Title of Invention	"A PROCESS FOR RECOVERY OF LEAD BY DIRECT HIGH TEMPERATURE ELECTROLYTIC REDUCTION OF OXIDE-SULPHATE SLUDGE FROM SPENT LEAD ACID BATTERIES"
Abstract	The present invention relates to a process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries.The utility of the invention is the direct recovery of lead from the oxide-sulphate sludge in spent lead acid batteries. It is a single stage high temperature electrolytic reduction process, which does not require to convert insoluble lead sulphate and lead oxides into leachable products used for recovery of lead by other electrolytic process. The electrolyte used for the recovery of lead can be reused. The reclaimed lead can be used for lead acid battery application.

Title of Invention

"A PROCESS FOR RECOVERY OF LEAD BY DIRECT HIGH TEMPERATURE ELECTROLYTIC REDUCTION OF OXIDE-SULPHATE SLUDGE FROM SPENT LEAD ACID BATTERIES"

Abstract

Full Text	The present invention relates to a process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries. The utility of the invention is the direct recovery of lead from the oxide-sulphate sludge in spent lead acid batteries. It is a single stage high temperature electrolytic reduction process, which does not require to convert insoluble lead sulphate and lead oxides into leachable products used for recovery of lead by other electrolytic process. Moreover the electrolyte used for the recovery of lead can be reused. The reclaimed lead can be used for lead acid battery application. Reference may be made to following methods for recovering of lead, 1. E.R. Cole, Jr. A.Y. Lee and D.L. Paulson, "update on recovery of lead from spent batteries", J. Metals, Feb. 1985, 79. 2. E.R. Cole, Jr. A.Y. Lee and D.L. Paulson, "Recovery of lead from battery sludge by electrowinning", J. Metals, Apr. 1983, 42-43. 3. M. Maja, N. Penazzi, P. Spinelli, M.V. Ginatta, O. Ginatta and Orsello, "The electrolytic recovery of lead from spent storage batteries". Electrochemical Engineering, The Institution of Chemical Engineers, Pregamon Press, 1986. 4. Marco olper, "A fuel electrochemical approach in processing junk batteries", Proc. of 11th Intl. Lead Conf. Venice, Italy, May 25-27, 1993 organised by Lead Development Association, London. 5. Suma lyengar, "Fluoborate technology for lead extraction", Minerals and Metals Revi, June, 1999, 105. 6. Prem Chand, R. Kumar, "Various technologies for lead, zinc recycling, "Minerals and Metals Review, Oct. 1999, 75-82. 7. Z. Vaysgant, A. Morachevsky, A. Demidov, E. Klebanov, "A low temperature technique for recycling LAB scrap without wastes and with improved environmental control", J. Power Sources, 53 (1995) 303-306. ^ 8. Gust anodiaz and David Andrews, "Placid- A clean process for recycling lead from spent batteries", J. Metals, 1996, Jan, 29. 9. Z. Vaysgant, A. Moracherisky, A. Demidov, E. Klebanov, "A low temperature technique for recycling lead/acid battery scrap without wastes and with improved environmental control", J. Power Sources, 53 (1995) 303-306. Reference may be made to various technologies as given above which are available for the recovery of lead from spent lead acid batteries by Hydro and Electrolytic processes where in all these processes the sludge from the spent lead acid batteries such as lead sulphate and lead oxide are converted into teachable lead carbonate or hydroxide. The products obtained are leached by electrolyte such as fluosilicic acid/ fluoboric acid/HCI brine solution, which is followed by electrowinning with an insoluble anode. In the ELTA lead recycling process , the crushed oxide-sulphate mixture is desulphurised to remove the sulphate ions and to convert all of the lead to the oxide or hydroxide form. The lead is extracted using hydrometallurgical process. Thus, these processes involve several steps for the recovery of lead. The main object of the present invention is to provide a process for recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries" which obviates the drawbacks as detailed above. Accordingly the present invention provides a process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries which comprises an electrolytic cell consisting of a mild steel crucible containing melt of alkali hydroxide such as herein described as cathode and the cell is kept inside a tubular furnace with temperature controller to maintain the bath temperature at 450°C to 500 °C with anode being a mild steel tube introduced from the top from an electrode holding stand and is centrally positioned into the melt containing the oxide-sulphate sludge material from the plates, fed into the melt little by little till its concentration in the melt is 10 to 15% and direct current is impressed through the electrodes at the current densities ranging from 0.2 to 0.6 A/cm2, removing lead and subsequently purifying in commercial grade calcium chloride bath at 850°C to remove impurities alkali metal such as sodium, potassium, iron and calcium with a tubular suction arrangement placed over the set up for removing any fumes if evolved during melting and electrolysis. In an embodiment of