Note: Descriptions are shown in the official language in which they were submitted.
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Dust-free Grade Lithium Hydroxide Monohydrate and Its Preparation Method
Technical Field
The present invention relates to a dust-free grade lithium hydroxide
monohydrate and its preparation method thereof, belonging to the technical
field of lithium
hydroxide preparation.
Technical Background
Lithium hydroxide monohydrate (Li0H+120) is widely applied, of which
manufacturing of advanced lithium base grease is its greatest consumption
field. Lithium
base grease produced with Li0H+120 is featured in wide applicable temperature
range
(-50 C to +300 C), good fireproof performance, resistant to oxidation, stable
performance in
case of repeated heating-cooling-heating cycle, long service life and strong
water resistance.
In addition, Li0114-120 is also widely used in the fields of chemical,
national defense and
battery, etc. As alkaline storage battery additive in the battery industry, it
can extend the
service life and increase the storage capacity of battery, while being ion
exchange resin in
1 5 defense field, it can absorb radioisotopes, thus being used as a
reactor heat carrier and a metal
surface protecting agent. In terms of aerospace, Li0H.H20 can be used for air
purification in
submarine and the pilot's breathing mask. In addition, Li0H+120 can also be
used as water
purifying agent, emulsifier for production of porous concretes as well as raw
material of
special optical glass, synthetic vitamin A and a lot of other lithium salts.
Preparation methods of Li011.1120 mainly include:
1. Limestone calcinations process
Firstly, Lithium-containing ore and limestone are mixed and milled as per the
specific mass ratio, then, the milled slurry is placed into a rotary kiln for
calcination, during
which CaO generated from decomposition of calcium carbonate is reacted with
lithium ore to
generate Li0H. However, this process has rarely been applied due to high
energy
consumption, large material liquidity, high cost, difficult to improve product
quality.
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2. Beta-spodumene sodium carbonate pressure extraction method
'
First, Alpha-spodumene concentrate is transformed into beta-spodumene after
being calcined
at temperature of 1050 C to 1100 C in the rotary kiln, then, add and evenly
mix a certain
amount of Na2CO3, which is leached after being heated to 200 C, the soluble
LiHCO3 is then
generated by introducing CO2, the residue is then removed by filtration, add
the purified lime
milk as per the stoichiometric proportion, thus, Li011-1-120 is prepared as
the reaction liquid is
concentrated and crystallized.
3. Lithium carbonate causticizing method
Mix the purified lime milk with lithium carbonate in certain proportion,
adjust
the mixture to a certain caustic solution concentration, and then heat it to
boiling while stirring
vigorously. The causticizing reaction is as follows:
Ca(OH)2 + Li2CO3 = CaC031+ 2LiOH
3.5% LiOH solution can be obtained by the reaction. Insoluble residue (mainly
CaCO3) is removed and mother liquor is separated, concentrated and
crystallized to obtain
lithium hydroxide monohydrate. Lithium hydroxide monohydrate is dried at 130 C
to 140 C
and then heated at 150 C to 180 C under reduced pressure to prepare anhydrous
Li0H.
Lithium carbonate causticizing method is the main method for producing lithium
hydroxide
both at home and especially abroad. However, this production process featured
in complex
process, large investment in equipment and high cost. Besides, the main raw
material is
lithium carbonate, the price of which directly affects the production cost of
lithium hydroxide
monohydrate.
4. Electrolysis of refined brine
Concentrate the brine until it contains 5% to 7% of Li (LiC1 is measured at
rate
of 35% to 44%) , then adjust pH into 10.5 to 11.5 after being filtered,.
remove calcium and
magnesium ions in brine to obtain purified brine (with LiC1 as the main
ingredient) by
precipitation; the purified brine is electrolysed as electrolytic solution in
special electrolytic
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tank, wherein the anolyte is of purified brine and the catholyte is of water
or LiOH solution;
There is a cation permselective membrane between the anolyte and catholyte
(such as
perfluorosulfonic acid membrane Rf-S03H and perfluorocarboxylic acid membrane
Rf-COOH, etc.), where cation can pass though but anion is blocked. During
electrolysis, Li+
can migrate through the membrane to the cathode and be converted to LiOH. H2
and C12
produced by the reaction can be used as by products for producing HC1.
