US1898688A

US1898688A - Purification of battery acid

Info

Publication number: US1898688A
Authority: US
Inventors: Clarence C Rose
Original assignee: Willard Storage Battery Co
Current assignee: Willard Storage Battery Co
Priority date: 1931-09-16
Filing date: 1931-09-16
Publication date: 1933-02-21
Anticipated expiration: 1950-02-21

Description

Feb. 21, 1933.' c c ROSE 1,898,688

PURIFICATION OF BATTERY ACID Filed Sept. 16, 1951 STEAM ACT VA TED CA R80 N i FILTRATE ,Erz verz for" f m MMT7 Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE CLARENCE G. ROSE, OF CLEVELAND, OHIO, ASSIGNOR TO WILLARD STORAGE BATTERY COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF WEST VIRGINIA PURIFICATION OF BATTERY ACID Application filed September 16, 1931.

This invention relates to the purification of battery acid. It has to do primarily with the treatment of sulphuric acid employed in batteries during the original charging of the batteries, or the forming of the plates thereof. The electrolyte thus used is generally of lower specific gravity than that normally employed in a fully charged battery. Hence, after it has performed its function, it is dumped from the battery and new acid of higher specific gravity is introduced in its place.

If wood separators are employed in the battery, this dumped acid is contaminated more or less by wood acids, principally acetic acid, present to a small degree in the wood separators. Such impure acid cannot be economically used a second time for the reason that the wood acids therein subject the positive plates of the battery to scaling and grid corrosion. This action is very noticeable when acid containing more than .01% wood acid is used for the initial formation of a battery. The amount of wood acids which the dumped electrolyte is likely to contain will depend upon the thoroughness with which the wood separators have been treated before they are used. In almost every case, however, the wood acid content of this electrolyte is found to be more than .01% and is genqe rally in the neighborhood of .03% or .04 0. dumped electrolyte a second time without dis astrons results.

Prior to the present invention, the only method known for removing these wood acids from the battery acid involved boiling the impure acid down to a high acid concentration and then aerating it with compressed air, which is an expensive and troublesome process. After considerable experimentation, I have discovered that the removal of the wood acids may be effected directly, that V is, without boiling down, by the simple ex- Hence it is impossible to use such Serial No. 563,036.

means which I prefer to employ is that illustrated more or less diagrammatically in the accompanying drawing, the single figure of which is an elevational view of the apparatus,

with some parts broken away to more clearly illustrate the invention.

In the drawing, 10 represents a relatively long tubular container of acid resisting material, into the bottom of which opens a pipe 11 for the admission of the impure acid, a valve 12 being employed for shutting off and controlling the rate of flow of the acid, it being understood that the acid is to be fed through the apparatus under pressure engendered by a pump or gravity resulting from the elevation of the acid tank with respect to the apparatus in question. A second pipe 13 also makes connection with the lower end of container 10, this pipe having a shut-oil valve 14, and being employed for carrying off the impurities absorbed by the carbon.

Just above the bottom of the container 10 there is mounted a grid 15 upon which is supported a small quantity of coke 16 that is employed for holding the finer activated carbon .17. enclosed by the tubular container. The

height and diameter of the container 10 are dependent upon the rate of fiow of the acid therethrough, it being necessary to maintain the acid in contact with the carbon for a given length of time.

Near the upper end of container 10 I mount a second grid 18 to prevent the carbon from being carried oil with the outgoing acid. Just above this grid there is a draw-off pipe 19 in which is mounted a valve 20. At the top of the container 10 there is a connection to a steam pipe 21.

- lVhen the process is to be started, the Valve 14 is closed and the

valves

12 and 20 are opened, the valve 12 being opened partway only, if desired, so as to control the rate of flow of the acid into the container 10. The coke 16, in addition to supporting the finer carbon 17, acts as a filter to remove any solid material which may have gotten into the battery acid. The latter then flows gradually upward through the activated carbon 17 and the wood acid is absorbed thereby, the filtrate which passes off through the grid 18 and pipe 19 being pure, or substantially pure, sulphuric acid capable of being used again in the formation of new batteries. In fact the acid may be used indefinitely when it is purified by my method after each forming operation.

When the activated carbon has become saturated or so much so that the discharge is no longer of satisfactory purity, the percolation is stopped by the closing of valve 12. Valve 14 is then opened and the acid in the container permitted to drain ofi'. Then the valve 20 is closed and steam is introduced through pipe 21 and forced through the activated carbon and out through waste pipe 13. The carbon is thereby heated and the acid previously absorbed is driven off as a vapor, it being carried out through the waste pipe with the exhaust steam. When this cleaning operation has been continued a suliicient length of time, determined by test, the steam is turned off, the valve 14 closed, and the

valves

12 and 20 opened for the resumption of the acid purifying process.

In the foregoing description, I have necessarily gone somewhat into detail in order to explain fully the particular embodiments of the invention herein illustrated, but I desire it to be understood that such detail disclosure is not to be construed as amounting to a limitation, except as it may be included in the appended claims.

Having thus described my invention, I claim:

1. The method of separating wood acid impurities from sulphuric acid, which consists in bringing the impure acid into contact with activated carbon.

2. The method of separating acetic acid impurities from sulphuric acid, which consists in bringing the impure acid into contact with activated carbon.

3. The method of reclaiming sulphuric acid from battery acid adulterated with wood acids, which consists in bringing the impure acid into contact with activated carbon, and maintaining the contact a sufiicient length of time for the removal of the wood acids by the carbon.

at. The method of removing wood acid impurities from sulphuric acid, which consists in passing the impure acid through activated carbon.

5. The method of removing wood acid impurities from sulphuric acid employed in bat-- tery formation, which consists in passing the impure acid upwardly through a column'of activated carbon.

6. The method of removing wood acid impurities from sulphuric acid employed in battery formation, which consists in passing the impure acid upwardly through a column of granular activated carbon.

7. The method of removing wood acid impurities from sulphuric acid employed in battery formation, which consists in bringing signature.

CLARENCE C. ROSE.