Note: Descriptions are shown in the official language in which they were submitted.
S~37
The present invention relates to processes for elec-
trolytic recovery of gallium or gallium and vanadium
from alkaline liquors resulting from alumina production.
The process of the present invention is useful in
the manufacture of gallium or gallium and vanadium from
alkaline liquors resulting from alumina production which
liquors contain aluminates, carbonates, silicates, vana-
dates, gallates, phosphates, molybdates, zincates, ferrites,
chlorides, fluorides, polyvalent-sulphur compounds with al-
kali metals, as well as organic compounds.
Gallium and vanadium, owing to their valuable specific .
properties, find an extensive use in such industries as
nuclear energy, electronic and semi-conductor instrument
manufacture, rocket engineering, metallurgy, optics and
medicine.
The direct production of gallium from ores is not com-
mercially implemented. Gallium is produced from productsfrom processing buaxites to alumina which contain substan-
tially
i
,,
j 35
.. . . .
,, ' ' : -
,, .: .
,
g'7
-2-
the rollowing components, per cent by ~ ~ alumina 50-60,
iron oYides 15-25; silica 2-5; calcium o~ide 1-3.
In addition to these comp~nents a number oi rare ele-
ments are present in bauxites including 1-2 kg/ton oi vanadium
pento~ide and 0.02-0~07 kg/ton Or gallium.
Processing oi bauYites by the Bayer's ~ethod comprises
leaching o~ aluminium o~ldes contained in the core, by means
Or a solutian of caustic soda. At the same time, into the re-
sulting aluminate solution gallium passes i~ an amount of abo-
ut 75 per cent by mass in the ~orm o~ sodium gallate. Upon de-
composition of aluminate solutions the predominant amount of
gallium remains in the solution due to the formation of more
durable, compared to aluminium, comple~ compounds (mother alu-
minate liqu~r). ~he mother aluminate liquor, after separation
oi aluminium hydroYide, is evaporated to a return aluminate li-
quor and reeycled to leaching oi a new portion oi bauxite.
During circulation these liquors get enriche~ in gallium.
Under stationary proces~ conditioas gallium concentra-
tion in liquors becomes constant and varies within the range
o~ from 0.15 to 0.50 g/l. ~he concentration value depends on
the cont~nt oi gallium in bau~ite, bauYite composition and pro-
cess technology employed in alumina production.
In a similar manner proces~ing oi vanadium is per~ormed
11 ~8 5
in the above-dsscribed Bayer ~9 method.
- ~here~ore, ~or a commercial production oi gallium and
vanadium rrom bauYite~ as the ~tarting materials use can be
made o~ alumi~ate liquors.
Enown in the art is a process ~or a direct recovery
o~ gallium ~rom alkaline lLquors re~ulting ~rom alumina pro-
duction o~ a mercury cathode ~J. of ~etals, 1956, 8, p. 1528;
/est G~A~
. SWi8S Patent No. ~33,264; 1958i~g~ Patent No. 1,051,827;
1959~. -
In accordance with this process, the mother aluminate
liquor resulting from the Bayer's process is subjected te
electrolysis on a liquid mercur~ cathode and nickel a~ode.
~he electrolysis is conducted under the ~ollowing conditions:
anodic current density 1,000-1,200 A/m2, cathodic current
densitg, 35 to 45 A/m , duration o~ electrolysis 24 hours.
Under the~e conditions gallium is reduced on the cathode and
diffuses into the bulk o~ mercury. To ~acilitate the processes
oi di~u~io~ and renewal o~ the cathode sur~ace, an intensive
agitation of the liquor and mercury is eirected. The electro-
ly8is i8 stopped when O.5-1.O~0 by mas~ of gallium amalgam is
obtained, since ~olubilitg o~ gallium i~ mercury at the tem-
perature of 50C is L 5% by 4~. Gallium amalgam i~ decomposed
by means of a ~olution oi caustic soda at the boiling tempera-
.
~lS8597
ture o~ the resulting solution in the presence of metallia
iron. a~ter carryi~g out ~everal abo~e-mentioned operatio~s
0i the amalgam deGomposition, the co~tent o~ gallium in the
resulting gailate solution is as high as 30 to 80 g/l. From
this solution gall~um is recovered in an electrolyzer with
~ ic ~
a steel,/niokol/,or liquid gallium cathode.
This process, however, reatures a low r~te o~ t~e pro-
G cess Or gallium recovery, the use Or ~ ~ophisticated process
eguipment, large amounts of mercury empl0yed i~ circulation
(up to 3,000 kg in the case oi a ilat-bottom electrolyzer).
Furthermore, mercury is an excellent collector ior a number
oi metals there~ore, the thus_produced gallium is generally
strongly contaminsted w~h iron , nickel, lead, copper, molyb-
denum.
It should be also ~oted that mercury employed tn this
prior art proce~s has a high toYicity, while t~e rate o~ con-
sumption oi mercury in the process is 2 kg per one kg oi gall-
iu~. De~pite the severe measures ~or ensurin~ sa~ety oi ope-
ratio~ wit~ mercury, the operating perso~cl ~ rrom time to
time withdrawn irom the main production shops. Another problem
as~ociated ~ith the production 0r gallium by thi~ prooess is
la¢~ oi u~ers oi the va~adium slime co~taminated with mercury
, ~ ~
- , ~
5~-~
which is simultaneously obtained as a by-product.
