The CHEMIST at WORK ROY I. GRADY AND JOHN W. CHITTUM The College of Wooster, Wooster, Ohio
XXVIII. THE CHEMIST I N THE MANUFACTURE OF ACIDS H. M. COSTER
Mr. Coster is Superintadent of Acid Plants, U . S. previous nitration of cotton. This phase of the process Naval Powder Factory at Indian Head, Maryland. His has raised a problem which will he mentioned later. description of the work involved is followed by a brief bioAs indicated above, the superintending of the operagraphical outline, giving something of his experience and tion of the plants constitutes about eighty-five per cent. training. of the work of the writer. This work is largely of a The work of the Superintendent.of Acid Plants hac been routine nature and includes checking of plant performoutlined quite formally as follows: ance, layout of maintenance and repair work, purchasing of raw materials and repair parts, supervision and Superintends operation of seventy-ton contad coordination of personnel, development of plant policy Sulfuric Acid Plant and thirty-$ve ton Nitric and plant efficiency. Acid Plant.. . . . . . . . . . . . . . . . . . . . . . . . . . . 85% The preparation of accounts and reports can be diSupemises preparation of production accounts vided into: daily record of plant performance, raw and reports.. . . . . . . . . . . . . . . . . . . . . . . . . . . 5% materials used, acid mixed and shipped, monthly inSupemises experimental and research work in ventory of stock, of acid produced and plant yield, plant process and control methods.. ........ 10% monthly report to Powder. Expert of all plant data Total 100%
+ + + + + +
from which unit cost of production is calculated. Perhaps i t is the last phase of the work (experimental and research work in process and control methods) which adds zest to the other duties of routine nature. One or two examples will suffice to illustrate this phase. Previous to 1928 it was necessary to make frequent analyses of the oleum product in order to properly control the concentration. These analyses were costly and hazardous, for oleum is a dangerous product to handle, and even then they were notalways accurate, due to the opportunity for loss. in sampling. Therefore i t was desirable to find, or develop, a method of analysis which avoided all (or most) of the difficulties in the older scheme. The successful solution of this problem has been described before1 but will be outlined here. Earlier work had established the feasibility of determining the concentrations of sulfuric acid samples by measuring the electrical resistance of the solutions, provided that the concentrations fell between ninety-six and ninety-nine per cent. Therefore it seemed advisable to study the resistance of oleum (acid above one hundred per cent.) in the hope of using the information in the analysis of the samples from this plant. Accordingly, samples of different concentrations were obtained and their electrical resistance measured. When all of the data (both old and new) were plotted it was obvious that, while the resistance would not serve for analysis between ninety-nine and one hundred two per cent., the variation in the region of the one hundred seven-one hundred twelve per cent. was very satisfactory for such purpose. Since the oleum samples
In this U. S. Naval Powder Factory both sulfuric and nitric acids are produced for use in the manufacture of smokeless powder and other explosives. The Sulfuric Acid Plant was built in 1918 and has been in almost constant operation since that time. The process uses the contact method in which the essential steps are as follows: 1. Conversion of sulfur into sulfur dioxide. 2. Oxidation of the sulfur dioxide by means of air (oxygen) in the presence of a catalyst. The product is sulfur trioxide. 3. Absorption of sulfur trioxide in sulfuric acid to produce fuming acid (oleum). Automatic diiution to maintain correct water balance. In this plant sulfur dioxide is obtained by burning free sulfur as the raw material. The catalyst used in the second step is platinum on magnesium sulfate. The product is fuming acid (oleum) of a strength which may be expressed as one hundred eleven per cent. (one hundred per cent. H2S04)or 90.61 per cent. total sulfur trioxide. The Nitric Acid Plant now in operation uses the old process of sodium nitrate and sulfuric acid, but this will he replaced within the next fiscal year by a new and modern ammonia oxidization unit. The acid produced from sodium nitrate must be distilled before it can be used in the manufacture of smokeless powder. Furthermore, it is desirable to have the product quite concentrated so that i t can be used in building UD or fortifying other acid which has been weakened ?spent) during 174
COSTER, Ind.Eng. C h . .23,563 (1931).
requiring analysis in this plant have concentrations in this latter range the applicability of the method was established. As a result a resistance indicator was permanently mounted in each acid tank. Further refinements make the work practically free from any error due to temperature fluctuations. A slight extension of the method makes i t possible to determine the temperature of the acid without the use of long stem mercury thermometers. "By the new method the acid temperature and the strength are read in one operation. In addition, should a continuous record of the changes in acid strengths ever possess any practical value, a recorder can he easily adapted to this system. "The increased safety to the men in handling so dangerous a product as oleum, as well as the saving in the cost of analysis, is important. But these advan-
on the time elapsed during the process, was quite inefficient, resulting in a loss of strong acid and causing more material to be redistilled a t an added and unnecessary expense. The utility of the electrical resistance process for analyzing oleum (as outlined above) suggested the prospect of developing a similar one for analyzing the nitric acid. In the investigation which followed, various samples of nitric acid were examined. Some samples contained oxides of nitrogen whose influenceon both acidity and resistance was determined. When the
S I T R I CAND
SULEURIC ACIDPIANTS, NAVAL POWDER FACTORY, INDIAN H ~ A DMARYLAND ,
data were collected and examined it was found that an electrical resistance recorder, similar to that previously installed in the sulfuric acid tanks, would indicate the concentration of nitric acid (when it fell between certain limits) with greater speed, ease, and accuracy than any other known method and would indicate the exact moment when the distillation cuts should be made.
Mr. Coster was asked about the qualifications for a chemist in the work he is doing. He replied with the following biographical outline: "With a degree in chemistry, a few months' experitages are slight as compared with the value to the absorption system, for it is only necessary to press a hut- ence as an instructor in chemistry, and one and one-half ton and read with ease and accuracy the changes which years' experience in the laboratory of the Pennsylvania so vitally influence the absorption of sulfur tri~xide."~Railroad in Altoona, Pennsylvania, I passed the exIn the Nitric Acid Plant, as mentioned above, the amination for Third Class Chemist a t the U. S. Naval nitric acid concentration must not fall below a certain Powder Factory, Indian Head, Maryland, and was prescribed minimum. From any one charge of sodium given that position. At that time these examinations nitrate only about three-fourths of the nitric acid first and appointments were a direct function of a special distilled is sufficiently strong to meet the standard. hoard a t the Navy Yard, while today they belong The rest requires further concentration before it, too, entirely to the U. S. Civil Service Commission. "The work assigned was not difficult, involving only can be used. "In order to effect a separation of the strong and weak, a cut is made during the run which the analyses of raw materials used in acid and smokeless diverts the weak fraction into a different tank from that powder manufacture and the final products-acids, receiving the strong. Obviously, i t is important that nitrocellulose and smokeless powder. Occasionally, this cut be made a t such a time as will secure the maxi- other explosives and miscellaneous materials were inmum yield of strong acid."$ The old practice, based cluded. Having a major in agricultural chemistry and experience in analyses of railroad materials, it was ' cosrsn, loc. c d . necessary for me to readjust myself to fit the new work a COSTER, Ind.Eng. Chen.,25,980 (1933).
on explosives. The work could not be classified as dangerous or difficult. Visits to the Powder Factory taught the process and developed understanding in analysis. "In about three years, a vacancy in a Second Class position permitted promotion. I n this new position, much of the routine work was absent, and, in its place, more special tests and experiments on old and new explosives were conducted. Various other incidental tests added to the already interesting work. The work was not particularly difficult or dangerous, and capable supervision assumed much of the responsibility. "In the course of about another three years, a vacancy in the First Class again permitted promotion. In this position, experiments and research required most of the time. Translations from the French and German added scope and interest to the work: I was thrown on my own responsibility and resources and given a chance to investigate. The work was not particularly dangerous, but required caution; it was deeply interesting. Capable heads again were always available for the more difficult problems.
"Time was taken out to spend a year in the study of the manufacture of sulfuric and nitric acids under a very capable Superintendent of Acid Plants. "The war time expansion reduced the time for research work and permitted my duties to include the Pyro line (Smokeless Powder Factory) supervision, and also the supervision of all tests of explosives purchased by the Navy as well as all tests on secret war materials collected by the Intelligence Board. "Again a vacancy in the position of Superintendent of Acid Plants permitted promotion and ended the nine years' experience in the Chemical Department. I n the new position, the experience in the laboratory, the knowledge of the Smokeless Powder Factory and high explosive plants, also the year's experience in the Acid Plants, supplied the background for the position. "Obviously, more engineering experience would have better rounded out ideal qualifications. However, with an excellent corps of plant operators and practical men and a little hard digging and long hours, this, too, was mastered sufficiently to enable us to continue satisfactory production without interruption."
