Green molded product containing asbestos tailings suitable for firing

There is disclosed a green moulded product suitable for preparing shaped fired units comprising (a) at least 55% to 99% by weight of non-calcined asbestos tailings, the remainder comprising (b) at least one of (i) a heat decomposable metal salt selected from sodium, potassium, lithium, calcium, barium, magnesium, aluminum and mixtures thereof in an amount of from 1% to 15% by weight, (ii) a natural aluminum silicate in an amount of from 1% to 30% by weight, and (iii) mixtures of (i) and (ii). The properties of fired units are such that they can be used as structural bricks, medium refractory bricks, firebricks, tiles and the like.

INTRODUCTION 
The present invention relates to a green moulded product and to a shaped 
fired unit obtained therefrom using asbestos tailings as the major 
ingredient. The properties of the resulting units are such that they can 
be used for making structural bricks, medium refractory bricks, 
firebricks, tiles and the like. The exposed surfaces of the green units 
can also be glazed or engobed before firing to improve decorative effects. 
BACKGROUND OF THE INVENTION 
In the structural clay and refractory industries capable of mass 
production, ceramic units are either made by the extrusion or the pressing 
process. Extrusion is preferred when dealing with plastic raw materials, 
whereas pressing is rather used to agglomerate non-plastic materials. The 
process in making these products consists in quarrying the clay, milling 
and grinding the same. Then, the clay is cleared of stones and extruded in 
pug mills. When using non-plastic clays, plasticizers can be added to the 
mixture before extrusion, or the shaped units can be made by pressing. The 
resulting units are dried and finally fired. As the temperature of firing 
increases beyond red heat, vitrification occurs. 
Vitrification is the hardening, tightening and finally the partial fusing 
of clay. Clays vitrify at various temperatures depending upon their 
composition. A common red clay, for example, which as a high iron content 
and other mineral impurities, may be fired to hardness and density at 
about 1000.degree. C. and may melt to a liquid at about 1250.degree. C. 
More refractory clays fire somewhere between 1000.degree. and 1250.degree. 
C. A well-fired piece of clay is characterized by hardness, great 
compressive strength, high density, impermeability and by a very large and 
easily controlled variety of color and texture which is reminiscent of the 
variety in the earthy materials of the landscape. When the compressive 
strength is higher than 20 MPA, and water absorption lower than 18%, the 
units can be used as building blocks. If water absorption is lower than 
5%, the units can be used as quarry or paver tiles, according to the 
American specification ANSI A1-37, 1-1980 or the Canadian equivalent 
specification CAN2-75.1-M77. 
It is also known that serpentine, more particularly chrysotile asbestos 
tailings, contains the constituents of olivine, that is magnesium oxide, 
silicon dioxide and ferric oxide, though in different proportions. It is 
also known that there is an enormous amount of chrysotile asbestos 
tailings and residues in countries where asbestos mining is carried out to 
a large extent, so that it would appear that great advantages could be 
derived if a satisfactory method could be found to modify or convert the 
plentiful asbestos tailings into sintered moulded units, having properties 
equivalent to commercial ceramic bodies made from clays. 
Asbestos tailings have a low commercial value and the appropriate 
granulometry is already available for pressing. Accordingly, quarrying, 
milling, grinding and cleaning raw materials which are required for clays, 
are not required when dealing with asbestos tailings. However, since the 
tailings are more refractory than clays, they sinter at a much higher 
temperature. 
Accordingly, it would appear highly desirable if asbestos tailings could be 
sintered at as low a temperature as possible whereby the energy cost would 
be substantially reduced while still obtaining sintered units of the same 
quality level as those of standard clay products. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a green moulded 
product containing from 55 to 99% by weight of asbestos tailings which can 
be actively sintered between 1100.degree. and 1300.degree. C., in such a 
way that the resulting sintered units have properties equivalent to and in 
some case even better than the standard clay products commercially used. 
The sintered moulded units of the present invention are characterized by 
being asbestos-free, by having good compressive strength, low water 
absorption, and low coefficient of saturation. Furthermore, the fired 
units of the present invention are such that units are obtained where 
shrinkage, warpage and wedging can be closely controlled. 
