BIKANER CLAYS
BY
B.C. Bhattacharya
Ceramic Engineer
DEFINATION
Clay is defined as the earthy hydrous alumino silicate formed by decomposition of preferably
feldsohatic materials which do possess the property of plasticity when suitably tempered with
water. R.E. Grim has laid down the following three criteria for any material to be called a clay :
i ) It must be a natural material with plastic properties.
ii) It must have an essential composition of particles of very fine size .
iii) The essential composition of crystalline fragment of minerals should be hydrous
alumino – silicate or to some extent hydrous magnesium silicate.
Identification of the different clay minerals depends very therefore on x-ray diffraction method
and differential thermal analysis (d.t.a.) technique. Also electro-chemical study of clay
suspension, particle size determinations and physical prosperities study od different particle size
fractions (including electron microscopic study) are helpful in this reggae.
From the structural point of view the clay minerals from a complex group of mineral species in
which some from a continuous series with another and the line of demarcation between the two
pieces is often difficult to demarcate. However, three important mineral Is which are common and
fairly distinctive, namely Kaolinite, montmorillonite and illite, can be considered to have been
built up of silica and alumina layer stacked parallel to 'c'axis of the crystal. In Kaolinite whose
structural formation approximate of Si4 Al4 O10(OH)18, there is very little replacement of Si or
Al by other ions within the layers and consequently no charge deficiench need de balanced by
exchangeable ions. Forces between the units are weak and minerals are therefore intrinsically fine
grind and platy.
Montmorillonite is composed of three sheets where the octahedral [Al(OH)6] Aluminate sheetis
sandwiched between two tetrahedral [Si(OH)4] Silica sheets, givig the idealised structural
formula Si8 Al2 O (OH)4nH2O.
In nature there is a range of minerals of the type arising from a wide substitution of Mg2÷, Fe2÷
etc. for Al3÷ in the octahedral position and to a lesser extent from the substitution of Al 3-/- for
tetrahedral Si4÷. The charge deficiency thus produced (negative Charge ) is balanced in part by
the caption which mostly concentrate in the internal basal layer spacing along the 'c' axis. The
individual units are thus held together by electrostatic binding forces which even though stronger
than that present in the case of kaolinite, is not sutticient to prevent of polarised molecules like
water, glycerol etc. resulting in swelling of the lattice.
The micaceous clay minerals (illites) have basically a similar structure as the montmorillonite
group, except, that substitution is mostly in the tetrahedral layer Al 3-/-for Si 4-/- and the
balancing caption is mostly potassium which can simply set in the octahedral socket of the silica
layers. Because of shorter distance of separation of the charge deficient site and the balancing
charge site the inter layer forces are much stronger than in montmorillonite. Consequently
swelling is limited and exchange is more difficult.
Classification:The clay deposits in Bikaner district are located near Shreekolayat, Gurda, Deh, MudhChandi,
Indoka Bala, Kotri, Nal, Suraj-ki-Dhani. Barsingsar etc.
The clay of these places is of sedimentary nature and may be classified as secondary clay. The
mineralogical studies reveal that the chief minaral constituuent is kaolinite having a chemical
compostituent of Al2 O3 2Si O2 2H2 O.The type of impurities in clay is due to the degree and
extent of impurities present in clay of the various deposits. The impurities identified are as fine
silica (quartz), hemetite, iron hydrozide, rutile, undecomposed feldspar,and in Some cases lime
kankers.
This sedimentary kaolinite clay having very large amount of fine particle size even less than 1
micron, very good plastic by hand feeling and verifications complete around 1250ºC with a dull
white colour leads to a commercial classification as ballclay.
The clays available below and above the lignite seam may be classified as fire clay e.g. the clay of
Barsingsar and Gursh Palana where the alumina content in the clay is above 30% lower green
strength as compared to plastic ball clays, and a higher temperature of verifications.
Specifications:
Bureau of
follows:
1.
2.
3.
Indian standard has published various specification on clays. The specifications are as
Specification for plastic clay (ball clays)for ceramic industry (IS : 4589-1979).
