Search Documents

1-Iron and Steel JOHN A MATHEWS, Chairman Ralph H SWEETSER Vice-chairman WILLIAM CAMPBELL, Vice-chairman MAX ROESLER, Secretary Iron Ore CHARLES B MURRAY, Chairman R C ALLEN W O HOTCHKISS MAX ROESLER ERNEST F BURCHARD THOMAS T READ DWIGHT E WOODBRIDGE M M DUNCAN WILLIAM KELLY CARL ZAPFFE C T FAIRBAIRN CHARLES F RAND

Jan 1, 1923

By Samuel H. Dolbear

THE purpose of a technical report is to record facts, usually collected by investigation, and to interpret these facts in understandable language. The audience may range from a small shareholder without technical knowledge, to a highly trained engineer or geologist. If the client is a mining company with technically trained executives, the report writer's problem is relatively simple. The writer will then be appraised not only for his conclusions, but for clarity of language and organization of the report. If the writing is bad, the construction careless, and there is a failure to clearly convey to the reader the facts and the author's conclusions, the report is a failure and the writer may have damaged his professional character. Spoken words die quickly, written words may constitute a permanent record and if they are badly composed they may rise up to damn the author. "A good measure of an author's understanding of his subject is his ability to express it clearly in plain words." Good English Teachers in the fields of mineral technology have frequently complained that even in post-graduate groups there is an appalling indifference to their appeals for good English. Some have even noted a student's belief that the use of refined English is effeminate. If those with such immature beliefs could measure the pay-check damage arising from the use of "sloppy" language, they would realize that precision and refinement in English may be quite as important as technical accuracy. When the reader audience is without technical knowledge simplicity in treatment becomes especially important. If one is engaged in consulting work, in government service, or in any field where reports have public distribution, the language employed should be technically adequate but simple enough to be understood by non-technical readers. For example, one may use the term "visual" in place of "megascopic." Technical language can be so obscure that it cannot be understood even by highly-trained students. In the March-April (Vol. 47-No. 2) issue of Economic Geology, Nicholas Vanserg ridicules these extremes and quotes various paragraphs from published material, such for example: "However, lattice orientation unaccompanied by cognate dimensional orientation can never be attributable to growth from an isotropic blastetrix." "The temperature declines because of cessation of the exothermic chemical and mechanical equilibriopetal processes." These he calls "good geologese" and they are calculated not only to baffle the reader but to impress upon him the erudite character of the author. Revision In some cases, difficulty arises from the fact that the writer is too close to the subject and unconsciously assumes that his reader is equally familiar with the background of the report. It is difficult for the writer to regard his work objectively and to determine to what extent it is likely to be understood. Every important manuscript will gain in clarity if the author will have it reviewed by an informed reader. But the writer must not be oversensitive to criticism and should not treat his composition as perfect and beyond the possibility of improvement. The first draft of a report always requires revision, regardless of the care used or the ability of the writer. Three or four revisions are not uncommon. The first draft usually requires expansion in places, the deletion of non-essential material, and language changes to promote clarity of expression. This should be done by the author after a lapse of time, even if only overnight, in which his mind has been occupied on some other subject. Possible improvements are always more visible. The manuscript should be passed on to another reader for further suggestions. Organization of Material The engineer should study available reports and library references before going into the field. If the previous reports have been responsibly done and can be accepted as correct, then much field time can be saved. It is, of course, customary to make some on-the-ground checks to confirm earlier reports, particularly those relating to ore reserve which may have undergone changes. Report writing requires time and expense, but nevertheless, the basic reasons for conclusions should be presented even in the case of a worthless property, for it may prevent a duplication of the work. If the mine examined is obviously of no further interest, no useful purpose can be, served by preparing a report in detail. In one case an engineer travelled all the way to South America only to find that the mine had been grossly misrepresented and was valueless. His cabled report "Nonsense" is a case of over-simplification, but it served his company's purpose. The first step in report organization should be the selection of subjects. This should be done at the mine, and the data collected for each subject should be reviewed in considerable detail on the ground. Otherwise one may find that he has failed to collect some essential details not readily obtained after he has returned to headquarters. If the property to be described is undeveloped, then many of the subject titles are automatically eliminated. Usually no useful purpose is served by an attempt to calculate the cost of production under such circumstances, although the cost of exploration

