Title of Invention	A PROCESS FOR THE DESULPHURISATION OF SCRAP LEAD ACID BATTERY SLUDGE FOR THE RECOVERY OF LEAD
Abstract	A process for the desulphurization of scrap lead acid battery sludge for the recovery of lead The present invention relates to a process for the desulphurization of scrap lead acid battery sludge for the recovery of lead. The process uses electrolytically regenerated sodium hydroxide for the recovery of lead. The process steps are : desulphursing the spent battery sludge after treating at 300°C in a PVC container at a temperature ranging in between 30-70°C for 15 to 160 minutes using electrolytically regenerated sodium hydroxide from impure sodium sulphate solution at a current density of 1000-5000 A/m2, cooling and filtering the resultant solution to obtain the desired desulphurised sludge essentially containing lead mono oxide.

Title of Invention

A PROCESS FOR THE DESULPHURISATION OF SCRAP LEAD ACID BATTERY SLUDGE FOR THE RECOVERY OF LEAD

Abstract

A process for the desulphurization of scrap lead acid battery sludge for the recovery of lead The present invention relates to a process for the desulphurization of scrap lead acid battery sludge for the recovery of lead. The process uses electrolytically regenerated sodium hydroxide for the recovery of lead. The process steps are : desulphursing the spent battery sludge after treating at 300°C in a PVC container at a temperature ranging in between 30-70°C for 15 to 160 minutes using electrolytically regenerated sodium hydroxide from impure sodium sulphate solution at a current density of 1000-5000 A/m2, cooling and filtering the resultant solution to obtain the desired desulphurised sludge essentially containing lead mono oxide.

