Patented Mar. 28, 1950
‘2,502,327
UNITED STATES PATENT OFFICE
2,502,327
SEPARATION OF ALUMINUM CHLORIDE
AND FERRIC CHLORIDE
Ignace J. Krchma, Wilmington, and Holger H.
Schaumann, Newark, Del., assignors to E. I. du
Pont de Nemours & Company, Wilmington,
Del., a corporation of Delaware
No Drawing. Application February 18, 1948,
Serial No. 9,326
7 Claims. (01. 23—93)
1
2
This invention relates to a separation process
and more particularly to a method for separat
ing aluminum chloride from a substantially an
hydrous mixture of ferric chloride and aluminum
component of anhydrous mixtures of aluminum
in catalysis.
property of titanium tetrachloride for separation
into its component parts of a mixture comprising
chloride and ferric chloride. Aluminum chloride
is soluble to the extent of about 283 grams per
liter of TiCli at 137° C. and 17 grams per liter at
25° C. Ferric chloride is substantially insoluble
chloride.
1
in both hot and cold titanium tetrachloride, the
Aluminum chloride is a valuable chemical prod
solubility being less than about 0.5 gram per liter.
uct for such applications as catalysis, mordant
These data show the large temperature co-ef?
ing and pigment treatment. Contamination with
cient of solubility of aluminum chloride in titani
an iron salt in these and other uses is detrimental
because iron salts impart discoloration in dyeing Y 10 um tetrachloride and the selectivity of the sol
vent. In our invention we utilize this selective
and pigment applications and reaction variability ‘
,
In the preparation of aluminum chloride from
an aluminiferous ore, vapors of ferric chloride,
silicon tetrachloride and titanium tetrachloride
may be formed during chlorination from the im
purities present in the ore. The ?rst two named
chlorides are readily separated from the last two
ferric chloride and aluminum chloride.
In a speci?c embodiment of our invention, the
anhydrous mixture of aluminum chloride and
ferric chloride is treated in a contacting vessel
with the titanium tetrachloride solvent. This
contacting vessel may be equipped with means
by fractional condensation because their boiling
points are considerably higher; but subsequent 20 for supplying heat for increasing the tempera
separation of the aluminum chloride from the
ture of the mixture; means for condensing and
ferric chloride cannot thus be effected. Mixtures
returning any vaporized titanium tetrachloride
of anhydrous aluminum and ferric chlorides are
also collected when titaniferous materials, con
taining iron and aluminum values, are chlori
nated. The chlorination of contaminated scrap
which is released from the mixture by such heat
ing; and means for discharging the solids and
aluminum produces aluminum chloride often
containing iron chloride as an impurity.
Aluminum and ferric chlorides normally are
sublimable solids. They condense as solids from
their vapor state upon cooling; but their subse
quent separation by sublimation is very di?icult
if not practically impossible. Heretofore many
other methods have been advanced for effecting
this separation. Most of these are based upon
conversion of the ferric chloride to the less vola
tile ferrous salt or to metallic iron by reduction
with an active metal. The aluminum chloride is
is dissolved by the titanium tetrachloride solvent,
the liquid solution resulting from the contacting
operation. In the vessel the aluminum chloride
and the ferric chloride and other insoluble mate
rials remain as solids.
After solution is com
pleted, the solids and liquid are discharged from
the contacting vessel into a separator, for in
stance a centrifuge which by centrifugal action
separates the undissolved ferric chloride fraction
from the titanium tetrachloride solution con
taining the aluminum chloride. The solution is
then discharged into a cooler and crystallizer
wherein the temperature is lowered until the
aluminum chloride crystallizes out. The con
then sublimed from the iron metal or ferrous
tents of the crystallizer are then transferred to
4.0 another separator which removes the solid alu
salt. Such methods are costly, however.
One of the objects of this invention is to pro
minum chloride crystals from the titanium tetra
vide a method of separating aluminum chloride
chloride solvent. The latter may then be re
from a substantially anhydrous mixture of alu
cycled for use in dissolving more aluminum chlo
minum chloride and ferric chloride. Another ob
ride.
The two solid products, one composed of
ject is to provide a method of obtaining aluminum 45
ferric chloride, the other of aluminum chloride,
chloride substantially free of ferric chloride im
are then separately heated to remove adsorbed
purity. A further object is the solvent extrac
titanium tetrachloride. The adsorbed solvent is
tion of aluminum chloride from a substantially
recovered from this operation and combined with
anhydrous mixture of aluminum chloride ‘and
the titanium tetrachloride being recycled for fur
ferric chloride, wherein the aluminum chloride is
ther extraction.
protected from contamination by moisture. Oth- .
The following are typical ferric chloride-alu
er objects will become apparent as our process is
minum chloride mixtures which are advanta
described.
geously treated by means of our invention: (All
We have found that titanium tetrachloride is
a selective solvent for the aluminum chloride 55 percentages are by weight.)
