MARBLE WASTE MINIMIZATION
Introduction
R. K. Bapna *
Marble ranks the largest produced natural stone in the world and it accounts for 50% of
the world's natural stone production. Around 90% of the world's production of marble comes
from India and approx 85% of India's production is received from Rajasthan and almost all
mining and processing activities are concentrated around Udaipur, where the proposed study is
planned to undertake. The marble mining industry has come up significantly in recent past.
Rajasthan has around 4000 marble mines and about 1100 marble gang saws (processing plants).
The industry involves Mines, Processing plants, Cutters for the production of tiles for walls and
floors, articles, waste reproduction and other ancillary works.
The marble mining and the industry as a whole is different from other industries with the
very fact that, the marble is a "Dimensional Stone", which means the stone is sold by size not by
weight. (In other words in sqm not by tonnes)
Since the selling price increases manifolds with size, all the operations involving mining
& processing are aimed to get slabs as big as possible.
Waste generation
The very fact of being dimensional stone marble has contributed to the development of
grave environmental problems in the region due to waste generation at different stages of mining
and processing operations. The technical, operational and management practices in the industry
are less developed and they have also contributed significantly to greater waste generation.
The industry is causing two serious problems, which are creating havoc in the region:
* B.E. (Mining), F.C.C., Consultant Mining Engineer.
(a) Problems owing to slurry produced in different operations, and
(b) Dumping of small boulders which are not economic to cut into slabs.
The magnitude of the problem can be seen in the following table:
Finished marble produced
(Saleable product)
Marble waste generated
- Mining waste (including small
blocks of lower revenue,
boulders, cutting slurry)
- Processing waste (including
broken tiles, dressing waste,
cutting slurry)
- Polishing and transportation Waste
Total Waste
Total excavated marble
30%
50%
15%
05%
70%
100%
From the above table it can be adjudged that recovery is only 30%, while 70% of
excavated marble go as wastage.
Environmental problems due to waste
The production of waste shown in the above table are causing following
environmental problems:
(a) Conservational
The valuable national wealth is getting wasted mainly due to lack of management and
lack of technology. This waste, if recovered as useful, can change perhaps the entire scenario
of the industry. Since it is not impacting directly on the environment the non-conversion of
useful mining product is a more grave problem in longer term than other direct problems.
(b) Air pollution
This is the most direct and hazardous impact of the industry. As it is clear from the table,
slurry is produced at almost every operation and its dumping is a great problem. When it gets
dried and airborne, it causes air pollution and related problems.
(c) Water pollution
Like any industry, the marble industry needs water in its different operations for cooling
and flushing different discharge. In these operations water gets contaminated. This contamination
is considerable and it can be said that water pollution of the region is caused by discharging
slurry.
(d) Vegetation related problems
Due to opencast nature of the mining, devegetation of the area is imminent. Also dried
slurry deposited over plants and vegetation hamper their growth.
(e) Visual impacts
Running mines, abandoned mines, dumping sites, slurry waste sites, deposition of dried
slurry over almost every structure in surrounding aeas are a very bad sight. Hills having been
excavated and dumps over them are very unaesthetic.
(f) Scarcity of the dump sites
The production of a large amount of waste needs additional land for its dumping and
handling.
(g) Accidents due to unscientific dumping
There are a number of accidents due to unscientific dumping of mine wast on road and
quarry sites.
(h) Loss to flora & fauna
Already grown trees and bushes have died out and new ones do not grow. Animals have
also been deprived of their food and shelter.
Measure to remedy problems related to waste
Reaching general evaluation of the industry, it is observed that the problems related to
waste production in the marble mining and processing and its disposal and reutilization can be
circumvented by technical assistance and improved management practices. For this purpose the
most useful step can be :
(a) Reduction of waste production
If waste is reduced a crucial part of the problem is solved; and hence, the methods have to be
developed to reduce the waste production in conjunction with its reutilization and rehabilitation.
This following are some measures to reduce waste production:
Inputs to be made cheaper: The diamond based tools have industrial diamonds in them.
There are two types of diamond insertion (Bit, Segment and Beads), Electroplated or
Impregnated. The Electroplated type is the most suitable for sawing soft stones and requires less
water spray and Impregnated type is suitable for all types of stone with fairly abundant spraying.
