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Патент USA US2133251

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“ Patented Oct.1l,1938
2,133,251
UNITED STATES PATENTOFFICE: to
CLARIFICATION AND PURIFICATION OF IN,
DUSTRJAL ACID LIQUORS ’ _
‘ Andrew T. McCord, Metuchen, N. J.,' assignor to
National‘ Lead Company, New York, N. Y.,,a
‘corporation of New Jersey
'
“
‘
No Drawing.v Application October 6, 1937,
Serial No. 167,529 ,
12 Claims. (01. 23-165)
This inventionrelates to the clari?cation and to impart an objectionable odor. By means of
uri?cation of industrial liquors containing ‘the present invention, these disadvantages are
‘
tronginorganic acids.
Ithas particular refer
ence to the removal ofsuspended un?ltrable‘in
5 ‘soluble impurities from sulfuric acid solutions,
‘such as sulfuric, acid solutions‘ of ilmenite. It
‘has equal reference to the‘ puri?cation of waste
acid solutions which are obtained from many
\
industrial processes. ‘ ,
J 0 ,
l
This application is‘ a, continuation-in-part of
“ 3 my ‘previous application, Serial No. 70,109, ?led
‘
on March 21, 1936.
‘ ,
‘
An object‘ of my invention is a simple and eco
nomical, method for removing undesirable, sus
ll pended, solid, un?ltrable, impurities contained in
industrial acid liquors. Another object of my
invention is the removal from such liquors of
residual colloidal organic coagulating agent
and/or decomposition products ‘thereof which
20 may remain in“ un?ltrable colloidal suspension or
in solution in the, acid liquor. These and other
objects of ‘my inventionwill become apparent
from the, detailed description herein set forth.
Prior ‘to my invention,‘ processes have been de
25 veloped‘ for purifying industrial acid liquors ‘by
adding thereto ‘an organic colloid which par
tially ‘settled, out the “ undesirable suspended
solids. Many such processes involve the, use of
glue or similar materials as the organic colloid. I
30 have found that‘prior art processes always ln~
‘volved certain major disadvantages. , First, in
many cases the ‘glue 1or siniilanmaterials failed
to“ remove‘ as completelyas desired the suspended
solid materials. ,Furthermoraeven if the sus:
35' pended material was reduced to a satisfactory
low value, part‘ or all of the coagulating colloid '
‘ itself of ‘decomposition products
thereof re
mained in colloidal suspension or in soluton in
overcome.
.
,
When the acid liquors‘ to be puri?ed are of
the strong acid type the problem of clarifying 5
them by means of an organic colloid is particu
larly acute because such acids tend to act on the
organic colloid forming decomposition products
which are solubléi‘ln the acid liquors and which
are not removed"by~decantation, ?ltration, etc. 10
Thus,-acidsof-the type of hydrochloric, sulfuric. ,
and phosphoric, because they are lr‘ghly ionized,
tend to decompose, e. ,g., as by hydrolysis, organic
colloids such as glue, proteins etc. The products
of such decomposition or hydrolysis are usually 16
amino acids which are soluble in the strong acid
liquors. For instance, amino acetic acid,
NHzCHzCOOH, is a welleknown decomposition
product of glue or protein‘hydrolysis. It should
be noted in this conndction that by the expres- go
sion “strong acid” I refer to such inorganic acid
liquors as hydrochloric, sulfuric and phosphoric
which are ionized to a high degree in aqueous
solutions as distinct from weak acids, such as
acetic, tartaric, oxalic, etc., which ‘are ionized 25
only, to a slight degree. Thus, the concentration
of acid molecules is not to be considered but
rather the concentration of hydrogen ion. It
should also be further noted that by the terms
“residual organic matter” as used by me in the 30
claims attached hereto, I mean to include both
that part of the organic colloid which may re
main in colloidal suspension in the acid liquor
as well as the decomposition products of the
said organic colloid which are in solution in the 35
acid liquor.