2,502,327
3
4
(1) Solid chlorides condensed from the prod
yield a solid mass containing the ferric chloride
and a solution containing the aluminum chloride.
The solid mass was treated again in the same
way using 86 parts of T1014. The two titanium
ucts of chlorination of Indian titaniferous ore:
'7
TiCl4
Per cent
________________________________ __
1.35
chloride-aluminum chloride solutions were com
FeCl3 ________________________________ __ 78.6
FeCl-z ________________________________ .__
Alkaline earth chlorides _______________ __
3.38
A1C13
2.51
________________________________ __
bined and subsequently cooled to 20° 0. to crystal
lize out aluminum chloride. The aluminum
‘chloride crystals were then separated from the
titanium tetrachloride solvent by ?ltration. The
1.77
Residue (coke-ash, etc.) _______________ __ 12.40
(2) Solid chlorides condensed from the'prod
ucts of chlorination of slate from titaniferous
10 twov solid products of FeCls and A1013 were sep
arately treated by heating in a distallation unit
'as was done. for the Fe0l3 in Example I, to re~
iron ore:
move adsorbed titanium tetrachloride. The yield
of. this experiment is shown by the following
table:
Fe0l3 _________________________________ __ 58.1
-Fe0l3 fraction, 73 parts contained 2.1% A1013.
A1013 ___________________ __' ____________ __ 28.5
A1013 fraction, 24.9 parts contained less than
Residue (coke-ash, etc.) ________________ “10.4
.28% FeCls.
(3) Impure A1013:
Ti0l4 solvent (to be recycled), 260 parts con~
Per cent 20
tained about .'76% A1013.
A1013 _________________________________ __ 89.0
A1013 yield=24.9/28.5=.875><100=87.5 %.
..
MgClz
Per cent
________________________________ -_
3.0
Fe0l3 _________________________________ __
7.5
‘Residue (oxides'and ash) _______________ __
3.5
Example III
The following. examples are illustrative of the
100 parts of impure A1013 of type (3) above
modeof our invention and are meant in no way
were added to the vessel as in Example I, heated,
re?uxed and stirred with 605 parts of TiCli.
After this treatment the hot liquid portion was
removed. About 680~parts of a Ti'Ch solution of
A1013 were obtained, free of the FeCls undis
solved solids. vThis. solution was cooled to 25° C.
to be limitative thereof:
(All .parts are by
weight).
Example I
100parts. of the mixture of ferric chloride. and
aluminum chloride given as type ‘(1), above, were
extracted with an equal weight of titanium tetra
to crystallize out the A1013. The solid A1013
and liquidTiCh were separated by centrifuging.
chloride. This operation was carried out in a
vessel equipped with a re?ux condenser, and agi
The solids were separately treated as above to re
move .the adsorbed titanium tetrachloride. The
tator and, heating means. ‘The mixture of solids "
vyieldsin this experiment are vtabulated below:
and titanium tetrachloride was heated to between
about 100°jand 137° C. and agitated for about
15 minutes. After this treatment‘withxthesol
vent, the solids were allowed to settle and vthe‘hot
'83 parts AlC‘ls containing less than-2% Fe013.
11.5 parts of solid ‘residue containing the 'FeCls.
‘600 parts of TiCh containing about ‘96% A1013.
liquid portionwas‘removed. About 80 parts of 40
'TiCli solution Were obtained. This hot TiClc
containing the AlCl3rwas transferred to a dis
material is low, was carried out to make the re
*
The method‘ of our invention isapplicable to
mixtures‘ of ferric chloride and aluminum chloride
produced from many di?ferent operations. Men
tillation unit and the T1014 was distilled over
and condensed in. a collection vessel. This step,
advisable when the A1013 content of the starting
" This solvent to bev recycled.
'AlCla recovery 83/89=.94>'<100=94%.
' .tion has been made of impure aluminum chloride
and of products of chlorination of titaniferous
covery of A1013 substantially complete. ' Since
ores or slags containing iron and aluminum.
Other; chlorination products from raw materials
the volume of solvent used was low, the amount
of'FeCls contamination remaining 1in the A1012
such as-aluminous clays containing titanium and
was also low. The ferric chloride solid residue 50 iron values or. from any operation where anhy
remaining after the ‘extraction contained some
drous iron and aluminum chlorides are obtained,
‘adsorbed titanium tetrachloride. This residue
may be advantageously treated by our new
was separately treated by heating in. a distillation
method.
vessel eouip-ped with a rwater~cooled condenser.
The-individual operations in~our invention may
The aces-bed titanium tetrachloride was-:dis
’ take on widely di?erent variations. The leach
til-led from the solidsand'the last trace was re
ing phase can be. carried outin various types
’moved by blowing dry air throughthe distillation
outfit. These operations gave ‘the following prod
of. equipment andmay include steps of mixing,
grinding, washing, percolating and leaching. The
main element is to insure adequate solubility
11161352
.(A) Fe0l3portion--96.2 part-s ‘containing about
.6% A1013.
