Kota stone slurry problem and possible solutions

1. 1
KOTA STONE SLURRY PROBLEM AND POSSIBLE SOLUTIONS
- A. Hussain
India has largest reserves of dimensional stones in the world and this makes suo-moto
largest producer of dimensional stones in the world. We have a wide spectrum of
dimensional stones including Granites. Marbles of different colours and textures, Sand
stone, Lime stone, Slates and Quartzites spreaded all over country.
In today’s reference India alone share about 32 percent of world’s total dimensional stone
output, with total annual production of combined range exceeding 185 million tones per
year. Rajasthan is leading producer of dimensional stones contributing about 90 percent
of country’s total Marble, Sandstone and Kota stone production. The estimated reserves
of important dimensional stones in Rajasthan are given in table – A.
Table – A
Estimated Reserves of Dimensional Stone in Rajasthan (Million Tonnes)
Marbles 1100 Million Tonnes
Ceranites 1128 million tones
Sand Stones 900 million tones
Flaggy Lime Stones 1800 million tones
Slates 50 million tones
A simple and most generalized chemical composition of important dimensional stones is
given in table –B
Table – B
Chemical composition of Marble, Granites and Limestone
Chemical
composition
Marble
(Percentage)
Granite
(Percentage)
Limestone
(Percentage)
Lime 28-32 1-4 38-42
Magnesia 20-25 0.5-1 4-6
Ferrons and Fernic
oxides
1-3 - -
Mining and polishing of dimensional stones generate a large quantity of waste and fine
dust, which creates a serious environmental problem. According to international Journal
of Engineering sciences and research teachnology the mining and processing activities of
marble in Rajasthan alone is produching about 50,00,000 Mt of marble slurry in a year
out of 1.5 to 2.0 million tones of total waste generated out of marble mining in the state.
The waste slurry contains about 40,00,000 Mt of water and rest 10,00,000 Mt of
calcareous line particles. This volume of gigantic slurry is released from 1000 gang
shaws and thousands of stone cutters operating in the state marble producing zones. This
marble waste is indestructible and harmful to common man, animals and vegetation
creating aesthetic problems. This is a major threat to environment.

2. 2
India has over 85,600 million tones of calcareous stones (marble and other lime stone
based stones) and the annual production of all dimensional stones is over 185 million
tones and Indian stone cutting and polishing industry produce around 17.8 million tones
of solid calcareous waste per annum. The accumulated waste is of the order of 250
million tonnes.
Apart from the entire calcareous stones, in this paper we want to focus on Kota stone
mining and processing problems in specific, thought Kota stone is part of overall
calcareous stones spectrum and face similar environmental problems.
Table – C provides chemical composition of all the Indian calcareous stones
(Dimensional stones)
Table – C
Chemical compesition of Indian calcareous stones
Ingradient Percentage by weight
Marble Limestone Granite
Calcium oxide 35-40 38-42 1-3
Silica 3-25 15-18 73-76
Alumina and
Ferrous oxide
9.12-11-76 1.02-1.53 18.78-21.12
Potassium and
sodium oxide
0.06-1.12 0.35-0.62 5.12-7.15
Magnesium oxide 2-3 13.14-15.32 0.04-0.09
Loi 38-43 32-34 <0.5
Kota stone as is better known in building stone terminology, is basically a calcareous
sedimentary rock available in a number of colours (blue, green, brown, grey etc) and
textures. The stone deposits are well stratified and split easily all along the well formed
weak plans facilitating smooth and well textured homogenous stone panels in various
thickness.
Kota and Jhalawar districts of Rajasthan and neighbouring Madhya Paredsh district of
Neemach have 1800 million tones of this splittable dimensional stone reserves and a
typical chemical analysis of this type of stone is given in Table – D
Table – D
Chemical composition of Kota Stone
Calcium oxide 37.30%
Magnesium oxide 4.13%
Sodium oxide 1.21%
Postssium oxide 0.40%
Aluminium Trioxide 1.37%
Ferrous oxide 0.86%
Titanium oxide 0.05%
Silica 24.90%
Loi 31.94%

