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By Hani Mitri

A new monitoring device called SAFEBOLT (Stress And Force Evaluator in Bolts) has been recently developed. The device SAFEBOLT, essentially replaces the load cell, it permits the monitoring of bolt axial load from the time of its installation underground. The SAFEBOLT system consists of a portable readout unit, connecting cable and the SAFEBOLT device, which is installed in the bolt head. SAFEBOLT can be installed on any industry standard rockbolt. No special installation method is required; the conventional method of bolt installation by the stoper or roofbolter remains unchanged. The device is completely encapsulated in the bolt head, which makes it resistant to corrosion, rugged, and free of any electrical wires. Pilot tests at three underground Quebec mines were carried out and helped improve the initial design of the device connector. The paper reports on two of such pilot tests.

Jan 1, 2001

By AIME AIME

FOR many years it has been the invariable custom of the Institute, in addition to its annual meeting in February, to hold a technical meeting in the fall in some mining or metallurgical center in the West. As the activities of the Institute have increased, and especially since the absorption 'of the American Institute of Metals, there have for a number of years been two fall meetings. Never before in the history of the Institute have there been three meetings in addition to the annual meeting in February; in 1920, however, three important fall meetings are to be held. The general Institute trip will be made this fall to the Lake Superior iron and copper country. Members will leave Buffalo on August 20 by steamer, visit the copper mines in and about Houghton, the iron mines of the Marquette and Iron Ranges of Michigan and the iron mines of the Mesabi Range in Minnesota, and' return to Buffalo by steamer on September 3. Technical sessions will be held at Houghton, Minneapolis and Duluth. For a long period it was customary for the Institute to visit the Lake Superior country about every seven years. This trip, however, will be the first visit since 1904. The unprecedented development in both copper and iron mining in this section during this period will make this trip of unusual importance. In addition, a notable series of papers will be presented.

Jan 1, 1920

By C. Sui, J. E. Nesset, M. Li, J. Y. Kim, S. L. Chryssoulis

"A plant study of zinc rougher flotation at Brunswick Mining was conducted using lime, soda ash and a combination of both as the pH modifiers in order to establish the effects on sphalerite and pyrite kinetics and mineral selectivity. The plant sampling and analysis was augmented by surface analysis using TOF-LIMS, SEM and XPS as well as fundamental precipitation and surface-charge studies in the sphalerite Ca/C03/S04 system.The results revealed the important role of carbonate ions in cleaning the sphalerite surface for effective activation by CuS04 to occur, and the beneficial role of combined soda ash and lime in increasing pyrite and galena depression.1.0 IntroductionThe studies reported in this paper were initiated as part of an investigation into the causes of a particularly pronounced seasonal deterioration in metallurgical performance at the Brunswick Mining concentrator during the summer of 1995. The concentrator treats a complex base metal ore having a typical feed composition of 9.0% Zn, 3.5% Pb, 0.4% Cu and 100g/t Ag at a current throughput of 9,000 TPD, although at the time of the problem in 1995, the average production rate was closer to 10,500 TPD. Zinc, lead, copper and bulk (zinc-lead) concentrates are produced with overall metal recoveries of 86% zinc, 63% lead, 60% copper and 60% silver; results which are typical of the lower recoveries associated with fine-grained, highly complex VMS and SEDEX type deposits. The main economic minerals of interest are an iron-containing (7% Fe) sphalerite, galena and chalcopyrite with the main diluent (about 60% wt) being pyrite.Figure 1 shows a simplified flowsheet of the Brunswick milling circuit while the seasonal decrease in summer metallurgy in 1995 is illustrated in Figure 2. Of significance is the rapid drop in copper and lead recovery in June while there is an apparent delay until late August-September before the zinc deterioration reaches its lowest point. A more typical seasonal effect within the experience of the authors is the reverse of the Brunswick situation, namely an improvement in summer performance thought to be associated with improved differential flotation kinetics during warmer weather leading to better mineral selectivity. The historical Brunswick experience was particularly severe during the summer of 1995 with estimated incremental losses of $10 Million for this period. The potential of the very significant economic benefits to be gained from understanding and hopefully improving the annual drop in performance led to an investigation involving the minesite metallurgical group, the Noranda Technology Centre (NTC) as well as researchers in Professor Jim Finch's group at McGill and the surface analytical services and interpretive skills of AMTEL."

