TRENDS
has been greatly aided by the development in recent years of thermal analysis techniques, and the acronyms T G A (thermogravimetric analysis) and D T A (dayerential thermal analysis) have become well known outside the circle of analytical chemists. Now a new thermal analysis technique, thermohygrometric analysis-conveniently abbreviated to THA-has been proposed by J . E. Still and R. C. Chirnside of England’s General Electric Co. Ltd. (no relation to the U. S. company of the same name). While TGA involves monitoring the change in weight of a heated sample and D T A follows its temperature change, T H A determines how much water is evolved from the sample. A n inert gas stream sweeps over the heated sample, carrying any water that is given off to an electrolytic hygrometer cell. A s in the other thermal analysis techniques, heating can be programmed-i.e., rates of heat input or of temperature rise can be preset. T H A promises to be useful in the study of temperature-dependent reaction phenomena in which water is etiolced, and in the “j’ingerprinting” of minerals [Nature, 219, 200 (7968)1. Characterization of materials
Attrition of particles in slurry transport systems as
often aproblem when the size of the Individual particles in the slurry as requzred to be wathzn a narrowly dejned range. However, since so litle i s known about the mechanzcal strength of dzflerent types of particulate materzals, predzctaon of the extent of attritzon to be expected an papelznes as a daflcult matter. Full-scale tests are necessarzly expensite, so I . S. Bjorklund and J . C. Dygert of Shell Deuelopmnt Co. have made an attempt to $redact attrztion an slurry systems by using two sample small-scale tests [A.I.Ch.E. J., 14, 553 (1968) 1. In the j’irst, the partacles are mechanacally crushed; however, the physical dasszmalarity between the test and the pow of a slurry makes it only qualatatzvely useful. In the second test, the actual slurry zs held zn the annular space between aJixed outer cylznder and a rotatzng inner one-thas method as expected to yzeld quite accurate predzctions of attrataon. Advances in our knowledge of particle strength are reviewed yearly by R. H . Snow zn the I B E C Annual Review of Szze Reductaon; the next such review wall appear in our Notember 1968 zssue. to scientists and engineers may be due as much to the thought patterns it induces in those who study it as to the actual “concrete” content of mathematics courses. This belief, stated by D. R. Weidman of the U. S.Naval Weapons Laboratory in Science, 161, 314 (1968),was intended by him to rebut some of the arguments put forward in the results of The hTational Study of Mathematics Requirements for Scientists and Engineers [Science, 160, 742 ( 1967) ]. Whereas this study concluded that the major value of mathematics to the nonmathematician lies in the provision of practical tools f o r problem solving-methods for solving sets of simultaneous equations, for example- Weidman feels that the habits of thought, ways of approaching problems, and attitudes inculcated by a study of math are at least as valuable. For the same reason, he also rejects the notion that mathematics ispractically useless to those studying such seemingly nonmathematical subjects as zoology and theoretical organic chemistry. The value of mathematics
was highlighted in a review appearing on p 12 of our August issue. There, D. R. Buss and T . Vermeulen outlined the daficulties inherent in the separation of mirror-image forms of a compound and suggested efective but, nevertheless, expensive resolution methods. This expense is often so high that there is a real incentive to j n d cheaper ways to prepare pure optical isomers. For example, The separation of optical isomers
4
INDUSTRIAL AND ENGINEERING CHEMISTRY
the isomer L-aspartic acid commands $lOO/kg in the marketplace; it is usually prepared from fumaric acid and ammonia by the enzymatic action of microbes. However, another enzymatic method that is potentially cheaper has been discovered and patented by Y. Takamura and his associates in Japan [U. S. Patent 3,391,0591. A mixture of maleic and malonic acids is used as a nutrient in which one of a large number of naturally occurring microbes is cultivated. This produces an enzyme capable of converting maleic acid to L-aspartic acid (in the presence of ammonia or of an ammonium salt). The low cost and availability in large quantities of maleic acid are the principal reasons for optimistic hopes for large-scale production of L-aspartic acid along these lines. Stainless steel with a high chromium content is produced by a new, simpl;f;ed manufacturing process just developed by the Union Carbide Corporation. I n conventional practice, the excess carbon is removed from the scrap steel charge by lancing with pure oxygen. The disadvantage of this method is that it is not possible to produce a melt since, as the carbon level drops containing the required amount of chromium (- l8yO) to the desired 0.0270, chromium, too, is oxidized and enters the slag layer above the melt. The success of the Carbide process hinges on the fact that the oxidation of carbon can be favored over the oxidation of chromium by reducing the partial pressure of carbon monoxide in the r$ning chamber. This is achieved by introducing into the melt argon as well as oxygen-the argon serves to reduce CO partial pressure from 1 atm down to 0.1 atm and thus enables a high proportion of the chromium charged to remain in the melt. The economic advantage of the new process lies in the fact that it is not necessary to make up the chromium deJiciency with low-carbon FeCr, an extremely expensive ingredient.
TUYCRE5 rOK A R W W AUD OXYO€l7
today are, as expressed in a review of chemical engineering in the U.S.S.R., strikingly similar to those being faced in Free- World countries. Although much of what P. G. Romankov and M . I. Kurochkina have to say in J . Appl. Chem. USSR, 40, 2091 ( 1 9 6 8 ) is so imbued with the spirit of the 50th anniversary of the Russian revolution as to allow digestion only when accompanied by a hefty pinch of (presumably Siberian) salt, their list of goals f o r the future will strike a responsive chord in Western ears: ( 1 ) establish the kinetic relationships of the principal technological processes; ( 2 ) create scient@ methods f o r standard design calculations; and (3) establish economic principles for the operation of chemical equipment. Kipling’s remark about East and West neuer meeting seems to have been a rather inaccurate piece of technological forecasting. The tasks facing chemical engineering science
Synthetic organic chemistry as practiced on the commercial plant scale and the same subject as studied by the basic researcher represent two distinct points of view, says T. Shiba in Intern. Chem. Eng., 8, 556 (1968). For the researcher, it is the chemical details of the conversion of substance A to substance B and the selection of an active and selective catalyst that are most fascinating. A t the commercial scale, on the other hand, economic factors dictate-the orders are, simply, to make substance B economically. No one even cares whether A is the starting material, so long as the amount of catalyst is small, the equipment and its operation are simple, and by-products are either produced in small amount or are easily sold. Considering the dafference between these two points of view, it isn’t really too surprising that the road from basic research to commercial process is such a notoriously rocky one. VOL. 6 0
NO, 9 S E P T E M B E R 1 9 6 8
5
