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By K. Huessener

INTRODUCTION THIS paper attempts a survey of the principles involved in the com¬bustion of blast-furnace gas in boilers and stoves. I do not expect to be able to give much information which is actually new, since the laws and methods of calculation pertaining to this problem are contained in a number of handbooks; but, so far as I am aware, they have nowhere been treated exclusively with reference to this one problem of gas economy. The road which I follow is less that of strictly scientific research than that of the practical engineer, faced by operation problems which require a. quick solution by easily accessible means without a prolonged search in scientific handbooks. For this purpose I give a number of tables and diagrams, as well as the results of many years' practical working experience as combustion engineer, which I trust will prove useful to my readers. HISTORICAL Considering the tremendous efforts made during the last 15 years to increase the efficiency of all kinds of power plants, it is highly surprising that until a comparatively very recent period, progress in the economical combustion of blast-furnace gas has been so slow. The explanation generally put forth, that fuel has been so cheap that it was hardly worth while to bother about this economy, will not hold good, for the greatest trouble was taken to improve the combustion of coal and to reduce the consumption of steam. The most plausible explanation appears to be the general impression, held as an accepted fact, that gas, especially hot, uncleaned, blast-furnace gas, was not a good boiler fuel. Many managers of high repute had tried unsuccessfully to improve the conditions of its use, and the dictum went forth that efficiencies of over 60 per cent., particularly with high loads, were impossible. This was the situation not only in the United States, with very cheap fuel, but also in Europe, where fuel prices are twice and three times as high.

Jan 2, 1916

By Erwin H. E. Gaertner

The brown-coal opencast mines in Germany's Rhineland have to cope with several problems. Predominant are densely populated areas with highly productive farmland, many railroads, highways, and rivers, as well as towns and farm settlements which have to be removed before or during the lifetime of a mine. Also the ground- water table has to be lowered to keep the deep opencast mines dry and stable. These problems urged a development towards deep opencast mines with powerful machines; the large material movement and the high coal production are the basis for the economic success in working the Rhenish brown-coal deposits. Up to now, bucket wheel excavators with a daily capacity of 100,000 m3 (130,000 cu yd) are in operation. Machines of twice this capacity are under construction. Corresponding to the excavators development, the stackers' capacity has to be increased too. The new stackers will reach a daily capacity of 240,000 m3 (310,000 cu yd). The haulage in the mine is performed by conveyor belt systems, which are arranged in such a manner that the belt lines meet at a belt switching point. Here the incoming lines may be connected to the outgoing ones so as to direct the material flow to the desired receiving stations. At the moment there are conveyor belts in operation with a width of 2.2 m (7.2 ft); the new belts will have a layout for 37,000 t/h (40,770 stph), the width of which amounts to 3.0 m (9.8 ft). All belts and driving stations on benches are shiftable.

Jan 1, 1976

By Marston G. Fleming

CRITICAL pH has been defined by Wark1 as that pH value below which a mineral will float and above which it will not float in solutions containing a given concentration of collector but free from other depressants or activators. - The relationship between mineral, collector concentration, and pH is expressed in the form of a critical pH curve determined by the captive bubble method and is generally regarded as being fundamental to the system involved. The mechanism of alkali depression is currently in dispute, two general theories having received authoritative support. The view expressed in Taggart's chemical theory of flotation2 is that in the presence of a critical concentration of hydroxyl ions, all the metal ions available at the surface of the mineral are present as anions of the form [M (OH)x]-y. The formation of the necessary metal xanthate is thus precluded and, furthermore, any metal xanthate coating previously formed, at a lower pH, will be dissolved. Gaudin3,4 and the Melbourne school under Ware hold that alkali depression is caused by the preferential adsorption of hydroxyl ions by the mineral surfaces. This paper describes an investigation of the mechanism of alkali depression in each of the three systems: cerussite-aqueous carbonate-xanthate, cerussite-xanthate, and galena-xanthate. Alkali Depression of Cerussite by Control of Carbonate Ion Concentration Wark and Cox6 have shown that in the presence of Na2CO3 a higher concentration of xanthate is required to effect bubble contact with a cerussite surface than in carbonate-free solutions. To examine this depression of cerussite by sodium carbonate, a series of captive bubble tests was carried out on cerussite specimens in solutions containing 100 mg per liter of potassium ethyl xanthate and varying concentrations of sodium carbonate. The pH was adjusted by the addition of dilute hydrochloric acid. For purposes of comparison a standard critical pH curve was determined for cerussite with potassium ethyl xanthate in solutions containing no added carbonate. In the latter case pH adjustment was made with sodium hydroxide. The experimental method employed in both series was broadly similar to that described by Wark and Cox;7-9 a number of refinements suggested by Sutherland10 were adopted, and the procedure was further developed and modified to suit the particular requirements of the investigation. The relationship between pH and the concentration of potassium ethyl xanthate necessary to induce bubble contact at cerussite surfaces is shown in Fig. 1. The relationship between pH and the concentra- [ ] tion of sodium carbonate necessary to prevent bubble contact at cerussite surfaces in the presence of 100 mg per liter of potassium ethyl xanthate is shown in Fig. 2. Comparison of the. two curves shows that at a collector concentration of 100 mg

