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By Bartlett W. Paulding

Since its introduction to the petroleum industry in 1949 by Clark,1 hydraulic fracturing or "hydrafracing" has developed into a widely respected and useful technique for increasing production from petroleum reservoirs. Even then, Clark described production increases of from 6 to 100 barrels of oil per day (bopd). Since that time, others have described treatments in which production increased from 12 to 456 bopd, from only a show to 40 bopd;2 from 48 to 219 bopd; 3 from 500 to 1400 bopd and from a show to 192 bopd.4 Although representative of only a few of many successful hydraulic fracturing operational6 these increases in production attest to the past and potential value of the hydrafracing technique to the petroleum industry. The technique has received a considerable amount of theoretical and experimental attention.1, 5-20 Unfortunately, however, the degree of general understanding of the mechanics of hydraulic fracturing is still inadequate to solve many recurring problems. The practicing engineer is plagued with difficulties in predicting such factors as: (1) the required pressure and viscosity of the fracturing fluid to not only induce the fracture but to control the extent of its growth, (2) the strength characteristics and amount of proppant to include in the fluid so that the fracture is held open once the fluid pressure is decreased, and (3) the volume of the reservoir influenced by the induced fractures and the resulting increase in production. A major cause of these difficulties is the uncertainty associated with determining the orientation of the hydraulically induced fractures. One's natural conclusion in considering the problem is that the orientation of the fracture would depend on several variables, as, for example, the relationship between the viscosity and injection rate of the fluid and the

Jan 1, 1968

The Honor Roll includes the names of all members of the Institute Whom we know to have been on active military duty it the date of compilation, Mar. 5, 1919. Despite our efforts to have this list accurate and complete, some of our members who have been rendering military service are probably left off because of the fact that we have not been informed of their military connection. The list of men in military service has been compiled with great difficulty owing to the modesty of the members, who in their patriotism began their service but neglected to send us notice. In 1918, We published a separate Honor Roll of the Institute in which we included a list entitled "On active duty in other departments of the service" which contained the names of members who were rendering important emergency service to the Government other than in the Army. This list is entirely omitted this year because any list We might compile for this purpose would be entirely inadequate and must inevitably do injustice to a large number of our members who have been devoting great time and making many sacrifices for the benefit of the government along lines not within our ken. It is not too much to say that almost all our membership in this country has been, more or less directly, doing its uttermost for the successful prosecu¬tion of the war. The active work of many of these members we are Well aware of, as is also the rest of the civilized world. Faithful and wholehearted efforts on the part of many other members we have not been informed of, so that any list would be both incomplete and unsatisfactory.

Jan 1, 1923

The finding of gold, in enriching quantity, along the streams that issued from the western foothills of the Sierra Nevada was the prelude not only to the birth of an organized mining industry in California but to the intensive exploration of the entire Pacific slope; it presaged the feverish exploitation of the mineral resources that the ubiquitous prospector soon uncovered all over our western domain. At first when this migration began, as typified by the rush of 1849, there was no time to examine the signs of ore that were to be detected along the track of adventure, and, it must be added, not many in that motley crowd of gold-seekers were qualified to interpret the signs if they had lingered to look at them. Such intelligent curiosity as a few of them possessed was directed to the finding of gold chiefly, if not exclusively; and their good sense in this respect can not be impugned, because in a new and remote country the less valuable metals and minerals are unlikely to be worth the winning. Many of those that came to California crossed the alkaline wastes and sagebrush prairies that extend between the Great Sal? Lake and the ramparts of the snow-clad Sierra; when coming overland they found it convenient to halt on the eastern slope and to pitch their camp in the valley of the Car- son river before they began the tedious ascent of the mountains and the final entry into the land of gold. One of the trails most used by these immigrants followed the Carson river to the mountain meadows south of Lake Tahoe and then descended among the pine-woods of Placerville, where they went to work with pan and shovel in the gold-bearing streams

