The Application of Ion Exchange
Resins to Metallurgical
Waste Problems
F. X.   MC GARVEY
Chemical Engineer
Rohm & Haas Company
Philadelphia, Pa.
Ion exchange techniques have been employed successfully in the
solution of certain metallurgical waste problems. The exchangers have
been particularly successful as concentrators of metals from dilute
solutions. Their use gives an economical and effective method for the
elimination of dilute wastes which are especially difficult to handle by
conventional precipitation, and settling and by filtration techniques.
In certain cases ion exchange resins may purify such objectionable
industry wastes as hydrochloric pickle acids.
Ion exchange resins are solid, insoluble, cross-linked poly-electrolytes.
Their property of insolubility is essential to their use in many industrial
applications. The different types of ion exchange resins may be characterized by analogy to common electrolytes. For example, strong
acid cation exchange resins contain sulfonic acid groups attached to
a resinous three dimensional network. Amberlites IR-112 or IR-120
are examples of resins of this type. In the hydrogen or acid form,
these resins have the properties of insoluble sulfuric acid. In the sodium
form, the solid electrolyte is similar to sodium sulfate.
This comparison of chemical characteristics may be extended to
all types of exchangers. Amberlite IRC-50, a typical carboxylic
exchanger, has chemical properties similar to acetic acid or sodium
acetate. Strong base anion exchangers may be compared to sodium
hydroxide or sodium chloride. Amberlites IRA-400 and IRA-410 are
examples of strong base exchangers. Weak base exchange resins such
as Amberlite IR-4B and IR-45 may be compared with polyamines of
ammonia with respect to their chemical properties.
The analogy with soluble salts cannot be extended beyond qualitative chemical properties. The theory of ion exchange equilibria is
closely related to the thermodynamics of two phase systems. Efforts
to derive a consistent theory of ion exchange reactions are advancing
rapidly. The kinetics of ion exchange operations have been investigated
for a wide variety of conditions.    Recent studies by Bliss and Selke
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