Need Vi to 44 Microns? Sturtevant Micronizers* Make 325 Mesh Obsolete
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Flow diagram of Sturtevant desifned ffltcromzing system using cominEssed air. Steam also may be used
One Operation Reduces, Classifies Sturtevant Micronizers grind and classify in one operation in a single chamber—provide fines in range from Vi to 44 microns to meet today's increased product fineness needs. Can handle heat-sensitive materials. Production Model (15 in. chamber) No A t t r i t i o n a l H e a t Particles in high speed rotation, propelled by compressed air entering shallow chamber at angles to periphery, grind each other by violent impact. Design gives instant accessibility, easy cleaning. N o moving parts.
Classifying is Simultaneous Centrifugal force keeps oversize material in grinding zone, cyclone action in central section of chamber classifies and collects fines for bagging. Rate of feed and pressure control particle size.
Eight Models Available Grinding chambers range from 2 in. diameter laboratory size {]/± to 1 lb. per hr. capacity) to large 36 in. diameter production size (500 to 4000 lbs. per hr. capacity). For full description, request Bulletin N o . 091.
Engineered for Special Needs A 30 in. Sturtevant Micronizer is reducing titanium dioxide to under 1 micron at feed rate of 2250 lbs. per hr. For another firm, a 24 in. model grinds 50% DDT to 3.5 average microns at a solid feed rate of 1200-1400 lbs. per hr. A pharmaceutical house uses an 8 in. model to produce procaine-penicillin fines in the 5 to 20 micron range. Iron oxide pigment is being reduced by a 30 in. Micronizer to 2 to 3 average microns. Sturtevant will help you plan a FluidJet system for your ultra-fine grinding and classifying requirements. Write today. C a n Test or C o n t r a c t M i c r o n i z i n g Help You? Test micronizing of your o w n material, or production micronizing on contract basis, are part of Sturtevant service. See for yourself the improvement ultra-fine grinding can contribute to your product. Write for full details. STURTEVANT MILL CO., 1 0 5 Clayton St., Boston, Mass. "REGISTERED TRADEMARK O F STURTEVANT M I L L
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Gold is recovered in these ion exchange columns tactors contains a n u m b e r of disks on a c o m m o n horizontal shaft. R o t a t i o n of the disks m a i n t a i n s solids in suspension on the p u l p occupying the lower third of the contactor, a n d the disks carry a film of p u l p t h r o u g h the u p p e r solvent layer, effecting transfer of the solute. Following this continuous c o u n t e r c u r r e n t solvent extraction, u r a n i u m is stripped from the loaded solvent by contact with a solution of sodium c a r b o n a t e in internal mixer-settlers. Solvent is contacted with sulfuric acid for regeneration a n d recycled to the rotary film contactor. Thar's Gold in Them Thar Pills A l t h o u g h gold producers h a v e not been overly loquacious on the sub-
ject, it is generally understood t h a t between 1 a n d 2 % of the gold at extraction plants is r e t u r n e d to t h e earth in effluent streams. [I/EC 49, N o . 1, 1 ( J a n u a r y 1957)]. N C L knows how to keep it in the family. Using spheres of polystyrene cross-linked with divinylbenzene, they are able to c o n c e n t r a t e this waste on the a m i n e form of t h e ion exchange spheres. T h e capacity a n d stability of these pills is great for g o l d — b u t so is their affinity for gold. Biggest p r o b l e m to d a t e is in eluting the gold from the resins with aqueous solutions. N C L is trying to solve this problem by using n o n a q u e o u s elutants. Results of tests u n d e r w a y in the U n i o n of South Africa h a v e already confirmed their l a b o r a t o r y promise. J.B.P.
See-Through Potting Compounds Novel silicone systems cure into colorless, transparent products, self-supporting but flexible I HERE'S A new look in potting comp o u n d s . A n d the visibility's excellent. Both G e n e r a l Electric's Silicone Products D e p a r t m e n t a n d D o w C o r n i n g C o r p . h a v e b r o u g h t out colorless, t r a n s p a r e n t , dielectric silicone materials developed chiefly to protect electronic p a r t s a n d assemblies against t h e r m a l a n d m e chanical shock. Both cure at low
t e m p e r a t u r e s to form flexible, resilient, self-supporting solids which w o n ' t flow as clear potting gels d o . Units potted with these new comp o u n d s d o n ' t have to be contained, c a n be removed from mold alter curing, a n d will retain their shape. A principal a d v a n t a g e foreseen for (Continued on page 39 A)
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