Jan 1, 1952

By C. M. Moncrief, B C. Craft

A bentonite-clay drilling mud when treated with tetrasodium pyroarsenate underwent substantially the same reduction in viscosity and water loss as when treated with the complex phosphates. The complex arsenate showed a slightly higher reversion after heating; the other arsenates showed poor viscosity-reducing properties. Introduction During the past 10 years the chemical control of drilling mud has become of major importance in affecting the successful drilling and working over of wells. The desired properties of drilling mud have been well established, and in obtaining these characteristics there has developed a large market for viscosity-reducing chemicals. Viscosity reduction produced by humic acid, tannic acid, sodium silicate, sodium tannate, Calgon, and the complex phosphates has been described by Loomis, Ford, and Fidiam.l The effects Of treatment with complex phosphates and ammonium PolyPhosPhates on the rheological properties of muds were investigated by Fancher2 and the alkali vanadates have been described by Williams.3 Laboratory Investigations It is the purpose of this paper to point out the effects of arsenates in controlling the viscosity and gelling characteristics of a drilling mud. Viscosities and gel strengths were measured at room temperatures with a Stormer viscosimeter calibrated in centipoises and operated at 600 r.p.m. Water loss was determined at 80°F. with the Baroid low-pressure wall-building tester at a pressure of I00 lb. per sq. in. for 30 min. The hydrogen-ion concentration was measured with a glass electrode. The bentonite-clay suspensions were prepared in the laboratory and allowed to age several days before testing. Members of the Arsenic Group in the periodic Table include arsenic, antimony and bismuth, but this investigation was limited to arsenic. Phosphorus also occurs in Group V of the Periodic system and phosphorus and arsenic form many closely related compounds such as pH3 and AsH3, P2O5 and As2O5, H3PO4 and H3AS04 Samples of tetrasodium pyroarsenate were prepared by fusing c.p. disodium arsenate (Na2HA5O4.7H2O). According to Friend,' this re-forms the ortho-arsenate on dissolution in water. Sodium trihydrodiorthoarsenate was prepared as described by Mellor,5 from arsenic pen-toxide as follows: As2O5 + 3H20 -> 2H3AsO4 2H3AS04 + 3NaOH Na3H3(AsO4)2 .3H20 Sodium dihydrogen orthoarsenateWaHz-As04) was obtained by fusing together equivalent quantities of arsenious Oxide and sodium nitrate, dissolving the residue in water and allowing it to crystallize.

