Industrial minerals in Southern California's wallboard joint cement industry: a potential for mineral development in Arizona

              INDUSTRIAL MINERALS IN SOUTHERN CALIFORNIA'S
WALLBOARD JOINT CEMENT INDUSTRY
A POTENTIAL FOR MINERAL DEVELOPMENT IN ARIZONA
Open File Report 89-3
September 1989
by Ken Phillips
Chief Engineer
Arizona Department of Mines and Mineral Resources
1502 West Washington
Phoenix, Arizona 85007
This is a preliminary report,
Subject to technical and
Editorial revision.
Arizona Department of Mines and Mineral Resources
Open File Report 89-3
September, 1989
INDUSTRIAL MINERALS IN SOUTHERN CALIFORNIA'S
WALLBOARD JOINT CEMENT INDUSTRY,
A POTENTIAL FOR MINERAL DEVELOPMENT IN ARIZONA
by Ken A. Phillips. Chief Engineer
Abstract
This report briefly describes southern California's wallboard joint cement industry, and in more de-tail,
the specifications and quantities of industrial minerals consumed.
The Stouffer California wallboard joint cement manufacturing industry is believed to use a larger
quantity of industrial minerals as extender pigments and functional fillers than any other southern Cali-fornia
industry. Minerals used include limestone, talc, mica, kaolin clay, attapulgite clay, gypsum, and
perlite. Southern California companies annually consume more than 640 million pounds (320,000 short
tons) of minerals, with a value in excess of $15.5 million, for use in manufacturing joint cement. Since
most of these minerals are not currently produced in Arizona, and Arizona deposits are within a reason-able
shipping distance to southern California, a market for Arizona material exists.
Acknowledgements
I would like to take this opportunity to ex-press
my appreciation to all of the following
southern California manufacturers who provided
assistance and information: Supro Corporation,
Pomona, California; Hamilton Materials, Inc.,
Orange, California; Beadex Manufacturing,
Riverside, California; U.S. Gypsum Company,
Torrence, California; Custom Building Prod-ucts,
Bell, California; and Crystal Corporation,
Castaic, California. Without their cooperation
the data to assemble this report would not have
been available.
A special thank you is extended to Tim
Whitney of Murco Wall Products, Buckeye,
Arizona for taking the time to provide an educa-tion
on joint cement manufacturing and raw ma-terials,
and for his review of this chapter.
Development Potential in Arizona
An opportunity for development of Arizona
mineral deposits exists. Few of these minerals
are currently mined in Arizona, despite the like-lihood
that significant deposits occur in the
state. Joint cement manufacturers in southern
California are within a reasonable distance from
Arizona deposits. In many cases their current
sources are more distant. Arizona’s joint cement
manufacturers in Arizona and the Southwest use
many of the same minerals.
Wallboard Joint Cement
The wallboard joint cement manufacturing
industry in Southern California is believed to
use the largest quantity of industrial minerals as
functional fillers of any Southern California in-dustry.
For the purpose of this report, products
such as wallboard texture coatings and ceiling
texture spray coatings are included.
Wallboard joint cement is known by a num-ber
of common names including ‘dry wall mud,’
‘tape joint compound,’ ‘joint cement,’ and
‘mud.’ It is the sealer and adhesive used to at-tach
joint tape to the junctions between sheets of
gypsum wallboard on walls and ceilings. Wall-board
is also called gypsum board and Sheet-rock
®.
In addition to being used with joint tape to
hide or conceal joints, it is also used to cover
nail and screw heads and to cover the wall-board's
paper surface to provide an equally ab-sorbent
and uniform surface prior to the applica-tion
of a decorative coating such as paint.
Wallboard joint cement is produced in a
number of different varieties for use in various
applications. Types such as chemically setting,
lightweight, topping, and all-purpose are all
made for differing applications or environ-mental
conditions of application. Wallboard
joint cement is manufactured as both a wet
ready to use product and as a dry powder that
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must be mixed with water at the job site prior to
application.
Wall and ceiling texture compounds are
manufactured for application to wallboard sur-faces
after taping and sealing to provide a deco-rative
texture for walls and ceilings. Wall tex-ture
coatings are nearly always subsequently
painted, while ceiling texture coatings do not
necessarily require painting.
Wallboard joint cement is a mixture of raw
materials. It generally consists of a binder, wa-ter,
chemical additives, and mineral fillers. The
binder is either a liquid vinyl resin as a latex for
wet, ready to use products or a starch or spray-dried
vinyl resin for dry mix products. Chemical
additives include ethylene glycol (to prevent
freezing or control drying time), various dryers,
and preservatives. The mineral fillers make up
the major portion of the product.
Wall and ceiling texture coatings additionally
contain hiding pigments such as titanium diox-ide.
