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By K. O. Bennington

The thermodynamic properties of pollucite [(Cs0.650Na0.185Rb0.028)(AlSi2) (05.8630H0.137)?0.19H201 were determined by the Bureau of Mines in collaboration with the Argonne National Laboratory. The standard enthalpy of formation determined by hydrofluoric acid calorimetry is ?Hf°298 = -3,098.52 ±3.63 kJ mol-1. The standard enthalpy of formation from the oxides is ?H298 (from oxides) = -209.50 ±2.38 kJ mol-1. Low-temperature heat capacities were determined by adiabatic calorimetry from 5.0 to 306.1 K. The derived standard entropy is S°298 = 207.24 ±0.43 J mol-1k-1. Enthalpy increments above 300 K were measured by copper-block drop calorimetry from 349 to 674 K. Various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of measurements. Standard enthalpies of formation and Gibbs energies of formation are given as functions of temperature. The Gibbs energy of formation is ?Gf°298 = -2,919.9 W mol-1

Jan 1, 1983

This paper discusses design concepts in planning a large modern bulk terminal. The need is emphasised for a studied master plan, in-built materials handling flexibility and staged development. An integrated approach is advocated, combining functional purpose designed foundations and structures to serve their mechanical, electrical and environmental functions. Dry bulk and slurry handling are also compared in perspective.

Jan 1, 1983

By P. M. Scott

The South African Institute of Mining and Metallurgy held a colloquium on 'The Selection of Equipment for Underground Mining' in Johannesburg on 22nd September, 1982, which, judged by the interest shown, was an unqualified success. Mintek 50 As announced earlier, the Council for Mineral Technology (Mintek) will be celebrating fifty years of growth in 1984 and is organizing an international conference, MINTEK 50, on its areas of special expertise. Drilling Once again the South African Drilling Association will be holding a technical symposium in 1983. ILAFA Congresses The Instituto Latinoamericano del Fierro y el Acero (ILAFA) has scheduled the following congresses for 1983:

Jan 1, 1983

By P. N. Harris

The Colloquium on 'Recent Mining and Metallurgical Developments in the Orange Free State' was held at the Civic Centre in Welkom on the 4th and 5th May, 1983. The Chairman of the Orange Free StatejKlerksdorp Branch of the Institute and Acting General Manager of Unisel Gold Mining Company, Mr D. A. Parfitt, opened the proceedings, and Professor A. N. Brown gave the welcoming address. Mechanization of mining The South African Institute of Mining and Metallurgy is to hold a one-day colloquium on 'Developments in the Mechanization of Mining Operations' during September 1984. Surfac,e mining and quarrying The Second International Surface Mining and Quarrying Symposium is being organized by The Institution of Mining and Metallurgy in association with the Institute of Quarrying.

Jan 1, 1983

To develop an explosive charge that will effectively break rock in underground mines and that can be safely fired without the use of blast-holes or the need for stemming. Approach The Bureau of Mines developed a non-incendive, cylindrically-shaped explosive charge that will not ignite gassy or dusty atmospheres, even methane-laden air. How It Works Firing unconfined explosive charges in underground mines is prohibited by law since detonation in gassy or dusty atmospheres is extremely dangerous. However, there are advantages in using unconfined charges from both a safety and a production standpoint. Explosives can effectively break up large boulders, rocks and slabs when leveling roof falls and can dislodge overhangs which miners would other-wise have to dislodge manually, exposing themselves to

Jan 1, 1983

By M. Splaine, M. A. Field, S. J. Browner

In the field of operational control, Shewhart Control Charts and Cusum Charts have long been available to management. These techniques provide help by detecting rogue values of a control variable and changes in the underlying mean of that variable respectively. This paper describes a new technique for identifying changes in the trend of a control variable, particularly when that variable is subject to large inherent variance.

Jan 1, 1983

By Wallace W. Roepke

The Bureau of Mines conducted a series of experiments using Illinois No. 6 coal to determine the effect of asymmetric wear on airborne respirable dust (ARD), specific energy, cutting force, and normal force. Plumb-bob-type bits--one new bit and four ground with different sized flats--were used. Constant-depth linear cuts at 0.32, 0.64, 1.27, and 2.54-cm cut depths were made. Both cutting force and normal force increased as the flat area increased. Specific energy demonstrated a statistically significant increase with flat area at the 0.32-and 1.27-cm cut depth only. Specific ARD showed a statistically significant decrease with increasing flat area only at the 0.64-cm cut depth. Increasing cut depth increased cutting force but decreased specific energy and specific ARD. Normal force increased with increasing cut depth for the new bit but exhibited a maximum at 0.64 cm for the bits with flats.

