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By Jos. J. Walsh

Ventilation within a coal mine is essential to the welfare of those employed therein, from the standpoint of health, safety, and efficiency. While the saving of life and the preserving of health are the chief reasons for ventilation, efficiency and production are increased. In spite of the fact that we speak of air as having a certain composition, the proportions of oxygen, nitrogen, and carbon dioxide are not fixed, but vary between small limits. The different elements are not chemically united, they are merely mixed and each is free and can be separated with little energy. For this reason air in the mine workings is seldom found in a pure state. Factors that necessitate ventilation in coal mines are those that change the composition of pure air. Contamination of mine air results from the burning of oil-fed flames, the use of explosives, the oxidation of coal, and the liberation of gases by the coal. The extent to which these factors exist governs the size and general plan of the ventilating applianccs required. An efficient ventilating system is one that will furnish air at the working faces in sufficient volume to dilute and render harmless noxious gases and at the same time maintain an oxygen content closely approaching that of pure air. In a well-ventilated mine, the oxygen seldom falls more than 0.5 per cent. below normal. The carbon-dioxide content of the air in the average coal mine will vary from 0.1 to about 0.8 per cent., which amounts are not harmful. Three per cent. of carbon dioxide in air doubles the frequency and the depth of breathing; it is plainly noticeable and if breathed continuously for several hours its effect would probably be harmful. Slight reductions in the oxygen content of the air, such as occur in well-ventilated mines, have no debilitating effect on the worker. A person not exerting himself would fail to observe any unusual physical effect in an atmosphere: containing 17 per cent. of oxygen. This condition, however, or even a condition showing an oxygen content below 20 per cent., would indicate poor ventilation and that the elements which tend to reduce the efficiency of the worker are present, namely water vapor and a high wet-bulb temperature.

Jan 1, 1923

The passing of Benjamin Bowden Lawrence in January, 1921, was a distinct loss to the engineering profession. Mr. Lawrence had a genius for reviving abandoned mines and developing them into substantial producers. A notable example of his work in this line was the Dives-Pelican near Georgetown, Colo. While on an exploring expedition in 1888, he examined this old mine and was convinced that bonanza ore still existed there. He located the owners of the property, and induced them to place sufficient capital at his disposal to enable him to re-open and explore this mine. So confident was he of the outcome that he undertook this work on a profit-sharing basis without salary. Within eighteen months the old Dives-Pelican was operating profitably, and for the following ten years it paid very substantial dividends. The late Theodore N. Vail was one of the owners of this old mine, and many years later, at a dinner given to Mr. Lawrence by the Alumni of Columbia University, Mr. Vail told the story of the resuscitation of the Dives-Pelican by Mr. Lawrence, and declared that the dividends he himself had received provided a large part of the funds that made possible the realization of his dream of establishing the long-distance telephone in this country. The E1 Cobre mines at Santiago de Cuba also owed their renewed life to Mr. Lawrence. Under his management, these mines produced and shipped several million pounds of copper per year. He was for several years consulting engineer for the Kerr Lake and other silver mines in the Cobalt region; the Kerr Lake became famous as a silver producer. Mr. Lawrence spent more than twenty years of his life in the mining camps of the West. He was but twenty-one years of age, and only a few months out of college, when he was appointed manager of the great Chautauqua Lode (a silver mine) located on Glacier Mountain near Montezuma, Colo. Here, isolated in the mountains for several months each year by ice and snow, he worked for five years to make these mines Pay. He possessed unusual breadth of vision and human understanding; he had ''personality plus," and when he opened an office in New York City as consulting engineer he quickly rose to an enviable position in his profession. Young engineers worked with enthusiasm under his guidance. He carefully selected his men, discussed fully with them the plans and policies to be pursued, then left them free to accomplish results in their own way. This attitude developed individuality and resourceful-

Jan 1, 1922

By Charles A. Mitke

Discussion of the paper by CHARLES A. MITKE, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 105, September, 1915, pp. 1941 to 1958. GERALD SHERMAN, Bisbee, Ariz.-Mr. Mitke justly might have made much stronger his claim for increase in efficiency of labor due to the introduction of forced ventilation. The product per man shift in stoping in the Gardner division has practically doubled. While it is true that improved methods have been responsible for a great part of this gain, and what is due to better ventilation cannot be definitely known, yet it is also true that the results could not have been obtained in that division as it was in 1912. . The paper discusses the two systems of ventilation in use, exhaust and pressure. In both the object is the same, to take foul air or gas out of the mine by the most direct course and replace it by fresh. In coal mines, the exhaust system is in almost universal use, and since the most advanced work in ventilation has been in that class of mines, it was naturally the first one to be considered. It has the advantage of leaving all adits, shafts, or other openings free for use. Doors are only needed to direct the course of the air, and not to confine it. Its disadvantages appear in case of fire, or if the ground over the mine is much broken by subsidence. The fan must work in gas in the case of a -fire, and may be. damaged or destroyed either by heat or by corrosive gas. At the time of the fire in the Lowell division of the Copper Queen, a small exhaust fan was placed over a ventilating raise, but the vanes and housing were destroyed by sulphurous gases within a few weeks. If the ground above the mined area is much broken, as is frequently the case when the ore deposit is thick vertically, a good deal of air is likely to pass through it, particularly if it is near the surface. Leakage from this source is a loss to the exhaust system by short circuiting, which is exaggerated by a contraction or block in the air course. It serves as an added outlet in the pressure system. This is strikingly shown at the United Verde, where many jets of steam may be seen coming up through the ground above the stoped country on a cold day.

