Remote Mixing and Handling Procedures for Pyrotechnic Materials

Chapter 9

Remote Mixing and Handling Procedures for Pyrotechnic Materials 1

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Thomas E. Shook , Loy M. Aikman , Max Frauenthal , David Garcia , Joe G. Janski , and F. L. McIntyre 2

Downloaded by UNIV OF NEW SOUTH WALES on January 11, 2018 | http://pubs.acs.org Publication Date: July 20, 1987 | doi: 10.1021/bk-1987-0345.ch009

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Pine Bluff Arsenal, Pine Bluff, AR 71602-9500 NASA National Space Technology Laboratories (NSTL), Sverdrup Technology Inc., Technical Services Laboratory, NSTL Station, MS 39529 Proper safety testing and classification of pyrotechnic energetic capacity will allow the selection of modern remote equipment for the manufacture of pyrotechnic material in a safe and economical manner. Examples are provided for new remote mixing/handling equipment certified to handle pyrotechnic mixtures at a Department of Defense facility located at Pine Bluff Arsenal (PBA), Arkansas. Safety testing is described along with a suggested rationale for improving productivity, safety, and manufacturing costs.

P y r o t e c h n i c m a t e r i a l s a r e r e p o r t e d t o have t a k e n many l i v e s s i n c e the b e g i n n i n g o f r e c o r d e d h i s t o r y , e s p e c i a l l y where s c a l e up from s m a l l b a t c h e s has o c c u r r e d . In r e c e n t times s e v e r a l works have appeared (1,2) w h i c h have p r o v i d e d a n adeauate d e s c r i p t i o n o f t h e chemistry of pyrotechnics. The f o r m u l a t o r , h a v i n g b o t h inadeauate p r o c e s s equipment and lack f o r a r a t i o n a l l a b o r a t o r y t e s t and c l a s s i f i c a t i o n s y s t e m o f e n e r g e t i c c a p a c i t y , has been f o r c e d t o handle pyrotechnic m a t e r i a l s i n small batches. This r e q u i r e d personnel u s i n g equipment d e s i g n e d i n t h e 1940's and 1950's t o p e r f o r m t h e labor i n t e n s i v e f u n c t i o n s o f w e i g h i n g , g r i n d i n g , m i x i n g , f e e d i n g and compaction i n c l o s e p r o x i m i t y t o hazardous m a t e r i a l s that r e s u l t e d in a high degree of r i s k . In t h e p a s t t e n y e a r s t h e chemical i n d u s t r y , p r i m a r i l y p h a r m a c e u t i c a l s , has demanded more e f f i c i e n t and s a f e r methods f o r m i x i n g and g r a n u l a t i n g o f s o l i d systems t o c a r r y v a r i o u s doses o f drugs in w e l l mixed blends. The r e s u l t was t h a t t h e p y r o t e c h n i c i n d u s t r y c o u l d o b t a i n and m o d i f y ccrrmercial J e t A i r M i x e r s , F l u i d i z e d Bed m i x e r s / D r i e r s ( G l a t t ) , and MIGRAD (Mixer-Granulator-Dryer) mixers along with a i r transport of s o l i d s from weigh f e e d e r s t o t h e p r o c e s s m i x e r s . Modern f i l l and p r e s s equipment were a l s o d e v e l o p e d w h i c h r e s u l t e d i n remote systems f o r the e n t i r e m a n u f a c t u r i n g p r o c e s s t h a t was f r e e from c l o s e p r o x i m i t y t o t h e o p e r a t o r and p r o v i d e d a s i g n i f i c a n t r e d u c t i o n i n p e r s o n n e l . To t a k e advantage o f t h i s p r o c e s s equipment f o r p y r o t e c h n i c s and expand p r o d u c t i o n t o l a r g e volume remote systems has r e q u i r e d t h e This chapter not subject to US. copyright Published 1987 American Chemical Society

Scott and Doemeny; Design Considerations for Toxic Chemical and Explosives Facilities ACS Symposium Series; American Chemical Society: Washington, DC, 1987.


9.

SHOOK ET AL.

Mixing and Handling of Pyrotechnic Materials

development o f a r a t i o n a l c l a s s i f i c a t i o n o f e n e r g e t i c c a p a c i t y t o p r e d i c t the l e v e l s of m a t e r i a l w h i c h may be s a f e l y h a n d l e d . P y r o t e c h n i c s a r e u s u a l l y i n c l u d e d i n the d e f i n i t i o n o f e x p l o s i v e s ( 3 ) . The same q u a n t i t y / d i s t a n c e s v a l u e s a p p l y f o r a d e l a y m i x t u r e as t h e y would f o r equal amounts of TNT ( 4 ) . The e n e r g e t i c s of a p y r o t e c h n i c a r e o f t e n not the same and p r o v i s i o n s f o r p r o p e r i n - p r o c e s s and f i n a l c l a s s i f i c a t i o n s h o u l d be based upon the e n e r g e t i c s of t h e m a t e r i a l . B e n e f i t s g a i n e d from p r o p e r c l a s s i f i c a t i o n o f p y r o m i x t u r e s o t h e r than p o s s i b l e i n c r e a s e d p r o d u c t i v i t y and s a f e t y a r e i n the p l a n n i n g of p y r o t e c h n i c p r o d u c t i o n f a c i l i t i e s s u c h t h a t p r o p e r s e p a r a t i o n o f b u i l d i n g s and equipment may be e n j o y e d w i t h o u t a l a r g e c o s t i n a c r e a g e . E l i m i n a t i o n o f the c o n s t r u c t i o n of e x p e n s i v e b l a s t r e s i s t a n t b u i I d i n g s may a l s o be a v o i d e d . The Department of Defense (DOD) has e s t a b l i s h e d p r o c e d u r e s ( T a b l e I) f o r i n - p r o c e s s S a f e t y Classification.

T a b l e I.

DOD

Safety C l a s s i f i c a t i o n

Tests

SENSITIVITY: PARAMETRIC: C a r d Gap T e s t : A u t o i g n i t i o n Temperature: Detonation Test: D e c o m p o s i t i o n Temperature: E l e c t r i c a l Spark E x p l o s i o n Temperature: Sensitivity: I g n i t i o n and U n c o n f i n e d Apparent B u l k D e n s i t y : Burning: Impact S e n s i t i v i t y : Fuel/Oxidizer Ratio: Friction Sensitivity Gas Volume: ( R o t o - F r i c t i o n Test D e v i c e ) Heat of Combustion: OUTPUT: Heat of R e a c t i o n : Burn Time-. (Cube). P r o p a g a t i o n Index: Burn Time: ("Vee" b l o c k ) P r e s s u r e Time: STABILITY: a) Peak P r e s s u r e Thermal S t a b i I i t y : b) Time t o Peak Vacuum D r y i n g weight l o s s c) Rate of R i s e

A d d i t i o n a l t e s t s t h a t a r e r e a u i r e d i n c l u d e mass e f f e c t s and f u l l s c a l e " w o r s t - c a s e " t e s t s . These a l l o w f o r the assignment o f an i n - p r o c e s s i n t e r i m qualιfication downgrading c l a s s i f i c a t i o n from 1.1 t o 1.3 or 1.4 ( T a b l e I I ) . I n i t i a l l y the p y r o t e c h n i c e n g i n e e r s e l e c t s the equipment of c h o i c e t o meet p r o d u c t i o n r e q u i r e m e n t s r e l a t i v e t o q u a n t i t y o f m a t e r i a l , e a s e o f o p e r a t i o n s , and apparent s a f e t y c o n s i d e r a t i o n s . H i g h l y r e a c t i v e mixtures ( s t a r t e r mixes, f l a r e s e t c . ) a r e u s u a l l y i n c l a s s 1.1 or 1.2, w h i c h l i m i t s the q u a n t i t y t o 100 l b s . L e s s r e a c t i v e m a t e r l a l s l i k e s c r e e n i n g smokes and s i g n a l s may be m i x e d i n l a r g e r q u a n t i t i e s . Mass e f f e c t and d e t o n a t i o n t e s t s a r e not r e q u i r e d i n c l a s s 1.1 and 1.2 s i n c e a s m a l l amount of m a t e r i a l (100 l b s ) e x i s t s i n the system. These t e s t s a r e r e q u i r e d t o g a i n c l a s s i f i c a t i o n as c l a s s 1.3 o r 1.4 and a r e c a r r i e d out on b a t c h s i z e s r a n g i n g from 200 t o 2,000 l b s . These t e s t s i n c l u d e d e t o n a t i o n , d e f l a g r a t i o n , shock, fiame, and e x p l o s i v e


153

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TOXIC CHEMICAL AND

EXPLOSIVES FACILITIES

charge. A p r e s s u r e r e l e a s e ( v e n t i n g ) system and f i r e s u p p r e s s i o n equipment a r e a l s o e v a l u a t e d . C l a s s 1.1 and 1.2 m a t e r i a l s use t e s t s s i m i l a r t o t h o s e r e p o r t e d i n T a b l e I I I and a l s o r e q u i r e v e n t i n g and f i r e s u p p r e s s i o n . The p r o c e s s o f c h o i c e i s made c a r e f u l I y and t h e t e s t s a r e d e s i g n e d t o p r o v e the m e r i t o f the c h o i c e b o t h w i t h l a b o r a t o r y and f i e l d t e s t s .


Table

I I . Four D i v i s i o n s of UNO

Hazard C l a s s and D i v i s i o n D e s i g n a t i o n 1.1 1.2 1.3 1.4

Class 1 (Explosives) Hazard Mass D e t o n a t i n g Non Mass D e t o n a t i n g Mass F i r e Moderate F i r e , No B l a s t

S a f e t y C l a s s i f i c a t i o n f o r P y r o t e c h n i c M a t e r i a l s i n a MIGRAD M i x e r : Test r e s u l t s (5,6) f o r s e v e r a l c a n d i d a t e m a t e r i a I s ( T a b l e I I I ) a r e r e p o r t e d which span t h e range o f e n e r g e t i c c a p a c i t y . Those v a l u e s which exceed t h e t h r e s h o l d a r e h i g h l y s u s o e c t and have been known t o r e s u l t i n s e r i o u s f i r e s i n the p a s t . Mix No. 1, (M49A1, T r i p F l a r e Mixture) i s a "safe" mixture that i s i n s e n s i t i v e to e l e c t r i c a l s p a r k , impact, and f r i c t i o n . I t does not have a f a s t b u r n r a t e on t h e Vee B l o c k t e s t e r and i t has a low p r e s s u r e - r a t e - o f - r i s e . M i x t u r e No. 2, (R2S6 T r a c e r M i x t u r e ) i s f r i c t i o n s e n s i t i v e as i n d i c a t e d by an Eq v a l u e o f 45 compared t o a t h r e s h o l d l e v e l o f 100 minimum. M i x t u r e No. 3, (I548 I g n i t i o n m i x t u r e ) i s b o t h f r i c t i o n and impact s e n s i t i v e w i t h r e a d i n g s o f 66 f t l b /sec and 3.75 i n . r e s p e c t i v e l y . M i x t u r e No. 4, (40 mm i g n i t i o n m i x t u r e ) i s f r i c t i o n , impact, and e l e c t r o s t a t i c s e n s i t i v e (ESS). It burns r a p i d l y i n the Vee B l o c k t e s t e r and has a p r e s s u r e - r a t e - o f - r i s e e x c e e d i n g t h e t h r e s h o l d l e v e l o f 200 p s i maximum. M i x t u r e No. 4 r e q u i r e s more s a f e t y c o n s t r a i n t s i n p r o c e s s i n g than does m i x t u r e No. 1 which has no parameters f a i l i n g the e s t a b l i s h e d t h r e s h o l d l e v e l s . B e f o r e meaningful p r o c e s s i n g c o n s t r a i n t s can be e s t a b l i s h e d f o r a p y r o t e c h n i c c o m p o s i t i o n , a l l s a f e t y c l a s s i f i c a t i o n t e s t s ( T a b l e I) s h o u l d be conducted t o c h a r a c t e r i z e t h e p y r o m i x t u r e .

Table

I I I . Key Parameters f o r S a f e t y E v a l u a t i o n o f MIGRAD M i x e r s

PARAMETER Vee Burn Time-s/crn: ESS-Joules: Roto-Friction-ft.Ib2/S: Impact S e n s i t i v i t y - i n . : Pressure RCR-psi/S:

THRESHOLD PrROMIXTURES LIMITS (1) Γ2) C3) (4) 0.06 (Min) T2.67t0.67t 1.8Π 0.05t 1.0 (Min) ΐ >50t >50t >50ΐ0.107Τ 100 (Min) t 197T 45Î 66T 86T 3.75 t 10ΐ 10Î3.75t 3.75T 200 (Max) t 17t42.3t38.2t265.8t


9. SHOOK ET AL.


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Mixer G r a n u l a t o r D r i e r (MIGRAD1: A s e a r c h was conducted t o i d e n t i f y a corrmercial mixer ( 7 ) t h a t would e n s u r e proper m i x i n g , g r a n u l a t i o n and vacuum d r y i n g o f p y r o t e c h n i c powders and lend i t s e l f t o r e s t r u c t u r i n g / t a i l o r i n g f o r remote accomplishment o f p r o j e c t g o a l s . (See F i g u r e 1) The mixer s e l e c t e d was t h e 30 l i t e r brandy g l a s s shaped "Dry D i s p e r s e r M i x e r / G r a n u l a t o r " made by B a k e r - P e r k i n s Chemical Machinery L t d . , a B r i t i s h f i r m . The mixer has two h y d r a u l i c a l l y d r i v e n i m p e l l e r s . M i x i n g i s a c c o m p l i s h e d by t h e m i x i n g i m p e l l e r l o c a t e d i n t h e bottom of t h e m i x e r , w h i l e g r a n u l a t i o n i s a c h i e v e d by the g r a n u l a t i n g i m p e l l e r , o r chopper, l o c a t e d i n t h e s i d e o f the m i x e r . The h y d r a u l i c motors d r i v e t h e i m p e l l e r s i n i n f i n i t e l y v a r i a b l e speeds from 0-650 RPM ( m i x e r ) and 0-1000 RPM ( c h o p p e r ) . The m i x i n g bowl i s j a c k e t e d t o p e r m i t c o o l i n g o r h e a t i n g and s h o u l d meet ASME C l a s s V I I I , D i v i s i o n I s t a n d a r d s ( i n t e r n a l w o r k i n g p r e s s u r e 170 p s i g ) . The mixer i s e a u i p p e d w i t h a h y d r a u l i c a l l y a c t i v a t e d d i s c h a r g e v a l v e t h a t a l l o w s a u t o m a t i c and remote u n l o a d i n g o f t h e m i x e r . F u r t h e r a d a p t a t i o n o f t h e mixer f o r p y r o t e c h n i c a p p l i c a t i o n s c o n s i s t e d o f a d d i n g a mixer e x t e n s i o n w i t h e n t r y p o r t s f o r a d d i n g d r y raw m a t e r i a l s , l i q u i d b i n d e r s and d e l u g e water. A vent s t a c k was added to vent a o o s s i b l e f i r e . The m i x e r was c l o s e d by the a d d i t i o n o f a 10 p s i r a t e d r u p t u r e d i s c between t h e mixer e x t e n s i o n and vent stack. D r y i n g o f the p y r o t e c h n i c composition i s accomplished by c i r c u l a t i o n o f h o t water through t h e m i x i n g bowl j a c k e t w h i l e p u l I i n g a vacuum on the m i x i n g chamber. Chi I l e d I i q u i d may be c i r c u l a t e d through the m i x i n g bowl j a c k e t t o keep t h e c o n t e n t s c o o l d u r i n g c r i t i c a l phases o f t h e m i x i n g p r o c e s s . A f i r e d e t e c t i o n / s u p p r e s s i o n system was added t o t h e corrmercial equipment t o a c h i e v e t h e f a s t e s t p o s s i b l e response time (10-50 ms) i n t h e event o f a f i r e . The f i r e d e t e c t i o n s e n s o r s c o n s i s t o f i n f r a r e d r a d i a t i o n s e n s o r , p r e s s u r e sensor (8 p s i r a t e d ) and temperature sensor (210nF/99 C r a t e d ) i n s t a l l e d d i r e c t l y i n t h e mixer e x t e n s i o n . U l t r a v i o l e t (UV) r a d i a t i o n s e n s o r s m o n i t o r t h e o p e r a t i n g bay and the vent s t a c k . Deluge water i s d e l i v e r e d i n d e p e n d e n t l y through a P r i m a c v a l v e w i t h p r e p r i m e d d e l u g e I i n e s , and through a p r e s s u r i z e d water s t o r a g e r e s e r v o i r a n d e x p l o s i v e l y a c t u a t e d d e l u g e v a l v e l o c a t e d a t t h e m i x e r . The f i r e d e t e c t i o n and s u p p r e s s i o n system i s a u t o m a t i c a l l y m o n i t o r e d f o r system f a u l t s a n d c o n t r o l l e d by i n s t r u m e n t a t i o n p r o v i d e d by D e t e c t o r E l e c t r o n i c s Corporation, Minneapolis, Minnesota. S t e p s i n the manufacture o f a t y p i c a l b a t c h a r e r e p o r t e d i n T a b l e IV. F i g u r e 2 g r a p h i c a l l y represents the b l e n d i n g o f dry m a t e r i a l s a t v a r i o u s mixer and chopper speeds by p l o t t i n g the p r o d u c t temperature, a i r temperature above t h e p r o d u c t b o w l , and vacuum v e r s u s t i m e . The m i x e r and chopper were i n c o n t i n u o u s o p e r a t i o n w i t h v a r i a b l e v a l u e s from t h e b e g i n n i n g o f m i x i n g u n t i l a p p r o x i m a t e l y 13 m i n u t e s i n t o t h e p r o c e s s . At t h a t t i m e , t h e m i x e r and chopper were s t o p p e d and p u l s e d (P) f o r 3 seconds a t 50 PPM a t v a r i o u s time i n t e r v a l s .



INLET WATER FLOAT CONTROL «1

VACUUM SET PIONT

WATER HEATER

VACUUM PUMP

PUMP

SS

R1

U

V

HYDRAULIC MOTOR

'

R2-2-MIXER SPEEED

R2-1-CHOPPER SPEED

R1-1-AIR TEMP R1-2-PR0D TEMP

Τ

—ι 1

I

VALVE CAVITY AIR

INSTRUMENT AIR

ACETONE SEAL FLUID

HYDRAULIC POWER PACK

HYDRAULIC PUMP

MIXER SET SWITCHES HI-LO SPEED SWITCHES TIMER SWITCHES TM1 —TM2—ΊΓΜ3—ΤΜ4

BOWL DUMP SWITCH (SW-BD)

FIKE

FIRE SUPPRESSANT 30 GAL. Ο 100 PSI

ADD BINDER ' (SW-B.BT)

SUPPLY AIR

SPRINKLER

REFRIGERATED AIR

FUSIBLE UNK

AIR^7 SWITCH

SMOKE DETECTOR

1

I

F i g u r e 1. 30 L i t e r Migracl M i x i n g System

VACUUM VALVE

IR SENSOR

UV SENSOR

FIXED h—VENT STACK


m

r H

< m

00

S

> ζ α m χ

> r

ο

m

α η η χ

Η Ο

ON

9.

SHOOK ET AL.


157


T a b l e IV. S t e p s i n Remote Manufacture o f S t a r t e r Mix ( C l a s s 1.1), U s i n g a MiGRAD Mixer 1. P l a c e preweighed raw m a t e r i a l s i n dumpers. 2. P l a c e b i n d e r i n tank. 3. Remotely load raw m a t e r l a l s i n t o mixer (Dumpers p l a c e raw m a t e r i a l s i n t o feeder h o p p e r ) . 4. Dry b l e n d t h e raw m a t e r i a l s f o r 3 minutes ( u n l e s s s a f e t y concerns p r o h i b i t d r y b l e n d i n g ) . 5. Add b i n d e r and r u n chopper t o a c h i e v e g r a n u l a t i o n . 6. I n t r o d u c e hot water i n t o m i x i n g bowl j a c k e t and vacuim t o t h e m i x i n g bowl t o remove v o l a t i l e s o l v e n t s . 7. C o n t r o l m i x i n g speed, t i m e , temperature, and vacuum u n t i I d r y i n g i s ccmplete. 8. Open d i s c h a r g e v a l v e t o d i s c h a r g e m i x t u r e i n t o a w a i t i n g containers. 9. C l e a n mixer by f l u s h i n g w i t h c l e a n i n g s o l u t i o n .

By e x a m i n a t i o n o f F i g u r e 2 s t a r t i n g a t z e r o t i m e , t h e d r y i n g r e d i e n t s were f i r s t mixed we 11. Next the mixer and chopper speeds were reduced w h i l e I i q u i d b i n d e r was added. A f t e r b i n d e r a d d i t i o n , the mixer speed was i n c r e a s e d and vacuum and heat were a p p l i e d t o t h e bowl. The d e c r e a s e i n p r o d u c t temperature i n d i c a t e s e v a p o r a t i o n o f s o l v e n t d u r i n g the d r y i n g s t e p . At t h i s p o i n t , t h e mixer and chopper i m p e l l e r s were s t o p p e d , o t h e r than o c c a s i o n a l p u l s i n g t o f a c i I i t a t e d r y i n g o f the mix. When t h e r e was a c o n s t a n t temperature d i f f e r e n t i a l between t h e p r o d u c t and t h e a i r over t h e p r o d u c t bowl, t h e d r y i n g was stopped. T y p i c a l d r y i n g t i m e s a r e 35-45 m i n u t e s . When d r y the p y r o m i x t u r e was unloaded v i a a r e m o t e l y o p e r a t e d , h y d r a u l i c a l l y d r i v e n d i s c h a r g e v a l v e . P a r t i c l e s i z e and v o l a t i l e s were d e t e r m i n e d and t h e mix was f u n c t i o n t e s t e d . Test r e s u l t s i n d i c a t e a homogenous p r o d u c t . F l u i d i z e d Bed Granulator.The f l u i d i z e d b e d s p r a y g r a n u l a t i o n p r o c e s s equipment ( G l a t t U n i t ) was manufactured by the G l a t t Company i n West Germany and d i s t r i b u t e d i n the U n i t e d S t a t e s by G l a t t A i r T e c h n i q u e s , I n c . , Ramsay, New J e r s e y . T e s t s i n d i c a t e d (8) the G l a t t WSG-300 u n i t was c a p a b l e o f m i x i n g , g r a n u l a t i n g , and d r y i n g a 1000 pound b a t c h o f M18 c o l o r e d smoke mix. PBA has two such u n i t s . Each u n i t ( F i g u r e 3) c o n s i s t s of a s t a i n l e s s s t e e l product c o n t a i n e r (bowl), product d o l l y , lower s u p p o r t s e c t i o n , and upper mix chamber s e c t i o n . The p r o d u c t bowl may be removed f r c m t h e s t a t i o n a r y u n i t on t h e p r o d u c t d o l l y . The mix, o r e x p a n s i o n , chamber s e c t i o n o f t h e s t a t i o n a r y u n i t c o n t a i n s t h e b i n d e r s p r a y n o z z l e . The l i q u i d b i n d e r i s



TEMPERATURE DEGREES FAHRENHEIT

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5

6272-1

DATE:

9/29/86

STARTER MIX XXV INERT

F i g u r e 2.

TIME IN

MIGRAD Operat m g P a r a m e t e r s

MINUTES

10 15 20 25 30 35 40 45 50 55 60

BATCH NO:

87.63 48.83 33.44 30.44 29.43 25.75

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LEGEND

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25 φ BATCH 1300 G BINDER 6 mln 0 *»c

χχχ/yyy -

VACUUM IN INCHES OF MERCURY

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6 12 20 40 60 100 PAN

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atomized u s i n g p r e s s u r i z e d a i r . The mix chamber can be removed when n e c e s s a r y t o f a c i l i t a t e f i l t e r c l e a n i n g . On t o o o f t h e mix chamber i s a c o n d u c t i v e c l o t h f i l t e r a t t a c h e d t o a shaker arm which i s used to p r e v e n t l o s s o f m a t e r i a l s by r e t u r n i n g f i n e s t o t h e f l u i d i z e d bed at r e g u l a r i n t e r v a l s . The o u t l e t a i r f l a p i s a l s o l o c a t e d i n t h i s chamber. The i n l e t a i r d u c t , s t a r t i n g a t t h e roof l e v e l o f t h e c u b i c l e , leads t o t h e i n l e t a i r f l a p , i n l e t a i r f i l t e r s , and steam h e a t e d heat exchanger c o i l s t o heat t h e i n l e t a i r . This heated a i r i s d i r e c t e d through a 1/2" s u p p o r t i n g g r i d and 100 mesh s c r e e n on t h e bottom o f t h e p r o d u c t c o n t a i n e r . The equipment o p e r a t e s by n e g a t i v e p r e s s u r e d i f f e r e n t i a l g e n e r a t e d by a t u r b i n e . A i r i s drawn i n t h e i n l e t d u c t , t h r o t t l e d at t h e i n l e t f l a p , c l e a n e d a t t h e i n l e t f i l t e r , h e a t e d a t t h e steam h e a t e d c o i l s , and then used t o f l u i d i z e t h e m a t e r i a l r e s t i n g on t h e s c r e e n i n t h e b o t t c m of t h e p r o d u c t bowl. The a i r i s then c l e a n e d at t h e o u t l e t f i l t e r , t h r o t t l e d a t the o u t l e t f l a p , a n d a c c e l e r a t e d through t h e t u r b i n e t o t h e atmosphere. Each G l a t t u n i t i s equipped w i t h a b i n d e r s o l u t i o n pirrp t h a t s u p p l i e s the l i q u i d binder a t a c o n t r o l l a b l e r a t e t o the a t o m i z i n g n o z z l e l o c a t e d i n t h e m i x i n g chamber. Various safeguards a r e designed into the G l a t t u n i t . In c a s e o f m a t e r i a l i g n i t i o n , t h e G l a t t i s d e s i g n e d t o vent p r e s s u r e b u i l d u p s through t h e r o o f by t h e o p e r a t i o n o f h i n g e d c o v e r s above t h e f i I t e r chamber. These c o v e r s a r e opened by e x c e s s i v e p r e s s u r e i n t h e G l a t t and wi11 not open a t normal o p e r a t i n g p r e s s u r e s . A l a r g e volume water d e l u g e system has been i n s t a l l e d i n t h e G l a t t . I t may be a c t i v a t e d m a n u a l l y o r by two a u t o m a t i c s e n s o r systems. One a u t o m a t i c system o p e r a t e s by UV d e t e c t i o n . The sensor v i e w s through the window o f t h e m i x i n g chamber. The o t h e r a u t o m a t i c system o p e r a t e s by temperature s e n s i n g . A thermocouple l o c a t e d above t h e m i x i n g chamber i s a c t i v a t e d by a temperature that exceeds 210 F. O p e r a t i o n o f any o f t h e t h r e e systems CUV, temperature, o r manual c o n t r o l ) r e s u l t s i n t h e f o l lowing a c t i o n s : 1) The d e l u g e v a l v e s i n t h e G l a t t and t h e c u b i c l e sprinklers are activated. 2] A s i g n a l i s sent t o t h e F i r e S t a t i o n . 3) The G l a t t w i l l shut down and t h e f l u i d i z e d m a t e r l a l s wiI ! s e t t l e . 4) B u i I d i n g fι r e a l a r m s wiI I sound. F l u d i z e d Bed M i x e r Opération. The G l a t t u n i t i s e q u i p p e d w i t h s e n s o r s t o m o n i t o r t h e g r a n u l a t i o n p r o c e s s . The m o n i t o r s a r e l o c a t e d on t h e c o n t r o l panel i n t h e c o n t r o l room. P r e s s u r e s e n s o r s are i n s t a l l e d t o m o n i t o r t h e p r e s s u r e d r o p a c r o s s t h e f l u i d i z e d bed of m a t e r i a l b e i n g g r a n u l a t e d and a c r o s s t h e o u t l e t f i l t e r s . Température s e n s o r s m o n i t o r t h e terrperature o f t h e incoming heated a i r and t h e ex 11 i ng a ιr. A p i t o t tube i s i n s t a I Ied i n t h e ι η I e t a i r d u c t t o m o n i t o r t h e f l o w r a t e o f incoming a i r . These m o n i t o r s a r e used m t h e c o n t r o l of t h e g r a n u l a t i o n p r o c e s s . The G l a t t u n i t i s equipped w i t h a d j u s t a b l e v a l v e s and t i m e r s t h a t a r e used t o c o n t r o l t h e g r a n u l a t i o n p r o c e s s . The phases o f g r a n u l a t i o n a r e : M i x i n g , S p r a y i n g , D r y i n g and C o o l i n g . Timers c o n t r o l t h e time f o r t h e v a r i o u s phases o f t h e g r a n u l a t i o n p r o c e s s . The i n l e t a i r f l o w i s c o n t r o l l e d w i t h e i t h e r t h e i n l e t a i r f l o w



9.

