Exploring The Benefits Of Incorporating Rice Husk And Groundnut Shell In Refractory Bricks

Abstract

Refractory bricks are widely used in industries such as metallurgy, glass, cement, and ceramics due to their high resistance to heat, corrosion, and mechanical stress. Traditional refractory bricks are typically made from materials like clay, silica, and alumina. However, the increasing demand for sustainable and eco-friendly solutions has prompted researchers to explore alternative materials that can be used in the production of refractory bricks.

This research investigates the potential utilization of two agricultural waste materials, rice husk and groundnut shell, as alternatives to traditional refractory brick components. Rice husk is the outer protective covering of rice grains, while groundnut shell refers to the outer covering of groundnut or peanut. Both materials are abundantly available as agricultural residues and are often considered as waste.

The study aims to determine the physical, mechanical, and thermal properties of refractory bricks produced by incorporating rice husk and groundnut shell. The researchers analyze the effects of different proportions of these materials on the overall performance of the bricks. Various manufacturing techniques and binding agents are also examined to optimize the production process.

Full text

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Exploring The Benefits Of Incorporating Rice Husk
And Groundnut Shell In Refractory Bricks
1*Onyia, T. M.,2 Onyia, P. E., 3Ugwuoke, N. F., 4Romanus, F. O. 5Iyida, L. O., 6Idenyi, N. E.
1,2,3,4,5&6 Department of Metallurgical and Materials Engineering,
Enugu State University of Science and Technology, Enugu, Nigeria
5Department of Mechanical Engineering,
Ebonyi State University, Abakaliki, Nigeria
*Corresponding Author Contacts; +2348147764797, tobias.onyia@esut.edu.ng
ABSTRACT
A study to explore the benefits of incorporating Rice husk and Groundnut shell in refractory brick was
carried out. Eight samples of refractory fire brick were used in the experiment and all were fired to a
temperature of 1200OC. The mixing ratio of rice husks/groundnut shell in sample D to G were 1:5, 1:3,
2:1 and 5:1. A few tests in the likes of Apparent porosity, apparent density, bulk density and modulus of
rupture test were conducted. Results shows that samples H had the highest performance in the modulus of
rupture. These blends produced can be used as a refractory lining.
Keywords: Groundnut shell, Rice husk ash, Clay, Refractoriness, Physical Properties, Chemical
composition
INTRODUCTION
Refractory bricks are an essential component in high-temperature industries such as steel, cement, and
glass production. The properties of refractory bricks, such as thermal conductivity, strength, and
resistance to thermal shock, directly affect the efficiency and reliability of these industries. However, the
production of traditional refractory bricks involves the use of natural resources such as clay, which can
lead to environmental degradation and resource depletion. Therefore, there is a need to explore alternative
materials that can be used in the production of refractory bricks.
One such alternative material is agricultural waste, which is abundant and readily available in many parts
of the world. Rice husk ash (RHA) and groundnut shell (GS) are two examples of agricultural waste that
have been studied for their potential use as a raw material in the production of refractory bricks. RHA and
GS are rich in silica, which is a key component in traditional refractory brick production. In addition, they
are environmentally friendly and can provide a sustainable solution to the production of refractory bricks.
The purpose of this research article is to investigate the effect of RHA and GS on the properties of
refractory bricks. The study will focus on the effect of varying percentages of RHA and GS on the thermal
conductivity, strength, and resistance to thermal shock of refractory bricks. The research will be
conducted using a standard method of production of refractory bricks with varying percentages of RHA
and GS added.
The thermal conductivity of the refractory bricks was measured using a thermal conductivity meter. The
strength of the bricks was determined using a universal testing machine, and the resistance to thermal
shock was evaluated using a thermal shock test. The results obtained from the tests were compared with
International Journal of Innovative Scientific & Engineering
Technologies Research 11(2):31-38, April-June, 2023
© SEAHI PUBLICATIONS, 2023 www.seahipaj.org ISSN: 2360-896X