Jan 1, 1946

By C. M. Moncrief

A bentonite-clay drilling mud when treated with tetrasodium pyroarsenate underwent substantially the same reduction in viscosity and water loss as when treated with the complex phosphates. The complex arsenate showed a slightly higher reversion after heating; the other arsenates showed poor viscosity-reducing properties. Introduction During the past 10 years the chemical control of drilling mud has become of major importance in affecting the successful drilling and working over of wells. The desired properties of drilling mud have been well established, and in obtaining these characteristics there has developed a large market for viscosity-reducing chemicals. Viscosity reduction produced by humic acid, tannic acid, sodium silicate, sodium tannate, Calgon, and the complex phosphates has been described by Loomis, Ford, and Fidiam.l The effects Of treatment with complex phosphates and ammonium PolyPhosPhates on the rheological properties of muds were investigated by Fancher2 and the alkali vanadates have been described by Williams.3 Laboratory Investigations It is the purpose of this paper to point out the effects of arsenates in controlling the viscosity and gelling characteristics of a drilling mud. Viscosities and gel strengths were measured at room temperatures with a Stormer viscosimeter calibrated in centipoises and operated at 600 r.p.m. Water loss was determined at 80°F. with the Baroid low-pressure wall-building tester at a pressure of I00 lb. per sq. in. for 30 min. The hydrogen-ion concentration was measured with a glass electrode. The bentonite-clay suspensions were prepared in the laboratory and allowed to age several days before testing. Members of the Arsenic Group in the periodic Table include arsenic, antimony and bismuth, but this investigation was limited to arsenic. Phosphorus also occurs in Group V of the Periodic system and phosphorus and arsenic form many closely related compounds such as pH3 and AsH3, P2O5 and As2O5, H3PO4 and H3AS04 Samples of tetrasodium pyroarsenate were prepared by fusing c.p. disodium arsenate (Na2HA5O4.7H2O). According to Friend,' this re-forms the ortho-arsenate on dissolution in water. Sodium trihydrodiorthoarsenate was prepared as described by Mellor,5 from arsenic pen-toxide as follows: As2O5 + 3H20 -> 2H3AsO4 2H3AS04 + 3NaOH Na3H3(AsO4)2 .3H20 Sodium dihydrogen orthoarsenateWaHz-As04) was obtained by fusing together equivalent quantities of arsenious Oxide and sodium nitrate, dissolving the residue in water and allowing it to crystallize.

Jan 1, 1946

The following list comprises the names of those persons who became. members during the period Oct. 10, 1919, to Nov. 10, 1919. ABELL, 0. J., Pres. & Treas., Abell-Howe Co., 332 South Michigan Ave.; Chicago, Ill. ADAMI, ARTHUR E., Asst. Prof. of Min. Engrg., Montana State School of Mines,Butte, Mont. BASSETT, R. H Chief Engr., Hanna Ore Min. Co., Hibbing, Minn. BOZA, HECTOR J., Cons. Engr., Boza Aizcorbe Hermanos, Box 106, Lima, Peru. BROWN, HAROLD P., Cons. Concrete Engr 120 Liberty St., New York, N. Y. BUCHANAN, W. A Mgr., Meteor Mine, Slocan City, B. C., Canada. CAMERON, JAMES A Supt., Ellsworth Collieries Co., Ellsworth Pa. CARPENTER, CRANSTON HOWE, Electro-Met. Engr., General Engrg. Division, Westinghouse Electric & Mfg. Co., East Pittsburgh, Pa. CASTLETON, GEORGE T Assayer, Custom Office, Box 122, Eureka, Utah. CHAFFIN, C. E., Eastern Mgr., General Engineering Co., 120 Broadway, New York-, N. Y. CLARK, WALTER R., Wks. Mgr., Bridgeport Brass Co., 1875 Park Ave., Bridgeport, Conn. CLARKE, ERNEST E., Min. Engr., Vinegar Hill Zinc Co., 419 S. Court St., Platteville, Wis. COOLIDGE, E. B., Mgr., Spotted Horse Mine, St. Paul Montana Min. Co., Maiden, Mont. CORTELYOU, ARTHUR P., Resident Mgr., Potrero Min Co. Mocorito, Sinaloa, Mexico. COTTINGHAM, KENNETH, Pet. Engr., Halter & Robitaille Delmonico Bldg.,Fifth Ave. & 44th St., New York, N. Y. CREW, J. A Mgr., Research Dept., Pittsburgh Steel Co., Monessen, Pa. CUMMINGS, LISTER M., Efficiency Engr., Copper Queen Branch, Phelps-Dodge Corpn., Box 1539, Bisbee, Ariz. DANFORTH, GEORGE L., JR., Asst. Gen'l Supt., Illinois Steel Co., South Works, South Chicago, Ill.

