7
The absorption amount of foaming agent is kept at 50 kg/h
through adjusting control valve. The foaming effect test is
conducted at the environmental temperature of 20 °C, the
relative humidity of 50%, and the barometric pressure of
101 kPa. The suggested parameters are applied on an active
coal combustion field within China through the blast holes
and the results are compared with water infusion method.
Results show that foams have a superior fire extinguishing
performance. The temperature reduction range using foams
is 6–7 times higher when compared with the conventional
water infusion, and CO concentration is reduced from 9.43
to 0.092‰ in the drilling hole after infusing foams. From
the remarkable results, it is confirmed that foams are appro-
priate for use on extinguishing large-scale coal fires in open
pit mines and have a broad prospect for the application.
Field applications in (X. M. Hu et al., 2014) demon-
strated that the composite foam effectively prevented air
leaks in collapsed areas, thereby reducing the risk of spon-
taneous combustion in the remaining coal. Walls reinforced
with composite foam provided significant advantages in
terms of sealing performance and compressive strength
compared to original walls, ensuring ventilation safety in
the working area. Furthermore, the composite foam was
found to be particularly effective for filling high-ceiling
spaces, offering a simple construction process, excellent fill-
ing performance, and strong supporting effects.
In (Y. Zhang et al., 2021)the synthesized foam is
applied at the Matigou coal mine, the new material reduced
the average air leakage rate from 12.8% to 2.1%. No
abnormalities in CO concentration were observed during
the withdrawal of supports from fully mechanized mining
areas, indicating that the phenolic resin-based composite
material effectively reduces the risk of spontaneous coal
combustion.
CONCLUSION
Studies on phenolic foams have shown that these materi-
als, while traditionally valued for their fire resistance and
low smoke emission, also exhibit promising potential for
mechanical and thermal applications in various industries,
including mining. Phenolic foams, composed of phenol
and formaldehyde, are known for their light weight, high-
temperature resistance, and stability under harsh condi-
tions. However, efforts to optimize these foams for broader
applications, especially in addressing coal spontaneous
combustion risks in mining, have led to extensive research
focused on modifying their properties through formulation
adjustments, density manipulation, and additive incor-
poration. One of the main areas of research has been the
manipulation of the formaldehyde-to-phenol (F/P) ratio.
Findings show that a higher F/P ratio generally improves
the compressive strength of phenolic foams, making them
more suitable for structural applications where stabil-
ity under load is required. However, this adjustment can
sometimes affect the thermal stability of the foam, prompt-
ing researchers to explore other avenues for balancing these
properties. The addition of bio-based materials, such as
lignin or cellulose, has emerged as an effective approach
to enhancing both mechanical and environmental perfor-
mance. Bio-based additives contribute to increased com-
pressive strength and resilience, allowing phenolic foams to
better withstand dynamic loads encountered in industrial
settings. These bio-mass inclusions also align with sustain-
ability goals, making phenolic foams more environmentally
friendly without compromising structural integrity. Further
studies have tested various synthetic and mineral additives
to improve the thermal insulation properties of phenolic
foams. The addition of nano-materials, such as nano-silica,
has been particularly effective in enhancing both mechani-
cal and thermal stability, due to the improved cellular struc-
ture they provide. Studies indicate that even small amounts
of nano-silica significantly strengthen the foam’s cellular
walls, providing a more stable thermal barrier and improv-
ing resistance to compression. Reinforcing agents like glass
fibers also contribute to higher mechanical strength, sup-
porting phenolic foams in applications that require both
durability and heat resistance, such as protective barriers in
coal mines. Density adjustments have shown that increas-
ing foam density leads to greater compressive strength but
with a trade-off in flexibility and cost. High-density foams
are found to be ideal for applications requiring rigid, struc-
tural support, whereas low-density foams retain flexibility
and are easier to deploy in varied spaces. As a result, cur-
rent studies suggest a tailored approach to density adjust-
ment based on the intended application. For the mining
industry, where spontaneous combustion of coal remains a
serious hazard, phenolic foams enhanced with these addi-
tives and adjustments have demonstrated the potential to
serve as effective barriers, reducing oxygen flow to coal sur-
faces and lowering ignition risks. Testing for these prop-
erties, following industry-standard protocols, has shown
that enhanced phenolic foams provide superior thermal
insulation, compressive strength, and long-term stability
under adverse conditions. Thus, with continued material
improvements, phenolic foams could become a viable, sus-
tainable solution for addressing safety challenges in mining
and other high-risk environments.