‘
‘
Brie?y stated, my invention consists in adding
to the impure acid liquor an organic colloid‘to
the acid liquor after ?ltration, decantatiwon, etc._ remove wholly or partially the undesired sus-'
40 The presence of glue or similar material as;wel1, pended
matter, then adding to the said liquor, 40
,as?the products resulting from the action of the from which
the settled suspended matter may or
\‘ acid on the glue,‘etc., is extremely objectionable may
not have been removed,‘another organic
\_ in_ acid solutions; it causes frothing ‘and foaming colloid capable of precipitating the ?rst colloid
‘ when these solutions are heated as‘in a vacuum
“evaporator; ‘it i‘slsubject to further decomposi
tion giving rise to ‘ obnoxious odors and carbo~
,n‘acjeous decomposition products which act as re
as well as its decomposition products. Thus,my
‘invention consists in the use of mutually coagu- 45
lating organic colloids. The‘mutual coagulation
may possibly be the result of a chemical reaction
ducingagents ‘when the‘acid is heated; it inter ‘or may involve neutralization of opposite elec
’: feres with the use of acid solutions in many trical charges carried by the colloidal materials.
'50 chemical; processes. The presence of glue, gela
I have found that the suspended matter con- 50
tins or other organic colloid and their decompo-. tained
in impure acid liquors may be wholly or
sition products is particularly objectionable in partially
removed by the addition of a colloid se
‘ phosphoricacid which isto, be used for prepar- _
lected ‘from the group consisting‘of glues, gela
1 ing monocalcium phosphate for manufacture of
55‘ ‘ foodstuffs, ‘e. g.‘, baking powder, because it tends
tins, albuminoids, proteins, either of animal or
vegetable origin, and like materials. Fish or ani- 55
2
2,133,261
mal glue is particularly useful in the practice of
this part of my invention. Alginates derived
from varieties of marine algae are also useful.
When such colloids are added to an acid liquor
there is a coagulating effect followed by a set
organic colloid, for example, glue or alginates such
as alginic acids and salts thereof as described
in United States Patent No. 1,619,036 to Ravne
stad. The acidity of thesolution is su?icient to
or all of the suspended matter. However, there is
coagulate the colloid which settles out of solu
tion carrying with it the major part of the
suspended matter. Thus, I have found that
always some part of the colloid itself or a de
even after a clari?cation treatment ‘according to
tling of the coagulated colloid together with part
composition product which remains in suspen
10 sion or solution in the acid liquor and cannot ,be_
the best known methods, of the prior art using
glue as a clarifying agent there will remain in 10
removed by ?ltration or similar methods. At' suspension about 0.04% by weight of suspended‘
the same time, part of the suspended material ‘matter which cannot be removed by ?ltration.
may aisbiremain in suspension. If another 001- - However, the solution being a strong acid (sul
loid possessing the properties of precipitating the
15
_ furic acid) solution, some substantial part of the
‘?rst colloid and its decomposition products, while colloid is decomposed and the decomposition prod 15
itself being simultaneously coagulated and pre ‘ ucts are dissolved in the solution while, at the
cipitated, be added, according to my improved same time, a portion of glue apparently will re
methods, to the "partially puri?ed acid liquor, - main in un?ltrable suspension in the ilmenite
then that part of the ?rst colloid which remains solution. By means of the addition of a mutually
20 in the acid liquor in solution or in un?ltrable. coagulating colloid, for example, tannic acid, ac 20
colloidal suspension will be coagulated and pre
cipitated by the second colloid and the whole
will settle out of the solution carrying down any
remaining suspended matter.
26
,
I have found that tannins are generally useful
in coagulatingthe organic colloids ?rst used in
the practice of my invention. I have also found
cording to my invention, not only the glue and its
dissolved decompositionv products, but also the
?nely-divided suspended matter can be removed
by settling, decantation, ?ltration, etc. The re
sulting solution is excellently adapted for thermal 25
hydrolysis.
.
_
Furthermore, processes for the manufacture of
titaniumpigments yield large quantities of dilute
that tannins precipitate from solution in the acid
liquors, the decomposition products of organic
spent sulfuric acid more or less contaminated
colloids.
with ?nely-divided colloidal titanium dioxide, 30
Whether this is due to a chemical reac
glue, etc. In most cases this acid is discarded
tion between the tannin and decomposition prod—
ucts of the organic colloid forming, for example,
involving a waste of raw material.
an acid-insoluble tannate of an amino acid or
that if this spent acid be’ treated ?rst with an
organic colloid selected from the group‘ including
whether physical and chemical factors are in
volved, cannot be de?nitely amrmed but the fact
I‘have found
glues, g'elatines, albuminoids, and proteins and
containing complex organic acids, together with
then subsequently treated with an organic col
loidal tannin, for example, oak tan or tannic acid,
both the originally added colloid and its soluble
decomposition products as well as any ?nely
the derivatives of such acids, such as their esters,
divided colloidal titanium dioxide can be com
is as stated.