Jan 1, 1983

By Garth A. Maki, Douglas M. Smith

"The largest Canadian Lamella thickener installation to date, with 13,600 square feet of effective clarification area, is being successfully operated at the Rocanville Division of the Potash Corporation of Saskatchewan. This paper describes the operational principles and design features of the Lamella thickener, the testwork leading to its specification f or the Rocanville phase two expansion project and a review of the performance of the full- size unit which was ultimately installed.IntroductionThickening equipment operating in the Saskatchewan potash industry is generally situated within the main refinery building or a separate insulated an d he a ted structure due to the harsh winter climate and the need to closely control plant brine temperatures to en sure good flotation circuit performance Because these thickeners process large volumes of slurries, conventional basin-type designs tend to be large, ranging up to 46 metres in diameter or more. As part of the general effort to minimize capital costs, the potash industry has begun investigating the use of alternate high capacity, compact thickener designs. In this regard, PCS Rocanville undertook a program in 1978 to evaluate a LamellaTM thickener and one other type of ‘High Rate' thickener as alternatives to a conventional design for the phase two expansion project.This paper describes the operational principles and design features o f the Lamella thickener (manufactured by Axel Johnson lnc.), the testwork leading to the specification of a Lamella for the Rocanville expansion project and are view of the performance of the full size unit (1486 m2 of the effective settling area) which was ultimately installed and is now successfully operating in the Rocanville plant."

Jan 1, 1983

The last 40 years has seen a dramatic reduction in the prevalence of pneumoconiosis through improved mining engineering associated with continuing medical surveillance of those at risk. Presently the dust particle count standard is being correlated with gravimetric dust standards. Chronic Bronchitis and Emphysema are also coal mining related diseases. Methane is the commonest of a number of coal mine gases. Oxygen deficiency symptoms may result from high gas content of mine air. The explosive nature of methane-air mixtures is well known. Mine gases will always present a potential threat to safety.

Jan 1, 1983

By Ginger S. Evans

This report documents a preliminary hydrologic investigation of an area where longwall mining methods are to be used. The scope of work includes: determination of physical and chemical characteristics of major soil types in the area; determination of physical and chemical properties of surface water bodies; collection of geologic characteristics, including stratigraphy, structure, and detailed aquifer descriptions; collection of 10 years' meteorological data and installation of a weather station; and a detailed ground-water investigation that includes completion of observation wells, aquifer testing, water quality sampling, and analysis using a 3-D computer model. The Trescott model developed by USGS was used to simulate steady-state aquifer conditions. Input data from 8 multiple-completion monitor wells were used to model an area of approximately 10 square miles. Two layers, coal and overburden, were simulated, both confined. Model results showed good agreement with know piezometric data, desaturated areas, and flow from springs. The study area was found to have very low-yield bedrock aquifers with transmissivities ranging from 5 to 320 ft2/day for the coal (depths from 500 to 1,200 ft) and from 499 to 576 ft2/day and fractured sandstone units (depths less than 100 ft). Annual precipitation and recharge are very low, 10 to 11 inches and 0.25 inch respectively. The area has very high relief and large areas of rock outcrop. No perennial streams are present on the site.

Jan 1, 1983

By Winn B. Frank

Events of the mid-1970's have materially affected US coal production and transportation by railroad. Coal, as a replacement or substitute for petroleum fuels, has been hauled in significantly increased tonnages. Concurrent with the new demand, the railroad regulatory environment has undergone major changes, especially in "deregulation" activity. Those two events have produced considerable Litigation regarding coal rates. This paper discusses the factors involved with railroad rates and topics such as revenue adequacy, Ramsey Pricing, stand-alone cost, and differential pricing. In addition, an update on the western railroad merger situation and the implications for coal transportation are presented. The paper concludes with an evaluation of the current regulatory climate and future prospects.

Jan 1, 1983

By S. Y. Han

INTRODUCTION More than 97% of the total uranium production of the United States comes from sedimentary deposits (1). These sandstone deposits were formed by reduction of migrating uranium-bearing solutions from volcanic silicate rock sources. Such deposits occur in two major forms, either as relatively flat, lens-like deposits or as crescent- shaped roll front deposits. The lens-like deposits are found as discrete masses enclosed in reduced sandstone which is generally surrounded by oxidized sandstone. The roll front deposits are found along crescent-shaped interfaces between reduced and oxidized sands tone (2). In-situ mining of selected sedimentary deposits has proven to be a viable method of extraction and competitive with conventional mining for relatively deep low-grade ores (2). In in-situ leaching, uranium is recovered by drilling injection and collection wells in the ore body, pumping a suitable lixiviant to dissolve the mineral, extracting uranium from the pregnant solution by ion exchange, and finally regenerating and recycling the lixiviant. Even though there is increasing interest and practice in developing the in-situ technique for obtaining uranium values from deeper, lower-grade reserves, there is a lack of knowledge of the basic leaching kinetics and combined transport processes. In-situ leaching operations, in general, appear attractive for the following three general types of deposits (2): (1) low-grade surface dumps or deposits which lie above the natural water table,

