# US 5,879,830 A · Process for regenerating sodium sulphide from the sodium sulphate which forms in treating lead paste from exhausted batteries

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- Number: US 5,879,830 A
- Document ID: US5879830A
- Status: Granted
- Kind: A
- Application number: 08/985,041
- Filed: 1997-12-04
- Granted: 1999-03-09
- Earliest claimed: 1996-12-04
- Assignees: Ecochem Aktiengesellschaft
- Inventors: Marco Olper; Massimo Maccagni; Silvano Cossali
- Web page: https://patentgrep.com/patent/US5879830A

## CPC

- H01M 10/54: Reclaiming serviceable parts of waste accumulators
- C01B 17/22: Alkali metal sulfides or polysulfides
- C01F 11/46: Sulfates (dehydration of gypsum {for the production of calcium sulfate cements} C04B11/02)
- H01M 10/12: Construction or manufacture
- Y02E 60/10: Energy storage using batteries
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- Y02W 30/84: Recycling of batteries or fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

A process is disclosed for treating lead paste from exhausted batteries. Calcium sulfite and calcium thiosulfite are formed by the reaction: 3Ca(OH).sub.2 +4S.degree..fwdarw.2CaS+CaS.sub.2 O.sub.3 +3H.sub.2 O(1). The CaS and CaS.sub.2 O.sub.3 is reacted with sodium sulfate to effect the double exchange reaction: 2CaS+CaS.sub.2 O.sub.3 +3Na.sub.2 SO.sub.4 .fwdarw.2Na.sub.2 S+Na.sub.2 S.sub.2 O.sub.3 +3CaSO.sub.4 (2). The sodium sulfide and sodium thiosulfate is then reacted with the lead paste for converting the various lead paste components (PbSO.sub.4, PbO and PbO.sub.2) into PbS with the concomitant production of sodium sulfate. The sodium sulfate can be recycled to reaction (2).

## Claims

### Claim 1

A process for treating lead paste from exhausted batteries, comprising the steps of:
(a) reacting elemental sulfur with an aqueous lime suspension in accordance with the reaction:
3Ca(OH).sub.2 +4S.degree..fwdarw.2CaS+CaS.sub.2 O.sub.3 +3H.sub.2 O(1)
to form calcium sulphide and calcium thiosulphate;
(b) reacting the calcium salts formed in step (a) with sodium sulphate in accordance with the reaction:
2CaS+CaS.sub.2 O.sub.3 +3Na.sub.2 SO.sub.4 .fwdarw.2Na.sub.2 S.sub.2 +Na.sub.2 S.sub.2 O.sub.3 +3CaSO.sub.4 ( 2)
(c) separating the calcium sulphate formed in step (b), by filtration, to obtain a solution containing sodium sulphide and thiosulphate which is suitable for treating said lead paste; and
(d) suspending said lead paste in water, and reacting the sodium sulphide and thiosulphate solution obtained in step (b) with said lead paste suspended in water, to produce PbS and Na.sub.2 SO.sub.4, in accordance with the reactions
PbSO.sub.4 +Na.sub.2 S.sub.2 O.sub.3 +H.sub.2 O.fwdarw.PbS+Na.sub.2 SO.sub.4 +2H.sub.2 SO.sub.4 ( 3)
PbO+Na.sub.2 S.sub.2 O.sub.3 .fwdarw.PbS+Na.sub.2 SO.sub.4 ( 4)
4PbO.sub.2 +5Na.sub.2 S.sub.2 O.sub.3 +H.sub.2 O.fwdarw.4PbS+5Na.sub.2 SO.sub.4 +H.sub.2 SO.sub.4 ( 5).

### Claim 2 (depends on 1)

The process as claimed in claim 1, further comprising:
recycling said Na.sub.2 SO.sub.4 produced in step (d) to step (b) for reaction with said calcium salts.

### Claim 3 (depends on 1)

The process as claimed in claim 1, further comprising:
leaching said PbS produced in step (d) with ferric fluoroborate to form elemental sulfur, and recycling this elemental sulfur to step (a).