Finally, LiOH
solution at concentration of about 14% can be obtained in the cathode, thus,
LiOH product can
be produced after being crystallized and dried. However, this method is
disadvantaged in great
energy consumption, high cost and serious impact on the environment.
5. Electrolysis of Li2SO4 solution
Li2SO4 solution as anolyte and water as catholyte is electrolyzed in membrane
electrolytic tank, wherein anolyte and catholyte is separated by fluorine-
containing cation
exchange resin (such as C2H4 and CF2=CFO(CF2)3COCF3 copolymer), the control
voltage is
controlled to be 6V and the current density is controlled to be 100A/dm2 so as
to obtain LiOH
solution with mass concentration of about 10% in the cathode and H2SO4
solution in the
anode. Ion-exchange membrane electrolysis method for preparation of LiOH is
featured in
high Li recovery rate (nearly 100%), no secondary pollution and high purity (>
99%) of the
obtained product which can be directly used in the production of lithium
lubricant. However,
the present method requires higher impurity ion content of the purified brine,
namely the total
concentration of Na and K+ should be below 5%, and the total amount of Ca2+
and Mg2+
should not be more than 0.004%. In addition, the ion-exchange membrane is
expensive and
difficult for maintenance, resulting in higher production cost of LiOH.
6. Lithium aluminate precipitation method
The method for preparing lithium hydroxide is to use sodium aluminate at
concentration of 10% as the raw material, A1(OH)3 is prepared by carbonization
of CO2 with
concentration of 40%, then add it into the boron-abstracted brine (containing
0.13% of Li) at
aluminum-to-lithium weight ratio of 13 to 15, during which pH is at 6.8 to 7.0
and
temperature at 90 C, wherein A1(OH)3 can react with Lì+ in brine to produce
stable lithium
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aluminum compound (LiC1.2A1(OH)3.nH20) precipitate, with lithium aluminum
precipitate
yield of 95%, then, calcine the obtained lithium aluminum precipitate in the
presence of
neutral salts (e.g., NaNO3, NaCI, etc.) at 120 C to 130 C for 20 to 30 minutes
so as to
decompose into A1(OH)3 and soluble lithium salt, lithium and aluminum in the
precipitate can
be separated by hot water leaching. Let the leached solution flow through
exchange column
filled with strongly acidic cation exchange resin, Li, Mg2+ and other cations
are substituted
and left in the exchange column, elute it with 1% to 20% aqueous caustic so
that Mg2+, Ca2+
and other impurity ions generate hydroxide precipitates and remain in the
exchange column
while Li + generates LiOH to flow out with the solution; or making the
leaching solution flow
through exchange column filled with strongly basic anion exchange resin, LiC1
in the solution
is converted into LiOH and flow out with the solution, while Mg2+, Ca2+ and
other impurity
ions are precipitated and remained in the exchange column to be separated. The
LiOH
solution concentration obtained by the present method is about 6%, and the
recovery rate of
lithium is more than 90%. The obtained LiOH solution is concentrated by
evaporation,
crystallized and dried to obtain LiOH product. The recovered calcined soda and
aluminum
hydroxide from the carbonation mixture is calcined at 900 C and then leached,
wherein the
leached sodium aluminate can be recycled. The disadvantage of this method for
the scaled
production lies in that the obtained lithium aluminum precipitate is colloid,
the solid weight
accounts for only about 10% and the average particle is only 11.1m, so, it is
difficult to be
filtered, resulting in complex process and high energy consumption.
7. Calcination method
Extract boron from brine and evaporate 50% of water, then calcine it at 700 C
for 2 hours so that magnesium chloride in brine becomes magnesium oxide by
pyrolytic
decomposition, with decomposition rate of 93%. Then it is leached by water,
wherein the
leaching solution (containing 0.14% of lithium) is added with lime milk and
calcined soda to
remove calcium and magnesium ions, and add Na3PO4 to precipitate Li3PO4, and
Li3PO4
precipitate is filtered and mixed with CaO and A1203 at the ratio of 1:6:2,
which is then
calcined for 2 hours in resistance furnace at 2300 C, the calcined mixture is
leached with hot
water at 85 C to 95 C and filtered, the filtrate is concentrated by
evaporation, crystallized and
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dried to obtain LiOH product. The advantages of this method are as follows:
lithium and
magnesium and other resources can be comprehensively utilized, needing less
chemical raw
materials; calcination can remove impurities such as boron and magnesium to
improve the
purity of the lithium hydroxide. The disadvantages are as follows: the use of
magnesium
makes the process flow be complex, serious corrosion of equipment, great water
evaporation
and high energy consumption.