Ceiling coatings usually contain coarsely
ground expanded polystyrene particles. Ceiling
coatings requiring acoustical properties may
contain expanded vermiculite or popped perlite.
Ready to use wallboard joint cement is pack-aged
in four gallon boxes weighing 50 pounds,
one gallon pails, and pails weighing 62 pounds.
Dry mix joint cement is packaged in 25-pound
bags. Lightweight joint cement made in south-ern
California is packaged in four-gallon boxes
weighing 30 - 40 pounds.
Functional Fillers
Functional fillers for wallboard joint cement
can, for the purpose of discussion, be divided
into two groups; those which impart some use-ful
property such as strength or sag resistance to
the final mixture and those that fill space, add
bulk, and extend the usefulness of the other con-stituents.
Ground limestone is the most common
bulk filler in joint cement, but many white, non
water-soluble mineral fillers could be used in its
place if they were available at a competitive
price. Functional fillers used include mica, talc,
kaolin clay, attapulgite clay, and popped perlite.
Southern California’s Joint Cement
Manufacturing Industry
Southern California's joint cement manufac-turing
industry consists of seven plants produc-ing
over 18 million boxes (average weight per
box: 50 pounds or the equivalent in pails and
dry mix material) of joint cement and wall tex-ture
coating a year. In addition to the six com-panies
listed under acknowledgements on page
1, Gold Bond Building Products operates a joint
cement manufacturing plant in Long Beach,
California. These plants manufacture nearly all
of the joint cement consumed in the state, sup-ply
about 20 percent of the joint cement con-sumed
in Arizona, and export material to other
states and foreign countries. Most of the plants
produce joint cement and wall/ceiling texture
coatings. Major gypsum wallboard manufactur-ers
operate two of the plants. One company pro-duces
a complete line of do-it-yourself wall re-pair
products including tile grouts and patching
materials primarily distributed through retail
establishments.
Wallboard joint cement is used in new and
remodeling construction only. Thus the eco-nomic
health of that industry directly affects the
quantity of joint cement consumed. Further, it is
used when gypsum wallboard is used as an inte-rior
wall or ceiling covering. Neither wood or
vinyl paneling nor lathe and plaster require joint
cement.
Industrial Minerals in Joint Cement
Southern California joint cement manufac-turers
consume at least six different industrial
minerals as functional fillers. They are listed in
Table 1 along with typical annual consumption
and prices. Typical price ranges are given to
help estimate the size of the market. The lowest
prices are often those paid by warehouses and
the largest bulk users, while the highest prices
are often in quantities of single pallet loads and
materials obtained through distributors' ware-houses.
Material may be supplied in bulk rail
cars, bulk trucks, ‘super sacks’ (bulk bags which
hold from 1000 to 3000 pounds), or in 50-pound
paper bags. The larger consumers often negoti-ate
prices and delivery contracts directly with
the mining-processing-supplier company at
terms lower than published prices.
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The industrial minerals used in joint cement
manufactured in the state are described in the
remainder of this chapter. All are very finely
ground and must conform to detailed specifica-tions.
Some are interchangeable in certain uses.
Those interested in developing new sources
of these minerals should be fully aware of the
idiosyncrasies of the industrial minerals indus-try.
Suppliers of minerals to the industry are ex-pected
to provide considerable technical data
and support to potential consumers.
Table 1. - Industrial Minerals Used by Southern California’s Wallboard
Joint Cement Manufactures - Typical total annual consumption
Commodity Quantity Price Paid by Consumers
(tons) Minimum paid Maximum paid
Limestone 264,000 $33 $50
Mica 9,646 248 280
Talc 1,966 82 139
Kaolin 5,702 119 200
Attapulgite clay 2,869 233
Perlite 3,590
Bentonite Clay 2,135
Sepiolite Clay 3,708
Gypsum 2,400
Silica * 25,000
Diatomaceous Earth Could be used in place of perlite fines
Pyrophyllite Could be used in place of some mica
Wollastonite Could be used in place of some mica
Feldspar Could be used in place of some to all limestone if
it were available at a competitive price
*Silica is used primarily in tile grout products but is included here to protect individual company pro-prietary
data.
Calcium Carbonate
The most used filler in joint cement is cal-cium
carbonate, primarily used as fine ground
white limestone or marble. It is ground much
finer than 325 mesh with the mean particle size
being in the range of 10 to 15 microns. Calcium
carbonate supplies volume solids or bulk at a
low cost. At about $0.017 per pound (or 42 to
51 cents per 50 pound box), it is the cheapest
ingredient in joint cement.
Calcium carbonate's tendency to ‘frost’ or
‘chalk’ when repeatedly exposed to moisture
does not present a problem in joint cement. Joint
cement is very seldom used in exterior applica-tions
and is always protected by painting.