To reduce the amount of the mercury employed, Landi
(Italy) has proposed an improved design of the electrolyzer,
wherein a rotary cathode is used in the form of a hollow
steel drum with the surface thereof coated with a thin layer
of mercury (Aluminio, 195g, 5, 219).
Also known in the art is a process for a direct elect-
rochemical recovery of gallium on a solid cathode fromalkaline liquors resulting from alurnina production (cf. US
Patent No. 3,667,918; 1972).
This process comprises recovery of gallium from said
liquors by electrolysis using, as the cathode, steel, lead,
or copper. As the anode use is made of steel, nickel or
graphite. The electrolysis in this process is conducted
under the following conditions: cathodic current density
1,000 A/m2, voltage 4 V, temperature 60-80C.
The electrolysis is conducted after a preliminary ef-
fective purification of the liquors from impurities hind-
ering recovery of gallium, namely: vanadium, iron, copper
and organic compounds.
Purification from vanadium is conducted by way of
reducing soluble pentavalent vanadium compounds to tri-
valent compounds insoluble in alkaline solutions.
3 ~ ~
The reduction is effected by the addition, into the
starting alkaline liquor resulting from alumina produc-
tion, of sodium hydrosulphite at a temperature of from
60 to 80C under vigorous stirring. Reducing said vanadium
compounds can also be effected by means of hydrogen which
is obtained both by dissolution of granulated aluminum in
the aluminate liquor and electrolysis of alkaline liquors
with the use of amalgamated cathode. Satisfactory results
are obtained also with the use of membranes made of un- -
glazed porcelain which are placed around the electrodes.
Impurities OL copper and iron are eliminated from said
liquor by reduction thereof with sodium hydrosulphite with
a subsequent filtration of the purified liquor; for the
removal of organic compounds the liquor is treated with
activated coal at a temperature within the range of from
60 to 80C at the rate of 1 g of activated coal per one
litre of the liquor.
This prior art process features the necessity of the
preliminary effective freeing of aluminate liquors from
impurities; sophisticated process equipment employed, a
low current yield of gallium (0.27%) and a high rate of
consumption of electric power (1,700 kW.hr per 1 kg of
gallium)
~,
s~
Another known process for electrolytic recovery of
gallium from aluminate liquors (cf. French Patent No.
2,237,991;1975; British Patent No. 1,436,260; 1976) com-
prises recovery of gallium at a cathodic current density
of from 20 to 500 A/m2 on a solid cathode manufactured from
a metal, whereinto reduced gallium diffuses till its con-
tent in the superficial layer of the cathode is equal to
0.1-0.5~ by weight. As the cathode material use may be
made of tin, lead, indium, zinc or an alloy of tin and
lead made as a thin plate with a thickness of from 0.01
to 0.3X 103 micrometers or as a thick block of said metals.
The cathode may be also made of an inert material such as
stainless steel coated with said metals to the thickness
of from 1 to 50 micrometers. As the anode use is made of
platinum, platinized titanium, stainless steel, nickel,
aluminium. The electrolysis is conducted at a temperature
within the range of from 25 to 80C.
Gallium is separated from the cathode by physical me-
thods or by treating the cathode with a molten flux con-
sisting of a molten alkali metal hydroxide at a temperature
within the range of from 220 to 800C.
This prior art process, however, has the following
disadvantages:
~:r - 7 -
~ ",
- 8 ~1~85~7
- a low rate of gallium recovery (the process duration
is as long as 20 hours) which is associated with diffusion
of.gallium into the bulk of the substrate metal;
- complicated process technology due to the use of
consumable cathodes;
- the use, as the consumable cathodes, of rarely-avail-
able and expensive metals;
- complicated and labour-consuming technology of reco-
vering gallium from the cathode material.
The present invention provides such a process for elec-
trolytic recovery of gallium or gallium and vanadium from
alkaline liquors of alumina production which would make it
possible to increase the degree of recovery of gallium or
gallium and vanadium and enable the use of starting materials
with substantially any contcnt of gallium and vanadium
therein.
According to the present invention there is provided
a process for electrolytic recovery of gallium or gallium
and vanadium from alkaline liquors resulting from alumina
production by electrolysis on solid electrodes, wherein,
said electrolysis is effected at a cathodic current density ~:
of from 200 to 1,000 A/m , at a voltage of 3.4 to 4.5 V and
at a tempjerature from 28 to 37 C in the presence of a metal
; ~rclimina~ily introduced into starting liquors which forms
an alloy with gallium when it is electrolytically reduced
together therewith (in the form of an electrolytic precipi-
tate), which is not passivated under the electrolysis condi-
tions, the concentration of such metal being between 0.15
and 5.0 g/l with th.e gallium concentration being between
0,15 and 0.5 g/l.
In accordance with the invention, a metal prcliminaYrily
introduced into starting liquors is a metal selected from
the group consisting of zinc, tin and lead. These metals
form precipitates containing gallium or gallium and vanadium
,; :-
.: f
' '
~s~s~
during electrolysis, owing to their electrochemical pro-
perties.
These metals are present in starting liquors in the
form of an oxide, soluble inorganic salt, or pure metal.
In the process according to the invention, for recovery
of gallium or gallium and vanadium, starting alkaline liqu-
ors of the alumina production for gallium recovery should
comprise a solution, selected from the group including
mot~er aluminate Bayer process liquor, recirculation alum-
inate Bayer process liquor, and mixture thereof, as well
as recirculation aluminate Bayer process liquor diluted
with water in a ratio (vol. ~):
recirculation liquor 10 - 90
water the balance.
