Zinc-coated galvanized steel scrap is the most widely used
feedstock for Electric Arc Furnace (EAF) steel production. World
crude steel production reached 1,66 billion metric tons for the
year 2014, up by 3.9% compared to 2013 (World Steel Association).
Around 26% of crude steel is produced using the EAF technology.
During the EAF process, the high temperatures required to melt the
feed material produce a zinc byproduct (EAF dust) that leaves the
furnace along with the off-gases. The gases are filtered and the
EAF dust is collected in bag houses.skype:gary102884,
The EAF dust waste steam is considered a hazardous material due to
the potential for the heavy metals to leach into the ground,
contaminating ground water and sewage systems.
The EAF dust generated by steel mills can be recycled in an
economically viable way using the Waelz Kiln technology. The
recycling process is part of the larger steel industry loop that
allows the reuse of two important natural resources - zinc and
Energy efficient and clean, the Waelz Kiln technology is especially
suited to the increasing demands of environmental laws being
(1) EAF steel dust is transported by road or rail to a steel dust
(2) The feed materials are provided in either dry compact-moist or
pelletized form. The compact and pelletized moist materials, coarse
fluxes and coke are stored in boxes while the dry dust is
transported by pneumatic conveying systems to raw material silos.
(3) Typically 55 meters long with a four-meter diameter, the Waelz
Kiln is slightly inclined 2-3% and has an approximate rotary speed
of 1.0 rpm. skype:gary102884, whatsapp:+8615617816797. As the moist
material moves through the rotary kiln, it is dried and preheated
by the kiln gas, flowing in a counter-current pattern. In the
reaction zone, reduction of the metal oxides occurs around 1200°C
as the zinc is vaporized as metal vapor into the gas cleaning
system. Zinc is then re-oxidized in the kiln atmosphere that is
operated with excess air (process air is injected from the kiln
end). Chlorine and alkalis volatilize jointly with the heavy metals
and the dust-laden off-gas is treated in a downstream off-gas
(4B) In the first stage, coarse particles mechanically entrained
are separated in a dust settling chamber and returned to the kiln.
The hot, dust-laden off-gas is cooled and Waelz Zinc Oxide is
separated in a high efficiency collector.
(4A) The co-product, Waelz Iron Product, can be used directly in
road construction, civil construction (backfilling), cement
manufacturing or can be reprocessed to add more value to the iron
content which is currently under research and development.
(5) The dust-free off-gas is then treated, filtered and discharged.
(6) Waelz Zinc Oxide, the main product of the process, is delivered
to zinc smelters for zinc production.