Jan 1, 1952

[Billings Petroleum Section: Fraser M. Burback, chairman; N. J. Matthews, first vice-chairman; Charles B. Evans, second vice-chairman; and lion M. Madden, secretary-treasurer. Meets 3d Tues., Petroleum Club. California Coastal Section: Jack R. Severns, chairman.; Gilbert L. Jemmott, vice-chairman,- Jack A. Biren, secretary; and Robert L. Richardson, treasurer. Meets 3d Thurs.] [ ]

Jan 1, 1961

By Joklik, G. F.

Most publicity about the copper industry nowadays is focused on the adequacy of ore reserves and on excessive mining capacity. These concerns, stemming from public awareness of actual and potential shortages and oversupplies, relate to production rather than consumption. Perhaps the reason for this one-sided view is that copper is thought of as a commodity which is conspicuously traded in world markets, rather than as one of many industrial materials that serve today's rapidly changing technology. Copper differs from other widely traded commodities in that its real cost of production has progressively increased since World War 11. The reasons for the increase are identifiable by analyzing operations in one of the world's large producing centres, the copper province of Arizona. Another respect in which copper differs from some other commodities is that increases in demand occur less automatically in the case of copper than they tend to in commodities whose consumption is more directly related to population growth. The copper industry's current inability to generate and attract needed investment capital is attributable to these differences between copper and other commodities; it suggests that the concept of copper purely as a commodity is outdated. The key to the problem is better integration between the activities of copper producers and users. Depending on circumstances, integration takes various forms- for example, investment tied to long-term sales con- tracts between producers in developing countries and consumers overseas; common ownership of producing and manufacturing facilities in industrialized nations like the U.S.; and consumer-oriented research and marketing by the copper producers.

Jan 1, 1978

By J. R. Thoenen

IN five years mineral wool has grown to a thirty-million-dollar industry from one whose output was valued, in 1933, at $1,700,000. Ten years ago, in 1928, there were only seven producing companies, with an annual output of but 50,000 tons. By 1936 fifty or more companies were producing half a million tons. The industry is still growing vigorously and will profit from the expected activity in building in 1339, for two-thirds of this material is used for building insulation and to assist in fire-retarding, in both new and old homes. It is as useful in the South, to protect against heat, as in the North, to keep out the cold, if one may speak nontechnically. It is a concomitant of air conditioning, that new addition to the American standard of living that began in theatres, department stores, and railroad dining cars, and is rapidly progressing down to small homes. Here, then, is an industry that is only beginning to have a present, and one with an almost certain important future; one that depends upon mining and the by-products of mining for all of its raw materials; one that every progressive mining man should know something about.

Jan 1, 1939

By Thomas A. Lang, John A. Bischoff

The use of rock bolts for the support and stabilization of coal mining excavations was introduced over 30 years ago and, since that time, has progressively increased until today it is the primary means of support and stabilization of large underground openings. Early analytical studies and work with photoelastic and physical models established that even highly fragmented rock could be stabilized by rock bolting and form a load-carrying structural member that would span an opening. For stability, interaction of the bolts is essential and it depends on the bolt tension, the length and spacing of the bolts, the characteristics of the rock, and the applied load. However, the development of an explicit functional relationship embracing all these factors proved to be elusive. A review of the early rock bolting investigations led to the concept that the basic element of a rock bolted roof is the reinforced rock unit (RRU), consisting of an individual bolt and the rock immediately surrounding and adjacent to it, and to the development of mathematical equations which give the minimum bolt tension required to ensure that the RRU's are stable relative to one another and act together as a structural member. Analytical procedures have been developed for integrating RRU's into a reinforced rock structural (beam-arch) member which spans an underground opening and providing a rational basis for the design and installation of rock reinforcement systems.