Jan 12, 1919

By Jan D. Miller

Under the name given to this column, I almost feel obliged to write about some aspect of grinding, but I have decided instead to comment on the future of chemical processing. In recent years, I have seen a tremendous interest in extractive metallurgy develop among undergraduate and graduate students at the University of Utah. For example, of the 12 graduating seniors this year, over half seem to prefer extractive metallurgy to physical metallurgy. In particular, they seem to be most interested in hydrometallurgy, or chemical processing, obtaining industrial exposure to the phenomena they study via part-time employment at the Kennecott Research Center and the USBM Metallurgical Center in Salt Lake City. The stimulus has been generated by society itself. Many students are dedicated to the proposition that new technology can circumvent the destruction of our environment, a concept which provides considerable motivation. At the governmental level, the recent concern for the quality of our environment has created action in the area of chemical processing both through imposition of stringent air and water quality standards, and through increased funding for technological research in this area. The National Academy of Sciences (NAS) gave impetus to this movement when it pointed up the need for development and support of such disciplines as extractive metallurgy, particularly chemical processing, in a recent report on Mineral Science and Technology. The recommendations in the NAS report have prompted governmental action on many fronts, including the Bureau of Mines, and have also given rise to direct legislation in the form of two bills -H. R. 3492 and S. 635- presently before Congress to a mineral engineering education. The report recommends that chemical processing technology (more generally extractive metallurgy) be developed by both new engineering techniques and unconventional chemical techniques such as application of the chemistry of nonaqueous liquids to mineral systems.

Jan 1, 1971

By R. L. McCarron, G. R. Belton

The diffusivities of oxygen and sulfur in liquid iron have heen determined hy a capillary technique in which the surface concentrations of the solutes were established by means of appropriate H2/H2 and H2S/H, gas mixtures. Total diffusate and concentration profile results are shown to be in good accord, yielding for- 1560 and Supporting results at 1660°C are also presented. The conditions necessary to avoid gas transport control in this type of experiment are discussed. IN spite of their importance in understanding the kinetics and mechanisms of refining reactions, the dif-fusivities of oxygen and sulfur in liquid iron are not well established. Accordingly, as a first step in studies of rates of solute absorption from the gas phase into liquid iron, new measurements of these diffusivities have been made and are presented in this paper. The only published results for the diffusion of sulfur in pure liquid iron are those of Kawai.' He used a diffusion couple technique in which two cylindrical specimens, one containing sulfur and the other with negligible sulfur concentration, were joined together and held in a refractory capillary. After an experiment, the sample was quenched and the concentration distribution of the solute determined. Kawai recognized that significant changes in solute distribution occurred during melting and freezing and he attempted to correct the concentration profiles for these effects to give a sulfur diffusivity of 4.6 x 10-6 sq cm per sec at 1560°C. The method of correction, however, was not rigorous and the uncertainty in this result cannot be easily assessed. Koslov et a1.2 have reported the diffusivity of oxygen in iron as 7.8 x 10"3 sq cm per sec at 1660°C. This value appears to be unreasonably high but, unfortunately, details of their experiments are not available. Shurygin and Kryuk have used the rotating disc method for a study of oxygen diffusion in liquid iron. In their experiments a silica disc was rotated in liquid iron containing oxygen, and the rate of formation of liquid iron silicate was determined by measuring the decrease in weight of the disc. On the assumption that the rate of dissolution was controlled by the diffusion of oxygen in the iron, the diffusion coefficient was computed to be 5.2 x sq cm per sec at 1550°C. However, the Levich equation, which was used to interpret the rate data, was originally de- rived for the case of mass transfer between a solid disc and a single-phase liquid. The hydrodynamic and diffusion boundary layers in the iron stirred by a disc, via coupling of the silicate melt, may be appreciably different from those predicted by Levich's equations. Recently, Novokhatskiy and Ershov, using an identical experimental method to that of Shurygin and Kryuk, obtained a diffusivity for oxygen in liquid iron of 1.22 x 104 sq cm per sec at 1550°C: no reasons were offered for the disagreement. Schwerdtfeger5 has also recently studied the diffusivity of oxygen in liquid iron. He reacted shallow melts of liquid iron, 0.5 to 1.0 cm deep and contained in high-purity alumina crucibles, with appropriate H20-HZ-He mixtures. The total sample was analyzed, without sectioning, to obtain the average concentration of diffusate. A value at 1610°C of D = 12(3) x 10-5 sq cm per sec was obtained from the results of twenty experiments.= Oxygen profile measurements, which were carried out in three additional experiments using long capillaries and the semiinfinite boundary conditions, indicated a diffusivity about half that computed from the shallow bath experiments. Possible sources of error in Schwerdtfeger's study will be discussed later in this paper. EXPERIMENTAL TECHNIQUE The essential arrangement of the diffusion cell is shown in Fig. 1. The liquid iron was contained in an alumina capillary, 3 to 4 mm diam and 3 to 9 cm long, which was supported by a hollow alumina pedestal and this whole assembly was held within a movable alumina reaction tube. This tube, which was about 7 mm in bore