Jan 12, 1915

By Gerald Edmunds

IN a paper1 before this Institute in 1940, the writer reported that the surface orientation texture of zinc and cadmium differed from the texture existing within the casting, in that basal planes were parallel to the surface. He was unable to rationalize the origin of this surface texture. It is conceivable that the surface orientation texture is influenced by the atomic force fields, which are different at the surface and within the body of metal. It was considered that a radical change in the surface against which the metal is cast might alter the surface texture. In trial of this, zinc has been cast against a surface of molten lead, but the same result has been obtained-i.e., (001) parallel, ±20°, to the surface-as was obtained when it was cast against air, Transite or iron.1 Into the bottom of an open cast-iron tray, 7 by 14 in. by 2 in. deep, preheated to about 275°C., about ¼ in. of lead, then) ½ in. of zinc was poured, and the whole was covered with an electric heater to enforce freezing from the bottom upward. After a lapse of time sufficient for the zinc but not the lead to solidify, the zinc slab was raised free of the molten lead. The bottom surface of the zinc casting was coated with a thin layer of lead. A specimen of the slab 1 ½ in. square was metallographically polished to flatten it and remove the slight film of lead, and the orientation was determined by the method used before,1 with the result stated above. Some determinations have also been made on other metals, as follows: Surface orientation determinations were made on the 3/8-in. diameter grip section of two ¼ -in, diameter aluminum-alloy die-cast tensile bars and on a 1/8 by ½ -in. flat aluminum-alloy die-cast tensile bar. None of these three aluminum die castings exhibited any preferred orientation at-the surface. A brass die casting (nominal composition: 60 Cu, 37.75 Zn, 1.00 Sn, 1.00 Pb, 0.10 Al, 0.15 Si) furnished by C. S. Smith was also examined. The surface showed a random orientation of alpha and beta. SUMMARY A zinc casting solidified against a molten lead surface was found to have the same surface orientation texture, (001) parallel to the surface, as other zinc and cadmium castings. Aluminum and alpha-beta brass die castings were found to have random grain orientation textures at the surface. ACKNOWLEDGMENT The X-ray determinations were conduced by M. L. Fuller.

Jan 1, 1945

By C. Y Garber

Interest in the sink-float plant operated by the Bunker Hill and Sullivan Mining and Concentrating Co. at Kellogg, Idaho, has recently been largely confined to the preparation and reconditioning of the galena medium. The ease and simplicity of these operations in a concentrating mill producing a flotation lead concentrate has occasioned enough comment to possibly justify a brief description. The subject is treated from an operator's viewpoint only; no effort is made to discuss it in a theoretical or technical manner. Plant at Bunker Hill The sink-float plant was first operated in December 1941. It was built for the purpose of quickly increasing mill capacity with a minimum of equipment. It is the Huntington-Heberlein sink and float process using galena medium and is operated under license from the Sink and Float Corporation, New York city. Lead-zinc ore from the Bunker Hill mine is crushed to pass a 1¼ in, screen and is then washed and separated on vibrating screens having 4½-mm. round-hole punched plates. The screen under-size, amounting to 33 per cent of the mill feed, is dewatered and sent to the ball-mill feed bins. The screen oversize goes to the sink-float plant, where 50 per cent of the oversize, or 33 per cent of the mill feed, is float, which is washed free of medium and disposed of as a tailing. The remaining 33 per cent is sink, which, after washing, is crushed to pass 36 in. and joins the under-size in the ball-mill feed bins. The normal plant capacity is 1700 tons per 24 hr. About 1.7 per cent of the total lead and 3.3 per cent of the total zinc in the feed is lost with the sink-float tailings (Table I). More complete descriptions of the H. H. process and Bunker Hill sink-float plant are given in several recent articles, listed at the end of the paper. Preparation OF Medium at Bunker Hill New medium is made intermittently as needed, usually 12 hr. in each 6 days. A small portion of the current mill flotation concentrate is diverted from the lead cleaner cells to a I-in. vertical sand pump and pumped to a two-cell 36-in. Agitair flotation machine, where NaCn and ZnSO4 are added and the grade of concentrate is improved as shown in Table 2. Tailing from this operation is returned by gravity

Jan 1, 1947

By R. S. McCaffery, D. E. Krause

There has been some discussion among blast-furnace operators regarding the relative merits of tuyeres of the converging type and tuyeres designed in an attempt to produce a diverging jet of air. An article1 on Progress in German Blast Furnace Practice indicates the interest in this subject abroad. This article illustrates a diverging type of tuyere which is shown here in Fig. 1A. The design appears to be rather poor as regards known properties of air flow. The adoption of this tuyere, the arlicle states, resulted in a decrease of blast pressure of about 4 Ib. per sq. in. and an increase of the output of the furnace. If the improvements mentioned are due entirely to the change in tuyere design, the subject of tuyere design seemed worthy of investigation and this paper is a report of such work. Because of the gain in efficiency brought about by the use of a diverging tuyere in the German plant, it was thought desirable to investigate the shape of the air streams issuing from various types of tuyeres to ascertain whether the gain was due to the tuyere itself or to the distribution of the air in the furnace. Since it is difficult to do experimental work on a full-sized furnace, or even on full-sized tuyeres, and because of the equipment available for the work, it was decided to carry out the work on scale models of tuyeres. Therefore, in this work, single tuyeres were used and the blast discharged into the atmosphere. The shape of the air stream was determined by means of a Pitot tube suitably supported in the air stream at various positions. The air was furnished by a Roots blower driven by a 10-hp. direct-current motor having field control, and capable of discharging 250 cu. ft. per min. with a pressure on the discharge of 4 in. of mercury. A modern blast furnace with 21-ft. hearth requires about 50,000 cu. ft. per min. of free air at from 16 to 23 Ib. per sq. in. pressure, depending upon the type of burden. This pressure is the total pressure required to force the air through the burden and through the tuyeres. Upon computation the pressure drop through the tuyeres is about 1 to 2 lb. per sq. in. By making the tuyeres to a one-fifth scale, and by using a pressure of 1.5 in. of mercury, the shape of the air streams should be

Jan 1, 1931

THERE can be little doubt in the mind of anyone of the great interest which has been provoked in the mining and petroleum industry by the com-paratively new geophysical methods of prospecting, after the sessions at this year's meeting of the Institute. Not only were the sessions very well attended but every¬one seemed most attentive. Although the discussion was somewhat limited in general, that may well be at-tributed to the newness of the subject. Two sessions on this subject were planned originally, but these gave insufficient time for the presentation of all the papers prepared and a third session was abso-lutely necessary. The first meeting dealt entirely with the gravity methods and was completed in the scheduled time owing to the fact that but two of the five papers listed were read. The second session was devoted to magnetic and electrical methods, the completion of which had to be carried over into the third period of geophysics. The first session on geophysical prospecting, and in-cidentally the first scheduled Institute meeting devoted entirely to this subject, was most appropriately opened by E. L. DeGolyer, the chairman of the session. It was through the efforts of Mr. DeGolyer that the first gravity work, as applied to prospecting, was under-taken in this country. Again most appropriately, the first paper presented was given by Donald C. Barton, who carried on the first work with the Eötvös torsion balance in America and aided materially in its development. A subject, the theory of which is so difficult to understand as it is generally presented, was so clearly illustrated and ex-plained by the speaker that even a novice could grasp the fundamentals. Dr. Barton, in showing actual re-sults obtained in torsion balance surveys with the in-terpretation of the sane and later drilling records, was free in stating that there are many limitations to the field in which this and the other geophysical instruments may be successfully employed. This paper called for considerable discussion relative to the application of the torsion balance to gravity surveys over various types of structures. During the course of this discus-sion a very important point was emphasized by the chairman, namely, that for successful application of any or all of the scientific methods of prospecting, a back-ground of experience is absolutely necessary to serve as a basis for further work. This can only be secured by contributions from the results of actual prospecting work.

Jan 3, 1928

The following is available free of charge from the Bismuth Institute, rue Brederode 9, B-I000 Brussels, Belgium: The chemical analysis of bismuth. Automatic methods of guiding welding heads along butt joints. Investigations into lamellar tearing. A technical survey of seam tracking methods in welding. Review - Seawater corrosion handbook, by M. Schumacher (editor). New Jersey, Noyes Data Corporation, 1979. New journal February 1979 marked the appearance of a new monthly journal, Lloyd's Shipping Economist. New edition Gasification of coal, a basic study of existing processes and new developments, by H. D. Schilling, B. Bonn, and U. Krauss (edited by W. Peters). Essen (West Germany), Verlag Gltickauf GMBH, 1979. 2nd revised edition. 336 pp. 68DM (approximately R32). In German. South African technikons The six autonomous colleges for advanced technical education in South Africa were established in terms of the Advanced Technical Education Act (Act 40 of 1967). However, since the inception of these colleges, it has become clear that members of the public find the name difficult to use and to remember. Consequently, these colleges, which play such an important role in the community, were not always correctly identified. Die forging The 9th International Conference on Die Forging will be held from Monday, 4th to Saturday 9th May, 1981, in Diisseldorf, Federal Republic of Germany. It is being organized jointly by the Forging Committee of the Verein Deutscher Eisenhiittenleute and the Vereinigung Deutscher Freiformschmieden. High-temperature alloys An International Conference on the Behaviour of High Temperature Alloys in Aggressive Environments will be held in Petten (North-Holland) from 15th to 18th October, 1979. Strategic minerals The National symposium on the availability of strategic minerals, which is being organized by the Institution of Mining and Metallurgy in collaboration with the Fellowship of Engineering, will be held at the London Press Centre, New Street Square, London EC4, on 20th and 21st November, 1979. The symposium has as its main objective consideration of those minerals that may pose problems of availability in the United Kingdom. Underwater mining The 10th Annual Underwater Mining Institute is scheduled for 1st to 3rd October, 1979, at Galveston, Texas. The Institute will be cosponsored by the Sea Grant College Programs of the University of Wisconsin and Texas A & M University and by the Marine Science Institute of the University of Texas it is being held in co-operation with the Association for Marine Mining. Die Suid-Afrikaanse Instituut Vir Mynbou En Metallurgie - Inligting Oor Lidmaatskap.

Jan 1, 1979

By C. Y. Garber

Interest in the sink-float plant operated by the Bunker Hill and Sullivan Mining and Concentrating Co. at Kellogg, Idaho, has recently been largely confined to the preparation and reconditioning of the galena medium. The ease and simplicity of these operations in a concentrating mill producing a flotation lead concentrate has occasioned enough comment to possibly justify a brief description. The subject is treated from an operator's viewpoint only; no effort is made to discuss it in a theoretical or technical manner. Plant at Bunker Hill The sink-float plant was first operated in December 1941. It was built for the purpose of quickly increasing mill capacity with a minimum of equipment. It is the Huntington-Heberlein sink and float process using galena medium and is operated under license from the Sink and Float Corporation, New York city. Lead-zinc ore from the Bunker Hill mine is crushed to pass a 1¼ in, screen and is then washed and separated on vibrating screens having 4½-mm. round-hole punched plates. The screen under-size, amounting to 33 per cent of the mill feed, is dewatered and sent to the ball-mill feed bins. The screen oversize goes to the sink-float plant, where 50 per cent of the oversize, or 33 per cent of the mill feed, is float, which is washed free of medium and disposed of as a tailing. The remaining 33 per cent is sink, which, after washing, is crushed to pass 36 in. and joins the under-size in the ball-mill feed bins. The normal plant capacity is 1700 tons per 24 hr. About 1.7 per cent of the total lead and 3.3 per cent of the total zinc in the feed is lost with the sink-float tailings (Table I). More complete descriptions of the H. H. process and Bunker Hill sink-float plant are given in several recent articles, listed at the end of the paper. Preparation OF Medium at Bunker Hill New medium is made intermittently as needed, usually 12 hr. in each 6 days. A small portion of the current mill flotation concentrate is diverted from the lead cleaner cells to a I-in. vertical sand pump and pumped to a two-cell 36-in. Agitair flotation machine, where NaCn and ZnSO4 are added and the grade of concentrate is improved as shown in Table 2. Tailing from this operation is returned by gravity

Jan 1, 1947

Discussion of the paper of Frederick W. Apgar, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 7S, June, 1913, pp. 1011 to 1022. L. C. GRATON, Cambridge, Mass.:-I presume I am one of the few who are exceedingly interested in microscopic work, and I am sure we have all enjoyed this paper very much. I will not attempt to express my own feelings in regard to it beyond saying that it seems to me that this sort of investigation and study has been overlooked and slighted, and its possibilities are very great. There are one or two, details which impressed me, because they were novel to me, and one was the development of secondary galena with dull luster. I have never seen any galena which seemed to be secondary, and have never seen any that was secondary or primary that did not have a bright luster. KIRBY THOMAS, New York, N. Y. (communication to the Secretary *) :-The present-day mining engineer is expected to " see into the ground farther than the point of the pick " and he is justified in making free claim to his ability to do so. Mr. Apgar has recorded the development of the application to the work of the engineer of a very useful but tardily recognized instrument-the petrographic microscope, an instrument which is helping to shatter the proverbial "point of' the pick" limitation-and he has shown its use and its possibilities very clearly. Some further field examples of the use of the microscope in engineering problems may add to the appreciation of Mr. Apgar's scholarly paper. In exploration by diamond drills in the Sudbury, Ontario, nickel district it is often of great importance to determine when the drill has passed out of the norite and into the foot-wall formation. Structural calculations may give a clue to the expected point of contact, but the variations are considerable, and, since to stop the drill before reaching the contact is futile, and too continue beyond it is needless, it becomes of theoretic and economic importance to determine positively the lithological nature of the corer at critical stages in the work. In some places the foot-wall is an earlier norite, only distinguishable from the nickel norite (Sudbury-: ite), by means of an examination of the rock slides with a petrographic; microscope. Again, certain diabase dikes which cut the norite and. the foot-wall formations cannot be easily or with certainty distin-

Jan 11, 1913

Without having asked for it, the writer has apparently been drawn into the discussion regarding relative hoisting capacities which was started by Woodward Iron, egged on by Joe Haller of Cleveland-Cliffs [Mining Engineering, August p. 642] and Axel Kjelgaard [November p. 919], who took exception to Mr. Haller's remarks of tonnage hoisted and avers that they do better in Sweden. It does not appear to the writer that Mr. Haller was inclined to refer to the tonnage hoisted at Cleveland-Cliffs in a manner to imply that they claimed any hoisting record, but rather as a statement that they had hoisted a certain amount of ore during the year 1950. Mr. Haller has been in the mining game long enough to appreciate what Mr. Kjelgaard did not apparently take into consideration, that length of haul, shifts hoisted, nature of ore, method of loading and the many other factors which influence the hoisting cycle make a comparison of tonnages hoisted of two given mines almost an impossibility. Mr. Cheyette sent you .a copy of his letter to Bob Manegold relative to the capacities of the Orient #2 mine. There are several mines around the Country which constantly set up records about which little or nothing at all is ever heard. We cite the Snow Hill Coal Co. mine at Terre Haute, Ind., which has an automatic Nordberg hoist and which hoists 12 tons per trip or 700 tons per hr from 700 ft. This is a counter-weighted installation and a complete cycle is made every 62 seconds or 58 trips per hr. Another mine, The Potash Company of America mine at Carlsbad, N. Mex., has a Nordberg automatic hoist, hoisting eight tons per trip from 1150 ft on a one minute cycle. The materials hoisted in these two mines are ideal for automatic hoisting-they are free flowing so that no hang up is anticipated and hoisting is continuous. Multiplying out the above figures you will find that it is possible to hoist 11,000 tons in two shifts at Snow Hill or over 3 million tons in 300 days per year and over 2 million tons at Potash. Other mines have records which can be pointed to with pride. When a record for one year is established, it doesn't stand too long as here in America the ambition of all the men connected with the operation forces them on to larger tonnages. T. C. WIEDENHOEFER MANAGER MINE HOIST DEPARTMENT NORDBERG MANUFACTNRING CO. MILWAUKEE, WIS.

Jan 1, 1952

The passing of Benjamin Bowden Lawrence in January, 1921, was a distinct loss to the engineering profession. Mr. Lawrence had a genius for reviving abandoned mines and developing them into substantial producers. A notable example of his work in this line was the Dives-Pelican near Georgetown, Colo. While on an exploring expedition in 1888, he examined this old mine and was convinced that bonanza ore still existed there. He located the owners of the property, and induced them to place sufficient capital at his disposal to enable him to re-open and explore this mine. So confident was he of the outcome that he undertook this work on a profit-sharing basis without salary. Within eighteen months the old Dives-Pelican was operating profitably, and for the following ten years it paid very substantial dividends. The late Theodore N. Vail was one of the owners of this old mine, and many years later, at a dinner given to Mr. Lawrence by the Alumni of Columbia University, Mr. Vail told the story of the resuscitation of the Dives-Pelican by Mr. Lawrence, and declared that the dividends he himself had received provided a large part of the funds that made possible the realization of his dream of establishing the long-distance telephone in this country. The E1 Cobre mines at Santiago de Cuba also owed their renewed life to Mr. Lawrence. Under his management, these mines produced and shipped several million pounds of copper per year. He was for several years consulting engineer for the Kerr Lake and other silver mines in the Cobalt region; the Kerr Lake became famous as a silver producer. Mr. Lawrence spent more than twenty years of his life in the mining camps of the West. He was but twenty-one years of age, and only a few months out of college, when he was appointed manager of the great Chautauqua Lode (a silver mine) located on Glacier Mountain near Montezuma, Colo. Here, isolated in the mountains for several months each year by ice and snow, he worked for five years to make these mines Pay. He possessed unusual breadth of vision and human understanding; he had ''personality plus," and when he opened an office in New York City as consulting engineer he quickly rose to an enviable position in his profession. Young engineers worked with enthusiasm under his guidance. He carefully selected his men, discussed fully with them the plans and policies to be pursued, then left them free to accomplish results in their own way. This attitude developed individuality and resourceful-

