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Патент USA US2407261

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Patented Sept. 10, 1945
2,7,2l
~. 'E‘ES
P'E‘EN'E'
QFFICE
2,407,261
PRGCESS FGR STABILIZING 0R DEACTIVAT
ING SLUDGES, PRECIPITATES, AND RESI
DUES OCCURBING 0B USED IN THE MAN
UFA€TURE 0F‘ TETRAALKYL LEADS
Frederick E. Downing, Penns Grove, N. J ., and
Adrian L. Linch, Wilmington, DeL, assignors to
E. I. du Pont de Nemours & Company, Wilming
ton, $21., a corporation of Delaware
No Drawing. Application September 16, 1942,
Serial No. 458,578
9 Claims. (Cl. 260——437)
1
2
This invention relates to a process for stabiliz
ing or deactivating sludges, precipitates and res
idues occurring or used in the manufacture of
plication Ser. No. 393,680. However, even in
these cases the sludge which is deposited by the
action of the oxidizing agent and which invar
iably contains tetraethyl lead, tend to ignite
when exposed to air thus presenting serious ig
nition hazards, making it desirable that even
these sludges should be deactivated during their
tetraallzyl leads, and which normally tend to pro
mote decomposition and ignition of the tetra
alkyl leads that may be contained therein.
It is known that alkyl metal compounds in
general are quite unstable and decompose read
1137, particularly in the presence of air or oxygen.
formation or afterwards to permit of their re
moval and disposal in a safe manner.
It is therefore an object of this invention to
It has also been found that these alkyl metal 10
provide a process for stabilizing sludges, precip
compounds are particularly unstable when ad
itates and residues occurring in the manufacture
sorbed on materials which present a large sur
of tetraalkyl lead compounds whereby the igni
face area pcr unit volume such as silica gel, clays,
tion hazard presented by the lead alkyl com
alumina, earths, asbestos, charcoal, and mate
rials of similar structure which materials appear 15 pounds in contact with such catalytic surfaces is
reduced or completely overcome.
to exert a catalytic effect in the decomposition
It is a still further object of the invention to
of these alkyl metal compounds. Even tetra
render inactive materials which tend to exert a
alkyl leads such as tetraethyl lead which is known
catalytic effect in the decomposition of tetraalkyl
to be somewhat more stable than some of the
other alkyl metal compounds decomposes and 20 leads in the presence of air thus permitting the
often ignites in the presence of oxygen when
small amounts are adsorbed on materials that
offer extended surface areas, particularly when
the masses containing the tetraethyl lead are
exposed to temperatures somewhat higher than
normal atmospheric temperatures. The tend
safe use of such materials as ?lter aids in the
manufacture of tetraalkyl lead.
We have found that the sludges, precipitates
and residues occurring in the manufacture of
tetraalkyl lead which tend to catalyze the decom-'
position of tetraalkyl lead compounds contained
therein when in contact with oxygen or air can
ency to oxidize and ignite of course varies with
be rendered relatively stable to oxidation and ig..
the substance with which the alkyl metal com
nition by incorporating with such materials a
pound is incorporated, some materials apparent
ly exerting a greater catalytic effect than others 30 compound of the class consisting of alkali metal,
ammonium and organic amine sul?des, polysul
in promoting ignition of the alkyl lead com
pounds.
?des, and sulfhydrates; organic mercaptans and
organic compounds which contain the sulfhydryl
In the manufacture of tetraalkyl leads, such
radical (—SI-I), or compounds which contain
as tetraethyl lead, tetramethyl lead and the mixed
ethyl-methyl lead compounds, sludges are formed 35 such radical by tautomerization.
