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By Ernest A. Hersam

"INTRODUCTION.Luring the year 1923 a complete survey was made of the condition of research in the reduction (milling) and concentration of ores and nonmetallic minerals - that is, up to the stage where the ores or concentrates were ready for hydro- or pyro-metallurgical treatment. This survey was carried on under the general supervision of L. A. Lyon, assistant director and chief metallurgist of the Bureau of mines, in cooperation with the milling committee of the American Institute of mining and metallurgical Engineers, the Massachusetts Institute of Technology, and the University of California. Other institutions, including the National Research council, were of assistance and outlined recommendations during the study.While this report is on ""ore dressing"", it contains short sections on coal and clay. The mechanical handling that these minerals undergo is ""dressing"", so that ore dressing is inclusive of metallic and nonmetallic minerals. ""milling"", in its broadest sense, includes with ore dressing certain other metallurgical treatment which the report is not designed to cover.The survey revealed that considerable experimentation is being carried on great cost to the mining industry, but that the research is in general poorly coordinated while companies and firms are adequately taking care of routine tests and the mechanical features involved in their own operations, no comprehensive study of the fundamental principles of ore reduction is now in progress or contemplated. Many industries, besides mining, are interested in the preparation of materials for final treatment, rendering this investigation of value also to them. This class of fundamental research is neglected by industry unless there is some agency which can bring together at least a majority of this interested in a cooperative effort. It can not be effectively handled by a single company; and, moreover, no company can be expected to bear the whole burden of an investigation to benefit the entire industry or a number of industries hence there is need for concerted study within reasonable limits. Furthermore, co-operation eliminates duplication, which is largely a waste of effort and capital."

Mar 1, 1925

By J. J. Jakosky, D. H. Zellers

"IntroductionThis paper is the seventh of a series describing an investigation being conducted by the Bureau of Mines on underground communication. A review of past work and results obtained has been published. The present paper deals with a study of line-radio or wired-wireless methods of communication, herein electrical energy is transmitted by metallic conductors.The use of line-radio over metallic conductors has been practiced for a number of years, and at present is being used on a large scale in long-distance carrier-current telephone and telegraph. The early work of the U. S. Army Signal Corps and the Bureau of Standards in using ordinary radio transmitting and receiving apparatus for communication over metallic conductors was been descried. Later publications describe commercial applications, and an excellent treatise and resume is given by E. Colpitts and C. B. Blackwell.Scope of ReportThis report contains (1) a discussion of the chief factors affecting carrier-current transmission, with particular reference in application to underground communication for mines; (2) a description of typical underground circuits used for power and lighting; and (3) description of apparatus used and results obtained in line-radio experiments in coal mines near Pittsburgh, with circuit diagrams, and conclusions as to power requirements and limitations for mine use."

Apr 1, 1925

By M. B. Cooke

 An analytical method for the determination of the gum-forming material in gasoline has been developed by the Bureau of Mines, during a study now in progress to determine the best rays for elimination of such constituents from gasoline. This method is similar in principle to that previously described by Smith and Cooke, which involved evaporation of e semple of gasoline in a small glass dish. The evaporation was started on an actively boiling steam bath and completed in an air oven at 105°C. In the improved method described below, the steam bath has been replaced by a steam heated oven in which an inert atmosphere is maintained. Air is ex- cluded from the oven, consequently the precision of the determination is increased. Furthermore, evaporating dishes different from those previously described may be used.

May 1, 1925

By M. B. Cooke

An analytical method for the determination of the gum-forming material in gasoline has been developed by the Bureau of Mines, during a study nor in progress to determine the best rays for elimination of such constituents from gasoline. This method is similar in principle to that previously described by Smith end Cooke,2 which involved evaporation of e sample of gasoline in a small glass dish. The evaporation was started on an actively boiling steam bath and completed in an air oven at 105°C. In the improved method described below, the stem bath has been replaced by a steam heated oven in which an inert atmosphere is maintained. Air is excluded from the oven, consequently the precision of the determination is increased. Furthermore, evaporating dishes different from those previously described may be used.

Jan 1, 1925

By C. O. Anderson, W. M. Meyers

Since 1922, when a brief report3 on the production and utilization of garnet was issued by the Bureau of Mines, there have been a number of interest—in developments in the technology of that mineral. Greater activity has been displayed in mining, new mills have been erected, and more attention has been paid to improvements in milling so that a more efficient and economical recovery of garnet has been possible. These activities have resulted in larger production; therefore, attempts are being made to broaden the market for garnet abrasives, and to find new uses for the unusual combination of physical properties than this mineral possesses. The writers have recently completed a field study of the occurrence, methods of mining and milling of garnet, and the manufacture and utilization of abrasive garnet products. This preliminary report indicates the most important sources of garnet, the methods by which it is recovered, and the manner in which it is recovered, and the manner in which it is utilized.Chemical and Physical Properties.The term ""garnet"" is applied to a closely related group of minerals which crystallize in the caste forms and possess similar physical properties, although their chemical composition may exhibit greater variation. The chemical composition of the garnet group may be represented by the general formula 3R"" O.R""' 203.3S102, in which R represents the bivalent elements calcium, magnesium, in the manganese state and ferrous iron, R"" represents the trivalent elements, ferric iron, aluminum and chromium in the chromie state. An account of the amorphous substitution of the different bivalent and trivalent elements, specimens whose composition may be represented by a definite formula are rare, the composition of any given specimen generally exhibits treat complexity.

Jun 1, 1925

By J. E. Tiffany, J. J. McKitterick

"IntroductionThe Bureau of Mines is investigating the fundamental factors in breaking down coal at the face, which govern the production of lump coal in typical mines working, different coal beds. Tiffany and Nelson in 1923-21 conducted tests on methods of blasting and use of different explosives, in a mine working the Pittsburgh bed in Pennsylvania. They determined come of these factors quantitatively, and compared their results with those obtained when the regular mine practice was followed.Results of Previous InvestigationThe tests by Tiffany and Nelson showed that the use of the cartridge of smaller diameter than that used in mine practice, resulted in an increase of 5 per cent in the amount of lump coal passing over a 1-1/4-inch bar screen, with a reduction of 32 per cent by weight in amount of explosive required. On the other hand, they found that on reducing the weight of charge 20 per cent, and using the cartridge of larger diameter, the round would not throw down the coal satisfactorily.Experiments with ""snubbing"" showed a similar improvement in quantity of lump coal, end the coal that was blasted rolled forward into the working place. however, in recent tests at another mine where the coal Lad different physical characteristics, snubbing did not always result in the coal rolling forward, on account of clinging to the ribs, and was not found to be an advantage. Therein the writers of this paper recommend that tests be made before deciding upon the adoption of snubbing in a particular mine."

Aug 1, 1925

By Ernest E. Berger

"INTRODUCTIONOne of the outstanding problems in the normetallic industries, and one which involves two of the greatest of these industries, cement and gypsum, is the reaction of Portland cement with calcium sulphate. To all Portland cement clinker there is added in the manufacturing process, a small amount of retarder, as a necessary ingredient of the finished product. This retards the initial set, increases the strength, and adds to the plasticity of the cement so it will have the desired working and setting qualities. The retarder commonly used is gypsum, (CaSOA.2HO), which is the hydrous form calcium sulphate. Calcium sulphate is also available as plaster of Paris (CaSO4 1/2 HC) and anhydrite (CaSO4). The purpose of this inquiry was to determine the form or mixture of forms best adapted for retarder. The problem is complicated by the fact that cement clinker is a complex mixture of calcium silicates and aluminates, and that clinker from different mills, making cement of approximately equal quality, differs considerably in chemical constitution. Thus the same retarder may give very different results with different types of clinker, especially in the percentage of retarder required for the same degree of retardation.It has been known for some time that a small percentage of plaster of Paris will greatly retard the time of set of Portland cement as well as increase its strength and plasticity, but whether gypsum and anhydrite will have a similar effect is as such disputed question. The offects of gypsum have received little consideration in laboratory research because, even though it will not retard a clinker when the two are mixed in the laboratory, as has been noted in some instances, the cement will have a normal set when the two arc mixed in the large tube mill at the plant, so that practically, gypsum seems to be equally as goou as plaster of Paris, and because of the great saving in cost it has been used almost exclusively."

Sep 1, 1925

By Charles H. Shapiro

[In July, 1924, the Bureau of Mines, through its Petroleum Experiment Station, undertook a field study of methods used in oil-field shops for dressing and tempering fishtail bits. The purpose of this work was to suggest chances that would be helpful to the bit-dresser in turning out better treated, harder, and tougher bits, and thus cut down the excessive loss of time caused by too frequent changing of bits. It was the intention to eliminate as much as possible the guess work connected with dressing and tempering bits under the method of judging temperature by eye, by developing; practical methods of controlling temperature. If there were some possible means of accurate temperature control, then it would be an easy matter to bring all bits to the proper temperature for maximum hardness rued toughness, thus doing away with the source of most of the trouble experienced in the present method of bit tempering. Shortly after the Bureau of Mines began its study, a chop In the Stroud, Oklahoma, oil field announced method for tempering fishtail bits that Would increase the drilling footage of each bit treated. The method accurately regulates, by the use of a bath of molten salt, the temperature to which a bit is heated before being quenched to produce hardness. There is nothing new in using silt baths for the, heat treatment of steel, but this was the first attempt to introduce it into the oil fields for use in hardening bits, and for this purpose it proved to be admirably adapted. In tempering, by the old system it is not possible to measure the temperature of the heated bit by means of an electrical instrument for that purpose, whereas this is an easy matter with the now method. If heating steel to slightly above the critical point rind quenching suddenly will bring out its best properties, their here is a method of accurately bringing the steel to that point.]

Jan 1, 1925

By C. W., Davie

"DEFINITIONDiatomaceous earth consists almost entirely of the silicious remains of minute flowerless aquatic plants known as diatoms. The name diatomaceous earth, therefore, is to be preferred to others such as trade names, inappropriate terms, or names correctly applied to some other product. The following names should, therefore, not be used for diatomaceous earth,-- kieselguhr, infusorial earth, diatomite, celite, moler, bergnehl, English rottenstone, tripoli, tripolite, fossil earth, desmid earth, white peat, tellurine, randanite, ceyssatite, or any trade name.FORMATIONDiatoms live in practically all kinds of water, fresh or salt, hot or cold, still or running and under different conditions of depth and pressure. These minute plants assimilate inorganic salts from their environment and produce skeletons of silica much as mollusks secrete lime and form their Shalls. When the diatoms die they settle to the bottom together with anything else which may be present, such as sand, clay or volcanic ash. The organic matter gradually disappears leaving the silicious skeletons of the diatoms which, with impurities, make up the deposits of diatomaceous earth. These deposits which are still being foamed at the present time and which were produced throughout very different epochs, were more prolifically formed in the Tertiary, so that the thickest beds so far discovered are of that Age."

Nov 1, 1925

By L. D. Tracy

"The first study of this subject has been made in Illinois, but as opportunity affords, similar studies will be made in other States. It is hoped that the data obtained will assist the coal—mining industry to standardise the forms of leases, and so avoid some of the abstruse and ambiguous clauses which may be found in many of then and the consequent liability of costly litigation.In some of the publications of the Illinois Mining Investigations prepared under a cooperative agreement with the U. S. Bureau of Mines, the Illinois State Geological Survey and the Engineering Experiment Station of the University of Illinois, the coal areas of the State have been dividedinto eight geological districts, each district being treated separately.report covers District No. VI of that classification, and it is hopedstudies of the other districts will be completed in the near future and similar results published.The report includes a short description of the geological condition the character and quality of the coal and the nature of the surface, data for which have been taken largely from the Illinois Geological Survey publications.Mining methods and percentages of recovery are mentioned, together physisal conditions, market and transportation facilities, because all of these factors have a bearing on royalties and leasing conditions."

Jan 1, 1926

By J. F. Barkley

"In the course of the Government's Fuel Economy Survey of its own power plants, studies and tests have been made of various oil-burning equipments under power-plant boilers. There are now many types of burners being offered in the relatively limited field of power-plant use. The majority of the types used may be grouped into two general classes- those using steam to effect the atomizing of the oil, and those using mechanical means.Burners using steam have had the most prominence in this field for a long period. The mechanical atomizing type of burner successfully applied on shipboard, however, pointed to a possible betterment in land work. The vision presented itself of a burner that would need no steam for atomizing that would permit of air inlets or registers compactly arranged as a part of the entire burner, and that would only require the natural stack draft usually available in land boiler furnaces. Hence, rather recently there has been much development along this line, resulting in various types of burners.In Table 1 are grouped test items chosen from many tests showing representative analyses of the products of combustion obtained with various burners installed in various types of furnaces. In all these tests the burners were handled by experts and represent practically the best attainable for that particular arrangement. The boiler efficiencies ranged from 70% to 80%. It will be noted that the burners using steam for atomizing were able to secure slightly better 002 and less 02 without the presence of CO."

Feb 1, 1926

By F. V. Meriwether

The Bureau of Mines, in cooperation with the Federal, State, and local health services, and the mining companies, and miners? organizations, has for several years been carrying on sanitary surveys of mining districts in various states, with the purpose of collecting information on good and poor practices in mine sanitation, construction of approved wash-houses and change houses, the measures being taken to combat preventable diseases, the essential features of good houses for mining towns, and other conditions affecting the health and efficiency of miners and their families. The knowledge thus gained is disseminated for the common benefit of the mining industry. The sanitary conditions in the coal-mining districts of Alabama, as found by a recent survey made by the writer, are presented in this report. In addition to the towns on which this report is chiefly based, at least twice as many were visited where no details :were taken, but their general conditions are taken into consideration in summing conditions in the coal districts.

Jan 1, 1926

By Oliver Bowles

Since 1922 when the Bureau of Mines issued a report2 covering the slate industry in detail, changes in technology have taken place which have an important bearing on the industry. The present paper comprises a record of these changes. Though the value of slate, for roofing, structural, blackboard, sanitary, and electrical uses is generally recognized, it has many competitors. To meet this constantly increasing competition producers are promoting economies in manufacture, and improving processes, thereby lessening costs of production, and are placing on the market products of the highest possible quality, thus creating satisfaction and confidence on the part of the user. This endeavor to place the industry on a better basis, both as regards processes and products, is shown in the recent developments in technology which are presented herein. Valuable assistance in obtaining data for this paper was given by W. S. Hays, secretary of the National Slate Association, N. M. Male, president of the National Slate Association, and Robert Notvest, consulting engineer, Cleveland, O.

Jan 1, 1926

By Wm. W. Odell

A study of certain gas making and fuel problems peculiar to the gas industry of California has been made by the Bureau of Mines. The work was done at the request of, and in cooperation with The California Gas Research Council 2, for the purpose of obtaining basic information on the gas-making fuels available to California, and their applicability to the present and future needs of the gas industry in that State. The data obtained have been applied in outlining a construction program, and indicate the possibilities in efficiently utilizing fuels in making gas by other than the oil-gas process. This paper presents an outline of the study and a summary of the principal results obtained, with some of the more important conclusions and recommendations based on this data. Gas is produced in California by processes which are both unique and different from those common to other parts of the United States. The bulk of the manufactured gas is made in and distributed from two main districts which are centers of population - namely, the Los Angeles district and the San Francisco Bay district. The gas manufactured in the Bay district is, almost exclusively oil-gas, whereas that produced in the southern part of the State, where natural gas is available, is mostly mixed natural gas and reformed-gas, but oil-gas is the chief product when the supply of natural gas is inadequate. Practically all of the gas companies are equipped with oil-gas generating apparatus, and anticipate using it in the future. As the continued use of the oil-gas process to the exclusion of all other processes, depends upon a continued supply of oil at a low cost, and the prospect of obtaining such low-priced oil in the future is somewhat uncertain, the questions have arisen: What will the future gas-making process or processes be? When will it be necessary to make plans for the installation of different gas generating equipment, and what will that equipment comprise?

Jan 1, 1926

By W. P. Yant, H. C. Fowler

"INTRODUCTIONHydrogen sulphide is probably the most toxic gas associated with crude oil. Hydrocarbon (petroleum) vapors themselves are harmful to the human system, but hydrogen sulphide, when present, is usually more important from the standpoint of health and safety. These conclusions were reached in an investigation of the toxic gases encountered in the transportation end refining of high-sulphur petroleum. The results of that investigation are presented in Bureau of Mines Bulletin 23l. although the writers of Bulletin 231 paid no direct attention to the production of oil in the field, they attributed to hydrogen sulphide reports of accidents caused by gas in the oil fields of Mexico.During the development of oil fields in Texas, a ""poison gas"" was encountered that constituted a decided health and safety hazard. The present report discusses an investigation of this gas made in July, 1926.The major portion of the investigation was conducted in the Panhandle field of Texas, but the study also includes the Big Lake and McCamey fields.Scope of WorkThe work undertaken in each field included:Examination of the gas-coming from representative wells at various locations in the field; also analyses of the gas-air mixtures to which the workmen were or might be exposed.Observation of symptoms of poisoning and severity of these symptoms."

Oct 1, 1926

By L. D. Tracy

This is the third of the series of reports on coal-mine royalties and leasing conditions in Illinois. The results of the study of District VI were published as Serial No. 2726, January, 1926, and those of District VIII as Serial No. 2745, April, 1926, of the Bureau of mines. The counties of Macoupin, Sangamon, and Montgomery, which are three of the principal coal-producing areas in the northern part of District VII, have been chosen for this report because these counties cover an entirely different part of the State than do the two districts already covered. Some leases in, Randolph and Washington counties are included as they are in the southern part of the district, and the data happened to be readily available.

Jan 1, 1926

By W. W. Adams

"Accidents at coal mines in the United States in September 1926 resulted in the loss of 170 lives, according to information furnished to the Bureau of Mines, Department of Commerce, by State mine inspectors. Of this number 125 occurred at bituminous mines and 45 in the anthracite field. As the bituminous output of coal for September was 48,976,000 tons, and the production of anthracite was 8,444,000 tons, the fatalities reported represented a death rate of 2.55 per million tons for bituminous mines and 5.33 for anthracite mines. The industry as a whole showed a fatality rate of 2.6 per million tons of coal produced in September 1925 the rate for bituminous coal mines was 3.29; the anthracite mines were idle in September last year due to a strike.During the first nine months of the present year 1,759 men have been killed by accidents at the coal mines throughout the United States, resulting in a death rate, per million tons of coal produced, of 3.76 as compared with 3.95 for the same period in 1925. Reports for bituminous mines alone showed a nine-month fatality rate of 3.53 which was about the same as the corresponding rate from January to September in 1925. The anthracite rate for the present year, however, shows a decrease of about 17 per cent; that is, the rate has declined from 6.36 to 5.28.Records covering the first nine months of 1926 show that 12 ""major"" disasters, that is, disasters in which five or more men were killed at one time, have resulted in the loss of 271 lives as against 10 disasters and 199 deaths in the corresponding months in 1925. The fatality rates for these disaster: alone were 0.579 and 0.465, respectively. One major explosion occurred at Tahona, Oklahoma, on September 3, 1926, in which 16 men lost their lives.An analysis of the principal causes of the 1,759 fatalities for the first nine months of the present year shows a reduction in the death rate as a whole and for falls of roof and coal and for explosives, but an increase in haulage, gas and dust explosions, and electricity. The comparative rates for these accidents were:"

Oct 1, 1926

By W. W. Adams

"A recent paper prepared by the writer summarized the results of an analysis of the accident records of 34 metal mines for the calendar year 1925. The present paper summarizes the results of a similar analysis of the accident records of 59 coal mines for the same year. This summary is based upon reports furnished to the Bureau of Mines, Department of Commerce, by operating companies that par¬ticipated in the National Safety Competition of 1925.The purpose of the Competition was to establish the lowest accident-severity rate, thus showing the smallest loss of time from accidents in proportion to total number of man-hours worked. The reports covered all lost-time accidents that occurred during the year, that is, all accidents that disabled an employee beyond the day or shift on which the accident occurred. Detailed information for each of the 59 coal mines is given in the appended table. Each mine employed at least fifty men underground; over half of than employed more than 200 men underground. Hence the accident records should be typical of those of large-scale mining operations in general where the company is devoting special attention to accident-prevention work. The mines covered by the reports are situated in eleven States: Alabama, Illinois, Indiana, Kentucky, Maryland, Ohio, Pennsylvania, Tennessee, Utah, Washington, and West Virginia.A tabulation of the reports covering the 59 mines showed an accident-frequency rate of 123 per million hours of ""exposure* and an accident-severity rate of 10.214 per thousand hours of exposure3. The total volume of exposure or employment was 29,117,561 hours, representing the equivalent of work of 12,000 men for three hundred 8-hour shifts. The records covered employment and accident above ground as well as underground, although they did not include stripping or open-pit mining. Accidents during the year resulted in 33 deaths, 1 permanent total disability, 28 permanent partial disabilities, and 3,510 temporary injuries. These accidents represented a loss of tine equal to 297,417 man days. In arriving at this lost-time equivalent, each fatality and permanent total disability was weighted at 6,000 lost days (see footnote 3), as specified in the scale adopted by the International Association of Industrial Accident Boards and Commissions; permanent partial disabilities were weighted according to nature of injury, in accordance with the scale adopted by the :Board; temporary injuries were weighted according to the actual number of calendar days during which the employee was incapacitated as a result of the injury."

Nov 1, 1926

By L. D. Tracy

"IntroductionOne of the problems which the coal-mining industry must solve in the next few years is the redaction of its ever-increasing timber bill. This includes pit posts, mine tees, timber sets, and brattice boards. As an example of this increase, the following table of timber prices from the records of a coal company in western Pennsylvania, in a district where the supply of most of the different kinds of timber used can be shipped from points within the State, is self-explanatory: Present conditions seem to indicate the continued upward trend ox the cost of mine timber, although the regrettable calamity that has visited the chestnut timber in Pennsylvania may temporarily hold the price of some types of mine timber on a level basis. On account of the chestnut blight, many farmers will undoubtedly begin to convert their chestnut trees into timber before they become a total loss. This may provide, for the time being, a sufficient supply of mine timber to check the steadily rising prices.The local lumber producers are turning their attention to the production of the larger sizes of timber and lumber on account of an unfavorable price on mine ties. From the foregoing table, it is seen that the average advance in the price of ties during the period 1914 to 1920 is 52 per cent, while timber sets and mine car plank increased in value 60 per cent. Amore striking illustration is the fact that a 6 by 8 inch by 6 foot tie sells for 42 cents or at the rate of $17.50 per 1000 board feet; yet mine car plank and timber sets have a value of $48 per 1000 feet, an advantage of $30.50 in favor of the heavier timber.The supply of coal in Western and Central Pennsylvania will last for a long period and it is for the possible future demand for timber that the coal companies must provide. While steel, concrete, and other materials may, in many cases, prove an acceptable substitute, there is no doubt that timber will always be in demand."

Nov 1, 1926

By E. D. Gardner

The Bureau of nines, in cooperation with the mining companies of the Southwest, is conducting an investigating to ascertain the safest and most economical explosives to use in metal mines, and to ascertain the best methods of blasting under various conditions. A part of this investigation has been a study of drilling and blasting drift rounds in metal mines. This paper covers one phase of work on drift rounds and discusses the methods of loading the individual holes of the rounds. The blasting tests, on which this paper is based, were made at the Copper queen Branch of the Phelps Dodge Corporation at Bisbee, Arizona.

Jan 1, 1927