ELECTROLYTIC RECOVERY OF VANADIUM, MOLYBDENUM, AND GALLIUM FROM ALUMINATE LIQUOR

RECUPERATION ELECTROLYTIQUE DE VANADIUM, DE MOLYBDENE ET DE GALLIUM A PARTIR D'UNE LIQUEUR D'ALUMINATE

English Abstract

ABSTRACT OF THE DISCLOSURE
The invention relates to a new method for simultaneous recovering
vanadium, molybdenum and gallium from alumina factory aluminate liquor compris-
ing an aqueous sodium aluminate solution. The recovering is carried out in one
step by electrolyzing the aqueous sodium aluminate solution at a temperature
exceeding 70°C with a direct current having a current density of from 400 to
1200 A/m2 using a low-melting liquid alloy as a cathode and agitating said alloy
mechanically. The gallium is alloyed into the cathode in the course of the
electrolysis. By using the new process vanadium, molybdenum and gallium can
be recovered simultaneously in one step with good efficiencies without any
preliminary treating of the aluminate liquor and without using any anxiliary
chemicals.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for recovering vanadium, molybdenum and gallium from aluminafactory aluminate liquor comprising an aqueous sodium aluminate solution char-
acterized in accomplishing the recovering of said metals together, in one step
by electrolyzing the aqueous sodium aluminate solution at a temperature exceed-
ing 70°C with a direct current having a current density of from 400 to 1200 A/m2,
the electrolysis being performed using a low-melting liquid alloy as a cathode
and agitating said alloy mechanically, and the gallium being alloyed into the
cathode in the course of the electrolysis.