We have found that the sludges originating in
from which it is diflicult and, from a practical
the production of tetraethyl lead, or other mate
standpoint, impossible to entirely free from the
rials such as ?lter aids used in the process which
alkyl lead compounds during the normal steam
offer large surface area per unit volume are de
distillations or decantation operations. There is,
therefore, carried through the process very ?nely 40 activated conveniently and economically by wash
ing with aqueous solutions of the sulfur com
divided lead and impurities such as bismuth com
pounds which, although present in very small
amounts, ?nally are deposited as sludges in the
pipes and tanks and other processing equipment
and these sludges which contain tetraethyl lead 45
adsorbed therein when exposed to oxygen or air
often ignite, thus presenting serious ignition and
pounds of the types above described, irrespective
of whether such materials contain the tetraalkyl
lead compounds at the time they are washed with
such sulfur containing solutions or whether they
are later incorporated therewith. Where ?lter
aids are employed in the ?ltering of the tetra
alkyl lead compounds these aids such as clays,
explosion hazards in the process.
Methods have been advanced for the removal
silica, earths, charcoal, etc., which tend to cata
of practically all the sludge forming materials 50 lyze the decomposition of small amounts of the
tetraalkyl leads contained therein may be ren
from the tetraethyl lead after its distillation,
such as by controlled blowing with air or oxygen
dered inactive by washing them with the sulfur
with agitation, preferably under a layer of water,
containing compounds of the classes above men
followed by separation of the precipitated sludge,
tioned so that when they are subsequently em
as more particularly described in copending ap- 55 ployed either before or after drying in the ?ltra
2,407,261
3
4
tion of the tetraalkyl lead they no longer cause
the ignition of the residual tetraethyl lead on ex
posure to air even at steam bath temperatures,
thus facilitating their removal from the system
and ?nal disposition.
In the storage of crude tetraalkyl lead com
pounds prior to ?nal puri?cation, sludges are
be employed to effect good physical contact be
tween the solution and the adsorbed material.
Where inorganic hydrogen sul?de compounds
rial No. 393,680. The precipitated sludge, which
are employed they should be used in a slightly
alkaline medium (in a medium of a pH greater
by analysis of a small sample of crude tetraethyl
lead is'calculated to weigh one part, is collected
in 100 parts of water. The puri?ed tetraethyl
lead is then decanted from the water layer. Ap
proximately 0.6 part of sodium sul?de is added
to the aqueous phase producing a solution of about
0.6% sodium sul?de. The mixture is agitated for
15 minutes and ?ltered.
A small portion of the wet ?lter cake is tested
‘for ignition activity by heating for 24 hours on the
steam bath (95°-l00° C.) and is found to be in
active. No signs of ignition or charring of the
It has been found desirable to employ a rela
tively large volume of solution with a concentra
tion of less than 5%, and only in cases where the
allowable Volume is limited is the use of con
centrations above 5% necessary.
In treating the sludge, ?lter aid, or other ac
formed which settle out, or in some cases collect
tive material with the sodium sul?de or other de
on the surface of the alkyl lead compounds and
there when exposed to air, because of the cata 10 activating substance, the effect of the deactivate
ing agent is not impaired by drying the treated
lytic effect of the inorganic materials incorpo
material, and even with repeated washing with
rated therein tend to ignite, offering serious ?re
water, solvents, or with the tetraethyl lead the
and explosion hazards. By maintaining an
activity of the sludge or ?lter aid is not restored
aqueous solution of one of the aforementioned
to an appreciable extent.
deactivating agents as a layer over the crude
The following examples are given to illustrate
tetraalkyl lead any sludge which precipitates at
the invention. The parts used are by weight.
the surface is deactivated on contact with the
aqueous layer and the sludge is rendered inac
EXAMPLE 1
tive to air oxidation. By employing deactivating
agents of the types mentioned, which are soluble
Approximately 1000 parts of tetraethyl lead are
in the tetraethyl lead, any sludge which precipi
processed in a washer to precipitate the sludge
tates while in storage is immediately rendered
forming impurities by the method more particu
safe from the ignition hazard.