8. The patent numbered ZL 200710051016.5 provides a method for
preparation of battery-grade lithium hydroxide monohydrate.
This method includes the steps as follows: suitably concentrate lithium
sulfate leaching
solution by evaporation, add NaOH for reaction to remove Fe, Ca, Mn and other
impurities by
filtering, and then freeze it to -5 3 C, Na2SO4.10H20 can be filtered and
separated, after
then, concentrate the filtrate by evaporation and crystallize the concentrated
filtrate to obtain
crude Li0H+120. Then further dissolve the crude Li0H+120 and add refinined
agent to
remove Na, wet solid Li0H+120 is obtained after being cooled, crystallized and
filtered, then
dry it to obtain Li0H-1120 product.
9. Lithium silicate conversion method
Lithium silicate conversion method is to melt the obtained lithium carbonate
and silicic acid to generate lithium silicate, wherein lithium silicate is
hydrolyzed to produce
lithium hydroxide; while lithium sulfate conversion method is to convert
lithium in brine into
lithium sulfate, and then make lithium sulfate and barium hydroxide react to
produce lithium
hydroxide. At present, above two processes are not mature, and the study is
still underway.
Li0H+120 obtained by above-mentioned method results in pungent dust. With
the enhancement of people's awareness of environmental protection, friendly
working
environment is urgent, thus, the flying dust is imminent to be solved. Wet
Li0H+120 can
solve the problem of flying dust but it results in caking. It will be caked if
it is not used for
two days and needs to be broken into small pieces before feeding. If it is not
used for 3 to 4
days, it will become very hard block and difficult to use. If it is not used
for over four days, it
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is difficult to beat even with a hammer and unable be used any more. Thus, it
has high
requirement for procurement and production, which has serious impact on its
use. Therefore,
it is a new issue for us to solve the caking problem of wet 1.,i0H= H20 and
flying dust of dry'
Li01-1-1-170.
Summary of the Invention
The present invention relates to Li01-1=1-120 lithium hydroxide monohydrate,
which is dust-free and non-caking.
The present invention relates to lithium hydroxide monohydrate which is a wet
loose granular product, which may be stored for 3-5 months and still remain
loose particles,
1 0 without caking.
Said lithium hydroxide monohydrate may be a loose granular wet product,
wherein its moisture content is <3.5%, a small amount of anti-caking agent is
coated on the
surface of the lithium hydroxide monohydrate, and the said anti-caking agent
is one of sodium
dodecyl sulfate, sodium ferrocyanide, potassium ferrocyanide, sodium
hexametaphosphate,
trimeric sodium phosphate, sodium pyrophosphate, sodium lauryl sulfate,
polyacrylamide,
methyl pentanol, 3-ethylhexyl phosphoric acid or cellulose derivatives; one of
sodium dodecyl
sulfate, sodium hexametaphosphate, potassium ferrocyanide or sodium
ferrocyanide is
preferred; and the weight of the anti-caking agent is 1 to 10 ppm.
One aspect of the invention relates to lithium hydroxide monohydrate,
characterized in that said lithium hydroxide monohydrate (1.,i01-11-1)0) is a
loose granular wet
product, containing Li0I-1=1-120 and from 1.5 to 3.5% by weight of moisture,
wherein the
surface of the LiOITH70 granules is coated with an anti-caking agent, wherein
the anti-
caking agent is one of sodium dodecyl sulfate, sodium ferrocyanide, potassium
ferrocyanide,
sodium hexametaphosphate, trimeric sodium phosphate, sodium pyrophosphate,
sodium
lauryl sulfate, polyacrylamide, methyl pentanol, and 3-ethylhexyl phosphoric
acid; and
wherein the weight ratio of the anti-caking agent to 1_,i0H is from 1 to 10
ppm.
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The dust-free lithium hydroxide monohydrate of the present invention may be
prepared in the following method:
(1) preparing LiOH solution containing 70+5 g/1 of Li70, wherein the
concentration of S042- is controlled to be no more than 15 g/1;
(2) evaporating the LiOH solution obtained in Step (1) to a liquid-solid
volume ratio of 1:0.8 to 1:1.5, then adding anti-caking agent, stirring,
separating and washing
to obtain the dust-free industrial grade LiOH1120 product which does not caked
in VaCULIM
sealed package within several months;
wherein, as the anti-caking agent is added, the preferred temperature is
90-100 C. When the temperature decreases to 90 C below, the S042- content of
the obtained
wet product may be significantly high.