Full Text	The present invention relates to a process for the desulphurisation of scrap lead acid battery sludge for the recovery of lead. More particularly the p:esent invention relates to a process for the desulphurisation of scrap lead acid battery sludge using electrolytically regenerated sodium hydroxide for the recovery of lead. The scrap lead acid battery which contains both metallic fraction and lead compounds are traditionally reduced in reverberatory or rotary furnaces the reference may be made to John R.Ainley, "Environmental regulations: their impact on the battery and lead industries", J. Power sources, 53, (1995) 309-314.; Jozsef Keri and Jozef Preceko "Development and use of a new system for environmentally clean recycling of lead battery scrap", J.Power source, 53, (1995), 297-302.; G.Wixon and E.Davies "Guidelines for lead in soil", Environ. Sci. Technol. 28, 1, 1994. The spent battery sludge which comprises these lead compounds contains nearly 50-60% PbSO4, which gives rise to emission of sulphur dioxide during smelting, an area of environmental concern. Alternative hydrometallurgical routes have been reported the reference may be made to R.David Pregaman "Recovering lead from batteries", J. Metals, (1995) 31.; Michael E.Stout, "Secondary lead recovery from spent SLI batteries", EPD Congress (1993) The Mineral Metals and Material Society, (1992) 967 wherein the scrap battery sludge is desulphurised with NaOH prior to smelting or leaching cum electrowinning so that the emission of SO2 and lead participate can be prevented. The purpose of desulphurisation is to convert the lead sulphate content of the battery sludge into lead monoxide, Which can be subsequently smelted, or electro won to lead metal. A waste product accumulated in the desulphurization stage is sodium sulphate which is contaminated with lead creating disposal problems. The main object of the present invention is to provide a process for the desulphurization of scrap lead acid battery sludge using the sodium hydroxide regenerated lectroytically from waste sodium sulphate solution for the recovery of lead which obviates the drawbacks as detailed above. The novelty of this process is the electrolytic regeneration of sodium hydroxide using a divided cell from the accumulated waste sodium sulphate solution, for the desulphurization of battery sludge. Another object of the present invention is to employ suitable current density for the regeneration of sodium hydroxide from the sodium sulphate solution. Yet another object of the present invention is to use proper diaphragm material for the separation of anode and cathode in the electrolytic cell for the regeneration of NaOH. Still another object of the Opresent invention is to determine the time required for the desulphurization operation. Yet another object of the present invention is to optimize the temperature during the desulphurization process. Accordingly the present invention provides a process for the desulphurization of scrap lead acid battery sludge for the recovery of lead which comprises; a) regenerating electrolytically sodium hydroxide from impure sodium sulphate solution at a current density of 1000-5000 A/m2 , treating the spent battery sludge at 300°C , c) desulphursing the said spent battery sludge as obtained in step b) with sodium hydroxide obtained in step a) in a PVC container at a temperature ranging in between 30-70°C for 15 to 160 minutes, d) cooling and filtering the resultant solution to obtain the desired desulphurised sludge essentially containing lead mono oxide. In an embodiment of the present invention the temperature of desulphurization is preferably in the range of 40°C - 70°C. In an another embodiment of the present invention the duration of desulphurization is preferably in the range of 15 mts -60 mts, In an another embodiment of the present invention the sodium sulphate used for regenerating the sodium hydroxide is impure sodium sulphate accumulated as the waste product in the desulphurization process. In an another embodiment of the present invention the yield of lead recovered is 80-97%. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of present invention. Example -1 The electrolytic cell for regeneration of sodium hydroxide was a PVC container of 2 litre capacity where a PVC separator was employed for dividing the cell into cathode and anode compartments. Nickel and lead sheets of area 36 cm2 each were employed as cathode and anode respectively. Sodium sulphate of 100 g/1 was used as electrolyte. A current density of 1 OOOA/m2 was employed. Sodium hydroxide was regenerated in the cathode compartment. The electrolysis was carried out till the required quantity of NaOH is regenerated. 10 gm of spent battery sludge after treatment at 300° C , was subjected to desulphurisation in a PVC container of 1 litre capacity using stoichiometric amount of NaOH regenerated electrolytically. The temperature was maintained at 60°C and after certain interval of time the solution was cooled and filtered. The desulphurised sludge essentially contains lead monoxide (PbO) which was dried and analyzed for the PbO content. The recovery of lead was calculated from the amount of PbO in the desulphurised sludge. The various parameters involved in the above process is summarized below. a] Regeneration of sodium hydroxide i) Electrolyte : sodium sulphate : ii) Cathode current density : iii) Diaphragm material : iv) Duration : v) Sodium hydroxide regenerated : vi) Current efficiency : b) Desulphurisation i) Weight of sludge : ii) Concentration of NaOH : iii) Temperature : iv) Duration : v) PbO content : vi) Recovery of lead : 100g/l 1000A/m2 PVC material of 30% porosity 55 minutes 4.0 gms 88% 10g 1.0 M 60°C 30 minutes 6.6 g 95% Example -2 The procedure is similar to example 1 except the parameters as summarized below: a) Regeneration of sodium hydroxide i) Electrolyte : sodium sulphate ii) Cathode current density iii) Diaphragm material iv) Duration v) Sodium hydroxide regenerated vi) Current efficiency b) Desulphurisation i) Weight of sludge ii) Concentration of NaOH iii) Temperature iv) Duration v) PbO Content vi) Recovery of lead 150g/l 2000 A/m2 PVC material of 50 % porosity 25 minutes 4.1 g 97% 10gms 1.5 M 40°C 15 minutes. 6.6 g 93% Example -3 The procedure is similar to example 1 except the parameters as summarized below: a) Regeneration of sodium hydroxide i) Electrolyte : sodium sulphate 200 g/l ii) Cathode current density iii) Diaphragm material iv) Duration v) Sodium hydroxide regenerated vi) Current efficiency b) Desulphurisation i) Weight of sludge ii) Concentration of NaOH iii) Temperature iv) Duration v) PbO content vi) Recovery of lead 3000 A/m2 PVC material of 40% porosity 30 minutes 6.5 g 89% 10gms 2.0 M 70°C 45 minutes 6.4 g 92% Example -4 a) Regeneration of sodium hydroxide i) Electrolyte : sodium sulphate ii) Cathode current density iii) Diaphragm material iv) Duration v) Sodium hydroxide regenerated vi) Current efficiency b) Desulphurisation i) Weight of sludge ii) Concentration of NaOH iii) Temperature 100g/l 4000 A/m2 PVC material of 30% porosity 10 minutes 2.7 g 81% 10gms 1.0 M 60°C iv) Duration : 60 minutes, v) PbO content : 6.6 g vi) Recovery of lead : 95% The main advantages of the present invention are: 1. The emissions of SO2 and lead particulate which is common in the pyrometallurgical operation are completely eliminated. 2. The desulphurized sludge can be starting material for both low temperature smelting and electrolytic route for the recovery of lead metal. 3. The waste sodium sulphate accumulated in the desulphurisation process which would other wise create environmental problems is usefully recycled to generate the sodium hydroxide required for the desulphurisation process. 1. A process for the desulphurization of scrap lead acid battery sludge for the recovery of lead which comprises; a) regenerating electrolytically sodium hydroxide from impure sodium sulphate solution at a current density of 1000- 5000 A/m2 , treating the spent battery sludge at 300°C , c) desulphursing the said spent battery sludge as obtained in step b) with sodium hydroxide obtained in step a) in a PVC container at a temperature ranging in between 30-70°C for 15 to 160 minutes, d) cooling and filtering the resultant solution to obtain the desired desulphurised sludge essentially containing lead mono oxide. 2. A process as claimed in claim 1 wherein the temperature to desulphurization is preferably in the range of 40°C - 70°C. 3. A process as claimed 1 & 2 wherein the duration of desulphurization is preferably in the range of 15 -60 minutes. 4. A process as claimed in claims 1- 3 wherein the sodium sulphate used for regenerating the sodium hydroxide is impure sodium sulphate accumulated as the waste product in the desulphurization process. 5. A process claimed in claims 1- 4 wherein the yield of lead recovered is 80-97%. 6. A process for the desulphurization of scrap lead acid battery sludge for the recovery of lead substantially as herein described with reference to the examples.

