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E. LAIST, F. F. FRICK & R. S. OLIVER.
PROCESS 0F PREPARING ALUMINA.
APPLICATION FILED APR. l0, i918.
Patented Apr. 15, 1919.
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sTATíEs PATE "
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FREDERICK LAIsT, FREDERICK E. EEICK, AND ROBERT s. oLIvEn, 0E ANAcoNDA,
_
MCNTANA, AssIGNoEs To ANACCNDA COPPER MINING COMPANY, or ANACoNDA, ,
MONTANA, A CoaronATIoN or MONTANA
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PROCESS Í02E' PREPABING ALUMINA.
Speciñcation of lLetters Patent.
1,300,417.
Patented Apr. >15,191.9.>
Application ñled April 10, 1918. Serial No. 227,722.
To all 'whom it may concern:
‘
This is however merely a preferable Imode’ 55
Be it known that we, (1) FREDERICK LAIsT, of procedure: For example, the solution
(2) FREDERICK _F. FRIox, and (3) ROBERTS. may be run into ponds or other- crystallizing
OLIVER, citizens of the United States, resid system where the cooling will take place
ing at Anaconda, in the county of Deerlodge slowly', in which case the crystals` will be
and State of Montana,_have invented cer large in size. The crystals obtained by 'the 60
tain new and useful Improvements in Proc method first described are somewhat purer y
esses of Preparing Alumina, of which the than (those obtained by the latter method."
following is a specification.
10
This invention is a process applicable to
If the iron in the original solution has
been completely reduced to the ferrous state
the preparation of commercially pure alu before the addition of‘potassium sulfate, the,
mina, particularly from ’clays or equivalent resulting alum will be remarkably free from
silicates of aluminum. Clay- is essentially a iron. This is highly important, especially '
in case the aluminum oxid eventually pro
erally mixed with some quartz. Clay to be duced is to be used for the manufacturefof
treated in accordance with this process metallic aluminum. By proceeding in the 70
more or less impure aluminum silicate, gen
15
should preferably be reasonably low in iron, manner first above described, we have suc
calcium and magnesium. Potassium may or
may not be present.
20
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The process in its preferred embodiment does not exceed 0.10 per cent.
The alum is now dried and ignited to'a 75
is cyclical in character, and is indicated in
the accompanying drawing, which is a dia temperature approximating 1000° C. The
gram in the form of a flow sheet >of the
25
ceeded in preparing L from@ ordinary clay
aluminum oxid of which the iron content
ignition is preferably carried on in a fur- `
process. The operation thus indicated is as nace similar to' a by-product coke oven, or
follows :
in an electric furnace; that is to say in suchThe clay is first mixed with concentrated type of furnace that fire gases do not become 80
sulfuric acid, and the mixture is heated to mixed with the gaseous products from the
30W-400o centigrade in order to decompose
the aluminum silicate, as well as potassium
30 silicate, if present. This reaction results in
the formation of aluminum and potassium
sulfates, more or less sulfate of iron being
likewise produced. The soluble sulfates are
dioxid and oxygen, into sulfuric acid; and
the production of sulfuric acid is much sim
now extracted by means of hot water, or- a
plerwhen the gases are relatively pure. ' Tt
decomposition ofthe alum. This is forthe
reason that the process contemplates the con
version of such gaseous products of decom
position, comprising sulfur trioxid, sulfur
85
solution of potassium sulfate, and any ferric is understood, however, that the ignition
iron in ‘the resulting solution is reduced to may be carried on in oil >or gas-fired fur
the ferrous state by means of metallic alu
naces of any type.
minum, metallic iron,‘sulfur dioxid, or fother
We have found that under the preferred
'operating conditions approximately 2O per
The solution which now contains essen
cent. of the sulfuric acid combined with the
appropriate reducing agent.
40
‘
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tially aluminum sulfate, ferrous sulfate, and aluminum is expelled in the form of sulfur 95
possibly potassium sulfate, is filtered from trioxid (S03) . This may be separated from ’
the residue which consists chiefly of silica. the mixture of sulfur dioxid and oxygen’ by
The clear solution is mixed hot with suffi
any appropriate method, such Aas electro
cient potassium sulfate (unless this has been static precipitation, or absorption in con
added to the leaching solution) to form centrated sulfuric acid. The sulfur dioxid
potassium alum by reaction with all of the may likewise be converted into sulfuric acid
aluminum sulfate contained in the solution. in accordance with _the well known methods.
