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By Walter Lang

The year 1931 has shown a marked change over 1930 in New Mexico, with respect to the volume of activities attendant upon the petroleum industry. Although the total production of oil and gas this year exceeds that of preceding years, the results have been attained from established units operating under restriction, but capable of supplying far more than the economic conditions justify. The presidential order of March 12, 1929, that "there will be complete conservation of Government oil in this administration," has merely anticipated a normal consequence of overdevelopment. As a result of the combined economic and legal restrictions imposed, very little new drilling has occurred during the year. Even in proven areas the drilling of offsets has been curtailed to the absolute limit of requirements. Scouting and sample-cutting, which in 1930 were still in a state of feverish activity, are at low ebb, and lease buying has reached a condition of stagnation. A number of the major oil companies have either materially reduced their field and office forces or completely eliminated local office representation. Two tests of particular interest, because correlation shows them to be structurally high although they failed to produce, are the National Securities well drilled six miles west of the town of Hobbs, on sec. 33, T.18 S., R.37 E., Lea County, to a total depth of 4272 ft., which developed a flow of 4,000,000 cu. ft. of gas at 3860 ft., and a show of oil; and the Western Drilling Co. No. 1 State, sec. 16, T.20S., R.32 E., Lea County. The latter test found dead oil at 2575 to 2580 ft., and sulfur water at 2745 ft., increasing to 2780 ft., representing the zone from which production was generally expected. The well was drilled to 4013 feet. The discovery of sulfur at about 950 ft. in the deepening of an old water well (Pearson, NE. 1/4 sec. 8, T.16 S., R.25 E.) drilled in the Little Cottonwood area northwest of Artesia led the Union Sulphur Co. to drill three prospect tests on a block of acreage in the vicinity during the summer and fall. The results of the investigation have not been disclosed. The Kummbaca Oil and Gas Co. drilled the T. J. Kerline No. 1, in sec. 34, T.21 N., R.30 E., Harding County, gaging 3,654,000 cu. ft. of 98 per cent CO² at 940 ft. The Barton structure, 20 miles east of Albu-

Jan 1, 1932

To the American Institute of Mining Engineers: The committee appointed at the February meeting upon Railway Resistances would respectfully report: That one person has been constantly employed in calculating the results of the data taken prior to March 1st, 1876. Also to complete the data taken upon the Lake Shore and Michigan Southern Railway, a diagram was taken upon a through freight train from Cleveland to Chicago, and one from Chicago to Cleveland. So that now we have diagrams from Buffalo to Chicago and return, which, when fully worked up, will give results of the utmost importance in determining the cost of transportation of freight. These data will be of much importance in determining the proper methods of equating grades and curves, which is so essential in the location of new lines. The calculations show that instead of our attempting to formulate results from data obtained on one road, it will be best for the interests of transportation to enlarge the scope of our inquiries, and to extend the experiments so as to include all of the more probable causes which affect the cost of transportation. Were the details of railway equipment constructed alike, much work, which is now necessary, would be saved. It is not uncommon to find upon the same road 10 to 30 different patterns of something in construction to subserve the same purpose, which more or less modifies the friction of the cars. Take the majority of our trunk lines, with this diversity of construction, together with the varying conditions of track and manner of operating, and it will be at once seen that the labor and time to do the work and arrive at correct conclusions will occupy from two to three years. The results already attained in the short time in which they have been carried on, wholly by private enterprise, simply show what may be expected when the aid necessary is given to render them of the highest value to the great industries of the country. That the information may be general and of the greatest importance to our railway interests, the committee deem it advisable to secure, so

By Clarence A. Seyler

The object of all classification is to group together things which are alike, and separate those which are unlike. This object is essentially a practical one, enabling us to apply past experience to new conditions. Many costly large-scale experiments lose half their importance for want of proper description of the coal used, and the consequent impossibility of predicting that other coals will behave in the same way. I do not, therefore, make a fundamental distinction between "scientific'' and "use" classifications, except in so far as use depends on conditions, such as size or impurities which are not related to the nature of the coal substance itself. The characters chosen to define the classes of coal must be such as are accompanied by as many other properties as possible. It is not to be expected that any system of classification will enable us to predict every property of coal, since all specimens have an individuality of their own. But specimens can be grouped by a number of resemblances into species. Further, species which resemble each other can be grouped into genera. Elementary Composition as a Basis of Classification There can be little doubt that the ultimate or elementary composition of "pure coal" is the best basis of classification. It was soon after the perfection of the method of elementary analysis of organic substances by Liebig that Regnault, the distinguished chemist and physicist, laid down the principle that coals of the same kind vary only between narrow limits of elementary composition. This is still the widest generalization that can be made about coal. Upon it the metallurgist Gruner based his classification. In some quarters the value of the ultimate composition was denied, Stein going so far as to say that it teaches us nothing of importance about coal. One still hears statements that it is like crushing a work of art in a mortar and analyzing the powder, or like counting the number of times a given letter occurs in a sentence. Such comparisons are misleading, and the criticism might be applied to organic chemistry as a whole. Nor is the existence of isomerism, or of entirely different substances which

Jan 1, 1928

By Ionel I. Gardescu

In connection with some of the experiments carried out by the writer on the behavior of gas and oil in a sand reservoir,' an interesting phenomenon was observed which may throw some new light on the problem of recovery of oil from a natural reservoir. The experiments are intended to show the effect of the surface area of the occluded gas masses, originally present in a reservoir, on the further evolution of gas from the oil and its consequent effect upon the rate of production of oil. The apparatus used in the experimental work is shown in Fig. 1. It consists primarily of a sand reservoir R and a displacement chamber D, which is used to induce small variations in volume. The reservoir and displacement chamber form a unit, and a lowering of the plunger D is equivalent to increasing the volume occupied by the oil and gas in the reservoir. The reservoir was first filled with dead oil and maintained under pressure until it was ascertained that most of the free gas had gone into solution. The volume of free gas present in the reservoir was computed from the coefficient of compressibility of the fluids by means of the displacement chamber D, reading to 0.005 c.c. and a special gage J reading to 0.02 lb. per sq. in. The oil was saturated with gas under pressure in reservoir S by circulating the oil for a long period of time through the gear pump B. Subsequently, the saturated oil was circulated through the sand reservoir following the circuit S6, B, S6, R4, the sand reservoir R, R1, R², F4, F1, back to reservoir S. In the following experiments the sand reservoir R was filled with gas-saturated oil at a pressure of 415Ib. per sq. in. with no free gas present. This was ascertained by closing off all the outlet valves and determining the coefficient of compressibility of the system by means of the displacement chamber D. Much difficulty was encountered in eliminating all of the free gas masses from the oil reservoir. The dead oil originally present in the

Jan 1, 1932

By J. D. Davis, A. C. Fieldner

The older coal chemist had a much simpler conception of coal than we have today. To him coal was a mineral composed essentially of carbon, hydrogen, oxygen, nitrogen, sulfur, ash, and water, in various proportions. His studies on the constitution of coal were directed along the conventional lines of proximate and ultimate chemical analyses and making deductions from these data without any real appreciation of the fact that coal is a conglomerate of various chemical compounds, including many of the most complex structures known to organic chemistry. The view of the modern coal chemist is well expressed by Franz Fischer,' who says that while proximate and ultimate analyses are important both from the scientific and technical point of view, they tell the chemist no more concerning the number and kinds of chemical compounds that constitute coal than the reader would learn of the contents of a book if told that the printed contents consisted of 15 per cent. of the letter "e," 5 per cent. of the letter "n," 1 per cent. of the letter"g," 4 per cent. of the letter "b," etc. As the reader must have the grouping of letters into words and words into sentences, so the chemist must have the grouping of atoms into molecules and the proportion of each molecular compound in the coal aggregate before he acquires an adequate knowledge of the constitution of coal. Modern investigators2 are laying the foundation of a new chemistry of coal based on the biochemistry of plants and the chemical changes involved in processes of fermentation and decay. As

Jan 1, 1925

Jan 1, 1924

Jan 1, 1924

By W. F. Boericke

THE character of the Wisconsin orebodies must be clearly understood to appreciate the difficulties encountered in sampling and estimating them. Unlike the western vein deposits, they do not lie between regular walls, but form large, often highly irregular bodies, on a single floor in the so-called Galena limestone. The bottom of the ore is nearly always on the clay bed, a flat generally well-defined clay seam a few inches thick, which marks the junction of the base of the Galena lime and the top of the next formation, the Trenton lime. Above the clay bed, the orebodies make the unique pitch and flat formation described by Chamberlin.1 Theoretically, we should find two pitches, one on either side of the top crevice, diverging as they go down, with the final flats a considerable distance apart on the clay bed. The area between, known locally as core ground, should thus constitute a single defined orebody, with the richer portions near the pitches and the leaner portion in the center of the core. Practically, we find few examples of this perfect orebody. Almost invariably one pitch is better defined than the other, and often the opposite pitch is marked only by a faint line of fracture showing stronger mineralization than the wall rock, or it may be totally lacking. But with an orebody of any size or richness, at least one strong pitch usually tends to follow an east-west trend, or a quartering course. Late mining developments in the rich New Diggings field indicate that these pitches often assume a horseshoe or crescent shape, the richer ore being in the heart of the crescent and the pitches showing less mineralization as they extend outwards. In the northern end of the field, on the contrary, the pitches maintain generally a consistent direction, and have been mined for thousands of feet from the shaft. The length of the orebody may be several thousand feet, the height varying from 10 to 60 ft. and the width from 60 to 250 ft. In fact, on the core side, there is no definite end to the ore. The mineralization simply gets thinner and thinner, and the limit of working depends on the cost sheet and the profit from the recovery.

Jan 2, 1922

By George W. Small

The ore, as it is raised from the mine, has all average assay-value of $11 per ton, chiefly in the form of free gold. All the ore goes directly to the stamp-mills, of which there are two. The older and larger mill contains sixteen batteries of five stamps each, with one Frue vanner to each battery. The new mill has eight batteries of five stamps and two Frues to each battery. The large mill is driven by Leffel turbine wheels, with a pressure of eighty feet, and a consumption of 600 miners' inches of water. The smaller mill is driven by "hurdy-gurdy" wheels with a pressure of about 550 feet and a consumption of 150 inches of water. At both mills the tailings from the stamps pass over about 20 feet of plates on their way to the Frues. In each set of plates the first or upper one is copper, the rest are so-called silver plates. The bullion from the stamps is about 800 fine in gold and 200 in silver. The concentrates from the Frues average from 11/4 to 1 ; per cent. of the ore stamped. They very rarely exceed 2 per cent. I was unable to get the exact assay-value of the concentrates, but it is said to vary between $100 and $200 per ton. The concentrates are treated at the chlorination works at the rate of one hundred tons per month. The capacity of the works is somewhat greater than this, but as the supply of concentrates is limited it is not deemed advisable to work them up any faster. Care is taken to keep the concentrates always damp until they are put into the roasting furnace. If this is not done, a decomposition of the pyrites begins, forming lumps which do not roast, and which consequently cause a loss of gold in the residues from leaching. A Fortschaufelungsofen is used for roasting. Its dimensions, incloding fire-box, are 12' X 80'. The hearth is one continuous plane, but the charges, of which there are three in the furnace at one time, are kept entirely separate. The furnace-men call the three compartments, the "drying," the " burning," and the " cooking" compartments. In the middle, or "burning" compartment, the ore is spread

Jan 1, 1887

By John Jan

Iodine is a soft, lustrous, grayish-black non- metallic element with a density of 4.9. It is the least active of the four members of the halogen family. The other members are, in order of increasing activity, bromine, chlorine, and fluorine. Iodine is a solid at ordinary temperatures, while bromine is a liquid and chlorine and fluorine are gases. Iodine melts at 113°C and volatilizes at 184.4°C to a blue- violet gas with an irritating odor. It occurs in nature only as iodates and iodides or other combined forms. It was discovered by Bernard Courtois in France in 1811, who noticed its presence as an unknown substance in crude soda ash obtained from burning seaweed. Gay-Lussac recognized it as a new element and named it iode, from the Greek word "ioeides or iodes" for violet color (MacMillan, 1970). The world production is not known with any great certainty, but it is probably between 20 and 25 million lb per year, of which about 25% is consumed in the United States. Geology and Mineralogy Iodine compounds occur as a minor constituent as a mineral in the Chilean nitrate deposits and in solution in brines and sea- water. According to the U.S. Geological Survey, it is the 47th most abundant element in the earth's crust. The minerals lautarite, Ca (10,) (calcium iodate), and dietzeite, Ca, (10,) , (CrO,) , (calcium iodate-chromate) are found in Chilean nitrate deposits which are located in Antofagasta and Tarapach provinces on the eastern slope of the coast range in a desert area. Various brines contain iodine compounds. Seawater contains about 0.05 ppm of iodine and some seaweeds will extract and accumulate it up to 0.45% on a dry basis. Some coals in West Germany also contain iodine compounds. The known and potential sources of iodine reported in 1968 are given in [Table 1]. Iodine has been recovered from brines in Java, Indonesia, France, England, and the USSR. Iodine has also been recovered from seaweed in Ireland, Scotland, France, Japan, Norway, and the USSR. The indicated re- serves and future resources of iodine are large but have never been adequately measured. Analysis Iodine as the free element can be detected by the characteristic blue color it gives to a starch solution. Quantitatively it is determined as the free element by titration with standard thiosulfate solutions using starch as an indicator. Colorimetric methods are also applicable.

Jan 1, 1975

By C. W. Reith

The development of production in West Texas during the year 1933 was largely confined to the expansion of proven areas, especially Ward County, Iatan and North Winkler. Wildcat activity was at a comparatively low ebb and resulted only in discoveries of probable minor importance in Ector County. The interest shown in deep wildcatting to test beds of pre-Permian age was a new development, which should soon throw light on the possibilities of deeper production from the present producing fields. The important pre-Permian tests of the year were: 1. Stanolind Oil and Gas Co., Todd No. 1, a unitized test, in north central Crockett County on a probable continuation of the Big Lake trend. The well encountered several showings of oil and penetrated an Ordovician section very similar to the productive zones at Big Lake, but was abandoned when sulfur water was encountered at 8041 feet. 2. Gulf Production Co., McElroy No. 103, in the McElroy Field, Upton County. The well was drilling at 8553 ft. at the close of the year in beds of probable pre-Permian age. The test is an important one because it should prove or disprove deep production in the Church-Fields-McElroy pools and also throw geologic light on the deep possibilities of other fields in the western part of the Permian Basin. 3. Humble Oil and Refining Co., White and Baker No. 1, in Pecos County, about 11 miles west of the Yates field. The well is on a nonproductive Permian high and should indicate the deep possibilities of the Yates field. At the end of the year, drilling had progressed to 7200 ft., where beds of pre-Permian age are believed to have been penetrated. The major fields in West Texas, in which present-day proration had its inception, were produced under increased restrictions. A date of importance in the proration history of the area was $ept. 8, 1933, when the Railroad Commission issued an order placing all producing wells under proration. The severe reductions in total outlet made during 1933 were well compensated for by a more than threefold increase in the price of crude oil. Acid treatment was one of the general engineering developments of interest. The work had not progressed sufficie~ltly at the close of 1933

Jan 1, 1934

By James W. Malcomson

The Tigre Mining Co. of Mexico, owned by the Lucky Tiger Combination Gold Mining Co. of Kansas City, decided early in 1910 to enlarge its mill, which consisted of a concentrator milling 3,000 tons of ore per month. The enlarged plant was designed to crush and concentrate 6,000 of ore and to cyanide 7,500 tons per month. The extra tonnage cyanided was to be obtained from tailings which were stored below the old mill. Power was supplied to the old mill from four boilers; a 150-h-p. Corliss engine and two Weber 60-h-p. gas-engines using producer-gas made from charcoal. The total horse-power required, including 60 h-p. used for machine-drills in the mine, was approximately 275. Cord-wood cost $4.32 per cord, 8 by 4 by 3 ft., and charcoal $15 per ton. The fuel supply in the surrounding country was approaching exhaustion; more than 150 mules and 50 men were engaged in cutting and transporting this fuel, and the unsettled political conditions in Sonora were such that it would be practically impossible to keep an organization of this kind together. The price of fuel was steadily rising and at times it became almost impossible to get sufficient fuel to operate. It was estimated that the enlarged plant, together with the mine, would require 750 h-p., as follows: Horse-Power. Old mill, which was left unchanged,..............180 New concentrator,.......................90 Cyanide-plant,........................380 Mine and other requirements,................. 100 Total,........•..................750 In a study of the best manner to obtain power the following alternative propositions were considered:

Jan 1, 1914

By C. E. Wood, T. L. Joseph

This paper is a brief report of experimental work undertaken determine whether barium oxide in any quantity increases the desulfur ing action of blast-furnace slags. Industrial furnace operation wi slag containing small quantities of barium oxide, referred to later, intc ested S. A. Sanford of the Commercial Chemical Co., Youngstown, Oh to conduct experiments to furnish comparative results on desulfurizati with normal slag and slag containing small quantities of barium oxic The U. S. Bureau of Mines agreed to assist on the problem because the possible saving in fuel if the desulfurizing action of blast-furna slag can be substantially increased, also because the experiments woi yield new information on sulfur elimination in general, a matter economic importance in furnace practice. A more complete and func mental study of desulfurization of iron by slag is in progress. Distribution of Sulfur iN the Blast Furnace More than 90 per cent. of the total sulfur entering the blast furnz is in the coke. Sponge iron formed by reduction of iron oxides absor part of the sulfur as ferrous sulfide. Kinney's examination of sample taken from various levels of a 3004,011 furnace, shows that the me continues to take up sulfur until it reaches a level near the tuyer Desulfurization must therefore take place as the metal falls through t slag and as the slag and metal exist as layers in the crucible. The relative amounts of sulfur removed while the metal falls throu the slag and while the slag and metal exist as layers in t crucible are not definitely known. Preliminary experiments by t

Jan 1, 1929

By D. A. Lyon

Discussion of the paper of DORSEY A. LYON and ROBERT M. KEENEY, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1707 to 1730. LAWRENCE ADDICKS, Douglas, Ariz.-I think papers of this character, while general in, nature, are of particular value and interest, because when we figure on competing with the East in electrometallurgical industries, on account of the cheap power on the Pacific Coast, we have to take two or three things into account. In the first place, power very rarely amounts to more than 20 per cent. of the total cost of an operation, even .though it be electrometallurgical, and I think it is the common opinion among those who are not familiar with those particular industries, that it amounts to more than 50 or 60 per cent. Take copper refining; we may say that it is 15 per cent. of the total cost. In the second place, around New York City, with 100 per cent. load factor and a reasonably large load, say 10,000 kw., we can generate from a certain class of coal 1 kw.-hr. for about 0.3c. I might say, however, that 0.3c. does not include overhead charges, interest on the investment, etc. The third factor we have to consider out here is that any product to be salable, must command a retail market. It would be useless to produce wire bars here on the Pacific Coast because there is no place to roll them. If we were going to establish a copper refinery, that part of its output which goes into wire bars would have to be taken care of by building a rolling mill alongside of it to turn it into wire and finally make a product that is salable. I do not think, however, that Mr. Lyon need have excluded copper refining from his industries. There are perhaps 50,000,000 lb. of copper a month refined in this country on a custom basis. I think the smelting companies would be very glad to build refineries here if conditions warranted it. The recent extensions of the Great Falls refinery and of the Tacoma refinery in the last few months give evidence of that.

Jan 12, 1915

By Harold R. Bradford

EXPANSION initiated during and after the war has placed industrial plants in new areas and increased reduction and manufacturing facilities in communities already established. With added expansion interest has grown in possible area contamination from waste products. Evolved flue waste contains many chemical contaminants that may or may not cause concern; however, atmospheric pollution has always been a problem to industrial communities. For some time effects attributed to small quantities of compounds of fluorine in various waste gases have been studied by industrial, medical, agricultural, and associated interests.1'2 Aside from an article by Churchill, Rowley, and Martin in 1948," little has been published on the subject of fluorine in coal except by foreign investigators. The first indication of fluorine compounds in coal was noted in England in 1934 by R. Lessing,4,5 who found that the presence of fluorine in Midland and West County coals was definitely established by etching of glass and by severe corrosion of porcelain fillings in a gas works scrubber. Etching of glass in a direct contact annealing kiln initiated research, and in 1944 four papers were published by H. E. Crossley,6-9 giving results of investigations of fluorine in coal of England by the Fuel Research Board, Department of Scientific and Industrial Research. These investigations studied methods of determining fluorine, the quantities present in various coal deposits, the geographical distribution of fluorine in British coals, occurrence of fluorine in minerals associated with coal, amounts of fluorine compared to other constituents of coal, the nature of fluorine compounds, and industrial significance of fluorine in coal. It was shown that British coals contain from 5 to 200 ppm of fluorine, which is probably present as fluorapatite [Ca10F2(PO4)6], often written as [3Ca3P2O8.CaF2]. The fluorapatite is intimately associated with shale in some coals and can often be separated from these coals along with the shales. H. E. Crossley8 also reported no correlation between the amounts of chlorine, sulfur, or ash and the amount of fluorine in different coals. He found, however, a relationship between the content of fluorine and phosporus in many British coals. Thus it should be possible to anticipate likely fluorine-rich coals from existing data giving phosphorus content. Behavior of the fluorine compounds of coal was compared with that of 12 fluoride-phosphate minerals in sink-float separations and solvent ex-

Jan 1, 1958

By Norman D. Fitzgerald

The purpose of this paper is to analyze the behavior of oil securities during the six-year period January 1932 through December 1937. This period was selected because of its varied character. It includes the depths of the depression, the broad and spasmodic recovery, and the recession collapse. The first part of the analysis is devoted to the correlation of a number of economic factors with an index of 13 oil stocks. The second part is a comparison of the different,ial behavior of 6 oil stocks. The relationships developed here are only a few of many that might be considered in a complete analysis. The stock market is regarded as a barometer of business confidence and as such exerts an important influence upon corporate policies, particularly upon industrial expansion. The complex and continuously changing nature of its price structure, the ebb and flow of influences and the effects of impacts require dynamic rather than static analysis. When treated in this way, many of the important fluctuations in market prices and changes in the relationships between securities appear quite logical. The market for oil securities has varied widely in recent years. The Standard Statistics index of 13 oil stocks made a bull market peak of 166.7 in September 1929. The collapse of the boom and the ensuing bear market finally carried the index down to a low of 36.4 in June 1932. From this point oil stocks made an irregular recovery; they reached a top at 139.7 in March 1937, and after maintaining this approximate level through August, declined precipitously to 93.3 in December 1937. The prices of these 13 oil stocks have gone up and down under the influence of numberless variables. These variables are of two kinds, those external to the industry, and those that are solely due to its internal condition. The external factors are political, social, and economic, both domestic and foreign. These are the influences that induce the ebb and flow of all prices in general and security prices in particular. Among the internal factors are the regulation of industry, the development of new reserves and processes, and the disequilibrium due to lack of balance between supply and demand. Some of the simpler relationships are examined in this paper.

Jan 1, 1938

By F. L. Bosqui

Discussion of the paper of F. L. Bosqui, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 101, May, 1915, pp. 997 to 1033. H. A. WHITE, Springs, Transvaal (communication to the Secretary*). -It is, as the author points out in his valuable paper, a, fact, that in many plants the "trommel washings" are allowed to become eyesores, but the simpler system of pumping the entire product direct to the tube-mill circuit will avoid the extra expense of separation and small-scale treatment when one considers the relative distance of the points and the proportionately small amount of water. It is a matter of record that in stamp batteries the increase of weight has been developed concurrently with the increased use of tube mills, but independently and on its own merits. The satisfactory duty, excellent running time, and freedom from breakages in the newer mills, such as the Modder Deep, with 2,000-1b. stamps, will probably go far in removing some of the conservative prejudices mentioned by Mr. Bosqui. The success of the City Deep trial of the Nissen stamp cannot be entirely attributed to better feed distribution and discharge effects (published experiments on two-face discharge mortar boxes showed no advantages). Attention is directed to the treatment costs given by the author both before and after the increased capacity resulting from the addition of 16 Nissen stamps at Modder B. It will be observed that the only item of cost resisting the tendency to reduction caused by increased tonnage is that of milling, which has risen 1.3c. With reference to the provision for amalgamation in the new plans, it seems obvious that a great loss of head would be eliminated by passing the tube cone overflow over a separate top series of plates; three at the top and three at the bottom will effect the maximum amalgamation. This plan is followed at the Princess Estate and Gold Mining Co., Ltd., Modderfontein Deep Levels, Ltd., and Geduld Proprietary. Mines, Ltd., but elsewhere reliance is placed upon ample cone capacity and the underflow only is passed over three plates after going through the tube mill, while the overflow is passed direct to the cyanide works; both methods avoid the largely unnecessary elevation of considerable quantities of water, fine sand and slime involved in Mr. Bosqui's scheme.

Jan 1, 1916

By W. C. Williamson, J. L. Shugert

DUST control is receiving considerable attention today by most companies as is evidenced by the many articles, papers, and books written on the subject. ~~~t of the larger mining companies have given this subject close study and have established standardized methods of control. W. C. WILLIAMSON and J. L. SHUGERT, Members AIME, are Assistant Ventilation Engineers, Anaconda Copper Mining Co., Butte, Mont. San Francisco Meeting, February 1949. TP 2705 A. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received Jan. 17, 1949. Permissible Limits: The question of permissible dust limits has been considered by medical commit-ties and various national conferences. Dr. Lanza, of the Metropolitan Life Insurance Company, Dr. Le-roy U. Gardner, of the Saranac Laboratory for the study of Tuberculosis, and Dr. Pancoast, of the University of Pennsylvania, have been members of these committees. A statement included in reports of some of these committees is as follows: Concentrations to which the dust must be induced in order to be safe have not been absolutely determined. There is evidence that a concentration of more than five million particles per cubic foot of a highly siliceous dust is dangerous. Therefore, it may be stated that it is desirable to avoid counts of more than five million particles of dust containing free silica to a high percent in working places. Table I gives the safe limits adopted by several state industrial codes. Table I. Safe Limits of Dust Concentration Limit Million Particles State Per Cu Ft Cal~fornia Silica (less rhdn 10 pct) 50 Silica (10 pct to 50 pcr) 10 Sllica (more than 50 pct) 5 New York Frcc silica less than 10 pet by weight of rock formation 100 Frec silica more than 10 Pct by weight of rock formation 10 Oregon Silica (over 40 pct) 5 Silica (20 to 40 pct) 10 Silica (10 to 20 pet) 20 Wisconsin 15 million particles, under 10 nicrons in longest dimension per cu ft of air, when the quartz content of the dust is 35 pct, variations in free silica content will make proportional inverse changer in this standard Close attention to dust concentrations has been given to mining operations, since these operations are frequently carried on at considerable distances

Jan 1, 1951

By J. L. Shugert, W. C. Williamson

DUST control is receiving considerable attention today by most companies as is evidenced by the many articles, papers, and books written on the subject. ~~~t of the larger mining companies have given this subject close study and have established standardized methods of control. W. C. WILLIAMSON and J. L. SHUGERT, Members AIME, are Assistant Ventilation Engineers, Anaconda Copper Mining Co., Butte, Mont. San Francisco Meeting, February 1949. TP 2705 A. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received Jan. 17, 1949. Permissible Limits: The question of permissible dust limits has been considered by medical commit-ties and various national conferences. Dr. Lanza, of the Metropolitan Life Insurance Company, Dr. Le-roy U. Gardner, of the Saranac Laboratory for the study of Tuberculosis, and Dr. Pancoast, of the University of Pennsylvania, have been members of these committees. A statement included in reports of some of these committees is as follows: Concentrations to which the dust must be induced in order to be safe have not been absolutely determined. There is evidence that a concentration of more than five million particles per cubic foot of a highly siliceous dust is dangerous. Therefore, it may be stated that it is desirable to avoid counts of more than five million particles of dust containing free silica to a high percent in working places. Table I gives the safe limits adopted by several state industrial codes. Table I. Safe Limits of Dust Concentration Limit Million Particles State Per Cu Ft Cal~fornia Silica (less rhdn 10 pct) 50 Silica (10 pct to 50 pcr) 10 Sllica (more than 50 pct) 5 New York Frcc silica less than 10 pet by weight of rock formation 100 Frec silica more than 10 Pct by weight of rock formation 10 Oregon Silica (over 40 pct) 5 Silica (20 to 40 pct) 10 Silica (10 to 20 pet) 20 Wisconsin 15 million particles, under 10 nicrons in longest dimension per cu ft of air, when the quartz content of the dust is 35 pct, variations in free silica content will make proportional inverse changer in this standard Close attention to dust concentrations has been given to mining operations, since these operations are frequently carried on at considerable distances

Jan 1, 1951

By D. H. Wertz, R. R. Furlong

Dry room equipment at Donora Zinc Works is of the design which prevailed at the time the plant was built in 1915. It consists of 11 adjoining rooms, each being 99 ft long, 11 ft wide, and 7 ft high and having a capacity for 1040 retorts. Heat is supplied by steam coils beneath the slatted wood floor and by warm air ducts at the ceiling. Drying practice is about the same as that generally followed in the industry except that, under normal zinc furnace operations, the maximum drying time is 45 days. During certain seasons of the year the drying process was seriously affected by varying weather conditions which frequently resulted in a scrap loss of 5 to 7 pct. Because of these unfavorable conditions, which caused uneven drying and strains in the retorts, increased retort failures in the zinc furnaces were recorded. Regulation of temperature and humidity under all conditions appeared to be the logical solution of this problem. Controlled drying had been developed for a number of ceramic products and investigation of several such drying processes in this area revealed favorable results. Along with control of drying conditions and the attendant decrease in scrap losses, plant operators also reported a material reduction in drying time. Another factor affecting the decision to proceed with this development was the drastic change in market conditions for retort clay. Curtailment of shipments from the chief source of supply made it necessary to proceed with blending of other available clays, but quality of these clays was questionable for adequate retort life in the 24 hr furnace cycle. Rapid furnace testing of new mixtures was desirable but impossible with the prolonged drying schedule. Therefore development of a controlled drying process for zinc re- torts offered the solution to the problem of rapid testing of retort mixtures. Description of Process and Equipment The freshly extruded retort is cylindrical in shape, 58 in. long, 9 in. id and has 1 1/8 in. side walls. One end is closed and approximately 2 in. thick. The moisture content of this "green" retort is about 17 pct which means a necessary removal of 30 lb of water per retort. Retorts are set on the slatted floor of the dry room with the closed end down. The controlled drying process depends upon the circulation of a large volume of conditioned air at low velocity. To provide for uniform distribu-

Jan 1, 1950