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By H. Herbert Hughes

THE trend in modern building construction is definitely toward the use of weight-reducing materials. The basic advantage of lighter structural weight is obvious; reduction of dead load with retention of equivalent strength affords the possibility of increasing the live load, or if this is not desirable or necessary it makes feasible a reduction in size of structural steel members and corresponding savings in other phases of construction. Among the weight-reducing materials and practices rapidly gaining favor are the use of light-weight patented insulating board to replace back-up tile or units, particularly in home construction; introduction of aluminum alloys to replace steel for many purposes; manufacture of porous brick, the use of which materially reduces the weight of masonry walls and partitions; and the use of self-rising vesicular concrete, diatomite and sawdust tile, porous gypsum, or gypsum tile for nonload-bearing partitions and walls. Even building accessories are being designed to save weight and space; one of the most striking examples of this is improved radiator construction. Concrete technique is keeping pace with the rest of the industry. Burned shale aggregates now available in many sections of the country will make concrete weighing only 100 lb. per cubic foot, saving roughly 35 per cent. in weight and sacrificing none of the strength of a rock-sand mix. It may be more expensive, but actual experience has shown that the saving in dead load will effect a reduction in structural steel which in many instances will more than offset the increased cost of the aggregate. The vesicular nature of most light-weight aggregates gives the concrete especially good insulating, fireproofing and soundproofing properties; yet absorption is comparatively low. Strangely enough, however, the increased use of light-weight aggregates appears to have augmented the demand for ordinary aggregates in concrete construction rather than to have decreased it. Light-weight aggregates have widened the field for concrete structures and, since the producers do not attempt to recommend the use of their material except where weight or other special properties are important factors, impetus- has been given to sales of other aggregates.

Jan 1, 1931

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 1, 1979

By Warren Blauvelt

IN VIEW of the enormous wastes of natural resources, of labor and of capital, due primarily to the economic environment, established by legislation, the general neglect of this phase of the problem of the elimination of waste is difficult to understand. In such a study, the engineering method of attacking a problem should be employed. The engineer does not try to solve his problem by disregarding natural laws, but by utilizing them. The successful engineer establishes an environ-ment in which forces, acting in harmony with natural laws upon an object or objects, will produce the desired results. The engineer who notices that the water level in a vessel, into which a gallon of water per minute is flowing, is two feet higher than the level in an adjacent vessel, connected therewith by a 6-in. pipe, does not assume that the law of gravity has ceased to work, or that water no longer seeks its level; he examines the connecting pipe for obstacles which prevent the free flow of water. Some editors, many reformers and most politicians tell us that the law of supply and demand no longer works; hence governmental control of commerce is necessary. Governmental control may temporarily-that is, until trial proves its futility- "insure domestic tranquility" and "promote the general welfare;" but it cannot "secure the blessings of liberty" which it cur-tails, nor can it "establish justice" which it violates.

Jan 9, 1922

By A. T. Yu

As the first year of full-scale shiploading operations nears completion, Chile's twin ports of Chafiaral and Caldera have proved instrumental in promoting the growth of that nation's iron ore industry. Located on the Iron Coast several hundred miles below Antofagasta, the two ports boast of new conveyor shiploading facilities uniquely adapted to their coastal environment. Until recently, iron ore producers in this region of Chile have been hampered by antiquated methods of loading crushed ore on ships for transportation to foreign buyers. Use of the "truck-to-lighter- to-ship" method, which dominated heretofore, was too slow and costly to permit expansion of productive mines and exploitation of new high-grade discoveries to meet the growing world demand for such ore.