larly described in the co-pending application, Se
than '7) to prevent their conversion to hydrogen
sul?de which as such is ineifective in the deac
tivating of such sludges. These compounds are
therefore preferably employed as the alkali metal
salts. The organic sulfur compounds may be used
under either acidic or alkaline conditions. The
water soluble mercaptans may be employed as
aqueous solution while those which are water in
soluble may be dissolved in suitable solvents such
as benzene or alcohol and employed as such in the
deactivation of the sludge or other active mate
rial in which the tetraalkyl lead compounds are
adsorbed, or they may be used as suspensions in
?lter paper are noted even after 48 hours on the
steam bath. At the end of the 48 hours heating,
the sludge is saturated with tetraethyl lead and
40
water.
the test repeated. After 24 hours further heat
Because sodium sul?de is inexpensive and read
ing, the test is again repeated, making a total
ily available its use in the deactivation of sludges
of 72 hours testing time. No decomposition is
and residues in the‘manufacture of tetraalkyl
noted at the end of these tests.
leads is preferred. An aqueous solution contain
When a sample of the same sludge which is
ing an amount of sodium sul?de equivalent to ap
" taken before the sodium sul?de is added to the
proximately 33% of the dry weight of material
Water layer is tested for activity as outlined above,
to be stabilized has been'found to give very satis
ignition occurs shortly after the initial sample is
factory results. The amount of sodium sul?de,
placed on the steam bath.
however, may be varied over a wide range with
In plant operation it may not always be con
equally good results. For example, ei?cient sta
venient to run a laboratory analysis in order to
bilization can be effected with sodium sul?de
determine the amount of sludge that will be pres
ranging in amounts from 0.05% to 100% of the
ent, and such a procedure is not necessary. The
dry weight of the material to be treated. While
quantity of sludge formed per 1000 parts of tetra
some stabilization effect may be obtained by even
ethyl lead seldom exceeds 2 parts and this ?gure
smaller quantities the reduction in the ignition "a may be used as a basis for the calculation of the
hazard with smaller quantities is not sufficient
quantity of sodium sul?de required. Therefore
for ordinary operating conditions. The use of
if 0.6 part (30% of the dry sludge weight) of
larger quantities in general is needless and only
sodium sul?de is added to the water layer per
adds to the cost of carrying out the process and
, 1000 parts of tetraethyl lead, su?icient deactiva
does not materially contribute to increased safety
tion is insured to meet any conditions which may
in the disposal of the sludges and residues en
be experienced. It is of course understood that
countered in the manufacture and storage of the
tetraethyl lead manufactured in various plants
tetraalkyl lead compounds. The sodium sul?de
may vary in sludge forming material, but in any
is preferably employed in aqueous solutions of ap
one plant the quantity is relatively constant so
proximately 1% strength although aqueous solu
that a de?nite amount of sodium sul?de per unit
tions of 0.1% concentrations may be employed,
weight of tetraethyl lead can be employed after
the particular concentrations depending more
determining what quantity will be adequate in all
particularly upon the volume of the apparatus in
which the sludges are to be treated. Concentra
tions of less than 0.1% in the Wash solutions are
cases. As stated, the use of an amount of sodium
the loss of the sul?de as a result of the oxidation
sul?de equal to about 1/3 of the expected dry
weight of the sludge being deactivated is, in gen—
eral, satisfactory. This ?gure allows consider
by the oxygen dissolved from the atmosphere in
the solution. In washing the adsorbed materials
able latitude in operation, and We have found its
use to be very successful in all stabilization op
in general not commercially practical because of
it is of course desirable that a sufficient quantity
,erations.
2,407,261
5
6
As previously stated, we have found that other
alkali sul?des, polysul?des and sulphydrates are
eifective deactivators, and they may be substituted
for the sodium sul?de in this example.
tetramercapto copper phthalocyanine; and alkyl
mercaptans such as methyl mercaptan, amylmer
captan, octylmercaptan, and octadecylmercaptan.
The following compounds which not not contain
5 a sulfhydryl group as such, but which form this
EXAMPLE 2
group by tautomerization have also been found
Approximately 10,000 parts of crude tetraethyl
lead are placed in a suitable container provided
with means for agitating its contents. About
to be effective deactivators: guanyl thiourea,
thioacetanilide, thiosemicarbazide, thiocarbazide,
thiobiuret, thicaceto acetic acid ester, and thio
1,000 parts of water are added, and the sludge is 10 phenyl methyl pyrazolone.
precipitated and collected in the Water layer by
As in the case of the alkali metal sul?des, the
the process more particularly disclosed in 00concentration of the deactivators listed above as
pending application Serial No. 393,680.
examples of the types of compounds that may be
After the precipitation is complete, 10 parts of
employed, may be varied over wide ranges without
sodium polysul?de (Nazsis) are added and the 15 sacri?cing effectiveness. In the same manner as
contents of the container are agitated for about
with the sul?des, quantities of these compounds
15 minutes. The tetraethyl lead and the aqueous
equivalent to 0.05-l00% of the active sludge will
layer are then ?ltered together, and the clear
be found sufficient to insure good results. It is
tetraethyl lead is then decanted from the water
also to be noted that the quantity of stabilizing
layer. A sample of the sludge retained on the 20 agent required to deactivate the sludges originat
?lter when tested for ignition activity as preing'in the production of tetraalkyl lead does not
viously described is found to be inactive.
need to be suflicient to completely satisfy the ca
Organic compounds containing the sulfhydryl
pacity of the sludge to combine with the reagent
group may be applied from water as solutions if.
in order to obtain satisfactory reduction of igni
they are soluble therein, or as dispersions if in- 25 tion hazard,
soluble, or they may be employed with suitable
Wherever sludges or precipitates may settle out
organic solvents. Where water is used as the
in the lines, tanks and other processing equip
solvent or dispersing medium, the method of EXmerit during the manufacture of tetraethyl lead,
ample 1 is effective in applying the deactivator
it is desirable that these sludges and precipitates
to the precipitated tetraalkyl lead sludges. How- 30 be periodically deactivated to insure safety in the
ever, When some solvent other than water is em-
operation. This is accomplished by pumping an
ployed, the aqueous layer containing the sludge
may ?rst be ?ltered, and the ?lter cake then agi-
aqueous solution of the deactivator, such as 1%
solutions of sodium sul?de through the various
tated with the solution containing the deactivat~
pieces of equipment in a, manner that allows a
ing agent for 15 to 30 minutes, or the solvent so- 35 contact between the solution and the sludge for
lution may be added directly to the aqueous
from 15 to 30 minutes.
sludge suspension. It is not necessary to dissolve
A further use of the invention is to stabilize ac
the stabilizing reagent in a solvent or the aqueous
tive ?lter aids which are to be used in tetraalkyl
phase before it is applied for we have found that
lead ?ltration and which tend to catalyze decom
dispersions or suspensions of the deactivators are 40 positions of tetraethyl lead. These materials may
equally effective. Results obtained with various
be washed in a solution of sodium sul?de, or of
representative materials containing a sulfhydryl
one of the other deactivators and rendered inac
group (~—-SH) are given in Table I below.
tive as decomposition catalysts, and therefore
Ten parts of active sludge are shaken with 50
more suitable for use in tetraalkyl lead manufac
parts of each of the indicated solutions.
45 ture.
Table I
O0ncen_
tration.
Compound
percent
Steam bath stability
Solvent
Initial
After 24 hours
After 72 hours
Thioglycolic acid ____________________________ _.
Seleuoglycolic acid
.
5
5
Thio~uroa__
Thiosorbito
5
5
D0.
Do.
5
Do.
Thiophenol._
_
Mercapto thiazoline _________________ I.
.i
5
No decomposition." No decomposition.
C1
D0.
Do.
Potassium dibutyl dithio carbamate ________ __
1
Do.
Ammonium sulfhydrate _____________________ _.
2
D0.
Sodium
0.
sulfhydrate . _ . _ _ _
_ _ _ g _ ..
Do.
Calcium sulihydrate
1.
Do.
Potassium sulfhydrat _
1.
Do.
1.
Do.
Sodium selenide_ _ _____
No
deactivator
(control)
_ . _ _ . . _ . _ .
_ _ _ _ . . _ _ __
In addition to the above speci?c examples the
Two types of ?lter aids as well as a number of
following compounds which contain a sulfhydryl
other materials of similar structure which offer
group have been found to be effective deactiva 65 a large surface area were saturated with tetra
tors: thioamides such as thiocyanuric acid, di
ethyl lead and placed on a steam bath as de
methyl ammonium dithiocarbamate, and sodium
scribed in Example 1 above. All were found to
phenyl dithiocarbamate; thio acids such as thio
accelerate the ignition of the tetraethyl lead con
acetic acid, thiobenzoic acid, thiosalicylic acid
tained
therein. Ten parts of each of these ma
and 2-merapto-3-naphthoic acid; substituted cy
terials
were
then agitated for several hours with
clic mercaptans such as thiocresol, Xylyl mercap
50 parts of solution of sodium sul?de of the corn
tan, alpha- and beta-thionaphthol, pinene mer
centrations given below in Table II. After the
captans, terpene mercaptans, benzyl mercaptan,
agitation period, the suspensions were ?ltered
cyclohexylmercaptan, dithiohydroquinone, di
thioresorcinol, Z-mercapto-benzothiazole and 75 and portions of the ?lter cakes were wet with
7
8
tetraethyl lead and. placed on a steam bath. Re
suits of the tests are given below:
reacted with lead sodium alloy. All examples in
which tetraethyl lead is speci?ed are operable
with these mixed. lead alkyls.
Table II
Material
EXAMPLE 4
Wash solution
Filter aid (clay) _____________ __
Do _ _ _ _ _ _ _ _ _ . _
_ _ _ _ __
No
Ignited.
_ _ _ _
Do ______________________ __
Ferric oxide (anh.)____
_.
methyl triethyl lead and tetraethyl lead) are
10 placed in a suitable tank or washer, and 2000
No decomposition.
Ignited.
Do _______________________ __
Do _______________________ __
decomposition.
Ignited.
No decomposition.
Yellow lead oxide (N. F. VI) .
Bismuth oxide (prepared. by
hydrolysis of Bi(NO3)3).
methyl~ethyl lead compounds (tetramethyl lead,
trimethyl ethyl lead, dimethyl diethyl lead.
Ignited.
Filter aid (silica) _.
____ __
Do ______________________ __
Bismuth subnitrate.
Approximately 8000 parts of crude mixed tetra
Steam bath test
.
No decomposition.
Ignited.
parts of water containing ten parts of thiogly
colic acid are added. The contents of the tank
are aerated and agitated for two hOllI-s as dis
closed in the co-pending application, Serial No.
N0 decomposition. 15 393,680. After a settling period of a few minutes.
Ignited.
the clear solution of mixed lead alkyls is decant
No decomposition.
Ignited.
ed from the aqueous layer and the aqueous mix
No decomposition.
Ignited.
No decomposition.
ture is filtered. A portion of the ?lter cake is
given the steam bath stability test as described
20 in Example 1 except that the ?lter cake (sludge)
is wet with mixed lead. alkyl compounds rather
A further important use of the invention is
than with tetraethyl lead. No decomposition or
found
fore it in
is the
desludged.
storage of
Ancrude
aqueous
tetraalkyl
solutionlead
of one
ignition of the lead alkyls is noted. A similar ex
periment carried out in which no thioglycolic
of the deactivators may be used to cover the crude
tetraalkyl lead so that any sludge which sepa 25 acid is placed in the water layer. gives a sludge
which ignites the mixed alkyls when the steam
rates out and collects at the surface is deactivat
bath stability test is made.
ed by contact with the aqueous layer. If desired.
In testing the activity of the sludges before or
all of the precipitated sludge may be brought into
after treatment with the deactivating agents it
the aqueous layer by suitable agitation since the
will be noted that teraethyl or other alkyl lead
stabilized sludge particles readily disperse in the
was added to the residues. ‘This was to make
water layer. In this way the sludge may be ef
sure there was sufficient tetraalkyl lead present
fectively deactivated as soon as it is formed.
to ignite under the conditions employed, if the
The sludge formed in crude tetraethyl lead on
sludge was not fully inactivated, for in some in
standing may also be deactivated without the use
of the aqueous layer by the use of those deacti» 35 stances, it is possible that the amount of alkyl
lead may be reduced to such. a small amount
vating agents mentioned which are soluble in
that ignition might not be noted. While the
tetraethyl lead so that any sludge that precipi
tates during storage is immediately rendered safe
by the deactivator.
elimination of the alkyl lead from the residues
to such an extent does not ordinarily take place,
An aqueous solution of the deactivating agent 40 the tests were made under conditions favoring
ignition provided the sludge or ?lter aid was ac~
may also be used to cover the tetraalkyl lead dur
tive.
ing the accelerated sludge precipitation treatment
The sulfur compounds employed in the deac
previously referred to and more particularly de
tivation of the sludges, do not destroy or alter
scribed in coy-pending application Serial No.
393,680. The stabilizing agent may conveniently 45 the properties of the alkyl lead itself, nor do they
appear to decrease the property of the sludge to
be added to the water layer after the treatment‘
adsorb the alkyl lead. It is therefore difiicult to
is complete for, as we have already disclosed, in
general, more deactivating agent is required when
the agent is added before the desludging opera.
tion.
However, adding the stabilizer before the '
desludging operation does offer the advantage
that stabilization is effected as the sludge is
formed and no additional time is required.
EXAMPLE 3
Approximately 30,060 parts of crude tetraethyl
lead are placed in a suitable tank or washer, and
an approximately equal weight of water is added
to the tetraethyl lead. About 300 parts of thio
phenol are then added to the Water layer and the
sludge is precipitated and removed from the
tetraethyl lead by the method disclosed in the
co-pending application, Serial No. 393,680. After
explain the theory of how these catalytic ma
terials are rendered inactive.
This invention makes possible the deactiva
tion of the ignitable sludges and residues occur
ring in the manufacture of tetraalkyl lead com
pounds and is of particular value in eliminating
?re and explosion hazards involved in the re
moval and disposal of such sludges from the
process and in overcoming the potential ?re haz
ard arising from the collection of such sludges
and precipitates which accumulate in various
places in the processing equipment and which
‘when exposed to air often ignite with consider
able damage. The invention also permits the use
of ?lter aids which unless rendered inactive tend
to cause ignition of any absorbed tetraethyl lead
when they are exposed to the air. Any other ab
sorbent materials which for any reason may be
this operation is complete, the tetraethyl lead is
removed by decantation, and the aqueous layer
come saturated with tetraethyl lead in or about
containing the sludge is ?ltered. A portion of
the plant in which it is being manufactured may
the ?lter cake when saturated with tetraethyl
be rendered inactive by washing or otherwise
lead and tested for ignition as described in EX
treating with stabilizers of the type described so
ample l is inactive.
As previously stated, sludges found in tetra 70 that potential ?re hazards may be removed as
far as possible. Lagging on pipe which due to
ethyl lead are also found in other lead alkyls
leaks may become saturated, with tetraethyl lead
which are manufactured from commercial lead.
An example of these alkyls are the mixed tetra
and which have been known to cause its ignition
methyl-ethyl compounds of lead, formed when a
can be inactivated by treating such lagging with
mixture of methyl chloride and ethyl chloride are 75 the deactivating agents.
2,407,261
a
We claim:
1. The process of inhibiting spontaneous igni
tion of tetraalkyl lead compounds adsorbed on
id
prises placing a layer or an aqueous solution of
a compound of the class consisting of alkali metal
and ammonium monosul?des, polysul?des and
sludges which are precipitated from crude steam
suit-hydrates on the surface of a body of crude
distilled tetraalkyl lead compounds and which
sludges normally tend to cause spontaneous ig
nition of the tetraalkyl lead compounds adsorbed
ing of alkali metal and ammonium monosul?des,
steam distilled tetraethyl lead containing sludge
forming materials, causing the formation and
separation of the sludge from the tetraethyl lead
to the aqueous layer, and removing the sludge
carrying aqueous layer from the tetraethyl lead.