Jan 1, 1922

By Andrew Allen

WHEN a mine is changed from hand, to me-chanical loading, the character of the coal dumped at the tipple is changed in many ways. Selective mining is not so easy with mechanical load-ers, and where much picking is done at the face it is apt to be wasteful anyway. Much recoverable coal is apt to be lost by too free gobbing and, in my opinion, picking at the face should be confined to removal of heavy rock, such as pieces of roof or bottom or sulfur balls. and to such clearly defined and persistent bands as can be readily recognized and segregated. With mechanical loaders of the shovel type, even this amount of gobbing is almost impossible. When coal is shoveled into a conveyor there should be no difficulty in doing as much picking as now by hand loading. The size of lumps may be greatly increased, on ac-count of the ease of handling them with a shovel, as the miners will not break them up in order to lift them into cars. Fines may be increased. This is, of course, not universally true, yet it is my opinion that a shovel breaks the coal more, as a rule, than hand loading. This might not be true with all types of shovels and is cer-tainly not true with a conveyor, either with or without the "duck-bill." The average car load will be greatly reduced in fields such as Illinois and Indiana, in which it is the practice to build up the coal above the sides. Where "level full" regulations prevail there should be no material change. When the coal comes to the tipple these differences usually result in the discovery, that many changes are necessary in the preparation plant. The increase in the percentage of fine sizes will probably not bother the screen, but may overload the conveying apparatus. The larger size lump may clog the chute, but as a rule the efficiency of the sizing screens is not greatly affected. In one completely mechanized mine the proportions of 6-in. lump and 2-in. screenings, when loading by hand, were 16.9 and 51.3 per cent respectively. When loading mechanically, these proportions changed to 15 per cent lump and 53.5 per cent screenings. The picking force on the tipple has been increased from 14 on hand loading to 33 men on mechanically-loaded coal. This is for an output of about 5000 tons.

Jan 4, 1927

By George W. Bain

The good work of the surveys supported by the different branches of the government needs little mention to geologists but is underappreciated by people at large. Geologists and engineers realize their usefulness and yet even from this group one hears occasionally an undercurrent of discontent about their work or the distribution of it. The very fact that discontent arises within and without this group and has drawn attention of legislative bodies of the country in the present time of stress means that a large number of people do not receive or do not realize that they receive benefit from these public works. This seems to be a clear indication that more than the relations between government surveys and the mining industry is involved and that if the mining industry is interested in continuation of the work of these surveys on the past scale they must consider the other survey divisions and their activity. Also, relations between government surveys and certain specialized types of mining have not been as close as they should be. I have been employed in almost the entire range of fields offered to geologists and have studied closely the feeling of people towards geological service. Recently it has been a pleasure to be closely associated with men who were as deeply interested in civic welfare and affairs of state as in the financial success of a large industry developing natural resources. Previously I had seen service in a national survey, a state survey, summer employment by a large mining company exploring new property and detailed geological work for a large corporation. Major responsibility as a college instructor has left me free to view each of these assignments in unprejudiced fashion and at the same time study the relation of government surveys to large natural resource industries, average industrial and construction work and service to nongeologists and laymen. Considerations Governing Geologic Public Service Three groups of people must be satisfied by the surveys if dissatisfaction is to be dispelled. First there is a large group of people who pay taxes to support the government activities and must receive some service

Jan 1, 1935

By Alwyn Birchmore Cox, Ian William Wark

In defending the chemical theory of flotation, Taggart, del Giudice and Ziehl have criticized1 the views of those who prefer to attribute the effects of certain flotation agents to adsorption. Perhaps with some justification, they describe the latter term as the "haven of refuge of writers lost in a morass of shaky experiment and muddy thinking." We prefer to regard it, however, as a haven of refuge for writers who seek a conventional term to describe the formation of films of flotation reagents on solid surfaces, because in many cases it is not yet possible to specify the forces that hold them there. Originally, as Taggart and his associates state, adsorption connoted a concentration difference and nothing more. In recent years, workers in the field of surface chemistry have tacitly added other meanings, and they now speak of orientated adsorption of unimolecular films on a solid sub-strate, of chemi-adsorption, and of exchange adsorption. Thus the term adsorption may connote simply the Gibbs layer of excess concentration at the surface of a solution, or a unimolecular film at the surface of a solid. Perhaps this has led to the misunderstanding of Taggart, del Giudice and Ziehl concerning the relationship between surface tension and adsorption at solid surfaces. The change in "surface tension" accompanying adsorption at a liquid surface can be used as a measure of the adsorption, and the Gibbs equation as quoted by these authors correlates these two conceptions. But, to correlate two conceptions docs not necessarily imply an attempt to explain either, although sometimes such an "explanation" is carelessly inferred. Use of "surface energy per unit area" instead of the numerically equal but more difficult and less definite conception of "surface tension per unit length " would lessen many of the present difficulties. (Compare with Adam.2) At interfaces involving a solid phase, neither '" surface tension " nor " interfacial tension "can have any meaning, but the conception "interfacial energy per unit area" call be understood by anyone who is familiar with the concept of free energy. While it is true that surface energy cannot be directly measured at a solid surface,

Jan 1, 1939

By Henry M. Howe

Many direct processes have been proposed for the treatment of oxidized ores of copper by reducing the copper oxide to the metallic state, and by separating it from its impurities by a subsequent fusion. The radical objection common to all the methods which have come to my notice, except those in which sulphur plays the prominent part, is that the very deoxidizing agent which effects the reduction of the copper oxide, inevitably reduces at the same time a very considerable part, if not the whole, of the iron which almost invariably accompanies copper in its ores. The result is that, when the ore is subsequently fused, a very great quantity of the already reduced iron separates from the slag along with the copper, alloying with it, and necessitating costly subsequent operations for its separation. Thus, at Perm, in the Urals," the product of the fusion of ferrnginous copper oxides is a mixture of one hundred and fifty-tive parts of highly cupriferous pig iron with two hundred and fire parts of very impure and ferruginous black copper, containing Pome 10 per cent. of' carbon and iron, though free from sulphur, and of course very difficult to refine. If, in order to avoid this reduction of iron to the metallic state, the reducing action be made feebler, it inevitably results that a considerable part of the copper as well escapes deoxidation; and, consequently, the slags are so rich that it becomes necessary to treat them subsequently in order to recover the copper which they contain. Thus,. in treating native copper, at Lake Superior, where the reducing action is purposely made feeble in order to prevent the deoxidation of the iron, the slags from the first fusion of the ore carry so much copper as to render it imperative to treat them again, which is done in a cupola. And yet, in spite of so far weakening the reducing action as to cause a notable slagging of the copper, a very considerable reduction of iron actually takes place. These are the two dangers which threaten the smelter of oxidized copper ores. If he wishes to avoid slagging his copper, he must have so strong a deoxidizing action as to reduce a great deal of his

Jan 1, 1879

The Youga gold mine in Burkina Faso, West Africa, is scheduled to produce first gold in the third quarter of calendar 2007. The project is expected to produce 540 000 oz of gold over 6.5 years, from a conventional open pit carbon in leach mine. The direct capital cost of the project is US$47 M. Etruscan Resources Inc, a Canadian based gold exploration and development company, holds 90 per cent of the project company Burkina Mining Company SA (BMC). The state of Burkina Faso is free-carried for the remaining ten per cent of BMC. RMB Resources Limited, of Melbourne Australia, has arranged a US$35 M project finance facility for BMC (the Borrower) as the majority of funding for the Youga project development. The loan facility was provided by RMB Australia Holdings and Macquarie Bank Ltd (the Lenders) each as to 50 per cent in the lending syndicate. The Lenders also provided a gold hedging facility to guarantee a minimum price for the projectÆs gold production. Burkina Faso is a francophone country, part of the Economic and Monetary Union of West Africa (UEMOA). The project financing is the first such facility to be arranged for a mining project in Burkina Faso, with little or no precedent available in other UEMOA countries. Therefore, while the Youga gold project is forecast to be a robust project applying conventional mining and processing methods, a number of legal, technical, commercial and social issues required identification, evaluation and resolution before the loan could be established. This paper describes that evaluation process and the resolution of these issues. In-house experience and expertise in both the LendersÆ and BorrowerÆs teams has facilitated a greater understanding and æownershipÆ of the issues and hence provided comfort with risks which might not normally be taken in conventional project developments and project financings. As a result, blanket external reviews were not required by the Lenders. A long-standing relationship between Etruscan and RMB Resources also facilitated solutions to a number of issues. Nevertheless, a degree of flexibility by the Lenders, the Borrower and Etruscan was required to successfully close the financing.

