US1592935A

US1592935A - Process of recovering tin

Info

Publication number: US1592935A
Authority: US
Inventors: Elmo G Hickey
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-04-28
Filing date: 1925-04-28
Publication date: 1926-07-20
Anticipated expiration: 1943-07-20

Description

Patented July 20, 1926. i I

ELMO G. HICKEY, OF LOS ANGELES, CALIFORNIA.

PROCESS OF RECOVERING TIN.

Io Drawing.

This invention relates to process for recovering tin from tin cans, scrap tin and other tin surfaces.

For approximately the past fifty years various processes for the removal of tin from tin bearing scrap, tin cans and the like, have been known and used. These processes have, for the most part, been based upon the fact that tin is soluble in either hot or cold solutions of caustic alkali in the presence of alkali metal nitrates. These processes have, for the most part, a number of difiiculties, one of which difficulties has been in thedevelopment of this recovery process from the standpoint of com-.

mercial success because of the relatively long time required for this action to take place and the consequent excessive high cost in plant expense, handling charges of any considerable quantity of material to be detinned, such as tin scrap, refuse, tin cans, and the like.

An object of this invention is to provide a process by which the tin may be recovered from tin scrap, refuse, tin cans, and the like, in a relatively short time, maintaining a high efliciency of the recovery of the tin.

I have discovered that the recovery of tin is greatly accelerated by ,the addition of ammonia to the alkaline solution composed of caustic soda and alkaline nitrates. According to the preferred form of the invention, the tin scrap, tin cans, and the like, properly cleaned and perforated, is sub-- jected to the action of a solution of caustic soda and sodium nitrate to which from .3% to 3% by weight of ammonium hydroxide has been added; the ammonium hydroxide used being approximately 28% NH The solution is heated approximately to boiling. This solution is from 4 to 12% sodium nitrate and from 18 to 28% sodium hydroxide, although it is to be understood that other alkali-metal hydroxides might be employed Application filed April as, 1925. Serial No. 26,524.

and that nitrates other than sodium nitrate mlght be employed in this process with equal elficiency, sodium nitrate and sodium hy- "covered that the tin will be completely removed from the tin scrap within approximately an hour, where heretofore it has required from 6 to 7 hours to obtain the same tin recovery.

Having fully described the preferred embodiment of this invention, it is to be under,- stood that this invention relates tovthe use of ammonia as a catalytic agent for accelerating the rate of recovery of tin from tin scrap and that the same is in no way dependent upon the percentages of sodium hydroxides and sodium nitrate employed other than that the same should be of suflicient strength to remove the tin from the tin bearing scrap and precipitate the same, preferably as sodium stannate.

I claim:

1. A process of recovering tin from tin scraps which comprises subjecting the tin scraps to the action of caustic alkali and alkali metal nitrate in the presence of ammonia.

2. A process of recovering tin from tin scraps comprising subjecting tin scrap to the action of caustic alkali and alkali "metal nitrate in the presence of from .3 to 3% of ammonia hydroxide containing 28% ammonia by weight. V 3. In a process of recovering tin from tin scraps, employing caustic alkali solution, the step which includes the use of ammonia as an energizing agent.

Signed at Los Angeles, California, this 23d day of April 1925.

ELMO G. HICKEY.