Specification for china clay for ceramic industry (SI : 2840-1965)
Specification for light kaolin (IS : 505-1968).
Table - I
Physical requirement for plastic clay for use in Ceramic Industry(4589-1979)
Characteristics
Requirement
Grade I
Grade II
i) Grit content (Residue on 45 micron IS Sieve) 2
3
% by mass (Max)
ii) Particle size distribution % by mass
3
6
iii) Finer than 2 micron (min)
75
65
iv) Water of plasticity % by mass(min)
40
28
v) Atterberg Number (min)
20
15
vi) Dry linear shrinkage (min)
10
10
vii) Maturity on firing at 1350ºC (max)
3
5
viii) Modulus of rupture mass (min)
3.5
3.5
Grade III
9
40
25
10
10
9
3.5
Values of this type of clay are given for material passing through 75 micron IS Sieve.
Table – II
Chemical requirement for plastic clay for use in Ceramic Industry
Characteristics
i)
ii)
iii)
iv)
v)
Loss on lgnition % by mass (Min)
Iron Oxide as Fe2 O3 % by mass (Max)
Titania (TiO2)% by mass (Max)
Iron Oxide & Titania combined
(Fe2 O3 + TiO2) % by mass (Max).
Alumina (Al2 O3)% by mass (Min).
Requirement
Grade I
10.5
1.5
1.5
2.75
Grade II
9.5
2.0
2.0
4.0
Grade III
9.0
2.0
2.0
3.75
30
25
20
Table – III
Specification for china clay for Ceramic Industry (IS-2840-1965)
Characteristics
i)
Fineness (residue on 44 microns IS sieve)
% by wt.(Max).
ii) Loss on ignition % by wt. (min),
iii) Alumina (Al2 O3)% by wt (mm),
iv) Iron Oxide (Fe2 O3) 5 by wt. (max)
v) Titanium oxide (TiO2) by wt. (min).
vi) Oxides of iron (Fe2 O3) & Titania
[TiO2] together % by wt. (max).
vii) Water of plasticity % (min).
viii) Shrinkage, linear :
a)
By shrinkage (110ºC) (max)
b)
Fired shrinkage (at 12 conc)
(max)
Requirement
Grade I
1.0
Grade II
2.0
12.0
30.0
1.0
0.7
1.5
10.5
30.0
1.5
1.5
2.75
22
22
8
18
8
18
Specification of clay (light Kaolin) IS-505-1968:
Grads 1- Suitable for textile & paper industries.
Grads 2- Suitable for Rubber Industry.
Grads 3- Suitable as carrier in insecticide industry.
Grads 4- Suitable as absorbant in pharmaceuticals preparations.
Table – 4
Requirements for light kaolin
Characteristics
i)
ii)
iii)
iv)
v)
vi)
vii)
viii)
ix)
x)
xi)
xii)
xiii)
xiv)
xv)
xvi)
xvii)
Coarse particles % by wt. (max).
Particles larger than 10 microns (gm/ml)(min).
Particles larger than 3 microns (gm/ml) (min).
Grit (%by wt ) max.
Specific gravity at 27ºC .
Loss on drying (% by wt. max.)
Loss on ignition (% by wt. max.)
Matter soluble in water (max.)
Matter soluble in HCl acid % by wt. (max).
Copper (as CuO) % by wt. (max).
Arsenic (as As2 O3)parts per million.
Iron (as Ae2 O3) % by wt. max.
Manganese as (MnO) % by wt. (max).
pH
Oil absorption ml/100 gms.
Sedilmentation volume
Colour reflectance to dlue, light of
wave length 5040 A percent.
Requirement
Grade I Grade II
0.5
0.5
1.008
1.008
1.006
1.006
0.2
1.0
2.5-2.8
2.0
1.0
1.30
14.0
0.5
2.5
2.5
0.007
0.5
1.0
0.013
7-7.5
6-7.5
25-35
To pass the test
80-85
-
Grade III
0.5
1.008
1.006
1.0
1.0
14.0
0.5
1.0
0.5
7-7.5
-
GradeIV
0.5
1.008
1.006
1.5
15.0
3
0.5
7.5
-
TEXT :
Detail studies are conducted on clay samples of each deposit. The testing include, mineralogical
investigation, chemical analysis, levigation characteristic, plastic and dry properties & firing
characteristics.
