REFRACTORIES IN HEATING UNITS
DURABLE LININGS FOR THE TAP HOLES OF ORE-ROASTING FURNACES
V. V. Slovikovskii
and A. V. Gulyaeva
Translated from Novye Ogneupory,No.2,pp.3–5,February, 2015.
Original article submitted November 11, 2014.
The reasons for the short service life of the lining of the tap holes in ore-roasting furnaces at nickel and tin fac
tories are analyzed. It is established that the main reasons are the large number of seams in the lining and the
low resistance of the sintered periclase-chromite refractories to slag and abrasion. Work has been done to cre
ate a seamless design of tap hole made of a slag-resistant refractory. Blocks made of PShFB-grade refractories
have been developed along with a fused periclase-chromite refractory (grade PKhPP) and a new high-temper
ature adhesive. Use of the seamless tap holes has increased the life of their lining by a factor of 2.0 – 2.5.
Keywords: periclase-chromite refractories, periclase-spinellide brick, graphite-corundum products, refrac-
tory adhesive, tap hole.
The production of ferronickel from oxidized nickel ores
by reductive roasting of the ores in rotary furnaces, the pro-
duction of black ferronickel from a matte in ore-roasting fur-
naces, and the refining of black ferronickel in vertical con-
verters with the injection of oxygen are promising technolo-
gies in nonferrous metallurgy.
However, the dearth of experience in the operation of
high-power (48 MVA) furnaces by these technologies is cre
ating certain problems that are affecting the productivity of
ore-roasting furnaces and the quality of the finished product.
One of the bottlenecks in the production of ferronickel is the
low durability of the refractory lining (12 – 18 months under
a furnace load of 25 – 26 MVA). The rapid wear of the
refractories near the tap holes and notches and the escape of
molten metal through fractured parts of the lining make it
difficult to successfully use the roasting technology and op
erate ore-roasting furnaces at the power level for which they
An improvement in the design of the refractory lining
and the use of more durable refractory materials would allow
the furnaces to operate at their design capacity for two or
more years. The most heavily worn parts of the refractory
lining of the ore-roasting furnaces at the Pobuzhe Nickel
Plant in Pobuzhe are the tap holes. The tap holes of furnaces
Nos. 1 and 2 are currently made of periclase-spinel brick.
The tap holes in the slag zone have to be replaced after the
smelting of 6000 – 8000 tons of product. Figure 1 presents a
diagram of the lining and the wear of tap holes made of a
graphite-corundum refractory. The tap holes are character-
ized by severe erosion of the refractory, since the velocity of
the jet of metal and slag reaches 10 – 20 m/sec. In addition to
erosion, the refractories are subjected to corrosion by the slag
and to thermal shock at the moment the product is tapped.
A new refractory for the tap holes was chosen based on
the service conditions: erosion, thermal shock, and corrosion.
The most durable refractories under these conditions are
graphite-corundum products of the following composition,
wt.%: corundum ³55; refractory clay 1.7 – 2.0; graphite
15 – 18; silicon carbide 7 ± 0.5; silicon 3 ± 0.5. Products
made from this mix have good resistance to heat and erosion
and experience almost no impregnation. Corrosive wear
takes place in the form of thin layers as the carbon is oxi
dized. A 1-ton trial batch of the graphite-corundum products
was made for factory testing.
The experimental refractory is characterized by high me
chanical strength and excellent resistance to heat. Studies of
the character of wear of the lining of tap holes made of
periclase-spinel and graphite-corundum products showed
that wear takes place as a result of erosion; the seams are the
weakest link in the tap holes. The service life of the tap-hole
lining can thus be increased by partially or completely elimi
Refractories and Industrial Ceramics Vol. 56, No. 1, May, 2015
1083-4877/15/05601-0001 © 2015 Springer Science+Business Media New York
Ural Federal University, Ekaterinburg, Russia.