Jan 1, 1932

By A. M. Saddler, G. R. M. Del Giudice, Arthur F. Taggart, M. Hassialis

Flotation of sulphide minerals and native metals is no longer a practical difficulty. The underlying scientific principles of the method, although not explored in anything like complete detail, have been formulated with sufficient breadth so that the direction of attack on any specific case is clearly indicated. It has been known since the earliest days of flotation that certain of the nonsulphide nonmetal minerals—e.g., sulphur and graphite—would respond to flotation by oils as sulphides do; therefore they have been grouped with sulphides in many patents. But since the development of the chemical theory of collection,1,2,3 this similarity in action has been one of the facts cited in disproof of the theory by opponents of the hypothesis.4,5,6 Air levitation† of certain oxidized minerals, both metalliferous‡ and nonmetalliferous, and separation thereby from other oxidized minerals, is a recent development in practice, although the discovery of the method dates back 17 years7 This paper presents evidence that the principles underlying the air levita-tion of the nonsulphide nonmetal minerals are the same as those utilized in the flotation of the sulphides and native metals. It will be apparent immediately to anyone with knowledge of mineral concentration that separation of air-levitated minerals in water from minerals not so levitated is a simple matter of water-gravity concentration, the separating device employed depending solely upon the size of the particles treated and the buoyancy differences effected by the levita-tion. The usual separating means employed are: (1) a flotation machine for fine, slimy and for well aerated granular material; (2) shaking tables for granular less aerated material. By using large quantities of oil, it is possible to form substantially air-free oil-bound masses or granules of nonsiliceous minerals and to

Jan 1, 1939

By D. A. Summers, C. J. Haas, G. B. Clark, J. W. Brown

While significant advances have been made in excavation of rock, largely in improvements in drilling, blasting, loading, and haulage, conventional operations have been improved until little feasible increase in efficiency or rate of advance appears possible. Tunnel-boring machines have been developed which will excavate at rapid rates in soft to medium- hard rock. Hypervelocity impact is being intensively investigated as a possible means of cutting and breaking rock, as well as lasers, electric current, explosive drilling, high frequency vibration, etc. The current development and use of high-velocity small-diameter water jets, metallic jets, and projectiles of various materials involve ultra-high-pressure phenomena of fundamental interest. Rock disintegration by water jets has been investigated in the USSR for over a decade. Large-diameter jets of low velocity are used to mine coal, and high-velocity capillary jets will cut and break rocks under laboratory conditions. Velocity ranges for breaking and cutting are dependent upon rock and jet properties, and pulsed jets break some rocks more easily than continuous jets. Spectacular laboratory results have been reported for breakage of unconfined blocks of some types of rocks. Compressors, pressure multipliers, gas explosion chambers, and water cannons have been used to generate jets. Jet properties, such as continuity, unit pressure, total pressure, and stability have been measured. Results agree with theory, although the latter has been established only for relatively low-velocity flow. Diameter, speed of traversing, and frequency of pulsed jets affect rock response. Investigations in Britain have only recently begun consideration of harder rocks and higher velocities, although water jet cores have been found to be more continuous at lower velocities than previously believed. Lower limits of jet velocity for rock cutting were established for the rocks investigated.

Jan 1, 1970

By Sherwin Kelly

The prime objective of geophysical exploration is to promote the economical and rapid dis-covery of mineral or oil deposits of commercial value. To a few this concept as applied in min-ing may signify the direct discovery of ore-bodies, but to the geophysical engineer this latter Idea is one of the most insidious and detrimental misapprehensions which he has to combat. The destruction of this annoying obstacle to the progress of geophysical exploration reveals the kernel of truth behind it, that the exploration geophysicist has for the better part of two decades been concerned primarily with the discovery of mineral formations favorable to the occur-rence of commercial ore. There is a very real distinction here, since geophysical methods are capable of discovering certain mineral formations such as sulphide bodies or quartz veins, but are totally incompetent to predict whether or not they constitute ore; that is. whether or not they contain minerals of economic value in the amounts requisite to repay extraction. The art of geophysical exploration is now, however, rapidly outgrowing these early limita-tions. The rate of this growth will in large measure depend on the recognition by the mining industry of the fact that geophysics can play a role far wider and more important than it usual-ly does now, in guiding the future exploration and development of mineral deposits. It is my own firm conviction that as time marches on we will see the methods of applied geophysics turned more and more to the delineation of both minor and major structural features. The outlining of such features having a bearing on the probable loci of mineral deposition will be of inestimable value in guiding the development of a mining district. It is in this field that there will In-evitably occur a meeting and overlapping of the activities of the exploration geophysicists and