Jan 1, 1982

By R. P. Smith

In 1937 the employees of the Hollinger Consolidated Gold Mines Ltd.. at Timmins. Ont., Canada, approached organized medicine for a plan to provide themselves and their families with a complete medical service including hospitalization. This approach was made because of two conditions: (1) the necessity for some organization whereby contributions could be made in instalments to offset the sudden and large expense connected with illness for which the average employee is not prepared, and (2) the need for a more cohesive quality of service to replace a contract practice then in vogue, which did not take care of the employee's family or dependents. In different parts of the United States and Canada similar plans were in force, not only for employed groups but for numbers of people in circumscribed areas. In Europe different countries had adopted various forms of health insurance plans. It then was no surprise that these employees as a group should ask for some similar plan. With the cooperation of the management, a plan was instituted. The plan has one object only—the provision of medical services, including the accessory services such as hospitaliza-tion, X-rays, nursing, and necessary drugs and medicines. It is not concerned with cash benefits, sickness and accident payments, or any form of monetary return as the result of illness, but is simply an organization to provide medical services and pay for them from a central fund. It is a nonprofit organization and the only shareholders are the employees and their families who contribute and who in turn receive services. The Hollinger plan is limited to the employees of the Hollinger mine, who live in Timmins and the immediate vicinity. At first, the membership was voluntary. In the third year, it was made a condition of employment, with the proviso that at the end of any Association financial year an employee may withdraw if he wishes to do so. After withdrawal, he cannot again become a member until the end of the next Association year, and then only by the payment of the back dues. This step was taken to ensure continuity, and to prevent employees from withdrawing when well and reentering when faced with impending illness or operations. The employee himself is subject to medical examination on application for employment, and if accepted is subject to further examination by a specialist in chest diseases under the Workmen's Compensation Board of Ontario. Thus it is possible to exclude those who have heart disease, tuberculosis, or other disabling conditions when first employed. Wives and families of employees are not subject to medical examination but other dependents of an employee—mother, father, or other relative—who are declared by the employee to be wholly dependent upon him must be examined. The employee

Jan 1, 1946

By T. A. Rickard

"The chief aim in style ought to be absolute precision", said Flaubert. "There is only one noun that can express your idea, only one verb that can set that idea in motion, and only one adjective that is the proper epithet for that noun." Let this be your motto. The engineer tries to be exact in all his measurements; he should measure his language with similar exactness. The technical term is a word of precision. It is not only precise, it is a word-saver. To the unscientific the earth is "a ball slightly flattened at the poles, something like an orange". To the scientific it is "an oblate spheroid". A similar contrast between the precision of the technical term and the vagueness of common words is afforded by a conversation between Ivanhoe and Rebecca: "' What device does he bear on his shield?' asked Ivanhoe. 'Something resembling a bar of iron, and a padlock painted blue on a black shield.' 'A fetterlock and shacklebolt azure', said Ivanhoe "-using the technical terms of heraldry. It is good style in writing, however, to adapt your manner of expression to the intelligence and experience of the person or persons to whom the writing is addressed. The description of a mine should be worded differently according as it is intended to inform a mining engineer, a director, or a bishop. REMEMBER THE READER. It is as incorrect to write in a technical way for a non-technical reader as to write in a popular way for a technical or scientific reader. That style is best which enables the writer to place himself in the closest mental touch with his reader, to establish the maximum of sympathetic understanding. Let your precision be\ proportioned to your accuracy. You should not try to be precise in matters that do not admit of

Jan 1, 1931

By AIME AIME

WILLIS McGERALD PEIRCE-"Jerry" to his host of friends, and on that account a hit of a puzzle to those who have known him only as "W. 14."-a native of Buffalo, educated at Penn State College, Illinois: and Yale universities, has bee11 associated throughout all of his professional career with the New Jersey Zinc Company. Jerry has served successively as investigator, section chief, and division chief in the research department of the company and has just been promoted to chief of research.

Jan 1, 1937

Discussion -of the paper of I. N. KNAPP, presented at the New York meeting, February, 1915, and printed in Bulletin No. 96, December, 1914, pp. 2783 to 2793. A. C. LANE, Tufts College, Mass.-Is there any noticeable effect in drilling against salt water? Mr. Knapp says that the mud settles very quickly when brine is added-. What is the effect when you strike a strong salt water ill boring? I. N. KNAPP.-You are supposed to have enough mud pressure in your well to keep the saltwater out. I have drilled against what I knew to be 80 ft. head of water, and hot water too at 99.5°; this water did not show until the well was bailed and the mud pressure reduced. HENRY Louis, Newcastle-upon-Tyne, England (communication to the Secretary*).-Mr. Knapp may be interested to learn that the use of mud in drilling through porous strata is much older than lie appears to be aware of. It has been used notably by Honigmann for boring shafts in Holland and in some of the adjoining portions of Germany. At the Oranien Nassau colliery, shafts about 12 ft. in diameter and 425 ft. deep were sunk in. this way-namely, by boring with a rotary borer, a thick mud puddle being pumped into the shaft, so as to maintain a pressure in the shaft greater than the hydrostatic pressure in the surrounding loose sands and thus keeping the sides of the shaft from collapsing. He will find references to this method in Das Abbohren von Schächten; Handbuch der Ingenieurwissenshaften, p. 134, also in the Transactions of the Institution of Mining Engineers, vol. xiii (1896-97), p. 155. The process appears to have been employed even before 1895, though I cannot give the exact date when it was first used.

Jan 5, 1915

By G. S. Coe, G. F. Bolling

The columnar-to-equiaxed transition (CET) has often been studied as a function of concentration, C, temperature gradient in the melt, G, and rate of solidification, R. Although it may not be immediately obvious it is sure that the CET, expressed as some ratio G/R necessary to suppress equiaxed nucleation for a given C,' cannot be a single-valued function of C. This restriction which is ignored in theoretical presentations is most trivially illustrated by the following simple reasoning. An ordinary casting is an unconstrained system where the thermal conditions change continuously with progressive solidification, and thus where the ratio G/R decreases from the outset. A CET occurring early in a casting (much equiaxed material) must then mean a higher value of G/R at transition, in comparison with the late CET which implies a more columnar ingot. Therefore, when we choose to experiment under constant superheat for all alloys across the simplest binary, and we find an inversion in the amount of equiaxed material, we shall find two values of C satisfying the G/R condition. However, in addition to this simple instance, the early experiments of ~orthcott' seem to show that the amount of equiaxed material in cast ingots may be a multivalued function of composition in a given binary system. In the present investigation, the CET has been examined in Pb-Sb, Pb-Ag, Pb-Sn, and Sn-Pb under several types of casting conditions. First, we have used the "bidirectional" ingot section Simulation;~ and we have used .'i~z situ" ingot solidification where a hot mold already filled with liquid is chilled so that there is no disturbance provoked by pouring. Differences in method are trivial to our purpose except for the fact that certain variations are more simply observed by one technique than by the other. Second, we have varied the mode of superheating from the simple extreme of casting all alloys from the same temperature regardless of composition to the careful casting at a standard superheat, calculated with respect to the alloy liquidus. Third, we have made provisions for decanting and interface observation, so that some "castings" were not completed. The results obtained with Pb-Sb are exemplary; some of these are shown in Fig. 1 along with explanatory captions. At 9 to 10 at. pct Sb, and thus above the solid-solubility limit Cs = 5.8 at. pct Sb and yet below the eutectic concentration Ceu = 17.5 at. pct Sb, there is a persistent anomaly in all the variations. Measurement was easy enough and standard enough so that we may forgo discussion of either method or possible error, in view of the forceful self-consistency shown by experiment. Solute distributions were measured along the bidirectional ingots in order to determine if a solute buildup had occurred at the CET. No anomalous changes in concentration were observed along the bars at either side of the solute anomaly of 10 at. pct Sb. The microstructures of the ingots were also examined across the range of composition investigated. At concentrations less than 9 at. pct Sb the micro- and macrostructures were typical of the cellular-dendritic growth usually reported for the columnar zone. Above the anomaly, both the columnar grain size and the amount of primary phase decreased. This microstruc-tural observation can be correlated with observations made of decanted interfaces. Below 9 at. pct Sb, the interface reveals the "normal" columnar dendritic structure; however above the anomalous concentration range, preferential growth of certain dendrites appears to form a "super dendrite" pattern. In Fig. 2 a microstructural view of the etched '(super dendrites'' shows their constitution both in terms of relative phase proportion and in terms of the ordinary smaller dendrites.

Jan 1, 1969

By John Howe Hall

One's first thought, upon being chosen to deliver the Henry Mario Howe lecture, is of pride at being selected for this post of honor, but ther succeeds immediately a deep sense of the Obligation thereby incurre to give of one's very best in order to make a contribution worthy of hir in whose memory these lectures are given. One who had the goo fortune to be associated with Henry ill. Howe, upon sitting down t prepare such a paper as this, irnrnediately falls to musing upon thc day when his face and his footfall were familiar from constant association, an recalls with singular vividness his active figure, his mobile, alert face, an his keenness in penetrating to thc corc of the subject under discussior Like Dr. Mathews, I was a young man when I first worked under hi direction, now nearly a quarter of a century ago, and in those early day he oft,en seemed a hard taskmaster—a man whose standards it woul never be possible for me to meet. I well recall his insisting upon m proving for the third time the truth of a conclusion which I had brc unwilling to submit to him until it had been confirmed by two carefull planned experiments. To my impatient protest that thc third .demor stration he asked for was but a repetition of the second, with differer samples, he replied, "Yes, that is true, but the inherent improbability ( your conclusions is so evident that I can not accept them until you prov your case again." "Shall I ever do a thing well enough to suit him? I thought. Looking back today upon many similar incidents, 1 suspect that h never expected me to attain the excellence he preached, and held up t me and to himself as a model, but knew out of the fullness of his experienc. that in no other way could he so impress upon me the necessity in researc of the patient, never-failing attention to detail and to accuracy tha distinguished his own work. How painstaking he was in the preparation of his many books an professional papers, as well as in his experimcntal work, was ncvcr s

Jan 1, 1929

By C. E. Gregor

Current modern trends in mining show that hoisting shafts are being expected to fulfill an important ventilation function. However, where rigid guides and supporting structures are mandatory, ventilating power costs will be high, unless the transverse structures (shaft sets) are streamlined. In the complex configurations of hoisting shaft furniture patterns, either for original design purposes, or for the adjustment of an existing shaft, a useful degree of aerodynamic optimization, by reduction of overall resistance, can only be effectively evaluated by model studies in a special purpose wind tunnel, as described herein. The author has shown that, in one particular case, an annual power cost saving of more than $50,000 was indicated, mainly by the selection of buntons and dividers of improved aerodynamic profile. Mining companies are now realizing the advantages that can accrue through proper attention to the aerodynamic aspects of mine shaft design. With progressive demands of civilization for an ever greater supply of coal and metals, and with greater depths of working, higher rates of extraction, advanced degrees of mechanization, and improved standards of environmental health and work comfort, shaft design is becoming an extremely important aspect of mining operations. In addition, because the cost of sinking, equipping, maintaining, and operating a mine shaft is continually increasing, there is a greater incentive to use a shaft for the maximum duty, consistent with economy. The current natural tendency is therefore to sink multi-purpose shafts, to install as much equipment as is safely and effectively possible to operate; and then, over and above all these functions, to use the shaft to its maximum possible ventilating capacity, as a major, or auxiliary, airway. Clearly, this latter additional function can only be employed at a significant cost, since the most economic operating airways are smooth-lined and devoid of internal rigid furniture. It is true that hoisting functions can be carried out in such shafts if rope guides are used, but only under restricted conditions. Where a manway must be provided, fixed guides and supporting structures are mandatory, and ventilation costs become accentuated. It is generally recognized that the prime element of cost in ventilating a mine can be represented by the power required to drive the fan unit. It is also known that the largest component of total mine resistance is that of the downcast shaft, where this shaft is equipped with rigid guides for hoisting purposes. The pressure loss varies directly as the resistance of the shaft, in accordance with a modification of the Atkinson equation p = RQ2/3600. Furthermore, the air horsepower drawn is given by the equation AHP = (p x 0/33000. Therefore, the power required to drive the fan unit varies as the resistance of the shaft and the cube of the air quantity. Clearly, if Q is a specified minimum, then the only way to minimize the pressure loss (and the power costs) is to reduce the shaft resistance R. (See Table I for a list of symbols.) The resistance to airflow of a shaft equipped with rigid guides and supporting structural sets consists of two components which, for the sake of analytical simplicity, can be regarded as additive. 1) Frictional resistance, represented by the viscous frictional forces within the boundary layer, as air flows along the surfaces of the walls and the periphery of the vertical elements (guides, pipes, cables, ropes, etc.) of the furniture. The friction loss can be readily calculated by the Atkinson equation, after selection of a suitable value for the friction factor K from the McElroy compilation.' KxLxO xQ2 5.2 xA3 Friction loss can be minimized by lining the shaft walls (particularly if of circular or elliptical cross-section) with a smooth continuous lining of monolithic concrete.

