I/EC REPORTS
This residential street in Bryan, Tex., is being paved with an asphalt mix which uses Rockdale slag and limestone screenings as the a g g r e g a t e
slag and fly ash, both of which can be used in the construction field. There are two kinds of fly ash, at Rockdale these are called Rockdale fly ash (fines) and Rockdale coarse fly ash. Both are collected dry and are never wasted to the atmosphere. Slag (molten ash) moves from the combustion chamber through a port and flows into a vat of water, where it is shattered by thermal shock. This shattered slag is transported hydraulically to the "ash lake" or "tailing pond." Fly ash which has been collected dry also goes to the pond in a water slurry. The mixture of slag and fly ash in the pond is called Rockdale slag aggregate (RSA). Slag alone is known as Rockdale slag (RS). T T I finds that Rockdale slag aggregate works well in bituminous mixes. Rockdale slag alone has the black luster of obsidian (a volcanic glass rock) but RSA does not have this luster, because it has a fly ash film. Still this doesn't hurt RSA as an aggregate material. The aggregate which T T I uses is 7 5 % RSA and 2 5 % limestone screenings. Bob M. Gallaway, T T I research engineer, explains that limestone screenings (LSS) improve the mix's strength and density. Nonskid properties are also increased, since the two materials have different wear rates. In June 1958, T T I laid down two test sections. The mix was made up of the 7 5 % RSA-25% LSS aggregate with 6 to 7% asphalt cement. One test section is on 38 A
a highway just south of College Station and the other is part of a residential street in nearby Bryan. There was no difficulty in paving operations. The mix was laid down at 275° to 300 °F., which is slightlyabove normal for lay-down temperatures. But it carried a 10-ton breakdown roller as well as a finish roller without a noticeable front "wave." Nor are there noticeable joints in adjoining lanes. T T I is more than pleased with the results so far. The highway test section has had heavy truck traffic and shows no signs of pavement "shoving" or "raveling." The pavements have survived a hot, wet
INDUSTRIAL AND ENGINEERING CHEMISTRY
Still More Possible Uses for Lignite Waste By-Products
summer and a hard winter. Still they have kept their brilliant, black texture, nonskid properties, and quietness. Gallaway feels that Rockdale slag aggregate has proved itself as a paving material and others apparently agree. It is now being considered in Waco, Tex., and College Station has let a contract which permits its use on city streets. Some northern and eastern cities are also using a similar material produced in the area. T T I is investigating other possible uses for lignite waste byproducts. Fly ash may be used as an extender for portland cement, and RSA looks promising as a base course material when mixed with small amounts of clay and lime. If these and other potential uses become a reality, Alcoa will find itself, not with a useless by-product, but with a valuable building material on its hands. This will also please TPL, because it acts as marketing agent for Alcoa's Rockdale slag. E.V.A.
The Anatomy of an Aerosol W h e n hair spray ingredient becomes cancer suspect, Department of Agriculture chemists work out aerosol-analysis technique to give hair sprays clean
bill of health * Sand blasting or peening operations * Abrasives * Nonskid treads for stairs, ramps, and bridges * Asphalt shingle over aggregate * Slurry seals for city streets
r \ few months back, two doctors reported at a meeting in St. Louis that poly(vinylpyrrolidone) (PVP) was suspected of being a causative factor in causing certain cancer growths. The report caused a mild furor among cosmetics manufacturers—PVP is used in many of the aerosol hair sprays now on the market. The Food and Drug Administration was called in on the case and they in turn called in chemists from the Pesticide Chemicals Re-
Pilot Plant or Laboratory
Equipment
. ..
Ε Ε Ξ
REPORTS
for DRYING SINGLE-SHELL DRYER
r
TÎ
Single-shell, direct gas fired rotary dryer. Arranged for either parallel or counter-flow operation. Mounted on structural steel base. Has removable "knockers." Bulletin AH-471.
DOUBLE-SHELL DRYER Double-shell, indirect-heat, gasfired dryer for drying without contamination. Volatiles removed with only limited dilution. Shell rotation speed and shell slope easily changed. Bulletin AH-472.
Photograph shows hair spray coming out o f can. Velocity of individual particles immediately after emergence from the nozzle is 4 5 0 0 f e e t per second. The white fragments a r e the individual aerosol particles
STEAM TUBE DRYER Steam-tube indirect heat dryer. Can be connected to any available steam supply or furnished with a 3-HP steam generator. Available in stainless steel or other corrosion-resistant materials. Easily moved from place to place. Bulletin AH-473.
for G R I N D I N G A N D
CLASSIFYING
DRY GRINDING UNIT Make power connections only and the Hardinge Dry Grinding Unit is ready to perform. Selfcontained and portable, 7' 8" high. Complete with ConstantWeight Feeder, Conical Mill, "Gyrotor" Classifier, dust collector, product collector and "Electric Ear" grinding control. Bulletin AH-448.
WET GRINDING UNIT Power and water connections only are needed to put the Hardinge wet grinding unit into operation. Self - contained and portable, 6V2' high. Includes Conical Mill, Counter-Current Classifier, launders, feeder, pump and "Electric Ear" grinding control. Bulletin AH-448.
DINGE
HAB
I N C O R P O R A T E D
C O M P A N Y , YORK, PENNSYLVANIA
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2 4 0 ARCH ST.
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M a i n Office a n d Works
New York · Toronto · Chicago · Hibbing · Houston · Salt Lake City · San Francisco · Birmingham · Jacksonville Beach Circle Nos. 30-1, 30-2, 30-3, 30-4, 30-5 on Readers' Service Card 40 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
search l a b o r a t o r y at the U S D A ' s Agricultural Research Center, Beltsville, M d . T h e chemists, led by D r . R o b e r t A. Fulton, decided o n a practical a p p r o a c h to the problem. A "hair spray c h a m b e r " was constructed, complete with a lady's vanity a n d mirror. T h e n a n air exhaust system was installed a n d a n electrostatic sampler hooked u p to precipitate the particles in the exhaust air. N o w the c h a m b e r was ready for o c c u p a n c y . Pretty secretaries were called into the lab, a r m e d w i t h a commercial hair spray a n d instructed to spray a net on their hair in accordance with the directions on the can. Also, to simu late possible actual use conditions, the girls were told to purposely " m i s s " the head d u r i n g several applications. T h e results of this experiment were interesting. W h e n the precipitated particles collected by the sampler were analyzed, it was found t h a t w h e n the spray was directed a t her hair, there was a m o m e n t a r y "splash i n g " effect a n d the girl b r e a t h e d mostly P V P . But when she missed her h e a d , she breathed P V P plus alcohol, the P V P solvent. More i m p o r t a n t , however, the a m o u n t of
A Typical Hair Spray Formulation % Poly(vinylpyrrolidone) (PVP) Plasticizer Alcohol, anhydrous Freon
1-4
0.2-0.5 20-30 65-75
REPORTS
BBS
PVP collected from the air immediately after spraying was so small that Food and Drug Administration ruled that it could not possibly be a factor in producing cancer. While the work done by Dr. Fulton and his associates at Beltsville was of direct assistance to the manufacturers of aerosol hair sprays, it will be of value indirectly to manyother manufacturers of commercial aerosol products. For instance, makers of aerosol paint sprays are interested in the splash phenomenon— how much of the pigment sticks to the surface being painted, and how much bounces off? Studies of the velocities of the particles coming from the hair spray aerosol (over 3000 miles per hour!) and particle size will be useful in developing formulations that will give the consumer more spray product for his money. M.A.K.
r
/ J
Pure Chromium Oxides and
Hydrated Chromium Oxides
Cool, Man! Solar furnace proposed as cool light source for photochemical reactions
Most stable of the green pigments. Unaffected by acids, alkalis, vehicles, and solvents. Non-fading. The 4 pure chromium oxides will withstand ceramic
jfA
SOLAR
FURNACE can
be
an
ef-
ficient source of cool light for photochemical reactions. At first glance this may seem to be a paradoxical statement, since a solar furnace is usually thought of as a heat source. However, Rudolph J. Marcus and Henry C. Wohlers of Stanford Research Institute point out that such a furnace can equally well be considered as a light concentrator. T h e radiation concentrated by the furnace covers the whole range of the solar spectrum received at the earth's surface; the shorter wave lengths within this range (0.3 to 0.7 micron) are in the ultraviolet and visible part of the spectrum. T h e SRI group (working under an Air Force Cambridge Research Center Contract) has confirmed this speculation by using the institute's solar furnace as a light source for the photoreduction of eerie ion (a reaction which has been intensively studied by Heidt of M I T ) : Ce- +
l/2H,Og^Ce
+
3
H
temperatures. Use them in applications requiring permanency—enamels, emulsion paints, rubber, plastics, floor coverings, roofing granules, building materials, etc. Use the 2 hydrated chromium oxides for obtaining brilliant color and transparency in automotive finishes, high grade enamels and lacquers. Your nearest Williams representative will be glad to provide you with full technical data and samples, or write Dept. 2, C. K. Williams & Co., Easton, Penna.
WILLIAMS COLOR & PIGMENTS EASTON, PA.
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E. ST. LOUIS, ILL.
EMERYVILLE, CAL.
+
+
+ 1/4 0 :
Circle No. 55 on Readers' Service Card
VOL. 51, NO. 7
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JULY 1959
41 A