Jan 8, 1960

By G. M. Schwartz, G. A. Thiel

Dimension stone was first quarried in Minnesota in 1820 and a very active industry has grown up over the years. The main basis of the present industry is a wide variety of igneous rocks sold under the general trade name of "granite." Also of considerable importance is the Ordovician dolomite sold under the locality names, Man kato, Kasota and Winona. THE first record of the quarrying of dimension stone in Minnesota dates back to 1820 when limestone was quarried locally for part of old Fort Snel-ling. Limestone quarries were operated at Stillwater, Mankato, and Winona as early as 1854. Granite was quarried first at St. Cloud in 1868, and within a few years thousands of tons were shipped to widespread points. Rough dimension stone for large buildings furnished the first important market, but beginning in 1886 paving blocks were in demand. The largest shipment was in 1888, when 1925 cars were shipped from the St. Cloud area. Quartzite was quarried first at New Ulm in 1859 and somewhat later at Pipe-stone and elsewhere in southwestern Minnesota. The productive dolomite quarries at Kasota were opened first in 1868 and have continued as large producers of a variety of stone to the present time. At present, the industry is controlled by relatively few operators, and for that reason detailed figures on dimension stone are not released for publication. A general idea may be obtained from the data in the Minerals Yearbook for 1948. The figures for total stone produced in Minnesota are 1,804,000 tons valued at $5,090,652. Probably the largest item in the latter figure is received from dimension stone. A better idea of the situation in relation to the country as a whole may be gained by using the data for 1930 when more companies were operating in Minnesota, and complete figures were published. In that year Minnesota produced granite valued at $2,668,119 and ranked third among the states in value. Minnesota's production of granite was almost exclusively for dimension stone. In the same year Minnesota produced 300,000 tons of limestone (dolomite) valued at $840,860, and this likewise was mainly dimension stone. In finished limestone Minnesota ranked second among the states in 1930. Sandstone and minor amounts of quartzite are the only other dimension stones that have been produced in Minnesota, but the quarries are now inactive. The commercial stones of Minnesota have been described in two reports by Bowlesl and by Thiel and Dutton. The early history of quarrying in Minnesota and extensive notes on the various rocks are given by N. H. Winchell.8 Small limestone and dolomite quarries were numerous throughout the area of Paleozoic rocks in southeastern Minnesota. Early production was largely dimension stone. With the increased use of Portland cement, most of these ceased production, and today only those at Kasota and Winona remain in operation. In recent years many quarries have reopened and new ones started, but these are devoted to the production of crushed rock and agricultural lime. As the application of modern quarrying and finishing methods increased, small companies in the granite business have dropped out, and the remaining companies have modernized their plants, purchased old quarries, and opened up new ones, thus furnishing a wide variety of granites suitable for most of the customary uses. It is the purpose of this review to present notes on the geology and operations of each of the quarries now operating within the state. Granites and Related Igneous Rocks The term granite as used in this report includes granites, gneisses, diorites, gabbros, and other igneous rocks. The granites of greatest economic importance are found in three widely separated regions, see Fig. 1. 1—Central Minnesota in the region of the city of St. Cloud, 2—the upper Minnesota River valley region, 3—the northeastern portion of the state, commonly referred to as the Arrowhead region. The St. Cloud Region: The rocks of the St. Cloud region are mainly granites and related rock types such as monzonites and quartz diorites. The stones may be grouped into three major types, namely, pink granite, red granite and gray granite. Most of the pink granite occurs in the area to the southwest of St. Cloud. The rock is best described as stone with large pink crystals set in a finer grained black and white background. The minerals of the matrix occur in remarkably uniform sizes, and the pink crystals are sufficiently uniform in their dis-

Jan 1, 1953

By G. M. Schwartz, G. A. Thiel

Dimension stone was first quarried in Minnesota in 1820 and a very active industry has grown up over the years. The main basis of the present industry is a wide variety of igneous rocks sold under the general trade name of "granite." Also of considerable importance is the Ordovician dolomite sold under the locality names, Man kato, Kasota and Winona. THE first record of the quarrying of dimension stone in Minnesota dates back to 1820 when limestone was quarried locally for part of old Fort Snel-ling. Limestone quarries were operated at Stillwater, Mankato, and Winona as early as 1854. Granite was quarried first at St. Cloud in 1868, and within a few years thousands of tons were shipped to widespread points. Rough dimension stone for large buildings furnished the first important market, but beginning in 1886 paving blocks were in demand. The largest shipment was in 1888, when 1925 cars were shipped from the St. Cloud area. Quartzite was quarried first at New Ulm in 1859 and somewhat later at Pipe-stone and elsewhere in southwestern Minnesota. The productive dolomite quarries at Kasota were opened first in 1868 and have continued as large producers of a variety of stone to the present time. At present, the industry is controlled by relatively few operators, and for that reason detailed figures on dimension stone are not released for publication. A general idea may be obtained from the data in the Minerals Yearbook for 1948. The figures for total stone produced in Minnesota are 1,804,000 tons valued at $5,090,652. Probably the largest item in the latter figure is received from dimension stone. A better idea of the situation in relation to the country as a whole may be gained by using the data for 1930 when more companies were operating in Minnesota, and complete figures were published. In that year Minnesota produced granite valued at $2,668,119 and ranked third among the states in value. Minnesota's production of granite was almost exclusively for dimension stone. In the same year Minnesota produced 300,000 tons of limestone (dolomite) valued at $840,860, and this likewise was mainly dimension stone. In finished limestone Minnesota ranked second among the states in 1930. Sandstone and minor amounts of quartzite are the only other dimension stones that have been produced in Minnesota, but the quarries are now inactive. The commercial stones of Minnesota have been described in two reports by Bowlesl and by Thiel and Dutton. The early history of quarrying in Minnesota and extensive notes on the various rocks are given by N. H. Winchell.8 Small limestone and dolomite quarries were numerous throughout the area of Paleozoic rocks in southeastern Minnesota. Early production was largely dimension stone. With the increased use of Portland cement, most of these ceased production, and today only those at Kasota and Winona remain in operation. In recent years many quarries have reopened and new ones started, but these are devoted to the production of crushed rock and agricultural lime. As the application of modern quarrying and finishing methods increased, small companies in the granite business have dropped out, and the remaining companies have modernized their plants, purchased old quarries, and opened up new ones, thus furnishing a wide variety of granites suitable for most of the customary uses. It is the purpose of this review to present notes on the geology and operations of each of the quarries now operating within the state. Granites and Related Igneous Rocks The term granite as used in this report includes granites, gneisses, diorites, gabbros, and other igneous rocks. The granites of greatest economic importance are found in three widely separated regions, see Fig. 1. 1—Central Minnesota in the region of the city of St. Cloud, 2—the upper Minnesota River valley region, 3—the northeastern portion of the state, commonly referred to as the Arrowhead region. The St. Cloud Region: The rocks of the St. Cloud region are mainly granites and related rock types such as monzonites and quartz diorites. The stones may be grouped into three major types, namely, pink granite, red granite and gray granite. Most of the pink granite occurs in the area to the southwest of St. Cloud. The rock is best described as stone with large pink crystals set in a finer grained black and white background. The minerals of the matrix occur in remarkably uniform sizes, and the pink crystals are sufficiently uniform in their dis-

Jan 1, 1953

By Richard Amberg

While the old-time melter was satisfied to bring his metal out in the desired condition, and therefore took care to have the slag liquid enough, the importance of a thorough knowledge of the slag is at present recognized in all up-to-date melting-shops. Formerly slag or cinder was considered a necessary evil, accumulating in some mysterious way wherever a man was striving to produce a clean metal. Nowadays we deliberately aim at a well-defined slag, which varies with the nature of the process and the product. In steel-making we need slag for two main purposes, namely, refining and protecting the metal. To refine metal, essentially oxidizing and reducing processes are required, while to protect the metal we need a reducing or, still better, a neutral atmosphere. Although an absolutely neutral condition between steel, on one side, and the containing vessel and the slag, on the other, is an imaginary conception, the various furnaces in use for the production of liquid steel maybe arranged with respect to the attainment of this ideal in about the following order of merit: converter, open-hearth, crucible, and electric furnace. In dealing with the subject we will find it convenient to avail ourselves of the terms of physical chemistry, which yield a simple conception of the matter and an expedient way of expression. Slag and metal at large are not mixable with each other, and we will therefore call them the two " immiscible phases," though there are certain compounds which dissolve in both phases under conditions to be considered later. Reactions be-

Jan 1, 1913

By Edward Halse

The tin-deposits of Durango, Mexico, have been ably described by Mr. W. R. Ingalls in a paper published in our Transactions in 1895.* While the occurrellces of tin-ore in other parts of the Republic are similar in many resperts to those in Durango, there are noteworthy local differences which, it is hoped, ma? lend interest to the present paper. The deposits examined by me in May, 1895, are found in the Serrania de Chacuaco, Municipality of Sain Alto, District of Sombrerete. The workings are situated in a range of mountains having a general northwest to southeast trend between Sombrerete and Fresnillo; the most northerly claim (La Desparranlada) being about six leagues southeast of the former town. El Refugio lies about four leagues to the southwest, and El Calabrote eight leagues to the west, of Fresnillo. The claims are from about 8425 to 8775 feet above sea-level, and from 1500 to 1800 feet above Sain Alto, the position of which town is marked in the map printed in Mr. Ingalls's paper. In order to reach the claims, one uses the carriage-road from Sain Alto to the small tin-colony of Las Cuevas; from the latter place to the mines there is only a rough mule-track. The mountain range consists of a rugged, weathered, gray granite rock, remarkable for large grains of quartz, and is flanked by masses of rhyolite and rhyolite-tuff of upper Tertiary age. The whole formation is broken up by narrow and steep willding arroyos and deep barrancas, mainly the result of denudation, and it appears to be a southeasterlj extension of the tin-bearing belt of rocks north of Durango City. Here and

Jan 1, 1900

Man: A purely detached consideration of nature and the place of man in it may easily result in somewhat pessimistic conclusions as to man and his destiny. However, when we come to the evaluation of man's role in the development of natural resources and his achievements in this field, a more optimistic tone may be justified. Hence the possible contradictions between Man and Nature, Perfection, and the present chapter are more apparent than real. After all, progress must have a foundation of optimism, and we cannot challenge either the faculty or the students to better work and to a progressive and constructive outlook without an underlying tone of optimism and basic faith in the future. Geology is the basic science of Mother Earth; the science of the natural forces that have produced and modified the structure of our globe; the science of minerals and rocks; of landscapes and soils; of water supply and mineral resources, including mineral fuels; and of the history of life, both plant and animal, as revealed by fossils in rocks. It is difficult to reduce man and his historical significance to their proper relationship with regard to the earth and its history. Processes of rock formation have continued for at least two billion years; man's activities have been in evidence only a few thousand years. As a means of comparison, if the height of the Empire State building were to represent geologic time, the thickness of a nickel placed on the tower would just about repre-

Jan 1, 1950

By J. B. Dilworth

The purpose of this paper is, first, to give a general account of a little-known coal-district of SE. Kentucky, its topography, drainage, and mineral resourcee, for those who may be interested in its economic development; and secondly, so to describe the geologic features of the field as to furnish available data to those engaged on the broader problems of Appalachian coal-geology. The data from which the major portion of the paper has been prepared were obtained, in professional investigations for private individuals and corporations, within the last decade. The area under review, defined by a heavy line on the map, Fig. 1, lies between Little Black and Pine mountains, and extends from Harlan on the west to a N-S. line crossing Looney creek 3 miles from its mouth on the east. This area can be divided for description into a Western and an Eastern Division. The character of investigatioil pursued in the Western Division, below Fugitt creek, was very different from that employed in the Eastern. In the former, only a rapid reconnois-sance was attempted: such coal-openings as had been made by prospectors or by citizens in obtaining fuel were visited, their

Jan 1, 1913

By J. S. Jacobi

Treating copper ores by heap-leaching and similar hydrometallurgical means is a time-honored practice, which was well known even in the 19th century. Later the method lost ground to better ore dressing processes, particularly selective. flotation. More recently there has been a distinct reversion to leaching techniques, particularly for scavenging operations in old mining stopes, in connection with LPF systems, irrigation of tailings dumps and similar situations. These hydrometallurgical techniques will gain further ground because processing is simple and permits better extraction of copper, particularly from low-grade or partly oxidized ores. In the lixiviation of primary ores at some major operations, copper-bearing liquors may undergo re-circulation in heap-leaching arrangements or the ores may be subjected to systematic percolation treatment. The liquors resulting from this source usually are quite strong (above 10 gpl copper) and copper would normally be reclaimed by electrowinning or cementation. These processes fall out- side the scope of this paper which is concerned with recovery of copper from weak 1iquor.s containing from 0.1 to about 3 gpl copper.

Jan 9, 1963

By Frederic Lahee

THE purpose of this paper is to demonstrate the similarity of the oil-producing structures in the Mexia1 fault zone, and to show how the apparently very irregular well logs in these fields may be used for the practical interpretation of subsurface conditions. The Mexia oil field, in Limestone County, Tex. (Fig. 1) is closely associated with a fault that trends about 30° east of north and has a displacement of between 200 and 400 ft., with downthrow on the west. Minor slips accompany this major fault, some being roughly parallel to the main break while others are transverse to it. These faults belong to the so-called Mexia fault zone, a belt of fracturing that has been traced in its characteristic features southward to near Kosse, 15 miles south of Groesbeck, in southern Limestone County, and northward at least as far as the Trinity river at the eastern border of Navarro County, and possibly as far north as Hunt and Hopkins counties.2 The Balcones fault zone, from 30 to 40 miles west of the Mexia fault zone, differs from the latter in that its principal displacement is a down-throw on the east. In this respect, it is exactly the opposite of the Mexia displacement. Between these two zones of major faulting lies a great down-dropped block, or graben, which is broken by numerous minor faults.

Jan 2, 1925

By E. Morgan Massey

Located in virgin coal acreage near Gilbert, W. Va., Massey Coal Mining Co.'s Ben Creek No. 2 mine afforded the company's engineers the opportunity of designing and laying out the entire mining operation from the mine faces to the railroading loading site. However, the topography of this region posed difficult problems in haulage of coal for, in this extremely rugged terrain the uppermost coal seams lay in the mountain-top ridges, approximately 1400 ft above the valley floor. The decision for mining equipment naturally leaned to the new high-capacity continuous miners where seam conditions permitted: otherwise, to the new super-high capacity conventional cutting and loading machines. Since the coal seams lay in ridges and points of considerable outcropping, the decision was to keep the transportation on the surface and mine the coal with multiple entries into the outcrop. This way, the major problems of underground haulage, drainage, and ventilation are eliminated, and the opportunity to take advantage of a-c underground power becomes a much simpler proposition.

Jan 10, 1960

Discussion of the paper of, RICHARD H. RICE, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 89, May, 1914, pp. 721 to 743. S. G. VALENTINE, Oxford, N. J.-In a paper read at the New York meeting of the Institute last February I presented some notes taken from our experience with the turbo blower operating on a blast furnace. In connection with Mr. Rice's very interesting paper there are a few items that might be of further practical interest. The question of the reliability of this type of blower will naturally be presented. In this connection we would say that our turbo blower has been in practically continuous use during the present blast, which was begun June 7, 1912, with only three interruptions for repairs of any consequence. Soon after blowing in there was developed a tendency of the blower to surge or pulsate. This occurred on operating at a point considerably below the normal capacity of the machine, and was checked with comparatively little trouble by throttling the intake slightly and taking up a small lost motion on the governor connections, a legacy of the previous blast that had not been attended to. All this required only a few hours' time. In. March, 1914, the furnace being banked on account of a blizzard that cut off our freight deliveries for five days, the opportunity was used to replace the carbon packing on the steam-turbine shaft and to repack the steam inlet valves. In June, 1914, the blower was off 8 hr. to replace an oil ring and scrape a bearing. With these exceptions we have made continuous use of the machine and find we can depend upon it with entire safety as a piece of machinery.

