Electrolysis: processes – compositions used therein – and methods – Electrolytic synthesis – Preparing single metal
Patent
1995-01-26
1996-11-19
Niebling, John
Electrolysis: processes, compositions used therein, and methods
Electrolytic synthesis
Preparing single metal
205583, 205589, 205604, 205607, 205540, 241 23, 241 2411, 241 2412, 75401, 75403, 75743, 423100, C22B 700
Patent
active
055759076
DESCRIPTION:
BRIEF SUMMARY
This invention concerns a process for recovering raw materials from presorted collected waste materials, especially from scrap electrochemical batteries and accumulators.
We can no longer imagine daily life without electrochemical batteries as a practical and highly mobile source of energy, because there has been a steady increase in the use of portable electronic equipment. Along with the increase in use of such portable electronic equipment, there has also been an increase in the consumption of batteries, so there are growing numbers of old spent batteries that must be disposed of or sent for recycling.
The most commonly used batteries are zinc-carbon and alkali-manganese batteries. In addition, rechargeable nickel-cadmium batteries are also being used to an increasing extent. Furthermore, mercury button batteries are also used in cases where especially compact energy sources are needed, such as in watches and photographic equipment.
In addition to valuable materials such as nickel and cadmium, these batteries also contain toxic substances such as mercury that must not be allowed to enter the environment.
In order to prevent toxic mercury from entering the garbage, the industry has been trying for some time now to reduce the amount of mercury in batteries. Although considerable progress has already been made in this regard, zinc-carbon and alkali-manganese batteries in particular still contain small amounts of mercury, but even these quantities add up to be a substantial amount in view of the large number of batteries consumed today. Thus, approximately 1.5 tons of mercury are dumped in the garbage each year from the annual battery consumption amounting to approx. 230 million zinc-carbon batteries and approx. 200 million alkali-manganese batteries each year.
In addition to this environmental safety aspect, however, it would also appear expedient not to simply dump the valuable substances contained in batteries in the garbage but to recover them, so these valuable substances can be reused in production processes in a suitable manner.
Although lead batteries such as those used in motor vehicles and the nickel-cadmium batteries that are used industrially are already being recycled almost completely, there is not yet a suitable method of recovering the raw materials present in household batteries.
At the Seventh International Technical Symposium "Battery Disposal and Battery Recycling" of the Industrial Battery Association in ZVEI in March 1991 in Munich, a recycling method for nickel-cadmium batteries based on a wet chemical process was presented. For this recycling process, first the nickel-cadmium batteries must be sorted out of the collected used batteries. Then the batteries are shredded. In a pretreatment, scrap and plastics are recovered from the shredded battery materials and washed with hydrochloric acid. The remaining battery materials are leached out, using the same hydrochloric acid solution as that used to wash the shredded battery materials and then sent to this process step. After filtering, the solution obtained from leaching is sent for wet-chemical work-up, where the nickel and cadmium are also separated by electrolysis.
A disadvantage of this known process is that only nickel-cadmium batteries can be used, which necessitates a complicated (and expensive) sorting operation for the collected batteries.
In a recycling process for Leclanch e cells (zinc-carbon and alkali-manganese batteries) that was presented at the same symposium, first the nickel-cadmium batteries are sorted out of the collected batteries. After opening and separating the steel casings, mercury is evaporated at 400.degree. C. to 600.degree. C. in a rotary drum-type kiln, while the distillation residues are sent to a cooling drum to recover the mercury. The remaining material is first crushed in order to then retrieve the iron by means of magnetic separation. There remains a mixture of zinc and manganese that cannot be reused in this form, however.
A disadvantage of this process is that the problem of recovering zinc and man
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patent: 3666185 (1972-05-01), Williams
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Chemical Abstracts, vol. 106, No. 16, Apr. 20, 1987, Aoki, et al. "Recovery of Metals from Spent Dry Batteries" p. 239, column 2, summary number 123550u.
Jpn Kokai Tokkyo Koho JP 61,261,443 (86 261 443).
Batenus Umwelt - Und Recyclingtechnologie GmbH & Co. KG
Mee Brendan
Niebling John
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