Full Text

The present invention relates to a process for the desulphurisation of scrap lead acid battery sludge for the recovery of lead.
More particularly the p:esent invention relates to a process for the desulphurisation of scrap lead acid battery sludge using electrolytically regenerated sodium hydroxide for the recovery of lead.
The scrap lead acid battery which contains both metallic fraction and lead compounds are traditionally reduced in reverberatory or rotary furnaces the reference may be made to John R.Ainley, "Environmental regulations: their impact on the battery and lead industries", J. Power sources, 53, (1995) 309-314.; Jozsef Keri and Jozef Preceko "Development and use of a new system for environmentally clean recycling of lead battery scrap", J.Power source, 53, (1995), 297-302.; G.Wixon and E.Davies "Guidelines for lead in soil", Environ. Sci. Technol. 28, 1, 1994.
The spent battery sludge which comprises these lead compounds contains nearly 50-60% PbSO4, which gives rise to emission of sulphur dioxide during smelting, an area of environmental concern.
Alternative hydrometallurgical routes have been reported the reference may be made to R.David Pregaman "Recovering lead from batteries", J. Metals, (1995) 31.; Michael E.Stout, "Secondary lead recovery from spent SLI batteries", EPD Congress (1993) The Mineral Metals and Material Society, (1992) 967 wherein the scrap battery sludge is desulphurised with NaOH prior to smelting or leaching cum electrowinning so that the emission of SO2 and lead participate can be prevented. The purpose of desulphurisation is to convert the lead sulphate content of the battery sludge into lead monoxide,