the present invention the alkali hydroxide used may be selected from KOH, NaOH. In another embodiment of the present invention the preferred bath temperature may be at 450 °C. The process comprises of an electrolytic cell made of a mild steel crucible of 13 cm diameter and 20 cm height. This crucible acts as the cathode. The electrolyte used is sodium hydroxide melt. The crucible with the melt is kept inside a tubular furnace with temperature controller to maintain the bath temperature at 450°C. The anode is a mild steel tube of 4.5 cm diameter and is introduced from the top of an electrode holding stand and is positioned centrally in the melt. The oxide-sulphate sludge material from the plate is fed into the melt little by little till its concentration is raised to 10 to 15%. Direct current is impressed through the electrodes at particular current density. Lead forms a pool at the bottom of the cathode which can be removed by means of ladle. The pool of lead obtained is further refined in commercial grade CaCI2 bath at 850°C to remove the impurities such as sodium, iron and calcium. A tubular suction arrangement can also be placed over the set up for removing any fumes if evolved during melting and electrolysis. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. Raw materials obtained from spent Lead calcium alloy grids used in Lead acid battery. Example 1 Raw-material : Material from negative plate Weight of raw material : 1.4 kg Electrolyte : Commercial grade sodium hydroxide Weight of electrolyte : 5.25 kg Anode current density : 0.6 A/cm2 Power consumption : 19kWh Yield : 80% Composition of Pb recovered after : Na - Nil Ca - 0.029% treatment in CaCI2 bath at 850 °C Fe - 0.009% Pb - remaining Example 2 Raw-material : Material from positive plate Weight of raw material : 0.8 kg Electrolyte : Commercial grade sodium hydroxide Weight of electrolyte : 5.5 kg Anode current density : 0.26 A/cm2 Power consumption : 26 kWh Yield : 80% Composition of Pb recovered after : Ca - 0.073% Fe-0.001% treatment in CaCI2 bath at 850 °C Sb - 0.049% Na - 0.007% Pb - remaining Raw materials obtained from Pb-Sb-Cd grids used in lead acid batteries. Example 3 Raw-material : Material from negative plate Weight of raw material : 1 kg Electrolyte : Commercial grade sodium hydroxide Weight of electrolyte : 3.5 kg Anode current density : 0.6 A/cm2 Power consumption : 18kWh Yield : 75% Composition of Pb recovered after : Ca - 0.06% Fe - Nil treatment in CaCI2 bath at 850 °C Na - Nil Sb-Nil Cd - 0.006% Pb - remaining Example 4 Raw-material : Material from positive plate Weight of raw material : 1.65 kg Electrolyte : Commercial grade sodium hydroxide Weight of electrolyte : 4 kg Anode current density : 0.6 A/cm2 Power consumption : 30 kWh Yield : 81% Composition of Pb recovered after : Ca - 0.0408% Fe - Nil treatment in CaCI2 bath at 850 °C Na - 0.0099% Cd-0.0137% Sb-0.0031% Pb - remaining From the above examples the novelty and inventive step of the present invention is the possible direct recovery of lead from spent lead acid batteries sludge without undergoing any intermediate step. The product obtained can further be purified in commercial grade Calcium Chloride bath to get a refined alloy. The main advantages of the present invention are: a. Recycled lead can be used in lead acid battery application. b. Recycled lead can be refined to get lead-calcium alloy used in valve regulated lead acid battery. c. Environmentally clean process characterized by low level of emissions and minimum process residues. d. Maximum recycling with minimum energy. e. Low economic cost when scaled up for continuous production as it involves simple cell set-up with commercially available chemicals. We claim: 1. A process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries which comprises an electrolytic cell consisting of a mild steel crucible containing melt of alkali hydroxide such as herein described as cathode and the cell is kept inside a tubular furnace with temperature controller to maintain the bath temperature at 450°C to 500 °C with anode being a mild steel tube introduced from the top from an electrode holding stand and is centrally positioned into the melt containing the oxide-sulphate sludge material from the plates, fed into the melt little by little till its concentration in the melt is 10 to 15% and direct current is impressed through the electrodes at the current densities ranging from 0.2 to 0.6 A/cm2 , removing lead and subsequently purifying in commercial grade calcium chloride bath at 850°C to remove impurities alkali metal such as sodium, potassium, iron and calcium with a tubular suction arrangement placed over the set up for removing any fumes if evolved during melting and electrolysis. 2. A process as claimed in claim 1 wherein the alkali hydroxide used is selected from KOH, NaOH preferably sodium hydroxide. 3. A process as claimed in claims 1 - 2 wherein the preferred temperature of bath is 450 ° C. 4. A process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries substantially as herein described with reference to the examples.

Full Text

The present invention relates to a process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries.
The utility of the invention is the direct recovery of lead from the oxide-sulphate sludge in spent lead acid batteries. It is a single stage high temperature electrolytic reduction process, which does not require to convert insoluble lead sulphate and lead oxides into leachable products used for recovery of lead by other electrolytic process. Moreover the electrolyte used for the recovery of lead can be reused. The reclaimed lead can be used for lead acid battery application. Reference may be made to following methods for recovering of lead,
1. E.R. Cole, Jr. A.Y. Lee and D.L. Paulson, "update on recovery of lead from
spent batteries", J. Metals, Feb. 1985, 79.
2. E.R. Cole, Jr. A.Y. Lee and D.L. Paulson, "Recovery of lead from battery
sludge by electrowinning", J. Metals, Apr. 1983, 42-43.
3. M. Maja, N. Penazzi, P. Spinelli, M.V. Ginatta, O. Ginatta and Orsello, "The
electrolytic recovery of lead from spent storage batteries". Electrochemical
Engineering, The Institution of Chemical Engineers, Pregamon Press, 1986.
4. Marco olper, "A fuel electrochemical approach in processing junk batteries",
Proc. of 11th Intl. Lead Conf. Venice, Italy, May 25-27, 1993 organised by
Lead Development Association, London.
5. Suma lyengar, "Fluoborate technology for lead extraction", Minerals and
Metals Revi, June, 1999, 105.
6. Prem Chand, R. Kumar, "Various technologies for lead, zinc recycling,
"Minerals and Metals Review, Oct. 1999, 75-82.
7. Z. Vaysgant, A. Morachevsky, A. Demidov, E. Klebanov, "A low temperature
technique for recycling LAB scrap without wastes and with improved
environmental control", J. Power Sources, 53 (1995) 303-306.
^
8. Gust anodiaz and David Andrews, "Placid- A clean process for recycling lead
from spent batteries", J. Metals, 1996, Jan, 29.
9. Z. Vaysgant, A. Moracherisky, A. Demidov, E. Klebanov, "A low temperature
technique for recycling lead/acid battery scrap without wastes and with
improved environmental control", J. Power Sources, 53 (1995) 303-306.
Reference may be made to various technologies as given above which are available for the recovery of lead from spent lead acid batteries by Hydro and Electrolytic processes where in all these processes the sludge from the spent lead acid batteries such as lead sulphate and lead oxide are converted into teachable lead carbonate or hydroxide. The products obtained are leached by electrolyte such as fluosilicic acid/ fluoboric acid/HCI brine solution, which is followed by electrowinning with an insoluble anode. In the ELTA lead recycling process , the crushed oxide-sulphate mixture is desulphurised to remove the sulphate ions and to convert all of the lead to the oxide or hydroxide form. The lead is extracted using hydrometallurgical process. Thus, these processes involve several steps for the recovery of lead.
The main object of the present invention is to provide a process for recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries" which obviates the drawbacks as detailed above.
Accordingly the present invention provides a process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid
batteries which comprises an electrolytic cell consisting of a mild steel crucible
containing melt of alkali hydroxide such as herein described as cathode and the cell is kept inside a tubular furnace with temperature controller to maintain the bath temperature at 450°C to 500 °C with anode being a mild steel tube introduced from the top from an electrode holding stand and is centrally positioned into the melt containing the oxide-sulphate sludge material from the plates, fed into the melt little by little till its concentration in the melt is 10 to 15% and direct current is impressed through the electrodes at the current densities ranging from 0.2 to 0.6 A/cm2, removing lead and subsequently purifying in commercial grade calcium chloride bath at 850°C to remove impurities alkali metal such as sodium, potassium, iron and calcium with a tubular suction arrangement placed over the set up for removing any fumes if evolved during melting and electrolysis.