The present invention comprises the preparation of green moulded units made 
up of a compressed mixture of from 55 to 99% by weight of non-calcined 
asbestos tailings and 45 to 1% by weight of at least one of the following: 
(i) from 1 to 15% by weight of a heat decomposable salt of a metal selected 
from sodium, potassium, lithium, calcium, barium, magnesium and aluminum; 
or 
(ii) from 1 to 30% by weight of a natural aluminum silicate; or 
(iii) a mixture of (i) and (ii) in the respective amounts indicated. 
The green moulded units of the present invention are then sintered at a 
temperature of from 1100.degree. to 1300.degree. C. for a period of from 2 
to 4 hours to yield a new fired compacted moulded unit characterized by a 
water absorption of less than 18%. The fired units are made up of calcined 
granules of asbestos tailings and a chemical bond binding the granules 
together. The chemical bond is represented by a mixture of MOSiO.sub.2 and 
MgO wherein MO stands for any of Na.sub.2 O, K.sub.2 O, Li.sub.2 O, CaO, 
BaO, MgO and Al.sub.2 O.sub.3 and mixtures thereof. Finally, the fired 
units of the present invention possess advantageous physical properties as 
will be seen later. 
These objectives are obtained by making new compacted moulded units 
comprising a fired mixture of asbestos tailings with a binder which is a 
heat decomposable salt of a metal selected from sodium, magnesium, 
lithium, potassium, calcium, barium and aluminum, the amount of binder 
being from 1 to less than 15% by weight. The binder may also be a natural 
aluminum silicate in an amount of from 1 to 30% by weight. Also a mixture 
of a heat decomposable metal salt as defined previously in an amount of 1 
to 15% by weight and a natural aluminum silicate in an amount of from 1 to 
30% by weight can also be used as the binder. The green units are obtained 
by compacting the asbestos tailings and the selected binder at a pressure 
of from 3000 to 5000 psi and then fired at temperatures of from 
1100.degree. to 1300.degree. C., for 2 to 4 hours. If desired extrusion 
under vacuum can also be used to prepare the green moulded units. 
Uncalcined asbestos tailings taken directly from any asbestos mine are 
used to make the units of the present invention. 
In general, for a given compacting pressure and sintering temperature, the 
strength obtained on sintered units containing a binder is higher than 
that obtained without binder, and the water absorption is lower. 
It has been found that a wide variety of compositions can be used to make 
structural bricks, firebricks as well as medium refractory bricks, but for 
floor tiles and the like, sodium chloride appears to be the best binder to 
get the required properties. 
ADVANTAGES OF THE SINTERED UNITS 
The sintered units containing at least 55% asbestos tailings offers many 
advantages. There are: 
1. The cost of uncalcined asbestos tailings containing serpentine is quite 
competitive with clays since the cost of quarrying, crushing and grinding 
has already been absorbed in the pricing of the asbestos fibers. 
2. The sintered units do not contain asbestos fibers. Indeed, serpentine 
decomposes during the firing process, losing the water of crystallization 
at about 700.degree. C. and being transformed into a ceramic body at about 
800.degree. C. Forsterite and enstatite are then formed. 
3. The decomposition of the uncalcined asbestos tailings during the 
sintering process creates new surfaces between grains in contact and 
accelerates the sintering process. This is a remarkable advantage over 
pre-calcined tailings which are not so active during sintering. 
4. Addition of 5 to 8% water is required to make sound green compact with 
uncalcined tailings. This amount is about twice as low as that required 
for precalcined tailings. 
5. The addition of binder makes the sintering process of uncalcined 
asbestos tailings very attractive, because they can be sintered to high 
density at temperatures similar to those used to vitrify clays. 
Consequently, less energy is required to sinter the mass, furnace linings 
will have a longer life and maintenance cost for operating such furnaces 
will be considerably lower than those expected to densify this type of 
refractory material. 
6. Compacting pressures between 3000 and 5000 psi used to make the units 
are well within the limits of standard presses for mass production. 
7. Glazing or engobing compounds can be directly applied to the green 
unfired units. The compounds adhere very easily to the surface of the 
units during the sintering and glazes are formed without crazing. 
Accordingly, glazed tiles can be obtained in a single firing step thus 
rendering the products of the present invention commercially attractive. 
8. Although linear shrinkage takes place during sintering, close tolerance 
of the sintered moulded units can be maintained.

