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By Allen J. Johnson

Anthracite coals have been divided into three groups: (I) meta-anthracite, a high-carbon coal that is usually very slow to kindle and difficult to burn, at least on conventional equipment; (2) anthracite, a high-carbon low-volatile coal of widely accepted value as both a domestic and industrial fuel; and (3) semianthracite, a coal lying between anthracite and bituminous coal in carbon and volatile content, and also, generally speaking, in burning characteristics. Anthracite Groupings The technical differentiation between these groups, as defined by the A.S.A.-A.S.T.M. Sectional Committee on the Classification of Coals, is as shown in Table I. Tables 2 and 3 show typical analyses of anthracites and semianthracites and Figs. I to 3 show graphically the range of analytical samples. Table 4 shows the commercial sizes of coals. Meta-anthracite and Graphitic Anthracite Typical analyses from virtually every field in the United States indicate that there are few if any extensive deposits of meta-anthracite. Some of the anthracites of Rhode Island contain almost negligible quantities of volatile and would thus fall into the meta-anthracite grouping on a basis of analyses alone. However, their other characteristics indicate that it is doubtful whether they should be considered as fuels at all, but rather as graphite. In fact, this material is being mined for use as foundry facings and furnace linings.4 A typical analysis of Fenners Lodge graphite,4 from Rhode Island, is: graphitic carbon, 55.9 per cent; silica (ash), 40.6; sulphur, 1.6; moisture, 1.9; volatile, o. Other Rhode Island coals possess percentages of volatile that would throw them into the normal anthracite rather than the meta-anthracite class. However, this "volatile" is nearly all noncombustible,3,4 being composed almost entirely of carbon dioxide and inert gases, therefore its definition as volatile is open to discussion, leaving the exact classification of the fuel a moot question. One factor is certain, Rhode Island coal is so different from nor-mal anthracite in both analysis and burning characteristics that it should have a

Jan 1, 1944

By Allen J. Johnson

Anthracite coals have been divided into three groups: (I) meta-anthracite, a high-carbon coal that is usually very slow to kindle and difficult to burn, at least on conventional equipment; (2) anthracite, a high-carbon low-volatile coal of widely accepted value as both a domestic and industrial fuel; and (3) semianthracite, a coal lying between anthracite and bituminous coal in carbon and volatile content, and also, generally speaking, in burning characteristics. Anthracite Groupings The technical differentiation between these groups, as defined by the A.S.A.-A.S.T.M. Sectional Committee on the Classification of Coals, is as shown in Table I. Tables 2 and 3 show typical analyses of anthracites and semianthracites and Figs. I to 3 show graphically the range of analytical samples. Table 4 shows the commercial sizes of coals. Meta-anthracite and Graphitic Anthracite Typical analyses from virtually every field in the United States indicate that there are few if any extensive deposits of meta-anthracite. Some of the anthracites of Rhode Island contain almost negligible quantities of volatile and would thus fall into the meta-anthracite grouping on a basis of analyses alone. However, their other characteristics indicate that it is doubtful whether they should be considered as fuels at all, but rather as graphite. In fact, this material is being mined for use as foundry facings and furnace linings.4 A typical analysis of Fenners Lodge graphite,4 from Rhode Island, is: graphitic carbon, 55.9 per cent; silica (ash), 40.6; sulphur, 1.6; moisture, 1.9; volatile, o. Other Rhode Island coals possess percentages of volatile that would throw them into the normal anthracite rather than the meta-anthracite class. However, this "volatile" is nearly all noncombustible,3,4 being composed almost entirely of carbon dioxide and inert gases, therefore its definition as volatile is open to discussion, leaving the exact classification of the fuel a moot question. One factor is certain, Rhode Island coal is so different from nor-mal anthracite in both analysis and burning characteristics that it should have a

Jan 1, 1944

By R. R. Estill

THE rank of the Ruhr coal ranges from a high volatile bituminous coal to an anthracite, depending to some extent on the original depth of the seam. The average Ruhr coal corresponds to a soft bituminous American coal of a coking quality. The average thicknesses of individual coal seams being mined are also comparable (59 in. against 65 in. in the United States). However, consideration of seam conditions and mining conditions other than those just mentioned emphasizes differences rather than similarities with United States soft coal. In general, the Ruhr seams now being mined are much more folded and inclined than American seams. Dips of 20' and 30" are common in seams now being worked, and 30 pct of the coal reserves in the district are in seams dipping more than 35". Only on the tops and bottoms of folds do we find rather flat coal seams. In addition to the folding there is extensive displacement by cross faulting plus a certain amount of strike faulting of an overthrust nature, which results locally in doubling or omission of seams. Because of the long history of mining in the Ruhr, nearly all coal lying near the surface has long since been mined out, and we find that the average depth of mining is at present about 2300 ft below the surface. Deep mining, folding, and faulting result in seam conditions requiring a great deal more roof support than one finds in American soft coal mines. In fact only in the anthracite district and the Rocky Mountain and Pacific coal fields do we find somewhat similar conditions. It is easy to say, therefore, that the problem of mechanization of coal cutting and loading in the German mines is quite different from that which we have so effectively met in America with our mobile cutters and loaders, duck bill loaders, and a room and pillar system of mining our drift and slope mines. Partly because of more limited coal reserves, the traditional German mining system is largely the longwall method, which gives an almost complete coal recovery. Backfilling must be extensively practiced to protect the longwall faces, the over and underlying seams and workings, and especially the surface industrialized areas and barge canals. The German engineers have accordingly concentrated their efforts on the design of cutters, loaders, and conveyors suitable to longwall methods rather than room and pillar methods. Undercutters with cutter bars like American models have been in use in the Ruhr since well before World War 11. In 1941 they accounted for 8.5 pct of the production. This percentage, of course, includes coal which was undercut but nevertheless had to be broken down with air hammers or with explosives. The most common of these cutters is the Eickhoff Standard cutter (see fig. 1). This machine does about 95 pct of the undercutting in the Ruhr today, and is available with either compressed air or electrical power and in at least four different sizes. A variation of the cutter is this one with two cutter bars (fig. 2). At the end of 1947 about 200 of these machines and similar cutters were accounting for 13.2 pct of the total production, a production which was, however, only 60 pct of the 1941 production rate, so that the actual cutter tonnage was only up to a small amount over 1941. In 1941 about 3 pct of the production was accounted for by shearing machines making their cut perpendicular to the longwall face. They were similar to those used in the States. These machines are today considered obsolete and now account for only 0.7 pct of the total production. They are located at only a few mines and at present do not seem to have much of a future in the Ruhr. For the future, the Ruhr miner is looking forward to rather extensive mechanization of face work, with two major types of equipment being developed almost simultaneously. On one hand there is the development of cutter loaders for use in relatively hard coal. They represent the further extension of ideas developed after relatively long experience with the Eickhoff cutter. On the other hand there has been since 1942 an intense interest in the Ruhr in the development of face-stripping methods, particularly by the Kohlenhobel (coal plow) and its modification. At the end of 1947 these cutter loaders, Kohlen-hobels and scrapers together were actually accounting for only about 1.4 pct of total production while air hammers still broke 77.1 pct and as much as 1.2 pct was actually broken by hand picks. However,

