Патент USA US2407261код для вставки
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.