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By G. L. Corrigan, J. R. Coleman

Four factors that largely determine the end product obtained when cement and water are mixed are the chemical compo ition of the cement, the fineness to which the cement is ground, the amount of mixing water used, and the procedure used in mixing the slurry. In order to study the effect of two of these factors, the other two, the chemical composition and method of mixing, are kept constant, leaving as variables fineness and water-cement ratio. Through years of experimentation and usage it has been well established that the reduction of cement clinker to a very fine state by grinding improves its cementing value, principally because the reaction between cement and water takes place only at the surface of the cement particle, further action being hindered by the accumulation of reaction products that tend to coat the unreacted material. Therefore, the more finely ground a cement, and the greater the surface exposed in proportion to its mass, the more rapid is the hydration rate. Similarly, the greater the surface exposed, the greater the proportion of the cement that reacts, and the lower the amount of residue that is unreacted and so remains inert and unable to make any contribution to cementing properties.1 Although it is more expensive to manufacture a finely ground cement than a coarser cement, the advantages of fine grinding of construction cements were so marked that the fineness of cement has increased considerably in past years. When the manufacture of special oil-well cements was begun, it was necessary to consider properties of cement that previously were considered of minor importance, foremost of these being pumpability. Since, with the water-cement ratio constant, a finely ground cement will produce a neat slurry of higher consistency and shorter time of pumpability than will a coarser cement, there is a tendency to grind oil-well cements to a lower degree of fineness. Therefore, in order to produce oil-well cements that will make a slurry having a long time of pumpability, cements are manufactured that because of their coarseness generally are poorer cementing materials than some of the more finely ground construction cements. On the other hand, often it is necessary to pump oil-well cements for long periods of time to place them properly behind a string of casing in a deep well, and since high strength is not of foremost importance for such cement, there is room for considerable controversy concerning the proper fineness range.

Jan 1, 1941

By George W. Riter

A distinguished engineer, the active head of a large mining company, has said that surveying attains the dignity of a profession only in the hands of a few men—the few who know how to keep notes that will be understood by even a novice without further word of explanation. Of all mine-records, survey notes are perhaps the most important. The maps made from them serve as a working-guide, and as framework for other data; and when, from any cause, access to underground workings is shut off, the surveyor's record often becomes invaluable. So seldom docs a surveyor have a chance to check underground surveys by making a closure, that he is compelled to rely on the precision of each step of his work for the accuracy of the final result. When data are fully recorded on the spot, the notes, even in the hands of second parties, become evidence of the care and precision with which the surveying was done. It is worth a great deal to be able to pick up the work of a former surveyor where it was left off, and to be able to carry it forward without rctracing from the beginning. The purpose of this paper is to describe the survey-note system of a mine now under my direction, in which underground surveys had to be relied upon entirely for the proper division of rich ore-bodies between neighbors, thereby placing a premium on accurate surveying and permanent records. In survey-work, it soon turns out that paper is the least item of expense, and that little is gained by trying to economize note-book space. For many purposes it is best to record notes on cards or loose-leaves, which may be left in the office at the end of the day's work, and need not be carried into the mine again, there to become smeared with grime and grease. With the loose-leaf or card system, all notes relating to the same local-

Jan 1, 1911

Speech advocating a new law of the sea-the "common heritage of mankind." The 3rd Law of the Sea (L0S) Conference was held in Caracas in mid-1974, and a fourth UN conference, scheduled for mid-March in Geneva, will once again attempt to produce a cohesive LOS Convention to take up where the 1958 Geneva Convention left off. The 1958 Convention specified coastal state resource rights on a continental shelf out to a water depth of 200 m-a supposed technological limitation at the time. But the surge of offshore petroleum drilling and the advent of the nodule resource have long since exploded beyond the 200-m limit.