In an embodiment of the present invention the alkali hydroxide used may be selected from KOH, NaOH.
In another embodiment of the present invention the preferred bath temperature may be at 450 °C.
The process comprises of an electrolytic cell made of a mild steel crucible of 13 cm diameter and 20 cm height. This crucible acts as the cathode. The electrolyte used is sodium hydroxide melt. The crucible with the melt is kept inside a tubular furnace with temperature controller to maintain the bath temperature at 450°C. The anode is a mild steel tube of 4.5 cm diameter and is introduced from the top of an electrode holding stand and is positioned centrally in the melt. The oxide-sulphate sludge material from the plate is fed into the melt little by little till its concentration is raised to 10 to 15%. Direct current is impressed through the electrodes at particular current density. Lead forms a pool at the bottom of the cathode which can be removed by means of ladle. The pool of lead obtained is further refined in commercial grade CaCI2 bath at 850°C to remove the impurities such as sodium, iron and calcium. A tubular suction arrangement
can also be placed over the set up for removing any fumes if evolved during melting and
electrolysis.
The following examples are given by way of illustration and therefore should not be
construed to limit the scope of the present invention.
Raw materials obtained from spent Lead calcium alloy grids used in Lead acid
battery.
Example 1
Raw-material : Material from negative plate
Weight of raw material : 1.4 kg
Electrolyte : Commercial grade sodium hydroxide
Weight of electrolyte : 5.25 kg
Anode current density : 0.6 A/cm2
Power consumption : 19kWh
Yield : 80%
Composition of Pb recovered after : Na - Nil
Ca - 0.029%
treatment in CaCI2 bath at 850 °C Fe - 0.009%
Pb - remaining
Example 2
Raw-material : Material from positive plate
Weight of raw material : 0.8 kg
Electrolyte : Commercial grade sodium hydroxide
Weight of electrolyte : 5.5 kg
Anode current density : 0.26 A/cm2
Power consumption : 26 kWh
Yield : 80%
Composition of Pb recovered after : Ca - 0.073%
Fe-0.001%
treatment in CaCI2 bath at 850 °C Sb - 0.049%
Na - 0.007%
Pb - remaining
Raw materials obtained from Pb-Sb-Cd grids used in lead acid batteries.
Example 3
Raw-material : Material from negative plate
Weight of raw material : 1 kg
Electrolyte : Commercial grade sodium hydroxide
Weight of electrolyte : 3.5 kg
Anode current density : 0.6 A/cm2
Power consumption : 18kWh
Yield : 75%
Composition of Pb recovered after : Ca - 0.06%
Fe - Nil
treatment in CaCI2 bath at 850 °C Na - Nil
Sb-Nil
Cd - 0.006%
Pb - remaining
Example 4
Raw-material : Material from positive plate
Weight of raw material : 1.65 kg
Electrolyte : Commercial grade sodium hydroxide
Weight of electrolyte : 4 kg
Anode current density : 0.6 A/cm2
Power consumption : 30 kWh
Yield : 81%
Composition of Pb recovered after : Ca - 0.0408%
Fe - Nil
treatment in CaCI2 bath at 850 °C Na - 0.0099%
Cd-0.0137% Sb-0.0031% Pb - remaining
From the above examples the novelty and inventive step of the present invention is the possible direct recovery of lead from spent lead acid batteries sludge without undergoing any intermediate step. The product obtained can further be purified in commercial grade Calcium Chloride bath to get a refined alloy.
The main advantages of the present invention are:
a. Recycled lead can be used in lead acid battery application.
b. Recycled lead can be refined to get lead-calcium alloy used in valve
regulated lead acid battery.
c. Environmentally clean process characterized by low level of emissions and
minimum process residues.
d. Maximum recycling with minimum energy.
e. Low economic cost when scaled up for continuous production as it involves
simple cell set-up with commercially available chemicals.

