Document RpryvN1OmwzBvvGZpXDq5Qr8z
FILE NAME Quigley QUIG
DATE 0000 DOC QUIG007
DOCUMENT DESCRIPTION Government Report
PM DIATOMITE MINING
_
AND PROCESSING
W. Clark Cooper M. D.
Medical Director
Lewis J. Cralley Ph D.
Scientist Director
With the Assistance of
W. H. Clark M. and B. R. Hubbard M. S. California State Department of Public Health D. J. Hurley M. D. Nevada State Department
of Health and R. R. Sullivan M. Oregon State Board of Health
Prepared under Direction of
W. M. Gafafer D. Sc Technical Adviser
U.
DEPARTMENT OF HEALTH EDUCATION
Public Health Service
Bureau of State Services Division of Special Health Services
Occupational Health Program
AND
WELFARE
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Environmental Studies
27
ture content may exceed 5 percent The values in the table are
within the general range reported by others 38 39 47 48 No
apparent difference is noted in the chemical composition of the
crude diatomite from the two sources
TABLE 1. Percent composition by dry weight of crude diatomite according to source
Component
Percent
Fresh Salt
+
water
diatomite
diatomite
Component
.
;
an
Percentweighbty dry
.
Salt Fresh water
;
diatomite diatomite
Ignition loss 0200...
SiO
eee
eee
Al2O3 ooo... Seen,
|
Fe
TiO TiO
CaO
0. cce Os.20.... eee
eee
6.4
187.8
2.6
.9
2
20
8.1 |! MgO ..ccrccscecnsscceuee
1.85 || K eee ee eeeeee
3.6
Naso ....
1.6 || Undetermined
.2
.1
Total
0.5 .2
46 8
100.0
0.2 .1 al .5
100.0
1 Essentially amorphous silica
2 Trace
. .
Quartz in Parent Material Settled Dust and Airborne Dust .
Table 2 shows the percent by weight of quartz in overburden
_
crude diatomite and mixed mill dust The crude and various
diatomite products and their settled and airborne components
had a mean quartz content of 2 percent and under Overburden
had a mean quartz content under 5 percent Although the per-
centage values for quartz will vary with the source of the crude
and within the same deposit these values based on a total of 68
samples are believed to be representative The values found in-
dicate that exposure to quartz is not a problem in the diatomite
processing industry studied
Table 2.
Percent by weight of quartz in parent muteriul settled dust and airborne dust according to product 5 plants combined
Product
Ox rburdeni Uru le dialoituke Milk d prachuet
|
Parent material
|
Settled dust
fT
Seen ee ene eee one ananassae
*
Quartz
: Number {|
of
|
percent by weight
|
samples
i
!
| Number of
|{ samples
Quartz percent by
weight
| |
i Range | | | | Mean
Range Mean
_
Sw
mtepmmeree
mt
mee
at
ene]
8 ewe]
i
{
"
Airborne dust ne eee
Quartz
Number of
percent hy weight
samples fo
Range | Meun
ee eet ene oe leone ape
4
0 12
4
3 i
27
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1
i
11 #
2
a} 1-5
2
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0-4
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gs
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2
Cristobalite in Parent Material Settled Dust and Airborne Dust
.
No cristobalite was noted in the overburden crude diatomite
natural diatomite or temperature calcined diatomite
ke]
Es
Z
.
;
bEee
Rs
EA
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=
a A:
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products Although a small percentage of cristobalite was found
in one sample of airborne natural powder dust this was likely due to contamination from temperature straight
and calcined materials The crude diatomite and the natural
and temperature straight products were essentially amorphous silica In this report temperature straight cined diatomite was included and treated as a part of the natural
powder category Diatomite with only trace amounts of cristobalite is classed as cristobalite material
Tridymite was not detectable in any of the parent materials settled dust or airborne dust by ray diffraction techniques and
problem does not appear to constitute a
industry studied
in
in the diatomite processing
The percent of cristobalitein parent material settled dust and .
airborne dust according to type of diatomite product is shown
in table 3
"
TABLE 3.
Percent by weight of cristobalitein parent material settled dust and airborne dust according to product 5 plants combined
Parent material
Settled dust
Airborne dist
rn
Product
Number
: | of sam ples
Cristobalite
|
j. percent by | Number
weight
of sum-
ples
Cristobalite
percent
weight
:
by NumberNumber
of sam
ples
Range | Menn
Range | Mean
Cristobalite
percent Cristobalite by
weight
_
Range Mean
Natural
:
Main product
Bagliouse product.
Straight 1
0 0-1
2
rs
:
A
A
:
i
eee
VV
!
2
VV
,
.
Main product .... Baghouse product
4 10-20
15
30- 8-37
27
3
12-26
17
,, 11-31 11-31
,"
30-
252
ry).
#
,
calcined
Main product
5 [ 44-59 44-59
3,\~
8 16-66
38
TI]
15-46
22
Baghouse product fT 58- / 61
erferen .
All types
a
mixed =? |areeeres[eseeeees
4] 21-64
45
4
23-10
22
| 4
57-95
275
:
18 | 10-63
25
4]
7-26
16
High temperature Baghouse classification arcas
The temperature straight diatomite had an
e729
average cristobalite content of 15 percent for main product and
eran
21 percent for baghouse product calcined diatomite had an
2:
average cristobalite content of 49 percent for main product and
61 percent for baghouse product The cristobalite content of the
g< ht
temperature straight product was variable and was -
probably influenced by the amount of natural flux in the purified
_
crude ray diffraction patterns showing percent of cristobalite
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