Page 27 - CFCM May-June 2021_Neat

PLATING AND ANODIZING: FUME CONTROL

CONTROLLING

FUMES IN PLATING

ume control in plating plants is a complex subject. There are
Fvarious substances used in plating processes that either
produce undesirable fumes directly, or that can become airborne
during manufacturing.
The issues with hexavalent chrome are well-known, and this
substance has been phased out from many applications where it was
once widely used. Poly- and perfluoroalkyl substances are not
harmful in direct contact, but they persist in the body, potentially
leading to or aggravating some forms of cancer or hormonal
conditions, or causing problems with fertility.
Their average serum elimination half-life is four to five years,
meaning the amount of them in a worker’s body reduces by 50
percent in that time. Therefore, they can carry problematic levels of
them in their bodies for much of their lives. There are close to 5,000
perfluoroalkyl substances known, though most are rarely used, and
only a few are considered significantly toxic.
Then, whatever metal is being used for plating can become
volatilized, and exist as ambient particles in the plant air. Not all
metals are harmful under such conditions, but clearly, the cleaner
the air plant workers are breathing, the fewer problems can also
occur in the areas outside of the plant.
There are two separate approaches to controlling emissions from
within a plant. One is to use extraction and filtration systems, and A Mech-Chem dust particulate collection system.
there are numerous suppliers of these. The other is to use wetting
agents or fume suppressants, which can reduce the degree of misting
that occurs at the surface of the plating bath. Atotech’s Fumetrol 21 LF2 was developed, the company says, to
Both approaches have their advantages and drawbacks. Many reduce the surface tension of a chrome plating solution to below 40
facilities employ both, to reduce fumes to the smallest level possible mN/m emissions of hexavalent chrome due to mist.
with current technology. “Combined with a thin foam layer that forms around the cathodes
“Surface active” fume suppressants, often called surfactants, are and anodes, it acts as a physical barrier to further reduce mist and so
used particularly in chromium plating baths and are classified as hexavalent chrome emissions,” the company says. “Its ease of opera-
either temporary or permanent. Some fume suppressants produce tion, high stability and simple conversion of old suppressant systems
“blankets” that suppress the mists on the surface of baths, while makes it the ideal choice for reducing mist and complying with the
wetting agents affect the surface tension of the baths to reduce latest PFOS directives.”
misting. When such wetting agents lower the surface tension, gases Fumetrol 21 LF 2 has a wider working window, Atotech adds. It is
escape at the surface of the solution less energetically, causing less only a single product and has reportedly superior low-foaming action.
mist formation. Hunter Chemical’s Fume Control HCA-8.4 formula is recom-
Dynamix’ Dynaplate Cr FS product line is one example of such mended for hard-chrome plating and decorative-chrome
materials, and comprises several options for different plating bath plating/chromic acid anodizing operations. This formula is available
formulations. Referring to prior additives that have been commer- for use in markets both in the U.S. and internationally.
cialized, the company has described these as fifth-generation chem- “Additional formulations, such as Fume Control HCA-8.2, HCA-
istries that are fluoride-free, PFOS/PFAS-free and halogen-free. 8.2D and HCA-8.1, are used across the U.S. and Canada,” the
They are also reportedly completely biodegradable. company states.
These non-ionic, dispersive suppressants, the company says, On the filtration equipment side, Viron International Corp. spe-
work by coating the surface of the plating bath with a very stable low cializes in the collection of chromic acid in chrome plating applica-
foam blanket, while reducing the surface tension to below 40 tions. Its Viro-Chrome 9000 Series Chrome Scrubber systems,
dynes/cm. Another benefit is that these agents can be used in both Viron says, have been meeting the stringent efficiency requirements
decorative and hard chrome plating, which gives the end user versa- in place and solving customer’s emission concerns since 1971.
tility and practicality in the operation of chromium plating baths. “The Viro-Chrome 9000 Series was designed to meet the
WWW.CFCM.CA CANADIAN FINISHING & COATINGS MANUFACTURING 27