Jan 1, 1968

R. L. Fleischer (Department of Metallurgy, Massachusetts Institute of Technology)— The authors have presented valuable observations of oehavior of aluminum at intermediate and high temperatures. I should like to consider their interpretation of the appearance of cross slip plane traces in sample B-3 as partly due to "bending of the crystal due to grip constraint." Because bending moments might be set

Jan 1, 1960

E. P. Pfleider, University of Minnesota I would like to ask Bob Merrill whether he considers that horizontal concave curvature of a slope has any stabilizing effect, such as Jenike 1 suggested several years ago. R. H. Merrill, U. S. Bureau of Mines, Denver Federal Center The stabilizing effect is due to the restraint offered to radial movement by the curvature. We found in laboratory tests that if we constrained the rock with the same stresses as those measured in the pit then it would sustain a maximum stress about two or four times greater than when the same rock type was unconstrained. We are therefore definitely of the opinion that a constrained situation in a slope is favorable towards stability. G. A. Leonards, Purdue University I was interested in Mr. Lane's observations concerning the correspondence between rate of slide movement with rise of reservoir. Perhaps the most interesting feature is that the rate of movement at the time the rock slope failed was less than the rate at an earlier time when it did not fail. This is difficult to explain from current slope stability theory. K. S. Lane, U. S. Army Corps of Engineers I believe that reduced rate of movement is the result of the progressive type of failure, such as described by Patton and Deere. which occurs along the sliding surfaces. It is difficult to analytically define the progressive failure condition for inclusion in slope stability conditions, but its existence should be recognized in design. We should also realize that many apparently stable slopes undoubtedly contain overstressed regions. To design a slope with no overstressed region would be uneconomical and conservative. D. H. Deere I would pose the question-"What is the meaning of a factor of safety of one?" We were involved in the design of a large, irregularly shaped, underground cavity with an unsupported span of several hundreds of feet. Tests on rock specimens indicated a strength of 1300 lb per sq in. The RQD would have been between 90 to 100 percent indicating excellent structural continuity. In-situ stress determinations indicated an approximately hydrostatic state of stress at a level of 1400 lb per sq in. Calculation of stress concentrations at the walls indicated that the stresses there would be about 3000 to 4000 lb per sq in. Admittedly the rock is in a confined condition everywhere except at the very skin of the wall and the rock walls would thus on the average be somewhat stronger. Allowing for the effect of restraint the factor of safety was found to be less than 0.5 over a region several feet into the wall. Construction was started, using rockbolts only to support the walls. Failure around the immediate skin occurred after each

Jan 1, 1967

By VERITAS

THE most concentrated industry of major character in the United States is that of the Ford Motor CO., which is to say Henry Ford. Its sole function is to supply the public with a cheap motor car which it does to the extent of two million or so per annum. In doing this, a relatively small profit per unit is multi- plied to an enormous aggregate per annum and has resulted in the creation of one of the greatest industrial fortunes of the world. The industrial and sociological consequences of .this are bound to be immense. On the physical side the production of two million automobiles means the consumption of two or three million tons of materials, chiefly metals, in the 'direct form of the finished product', and a huge additional tonnage of coal and other things that ,are consumed en route, and also the labor of many thousands of men. In the development of a business on this scale it was but natural that the Ford Motor ,Co. should seek to supply itself with the raw 'materials it needs, and they being so largely coal and metals the company is brought into close contact with the mining and metallurgical industries. It is a huge consumer of - steel. It is the fourth largest consumer of copper. It is a large consumer of lead, tin, aluminum and zinc. The mining and metallurgical industries have, therefore, good reason to learn to know Henry Ford, his personality, his thoughts and his policies.