DETAILED DESCRIPTION 
More specifically, the present invention provides novel fired units by 
mixing asbestos tailings with a metal salt binder and/or a natural 
aluminum silicate and firing same at temperatures of from 1100.degree. to 
1300.degree. C. It has been found that in the sintering process, the 
asbestos tailings decompose to granules of forsterite and enstatite bonded 
together at their outside surface by a chemical bond derived from the 
binder. 
ASBESTOS TAILINGS 
The asbestos tailings or residues used in the present invention are those 
normally found next to asbestos mines after the asbestos fibers have been 
extracted from the mined asbestos rock. In most cases, the particle size 
is less than about 28 mesh (U.S. standard). If desired the asbestos 
tailings can be submitted to grinding to reduce the size to from 100 to 
400 mesh (U.S. standard). 
The asbestos tailings or residues can be used as such. Depending on the 
color desired in the end product the iron-rich or iron-depleted fraction 
obtained from a magnetic separation process will be used. When using the 
iron-rich fraction of asbestos tailings, the color of the end product will 
vary from dark brown to black. On the other hand when using the 
iron-depleted fraction of asbestos tailings the color of the end product 
will vary between various shades of light brown. 
The amount of asbestos tailings or residues used in accordance with the 
present invention will vary from 55 to 99% by weight of the total 
ingredients used in making up the green moulded product which will be 
subjected to firing. 
BINDER 
The binder used in accordance with the present invention is a heat 
decomposable chloride salt of a metal selected from sodium, potassium, 
lithium, calcium, barium, aluminum and magnesium or a natural aluminum 
silicate or a mixture of both. 
As heat decomposable metal salt of a metal selected from sodium, potassium, 
lithium, calcium, barium, magnesium and aluminum there is used the 
chloride salt. Also there can be used a mixture of heat decomposable 
salts. The amount of such salt varies from 1 to 15% by weight. 
As an example of natural aluminum silicates which can be used in accordance 
with the present invention there may be mentioned: kaolinite (Al.sub.2 
O.sub.3, 2SiO.sub.2, 2H.sub.2 O), halloysite (Al.sub.2 O.sub.3, 
2SiO.sub.2, 4H.sub.2 O), pyrophillite (Al.sub.2 O.sub.3, 4SiO.sub.2, 
H.sub.2 O), mica (KAl.sub.3 Si.sub.3 O.sub.10 (OH).sub.2), potassium 
feldspath (K.sub.2 O, Al.sub.2 O.sub.3, 6SiO.sub.2), sodium feldspath 
(Na.sub.2 O, Al.sub.2 O.sub.3, 6SiO.sub.2), nepheline syenite (0.25K.sub.2 
O, 0.75Na.sub.2 O, 1.11Al.sub.2 O.sub.3, 4.65SiO.sub.2), custer feldspath 
(0.69K.sub.2 O, 0.31Na.sub.2 O, 1.05Al.sub.2 O.sub.3, 7.05SiO.sub.2), 
sillimanite (Al.sub.2 O.sub.3, SiO.sub.2), spodumene (Li.sub.2 O, Al.sub.2 
O.sub.3, 4SiO.sub.2) or petalite (Li.sub.2 O, Al.sub.3 O.sub.3, 
8SiO.sub.2). 
As natural aluminum silicate there may be also used the aluminum 
silicate-bearing clays which are well known in the ceramic art. The 
natural aluminum silicates are used in an amount varying from 1 to 30% by 
weight. 
As binding agent there may also be used a mixture of the above-mentioned 
heat decomposable metal salts with a natural aluminum silicate. When using 
such a mixture the amount used in the composition will vary from 1 to 45% 
by weight. 
GREEN MOULDED UNITS 
In order to prepare the green moulded units, the heat decomposable binder 
is dissolved in water and the asbestos tailings or residues are added and 
mixing is continued until a wet powder is obtained which is then compacted 
in a double action press at a pressure of from 3000 to 5000 psi. The 
resulting green compacted units thus obtained are strong enough to be 
handled or transported on conveyors without cracking. On the other hand, 
whenever a natural aluminum silicate is used it is first dry mixed with 
the asbestos tailings and the mixture is wetted with water when the 
silicate is used as the sole binding agent or an aqueous solution of the 
heat decomposable metal salt when the binder is to consist of a mixture of 
natural aluminum silicate and heat decomposable metal salt. 
