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Re: INFOTERRA: HCl + H2SO4 pickle liquors waste mgmt with ze
There can never be true "zero discharge" at a steel pickling operation
because the iron which is removed as scale from the pickled steel must
be rejected from the process.
For spent sulphuric acid pickle liquors, the typical waste reduction
solution for a small pickler is to install an acid recovery system and
generate ferrous sulphate crystals for sale (or precipitate the iron
as a hydroxide sludge for disposal).
For spent hydrochloric acid pickle liquors, some small pickling
operations neutralize the residual acid and send the solution to a
nearby sewage treatment plant where the iron chlorides are beneficial
for phosphate removal. Others send the spent pickle liquor to larger
steel mills who have the roaster which can recover hydrochloric acid
and generate iron oxides for re-use.
I did hear of one U.S. steel mill that ran a process which recovered
HCl from spent pickle liquors through the precipitation of first
ferrous hydroxide and then calcium sulphate. Another tried a process
that recovered HCl through the addition of sulphuric acid and
evaporation of HCl gas, but it shut down because of extreme corrosion
I hope this is helpful.
2 Tippett Rd.
______________________________ Reply Separator _________________________________
Subject: INFOTERRA: HCl + H2SO4 pickle liquors waste mgmt with zero
List-Name: P2Tech at INTERNET
Date: 8/28/97 6:06 PM
P2 Techers: I am forwarding to you this request that was sent to the
Infoterra listserv, along with my response, in case any one has some
additional info they would like to pass on to the original sender.
>Date: Thu, 28 Aug 1997 15:02:58 -0500
>From: Alejandro Fernandez <email@example.com>
>Organization: Universidad de los Andes
>Subject: INFOTERRA: HCl + H2SO4 pickle liquors waste mgmt with zero
>Reply-To: Alejandro Fernandez <firstname.lastname@example.org>
>Can someone help me? I am interested in options for management
>(treatment, recovery) of pickling liquors wastes from wire
>manufacturing. The tricky part is that a "zero-discharge" condition must
>be contemplated in the analysis. A volume of up to 120 m3 must be
>managed, 50% from HCl pickling liquor and 50% H2SO4 pickling liquor
>(waste stream separation has not been implemented yet but is being
>considered for the near future).
>Hydrolisis for HCl and Fe oxide recovery appers to be financially out of
>I would greatly appreciate any information that may assist to address
>this challenge. Please send responses directly to sender. Thank you in
>Alejandro Fernandez, PE, QEP, CHMM
Several years ago I helped a company in Seattle prepare a pollution
prevention and they had the same problem as you, and a very interesting
solution. The Davis Wire Company had to dispose of high volumes of acid
from wire pickling. Previously they had been neutralizing it for sewer
disposal. However they found out that sulfuric acid is a primary ingredient
of certain kinds of fertilizer, and iron contamination of the fertilizer is
not a problem since the stuff is applied to the soil from whence comes the
minerals anyway. So they purchased a small fertilizer production facility
and put it at the end of the pickling liquor drain, and they sell the
fertilizer they make to farmers in Eastern Washington. Their engineer told
me they seem to make more profits from fertilizer sales than from wire sales
and he was wondering what industry he was in! Hope this inspires some
creative thinking for your clients.
Asian Institute of Management