Jan 1, 1970

By Charles Catlett

THE rapid development of the Portland-cement industry implies that the country is being very carefully searched for material suitable for its manufacture. Such material can be found at a great many places ; but deposits thoroughly satisfactory in chemical composition, and at the same time meeting all the other requirements connected with the economic production and profitable marketing of the product, are exceedingly few, if I may judge from the investigations which I have had to make in a number of States. The raw mixture which by its clinking and grinding forms Portland cement contains approximately 75 per cent. of carbonate of lime. This is found in nature as limestone or marl. The natural rock commonly carries either more than the required percentage of carbonate of lime (in which case it has to be reduced by suitable admixture of clayey ingredients) or less-in which case purer lime carbonate has to be added. The controlling ingredient, therefore, is carbonate of lime, or limestone of the right composition. Among the most serious difficulties is that of finding limestones low enough in magnesia to meet the exacting requirements of certain specifications. All engineers recognize that there is a limit beyond which it is not safe to let the magnesia go; but within that limit there is considerable difference of opinion. Until that difference is finally settled, no one would be willing to invest the large sum of money necessary for a Portland-cement plant, if it were not certain that the usual requirements in this particular could be satisfied. The usual limit in well-established specifications is 5 per cent. of magnesium oxide in the finished cement, but many specifications limit the amount to 3 per cent. These figures

Jan 9, 1907

By Albert Sauveur

My first paper dealing with the theories of the hardening of steel by rapid cooling was published in the Transactions of this Institute in 1896— 30 years ago-under the title "The Microstructure of Steel and the Current Theories of Hardening," hence, also, the title of the present paper. It was extensively discussed and was, I believe, one of the starting points of many subsequent papers and discussions of the same subject, dis-cusssions which at times became almost violent and which led to the formation of different schools such as the "Carbonists" and the "Allo-tropists." Some of the older members of the Institute, who took part in the debate or who were interested observers, will, I am sure, have kept a vivid remembrance of it. The controversy gradually quieted down, apparently for lack of ammunition, without any side acknowledging defeat. Recently, however, interest in it ha been revived through the claims of some that these vexed questions had at last been solved. In an effort to ascertain if possible the prevailing view of those best qualified to express an opinion a questionnaire was submitted to the following gentlemen: J. 0. Arnold Sir Robert Hadfield Edgar C. Bain W. H. Hatfield Carl Benedicks Samuel L. Hoyt N. Belaiew Kotaro Honda H. M. Boylston Zay Jeffries Harry Brearley H. Le Chatelier G. K. Burgess H. H. Lester William Campbell Francis F. Lucas H. C. H. Carpenter John A. Mathews Pierre Chevenard A. McCance P. Dejean Albert Portevin C. A. Edwards Walter Rosenhain F. Giolliti Bradley Stoughton G. Grenet F. C. Thompson Leon Guillet

Jan 1, 1926

By D. Brion, J. J. Prédali, J. Hayer

The need to grind volcanic-sedimentary ores very finely (d80 < 20 µm) so as to liberate Pb, Zn, and Cu sulfides from their pyritic gangue causes difficulties in selective flotation. The pyrite, which accounts for 70-80% of the mineral content, is insufficiently depressed by the usual pH and NaCN techniques. To determine better depressing methods, the surface evolution of pyrite during flotation was followed by ESCA spectroscopy to compare the stability range in the Eh-pH diagram. Surface iron hydroxide was formed, which is the main pyrite-depressing factor. NaCN appears to play a more restrictive part, since no ferricyanides were detected, except for very small amounts at pH 7.

Jan 1, 1980

By J. PARK

Discussion of the paper of J. PARSE CHANNING, presented at the New York meeting, February, 1915, and printed in Bulletin No. 99, March, 1915, pp. 529 to 538. FRED H. RINDGE, JR., * New York, N. Y.-It is interesting to note that although this movement was started only seven years ago at Yale, it has spread in that brief time to 200 colleges and technical schools, anti thousands of men are interested in it. There are 3,000 graduates who became acquainted with the movement in college days anti are now promoting the industrial betterment idea all over the country. Some of these men are employed entirely in this work, and the number of such workers is constantly increasing. We feel we are really doing a very fundamental thing in getting so many coming engineers and prospective employers of labor to interest themselves in these things which we have been discussing this morning; these things which are so vital to efficiency and success in any line of business or engineering to-clay. Of course the institutions located in our large industrial centers have the greatest opportunity for practical service. But I have just returned from one college, Pennsylvania State College, where 300 engineering students in three clays signed up as interested in this movement and as anxious to take active part in the work this summer. That is one of a number of colleges situated in towns where there are 110 industrial opportunities. Therefore, their field of service must be where they work

Jan 5, 1915

By Henry H. Logan

THE purpose of mine-hoist safety controllers is to prevent hoists from being operated at speeds above those considered safe and expedient, to ensure proper acceleration and retardation near the ends of travel, and to prevent overwinding. In other words, they are to safeguard the normal speeds and movements of the hoisting drums and cages. The object of this paper is to explain the fundamental principles of hoist controllers, and to aid in their selection, installation, and maintenance. There have been many designs of mechanical hoist controllers, the basic elements of which as ultimately developed consisted of a flyball governor and another movable member supported by a frame and arranged to move in a vertical, horizontal, or rotary direction, depending upon the particular design, the whole mechanism arranged to be driven in synchronism with the hoist drum. In case of overspeeding, inadequate retardation, or overwinding, a pawl or catch controlled by the governor would engage teeth or dogs on the moving member, which through mechanical connections would cut off the power and set the brakes. Since in strictly mechanical hoist controllers valuable time was lost while the various mechanical movements took place, an important development was the invention of controllers partly mechanical and partly electrical. This type of controller has a governor and movable cams to be driven in synchronism with the hoist drum, the governor representing the hoist speeds and the cams profiled to form a pattern for retardation, representing the travel of the cages in the shaft. This type is also provided with an overspeed switch and usually with a pair of selective-limit switches, one for the top limit and the other for the bottom. In overspeeding or failure to retard in accordance with the profile of the cam, the overspeed switch will be opened, or if the top or bottom limit is overrun one of the limit switches will be opened, breaking the retaining circuit of a contactor or magnetic latch, causing the power to be cut off and the brakes applied. When the speed falls to the predetermined safe speed, the overspeed switch closes, and a hoist equipped with power-operated brakes controlled in emergency by a solenoid-operated valve can be restarted immediately by simply moving the master control lever to the "off" position and then applying power-unless brake interlocks are used, in which case the brake lever or levers must also be brought to the "applied" position, after which the hoist can be restarted in the usual way. When hand-reset weights instead of solenoid-operated mechanism are arranged to set the brakes for emergency, it is necessary to reset the weights manually, besides bringing the master control lever to the "off" position before the hoist can be restarted. Should a final limit be slightly overrun, and a stop made with a limit switch held open by a cam, it is necessary for the hoistman to use a "backing-out" switch which short-circuits the overrun limit switch, reestablishing the hoist-control circuit, and simultaneously opening the