SHOOK ETA L .

Mixing and Handling of Pyrotechnic Materiab

161

c o n t r o l f l a n C v a l v e ) o r the o u t l e t a i r flow c o n t r o l f l a p ( v a l v e ) . The heat input i n t o t h e f l u i d i z e d b e d g r a n u l a t i o n p r o c e s s i s c o n t r o l l e d w i t h a steam c o n t r o l v a l v e . The s e t t i n g s f o r t h e s e n s o r s and c o n t r o l s used i n the G i a t t u n i t a r e l i s t e d ( T a b l e V ) . A f t e r t h e c o n t r o l panel has been p r e s e t w i t h the d e s i r e d c o n t r o l p a r a m e t e r s , t h e c o l o r e d smoke mix b a t c h i s g r a n u l a t e d w i t h l i t t l e o p e r a t o r i n t e r v e n t i o n . In t h e f i r s t phase o f g r a n u l a t i o n , the Mix phase, t h e raw i n g r e d i e n t s a r e mixed w i t h heated a i r . The Mix phase i s long enough t o mix t h e i n g r e d i e n t s b u t s h o r t enough t o p r e v e n t s t r a t i f i c a t i o n . When the Mix phase i s complète, the Spray phase b e g i n s and the b i n d e r i s s p r a y e d i n t o t h e f l u i d i z e d raw i n g r e d i e n t s . T h i s g r a n u l a t e s t h e raw i n g r e d i e n t s . The s p r a y timer c o n t r o l s t h e l e n g t h of time t h a t b i n d e r i s sprayed. During the Spray phase t h e f l u i d i z e d bed becomes h e a v i e r due t o the a d d i t i o n o f the b i n d e r a n d b i n d e r s o l v e n t even though some s o l v e n t ( w a t e r ) i s b e i n g removed by t h e h e a t e d f i u i d i z a t i o n a i r . The f l u i d i z a t i o n a i r volume i s i n c r e a s e d a t t h i s p o i n t by the o p e n i n g o f t h e i n l e t a i r c o n t r o l f l a p w i t h a p r e s e t t i m e r . When t h e s p r a y timer runs o u t , the Spray phase i s f i n i s h e d and the D r y i n g phase b e g i n s . During the D r y i n g phase t h e f l u i d i z e d b e d becomes l i g h t e r due t o t h e removal o f the b i n d e r s o l v e n t ( w a t e r ) . The f l u i d i z a t i o n a i r volume must be d e c r e a s e d when the bed becomes I i g h t e r t o prevent product e n t r a i n m e n t i n t o the o u t l e t f i l t e r s and d e c r e a s e product a t t r i t i o n . A i r volume r e d u c t i o n i s a c h i e v e d by c l o s i n g t h e i n l e t a i r c o n t r o l f l a p with a preset timer. Wnen a p r e s e t f i n a l temperature l i m i t i s reached, the D r y i n g phase i s complete. The b a t c h may be c o o l e d t o the d e s i r e d temperature o r o p t i o n a l I y p r o c e s s i n g may be s t o p p e d a t t h i s p o i n t . F o r c o l o r e d smoke mix, p r o c e s s i n g i s s t o p p e d b e f o r e c o o l i n g t o p r e v e n t the p a r t i c l e s i z e a t t r i t i o n t h a t o c c u r s d u r i n g the C o o l i n g phase. B i n d e r s . Perhaps the most important v a r i a b l e s i n v o l v e d i n g r a n u l a t i o n a r e those r e l a t e d t o the b i n d e r . G r a n u l a t i o n i s dependent on n o t o n l y t h e type o f b i n d e r used, b u t a l s o on t h e c o n c e n t r a t i o n o f the b i n d e r , t h e s p r a y r a t e o f the b i n d e r , the s p r a y s i z e o f the b i n d e r , and t h e t o t a l q u a n t i t y o f b i n d e r i n the mix. S e v e r a l b i n d e r types have been t e s t e d . Two b i n d e r s were found t h a t e f f i c i e n t l y g r a n u l a t e t h e components used i n c o l o r e d smoke mix p r o d u c t i o n . They a r e p o l y v i n y l p y r r o l i d o n e , a w h i t e , f r e e f l o w i n g powder t h a t i s s o l u b l e i n water and o r g a n i c s o l v e n t s , and p o l y v i n y l a l c o h o l (PVA), a w h i t e t o cream c o l o r e d powder t h a t i s water s o l u b l e . PVA was found t o be the most r e l i a b l e b i n d e r . The c o n c e n t r a t i o n o f the b i n d e r e f f e c t s g r a n u l a t i o n because i t must be d i i u t e enough t o f l o w b u t c o n c e n t r a t e d enough t o prevent a d d i n g t o o much s o l v e n t t o the mix. The b i n d e r must be a p p l l e d s l o w l y enough so t h a t too much s o l v e n t i s n o t added t o the mix a t once, b u t r a p i d l y enough t o l i m i t a t t r i t i o n d u r i n g t h e s p r a y phase. Enough b i n d e r must be added t o g r a n u l a t e the mix. The s p r a y s i z e o f t h e b i n d e r i s c o n t r o l l e d by a d j u s t i n g t h e s p r a y a t c m i z a t i o n a i r pressure. A h i g h a t c m i z a t i o n a i r p r e s s u r e a t c m i z e s the b i n d e r . A low a t c m i z a t i o n a i r p r e s s u r e r e s u l t s i n seme b i n d e r d r o p l e t s . The optimum a t c m i z a t i o n a i r p r e s s u r e r e s u l t s i n a s p r a y s i z e which wi 11 g i v e a d e s i r e d p a r t i c l e s i z e d i s t r i b u t i o n i n t h e f i n a l mix. The d e s i r e d p a r t i c l e s i z e d i s t r i b u t i o n i s p r e d o m i n a t e l y i n the 40-100 mesh s i e v e s i z e . (Figure 4)


162

TOXIC CHEMICAL AND EXPLOSIVES FACILITIES T a b l e V.

