Document e7YgBaaYdaDbQ7qO6QnrEjwre
GRACE
061543C1
Zonolite
Construction Products Division
DISTRIBUTION
E. S. Wood J. W. Wolter H. C. Duecker B. R. Williams J. C. Yang 0. M. Favorito F. W. Eaton__________ R. H. Locke R. E. Schneider D. D. Walczyk/Proj. File
July 15, 1977
r
w
15170077
06154361
AIRBORNE FIBER REMOVAL BY AIR SEPARATION P-207
REC'D
OBJECTIVE:
"JL 1 91377
Reduce the airborne fibers present during products application to acceptable levels by the use of air separation equipment.
w.r'.D. ENG.
BACKGROUND;
Tests were conducted at Kearney in April (see report dated 4/14/77 "Airborne Fiber Removal by Air Separation")which showed that drop test fiber counts were lower on material which had been run through the Kearney D-18 modified cooler chute and stoner without any aspiration air than material which had been run through the same equipment with the air on. This result did not appear logical so the following, more comprehensive, test series was con ducted.
TEST METHOD:
120 - 3 cf bags of Libby #1 attic fill were produced at Weedsport. Twenty bags were retained at Weedsport as a control and one hundred were shipped to Kearney.
. Test 1 - Twenty of the bags shipped to Kearney were re turned to Weedsport without being subjected to testing on the Kearney equipment.
. Test 2 - Twenty bags were run through the cooler chute/ stoner without having any aspirating air on either the cooler chute or stoner.
. Test 3 - Twenty bags were run through the cooler/stoner once with air on.
. Test 4 - Twenty bags were run through the cooler/stoner twice with air on.
. Test 5 - Twenty bags were run through the cooler/stoner three times with the air on.
Static pressure on the constant velocity vent system was increased from 4%" H2O to 5V H2O and the cooler chute damper was full open in order to maximize the air flows.
All material was returned to Weedsport for drop tests and simulated attic tests. The volume of each bag was checked initially at Kearney, at Kearney after testing and at Weedsport prior to fiber testing. Screen analyses were run on each material before and after testing and after shipping back to Weedsport.
15170078
Airborne Fiber Removal by Air Separation P-207, Continued Page 2
061543G}
CONCLUSIONS:
1. Air scrubbing of expanded #1 Libby in the cooler chute/ stoner is not an effective means of reducing airborne fibers.
2. The reductionsin airborne fiber counts noted, due to just handling expanded product, suggests that techniques not involving air separation might be effective. There is not, however, sufficient information available in these test results to indicate a technique.
3. Visible dust is not an indication of the presence of high fiber counts.
^ 4. Fibers are not released from the breaking down of the V material.
5. Volume losses of 3% due to passing through the equipment in these tests are much lower than the shrinkage losses experienced in binder addition tests on Libby #1.
6. As the number of passes through the equipment increased, the fines collected by the cyclone increased indicating that as the material breaks down it is removed by the air separating equipment.
RECOMMENDATIONS:
1. This is the first indication of a favorable pattern developing in the fiber reduction program. V7e would strongly recommend an intense study be initiated by management to determine the reasons why agitation and screening without air separation results in lower fiber counts on. Libby #1. This will require basic research from our own and perhaps corporate research facilities.
15170079
Q G_
Airborne Fiber Removal by Air Separation P-207, Continued Page 3
CGIS'3C4
RESULTS;
1. Material which had been run through the equipment without any air had as low an airborne fiber count in both drop tests and simulated attic tests as material which had been subjected to three passes with the air on. (Table 1, page A-l, Test 2 vs Test 5.)
.2 This result duplicated the pattern obtained with previous
air separating tests conducted in April.
May Test (#1 Libby)
April Test (#2 Libby) Fiber Count (T.W.A.) Fiber Count (T.W.A.)
Control
3.35 f/ml
Control
7.184
Air Off
1.89 f/ml
Air Off (Test 2) 1.968
Air On
2.35 f/ml
Air On (Test 3) '3.53
3. Material which had been shipped to Kearney and returned without any processing showed a considerable drop in fiber counts in both drop tests and simulated attic tests. (Table 1, Page A-l, Test 2 vs Test C.)
4. The airborne fiber count of the control (7.184 f/ml) is con siderably lower than previous tests using #1 Libby. On report dated June 15, Test 9A, the fiber count, (T.W.A.) was 17.245 f/ml. Test 12A was 11.045 f/ml and Test 17A was 16.25 f/ml. The plant believes this material was received April 26, 1977 on BN 451684 and had an assay yield of 81.8 bags/ton.
5. Exposing the material to increasing amounts of air separation did not lower fiber counts of either the drop tests or the simulated attic fill appreciably. (Table 1, Tests 3, 4, and 5, Page A-l.)
6. All material tested at Weedsport was extremely dusty and many of the filters could not be analyzed by the lab. An attempt was made to read one of the dust loaded filters in Tests C, 1 and 5, so that a best possible T.V7.A. fiber count could be obtained. However, the accuracy of these results are question able.
7. Visually the dust levels of all materials tested appeared about equal and as has been concluded in previous tests visual dust is not an indication of fiber levels.
15170080
Airborne Fiber RemoveTM' by Air Separation P-207, continued Page 4
06154365
8. Material break down was approximately 3% each time it was run through the equipment with the air on and 5% with the air off. The breakdown in shipping back to Weedsport was 5 to 7%. (Table 2, Page A-2.) However, each time the volume is checked to measure the loss there will be some compaction and breakdown associated with the volume check itself. Previous tests have shown this to be around 2% on Libby #1. (Report dated May 31, 1977, Table 2, Page a-2 Test 9A and 12A.) If 2% is subtracted from the results on Table 2 a corrected loss is obtained which should be close to actual "in bag" losses.
9. From a comparison of the fiber levels of the control, which was not shipped to Kearney.and back, and Test 1 which had a breakdown/compaction loss of 5.6%, the increased break down did not release more fibers. (Table 1, Page A-l.)
10. Screen analyses (Table 3 , Page A-3) show that generally the 4 mesh material is breaking down to the 8 mesh material. The respirable dust size which would probably be in the pan is generally around 1% which seems low when observing the extreme dustiness of this material during drop and attic tests. However, segregation does occur in the bag with the fine dust collecting at the bottom. Grab samples taken in the middle or top of the bag would not detect this.
11. Cyclone fines were removed from the product as follows:
Test 3 Test 4 Test 5
- 5.8 lbs. - 9.1 lbs. - 12.1 lbs.
The increasing amount of cyclone fines removed indicates that as the material breaksdown in each pass through the equipment, the air separating equipment removes it.
15170081
Q
Airborne Fiber Removal by Air Separation P-207, Continued Pace 5
06154266
DISCUSSION:
A very significant pattern has developed both from the air separating tests and binder tests where bagging hopper screens were used. Although the data is limited, it appears that agitation and screening of the material without air separation does reduce the fiber count on some sizes. This is opposite to what we expected. If we can determine why this is so, perhaps it can be used to greater advantage. Many questions are posed by these results.
. When no air is used, where are the fibers going?
. What effect do electrostatic charges have?
. Does air increase or decrease these charges?
. If static charges are binding the fiber to the material can these charges be reduced to allow the air to remove the fibers?
. If static charges are binding the fibers to the material, can these charges be increased to further bind the fibers to the material?
A very carefully constructed and controlled series of tests should be run to determine the answers. Since the questions will involve basic research, Cambridge R&D and perhaps corporate research should be involved.
MMW;mt
M. M. Williams 5/14/77
X 517006 2
TABLE 1
Q_
FIBER EVALUATION - LIBBY #1 AIR ELUTRIATION
A-!.
61543G7
Date
Material
Prod. Identification
Sampling Conditions
Date
Location
Min.
Fiber Analysis
(f/ml)
Max.
Avg./TWA 2/8
About 5/6
Test C Production Mat'l retained at Weedsport
6/7 Drop Test
3.85
12.83 7.184/
(Avg. 5 lab results)
6/7 Simulated
1.43
3.80 2.615/0.654
attic - approx.
14 - 3 cf bags
About 5/6
Test 1 Shipped to Kearney & Returned to Weedsport. No air separation
6/8 6/8
Drop Test
0.86
7.70 3.103/
(Avg. 4 lab results)
Simulated
0.47
1.43 0.95/0.238
attic - approx.