Jan 1, 2007

By H. R. Fife

AN extended study of dustproofing Freeport-seam coal has empha-sized several fundamental features in the successful treating of bituminous coals. The extent of the exposed surface area and its absorption proper-ties for the dust-retaining film were found to be the most critical factors affecting the efficiency of fly-dust prevention. From recently published screen data and specific surface-area measure-ments on United Kingdom coals, an approximation of the surface exposed by mine-run coal and by 1-in. slack was made. The total surface area exposed by an average ton of this mine-run coal was estimated at 3768 sq. yd., while a ton of 1-in. slack represents a total surface area of 8779 sq. yd. with no additions for porosity. It is important in coal treating to consider that in mine-run coal the fraction above 1/4 in. in size represents 79.5 per cent of the total weight, but only 4 per cent of the total surface, while the fraction below 150 mesh contains 47 per cent of the total surface and only 1.2 per cent of the total weight. Also, one should appreciate that, in a 1-in. slack, the domestic stoker fraction (1 in. to 8 mesh) contains 76.3 per cent of the weight and 8.2 per cent of the surface, while the fraction below 150 mesh represents 3.3 per cent by weight and 54.8 per cent by sur-face area. Wax extraction data on 1-in. to 0 slack from mine-run treated Free-port-seam coal showed that the coating was distributed uniformly as a function of exposed surface; hence, nonuniformly on a weight basis. This distribution of the coating on mine-run coal therefore limits the extent of treating that is desirable on bituminous coal at this point in the preparation. The treatment of Freeport mine-run coal before it reached the tipple gave a 70 to 80 per cent reduction of fly-dust in the tipple, a satisfactory treated commercial slack coal, and an indicated change in the trend of tipple degradation. The premium-treated domestic sizes required a supplemental treatment for complete dustproofness.

Jan 1, 1937

By A. W. Gauger

For perhaps one hundred years scientists have been engaged in attempts at devising a satisfactory method of classification of coal. During this time many charts, tables and graphs have been proposed, some of which have had considerable merit, but no one system has been found to be applicable to all ranks of coal, nor has any one system received general acceptance. In many of the proposals, water eliminated between room temperature and 105" C. has been regarded as extraneous matter and calculations have been made to the air-dry or water-free basis. Such methods of calculation do not lend themselves to satisfactory grouping of the high-moisture coals.1, 2 A consideration not only of the properties of the high-moisture coals and their behavior on drying but of the generally accepted ideas of the coalification process and the role of water in this process indicates that water is an essential constituent of all coals and therefore should not be neglected. For example, in such low-rank coals as the lignites of the Northern Great Plains' deposits the inherent moisture of the lignite as mined plays a very important part in the physical properties thereof. Freshly mined lignite contains upwards of 30 per cent water and is extremely tough and resistant to shock. Upon exposure to the atmosphere, the lump loses part of its moisture and checks and splits, leaving a friable and broken up residue. So far as we have been able to determine, water is the only thing lost in this process and we are forced to the conclusion that moisture plays an extremely important part in the structural properties of the original lignite. With reference to the coalification process, Mack and Hulett3 pointed out in 1917 the important part that water played therein. They observed that water cannot be removed from peat or coal by pressure alone, but only as the result of chemical reaction, and suggested that peat in its early stages may be largely a hydrosol. Slow chemical changes occur over a long period of time until finally the mass becomes more largely a hydrogel. These views are substantiated to some extent by the experi-

Jan 1, 1932

By Ian William Wark, Alwyn Birchmore Cox

In defending the chemical theory of flotation, Taggart, del Giudice and Ziehl have criticized1 the views of those who prefer to attribute the effects of certain flotation agents to adsorption. Perhaps with some justification, they describe the latter term as the "haven of refuge of writers lost in a morass of shaky experiment and muddy thinking." We prefer to regard it, however, as a haven of refuge for writers who seek a conventional term to describe the formation of films of flotation reagents on solid surfaces, because in many cases it is not yet possible to specify the forces that hold them there. Originally, as Taggart and his associates state, adsorption connoted a concentration difference and nothing more. In recent years, workers in the field of surface chemistry have tacitly added other meanings, and they now speak of orientated adsorption of unimolecular films on a solid sub-strate, of chemi-adsorption, and of exchange adsorption. Thus the term adsorption may connote simply the Gibbs layer of excess concentration at the surface of a solution, or a unimolecular film at the surface of a solid. Perhaps this has led to the misunderstanding of Taggart, del Giudice and Ziehl concerning the relationship between surface tension and adsorption at solid surfaces. The change in "surface tension" accompanying adsorption at a liquid surface can be used as a measure of the adsorption, and the Gibbs equation as quoted by these authors correlates these two conceptions. But, to correlate two conceptions docs not necessarily imply an attempt to explain either, although sometimes such an "explanation" is carelessly inferred. Use of "surface energy per unit area" instead of the numerically equal but more difficult and less definite conception of "surface tension per unit length " would lessen many of the present difficulties. (Compare with Adam.2) At interfaces involving a solid phase, neither '" surface tension " nor " interfacial tension "can have any meaning, but the conception "interfacial energy per unit area" call be understood by anyone who is familiar with the concept of free energy. While it is true that surface energy cannot be directly measured at a solid surface,

Jan 1, 1939