Patented No. 20, 1945 2,389,465 UNITED STATES PATENT OFFICE

PLATES AND METHOD OF PRE PARNG SAME Alexander Stewart, Mountain Lakes, N. J., and Adrian R. Pitrot, Hempstead, N. Y., assignors tocorporation National Leadof New Company, Jersey New York, N. Y., a No Drawing. Application September 25, 1941, Serial No. 412,284 Claims. (Cl. 136-26) This invention relates to storage batteries of which products have been formerly used in the the lead-acid type and has for its object an im negative plates of storage batteries. provement in the capacity of such batteries. On the other hand, the waste SOda liquors re Specifically, this invention relates to a new sulting from the manufacture of pulp by the so “expander' material recovered from waste liquors 5 called soda or kraft processes, namely, "black of the sulfate or soda processes for pulping wood liquors,' are the raw products used in carrying which when incorporated in the active material out our invention. In the Soda process, chips of of the negative plate of the lead-acid storage wood are treated with a solution of Sodium hy battery, will result in a battery of improved ca drate. The kraft process differs from the SOda pacity especially at low temperatures and at high O discharge rates. process chiefly in the fact that sodium, sulfide is used in addition to sodium hydrate in the di The prior art has shown that when a small gesting liquor. The pulping of the chips in both percentage of a certain class of substances, gen processes is performed in closed steel tanks or erally classified as humins, humic acids, ulmins, digestors under steam pressure. When the wood ulmic acids, lignins or ligneous materials and de is properly digested, the charge is emptied into rived from vegetable matter either in the unde Wash tanks where the cellulose fiber is washed composed state as in woods, corncobs, straw, and free from the liquor solution or the so-called the like, or in a partially decomposed state as in "black liquor.' This black liquor is concentrat muck, peat, lignites, compost, tanbark, and the ed in evaporators, the residue from which comes like,preparing are added negative to the storage oxide compositionbattery plates, used the in 20 out as a black semi-solid material called “black resultant capacity of the battery, especially at ash.' Either the black liquor or the black ash high rates of discharge, is markedly improved. may be used as the raw material for the prepa Such vegetable matter as has been used for the ration of our improved storage battery expander. source of the expander material has been ex 25 As will be understood by those skilled in the art, tracted for the active fraction by numerous the alkalinity of this black liquor or black ash means. The prior art has shown a progressive is so strong that it cannot be determined or ex improvement in battery performance as a re pressed in pH values. sult of improved methods in the manner of prep The composition of the black ash varies some aration of the expander material. what and is dependent upon a number of factors Thus, the prior art has disclosed that the ad which include the type of wood used, conditions dition of specially treated waste sulfite liquors ob of digesting and the like, but on the average will tained as a by-product of paper mills using this contain about 50% organic matter. process, might be used for the purpose of im In general, the preparation of the material to proving the low temperature capacity of lead 35 be used may be carried out in accordance with stdage batteries. We have now found that cer the following procedure. The black ash is dis tain chemical products may be obtained from the solved in water in a ratio of about one part solids waste liquors of the soda or kraft processes for to about four parts water, or the black ash may making pulp and that these products can also be dissolved in waste black liquor to give the be used to increase the initial capacity as well 40 same solid content, or the waste black liquor as the sustained low temperature capacity dur may be adjusted to approximate this concen ing the life of the battery. tration either by dilution or evaporation as the Sulfite liquor is distinguished from the soda, case may be. From this solution a fraction of or kraft liquors in its chemical composition. Sul the Organic matter present is precipitated by fite liquor is a waste product from paper mills 45 lowering the alkalinity of the solution. This may wherein wood chips are digested under pressure be accomplished by the addition of an acid or with a solution of calcium bisulfate. In this an acidic material, e. g. hydrochloric acid, an process the bisulfite liquor dissolves the ligneous acid salt, e. g. potassium acid sulfate, or a salt portion of the wood resulting in two fractions, giving an acid hydrolysis, e. g. ammonium sul (1) the cellulose pulp from which paper and 50 fate, until the pH of the solution is between 10.0 other products are made and (2) the waste sul to 7.0, but not below 7.0. In this manner a frac fite liquor. Organic matter may be precipitated tion of the available, Organic matter present in from the waste sulfite liquors by treatment with the liquor varying from about 30 to about 80% caustic lime to give battery expander materials of the total, is precipitated. Following this pre such as lignin or sulfonic derivatives of lignin bycipitation, heating the the material entire systemis coagulated to a temperature or collected 2,389,465 2 sistent results. The fraction precipitated from of between about 60° C. and about 100° C. The an alkaline solution in accordance with the pres precipitate is filtered and washed free of sol ent invention differs somewhat in its general uble materials by means of Water to which has properties from the fraction which remains in been added a small amount of acidic material, solution and which may be precipitated from usually that employed in the precipitation. If, 5 acid solutions. In general, the former material however, the acidic material used in the pre is insoluble in water and in dilute acids but is cipitation is of such a nature as to be "deleterious readily soluble in dilute alkalies. Being of a or injurious to the finished storage battery, then ligneous nature, its composition is incapable of a different agent may be used in Washing such exact chemical definition, and it can only be de as dilute Sulfuric acid. The Washed filter cake O scribed as being the selective product of the is dried and pulverized and is now ready for use method of preparation hereinabove set forth. as an expander material to be added to the lead To illustrate the manner of practice of our in compound for the negative plates of storage bat vention, we now offer the following example: teries. 1,600 c. c. of waste. sulfate kraft liquor solu While the exact nature of the organic mate 5 tion of 16° Bé. was diluted with 400 c. c. of water rial resulting from the above process is not to give a solution of 13 Bé. This solution was clearly understood, it is of a ligneous nature. heated to a temperature of between 85 to 90° C. Preliminary work had indicated that the organic and then 200 c. c. of Solution containing 100 material existing in the waste black liquor from grams of ammonium sulfate was added slowly, the SOda or kraft processes would be suitable as 20 approximately one hour being taken for this ad an expander. However, considerable experi dition. When the equivalent of 40 grams of am mental work and the production of many test monium sulfate had been added a precipitate batteries showed that the entire organic frac appeared. Following the addition of the amn tion gave inconsistent results. While some monium sulfate solution, the temperature of the Samples of waste black liquors were obtained entire solution was maintained at between 85 which on precipitation by an acid gave a product to 90° C. for a period of about three hours at the of desirable properties, when incorporated in a end of which time the odor of escaping ammonia, storage battery, other samples given the identical was no longer evident. A voluminous precipitate treatment, produced a product which was de had formed and at the end of this time the pH cidedly inferior. This difference in behavior 30 was 9.1. The precipitate was filtered and washed remained inexplicable over a period of time dur with dilute sulfuric acid until free from soda, ing which continued investigation was made. after which it was then washed with water until We subsequently discovered, however, that if the filtrate was neutral. The filter cake was then we precipitated in the manner above described a dried and ground and weighed 124 grams. fraction of this organic material which is present The yield of the organic matter in the present in waste black liquors, and if at no time we al example was about 62%, since the Organic mat lowed the solution to become acid, i. e., to reach ter contained in the quantity of waste Sulfate a pH lower than 7.0, the fraction obtained con liquor used was found to have been 200 grams. sistently possessed the desired properties when About 0.5 of a pound of this dried organic it was incorporated in the negative plate of a 40 product was then added to 100 lbs. of litharge storage battery. We also ascertained that by and thoroughly mixed together with 0.5 lb. of precipitating the residual material from the blanc fixe and 0.25 lb. of lamp black in a mixing filtrate by the addition of more acid, this residual machine such as is usually employed for this pur material varied considerably in its properties pose. This mixture was then made into a paste When it was incorporated in the negative plate in the usual manner by adding about 5,000 c. c. of a storage battery. At times it proved to be of water and 3,000 c. c. of sulfuric acid of a Suitable for use in a battery, but often it con specific gravity of about 1.250 and the mixing tained undesirable materials which rendered it continued until the reaction was complete. The decidedly unsuited for use in a storage battery. 