'
.(B). Aron-1.9 parts containing less than 1.0%
FeCls.
. A1013 recovery. about 1.9/2.5=.76.%.andin re1a~
tively pure. condition.
Ea'tmtple II
we parts of the solid chloride condensation
product from the chiorination of a .titaniferous
ore slag, type (2) above, were addedto. the con
tacting vessel used in Example I. '173, parts of
titanium tetrachloride were also added. This
mixture was stirred andheated until ‘the alumi_
num chloride content was ‘dissolved. The‘ hot
products were then separated by ?ltration to
60
of the aluminum. chloride in the T1014. The
temperatures used in the operation may be varied
when ‘limited by available heating and/or cool
ingagent temperatures. 'Of course, some leach
ing wil be ‘effected at as low as 25° 0., where A1013
is, soluble to the extent of. 1'7. g./l.; and conversely,
some crystallization from a solution saturated at
sayv v13'7" ‘0., will occur upon cooling even slightly
below that temperature. It is preferred to oper
ate. at above 100° 0. for solubilizing and below 50°
C. for crystalli'zing, however, because the amount
of purified A1013 obtained per operation, and thus
‘the practical economics of the process, will de
pend, with a givenamount of solvent, upon this
temperaturedifference. Treatments at tempera
ture‘ above about'137°‘ 0.‘need" to be conducted
9,562,222?
5
6
tures may be carried out by various well known
the undissolved material, cooling the solution to
crystallize out the aluminum chloride, and sub
sequently freeing the aluminum chloride crystals
procedures including settling, ?ltering, centri
fuging and thickening. The crystallization step
of TlC14.
5. In a method for purifying substantially an
may be varied by changing the temperature and
rate of cooling to effect changes in the type of
aluminum chloride crystals obtained. Care must
be exercised during all operations to insure elimi
nation of moisture from the reaction vessels be 10
hydrous impure AlCls, the steps of dissolving the
141013 in heated TiC14 and separating the T1014
under pressure because of the volatility of the
TiCl4. The two separations of solid-liquid mix
cause of the extreme reactivity of all materials
with water. Our invention may be carried out
in either batch or continuous fashion. It is
AlCls solution from the undissolved material.
6. A method for recovering aluminum chloride
from an anhydrous mixture with ferric chloride
which comprises contacting said mixture at an
elevated temperature with titanium tetrachloride
solvent, and until the aluminum chloride becomes
apparent that multiple puri?cation operations on
dissolved in said titanium tetrachloride, separat
the same charge will result in a very pure AlCl: 15 ing the resulting hot solution of aluminum chlo
ride in titanium tetrachloride from the undis
product, and that the number of such operations
solved ferric chloride, cooling said solution to
will depend on economic considerations.
below 50° C. and recovering the aluminum chlo
We claim:
ride crystals from the solvent.
1. A method of removing aluminum chloride
'7. A method for recovering aluminum chloride
from an anhydrous mixture comprising aluminum 20
from an anhydrous mixture with ferric chloride
chloride and ferric chloride which comprises dis
which comprises subjecting said mixture to con
solving the aluminum chloride in titanium tetra
tact with titanium tetrachloride at temperatures
chloride.
ranging from about 100-137° C. with accompany
2. A method of separating aluminum chloride
from an anhydrous mixture comprising alumi 25 ing agitation for a period of about 15 minutes,
separating the undissolved ferric chloride from
num chloride and ferric chloride which com
the resulting solution of aluminum chloride in
prises leaching the said mixture with heated ti
tanium tetrachloride, separating the resulting
titanium tetrachloride, and thereafter recovering
said aluminum chloride from said solution by
30 cooling the latter to below 50° C. and removing
the aluminum chloride crystals from the cooled
tion, and recovering the aluminum chloride by
solution.
cooling the solution.
IGNACE J. KRCHMA.
3. A method of separating aluminum chloride
HOLGER Hi SCHAUMANN.
and ferric chloride which comprises contacting
a mixture of said chlorides with titanium tetra 35
REFERENCES CITED
chloride solvent, heating to above 100° C., separ
ating the undissolved ferric chloride, cooling the
The following references are of record in the
solution to below 50° C. and removing the alumi
?le of this patent:
num chloride crystals from the solvent.
UNITED STATES PATENTS
4. A method of purifying impure anhydrous
aluminum chloride containing ferric chloride
Number
Name
Date
which comprises dissolving the aluminum chlo
2,245,358
Pechukas _________ __ June 10, 1941
ride in heated titanium tetrachloride, separating
2,387,228
Arnold ___________ __ Oct. 23, 1945
solution of aluminum chloride in titanium tetra
chloride from the undissolved ferric chloride frac