Wherein, the anti-caking agent is one of sodium dodecyl sulfate, sodium
ferrocyanide, potassium ferrocyanide, sodium hexametaphosphate, trimeric
sodium
phosphate, sodium pyrophosphate, sodium lauryl sulfate, polyacrylamide, methyl
pentanol,
3-ethylhexyl phosphoric acid or cellulose derivatives. The weight ratio of
anti-caking agent
and LiOH in material may be 1:500 to 1:10000.
A further aspect relates to a method for preparing lithium hydroxide
monohydrate, which comprises the following steps: (1) preparing an aqueous
Li011 solution,
in which equivalent 1.,i20 concentration is 70+5 g/l, the solution being free
of S042- or
having a S042- concentration of no more than 15 g/1; (2) evaporating the LiOH
solution
obtained in Step (1) to a liquid-solid volume ratio of 1:0.8 to 1:1.5, adding
the anti-caking
agent, stirring, and separating and washing an obtained solid to obtain a
loose granular wet
product and then performing vacuum sealed packaging; wherein said anti-caking
agent is
added in a weight ratio of between 1:1000 and 1:10000 relative to LiOH,
wherein, when said
anti-caking agent is added, the temperature of the LiOH solution is maintained
at 90 C to
100 C, wherein the anti-caking agent is one of sodium dodecyl sulfate, sodium
ferrocyanide, -
potassium ferrocyanide, sodium hexametaphosphate, trimeric sodium phosphate,
sodium
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pyrophosphate, sodium lauryl sulfate, polyacrylamide, methyl pentanol, and 3-
ethylhexyl
phosphoric acid.
Extra anti-caking agents may introduce new impurities resulting in excessive
impurity content and substandard product. Too little anti-caking agent may
result in unobvious =
effect of anti-caking.
Further more, in order to obtain battery grade LiOH=E120 with higher purity,
in
Step (1) the concentration of S042- may be controlled to be no more than 8
g/1, and the
concentration of Na2O may be controlled to be no more than 2 g/1, and the
concentration of
CaO may be controlled to be no more than 0.01 g/1; and in Step (2), anti-
caking agent may be
1 0 added after the 1.i014 solution is evaporated to 1:0.8 ¨ 1.1 of liquid-
solid volume ratio.
Control of the liquid-solid ratio of the evaporation may be to control the end
of
evaporation. Higher liquid-solid ratio and early ending of evaporation may
affect productivity
and crystallization, resulting in had crystal form. However, lower liquid-
solid ratio and delay
of ending of evaporation may make the feed liquid concentration be too high
and high content
1 5 of' impurity product.
Industrial grade product is allowed to contain more impurity than that of
battery grade product, so, the feed liquid concentration can be higher than
that of battery
grade products at end of evaporation, namely, liquid-solid ratio for
production of industrial
grade product can be less than that of battery grade product at end of
evaporation.
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The anti-caking agent of the present invention can be: sodium or potassium
'
salts, such as sodium dodecyl sulfate, sodium ferrocyanide, potassium
ferrocyanide, sodium
hexametaphosphate, trimeric sodium phosphate, sodium pyrophosphate or methyl
pentanol,
3-ethylhexyl phosphoric acid, cellulose derivatives and so on.
The anti-caking agent of greater solubility is preferred, such as one of:
sodium
dodecyl sulfate, sodium hexametaphosphate, potassium ferrocyanide and sodium
ferrocyanide.
Insoluble anti-caking agents should not be used as possible as it could be,
such
as sodium aluminium silicate, tricalcium phosphate, amorphous silica and so
on.
Due to its extremely low solubility, insoluble anti-caking agent has bad
mixing
effect in the slurry but the amount is a relatively large, which may result in
too high impurity
content in the product. Thus, insoluble anti-caking agent should be avoided.
Meanwhile,
lithium hydroxide monohydrate production environment is inorganic salt system.
According
to the principle of the dissolution in the similar chemical substances, it is
better not use
organic substance during selection of anti-caking agent.
Wherein, LiOH solution in Step (1) can be obtained by the existing technology
or obtained by dissolving crude LiOH=1420 in water to remove the impurities.