Table of G l a t t Process S e t t i n g s

Feed R a t e S e t P o i n t : D r i b b l e Speed: 5.0 D r i b b l e P o i n t : 98

90


Glatt Uhit Timer Set Points Mix Time: 3 M i n u t e s A i r Volume Set P o i n t II Time: 15 M i n u t e s F i l t e r Shake I n t e r v a l : 45 Seconds F i I t e r Shake Time: 5 Seconds Spray Time-. 46 M i n u t e s A i r Volume S e t P o i n t M l Time: 15 M i n u t e s

(jlQtt UhLLV9>ve Set PQint? Steam V a l v e S e t P o i n t 1: 85 Steam V a l v e S e t p o i n t 2: 95 I n l e t A i r F l a p P o s i t i o n : 100 A i r Volume S e t P o i n t 1: 38. A i r Volume S e t P o i n t 2: 44 A i r Volume S e t P o i n t 3: 38 Atomization A i r Pressure P r e s e l e c t i o n : Atomization A i r Pressure: 4.0 Bar

2.5 b a r s

Glatt Uhit Limit Set Points Jnteruption Mixing: 35 C Operation Cooling 35 C O p e r a t i o n Drying.70 C I n l e t A i r Temperature L i m i t : 90 C Exhaust A i r Temperature L i m i t ( O p e r a t i o n C o o l i n g ) : 35 C Exhaust A i r Temperature L i m i t ( O p e r a t i o n D r y i n g ) : 65 C :

The b i n d e r and f l u i d i z a t i o n a i r parameters a r e i n b a l a n c e w i t h each o t h e r and a l s o e f f e c t t h e p a r t i c l e s i z e d i s t r i b u t i o n . If the b i n d e r a d d i t i o n r a t e o r b i n d e r s p r a y s i z e were i n c r e a s e d , t h e f l u i d i z a t i o n a i r temperature o r f l u i d i z a t i o n a i r r a t e must be increased t o prevent changing the nature o f the f i n a l product. L i k e w i s e i f t h e f l u i d i z a t i o n a i r temperature or r a t e a r e d e c r e a s e d , the b i n d e r a d d i t i o n r a t e o r s p r a y s i z e must be d e c r e a s e d t o m a i n t a i n the same p a r t i c l e s i z e d i s t r i b u t i o n i n t h e f i n a l m i x . The b i n d e r used i n G l a t t g r a n u l a t i o n i s a s i x p e r c e n t ( 6 % ) b y weight s o l u t i o n o f PVA i n w a t e r . The b i n d e r i s a c c u r a t e l y weighed and s l o w l y poured i n t o t h e s t i r r e d non-heated w a t e r . When a l l t h e PVA i s added, heat i s a p p l i e d t o b r i n g t h e temperature o f t h e s l u r r y t o 185 F. T h i s temperature i s m a i n t a i n e d f o r a t l e a s t 30 m i n u t e s , or u n t i l a l l t h e PVA i s i n s o l u t i o n . At t h i s p o i n t t h e a p p l i c a t i o n of heat i s d i s c o n t i n u e d a n d t h e b i n d e r i s a l l o w e d t o c o o l b e f o r e use. F u l l Scale G l a t t Mixing. The f l u i d i z e d bed g r a n u l a t o r i s one o f t h e most important g r a n u l a t i o n methods a v a i l a b l e today, because i t combines t h e u n i t o p e r a t i o n s o f m i x i n g , g r a n u l a t i n g , a n d d r y i n g i n t o


9. SHOOK ET AL.


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one system. The f l u i d i z e d bed m i x e r , w n i c h has long been used by the p h a r m a c e u t i c a l i n d u s t r y , f i t s many p y r o t e c h n i c p r o c e s s i n g r e q u i r e m e n t s s u c h a s m a t e r i a l s containment, e a s e o f c l e a n i n g , homogeneity o f mix. and hygiene.


N

Hazards A n a l v s t s - G l a t t . B e f o r e t h e G l a t t c o u l d become a f e a s i b l e a l t e r n a t i v e f o r m i x i n g M18 c o l o r e d smoke mix, i t was n e c e s s a r y t o conduct s a f e t y c l a s s i f i c a t i o n t e s t s [ T a b l e I ) . The c o m p o s i t i o n s were t e s t e d i n t h e G l a t t m a n u f a c t u r i n g p r o c e s s and were found t o g e n e r a t e minimal amounts o f e l e c t r o s t a t i c energy d u r i n g the m i x i n g , g r a n u l a t i n g , and d r y i n g p r o c e s s e s . Full scale simulation tests ut i11 ζ ing 740 and 940 pound b a t c h e s i n d i c a t e d t h a t t h e r e were no mass d e t o n a t i o n h a z a r d s d u r i n g m i x i n g . Based on t h e above e v i d e n c e the Department o f Defense E x p l o s i v e s S a f e t y Board a I lowed an i n - p r o c e s s h a z a r d s c l a s s i f i c a t i o n o f 1.3. T h i s a l l o w e d b a t c h s i z e s to be i n c r e a s e d t c 1000 pounds. A c r i t i c a l d i f f e r e n c e e x i s t s between p y r o t e c h n i c and p h a r m a c e u t i c a l p r o c e s s i n g i n t h e G l a t t g r a n u l a t o r . Common pharmaceutical p r a c t i c e involves p r o c e s s i n g w i t h the operator p h y s i c a l l y p r e s e n t a t t h e u n i t t o make a d j u s t m e n t s a s p r o c e s s i n g d i c t a t e s . S a f e t y requirements i n p y r o t e c h n i c s p r o c e s s i n g f o r c e remote o p e r a t i o n . S i n c e p y r o t e c h n i c p r o c e s s i n g must be p e r f o r m e d w i t h o u t t h e l u x u r y o f an o p e r a t o r p h y s i c a l l y p r e s e n t a t t h e u n i t t o make a d j u s t m e n t s a s t h e p r o c e s s i n g d i c t a t e s , d e t a i l e d o p e r a t i n g parameters were d e v e l o p e d f o r each p y r o m i x t u r e . Product Loading. P r o d u c t i o n o f mixes w i t h c o n t r o l l e d p a r t i c l e s i z e d i s t r i b u t i o n s ( F i g u r e 4 ) c a n be a c c o m p l i s h e d i n t h e G l a t t , a n d t h i s c o n t r o l o f p a r t i c l e s i z e i s e s s e n t i a l f o r s u c c e s s f u l automated v o l u m e t r i c feeding of a Stokes r o t a r y press. S l u g production r a t e s exceed 80 s l u g s p e r m i n u t e . T h e r e f o r e a f r e e - f l o w i n g p r o d u c t i s e s s e n t i a l to obtain consistent s l u g q u a l i t y . After production, the s l u g s t r a v e l f l a t on a c o n d u c t i v e rubber conveyor ( F i g u r e 5) t o a g r a v i t y t r a c k where they a r e t u r n e d on edge. Next they r o i I down t o an a u t o m a t i c s l u g placement machine. Four s l u g s a r e f e d i n t o each of two r o t a r y c y l i n d e r s w h i c h r o t a t e t h e s l u g s 90 degrees t o a v e r t i c a l p o s i t i o n . The e i g h t s l u g s f a l l four each i n t o two cans on f l o a t i n g p a l l e t s on t h e conveyor beneath. Proper i n s e r t i o n o f t h e s l u g s i s a s s u r e d by t h e passage o f rods through t h e r o t a r y c y l i n d e r s . The s l u g f i I l e d cans t r a v e l t o an automated c o n s o l i d a t i o n p r e s s where t h e s l u g s a r e c o n s o l i d a t e d i n t o an i n t e g r a l mass (9,JO). Equipment s u r v e y s l e d t o t h e p u r c h a s e o f a t w i n f e e d , 11 s t a t i o n , r o t a r y s l u g g i n g p r e s s (Pennwalt S t o k e s 523 PBX). The p r e s s has a v a r i a b l e p r o d u c t i o n r a t e o f from 60 t o 180 s l u g s p e r m i n u t e . Seme f e a t u r e s o f t h i s p r e s s a r e : d o u b l e a c t i o n compression, 30,000 pound c a p a c i t y , remote pneumatic f i l l weight a d j u s t m e n t , 7.6 cm maximum s l u g diameter p r e s s , vacuum dust c o l l e c t o r s , and e x p l o s i o n p r o o f e l e c t r i c a l c o n t r o l s . The p r e s s i s c a p a b l e o f c o n s i s t e n t l y p r o d u c i n g s l u g s o f u n i f o r m d e n s i t y and s i z e a t a compaction p r e s s u r e of 5000 l b s . V a r i a t i o n s i n t h e p a r t i c l e s i z e d i s t r i b u t i o n o f t h e smoke m i x wi11 o c c u r i n any m i x i n g p r o c e s s . T h e r e f o r e s t u d i e s were made u s i n g t h r e e mixes o f d i f f e r e n t p a r t i c l e s i z e d i s t r i b u t i o n from t h e G l a t t p r o c e s s . The p a r t i c l e s i z e d i s t r i b u t i o n s were i d e n t i f i e d a s "Dusty"