Which can be subsequently smelted, or electro won to lead metal. A waste product accumulated in the desulphurization stage is sodium sulphate which is contaminated with lead creating disposal problems.
The main object of the present invention is to provide a process for the desulphurization of scrap lead acid battery sludge using the sodium hydroxide regenerated lectroytically from waste sodium sulphate solution for the recovery of lead which obviates the drawbacks as detailed above.
The novelty of this process is the electrolytic regeneration of sodium hydroxide using a divided cell from the accumulated waste sodium sulphate solution, for the desulphurization of battery sludge.
Another object of the present invention is to employ suitable current density for the regeneration of sodium hydroxide from the sodium sulphate solution.
Yet another object of the present invention is to use proper diaphragm material for the separation of anode and cathode in the electrolytic cell for the regeneration of NaOH.
Still another object of the Opresent invention is to determine the time required for the desulphurization operation.
Yet another object of the present invention is to optimize the temperature during the desulphurization process.
Accordingly the present invention provides a
process for the desulphurization of scrap lead acid battery sludge for the recovery of lead which comprises; a) regenerating electrolytically sodium hydroxide from impure sodium sulphate solution at a current density of 1000-5000 A/m2 , treating the spent battery sludge at 300°C , c) desulphursing the said spent battery sludge as obtained in step b) with sodium hydroxide obtained in step a) in a PVC container at a temperature

ranging in between 30-70°C for 15 to 160 minutes, d) cooling and filtering the resultant solution to obtain the desired desulphurised sludge essentially containing lead mono oxide.
In an embodiment of the present invention the temperature of desulphurization is preferably in the range of 40°C - 70°C.
In an another embodiment of the present invention the duration of desulphurization is preferably in the range of 15 mts -60 mts,
In an another embodiment of the present invention the sodium sulphate used for regenerating the sodium hydroxide is impure sodium sulphate accumulated as the waste product in the desulphurization process.
In an another embodiment of the present invention the yield of lead recovered is 80-97%.
The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of present invention.
Example -1
The electrolytic cell for regeneration of sodium hydroxide was a PVC container of 2 litre capacity where a PVC separator was employed for dividing the cell into cathode and anode compartments. Nickel and lead sheets of area 36 cm2 each were employed as cathode and anode respectively. Sodium sulphate of 100 g/1 was used as electrolyte. A current density of 1 OOOA/m2 was employed. Sodium hydroxide was regenerated in the cathode compartment. The electrolysis was carried out till the required quantity of NaOH is regenerated.

10 gm of spent battery sludge after treatment at 300° C , was subjected to desulphurisation in a PVC container of 1 litre capacity using stoichiometric amount of NaOH regenerated electrolytically. The temperature was maintained at 60°C and after certain interval of time the solution was cooled and filtered. The desulphurised sludge essentially contains lead monoxide (PbO) which was dried and analyzed for the PbO content. The recovery of lead was calculated from the amount of PbO in the desulphurised sludge.
The various parameters involved in the above process is summarized below.

a] Regeneration of sodium hydroxide
i) Electrolyte : sodium sulphate :
ii) Cathode current density :
iii) Diaphragm material :
iv) Duration :
v) Sodium hydroxide regenerated :
vi) Current efficiency :
b) Desulphurisation
i) Weight of sludge :
ii) Concentration of NaOH :
iii) Temperature :
iv) Duration :
v) PbO content :
vi) Recovery of lead :

100g/l
1000A/m2
PVC material of 30% porosity
55 minutes
4.0 gms
88%
10g
1.0 M
60°C
30 minutes
6.6 g
95%

Example -2
The procedure is similar to example 1 except the parameters as summarized below:

a) Regeneration of sodium hydroxide
i) Electrolyte : sodium sulphate
ii) Cathode current density
iii) Diaphragm material
iv) Duration
v) Sodium hydroxide regenerated
vi) Current efficiency
b) Desulphurisation
i) Weight of sludge
ii) Concentration of NaOH
iii) Temperature
iv) Duration
v) PbO Content
vi) Recovery of lead