Jan 1, 1951

By R. R. Estill

THE rank of the Ruhr coal ranges from a high volatile bituminous coal to an anthracite, depending to some extent on the original depth of the seam. The average Ruhr coal corresponds to a soft bituminous American coal of a coking quality. The average thicknesses of individual coal seams being mined are also comparable (59 in. against 65 in. in the United States). However, consideration of seam conditions and mining conditions other than those just mentioned emphasizes differences rather than similarities with United States soft coal. In general, the Ruhr seams now being mined are much more folded and inclined than American seams. Dips of 20' and 30" are common in seams now being worked, and 30 pct of the coal reserves in the district are in seams dipping more than 35". Only on the tops and bottoms of folds do we find rather flat coal seams. In addition to the folding there is extensive displacement by cross faulting plus a certain amount of strike faulting of an overthrust nature, which results locally in doubling or omission of seams. Because of the long history of mining in the Ruhr, nearly all coal lying near the surface has long since been mined out, and we find that the average depth of mining is at present about 2300 ft below the surface. Deep mining, folding, and faulting result in seam conditions requiring a great deal more roof support than one finds in American soft coal mines. In fact only in the anthracite district and the Rocky Mountain and Pacific coal fields do we find somewhat similar conditions. It is easy to say, therefore, that the problem of mechanization of coal cutting and loading in the German mines is quite different from that which we have so effectively met in America with our mobile cutters and loaders, duck bill loaders, and a room and pillar system of mining our drift and slope mines. Partly because of more limited coal reserves, the traditional German mining system is largely the longwall method, which gives an almost complete coal recovery. Backfilling must be extensively practiced to protect the longwall faces, the over and underlying seams and workings, and especially the surface industrialized areas and barge canals. The German engineers have accordingly concentrated their efforts on the design of cutters, loaders, and conveyors suitable to longwall methods rather than room and pillar methods. Undercutters with cutter bars like American models have been in use in the Ruhr since well before World War 11. In 1941 they accounted for 8.5 pct of the production. This percentage, of course, includes coal which was undercut but nevertheless had to be broken down with air hammers or with explosives. The most common of these cutters is the Eickhoff Standard cutter (see fig. 1). This machine does about 95 pct of the undercutting in the Ruhr today, and is available with either compressed air or electrical power and in at least four different sizes. A variation of the cutter is this one with two cutter bars (fig. 2). At the end of 1947 about 200 of these machines and similar cutters were accounting for 13.2 pct of the total production, a production which was, however, only 60 pct of the 1941 production rate, so that the actual cutter tonnage was only up to a small amount over 1941. In 1941 about 3 pct of the production was accounted for by shearing machines making their cut perpendicular to the longwall face. They were similar to those used in the States. These machines are today considered obsolete and now account for only 0.7 pct of the total production. They are located at only a few mines and at present do not seem to have much of a future in the Ruhr. For the future, the Ruhr miner is looking forward to rather extensive mechanization of face work, with two major types of equipment being developed almost simultaneously. On one hand there is the development of cutter loaders for use in relatively hard coal. They represent the further extension of ideas developed after relatively long experience with the Eickhoff cutter. On the other hand there has been since 1942 an intense interest in the Ruhr in the development of face-stripping methods, particularly by the Kohlenhobel (coal plow) and its modification. At the end of 1947 these cutter loaders, Kohlen-hobels and scrapers together were actually accounting for only about 1.4 pct of total production while air hammers still broke 77.1 pct and as much as 1.2 pct was actually broken by hand picks. However,

Jan 1, 1951

By Walter Harvey Weed

In a previous paper upon the enrichment of mineral veins by later metallic sulphides,? the writer has shown that certain masses of rich ores, such as are found in many mines, either near the water-line or as bonanzas in depth, are of secondary origin, and are due to a leaching of lean ore and the concentration of the material by reaction between the solution and the unaltered ore below. The geological and mineralogical evidence is believed to form an adequate basis for a chemical and physical explanation of the phenomenon. In the present paper the writer will give a brief synopsis of this theory, and will apply it more particularly to deposits of the precious metals, laying special emphasis upon the dependence of such enrichments upon the presence of iron sulphide (as pyrite, etc.) in the primary ore, and upon structural features which control the circulation of the enriching solutions below the water-level. It is believed that many, though not all, of the bonanzas arid pay-shoots of rich sulphide ores, especially those carrying gold and silver, which are encountered in ore-deposits, are of such secondary origin. Apparently it is essential that the occurrence and structural relations of such ore-masses should be understood, as the success of the mine is often dependent upon the finding and extraction of these ores. A legitimate deduction, too, is that such ore-deposits decrease in value With depth. As my own studies have been mainly in Montana, my illustrations must be drawn from the ore-deposits of this and adjacent States, with such as I have noted in hurried visits else-

Jan 1, 1901

By M. Amsterdam, F. Rothwarf, L. Muldawer

SILVER-cadmium near the composition AgCd shows three equilibrium phases. As with 13 brass, the high temperature phase is disordered body-centered cubic (8) and the low temperature phase has the ordered CsCl structure . However, there is an intermediate temperature phase which is hexagonal close-packed ((). In a recent paper, Speich and Mack' report on a study of the Ag-Cd eutectoid near the AgCd composition. Unfortunately, the phase diagram upon which they base some of their conclusions is incorrect. That diagram is taken from the Metals Handbook' and the error is that the 0 and ( phases have been interchanged. The Handbook gives the low temperature phase as hexagonal (designated 5) and the intermediate temperature phase as cubic ordered (designated . The error may be typographical or it may be one of confusion resulting from the use of 5, ,, and 0 for the intermediate phase in various papers. A careful search of the literature reveals that a number of authors have indicated the correct relative positions of the 13, 5, and 0 phases. The comprehensive work of Fraenkel and Wolf clearly stated that the high and the low temperature phases are either identical or are very similar. olander,' on the basis of electrochemical measurements, showed that the 13 phase is disordered and the 1 phase (designated 8" in his paper and in refs. 3 and 5) is ordered. Further work by Durrant5 using thermal and metallographic analyses provided a more precise phase diagram. A summary of these works was given by Hansen6 and shows the correct relative positions of the phases. Owen, Rogers, and Guthrie7 located correctly the upper two phases by X-ray diffraction. Their failure to find the low tem-

Jan 1, 1954

By C. L. Dake

Chemistry of Iron Solution IRON is much more soluble in the ferrous than in the ferric form. Where, as in the case of the ferrous silicates and the sulphides, the iron is already in the ferrous form, it may go at once into solution and be removed, upon the breaking down of the parent rock. If in the ferric form, it must first be reduced; usually by the decay of organic matter, the demand of the decaying carbonaceous matter for oxygen being so great that the latter is abstracted from the ferric compounds and the iron is thereby reduced and rendered' soluble. The iron may go into solution as the sulphate, or in the presence of excess CO2 as ferrous carbonate. It is probably soluble as salts of the organic acids.1 Recent work indicates that these are important in the formation of bog ores.2 There is considerable variety of opinion concerning the behavior of these organic compounds.3 The secretions about the roots of plants and trees also cause the solution and removal of iron and a consequent bleaching of the soil.4 While the matter is not yet well understood, we can probably say definitely that the so-called organic acids are a group of colloids which possess slightly acid properties, and the salts of which are partly soluble

Jan 7, 1915

By George Bain

SOME problems concomitant with commercial exploitation of marble are presented as examples of interesting, useful and profitable fields for application of scientific knowledge. The marble industry is only one such field and is selected because its varying new aspects are familiar to the author. However, what is true for marble is equally so in principle for many industrial minerals. The problems of any stone industry are to maintain markets, create new outlets for stone already in demand, and develop varied uses for varieties that are not so popular. Here the geologist has a different role from most of his colleagues in metal mining. The producing branch may ask about the expectable variation in thickness or size of a deposit as development proceeds. The stock department may call for the available amount of a given type of stone before accepting a large order. The sales force requires data on the use for stone from certain parts of deposits in order to divert grades to the most suitable use. The service depart-ment wants defects rectified and the cause determined to avoid recurrence. The mills want data on durability and cutting quality of abrasives. The geologist occupies no special department; he is on general call, as may be illustrated by a few types of problems that may be classified as: (1) dominantly geological in character, (2) dominantly chemical in character, (3) dominantly physical in character.

Jan 1, 1940

By J. J. Rutledge

THE first method of working coal mines in the middle western states, more particularly in Illinois, Indiana and Missouri, was by means of the so-called single-entry method. In this method a single main passageway, or entry, was driven in the coal seam. with no parallel passageways, and from this pas-sageway or entry there were turned at intervals sim-ilar cross-passageways or entries, and from these cross-passageways, if the coal seam worked lay fairly horizontal, rooms were turned right and left. These crude methods of working were followed when the com-panies opening the mines were small and of very limited capital, and when the demand for coal was small and irregular. The principal desire was to produce coal in the short-est possible time and at the cheapest price. The chief evil resulting from such method of working was de-fective ventilation, although there were other serious drawbacks. There were then few or no good mining laws and no restrictions on those operating the coal mines. The hours of labor were long, the wages low, and the miners accordingly worked hard. All the coal was either sheared or undercut with a pick by hand. Very little solid shooting and no machine mining was done. What little air entered the mine, openings was introduced through the entries or. headings and thence conducted through the rooms by means of curtains; in many cases, as the workings became more exten-sive, the number of curtains added so materially to the mine resistance that ventilation was extremely in-efficient. Shots were fired by the miners at any time during the working shift and consequently there was more or less powder smoke or fumes in the mine work-ings all day long. Moreover, the working days were much longer than at present. The fine, dry coal-dust falling from the miners' picks while they were shear-ing or undercutting the coal filled the mine atmosphere and was taken into the lungs of the mine employees.

Jan 2, 1927

By J. H. Curran

In this paper, a numerical model for determining the stress and displacement fields around a crack of arbitrary geometry in a linear elastic medium is described. Accuracy and computational speed were the main considerations in selecting the numerical method and Propagation criteria used to model the growing crack. Some results regarding the stresses and displacements around a two-dimensional crack of arbitrary geometry are discussed.

Jan 1, 1984

By Jon E. Fatzinger

The design of a centrifugal slurry pump is approached as a compromise between efficiency and wear life of the wetted parts. This compromise is effected by the choice of proper materials of construction and geometry. However even the most optimally designed pump will fail if due consideration is not given to its installation and operation. System head curves and hydraulic profiles are discussed as useful tools to be used in the operational analysis of a slurry system.

Jan 1, 1978

By Lloyd B. Underwood

Dr. Gardener, in Chapter 2, has presented a comprehensive state-of-the- art review of site investigations For tunneling. Nearly all of the techniques he discussed will also be required for future site investigations. Therefore, this chapter will be devoted to a few rather new exploration techniques plus ideas for improving some of the present-day methods. In March 1962, the first symposium on "Remote Sensing of Environment" was held at the University of Michigan.l Since that time, four additional symposiums have been held at the same University. Also, the technical Literature has recently included a number of articles on remote sensing techniques. A recent one appeared in the February 1968 issue of Materials Research and Standards.Vt was entitled "Developments in Remote Sensing Applicable to Airborne Engineering Surveys of Soils and Rocks," and was written by Dana C. Parker. Mr. Parker predicts that aerial reconnaissance will someday supplant soil augers, rock drills, surface reconnaissance, and geophysical surveys as the engineer's primary means of obtaining information about soils and rocks. He states, "The engineer wishing to survey a route or a site or to locate rock and soils suitable for construction projects will be able to push some buttons in an airplane and record all the data required for determining the relevant conditions. In a short time after he returns to earth with his rolls of film and charts, he will be able to reduce and analyze the data by partially computerized techniques and to compile a concise and comprehensive engineering report that gives all the relevant information about rocks, soil, water, and vegetation in the area he surveyed. Most important he will feel as confident with his recommendations, derived primarily from image characteristics and spectral power distributions, as his predecessors did with recommendations based on more tangible evidence obtained from drill cores and surface reconnaissance." The airborne sensors for engineering surveys of soils and rocks are those that sample some electromagnetic property of the materials that com- prise the terrain and cover its surface. In addition to cameras, these include

Jan 1, 1970

By Woolsey Johnson

THE object of this paper is to, describe the several necessary characteristics of the zinc-retorting charge and to show how by certain improved methods; the large excess of coal, over that theoretically required, can be reduced, thereby effecting an increase in the smelting capacity of a retort plant as well as other economies. In the Southwestern zinc works a charge of roasted zinc ore with a side mixture of carbonates and silicates, analyzing on the average 50 per cent. Zn, is mixed with 55 or more per cent. of its weight of a mixture of coal and coke analyzing 60 to 70 per cent. fixed carbon. . The ore is of varying fineness and the coal and coke are usually crushed in a semi-moist condition through a 3/8 -in. screen. With ores of a slaggy nature, this coal proportion is increased, sometimes to as much as 100 per cent. of, the weight of the ore. With carbonate ores, or where anthracite screenings with higher carbon content are cheap enough, the percentage of reducing agent is cut to 45 per cent. or even somewhat lower. The average charge per retort for a monthly run of a plant on ore, as distinguished from retorts on blue-powder, ladle-skimmings and other between-products, runs from 60 to 66 lb., with a mean of 63 lb. for the Southwest with standard retorts of 8 ½ -in. inside diameter and 50 in. long inside, using roasted sulphide ores. Conditions will change these figures, but 40 lb. of ore per cubic foot of retort space is, I believe, an average in the better-operated plants. Since the rise in. the price of spelter, the tendency has been to overcharge. To remove the slag that is formed when retorts are overcharged, extra men are put on to "gum-chisel" the retorts to prevent "set" furnaces and "butchered, retorts." Taking the above conditions as premises, we find that from four to six times the amount of coal necessary for the reduction is used, as is evidenced by the fact that the residues analyze as high as 35 per cent, fixed carbon. There are good reasons why this excess of fixed carbon must be used and perhaps these can be best explained by a description of the metallurgical requisites of a zinc charge. We may enumerate these as follows: 1. High reducing power, especially at the end f the shift, to reduce any carbon dioxide to monoxide and bring about a good condensation

Jan 2, 1918

By Edwin Ludlow

EDWIN LUDLOW, president of the American Institute of Mining and Metallurgical Engineers for the year beginning Feb. 15, 1921, is a well-known figure in the state that was the birthplace of the Institute-Pennsylvania-although he was born and educated in New York and is again one of its residents, after years of active work in the field. Mr. Ludlow was born at Oakdale, Long Island, and was graduated from the School of Mines at Columbia University with the class of 1879. After graduation, he became a civilian worker with the U. S. Engineer Corps under General William Ludlow, his brother, and for two years did river and harbor surveying along the New Jersey coast.