Jan 4, 1975

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and visitors who registered at Institute headquarters during November: George W. Otterson, Mauson, B. C. Roy H. Allen, Chihuahua, Mexico. E. L. C. Ayres, Bound, Brook, N. J. George A. Packard, Boston, Mass. M. Russell, Bound Brook, N. J. Richard C. Patterson, Jr., Kansas City,,Mo. Carlo Spruyt, Antwerp, Belgium. Francis C. Phillip, Pittsburg, Pa. Charles A. Pringle, San Francisco, Cal. M. H. Kuryla, Mexico City, Mexico. E. S. Bardwell, Great Falls, Mont. Arthur Chippendale, Mexico City, Mexico. Sir Robert Hadfield, London,, England. F. Danvers Power, Sydney, Australia. James A. Barr, San Francisco, Cal..

Jan 12, 1913

New York Meets first Wednesday after first Tuesday of each month. J. E. JOHNSON, JR., Chairman EDGAR RICKARD, Vice-Chairman D. M. LIDDELL, Secretary, 7 Wall St., New York, N. Y. JOHN V. N. DORR C. A. BOHN, Treasurer LEWIS W. FRANCIS Boston Meets first Monday of each winter month. R. L. AGASSIZ, Chairman JAMES G. CARLETON, Vice-Chairman E. E. BUGBEE Secretary-Treasurer, Mass. Inst. of Technology, Cambridge, Mass. W. E. C. EUSTIS G. A. PACKARD Columbia Holds four sessions during year. Annual meeting in September or October. W. H. LINNEY, Chairman OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. STANLY A. EASTON S. SHEDD

Jan 9, 1917

By John F. Blandy

Although the question of the "waste of anthracite coal mining " has been so frequently discussed, and a committee was appointed at the first meeting of this Society to consider and report upon the subject, still but little progress seems to have been made in arriving at a conclusion as to how it ran be reduced. That committee made a preliminary report at the August meeting, 1871, in which it divided the question into three parts, namely: Waste in mining, in preparing for market, and in transportation. I shall not here refer to the first item, as so much depends upon the peculiar features of each separate mine, and the skill of those in charge; but in reference to the second, that of preparing the coal for market in breaker and screens, I wish to make some remarks. There is no use considering the question, whether the coal should be broken up to suit the fancy of consumers; all miners are satisfied that it should not be, but the consumers decide that they want it that way, and the miner must submit, and simply utter his maledictions upon the head of the man who first suggested a breaker or screen, if that is any consolation to him. What is called waste in this process of preparation, is the dust and fine coal, which results from the breaking and screening, and, as we all know, this is a very important percentage of what passes from the slope to the top of the breaker. Now, if this dust and fine coal can be utilized—the slate which is picked out is not to be taken into consideration as waste—then we get rid of this item entirely. There is no question in my mind that this article can and will be used as a steam generator at least, and I think, therefore, that in depositing

By John F. Blandy

ALTHOUGH the question of the "waste of anthracite coal mining" has been so frequently discussed, and a committee was appointed at the first meeting of this Society to consider and report upon the subject, still but little progress seems to have been made in arriving at a conclusion as to how it can be reduced. That committee made a preliminary report at the August meeting, 1871, in which it divided the question into three parts, namely Waste in mining, in preparing for market, and in transportation. I shall not here refer to the first item, as so much depends upon the peculiar features of each separate mine, and the skill of those in charge; but in reference to the second, that of preparing the coal for market in breaker and screens, I wish to make some remarks. There is no use considering the question, whether the coal should be broken up to suit the fancy of consumers; all miners are satisfied that it should not be, but the consumers decide that they want it that way, and the miner must submit, and simply utter his maledictions upon the head of the man who first suggested a breaker or screen, if that is any consolation to him. What is called waste in this process of preparation, is the dust and fine coal, which results from the breaking and screening, and, as we all know, this is a very important percentage of what passes from the slope to the top of the breaker. Now, if this dust and fine coal can be utilized-the slate which is' picked out is not to be taken into consideration as waste-then we get rid of this item entirely. There is no question in my mind that this article can and will be used as a steam generator at least, and I think, therefore, that in depositing

Jan 1, 1877

By AIME AIME

THE third award of the W. L. Saunders Gold Medal for "distinguished achievement in mining" has been made to John Hays Hammond. The two previous awards were to David Brunton and Herbert C. Hoover. Since the principal events in Mr. Hammond's interesting life are not only well known to his many friends but were summarized in the April, 1928, issue of MINING AND METALLURGY (p. 186), it seems most appropriate to reproduce here the chronological record of his career that appears on pages 67 to 69 of "A Student Reverie," by his friend and fellow Freiberg student, F. G. Corning. Mr. Hammond, after graduating from Yale in 1876, was a student at Freiberg for the next three years.

Jan 1, 1929

Committee of Arrangement E. P. MATHEWSON, Chairman. FRANK M. SMITH, Vice- Chairman D. C. BARD, Secretary, Montana State School of Mines, Butte, Mont. OSCAR ROHN, JAMES L. BRUCE. On Aug. 20, 1913, the following 30 members of the Institute residing in Montana made written application to the Board of Directors of the Institute for authority to establish a local section of the Institute to be called the Montana Section, with headquarters at Butte, and having such territory as may, later be determined on. This petition was granted by the Board at its meeting in Butte, Mont., Aug. 20, 1913. The committee named at the head of this paragraph was appointed to' arrange for permanent organization of this section.

Jan 9, 1913

1-Coal and Coal Products HOWARD N EAVENSON, Chairman C. T. HAYDEN, Vice-chairman, Bituminous Coal Production CHARLES DORRANCE, Vice-chairman, Anthracite Coal Production HOWARD P. ZELLER, Vice-chairman, Evaluation of Coal for Coke Making W H. FULWEILER, Vice-chairman, Gas and Its Manufacture J. B. MORROW, Vice-chairman, Coal Preparation Bituminous Coal Production C. T. HAYDEN, Chairman R L ADAMS EUGENE MCAULIFFE HAROLD J ROSE WILLIAM H BLAUVELT H E NOLD D. A RUSSELL GEORGE W EVANS JAMES W PAUL CECIL W. SMITH JOHN A GARCIA GEORGE S RICE SAMUEL A TAYLOR H. S GEISMER W F RITTMAN F G TRYON FRANK HAAS J D ROGERS FRANCIS R WADLEIGH CHESTER M LINGLE

Jan 1, 1923

By L. B. Herring, Harold Decker

The area under discussion includes districts 2 and 4, so designated by the Texas Railroad Commission,‡ and comprises the following 26 counties: Bee, Brooks, Calhoun, Cameron, De Witt, Duval, Goliad, Gonzales, Hidalgo, Jackson, Jim Hogg, Jim Wells, Karnes, Kenedy, Kleburg, Lavaca, Live Oak, Nueces, Refu-gio, San Patricia, Starr, Victoria, Webb, Willacy, Wilson and Zapata. Drilling and Production The total number of wells drilled in this district during 1944 is shown in Table 5. This indicates a 41 per cent increase in all drilling over 1943. In spite of every handicap created by the war, the oil industry more than met the crisis in its drilling program in this district. Last year we thought it would be impossible to add to the total number of wells drilled in the previous yea;, but in spite of the lack of manpower and materials this large increase was shown. During 1944 this district produced 124,201,978 bbl. of oil from 11,607 producing wells, whereas in 1943 it produced 88,421,693 bbl. from 11,211 producing wells. This is an increase of 35,780,285 bbl. of oil. Some decline has been shown in the older fields arid undoubtedly the majority of wells in the district are producing at too high a rate. However, this district has been able to meet any demands made on it by the Petroleum Administration for War for increased production. Discoveries and Extensions There was a slight decline over the preceding year in the number of wildcats drilled, but the number of discoveries increased. In most instances subsequent development has not been sufficient to arrive at preliminary valuations but it appears that the over-all oil discoveries were below normal and that the gas discovcrics were relatively more important. The Canolis and Tijerina pools, Jim Wells County, and the Dan Sullivan pool, Brooks County, appear to be the outstanding oil discoveries of the year. No important oil reserve was discovered or developed in the Wilcox horizons, although considerable wildcatting was done. Important extensions were made at Agua Dulce and Stratton in Nueces and Teleberg Counties. Production was increased appreciably at Willimar, Willacy County, and Seeligson, Jim Wells County, in sands and areas which were apparently productive at the beginning of the year. Refining Most of the major work in the changing and completing of refineries was finished this past year. Some of the most modern refineries in the industry are now located in the Corpus Christi area. Gas and Condensate No new recycling projects were commenced during the year, nor were there any important additions to the old operations. No major gas reserve was developed, although several new discoveries suggest potentid possibilities.

Jan 1, 1945

By Roy W. Wright

Introduction The title of my paper is satisfyingly broad and allows me to touch lightly or dwell at length on virtually any aspect of mining, while endeavouring not to trespass on the subjects of other papers to be presented. However, at this stage in our world history when for the first time we are beginning to take conservation and the welfare of future generations more seriously, I want to concentrate mainly on the question of whether or not there will be the resources of minerals available to sustain mankind's progress in the generations ahead. Metals and the Population Problem The supply of raw materials is of course only one of the fundamental problems that will face future generations: if we assumed that the world population would continue to increase at the present explosive rate, then I believe we can say with certainty that other fundamental problems of much greater significance would arise long before a shortage of raw materials - or other substitutes -had any impact on the progress of mankind. Thus, I must start this paper with the assumption that some equilibrium in population will be arrived at before these other problems overwhelm the world. Will the Metals Run Out? At the 75th Anniversary Meeting of this Institute in March, 1947, Clinton H. Crane, President of St. Joseph Lead Co., prophesied that for the next 100 years there would be enough copper, lead and zinc for every essential need. He defined a need as essential where the qualities of the metal in that use were irreplaceable. Today, except for one or two cases such as lead in lead-acid batteries, few metals have qualities that cannot be provided either by another metal or by another material. It is more a question of what the engineer or manufacturer is prepared to pay for special qualities as compared with using cheaper materials and perhaps a less satisfactory design.

Jan 1, 1971

SINCE I promised you above when speaking of the melting of metals to teach you to make small crucibles and shells for melting, I do not wish to fail in my promise. For, in truth, since they are instruments that are much used for this procedure, they increase the work if they are not good, and often cause great extra expense as well as necessitating repetition of the work. If they are good they save everything. Therefore, if you have to make them, do it so that they, are greatly aided by art. It is first necessary to have the clay of a good nature, that is, resistant to the force of the fire by its own natural virtue, either when it is lean or when its viscousness is mixed with much talc, and whether it is yellow or white. This should be well freed from small stones and beaten well with an iron, and then thoroughly mixed by hand. With this should be mixed an eighth part of finely ground and sifted iron scale,* and also some [145] young ram's-horn ashes. These things should be well mixed together by hand and by beating them. If this clay should not be strong enough by itself, it is mixed with another lean clay, with crushed peperino, flintstone, or some other stone that in your judgment seems to be arid and resistant. Crucibles are worked on a low potter's wheel turned by hand, or on a high one turned by foot, just as plates are made. Both large and small ones are made. Most of them are given a triangular shape at the mouth, and the shells have a kind of spout for ease in pouring out the metal. This done they are well dried, and baked in furnaces like pots or other vessels. At the end, when they have been thus made they are used for melts.

Jan 1, 1942

By Herbert Wilson

THIS topic was discussed at the meeting in St. Louis in September, 1917, and at the meeting in New York in February last, but in the interval the war has accentuated in measurable degree the necessity for considering human relationship, not only as between nations, or in the treatment of our returning soldiers, but with respect to the relations between labor and capital in industry. It is my firm conviction that no other subject will have so large a place in industrial and political life during the next decade as this. Heretofore, the employer has been so engrossed with the financial, mechanical, and technical aspects of his business that he, has been willing to muddle through 'his relations with labor as best lie might and, on the other hand, the laborer has been so engrossed in his endeavors to secure a livelihood under whatever living and working conditions might be offered him that he has given little thought to his relations to his employer, until some misunderstanding has ended in disagreement and strike. No thinking man doubts that were the machinery available for friendly, personal, face-to-face consideration of the problems confronting employer and employee, there would he fewer disagreements, fewer strikes, and a better and more settled industrial situation. The necessity for some such medium for exchange of views has resulted in the organization of labor and, in some measure, of capital. Each party, engrossed only in defending its own viewpoint, has generally tried to gain its point by might rather than by right. Gradually, however, the representatives of both elements are beginning to appreciate that when the machinery for bringing them together in friendly communion is available their differences frequently settle themselves. There remain yet vast numbers of employers and of employees who are not organized and to whom the opportunity of friendly discussion of differences is not available; for these the machinery should he provided.

Jan 1, 1919

By Arthur Notman

THE matters I had intended to present to you ap-peared in the March 12 issue of Engineering and Mining Journal over the signature of George J. Young, so that although I should like to talk to you for about three hours on this subject, unfortunately it has all been done before. The subject originally sug-gested to me was the trend in mining methods. You will find that fully set forth much more clearly than I could hope to do, in Mr. Young's article, so that I shall confine my attention to a few points of interest in specific cases. You are undoubtedly familiar with the problem that was presented to the Miami Copper Co. when they had exhausted their so-called high-grade orebody. They had what appeared to be a large tonnage of material which their preliminary development work and such drilling as was done indicated contained one per cent copper or a-little over, and how to mine that profitably by underground methods was the question. It was somewhat complicated by the fact that the nature of the ground made them doubtful of their ability to cave it successfully. It was unquestionably harder ground than that of the more highly mineralized sections of the Miami and Inspiration- ore zone which had been mined. However, they had kept very accurate and complete records of past accomplishments and knew what they had to work with and what modifications with respect to costs would be necessary in order to solve this problem. Under the old method of working, they were extract-ing about 71/2 tons per man employed in the mining department; that is to say all labor, direct and indirect required to put the ore in the mill bins, and this, with the grade of ore which they had, resulted in a satis-factory financial outcome. Under their modified method now in use, they have raised that output per man to 29 tons per man shift. That is almost four times what they were doing with the old method.

Jan 4, 1927

Prof. HEnRy Louis, Newcastle-upon-Tyne, Eng. (communication to the Secretary*):—I welcome Mr. Hammond's paper as an attempt to give definiteness to the best modern professional practice. Such a codification of our professiollal ethics is urgently needed, seeing how widely the views of nlining engineers direr on some of the points raised; for example, I have no hesitation in performing a class of work, as to which Mr. Hammond seems to entertain some doubts, and, on the other hand, I strongly condemn a practice which he appears to recommend. I have not the least hesitation in making reports for vendors of mining-properties, and am constantly doing so; the best justification for this practice may be found in the fact that such reports have been repeatedly accepted by buyers as giving a correct representation of the facts of the case, which is all that should be demanded from any report. On the other hand, Mr. Hammond advocates that mining engineers should take payment for their reports in shares of a company to be floated upon the basis of such reports. I hold that this is ethically wrong, as even themost honest of men is liable to be unconsciously biased under these conditions. Indeed, I go much further, and maintain that a mining engineer who reports or advises upon mining-properties should never hold any mining-shares at all, or be himself interested in any mine, and this has been my consistent practice for many years. A man who hold shares in a mine, and is called upon to report upon a neighboring property or a similar mine, can never be wholly unbiased; and even if he could be, he would always lay himself open to the suspicion that he was giving a favorable report 80 as to enhance the value of the property in which he himself is interested, or an unfavorable report so as to stifle competition. It is quite as bad for the manager of a mine or the consulting manager to be interested, because he will have access