More specifically, for example, to prepare a wet powder mixture containing 
3% dry weight of sodium chloride and 97% of asbestos tailings, 3 gr of 
sodium chloride are dissolved in about 8.5 cc of water and then 97 g of 
asbestos tailings are added. After thorough mixing the wet powder obtained 
has a humidity content of from 5 to 8%. The humidity should not be higher 
than 8% when pressing is used and should be at the lowest possible 
percentage when extrusion is used in order to avoid loss of binder when a 
water-soluble binder is used. 
FIRING STEP 
The green moulded units of the desired shape are strong enough to be 
handled or transported without crumbling or cracking. The units are then 
preferably dried at about 110.degree. C. and fired for 2 to 4 hours at 
temperatures varying between 1100.degree. and 1300.degree. C. The heat 
cycle can vary from 10 to 12 hours. The time required to arrive at the 
sintering or firing temperature is about 4 hours, after which the firing 
or sintering temperature is maintained for a period of 2 to 4 hours, after 
which the sintered or fired units are permitted to cool for a period of 
about 4 hours. 
The cycle just described is similar to thermal cycles used in standard 
tunnel kiln operations. 
It is also possible to carry out the firing in a reducing or oxidizing 
atmosphere as is well known in the art. When operating in a reducing 
atmosphere, the resulting units are stronger than those sintered or fired 
in an oxidizing atmosphere. 
FIRED UNITS 
In general, the properties of the fired units prepared in accordance with 
the present invention will vary with the compacting pressure applied to 
the green product, the amount of binder used, the particle size 
distribution of the asbestos tailings used, the sintering temperature and 
atmosphere. Generally speaking, the fired units of the present invention 
have the following physical properties within the ranges shown: 
______________________________________ 
linear shrinkage 5 to 13% 
loss on ignition 10 to 23% 
coefficient of saturation 
0 to 0.85% 
water absorption 0.05 to 17% 
compressive strength 
18 to 150 MPA 
(2,000 to 22,000 psi) 
abrasion resistance index 
&gt;50 
resistance to freezing 
excellent 
and thawing 
______________________________________ 
The fired units of the present invention are also characterized by being 
asbestos-free. 
MOULDED SHAPES 
The products of the present invention can be moulded in the shape of tiles 
for various industrial uses. For example, ceramic tiles prepared according 
to the present invention can be used wherever an acid resistant surface is 
required such as, for example, inside tank linings for the paper industry 
where the water absorption must be less than 4% and the weight loss less 
than 8% according to the ASTM C-279 acid test. Suitable floor tiles where 
the water absorption must be less than 3% can also be prepared in 
accordance with the present invention. 
In another aspect of the present invention, moulded fired units having 
different physical properties for different uses can be obtained by simply 
humidifying asbestos tailings, shaping same and firing thus avoiding the 
use of a binder. 
The present invention will be more fully understood by referring to the 
following Examples which illustrate the invention. 
EXAMPLES 
The amounts of asbestos tailings and in the size indicated are mixed with a 
solution containing up to 15% by weight of the selected heat decomposable 
salt. The total amount of water in the final mixture is about 8%. The wet 
powder is then compacted in a double action mould at the indicated 
pressure to provide green cylindrical units having 2" in diameter by 4" 
high. These units are dried at 110.degree. C. for a period of 24 hours 
after which they are fired in an intermittent gas furnace at the shown 
temperature for a soaking time of 4 hours at the maximum temperature. 
When using a natural aluminum silicate, it was dry mixed the asbestos 
tailings and then wetted to provide a mix having from 5 to 8% humidity. 
Finally when using a mixture of metal salt and natural aluminum silicate, 
the latter was dry mixed with the asbestos tailings and then wetted with 
an aqueous solution containing the metal salt, the amount of water being 
such as to obtain a final humidity of from 5 to 8% by weight. The 
respective ingredients, amounts, moulding pressure and firing temperature 
are shown in the following Examples. Each results shown is computed from 
an average of 5 samples. 
EXAMPLE 1 
Results with sodium chloride as binder at different compacting pressure and 
at a constant temperature. 