Jan 1, 1921

UNDER the same justification that I spoke to you in the preceding chapter on crystal and some other gems, I can now speak much better and with much greater reason of glass, since it is one of the effects and peculiar fruits of the art of fire. Every product that is found [41v] in the interior of the earth is either stone or metal or one of the semiminerals, and glass, as is seen, resembles them all, although in all respects it is dependent upon art. Therefore it seems to me that before coming to the discussion of the arts themselves, I must treat of this very beautiful composition created by art and number it with the semiminerals. Thus in this chapter I shall speak to you of glass, not as a proper semimineral, nor yet as a metal, but as a fusible material that is almost made mineral by art and by the power and virtue of fire, born from the speculation of good alchemistic savants, through whose efforts it imitates. the metals on one hand and the transparency and splendor of gems. on the other. Certainly it is a very beautiful thing and one that should not be left buried in silence, in consideration first of how great a thing art has been, able to discover, and then because its beauty makes it such a pleasing thing for making drinking. glasses and an infinite number of other ornamental things that satisfy the desires of man. I shall begin, then, by telling you, to the credit of the alchemists, how I believe that this thing was found through their desire to make gems; for when they could not bring them to perfection (as also happened with the metals) they made this beautiful and attractive product, glass. However, Pliny says that it was found by chance in Syria at the mouth of the Belus River by certain merchants who were driven there by the fortunes of the sea and forced to stop and disembark there for a time in order to eat. In cooking the food they saw the rocks of that place converted into a flowing, lustrous material. And as they thought about this, it seemed beautiful to them, and when they went away they carried some stones and plants with them. Thus they gave beginning to glass making. But now leaving this discussion it does not matter how it may have been discovered, whether by merchants or by ingenious alchemists. Art is that which has given it being, through many experiments and by addition

Jan 1, 1942

By Hu Weibei

This paper describes the development and implementation of the control system in the flotation plants of China. The control system can be categorized as: Control in the crushing circuits: Automatic control of the flow rate of the crusher. Control in the grinding circuits: Control of the feed rate of the grinding mill and circulating load. PSM-200, an indigenous particle size monitor, and gamma-ray density gauges are utilized. Control in the flotation circuits: pH control, flotation reagent dosage estimation and control, pulp level control, aeration control, etc. Complete grinding-flotation circuits control is based on minicomputer operations. Some typical control systems which have been applied in copper flotation plants are summarized and specific problems discussed.

Jan 1, 1984

By J. G. McCullough

The paper is a general description of the U.S. lead and zinc industries as they are now compared to ten years ago and the effect of recent world-wide developments. Topics of interest concerning lead are the present and potential growth of the lead-acid battery business, the potential hazards of having one outlet for a major proportion of production, the expanding U.S. secondary lead production, the hardships of stringent hygiene and environmental regulations and the future supply and demand outlook. The present poor condition of the U.S. zinc industry caused by an oversupply of zinc metal - mostly in Europe - is discussed and also the shifting markets influenced by the automotive programs to reduce the weight of cars and the continuing high mine production due to the mixture of metals contained in the massive sulphide deposits which contain a major portion of the zinc metal reserves. This is all tempered by technical advances in die casting and the emphasis on the protecting of steel with zinc to prolong its useful life. New U.S. mine and smelter production facilities will be restrained due to lower cost foreign zinc from better grade ore deposits and the insistence by Governments for refining capacity to be constructed in the country that the ore is mined.

