials is presented. The chemistry of the aqueous oxidation of arsenopyrite and pyrite is discussed. Data obtained on the pressure oxidation and subsequent cyanidation of concentrates and ores tested at the Sherritt Research Centre are also presented.

Jan 1, 1984

By M. A. Bothwell

The purpose of this paper is to describe the methods used to select mill discharge screens, and to outline factors which should be taken into consideration when choosing screens for this application.

Jan 1, 2001

By John C. Balla

The Spar Lake deposit is located in northwestern Montana, approximately 27 km (17 miles) south of Troy, MT, under Mt. Vernon. The deposit is a stratiform, stratabound copper-silver deposit occurring in the Revett Formation of the Proterozoic Belt Supergroup. Distribution of known sandstone-type deposits in the Revett Formation is shown in Fig. 1.

Jan 1, 1991

By D. Antonov

The physical and mechanical properties of coal play a important role in the planing and design of coal mines. However, due to the complexity conditions in situ and the influence of unknown factors, it is hard for people to evaluate the physical and mechanical properties of coal directly. In this research, uniaxial compressive stress was used to change the attribute of coal samples, and the ultrasonic measure technique was used to evaluate the physical and mechanical properties of coal. The results of laboratory test showed that there was a strong relation between uniaxial stress and velocity of ultrasonic wave. Sensitivity analysis with numerical simulation was used to define the relation between the physical-mechanical parameters of coal and ultrasonoc wave. With the dynamic analysis module of FLAC, three elastic and plastic models were built to model the coal samples. The modeling parameters were changed pro rata, and the correlation of coal and ultrasonic wave properties were summarized and presented. The result from this research will be base for further analysis of caving behavior of coal.

Jan 1, 2010

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

Jan 1, 1986

By J. G. Groppo, S. M. Khandrika, B. K. Parekh

It is shown that dewatering of fine coal particles (D50 = 21 µm) is enhanced near the point-of-zero-charge. The coal surface is modified by the addition of copper ions and by adjusting the pH to precipitate surface-active metal hydroxy species, which promote agglomeration and produce low-moisture cakes. Filtration kinetics data are used in calculating filter cake parameters from an integrated form of Darcy's law. The influence of copper ions and pH on filter cake parameters and the correlations among them are presented.

Jan 1, 1995

By M. C. Fuerstenau

Collophane, cryptocrystalline fluorapatite, is examined as a substrate for plant water and wastewater remediation. The attenuation of Fe3+, Cr3+, Fe2+, Cd2+, Hg2+ and Pb2+ is presented as a function of metal ion concentration, amount of collophane, initial pH and conditioning time. TCLP results for Pb2+ contaminated collophane are presented. Mechanisms of adsorption for divalent and trivalent species are suggested. Key words: Collophane, Wastewater remediation, Heavy metal removal

Jan 1, 2003

By M. S. Vernon, J. J. Kellar, W. M. Cross, R. M. Winter, F. J. Johnson, A. G. Pommer

Three substrates (MgO crystal, CaF2 crystal and Mg plate) were used to construct thin layers of Mg(OH)2. Various routes were used to modify these substrates, including surface hydration and sol-gel coating. In each case, it was found (by using Fourier transform infrared spectroscopy) that thin layers of Mg(OH)2 could be produced. In the case of hydrated layers, the surface morphology of the Mg(OH)2 resembles the bulk platelet shape of precipitated Mg(OH)2.

Jan 1, 2000

By M. G. Yalçin

Marbles commercially known as the Nigde- white crop out in the town of Gümü?ler, around the Çalkama Hill within the Gümü?ler Formation of the Nigde Masif of Paleozoic age. Marbles sporadically occur within the masif, however its prevalent occurrence is associated with the Gümü?ler Formation. Due mainly to its intense fractured nature, the Nigde-white marbles are used as dimension stones, crushed stones and most recently micronized calcite. Insignificant portion accounts for block use through a few quarries.

Jan 1, 2005

By Jihong Xue, Jialin Wang, Della Valle Nicola

Experience of Hard Rock TBM excavating soil in Wanjiazhai Yellow River Diversion Project tells us that selection of Hard Rock TBM to excavate soil in case that rock dominates overall length of tunnel, could be a compromise among tunneling speed, cost and quality. Risk of this operation could be greatly reduced with a detailed study of the geomechanical characteristics of the soil and, if the characteristics are suitable, money and time can be saved by using Hard Rock Double Shield TBM.

Jan 1, 2003

By John N. Murphy, Edward F. Fries

The availability of fast, low-cost computer hardware and advanced software is opening new opportunities for minerals extraction and processing. Programmable Logic Controllers (PLC's) are currently used extensively in the minerals industries; this paper looks beyond PLC's and that vintage of “computer control”--it looks toward what the authors see as new in the next five years. Topics covered include expert systems, neural networks, intelligent signal processing, and hierarchical controllers as applied to mining and mineral processing operations.