Jan 4, 1915

By Frederick C. Langenberg

A method is presented for computing the solubility of nitrogen in molten alloy steels. Examples are given to illustrate the procedure, and comparisons are made between predicted and measured nitrogen solubilities. THERE is an increasing use of nitrogen as a major alloying element in steels, or as a partial substitute for other alloying elements. Nitrogen is a potent austenite stabilizer, and Cr-Mn-low Ni-N steels, or even Cr-Mn-N steels, are being considered

Jan 1, 1957

By B. H. Bergstrom, Will Mitchell, T. G. Kirkland, C. L. Sollenberger

SEVERAL constructive and fundamental studies have been made in the analysis of data obtained from experiments carried on with batch ball and rod mills. The operating characteristics of ball milling in small continuous circuits have also been appraised. It is from these analyses that some of the theories of comminution have been developed. Relatively few studies of continuous rod milling have added significantly to the fundamental concepts, because seldom have they yielded sufficiently consistent results. Perhaps they have been too limited in their scope. Careful control of the variables in batch grinding is simple compared with that encountered in a continuous operation. This factor alone has discouraged many investigators. Occasionally results of systematic changes made in industrial rod mill circuits have been published, but usually the data are sketchy and are restricted because -of the unwieldiness of the equipment used. The work, in general, has not been comprehensive; nevertheless it has provided empirical relationships that have bridged the gap between postulate and practice so that by proper manipulation of formulae, a mill designer can anticipate mill size and power requirements.1-3 Although operating variables of a small continuous mill are not so easy to control as with the batch mill, with present day devices, and with careful experimental work, consistent results can be obtained.

Jan 10, 1954

By T. D. Yensen

AGING is a term that connotes a slow change in properties under ordinary operating conditions. It can be accelerated by increasing the temperature and by mechanical straining. The magnetic properties of iron and some of its alloys have for many years been known to be subject to such a change. But the cause of the change was not recognized until a few years ago after mechanical age-hardening in non-ferrous alloys of the "duralumin" type had been definitely shown, by means of solid solubility curves, changes in electrical resistance and microanalysis, to be caused by slow precipitation of one or more con-stituents from the solid solution. The similarity between the solid solubility curves of such alloys (Fig. 1) and those for iron-nitrogen (Fig. 2) and iron-carbon alloys (Fig. 3) below the Al transformation point suggested at once that magnetic aging of iron might be caused by a similar process; namely, by the slow precipitation of carbon and nitrogen in the form of Fe4N and Fe3C at ordinary temperatures because of a cooling rate that had been too rapid to permit complete precipitation according to equilibrium conditions. This suggestion has since been amply confirmed, particularly by the comprehensive work of Köster1 on the effect of nitrogen and carbon. Typical curves are shown in Fig. 4 for the relationship between aging temperature and coercive force. Previous to the establishment of the precipitation-hardening theory it was thought that the effect of nonmetallic elements like C, N, 0, etc., on the magnetic properties of iron was greatest when these elements were retained in solid solution, atomically dispersed throughout the interstitial spaces of the iron lattice2.

Jan 1, 1935

By J. A. Herbst, D. W. Fuerstenau

The effect of mill speed and ball load on the dry ball milling of dolomite is examined in the context of the batch grinding model. Observed changes in the parameters of the model are interpreted, as far as possible, in terms of the mechanics of particle motion in the mill. A parameter estimation scheme previously proposed by the authors is shown to provide the basis for a successful simulation of grinding behavior over a wide range of mill speeds and ball loads. Finally, a combination of experimental and simulated results is used to determine the optimum mill speedball load for closed circuit grinding in this mill-material system.

Jan 1, 1973

By C. W. Waidner

THE standard scale of temperature that it is attempted to realize in practice is the centigrade thermodynamic scale, as defined by Kelvin about the middle of the last century. This scale would be exactly realized with a perfect1 gas in an ideal gas thermometer, and is closely realized with the more permanent gases. From the departure of certain properties of these gases from those of a perfect gas, it is possible to deduce the amount of the departure of the temperature scales, defined by their use, from the thermodynamic scale. In nearly all the precise experimental work done during the latter part of the last century, it was necessary for the experimenter to establish his own gas-thermometer scale, and the labor involved in this was often greater than that involved in the prime object of the experimental work undertaken. The experimental difficulties involved in gas thermometry led to the establishment of temperature scales differing from one another by amounts considerably greater than could be accounted for by the differences in the properties of the gases used. Results were, therefore, expressed in terms of somewhat different temperature scales, snaking correlation of such results difficult and uncertain.

Jan 9, 1919

Jan 9, 1951