Jan 1, 1924

P. Herasymenko (New York University, New York) —The authors' experiments on equilibria between water vapor and liquid synthetic slags represent a valuable contribution to our knowledge of the nature of liquid slags. They can be regarded as a proof of ionic splitting of water molecules dissolved in slags. The assumption that water dissolved in slag was com- pletely ionized was made in my report on hydrogen equilibria in steelmaking as early as 194010. In that paper, the first systematic data were given on the content of ionized hydrogen in acid and basic open-hearth slags. The paper probably escaped the notice of the authors, although they mention the articles published later by other investigators who reported erratic and

Jan 1, 1958

By H. O. Hofman

(Canal Zone Meeting, November, 1910.) I. INTRODUCTION. IN a previous paper,1 The Behavior of Calcium Sulphate at Elevated Temperatures with Some Fluxes, we published the results of our investigation, into the behavior of calcium sul-phate in air; that, is, under oxidizing conditions. The results as a whole hold good for a neutral atmosphere, or one which has no chemical effect upon calcium sulphate. The present paper deals with the behavior of calcium sulphate under reducing conditions, the reducing-agents employed being carbon monoxide and carbon, and the changes the calcium sulphide formed undergoes when it is subjected to an oxidizing-roast. Technical literature deals very sparingly with the subject. The information furnished by the recent leading chemical manuals is general. Thus Dammer,2 Moissan,3 and Abbegg,4 quote Berthier as having reduced, in 1823, calcium sulphate with carbon, and Stammer as having done the same in 1851 with carbon monoxide; Gmelin Kraut 5 add Leplay and Laurent (1848) as third investigators. Metallurgical authorities confine their statements to the known fact of reduction by carbon. II. PREPARATION OF RAW MATERIALS. 1. Calcium Sulphate.-This salt was prepared in the same manner as described in our previous paper,6 and was found to be chemically pure. * Professor of Metallurgy, Massachusetts Institute of Technology. + Metallurgical Instructor, Imperial Technological Institute. 1 Trans, xxxix., 628 to 653 (1909). 2 Handbuch der anorganischen. Chemie, vol. ii., part 2, p. 309 (1894). 3 Traité de Chimic Minérale, 1904, vol. iii., p. 543. 4 Handbuch der anorganischen Chemie, vol. ii., part ii., p. 116 (1905). 5 Handbuch der anorganischen Chemie, vol. ii., part 2, p. 233 (1909). 6 Trans., xxxix., 630 (1909).

Nov 1, 1910

By Leo Ranney

ANY years ago a prospector came to a Nevada town and built himself a shack. Day after day he searched the hills for gold -but he found none. He closed his shack and hurried north, where a strike had been made. Next he tried to trap the flour gold that floats down the Snake River. He panned the black sands along the Oregon coast. He ranged over the mountains and up the gulches of far-off Alaska. At last, broken in health, six years ago he came back to his old home in Nevada. There his shack still stood-nobody wanted it. One day he started a garden in the rocky soil that he owned. His spade turned up a chunk of quartz, and in that quartz were stringers of gold. He had found a rich gold vein, running right under his own house. You gas producers who have hurried to Oklahoma, Louisiana, East Texas, South Texas, West Texas, even to California to drill wildcat holes a mile or two miles deep-why not, like the old gold prospector, have a look in your own back yard? Some of your coal seams contain 20,000,000 cu. ft. of natural gas per acre.

Jan 1, 1943

By E. J. Duggan

CLIMAX ore is an altered and highly silicified granite, about half of the gangue being quartz. Molybdenite is the only mineral recovered and most of it is intimately associated with the quartz in fine veinlets. Other minerals are molybdite, pyrite, and chalcopyrite. Although the molybdite may be readily extracted by hydrometallurgical methods, its content is too low to make this profitable. The pyrite ranges from 2 to 5 per cent and the chalcopyrite from 0.03 to 0.05 per cent. There is not enough copper to make its recovery attractive and one of the problems is its elimination, and that of pyrite iron, from the final product. On account of the high degree of dissemination of the molybdenite and the necessity of eliminating the iron and copper, fine-grinding followed by flotation is the only known feasible method of concentration. Two factors, peculiar to Climax ore, have a predominating influence on the metallurgical attack: (1) Molybdenite is one of the most easily floated minerals. High recoveries may be made with pine oil alone if the

Jan 1, 1946