This makes it possible to use liquors more concen-
trated in terms of gallium compared to aluminate mother
liquors and less concentrated compared to recirculation
aluminate liquors.
To improve the efficiency of the process of electro-
lytic recovery of gallium, the alkaline liquors of the
alumina production should comprise filtered liquor which
is prepared by repulping of sodium carbonate precipitate
formed from the Bayer process recirculation liquor during
its vaporization with water at between 50 and 100C.
~7
f~- _ g _
S~3';J
-- 10 --
In the process according to the present invention, upon
electrolysis of alkaline liquors resulting from alumina
production use is made of DC, pulsating current, reversible
current as well as various combinations thereof. This tech-
nique makes it possible to substantially increase the degreeof recovery and current yield of gallium or gallium and
vanadium, increase the content of these components in the
electrolytic deposit, as well as reduce the rate of power
consumption.
In order to eliminate contamination of the startin~
alkaline liquors resulting from alumina production and con-
tamination of the desired products ~gallium or gallium and
vanadium), in accordance with the present invention as the
~'
,
:
: .
." , " ~ ' ` ' ' ' ` '
3'7
.
electrodes used should be made of metals resistant in
alkaline media, i.e. steel, nickel, titanium. Said metals
possess a satisfactory adherence to the electrolytic de-
posit containin~ the metzlintroduced into the starting li-
quor and gallium, or gallium and vanadium.
In the process according to the present invention, for
increasing efficiency of the electrolytic recovery of gal-
lium or gallium and vanadium use is made of water-cooled
cathodes.
In the case where the starting alkaline liquor result-
ing from alumina production contains polyvalent sulphur
compounds it is advisable, for combining said sulphur com-
pounds, to charge said metal, apart from the above-spe-
cified amount thereof, into the liquor prior to the ele-
ctrolysis in an additional amount stoichiometric in respect
of the content of polyvalent sulphur compounds in the
starting liquor. This enables an additional purification
of alkaline liquors resulting from alumina production,
improve quality of alumina and make use of bauxites with
an increased content of pyrite minerals.
According to the process of the present invention, it
is advisable that the electrolysis be effected to a resi-
dual concentration of the metal introduced into the
starting liquors resulting from alumina production equal to
~7 - 11 -
; ,
:-: ' - , .. :
.
:
9~
-12-
0.020-0.005 g/l. This makes it possible to minimize contami-
nation of alkaline liquors resulting irom alumina production
with ~oreign impurities.
The process according to t~e present invention is simple,
efiective and integrall~ combined wi~ the production o~ alu-
mina; it makes possible to produce gallium or gallium and va-
nadium directly ~rom alkaline liquors resulting ~rom alumina
production o~ substantially any comp~sition, to use the start-
ing materials with both high and low content of gallium, vana-
dium 1 pyrite and carbonate minerals.
The process according to the present invention makes
it possible to eliminate the preliminary puri~ication of al-
kaline liquors resulting ~rom alumina productio~ ~rom impuri-
ties hindering electrolysis such as vanadiu~, copper, iron,
polyvalent sulphur compoundæ and organic compounds; eliminate
the use and consumption o~ to~ic (mercury) and expe~sive (tin,
indium, lead) materialæ; employ standard electrolyzers thus
makin~ it possible to combine recovery o~ gallium o~ gallium
and vanadium with a simultaneous p~rifioation of alkali~e li
~uors from harm~ul impurities (iron, lead, copper, titanium,
polyvalent sulphur compounds).
~ he proce~s according to the present invention can be
easily automated; it reduces capital e~penses ior the produc-
~lS8~
--13--
tio~ o~ gallium. The repay period o~ a plant producing annual-
ly 10 tons o~ gallium is not longer than one year.
The procéss according to the present invention is ei-
fected in the ~ollowi~g manner.
A9 the starting alkaline liquors resulting from alumi~a
produ¢tion use is made o~ the liquors obtained in processing
o~ bauxites b~ the sinterin~ method or Bayer's method.
It i9 preferable to use aluminate li~uors resulti~g from
Bayer's process owing to a higher content of galliu~ therein~
The mother liquors produced in proce~sing of bauxites
according to Bayer contain, on the average, the ~ollowing com-
po~ents in the amounts speci~ied hereinbelow, g/l: sodium oxide-
- 130-180; alumina 60-80; silica 0~3-0.6; iron oxida 0.004 -
- 0.006; organic compounds - 1.5 - 2.0 (a~ oalculated ~or oYy-
ge~ b~ potassium permanganate), total sulphur 2.5-~.5 including
~ulphide sulphur 0~5-0.8, thiosulphate sulphur 1.0-1.2; sul-
phite sulphur 0.2-0.4, sulphate sulphur 0.8-1.1~
f e. c, r C ~ o r7
C The Pe~u~n aluminate liquors contain, on the average,
g/ls s~dium oYide 260-~20; alumina - 120-160; silica - 0.6-1.2
iro~ oxide - 0.01 - 0.015; organic compounds - 3.0-4.0; total
sulphur - 5.0-7.0 including sulphide sulphur 1.0-1.6; thiosul-
; phate sulphur 2.0-2.4; sulphite sulphur - 0.4-0.8; sulphate
sulphur - 1.6-2.2.
.
~151 35~37
Concentration of gallium and vanadium in mother alu-
minate liquors is respectively 0.15 - 0.25 and 0.16 - 0.28
g/l; in recirculation aluminate liquors concentration of
gallium and vanadium is respectively 0.30 - 0.5G and 0.32 -
0.56 g/l.
For electrolytic recovery of gallium or gallium andvanadium use can be made of both above-specified and other
liquors. In both cases recovery of gallium into the ele-
ctrolytic deposit within 4 hours of electrolysis is 40 to80%, that of vanadium is 10 to 40%. It has been found
that the best results on recovery of gallium or gallium
and vanadium occur in using a mixture of the above-men-
tioned aluminate liquors (mother or recirculation) or re-
circulation aluminate liquor of the Bayer process dilutedwith water with a ratio (vol. %):
recirculation liquor 10 - 90
water the balance.
The electrolysis of the recirculation aluminate liquor
itself is hindered and economically inefficient due to
a high concentration of sodium oxide therein and, con-
sequently, increased viscosity and electrical resistance
of this liquor thus causing a considerable foam-formation
and voltage rise in the electrolyzer.
In order to increase the content of gallium in the
liquor and lower concentration of sodium oxide therein,
use is made of liquors prepared by repulpation with water
at
, 35
i
X - 14 -
::
. ,
. , : ' ` :: :.... .
~8~
a temperature within the range of from 50 to 100C, of
sodium carbonate precipitated from the recirculation al-
uminate liquor resulting from the Bayer process during
its vaporization.
Prior to electrolysis, into any of the above-specified
~ uors is introduced a metal forming, when the liquor is
reduced electrolytically, together with gallium an alloy
which is not passivated under the electrolysis conditions,
the concentration of such'metal being between 0.15 and
5.0 g/l with a concentration of gallium of 0.15 - 0.5 g/l.
~urthermore, said metal has the structure and parameters
of crystal lattice similar to those of gallium, as well as
the recovery potential approaching that of gallium. The
metal introduced into starting liquors is selected from
the group consisting of zinc, lead and tin. This metal
is introduced into hot alkaline solutions resulting from
alumina production,either per se or in the form of an oxide,
an inorganic salt soluble in said liquors. It is prefer-
able to use zinc which is not passivated upon electrolysis,has a high overtension relative to hydrogen (~.7 V), a
recoVery potential close to that of gallium (i e.-1.220 V
for Ga and -1.216 V for Zn), as well as similar structure
and parameters of crystal lattice. During electrolysis
zinc, while being deposited on a solid cathode, renews its
surface, whereby the deposition of gallium or gallium and
` vanadium occurs on the zinc cathode. These factors facili-
tate the process of re-
"
~,'
- 15 -
~ ~ ,
~ ~ ,
- -
.
duction of ions of gallate and vanadate on the cathode.
In the case where in the starting alkaline liquor re-
sulting from alumina production polyvalent sulphur com-
pounds are present, for the purpose of introducing thelatter into said liquor, prior to electrolysis, an add-
itional portion of the metal forming an alloy with gallium
non-passivating under electrolysis conditions added in the
stoichiometric amount relative to the polyvalent sulphur
compounds. In doing so, taken into account is the de-
composition of thiosulphate sulphur compounds during ele-
ctrolysis to compounds of sulphide sulphur and sulphate
sulphur.
An alkaline liquor from alumina production containing
the introduced metal is subjected to electrolysis on solid
electrodes under the following conditions:
cathodic current density of from 200 to l,000 A/m ;
voltage 3.4 to 4.5 V; process temperature of from 28 to
37C. As the electrode material use is made of metals
resistant in alkaline media, namely: steel, nickel, titan-
ium.
It is advisable that the cathode be cooled with water
in order to raise the electrolysis temperature due to a
lower temperature of the cathode surface and increased
temperature within the bulk of the solution. As a result,
the liquor vis-
- 16 -
. ~ ,, , , ., , , ... , . ~ .- , ..
: :
.
s~
cosity is lowered and the voltage on the electrolyzer is
decreased.
To improve the efficiency of the process, increase
the current yield of gallium or gallium and vanadium,
the electrolysis is conducted using direct, pulsating or
reversing current, as well as various combinations of said
currents.
The resulting electrolytic deposit is removed from
the cathode by any conventional method such as mechanical
or chemical ones, while the liquor with the residual con-
centration of the introduced metal of from 0.02 to 0.005
g/l is recycled back to the production of alumina.
Gallium or gallium and vanadium are recovered from the
resulting electrolytic deposit by any conventional method
such as vacuum-thermal treatment. Furthermore, it is pos-
sible to recover gallium or gallium and vanadium by dis-
solution of the electrolytic deposit is acids or alkalis.Thereafter, gallium is recovered from the resulting solu-
tions electrolytically, while vanadium remains in the solu-
tion as a slime of vanadium concentrate and is then filter-
ed-off. Gallium produced by this process contains, as
the principal impurity, 2 to 6% by mass of the metal added
to the liquor for electrolysis.
Production of metallic gallium conta;ning the above-
.
; 35
, ~ - 17 -
,. , ~ ~ , ~. I . ,
, , , . , ::
, ' . . ; 1', " . :
. ~ :
8~
mentioned amount of the metal added to the starting liquor,
for example zinc, facilitates the production of gallium
having much smaller amounts of other impurities. It is
known that in the case of presence of zinc in gallium in
the above-specified amount activity of gallium is lowered,
wherefore solubility therein of other impurities is sub-
stantially reduced. The removal of zinc by conventional
methods such as acid treatment or vacuum-thermal treat-
ment is performed without any troubles.
For a better understanding of the present invention,
some specific Examples illustrating the process of re-
covery of gallium or gallium and vanadium are given here-
inbelow.
Example 1
A recirculation aluminate liquor resulting from Bayer's
process in the amount of 48 1 having the following composi-
tion as to the content of the main components, g/l; sodium
oxide 310; alumina - 138; silica - 0.9; iron oxide -
0.019; organic compounds - 3.89; gallium - 0.43; vanadium
- 0 35, is diluted with 13 1 of water (in vol. ~) recircu-
lation liquor - 78, water - 22. Then to the liquor heated
to the temperature of 90C there are added 112 g of zinc
oxide under stirring. The resulting liquor having the
following composition, g/l: sodium oxide - 250; alumina -
112; silica - 0.72; iron o~cide - 0.008; organic com-
- 18 -
,:
1~ ~&~
pounds -3.14; gallium - 0.35; vanadium - 0.28 and zinc -
1.5 is fed into the electrolyzer with the working `capacity
of 60 litres. Electrolysis is carried out using direct
current under the following conditions:
cathodic current density 650 A/m2, volt~ge 3.8 V,
temperature 32C. The material of anode - steel lX18H9T,
the material of cathodes - nickel.
After 4 hours of electrolysis the following metals
are recovered as a percentage of their total amounts: gal-
lium - 57; vanadium - 20; zinc - 98.
The thus-produced electrolytic deposit is removed
from the cathode mechanically, while the liquor after
electrolysis with the residual concentration of zinc of
0.03 g~l is recycled to the production of alumina.
The electrolytic residue is washed with water to re-
move sodium oxide and other soluble impurities, dried and
subjected to vacuum-thermal sublimation to remove zinc.
The residue obtained after the vacuum-thermal sublimation
contains gallium and vanadium; this residue is dissolved
in 3litres of a hot solution of caustic soda with the
concentration of 150 g/l as calculated for sodium oxide.
The vanadium concentrate is precipitated and the precipi-
tate is separated by filtration, while the solution con-
taining gallium in the amount of 4 g/l
.. ,~,,~ -- 1 9
,~, "b~,"
.,
,
`: .;. ' . ,' - :
': ' ~ ~'.`.,' .;,. ,: ,:
'''`'.`, ~ ''''.,"' ' ~''' ::""' '
,.' ;`', `':':
115~S~7
is subjected to electrolysis on a nickel cathode a~ the
cathodic current density of 1,200 A/m2 and the tempera-
ture of 60C.
5The total amount of the recovered gallium is 11.4 g;
that of vanadium concentrate is 8.1 g.
The thus-produced metal contains, per cent by mass:
gallium - 96.997; zinc - 3.0; lead - 1.10 3; copper - 1.10 3,
aluminium - 1~10 3; and other impurities are not detected.
The vanadium concentrate contains, per cen by mass:
vanadium pentoxide - 84.1; sodium oxide - 10.0; silica -
2.Q; gallium- 0.2; zinc - 3.7.
After treatment of the resulting metallic gallium with
hydrochloric acid diluted with water in the ratio of 1:2
(by volume) at the temperature of 60C, the content of gal-
lium in the product is 99.998% by mass.
Example 2
The recirculation aluminate liquor resulting from
Bayer's process in the amount of 40 1 having the composi-
tion described in the foregoing Example 1 is mixed with
20 1 of the mother aluminate liquor from the Bayer process
(in vol. %) mother liquor - 33.3 recirculation liquor -
66.6 of the composition in terms of basic components, g/l:
sodium oxide -173; alumina -75.1; silica -
- 20 -
~S859'7
- Q.42; iron oxide - 0.005; organic compounds - 1.94;
gallium - 0.19; vanadium - 0.17. The volume ratio of the
liquors IS 1: O. 5. Then, into the resulting liquor 110 g
of zinc oxide are added using the procedure described in
the foregoing Example 1. The.resulting liquor having the
following composition, g/l: sodium oxide - 264; alumina
- 117; silica - 0.74; iron oxide - 0.008; organic substi-
tutes - 3..24;.gallium -Ø35; vanadium - 0.29 and zinc
- 1.5 is subjected to electrolysis in a manner similar to
that of Example 1, except that the cathodic current density
is equal to 1,000 A/m2 at the voltage of 4.1 V.
After 4 hours of electrolysis the following metals
are recovered, as a percentage of their starting amounts;
gallium - 63; vanadium - 2~; zinc - 96.
The resulting electrolytic deposit is removed from the
cathodes and processed to gallium and vanadium concentrate
in a manner similar to that of Example 1 hereinabove.
The total amount of the recovered gallium is 12.5 g;
that of vanadium concentrate is 10.1 g.
The composition ofthe resulting products is similar
to that indicated in Example 1.
Example 3
The recirculation and mother liquors resulting from
30 Bayer's pro- - -
- 21 -
''' ~'"' . '
s .. . .~
. . :, :
.
:. : ...
.
~5~
cess haviny compositions according to Examples 1 and 2 res-
pectively are mixed (in vol. %~ mother li~uor - 90 recir-
culation liquox - 10 then..to 6Q 1 of the prepared liquor
67.5 g of zinc oxide are introduced by the method described
in Example 1. The resulting solution having the following
composition, g/l: sodium oxide - 187; alumina - 81.3;
silica - 0.47; iron oxide - 0.006; organic compounds - 2.13;
gallium - 0.21; vanad~um - 0.19 and zinc - 0.9 is subjected
to electrolysis as described in Example 1.
After 4 hours of electrolysis the following metals are
recovered, as a percentage of their starting amounts: gal-
lium 48; vanadium - 15; zinc - 96.
The total amount of the recovered gallium is 5.7 g;
that of vanadium concentrate is 3.5 g.
The composition of the resulting products is similar
to that of Example 1.
Example 4
Into 60 1 of a liquor prepared in a manner similar to
that described in Example 3 there are introduced 109 g of
zinc oxide. The resulting solution of the following compo-
sition, g/l: 187 - sodium oxide; alumina 81.3; silica
_ 0.47;
~ - 22 -
115~SS:3 ~
iron oxide - Q.006; organic compounds - 2.13; gallium
- 0.21; vanad~um - 0.19; Zinc - 1.47 is subjected to ele-
ctrolysi~s as described in Example 1.
After 4 hours of electrolysis the following metals
are recovered, percentage of their initial amounts: gal-
lium - 65; vanadium - 37; zinc - 97.
The thus-produced electrolytic deposit is removed from
the cathodes and processed to gallium and vanadium con-
centrate in a manner similar to that of Example 1.
The total amount of the recovered gallium is 7.8 g;
that of vanadium concentrate is 8.5 g.
The composition of the resulting products is similar
to that described in Example 1 hereinbefore. ~ .
Example 5
The liquor prepared in a manner similar to that de-
scribed in Example 1 and having composition as indicated
in the same Example 1, except that the content of zinc is
3.5 g/l is subjected to electrolysis as described in
Example 1.
After 4 hours of electrolysis the following metals are
recovered, percentage of their initial amounts: gallium
- 38; vanadium - 10; zinc - 90.
- 23 -
: . . ; : .
,
I' . , . ~ .'. '
' '' ' ' . ". ' ~ ~'
5~
The resulting electrolytic deposit is removed from
the cathodes and processed to gallium and vanadium concen-
trate in a manner similar to that of Example 1.
The total amount of the recovered gallium:is 7.6 g;
that of vanadium concentrate is 5.8 g.
The composition of the resulting products is similar
to that described in Example 1.
Example 6
The recirculation and mother liquors resulting from
Bayer's process having the compositions indicated in Examples
1 and 2 respectively are mixed (invol. %) mother liquor
- 10 and recirculation liquor - 90. Then to 60 1 of the
prepared liquor 127 g of zinc oxide are added using the
method described in Example 1 hereinbefore. The resulting
liquor having the following composition, g/l: sodium oxide
- 296; alumina - 132; silica - 0.85; iron oxide - 0.018;
organic substitutes - 3.69; gallium - 0.41; vanadium - 0.33
and zinc - 1.77 is subjected to electrolysis as described
in Example 1, at a voltage of 4.5 V.
After 4 hours of electrolysis the following metals are
recovered, percentage of their starting amounts: gallium
- 40; vanadium - 13; zinc - 97.
~r - 24 -
1~
-25-
~ he resultin~ electrolytic deposit is removed from the
cathodes and processed to gallium and vanadium ooncentrate
as described in Example 1.
The total amount o~ the recovered gallium i9 9.3 g;
that o~ vanadium concentrate is 5.4 g.
~ he composition of the resulting products i9 similar
to that described in Example 1 hereinbefore.
~ xample 7
The residue obtained after settling and filtration o~
r C C / rc ~ f / ~
~r the roturn alumi~ate li~uor resulting from Bayer's process is
repulped with water for 8 hours at the temperature of 60C.
Then the re~ulting solution is filtered-off to separate it
from the residue insoluble in water. The resulting filtrate
has the following composition, g/l: sodium oxide - 246; alu-
mina - 92j gallium - 0.4; iron oxide - 0.04. Into this filt-
rate taken in the amount of 60 litres 1.5 g/l of zinc are
introduced as described in Example 1. Afterwards, electrolys-
is is conducted u9ing DC under the ~ollowing conditions:
cathodic current density of 400 A/m2, v~ltage 3.4 V; tempe-
rature 30C. The material of a~ode~ i9 steel 1~18~9T; material
o~ the cathode~ is nickel.
A~ter 4 hours of electrolysis the following metals are
~' ,
~ 5~
recovered, percentage of their initial amounts: gallium
- 75; zinc - 98.
The removal of the residue and processing thereof to
metallic gallium is effected as in Example 1.
The total amount of gallium recovered is 18 g.
The composition of the resulting product i.e. metallic
gallium is similar to that indicated in Example 1 herein-
before.
Example 8
lS The recirculation aluminate liquor resulting from Bayer's
process and having the composition according to Example 1,
but containing no vanadium is diluted with water (invol. %)
recirculation liquor - 78,~ater - 22. Then to 60 1 of the
solution heated to the temperature of 100C 45 g of lead
20 oxide are added under stirring. The resulting liquor having
the following composition, g/l: sodium oxide - 250; alumina
- 112; silica - 0.72; iron oxide - 0.008; organic compounds
- 3.14; ~allium - 0.35; and lead - 0.7 is subjected to ele-
ctrolysis as in Example 1. After 4 hours of the electroly-
sis the following metals are recovered from the liquor, per-
centage of their initial amounts: gallium - 69; lead - 98.