Jan 1, 1910

By L. W. Bahney

The photograph, Fig. 1, shows the apparatus a little less than half size, consisting of a filtering-flask fitted with rubber stopper through which passes a bent glass tube, and an extraction-thimble fitted with rubber stopper through which passes a glass tube of 0.25-inch bore. Both tubes are connected by a short piece of rubber tubing. A section of a thimble is shown in the photograph ; the tube extends to within & in. of the tapered end. The object of using the thimble is to remove the acid from the beaker after all the copper has been precipitated. Time is saved, the copper is not exposed to the acid alone, and there are none of the losses attending ordinary filtration. I have accomplished these results by means of a piece of perforated platinum fastened in the end of a (0.25-in. bore glass tube and a filter-mat of asbestos, but after my supply of proper length fiber became exhausted I could not replenish it even after purchasing 14 lots from four different dealers. The above apparatus may be used to remove at least seven-eighths of a supernatant liquid from a settled precipitate without disturbing the latter. The application of the thimble is best shown by partly outlining the assay for copper, as follows: Dilute the acid solution of copper and other sulphates to 150 cc. in a 200-cc. Jena beaker, place on a hot plate, add 2 drops of concentrated HCl, then place a strip of aluminum in the beaker (this may be bent or straight, as desired). Connect the apparatus, as shown in Pig. 1, with a filter-pump having a strong suction. When the copper is precipitated, remove the beaker from the hot plate and insert the extraction-thimble alongside the strip of aluminum. The acid solution will be drawn through the porous tube. Wash the upper end of the aluminum strip with a jet of hot water, wash down the sides of

Jan 1, 1913

TO THE BOARD OF DIRECTORS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen:-The following report covers briefly some of the more important activities of the Institute during the year 1923. In my report for the year 1922, I drew attention to the falling off in membership of the Institute due to the depressed condition of the mining industry in several lines and the inability of many of our members to find profitable employment in mining or its associated branches. A number who were unemployed during 1922 established connections during 1923, but a still greater number have been forced to resign or drop their membership during 1923. Fortunately, the number dropped is not so great as in the previous year. The Employment Service conducted by the four Founder Societies bears witness to the trend in business. For the young men just out of college, there are plenty of opportunities at small salaries, there are plenty of opportunities for them as laborers; but for the mature members, those of experience, there are few calls. During the last eighteen months, our Employment Service has been able to place only six of our members out of every hundred engineers for whom it has found work. Another loss which this Society has suffered, but which is not felt so keenly by our sister societies, is in its foreign members. The A. I. M. E. has always had a large foreign membership, but of recent years exchange has been so heavily against many European and South American countries that a large number of members residing abroad have been compelled to relinquish their membership. Almost invariably these members express keen regret because of the necessity that confronts them, and almost invariably the writers express hope that present conditions will not last long and that they will soon be able to ask-for reinstatement. Having stated the darkest side of the picture first, it may now be drawn to your attention that in spite of these losses the number of persons applying for membership was decidedly encouraging.

Jan 2, 1924

By Gordon W. Hodgson, Edward Tipman

INT'RODUCTION An appreciable number of the oil fields in Western Canada are accumulations of heavy black oils in more or less unconsolidated sandstones. When the crude oils are produced by conventional means, they are frequently contaminated with both sand and oilfield water. The water is usually present as emulsified water, and the sand and other solid materials are suspended in the emulsions. The presence of the solid material in the crude oils is troublesome and, in general, little is known about the behavior of suspended solid particles in emulsions. The Stokes equation describes the behavior of suspended particles in homogeneous fluids in terms of particle size, density differential, and fluid viscosity. In the case of an emulsion, particle size and density differential introduce no difficulties, but considerable doubt centers around the viscosity term. It has been reported1 that the viscosity of an emulsion is related to the viscosity of the continuous phase by an expression of the type: n = a, (1 + a C) where n is the viscosity of the emulsion, n,, is the viscosity of the continuous phase, a is a constant, C' is the volume concentration of the disperse phase. The value of 17, the coefficient of the concentration term, has been determined for various systems, and has been found to vary from a value of 1 to 4.75. The value of 2.5 has been found to be applicable to a large number of systems, and this is the value that is widely used in the equation which then becomes the Einstein equation for the viscosity of emuls~ons. It is of considerable significance that neither the particle size nor the viscosity of the disperse phase enters the expression; the expression for the viscosity of the enlulsion is based solely upon the viscosity of the continuous phase and the concentration of the disperse phase. For crude oil emulsions the Simha equation and the data presented by Fukushima and lchimurai show a non-linear dependence of the viscosity ratio on the water concentration. While it is undoubtedly reasonable to use these data for predicting the viscosity of a specific emulsion, and while it is equally reasonable to expect the calculated viscosity to predict the settling rate of a solid spherical particle in the emulsion by means of Stokes equation, there seems to be no direct evidence that this calculation is indeed sound for describing the settling rates of solid particles in emulsions of water in crude oils. PROCEDURE A direct approach to the problem was thus indicated. Laboratory equipment was designed and built for the direct determination of the rate-of-fall characteristics of solid particles in emulsions of water in oil. Although the apparatus incorporated the basic design of conventional falling-ball viscometers, the study was concerned directly with the rate-of-fall characteristics of particles in emulsions, rather than with the viscosity of the emulsions as such. The crude oil used in this study was a very heavy black crude oil—the McMurray oil obtained from oil-soaked sands outcropping on the Athabasca River in northeastern Alberta. It was produced from the sands by strip mining followed by hot-water separation of the oil in the separation plant of the Alberta Government at Bitumount'. The primary plant product was a wet crude oil containing about 5 per cent solids and 35 per cent water. The final plant product was only slightly different from the native oil, having lost only about 4 per cent of its bulk as light ends during dehydration distillations. In the present investigation two kerosene dilutions of the McMurray oil were used in addition to the dry plant product. The McMurray oil contained 1.92 per cent solids. Analysis of the solids by X-ray diffraction showed the presence of kaolinite, pyrite, and illite as major constituents. with lesser amounts of quartz. Particle size of the pyrite and quartz was less than 10

Jan 1, 1957

By A. G. Roach

THIS paper deals with a plant built under joint agreement between the Canadian and United States Governments to supply the strategic mineral, corundum, at a time when African production was dwindling and war demands still increasing. The operation began in September 1944, retreating the tailings from a former mill by gravity methods, and is still in production (Sept. 1946). In 1942, when it became apparent that South African production would be insufficient to meet mounting wartime requirements of corundum, a survey was made of Canadian sources of the mineral, at the request of the Foreign Economic Administration of the U. S. Government. The investigation1 indicated that the quickest and cheapest supply would be obtained by reworking the tailings deposit at Craigmont, Ontario. Sampling of the dump by Canadian Government engineers revealed that 125,000 tons of tailings, averaging 2.96 pct corundum, was available for retreatment. Ore-dressing tests on representative samples of the deposit were conducted by the writer in the laboratories of the Industrial Minerals Section of the Department of Mines and Resources at Ottawa; and gravity concentration on tables was indicated as the most suitable method of treatment. Decision to proceed with the project was deferred until May 9, construction was begun on May 18, and tune-up operation of the plant begun on Sept. 15, 1944. CORUNDUM-ITS PROPERTIES AND USES Corundum is an oxide of aluminum having the formula A1203. Its outstanding characteristic is its great hardness; 9 in the Mohs scale. In this respect it is second only to the diamond. It usually occurs in barrel-shaped crystals in nepheline syenites and other feldspathic rocks deficient in silica. It has a specific gravity of 3.95 to 4.1 and is insoluble and infusible. In color it ranges from white, through red and green, to black. Ruby and sapphire are gem varieties of corundum. Corundum is supplied to industry as closely graded grain.2 The coarser products (10 to 24-mesh) are used largely for snagging wheels in the steel-castings industry, while the finer grades (from 70-mesh down to flours) find a wide application in the polishing of lenses and for other uses in the optical trade. All sizes of corundum grain are in close competition with synthetic abrasives such as carborundum and alundum. In some fields of application the artificial product is superior to the natural grain but not in all. The shape of the particle and its behavior under conditions of actual use determine its sphere of employment. The United States is the largest consumer of corundum, annual consumption in peacetime approaching 3000 tons; during the war this figure was roughly doubled. During the years 1902 to 1913, the bulk

Jan 1, 1946