By the term “tannin" I mean to
include all tanning materials derived from vege
table substances including various barks and nuts
glucoside's, etc., which are capable of tanning
pletely removed from the spent acid which may
leather.
then be reconcentrated for subsequent use in the
Bernthsen de?nes tannins as “natu
rally-occurring derivatives of polyhydroxy-benzoic
manufacture of titanium-pigments or other proc-.
acids which are used for converting skins into,
leather”. (Organic Chemistry, 1933, pages 490
esses.
491, published by D. Van Nostrand Company.)
40
Not only is my invention applicable to the clari 45
?cation of ilmenite solutions and waste sulfuric
Such materials may contain tannic acid, gallo-‘ acid but it is likewise especially adapted for clari-'
tannic acid, quinic acid, pyrogallic acid, etc. I i fying'other acid-liquor, for example, phosphoric,
acid.
'
may also use these acids in'pure form to effect
In the wet process for the manufacture of food 50
the coagulation of the organic colloid ?rst added
to the impure acid liquor. It will be understood
grade phosphoric acid, apatite ore is leached with
that my invention is not limited to the use of
dilute phosphoric acid to remove soluble iron and
naturally occurring tanning materials,-but in
aluminum.
The apatite is separated from the
cludes these as well as synthetically prepared‘
liquor by ?ltration, it being necessary'to coagu
tanning materials.
My invention is particularly useful in the art
of manufacturing titanium pigments. As is
known, commercial processes depend upon the
late with gelatin to make this ?ltration'step pos
thermal hydrolysis of a titanium sulfate solution.
Such solutions are obtained by‘ a reaction between
a titaniferous ore and sulfuric acid, followed by
dissolution of the resultant digestion cake in
water or weak sulfuric acid. The resulting solu
tion will contain considerable quantities of sus
pended insoluble material which largely consists
of undissolved portions of the ore. ‘ This suspend
ed material is so ?ne as to be colloidal in character
and cannot be removed by ?ltration.
It is essen
tial, however, that the hydrolysis solution should
70 be entirely free from suspended impurities.
Con
sible.
55
Iron and aluminum are subsequently re
moved from the‘leach liquor which is returned to
the acid system to minimize losses in phosphoric
acid. This leach liquor carries with it an appreci
able amount of gelatin ‘and/or decomposition’ 60
products thereof which gives the ?nal concen
trated phosphoric acid a highly objectionable
“fertilizer” odor'whichv is imparted to any phos
phate compounds, e. g., monocalcium phosphate,
V made therefrom. This may be entirely avoided as,
by the application of my invention.
‘
Only' small amounts of both colloids'are re
quired in the practice of my invention. For ex
ample, a quantity of organic colloid selected from
the group consisting of glues,v gelatins, albumi-‘ 70
noids, and proteins equal to from 1/2 kg. to 2 kg.
sequently, industrial processes for the manufac
ture of titanium pigments comprising an hydrol
ysisv of a titanium, salt solution always involve
a clari?cation treatment of the ilmenite solution.
per cubic meter of acid liquor, is usually su?icient
for the initial step. A ‘quantity of the mutually
coagulating colloid selected from the group con
This clari?cation involves the addition of an
sisting of tannins, organic acids and their derivaJ-J 75
,
r
3
2,188,251
‘ tives contained therein, equal to from 0.1 to 5.0
I have used the term “mutually coagulating” to
a completecoagulation of both organic colloids
‘well as decompositionrproducts thereo?lwhile be
parts‘ to‘ one part of the organic‘ colloid added in ‘denote the property possessed by‘ certain colloids
the ?rst step is usually su?lcient to bring ‘about ‘ j to coagulate and to precipitate other colloids as
‘ ca
and complete removal of all suspended material. ing themselves also coagulated and precipitated
‘,‘Generally, the quantity of tannin to be added regardless of whether a ‘chemical reaction is in- '
“should‘be‘equivalent to the‘ amount of organic. volved or merely a physical effect such as a ‘dis
charge of opposite electrical charges.