Jan 1, 1998

By M. F. Handley

This paper covers in situ stresses in the Earth?s crust prior to any man-made disturbances, such as mining. It introduces the Southern African Stress Database, which contains primitive stress measurements obtained from locations spread all over southern Africa. The measured stress data shows large variability without any visible trends, except a relationship with increasing depth. The stress database is reviewed briefly, establishing means to measure the variability or dispersion in the measurements, and showing that the dispersion is not as much a result of experimental error as it is a feature of primitive stress. The paper demonstrates from the beginning that the state of stress in rock is highly variable, but that there are well-defined maximum and minimum limits to all the stress components in rock. Formal error analysis is introduced to check the consistency of the database and to separate out a database of consistent stress measurements for use in a primitive stress model. The aim is to provide a picture of primitive crustal stress based on objective stress measurements together with interpretations of how the primitive stress can be affected by the five main influences; namely, depth, rock mass properties, tectonism, isostacy, and erosion. Four elementary models for primitive stress are introduced and compared with the measured data. It is quite clear that none of the elementary models is sufficient to describe the data. In the absence of a better model, this paper suggests a generic model based on the Hoek-Brown failure criterion and the consistent stress database, since it incorporates the variability in the stress tensor that is likely to be encountered underground all over southern Africa. Rock engineers should take every opportunity to obtain local primitive stress data at every mining operation and civil engineering project, and to adjust the proposed model accordingly Keywords primitive stress, Southern African Stress Database, error analysis, generic primitive stress model.

Jun 1, 2013

By Raymond B. Ladoo

Abrasives include the substances, natural or artificial, that are used to grind, polish, abrade, scour, clean or otherwise remove solid material, usually by rubbing action but also by impact (sandblasting, for example). They do not include abrasive tools-for instance, lathe tools and files-or polishing agents such as waxes, which act by filling pores. Detergents and cleaners whose action is chemical rather than physical are omitted although some chemical-action polishes and cleaners may also contain solid abrasives; for example, many automobile and metal polishes. General Considerations The most important physical properties of materials that qualify them for use as abrasives are hardness, toughness (or brittleness), grain shape and size, character of fracture or cleavage, purity or uniformity. For making bonded grain abrasives such as grinding wheels, additional important factors are stability under high heat and bonding characteristics of grain surfaces. The economic factors of cost and availability are always important. No one single property is paramount for any use. For some uses extreme hardness and toughness are needed, as in diamonds for drill bits; for others, the factors of greatest importance are hardness and ability to break down slowly under use, to develop fresh cutting edges when grains become worn-for example, in garnet for sandpaper, neither highly cleavable or friable grains nor extremely tough grains are wanted. For still other uses, great hardness is objectionable; for example, abrasives for dentifrices and for glass-cleaning soaps. For the most efficient use in the more critical applications, the different types of abrasives are rarely completely interchangeable; thus, while crushed quartz and garnet are both used in sandpaper, the papers are not at all interchangeable in their use applications. In the last analysis, the choice of a high-grade abrasive depends upon the quality and quantity of work done by the abrasive per unit of cost. Initial cost of an artificial abrasive. may be much greater than that of a natural abrasive but the artificial abrasive may do so much better work than the natural one, and do it so much faster, that the ultimate cost will be less. It is on this basis that artificial abrasives have largely replaced natural abrasives for grinding metal. Classification Abrasives may be divided into two general classes, natural and manufactured. The former includes all rocks and minerals used for abrasive purposes without chemical or physical change other than crushing, shaping or bonding into suitable forms. Manufactured or artificial abrasives are made either by heat or chemical action from metals or mineral raw materials. On page 2 is a list of the most important abrasives, classified as to inherent types and as to forms in which they are used industrially. For most types of use there are manufactured products that can be substituted for the natural products, usually at higher initial

Jan 1, 1960

By Julio E. Claudeville

Approaches and Lessons Learned ??Address business needs?local skills training and employment ?local procurement programs ?health and safety programs ??Ensure consultants/ advisors/ contractors apply Company standards ?especially in the field/ locally ?will not be differentiated from the Company itself