Jan 1, 1940

1. What Is a Rock Burst? . . . . 569 Jack Spalding . . 569 A. F. Robertson . 569 W. R. Crane . 569 G. S. Rice......569 P. J. Shenon........... 569 L. C. Graton........... 569 2. What Are the Causes of Rock Bursts? 573 Jack Spalding..........573 A. B. Yates and P. J. Shenon 574, 578, 592, 596 A. F. Robertson . . . . . 575, 595 W. R. Crane. ... 579 G. S. Rice.........582 Oscar Weiss .........582 P. B. Bucky..........582 P. H. Bird.....588, 592, 593, 595 M. K. Hubbert.........593 G. Wheeler.......... .593 B. F. Tillson........593, 595 T. T. Read............594 3. How Can Rock Bursts Be Prevented?. 597 Jack Spalding..........597 A. B. Yates and P. J. Shenon ... 598 A. F. Robertson.......599 W. R. Crane....... .602 G. S. Rice............602 Page 4. How Can Rock Bursts Be Predicted?. 602 Jack Spalding.........602 A. F. Robertson.......602, 603 A. B. Yates and P. J. Shenon ... 602 W. R. Crane......602 G. S. Rice......602 B. F. Tillson...........603 5. How Can Rock Bursts Be Controlled? 603 Jack Spalding..........603 A. F. Robertson.......603 W. R. Crane...........604 A. B. Yates and P. J. Shenon 604 Oscar Weiss........605 G. S. Rice......- 604, 609 R.D.Hoffman..609, 610 R. D. Hall..........609 R. H. Cromwell . . 609 P. J. Shenon...........609 P. B. Bucky......609, 611 B. F. Tillson.........609, 611 A. B. Yates...610, 611 P. H. Bird.......610 6. General Discussion........ 611 Jack Spalding.......... 611 R. D. Parker....... . 616 C. Baring Horwood........ 618 P. B. Bucky........... 619 Foreword This symposium brings together points of view, experiences and ideas on rock bursts from a goodly portion of the globe. Some conceptions, particularly those regarding the necessity of depth, have been fairly well shattered, as we find that they are present in the water tunnels of New York, on the surface at marble quarries in Vermont, and in the coal mines of the United States, as well as in the deep mines of the South African and Kolar gold fields, and in the nickel, copper and gold mines of Canada. Their occurrence under such a variety of conditions is, therefore, a challenge, which, if successfully met and overcome,

Jan 1, 1946

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&apos;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 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&apos;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

Jerome L. Boyer, Reading, Chairman; William L. Sheafer, Pottsville, Secretary ; Levi Quier, Reading, Treasurer; Robert Allison, Port Carbon; James Archbald, Jr., Pottsville; William Atkins, Pottsville; D. P. Brown, Lost Creek; William McH. Boyer, Rending; Albert Broden, Reading; George Brooke, Birdsboro; Frank Carter, Pottsville; H. P. Cooper, Pottsville ; J. H. Carpenter, Reading; E. S. Cook, Pottstown; B. Halberstadt, Pottsville; Hakon Hammer, Pottstown; J. Hartshorne, Stowe; M. P. Janney, Pottstown; R. C. Luther, Pottsville; N. Muhlenberg, Reading ; W. H. Morris. Pottstown ; George L. Norris, Reading; G. H. Potts, Pottstown ; H. Potts, Pottstown; S. M. Riley, Ashland ; J. S. Robeson, Pottstown ; Jas. P. Roe, Pottstown; A. W. Sheafer, Pottsville; Heber S. Thompson, Pottsville; Bard Wells, Pottsville; E. C.Wagner, Girardville; N. B. Wittman, Birdsboro. Reception Committee.— George Brooke, Chairman; Robert Allison, J. H. Carpenter, Edgar S. Cook, R. C. Luther, W. H. Morris, H. S. Thompson. Hotel Headquarters.—The Neversink Mountain Hotel, near Reading, Pa. All sessions were held in the hotel. The opening session was held on Tuesday evening, October 11. Mr. Jerome L. Boyer, Chairman of the Local Committee, called the meeting to order, and introduced Mr. John F. Daniel], Jr., VicePresident of the Reading Board of Trade, who delivered an address of welcome, in the course of which the industrial and commercial importance of the city was effectively outlined by skilful use of the statistics of leading branches. From this statement the following particulars are condensed for preservation: The Board of Trade has about 300 members. The annual value of the manofttctures (taking mainly the figures of 1891) is as follows: Iron manufactures, about $16,000,000 (including boilers and flues, $323,000; hardware, locks and butts, $1,650,000; pig-iron, wrought-iron pipe and machinery, $8,400,000; beams, bridge-work and steel, $4,000,000; bolts, nuts, rivets, etc., $1,000,000; stoves, $659,000); silk and cotton goods, $1,725,000; boots and shoes (one concern only), $150,000; ropes and cordage, $600,000; fire-brick, terra-cotta and glass, $320,000; wool and fur hats, $3,000,000; cigars (105 millions), upwards of $3,150,000. The street and elec-