150g/l
2000 A/m2
PVC material of 50 % porosity
25 minutes
4.1 g
97%
10gms
1.5 M
40°C
15 minutes.
6.6 g
93%

Example -3
The procedure is similar to example 1 except the parameters as summarized below:

a) Regeneration of sodium hydroxide i) Electrolyte : sodium sulphate

200 g/l

ii) Cathode current density
iii) Diaphragm material
iv) Duration
v) Sodium hydroxide regenerated
vi) Current efficiency
b) Desulphurisation
i) Weight of sludge
ii) Concentration of NaOH
iii) Temperature
iv) Duration
v) PbO content
vi) Recovery of lead

3000 A/m2
PVC material of 40% porosity
30 minutes
6.5 g
89%
10gms
2.0 M
70°C
45 minutes
6.4 g
92%

Example -4
a) Regeneration of sodium hydroxide
i) Electrolyte : sodium sulphate
ii) Cathode current density
iii) Diaphragm material
iv) Duration
v) Sodium hydroxide regenerated
vi) Current efficiency
b) Desulphurisation
i) Weight of sludge
ii) Concentration of NaOH
iii) Temperature

100g/l
4000 A/m2
PVC material of 30% porosity
10 minutes
2.7 g
81%
10gms 1.0 M 60°C

iv) Duration : 60 minutes,
v) PbO content : 6.6 g
vi) Recovery of lead : 95%
The main advantages of the present invention are:
1. The emissions of SO2 and lead particulate which is common in the
pyrometallurgical operation are completely eliminated.
2. The desulphurized sludge can be starting material for both low
temperature smelting and electrolytic route for the recovery of lead
metal.
3. The waste sodium sulphate accumulated in the desulphurisation
process which would other wise create environmental problems is
usefully recycled to generate the sodium hydroxide required for the
desulphurisation process.

1. A process for the desulphurization of scrap lead acid battery sludge for the
recovery of lead which comprises; a) regenerating electrolytically sodium
hydroxide from impure sodium sulphate solution at a current density of 1000-
5000 A/m2 , treating the spent battery sludge at 300°C , c) desulphursing the said
spent battery sludge as obtained in step b) with sodium hydroxide obtained in step
a) in a PVC container at a temperature ranging in between 30-70°C for 15 to 160
minutes, d) cooling and filtering the resultant solution to obtain the desired
desulphurised sludge essentially containing lead mono oxide.
2. A process as claimed in claim 1 wherein the temperature to desulphurization is
preferably in the range of 40°C - 70°C.
3. A process as claimed 1 & 2 wherein the duration of desulphurization is
preferably in the range of 15 -60 minutes.
4. A process as claimed in claims 1- 3 wherein the sodium sulphate used for
regenerating the sodium hydroxide is impure sodium sulphate accumulated as the
waste product in the desulphurization process.
5. A process claimed in claims 1- 4 wherein the yield of lead recovered is 80-97%.
6. A process for the desulphurization of scrap lead acid battery sludge for the
recovery of lead substantially as herein described with reference to the examples.

Documents:

424-del-2001-abstract.pdf

424-del-2001-claims.pdf

424-del-2001-correspondence-others.pdf

424-del-2001-correspondence-po.pdf

424-del-2001-description (complete).pdf

424-del-2001-form-1.pdf

424-del-2001-form-18.pdf

424-del-2001-form-2.pdf

424-del-2001-form-3.pdf

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Patent Number

230951

Indian Patent Application Number

424/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

30-Mar-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	PERIAIAH RAMACHANDRAN	CFCRI, KARAIKUDI
2	VENKATARAMAN NANDKUMAR	CFCRI, KARAIKUDI
3	KUNNISSERI VENKATACHALAM VENKATESWARAN	CFCRI, KARAIKUDI

PCT International Classification Number

C22C 13/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA