Towards a sustainable future
Background of the case:
I
had earlier worked on developing a useful product viz: Pavement Blocks from industrial
waste i.e. cupola furnace slag. While sharing the case study with a group, one of the participants,
Mr. Aakash Mittal, approached me and expressed that his family industry was also
facing a similar problem and whether I can help his family business
and find a solution similar to the cupola slag.
As there is never ever a single cut out solution for
such wastes, I desired to visit the industry and offered to
give it a shot, but didn't promise a solution off hand.
Accordingly, a visit was planned for
the unit located in Gwalior, Madhya Pradesh. It turned out that it
was a stone slabs manufacturing unit.
Gwalior stone slabs industry:
Gwalior region in MP, like many other geographic
regions, has a cluster of stone slabs manufacturing units. The cluster has
about 60 units within a radius of about 50 kms. encompassing the small towns of
Banmore, Purani Chawni, Morena, Dhaulpur etc.
The stone slabs have found their utility in large
scale construction activity. The process involves quarrying large stone blocks
(Picture-1), Slicing the slabs on a endless blade cutting machine (Picture-2
and Picture-3), and finally sizing them as per specifications and offerings
(Picture-4). The finished slabs are also graded based on the quality of the
stone and geological structure.
Picture - 1 Picture - 2
Picture - 3 Picture - 4
Picture-5
The problem definition:
While everything seemed to be going smooth for the
industry at large, during a detailed chat with the owner of the unit
(Picture-5) , the owner of the unit expressed that they in fact have a serious
problem with the disposal of the stone dust, which is a by product of the
process of cutting stone blocks in to slabs. He also narrated his experiences
with the neighbouring population’s resistance and the directives from the state
Pollution control boards, threatening that the units may be asked to close down
if they don’t find a permanent solution to the stone dust. He also informed
Prof. Chari that in the previous year alone they had spent about Rs. 4,00,000
(Rs. Four Lacs) for clearing the space occupied by earlier dust. However, all
they could do was just to shift the location of the heaps.
This prompted a visit to the area surrounding the
unit. It revealed that the whole neighbourhood was strewn with fine greyish
powder, all around the unit and spreading about 500 meters radius. Pictures 6
to Picture 9 show the condition of the area. where they have been dumping it
over the past years.
Picture-8 Picturee-9
However, the present process used for cutting stone
slabs will always generate the dust.
During the discussions, it was estimated that on an
average, an estimated about 4 to 5 truck loads (about 40 to 50 mts.) of such
dust is generated daily in the region.
With a view to find a solution to the problem, some
samples of the dust were collected.
Experimentation:
Many initial and ground level experiments were
conducted, but without any result.
At this stage, Prof. Chari decided to embarked on a
scientific approach to the issue. The
dust samples were sent to laboratories for chemical analysis to find the basic composition.
The results receivd from the laboratory are produced
here below.
|
L.O.I
|
0.74 %
|
|
SiO2
|
91.98 %
|
|
Al2O3
|
2.78 %
|
|
Fe2O3
|
0.80 %
|
|
CaO
|
0.67 %
|
|
T.CO3
|
Nil
|
From the above results, it was found that the dust
contains about 92% Silica and the remaining comprise traces of Alumina, Iron
Oxides, Cao and other ingredients.
Having come to know about the content of Silica, the
Prof. Chari remembered his work in the past at Glass Industry in the town of
Firozabad in Uttar Pradesh- India. He remembered that the glass industry also
uses silica rich raw material for producing Glass.
He searched through his database and found out the
contact details of a glass expert with 50 years of experience in glass industry.
That was Mr. Shrivastav, General Manager of M/s Nannoomal Glass Industries in
Firozabad.
Mr. Shrivastav was contacted and requested to give
his impression about the practicality of using this material as a raw material
for glass manufacturing.
Mr. Shrivastav desired that a sample be sent to him
and he would get it analysed as per their own standards. Accordingly, on his
advise, a sample was sent to the laboratory of the Center for Development of
Glass Industry (CDGI), an extension of the CGCRI (Central Glass and Ceramic
Research Institue, Calcutta, a central government organisation.
The results given by the laboratory were as below.
Analysis carried out by CDGI, Firozabad
|
Item
No.
|
Element
/ Parameter
|
Percentage
|
|
1
|
LOI (Loss On Ignition)
|
00.59
|
|
2
|
Sio2
|
94.02
|
|
3
|
Al2O3
|
02.59
|
|
4
|
Fe2O3
|
00.12
|
|
5
|
Na2O
|
00.32
|
|
6
|
K2O
|
01.94
|
|
7
|
Cao
|
00.27
|
|
8
|
Mgo
|
NIL
|
Sieve analysis of stone dust sample
SAMPLE TAKEN
100 gms
|
MESH NO.
|
WEIGHT
RETAINED ON SIEVE
|
Percentage
|
CUMULATIVE
%
|
|
25
|
0.3
|
0.3
|
0.3
|
|
35
|
0.7
|
0.7
|
1.0
|
|
50
|
40.0
|
40.0
|
41.0
|
|
90
|
52.0
|
52.0
|
93.0
|
|
100
|
4.0
|
4.0
|
97.0
|
|
-100
|
3.0
|
3.0
|
100.0
|
After reviewing the results, Mr. Shrivastav told
that while the material can not be used for producing white glass, as it
contains iron oxides more than the process can handle, however the material can
be definitely used for making coloured glass.