The following is the test of various clays deposits along with the physico-chemical properties and
there use in different industries.
SURAJ KI DHANI :
The creamish white colour clay associated with ferruginous patches extends for 3 km. The clay
beds are 1 to 2.5meters in thickness It is an occurrence of low grade plastic plastic clay. The
physico-chemical properties areas given below.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
57.94%
27.53%
1.59%
1.86%
0.56%
Physical properties
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
Creamish white
good
20
35.20
5%
Mg O
0.20%
Na2 O
K2 O
L.O.I.
0.20%
0.20%
10.68%
PRIMARY MINERAL
IMPURITIES
USES
6) Vitrification at 1305ºC Colour- Dull 17%
white, complete T.L.S.
at 1400ºC Colour – Greyish, bloating
observed T.L.S.
17%
-
Kaolinite
Fine silica, Hematite & Rutile
This ball caly could be used in making S.W.
pipes.Cold facemica insulation bricks, low vitrification
earthernwaer dobies, etc.
NAL :
Two clay beds associated with silitstone and ferruginous sandstone occur exposed for 300-50m.
strike length. The clay beds are 1.50and 1.70 m. thick highly silty and highly plastic. The reserves
are 0.05 and 0.06 million tons, respectively for 30 m. dip extension, and 0.16 and 0.19 million
tons for 100m. Extension.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
49.08%
32.93%
1.75%
0.31%
1.20%
Mg O
0.60%
K2 O
Na2 O
L.O.I.
0.20%
0.23%
13.25%
PRIMARY MINERAL
IMPURITIES
USES
CHANDI :
Physical properties
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
Dull white
good
20
31
3
6) Vitrification
18.5%
at 1305ºC Colour- Dull white, complete
T.L.S.
at 1400ºC Colour – Dull white, complete 18.5%
T.L.S.
-
Kaolinite
Fines quartz/silt iron & rutile.
This plastic ball clay could find its use in making
earthenware bodies, low tension insulators, in cold face
insulation bricks, in a batch of sanitary ware body etc.
The clay varies upto 8m. in thickness and is estimated to contain 3 million tons of reserves. The
clay deposit near village Chandi is very good in terms of quality. It occurs in an area of about ½
square mile. This clay is soft grayish white possesses a high plasticity. Apart form the tests
conducted by this Ceramic & Ore Dreeing Laboratory, Central Glass& Ceramic Research
Institute, Calcutta also conducted tests.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
51.60%
30.79%
1.76%
2.00%
0.56%
Mg O
K2 O
0.40%
0.49%
Na2 O
L.O.I.
0.76%
11.62%
PRIMARY MINERAL
IMPURITIES
USES
Physical testing
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
white
good
22
32
6
6) Modulus of rupture (green)Kgf/Sqcm 44.8
7) Verifications
17%
at 1305ºC Colour- Creamish white,
fairly vitrified T.L.S.
at 1400ºC Colour –Grey, Completely 18%
vitrified T.L.S.
-
Kaolinite
Fines Silica hematite & retile.
The white ball clay could be used in making low tension
electrical insulator, cream earthen ware, ceramic tiles and
sanitary ware.
GURAH :
A large clay deposit is located near village Gurah. The deposit is very extensive with an average
thickness of about 3 m. The estimated reserve is about 2 million tons. The dull white colour caly
is very good plastic slakes in water readily and has a soapy hand feeling.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
64.32%
20.23%
2.24%
2.33%
0.56%
Physical characterstics
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
Dull white
very good
17
29.2
6
Mg O
0.20%
Na2 O
K2 O
0.40%
6) Verifications
at 1250ºC
L.O.I.
8.82%
at 1305ºC Colour –Grey, Completely 16%
vitrified T.L.S.