We claim:
1. A process of recovery of lead by direct high temperature electrolytic reduction
of oxide-sulphate sludge from spent lead acid batteries which comprises an
electrolytic cell consisting of a mild steel crucible containing melt of alkali
hydroxide such as herein described as cathode and the cell is kept inside a
tubular furnace with temperature controller to maintain the bath temperature
at 450°C to 500 °C with anode being a mild steel tube introduced from the
top from an electrode holding stand and is centrally positioned into the melt
containing the oxide-sulphate sludge material from the plates, fed into the
melt little by little till its concentration in the melt is 10 to 15% and direct
current is impressed through the electrodes at the current densities ranging
from 0.2 to 0.6 A/cm2 , removing lead and subsequently purifying in
commercial grade calcium chloride bath at 850°C to remove impurities alkali
metal such as sodium, potassium, iron and calcium with a tubular suction
arrangement placed over the set up for removing any fumes if evolved during
melting and electrolysis.
2. A process as claimed in claim 1 wherein the alkali hydroxide used is selected
from KOH, NaOH preferably sodium hydroxide.
3. A process as claimed in claims 1 - 2 wherein the preferred temperature of
bath is 450 ° C.
4. A process of recovery of lead by direct high temperature electrolytic reduction of oxide-sulphate sludge from spent lead acid batteries substantially as herein described with reference to the examples.

Documents:

531-del-2001-abstract.pdf

531-del-2001-claims..pdf

531-del-2001-correspondence-others.pdf

531-del-2001-correspondence-po.pdf

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

531-del-2001-form-1.pdf

531-del-2001-form-18.pdf

531-del-2001-form-3.pdf

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Patent Number

220126

Indian Patent Application Number

531/DEL/2001

PG Journal Number

28/2008

Publication Date

11-Jul-2008

Grant Date

15-May-2008

Date of Filing

26-Apr-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	SHRI. KASIVISWANATHAN NAMBIAH
2	ER. PALAINIAPPAN SANKAR
3	ER. MARIASUSAI DEVASAHAYAM
4	DR. MOHAMED KAMALUDEEN
5	ER. SOMASUNDARAM AMBALAVANAN
6	ER. POOCHI MURUGESAN
7	ER AROCKIAM VISUVASAM
8	DR. MEENAKSHISUNDARAM RAGHAVAN

PCT International Classification Number

C22 B 13/06

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA