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Acid-free metal cleaning for wire production
I posted a message last week about the replacement of pickle liquor in a wire
casing operation. The article was in the Dec. 1966 issue of POLLUTION
ENGINEERING magazine on page 47. The equipment is a DynaPower
ultrasound/electrolysis cleaner made by DynaMotive Technologies Corp. in
Vancouver. At the Nucor Wire Inc. plant the toxic solid output alone was down
550 - 600 percent compared to conventional systems that clean metal with pickle
acids. The system creates chemical reactions by the electrolysis in a shallow
bath of hot water that contains "harmless" dissolved salts. DC electrical
current passes through this aqueous electrolyte to the wire, repeatedly
alternating the wire polarity from anodic to cathodic. The wire's dwell tiem in
the electrolysis bath is measured in seconds at the cleaning systems speed of
250 - 300 ft./min. This weakens the bond between surface scale and the metal
underneath. After cleaning in the electrolysis bath, the wire proceeds through
a series of low-pressure water jets through which pass shore compression waves
of ultrasound. When these waves encounter debris loosened by electrolysis, they
"literally blast it away." The wire is then rinsed in clean water and dried
with air jets. The wire exits the system pH neutral which keeps it from
oxidizing upon re-exposure to air. Capital costs amounted to about $200,000
This goes to show you that there is nothing offering zero pollution. The
wastewater will need to be treated to remove the metals from the wire. There
will be a sludge. But we did get rid of the acid!!! We are also probably using
more energy to run this little system.
Jacksonville Naval Air Station went to zero discharge of water. They are using
hydrogen peroxide (requiring Process Safety requirements) to treat the water and
have to evaporate the water and dispose of the salts as a hazardous waste. They
did achieve zero discharge of WATER. Think about it.
Robert B. Pojasek, Ph.D.
Cambridge Environmental Inc.
58 Charles St.
Cambridge, MA 02141
(617) 225-0813 (F)