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By J Addai-Mensah, W Skinner, C Kelsey, J R. Kelly, E Baawuah

Comminution continues to be the most capital-intensive unit operation in mineral processing. The fundamental purpose of comminution is to liberate the valuable minerals so that they can be economically concentrated into saleable products. Declining ore quality characterised by lower grade and increased complexity requires significant energy consumption for comminution. Low-grade magnetite ores are typically fine-grained and require fine to ultra-fine grinding (P80 ~ 30 - 40 µm) to enhance its liberation from the typically siliceous gangue matrix. Historically, this has been achieved using multi-stage crushing and grinding technologies, which require high energy consumption with low energy efficiency. This motivated innovations in energy efficient technologies for comminution. Such technology has been developed in the IMPTEC super-fine crusher. It is an innovative, dry (with the potential to be operated wet), media-free, energy efficient crusher that can to reduce 10 mm feed particles to 19 – 30 µm with very low recycle loads. In this study, the mineralogical and physicochemical characteristics of crushed magnetite ore using the IMPTEC super-fine crusher have been investigated in comparison with those of rod milling. The super-fine crusher generated higher liberated magnetite minerals in the – 300 + 212 µm and < 45 µm size fractions compared to rod mill. Both comminution devices generated large low-grade hematite and goethite middlings. However, the rod mill produced higher locked/unliberated hematite and goethite compared to that of the super-fine crusher. Quartz mineral had the highest liberation irrespective of the comminution device used. The super-fine crusher generated higher entrapment of other minerals within the silica matrix compared to the rod mill. The breakage mechanism of the super-fine crusher which is predominantly through high compression with shear, generated improved mineral liberation in the coarse size fractions compared to the predominant abrasion and attrition breakage mechanisms of rod milling. The higher mineral liberation generated by the rod mill is potentially due to the prolonged batch milling of the ore compared to the single-pass open circuit of the super-fine crusher.CITATION:Baawuah, E, Kelsey, C, Kelly, J R, Addai-Mensah, J and Skinner, W, 2018. Mineral liberation studies of IMPTEC super-fine crusher – 130 crushed product, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 313–326 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By J. Chai, Q. Yuan, B. Qiu

"Overburden strata deformation monitoring is one of the key problems in ground control. Using geophysical method through surface drilling to detect strata deformation is commonly used in the industry. In this paper, a geophysical method based on the distributed optical fiber sensing (DOFS) system were conducted in the laboratory, where a DOFS-based strata deformation monitoring experiment was performed with three physical models. The results show that the DOFS method precisely detects the rock mass deformation and strata structure forming with the Brillouin frequency shifts (BFS) representation. The BFS curves are divided into three phases, which reflects the horizontal three zones developed in the overburden. The BFS distribution presents a multiple stages form, the 1st stage corresponds to the caving zone and the 2nd stage corresponds to the fracture zone. Based on the multiple stages form, the evolution of the water flowing through fractured zone have been determined and the controlling effect of key strata over the water flowing fracture has been pointed out. In the end, the comparison validation proves the accuracy and reliability of this method, and it could be a new approach for the ground control research. INTRODUCTION Overburden rock strata above the work face space will propagate from slight deformation, part destruction to violent movement because of the underground coal mining. It is fundamental and an intrinsic requirement of ground control to monitor the mining-induced rock mass deformation.[1] Overburden strata have their significant mechanical behaviors and movement under damage deformation and fracture. Overburden strata deformation affect the mining ground pressure control directly, and performance in the relationship of supporting equipment and the surrounding rock, the mining-induced fracture distribution and the loss of underground water resource, the ground surface structure stability and the ecological environment.[2] From the perspective of the concept of safe and efficient scientific coal mining: the overburden strata deformation is an important part of mining method selection and reasonable supporting solutions decision which can solve the issues like the roof supporting force calculation, overburden fracture distribution and gas drainage, ground subsidence, separation of coal and rock control and top-coal recovery rate and so on. From the perspective of green and ecological mining: the overburden strata deformation is the key basis of studying the mining-induced ground subsidence and mining area ecological damage, and such engineering problem like environmental protection in mining area, ecological restoration in mining subsided land and the water conservation in fragile ecology area of mining could be solved based on it.[3-6] Therefore, the mining-induced overburden strata deformation is the key of ground control and needs to be controlled artificially."

