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By Ralph Nichols

THE mines are near the town of Gilmore, in the Texas mining district. This district was organized in 1880. The present producing mines are near the terminus of the Gilmore & Pittsburg railroad. This railroad connects with the main line of the Oregon Short Line at Armstead, Mont. The distance from Gilmore to Armstead is 70 miles. The town of Gilmore is near the head of the Lemhi river at an elevation of 7,000 ft., while the mines are from 400 to 1,300 ft. higher. The range of mountains upon which the mines are situated forms the water shed for the Little Lost river on the west and the, Lemhi river on the east. The winters are severe and the snow fall is heavy, but the mines ship right through the year. There is an abundance of timber suitable for all mining purposes in the immediate vicinity. Water is piped into the camp from a lake about 2.5 miles distant. This lake is about 1,400 ft. above the town of Gilmore. The water is exceptionally good for boiler and domestic purposes. The mining companies now producing are. the Pittsburg Idaho Co., Ltd. ; the Latest Out Mining & Smelting Co:, Ltd. ; and the Gilmore Mining Co., Ltd. Besides the above properties, there are a number .of prospects in different stages of development. The producing mines of the district are fissures in limestone, with a general northeast-southwest course .and a dip to the west of from 40° to 70°. These fissures are at about right angles to the bedding of the limestones. The veins are regular and the ore shoots strong, both laterally and in depth, so far as developed. The ore shoots have a rake or pitch to the south. The character of the formation is shown in Fig. 1, a section of the Latest Out mine.

Jan 11, 1913

By Ralph Arnold

Since 1915, when Elk Basin field was brought in, eight oil fields have been developed in Montana and the production has arisen from 50,000 bbl. in 1916 to 8,000,000 bbl. in 1926. The production for 1927 was 5,121,600 bbl. and the total up to the end of 1927 was 27,138,239 barrels. The eight fields, with their year of discovery are: Elk Basin, Carbon County (1915); Devil's Basin, Petroleum County (1919); Cat Creek, Petroleum County (1920); Soap Creek, Big Horn County (1921); Kevin-Sunburst, Toole County (1922); Lake Basin, Stillwater County (1924); Pondera, Pondera and Teton counties (1927); and Bannatyne, Pondera and Teton counties (1927). About 170 wildcat wells have been drilled in the state of which 8 were successful and 162 gas wells or dry. Hence, only one out of 21, or 5 per cent. of the wildcats have been successful. The average depth of the wells has been 1600 ft. and the average cost $32,000 apiece. • Up to Jan. 1, 1927, a total of 1376 wells have been drilled in the producing oil and gas fields of the state, of which 904, or 66 per cent., were successful oil wells; 82, or 6 per cent. were gas; and 390, or 28 per cent, were dry. The percentage of dry wells is excessive as compared to the wells in other states, due to the uncertainties of limestone reservoir rocks. The total production of oil to Jan. 1, 1927, has been 22,016,639 bbl. and of gas 7,265,330,000 cu. ft. The average price at the well for the oil has been $1.47 per bbl. and for gas about 4 c. per 1000 cu. ft. The value at the point of consumption has been about 23 c. per 1000 cu. ft. The total revenue derived from crude oil has been $32,277,119, and from gas 8350,613, or a total income to the producer of $32,727,832. Each well drilled in the state has already (to Jan. 1, 1927) averaged a return of over $21,000. The total number of domestic (Montana) oil and gas companies organized, since the first in 1885, has been 844, of which 702 are still alive and 142 dead. Oil and gas companies registered for operation within the state to Jan. 1, 1927, but with outside charters, are 143, of which 66 are alive and 77 are dead. Outside the few distributing companies, which are included in these figures, the grand total of 997 companies which have

Jan 1, 1928

By M. A. Hunter

CHAIRMAN M. A. HUNTER. UP to this time our stress-corrosion sessions have been concerned with stress-corrosion cracking in brass. In the succeeding sessions a variety of other products which are susceptible to stress-corrosion cracking are to be considered and this afternoon's session is to be devoted to stress-corrosion cracking in light metals. The problems you have had to deal with up to now in brass have been very simple ones. From this time on the complexities become greater. You have already learned in the preceding sessions, that copper is not susceptible to stress-corrosion cracking and when you begin to alloy it with 3 per cent or larger proportions of zinc, then stress- corrosion cracking ensues. You apparently have few complications in the copper alloys you make. There is apparently no precipitation on the grain boundaries in the brass, and no precipitation within the metal itself. So, on the whole, the problem is a simple one. Yet it has been with the brass people for a very long time and it is apparently not yet settled from the fact

Jan 1, 1945

By Bernard K. Asdell

Georgia, a state seldom considered to be an important mineral producer, has one surprising feature-it is the nation's largest producer of kaolin. Kaolin is a highly important raw material in the paper, rubber, ceramic whiteware, paint and chemical industries. In 1965, more than 2.7 million tons of kaolin were produced in this state, a 150,000-ton increase over the preceding year, and production continues to climb. Strictly defined, the term "kaolin" applies to a group of hydrous aluminum silicates in which kaolinite is the predominant mineral. Kaolinite is inherently white, non-abrasive, chemically inert, and of a very fine particle size, ranging from sub-micron to 40-microns equivalent spherical diameter. An electron-micrograph of kaolinite is shown in Fig. 1. The particles finer than about 2 microns are thin, elongated plates, hexagonal in outline. The larger particles, coarser than 2 microns, are predominantly vermicular in outline with a foliated structure. Table I shows a typical chemical analysis of commercial, wet-processed kaolin compared to pure kaolinite.

Jan 11, 1967

"The Murray Plant of the American Smelting & Refining Company is situated seven miles south of Salt Lake City, and has a fine view of the Salt Lake Valley with its fertile farms and orchards.It is located on the Los Angeles & Salt Lake and Denver & Rio Grande Western Railroads, and has a fine electric car service, cars running every 15 minutes.The beautiful and majestic Wasatch Range lies about five miles to the east and the Oquirrh Range to the west, and from these mountains a large proportion of the ores treated are obtained.The location is very central, ores coming to the plant from all directions. Park City, where a large tonnage of high grade silver-lead ore is obtained, lies to the east and the camp of Alta is just across the mountains from Murray.To the west is the wonderful camp of Bingham, which produces a large tonnage of lead ores, in addition to its immense tonnages of copper ores, which are treated at Garfield.Tintic, to the south, sends in quantites of dry silicious ores, as well as silver-lead ores.Besides the above, ores are shipped to the plant from Stockton, Ophir, Milford and other camps in Utah, as well as from Nevada and Idaho, and also some ores from Cali¬fornia, Oregon, Washington, Wyoming and Colorado.The American Smelting & Refining Company took possession in 1899 of its Utah properties which consisted of the following plants, all of which have been dismantled:"

Jan 1, 1925

By C Gunther

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

Mining examinations are of several kinds and the scope of the investigation depends in each case upon the purpose for which the examination is made. A formal examination of a developed mine is an expensive undertaking; from one to several months are allowed for the work according to the size of the property; many samples are taken; investigation is made of the geological features, including, perhaps, a topographical and geological survey of the surface; the metallurgical treatment of the ore is studied; finally, a determination of costs is demanded. Formal examinations are made for prospective purchasers or as a basis for the consolidation of several properties, and occasionally, in the owner's behalf, to verify the work of resident engineers, or to determine the readiness of a mine for equipment and the kind and capacity of equipment it shall receive. A formal examination of a mine should not be undertaken until a preliminary examination has shown that it is justified. It is regrettable that some engineers are in the habit of prosecuting long and exhaustive examinations of properties whose lack of merit should be, and perhaps is, apparent from the start, or of continuing their investigation long after an unfavorable result is seen to be inevitable. This wasting of a client's money is a species of trickery difficult to prove, and therefore the more contemptible. Preliminary examinations are precisely what the term implies, and are undertaken to determine the advisability of making

Jan 1, 1932

IRVING. PERRINE, Hutchinson, Kans.-I think in reading this paper one should hear in mind its relation to Dr. David White's paper on "Some Relations in Origin between Coal and Petroleum."' In that paper he discusses the relationship between the percentages of fixed carbon in the coals, the gravities of the oils, and commercial gas possibilities. His paper has a map showing certain areas which Dr. White believes to be hopeless as far as oil and gas possibilities are concerned. THE CHAIRMAN (C. W. WASHBURNE, New York, N. Y.).-I. would like to emphasize one point brought out by Professor Schuchert.2 The southern hemisphere has had an exceedingly monotonous geological his-tory, except the northern border of Africa, the eastern border of Aus-

Jan 12, 1919

By J. A. Barr, R. B. Burt, I. S. Tillotson

THE pumping of solids in water suspension is an important part of many metallurgical and mining operations. In most cases, it is still in the rule of thumb category for which no universal formula has been developed, and much research is needed. Because of the limited and incomplete data available, this article may be classed as an experience paper, which is presented with the hope that some contribution will be made toward the development of the so-called universal formula. This formula, if and when developed, may be evolved from several factors, many of which are not now available for general application. The designing engineer is interested in obtaining accurate forecasts on: 1—the minimum velocities needed to prevent choke-ups in the pipeline, which in turn dictates pipe sizes, 2—power required for pumping, 3—pump selection. The basic factors for a given problem will include: 1—weight per unit of time of solids to be handled, 2—specific gravity of solids, for calculation of volume, friction and power, 3—screen analysis of solids with the colloidal acting, i.e., the slime fraction, a very important factor, 4— shape of particle or some means of determining a friction constant, 5—effects of percentage of solids, 6—development of a viscosity factor to be used in the overall calculations, 7—calculation of the lower limits of pipeline velocities permissible, 8—calculation of total head, pump horsepower, and 9—setting up of pump specifications. In certain limited cases horsepower and total heads and minimum velocities may be computed and a suitable pump selected from basic data, but in many cases, as in mining of Florida pebble phosphate, experience rather than a hydraulic formula still should be used as a basis of selection. Pumping Florida Pebble Matrix Pumping at the Noralyn mine of International Minerals and Chemical Corp. will be used as an example. Other areas will vary as to the characteristics of the matrix, especially the slime content. A typical screen analysis of this matrix is: +14 mesh, pebble size,* 2.1 pct; —14 +35 mesh, 11.4 pct; -35 +I50 mesh, 60.5 pct; -150 mesh, 25.0; total, 100 pct; moisture in bank, 20.0 pct; weight per cu ft in bank, 120 lb. The —150 mesh fraction may increase to as much as 35 pct in adjacent areas. When thoroughly elutriated, the matrix has a relatively slow settling rate, which is an important factor in permitting lower pipeline velocities without choke-ups. Exact data is not available to evaluate settling rates. For a factor of 100 a suspension of clean building sand in water is suggested. When pumping long * Pebble is a commercial designation for the coarser fraction of finished phosphate from a washer, usually +14 mesh. distances, a quick settling matrix allows the coarser solids to settle out along the bottom of the pipeline, causing drag, turbulence, and increased friction. With a slow settling matrix as at Noralyn, turbulence acts to keep the solids in suspension at a lower friction head, regardless of the pumping distance. When the pebble content of the matrix, i.e., the + 14 mesh fraction, is in excess of 10 pct of the total solids, trouble may be expected from settling out even in normal pumping distances. To prevent choke-ups and maintain tonnage, an additional pump must be added in the long runs, where one pump would otherwise be satisfactory. A typical pulp handled is: total volume, 7800 gpm; water, 4500; solids pumped per hr, 4200 lb; sp gr pulp, 1.4; percent solids in pulp, 46.; pipe size, 16-in. ID; pulp velocity, 12.85 fps; probable critical velocity, 10 fps, as below this minimum velocity choke-ups would be numerous. In calculating friction heads the Armco handbook is used where a roughness factor based on 15-year-old pipe is set up. Because the pipe used in pumping matrix is smooth and polished because of the scouring action of the phosphate and its silica content, the head losses in the Armco table for water are practically the same as in pumping the Noralyn matrix through smooth pipe, plus the fact that conditions vary widely over short periods, making accurate determinations difficult to obtain. New pumps and pump changes are being tested continuously and a wealth of data built up. This has resulted in a substantial improvement and lower relative costs in pumping matrix. The Florida phosphate industry is constantly seeking to offset higher wage and material costs with improved technique. Until a few years ago a 12-in. discharge pump was commonly used, with heads as low as 80 ft. Sizes have gradually increased and heads more than doubled. For example, the following pump was placed under test at the Noralyn mine: make, Georgia Iron Works; size, suction 16 in., discharge 14 in.; impeller, 39-in. diam; motor, 600 hp, slip ring; full load speed, 514 rpm. The results were increased head, higher capacity than the older design, with fewer pumps in the line from mine to washer.

Jan 1, 1953

By R. B. Burt, J. A. Barr, I. S. Tillotson

THE pumping of solids in water suspension is an important part of many metallurgical and mining operations. In most cases, it is still in the rule of thumb category for which no universal formula has been developed, and much research is needed. Because of the limited and incomplete data available, this article may be classed as an experience paper, which is presented with the hope that some contribution will be made toward the development of the so-called universal formula. This formula, if and when developed, may be evolved from several factors, many of which are not now available for general application. The designing engineer is interested in obtaining accurate forecasts on: 1—the minimum velocities needed to prevent choke-ups in the pipeline, which in turn dictates pipe sizes, 2—power required for pumping, 3—pump selection. The basic factors for a given problem will include: 1—weight per unit of time of solids to be handled, 2—specific gravity of solids, for calculation of volume, friction and power, 3—screen analysis of solids with the colloidal acting, i.e., the slime fraction, a very important factor, 4— shape of particle or some means of determining a friction constant, 5—effects of percentage of solids, 6—development of a viscosity factor to be used in the overall calculations, 7—calculation of the lower limits of pipeline velocities permissible, 8—calculation of total head, pump horsepower, and 9—setting up of pump specifications. In certain limited cases horsepower and total heads and minimum velocities may be computed and a suitable pump selected from basic data, but in many cases, as in mining of Florida pebble phosphate, experience rather than a hydraulic formula still should be used as a basis of selection. Pumping Florida Pebble Matrix Pumping at the Noralyn mine of International Minerals and Chemical Corp. will be used as an example. Other areas will vary as to the characteristics of the matrix, especially the slime content. A typical screen analysis of this matrix is: +14 mesh, pebble size,* 2.1 pct; —14 +35 mesh, 11.4 pct; -35 +I50 mesh, 60.5 pct; -150 mesh, 25.0; total, 100 pct; moisture in bank, 20.0 pct; weight per cu ft in bank, 120 lb. The —150 mesh fraction may increase to as much as 35 pct in adjacent areas. When thoroughly elutriated, the matrix has a relatively slow settling rate, which is an important factor in permitting lower pipeline velocities without choke-ups. Exact data is not available to evaluate settling rates. For a factor of 100 a suspension of clean building sand in water is suggested. When pumping long * Pebble is a commercial designation for the coarser fraction of finished phosphate from a washer, usually +14 mesh. distances, a quick settling matrix allows the coarser solids to settle out along the bottom of the pipeline, causing drag, turbulence, and increased friction. With a slow settling matrix as at Noralyn, turbulence acts to keep the solids in suspension at a lower friction head, regardless of the pumping distance. When the pebble content of the matrix, i.e., the + 14 mesh fraction, is in excess of 10 pct of the total solids, trouble may be expected from settling out even in normal pumping distances. To prevent choke-ups and maintain tonnage, an additional pump must be added in the long runs, where one pump would otherwise be satisfactory. A typical pulp handled is: total volume, 7800 gpm; water, 4500; solids pumped per hr, 4200 lb; sp gr pulp, 1.4; percent solids in pulp, 46.; pipe size, 16-in. ID; pulp velocity, 12.85 fps; probable critical velocity, 10 fps, as below this minimum velocity choke-ups would be numerous. In calculating friction heads the Armco handbook is used where a roughness factor based on 15-year-old pipe is set up. Because the pipe used in pumping matrix is smooth and polished because of the scouring action of the phosphate and its silica content, the head losses in the Armco table for water are practically the same as in pumping the Noralyn matrix through smooth pipe, plus the fact that conditions vary widely over short periods, making accurate determinations difficult to obtain. New pumps and pump changes are being tested continuously and a wealth of data built up. This has resulted in a substantial improvement and lower relative costs in pumping matrix. The Florida phosphate industry is constantly seeking to offset higher wage and material costs with improved technique. Until a few years ago a 12-in. discharge pump was commonly used, with heads as low as 80 ft. Sizes have gradually increased and heads more than doubled. For example, the following pump was placed under test at the Noralyn mine: make, Georgia Iron Works; size, suction 16 in., discharge 14 in.; impeller, 39-in. diam; motor, 600 hp, slip ring; full load speed, 514 rpm. The results were increased head, higher capacity than the older design, with fewer pumps in the line from mine to washer.

Jan 1, 1953

By G. Carman Ridland

A program of exploration for radioactive deposits, conducted in 1945 in the well-known mineralized areas of the Front Range, Colorado, was rewarded with the discovery of pitchblende in a dump at Caribou Hill. The presence of pitchblende in. the silver veins at depth apparently is not expressed as gamma-ray anomalies at the surface.

Jan 1, 1950

By C. W. Baxter

Eveleth Taconite Co. was formed in 1963 to mine and beneficiate taconite on the Mesabi Range. Its Thunderbird mine is located mid-way between the cities of Eveleth and Virginia, Minn. The program for blasting restraints here is unique not only on the Mesabi Range but possibly in the world. The ore is a hard siliceous taconite. Its structure varies from bedded to massive with prominent vertical jointing. The jointing of the top or outcrop of the orebody is a challenge for the blasting practices as it is the source of an estimated 75% of the secondary breakage.

Jan 11, 1972

THE CHAIRMAN ( F. K. COPELAND, * Chicago, ,Ill.).-This is an interest-ing and very troublesome proposition to all of us. Ten or fifteen years ago, when the old-fashioned idea prevailed that a man was responsible for his own health and safety, that if anything happened to him it was his own lookout; we got along without this problem; but with the advent of accident compensation, with the agitation that there is all the time for pensions, sick benefits, and the responsibility of a company for the health of its employees, whenever you take a man on, that phase is becoming more and more important. One cannot afford to hire a man who is blind in one eye, even though he may have perfect sight in the other eye; if he loses that one eye, if lie becomes a total disability, the company is liable for the man's complete sight. Another thing that should make us particularly interested in this problem is the fact that the unions are very much opposed to it. One of the requirements of this steel unpleasantness is that the companies abandon their physical examination of employees. It is a very difficult problem to examine 400 or 500 men as intelligently as possible and decide whether a man on this or that side of the line is accepted. T. T. READ, Washington, D. C.-The United States. Bureau of Mines has in progress at the present time a study of the effect of underground atmospheric conditions on the safety and health of the workers. Im-proved methods have been employed and it is an excellent and ex-tremely valuable piece of research work.

Jan 12, 1919

By M. N. Short, I. A. Ettlinger

M. N. Short,? Washington, D. C., and I. A. Ettlinger, New York', N. Y. (New York Meeting. February, 1926) The Pioneer mining district, better known as the Superior district, from its principal town, is located in Pinal County in south-central Arizona about 80 miles east of Phoenix and 22 miles west of Miami. The region embraces a, confused series of mountain ranges of moderate height but precipitous slopes, between which lie irregular valleys filled with alluvial detritus. The average elevation is about 2800 ft. in the valleys and the summits of the ranges reach 2000 ft. above this. Superior is situated on the north bank of Queen Creek where it emerges from one of those ranges into a more or less basin-shaped valley. The drainage of Queen Creek is to the southwest and the flood waters spread out and lose themselves in the desert northeast of Florence, the county seat of Pinal County. The Magma copper mine (Fig. 1) is the only producer in the district. Although discovered in 1875, its production has been important only

Jan 1, 1927

By Thomas D. Henderson, Donald E. Crowell

INTRODUCTION This paper presents a "case history" of the steps taken to estimate capital and operating costs for a typical porphyry copper concentrator of ±9,070 metric tons (10,000 short tons) per day capacity. The concentrator described herein is hypothetical, but is based on experience and is, in effect, a composite of several actual projects. The numbers used are illustrative only and do not represent actual costs at any particular concentrator. These numbers are, however, representative of typical milling costs at one point in time, and. are sufficiently accurate to illustrate the cost estimating procedures described in this paper. It is not possible to publish actual, current milling costs and, in any event, actual cost figures quickly become meaningless in today's economic situation with various costs all rising at different rates. The paper is divided into three parts: (1) order-of-magnitude estimate, (2) feasibility study estimate, and (3) discussion of differences between estimated and actual costs.

Jan 1, 1978

W. VAN DER GRACHT, Tulsa, Okla. (written discussion.*).-I fully agree with Mr. Daly's observation that there is such a coincidence between petroleum deposits and geosynclines as to suggest them to be "closely allied phenomena." However, I accept no "identity of cause." To me the explanation is a simple one. Geosynclinal deposition is the first phase in the formation of a mountain, chain, and petroliferous deposits are indeed closely allied to zones of, mountain folding. In fact, petroleum is a typical occurrence in those beds, which represent the flysch facies, to use the Swiss expression. The uplifting of a great mountain chain is a very slow process; it gradually sets ill as a slow geo-anticlinal upheaval within a zone off former geo-

Jan 1, 1918

By C. R. Van Hise

[Concluding Contribution of Prof. Van Hise to the Discussion of his Paper, and Others on the Same General Subject, presented at the Washington Meeting, February, 1900 (see Ram., xxx., 27, 177, 323, 424, 578) ; also of the contributions of Vogt, De Launay, Beck, Lindgren, Kemp, Rickard, Bain, Keyes, Collins and Adams, presented at the Richmond Meeting, February, 1901, and to be printed in the present volume.] In June, 1900, shortly after my paper was published in the Fransactions, I made a briefer statement* before the Western Society of Engineers covering the same ground, which, in certain respects, is somewhat of an improvement. For instance, instead of using the terms descending and ascending &th reference to the waters resulting in the two concentrations, my modified statement is as follows: " The first concentration of many ore-deposits is the work of a relatively deep water-circulation, while the reconcentration is the result of reactions upon an earlier concentration through the agency of a relatively shallow water-circulation. Commonly the deep water-circulation is lacking in free oxygen, and contains reducing agents, and the shallow water contains free oxygen. The deep water is therefore a reducing, and the shallow water an oxidizing agent."† Of the papers upon ore-deposits which, in vol. xxx. of the Fransactions, follow my own, or which were presented at the Richmond meeting, a considerable number are wholly con-

Jan 1, 1902

By John Gross

The building of reverberatory furnaces (Fortschaufelungsofen) where ordinary brick, fire-brick and iron are comparatively cheap, is quite a different matter from the building of such furnaces in isolated camps, where proper material is only to be obtained at high cost and with long delays. Time is always a large factor in metallurgical operations, and the metallurgist may find himself in a position where it becomes necessary to erect apparatus and have it running in less time than it would take to obtain material from outside. It is here that he must make use of makeshifts. In Mexico, one of the most important of these is the alluseful adobe. Employed from prehistoric times, it still has its sphere of application in a surprisingly large number of instances requiring an article that can be quickly and cheaply produced. It is quite possible to erect serviceable reverberatory furnaces with no other materials than adobes, stone and wood. The old Mexican smelting shaft-furnace was an example of what can be done with adobes, and the large number of ruins of this class of furnace scattered through the mining districts of Mexico are silent testimony to the genius of a people who demonstrated their capability of adapting material at hand to their needs. The present paper will describe briefly the construction of an adobe reverberatory furnace which is giving good results, can be quickly erected at a low cost, and, if properly built and handled, will last a long time. The material being simply sun-dried, it naturally follows that the construction must be quite heavy. The adobes should be evenly made, with just sufficient straw to hold them together, and not too large in size (9 in. wide, 18 in. long and 4 in. thick

Jan 1, 1902

By Roland D. Parks

To construct a yieldable metal prop of demonstrated practicability has been the aim of the writer of this article for a period of years. Such a prop is herewith described; it involves a yielding principle not previously utilized, to the best of the author's knowledge, in any of the numerous types of props which are in use in Europe and England or on record at the United States Patent Office.' No attempt will be made in this paper to analyze the situation in regard to the economics of timber substitutes. Suffice it to say that shortage of suitable timber combined with high freight rates has already presented a problem in some mining districts, and in the relatively near future will probably demand considerable attention from the mining industry as a whole. In order to understand the problems involved in the design of timber substitutes for underground support, it will be well to review briefly the fundamentals of ground subsidence and of the action of timber as props. The forces encountered in the support of mine openings are not computable. As a rule subsiding ground moves slowly; but it moves with an irresistible force. The only way to be certain of stopping ground movement is to completely fill up the openings below such movement. This is, obviously, an impracticability from the mining standpoint. The ordinary procedure is to put in timber to hold up the loose back and permit the natural arch above to resist its own loading. Under these conditions the timber rigidly supports the loose; but if the natural arch fails, the timber is then called upon to resist this additional pressure. Usually it cannot do this. The result is a crushing of the supports. Efficient timbering is that which will last just long enough to complete in safety the mining operations necessary to extract the ore. Wood has a cellular structure. It has great longitudinal strength for its weight. Further, it possesses the ability to maintain a high percentage of its strength while it is being crushed. In other words, it rigidly supports loads up to its capabilities and then continues to sustain

Jan 1, 1934

By George C. Ference

Sulfur is the 13th most common element in the earth's crust, constituting approximately 0.05% of the total. It occurs naturally in its elemental form, as metallic sulfides, nonmetallic sulfates, and as combined or free sulfur in natural gas, crude oil, and coal. COMMERCIAL SOURCES Most of the sulfur that is consumed is converted into sulfuric acid before use; therefore, it is not necessary to recover sulfur solely in its elemental form. Processes for recovery are peculiar- to the types of reserves being processed. The major commercial processes as well as the general geographic locations where the appropriate reserves occur are listed in the following. It should be noted that the sulfur values may be recovered as the primary product, as a coproduct with other materials, or as a byproduct. Elemental Sulfur 1) Frasch mining is used for subterranean deposits of elemental sulfur around the Gulf Coast areas of the United States and Mexico. Generally, but not exclusively, such deposits are located in salt dome structure. 2) Autoclaving, flotation, or solvent extraction of surface deposits of elemental sulfur is practiced throughout the world. 3) Extraction and conversion of hydrogen sulfide from sour natural gas into elemental sulfur is done principally in Canada, France, and the United States. 4) Conversion of metallic sulfides from pyrites into elemental sulfur is done via the Outokumpu process in Finland. 5) Catalytic cracking and hydrocracking of sulfur-bearing crude oils to produce elemental sulfur is done worldwide. Desulfurization of refined petroleum products also yields elemental sulfur. 6) Recovery of elemental sulfur from sulfur-bearing oil sands (Athabasca tar sands) has been initiated in Canada. 7) As of this writing (1970), a plant has been constructed for the thermal decomposition of gypsum to produce elemental sulfur in the United States. Sulfuric Acid Sulfur values in the form of sulfuric acid are recovered via: 1) Recovery from smelter gases throughout the world. 2) Roasting of pyrites throughout the world with iron sinters as a byproduct. 3) Roasting of anhydrite with cement as a coproduct, primarily in Europe. 4) Processes currently are being developed for recovery of sulfuric acid from combustion gases resulting from the burning of high-sulfur-content fuel. Other Sulfur values also are recovered from waste products which normally occur in highly industrialized areas. Some examples are: coke-oven gases, sludge sulfuric acid, and pickling liquors (ferrous sulfate).

Jan 1, 1976