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164

PLOTS

OF

SLUG

THICKNESS

2.46

W > A ^


2.39 (CM) IF OUTLET AIR TEMP - 45 C MIX WILL BE DUSTY

I1 1

6- 4 0 20 100 100

35 C IDEAL

75% 50% 25% 0%

SIEVE SIZE

1 1

25 C COARSE %

THRU SIEVE

6- 4 0 20 100 100 SIEVE

SIZE

1 11

1

6- 4 0 20 100 100 SIEVE SIZE

ADDITION OF: MASS (WATER) AND ENERGY (HEAT) MUST B E BALLANCED AT SPECIFIC LEVELS (OUTLET AIR TEMP) FOR PROPER GRANULATION F i g u r e 4.

R e l a t i o n s h i p Between G l a t t Particle

F i g u r e 5.

S i z e and R e s u l t a n t

Operating Slug

Parameter,

Thickness

S l u g Placement Machine



9.

SHOOK ET AL.


165

(many p a r t i c l e s s m a l l e r than 100 mesh), "Idea!" (most p a r t i c l e s 60-100 mesh), and "Coarse" (many p a r t i c l e s i n 12-40 mesh r a n g e ) . S l u g s were produced u s i n g the t h r e e d i f f e r e n t m i x e s w i t h samples taken at one m i n u t e i n t e r v a l s f o r s l u g t h i c k n e s s checks. Figure 4 shows the g e n e r a l e f f e c t of p a r t i c l e s i z e d i s t r i b u t i o n on s l u g thickness. As was shown above ( F i g u r e 4), a u n i f o r m p a r t i c l e s i z e d i s t r i b u t i o n i s important t o a c h i e v e c o n s i s t e n t p r e s s f e e d i n g . A change i n p a r t i c l e s i z e d i s t r i b u t i o n changes the r a t e a t w h i c h the p a r t i c l e s f l o w and t h e r e f o r e a f f e c t s s l u g p r e s s l o a d i n g . Two v a r i a b l e s t h a t a f f e c t the s l u g q u a l i t y a r e the r a t e of mix f e e d i n t o the s l u g p r e s s d i e and the d i e f i l l v o i u r e . The mix f e e d r a t e v a r i e s d i r e c t l y w i t h m a t e r i a l hopper d i s c h a r g e h e i g h t above the f e e d e r . S l u g d e n s i t y v a r i e s d i r e c t l y w i t h d i e f i 1 1 volume. The d i e f i l l volume i s a d j u s t e d by r a i s i n g or l o w e r i n g the lower punch on the s l u g p r o d u c t i o n p r e s s . If the mix d e n s i t y changes from " i d e a l " to " c o a r s e " , the hopper i s r a i s e d t o i n c r e a s e the f e e d r a t e and the die f i l l volume i s i n c r e a s e d to compensate f o r lower mix b u l k dens ιty. Jet

A i r m i x Mixer Smoke Mix

Batches.

H e x a c h l p r o e t h a n e ( H Q smoke mix p r o d u c t i o n . E v a l u a t i o n of the Sprout Waldron 35 c u b i c f o o t J e t A i r m i x U n i t ( F i g u r e 3) f o r M i x i n g 2,200 pounds of w h i t e HC smoke mix ( c o n s i s t i n g of HC, z i n c o x i d e , and aluminum) was conducted ( H ) . The m i x e r was s e l e c t e d t o r e p l a c e the 340 pound r o t a r y M c C l e l l a n d B l e n d e r . T e s t i n g revealed that improved m i x i n g was acccrrpl i s h e d i n about 2 m i n u t e s w i t h v e r y few r e j e c t e d batches. The J e t A i r m i x u n i t uses d r y , h i g h p r e s s u r e (250-300 p s i ) a i r p u l s e s d i s c h a r g e d through a n g u l a r n o z z l e s t o l i f t , s w i r l , and b l e n d the m a t e r i a l through a t i i r b l i n g a c t i o n . F i v e t o twenty s h o r t (2-5 sec.) p u l s e s spaced w i t h s i m i l a r l y timed pauses represented a ccmplete m i x i n g c y c l e . S a f e t y t e s t i n g i n d i c a t e d low e l e c t r o s t a t i c charge g e n e r a t i o n d u r i n g m i x i n g . P a r a m e t r i c s t u d i e s r e p o r t e d the m a t e r i a l was d i f f i c u l t to i g n i t e . In-process c l a s s i f i c a t i o n of 1.4 was approved. Four m i x e r s have been i n o p e r a t i o n a t PBA f o r s e v e r a l y e a r s . Loading i s from the t o p , u s i n g weigh f e e d e r s and a i r t r a n s f e r equipment. M i x i n g a i r i s d i s c h a r g e d t o a bag house d i r e c t l y above the m i x e r and then through a HEPA f i I t e r . The bag house f i n e s d i s c h a r g e back i n t o the mix and a r e r e c y c l e d . Red Phosphorus smoke mix p r o d u c t i o n . E v a l u a t i o n of t h e Sprout Waldron 35 c u b i c f o o t J e t A i r m i x u n i t f o r p r o d u c t i o n of Red Phosphorus (RP) M8E1 Smoke M i x t u r e s was conducted ( 1 2 ) . R e s u l t s i n d i c a t e d t h e mix was s t a b i l e and not e a s i l y i n i t i a t e d by h e a t , but s e n s i t i v e t o f r i c t i o n and spark s t i m u l i . The b u r n i n g time was slow w i t h dense smoke e m i s s i o n . F u l l s c a l e m i x i n g s t u d i e s were conducted w i t h o u t i n c i d e n t u s i n g 100, 250, 500, and 1,000 pound b a t c h s i z e s . E l e c t r o s t a t i c charge g e n e r a t i o n d u r i n g the b l e n d i n g c y c l e was s e v e r a l o r d e r s of magnitude below t h a t r e q u i r e d f o r i n i t i a t i o n . To f u r t h e r e v a l u a t e the mix an e l e c t r i c match was used t o i n i t i a t e t h e r e a c t i o n of a 1,000 pound b a t c h o f smoke c o m p o s i t i o n . Al I t e s t s were conducted w i t h the b l e n d e r e q u i p p e d w i t h a 16 i n c h