The three most important specifications for
ground calcium carbonate to be used in joint
cement are whiteness, chemical stability, and
particle size. Whiteness is important because the
finished product must be white to avoid show-ing
through paint coating applied over the joint
cement, especially since most interior walls in
residential construction are painted white or
very light colors. Whiteness should be above 90.
Fine and consistent particle size is important to
manufacturing a joint cement that applies
evenly. The necessity for chemical stability is
somewhat nebulous. Limestone or marble that
can be ground for joint cement use must be free
of water soluble or water absorbable foreign
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minerals that could cause tape adhesion prob-lems
or the appearance of blemishes in the wall
coating. Common clays are typical impurities
that should be avoided. However, the limestone
or marble need not be pure CaCO3. Dolomitic
limestone or marble can be used if white. Many
white silicate minerals such as a feldspar or py-rophyllite
could also be used, but must compete
on a price basis with ground limestone.
All of the ground limestone used by Southern
California joint cement manufacturers is pro-duced
at Lucerne Valley in southern California.
The cost of shipping ground limestone from Lu-cerne
Valley to the various southern California
area manufacturers ranges from $8.00 to $11.00
per ton in bulk trucks.
Calcium carbonate used in joint cement is
one of two average particle sizes: 10 microns 15
microns (U.S. sieve mesh 325 is approximately
44 microns).
A typical specification for fine ground cal-cium
carbonate used in the manufacture of
wallboard joint cement is shown below:
Typical Chemical Analysis (Calcium Car-bonate)
CaCO3 Minimum 97-98%
MgCO3 1 %
Acid insoluble 2%
Typical Particle Size Distribution
Retention on 325 mesh screen <1 %
Mean particle size 10 microns
Percentage by weight finer than:
Microns %
44 99 min
20 85
15 70
10 50
5 25
2 13
Typical Physical Characteristics
Dry brightness 92 %
Gallons per pound 0.0445
Pounds per gallon 22.5
Specific gravity 2.71
Moisture less than 0.20%
ph Factor 9.5
Oil absorption 11
Kaolin
Kaolin, also known as kaolin clay or kaolin-ite,
and sometimes referred to as china clay or
aluminum silicate, is a functional filler that is
white, has some hiding power, provides some
strength, and ties up water to control drying. Its
hiding power is a result of the delaminated clay
particles piling up and overlapping. As a filler it
is chemically inert. It also improves spreadabil-ity.
All of the ground kaolin used by southern
California joint cement manufacturers is
shipped from northern California. The cost of
shipping ground kaolin from northern California
to southern California area manufacturers
ranges from $15.00 to $25.00 per ton in truck-load
quantities.
A typical specification for fine ground kaolin
is shown below:
Typical Chemical Analysis
Al203 38.8%
SiO2 45.2%
Na2O 0.05-0.3%
TiO2 0.6-1.7%
CaO 0.02 %
Fe203 0.3-0.9%
MgO 0.03%
K20 0.05-0.2%
Loss on ignition 13.6-14.2%
Typical Particle Size Distribution (Kaolin)
Retention on 325 mesh screen 0.15%
Mean particle size 4.8 microns
(Equivalent spherical diameter)
Percentage by weight finer than:
Microns %
20 99+
10 85
5 50
2 21
Typical Physical Characteristics
Physical Highly pulverized powder
Dry brightness 79-82%
Specific gravity 2.58
Moisture less than 1.0%
ph Factor 3.5-5.0
Oil absorption 30-35
Refractive index 1.56
Bulk density (loose) 24 lbs/cu ft
Bulk density (tamped) 45 lbs/cu ft
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Attapulgite Clay
Attapulgite clay is a gelling clay used as a
thickener and/or thixotropic agent. It provides
sag control, aids in spreadability of the final
product, and the holding of ingredients in sus-pension.
Nearly all of the attapulgite clay used by
Southern California joint cement manufacturers
is imported from the Georgia - Florida area of
the southeastern United States. The cost of ship-ping
attapulgite clay from the southeast U.S. to
Southern California area manufacturers is ap-proximately
$105.00 per ton in truckload
quantities.
Mica
Ground mica is used in joint cement where
its platy structure and high aspect ratio (area:
thickness) provides a number of useful proper-ties.
It prevents packing of the other fillers, adds
strength to the applied layer on the wallboard,
and aids in shrink and cracking control. Mica
for use in joint cement must be white to a very
light tan when ground and free of dark particles
of other minerals. Air ground or micromized
muscovite is most commonly used, but dry
ground sericite or muscovite has been occasion-ally
used. Both muscovite and sericite have been
mined in Southern California in the past for use
in joint cement.
Most of the ground muscovite mica used by
Southern California joint cement manufacturers
is imported from North Carolina. The cost of
shipping ground muscovite mica from North
Carolina to Southern California area manufac-turers
is in the range of $95 to $115 per ton in
truckload quantities.