Jan 1, 1940

By Bevan Presley

THERE has been developed at Latouche a rather unusual system of mining which, for want of a better name, has been called the "Latouche system of mining." It is a modified form of shrinkage stoping applicable to orebodies of large or fairly large size where the ground is such that timbering would not be required in stoping. Mention has been made of this method of mining by Birch,1 who gave no details as it had been in use only a short time and the final outcome undetermined. The system, however, has proved to be entirely successful and it is thought that a paper covering it might be of general interest. Before proceeding with a detailed description of the "Latouche system" a brief description of the property and the various mining methods previously used will be given. LOCATION The Beatson mine of the Kennecott Copper Corp. is situated on the west coast of Latouche Island-, in Prince William Sound, Southwestern Alaska, 45 miles east of Seward, the coast terminus of the U. S. Government Railroad. It is a regular port of call for ships on the Southwestern Alaska run. The island is about 12 miles long and 3 miles wide. A ridge of mountains runs the entire length with a maximum elevation of 2500 feet. CLIMATE Latouche has to contend with possibly the greatest amount of precipitation on the North American continent. The annual average precipitation for the past 4 years has been 188 in., with 248 in. for the year 1926. A rainfall of 4 in. per day is not uncommon. In the winter the thermometer rarely falls below +20° F. and the snowfall is usually heavy during the months of March and April.

Jan 1, 1927

By T. A. Rickard

The province of Otago consists, roughly speaking, of the southern half of the South Island* of New Zealand. On three sides it is washed by the Pacific Ocean and on the north it abuts against Westland and Canterbury. It covers an area of over 20,000 square miles, and for the most part has an extremely broken surface; the narrow plains of the sea-board are bounded by the rounded foothills which in turn are overlooked by range after range of the snowy summits whose varied beauty has made the island known as the Switzerland of the southern hemisphere. The gold-fields are confined to the quartzose schists which, in a broad band, 70 to 75 miles wide, cross the district, extending in a northwesterly direction from the shore of the western ocean into the northern provinces. These quartzose schists are the characteristic rocks of Otago, and to their curious structure are due the interesting differences exhibited by the mining districts in the modes of occurrence of the gold. These rocks, which are almost unbroken over their full extent, have been divided by the Provincial Geologist, F. W. Hutton, into two series of beds, named respectively the Wanaka and Kakanui formations. The only reason given for this division is the desire " to divide such an enormous thickness of rocks in order that the map might display somewhat of the geological structure of the district." As Hutton and others have pointed out, there is in fact no dividing line. The changes noticeable in the ascending series of schists are very gradual, and are due to the slowly decreasing effects of metamorphism. Hutton estimates the thickness of the Wanaka series at as much as 50,000 feet, and the

Jan 1, 1893

By Kenyon Burch

ONE of the advantages presented by electric drive in many classes of work is the ease with which the electric motor can be controlled automatically. In a large number of cases certain features of the control are automatic-for example, the rate of acceleration may be limited automatically or the equipment may be stopped automatically at the limit of travel-but the equipment is started and ordinarily is stopped by hand. . In other cases the motion of the machinery is utilized to start, control the: speed, and stop the motor automatically, independently of any operator. A considerable proportion of the large mine hoists now in use have certain automatic features, particularly protective devices against over-winding, and, in some classes of electric hoists, devices for preventing excessive acceleration or retardation. The large automatic hoists discussed in this paper, however, are completely automatic, i.e., capable of snaking their trips without the presence of an operator at the control levers. According to circumstances, various advantages may be obtained by automatic control, chief of which are decreased power consumption', increased precision and safety of operation, and decreased, cost of attendance. The first step in the analysis of a prospective automatic mine hoist is to determine whether automatic operation is feasible at all. If men are to be hoisted, or levels changed, the attention of an operator is required for these purposes; but tinder some conditions it may be entirely practicable and advantageous to build the equipment so that, while provision is made for hoisting mien or changing levels, ore can be hoisted automatically from, any one level. If, however, an operator's attention is required every few minutes for changing levels, handling men or drills, or other work requiring hand control, it is obvious that automatic operation between times will not be of any, practical benefit.

Jan 3, 1916

By M. A. Whiting, H. Kenyon Burch

One of the advantages presented by electric drive in many classes of work is the ease with which the electric motor can be controlled automatically. In a large number of cases certain features of the control are automatic—for example, the rate of acceleration may be limited automatically or the equipment may be stopped automatically at the limit of travel—but the equipment is started and ordinarily is stopped by hand. In other cases the motion of the machinery is utilized to start, control the speed, and stop the motor automatically, independently of any operator. A considerable proportion of the large mine hoists now in use have certain automatic features, particularly protective devices against overwinding, and, in some classes of electric hoists, devices for preventing excessive acceleration or retardation. The large automatic hoists discussed in this paper, however, are completely automatic, i.e., capable of making their trips without the presence of an operator at the control levers. According to circumstances, various advantages may be obtained . by automatic control, chief of which are decreased power consumption, increased precision and safety of operation, and decreased cost of attendance. The first step in the analysis of a prospective automatic mine hoist is to determine whether automatic operation is feasible at all. If men are to be hoisted, or levels changed, the attention of an operator is required for these purposes; but under some conditions it may be entirely practicable and advantageous to build the equipment so that, while provision is made for hoisting men or changing levels, ore can be hoisted automatically from any one level. If, however, an operator's attention is required every few minutes for changing levels, handling men or drills, or other work requiring hand control, it is obvious that automatic operation between times will not be of any practical benefit.

Jan 1, 1917

By Frank H. Riddle, Wilfrid R. Foster

GENERAL treatment of the various minerals of importance in refractories appears in the chapter entitled "Refractories" elsewhere in this volume. The present chapter is restricted to a discussion of minerals of the sillimanite group and brings up to date the excellent information contributed by Prof. Paul F. Kerr to the first edition (1937). Since the appearance of that edition, the status of the group has changed some- what. Kyanite remains the preferred source material for mullite refractories but total consumption of kyanite has increased considerably.85 The exigencies of World War II forced an increased dependence on domestic sources and led to an intensification of the search for higher-grade deposits of kyanite and allied minerals. The first discovery of massive kyanite similar to that of India has been reported from Georgia.37 British East Africa has joined India as a substantial supplier of our imported kyanite, but that from India continues to hold preference.85 During World War II, prices of both domestic and foreign grades reached peaks unparalleled since the earliest years of the use of kyanite and as yet have shown no tendency to return to prewar levels. Topaz, by virtue of the deposit outlined in South Carolina, merits inclusion in the group.20,36,95 Large andalusite deposits, which threaten to rival our one large domestic occurrence, have been found in Russia.69,88 Sillimanite has not yet attained an important position among these useful minerals because of the lack of accessible deposits of high-quality material in adequate supply.37,50,58 Tests by the Bureau of Mines have indicated the possibilities of economically beneficiating low-grade sillimanite and kyanite.105.106,140 Government, university, and industrial

Jan 1, 1949

By F. C. Blickensderfer

During 1914 and 1915, extensive experiments were conducted at the concentrator of The Detroit Copper Mining Co. of Arizona, at Morenci, Ariz., in order to test the relative grinding efficiencies of the Marathon, the Chilean and the Hardinge Mills. The Marathon mill used in the experiments was the first one ever built by the manufacturers; and since this was the first time that it was given a thorough tryout, with such remarkable results, the data have been assembled in the following paper and submitted in the interests of the milling profession. Description of the Flow Sheet The concentrator flow sheet, as it existed at the time of these tests, is shown in Fig. 1. The total mill feed, as delivered from the crushing plant, had as its maximum size 1-in. material. This material was screened dry on Cole Zig-Zag screens fitted with 4-mesh openings; the oversize going to one pair of coarse rolls, the undersize to five Wilfley tables fitted with Butchart National riffles. The coarse-roll product was elevated and screened wet on Zig-Zag screens fitted with 4-mesh openings, the undersize going to the five tables mentioned above and the oversize to one pair of fine rolls. The fine-roll product was elevated and screened together with the coarse-roll product; so that, before any concentrating operations took place, the total mill feed was reduced to pass a 4-mesh screen. After concentration on Butchart-riffled tables, the tailings from these tables passed to de-sliming hoppers, where two products were formed, viz., an overflow and a discharge. The discharge constituted the feed for the Chilean mills. It contained 16 per cent. slime (—200 mesh) and 3 parts of water to 1 of solids. The concentrator was equipped regularly with four Chilean mills (Monadnock type) to the unit; but, in order to