PRIMARY MINERAL
IMPURITIES
USES
-
15%
ColourCreamish,fairly
vitrified T.L.S.
Kaolinite
Fines Silica, iron, rutile, & carbonates.
By levigation the carbonate impurities could be removed.
This low grade ball clay could find its use in making sewer
pipes, common art potteries and molding purpose.
DEH :
An extensive deposit of clay is located at village Deh, near Kolayat, distt. Bikaner . The estimated
reserve is about 1.5 milion tons. The clay is white in colour with pinksh specks unevenly
distriduted on the lumps. The clay slakes completely within few few minutes. It is very good
plastic with a soapy by hand feeling.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
56.00%
29.20%
1.60%
1.20%
0.84%
Mg O
0.20%
Physical properties
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
6) Vitrification
at 1250ºC
T.L.S.
at 1350ºC
T. L.S.
L.O.I.
white
very good
20
31.1
6.0%
Dull white with major
amout of vitrification
15%
Grey
colour
with
complete vitrification
16%
10.40%
PRIMARY MINERAL
IMPURITIES
-
Kaolinite
Fines Silica,iron,oxode, titania oxide & minor amount of
lime.
USES
-
This clay can be used for the manufacture of S.W. pipes,
Cold face insulation bricks as filler in soap or detergent. this
may also find suitable for rubber industries.
MUDH :
A large clay deposit is located near village mudh about 5 kms. from shri Kolayatji Railway
Station. The deposit covers an area of about 2.5 sq. km. with an average thickness of about 2.5 - 3
meters. The estimated reserves are about 2 million tons. The clay is white. The slaking
characteristic if the clay is very good. The plastic clay is having very fine particle size.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
Physical properties
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
50.24%
32.01%
1.76%
0.53%
0.56%
Mg O
0.20%
6) Modulus of rupture (green) 68.3
Kg/Sqcm
L.O.I.
12.10%
7) Verifications
at 1250ºC
T.L.S.
at 1305oC
T.L.S.
P.C.E.
PRIMARY MINERAL
IMPURITIES
USES
-
white
good
23
33
7
Dull white with major
amount of verifications
16%
Greysih
complete
verification
19%
Orton cone 30-31( 1650oC
– 1680oC)
Kaolinite
Fines Silica, hematite, minor quantity of lime.
The ball clay as such can be used for the manufacture of
cream earthenware,
low tension electrical insulator.
Vitrified dinner wares, sanitary ware & tiles etc A lot of
work has been carried out on Mudh clay by C.G. & C.R.I.
Calcutta also. Ceramic & Ore Dressing laboratory of the
Deptt. of Mines & Geology investigated the clay in details.
This is geese-I as per the specification of plastic plastic clay
for ceramic industries.
KOTRI :
A good clay deposit occurs near village Katri district Bikaner, it occurs in an area of about ½ sq.
km. with an average thickness of 3 to 5 meters. The approximate estimated reserve is about 15
million tons. The clay slakes in water quickly giving a very good plastic mass. it is white in colour
having few pinkish specks.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
51.60%
32.82%
1.60%
0.68%
0.56%
Physical properties
1) Colour
2) Plasticity by hand feel
3) Atterberg No.
4) % Water of plasticity
5) % Dry linear shrinkage
white
very good
22
31.2
6
Mg O
0.40%
6) Modulus of rupture green
45.7
L.O.I.
10.50%
7) Verifications
at 1305ºC
Colorful white
major
amount of verifications
16%
Colour grey complete
verifications
17%
T.L.S.
at 1400oC
T.L.S.
PRIMARY MINERAL
IMPURITIES
USES
-
-
Kaolinite
Fines silica, hematite, rutile.
The ball clay be used in the manufacture of sanitary ware
cream earthenware, low & high tension electrical porcelain
bodies, a old face mica insulation bricks and potteries. This
is grade-I as per the specification of plastic clay for ceramic
industries.
INDOKA BALA :
There are four clay beds with an averge thickness of 2.5-3 meters. The approximate estimated
reserve is about 2 million tons. This iron stained plastic clay occurs in association with
ferruginous sandstone. The slaking characteristic is moderate having the following properties.
Chemical analysis
Si O2
53.84%
Physical characteristics
1) Colour
Al2 O3
Fe2 O3
Ti O2
Ca O
2) Plasticity by hand feel
3) % Water of plasticity
4) % Dry linear shrinkage
5) Verifications
at 1250ºC
T.L.S.
at 1305oC
29.27%
1.75%
1.24%
1.12%
T.L.S.
Mg O
Na2 O
K2 O
0.40%
0.20%
0.80%
Dull white
specks
good
31.0
6.0
with
pinkish
Colour grey with vitrified
14%
Colour grey with complete
verification
16%
L.O.I.
10.30%
PRIMARY MINERAL
IMPURITIES
USES
-
Kaolinite
Fine silica, iron oxide retile & minor amount of carbonates.
The clay is suitable for manufacture of sewer pipes, cold
face mica insulation bricks and calcimined clay can be used
as possolana material. This is as per grade II plastic clay for
ceramic use. This clay can be used by blending with other
good quality's clay.
PALANA :
The fire clay is 0.60 to0.90meter thick occurring below the lignite at depths varying from 39 to 76
meters. It is plastic. The estimated reserve is about two million tons. The fire clay can be removed
by scrapping the over burden which will also expose the lignite seam underneath. It is blackish
grey in colour good plastic and slaking characteristics.
Chemical analysis
Si O2
Al2 O3
Fe2 O3
Ti O2
Ca O
Physical properties
1) Colour
2) Plasticity by hand feel
3) % Water of plasticity
4) % Dry linear shrinkage
5) Verification
at 1305ºC
59.24%
25.40%
1.25%
0.34%
-
at 1400oC
blackish grey
good
29
4
Colour brownish white fairly
vitrified
Colour
brownish
white
complete verification
Orton cone 31
P.C.E.
Mg O
Na2 O
K2 O
L.O.I.
0.30%
0.40%
0.90%
12.28%
PRIMARY MINERAL
IMPURITIES
USES
-
Kaolinite
Fine sillica, iron oxide & hydroxide.
This fire clay is suitable for manufacture of fireclay bricks
(IS-6). It is also suitable for manufacture of saggars and kiln
furniture,
It can be used for manufacture of SW pipes insulation
bricks etc.
BARSINGHSAR :
Studies on clay sample encountered in the boreholes of Barsingsar area have been conducted in
the departmental ceramic & Ore Dessing laboratory. It occurs with an average thickness of 0.5
mts. to 0.8 mts. at the verious depth of 30 meter to 120 meters. This fire clay is having the
impurities of fine silica and in some cases minor quantiy of carbonates. The Plasticity is good.
The aveage chemical analysis of crude and washed clay are given below.
Chemical analysis
Crude
Si O2 56.98%
Al2
28.16%
O3
Fe2
2.40%
O3
Ti O2 0.80%
Ca O 0.56%
Mg O 0.40%
Na2 O 0.67%
Physical properties
Washed
45.60%
35.83%
1) Colour
2) Plasticity by hand feel
dull white
good
1.28%
3)Atterberg No.
23
0.48%
0.28%
0.20%
0.20%
4) % Water of plasticity
5) % Dry linear shrinkage
6) Modulus of rupture green
Vitrification
at 13050C
38
6
53.2Kg/Sq.Cm.
T.L.S.
at 14000C
T.L.S.
K2 O
L.O.I.
0.84%
9.20%
Colour dull white with major
amount of vitrification
17%
Colour creamish Complete
vitrification
20%
0.24%
11.92%
PRIMARY MINERAL
IMPURITIES
LEVIGATION
CHARACTERISTICS
-
Kaolinite
Fine sillica, iron oxide & minor amount of carbonates.
(i)
it slakes moderately. The plasticity of the clay is
good.
(ii)
On an average the effective recovery of good grade
clay varies from 36% to 58.5%
USES
-
This fire clay is suitable for manufacture of fireclay bricks
(IS-6). It is also suitable for manufacture of saggars and
kiln furniture,