Rice Husk Waste as an Exothermic Material for a Riser Sleeve for Steel Casting
Corresponding email: idamayanti79@gmail.com
Published at : 29 Jan 2020
Volume : IJtech
Vol 11, No 1 (2020)
DOI : https://doi.org/10.14716/ijtech.v11i1.2544
Idamayanti, D., Purwadi, W., Bandanadjaja, B., Triadji, R., 2020. Rice Husk Waste as an Exothermic Material for a Riser Sleeve for Steel Casting. International Journal of Technology. Volume 11(1), pp. 71-80
| Dewi Idamayanti | Department of Foundry Engineering, Politeknik Manufaktur Bandung, Jl. Kanayakan No.21 Bandung 40135, West Java, Indonesia |
| Wiwik Purwadi | Department of Foundry Engineering, Politeknik Manufaktur Bandung, Jl. Kanayakan No.21 Bandung 40135, West Java, Indonesia |
| Beny Bandanadjaja | Department of Foundry Engineering, Politeknik Manufaktur Bandung, Jl. Kanayakan No.21 Bandung 40135, West Java, Indonesia |
| Rafidan Triadji | Department of Foundry Engineering, Politeknik Manufaktur Bandung, Jl. Kanayakan No.21 Bandung 40135, West Java, Indonesia |
This research examines the
suitability of rice husk waste as an exothermic material for a riser sleeve for
use in steel casting production. Exothermic sleeves are used in the steel
casting process to compensate for shrinkage of the steel during solidification.
Commonly, the exothermic sleeve consists of fuel materials, fillers, and
binders. Rice husk waste has potential for use as a fuel material in the
exothermic sleeve due to its high calorific value. For this study, rice husk
waste was ground to gain a particle size of 60 mesh and then mixed with organic
binders of 12wt%, 15wt%, and 18wt%. A H-sleeve was then formed by hand
pressing, followed by drying. A series of quantitative tests were carried out
to analyze the performance of the rice husk as an exothermic material. These
include measurement of modulus extension factor (MEF) and the cooling rate of
the steel casting within the liquidus-solidus temperature range. The test
results show that the rice husk sleeve mixed with 12wt% of binder extended the
solidification time from 273 seconds to up to 511 seconds within the desired
temperature range. Furthermore, the best MEF of 1.69 was achieved using the
rice husk riser sleeve. This meets the standard MEF value of an exothermic
sleeve.
Exothermic sleeve; Modulus extension factor; Rice husk; Riser sleeve; Steel casting
Exothermic
riser sleeves are feeding aids used in steel casting to prevent the molten
steel from shrinking during solidification. They perform better than silica
sand risers (conventional risers) in increasing feeding efficiency and
minimizing the riser size (Brown, 2000; Miki, 2002).
One riser sleeve manufacturer reports that the use of an exothermic riser
sleeve can enhance the casting yield by 74.47–91.80% (Schäfer,
2011). According to many references (Auderheide
et al., 1999; Miki, 2002; Schäfer, 2011), exothermic riser sleeves
consist of fuels (i.e., oxidizable metals or exothermic materials), fillers
(i.e., sand or metal oxides), and binders (i.e., resin or water glass). In
order for an exothermic riser sleeve to produce a high casting yield, certain parameters
must be considered, such as the heat resistance of the fuel material in the
exothermic sleeve, which should readily ignite at 600oC (Williams et al., 2015; Dafiqurrohman et al., 2016); the density of the
exothermic sleeve, which should be low as porosity produces higher insulation (Miki, 2002); and the ash content after the
material is burned (Rao, 2013). These properties are required to keep the retardation of
temperature fall during steel
However,
our previous studies revealed several problems, including limited raw materials
and a complicated sleeve fabrication process. To solve these problems,
substitute materials were studied based on their thermal properties. One study
reported on an experiment in which rice husk was used as the primary material
to produce a top riser sleeve to prevent heat loss from the mold (Rao, 2013). This showed the potential of rice
husk for use in a riser sleeve. Currently, rice husk is not widely used in the
foundry industry, despite its abundance as biomass waste in Indonesia (Gibran et al., 2018). It is a source of renewable
energy and, due to its high calorific value (Lim et
al., 2012), is promising as an exothermic material. Thus, this study
aimed to utilize rice husk waste as a material for an exothermic riser sleeve.
Rice husk has a remarkably higher heating value (15.84 MJ/kg) (Lim et al., 2012) than commercial exothermic
sleeves (250–850 kJ/kg) (Williams et al., 2015).
Burned rice husk produces combustion residues that contain SiO2
(91.42%), K2O (3.71%), CaO (3.21%), Al2O3
(0.78%), and small amounts of other metal oxides (Maiti
et al., 2006), all of which can act as insulators. As well as being
affordable and having slow oxidation properties, rice husk is one of the
carbonaceous materials with anti-piping characteristics (Rao, 2013). Based on previous studies, it can be concluded
that rice husk is a potential material for exothermic sleeves with its
excellent physical properties (Maiti et al., 2006),
effective insulating potential due to the amorphous structure of residual
silica, and the high porosity of its ash residues (Wang
et al., 2016a); (Tiwari and Pradhan, 2017). It is easy to form into
briquettes with a low binder of 2–4% (Maiti et al.,
2006) and is an eco-friendly product with very low emissions (Unrean et al., 2018).
Hence,
this research focuses on the use of rice husk waste as an exothermic material
for a riser sleeve in steel casting. Its suitability as a riser sleeve was
determined quantitatively by testing the modulus extension factor (MEF) and
measuring the cooling rate to observe the thermal behavior of the rice husk
sleeve. Furthermore, the simulation was calculated to predict its feeding
efficiency in steel casting. The physical properties of the rice husk sleeve,
such as its bulk density and compressive strength, were also investigated.
Rice husk
waste has significant potential for use as a material for a riser sleeve
feeding system in steel casting. The MEF calculation generates an MEF value of
1.69, based on which the rice husk sleeve can be classified as an exothermic
sleeve. With a binder content of 12wt%, the rice husk sleeve had good
formability, a sufficient compressive strength of 6.9 kg/cm2, and
excellent temperature retardation of during GX60Cr15 solidification. The
solidification time of molten metal in the rice husk sleeve can be extended to
511 seconds, which is higher than that of the sand riser (215 seconds).
Furthermore, the feeding efficiency of the rice husk sleeve can be increased to
approximately 67.58%. In terms of compliance, the main characteristics of the
rice husk sleeve comply with the standard specifications of IS 15865:2009 for
an exothermic sleeve. Hence, the rice husk sleeve is recommended for use in a
feeding system for steel casting, where it has the potential to replace
existing commercial exothermic sleeves and enhance the value of rice husk
waste.
The authors acknowledge POLMAN-Bandung for providing financial support
under the Polman research project. We also thank the foundry department for
providing facilities.
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