Description

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The inventlon relates to a new process for recovering molbdenum,
gallium and vanadium from alumina factory aluminate liquor comprising an aqueoussodium aluminate solution. According to the invention the above-mentioned metalsare recovered together, in one step by electrolyzing the aqueous sodium aluminate
solution at a temperature exceeding 70C with a direct current having a density
of from 400 to 1200 A/m2, the electrolysis being performed using a low-melting
liquid alloy as a cathode and agitating said alloy mechanically, and the galliumbeing alloyed into the cathode in the course of the electrolysis.
Several methods are known for recovering gallium from aluminate liquors.
Nowadays the "direct" recovering process0s are generally used. Such "direct"
processes are .e.g the mercury-pool cathode process (disclosed in Hungarian
patent 145,729 and United States Patent Specification 2,793,179), electrolysis
accomplished by using a liquid gallium cathode ~disclosed in French patent
1,418,513) or by using a solid cathode ~described in Hungarian patent 156,992
and United States Patent Specification 3~677,91&), extraction with organic sol-
~,.
vents ~disclosed in Hungarian paten~ 164,521) and cementation by gallium-
aluminium alloy (described in United States Patent Specifica~ion 3,988,150,
Union of Soviet Socialist Republics Patent Specification 263,154, 329,792 and
510,848),
The methods for recovering vanadium from alumina actory aluminate
liquors are particularly based on crystallization. Such methods are disclosed
~ e.g. in the following publications: ~svald, Z., Skuteczky,
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Eoll 2~mb~, J~g Tot;h, :Bs ~e~ipari Kutatointezeb Xozle-
i IProoceding of the l~etallurglcal I~dustry
~searoh In~titute , published in Hungar.y~, VO t 53~62
(1961~ Tara~enko, ~Z~, Zazubin~ Io~ P~nomare~rD Y~
Baespalo~ 13O1~ $rudi Inst .. Met . i ObogashohO
Akad~ ~suk~. Kaz, SSR, ~ 66-74, (1968) ,, Juh~sz, ~s
~oh~atl Iapok IMetallurgical P~riodical~., published
ln ~Iungaryl, ,~,, 161-168, (1958). Chemical a2ld eleotro-
che~loal redu~tio~ ~se~hods are al~o u~ed~ suoh r~thod~
are di~clo~ed e ,g~, i n US PS 3 677 918 and USSR PS 431
752, a~d in the ~ollo~ing publi~atioIls: Za~ubin9 A.,I.
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3Boookarev, BoAog Rorllanov9 &oA~ s Trudi In~t~ Met.. i
()boga~hoh. klcad.. ~auk O Eaz. S5R~, 27, 79~85, (1968) D
Sla~ina, 3,~. D Ivanova, G.A.: Ibid.. 9 17, 20-26, (1966~,
Meth~d ~uitable for rec~Yering ~olybdenum
: ~ro~ alu~ina factory aluminate liquor i~ not yet kno~n~
~ : Each ~entioned process, tho~gh ~eve.ral o~
he~ are u6ed in ~actorie~ e~en now, has oertQin
te~hnl~al i~per~ect~es3a~0 Por recove~ing the galliu~
.
~ the lndustrlal aluminate li~uor must always be suboitted
i to a preli~inary p~r~ioatio~ and the reco~ering pr~ces~
i~ ac~o~plished by u3ing pol~onous o~ e.xpen~i~e reagents
8~ ~lumi~ium, or~anic ~xtracting agent)0 In ca~e of
' reoo~eri~ ~anadiu~ the cost~ o~ inve~t~e~t aoncernlng
~ the heating and cooling ~y~te~s, and the cost~ of the
¦ I ~p~olal ~hc~i¢al~ re~ult in a high production co~t.
~ The pri~ary di~advantage of each known recoverillg
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process lies in the fact that the sufficiency of these processes depends mainly
on the technical circumstances of alumina processing ~e.g. presence of organic
materials, other inorganic impurities, concentration rates), and for this reasontheir general use requires carrying a separate adaptation experiment.
The purpose of present invention was to provide a new recovering pro-
cess which can successfully be appied without being dependent basically on the
alumina processing technology and without harmPully influencing that, further-
more recovering the metals with a lower production cos~, and eliminating the useof poisonous andjor expensive reagents.
In accordance with the foregoing present invention relates to an
electrolytic process which provides the recovery of vanadium, molybdenum and
~; gallium simultaneously. In case the process according to the invention is
applied, the aluminate liquor from which the metals are recovered need not be
submitted to any preliminary treatment ~e.g. cooling, removing impurities).
The process is perormed in an electrolyzing cell made of a proper material,
using a low-melting alloy as a cathode - its composition can be e.g. 50% bismuth,
25% lead, 12.5% tin and 12.5% cadmiw.l - and an alkali-insoluble metal surrounded
by an alkali-proof diaphragm as an anode. The temperature oP the electrolyzed
aluminate liquor must be above 70C. In order to reach a high recovering effic-
iency and to recover vanadium, molybdenum and gallium together the cathode
current density is maintained between ~00 and 1200 A/m2 and the cathode is
agitated mecham cally~ In the course of electrolysis vanadium and molybdenum
form alkali-insoluble precipitates in form of lower-valent oxides, while galliumis alloyed into the cathode metal.
Summarizing the aclvantages of the process according to our invention
there are as follows: vanadium, molybdenum and gallium can be recovered in one
; step from alumina factory alum m ate liquors; the aluminate liquors need not be
~; submitted to any preliminary treatmenti accomplishing of the process requires
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only electric energy and no other anxiliaries or chemicals are necessary.
The following examples illustrate the process according to the inven-
tion without delimiting i*s scope.
Example 1
Industrial aluminate liquor containing 1 g/l vanadium pentoxide, 0.2 g/l
molybdenum and 0.15 g/l gallium was electrolyzed at a temperature of gOCC for
two hours with 800 A/m2 current density~ the cathode being agitated. The surface
of the cathode was 20 cm2, the volume of the electrolyzing cell was 150 ml. After
finishing the electrolysis 0.04 g/l vanadium pentoxide, 0.0l g/l gallium and
0.08 g/l molybdenum remained in the solution. On the basis of this data the
recovering efficiencies are as follows:
vanadium pentoxide 97%
~; molybdenum 60%
gallium 95%
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Example 2
Industrial aluminate liquor containing 0.71 g/l vanadium pentoxide,
0.3 g/l molybdenum and 0.18 g/l gallium was electrolyzed at a temperature of
90C for two hours with 1000 A/m2 current density, the cathode being agitated.
After finishing the electrolysis 0.041 g/l vanadium pentoxide, 0.08 g/1 moly-
bdenum and 0.1 g/l gallium remained in the solution. On the basis of this data
the recovering efficiencies are as follows:
vanadium pentoxide 94%
molybdenum 73%
galliwn 39%
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