‘colloid and decomposition products thereof re;
It will‘beu‘nderstood that as used by me in this
‘maining‘ in suspension in‘the partially clari?ed
acid liquor. “ _It is desirable to use both organic description of ‘my invention and the claims ap 10
“ colloids in the ‘form of aqueous colloidal solutions. , pended hereto, the‘term “tannic acid” includes
the group conslsting‘of naturally occurring tan
i . Example No.17
ning materials, complex organic acids contained
a I‘; A‘ concentrated aqueous colloidal solution of therein and derivatives ofsaid acids which pos
[glue containingl kg‘. of glue on the dry basis was sess the property’ of tanning leather.
‘
15
The foregoing detailed description ‘has ‘been
“ ‘added to one cubic meter of a sulfuric acid solu
tion of ilmenite,
After ?ltration,‘ ' the ilmenite
i
‘
given‘for‘clearness of understanding and no un
solution contained 0.04% of solld‘impurities based ‘ due limitations should be deduced therefrom but ‘
“on the ‘weight of the‘ solution and practically all the appended claims should be construed as
. ‘the glue remained in the ?ltrate either as such broadly as possible‘ in view ‘of the prior art.
‘or as decomposition products thereof. 2.5 kg.of
‘taniuc acid as a‘concentrated aqueous colloidal
1. Method of clarifying industrial acid liquors
solution was then added. The tannic acid coagu
which comprises adding to an ‘industrial ‘liquor
lated‘ the glue and vdecomposition products to form . an aqueous solutlonjof an organic colloid selected
l?ocs which‘ ‘readily settled out ‘of ’ suspension from the group consisting of glue,‘ gelatins, 25
‘Iclaim:“
‘
k
“
'
"
‘ ‘carrying ‘with’ ‘ them‘ the remaining suspended
albuminoids and proteins, said liquor containing
‘material. The solution ‘was then decanted and
a strong inorganic acid in sufficient quantity to
I ‘ ‘?ltered. After‘ ?ltration“ the solution was sub
stantially
. ~ ‘free "of I both‘ suspended‘ matter ‘and
coagulate‘ the colloid which removes by settling
?nely-divided impurities suspended therein, then
organicmatter.
‘
a.
adding an aqueous solution‘of a ‘tanning material 30
.
selected from the group consisting of‘ polyhy
l AV concentrated
, ‘ ‘
Example
"aqueousN0.
‘colloidal
2_
solution
_
of
as‘
1alginate‘ containing alginic‘acid and derived from
marine algae “containing 1.5 kg. of organic col
loid 'on the dryl ‘basis‘was added‘to one cubic
‘ wmeter‘of a spent ‘sulfuric acid solution as a by
‘ {productl‘from
iments.‘
‘a manufacture of titanium pig
,
l
After coagulation and settling, the supernatant
‘40: substantially clear liquor was ‘decanted from‘the
settled alginate and‘titanium dioxide. The de
canted liquor contained a large part of the algi
‘ hate as‘ such and ‘_as‘ decomposition‘ products
‘thereof, as well as a small percentage of colloidal
titanium dioxide. 3.0 kg. of pyrogallic acid as
‘a concentrated‘ aqueousllcolloidal solution ‘was
‘then added: ‘The pyrogallic acid, thelalginate
and ; ‘its soluble decomposition products were
‘mutually coagulated‘a‘nd‘formed ?ocs which set
‘tl‘ed out of suspension carrying with them the re
‘maining suspended titanium dioxide. ‘The solu
tion was then ‘filtered. ‘ The ?ltrate was substan
tiallyrfree from both organic .matter and sus
‘pended‘titanium dioxide and was ready, for re
‘
1‘ concentration ‘prior to reutilization in the manu
.
facture‘of titanium pigments.
)
ii
‘
‘Emqrnple‘NoJ
‘
l i
‘
i
2.5 kgfof gallotannic acid, asa concentrated
aqueous solutiongis added ‘toyone cubic meter of
droxy-benzoic ‘acids and derivatives thereof in
sui?cientr quantity to remove “substantially com
pletely by precipitation residual organic‘ matter
andidecomposed ‘colloid together with any're
‘maining‘?nely-divided suspended impurities.‘
‘
2‘. Method of clarifyingindustrlal acid liquors
which comprises adding “tofan industrial liquor
an aqueous solution of an organic colloid selected
from the group consisting" of glues, gelatins,
albuminoids and proteins, said liquoricontaining a‘
‘strong inorganic acid in su?lcient quantity to
coagulate the colloid whichlremoves by settling
‘?nely-divided impurities suspended therein, then
adding an ‘aqueous solution of a tanning material
selected‘ from the group consisting of polyhy
dr‘oxy-‘benzoic acids and derivatives thereof in
an amount 'substantally equivalent to that of
residual organic matter and decomposed colloid
derived‘ fromj'the previously addedorganic col
loid remaining in the said liquor, to remove sub
stantially completely by precipitation said resid
‘ual‘ organic matter and decomposed‘ colloid‘to
gether with any remaining ?nely-divided sus
pended impurities.
‘_
‘
3. Method ‘of clarifying a sulfuric acid ilmenite.
‘solution which ‘comprises adding to said ‘ilmenite
solution an aqueous solution of an‘organic‘col
loid selected‘from the group consisting of“ glues,
gelatins,'albuminoids, and proteins, said ilmenite
containing, sulfuric acid in suf?cient
,crude phosphoric‘acid leach liquor containing 1.5 solution'
kg, of. gelatin and some ?nely-divided inorganic ~ “quantityto coagulate the‘ colloid WhiQh‘l‘?lllOl/BS
“material; ~ ‘Flocsare formed asaresult‘of‘ the
by‘ settling ‘?nely-divided‘ impurities suspended
mutuallycoagulating action of the gelatin and/ or
‘therein, then adding to the so-treated ilmenite
?ltrate and the gallotannic acid. These ?ocs set
rial selectedfrom the group consisting of poly
gelatin decomposition‘ products. contained in the ‘ ‘solution‘an aqueous solution of a tanning mate
‘hydr‘oxy-benzoic‘ acids and derivatives thereof in
an amount substantially equivalent to that of
residual organic mattter and decomposed colloid
is ?ltered. There is thus obtained a phosphoric .
acidsubstantially completely free from both or-v derived from the previously added organic col 70
loid remaining in the said ilmenite solution to re
ganic matter and ?nely-divided impurities.
move substantially completely by precipitation
From the foregoing description of my inven
said residual organic matter and decomposed col
tion, it will be seen that my novel process is read
loid together with any remaining ?nely-divided
ily adaptable for many industrial uses, particu
tle carrying down any remaining ?nely-divided
, impurities. After‘settling, the supernatant liquor
larly for ‘the clari?cation of strong acid liquors.
suspended impurities.
~
75
' 4
stantially completely by precipitationsaid residual
4. Method of clarifying a sulfuric acid ilmenite
solution which comprises adding to said ilmenite
organic matter and decomposed gelatin together
solution an aqueous solution of glue, said ilmenite
with any remaining ?nely-divided suspended im
solution containing sulfuric acid in suilicient
quantity to coagulate the glue which removes by
settling finely-‘divided Jimpurities suspended
purities.
quantity to coagulate organic colloids, the step
thereimthen ‘adding to the so-treated ilmenite
solution an ‘aqueous solution of tannic acid in
an amount substantially equivalent to that of re
10 sidual organic matter and decomposed glue de
which consists in adding to an acid liquor which
has been previously treated with‘ an organic colloid
‘ coagulating agent and which contains residual 10
rived from the glue remaining in the said ilmenite
organic matter and decomposed'colloid derived
solution to remove substantially‘ completely by
precipitation said residual organic matter and
from the added organic colloid, an aqueous solu
tion of a tanning material selected from the group
consisting. of .poiyhydroxy-benzoic, acids and de
rivatives thereof in an amount substantially
decomposed glue together with any ‘remaining
is
_
8. In a method of clarifying an industrial liquor
containing a strong inorganic acid in sufficient
?nely-divided suspended impurities.
15.