Jan 1, 1893

E O&apos;C Acker &apos;86 Jinzoc Adachl &apos;88 Frederic R Abbe &apos;97 T H Aldrich &apos;96 Truman H Aldrich &apos;78 Walter H Aldridge &apos;89 Anson W Allen &apos;87 John H Allen &apos;84 Thomas Andrews &apos;94 William R Appleby &apos;90 R M Atwater, Jr &apos;97 Lawrence Austin &apos;82 S Ayres &apos;73 H Foster Bain &apos;97 David Baker &apos;86 John Henry Banks &apos;83 Henry C Banon &apos;90 Thomas J Barbour &apos;97 Alonzo F Bardwell &apos;89

Jan 1, 1952

By Chas. Kohl

ABOUT 1929 an engineer was engaged to organize a Safety Department, lay out an educational program, and achieve a reduction in accident frequency. Due to the large number of employees, about 12,000, and the distances between the various properties, it was a big undertaking. Most of the workmen are from the Sierra and for generations have been agricultural people, with little conception of modern tools and machinery, and to a large degree are illiterate. However, gratifying results have been obtained, as evidenced by the accident frequency curve during the sixteen-year period. Safety offices have been established in each of the six major properties, staffed by men who devote their entire efforts to inspections of working conditions and equipment, instructions as to safe methods, and investigations of accidents. The Corporation is a member of the Inter-American Safety Council, receiving their publications and literature, which serve to keep us up to date and informed on modern methods. Dissemination of this material is accomplished chiefly through word-of-mouth and bulletin boards. When it is found that the accident rate is increasing in a certain occupation, as for instance underground haulage or mine hoisting, the operators so engaged are assembled and given renewed instructions on the safety code pertaining to their work. Inter-camp competitions in accident avoidance are being conducted, with annual awards for that unit having the lowest severity rate for the year.

Jan 1, 1945

By James C. Fulton

Since publication of the First Edition of "Basic Open Hearth Steelmaking," in 1944, this book has been a major reference on the subject of steelmaking. The Second Edition of 1951 was so fundamental that it has retained its general usefulness to the present date. However, recently some of the material has been updated in connection with the writing of a companion book, "Electric Furnace Steelmaking." The sponsor of these two books, the Physical Chemistry of Steelmaking Committee, has felt that the new material should be made equally available to purchasers of either book. Accordingly the subject matter of Chapters 14, 15, and 16 of this new edition is duplicated by corresponding chapters in "Electric Furnace Steelmaking." It was also recognized that the use of oxygen in the open hearth and in the new basic oxygen processes represents a major development that should not be omitted from any basic reference. Thus the major new feature of this Third Edition is the supplement on "Oxygen in Steelmaking." The cooperation of the Iron and Steel Division&apos;s Acid Converter and Basic Oxygen Steel Committee (now merged to form the National Open Hearth and Basic Oxygen Steel Committee) is specifically recognized. In addition to the authors of chapters listed elsewhere, it should be noted that Arthur B. Wilder was the Committee Chairman. Although the changes in the Third Edition are important, the Committee cannot overlook the classic character of the Second Edition. This edition was edited by W. O. Philbrook and M. B. Bever in collaboration with H. B. Emerick and B. M. Larsen. It is anticipated that the Third Edition will maintain the value of the book until the current rapid changes in all basic steelmaking processes stabilize themselves sufficiently to justify a complete revision of the entire text in Part I. The experienced service of Wesley Burr in incorporating the new material in the index is also recognized.

Jan 1, 1964