This example shows the results with sodium chloride as binder on the 
sintering behaviour of asbestos tailings. The samples are made in the 
following manner: 
raw material: -28 mesh uncalcined and non demagnetized asbestos tailings 
binder: 0 to 5% of NaCl 
compacting pressure: 3000 to 5000 psi 
sintering temperature and time: 4 h at 1250.degree. C. 
sintering atmosphere: reducing 
Results are shown in Table I: 
TABLE I 
______________________________________ 
H.sub.2 O 
weight percent 
L.S. L.O.I. Ksat abs. C.S. 
of NaCl % % % % MPA 
______________________________________ 
A: compacting pressure: 3000 psi 
0 8.17 11.49 0.65 12.01 
61.13 
1 9.26 12.04 0.6 10.89 
80.80 
2 10.25 12.67 0.57 9.88 86.60 
3 12.09 13.66 0.51 8.77 88.65 
4 12.04 13.99 0.42 7.99 99.47 
5 11.82 14.60 0.29 6.60 110.32 
______________________________________ 
B: compacting pressure: 4000 psi 
0 8.98 11.08 0.56 10.34 
73.08 
1 9.32 11.60 0.46 7.80 89.43 
2 11.60 12.32 0.35 4.90 92.54 
3 12.08 13.25 0.22 1.95 108.33 
4 12.03 13.45 0.29 0.63 99.43 
5 11.11 14.27 0.27 0.94 80.10 
______________________________________ 
C: compacting pressure: 5000 psi 
0 9.3 10.85 0.51 9.48 99.74 
1 9.96 11.57 0.39 6.92 112.58 
2 11.48 12.27 0.44 2.89 147.94 
3 12.14 12.87 0.45 1.75 132.70 
4 11.57 13.27 0.55 0.25 144.43 
5 10.17 13.74 0.44 0.48 124.87 
______________________________________ 
L.S.: linear shrinkage 
L.O.I.: loss on ignition 
Ksat: coefficient of saturation 
C.S.: compressive strength 
EXAMPLE 2 
Results with sodium chloride as binder at different sintering temperature 
and at a constant pressure. 
This example shows the results with sodium chloride as binder on the 
sintering behaviour of asbestos tailings for a given compacting pressure. 
The samples are made in the following manner: 
raw material: -28 mesh uncalcined and non demagnetized asbestos tailings 
binder: 0 to 5% NaCl 
compacting pressure: 4000 psi 
sintering time and temperature: 4 h at temperatures of from 1150.degree. to 
1300.degree. C. 
sintering atmosphere: reducing 
Results are shown in Table II: 
TABLE II 
______________________________________ 
H.sub.2 O 
weight percent 
L.S. L.O.I. Ksat abs. C.S. 
of NaCl % % % % MPA 
______________________________________ 
A: sintering temperature: 1150.degree. C. 
0 6.08 11.02 0.77 15.23 
12.07 
1 5.99 11.14 0.72 14.17 
16.7 
2 6.50 11.72 0.70 14.09 
24.87 
3 7.34 12.91 0.66 13.5 30.32 
4 7.16 13.02 0.60 13.21 
35.50 
5 7.62 13.82 0.60 14.06 
43.61 
______________________________________ 
B: sintering temperature: 1200.degree. C. 
0 7.68 10.90 0.67 12.07 
46.93 
1 8.66 11.34 0.64 11.16 
55.10 
2 9.43 11.58 0.59 10.07 
81.58 
3 9.51 12.01 0.55 9.53 93.53 
4 10.33 12.69 0.46 9.14 105.40 
5 10.26 13.59 0.41 9.19 87.08 
______________________________________ 
C: sintering temperature: 1250.degree. C. 
0 8.98 11.08 0.56 10.34 
73.08 
1 9.32 11.60 0.46 7.80 89.43 
2 11.60 12.31 0.35 4.90 82.54 
3 12.08 13.25 0.26 1.95 108.33 
4 12.02 13.45 0.29 0.63 99.43 
5 11.11 14.27 0.27 0.94 80.10 
______________________________________ 
D: sintering temperature: 1300.degree. C. 
0 10.79 11.36 0.68 1.39 149.66 
1 8.78 11.83 0.62 0.81 129.5 
2 9.81 12.40 0.47 0.66 151.66 
3 9.25 13.08 0.17 0.42 140.20 
4 9.69 12.77 0.38 0.17 119.27 
5 9.62 14.30 0.43 0.86 119.53 
______________________________________ 
EXAMPLE 3 
Results with different types of binders on sintering of asbestos tailings. 
