Status of Wollastonite Mining in IndiaR.P VIJAY VERGIA,

GEOLIGIST

MINES AND DEPARTMNET, UDAIPUR

1 Introduction:

The Year 1968 was the land mark in the mineral history of India when the mineral

wollastonite was first reported in the Sirohi district of Rajasthan in Khila area. Discovery

of this Mineral in Rajasthan has added one more feather in this crown Rajasthan has pride

in having the entire production of wollastonite of the country which is being production

of wollastonite of the country which is being produced by M/s Wolkem Private Limited

from their Belka Pahar mines near village Khila.

The production of wollastonite has risen upto 35421 tonnes during the year 1988

against 5790 tonnes in the year 1980 The Indian Wollastonite has gained importance in

the market by export of 352 tonnes of mineral during the year 1978-79 which has gone

upto 8800 tonnes during the year 1986-87. The mineral has exported to different

countries such as Nether- land, Japan m Australia, Germany, Italy and United Kingdom.

Besides Rajasthan, Occurrence of this minerals have also been reported from

Banaskanta district of Gujrat and Dharmapuri and Triundveli district of Tamil Nadu.

Recently occurrences of wollastonite have also been located in Ajmer district by State

Department of Mines and Geology but these are not sufficient of meetout the increasing

future industrial demand. To cope up with the increasing demand, intensive search in

remote areasing geological favourable environment is needed.

2. Chemical Composition:

Wollastonite is a naturally occurring calcium Meta silicate (CaSiO3) was named

after the British mineralogist and chemist William Hyde Wollastone (1766-1826)

Wollastonite has the theoretical od 48.3% Ca O and 51.7% SiO2 although in nature iron,

magnesium or manganese often subscribe for the calcium component. The mineral is

usually found as an aggregate of white bladed or needle like crystals with a vitreous to

pearly lusture. It has hardness of 4.5 to 5, specific gravity of 2.87 to 3.09 and melting

point of about 1500° C.

3. Mode of Occurrence:

Wollastonite is a skarn mineral occurs in areas where siliceous limestones have

been subjected to regional metamorphism or local igneous activity. The other minerals

often associated within this geological environment are diopside, tremolite, idocrasc,

grossularite and andradite garnet. The main components are calcium and andradite

garnet. The Main components are calcium and silica as well as material like magnesia

and alumina as impurities, which are derived from the original rock or brought in by

igneous agencies.

Free quartz and calcite are also very common in this environment. In Rajasthan

Wollastonite deposits are found in skarns (of Delhi Super Group) Where granites are

intruded in impure limestone.

4. Commercial Utilistion:

The use of wollastonite depends on accicularity or the aspect ratio i.e. ratio

between length and width of a crystal. The low aspect ratio in the range of 1.3 to 1.5 has

little potential and applications are confined to ceramic, metallurgical, flux and filler.

Wollastonite with a higher aspect ratio in the of 1:15 to 1:20 is considered as semi-

fibrous replacement rang of asbestos, strengthing the various plastic and resin.

Wollastonite has become an important function filler in a number of products

including plastics, paint, ceramics, adhesive, sealants, reasins, bounded, abrasives wall

boards, insulating, materials and going to replace asbestos in number of industries.

The property of its low thermal expansion makes it suitable to reduce shrinkage in

ceramic industries. It is ideal ultra low loss ceramic. Electrical insulating bodies such as

high tension circuit barkers. In paint industries it is used as extender in oil and water

based emulsion paints latex paints, road paints and caulking compounds. It is also used in

the manufacture of asphalt and vinly, floor tiles, polyesters and epoxy resin compounds.

Besides this, wollastonite may used in the manufacture of ceramic bounded

abrasives, particulars, wheel stones, emery paper and industrial pumice by virtue of this

higher thermal shock residence and low co-efficient of expansion. In the fiber glass

industry to improve the surface and in manufacture of plywood substituting for alpha

cellulose. It is also used in continuous casting of steel for better surface finish.

The specification for the use of this mineral in different industries is not available

but the chemical analysis of world commercial grand wollastonite is given in table I:-

Table – I

Lappeenranta Finland Willsbore New York Belka phar India

SiO2 51.80 50.90 48.77

CaO 44.50 46.90 48.02

Al2O3 0.44 0.25 0.66

Fe2O3 0.22 0.55 0.43

TiO2 0.05 0.05 Traces

MnO 0.01 0.10 0.29

MgO 0.56 0.10 -

Na2O 0.10 - 0.02

K2O 0.01 - 0.11

Loss on ignition 2.20 0.90 1.68

Total 99.92 99.75 99.98

5. Indian Resources of Wollastnite:

The total known wollastonite reserves in the country are about 2.00 million

tonnes. The main deposits are found at the tri junction of Pali, Udaipur and Sirohi district

of Rajasthan. The other known occurrences are limited to only one in Godhra area of

Banaskanta district, Gujrat and two small deposits in Tiruneveli and Dharmapuri district,

Tamil Nadu. The total known resources are tabulated below.

Table – II

State Locations of the area Proved Probable Possible Total

Rajasthan Khila areas of Sirohi District - 14, 72558 4, 94,800 19,67,358

Gujrat Godera area Distt. Banaskanta - - 30,000 30,000

Tamil Nadu Dharampuri & Tirunelveli - - 2,650 2,650

Total say 2M.T. - - 2000008 -

Recently in the year 1988-89 low grade wollastonite occurrences have also been reported

by state Deptt. Of Mines and Geology, Rajasthan in Beawar area of Ajmer district

prospecting in the area will actually assess the deposit. Indications Udaipur district and

near Barwasa Village of Dungarpur district.

6. Wollastonite Mining In Khila Area:

A. Natural of Deposit:

The Village Belka (73° 10'50': 24° 46' 09” ) is located about 35 Kms NNE of

Sirohi Road Railway Station which falls on Delhi-Ahmdabad metergauge section of

western Railway. The areas is covered by high hill ridges rising upto 800 Mts above MSL

and covered by dense forests. The area is occupied by the rocks of calc-silicate and

impure limestone belonging to the Ajabagrah Group of Delhi Super Group and Post-

Delhi intrusive of granite &pegmatite which is highly deformed and trend of the

formation is NE-SW with steep dips. The Intrusions of Erinpura granite within the pre-

existing impure limestone pockets have given rise to formation of wollastonite and calcite

in favorable environment. The Other skarn minerals developed are garnet, epidote,

diopside etc.

The Wollastonite and calcite occurs in forms of plunging lenticular elongated,

bodies within Erinpura granite where long axis is trending N 35° E-S 35° W. There such

bodies separated each other by 100 to 200 mts. thick granite and skarn partings. The

central is the main lensoid body, extending for about 250 mts in length and 120 mts in

width. The core of the lense is made up of calcite and wollastonite forms the per

periphary followed by skarn and granite bodies, showing sharp contacts. The width of the

calcite across the long axis of the lense is 60 to 70 mts. and wollastonite is or 20 to 22

Mts. in Valley section, the persist then 100 mts. i.e. 790 Mts. above MSL and persist in

depth upto 675 Mts. above MSL. The dimension of the south eartern lense is 120 Mts. by

50 Mts. and north western lense is 35 Mts. by 25 Mts.

B. Mining Operation:

The mine has been developed considering the slope of the hills and plunge of the

lense. Mining is done by open cast method. Calcite and wallostonite both the minerals are

being mined simultaneously. The central lense has been developed into 7 benches and the

other two lenses are in developing stage. The mine is semi-mechanised and compressor,

tractor and Dumper etc. are in operation. During the year 1986,366 labours were

employed/day

7. Indian Production & Consumption:

The wollastonite is being supplied by the trade name of "KEMOLIT.

KEMOLIT S-1 to KEMOLIT S-4 are show white 100 to 400 mesh size powder and

KEMOLIT M-1 to KEMILIT M-4 is off white powder quality. KEMOLIT D-1 is the

cause fibrous variety. At present the pit mouth value of wollastonite is Rs. 325/- per

tonee. The snow –white and off white qualities are prepared as per demand. The Physical

properties of the Indian Wollastonite are as under :-

1. Colour Brilliant white

2. Lusture Pearly

3. Brightness 96-98%

4. Hardness 4.5%

5. Oil absorption 25-30 Lbs/100 Ibs

6. Ph of 10% slurry (Fresh prepared) 9.0

7. Solubility in water 0.00095(Gm/100cc)

8. Melting point 1540° C

9. Co-efficient of expansion (mm/Oc) 6.5x106

10. Thermal conductivity

(Btu/hrft2/OF/in) 0.87

11. Refractive Index 1.627

12 Specific gravity 2.9

13. Bulk Density 855 Kg/ M3

14. Bulking vaule (Gal/Ib) 0.0413

In India , the user Industries are basically of ceramic tile manufacture, such as

H&R johnson Spartek, Somani, Pilkington and insecticides industries.

The production of wollastonite of last 5 Years is given in the table as under.

GEOLOGICAL MAP KHIL WOLLASTONITE AREA, DISTRICT – SIROHI