The resulting electrolytic deposit is removed from the
cathode mechanically, while the liquor after electrolysis
with the residual lead concentration of 0.005 g/l is re-
cycled to the pro-
- 26 -
.
5~
ductiqn of alumina.
The electrolytic deposi~t is dissolved in 3 1 of sul-
phuric acid with the concentration of 210 g/l heated to
the temperature of 60C. The lead-containing precipitate
is separated by filtration and the solution is neutralized
with a 5% solution of ammon~a to precipitate gallium hydr-
oxide. The latter is dissolved in 3 1 of a solution of
caustic soda with the concentration of 150 g/l as calculated
for sodium oxide. The resulting solution with the concen-
tration of gallium of 4.4 g/l is subjected to electrolysis
in a manner similar to that described in Example 1.
The total amount of recovered gallium is 12.5 g.
The resulting metal contains gallium in the amount of
99.98% by mass.
Example 9
To 60 litres of the liquor prepared as described in
Example 1, but containing no vanadium, 112 g of zinc oxide
are added. The resulting liquor having the following com-
position, g/l: sodium oxide 250; alumina 112; silica 0.72;
iron oxide 0.008; organic compounds 3.14; gallium 0.35 and
zinc 1.5 is subjected to electrolysis as described in
Example 1, but with the cathodic current density of 300 A/m2
at the voltage of 3.4 V.
- 27 -
, . . , , ,, i . . - , - ,, :,
" -. ." .~-.,. ~. .~ .
., , , "." , , - .
i. . . - . . .. .
~' ' ' ' ' - ' ` "' ' .' ~ , . ~ ' '
, ' ~ . ' ' ` ' ' ' :
After 4 hours of electrolysis the following metals
are recoyered, percentage of thei-r initial amounts:
gallium - 46; zinc - g8. The resulting electrolytic de-
posit is removed from the cathodes and processed to gallium
in a manner similar to that described in Example 1.
Example 10
The recirculation and mother liquors resulting from
Bayer's process having compositions indicated in Examples
1 and 2 respectively but containing no vanadium are mixed
(in vol. %) mother liquor - 44, recirculation liquor - 56.
Thereafter, 119 g of zinc oxide are added to 60 1 of the
thus prepared liquor. Thus, liquor has the following com-
position, g/l: sodium oxide - 250; alumina - 110; silica
- 0.63; iron oxide - 0.012; organic compounds - 3.02; gal-
lium - 0.32 and zinc - 1.6 is subjected to electrolysis
using direct current under the following conditions: cath-
odic current density 700 A/m2; voltage 3.9 V; temperature
30C. The material of the anodes is nickel; that of the
cathodes is lead.
After 4 hours of electrolysis the following metals are
recovered, percentage of their initial amounts: gallium
- 70; zinc - 98.
The removal of the resulting electrolytic deposit and
- 28 -
~'f
.....
S~3
--29--
processing thereo~ to metallic gallium i9 conducted in a man-
ner similar to th~t described in B~ample 1.
The total amount oi reoovered gallium is 12.7 g. The
thus-produced metal ¢ontai~s, % b~ ma~s: gallium -94.788;
zinc - 5 2, lead - 1.10-2; c0pper - 1.10-~; aluminium - 1.10-3.
,~ No
other impurities are deteoted. ~iter treatment o~ the result-
~ng metallic gallium with hydrochloric acid di~uted with ~ater
in the volume ratio 0f 1:2 at t~e temperature of 60C it con-
tains 99.988 ~ by mass oi gallium.
~xample 11
Preparation and electrolysis o~ liquors are efiected
as in ~Yample 10, e~cept t~at electrolysis is a0nducted at
the temperature o~ ~C and at the v01t~ge of 3.7 V. T~e ma-
terial oi the anodes i8 niokel~ that oi eathode~ - steel 1~18H9T.
~he ¢athodes are cooled with water.
After 4 hours of ele¢trolysis the ~ollowing metals are
rec0vered, percent~ge o~ their initi~l amounts: gallium - 65;
zina - 97~
~ he resulting electrolytic deposit i9 removed ~rom the
cathodes and processed to gallium iollowing the procedure oi
E~ample 1 hereinberore.
,, ,
. - . . .
.
,,, . , : .
. . . . .
. , .
, . ~,
- ~
The total amount of the recovered gallium i5 11. 9 g.
The composition of the product i.e. metallic gallium is
similar to that indicated in Example 1.
Example 12
To 60 1 of the mother aluminate liquor resulting from
Bayer's process and having the composition mentioned in
Example 2 zinc is introduced in an amount of 1.9 g/l and
electrolysis is conducted using direct current under the
following conditions: cathodic current density 550 A/m ;
voltage 4.1 V; temperature 28C. The material of the
anodes - steel lX18N9T; the material of the cathodes - tit-
anium.
After 4 hours of electrolysis the following metals are
recovered from the liquor, percentage of their initial
amounts: gallium 51; zinc - 97.
The removal of the electrolytic deposit and processing
thereof to metallic gallium are performed as in Example 1.
The total amount o~ the recovered gallium is 5.5 g.
The composition of the resulting product i.e. metallic gal-
lium is similar to that indicated in Example 1 hereinbefore.