These examples show the results of the type of binder on the sintering 
behaviour of asbestos tailings. The samples are made in the following 
manner: 
raw material: -28 mesh uncalcined and non demagnetized asbestos tailings 
binder: 4% by weight 
compacting pressure: 4000 psi 
sintering time and temperature: 4 h at 1250.degree. C. 
sintering atmosphere: reducing 
Results are shown on Table III: 
TABLE III 
______________________________________ 
H.sub.2 O 
Type of binder 
L.S. L.O.I. Ksat abs. C.S. 
4% by weight 
% % % % MPA 
______________________________________ 
NaCl 12.02 13.45 0.29 0.63 99.43 
KCl 13.15 13.27 0.33 5.33 81.96 
LiCl 11.88 15.67 0.54 0.98 78.81 
MgCl.sub.2.6H.sub.2 O 
9.30 12.37 0.49 9.60 75.41 
CaCl.sub.2 10.11 14.99 0.50 1.36 98.06 
BaCl.sub.2 11.68 12.04 0.34 4.15 74.49 
NaCl/AlCl.sub.3 (ratio, 
6.47 11.53 0.44 10.33 85.97 
55/45) 
______________________________________ 
It appears from these results that better results are obtained from sodium 
chloride which is also the cheapest of the salts used. 
EXAMPLE 4 
Results with sodium silicate as binder. The samples are made in the 
following manner: 
raw material: -28 mesh uncalcined and non demagnetized asbestos tailings 
binder: 3.5% sodium silicate type N. 
compacting pressure: 4500 psi 
sintering time and temperature: 2 h at from 1100.degree. to 1250.degree. C. 
Results are shown in Table IV: 
TABLE IV 
______________________________________ 
H.sub.2 O 
Temperature 
L.S. L.O.I. Ksat abs. C.S. 
.degree.C. 
% % % % MPA 
______________________________________ 
1100 6.1 11.6 0.8 16.4 14 
1150 7.0 12.5 0.75 15 18 
1200 7.1 11.3 0.68 12.4 37 
1250 8.5 11.8 0.57 10.5 88 
______________________________________ 
EXAMPLE 5 
Results with a mixed binder comprising 3% NaCl+4% MgCl.sub.2.6H.sub.2 O. 
The samples are made in the following manner: 
raw material: -28 mesh, uncalcined and non demagnetized asbestos tailings 
binder: 7% (3% NaCl, 4% MgCl.sub.2) 
compacting pressure: 4500 psi 
sintering time and temperature: 2 h at from 1100.degree. to 1250.degree. C. 
Results are shown in Table V: 
TABLE V 
______________________________________ 
H.sub.2 O 
Temperature 
L.S. L.O.I. Ksat abs. C.S. 
.degree.C. 
% % % % MPA 
______________________________________ 
1100 6.4 15.5 0.75 16.1 18 
1150 7.1 14.1 0.73 16.5 26 
1200 8.8 14.0 0.66 13.2 43 
1250 10.7 14.0 0.60 9.8 100 
______________________________________ 
EXAMPLE 6 
Results with 14% magnesium chloride as binder. The samples are made in the 
following manner: 
raw material: -28 mesh uncalcined and non demagnetized 
binder: 14% MgCl.sub.2.6H.sub.2 O 
compacting pressure: 4000 psi 
sintering time and temperature: 2 h at from 1100.degree. to 1300.degree. C. 
Results are shown in Table VI: 
TABLE VI 
______________________________________ 
H.sub.2 O 
Temperature 
L.S. L.O.I. Ksat abs. C.S. 
.degree.C. 
% % % % MPA 
______________________________________ 
1250 12.42 22.4 0.54 9.3 72.84 
______________________________________ 
EXAMPLE 7 
Results with 20% clay as binder. 
The clay used contains 55% SiO.sub.2, 20.5% Al.sub.2 O.sub.3, 3.7% MgO, 6% 
alkalis, 5% Fe.sub.2 O.sub.3. The loss on ignition is about 6% and total 
other elements is about 4%. The samples are made in the following manner: 
raw material: -28 mesh uncalcined and non demagnetized 
binder: 20% clay 
compacting pressure: 4000 psi 
sintering time and temperature: 4 h at 1250.degree. C. 
Results are shown in Table VII: 
TABLE VII 
______________________________________ 
H.sub.2 O 
Temperature 
L.S. L.O.I. Ksat abs. C.S. 