At this stage, I initiated a dialogue with
the Firozabad Glass Industry cluster and the responses from some of the
manufacturers of glass bangles have been very encouraging. Mr. Gupta, Chairman
of the Durga Glass Works, who had more than 60 years of experience with glass
production, straightaway said that the material can be directly used as a raw
material. He offered to produce a batch, subject to the condition that a sample
of 500 Kgs. is delivered in his factory.
This effort proved that with some initial
processing, the waste has a high potential for use as a basic raw material for
glass bangles of the darker colours.
Other experiments:
While the above was underway, Prof. Chari continued
with his experimentation to identify some alternate possible uses of the waste.
Having come to know that the waste contains high percentage of silica, he
remembered his association with energy experts who had told him that silica is
indeed a very good material for heat insulation application. Taking a clue from
this, many expetiments were carried out in the direction of identifying and
exploring the possibility of use of the material as a heat insulation material.
Some experimental blocks were developed with various
binding agents and the initial experiments had shown a very favourable result.
It was felt that if it works that way, there indeed is a great opportunity for
use of this material as Low Cost heat insulation blocks for use in lining of
industrial furnaces.
While failures were faced in some of the experiments
(Picture- 10), the “Never Say Die” attitude finally brought out some very
successful outcomes.
With one of the binding material, viz: Plaster of
Paris (POP), the blocks were made successfully. Picture-11 and Picture- 12.
Picture
13 Picture-14
Picture-15: Two sides after 12 minutes (six minutes each)
Experiment for establishing the heat insulation properties of the blocks.
The initial experiments were carried out at home laboratory
level. The pan with one of the above mentioned slabs was heated for 60 minutes
to ensure that the whole set up is stabilised for the experiment. Two modules
of dough were made from single lot and placed on the pan, Picture-13, and it
was observed that the dough kept directly on the pan was burnt as shown in
Picture-14, in just about 6 minutes, whereas nothing happened to the dough kept
on the slab.
The burnt dough was turned upside down and after
another 6 minutes was found to be burnt in the same way as the first side.
Picture- 15. However, the dough kept on the slab was seemingly not much
changed.
Picture-16 Picture – 17:
Condition after 85 minutes
The experiment was continued for a total of 60
minutes, but the dough on the pan did not burn at all. See Picture-16
To doubly ensure the initial findings, one more
fresh lump of dough was added and the heating was continued till 85 minutes.
The condition of the dough blocks didn’t change much. Picture-17
This experiment showed that the material definitely
has some heat insulation properties, as it does not allow the heat to pass
through very easily.
This was followed by constructing a real life
furnace with equal wall thickness brick furnace. Picture – 18. The top of the
roof was covered with the blocks Picture-19 and the furnace was fired. Every
thing, from construction of the furnace to laying the roof and plastering, was
seeming to be a great success. The felt temperatures on the side walls and roof
were definitely much different, and the roof was found to be much cooler than
the side walls.
Picture
18 Picture-19
However, after about one hour, the roof collapsed.
Picture -20 and 21.
Picture-20 Picture-21
While an average person would get disheartened with
such happenings, but the experimenting team always believed that every failure
and disappointment is a step towards further research.
Based on these observations, Prof. Chari requested
M/s Durga Glass Works at Firozabad to allow his team to undertake a real life
and live experimentation on one of their Talli Bhattis, with these slabs.
M/s Durga Glass Works of Firozabad have already
given us a clean chit and welcomed to carry out any experiment that we may want
to, and agreed to allow experiments on one of their live furnaces.
A team of students comprising Mr. Aakash Mittal was
sent to the unit with these blocks and they conducted the experiment by
directly placing the blocks on the furnace (Talli Bhatti)
It turned out to be a highly
successful experiment with highly favourably results.
We
arranged tiles made of waste on Furnace at 07:30AM. A time of 2 and half hours
was allowed to get a stabilised state of the furnace surface. The readings were
taken at 10.00AM (After two and
half an hour).
At one place
on the conventional surface of the temperature of furnace was measured to be 2800C
while the temperature on the experimental blocks was only 1500C.
At
another place, the corresponding temperatures were observed to be 1900C
and 1200C respectively.
The
observations continued and at 11.00 PM
( after three and half hours) while the surface temperature on the conventional
surface was observed to be 3500C, the temperatures on the slabs were
observed to be only 1500C, which clearly indicated that the about
half inch thick slabs can help dropping the surface temperatures by almost
2000C, which will help in drastically reducing the furnace surface radiation
losses, and thereby enhance the thermal efficiencies of the furnaces. This has
it’s own advantage by reducing the carbon foot print of the industry.
The pictures 22 through 25 show how the experiment
was carried out.
Picture-22 Picture-23
Picture-24
Picture-25
Interaction with CGCRI Khurja also carried out an
analysis of the material and expressed their impression that the material
perhaps can be used for Glazing of ceramic pottery, and have offered to carry
our some experiments.
A similar discussion with some of the iron and steel
foundries revealed that silica rich (94%) material can also perhaps be a
candidate for either foundry sand or facing sand too.
The future work involves extensive experimentation,
scientific testing and proving of the product. The future work will also involve
Finding different ingredients for blending, increasing the mechanical strength of the bricks, Thermal Conductivity testing etc. The making of such products needs an infrastructure,
organization, laboratories, and live testing of the products in industry.
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