Example 13
10 1 of the liquor prepared as in Example 10 are sub-
jected to electrolysis using pulsating current (current
switch-
- 30 -
11S8~9'7
:
Oir interval i8 0.5 sec; ~requency o~ ~witahin~ is 1 æwitch-
ing per mi~ute) uuder the iQlloWi~g conditions: cathodic cur-
rent density is 650 A/m2, voltage 3.8 V, temperature 30C. ~he
material of the anodes i~ steel lX18H9~, that of the cathodeæ
- nickel. T~e cathodes are cooled with water.
Arter 4 hours oi electrolysis the following metalæ are
recovered from the li~uor, percentage of their initial amo-
unt~: gallium - 82; zinc - 98.
The removal Or the electrolytic deposit and processing
t~ereof to metallic gallium are periormed as in Example 1.
~ he tobal amount oi the recovered gallium is 2.49 g.
f~'5cf~Cf~
The composition oi the resulti~g/gallium i8 similar to
that described in hxample 1 hereinbefore.
Ex~mple 14
10 1 of the liquor prepared as in ~Xample 10, are su~-
~ecbed to electrolysis using reversing current (time oi anodic
polarization is 0.2 sec; frequency of switching - 4 switching~
per minute). ~h~ condition~ of electroly i~ and materials oi
the elect~odes are the same as in the foregoing Example 13.
Arter 4 houre of electrolysis the iollowing metals are
recovered from the liquor, percentage of their initial amounts
gallium - 75; zinc - 98.
- ' '
. , .
, " . , , , , , . ,, ~ :~
The removal o~ the electrolytic deposit and process-
ing thereof to metallic ~allium are conducted as in
Example 1,
The tobal amount of the recovered gallium is 2.28 g.
The resulting metal contains, % by mass: gallium - 95.
996; zinc - 4.0; lead - 1.10 3; copper - 1.10 3; aluminium
- 1.10 3; iron - 1.10 3. No other impurities are detected.
After treatment of the resulting metallic gallium with
hydrochloric acid di-l~ted with water in the volume ratio
of 1:2 at the temperature of 60~C, the product contains
gallium in the amount of 99.996% by mass.
Example 15
The recirculation aluminate liquor resulting from Bayer's
process having the following composition, g/l: sodium
oxide - 310; alumina - 138; silica - 0.9; iron oxide - 0.019;
organic compounds - 3.89; sulphide sulphur - 1.47; sulphite
sulphur - 0.92; thiosulphate sulphur - 2.19; gallium - 0.43
is diluted with water (in vol. %): recirculation liquor
- 78; water - 22. Then to 100 1 of the liquor heated to
~ ~C 609 g of zinc oxide are added under stirring, in-
cludin~ 302 g consumed for binding sulphide sulphur in thestarting liquor and 89 g - for binding secondary sulphide
sulphur formed during electrolysis upon decomposition of
thiosulphate sulphur. The remaining amount of zinc oxide
- 32 -
"~
- ` ~1S8~97
(218 g) $s consumed for electrolytic recovery o~ gallium.
The resulting liquor, after separation Or the precipi-
tate oi zino sulphide, has the following eomposition~ g/1 : so-
dium oxide - 253; ~lumina - 112; silica - 0.72; iron oxide -
- 0.008; organic compounds - ~4; thiosulphate sulphur - 1.76;
sulphite sulphur - 0.70; g~llium - 0.35 and zinc - 1.75. This
liquor in the amount of 60 litreæ is subjected to electrolysis.
Said electrGlysis is conducted using direct current under
the following conditions: oathodic current densit~ 400 A/m2;
volt~ge 3.8 V; temperature 35C. The material of the an0des i9
nickel. ~jhat of the ¢athodes is steel 1X18H9~.
Aiter ~ hours of electrolysis th0 rollowing metals are
recovered from the liquor, percentage of their initial amo-
B untss gallium - 52; zinc - 9y~ ~he resulting electrolytic re-
sidue is removed irom the cathode and processed to metallic
gallium as in Bsample 1.
The total amount of the recovered gallium is 10.~ g.
~ roJ~ /. e.,
J The composition of the resulting/metallic gallium is similar
to that indicated in Example 1 hereinbefore.
A~ter settling the ~pent liquor purified during the
electrolysis from contaminating pol~valent sulphur compounds
and lron and having the following composition, g/l: sodium oxide -
,
,, , ~ .
-
" .
.
255; alumina - 112; silica - 0.72; iron oxide - 0.001;
organic compounds - 2.90; sulphide sulphur - 0.07; sul-
phite sulphur - 0.45; thiosulphate sulphur - 0.42; gallium
- 0.17 and zinc - 0.017 is recycled to the production of
alumina.
Example 16
Into 60 1 of the recirculation aluminate liquor re-
sulting from Bayer's process and having the composition ascited in Example 2 57 g of zinc oxide are introduced by
using the same technique as specified in Example 1. The
resulting solution having the following composition, g/l:
sodium oxide - 173, aluminium oxide - 75.1; silica - 0.42
iron oxide - 0.005, organic substances - 1.94, gallium
- 0.19, vanadium - 0.17, and zinc - 0.95 is subjected to
electrolysis as described in Example 2.
After 4 hours of electrolysis the following metals are
recovered from the liquor, percentage of their initial
amounts: gallium - 48, vanadium - 15, and zinc - 97.
The resultant electrolytic precipitate is removed from
the cathodes and processed to gallium and vanadium concen-
trate as in Example 1.
The total amount of the recovered gallium was 4.99 gand of vanadiaum concentrate, 2.8 g.
The composition of the products obtained is similar
to that specified in Example 1.
- 35
- 34 -
~'~'
