January, 1923
INDUSTRIAL A N D ENGINEERING CHEMISTRY
is well designed, embodying several new principles, and has shown excellent thermal efficiencies over long periods of operation. CONTACT PROCESS There are four contact processes in successful operation: the Badische, Mannheim, Grillo-Schroeder, and Tentelew systems. Very few improvements of recent date have been recorded in the manufacture of contact acid. H. F. Merriaml3 has patented a process which consists of drying the air used for combustion of brimstone. This procedure permits the passage of the hot burner gases to the converter after being slightly cooled to the proper temperature. The advantages claimed are: (1) conservation of heat; (2) simplicity and stability of apparatus; (3) longer life of contact mass because of the elimination of sulfuric acid mist. F. Slama and H. WolfL4have patented a catalyst consist-
13
ing of vanadium oxide deposited on pumice or kieselguhr. A 96 per cent conversion of sulfur dioxide to sulfur trioxide is claimed with this catalyst. . W. A. Patrick15 proposes a process for the conversion of sulfur dioxide to sulfur trioxide catalytically by passing the gases through silica-gel previourly treated with certain metallic salts. The process has not been tried out on a commercial scale as yet but experimental work has been in progress for some time. PATENT REFERENCES 1-U S. Patent 932, 771 (1909). 2-Fr. Patent 528,080. 3-U. S. Patents 1, 112,546 (1914); 1,312,741 (1919); 1,312,742 (1919). 4-U. S. Patent 1,402, 941 (1922). 5-U. S. Patent 1,012,421 (1911). 6-Brit. Patent 156,328 (1921). 7-TJ. S. Patents 1, 334, 384 (1920); 1,342, 024 (1920).
8-Brit. Patent 9-Brit. Patent 10-Brit. Patent 11-U. S. Patent 12-Brit. Patent 13-U. S. Patent 14-U. S. Patent 15-Brit. Patent
159, 156 (1920). 149, 648 (1920). 164, 572 (1920). 1, 363,918 (1920). 163,030 (1921). 1,384, 566 (1921). 1, 371,004 (1921). 159, 508 (1921).
Stabilizing t h e Sulfur Market for Chemical Industry By Harold S. Davis ARTHURD. LITTLE, INC., CAMBRIDGE, MAPS.
HE STABILITY of any industry is
T
greatly influenced by the degree of accuracy with which the prices of the raw materials it needs can be predicted, Sulfur, owing mainly to the everincreasing usefulness of sulfuric acid, has become one of the basic elements for chemical industry. Let the reader consider for a moment whether, if the price of sulfuric acid were to double in the next few yeam, the particular organization with which he is affiliated would not be adversely affected by the rising price of some necessary raw material. It is therefore a great satisfaction to be able to predict a stable sulfur market in America for a t least the next ten years, with almost complete independence of production and consumption in foreign countries. THEPAST Up to the present century, only negHAROLD S. ligible quantities of sulfur were mined in the United States and practically the world’s supply came from Sicily.- The deposits in this idand contained originally about 65 million tons of sulfur available for mining.l More than half of this has now been mined, The total sulfur recovered up to 1885 was estimated at 10 million tons and 13.6 million long tons were exported from 1885-1919.2 About one-quarter of the sulfur mined has been lost in processing, a factor which must be considered in estimating the value of the supplies that remain. In the past the methods of mining were very crude, manual labor being employed for the most part in transporting the ore from the pits to the surface. Even to-day, thousands of children still work in the Sicilian mines.3 The methods used for separating the sulfur from the ore were also very wasteful. 1 J . JOG. Chem. I n d . , 7 (1888), 140. *Mineral Ind., 1 (1892); 9 (1900); 18 (1904); 21 (1912); 38 (1919); Thorpe’s “Dictionary of Applied Chemistry,” 5 (1913), 287. 8 Eng. Mining J . , 112 (1921). 138.
It is true that scientific methods of production and conservation have been to some extent introduced into the Sicilian sulfur industry, but the cost of mining the deposits is of necessity rather heavy. The ore, containing only 10 to 20 per cent of sulfur, must all be transported to the surface before the sulfur can be recovered, The resultingproduct contains 2 to 11 per cent of impurities, and for most purposes must be further refined by distillation. To-day this sulfur must compete with the American product which, by one process, is brought to the surface nearly 100 per cent pure and which is handled a t the mines, transported to the seaboard and loaded on ships entirely by mechanical means. The plain fact seems to be that no large quantity of Italian sulfur can be mined and sold to-day in free competition with the American product, even in Europe, except at a loss. DAVIS THEPRESENT America now dominates the world’s sulfur industry. She owes the position primarily to the daring genius of Hermann Frasch, who originated and developed the method of mining which made available the vast supplies of sulfur existing in the so-called “salt domes” of the Gulf coastal plain. I n the Frasch process, the sulfur which exists in great beds about 800 to 1000 ft. below the surface is melted in situ by means of superheated water and then raised to the surface in a molten condition by means of an air lift.4 The basic Frasch patents expired in 1908 and to-day three large and well-financed companies are utilizing his methods for mining. One company is in Louisiana and two are in Texas. I n addition a new company apparently well financed has recently entered the field. All the essential features of the process as it is still used were worked out by Frasch. However, some of the companies have employed the highest 4
THISJOURNAL, 4 (1912), 134, Bacon and Davis, Chem. Met. Eng.,
24 (lQZl),65.
14
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
technical skill in the control of their operations and have effected unexpected economies in the consumption of fuel which constitutes the main operation cost. The Texas Gulf Sulfur Company maintains a large-sized model of its deposit in which all the mining operations are carefully checked so that its engineers are able constantly to visualize what is taking place underground. Those who uphold the principle of the conservation of natural resources may feel assured that little of the sulfur in these vast deposits will be lost t o industry. It was mentioned above that crude Sicilian sulfur contains a large percentage of impurities. The American sulfur mined by the Frasch process has a degree of purity that is extraordinary. Think of sulfur being pumped out of the ground over 99 per cent pure at the rate of over 500 tons a day from one well. Furthermore, average well samples taken over considerable periods have, when freed from moisture, analyzed over 99.9 per cent pure. The sulfur, however, almost invariably contains traces of petroleum oil, and this gives rise to effects which occasionally lead the consumer to believe that the sulfur is fairly impure. This oil is dissolved in the sulfur to form a true solution and is not easily removed. Even minute traces have an adverse effect upon the burning properties of the sulfur in an open dish because of the asphaltic film that forms on the surface. However, special methods have been devised which completely overcome any difficulties encountered in burning.
THEFUTURE Estimates vary as t o the amount of sulfur in the domes which are now being mined, but it is reported that in some
Vol. 15, No. 1
cases reliable drill tests have shown over 10 million tons in a single deposit which may be raised by present equipment. It seems likely that more sulfur-bearing domes will yet be discovered. There exist in addition great surface deposits of sulfur in the United States and in other parts of the world. I n some localities transportation costs provide a margin on which these can be successfully worked for a local market even to-day. I n 1920, however, 1,255,000 long tons of sulfur were mined in the United States and of this quantity 99.5 per cent was produced in Texas and Louisiana.6 It would require a rather substantial rise in the price of fuel to put the margin of profit again in favor of the exploitation of surface deposits, so that it seems likely that the supply of sulfur for America, if not for the world, will be drawn from the Gulf Coast domes for the next ten years and probably longer. NEWUSESFOR SULFUR Unquestionably, the use of sulfur for purposes old and new will steadily increase. Those properties which suggest certain possible uses for sulfur in large quantities are its exceptional insulating qualities, its resistance to being wetted by water, and its inertness toward most acids, all combined with a fair degree of physical strength. Engineers are naturally and properly conservative about the introduction of new materials into construction work. Still, sulfur is about as easily handled as asphalt, so that when concrete and other materials fail, they will do well to keep in mind this old familiar substance which is now so readily available. 8Chem Age ( N . Y.),SO (1922), 231.
Problems in the Determination of Physical Properties I n preparing for publication the data on physical properties of chemical substances, the editorial staff of International Critical Tables, 1701 Massachusetts Ave., N. W., Washington, D. C., will find from time to time that important physical properties of substances of technical and scientific importance are missing from the literature. As fast as they become aware of missing data of this character, it is their policy to formulate research problems covering such missing data and to endeavor to interest chemists and physicists in undertaking the necessary investigations to supply the required data. Most of the research problems formulated in this way will be suitable for bachelors’ or masters’ theses and in a few instances topics sufficiently broad to be suitable for doctors’ theses will also be available. Many of them will be suitable for, experimental problems in the ordinary laboratory courses in physical chemistry and physics. Thus, for example, the laboratory experiment covering the determination of solubility might to advantage deal with substances whose solubility is needed but is unknown. The average of the determinations made by a class, of students, while not as accurate and reliable as the determinations made by a skilled investigator, will nevertheless be very valuable when they constitute the only data available on the subject. Moreover, the average student will be more interested in laboratory experiment, the results of which are of actual value and worthy of publication, than he would be in repeating for the nth time the measurement of a property of some system which has been measured many times be€ore. International Critical Tables will be glad to submit to interested, instructors in universities and colleges lists of character and to advise as far as it can concer
paratus and methods of measurement. It may be possible also in some instances to secure moderate financial assistance to aid in the purchase of materials and apparatus for investigators interested in carrying out work of this character. The results of such work may be published by the investigator in any appropriate publication medium, and they should also be reported in duplicate to the office of International Critical Tables on completion of the work. A number of problems on the following subjects are available a t the present date: Heats of combination: solid oxides, iron compounds. Specific heats: brass, solid oxides, steels, oils and fats, petroleum products, metals, salts, iron compounds, asphalts. Latent heats of fusion: brass, metals. Heat conductivity: steels. Latent heats of vaporization: petroleum products. . Viscosities: industrial materials, solutions. Kinetics: rates of drying, hydrolysis of industrial materials, catalysis, transpiration of mdisture, biochemical. Strength: industrial materials. Thermal expansion: steels, iron compounds. Freezing-point-solubility diagrams: salts, acids, metals in water, soaps. Boiling points: solutions. Solubility of gases: in molten metals, in water. Chemical equilibrium: dissociation pressures at lf3OO0 C. Electrical conductivity: metals, refractories, Properties of colloidal systems: industrial materials. Vapor pressures: metals, solutiods. Specific rotary power: gliadin. Index of refraction: solids. Density: certain organic compounds, solutions. Plash points. Surface tensions: solutions.