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Generation of Stone Waste:
In specific to stone powder generation, there are two types of powder wastes coming out
of Kota stone mining ie-
1. Quarrying or sawing from the insitu stone mining sites and
2. Cutting and polishing wastes from polishing industries.
During processing of the stone, different size cuts
are made in the insitu stone benches, facilitating
tiles or slabes of various sizes and thicknesses
(usually 2 to 4 cms thick) using diamond blades. A
constant stream of water is thrown over the blades,
while cutting is in progress to cool the blades and
to remove the dust produced during cutting
operation. The waste water from this operation is in
a considerable large quantity and highly alkaline in
nature.
(Fig. 1 : Kota stone mining in progress)
Quantity of slurry generation:
The blades thickness of the cutting drums used in stone mining is about 5 mm and the
longitudinal cuts are made at an intervate of 60 cms all along the productive benches. The
slabes are further cut and dressed into 20mm thick slabes, and therefore out of every
25mm thick slabes production, 5 mms are converted into powder while cutting the stone
to make slabes. This powder flows alongwith water as slurry.
To find the quantity of fine powder
generation vis-à-vis the stone slabes
production a number of tests were
conducted. The slurry coming out of the
operation, was channeled into a two
compartment rock chamber, where the
overflow of the first chamber was allowed
to collect in the second chamber for
recycling. The stone dust was trapped into
first chamber as a white cake. Once the
first chamber was filled up with the stone
polish recycling was stopped and the dry-
polish cake was loaded into tippers with
the help of JCB machine, and weighment
made at the weighbridge. A relationship
was envoled between the weight of the
collected dust and stone output, results are
given in Table – E
(Fig. 2 : Waste dumps in Kota stone Mines)

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Table – E
(Results of stone output and waste generated in the form of dry dust)
S.No. Stones Quarried in MT Weight of Dry Dust generated MT Percentage
1. 328 MT 50 15.24
2. 287 MT 40 13.93
3. 362 MT 55 15.19
4. 285 MT 40 14.00
5. 318 MT 50 15.72
Thus, normally 15% of the total weight of limestone produced is converted into fine
powder slurry containing 35 to 45 percent of water content.
YEARLY QUNTUM OF KOTA STONE POLISH GENERATION AND ITS
DISPOSAL
Present level of Kota stone production is about 80 lakh Mt per annum, and consequent to
its mining and processing a fine dust waste to the tune of 12 lakh MT is generated every
year, out of which about 4 to 5 lakh MT of dust is disposed in the mined out areas, and
rest all the waste is discharged into convenient places, including near by water streams,
agricultural lands, govt. pasture lands, forest land ,road sides etc.
Disposal of this type of dust is affecting 5 to
10 hectors of prime land every year. So far, a
considerable land has already been
permanently damaged due to this activity
(Fig. 3 – Stone dust on agricultural land)

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ENVIRONMENTAL HARARD OF STONE DUST
Some of the ill effects of stone dust wastes are given as under –
1. The stone waste is indestructible
2. Dumping grounds gives repulsive dirty looks
3. Land fertility of agricultural land is totally impaired
4. Loss of valuable top soil due to blanketing with dust
5. Contamination of rivers, nallas and other surface water bodies
6. Slurry affects productivity of land due to decreased porosity water absorption and
percolation
7. Slurry dumped areas can not support vegetation
8. The fine particles of slurry gets entrenched into land capillaries and block ground
acquifers recharging.
9. Drains and nallas are chocked due to setteling of fine dust and adjoining
agricultural fields are flooded with rain water, making crops losses.
10. Dust nuisance
11. Fine particles of slurry (size less than 363 micron) becomes air borne and causes
air pollution
12. public out-cry against the dust nuisance
(Fig. 4: Washed out powder dust)
PROPERTIES OF STONE WASTE (POWDER)
Some of the important physical properties of stone powder waste material are given in
Table – F