Therefore, if the selection is made according to the need the cost will be reduced.
Improvement in performance: Some of the factors which affect the performance of
sawing are (i) Mode of sawing, (ii) blade peripheral speed, (iii) sawing rate, (iv) machine
parameter, (v) operator skill, (vi) flushing medium (type & rate), (vii) thrust and (viii) diamond
type, size & concentration.
For improvement of performance the following aspects of cutting operations are
inferred in most of the studies: (i) Optimising the application for particular stone, (ii)
Improvement of performance of diamond segments, (iii) Finding substitute of costly segments,
(iv) By adding surfactant into coolants and (v) Reducing diamond dropouts.
Reduction in production of slurry: For the reduction of the production of slurry, till
date sharp and perfect cutting edges were the only measures. Now thin blade technology has been
introduced in Italy. Its results are very good and can be used to reduce the production of slurry.
(b) Suppression / disposal of waste
All efforts should be made to minimize waste. But it is also a fact that some of the waste
will be produced. Hence proper suppression and disposal techniques are essential. Not much
work has been done yet, apart from giving site for slurry disposal. Yet a moderate advancement
has taken place. In other words interfaculty application from Mineral Dressing, has suggested the
making of cake of slurry using Filter Press. It has been suggested because 5000,000 tonnes slurry
generated annually contains 4000,000 tonnes of water. Hence an effort should be made to get the
maximum possible water out of it and slurry be converted in the form of cakes. This can far more
easily be disposed. For the purpose a special filter press is designed and plant owners are
encouraged to install one. This helps in utilization of water, proper disposal of slurry and
lowering the damage to eco-system. Added to this, is the fact that by help of filter press, the solid
concentration can be increased from 15 to 18% in slurry and 83 to 87% in cake.
(c) Reutilization of marble waste
Even by taking measures for minimum waste production the problem is partially solved.
Therefore it is -the need of the hour to develop modes of reutilization of waste.
The marble slurry is generating in substantial quantity and creating environmental havoc
in the region. Thus many scientists and agencies are working on it. Efforts are being made to
reutilize slurry for different civil works, since other applications cannot consume such a bulk
amount of slurry.
(d) Reutilization of marble waste other than slurry
There are a number of possibilities for the secondary use of marble lumps. Some of them
are:
- Value added products: Articles, idols, stairs, monuments etc. are being prepared. Mr.
Bhagirath Joshi from Jodhpur has shown a remarkable potential of the segment of the
industry.
- Marketable Chemicals: There are some of the areas of applications in chemical
production by marble waste like: synthetic Calcium Sulphate and Magnesium Sulphate
from dolomite waste.
- Defluorination of water: Rajeev Gandhi Mission for Water has suggested that serpentine
can be used for Defluorination of water.
Conclusion
In the beginning it has been explained that the marble mining and processing industry in
Rajsamand district has assumed a great dimension. But, to our great dismay it is also alarming
that as big as 70% of the marble resource goes waste which is not only unprofitable but is also
immensely harmful to the environment. Later in the article environmental problems have been
discussed and some useful suggestions made with a hope that if they are carried out the problem
will be solved to some extent.
Acknowledgement
I express my deep regards and sincere thanks to Shri B.L. Paliwal, Retd. Vice Principal,
Kendriya Vidyalaya, Pratap Nagar, Udaipur for his guidance and help in writing this article.
I am also highly grateful to Shri M.S. Paliwal, Mining Engineer, DMG, Amet for his
technical guidance and valuable suggestion in writing this article.
Refrences
Agarwal R.K. ; 'Modern marble processing techniques and their suitability for Indian
condition"; A company report by Rajasthan Udyog, Jodhpur.
Anon; "Technological evaluation & norms study in marble & granite industry'" Report of
Ministry of Science & Technology, GOI; July 1993.
Battacharya B.C.; "Possible utilization of waste marble powder / slurry - a case study".
Seminar on gainful utilization of marble slurry in various construction activities; UCCI, Udaipur;
Sept. 18,2002.
Bhatnagar A.; "Scientific and modern mining of marble - Development of large block
extraction with minimum of waste". Global seminar for golden jubilee of I.I.T. Kharagpur,
TMMPE-2000; Dec. 1-3-2000.