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Патент USA US2608469

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Patented Aug. ze, 1952
ßibrahamL. Fox, Washington, D. C‘., assigner` tor ‘y
ReginalddS. DeanfWashington, D. C.
` ’
o Drawing', Application. Deiuei‘nberlä,` 1948',
Serial No. 65,5740
‘ _
v(c1. 23-145)
" _
This invention relates to an active form of
manganese dioxide and processesfor preparing
polarized light shows that allparticles arecrys;
it. It has for its aim the provision of a new form
tice .parameters of rhodocrosite and ,examination
of manganese dioxide having properties making
with the electron.` microscope- shows _polyhedral
talline.Í X-ray spectrometry shows onlythelatf
it especially1 suitable for use asma _depolarizerin 5 crystals of. an average diameter of` Z-»micronse
dry., cells, `for the oxidation ot` organic chemical
This material ispinl; in "color vand `stable in air
compounds and for other purposes., _
at-room temperature.
_ .
L The manganese Adirnride of thisV invention is
Themanganese canbonate
is heated inairto 570° F; and the> material anar
especially suitable for use in _dry_»cells ofthe Le
lyzed at several periods with the following rer
Clanche> _type._ This arises fromthe fact that 10 sults:
it combines a higher electrical conductivity than
Time (mín ) _
heretofore known with great reactivity as re-`
vealed byÁbyinitial
long shelf
life of
high stability as
-- ` e» 60
______ ` ““““““““““““““““““
ture of the improved battery oxide of this inven-
tion starts in all cases with the preparation of ¿a
‘ “ f
Examination of the product under the electron
fully crystalline precipitated manganese car-`
microscope shows the product to have- a «particle
bonate having a crystal size from 0.25 micron to
size. of 2 microns average diameter.
6 microns average diameter.
The oxidation of 20
manganese carbonate has been heretofore em-
- >
Example II
ployed for the manuf'actureoi .battery oxide but
11.1;ake‘50 grams‘of manganous carbonate hav-_
With íïldilîerent results. It iS .ÍYIIDOl‘ÈßJlÈ that the
ing„completely crystalline particles 0.25 micron
preoioitated‘oarbonate be free from» amorphous
in diameter. Thismaterial is pìnkin eclo'r'and
material and havethe crystal structure of rhodo- 25 Stable in ‘dry air. The manganese carbonateis
@rosita the individual Crystals boina Within the ‘
heated to 300° F. in air and the material' analyzed
Size range stated. - Such mangaHGSerarbOIwJG
at several periods with the following results.
will not appreciably darken in` air lateroom tem-
,L __
peratures even` when stored ‘over long periods.
Tl‘me» (hours):
Per' cent M1102
Manganese carbonate «precipitates cfiñner crystal 30
size darken when` stored in'` air and coarse par-'- I
ticles, such as may bemade by grinding natural
rhodocrosite, do notoxidize readily enough on
heat-'mg' ï prefer tp make ¿thee manganese caff'
. .
., . _èrfe-f-e-„G‘Íë
Examination» of` the product under `the- electron
bonate‘foniltçpmctlce ,OfmYmVent-lon fromcom" 35 microscope shows'thepartìcle size to be thatfói'
plFX. animomlaçal 501111519115 m'the manne!" Whlçh " the‘c’rystal‘s ofthe carbonate used namely,- about
will be set forth later. Any manganese carbonate
meeting the herein stated requirements may.
however, be satisfactorily used. Themanguanese
0,;25rmìcmñ ‘
" ‘
' Examplelïï.
dioxide produced by the pmcüße 0f .my ÍHVGHÜOT? 40 ~ `l' ’take 100 grams of? manganese carbonate
Wm 'have ‘the Same particle Size. as the Crystal
Size 91° the manganese caï‘bona'te‘ffom WhÍCh it is
J _
In the practice or my lnvention I` take. this
‘ precipitated from aV complex manganese ammonia
solution in `accordance»with` the procedure` dee
scribed later herein.
This‘material is'fullycrys
tallineand has a grain size of 2` microns diameter.
manganese carbonate and heat 1t 1n air within 45 I` fui-_er but do not‘wa‘s‘h this_‘materíal so' thai-_fit
the temperature range 30W-600° F. for a SufïïCleflt
is `saturated` with ammonia andiammonium car-.
mme t0 pï'QduCe a product @Cmamïng from 50*
bonate. This material is dried in airandturns
70% M1192»
i y
black. .Itis then ynearest in air abaco?
The time necessary to accomplish this result
hours; .'*The resulting. product ¿analyzes 64%
depends 0n the [email protected] _At 500° F- it is 50 MnOz. It diiiersvfromethe.products of theepre.-V
about 2 hours and at 3_90" F- 1t 1S 21»190Wl 15 hOUl‘Sceding examples,- lhowever. in that the particle
Heatms for al? eddltlonal ’time has `very little
sizeef'the manganeseidioxide.iene.longer that
effect on the oxide.
of the :originalmanganese carbonate-crystals but
The fOllOWl'Ils eXäm'ples `are given aslllustffatîve
of this embodiment of `my; invention;
_j ' "l
isveryimuch smaller, lbeing in-this instaneeonly
55 (p25 mîcmm?.`
_ Toincreaseflthe M_nOz content of the` prod_
_’ _ _
I take lûll‘grams of manganese_carbona‘tehaving a composition manganese 44.3%, carbon
ucts-of« the foregoingexamples I~ iindthat- they
may ‘toe leached` with dilute acids which»` forni»
soluble manganese saltssuch as sulphuric or
@19eme î43l6_%1;vate§7f26%- Examinationguhdîer ‘GQ nitric acidsor. with.. ammonium salts of such
acids which dissolve MnO, such as ammonium
chloride'V or sulphate. After such leaching the
MnOz is washed with water until after «boiling
containing 65% MnOa This is 'made into a
slurry with water containing 20% solids. It is
carbonated by passing CO2 through the violently
agitated slurry for 15 minutes at such a rate that
50% excess over the stoichiometric equivalent of
than four is reached. This requires exhaustive
the 22.1% MnO present in the sample is passed
washing. The following examples are given as
through the solution. The slurry is then filtered,
illustrative of this embodiment of my invention.
washed, dried and reoxidized. The resulting
Example IV
product contains 75.9% M1102 and 58.0% Mn.
I take 100 grams of precipitated manganese 10 This gives a ratio of Mn as MnOz/Mn of 82.8%.
carbonate, fully crystalline, stable in air and _ An additional carbonation and reoxidizing gives v
a product having a ratio Mn as MnO2::Mn of
having an analysis of manganese 44.4%, carbon
89.7%. This product contains 2.2% H2O.
dioxide 43.7%, water 7.0% and a crystal size as
determined with the electron microscope of 3
Example VII
microns average diameter. I heat this material
I take 100 gi‘ams of the product `ò'f Example 11
in air at 300° F. for 81/4 hours. At thi-s time it
analyzes 53.0% MnOz. This material is Vigor
containing 64% MnOa I make this into a slurry
one gram with 100 cc. of water, a pH of more
ously boiled with a 10% solution of NH4Cl con
taining three times the amount of NHiCl neces
sary to combine with the unreduced manganese
pounds/square inch pressure with agitation.
oxide and liberate ammonia. After this leaching
treatment, the material is washed, dried and
assayed. It contains 79.0% MnOa
Example V
allow the reaction to proceed >until no further
CO2 is absorbed. This takes only about 10 min
utes. The carbonated product is filtered, washed
and dried. It is then heated in air for 24 hours
at 470° F. and the carbonation and oxidation
, I take 100 grams of manganese carbonate pre
as follows:
pared by decomposition of complex ammoni-a
manganese carbonate solution by ceiling, and
having'a crystal size of 2 microns, and heat in air
for-'24 hours at 475° F. This p-roduct analyzes: 30
procedures repeated. The final product analyzes
Per cent
Mn ___________________________________ __ 62.8
Per cent
________________________________ __ 69.0
________________________________ __ 90.8
_________________________________ __
H2O __________________________________ __
State of oxidation MnOrsis.
Mn ___________________________________ __ 59.3
_________________________________ __ 20.3
State of oxidation MnOmss.
This» material is leached with enough 10%
The water content recorded in these analyses
is determined by heating the sample lair dried at
105° C. to 800° C. in air dried over calcium
chloride and absorbing evolved water in calcium
H2SO4 to combine with the MnO. The leached
chloride. The water content for the product of
product is filtered, wash-ed and dried. It contains
this invention ranges from 1.8-4.5%, depending
by analysis:
40 on the particle size of the final product. The
Per cent
smaller the particle size, the higher the water.
M1102 ________________________________ __ 87.4:
The pH of the battery oxide prepared accord
Mn ._`_ _________________________________ __ 60.5
ing to the method described, as determined by the ,
_________________________________ __
standard method of the Signal Corps, ranges
State vof oxidation MnOrci.
45 from 7-9. It is accordingly well within the re
quirement of a pI-I higher than 4.0.
I"have found Ithat the unoxidized manganese
My` invention for the improvement of the man
oxide in the oxidized product may be converted
ganese dioxide content of materials containing
to carbonate by treating in a water slurry with
CO2,A >This carbonated product may be further l
essentially MnOz and MnO in a ratio of at least
oxidized by heating in the same temperature 60 one molecule of MnOz to one of MnO by carbona
tion and oxidation by heating in airis applicable
range as before, with the result that the manga
to such mixtures formed in other ways than the
This procedure may be repeated a number of
heating of carbonate as set forth in the preced
ing examples.
times ywith an increase in the MnOz at each step.
Such mixtures of MnO and MnO2 may, for ex
This increase is approximately 40% of the> un 55
ample, be formed by partially reducing natural
oXidized manganese remaining so that the in
or artiñcial MnOz. This may be accomplished
crement` of manganese oxidation obtained by
thentreatment is less for each succeeding step.
by heating in air or in a reducing gas. The lower
the temperature at which such partial reduction
Thus, _if the partially oxidized material contains
69% MnOz and 20.3 MnO, as in Example V, the 60 is carried out, the easier is the carbonation. As
ñrst treatment will leave about 12% MnO, the
illustrative of this embodiment of my invention,
I give the following examples:
secondabout 8% and the third about 6%. After
these three treatments, the state of oxidation of
Example VIII
the> _manganese will beV about Mn01.92.
The amount of CO2 required is the stoichiomet 65
I take 100 grams of pure MnOz made by the de
ric equivalent of the'MnO present. However, as
composition of manganese nitrate. I heat this
the reaction is slow, an excess of at least 50% is
for 5 minutes at 400° C. in a stream of hydrogen.
nese is further oxidized.
passed through the slurry. The carbonation
The resulting product analyzes 60.2% MnOz. I
process can be considerably expedited by con
make a, slurry of this product with 80% water
ducting it under _a pressure of several atmos 70 and pass in CO2 with stirring under 100 pounds
pheres. As illustrative of this embodiment of
my invention, I give the following examples:
Example VI
I take 100 grams of the product of Example I 75
per square inch pressure until no further CO2 is
absorbed. The carbonated material is washed.
dried and heated at 470° F. for 24 hours. -The
carbonation and heating steps are repeated once.
The final product dried at 105° C. has the follow
ing analysis:
75° C. Eighty-five percent of the manganese is
Per cent
Mn ________________________________ _‘.___ 62.8
M1102 _________________ _'. _______________ __ 90.8
M110 ______________________________ _..“_____
_________________________ _; _______ __
State of oxidation MnOrsis.
precipitated as carbonate. The carbonate is ñl
tered, washed with water and dried. It is stable
in air and has the following analysis:
Per cent
Mn ___________________________________ __ 44.0
CO2 _________________________________ .-.___ 43.3
H20' __________ I; ________________________ __
Example IX
10 The crystal size is 0.25 micron average diameter.
Regardless of the particle size, the manganese
I take 100 grams of a natural manganese ore
dioxide of rmy invention has new and important
containing 90.5% M1102 -200 mesh. I heat this
properties making it valuable as a battery oxide.
for `5 minutes in air at 750° C. The resultant
electrical resistance of the battery oxide of
product contains 78.1% _MnO2. I make a slurry
my invention is less than that of heretofore
of this product with 80% water and pass in CO2
known battery oxides. The vspecific resistance
with stirring until no further CO2 is absorbed.
of the product of this invention varies from
This product is ñltered, washed» and dried and
about 2000` to about 6000 ohm cm. For the
heated in air for 24 hours at 470° F. The result
purpose of comparison` I have made measure
ments in the Vsame way on Gold Coast ore of
The properties of such manganese dioxide, par 20 battery grade and lined a resistance of 80,000,
ticularly as they relate to its value as a battery
30,000 for oresV -activated by acid leaching,
oxide, depend especially on its particle size. This,
500,000 for precipitated amorphous oxides and
ing product contains 88.2% MnOz.
i-n turn, is determined by the particle sizeof the
10,000 to 12,000 for electrolytically prepared
carbonate from which it is prepared. In carry
battery oxides.
ing out my invention I prefer to control the crys
It should be understood that the high elec
tal size of the manganese carbonate. This I can
trical conductivity of the battery oxide is only
do by precipitating the carbonate from’the com
obtained if all the steps of any embodiment of
plex formed by dissolving MnO in solutions of
my invention are carried out. For example. the
ammonia and ammonium carbamate-carbonate
oxidation of manganese carbonate in accordance
mixtures. This may be done lby either dilution 30 with my process does not yield a highly con
or heating, both of which shift the equilibrium
ducting oxide. The high conductivity is only
from carbamate to carbonate. The higher the
conferred by the second step of leaching with
temperature and the greater the concentration of
acid or carbonating and reoxidizlng. Carbon
ammonia and ammonium carbonate in the solu
ation and reoxidation is especially effective in
tion from which the carbonate is precipitated, the
this connection. Such treatment in a typical
larger will be the crystal size.
