Title of Invention	"A PROCESS FOR THE ELECTROLYTIC RECOVERY OF LEAD FROM SCRAP LEAD ACID BATTERY DESULPHUPRISED SLUDGE"
Abstract	The present invention relates to a process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge. Process steps are: electrolysing the electroyte composition containing 50- 100 g/1 lead and 70-120 g/1 fluoboric / fluosilicic acid at a current density of 170-400 A/m2 employing graphite or Titanium Substrate Lead Dioxide (TSLD) as anode material and cathode material selected from stainless steel, lead or titanium with the addition of 3.0-5.0 g/1 grain refiner, 40-1000 ppm leveling agents such as herein described, 500-3000 ppm lead dioxide inhibiting agents such as soluble arsenic or phosphorous compounds, recovering the lead deposited on cathode by known method..

Title of Invention

"A PROCESS FOR THE ELECTROLYTIC RECOVERY OF LEAD FROM SCRAP LEAD ACID BATTERY DESULPHUPRISED SLUDGE"

Abstract

The present invention relates to a process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge. Process steps are: electrolysing the electroyte composition containing 50- 100 g/1 lead and 70-120 g/1 fluoboric / fluosilicic acid at a current density of 170-400 A/m2 employing graphite or Titanium Substrate Lead Dioxide (TSLD) as anode material and cathode material selected from stainless steel, lead or titanium with the addition of 3.0-5.0 g/1 grain refiner, 40-1000 ppm leveling agents such as herein described, 500-3000 ppm lead dioxide inhibiting agents such as soluble arsenic or phosphorous compounds, recovering the lead deposited on cathode by known method..

Full Text	The present invention relates to a process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge. The advantage of electrolytic route when compared to the pyrometallurgical operation is that the former avoids sulphur dioxide emission and emission of lead paniculate and also the purity of the final product is high. Pyrometallurgical process also produces slag byproduct which in certain cases can be deemed hazardous making disposal costly. Reference may be made to (John R.Ainley, 'Environmental regulations: their impact on the battery and lead industries', J.Power Source, 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.Daview 'Guidelines for lead in soil' Environ. Sci. Technol.28,1, 1994.) wherein the recovery of lead values from the paste fraction (active material) has always been an area of environmental concern. The lead compounds in the scrap battery are traditionally reduced in a reverberatory or rotary furnace. These, processes are costly due to the amount of fluxes required to add to the charge. The off gases from the process contain sulphur dioxide which makes it necessary to implement a scrubbing system to eliminate such gases. Pyrometallurgical process also produces a slag byproduct which in certain cases can be deemed hazardous, making disposal costly. The main object of the present invention is to provide a process by an electrolytic route for the recovery of lead from scrap lead acid battery desulphurised sludge which obviates the drawbacks as detailed above. Desulphurised sludge is obtained by treating the lead compounds of scrap batteries with alkali hydroxides and this is a prior operation to electrolysis. The electrolytic route is the direct deposition of lead metal from the electrolyte by passing direct electric current, without producing any hazardous emissions unlike in the case of pyrometallurgical route where emissions of sulphur dioxide and lead particulate are posing serious environmental problems when the spent batteries are smelted at very high temperatures. Another object of the present invention is to provide a cleaner and an efficient process for the extraction of lead electrolytic ally from lead containing electrolytes obtained by processing scrap batteries. Yet another object of the invention is to fix the concentration of lead and free fluoboric acid or fluosilicic acid to get maximum efficiency of lead deposition during electrolysis. Yet another object of the invention is to fix the concentration of lead and free fluoboric acid or fluosilicic acid to get maximum efficiency of lead deposition during electrolysis. Yet another object of the invention is to provide stable anode material which are anodically pretreated in phosphorus or arsenic containing electrolytes or simultaneously treated during electrolysis by adding small amounts of soluble phosphorus or arsenic compounds to the lead electro winning electrolyte in order to prevent undesirable anodic formation of PbO2. Still another object of the present invention is to use titanium sheet as cathode material for easy removal of lead deposit with improved physical characteristics. Yet another object of the present invention is the use of electrolyte additives such as animal / fish glue or gelatin as leveling agent and calcium / sodium lignin sulphonate as grain refiner in order to produce lead free from nodules, dendrites and tree growths. Accordingly the present invention provides a process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge which comprises; electrolysing the electroyte composition containing 50- 100 g/1 lead and 70-120 g/1 fluoboric / fluosilicic acid at a current density of 170-400 A/m2 employing graphite or Titanium Substrate Lead Dioxide (TSLD) as anode material and cathode material selected from stainless steel, lead or titanium with the addition of 3.0-5.0 g/1 grain refiner, 40-1000 ppm leveling agents such as herein described, 500-3000 ppm lead dioxide inhibiting agents such as soluble arsenic or phosphorous compounds, recovering the lead deposited on cathode by known method. In an embodiment of the present invention the electrolyte is lead fluoborate or lead fluosilicate solution containing 50 - 100 g /1 lead and 70 - 120 g /1 fluoboric acid or fluosilicic acid. In another embodiment of the present invention the anode material is graphite or Titanium Substrate Lead Dioxide (TSLD ) treated anodically in arsenic or phosphorus containing solution prior to electrowinning or treated simultaneously during electrowinning by adding soluble arsenic or phosphorous compounds to the electrowinning electrolyte , the arsenic or phosohorus concentration being 500 to 3000 ppm. In another embodiment of the present invention the cathode material is stainless steel or lead or titanium preferably titanium for easy removal of lead deposit from the substrate. In yet another embodiment of the present invention the cathode current density is in the range of 170-400 A/m2. In still another embodiment of the present invention the addition agents are calcium / sodium lignin sulphonate in the range of 3-5 g/1 and gelatin or animal / fish glue in the range of 40-1000 ppm to obtain lead deposit free from tree growth, dendrite, nodule etc. The electrolytic cell is a PVC container