The absorption amount of foaming agent is kept at 50 kg/h
through adjusting control valve. The foaming effect test is
conducted at the environmental temperature of 20 °C, the
relative humidity of 50%, and the barometric pressure of
101 kPa. The suggested parameters are applied on an active
coal combustion field within China through the blast holes
and the results are compared with water infusion method.
Results show that foams have a superior fire extinguishing
performance. The temperature reduction range using foams
is 6–7 times higher when compared with the conventional
water infusion, and CO concentration is reduced from 9.43
to 0.092‰ in the drilling hole after infusing foams. From
the remarkable results, it is confirmed that foams are appro-
priate for use on extinguishing large-scale coal fires in open
pit mines and have a broad prospect for the application.
Field applications in (X. M. Hu et al., 2014) demon-
strated that the composite foam effectively prevented air
leaks in collapsed areas, thereby reducing the risk of spon-
taneous combustion in the remaining coal. Walls reinforced
with composite foam provided significant advantages in
terms of sealing performance and compressive strength
compared to original walls, ensuring ventilation safety in
the working area. Furthermore, the composite foam was
found to be particularly effective for filling high-ceiling
spaces, offering a simple construction process, excellent fill-
ing performance, and strong supporting effects.
In (Y. Zhang et al., 2021)the synthesized foam is
applied at the Matigou coal mine, the new material reduced
the average air leakage rate from 12.8% to 2.1%. No
abnormalities in CO concentration were observed during
the withdrawal of supports from fully mechanized mining
areas, indicating that the phenolic resin-based composite
material effectively reduces the risk of spontaneous coal
combustion.
CONCLUSION
Studies on phenolic foams have shown that these materi-
als, while traditionally valued for their fire resistance and
low smoke emission, also exhibit promising potential for
mechanical and thermal applications in various industries,
including mining. Phenolic foams, composed of phenol
and formaldehyde, are known for their light weight, high-
temperature resistance, and stability under harsh condi-
tions. However, efforts to optimize these foams for broader
applications, especially in addressing coal spontaneous
combustion risks in mining, have led to extensive research
focused on modifying their properties through formulation
adjustments, density manipulation, and additive incor-
poration. One of the main areas of research has been the
manipulation of the formaldehyde-to-phenol (F/P) ratio.
Findings show that a higher F/P ratio generally improves
the compressive strength of phenolic foams, making them
more suitable for structural applications where stabil-
ity under load is required. However, this adjustment can
sometimes affect the thermal stability of the foam, prompt-
ing researchers to explore other avenues for balancing these
properties. The addition of bio-based materials, such as
lignin or cellulose, has emerged as an effective approach
to enhancing both mechanical and environmental perfor-
mance. Bio-based additives contribute to increased com-
pressive strength and resilience, allowing phenolic foams to
better withstand dynamic loads encountered in industrial
settings. These bio-mass inclusions also align with sustain-
ability goals, making phenolic foams more environmentally
friendly without compromising structural integrity. Further
studies have tested various synthetic and mineral additives
to improve the thermal insulation properties of phenolic
foams. The addition of nano-materials, such as nano-silica,
has been particularly effective in enhancing both mechani-
cal and thermal stability, due to the improved cellular struc-
ture they provide. Studies indicate that even small amounts
of nano-silica significantly strengthen the foam’s cellular
walls, providing a more stable thermal barrier and improv-
ing resistance to compression. Reinforcing agents like glass
fibers also contribute to higher mechanical strength, sup-
porting phenolic foams in applications that require both
durability and heat resistance, such as protective barriers in
coal mines. Density adjustments have shown that increas-
ing foam density leads to greater compressive strength but
with a trade-off in flexibility and cost. High-density foams
are found to be ideal for applications requiring rigid, struc-
tural support, whereas low-density foams retain flexibility
and are easier to deploy in varied spaces. As a result, cur-
rent studies suggest a tailored approach to density adjust-
ment based on the intended application. For the mining
industry, where spontaneous combustion of coal remains a
serious hazard, phenolic foams enhanced with these addi-
tives and adjustments have demonstrated the potential to
serve as effective barriers, reducing oxygen flow to coal sur-
faces and lowering ignition risks. Testing for these prop-
erties, following industry-standard protocols, has shown
that enhanced phenolic foams provide superior thermal
insulation, compressive strength, and long-term stability
under adverse conditions. Thus, with continued material
improvements, phenolic foams could become a viable, sus-
tainable solution for addressing safety challenges in mining
and other high-risk environments.