Preferably the solution is then cooled as The sulfuric acid thus produced is applied
50 rapidly as possible, and is stirred while cool
to the treatment of a fresh batch of clay in
.ing in orde-r that the resulting crystals'of a repetition of the process.
The solid residue remaining after the ig
potassium alum may be of small size, The
precipitate formed under these conditions is nition of the alum is essentially a mixture of
similar in appearance to granulated sugar. aluminum oxid and'potassium sulfate. This
45
100
105
1,300,417
2
miXture is leached with Water. The residue fates, and dissolving the saine; reducing
any ferrie iron to the ferrous state; adding
to the solution potassium sulfate in propor 55
tion to conyert the aluminum sulfate into
consists of commercially pure aluminum
oxid, and after drying is ready- for use in
the production of metallic aluminum, or for
any other purpose for which commercially
pure aluminumI oXid is required. The solu
tion of potassium sulfate is either used di
potassium alum; crystallizing' the alum and
igniting the same >at 'a su?licient tempera
ture to produce alumina, potassium sulfate,
returning the potassium sulfate to the proc
rect for leaching fresh batches of sulfatedv and oxids of sulfur ;'recovering the alumina;
clay or is evaporated, and the potassium sul
60
fate is returned to' the cyclical process at ' ess at the appropriate stage for producing.
l the appropriate stage for the precipitation with aluminum sulfate additional quantities '
10
of alum from fresh batches of .aluminum of potassium alum; and converting the oXids
of sulfur into sulfuric acid applicable for 65
Ã
'
Inf case the clay contains potassium there use in the treatment of further quantities
Will Abe a corresponding accumulation of I¿of the aluminous raw material.
3. In a process of preparing commercially
» potassium sulfate, which may of course be
marketed or disposed of in any desired man pure alumina from aluminous raw'v mate
sulfate.
ner.
4
rials, the steps which consist in converting
-
In so far as 'sulfates of the other alkali the alumina component ofthe raw material
into aluminum sulfate; reacting thereon»
metals may be capable of replacing potas
sium sulfate in this reaction they'are to be with potassium sulfate to produce potassium
regarded as equivalent thereto for the pur alum; and recovering potassium'sulfate and
commercially pure alumina from the alum
poses of this- invention.
»
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l
It is >obvious that the process above de thus produced.l
4. In a cyclical process of preparing com
25 scribed as applicable to thev preparation of
alumina from clay, is equally applicable to > mercially pure alumina from aluminum sul
the preparation of alumina from aluminum fate, the steps Which consist in reacting upon
sulfate from any source, including alunite aluminum sulfate in aqueous solution Wit'.
or the like.
We claim :---
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-1. A cyclical process of producing com
mercially pure alumina from aluminous raw ._
materials,~ comprising treatin the alumi
35
nous material with sulfuric acid in propor
tion sufficient to convert the bases intoy sul
80
potassium sulfate to produce potassium
alum; decomposing the alum by heat to pro
duce commercially pure alumina and po
tassium sulfate; and utilizing the recovered
potassium sulfate in a repetitlon ofthe proc-` .85
ess.
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,
,
5. In a cyclical process of preparing com
fates, and dissolving the same; reducing any mercially pure alumina from aluminum sul- `
ferrie iron to the ferrous state; adding to fate contaminated by ferrie- iron,` the steps
the solution potassium sulfate in propor Whlch consist in reducing the ferric iron to 90
tion to convert the aluminum sulfate into the ferrous state; treating the resulting alu
40
potassium alum; crystallizing the alum and
minum sulfate in aqueous solution with po-V ‘
tassium sulfate in proportion to produce po
ture to produce alumina, potassium sulfate, tassium alum; crystallizing and recoverlng 95
and oXidS of sulfur; recovering the alumina; the alum and decomposing the same by heat
and returning the potassium sulfate to the to produce commerclally pure alumina and
potassium sulfate; and utilizing the re
45 process at the appropriate stage for produc
ing With aluminum sulfate _additional quan covered potassium sulfate in a repetition of ’
the process.
vtitles of potassium alum.
igniting the same at a sufficient tempera#
.
2. AAcyclical 'rocess of producingv com
In testimony whereof', we affix our signa
mercially pure a umina from aluminous raw tures.
50
materials, comprising treating the alumi
FREDERICK LAIST.
nous material with sulfuric acid in propor
tion suíiicient to convert the bases -into sul
ROB-,ERI` -S.» OLIVER.
FREDERICK F. FRICK.
100