of 10 litres capacity where two graphite plates or anodically pretreated graphite plates or Titanium Substrate Lead Dioxide (TSLD) are employed as anodes and a lead sheet or stainless steel sheet or titanium sheet with a deposition area of O.lm2 are employed as cathodes. The electrolyte contains either lead fluoborate and free fluoboric acid or lead fluosilicate and free fluosilicic acid. Calcium / sodium lignin sulphonate and gelatin or fish / animal glue are added at regular intervals of time in order to produce lead deposit free from nodules and tree growth. The required amount of phosphoric acid or arsenic compound is added to the electrolyte in order to prevent undesirable anodic formation of lead dioxide, which would otherwise lead to loss of lead from electrolyte. A current density of 170-400 A/m2 is passed by a regulated DC power supply. Instead of adding soluble phosphorus or arsenic compounds to the lead electrolyte, anodes are also treated anodically in phosphorus or arsenic containing electrolyte for the inhibition of anodic formation of lead dioxide. During the electrolysis, the electrolyte is circulated and a fresh lead fluoborate/lead fluosilicate is fed to the electrolytic cell from an overhead reservoir. The electrolysis is carried out at 30°C-40°C for a fixed period of time. While lead is deposited cathodically, oxygen gas is evolved at the anode. After the electrolysis is over, the cathode is lifted and the lead deposit is stripped. From the weight of the deposit, current efficiency is determined. From the data on cell voltage and current efficiency, the energy consumption of lead produced is determined. The cathode lead is analysed for its purity level by mass spectrometry. The purity of the lead deposit is found to be 99.97-99.99%. The novelty of the present invention is the electrolytic extraction of lead from scrap batteries at room temperature without producing any hazardous emission , a serious environmental problem encountered in pyrometallurgical operations. The inventive step of the invention is the surface modification of graphite anode in presence of surface active and soluble phosphorous or arsenic compounds in the electrolyte for the complete inhibition of lead dioxide deposition at the anode ,thus preventing the loss of lead from the electrolyte. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. Example -1 (TABLE REMOVED) The main advantages of the present invention are: 1. The electrolytic process provides cleaner and an efficient method of extracting lead from lead electrolyte produced from scrap lead acid battery paste fraction. 2. Electrolytic lead of very high purity (99.99%) can be produced which is suitable for preparation of battery grade lead oxides and production of maintenance free lead acid batteries. 3. The process does not produce any emission of gases like sulphur dioxide and lead paniculate associated with pyrometallurgical operation practiced world over and hence it is eco friendly. 4. Titanium metal cathodes employed in the process facilitate easy stripping of lead deposit from the substrate. 5. Treatment of anodes in solutions containing soluble phosporus or arsenic compounds inhibit anodic formation of PbC>2 during electrolysis. Consumption of lead from the electrolyte for undesirable PbC>2 formation is prevented. 6. The electrolytic process is also applicable to other secondary sources of lead like dross, ash, slime, slag etc. 7. The electrolytic process provides flexibility in the scale of operation in contrast to the pyromeallurgical operation where the minimum capacity of the plant should be around 20,000 tons/annum to match with high cost involved in pollution control measures. But the electrolytic plants can economically be operated even for a minimum capacity of 1000 tons/annum. We Claim: 1. A process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge which comprises; electrolysing the electroyte composition containing 50- 100 g/1 lead and 70-120 g/1 fluoboric / fluosilicic acid at a current density of 170-400 A/m2 employing graphite or Titanium Substrate Lead Dioxide (TSLD) as anode material and cathode material selected from stainless steel, lead or titanium with the addition of 3.0- 5.0 g/1 grain refiner, 40-1000 ppm leveling agents such as herein described, 500-3000 ppm lead dioxide inhibiting agents such as soluble arsenic or phosphorous compounds, recovering the lead deposited on cathode by known method.. 2. A process as claimed in claim 1 wherein the electrolyte contains 70 g/1 lead. 3. A process as claimed in claim 1&2 wherein the grain refiner used is selected from sodium lignin sulphonate and calcium lignin sulphonate. 4. A process as claimed in claim 1-3 wherein the leveling agent used is selected from animal glue, fish glue and gelatin. 5. A process as claimed in claim 1-4 wherein the concentration of arsenic or phosphorus as lead dioxide inhibiting agents in the solution is 2000 ppm. 6. A process as claimed in claim 1-5 wherein the current density used is 200 A/m2. 7. A process as claimed in claim 1-6 wherein the grain refiners are added at 4 g/1 and leveling agent added at 50 ppm. 8. A process as claimed in claims 1-7 substantially as herein described with reference to the examples.

Full Text

The present invention relates to a process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge.
The advantage of electrolytic route when compared to the pyrometallurgical operation is that the former avoids sulphur dioxide emission and emission of lead paniculate and also the purity of the final product is high. Pyrometallurgical process also produces slag byproduct which in certain cases can be deemed hazardous making disposal costly.
Reference may be made to (John R.Ainley, 'Environmental regulations: their impact on the battery and lead industries', J.Power Source, 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.Daview 'Guidelines for lead
in soil' Environ. Sci. Technol.28,1, 1994.) wherein the recovery of lead values from the paste fraction (active material) has always been an area of environmental concern. The lead compounds in the scrap battery are traditionally reduced in a reverberatory or rotary furnace. These, processes are costly due to the amount of fluxes required to add to the charge. The off gases from the process contain sulphur dioxide which makes it necessary to implement a scrubbing system to eliminate such gases. Pyrometallurgical process also produces a slag byproduct which in certain cases can be deemed hazardous, making disposal costly.
The main object of the present invention is to provide a process by an electrolytic route for the recovery of lead from scrap lead acid battery desulphurised sludge which obviates the drawbacks as detailed above. Desulphurised sludge is obtained by treating the lead compounds of scrap batteries with alkali hydroxides and this is a prior operation to electrolysis. The electrolytic route is the direct deposition of lead metal from the electrolyte by passing direct
electric current, without producing any hazardous emissions unlike in the case of pyrometallurgical route where emissions of sulphur dioxide and lead particulate are posing serious environmental problems when the spent batteries are smelted at very high temperatures.
Another object of the present invention is to provide a cleaner and an efficient process for the extraction of lead electrolytic ally from lead containing electrolytes obtained by processing scrap batteries.
Yet another object of the invention is to fix the concentration of lead and free fluoboric acid or fluosilicic acid to get maximum efficiency of lead deposition during electrolysis.
Yet another object of the invention is to fix the concentration of lead and free fluoboric acid or fluosilicic acid to get maximum efficiency of lead deposition during electrolysis. Yet another object of the invention is to provide stable anode material which are anodically pretreated in phosphorus or arsenic containing electrolytes or simultaneously treated during electrolysis by adding small amounts of soluble phosphorus or arsenic compounds to the lead electro winning electrolyte in order to prevent undesirable anodic formation of PbO2.
Still another object of the present invention is to use titanium sheet as cathode material for easy removal of lead deposit with improved physical characteristics.
Yet another object of the present invention is the use of electrolyte additives such as animal / fish glue or gelatin as leveling agent and calcium / sodium lignin sulphonate as grain refiner in order to produce lead free from nodules, dendrites and tree growths.
Accordingly the present invention provides a process for the electrolytic recovery of lead from scrap lead acid battery desulphurised sludge which comprises; electrolysing the electroyte composition containing 50- 100 g/1 lead and 70-120 g/1 fluoboric / fluosilicic acid at a current density of 170-400 A/m2 employing graphite or Titanium Substrate Lead Dioxide (TSLD) as anode material and cathode material selected from stainless steel, lead or titanium with the addition of 3.0-5.0 g/1 grain refiner, 40-1000 ppm leveling agents such as herein described, 500-3000 ppm lead dioxide inhibiting agents such as soluble arsenic or phosphorous compounds, recovering the lead deposited on cathode by known method.
In an embodiment of the present invention the electrolyte is lead fluoborate or lead fluosilicate solution containing 50 - 100 g /1 lead and 70 - 120 g /1 fluoboric acid or fluosilicic acid.
In another embodiment of the present invention the anode material is graphite or Titanium Substrate Lead Dioxide (TSLD ) treated anodically in arsenic or phosphorus containing solution prior to electrowinning or treated simultaneously during electrowinning by adding soluble arsenic or phosphorous compounds to the electrowinning electrolyte , the arsenic or phosohorus concentration being 500 to 3000 ppm.
In another embodiment of the present invention the cathode material is stainless steel or lead or titanium preferably titanium for easy removal of lead deposit from the substrate.
In yet another embodiment of the present invention the cathode current density is in the range of 170-400 A/m2.
In still another embodiment of the present invention the addition agents are calcium / sodium lignin sulphonate in the range of 3-5 g/1 and gelatin or animal / fish glue in the range of 40-1000 ppm to obtain lead deposit free from tree growth, dendrite, nodule etc.
The electrolytic cell is a PVC container of 10 litres capacity where two graphite plates or anodically pretreated graphite plates or Titanium Substrate Lead Dioxide (TSLD) are employed as anodes and a lead sheet or stainless steel sheet or titanium sheet with a deposition area of O.lm2 are employed as cathodes. The electrolyte contains either lead fluoborate and free fluoboric acid or lead fluosilicate and free fluosilicic acid. Calcium / sodium lignin sulphonate and gelatin or fish / animal glue are added at regular intervals of time in order to produce lead
deposit free from nodules and tree growth. The required amount of phosphoric acid or arsenic compound is added to the electrolyte in order to prevent undesirable anodic formation of lead dioxide, which would otherwise lead to loss of lead from electrolyte. A current density of 170-400 A/m2 is passed by a regulated DC power supply. Instead of adding soluble phosphorus or arsenic compounds to the lead electrolyte, anodes are also treated anodically in phosphorus or arsenic containing electrolyte for the inhibition of anodic formation of lead dioxide.
During the electrolysis, the electrolyte is circulated and a fresh lead fluoborate/lead fluosilicate is fed to the electrolytic cell from an overhead reservoir. The electrolysis is carried out at 30°C-40°C for a fixed period of time. While lead is deposited cathodically, oxygen gas is evolved at the anode. After the electrolysis is over, the cathode is lifted and the lead deposit is stripped. From the weight of the deposit, current efficiency is determined. From the data on cell voltage and current efficiency, the energy consumption of lead produced is determined. The cathode lead is analysed for its purity level by mass spectrometry. The purity of the lead deposit is found to be 99.97-99.99%.
The novelty of the present invention is the electrolytic extraction of lead from scrap batteries at room temperature without producing any hazardous emission , a serious environmental problem encountered in pyrometallurgical operations.
The inventive step of the invention is the surface modification of graphite anode in presence of surface active and soluble phosphorous or arsenic compounds in the electrolyte for the complete inhibition of lead dioxide deposition at the anode ,thus preventing the loss of lead from the electrolyte.

The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention.
Example -1
(TABLE REMOVED) The main advantages of the present invention are:
1. The electrolytic process provides cleaner and an efficient method of extracting lead from
lead electrolyte produced from scrap lead acid battery paste fraction.
2. Electrolytic lead of very high purity (99.99%) can be produced which is suitable for
preparation of battery grade lead oxides and production of maintenance free lead acid
batteries.
3. The process does not produce any emission of gases like sulphur dioxide and lead
paniculate associated with pyrometallurgical operation practiced world over and hence it
is eco friendly.
4. Titanium metal cathodes employed in the process facilitate easy stripping of lead deposit
from the substrate.
5. Treatment of anodes in solutions containing soluble phosporus or arsenic compounds
inhibit anodic formation of PbC>2 during electrolysis. Consumption of lead from the
electrolyte for undesirable PbC>2 formation is prevented.
6. The electrolytic process is also applicable to other secondary sources of lead like dross,
ash, slime, slag etc.
7. The electrolytic process provides flexibility in the scale of operation in contrast to the
pyromeallurgical operation where the minimum capacity of the plant should be around
20,000 tons/annum to match with high cost involved in pollution control measures. But
the electrolytic plants can economically be operated even for a minimum capacity of
1000 tons/annum.

We Claim:
1. A process for the electrolytic recovery of lead from scrap lead acid battery desulphurised
sludge which comprises; electrolysing the electroyte composition containing 50- 100 g/1
lead and 70-120 g/1 fluoboric / fluosilicic acid at a current density of 170-400 A/m2
employing graphite or Titanium Substrate Lead Dioxide (TSLD) as anode material and
cathode material selected from stainless steel, lead or titanium with the addition of 3.0-
5.0 g/1 grain refiner, 40-1000 ppm leveling agents such as herein described, 500-3000
ppm lead dioxide inhibiting agents such as soluble arsenic or phosphorous compounds,
recovering the lead deposited on cathode by known method..
2. A process as claimed in claim 1 wherein the electrolyte contains 70 g/1 lead.
3. A process as claimed in claim 1&2 wherein the grain refiner used is selected from
sodium lignin sulphonate and calcium lignin sulphonate.
4. A process as claimed in claim 1-3 wherein the leveling agent used is selected from
animal glue, fish glue and gelatin.
5. A process as claimed in claim 1-4 wherein the concentration of arsenic or phosphorus as
lead dioxide inhibiting agents in the solution is 2000 ppm.
6. A process as claimed in claim 1-5 wherein the current density used is 200 A/m2.
7. A process as claimed in claim 1-6 wherein the grain refiners are added at 4 g/1 and
leveling agent added at 50 ppm.
8. A process as claimed in claims 1-7 substantially as herein described with reference to the
examples.

Documents:

1054-del-2000-abstract.pdf

1054-del-2000-claims.pdf

1054-del-2000-correspondence-others.pdf

1054-del-2000-correspondence-po.pdf

1054-del-2000-description (complete).pdf

1054-del-2000-form-1.pdf

1054-del-2000-form-19.pdf

1054-del-2000-form-2.pdf

1054-del-2000-form-3.pdf

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Patent Number

232872

Indian Patent Application Number

1054/DEL/2000

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

21-Mar-2009

Date of Filing

24-Nov-2000

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	VENKATARAMAN NANDAKUMAR	CECRI, KARAIKUDI, TAMIL NADU, INDIA.
2	KUNNISSERI VENKATACHALAM VENKATESWARAN	CECRI, KARAIKUDI, TAMIL NADU, INDIA.
3	PERIAIAH RAMACHANDRAN	CECRI, KARAIKUDI, TAMIL NADU, INDIA.

PCT International Classification Number

C25C 3/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA