US4222997-Method of recovering hydrochloric acid from spent hydrochloric acid pickle waste

[75] Inventor:
[73] Assignee:
_
Brazier K. Beecher, Wyandotte,
Mlch' I
[57]‘
ABSTRACT
A method of recovering hydrochloric acid from spent
Voss Steel Corporation, Taylor,
densed. Simultaneously and as a separate process, the
tem. First, hydrochloric acid availability has been mate rially reduced with a corresponding increase in cost throughout the industry. Second, the heat or energy
hydrogen chloride and the fractionated hydrogen chlo necessary to operate a recovery process is less available 5 ride are added together and stored. Furthermore, the
[21] Appl' No" 19’033 [22] Filed: Mar. 9, 1979 [51] Int. (:1.2 ....................... .. c0113 7/01; C01G 49/14
[52] us. (:1. .................................. .. 423/481; 423/488;
and at an increased cost. Third, the environmental dis
ferrous sulphate monohydrate formed in the double exchange reaction is ?ltered out and stored.
In one embodiment of the process, the condensed
ing the concentrated under?ow stream of strong pick ling waste with preheated concentrated sulphuric acid
in a double exchange reactor. The hydrogen chloride
3,131,110 4/1964 Duval _ _ ' _ _ _ _ . _ _ _ _ _ . ' _ “ 203/12
3,635,664
1/1972
Morimom _ _ _ _ _ _ _ _
_ _ _ __ 423/438
remaining products of the double exchange reaction are
Mich.
hydrochloric acid pickle liquor is used to increase the
amount of hydrochloric acid recovered and to improve the form of the waste products for better handling and
The regeneration of hydrochloric acid pickling
waste, which involves the recovery of hydrochloric
acid from waste left after a pickling operation on vari ous steel products, has led to three primary areas of concern regarding the operation of the recovery sys
to operate the concentrator and the heat exchanger.
The overhead stream from the fractionator has a
The prior art method for treating hydrochloric acid
pickle waste as illustrated in US. Pat. No. 3,635,664 to Morimoto issued Jan. 18, 1972 involves an addition of
able energy in various forms throughout the recovery liquid as a sulphuric acid source. The Morimoto patent 30 system. Additionally, the recovery process of the pres uses flash distillation to vaporize the hydrochloric acid
while separating out the precipitated ferrous sulphate from the residual liquid and circulating the resultant
overhead from the reactor is used as a source of energy
posal of waste hydrochloric acid pickle liquor is becom
ing a critical factor in all systems designs.
for addition to the fractionated hydrogen chloride. The
U5, PATENT DOCUMENTS 1897 996 2/1933 Barstow ............................. .. 423/488 2i437:29O 3/1948 Bottenberg ” 423/488
reduced energy costs. The waste pickle liquor from the pickle line is ?rst concentrated before the liquor is re ache‘! in ,e double exchange PmeSS with Strong, Shh
pickling liquor. Then the overhead stream is separated into water vapor and hydrochloric acid by using a frac
tionator. The next step involved in the process is react
sulphuric acid to the hydrochloric acid pickling waste
to convert FeClz in the waste to HCl and FeSO4. Then
trace of hydrogen chloride. The heat in this vapor is used in the pickle line or it is used to preheat the sul phuric acid going to the reactor. This use of internal
-by means of a fractionator with the underflow of strong
[56]
References Clted
pickle liquor being fed to the double exchanger reactor
to be mixed with the sulphuric acid. The overhead from the reaction process which consists of hydrogen .chlo' ride and water vapor 1s condensed and made ava1lable
heat supplied by the process substantially improves the
energy efficiency of the method of the present invention the resulting mixture is distilled to vaporize substan in recovering hydrochloric acid from hydrochloric acid tially all of the HCl together with the water and to 25 pickle waste. Because the sulphuric acid does not have precipitate the ferrous sulphate. Finally, the HCl and to be concentrated in the mother liquor for reuse in the water are condensed to recover hydrochloric acid process, the process of the present invention operates at
?ltered to form ferrous sulphate monohydrate crystals.
FOREIGN PATENT DOCUMENTS ‘
177444 3/1922 United Kingdom ................... .4 423/558
8 Claims, 1 Drawing Figure
_
into two streams consisting of an overhead vapor Stream and an under?ew of “mg Pickle liquer- The overhead vapor stream separates out hydrochloric acid
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1
4,222,997
2
METHOD OF RECOVERING HYDROCHLORIC ACID FROM SPENT HYDROCHLORIC ACID PICKLE WASTE
BACKGROUND OF THE INVENTION
liberated by the double exchange and the hydrogen
chloride and water vapor from the concentrated pick ling waste is circulated away from the reactor and con
Uit
Beecher
tates
atent 1191
[11]
’ 4,222,997
[45]
Sep. 16, T980
[54] METHOD OF RECOVERING
HYDROCHLORIC 4cm FROM SPENT HYonocHLomc ACID PICKLE WASTE
Primary Examiner-Brian E. Hearn Attorney, Agent, or Firm--Cullen, Sloman, Cantor, Grauer, Scott & Rutherford
Phhhe we‘ The eeheehheter Separates the Week Plekle
423/558; 423/DIG_ 1; 134/12; 134/13; 203/12 [58] Field of Search ....... .. 423/481, 488, 55s, DIG. 1; 1334/12, 13; 203/25, 12