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those of traditional refractory bricks to determine the suitability of RHA and GS as raw materials for the
production of refractory bricks.
The findings of this research article will provide insight into the potential use of RHA and GS in the
production of refractory bricks. The use of these alternative raw materials has the potential to reduce the
environmental impact of traditional refractory brick production while providing a sustainable solution to
the production of refractory bricks. The results obtained from this study can be used to inform future
research and development in the field of refractory brick production and provide a basis for further
exploration of agricultural waste as a raw material for other industries.
MATERIALS AND METHODS
The firebricks contain fireclay and additives, the additives are rice husk and groundnut shell. Fireclay was
crushed and ground separately, and stored in respective labelled dry containers. The rice husk was
screened and examined to ensure that no grams were present in their mass, also the groundnut shell was
also examined to ensure that it contained no groundnut in it. The rice husk and groundnut shell were
ground separately and carefully sieved using a mesh size of 30, then stored in respective labelled
containers. Furthermore, the ground fireclay was mixed properly using a small mortar with his addition of
water and used in a molding sample in a cylindrical mold, there were also rectangular molds used. The
fireclay mold had of 55mm, the firebricks contain fireclay and additives, the additives are rice husk and
groundnut shell. Fireclay was crushed and ground separately, and stored in respective labelled dry
containers. The rice husk was screened and examined to ensure that no grams were present in their mass,
also the groundnut shell was also examined to ensure that it contained no groundnut in it. The rice husk
and groundnut shell were ground separately and carefully sieved using a mesh size of 30, then stored in
respective labelled containers. Furthermore, the ground fireclay was mixed properly using a small mortar
with his addition of water and used in a molding sample in a cylindrical mold, there were also rectangular
molds used. The fireclay mold had of 55mm; the fireclay mold was prepared using used engine oil the
walls of the mold to allow for easy removal of the molded sample from the mold cavity. Then the samples
were weighed in a weight balance, with all on the sample recording a constant weight of 240g for all the
samples. Moreso, the fireclay, was added various quantities of additives, measured and weighed in weight
balance. Rice husk was added in the following sequence 5, 10, 15,20,25,30 also groundnut shell was
measured in containers and added in the sequence of 30,25,20, 15, 10,5 grams. As obtained in the weight
balance. They were properly mixed in a mortar to achieve a homogenous mixture. The first sample was
taken as the control sample, as there was no additive in it. The samples were all weighed again, and their
weight was recorded.
Tables 1. Composition of fireclay and additives
Samples
Fireclay
(g)
Rice
Husk (g)
Groundnut
Shell (g)
A
240
-
-
B
240
-
30
C
240
5
25
D
240
10
20
E
240
15
15
F
240
20
10
G
240
25
5
H
240
30
-
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Physical Test Analysis
The analysis of the physical properties includes: - Total Shrinkage, Volume Change, Bulk Density,
Apparent Density, Apparent Porosity, Water Absorption and Modulus of Rupture Test were all carried out
according to ASTM International standard.
Table 2. Physical properties of fire clay
Constituent
Fire Clay
Linear Shrinkage (%)
7-10%
Apparent Porosity
20-30 %
Bulk Density
1.71-2.1g/cm3
Cold Crushing Strength
1500kg/cm3 (22.9-59N/mm2)
Thermal Shock
Resistance Cycle
25-30 Cycles
Refractoriness
1500-1700°C
[Source: Chimaetal,2017].
Chemical Test Analysis
Composition of the chemical properties of International Standard. [Chima et al, 2017].
Table 3. Chemical properties of fired clay and refractive brick
Constituent
Material
Fired Clay (%)
Refractory
Brick (%)
Si02
55 - 75
51-70
AUO3
25 -45
25-40
K2O
< 2.0
—
Fe2O3
0.5-2.0
0.5-2.4
MgO
< 2.0
—
Chemical Composition of the Clay
The percentage composition of the Oxides required for the clay were determined through chemical
analysis of the clay sample. The chemical composition of the clay is SiO2, AUO3, K2O, Fe2O3 and MgO.
The X-Ray Fluorescence (XRD) method was used to perform chemical analysis on the clay samples, and
the finding were recorded. The chemical composition of the clay employed in this investigation revealed
Silica content of 51-70% and Iron oxide Fe2O3 content is 0.5-2.4%.
RESULTS
Shrinkage Test
The drying shrinkage, firing shrinkage and the total shrinkage were calculated for each test samples using
the following formulae stated (Chester J.A 1973 and Norsker H. 1987).
% Average drying shrinkage =
% Average firing shrinkage =
%Total shrinkage =
%Volume Change =
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From the bar chart the average drying shrinkage 110oC sample A and H increase sharply, decrease at
sample B, C, D of which all had a constant value. Samples E, F, G also increased, but sample A and H had
the highest value of 3.64. Making sample A and H the most shrinked sample in the dry state.
Average firing shrinkage at 1000°C, Sample A and H were the highest from the bar chart with the value of
5.66. Sample B, C, D had the constant of 3.77 while sample E, F, G increased steadily to the value of 4.67
therefore making sample A & H the most shrinked sample in the fired state.
The total shrinkage at 1000oC show sample A had the very highest total shrinkage, samples B, C, D had a
constant rate of shrinkage while sample E, F, G had a relatively increased total shrinkage. Sample H & A
show a more rate of total shrinkage from the experiment.
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Volume change at 10000C from the bar chart shows that sample A had the highest volume change while
sample B, C, D had the lowest volume change with a constant value for all the three. Sample E, F, G had
a steadily increased volume change while samples H had the second highest volume change from the bar
chart.
Sample H with 30g rice husk had t the lowest value of Bulk density of 2.11g/cm3, while Sample C with
5g/ 25g rice husk / groundnut shell had a value off 6.50g/ cm. Samples A, B, D, E, F, and G with no
additive 30g groundnut shell, 1Og/ 20g RH / GS, 15 /15g, 20g/ 10g RH/ GS and 25g/ 5g, had the values
5.83 g/ cm3, 5.40g/cm3, 5g/ cm3, and 6.6g/cm3 respectively. The higher and lower percentages of rice
husks and groundnut shell respectively in the sample led to lower values bulk density. This because rice
husks burn out, allowing the volatile matter to escape, leading to weight drop and thus reducing its bulk
density.
From the bar chart, at 10000C Sample G had the highest apparent density of 16g/ cm³ while sample C had
the second highest of 13g/ cm3 with 5g/25g RH/GS Other samples A, B, E & F had good apparent density
sample H show the lowest apparent density of 2.40g/cm3 with 30g rice husks in experiment. The results
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proves that the higher the percentages of rice husk and lower the percentages of groundnut shell in brick
samples the lower their apparent density.
Samples A with no additive the apparent porosity was 16.66% sample C and E with 5g/25g and 15g/ 15g
of RH/GS had an equal value of 50% while Sample G with 25g/5g of rice husk/groundnut shell had the
highest value of 60% samples B, D, F and H With 30g groundnut shell, 10g/20g, 20g/10g RH/GS and 30g
rice husks had 40%, 44.4% , 43.0%, and 11.76% because sample H was heated at higher Temperature of
12000C This led to shrinking of the pores.
As no RH/GS additives concentration, Sample A showed the lowest strength of 1.82kgf/ cm² while
Sample H showed the highest strength of 2.90kgf/ cm 30g rice husk concentration. At 15g/ 15g RH/GS
additives concentration, sample E showed strength of 2.20kgt/ cm2, while D has strength of 2.0kgf/cm² at
a concentration 10g/20g RH/GS additive. At 5g/25g RH/GS additives concentration, C showed a strength
of 1.96kg/cm² while sample B showed strength of 1.90kgf/cm2 at a 30g GS additive concentration and at
25g/5g RH/GS Additive At 20g/10g Concentration, sample F and G showed strength of 2.75kgf/cm2 and
2.97kg/cm² respectively.
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The water absorption of sample D is the highest in the experiment with 14.81%, sample with 15/15g rice
husk and groundnut shell had 14.3%, Sample F, had 10.3%, sample B had a value of 7.41%, sample C
with 5g/25g had the of 7.69%. Sample G and H had the value of 9.10% and 5.55% with 25g/5g RH/ GS
and 30g rice husk respectively. But sample A had the lowest value of water absorption due to a more
homogenous structure. It follows that as porosity increases, the rate of water absorption also increases. As
temperatures Increase, Percentages water absorption rate decreases leading to pore shrinking. It may be
said that the lower the percentages of groundnut shell and higher the percentages of rice Husk in the
sample, the higher its Strength and vice versa. This is because groundnut shell creates empty pores in the
firebrick matrix, while the rice husk has ash in the pores created. This left over ash is still capable of
supporting and transferring load. The reduction in the number and size of pores of the brick samples due
to increased rice husk percentage induce high transfer of load to the bricks, thereby increasing the
modulus of rupture. The rising trend in the values of modulus may also not be unconnected with the
formation of some bonds which increase cold strength of a refractory. Modulus of rupture is observed to
increase with increasing fire temperature. This according to Khanna 0.P material science (2005) is due to
the replacing of the glassy matrix formed on cooling, with crystals that tends to interlock with each other
giving rise to a strongly bonded mass considerably increasing the refractoriness under load.
From the result, it shows that the samples with high percentage of rupture had the increase modulus of
rupture and as well as high Strength sample C also showed an improved modulus of rupture of about
2.0kgf/cm². Sample G showed the highest modulus of rupture followed by sample E &F. Sample A had
the lowest modulus of rupture due to his material nature.
CONCLUSION
It may be said that the lower the percentages of groundnut shell and higher the percentages of rice Husk
in the sample, the higher its Strength and vice versa. This is because groundnut shell creates empty pores
in the firebrick matrix, while the rice husk has ash in the pores created. This left over ash is still capable
of supporting and transferring load. The reduction in the number and size of pores of the brick samples
due to increased rice husk percentage induce high transfer of load to the bricks, thereby increasing the
modulus of rupture. The rising trend in the values of modulus may also not be unconnected with the
formation of some bonds which increase cold strength of a refractory. Modulus of rupture is observed to
increase with increasing fire temperature. This according to Khanna 0.P material science (2005) is due to
the replacing of the glassy matrix formed on cooling, with crystals that tends to interlock with each other
giving rise to a strongly bonded mass considerably increasing the refractoriness under load. From the
results, it shows that the samples with high percentage of rupture had the increase modulus of rupture and
as well as high Strength sample C also showed an improved modulus of rupture of about 2.0kgf/cm².
Sample G showed the highest modulus of rupture followed by sample E &F. Sample A had the lowest
modulus of rupture due to his material nature.
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RECOMMENDATIONS
Composites are materials made up of different materials, fireclay and additives, in order to determine how
these additives would improve the clay used. Therefore, judging from the result obtained, I would
recommend the commercialization of this piece of work, in order to help in improving the economy
through boasting the local content policy of the government.
The government should also partner with multinational companies, industrialist, steel industries in order
to invest in improve this work through research and development. Therefore, further researches should
carry out to determine; the effect this additives rice husk and groundnut shell would have on other clay
types, through financial assistance to researchers in the form research grants.
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