For example, 1) calcine lithium-containing ore and limestone and then remove
the impurities to generate LiOH; 2) evenly mix beta-spodumene and Na2CO3, heat
it at 200 C
for leaching, introduce CO2 to generate soluble LiHCO3, add refined lime milk
according to
stoichiometric ratio for reaction, then remove the impurities to generate
LiOH; 3) lime milk
reacts with lithium carbonate to generate LiOH solution; electrolyze purified
brine to generate
LiOH solution; electrolyze Li2SO4 solution to generate LiOH solution; 4)
carbonate sodium
aluminate with CO2 for decomposition to obtain A1(OH)3, then react with brine
to produce a
stable compound lithium aluminum (LiC1.2A1(OH)311H20) precipitate, calcine at
the presence
of neutral salts (such as NaNO3, NaC1, etc.) so that it will be decomposed
into A1(OH)3 and
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soluble lithium salt, leaching in hot water, making it flow through the
exchange column with
=
strongly acidic cation exchange resin to remove impurities so that Li + will
generate LiOH and
flow out; and 5)add NaOH to lithium sulfate for reaction to remove Fe, Ca, Mn
and other
impurities by filtration, and then freeze it to -5 3 C, separate
Na2SO4.10H20 by filtration,
then concentrate the filtrate by evaporation to crystallize crude Li0H+120,
redissolve
LiOH=1420 to obtain LiOH solution and so on, wherein said LiOH solution
contains Li20
70 5 g/1 with the concentration of S042- no more than 8 g/L, the concentration
of Na2O no
more than 2 g/1 and the concentration of CaO no more than 0.01 g/1.
Addition of a small amount of additives (said additives is anti-caking agent.)
which, without affecting the product quality of LiOH=1420, may be added to
regulate LiOH
crystallization and precipitation process to prevent the wet precipitated
product Li01-1-1-120
from caking in the stored process and avoid flying dust after drying.
In order not to introduce new impurities, deionized water should be used as
much as possible in the process of preparation of the solution and elution.
In some embodiments, the present invention may provide a simple production
process, easy operation, less investment in equipment, lower product cost,
high recovery of
lithium, stable product quality and no pungent flying dust. The produced dust-
free Li0H+120
product may fully meet the quality demand of the downstream industry and
environment-
friendly.
According to one aspect of the present invention, there is provided lithium
hydroxide monohydrate, characterized in that said lithium hydroxide
monohydrate is a loose
granular wet product, containing from 1.5 to 3.5% by weight of moisture,
wherein the surface
of the lithium hydroxide monohydrate is coated with an anti-caking agent,
wherein the anti-
caking agent is one of sodium dodecyl sulfate, sodium ferrocyanide, potassium
ferrocyanide,
sodium hexametaphosphate, trimeric sodium phosphate, sodium pyrophosphate,
sodium
lauryl sulfate, polyacrylamide, methyl pentanol, and 3-ethylhexyl phosphoric
acid; and
wherein the weight of the anti-caking agent is 1 to lOppm.
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According to another aspect of the present invention, there is provided a
method for preparing lithium hydroxide monohydrate, which comprises the
following steps:
(1) preparing an aqueous LiOH solution containing 70 5 g/1 of Li20, the
solution being free
of S042- or having a S042- concentration of no more than 15 g/I; (2)
evaporating the LiOH
solution obtained in Step (1) to a liquid-solid volume ratio of 1:0.8 to
1:1.5, adding the anti-
caking agent, stirring, and separating and washing an obtained solid to obtain
a loose granular
wet product and then performing vacuum sealed packaging; wherein, when said
anti-caking
agent is added, the temperature of the LiOH solution is maintained at 90 C to
100 C, wherein
the anti-caking agent is one of sodium dodecyl sulfate, sodium ferrocyanide,
potassium
ferrocyanide, sodium hexametaphosphate, trimeric sodium phosphate, sodium
pyrophosphate,
sodium lauryl sulfate, polyacrylamide, methyl pentanol, and 3-ethylhexyl
phosphoric acid;
and wherein the weight of the anti-caking agent is 1 to 10 ppm relative to the
weight of the
LiOH.
Embodiments of invention
1 5 Example 1: Preparation of battery grade dust-free Li011.1120
(1) Preparation of LiOH solution containing Li20 of concentration of
70 5 g/1
It includes the following steps:
Taking 10000m1 of Li2SO4 leaching solution containing Li20 of concentration
of 38 g/L, adding Ca(OH)2 to adjust pH to 7, filtering, adding 1080g of sodium
hydroxide to
the filtrate, and sufficiently stirring to make it completely dissolve, and
then stirring and
cooling it to -3 C. When the concentration of S042- in the solution is 35 g/L,
filtering and
separating to obtain LiOH solution and Na2SO4.10H20 solid. Evaporating the
LiOH solution
to volume ratio of liquid-solid about 0.8:1, filtering and separating to
obtain crude Li0H+120;
adding deionized water and stirring to make it completely dissolve and make
Li20
concentration in the solution be 70 g/L. Adding 7.8g of refined agent
Li' 3Tio 8Ce0 4Zr0 5A10 3(PO4)3, keeping the temperature at 45 C, stirring for
120 minutes, and
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then filtering and separating to obtain the filtrate, which is pure LiOH
liquid; wherein said
LiOH solution contains Li20 of concentration of 72 g/1, and the S042"
concentration is
controlled to be 8 g/L, the Na20 concentration be 2 g/1 and the CaO
concentration be 0.01 g/1.
(2) Preparation of dust-free Li0H.1-120 by crystallization process
Evaporating the LiOH solution obtained in Step (1) to liquid-solid volume
ratio
of 1:0.9, then adding anti-caking agent sodium dodecyl sulfate, stirring,
maintaining material
temperature to be no less than 90 C, centrifugating and washing to obtain the
solid battery
grade dust-free Li01-1.1-120 which is not caked in vacuum sealed package
within five months.
Example 2-24: Preparation of battery grade dust-free Li01-1.1-120
The preparation process is the same as that of Embodiment 1, and the only
difference is quantity and type of anti-caking agent. Specific results are
shown in Table 1.
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Table 1
No local No local No local
Anti-caking No local
Qualification of caking caking caking
Examples Type of dispersant agent
caking
the products within 5
within 1 within 5
proportion within 3
days month
months
months
Sodium dodecyl Qualified
1 1:1000 4 \I \I -4
sulphonate
Sodium dodecyl
2 1:10000 Qualified 4 4 Ai 4
sulphonate
Sodium dodecyl
3 1:5000 Qualified 4 4 4 4
sulphonate
4 Sodium ferrocyanide 1:800 Qualified 4 4
x x
Sodium ferrocyanide 1:500 Qualified 4 4 4 x
__ 6 Sodium ferrocyanide 1:1000 Qualified Ai
Ai x x
Fatty acid
7 polyethylene glycol 1:1000 Qualified 4 x
x x
ester
Fatty acid
8 polyethylene glycol 1:800 Qualified '4 x
x x
ester
Potassium
9 1:5000 Qualified 4 4 4 4
ferrocyanide
Potassium
1:1000 Qualified 4 \I 4 AI
ferrocyanide
Potassium
11 1:10000 Qualified 4 4 4 x+
ferrocyanide
Sodium
12 1:1000 Qualified 4 4 x xl
hexametahposphate
Sodium
13 1:800 4 4 x x+
hexametahposphate Qualified
Sodium
14 1:500 4 4 x x+
hexametahposphate Qualified ,
Sodium pyrophosphate 1:1000 4 x x x'
Qualified
16 Sodium pyrophosphate 1:800 4 x x x+
Qualified
17 Sodium pyrophosphate 1:500 4 x x x '
Qualified
Sodium
18 1:1000 4 x x x+
silicoaluminate Qualified
Sodium Excessive x'
19 1:500 4 x
x
silicoaluminate sodium
Tricalcium phosphate 1:1000 x x ' x ' x'
Qualified
Excessive
21 Tricalcium phosphate 1:500 4 x+ x+ x+
calcium
Trimeric sodium x+
22 1:800 4 x x+
phosphate Qualified
Trimeric sodium
23 1:500 4 x x+ x+
phosphate Qualified
Trimeric sodium x+
24 1:1000 x+ x+
phosphate Qualified l x
4 in Table I indicates no caking, x indicates caking and, x+ indicates hard
caking.