Jan 1, 1983

By J. M. Duke, A. J. Naldrett

Significant resources grading less than about 1% nickel occur in magmatic sulfide deposits of two types. In the Mt. Keith type, extensive zones of disseminated nickel sulfides occur in the central portions of certain synvolcanic dunite-peridotite sills of komatiitic affinity in Archean greenstone terranes. In the Duluth type, disseminated copper-nickel sulfides occur near the basal margins of intrusions of flood basaltic affinity associated with intracontinental rifring. In both types, the parent magmas became saturated with sulfide following the onset of fractional crystallization and the separation of the immiscible sulfide melt was accompanied by the precipitation of a relatively large proportion of silicates. The abundant silicate crystals impeded the coalescense and accumulation of the sulfide droplets with the resulting formation of large but low grade deposits.

Jan 1, 1983

By Charle Lawrence, Murray E. Blanchard

"A significant addition to Canada's commodity export transportation capabilities is being built by Ridley Terminals Inc. on Ridley Island in the Port of Prince Rupert on British Columbia's north coast.Site preparation began in early 1982. By the end of 1983 the terminal will be receiving coal from two major new mines being developed in B. C.'s massive $2.5 billion northeast coal development.The RTI terminal will have initial capacity to transfer 12 million tonnes of coal a year from railcars to storage and to ships. Capacity will be doubled to 24 million tonnes as market opportunities are developed.The challenge of building this $220-million facility in less than 24 months, the benefits Canada has received from the work the project is generating, and the long-term faith in Canada that this project represents, are all part of the excitement which surrounds the Ridley Terminal and northeast coal developments.RIDLEY TERMINALS INC. (RTI) is building a very significant addition to Canada's commodity export transportation capabilities. The facility, on Ridley Island at Prince Rupert, on the north coast of British Columbia, is a key link in British Columbia's northeast coal development which in itself is a massive undertaking involving investment of some $2.5 billion. The entire project is making a substantial contribution to Canada's economy at a time when such contributions are sorely needed.The development is creating employment, not only in British Columbia where its various parts are being created by mining companies, railways and others, but also across the country where suppliers are manufacturing a wide variety of good s and equipment for the development's participants.The RTI terminal is no exception. It is a critical cog in this mega project's large transportation system and its construction is contributing substantially to job creation and to other economic activity, in the Prince Rupert area and in many other parts of British Columbia and the rest of Canada."

Jan 1, 1983

By A. Landsberg

Kaolinitic clays are potentially a vast domestic resource for aluminum. Utilization of this resource could decrease or eliminate the nearly complete dependence of the United States on foreign raw materials for this important metal. Furthermore, processing of clay to aluminum through anhydrous chloride metallurgy could reduce the high electrical energy requirements of the conventional Hall-Heroult aluminum reduction process. Several anhydrous chloride processes have been proposed; however, unresolved technical problems have prevented their commercialization. In particular, an acceptable chemical means has not been found to extract aluminum from clay as a highly pure anhydrous aluminum chloride. This Bureau of Mines report identifies and discusses the important chemical problems involved in achieving an acceptably rapid, self-heating, selective chlorination reaction and the subsequent separation of iron chloride byproduct from the anhydrous aluminum chloride.

Jan 1, 1983

Financial markets are subject to constant change and project finance, as a product within these markets, adapts and will continue to adapt with those changes. A meaningful discussion of these adaptations requires an understanding of differences between non-, limited and full recourse project finance. The reasons sponsors seek and lenders provide project finance are also pertinent in this context. Arranging a project, financing package can be a canplex and time consuming task. An important first step is choosing the right advisor for the assignment and then structuring and tailoring the financing before approaching prospective lenders. The last thirty years has seen changes in the needs of sponsors and the ability of lenders to meet them. These shifts in preference may well be a guide to the future. Several major project financings successfully canpleted in Australia in the last few years and more recent examples are broadly discussed. Project finance will be keenly sought in the future and the form and nature it takes will continue to vary.

Jan 1, 1983

Jan 1, 1983

By Terry S. Maio

In 1978, Ozark Lead Company made the decision to expand the capacity of its mine/mill complex by 33%. The objectives of the expansion were to (a) increase mine' production capacity by 1816 tonne/d(2000 TPD), (b) increase lead metal pro¬duction by 21,790 tonne/y (24,000 TPY) and to (c) construct new facilities and/or modify exis¬ting equipment to accomodate the increased pro¬duction. The intent of this paper is to give a brief explanation of the equipment installed and the overall production and metallurgical benefits-realized from this expansion. The expansion was completed in the second half of 1980 with all equipment debugging and fine tuning completed by the first' quarter of 1981. The concentrator modifications and improvements were basically restricted to four areas: (1) materials handling, (2) automation: of the mill grinding circuit, (3) the increase of flotation capacity, and (4) concentrate dewatering.