TOXIC CHEMICAL AND EXPLOSIVES FACILITIES


166

diameter r u p t u r e d i s c r a t e d a t 4 p s i and an i n t e r n a ! I y mounted UV d e c t e c t o r and water d e l u g e . Without the use of t h e rapid f i r e d e t e c t i o n and water d e l u g e , a m a s s i v e " f i r e b a l l " was r e l e a s e d . W i t h the use of the r a p i d f i r e d e t e c t i o n and water d e l u g e , t h e r e was no mass f i r e and the mix was dtmped i n t o water f o r c o n t i n u e d f i r e s u p p r e s s i o n . Any f i r e w i t h RP r e s u l t s i n the f o r m a t i o n of w h i t e phosphorus (wP). wP must be c o v e r e d w i t h water s i n c e i t i g n i t e s s p o n t a n e o u s l y when exposed to a i r . P r o c e s s i n g s t u d i e s were conducted t o d e t e r m i n e the b e s t methods f o r p o l l u t i o n abatement s i n c e WP/water m i x t u r e s a r e t o x i c a t 29 ppb f o r b l u e gi11 bream and s i n c e h i g h l e v e l s of phosphorus C r e p o r t e d as t o t a l phosphorus) may not be dumped i n t o the environment. There was no s i g n i f i c a n t damage t o equipment i n the f i r e t e s t s , and i t was demonstrated t h a t a J e t A i r m i x mixer may s a f e l y h a n d l e the m i x i n g of RP f o r m u l a t i o n s on a r o u t i n e b a s i s . S i n c e a h i g h r i s k of f i r e i s always a s s o c i a t e d w i t h any method of t r a n s f e r of RP, a p n a m a t i c c o n v e y i n g s y s t e m (dynamic a i r , two phase p o s i t i v e p r e s s u r e t r a n s f e r system) was e v a l u a t e d t o load RP i n t o the J e t A i r m i x m i x e r . E l e c t r o s t a t i c c h a r g e measurements were minimal and i n d i c a t e d the system was s a t i s f a c t o r y t o l o a d the b l e n d e r . Al I work was conducted w i t h "οι l e d " RP as s u p p l l e d by ERGO L i m i t e d , Canada. The " o i l e d " RP i s much l e s s s e n s i t i v e than " n o n - o i l e d " RP. Conclusion. Proper s a f e t y t e s t i n g and c l a s s i f i c a t i o n of p y r o t e c h n i c e n e r g e t i c c a p a c i t y w i l l a l l o w the s e l e c t i o n of a p p r o p r i a t e , remotely o p e r a t e d , corrmercial l y a v a i l a b l e equipment. T h i s eouicment can be i n s t a l l e d i n l e s s c o s t l y s t r u c t u r e s and p l a n t s i t e s f o r the m a n u f a c t u r e of p y r o t e c h n i c m a t e r i a l s i n a s a f e and economical manner. O f t e n , c o n s i d e r a b l e problems a r i s e i n c o s t and s a f e t y when p y r o t e c h n i c formulas a r e s e l e c t e d frcm the l i t e r a t u r e and used w i t h o u t r e g a r d f o r t h e e n e r g e t i c requirements o f the task t o be acccmpl i s h e d . For example s t a r t e r mix formulas mav be too r e a c t i v e f o r t h e i r intended use, but they c o u l d be used i f they were m o d i f i e d and t e s t e d r e l a t i v e t o p e r c e n t c o m p o s i t i o n , p a r t i c l e s i z e , c o n s o l i d a t i o n p r e s s u r e , p u r i t y , e t c . t o g a i n a 1.3 or 1.4 UNO classification. The c o n t i n u e d a d d i t i o n of i n g r e d i e n t s over the y e a r s f o r h e a t i n g or c o o l i n g o f a f o r m u l a t i o n w i t h o u t r e g a r d t o the b a s i c c h e m i s t r y o f the m i x t u r e was a p r o b l e m t h a t was n o t e d through r e v i e w of many f o r m u l a t i o n s i n the l i t e r a t u r e . Thus many examples may be found where " e x t r a " i n g r e d i e n t s have been i n c l u d e d w h i c h tend to negate each o t h e r and r a i s e p r o d u c t i o n c o s t s . The American P y r o t e c h n i c s A s s o c i a t i o n , P.O. Box 213, C h e s t e r t o w n , M a r y l a n d 21620, an i n d u s t r y a s s o c i a t i o n , p r o v i d e s a s s i s t a n c e t o m a n u f a c t u r e r s t h a t r e q u i r e more i n f o r m a t i o n . Annual Summer Symposia i n P y r o t e c h n i c C h e m i s t r y a r e a l s o o f f e r e d by Washington Col l e g e , C h e s t e r t o w n , M a r y l a n d 21620. The I n t e r n a t i o n a l P y r o t e c h n i c s Seminar on E x p l o s i v e s and P y r o t e c h n i c s i s o f f e r e d on a b i e n n i a l b a s i s . A d d i t i o n a l i n f o r m a t i o n on t h e s e seminars may be o b t a i n e d from I IT R e s e a r c h I n s t i t u t e , Chicago, I l l i n o i s 60616.


9. SHOOK ET AL.


Literature Cited McLain, Joseph H. Pyrotechnics; The Franklin Institute Press Philadelphia, Pennsylvania. (1980). 2. Conkling, John A. Chemistry of Pyrotechnics: Marcel Dekker, Inc. New York (1985). 3. Meyer, Rudolf. Explosives; Verlag Chemie, New York (1977). 4. Safety Regulation (AMC-R 385-100, Chapter 17), U.S. Army Material Command, Alexandria, Virginia 22333-0001 (1985). 5. Armour, Carl; and Smith, Lloyd A.; "The Invention of a New Type of Friction Sensitivity Apparatus," RDTR No. 60, 11 June 1965, U.S. Naval Ammunition Depot, Crane. IN 6. McIntyre, F.L. Safety Enhancement Program for MIGRAD Mixer Study; U.S. Army Armament, Munitions, and Chemical Command, Aberdeen Proving Ground, Maryland, 21010 (1985). 7. Aikman, Loy; Shook, Thomas E.; Lehr, Robert; Robinson, Eddie; and McIntyre, F.L.; Improved Mixing, Granulation and Drying of Highly Energetic Pyromixtures; Pine Bluff Arsenal, Pine Bluff, Arkansas 71602-9500 (1986). 8. Garcia, David; Aikman, Loy; Abies, Larry; McIntyre, Fred; and Shook, Thomas; Smoke Mix Facility (Glatt); Pine Bluff Arsenal, Arkansas 71611 (1983). 9. Garcia, David J.; Aikman, Loy M.; McIntyre, F.L.; and Shook, Thomas E.; Rapid Plant Scale Mixing Granulation and Loading of Dry Materials During the Manufacture of Colored Smoke Munitions; Pine Bluff Arsenal, Pine Bluff, Arkansas 71602-9500 (1981). 10. Aikman, Loy; Garcia, David; and Shook, Thomas E.; New Fill and Press Technology for Production of Colored Smoke Grenades; Pine Bluff Arsenal, Pine Bluff, Arkansas 71602-9500 (1982). 11. Fortner, Wendell; Yeldell, Steven L; and Shook, Thomas E.; HC Product Improvement Studies: Pine Bluff Arsenal, Ρine Bluff, Arkansas 71602-9500 (1977). 12. McIntyre, Fred; Amend, R.J.; and Smith, M.; Blending Technology for Red Phorphuros Smoke Compositions, U.S. Army Armament, Munition and Chemical Command. Aberdeen Proving Ground, Maryland 21010-5423 (1985).


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RECEIVED May 1, 1987


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Remote Mixing and Handling Procedures for Pyrotechnic Materials

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