Practical Development Aspects
of Waste Pickle Liquor Disposal
Lorenz W. Heise, Director
and
Milton Johnson, Supervisor
Central Material and Process Control Laboratories
A. O. Smith Corporation
Milwaukee, Wisconsin
The disposal of waste pickle liquor and other acid bearing materials
has been plaguing the metal working industry since its beginning. Pickle
liquor is a name given to a solution containing sulphuric acid used in
the steel industry for the removal of mill scale or iron oxide which is
formed during hot rolling or forging of steel. General interest in this
problem has been intensified in recent years because industry and population have increased to the point where direct disposal to streams or
ground waters is considered a major contamination problem.
The pickling bath varies from about 5 per cent to 20 per cent by
weight of acid. The chemical reactions during the pickling process
changes the nature of the bath so that in the course of time it approaches
saturation with iron salts and is no longer effective. The disposal of this
waste pickle liquor containing a large concentration of iron sulphate and
a small percentage of sulphuric acid is the essence of our problem.
Any industrial waste disposal problem must, generally, be classed
as plant overhead cost and as such, any possible steps to minimize or
eliminate these extra expenses represent a worthy cause.
At the A. O. Smith Corporation a low capital investment cost
method of waste pickle liquor disposal has been developed. It is believed
that the method is the most practical and economical for the A. O. Smith
Corporation's particular problem. Patent claims on this process have
been allowed and have been made available to industry. Since the
original development early in 1951, continuing effort has been applied
to simplify the operations and reduce costs.
It is believed that a step by step outline of our plant operating
improvements may be helpful to others faced with similar waste disposal
problems. This discussion is dedicated to that purpose.
The lime neutralization of pickle liquor is by no means a new
process or the ultimate method for the disposal of this waste.   But, at
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