Jan 1, 1977

By Eugene McAuliffe

TWO years ago the American Institute of Mining and Metallurgical Engineers made a memorable contribution toward a better understanding of the problems that have for many years confronted the coal industry. Specific suggestions toward betterment were then advanced, certain of which were taken up, amplified and endorsed by men who were conscien-tiously interested in the work of lifting this great industry out of the morass it has lain in for years. Two certain suggestions then made-provision for seasonal variations in railroad freight rates that would tend to encourage the purchase and movement of coal during the low summer production period, and provi-sion for the collection by the United States Government of all the facts surrounding the industry-were intro-duced in the form of legislation in the United States Senate by a member of that body, a man whose personal character, antecedents and business training put him above and beyond all suspicion of demagoguery; however, as the result of the insistent, vindictive opposition of the industry itself, these two bills, con-structive in their nature, were buried under an ava-lanche of misrepresentation. Today, with all mines that employ union labor at a stand still, the work of stabilizing the industry is yet before us. As aptly stated by Herbert Hoover, in March, 1920, when he was president of the Institute; An engineering organization is particularly the body to under-take this work. It is an economic problem, an engineering pro-blem within the ken of our experience; it is a problem that requires not only constructive thought but quantitative thought and wise social thought. The engineers of the United States occupy a position midway between capital and labor. They enter upon problems of this kind without prejudice either way, and they have that faculty of mind for quantitative thought, as distinguished from qualitative thought, that takes such problems as this out of the region of politics into the region of matter-of-fact solution.

Jan 5, 1922

By Thomas F. Bates

ANALYSIS of the chemical and structural differences in minerals often results in a better understanding of the differences in the geological conditions under which they were formed. The minerals in the kaolinite group differ in the amount of interlayer water and in the nature and amount of ordered and/or random shifting of each 1:1 layer with respect to those above and below it. This paper is a progress report resulting from research on the morphology, structure, and origin of fine-grained minerals, supported by Contract N6onr26914 with the Geophysics Branch of the Office of Naval Research. The purpose of the paper is to present data obtained in the laboratories at The Pennsylvania State College and elsewhere, which reveal some of the details of structure of the minerals in the kaolinite group, and to suggest a number of interpretations that bear upon the conditions of origin of these minerals. Be¬cause most of the work in this investigation thus far has been concerned with the relationships of kaolinite, halloysite (4H2O; endellite), and halloysite (2H2O), must of the discussion deals with these members of the group. The first step in the analysis of the differences in two sets of geological conditions is an evaluation of the differences in the minerals that result. Thus the chemical differences between the montmorillonite and the kaolinite clays corroborate other evidence in support of the view that the montmorillonites are commonly formed when solutions are alkaline and leaching poor, while kaolinite usually is associated with acid solutions and good drainage condi¬tions. It is obvious that the greater the differences in the minerals, the more divergent may be the conditions that give rise to them and the more readily one condition can be distinguished from the other. In the kaolinite group, differences between individual members are small, therefore the differences in condition of origin are presumably subtle and difficult to define. At the same time, the very fact that the minerals differ only slightly makes them more sensitive indicators of the exact conditions under which they and the minerals associated with them were formed. Since clay minerals are being used more and more to evaluate the nature, value, and mode of formation of economic mineral deposits, an attempt to define these subtle differences would appear worth while. For purposes of the present discussion, the minerals nacrite, dickite, kaolinite, the so-called "fireclay mineral," halloysite (4H2O), halloysite

Jan 1, 1952

By Sidney Wise

WHILE the installation of mine bulkheads to retain water under high pressure is y no means a rarity, the following points Which arose in the designing and placing of two of these bulkheads may be of interest: The Hibernia magnetite mine, located about 40 miles west of New York, in the State-of New Jersey, is partly filled with water. This mine is located on an ore lens, the outcrop of which is over a mile long. The ore has been mined from this lens from the surface to a depth of more than 1,500 ft. It was held desirable to- separate the old workings from the new, and to allow the former to fill to the 850-ft. level. Two weak places existed between the new and old workings below this level: namely, a temporary bulkhead on the 10th level and a rock bulkhead of indeterminate thickness on the 16th level. When the matter of allowing the old workings to fill was investigated, the fact was developed that if these old workings were filled, the bulkhead on the 10th level would be subjected to a water pressure of about 50 lb. per square inch, and that 200 lb. per square inch would act on the 16th-level bulkhead. As the above-mentioned barriers were not deemed of sufficient strength to permit of these pressures, it became necessary to design and install new bulkheads. Design As the 16th-level bulkhead was required to withstand a pressure of 200 lb. per square inch, it presented some difficulties. A careful consideration of the various types of mine dams now in use led to the adoption of a design of the form of a truncated wedge. In this, the pressure side of the dam is of greater area than the back, so that the resultant action is similar to driving the wedge. By cutting generous skewbacks in the walls, roof, and floor, this type in reality becomes an invisible arch. The wedge feature tends to compress the materials in the bulkhead, thereby adding to its imperviousness.

Jan 8, 1914