14 - 3 cf bags
About 5/6
Test 2 Ran Through Kearney D-18 cooler stoner once. No air
6/8 6/8
Drop Test
0.86
3.42 ,1.968/
(Avg. 5 lab results)
Simulated
0.53
2.14 1.335/0.334
attic - approx.
14 - 3 cf bags
About 5/6
Test 3 Ran through cooler/stoner once w/air on
6/8 6/7
Drop Test
2.14
4.28 3.-53/
(Avg. 4 lab results)
Simulated attic
approx. 14 - 1.60
2.14 1.87/0.468
3 cf bags
About 5/6
Test 4 Ran through cooler/stoner twice w/air on
6/7 Drop Test
1.71
3.42 2.885/
(Avg. 4 lab results)
6/7 Simulated
0.47
1.90 1.185/0.296
attic - approx.
14 - 3 cf bags
About 5/6
Test 5 Ran through cooler/stoner 3 times w/air on
6/8 Drop Test
0.86
4.65 1.956/
(Avg. 5 lab results)
6/8 Simulated
1.07
1.60 1.335/0.334
attic - approx.
14 - 3 cf bags
15170083
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t::: TABLE 3
*
A-* 06154360
Test No.
Mesh
Control retained at Weedsport
4 8 16 30 50 Pan
Test 1 shipping control not run through equipment
4 8 16 3050 Pan
Test 2 run through equipment no air
4 8 16 30 50 Pan
Test 3 air on run through once
4 8 16 30 50 Pan
Test 4 air on run through twice
4 8 16 30 50 Pan
Test 5 air on run through three times
4 8 16 30 50 Pan
Before Test
Wt. Cum.
qms %.
%
Aft^ Wt. qms %
35.0 13.4
1.1 0
. 0.1 0.4
70.0 26.8
2.2 0
0.2 0.8
70.0 96.8 99.0 99.0 99.2 100
i
~"fofter Shipping
Cum. Wt.
Cum.
% qms %
%
34.9 14.0
.5 .2 .1 .3
69.8 69.8 28.0 97.8
1.0 98.8 0.4 99.2 0.2 99.4 0.6 100
42.2 6.9 0.2 0.2 0.1 0.4
84.4 84.4 13.8 98.2
0.4 98.6 0.4 99.0 0.2 99.2 0.8 100
40.0 9.8 0.1 0 0 0.1
80.0 80.0 19.6 99.6
0.2 99.8 0 99.8 0 99.8
0.2 100
38.3 11.4
0.1 0 0
0.2
76.6 76.6 22.8 99.4
0.2 99.6 0 99.6 0 99.6
0.4 100
33.0 16.4
0.1 0.3
0 0.2
66.0 66.0 32.8 98.8
0.2 99.0 0.6 99.6
0 99.6 0.4 100
43.0 7.0 0 0 0 0
86.0 86.0 14.0 100
0 100 0 100 0 100 0 100
29.5 19.7
0.8 0 0 0
59.0 59.0 39.4 98.4
1.6 100 0 100 0 100 0 100
35.1 13.9
0.2 0
0.2 0.6
70.2 70.2 27.8 98.0
0.4 98.4 0 98.4
0.4 98.8 1.2 100
34.3 15.3
0.1 0.1 0.1 0.1
68.6 68.6 36.5
30.6 99.2 13.3
0.2 99.4 0.2
0.2 99.6
0
0.2 99.8 '
0
0.2 100
0
73.0 73.0 26.6 99.6
0.4 100 0 100 0 100 0 100
30.2 16.3
2.8 0.2
0 0.5
60.4 60.4 32.6 93,0
5.6 98.6 0.4 99.0
0 99.0 1.0 100
41.0 8.7 0 0.1 0.1 0.1
82.0 82.0 17.4 99.4
0 99.4 0.2 99.6 0.2 99.8 0.2 100
38.6 11.1
0.2 0.1
0
0
72.2 72.2 22.2 99.4
0.4 99.8 0.2 100
0 100 0 100
32.9 16.0
1.0 0 0
0.1
65.8 65.8 32.0 97.8
2.0 99.8 0 99.8 0 99.8
0.2 100
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