Jan 1, 1983

By R. W. Lawrence, A. Bruynesteyn

"Pre-oxidation of refractory pyritic concentrates by biological leaching to enhance the recovery of gold and silver in cyan ideation has been investigated. The results of laboratory tests on three concentrates are presented. In all cases substantial increases in precious metal recoveries were obtained following the pre-treatment. For one concentrate, gold recovery of 81% was achieved following an 87% oxidation of pyrite, compared with 24% recovery by direct cyanidation of non-oxidized concentrate. Gold and silver recoveries from the other concentrates were increased from the range 60-78% to over 90% and from 80-86% to over 98% respectively. Operating parameters are discussed and methods of maintaining high oxidation rates are evaluated. Methods of employing this pre-oxidation technique in commercial practice are described.IntroductionMany of the gold and silver deposits now being developed contain precious metals finely disseminated in sulphide minerals such as pyrite. These ore s often present considerable resistance to metal recovery. The ease with which gold may be extracted is usually related to grain size and its manner of distribution within the host mineral. In many cases, a significant percentage of the gold may occur in submicroscopic form, or in solid solution with pyrite, so that even very fine grinding fail s to liberate the metal for recovery by cyanide leaching. Such ores are often termed refractory. Even in cases where liberation by fine grinding is practicable, high cyanide and lime consumption may be experienced due to the presence of specific sulphide minerals, and poor metal recovery may result.Pre-oxidation methods for refractory ore s and concentrates are commonly used to improve precious metal recoveries. Roasting, for example, as a pre-treatment to cyanidation, removes harmful constituents by oxidation or volatilization, and liberates gold from pyrite. In some cases, however, this method of pre-oxidation can result in poorer metal recovery, particularly of silver, due to fusion and the formation of clinker, and the formation of compounds which consume cyanide in the subsequent metal recovery stage. Difficulties in compliance with environmental pollution regulations may also be encountered."

Jan 1, 1983

By Jeffrey L. Thompson, Kenneth A. Gutschick, Robert C. Freas, Robert S. Boynton

Lime, the "versatile chemical," is, generally speaking, a calcined or burned form of limestone commonly known as quicklime, calcium oxide or calcia, or, when water is added, calcium hydroxide or slaked lime. Almost 40 different lime products are available, a fact which has contributed to the rather loose use of the term lime as well as to much confusion and misunderstanding. The term is frequently, albeit erroneously, used to denote almost any kind of calcareous material or finely ground form of limestone or dolomite. Lime is usually made from high-calcium or high-magnesium limestone, generally having a minimum of 97% combined carbonate content. Normally, high-calcium limes contain less than 5% MgO. When the lime is produced from a high-magnesium limestone, the product is referred to as dolomitic lime. Calcination, or the production of lime, has its origins in the earliest days of alchemy, with the general reaction class having been identified in an Arabic text printed in 1000 A.D. It was much later, however, in the mid-1700s to the mid-1800s before this basic reaction became understood from a scientific perspective. The production of lime has been so basic and simple that its underlying scientific principles have over the years received only intermittent investigation. Rather, much of the thought and inquiry has been directed toward the development of kilns. Thus, it has only been in the last 15 to 20 years that lime has received any concentrated scientific investigation relative to the thermodynamics and kinetics of the calcination and hydration reactions. Calcination refers to a broad class of reactions, of which the lime/limestone reaction is just one, wherein a substance is heated to less than its melting point, resulting in a weight gain or weight loss. In the calcination of limestone to produce lime, the basic chemical reaction is as follows: [CaCO3 (limestone) + heat (1000° to 1300°C)= 100 CaO (quicklime) + CO2 T 5644 or CaCO3 • MgCO3 (limestone) 10084 + heat (900°C to 1200°C) CaO • MgO (quicklime) + 2CO2 T 56 4088] While there is nearly universal agreement about the equilibrium conditions related to the limestone/lime reaction above, there have been numerous and varied calcination models developed for the reaction. Recent investigations have resulted in the development of the model shown in Fig. 1. From this model it can be seen that calcination is a function of both temperature and CO2 pressure. It does not, however, provide any indication of the rate at which the reaction takes place. Calcination is strongly time variant with different limestones. In a very broad sense this relates to the fact that the calcination reaction starts on the exterior surface of the limestone and then proceeds toward the center. As the calcination reaction takes place, the CO2 released at the reaction interface must make its way through the lime to the exterior surface. Therefore, because calcination is limited by gas diffusion to the surface of the partially calcined limestone, natural impurities in the stone, differences in crystallinity, grain boundary chemistry, density variations, and imperfections in the atomic lattice all play a significant role in

Jan 1, 1983