7. The process for separating and deactivating
sludges from crude steam distilled tetraethyl lead
polysul?des and sulfhydrates.
and which sludges normally tend to cause spon
thereon upon exposure to oxygen, which com
prises incorporating with such sludges an aque
ous solution of a compound of the class consist
2. The process of inhibiting spontaneous igni
tion of tetraethyl lead adsorbed on sludges Which
are precipitated from crude steam distilled tetra
ethyl lead and which sludges normally tend to
cause spontaneous ignition of the tetraethyl lead
adsorbed thereon upon exposure to oxygen, which
comprises incorporating with such sludges an
aqueous solution of a compound of the class con
sisting of alkali metal and ammonium mono
sul?des, polysul?des and sulihydrates.
3. The process of inhibiting spontaneous igni
tion of tetraethyl lead adsorbed on sludges which
are precipitated from crude steam distilled tetra
taneous ignition of tetraethyl lead adsorbed
thereon upon exposure to oxygen, which com
prises placing a layer or" an aqueous solution of
an alkali metal sul?de on the surface of a body
of crude steam distilled tetraethyl lead contain
ing sludge-forming materials, causing the forma
tion and separation of the sludge from the tetra
20 ethyl lead to the aqueous layer, and removing the
sludge-carrying aqueous layer from the tetraethyl
lead.
8. The process for separating and deactivating
sludges from crude steam distilled tetraethyl lead
and which sludges normally tend to cause spon
taneous ignition of tetraethyl lead adsorbed
thereon upon exposure to oxygen, which com
prises placing a layer or" an aqueous solution of
sodium sul?de on the surface of a body of crude
ethyl lead and which sludges normally tend to
cause spontaneous ignition of the tetraethyl lead
adsorbed thereon upon exposure to oxygen, which
comprises washing suchsludges with an aqueous
solution of a compound of the class consisting of 39 steam distilled tetraethyl lead containing sludge
forming materials, causing the formation and
alkali metal and ammonium monosul?des, poly—
separation of the sludge from the tetraethyl lead
sul?des and sulihydrates.
4. The process of inhibiting spontaneous igni
to the aqueous layer, and removing the sludge
carrying aqueous layer from the tetraethyl lead.
tion of tetraethyl lead adsorbed on sludges which
9. The process for separating and deactivating
are precipitated from crude steam distilled tetra
sludges from crude steam distilled tetraethyl lead
ethyl lead and which sludges normally tend to
and which sludges normally tend to cause spon
cause spontaneous ignition of the tetraethyl lead
taneous ignition of tetraethyl lead adsorbed
adsorbed thereon upon exposure to oxygen, which
comprises washing such sludges with an aqueous
thereon upon exposure to oxygen, which com
solution of an alkali metal sul?de.
prises placing a layer of an aqueous solution of a
5. The process of inhibiting spontaneous igni
tion of tetraethyl lead adsorbed on sludges which
compound of the class consisting of alkali metal
and ammonium monosul?des, polysul?des and
are precipitated from crude steam distilled tetra
sulfhydrates on the surface of a body of crude
ethyl lead and which sludges normally tend to
cause spontaneous ignition oi the tetraethyl lead
steam distilled tetraethyl lead containing sludge
iorming materials, storing the tetraethyl lead
adsorbed thereon upon exposure to oxygen, which
comprises washing such sludges with an aqueous
solution of sodium sul?de.
6. The process for separating and deactivating
sludges from crude steam distilled tetraethyl lead
and which sludges normally tend to cause spon
with the layer of aqueous solution during the
formation and separation of the sludge from the
tetraethyl lead to the aqueous layer, and remov
ing the sludge-carrying aqueous layer from the
tetraethyl lead.
taneous ignition of tetraethyl lead adsorbed
thereon upon exposure to oxygen, which com
FREDERICK B. DOW‘NING.
ADRIAN L. LINCH.
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