6. 6
Table F
(Physical properties of Kota stone dust)
Specific gravity 2.58-2.65
Bulk Density 1568-1743 kg/m3
Water absorption 2-4 percent
Max partical size 0.2 mm
Fineness Module 3900-4123 cm2
/gm
Colour White
Kota stone it self is a soft stone having hardness between 3-4 (Moh scale) with density
varying from 2.20 to 2.85 gms/cc and having compressive strength between 1800-2100
kg/cm2
. It has low prosity and good weather resistant charactersistics.
APPLICATION POTENTIALITIES
Considering its harmfull impacts a number of exercises have been carried out by various
organizations including Private Mine/Factory Owners Associations, to explore gainfull
uses of stone dust. Some of the areas identified for potential uses are given as under-
1. Cement manufacturing
2. Filler material in paper making
3. Paints and poly propylene
4. Soda production
5. Blast furnace flux
6. Acid neritralizer for industrial effluents
7. Agricultural soil amendment specialy to offset soil acidity
8. Flue gas desulphuration in electric power generation stations
9. Lime manufacturing
10. Resin conglomerates for florring
11. Wall coatings in buildings
12. Chemical applications
13. Cosmetics and pharmaceuticals
14. Filler in concrete
15. Paving material
Recycle and use of Kota stone dust in cement plants is still a research based issues. High
silica is a point of consideration apart from logistical complexities. Experiments have
shown that it is a good substitute for some of the material items used in road construction
but public works departments as well other construction agencies have not shown much
interest, mainly because of transportation cost considerations.
In chemical segment, quality gypsum can be made from the slurry, but process cost in
comparison to natural available gypsum is forbidding.
Brick samples with cast size 230x125x75 mms were casted manually by mixing cement
in various ratios and putting into moulding frames for a specified time intervals. The
resultant bricks have shown compressive strength up to 30 to 50 kg/cm2
. Hosever, the

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cost of processing is still an hindrance. We have tried mixture of Dust with white cement
in various ratios, giving beautiful white tiles, but cost is an impairment.
SCIENTIFIC DISPOSAL
As earlier said that lime stone slurry is a processing waste of Kota stone mining and
dressing industry and its huge quantity to the tune of 15 percent of total production is
dumped on empty lands, agricultural fields, pasture lands, rivers beds and road sides
creating a number of serious environmental problems. The problem has to be tackled in
two critical alternatives i.e. firstly by finding and using a compatible engineering
utilization and second by adopting a scientific disposal.
Fig – 5: Slurry dumped into Nalla.
The scientific disposal can be practicised with a little
enforcement of discipline in waste disposal system, and
some of the recommendations are as under-
1. The processing facilities are situated is a close area
designated as Kota stone extractive zone. This zone
covers a part of Kota and Jhalawar districts. There
are a number of working and abandoned quarries
located in this zone. State mining and geology
department should take initiative and fix some old
workings in this zone and direct all the processing
units to dump their slurry waste into these old
workings, Processing Industries owned by the mine
owners should be forced to dump the waste slurry
into their own waste dump yards or re-use for
reclamation programmes.
2. Stone processing units operating near Kota town
should be given a specified land refill area, and
should not be allowed to dump their waste slurry in
all possible ways and means.
3. The slurry generated in the mining process should
be channelized into two inter connected chambers. Where, the sediments settle into
first chamber and clean water over flows into adjoining chamber, from there it can be
recycled for cutting operations. The collected sediments in first chamber can be
removed from time to time with the help of a JCB and tipper combination and
dumped into waste dumps.

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Fig. 6: Water recycling
This will not only save water for
recycling, this will also help in the
reduction of water demand by re-
utilization of water and also help in
disposing slurry and lowering
down the damage to eco-system.
Conclusion:
Kota stone slurry waste is indestructible and harmful to common man, animals and
vegetation, creating aesthetic problems. This is a major threat to environment and efforts
should be made to find viable engineering applications at the earliest. Till then, scientific
disposal of the waste should be given top priority.
A. Hussain