REFRACTORIES IN HEATING UNITS
CHROMITE-PERICLASE REFRACTORY WEAR
IN ZINC PRODUCTION WAELZ KILN REACTION ZONE
L. M. Aksel’rod,
T. V. Yarushina,
I. G. Maryasev,
I. V. Privalov,
and A. L. Andrievskikh
Translated from Novye Ogneupory,No.11,pp.5–11,November, 2016.
Original article submitted August 30, 2016.
A contemporary procedure is discussed for improving the structure of chromite-periclase refractory based on
analyzing corrosive action of a reaction charge fired in a Waelz kiln. It is established that refractory wear dur-
ing service proceeds by a frontal scheme through a series of successive transformations of the microstructure.
On the basis of studying corrosion results for refractory objects of fayalite composition by slag manufacturing
technology is developed for chromite-periclase refractories more resistant to Waelz material components.
Keywords: chromite-periclase refractory, zinc production Waelz kiln, crust formation, slag resistance.
The Waelz process is used for zinc extraction by volatil-
ization in the form of vapor during processing of zinc-con-
taining raw materials . The basis of the Waelz process is
reduction of zinc oxide with carbon above 1000°C. Zinc va-
por is extracted from gases forming within the kiln and is
captured in the form of dust enriched with oxide from metal
volatilization [2, 3]. A Waelz kiln lining is subject to chemi-
cal action of the reaction mix of treated material, and also
A Waelz kiln may be conditionally separated into five
typical zones [4, 5]:
– Drying zone. Gas heated to 750 – 1000°C entering the
drying zone heats a charge approximately to 150°C. There is
removal of physically and chemically bonded moisture. Heat
transfer is accomplished by convection and radiation, and
gas does not enter into reaction with charge components. The
zone length is roughly 7 m.
– Sulfate and carbonate decomposition zone. Waelz
treated material is heated to 700°C. Sulfates of zinc and iron,
and carbonates of calcium and magnesium decompose to ox-
ides. Gas temperature within the volume of the kiln and at
the charge surface reaches 1000 – 1250°C. Heat transfer
from gas into the material and into the refractory lining pro-
ceeds predominately by radiation. The extent of the zone is
of the order of 20 m.
– Reduction zone. Metal oxides and fuel combustion
products, i.e., carbon dioxide, are reduced by charge solid
fuel. Charge temperature reaches 900°C, and the gas temper-
ature is 1250°C.
– Reaction zone. Combustion processes, coke carbon
gasification and oxidation of iron oxides develop with for-
mation of a high-temperature gas stream, and there are re-
placement and exchange reactions with formation of matte
and slag phases. Reduced forms of metal oxides formed pre-
viously are subject to oxidation by air oxygen and water va-
por entering from the sinter cooling zone. The maximum gas
temperature reaches 1300°C. The material temperature also
reaches a maximum value and is 1250°C.
– Sinter cooling zone. The process of sinter formation is
complete with temperature reduced to 1150 – 1200°C.
Over the last decade during combined work by special-
ists from Gruppa Magnezit and various zinc production en-
terprises comprehensive research has been conducted mak-
ing it possible to improve refractory lining considerably. The
basis of research is a generally accepted method for evaluat-
ing resistance to action of a corresponding reagent during de
termination of slag resistance under laboratory conditions us
ing a dynamic method and analysis of the results of refrac
tory service in a furnace unit [6, 7]. Up to 2010 refractory
Refractories and Industrial Ceramics Vol. 57, No. 6, March, 2017
1083-4877/17/05706-0563 © 2017 Springer Science+Business Media New York
OOO Gruppa Magnezit, Moscow Russia.
OOO Gruppa Magnezit, Satka, Chelyabinsk Region, Russia.
TOO Dalmond, Pavlodar, Kazakhstan.