Jan 1, 2017

By Nick Rose, Robert Sharon, Mark Rantapaa

Development of the Northeast Layback of Barrick’s Betze-Post open pit commenced in June 2000 and was successfully completed to a height of 400m (1,300 ft) in January 2003. Following a brief exploration drilling campaign at the toe of the final slope, in-pit waste rock backfilling commenced, which will ultimately buttress the final wall. Instability initially occurred in late 2000, above the 5040 Level, as the slope height approached 120m (400 ft). As mining reached the 4680 Level, significant deformation was experienced over a slope height of 230m (760 ft). Slope stability was managed and targeted reserve recovery was achieved by executing complicated modifications of the mine plan, including splitting layback development, well placed offloading cuts, step-outs and mid-slope waste rock buttresses. Decision on timing of these modifying events was often dictated by review of deformation magnitudes and rates determined from continuous slope monitoring records. Design modifications were developed through continuing interpretive refinement of structural geology controls and groundwater distribution, and through stability re-assessments. This document presents an overview of the geological setting and material and strength conditions of the northeast sector of the Betze-Post open pit, followed by development experience leading to design and development of the Northeast Layback. Rock mechanics modeling, design details and geotechnical performance monitoring are then presented. Development experience, stabilizing adjustments to the original design and safety procedures for development and exploration activities are described. The document is finalized with conclusions and acknowledgements.

Jan 1, 2005

By J. C. Stankus

How to quantitatively identify the loads on a square/arch set is a complicated issue in designing the square/arch set in an intersection/entry. From an engineering perspective, understanding the nature and support mechanism of standing support such as a square/arch set can not only help design the support structure to maintain the roof stability, but save the steel materials and costs of manufacturing, labor, and delivery. Based on the design practices in recent years and successful applications in slope bottom intersections, the authors are confident that the concept of interaction and confinement effect between the steel square/arch set and surrounding rocks is critical in designing a proper steel structure to support an intersection/entry. This paper will detail the design concept and its applications in several underground slope bottom intersection designs, reaching the goals of improving roof stability and reducing costs.

Feb 23, 2014

By Guy Reed, Russell Frith

"The method of determining coal pillar strength equations from databases of stable and failed case histories is more than 50 years old and has been applied in different countries by different researchers in a range of mining situations. While common wisdom sensibly limits the use of the resultant pillar strength equations and methods to design scenarios that are consistent with the founding database, there are a number of examples where failures have occurred as a direct result of applying empirical design methods to coal pillar design problems that are inconsistent with the founding database.This paper explores the reasons why empirically derived coal pillar strength equations tend to be problem-specific and should be considered as providing no more than a pillar strength “index.” These include the non-consideration of overburden horizontal stress within the mine stability problem, an inadequate definition of super-critical overburden behaviour as it applies to standing coal pillars, and the non-consideration of overburden displacement and coal pillar strain limits. All of which combine to potentially complicate and confuse the back-analysis of coal pillar strength from failed cases.A modified coal pillar design representation and model are presented based on coal pillars acting to reinforce a horizontally stressed overburden, rather than suspend an otherwise unstable self-loaded overburden or section, the latter having been at the core of historical empirical studies into coal pillar strength and stability.INTRODUCTIONThe inspiration for this paper is founded in three statements from two eminent persons in the field of coal pillar strength research, Jim Galvin and Essie Esterhuizen, as follows:Both Salamon and Munro and [the University of New South Wales] based the derivation of their pillar strength formulae on a criteria that the diameter of a panel of pillars, W, had to at least equal the depth of mining, H. This was thought to result in full tributary loading. It is now known that there are some mining environments included in both the South African and Australian databases in which mining span must exceed depth by a considerable margin in order to achieve full deadweight loading. Hence, it is logical to conclude that these data points may have contributed to pillar strength being overestimated by Salamon and Munro and UNSW (underline added by authors). Normally, this should be of no consequence because it is reflected in the probability of design success associated with any given safety factor (Galvin, 2006)."

Jan 1, 2018

By Stefano Utili, Robert Pell, Nelson Morales, Cristobal Valderrama, Andrea Agosti, Guillermo Albornoz

The overall slope angle (OSA) of pit walls plays a crucial role in the financial return of open pit mines. The work showcases a novel design methodology where non-planar geotechnically optimal pit walls with an OSA steeper than what is used in current design practices are employed without compromising mine safety, i.e. the optimal profiles are featured by the same Factor of Safety (FoS) than their traditional design counterparts. In the current design practice, pit wall profiles are often designed to be planar in cross-section and the profile in between ramps especially tend to be defined by a constant inter-ramp angle.

Sep 30, 2022

By Gyan S. Rajhans

"The strategy of fibrous dust sampling is discussed, various sampiing methods are critically reviewed .and their application to coal dust is demonstrated. Fibre counting is described in detail. An attempt is made to explain the basis of determining the threshold limit value of asbestos and other dusts. The paper also discusses such dust control methods as enclosure of the process, effective local exhaust ventilation, segregation, substitution, wet processing and continuous monitoring of the return air for recirculation."

Jan 1, 1970

By Donald L. Colwell

THIS is a metallurgical war. More than ever before, the mechanized forces and the air-borne warfare are deciding campaigns. Both of these are primarily dependent upon metals. There are two ways of increasing the effective supply of these metals when the demand is greater than the total over-all supply. The American custom, when a shortage of anything develops, is to get more. In the case of some nonferrous metals this has been done. For example, our potential peak output of magnesium will be almost one hundred times the prewar production. Output of aluminun has also been tremendously increased, and production of other metals is being stimulated by every possible means. Our enemies, however, have another successful method of increasing the effective supply of a material, and that is, to eliminate entirely all nonessential uses, and also to use, in essential applications, alternate materials wherever possible. Sometimes, ersatz material is inferior to the original, and consequently does not do the job as well. Often, however, it has been found superior, and many substitute items are now being used both by industry and by the military which will continue even when the original material again becomes available.

Jan 1, 1943

By Tom Szaraz

Part of a major sewer expansion for the City of Columbus, Ohio. The Big Walnut Outfall Augmentation Sewer?Part II (BWOAS) consists of 13,200 feet of tunnel of 12-foot tunnel passing mainly through glacial deposits with a water head of up to 2 bar. A Lovat RME167SE was used to drive this tunnel with steel fiber reinforced precast segmental liner used for support. This paper will discuss the concepts for tunnel sup-port and TBM selection, the problems encountered with the TBM sealing systems and the solutions used to repair the machine.

By Derek Egan

"Abstract Construction clients want their foundation solutions to be right first time, every time; but it is often the geotechnical contractor who carries the most risk in achieving this. Robust validation to ensure that the installed geotechnical product is appropriate for the encountered ground conditions, will perform as required and be correctly measured for payment and record purposes is very important to minimise the contractor’s and the client’s risk. This paper outlines the development and operation of a robust real-time installation monitoring system which controls and validates the installation of driven cast in-situ (DCIS) piling. Using state of the art information technology the system allows the design engineer to interrogate the data acquired from the piling rig via his computer as the piles are completed. The use of the validation process, where data acquired during the driving of DCIS piles can be processed to estimate the finished pile performance, will be explained with reference to a new case study on large diameter DCIS piles. Examples of the routine use of the system will be presented to illustrate how automated monitoring of installation parameters can be used to raise the standard of reliability, efficiency and sustainability on piling projects. The conclusions to the paper will cover the key features and operational challenges characterising real-time monitoring of the execution of geotechnical works as developed from a number of years of experience of using a rig based data acquisition instrumentation system.INTRODUCTIONDriven Cast In-Situ (DCIS) piles have a long and successful history of use worldwide. The process, where a temporary steel drive tube, sealed at the bottom with a sacrificial base plate, is driven into the ground and filled with concrete before the tube is withdrawn, is well known (BS EN 12699, 2001 and Egan, 2013). Examples of large structures supported on DCIS piles installed by Keller UK include the Millennium Dome (now the O2 Arena) and the 2012 Olympic stadium in London.In recent times advances in piling rig instrumentation and telecommunications have enabled a new level of sophistication in the recording of installation parameters and the validation of pile performance. It is now possible to embed these features into the DCIS design and installation process which has improved the quality and efficiency of DCIS piling.This paper summarises the development and operation of a real time data acquisition and processing system for DCIS piling, but which is equally applicable to other forms of driven piling (for example concrete precast piling)."

Jan 1, 2014

By W. P. Yant, C. E. Traubert

"INTRODUCTION Canister-type gas masks have become an essential part of the equipment of many industries, not only for use in emergencies, but also in performing normal operations of industrial processes and procedures, particularly where ventilation is not practically or economically feasible. They are also used widely for enhancing safety of operations which previous to the development of gas masks had been performed in harmful atmospheres.Since the inception of industrial gas masks the Bureau of Mines has been actively engaged in endeavoring to increase the efficiency and safety of these devices, and this bureau has become a source of advice to manufacturers in producing devices of good quality and to industry in the proper selection and use of these devices. In order to give first-hand information and keep current with the demands and needs of industry it is necessary to perform investi-gations from time to time. This report deals with tests of certain types of commercial gas-mask canisters for protection against mercury vapor.TYPES OF CANISTERS EXAMINEDThis investigation included tests of the following types of canisters:(a) Gas-mask canister filled with 725 c.c. of granular activated charcoal, 8 to 14 mesh, and of a quality used in gas masks which meet the Bureau of Mines approval requirements 4 for protection against organic vapors."

Oct 1, 1932

By D Engelhardt, G Lane

The Cadia mine has shifted from an open pit operation to the Cadia East underground panel cave. The resulting increase in milled tonnes, more competent ore and the decrease in fines production through shifting to panel caving were predicted to require an increase of over 25 per cent in installed power. This expansion was accomplished via the installation of secondary and high pressure grinding rolls (HPGR) crushing of the ore, with the semi-autogenous grinding (SAG) mill receiving a combination of primary, secondary and HPGR crushed feed. This design, criteria and rationale for selection was presented at the SAG Conference 2011. This paper reports on the initial impact of secondary and HPGR crushing on the circuit performance with the new panel cave feed.CITATION:Engelhardt, D, Lane, G and Powell, M S, 2014. Cadia expansion – the impact of installing high pressure grinding rolls prior to a semi-autogenous grinding mill, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 233–240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Daniel Lozada

La unidad de producción polimetálica de Yauliyacu, ubicada en la localidad de Casapalca, Lima, tiene una presa de relaves en el paraje de Chinchan del mismo departamento. Sin embargo, dado que la presa nueva Yauliyacu culminaría su función y que la presa auxiliar Tablachaca no contaba con la suficiente capacidad de almacenaje, Centromin Perú evalúo otras alternativas para la ubicación y construcción de una nueva. De acuerdo al estudio realizado, se encontró que la quebrada de Chinchan era la más adecuada puesto que ofrecía mayor capacidad de producción y se descartó las de Corina y Tablachaca. En este sentido, el presente texto describe las características de la quebrada, el diseño del depósito de Chinchan, su proceso de construcción, la limpieza de fundación, el análisis de la estabilidad física y química, la implementación para mejorar la estabilidad de la presa, la mejora de calidad del aire en la zona del depósito, el programa de inversiones y el plan de cierre del relave.

Sep 13, 2001

The work to be described is part of a comprehensive research on the influence of impurities on the properties of lead. The author had previously compared an electrolytic lead containing less than 0.002% total impurities with a commercial lead containing 0.008% impurities (excluding oxygen) and had shown that the former recrystallised more readily than the latter under the same conditions of cold work and annealing. This difference in properties was attributed to the difference in purity. Electrolytic lead containing only 0.0005% total impurities has been prepared and cast in vacuo. Some interesting effects have been obtained by working and annealing this lead, and by adding silver to it. The preparation of this lead, and the effects obtained thereon, are described in this paper. Thepaper is divided into the following sections:(I) Preparation of electrolytic lead.(II) Vacuum Casting.(III) Effect of Cold, Work and Annealing on two Electrolytic Leads, having 0.002% and 0.0005% Total Impurities respectively.1 Research Fellow, Dept. of Metallurgy, University of Melbourne.2 Proc. Aust. lnst. Min. Met., 1932, 87, 145.

Jan 1, 1934

By B. S. Crocker

Pebble grinding was used at Lake Shore Mines in 1949. A full description of experimental evidence and test plant results was published in 1952 1 and further operating details in 1954 2.' In more recent years the term autogenous grinding has been coined and is now frequently seen in the technical literature. Autogenous crushing and/or grinding covers any grinding mill in which the larger pieces of ore are made to grind the fine pieces; the crushing and grinding may be either dry or wet. This discussion deals only with wet autogenous grinding, and only in the fine grinding part of the circuit, i.e., from 6 mesh to 92 pct —325 mesh. The term pebble milling could apply to fine autogenous grinding in which the pebbles are made from the ore itself, or it could also refer to grinding with pebbles, such as flint pebbles, from a source outside the mine. The first mill to use screened ore to grind the ore (1949) was Lake Shore Mines, Kirkland Lake, Ont. Pebbles were screened from the jaw crusher discharge and used in 5x16-ft tube mills which had been converted to 6 ft 8 in. by 16-ft grate discharge pebble mills. The same general practice was adopted the following year by the Wright-Har-greaves Mine in Kirkland Lake. Shortly after that the Neptune Mines in Nicaragua started correspondence with the writer concerning the possibility of using screened ore for grinding in their plant. They first ran some plant-scale tests which confirmed the Lake Shore findings, with the ultimate result that their plant was successfully converted in 1956 to an autogenous grinding plant. In 1957-1958 the writer was successful in converting the grinding plant of Renabie Mines in northern Ontario to autogenous grinding. In all these plants the existing grinding equipment was converted, usually by expanding the diameter of the shell to make the change from steel grinding to ore pebble grinding mills. In all the above plants primary grinding was done in either small rod mills or ball mills. These mills first reduced the pebble mill feed to about 6 mesh. The final grinding in the pebble mills varied from 75 pct —200 mesh to 92 pct —325 mesh. At Lake Shore three stages of pebble milling were used, with a different size pebble in each stage. In other parts of the world interest was being shown in this form of grinding, and in March 1952 the writer had some correspondence with the mill staff at Outokumpu in Finland, with regard to the pebble system used at Lake Shore. At Stockholm in 1957 the account of the crushing and grinding system at Outokumpu was presented in a paper by H. Tanner and T. Heikkinen.V his is the only ore grinding plant that does not use grate discharges on its pebble mills; trunnion discharges equipped with heavy reverse spirals retain the pebble load. The first new mill designed to use screened ore as a grinding medium was the Bicroft mill at Bancroft, Ont., which began operation in the fall of 1956. In 1957 this plant was followed by similar installations at Faraday Mines, also in the Bancroft area, and the North Rankin Nickel Mines in the North West Territories. In 1958 the Dyno Mill at Bancroft was converted, using the same type of grinding. Since all these plants, designed by Kilborn Engineering (1954) Ltd., were originally planned as pebble grinding mills, they were able to take full advantage of the latest design and technique. They are neat in appearance and very efficient and easy to operate. Effect of Ore Hardness: It is often commented that this type of autogenous grinding applies only to hard siliceous ores. Experience has shown that this is not so. In the past ten years the author has had an opportunity to test more than a dozen ores, several of which were quite soft. One of these was shale. The softer ores actually make better looking pebbles than the hard ores. These soft ores produced no particles in the intermediate size range which could not be ground by the largest pebbles in the mill charge. Slabby ores, such as shales, make a suitable pebble for the —6 mesh grinding. It is not generally recognized that for fine grinding a spherical medium is not essential or more efficient. Another frequent objection to pebble grinding is the belief held by some operators that there is too much variation in the hardness of their particular ore to make it acceptable as a source of pebble media. Experience has also shown that this is not a serious problem at all. The variation in pebble load due to changes in the ore hardness is nothing like as great as most people would expect, and the method used for feeding the ore and controlling the the load in the mills is more than sufficient to take care of daily variations in ore hardness. This point

Jan 1, 1960

By Howard J. Pincus

The purpose of the study is to investigate the effects of fracture filling and associated alteration on the mechanical behavior of rocks. Results are presented for specimens from the Climax and Henderson mines in Colorado and the San Manuel mine in Arizona. The rock types studied from each location are from 1) Climax, medium-grained - granite, fine-grained granite, granite porphyry, schist, and gneiss; 2. Henderson, rhyolite porphyry; 3. San Manuel, quartz monzonite and quartz monzonite porphyry. A description of the rocks was made including: color, texture, mineral composition, composition and fabric of fracture fillings, density and porosity. Unconfined and triaxial compression tests were run on the Climax and San Manuel specimens. Sonic relocities were measured during the compression tests; Shore sceleroscope hardness was measured before the compression tests. Tentative conclusions are that some relation appears to exist between compressive strength and the following properties and features for all the specimens: dynamic Young's modulus, sonic velocity, density, rock composition, and composition and fabric of fracture fillings - veinlets. There appears to be some relation between compressive strength and Shore scleroscope hardness and porosity for quartz monzonite (San Manuel). A relation appears to exist between compressive strength and texture for schist and between com¬pressive strength and extent of failure on fracture fillings for fine-grained granite, schist, and gneiss (Climax). We plan to perform additional analyses of data collected so far and data yet to be collected in the next few months, with emphasis placed on devising a practical index of alter¬ation that can be used in the field. Limitations on interpretations arise from such factors as heterogeneity of the rocks studied, the small range of confining pressures used, and other factors presented in the text.

Jan 1, 1973

By Northcutt Ely

This volume summarizes mining and petroleum legislation in 30 jurisdictions of the Western Hemisphere. Within these jurisdictions, primary attention is given to requirements that must be met in each country for acquisition of rights to permit development of mineral resources. Coverage includes: First, identification of the controlling laws or statutes governing minerals acquisition and reference to the administrative authority; second, analysis of the laws governing mines and quarries and their products; and third, analysis of laws applicable to natural gas, petroleum, and related materials. Where pertinent, sections dealing with historical background or administration have been added. In countries where minerals are subject to control of States or Provinces, those areas are considered separately from the central government.

Jan 1, 1970

By Wayne N. Marchant

Introduction The issue of coal mining safety plays an important role in the United States' growing dependence on coal to supply its future needs. This article will address the federal government's role, principally the US Bureau of Mines, in meeting this challenging growth and demand while reducing the social and economic costs attributed to injuries and fatalities in underground mining. Some interesting facts and projections with respect to the nation's energy picture will be discussed. This includes the distribution of its reserves and the projected role of coal in the energy and economics of the nation's future. Underground mining will continue to be an important means of providing this coal. The author will discuss how the Bureau of Mines' research program addresses the problems of health and safety that grow out of the demand for more coal. Future projections First, a synopsis of salient facts and projections concerning the US's situation with respect to energy and the economy. Figure 1 depicts the relative quantities of recoverable energy reserves in the United States by their type. Most people are aware of the nation's use of oil. We hear a lot about natural gas. And we are aware of the controversy over the use of nuclear energy. But, while looking at Fig. 1, the question becomes, "Where will our fuel to meet the demand for energy in the future most certainly have to come from?" With 82% of the nation's recoverable fuel reserves being coal, the answer is irrefutable. Coal will be that source. Figure 2 is the present market for coal. It shows that 77% of the coal mined goes to supply electric utilities. Therefore, the coal industry as a whole is most sensitive to the trends and demands for electricity. It is less affected by what happens in other markets, such as export and direct industrial use. In fact, the coal industry is three times more sensitive to the electric utility market than to all other markets combined. Therefore, the trend in the demand for electricity must be examined. Electricity demand is expected to increase steadily over the next 15 years. It is projected to grow from its present 2.3 trillion kWh per year to 3.5 trillion kWh per year by the year 2000. The fuel to supply this increase in demand must come from somewhere. The question is "How much of this extra fuel will be coal?" Although the demand for electricity is predicted to increase, the demand for coal does not necessarily follow. Coal must maintain its fraction of the energy sources used for electricity generation if its demand is to increase at the same or greater rate as electricity. Except for a near-term dip in demand due to a slight increase in nuclear capacity, the domestic electric generation accruing to coal will go from 56% in 1985 to more than 60% in 2005. Thus, the predicted trend is for coal to become a larger part of the fuel mix for electric power generation. Similarly, looking at the most recent forecast for total coal consumption trends, it can be seen that for electric power generation alone, the coal industry must be able to supply an additional 316 Mt/a (348.5 million stpy) by the year 2000 (Fig. 3). It must be stressed here, though, that without significant improvements in mining safety, it can also be easily predicted that injuries and fatalities will increase in proportion to the increase in coal production. Will society consider that acceptable? This author does not believe so. Figure 4 examines the effect of coal prices on the price of electricity. The projections show that the already high proportion of fuel cost will become a greater fraction of the consumer price for electricity. Specifically in 1985, 36% of the price of electricity was the cost of the fuel. In 1995, 46% of the price of electricity will be the fuel cost. That implies that the price of coal will have an increasing influence on the consumer price for electricity. Thus, as coal is used more to generate electricity and as fuel becomes a greater

Jan 4, 1987

By Thornton L. Neathery

Vertical magnetic surveys have been made over about 3, 150 miles of the crystalline area of east-central Alabama. A contour map (100-gamma interval) showing regional magnetic anomalies has been prepared (scale 1:250,000) from data points located at quarter-mile intervals on all public roads. Small one- and two-station anomalies were eliminated, leaving only areally extensive anomaly features associated with regional geology. The regional gradient was "filtered" from the basic data and the resulting magnetic configuration compared to the regional geology. Regional lines of vertical magnetic intensity trend northeast and follow the structural framework of the area. Correlations can be made between a large number of geologic and magnetic features. The strongest regional anomalies are associated with the Goat Rock, Bartletts Ferry, Towaliga, and Brevard fault structures. The Inner Piedmont area is characterized by a broad regional high. The magnetic values of the northern Alabama Piedmont grades gently northwestward, disrupted occasionally by elongate highs and lows associated with amphibolites or granites. Scattered throughout the Piedmont are anomalous areas of high magnetic intensity; some are related to magnetic-bearing rocks, and some Indicate possible mineralization. Most of the anomalies have not been evaluated,

Jan 1, 1972

By Madgwick J. C

The monosaccharides glucose, galactose and arabinose, and the polyols glycerol and mannitol (0.1 Ufo WIV) supported pure and mixed culture heterotrophic bacterial manganese leaching of solid pyrolusite (MnO2, 2% W/V) to yield 14-38 mg/litre manganous ion in 3 days from a simple mineral salts media at 30°C. Supplementation of pure bacterial isolates growing on glucose with soluble intracellular photosynthate from freshwater algae (0.07 g/l carbohydrate) and marine algae (0.11 g/l) led to an improvement in Mn++ yields of 24 and 100 per cent respectively. Extracellular products of the freshwater algae (0.3 g/l carbohydrate) boosted recoveries by 57 per cent.

Jan 1, 1982