ACID RECOVERY IN THE STEEL AND METALLURGICAL INDUSTRY: PROCESS
CHARACTERISTICS, FUEL SAVING OPTIONS
*F. Baerhold and S. Mitterecker
ANDRITZ AG
Eibesbrunnergasse 20
A-1120 Vienna, Austria
(*Corresponding author: frank.baerhold@andritz.com)
ABSTRACT
Acid recovery is an important process step in pickling and leaching processes. Pyrohydrolysis in spray
roasters and fluidized beds is well established to recover hydrochloric acid, but the hydrolysis in the liquid phase
is also more and more considered as alternative for new process routes. The characteristic features of the three
processes are discussed.
Hydrochloric acid based leaching processes for Ilmenite and Nickel-Laterite ores produce far larger
volumes of waste acid streams than the steel industry. Upscaling of the spray roasting technology to the
maximum possible capacity is necessary to become more cost effective. Process routes based on Ferric chloride
pyrohydrolysis allow the production of superazeotropic HCl (up to 30%).
The new ECOmode concept optimizes the operation of pickling line and spray roast acid recovery plant.
Long term results from industrial applications show, that fuel savings of the spray roaster of 25% are easily
achieved without additional process steps. An attractive feature is also to upgrade existing installations to higher
plant capacities.
KEYWORDS
Acid recovery, Hydrochloric acid, Pickling, Leaching, Energy saving,