5. Method of clarifying spent sulphuric acid' equivalent to that of. the organic matter and de-v
which comprises adding to such solution an composed colloid contained therein.
aqueous solution of an organic colloid selected
9. In a method of clarifying an ilmenitesolu
from the group consisting of glues, gelatins,‘ tion containing sufilcient sulfuric acid to co
agulate organic colloidsrthe step which consists 20
20 albuminoids, and proteins, said spent acid con
taining sulfuric acid in suillcient quantity to co- ' in adding to an ilmenite solution which has been
previously treated with an organic colloid co
agulating agent and which contains residual
agulate the colloid which removes by settling
?nely-divided impurities-suspended therein, then
adding to the so-treatedsulphuric acid solution
organic matter and decomposed colloid derived _
an aqueous solution of a tanning material selected
from the added organic colloid, "an aqueous solu 25
from the group consisting of polyhydroxy-benz'oic
tion of a tanning material selected from the group
acids and derivatives thereof in an amount sub
consisting of polyhydroxy-benzoic acids and de
stantially equivalent to that _of residual organic
rivatives thereof in an amount substantially
equivalent to that of the residual organic matter
and decomposed colloid contained therein.
30
matteranddecomposed colloid derived fromthe
30
previously added organic colloid remaining in said
sulphuric acid to remove substantially completely
10. In a method of clarifying an ilmenite solu
by, precipitation said residual organic matter and
decomposed colloid together with any remaining
agulate organic colloids, the step which consists ‘
?nely-divided suspended impurities.
in adding to an ilmenite solution which has been
6. A method of clarifying crude phosphoric acid
which comprises adding to aicrude phosphoric
previously treated with glue and which contains
residual and decomposed organic matter derived
tion containing su?icient sulfuric acid to co
acid solution an aqueous solution of an organic
from the glue an aqueous solution of tannicacid .
colloid selected from the group consisting of glues,
in an amount substantially equivalent to that of
geiatins; albuminoids, ‘and ‘proteins, said crude
the organic matter contained therein.
.40 acid containing phosphoric acid in suillcient
-
quantity to coagulate the colloid which removes
vby settling ?nely-divided impurities suspended
therein, then adding to the so-treated phosphoric
in adding to a spent sulfuric acid solution which
‘acid solution an aqueous solution .of a tanning
has been previously ‘ treated with an organic
40
colloid coagulating agent and which contains
polyhydroxy-benzoic acids'and derivatives there
of in an amountsubstantially equivalent to that of
residual organic matter and decomposed colloid
‘derived from. the previously added organic colloid
remaining in suspension in said phosphoric acid
50
to remove substantially completely by precipita
tion said residual organic matter and decomposed
colloid together with any remaining ?nely-divided
55
,
11. In a method of clarifying spent sulfuric '
acid containing suf?cient sulfuric. acid '_to co
agulate organic colloids, the step which consists
45 material selected from. the group consisting of
35
residual‘ organic matter and decomposed colloid
derived from the added organic colloid, an aqueous
solution of a tanning material selected from the
group consisting of polyhydroxy-benzoic acids and
derivatives thereof in an amount substantially
equivalent to that of the organic matter and de 50
composed colloid contained therein.
i
12. In a method of clarifying crude phosphoric
suspended impurities.
_
acid containing sufficient phosphoric acid to co
-7_. Method of clarifying crude phosphoric acid agulate organic colloids,>the step which consists in
which comprises adding to a crude phospohoric adding to a crude phosphoric acid solution which
acid solution an aqueous solution of gelatin, said‘ has been previously treated with an organic colloid
crude acidcontaining phosphoric acid insu?icient coagulating agent and which contains residual
quantity to coagulate the gelatin which removes organicmatter and decomposed colloid derived
by settling ‘finely-divided impurities suspended
' from the added organic ‘colloid, an aqueous solu
therein, then adding to the so-treated phosphoric
acid solution an aqueous solution} of pyro-tannic
acid in an amount substantially equivalent to that
of residual organic matter and decomposed ‘
gelatin derived from the gelatin remaining in sus
65
pension in said phosphoric acid to remove sub
tion of a tanning material selected from the group
consisting of polyhydroxy-benzoic acids and de
rivatives thereof in an . amount substantially
equivalent to that ofv the organic matter and de
composed colloid contained therein. ‘
'
ANDREW T. MoCORD..
Q
60
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