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By H. A. Schrecengost, H. R. Gil, Alfred Clarkson, E. H. McCleary

Much has been written and many discussions have been held concerning the prevention of accidents in coal mines , and considerable progress has been made in eliminating hazards to the health and safety of underground workmen . Although much progress has been made in the reduction of injury rates in the Pennsylvania anthracite field , the injury rates for the anthracite mines of Pennsylvania are generally higher than the average for coal mines in the United States as a whole , because the mining conditions , including the safety problems , in the Pennsylvania anthracite fields are more complex than in other coal fields of the United States . Several factors contribute to this extremely difficult problem , among which are : Multiple - vein mining , steeply pitching measures , folds or faults , hard smooth floors underneath the veins , and the remining or reclaiming of pillars in severely crushed , broken ground . In the early days of the Pennsylvania anthracite industry , only the more productive veins were mined , and this resulted in bypassing those veins that were relatively thin and those containing considerable proportions of impurities . However , the development of modern coal - preparation equipment , improved marketing conditions , and the adoption of mechanical equipment , such as the various types of conveyors and scraper loaders , have made possible the recovery of the thinner and poorer veins . Furthermore , in the early days , little or no attempt was made to recover the coal pillars , usually owing to the great amount of virgin coal available . Consequently , much of the anthracite produced within the last few years has been recovered by second and third mining and frequently by fourth mining - in areas where operations had been suspended for many years . In such areas , the coal veins and intervening strata are usually crushed as the result of gradual subsidence , which intensifies the hazards incidental to roof control , haulage , ventilation , and mine gases . Moreover , the use of coal - cutting equipment is not practicable in most anthracite mines because of. the inclination of the veins and because , in crushed -ground areas , the faces must be advanced slowly and for short distances at a time to permit the erection of timber sets and the placing of forepoles to support the roof and sides . Thus , the slow process of mining brought about by these conditions has resulted in the production of only 0.424 ton of anthracite for each man- hour worked , as compared with 0.753 ton? for each man - hour worked at other coal mines in the United States . A summary contained in Bulletin 462,8/ a publication of the Federal Bureau of Mines , reveals that the rate of fatal injuries in the Pennsylvania anthracite industry was improved from 13.47 deaths per million tons produced in 1870 to 3.88 deaths per million tons mined in 1942. During the period March 16 , 1942 to January 1 , 1947 , the fatality rate was reduced from 3.88 to 2.87 deaths for each million tons mined . On the million man-hour basis , the rate of fatal injuries was reduced from 1.643 to 1.130 and the nonfatalinjury rate was lowered from 119.01 to 83.12 during the same period . The improvements made in both the fatal- and nonfatal - injury rates have required the cooperation of the workmen , the mining companies , and the State and Federal inspection departments . Many individual mines and companies have achieved commendable safety records which contributed greatly to the over - all average for the industry , particularly during the 1942-47 period . One of the most outstanding of these is the Continental mine of the Continental -Archbald Coal Co. , a member of the Moffat Co. Interests .

Jun 1, 1948

By R. L. Soderberg

This paper is one of a series on mining methods and costs being published by the Bureau of Mines. It describes briefly the mining methods employed since the start of operations in 1937, with emphasis on the diamond-drill blast-hole method of ore breaking and slusher-drift method of ore drawing at the Holden mine of the Howe Sound Co., Chelan Division, Holden, Wash. The Holden mine is in the north-central part of the Cascade Range, 11 miles up Railroad Creek from Lake Chelan. The nearest railroad is at Chelan Falls, 40 miles by boat and 4 miles by highway from the mine. All freight comes into the mine and all concentrates are shipped out via Chelan Falls. The altitude of the main haulage level is 3,500 feet. Railroad Creek Valley is covered with a dense growth of fir and spruce, while most of the surrounding mountains are rocky, with sparse timber growth.

Jun 1, 1948

By Frank H. Reed

This report is one of a series written by members of the Solid Fuels Mission to Germany describing wartime developments in the mining , preparation , and utilization of coal . This mission was organized early in 1945 under the auspices of the Technical Industrial Intelligence Committee , which cooperated with a counterpart British committee . The Solid Fuels Mission operated under the direction of a steering committee headed by Dr. C. J. Potter , Deputy Solid Fuels Administrator . The personnel of the mission consisted of H. F. Yancey, in charge , J. W. Buch, Thomas Fraser , L. L. Newman , and L. D. Schmidt of the Bureau of Mines ; H. H. Lowry , Director of the Coal Research Laboratory , Carnegie Institute of Technology; H. J. Rose , Vice - president and Director of Research , Bituminous Coal Research , Inc .; and F. H. Reed , Chief Chemist , Illinois State Geological Survey . Over 50 reports were written by the members of the Solid Fuels Mission . These , together with microfilms of supporting data obtained in the course of the investigations , are on file at the Bureau of Mines , Washington , D. C. , where they are available for public examination . The Office of the Publication Board in the Department of Commerce is prepared to furnish photolith copies , photostats , or microfilm reproduction of all declassified reports . A Bibliography of Scientific and Industrial Reports is issued weekly by the Department of Commerce , Office of the Publication Board , and is sold by the Superintendent of Documents , Government Printing Office , Washington 25 , D. C. , on a subscription basis . An initial payment of $ 10 will provide for approximately 9 months , and subscribers will be notified when additional remittance is necessary . All subscriptions will begin with volume 1 , No. 1 , unless ordered otherwise . The Bibliography, covers all materials and subjects and gives instructions for obtaining the desired items . The reports of the Solid Fuels Mission relate to the following general subjects : Mining methods in the Ruhr district of Germany , with special reference to mechanical cutting and loading equipment , pneumatic packing , and Diesel mine locomotives ; activities of industrial research laboratories supported by the German coal and coke industry ; coal preparation in western Europe ; low- temperature carbonization processes ; metallurgical coke from

Jun 1, 1948

By O. C. Blade, Elizabeth Hughes

Conservation in the utilization of any product is always subject to improvement if the composition and properties of the product are known. Petroleum is no exception, and knowledge of the characteristics of crude oils, even when given on the broad basis of routine type analyses has proved useful to chemists, engineers, and geologists in improving pro- duction and utilization of petroleum. For a quarter of a century the Bureau of Mines has sought to provide such information regarding crude oils and has analyzed many samples of petroleum by its standardized rou- tine method. Most of these analyses have been published, sometimes in special compilations, other times in connection with reports of research on petroleum. This report is a finding index for all analyses published up to January 1, 1948. The routine method used for all these analyses is basically the same as that described by Dean, et al.. Briefly, the procedure consists of testing by standard methods, small samples of a crude oil for gravity, sulfur, color, and viscosity, and of distilling a sample of the crude oil by a standardized procedure and determining certain properties in the sep- arated fractions and residuum. Careful records are made during the proce- dure, and the distillation data obtained are used to calculate the approx- imate amounts of products present in the sample such as percents of gas- oline, kerosine, gas oil, and lubricants. The data obtained are recorded on a standard analytical report form. An analysis of a sample of typical midcontinent crude oil is shown in table 1. Compilation of these analyses, sometimes in tabular form and usually for specific geographic areas, are published from time to time. Analyses are often shown in connection with other studies, such as engineering field reports. This bibliography is a compilation of references to 115 publications, which contain analyses of crude oils by the Bureau of Mines. References may be found to analyses of crude oils from the United States, Canada,

Jun 1, 1948

By G. S. Scott. R. L. Grant

Ammonium nitrate (NH4NO3), a white crystalline chemical compound composed of 35 percent nitrogen, 60 percent oxygen, and 5 percent hydrogen, has again attracted attention, due largely to the recent catastrophe on April 16 and 17, 1947, at Texas City, Tex. The fire and subsequent explosion on the steamship Ocean Liberty, outside the harbor of Brest, France, on July 28, 1947, has fur- ther increased the interest in the properties of ammonium nitrate. As a result of the Texas City disaster, several laboratories have undertaken research to determine more certainly what causes ammonium nitrate to detonate and under what circumstances. This is not the first time that ammonium nitrate has been involved in a disaster, and its properties reviewed from the standpoint of safety. The disaster at Oppau, Germany, in 1921, which involved an equimolec- ular mixture of ammonium nitrate and ammonium sulfate, prompted an intensive study in Europe and in America. In the United States the properties of am- monium nitrate are now of especial concern because very large quantites are being manufactured and shipped in interstate commerce and abroad. Many an- monium nitrate factories, which were built during the war, will manufacture increasing amounts of this compound for use as a fertilizer. It is the purpose of this report to present a brief summary and biblio- graphy of the published experimental facts about the properties and behavior of ammonium nitrate. The reader is referred to original publications for greater details of the investigative work, and for theoretical discussions. This report also includes a survey of ammonium nitrate fertilizer of the type involved in the Texas City explosions. In the past, authorities have not always agreed on the degree of hazard involved in the manufacture and handling of ammonium nitrate, as the following quotations from the literature indicate: Munroe (82) quoted the following from Turner's Chemistry (a book pub- lished in 1835): "When this salt is exposed to fire, it liquefies, emits aqueous vapor, dries and detonates." Berthelot (14) in his book, Explosives and Their Power, 1983, wrote: "Ammonium nitrate from the point of view of its volatility, and cn account of many considerations, may be regarded as a typical explosive substance."

Jun 1, 1948

By A. B. Hooler

"A complete list of permissible mine equipment, tested and approved by the Bureau of Mines previous to January 1, 1947, was published as Information Circular 7432. 3/The present list is a supplement thereto that includes all of the equipment approved during the calendar year 1947.The items are numbered to indicate the consecutive order in which each type of machine or device was approved in its particular classification. Thus, Information Circular 7432 showed six air compressors on the active list; two additional compressors, Nos. 7 and 8 in this category, were approved during 1947.Items 2 and 7, unmounted loader and power unit, respectively, under Loading and Conveying Equipment, item 2, rubber-mounted mining machine and item 8, distribution box, appear in Information Circular 7432. They are repeated to show that approvals of these four equipments were extended to cover an additional voltage rating which requires material change in design.Equipment listed in these circulars is approved by the Bureau of Mines only when found upon inspection and test to comply with minimum standards of safety as outlined in schedules prepared on the basis of many years of experience in dealing with safety problems of the coal-mining industry. The use of such equipment in mines known to be gassy, as well as in those that may become so, is earnestly recommended in the interests of safety. This circular is published so that the industry may be kept informed as to the many types of machines, devices, and lamps that are available for reducing explosion and other hazards incidental to coal mining. The present paper, with Information Circular 7432, gives the complete list of permissible mine equipment that is available under the various classifications."

May 1, 1948

By Frank E. Cash, Max S. Peterson

"INTRODUCTION Falls of ground cause the greatest number of accidents at underground metal mines. Statistics compiled by the Federal Bureau of Mines show that during a 13 - year period ended in 1943, falls of ground caused 35 percent of the fatalities and 16.8 percent of the nonfatal injuries at underground metal mines in the United States. 4/ Expressed on a basis of a million man-hours worked, the frequency rate was 0.355 for fatalities and 11.76 for nonfatal injuries. Although some progress has boon made in preventing rock-fall accidents over a 30- or 40-year period, the problem is still a major one requiring the diligent efforts of management and employees.In the Lake Superior district: where organized safety programs have been in effect for more than 30 years, the record is more favorable. Statistics compiled by the Lake Superior Mining Section of the National Safety Council reveal that over a 6-year period ended in 1945 the frequency rate of fatalities per million man-hours was 0.277, and the rate for nonfatal injuries was 2.38 from falls of ground.Although the above-given statistics do not cover equal or concurrent periods, the improvement in accident experience in the Lake Superior district over the national average, is obvious. This improvement is due to more effective methods of ground support or more rigid enforcement of the use of known methods.It is hoped that the following information about ground-support practices in the Lake Superior district will assist operators of other mines in their efforts to reduce accidents from falls of ground."

May 1, 1948

By Nancy Potts, M. G. Barker, W. C. Holliman

"SUMMARYThis report on the characteristics of commercial aviation gasolines presents compilations of inspection test data furnished on their products by manufacturers of commercial grades of aviation gasoline, and special data obtained in Bureau of Mines laboratories on samples of these gasolines. Data and physical samples for the survey were submitted by 15 manufacturers on 18 grade 80, 21 grade 91/98, 22 grade 100/130, end 10 grade 115/145 aviation fuels.The inspection test data supplied by the participating manufacturers consist of octane and performance numbers, tetraethyllead content, dye color, and other characteristics usually listed in aviation gasoline specifications, such as AN-F-48a or ASTM Designation D910-47T. These data are tabulated and averaged by grades in tables 1 through 4 and, as reported, meet the AN-F-48a and similar specifications with a few exceptions. Two grade 80 gasolines show a lean-mixture octane rating slightly below 80.0, and 91/98 grade fuel shows a lean-mixture rating of 90.9 and a rich-mixture rating of 97.5, two 100/130 grade gasolines have a rich-mixture performance number slightly below 130.0, and one 115/145 grade gasoline shows a rich-mixture performance number of 144.5. However, octane and performance number averages are above the mini¬mum requirements for each grade. Tetraethyllead content in the 91/98 and 100/ 130 grades generally is above the maximum outlined in these specifications, whereas dye color for each of the four grades, with the exception of two gasolines in grades 80 and 100/130, is that designated for the particular grade. Distillation requirements, with a few exceptions at individual points, are met by gasolines of all grades. Reid-vapor-pressure, copper-dish-residue, heat-of-combustion or aniline-gravity-constant, freezing-point, and copper-strip-corrosion requirements are met by all gasolines so far as reported. No data for some of these tests wore submitted on a few of the gasolines. One gasoline, grade 115/145, shows a sulfur content greater than the specified maximum."

May 1, 1948

By Frank E. Cash, John A. Johnson

"INTRODUCTION During the 6-year period, 1940-45, 481,485,000 gross tons of iron ore was shipped from the Minnesota, Michigan, and Wisconsin mines of the Lake Superior district. Approximately 367,000,000 tons, or 76 percent, of this ore was shipped from open-cut mines. The production of this large tonnage of iron ore from the open-cut mines of the Lake Superior district during the recent war was an outstanding achievement. It is questionable whether this record-breaking tonnage of iron ore, vitally needed for the successful prosecution of the war, could have been produced without the modern equipment and mining methods used in the district, The transportation of iron ore from the open-cut mines of the district is the most important phase of the mining cycle. Although some of the mines still use rail haulage advantageously, this method of haulage has been replaced at most nines with motor-truck haulage or a combination of motor-truck and belt-conveyor haulage.SCOPEThe transportation of iron ore in this report covers (1) power shovels, (2) rail haulage, (3) trucks, (4) belt conveyors, (5) shipping pockets, (6) accident statistics, and (7) safety rules pertaining to open-cut transporta¬tion. The purpose of the report is to discuss briefly and disseminate to the mining industry the modern methods, equipment, and safety practices used in transporting iron ore at the open-cut mines of the district.The 25 open-cut mines covered herein, located in the Marquette, Cuyuna, and Mesabi iron ranges of Michigan and Minnesota, shipped approximately 44,000,000 tons of iron in 1945, which amounted to 72 percent of the open-cut iron ore shipped from the Lake Superior district."

May 1, 1948

By T. J. Ballard, Austin B. Clayton

"INTRODUCTION The Conrad Hill mine was first opened as a gold mine about 1832 and has been operated at various times since then.The Bureau of Mines, as part of the strategic minerals program, mapped and sampled the accessible mine workings.The: work failed to reveal appreciable copper values or evidence of additional ore deposits.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the and that they make the greatest possible contribution to national security and economy. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The field work embodied in this report was under the direction of Austin B. Clayton. The final report was prepared by T. J. Ballard uncle,- the general supervision of Mitchell H. Kline, chief, Raleigh, N. C., Branch, Mining Division. Analyses of samples and beneficiation tests were made by the Metallurgical Division. ACCESS AND OWNERSHIPThe property is 6 miles southeast of Lexington, N. C., and can be reached by U. S. Highway 64, turning off at Hedrick Grove Church, and is 1 mile north from the highway on the county road. The mine is in Davidson County at approximately 35° 47' latitude and 80° 10' longitude (fig. 1).The property comprises 471 acres and is owned (1943) by the McKeeMining Co., 512 Fifth Avenue, New York City. The property was optioned to Woodrow McKay of Lexington, N. C., in 1943, who in turn subleased the property to the Robert G. Lassiter interests of Raleigh, N. C."

May 1, 1948

By M. H. Kline, T. J. Ballard

"INTRODUCTION The Cranberry magnetite deposits occur in pre-Cambrian granite-gneiss in a belt extending from 3 miles southeast of Cranberry, N. C., to about 6 miles southwest of Magnetic City, Tenn. The belt forms a curve, elongated to the north, approximately 26 miles in length.The Bureau of Mines investigation has been confined to the eastern part of the belt, comprising the area from Fork Mountain, Avery County, N. C., to the Hcupscup Knob prospects in Carter County, Tenn.The deposits were worked at least as early as 1820. The Cranberry Iron & Coal Co. and its successors operated the Cranberry mine intermittently for about 50 years until 1930, when operations were abandoned.The magnetite rock is amenable to concentration. Numerous laboratory tests and pilot-mill operations have proved that a high-iron, and low-phosphorus concentrate can be obtained by fine grinding and magnetic, separation, the quality of the concentrate depending upon the extent of grinding. The principal objectives of the Cranberry project were threefold.The primary consideration for beginning exploration of the deposits was the need for developing additional deposits of high-grade iron ore during the war and for replenishing the war's depletion of iron-ore reserves for the peacetime economy. The emergency did not permit logical sequence bf development, and it was necessary to begin drilling before the geophysical survey was completed. The first drilling was begun at the Cranberry mine; and the holes were located from the geological data, coordinated with the position of the mine workings."

May 1, 1948

By B. H. Clemmons, B. G. Saunders, R. H. Stacy

"INTRODUCTION This investigation was undertaken to determine the response of Birmingham (Alabama) red-iron ore to heavy-medium concentration. Specifically, the work involved a study of the efficiency of the process in separating coarse gangue diluents from the ore and an endeavor to evaluate the potential economic results. The investigative work was not intended, nor is it to be construed, to be adequately exhaustive in scope to enable immediate plant construction. Rather, the primary objective was to determine the grade of ore that could be produced by heavy-medium treatment and the resulting indicative or tentative benefits to be derived from such treatment. The latter, in turn, would determine the merits of the more exhaustive study that would be required for an ultimate decision on the heavy-medium treatment of the ores.The problem of avoiding excessive contamination of red-iron ores by shale and/or ferruginous sandstone has been before the operators of the iron mining industry of the Birmingham, Alabama, district for many years. Within the last two decades, increased mechanization of mining methods has increased this contamination to a considerable degree. In fact, general utilization of scraper loading and other mechanical methods of mining, in conjunction with small increases in the natural insoluble content of the ores, in some cases has actually resulted in the production of ""acid"" or excessively insoluble ore, where ""basic"" or excessively lime ores were produced formerly.The contaminating materials are derived largely from roof spells and natural parting seams in the ore, a condition that to some extent has been aggravated by the irregularity of the ore beds. The latter have been subjected to both primary and secondary folding in many places. Considerable faulting has taken place, also. In many localities these conditions render virtually impossible complete avoidance of ore contamination from the over and underlying sandstones and shales. However, in a few localities, where the ore beds are less disturbed and shale partings are absent, mining can and is being accomplished with relatively little dilution."

May 1, 1948

By H. E. Sanford

"INTRODUCTION Of the occupations in and about coal mines, those of the haulage crews are among the most hazardous. Statistics indicate that the second largest number of fatalities about coal mines occurs during haulage operations and through the use or misuse of haulage equipment. Despite the fact that relatively few coal-mine employees are engaged continuously at haulage operations, approximately 20 percent of all coal-mine fatalities are attributable to haulage.Most of the hazards in haulage operations could be very greatly reduced if more serious consideration were given to the problems of the haulage crews and if sincere efforts were made to reduce the hazards. Underground haulage is similar in many respects to railroading; yet, railroading is now considered one of the safest of occupations a distinction that has been attained only by honest effort and whole-hearted cooperation on the part of all concerned. Underground haulage is also similar to street and highway operation and has in it some of the difficulties encountered in the reduction of traffic accidents the seriousness of which has not by any means been con¬trolled as yet, notwithstanding the fact that much effort has been expended through a multiplicity of laws, ordinance regulation, etc., as well as by thousands of enforcement agencies and officers.The men working on the locomotives are among the most important members of a coal-mine organization; without skilled haulage employees, the production of coal would be greatly retarded. Their jobs, particularly the job as brakeman, require physical endurance, agility, and mental and physical alertness; in thin coal beds, especially where the roof is not brushed and the coal is loaded into mine cars by hand, the need for these qualifications is greatly increased."

May 1, 1948

By Heine Kenworthy

"INTRODUCTION In 1930 the Shenandoah-Dives Mining Co. near Silverton, Colo., put into operation a newly erected, 300-ton selective flotation plant to mill complex ores from its nearby mine. The operation was a steady producer and was enlarged to treat 600 to 800 tons a day. In 1942 the company opened and started milling an area in the mine containing semioxidized ore. The valuable mineral content of this ore was considerably higher than in, the straight sulfide ore previously handled alone. The mixture of clean sulfide and semi-oxidized ore was difficult to treat; consequently, tailing losses, especially with respect to lead, were high. A few years later, in order to study the possibilities of obtaining higher recoveries by a modification of the mill flow sheet, a 1,200-pound sample of mill, feed, taken over a period of several days by the company, was submitted to the Mississippi Valley Experiment Sta¬tion for testing-. Although this sample proved to contain more than twice as much lead as the average yearly mill feed, the same problem of recovering the oxidized values was present.A résumé of the ore-dressing treatment used in the Shenandoah-Dives mill follows. After crushing, the ore passes through a ball mill, the minus 5-mesh discharge of which is distributed to three tables. A finished lead concentrate is made on the tables, and the table tailing goes to the classifier which is in closed circuit with the ball mill. The classifier overflow is treated -by flotation to obtain a bulk sulfide concentrate at a relatively coarse size. The bulk concentrate is thickened and reground to about 95 percent minus 325-mesh before flotation treatment to separate a lead-copper and a zinc concentrate. A typical monthly average showed that the table concentrate contained about 45 percent lead, 1 percent copper, 4 percent zinc, 12 ounces of gold, and 40 ounces of silver; that the lead flotation concentrate contained '35 percent load, 6 percent copper, 7 percent zinc, 3.5 ounces of gold, and 50 ounces of silver; and that the zinc flotation concentrate contained 2 percent lead, 0.5 percent copper, 60 percent zinc, 0.15 ounces of gold, and 4 ounces of silver. Recoveries in salable products were roughly b5 percent of the lead, 70 percent of the copper, 45 percent of the zinc, 85 percent of the gold, and b5 percent of the silver."

May 1, 1948

By E. V. Deshayes, W. E. Young

"INTRODUCTION The Camp Bird mine was investigated by Bureau of Mines engineers 3/ September 22 and 24, 1942, and April 29 and 30, 1944. In a subsequent report and supplement, it was recommended that core drilling be done below the 14th. level to determine if commercial ore existed at greater depths, and particularly if ore existed in the vein or adjacent thereto where it passes into the sedimentary formations estimated to underlie the volcanics approximately 400 feet below the 14th level.Seven diamond-drill holes aggregating 3,956 feet were drilled. Four of these holes were under the Hematite ore body and three were under the Big Discovery ore body. Two holes under, the Hematite ore body wore directed at angles but little steeper than the angle of dip of the vein and penetrated the sedimentaries beneath the volcanics close to the vein. Enough low-grade ore was found at the base of the Telluride conglomerate to indicate the presence of a large body of low-grade zinc sulfide ore. Two holes were directed to crosscut the vein at a depth of approximately 125 feet below the 14th level. No commercial ore was cut, but the vein showed the average width and same general characteristics as at the 14th level. One hole under the Big Discovery ore body was directed to crosscut the vein and test the base of the Telluride conglomerate in the footwall block. No commercial ore was found in either the vein or the sedimentary horizon. One hole was directed to test the base of the Telluride conglomerate in close proximity to the vein in the hanging-wall block. This hole was lost approximately 100 feet short of its objective, and a third hole was drilled to accomplish this same thing. The third hole was stopped approximately 50 feet short of its objective when failure of equipment caused a recess of the"

May 1, 1948

By J. S. Kennedy, M. M. Fine

"INTRODUCTION Barite is one of the major industrial minerals whose production has increased considerably in the last 10 years. In 1935 domestic production of barite was 218,075 tons and. had increased by 1944 to 515,136 tons. 3/ Most of the primary uses for barite and barite products were developed before 1935, so the increase in barite production reflects the growth of industry in general rather than any recent developments in barite technology.The principal uses for ground and crushed barrite are as a weighting agent in heavy drilling fluids, as a filler in rubber and other materials, as a pigment and extender in paints, and as a flux in glass melt. In addition, a considerable' quantity of barite serves as the raw material for the manufacture of lithopone and barium chemicals.Specifications for barrite vary widely and depend primarily on the use to which the material is put. The primary requisites for barite used in heavy drilling muds -are that it have a minimum specific gravity of 4.2 and be very,low in soluble salts. A minimun barium sulfate content of 92 percent may be specified; but this is less important than the gravity. 4/ In addition before consumption the material must be ground to '92 percent minus 325-mesh. 5/ Lithopone and chemical manufacturers require a minimum of 94 Percent barium sulfate, a maximum of 1.0 percent iron oxide, and not more than a trace of fluorine. 6/ Barite used as fillers in light-colored products should be of fairly high grade, but the filler used in dark products may be considerably lower grade.Glass barite should contain a minimum of 96 percent barium sulfate, not more than 3 percent moisture, a maxium of 0.2 to 0.4 percent iron oxide, and not more than a trace of titanium oxide. Particle size is a matter of some importance in glass barite, also. 7/"

May 1, 1948

By H. J. Sloman

"INTRODUCTION Industry, including coal mining, has come to realize that to prevent accidents the human element must be given more consideration than was customary in the past. In formulating safety rules and regulations and in the enactment of laws governing mining, too often enforcement is emphasized rather than the means of gaining willing compliance.' The purpose of this paper is to call attention to the human side of accident prevention, and the approach to this important and much-discussed subject will deviate somewhat from the usual discussions.The human being is a complex mechanism, both physically and mentally. It is difficult to establish a common denominator for the actions of humans, except in general. In establishing mining laws, rules, regulations, and standards, the ultimate objective should be to gain the best possible response of workmen, so that optimum results in accident prevention may be obtained. The complexity of human beings is apparent when the many ways 1n which they differ are considered. Some of these differences are manifested in emotional and phlegmatic types, degrees of intellect or native intelligence; and in hopes, desires, aspirations, and philosophies of life. How much simpler ac¬cident prevention would be if the response to laws, rules, regulations, or standards were equivalent to the definite movements of puppets responding to pulls on strings. Each time, the strings are pulled in exactly the same way, the puppets will respond in exactly the same manner. Human beings, although having many similar characteristics, do not respond uniformly to identical ""string-pulling""; therefore, much study is necessary before the desired re¬sponses can be obtained. To achieve the ultimate in accident prevention, it must be ""worked at"" constantly. Regardless of the adequacy of safety laws, rules, regulations, or standards, good accident records will not ""roll in"" if dude consideration is not given to the personal traits of those most likely to be involved in accidents."

May 1, 1948

By D. Harrington, W. J. Fene, H. B. Humphrey

In the fiscal years 1946 and 1947 the number of mine explosions decreased compared with the preceding years. However, the loss of life was so serious during the fiscal year 1947 the period when the Government administered bi- tuminous-coal and lignite mines that from April to June 1947 extraordinary measures were taken in mines then under Government possession to obtain com- pliance with provisions concerning rock dusting, ventilation, and blasting that had not been followed. The great loss of life in explosions during the fiscal year 1947 as compared with 1944, 1945, and 1946 is not easy to explain, but the necessity for maintaining adequate protection has been definitely demonstrated. Management, workers, and inspection agencies alike must keep the mines reasonably safe against explosions or allow them to lapse into a condition where chance is the principal protection against disaster. The at- tention given to protecting coal mines and the men employed in them against mine fires, following the disastrous fires in 1944 and 1945, has at least tem- porarily controlled this hazard loss of life from coal-mine fires was re- duced to 1 fatality in 1947. The number of fires was also less, and progress has been made in reducing the heavy losses in both life and property from un- derground coal-mine fires that occurred in the two years mentioned. Fatalities from mine explosions during the past 6 fiscal years, July 1942 to June 1947, totaled 674, and there were 149 explosions; during the preceding 6 years there were 655 fatalities in 132 explosions. The 6 fiscal years 1942- 47 cover the active period of Federal coal-mine inspection. During the fiscal year 1947, there were 154 fatalities from explosions compared with 58 during the fiscal year 1946, 64 in 1945, 94 in 1944, 152 in 1943, and 152 in 1942.

May 1, 1948

By William A. Beck

This paper is one of a series, describing current practice in diamond drilling for production at various mines throughout the United States. It describes the drilling and blasting methods, used at the Tennessee Copper Co., which started using deep-hole drilling for blasting in 1927, employing inde- pendent, rotation percussion drills with sectional drill steel. Since 1942 the company has employed diamond drills for deep-hole drilling. This method has now passed the experimental stage and promises to become permanent. The elimination of rock dust and safer working conditions for the drill crews are listed as the main advantages. The higher initial cost of equip- ment is the principal disadvantage.

May 1, 1948

By H. H. Schrenk

Much has been written and said concerning tables of permissible or maximum allowable concentrations of various toxic substances in air, but not enough attention has been given to their limitations and how to use them intelligently . There is a tendency to place too much reliance on figures , with little or no consideration of their real meaning . The repeated publication of a figure often adds significance to it far beyond that intended by the original author or publisher . How are these figures referred to as "maximum allowable concentrations " established? What is their real meaning? To answer these questions it is necessary first to define maximum allowable concentration . The usual definition is somewhat as follows : "The average concentration to which an industrial worker can be exposed for 8- hours daily for an indefinite period without injury or occupational disease . This definition is made up of the following items : ( 1 ) Average concentration, ( 2 ) 8 - hour day , ( 3 ) indefinite exposure period , and ( 4 ) lack of injury or occupational disease . There is some controversy regarding item ( 1 ) , items ( 2 ) and ( 3 ) are usually though not invariably accepted , and there is definite disagreement regarding the interpretation of item ( 4 ) . . To reach a more satisfactory interpretation of maximum allowable concentration , attention is directed to ( 1 ) the development of tables of maximum allowable concentrations , ( 2 ) criteria on which limits are based , and (3 ) methods used to obtain data on which limits are based .

May 1, 1948