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=
Qualified mentioned in Table 1 means conformity to the battery grade standard
indicators:
HC1 Water
Fe% Na% K% C1-% S042-% CO2% Ca%
insolubles
insolubles
<0.0008 <0.005 <0.005 <0.002 <0.010 <0.50 <0.005 <0.005 <0.005
According to the results in Table 1, in terms of selection of anti-caking
agent,
attention should be paid to the impact of the introduced substances on the
content of product
impurities. Meanwhile, some anti-caking agent will produce much foam to
seriously affect the
production progress. Thus, the good anti-caking agent includes sodium dodecyl
sulfate,
sodium hexametaphosphate, potassium ferrocyanide and sodium ferrocyanide.
Insoluble anti-
caking agent compounds could easily lead to excessive content of impurities
and can not be
used.
Example 25-48: Preparation of industrial grade dust-free L10111120
(1) Preparation of LiOH solution containing Li20 of concentration of
70 5 g/1
It includes the following steps:
Taking 10000m1 of Li2SO4 leaching solution containing Li20 of concentration
of 38 g/L, adding Ca(OH)2 to adjust pH to 7, filtering, adding 1080g of sodium
hydroxide to
the filtrate, and sufficiently stirring to make it completely dissolve, and
then stirring and
cooling it to -3 C,When the concentration of 5042- in the solution is 35 g/L,
filtering and
separating to obtain LiOH solution and Na2SO4.10H20 solid. Evaporating the
LiOH solution
to volume ratio of liquid-solid about 0.8:1, filtering and separating to
obtain crude Li0H+120;
adding deionized water and stirring to make it completely dissolve and make
Li20
concentration in the solution be 70 g/L.Filtering and separating to obtain the
filtrate, which is
pure LiOH liquid; wherein said LiOH solution contains Li20 of concentration of
70 g/1, and
the S042- of concentration is controlled to be 12 g/L, and the Na20
concentration be 5 g/1 and
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CaO concentration be 0.06 g/1.
(2) Preparation of dust-free Li011.1120 by crystallization process
Evaporating the LiOH solution obtained in Step (1) to liquid-solid volume
ratio
of 1:1.2, then adding anti-caking agent, stirring, maintaining material
temperature to be no
less than 90 C, centrifugating and washing to obtain the solid industrial
grade dust-free
LiOH=1420, its caking situation in vacuum sealed package can be seen in Table
2.
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Table 2
No local No local No local No local
Anti-caking Qualification of caking caking caking caking
Examples Type of dispersant
agent the products within 5 within 1
within 3 within 5
proportion days month months
months
Sodium dodecyl
25 1:1000 A) \) A) A)
sulphonate Qualified
Sodium dodecyl
26 1:10000
sulphonate Qualified
Sodium dodecyl
27 1:5000 Ai Ai Ai Ai
sulphonate Qualified
28 Sodium ferrocyanide 1:800 Ai Ai x x
Qualified
29 Sodium ferrocyanide 1:500 Al \i Ai X
Qualified
30 Sodium ferrocyanide 1:1000 Al Al X x
Qualified
Fatty acid polyethylene x
AI
31 1:1000 x x
glycol ester Qualified ,
Fatty acid polyethylene x
32 1:800 AI X X
glycol ester Qualified
33 Potassium ferrocyanide 1:5000 Ai Ai Ai Ai
Qualified
34 Potassium ferrocyanide 1:1000 Ai AI Ai AI
Qualified
35 Potassium ferrocyanide 1:10000 Ai Ai Ai x+
Qualified
Sodium
36 1:1000 AI \I x x*
hexametahposphate Qualified
Sodium
37 1:800 V Ai x X +
hexametahposphate Qualified
Sodium
38 1:500 Ai \/ x x '
hexametahposphate Qualified
39 Sodium pyrophosphate 1:1000 Ai X X X +
Qualified
40 Sodium pyrophosphate 1:800 Ai X X X '
Qualified
41 Sodium pyrophosphate 1:500 -AI X X X +
Qualified
42 Sodium silicoaluminate 1:1000 Al X X X +
Qualified
43 Sodium silicoaluminate 1:500 Ai x x+ x
'
Qualified
44 Tricalcium phosphate 1:1000 Ai x x+ x'
Qualified
45 Tricalcium phosphate 1:500 Ai x x' x
'
Qualified
Trimeric sodium
46 1:800 \I x x+ x+
phosphate Qualified
Trimeric sodium
47 1:500 Ai X X + X +
phosphate Qualified
Trimeric sodium
48 1:1000 Ai x x+ x+
phosphate Qualified