Jan 1, 1917

By Tomoyuki Moritani, Atsuyuki Mizuno

A concentration of manganese nodule varies areally from 0 to 30 kg/m2 in the central-eastern deep sea bottom of Central Pacific Basin with depth of 5,600-5,900m, but generally it is low, mostly of the abundance order from 0 to less than some kilograms per square metres through the bottom. A high concentration over about l0kg/m is localized to the northwestern basin, besides "St. 414 Deep Sea Hill" and “GH 76-1 Trought”, and also it is likely related with the substratum of deep sea clay. Nodules are tentatively classified into nine types of Sr, SPr, SEr, Db, Ss/SPs, ISs, IDPs and V, in terms of morphology and surface feature. The types may be related with internal structure, nuculeus, mineral composition, chemical composition, occurrence and areal distribution, and might have resulted from various environmental factors of nodule genesis. The abundance of nodule at each station shows the interesting relation with acoustic records by 3.5KHz and seismic reflection profilings. In both the records, thick transparent layer over about 45m thick yield neither any nor significant amount of nodule. The layer less than 45m relates with abundant nodules up to 30kg/m2, though it yield also very little nodule in some cases. The relation suggests that the formation of nodule most likely could be related with the accumulation rate of the post-middle Eocene sedimentary sequence to some extent and also with other controlling factors. The relation can lead us to the tentative delineation of distribution of nodule deposits in the area. The comparative-consideration with the deposits in GH 74-5 area, just east- ward of the present area, shows the areal peculiarity of nodule genesis in deep sea bottom. The results of chemical analyses will be discussed elsewhere.

Jan 1, 1976

By Charles V. Seastone

The hydro-electric plant of the Peninsular Power Co. is located at what is commonly known as Lower Twin Falls on the Menominee River. This location is about 3I/2 miles north of the city of Iron Mountain, Mich. The principal points of delivery of electric energy from this plant are in the mining regions adjacent to Florence, Wis., and Iron River, Mich., and in the cities of Iron River and Iron Mountain. The hydro-electric plant at Twin Falls and the substation of the Iron Mountain Electric Light & Power Co, are connected by a 6,600-volt transmission line carried on steel towers and steel poles, the latter being used within the city limits. The plant at Twin Falls and the substation at Iron River, about 36 miles distant, are connected by a 66,000-volt, duplicate, three-phase transmission line, supported on steel towers. At Iron River, are located a 1,500-kw. auxiliary steam plant, and the substation, from which the current is distributed to the mines in this vicinity. A description of the auxiliary plant, main and customers' substations, and of the main and secondary transmission lines, follows later in this paper. General Layout The relative location of the dam, forebay, and power house will be understood by referring to Fig. 1. The dam is constructed on a ledge of solid rock which forms Lower Twin Falls. This rock ledge offers an excellent location in that the height of the dam, and therefore the amount of concrete, are thereby reduced, and also in that practically no pumping was required in unwatering the dam site. The maximum head provided by the dam is 44 ft., with an average working head of from 40 to 42 ft. The other structures, including the substructure of the power house,

Jan 1, 1915

By Alex McCoy

SAMPLING of the fluid from oil wells for percentages of oil, emulsified oil, and water during the last two years has brought out some interesting facts concerning oil-water emulsion. This result led to a laboratory investigation of emulsion, which substantiated the conclusions made from the field observations. The purpose of this paper is to present the information collected, the laboratory experiments, and our interpretation of the same. In order to define emulsified oil exactly, give its synthesis and origin, and to show how and when it is formed in the wells, the work was necessarily divided into two separate lines-laboratory work and field observations. It is hoped that this study may lead to a discussion of such points so that the petroleum engineer, geologist, or technologist may be benefited by its practical bearing on oil-field management. Special credit is due Mr. Everett Carpenter, chief geologist of the Empire Gas & Fuel Co., for his assistance and cooperation in this work. LABORATORY INVESTIGATIONS ON EMULSIFIED OIL Laboratory investigations were conducted in an attempt to learn the composition and some of the properties of emulsified oil, or B. S., as it is more commonly called, also to demonstrate, by laboratory methods, how B. S. may be formed under conditions similar to those existing at the time a well is being pumped, and how it may be broken down. Literature bearing on this subject is widely scattered and very limited in scope. Bacon and Hamor define B. S., or bottom settlings, as "earthy matter, inert organic matter, or, in the case of Pennsylvanian petroleum, an emulsion of paraffin wax and water, which accompanies crude oil." In this discussion we will limit the term B. S. to that heavy,

Jan 8, 1919

By Hallet R. Robbins

Korea, the ancient" Hermit Kingdom," is a peninsula jutting out from the coast of eastern Asia. By the natives it is called " Chosen," nfhich, translated, means " Land of the Morning Calm." It lies between the Yellow sea and the Sea of Japan. On the north it is separated from Manchuria and the Russian province of Primorsk by the Yalu and Tiumen rivers; on the south the Korcan straits interpose a rough voyage of 120 nliles to the nearest point in Japan. The entire country is situated between the parallels of 34O and 42O N. latitude. The surface of the country is made up of successive ranges of ul~glaciated mountains, separated by narrow, fertile, and more or less densely populated, valleys. Through all the obscure centuries of its history, Korea has succeeded in maintaining a monastic seclusion, over which, from time immeniorial until the late Chino-Japanese war in 1894, China exercised a shadowy sovereignty. Although Korea had been forced into slight foreign contact previously, her first forcign treaty was signed with Japan in 1876. Under the restraining guardianship of China, the Japanese treaty bore but infiignificant innovations for Korea; but when, in 1883, a treaty was made with the United States, the first of the western nations, a decade after the American gunboats, under Commodore Rodgers and Lieutenant Schley, forced their may up the Salee river, Korea awoke from her sleep of 4,000 years. The Eorean peninsula suddenly became the arena where the enterprises and individuals of many foreign nations met in fiercest rivalry. Out of this struggle grew two singularly successful American enterprises, both of which have played an important part in developing the natural resources of the country. The first, and best known of these, is the Oriental Consolidated Mining Co., which was organized by Lcigh Hunt

Jan 1, 1909

By Richard Smith

After a brief history of the phosphate industry of Tennessee, the distribution and origin of the phosphate rocks are described. Then the mining and treatment, together with costs of production, and the uses of the rocks are given. THERE are three distinct varieties of phosphate rock, in Tennessee, known commercially as: (a) the "brown" rock, which is the residual product of the weathering and natural concentration of certain phosphatic Ordovician limestones; (b) the "blue" rock, which is an unaltered phosphatic stratum of Mississippian or Devonian age; and (c) the "white" rock, which is the result of chemical replacement and deposition. Before 1894, South Carolina and Florida had supplied most of the phosphate of the United States, South Carolina leading until that date and Florida from then until the present time. In December, 1893, the blue phosphate of Tennessee was discovered almost simultaneously on Swan Creek, in Lewis County, by two independent parties-by one as the result of a careful and systematic search for a workable deposit of the long known kidney phosphate, and by the other through mistaking it for a "bloom" of coal. Leases were taken and, with further prospecting disclosing other deposits in the region, the development progressed as rapidly as could be expected without railroad transportation. In January, 1896, Judge S. Q. Weatherly, who was interested in the development of the blue phosphate, while riding along the road south of Mt. Pleasant, noticed some slabs of a brown rock in place above the limestone. He took samples, and had them analyzed, thus discovering the high-grade brown phosphate of this district. This discovery was kept a secret until July, 1896, when mining was started at the village of Mt.

Jan 9, 1924

By H. W. Graham

[ ] Even though we have a small audience, I am sure there are some here who are interested in sponge iron. It is a large subject, with a lot of economic interest, and one that will continue to grow in importance as the years go by and as the conditions that urge action in that direction increase. The authors have chosen to deal in this paper with one particular narrow phase of a long program of work by the Bureau of Mines. Before asking for any general discussion, I would myself like to ask Mr. Buehl if he would tell us just a little bit about the mechanism of discharge and the form in which the material was discharged; that is, when dolomite is added, what happens to the dolomite? R. C. Buehl (author's reply)-You are interested in the equipment that was used? H. W. GRAHAM-No, just the product. R. C. Buehl-The product was in granular form, of a shape very similar to that of the ore used. Using minus 10-mesh ore, the product is essentially minus 10-mesh, mixed with the coal and dolomite. It is then passed through a belt type of magnetic separator, which picks up the magnetic iron and allows the dolomite and coal to fall off. If the coal is sufficiently valuable, it can be separated from the dolomite and, provided the coal has a sufficiently low ash content, it can be reused. For instance, if a low-ash reducing agent like petroleum coke is used, it can be reused until all the carbon is consumed. H. W. Graham-That clears the point for me. I was not quite sure whether the experi-

Jan 1, 1947

By C. H. Mathewson

(New York Meeting, February, 1916) DURING the past year considerable work dealing with the mechanical properties and microstructure following the anneal under uniform conditions of certain types of commercial rolled brass has been done in this laboratory. Since these experiments were conducted with the active cooperation of the Bridgeport Brass Co., involving free use of its product, and have thus furnished information which is characteristic of some of its special mixtures, full publication of the numerical relationships and comparative results encountered does not seem justifiable. Some of the more general features of this work are, however, available and it is our present purpose to use the material in question, along with some results of special tests, in discussing the characteristics of recrystallization as related to the degree of hardening by strain and the ordinary annealing variables. We desire to make acknowledgment of the many courtesies extended by Mr. Charles Ferry, Metallurgist of the Bridgeport Brass Co., and the value of his cooperation, which has greatly stimulated the study of brass in this laboratory. A clear and systematic presentation of the principal relations between temperature and time of anneal, the changing physical properties and microstructure and the degree of previous reduction by cold-rolling, was first made, in the case of rolled brass and copper, by the French engineer, C. Grard,1 in 1909, although much fragmentary information of this general character had appeared earlier and the main facts involved were undoubtedly known to many brass specialists through their own private research. From this work, it appears that in the cartridge mixture (67 per cent. copper, 33 per cent. zinc) the properties imparted by cold-working within the limits, 13 to 75 per cent. reduction of area by rolling

Jan 1, 1916

By C. E. Lesher

Low-TEMPERATURE carbonization needs no introduction to the literature on coal. This paper will attempt no review of that literature; it tells the story of the commercial development of one of the processes for carbonizing coal at so-called low temperatures, dealing with the technology and economics of the process rather than with the design of equipment. The process used is that covered by the patents of C. B. Wisner, with improvements and changes made by the Pittsburgh Coal Carbonization Co. The important and novel feature of the process is the phenomenon of making the product in ball form (Fig. 1). Melting coal dust into smokeless solid fuel in an apparatus as simple as a revolving cylinder of ordinary mild steel has been proved to be practical. Furthermore, it has been found that the process has a wide application, for by applying a knowledge of why and how this balling action is accomplished, the apparatus can be designed and adapted to treat any coal that has a certain minimum agglutinating property. The operating plant is 20 miles west of Pittsburgh, adjacent to the Champion preparation plant of the Pittsburgh Coal Co. The coal used is cleaned minus 3/8 -in- or finer sizes. The products are low-tem-perature coke, tar and tar products. Present capacity is 7000 tons per month of low-temperature coke and 140,000 gal, of tar. There is no surplus gas for sale, and none of the light oils are stripped from the gas. The coke is marketed in two sizes, 1 to 2 in. and 1 to 6 in., through retail coal dealers for domestic con-sumption in hand-fired furnaces, and for fireplace fuel. The smaller size is bagged by dealers. Crude tar and many distillates and road tars are sold.

Jan 1, 1940