Jan 1, 1993

By Fathi Habashi

THE MOST important arsenic minerals are shown in Table 6-1. The recovery of arsenic from arsenic sulfides is treated in Chapter Four. Arsenical ores may be either leached directly, or first smelted to volatilize as much arsenic and sulfur as possible, and the resulting product, called speiss, is then leached. A speiss is mainly a complex mixture of metal arsenides, but its [Table 6-1. Arsenic minerals. Arsenides Niccolite NiS Smaltite CoAs2 Skutterudite CoAs3 Sulfarsenides Cobaltite CoAsS Enargite CuaAsS4 Arsenopyrite FeAsS Arsenic sulfides Realgar As4S4 Orpiment As2S3] composition varies widely, depending on the type of ore treated. A speiss usually contains 15-35% arsenic. Methods of leaching are describedd in the following paragraphs.

Jan 1, 1970

By K. P. Madhusudhanan, R. K. Bhatia, K. S. Narasimhan, R. N. Singh

A typical case study of a coal washery of capacity 500 t/h raw coal input has been presented and discussed with particular reference to the techno-economics for flotation column vis-a-vis the conventional flotation cells, keeping parameters like input capacity and product ash same. The results presented indicate that substitution of flotation cells by columns in a coal washery results in advantages of increased fine coal recovery, better quality of concentrates, lower capital and production costs etc.,. The effect of increasing the specific capacity of the column by design modifications on the cost benefit is also analysed.

Jan 1, 1988

By G. W. Heunisch

The properties of Neutra-Fix® and Neutra-Ment®, two new lime substitutes for treating acid mine drainage (AMD), have been compared with lime and Allcament®, two products presently in use for AMD treatment. The two new products are basically dolomitic byproducts and produce sludges that are more compact than those from lime. Sludge settling rates are faster than lime with iron concentrations after 24 hours that comply with Environmental Protection Agency (EPA) regulations. Material utilization and optimum pH are reported.

Jan 1, 1988

By Haydn H. Murray

Common clay includes a wide variety of clay and other fine- grained rocks that are used in many ways. These clays are some- times classified as miscellaneous clay and shale. Most products made from them are fired and include such things as structural and face brick, drain tile, vitrified pipe, quarry tile, flue tile, conduit, pottery, stoneware, and roofing tile. Very large tonnages of these materials are bloated by firing to form lightweight aggregate, and large quantities are used in making portland cement (see the specific chapters in this volume). Uses not requiring firing of a finished product include filler for paint and other products and shale and clay used for packing dynamite in blastholes and for plugging oil and gas wells that are no longer in use.

Jan 1, 1994

By Jan K. Wolski

This paper addresses jet fans used as booster fans within mine ventilation networks. The static pressure developed by the jet fan was determined using the momentum theory. The influence of various parameters on this pressure was analyzed. A method was proposed for determination of the jet fan characteristic curve . The distance between the jet fan and a point where the fully developed static pressure can be measured was determined. It was shown that a reduction cone can significantly improve the jet fan performance. Verification experiments conducted in the Waldo mine are described.

Jan 1, 1995

By R. D. Lama

This paper presents the results of a large scale trial of polycrystalline diamond picks (PDC) on longwalls with particular reference to dust control. Results from fixed position monitoring showed that PDC picks produced less respirable dust than tungsten carbide Point Attack picks. Dust generation at the longwall face was lower by 39 - 43%. Field trials also indicated that the life of a PDC pick to be at least 1460 tonnes/pick.

Jan 1, 1993

By Mary Fu, Helen Leung, Colin R. Phillips

In uranium mines, the median size of the aerosol has been found to be about 0.1 micron or less. Such small aerosols are readily deposited or "plated-out" on dosimeter interior surfaces resulting in the recording of a low dose. The "plate-out" properties of the CEA alpha dosimeter head are described with respect to aerosol properties in controlled experiments in the laboratory. A simple model is derived to estimate the amount of "plate-out" in the CEA head.

Jan 1, 1981

By Ch. Arvanitidis

This work concentrates on investigating the development of a geotechnical classification method for the Greek soils, which can readily provide a rough but usable estimate of the main strength parameters of the soil. It is expected that such a system will be useful to the structural engineer for either checking the laboratory results or for providing a direct estimate in cases where no tests have been conducted. The method provides strength parameter values by relating classification or physical parameters of various types of soils and/or in situ observations of geological and physiographical nature to the strength parameters, such as, cohesion, angle of internal friction, compressibility, modulus of elasticity, etc, by means of a statistical approach and the extraction of empirical formulae.

Jan 1, 2006