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TURN UP THE
HEAT RESISTANCE
Jim Farrell, Blastcrete Equipment LLC,
discusses the installation of monolithic
refractory in cement kilns.
Introduction
Annual worldwide refractory consumption in the
production of cement is estimated to be more than
5 million t, or 12% of the total world refractory market,
and growing. Monolithic refractory makes up a good chunk
of that market, as much as 40%, and rightfully so. It is faster
and easier to install than refractory brick, which is why as
much as 2.3 million t of monolithic refractory is used each
year.
Because of equipment improvements and material
innovations, such as no-cement or colloidal silica, which
offer optimal alkali resistance and bonding properties,
contractors are installing monolithic refractories in areas
of cement kilns once reserved for brick refractory. This
includes the nose ring and tail ring, which is also called the
inlet cone. These improvements and innovations also are
making it easier and more cost effective for brick refractory
contractors to make the switch.
There are three methods that contractors use to install
monolithic refractory materials, including the following:
1.
Cast-in-place, also known as form-and-pour.
2.
Using wet shotcrete methods to spray in place without
the use of forms.
3.
Using the dry process method of spraying in place
without the use of forms, also known as the gunite
process.
Cast-in-place
The most popular placement process for monolithic
refractory installation over large areas is the cast-in-place
method. In some cases, this method is the only means of
placing the material. Contractors can mix precise amounts
of water with material and monitor each batch to ensure
a homogenous mixture is achieved, which maximises batch
quality. Once the material has been mixed properly, it is
loaded into a high-pressure swing tube concrete pump and
the material is pumped and vibrated in place.
The major advantages of cast-in-place installation are
optimal quality control and a smooth finished surface,