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RE: neutralizing chlorides

Title: RE: neutralizing chlorides


Chemical treatment to produce an insoluble chloride is not practical and you can't get more elemental than chloride.  I think what they need to do is wash the filter cake to remove the soluble chloride.  Washing will displace the retained brine, the source of the chloride (I'm assuming that the filter cake consists of metal hydroxides and not metal chlorides). A small RO unit can be used to concentrate the resulting filtrate and reduce the volume of water requiring disposal.  Specific details of the washing step will depend on the filtration method currently employed.  They may be able to wash the cake prior to discharge from the filter. Both plate and frame and rotary drum filters are often equipped with this function.

Mike Callahan, PE
Principal Chemical Engineer
Jacobs Engineering Group Inc.
1111 S. Arroyo Parkway
Pasadena CA 91105
(626) 568-7005


-----Original Message-----
From: Lange, Ted [mailto:lange@montana.edu]
Sent: Monday, July 29, 2002 3:47 PM
To: P2Tech (E-mail)
Subject: neutralizing chlorides

Hope some of you may be able to help with this question:

We got a call today from a company that has a tungsten-carbide stripping
process producing approximately 200,000 lbs/yr of copper/nickel filtercake
that they currently have to pay to get rid of because this filtercake has 3%
free chlorides.  They say that if they can neutralize the chlorides and
bring this percentage down, and if they can maintain a pH of 6-8, they will
be able to sell the filtercake to a smelter rather than having to pay the
smelter to take it.  They are wondering if adding hydrogen peroxide or soda
ash to their process, or some other process change, might do the trick.

This is outside our area of expertise.  So if any of you have suggestions we
would greatly appreciate it.


Ted Lange
Pollution Prevention Program
Montana State University Extension Service
P.O. Box 173580
Bozeman, MT 59717-3580
406-994-6813 (phone) / 994-5417 (fax)

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