A typical specification for fine ground mus-covite
mica is shown below:
Typical Chemical Analysis
Theoretical chemical formula H2KAl3(SiO4)3
Typical Physical Characteristics
Color White and lustrous
Particle shape Very thin and platy
Particle size distribution:
+60 mesh nil
-60 + 1 00 mesh 1.5 % max.
-100 +200 mesh. 10.0% min
-325 mesh 50.0% min.
Chemical activity Essentially inert except toH2
Loss on ignition 4-5%
Specific gravity 2.8-3.0
Moisture 0.25%
Oil absorption g/mg 80.0
Refractive index 1.58
Bulk density (apparent loose) 14lbs/cu ft
Hardness (MOHS) 2.5
ph 5.75
Surface area m2/g 6.64
Pyrophyllite
Ground pyrophyllite could be used in joint
cement in the same manner as mica. It is not
currently used by any of southern California's
joint cement manufacturers.
Talc
Talc is less expensive than mica and can re-place
some of the mica in joint cement where it
provides similar properties. Its platy grain struc-ture
helps keep the mixture in suspension and
aids workability.
Most of the ground talc used by Southern
California joint cement manufacturers is im-ported
from Montana, while some is still sup-plied
from central California. The cost of ship-ping
ground talc to Southern California area
manufacturers ranges from $20 to $65 per ton in
truckload quantities depending on whether the
source is central California or Montana.
A typical specification for fine ground talc is
shown below:
Typical Chemical Analysis
Si02 61.5-63.1%
MgO 31.0-32.9%
Al203 0.93-2.37%
CaO 0.19-3.90%
Fe203 1.00-1.30%
K20 0.01-0.13%
TiO2 0.05-6.20%
Loss on ignition 5.50-6.20%
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Typical Particle Size Distribution
Retention on 100 mesh screen nil
Retention on 200 mesh screen nil
Retention on 325 mesh screen 2.0%
Typical Physical Characteristics
Dry brightness 80-84
Specific gravity 2.70
Apparent density 28.7 lbs/cu ft
Tapped density 56.5 lbs/cu ft
Perlite
Perlite is used in a ground, then expanded
form, as a lightweight filler. Bag house fines
from perlite expanding (also called popping)
plants are also used. Perlite used in wallboard
joint cement must be very white when ex-panded.
It is used in place of some of the cal-cium
carbonate.
Gypsum
Gypsum is used by some manufacturers in
the form of plaster of Paris in rapid setting joint
cement.
Diatomaceous Earth (diatomite)
Diatomaceous earth or diatomite is a filler
primarily used in joint cement for its low effec-tive
density in light weight products. Because of
the physical structure of the individual particles
making up diatomaceous earth, they lay in a
random, three-dimensional pattern that stiffens,
reinforces and improves the durability of the
final product. The variety of shapes also pro-vides
low density. The effective density of dia-tomaceous
earth fillers is among the lowest of
any mineral fillers at 1.98 to 2.33 grams per cu-bic
centimeter. Diatomaceous earth occupies up
to 30 percent more volume per pound than most
other filler minerals.
Diatomaceous earth is not currently used by
any of the southern California wallboard joint
cement manufacturers.
Feldspar
White feldspar, if locally available, could re-place
limestone as the primary filler in wall-board
joint cement. Reduced transportation
costs would have to compensate for increased
grinding costs. Southern California’s joint ce-ment
manufacturers do not currently use it.
Wollastonite
Wollastonite could be used in place of some
mica and limestone in wallboard joint cement
where the acicular shape of the ground wollas-tonite
particles would provide many of the same
properties provided by ground mica. It is not
currently used by any of Southern California's
joint cement manufacturers.
Conclusions
Southern California's wallboard joint cement
industry is believed to use the largest quantity of
industrial minerals as fillers of any industry in
southern California. Many of these are currently
imported into southern California, often from
sources much further away than Arizona. Oc-currences
of most of these minerals, in particu-lar,
limestone, mica, kaolin, perlite, pyrophyl-lite,
and diatomaceous earth, are known in Ari-zona.
The consumption of these minerals in
joint cement may be sufficient to justify a spe-cialized
multi-mineral producer operating a
number of mines, each producing a specific
mineral, but utilizing a common grind-ing/
processing plant. Additionally, most of the
same minerals are used in Arizona's joint ce-ment
plants. All have nearly the same specifica-tions
as those used in Arizona's and southern
California's paint industry, although the quanti-ties
used in paint are much smaller. Thus a
multi-mineral producer could produce for more
than one Arizona and southern California indus-try.
Further, southern California is a large mar-ket
for industrial minerals in the manufacture of
other products. It is expected that investigation
of other industries in Arizona and southern Cali-fornia
will yield consumption data that will pro-duce
totals of sufficient quantities to justify de-velopment
of new mines in Arizona.