50 plastic active material was then pasted into grids, While the description of our invention thus far assembled in the usual manner into a battery presented has referred to the use of waste liquors and employed as the negative plate. Of the Soda or kraft processes as a Source for It is to be understood that the percentage of obtaining our improved battery expander, it is the precipitated substance used as an organic to be understood that this has been done because expander to be incorporated with the Oxide mix of the economy involved in employing such waste 55 ture to form the improved negative plate mate liquors. Our invention has general application rial may vary between wide limits. While it has to the treatment of alkaline solutions of wood been found that from about 0.1% to about 1% and woody materials from whatever source de of the compound may be used, the preferred rived and resides in the discovery that by pre range will usually be between about 0.2% to cipitating a selective fraction only of the organic 60 about 0.75% by weight of the litharge. Further matter by lowering the alkalinity of the solution more, details of making the paste may be varied to a point not below a pH of 7.0 and preferably to suit the needs of the battery manufacturer. between about 10.0 and about 7.0 there is pre It is to be further understood that by the term vented the precipitation of the deleterious sub 65 litharge, we mean to include a litharge composed stances responsible for the inconsistent perform of lead oxide which may contain up to 55% of ance in storage batteries of expanders of the finely divided metallic lead or which may con prior art. . tain amounts of so-called lead sub-oxide. We have also determined-that apparently the The foregoing description and example of our method of altering the pH of the solution is not present invention, and the terms therein em important to obtaining the proper characteristics 70 ployed have been intended merely for illustrative of the organic material. The importance lies in . purposes and no undue limitations should be de the pH itself. If, for instance, the pH is allowed duced therefrom. It is to be understood, there to reach 3.5, decidedly on the acid side, as it does fore, that variations and changes capable of be when the entire organic material is precipitated ing accomplished by the mere exercise of skill of with a mineral acid, the product gives incon- 5

2,889,465 3 the art are to be embraced within the scope of 4. Process according to claim 1 wherein the al the appended claims. kaline containing solution is an aqueous solution We claim: of black ash derived from the manufacture of 1. A process of making an expander for stor paper. age battery plates which comprises partially neu 5. A process of making an expander for storage tralizing an alkaline lignin containing solution battery plates which comprises partially neutral derived from wood to an alkalinity within a range izing an alkaline lignin containing solution de from upwards of pH=7.0 to about pH=10 sep rived from wood to an alkalinity of about pH-9.0, arating from the Supernatant liquor the ligneous separating from the Supernatant liquor the lig substance thereby precipitated in the alkaline O neous substance thereby precipitated in the al phase and washing and drying the same. kaline phase, and washing and drying the same. 2. A process of making an expander for stor 6. Active material for storage battery plates age battery plates which comprises adding to an comprising lead Oxide having incorporated there alkaline lignin containing solution derived from with between about 0.1% and about 2.0% of a wood a neutralizing agent to reduce the alkalinity ligneous Substance obtained according to the of such solution to within a range from upwards method of claim 1. of pHs'.0 to about pH=10.0, separating from 7. A paste for negative plates of storage bat the supernatant liquor the ligneous substance teries comprising lead oxide having incorporated thereby precipitated in the alkaline phase, and therewith between about 0.1% and about 2.0% washing and drying the same. i. 20 of a ligneous substance obtained according to the 3. Process according to claim 1 wherein the al Yslethod of claim 1. kaline containing solution is waste soda liquor ALEXANDER SEWAR.T.

derived from the manufacture of paper. AORIAN R. PTROT.