May 1, 2006

By C. P. Gazzara and

The modulus of elasticity and yield strength of commercially pure, annealed titanium sheet was investigated at room temperature as a function of strain rate and direction of loading. The value of E varied with direction of measuremeni in the sheet but was unaffected by strain rate in the range 0.04 x 10-to 10-2min-1. The yield strength increased with increase it2 strain rate and varied with specimen orientation. VALUES of the modulus of elasticity, E, in tension for commercially pure titanium have been reported at from 14 to 20Xl06 psi.' Reasons suggested for this variation have been a) composition, b) strain rate, c) texturing, and d) creep. For example, alloys of titanium with aluminum, manganese, and nitrogen have yielded modulus values of from 12.5 to 16.8 x lo6 psi at room temperature.' It was shown by Klier that the modulus in titanium plate was sensi-tive to strain rate. while Dotson and kattus meas- ured variations in E as the strain rate was increased from 3X to 60 min-l. For RC-7OA, 0.040-in. titanium sheet at room temperature Dotson and Kattus found that the average values of E, for specimens in the rolling direction, increased from 14.7 to 16.0 X lo6 psi as the strain rate increased. Simultaneously, the 0.2 pct yield strength increased from 74,700 to 95,700 psi for the same specimens. Differences in yield strength and E have been reported as a function of directionality in titanium sheet.= Dotson and Kattus report such an effect, and Feola6 found in annealed titanium sheet marked anisotropy in tensile strength, yield strength, reduction in area and elongation at room temperature, with

Jan 1, 1961

By Henry Fay

The erosion of guns is a complex problem which can be solved only by a detailed study of all the factors involved. In the present paper it is proposed to submit the results of observations and experiments which have extended over several years. Certain facts have been established and preliminary reports have been published.' Conclusions have been reached since then which, it is believed, are worth presenting for the purpose of promoting discussion, and with the hope that ultimately the whole truth will be known. The particular phase of the problem which will be presented here is the hardening of the inner surface of the gun tube. It has been known for a long time that after firing a large caliber gun for some time, the surface of the metal becomes hard and brittle, cracks, and wears away.2 The character of this phenomenon may be learned by an examination of some results which are typical, obtained from a detailed study of a 12-in. gun. The gun was trepanned and rings representing various sections of the gun were cut out for examination. The first ring represented the metal at the muzzle end, and the other rings were removed at approximately 120, 240, 325 and 337 in., respectively, toward the breech end. The appearance of the surface of the metal in the different sections is shown in Fig. 1. The greatest amount of wear and maximum amount of hard surface layer was found in section marked E, which is nearest the powder chamber and at the beginning of the rifing; the maximum amount of cracking in D; the maximum amount of copper deposition in C. Section B showed heat cracks on both lands and grooves, and section A showed heat cracks on the driving edge of the lands only. There was much flow of metal in both sections E and D, and there was progressively less effect noticeable toward the muzzle end. The polished cross-section of these same pieces is shown in Fig. 2. The extent of the erosion is greatest nearest the powder chamber, and diminishes toward the muzzle end.

Jan 1, 1917

By Calvin Bjorne, John Keeley

In the face of a highly competitive iron ore market, the Cleveland-Cliffs Iron Co. developed a process now being practiced at the company's Republic mine in Michigan's Upper Peninsula. By this process, a specular hematite crude ore is being beneficiated to produce a high iron-low silica concentrate with a suitable size structure for the production of a high quality pellet. This process involves crushing, primary grinding and primary flotation, followed by regrinding, heating and refloating the primary flotation concentrate. The ores consist predominantly of specular hematite with relatively minor amounts of magnetite and martite in a recrystallized chert gangue. A wide variety of silicates have been identified, particularly in association with intrusives of various description. The more abundant of these are sericite, talc, grunerite and chlorite with some carbonates, primarily calcite.

Jan 6, 1964

By E. Hornbogen

Discontinuous precipitation in a iron can occur by at least two different mechanisms. These mechanisms are compared, using observations made on an Fe-22 at. pct Zn alloy and an Fe-19.5 at. pct Mo alloy. In the Fe-Zn alloy, precipitation began on grain boundaries. These boundaries moved into the supersaturated solid solution, providing nucleation sites and an easy path for diffusion. The precipitated phase pew as lamellae, perpendicular to the PRECIPITATION reactions are called discontinuous if the nucleation of particles does not occur on individual sites in the supersaturated matrix.' In discontinuous precipitation, nucleation and growth occur on a reaction front that moves into the supersaturated solution and leaves a two-phase aggregate behind. The term cellular precipitation2 has also been used, but the term autocatalytic precipi- moving reaction front. The orientation of the depleted iron differed from that of the supersaturated iron. In the Fe-Mo alloy the growing precipitate particles apparently created dislocations in the growth front which served as nucleation sites. The precipitate grew on (110) planes of the iron, and growth occurred through volume diffision. The depleted iron retained the orientation of the supersaturated solid solution. tation seems to describe the nature of such reactions best. The basic effect of such a precipitation mechanism in a solid is that it is able to move or create sites that can catalyze nucleation. Such sites can be grain boundaries and dislocations. A mechanism of autocatalytic precipitation must, therefore, include some rational process by which a grain boundary may move into the supersaturated matrix or by which dislocations may be generated in front of the reaction. Discontinuous precipitation is always in competition with individual nucleation and growth of par-