example decreases the speciiic resistance from
The following examples are given as illustra
about 100,000 ohms to 3,000 ohms.
tive of this embodiment of my invention:
The battery oxide of my invention ¿is char
acterized by the so-called »y structure` as de
Example X
termined by X-ray spectrometry. Lattice param
I take 100 grams of MnO and dissolve it in a
eters and intensities of a typical product of
the present invention are as follows:
solution containing 500 grams NHiOH and 75
grams CO2 per liter. The solution is ñltered to
d, Ängstroms:
remove any residue and heated in an open con
tainer until substantially all the manganese has 45
been precipitated as carbonate. The carbonate
is filteredI washed with water and dried. It is
stable in air and has the following analysis:
Per cent 50
Mn ___________________________________ __ 44.3
CO2 ___________________________________ __ 43.6
H2O __________________________________ __ 7.3
The crystal size is about 2 microns average diam
Example XI
Intensity, relative
_______________________________ __
_______________________________ ..._
________________________________ __
_______________________________ .__
_______________________________ .__ 7
________________________________ __ 10
_______________________________ .__ 3
________________________________ ___
________________________________ __ 2
________________________________ _..
________________________________ __ 2
Examination of the product by the electron
microscope shows anhedral rounded somewhat
I make the same solution as in Example X but
porous particles of approximately uniform size.
instead of heating in an open vessel, I heat the
The relationship of initial battery discharge
solution in a pressure-tight vessel to 90° C. for
one hour. Ninety-ñve percent of the manganese 60 capacity to particle size for the battery oxide of
this invention is shown in the following table:
in the solution is precipitated as carbonate. This
carbonate is filtered and washed. It is stable in
air and has the following analysis:
Per cent 65
Particle Size
Mn ___________________________________ __ 44.8
CO2 ___________________________________ __ 44.1
__________________________________ __
Average Average
g Capacity
The crystal size is about 5 microns average diam
âlâ? Resistance, Vâ‘tlg e Initial Cîlfìaîlgy
0.25 ........... -_
110. Ü
90. Ü
2.0 ............ __
165. 2/3
1. 13
95. 0
Y 93. s
5.0 ............ _..
166. 2/3
166. 2/3
1. 13
1. 13
88. 0
88. 0
Example XII
The cells were of standard Le Clanche type.
I prepare the solution as in the previous two
The tests were at 70° F.
examples. I then dilute it with an equal volume
What is claimed is:
of Water and heat in a closed vessel for 6 hours at 75
1. The method of producing a manganese
the product.
carbonate of a particle ,size .25 to 6 microns by
`heating in an atmosphere containing oxygen
to a temperature from 300° to 600° F. carbonat
sure of several atmospheres.
in'g said oxidized carbonate by treatment with
carbon dioxide and water, and then further
oxidizing the carbonated product by heating to
a temperature of 300°_ to. 600° F. in an atmosphere 10
3. The process defined in claim 2, in which
the carbonation step is conducted under a pres
completely crystalline vprecipitated manganese
substantially to increase the oxygen content of
oxide suitable for depolarization of dry cells
which includes the steps of partially oxidizing
. f
4. The process defined in claim 2, in which
the carbonation and re-oxidation stepsV are re-`
peated at least once.
_' 2.'jProcess of improving therbattery grade of
The following references are of record in the
a manganese oxide product >corresponding in
ñle of this patent:
oxygen contentto a mixture of MnOz and MnO
in which the molecular ratio of MnOz Ato MnO 15
is at least 1:1, which comprises carbonating the
manganese oxide product by treating the same
inthe presence of Awater with carbon dioxide in
an „amount substantially in excess of the stoi
chiometrical> equivalent of the calculated MnO
content of the starting material, and subjecting
the carbonated product to oxidation treatment
by 'heating it to a temperature of from 300° to
600° F. in an atmosphere containing free oxygen
1,448,110 v
Ellis et al. _______ __ Aug. 13, 1918
Kaplan __________ __ Feb..4:, 1919
De Olaneta ______ __ Mar. 13, 1923
Laury ____________ __ June 3, 1930
Kobe ____________ __ Nov. 29, 1932
Bradley ..... _;____ Feb. 20, 1934
Kato ________ -_,_„„_ Jan. 22, 1935
Muller et al. _____ __ July 12, 1938
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