.degree.C. 
% % % % MPA 
______________________________________ 
1250 5.69 7.63 0.41 7.59 114.72 
______________________________________ 
EXAMPLE 8 
Fired units were prepared using asbestos tailings as mined and the iron 
depleted fractions from various asbestos mine along with a variety of 
binders and in various amounts. Each sample was pressed at 4000 psi and 
fired at 1250.degree. C. for 4 hours. The results are shown in Table VIII: 
TABLE VIII 
__________________________________________________________________________ 
Those samples were pressed at 4000 PSI and fired at 1250.degree. C. for 4 
hours. 
Iron depleted fraction as mined 
Location and 
% Absorp- % Absorp- 
particules 
Tail- 
% % tion Linear Tail- 
% % tion Linear 
size ings 
Nephel* 
NaCl 
water 
shrink 
Color ings 
Nephel* 
NaCl 
water shrink 
Color 
__________________________________________________________________________ 
Lac d'amiante 
100 
.0. .0. 11.0 7.6 Buff 100 
.0. .0. 11.0 6.7 Dark 
du Quebec Ltee buff 
Location R 2 
35 mesh 85 15 .0. 7.5 6.7 Buff 85 15 .0. 5.3 6.7 Rusty 
brown 
80 20 .0. 3.7 6.9 -- 80 20 .0. 6.1 7.0 -- 
75 25 .0. 5.9 5.16 
Beige 75 25 .0. 8.13 6.06 -- 
speckled 
98 .0. 2 11.0 7.2 Beige 98 .0. 2 11.5 6.07 Rusty 
speckled 
83 15 2 6.0 7.0 Light 83 15 2 4.3 6.5 Rusty 
grey brown 
78 20 2 1.7 6.5 Grey 78 20 2 2.5 6.1 Grey 
brown 
Bell Asbestos 
Ltee 
28 mesh 100 
.0. .0. 8.3 7.3 Dark 
brown 
" 95 5 .0. 5.6 7.4 Dark 
brown 
" 93 5 2 1.3 6.9 Brown 
200 mesh 98 .0. 2 0.05 11.1 Dark 
brown 
93 5 2 0.65 7.4 Dark 
brown 
Carey Canadian 
100 
.0. .0. 10.1 10.1 
Buff 100 
.0. .0. 8.8 8.90 Dark 
Inc. buff 
48 mesh 
Carey Canadian 
85 15 .0. 6.3 9.9 Grey with 
85 15 .0. 4.8 9.86 Rusty 
Inc. black 
48 mesh speckles 
Carey Canadian 
80 20 .0. 5.1 8.9 Light 80 20 .0. 5.7 8.15 Rusty 
Inc. buff 
48 mesh 
Carey Candian 
75 25 .0. 4.3 7.6 Light 75 28 .0. 6.0 8.07 Dark 
Inc. beige beige 
48 mesh 
Carey Canadian 
98 .0. 2 9.5 9.23 
Off white 
98 .0. 2 8.5 9.23 Dark 
Inc. speckled buff 
48 mesh 
Carey Canadian 
83 15 2 4.9 9.43 
Off white 
83 15 2 3.5 9.66 Light 
Inc. speckled ash 
48 mesh 
Carey Canadian 
78 20 2 1.95 8.50 
-- 78 20 2 1.40 8.52 Rusty 
Inc. 
48 mesh 
Lac d'aminate 
du Quebec Ltee 
Location S 12 
35 mesh 100 
.0. .0. 12.3 7.2 Beige 100 
.0. .0. 12.1 7.3 Rusty 
85 15 .0. 7.7 6.7 Buff 85 15 .0. 4.6 7.2 Brown 
80 20 .0. 5.3 6.5 -- 80 20 .0. 3.7 7.6 Brown 
75 25 .0. 2.9 5.4 Buff 75 25 .0. 4.3 N/A -- 
98 .0. 2 11.7 6.5 Light 98 .0. 2 11.05 6.7 Rusty 
buff 
83 15 2 5.5 7.6 -- 83 15 2 4.1 8.1 Brown 
78 20 2 1.5 6.5 Light 78 20 2 1.8 5.4 Dark 
beige brown 
73 25 2 0.5 5.62 
-- 73 25 2 1.6 5.6 Light 
brown 
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*The term "nephel" used in Table VIII means nepheline syenite