Jan 1, 1963

By Richard R. Klimpel

The purpose of this paper is to summarize some of the author's experiences in applying population balance models to a variety of industrial grinding circuits. Over 26 separate industrial circuits have been studied in detail during the last 10 years, each unique in its equipment type and layout as well as in the material (s) being ground. The success of the population balance approach during these studies was variable. Fourteen of the circuits were shown to be very amenable to such an approach while the remainder had conditions present that sufficiently violated the standard population balance assumptions so that the analysis was of less than optimal utility. Some discussion of the importance of standard population balance assumptions will be given. It is increasingly becoming this author's opinion that the use of population balance models has its greatest utility in defining logically and cheaply (in contrast to actual physical testing), the relative limits and comparisons of different proposed circuit configurations and changes in equipment types and/or operating conditions. As far as specific quantitative predictions and actual optimization of existing plant performance, the results of applying the population balance approach have been often disappointing and need to be coupled at the plant level with other engineering quantification techniques in order to achieve desired improvements.

Jan 1, 1992

By Robert W. Hunt

I have frequently stated that while the chemical composition of steel is important, yet even greater importance is connected with the mechanical and heat treatment of the metal. During the past year I encountered such a positive example of that fact that I deem it worth putting upon record. A prominent railway system divided an order for open-hearth steel rails between two steel works, both of which are under the control of the same corporation; giving to one about 18,000 tons, and to the other 7,500 tons of the same section and to be made under the same specifications. The rolling results obtained in the two mills varied so widely that a study of the figures is intensely interesting and serves to illustrate the advantages obtained by carefu1 ingot casting, and, quite as pertinently, the possible benefits of careful subsequent heating and rolling with moderate reductions in the rolling process. The smaller order was rolled complete in four installments during the same months that the larger order was being made in six separate installments; but, to permit of exact comparisons, the totals of the four installments (completing the order with the mill which I will call A) are given with the totals of the first four installments of the larger order, made by the mill designated as B. These rolling results are: Mill A. Mill B. Number of rollings,............................................ 4 4 Total number of rails rolled................................ 18,278 27,832 Percentage of rails cut to short lengths because of flaws near ends, etc......................................... 0.7 7.6 Percentage of rails made second quality for flaws, etc. 0.9 6.3 Percentage of rails scrapped for flaws, etc............... 0.6 4.5 Percentage of rails scrapped for failure at drop test... none 3.4 It should be stated that the figures given above cover all the reasons for putting the rails in the classes stated, Thus a part of the percentage of rails cut to short lengths may have been

Jan 1, 1914

By Campbell J

After eighteen months of discussions with employees and their trade unions, multiskilling was introduced at the Hellyer concentrator in early 1989, coinciding with the plant commissioning. Multiskilling was introduced with the Hellyer Skills Acquisition Program together with intensive training and performance assessment. Design innovations have helped to improve productivity. There have been some difficult times with personnel tending to return to the old and traditional ways of operating. In general, these have been overcome to ensure the success of multiskilling at Hellyer. The main factors making multiskilling effective have been continual training and assessment, and a competent team of shift supervisors. This has improved work standards towards the high level expected from a multiskilled approach without compromising safety standards.

Jan 1, 1991

By Liam Findlay

Optimizing a production schedule with semi-mobile in-pit crushing & conveyance (IPCC) requires integrating extraction sequence, destination policy, crusher relocation, conveyor layout, and truck fleet investment decisions. An integrated stochastic optimization framework is proposed to produce long-term schedules for mining complexes using multiple semi-mobile IPCC systems. The optimizer selects the crusher locations and designs the conveyor routes from anywhere in the mines. The stochastic framework considers simulated multi-element orebody realizations and manages associated risk. A hybrid metaheuristic based on simulated annealing and evolutionary algorithm is implemented for the optimization. The method is demonstrated using an iron ore mining complex.

Jun 25, 2023

By C. W. Lawr

THE ores mined by the Santa Gertrudis Co. at Pachuca, Mexico, are mainly silver-bearing; they also yield some gold and carry a little copper. Strong cyanide solutions are used to dissolve the silver and gold, and the mechanical loss of cyanide at the tailings filter has been considerable. Prior to the year 1923, the pulp, after agitation, was given a 35 to 37-min. wash with barren solution in a Butters-type leaf filter; the discharged slime cake was repulped and pumped into eight Merrill self-sluicing slime presses in which the slime was given a further wash with barren solution for 25 to 35 min., followed by a 10-min. water wash. At that time the barren solution titrated around 0.350 per cent. free KCN and 0.500 per cent. total KCN. (Aero brand cyanide is used.) It can readily be seen that a 10-min. water wash would leave considerable cyanide in the filter cake, which of course was a total loss. This averaged 0.522 kg. (1.15 lb.) KCN per ton of solution. As the daily discharge to. the dam was 1600 tons1 of slime of a 2: 1 ratio of liquid to solid, the value of this mechanical loss of cyanide was an important item and its recovery held alluring possibilities.

Jan 1, 1929

By JoAnn Silverstein, Eric A. Marchand

Competition between Thiobacillus ferrooxidans and non-iron-oxidizing heterotrophic bacteria was induced by the addition of glucose to a co-culture of T. ferrooxidans and A. acidophilum in an oxygen-limited environment. Iron oxidation was inhibited as dissolved oxygen was used preferentially for glucose metabolism. Furthermore, as the water became anoxic, glucose was consumed along with the oxidized iron species (Fe3+) during iron respiration resulting in a pH increase from 2.0 to 4.0. Results suggest that biologically mediated acidification of drainage water can be reversed by dispersion of an easy to degrade, soluble, and inexpensive carbon source such as glucose into the subsurface.

Jan 1, 2000

By R. A. Wood, R. I. Jaffee, H. R. Ogden, D. N. Williams

The tensile properties, creep resistance. and thermal stability of highly alloyed Ti-Al-Zr alloys were examined. On the basis of these studies, the Ti-7Al-1ZZr composition was selected for more complete evaluation. The alloy was found to be weldable and free from excessive directionality. In addition, it developed maximum properties without requiring heat treatment other than an annealing operation in the alpha field. The alloy was recommended for scale up and is presently being investigated on a production-level basis. One of the more attractive properties of titanium alloys is their ability to withstand stress at moderately high temperatures, and a considerable amount of effort has been devoted to increasing the maximum service temperature of titanium alloys. This work has suggested that the optimum alloys for high-temperature service will be single-phase a (close-packed hexagonal) alloys containing significant amounts of aluminum. However, the maximum amount of aluminum which can be alloyed with titanium is between 6 and 8 pct,l since at high-aluminum contents an embrittlement reaction occurs in the anticipated service temperature range, 800" to 1100°F. It has been shown that the embrittlement reaction involves decomposition of the high-aluminum a phase to one or more new phases.' Since this reaction does not occur at intermediate or low-aluminum contents, it was felt that intermediate Ti-A1 alloys might be strengthened by a-soluble ternary additions without inducing the embrittlement reaction. The first alloying addition considered was tin, which shows extensive solubility in a titanium and has moderate strengthening tendencies. Unfortunately, it was soon apparent that tin also promoted the embrittlement reaction, and that to obtain a stable alloy, the aluminum content had to be reduced as the tin content was increased. The second alloying addition considered was zirconium, which is similar to tin in its effects on titanium. This element did not contribute to the embrittlement reaction and, in fact, appeared to increase the maximum amount of aluminum which could be alloyed with titanium without inducing instability. This paper describes an investigation of the Ti-A1-Zr a alloy region. Alloys containing from 4 to 12 pct A1 and from 6 to 15 pct Zr were examined. The properties of these alloys are described and the bases for selecting an optimum composition is outlined. This composition, Ti-7A1-12Zr, is presently being scaled up in tonnage quantities, and is being evaluated extensively throughout the industry. In addition to presenting the basis for its selection, this paper presents a description of the properties developed in laboratory material as determined during the alloy investigation. These properties suggest that this alloy can fill an important position in applications requiring light weight, fabrica-bility, weldability, and strength to 1000oF or higher. EXPERIMENTAL PROCEDURES Titanium alloy ingots were prepared by inert electrode arc melting under an argon atmosphere. Alloying elements used were 110 Bhn titanium sponge, high-purity aluminum, and reactor-grade zirconium. Pancake-shaped ingots were prepared weighing approximately 300 g. The composition of the ingots was checked by weight measurements before and after melting. The pancake ingots were forged at 2000°F to approximately half their original thickness to give a flat plate roughly 1/2 in. thick. This plate was then rolled at 1800' to 1600°F to 0.250 in. thick. All of the alloys examined fabricated well. However, alloys containing 15 pct Zr tended to overheat due to exothermic oxidation, and scaling was excessive. As might be anticipated from its effect in decreasing the ß transus, increased zirconium appeared to improve fabricability somewhat, especially during rolling at lower temperatures. Except for a limited study of heat-treatment response, all alloys were examined in the a-annealed condition. Prior to heat treatment the a and ß tran-sus temperatures were determined by metallo-graphic examination of samples quenched after annealing at 50-deg intervals in the transformation region. These data are shown in Fig. 1. Recrystal-lization appeared to occur in about 1 hr in the range 1300º to 1500ºF. Therefore, alloys were annealed for 1 hr at 1550ºF (4 and 5 pct Al), 1600ºF (6 through 7-1/2 pct Al), or 1650°F (8 or more pct Al). This produced an equiaxed a grain structure. In most alloys, a "ghost" structure was visible after the a-annealing treatment, as shown in Fig. 2. This structure apparently resulted from the acicular

Jan 1, 1963

By C. H. Mathewson

BERYLLIUM, magnesium, zinc and cadmium, together with mercury, constitute a coherent sub-group of the periodic system and these metals, excepting mercury; have been studied in sufficient detail by the new X-ray diffraction methods to prove their common adherence to the hexagonal close-packed type of crystal structure with a progressive increase in axial ratio as we pass through the group from beryllium to cadmium. The first four columns of Table 1 summarize the data on crystal structure of these metals reported in the International Critical Tables.1 The last two columns are based on results obtained in the present investigation. TABLE 1.-Lattice Constants and Twinning Law of the Be-Cd Group of Hexagonal Metals Dimensions of Unit Axial Cell, A Ratio Description of Twinning Element a° c° (c°/a°) Composition Axis Plane Beryllium 2.28(3) 3.60(7) 1.58 {1012} Probably 1 {1012} Magnesium 3.22 5.23 1.621 ,1 {1012} Zinc 2.65(7) 4.94(8 1.86(2) 11012 } 1 {1012) Cadmium 2.98 5.63 1.88(5) {1012} Probably 1 {1012} Twinning has often been observed in zinc and cadmium. The general aspects of this twinning are abundantly illustrated by photomicrographs, diagrams, etc., in the papers by Romig, and Mathewson and Phillips reported to this Institute in 1927.2. A determination of the composition

Jan 1, 1928

By D. Z. Hobbs

Because an economic method for preparing pure boron has not been developed, a program was started by the Bureau of Mines to evaluate existing techniques or to develop new methods for preparing the pure element. This report describes investigations directed toward the development of techniques for the preparation of pure boron by fused-salt electrolysis. Only two of the several fused-salt baths tested were satisfactory for the preparation of boron. These baths contained (1) potassium fluoride, lithium fluoride, potassium fluoborate and boron trioxide; and (2) potassium fluoride, potassium chloride, and boron trioxide. Of these two mixtures, the latter was more satisfactory. Elemental boron of from 90- to 95-percent purity and, in isolated cases, as high as 98-percent purity, was prepared from these two types of fused-salt baths. There appeared to be no distinct differences either in the yields or the purity of boron prepared at current densities ranging from 795 to 1,000 amperes per square foot. Current efficiencies were as high as 85 percent.

Jan 1, 1961

By Arthur Knapp

THE economics of fuel oil must be considered in two aspects; viz., fuel oil as one of a number of competitive fuels and fuel oil as a refined product of petroleum. "Fuel Oil" is usually defined as that product of petroleum which is used in furnaces for the generation of heat by simple combustion. It is true that any product of petroleum used in an internal combustion engine is essentially a fuel oil, but such oils are not included in the class known as "Fuel Oil." FUEL OIL AS ONE OF SEVERAL FUELS For a number of years, the petroleum industry has believed that the petroleum reserves were very limited and that petroleum products would begin to become scarce within a few years. The industry has believed FIG. 1.-DAILY AVERAGE CONSUMPTION OF FUELS BY PUBLIC UTILITY POWER PLANTS. that there would be a gradual but continual rise in prices as a result of this impending scarcity.

Jan 1, 1928