Title of Invention	"A PROCESS FOR THE EXTRACTION OF NICKEL AT MACRO-LEVEL FROM A SOLUTION CONTAINING NICKEL AND SODIUM SULPHATE"
Abstract	A process was developed for the separation and recovery of nickel from a feed solution containing 34.4 kg/m3 of nickel and 20 kg/m3 of sodium sulphate. Di-(2-ethylhexyl) phosphoric acid (neutrlaised partially with alkali) was used as the extractant. It was possible to extract more than 99.5% nickel at an aqueous to organic ratio of 1:4 using 0.4 M solvent. Stripping of nickel from the loaded solvent was affected with spent electrolyte containing 57 kg/m3 nickel and 12 kg/m3 each of sodium sulphate and boric acid. A 3-stage stripping simulation with a spent electrolyte of pH 1.8 at A:O ratio of 2.2 : 1 resulted in a spent organic containing 0.014 kg/m3 of nickel corresponding to a stripping efficiency of 99.8%. Strip solution with a pH of 4.2 and enriched by about 3.9 kg/m3 of nickel is suitable for electrowinning to produce nickel cathode. 13

Title of Invention

"A PROCESS FOR THE EXTRACTION OF NICKEL AT MACRO-LEVEL FROM A SOLUTION CONTAINING NICKEL AND SODIUM SULPHATE"

Abstract

A process was developed for the separation and recovery of nickel from a feed solution containing 34.4 kg/m3 of nickel and 20 kg/m3 of sodium sulphate. Di-(2-ethylhexyl) phosphoric acid (neutrlaised partially with alkali) was used as the extractant. It was possible to extract more than 99.5% nickel at an aqueous to organic ratio of 1:4 using 0.4 M solvent. Stripping of nickel from the loaded solvent was affected with spent electrolyte containing 57 kg/m3 nickel and 12 kg/m3 each of sodium sulphate and boric acid. A 3-stage stripping simulation with a spent electrolyte of pH 1.8 at A:O ratio of 2.2 : 1 resulted in a spent organic containing 0.014 kg/m3 of nickel corresponding to a stripping efficiency of 99.8%. Strip solution with a pH of 4.2 and enriched by about 3.9 kg/m3 of nickel is suitable for electrowinning to produce nickel cathode. 13

Full Text	The present invention relates to a process for the extraction of nickel at macro-levels from solutions containing nickel and sodium sulphate using di-(2-ethylhexyl) phosphoric acid in which the nickel is extracted using a partially neutralised extractant (with alkali/ammonia) leaving with sodium sulphate in the aqueous solution. Processes are reported for the separation of cobalt and nickel from acidic sulphate solutions in which the separation of cobalt is carried out with partially neutralised organophosphoric acid based extractants, viz., di-(e-thylhexyl) phosphoric acid (D2EHPA), PC-88A and Cyanex 272 leaving the nickel values in the aqueous solutions. Ashbrook and Ritcey (A.W. Ashbrook, G.. Ritcey, Can. Pat. 795, 724, 1968) studied the extraction of cobalt from a feed solution containing 11.7-12.2 kg/m3 cobalt and 13.32-14.1 kg/m3 nickel. The cobalt recovery was about 98% when extraction was carried in the pH range 5-6.5 using an ammonia neutralised solvent of 5-40 vol.%. Cobalt stripping from the loaded organic was carried out using a mineral acid. Fugimoto et al. (A. Fugimoto, I. Muira, K. Noguchi, U.S. Patent, 4, 196, 076 (1980)) reported the separation of cobalt from nickel using 10-40% PC-88A at pH 5-6.5.. TBP and isodecanol was added to prevent emulsification. 0.5-5N inorganic acid was used to reextract cobalt salts from , the organic solvent. Rickelton et al. (W.A. Rickelton, D.S. Flett, D.W. West, Solvent extraction ion exchange, 2(6), (1984) 815-838) described a process for the separation of cobalt from nickel using Cyanex 272 as the extractant. The results indicated that Cyanex 272 is superior to the analogous phosphoric acid and phosphonic acids in terms of Co-Ni selectivity. The major sources for the generation of aqueous solutions containing nickel and sodium sulphate pertaining to the present invention are lateritic ore, supper-alloy scrap, catalyst, etc., which are processed through pyro-hydrometallurgical routes. Most of the studies reported are on the separation of cobalt from nickel from the leach solutions leaving nickel and sodium/ammonium sulphate (depending on the alkali or ammonia used for extractant neutralisation) in the raffinate. The raffinate obtained after cobalt separation generally contains 20-35 kg/m3 nickel and 15-20 kg/m3 sodium/ammonium sulphate, depending on the cobalt concentration in the leach solutions. Nickel recovery from these raffinate solutions can be affected by evaporation and crystallisation which requires lot of heat energy. Most of the research work reported in the literature on solvent extraction of nickel using D2EHPA, PC-88A and Cyanex 272 is concerned with the structure, selectivity and nature of the extracted metal species usually from micro-level concentrations. For example, Danesi et al. (P.R. Danesi, L. Reichley-Yinger, G. Mason, L. Kaplan, E.P. Horwitz, H. Diamond, Solvent Extn. Ion Exch. 3(4), (1985), 435-452) studied the extraction of cobalt and nickel using the phosphoric, phosphonic and phosphinic extractants to establish correlation between structure of the extractants and their selectivity for cobalt over nickel. The studies were mostly carried out in nitrate medium (0.3 NFLtNCh) at tracer level concentration (10~6 M) of the metals and a few experiments were carried out at 10"3 M metal concentrations. Preston (J.S. Preston, Journal of the South African Institute of Mining and Metallurgy, 33(6), (1983), 126-132) studied the extraction of cobalt and nickel using D2EHPA, PC 88A and Cyanex 272 from a feed solution containing 3 kg/m3 of cobalt and nickel and 40 kg/m3 of ammonium sulphate. He established the PC-88A and Cyanex 272 were better than D2EHPA so far as selectivity is concerned and also that these two reagents can be used at ambient temperature in contrast to D2EHPA where higher temperatures are required for Co-Ni separation. Di(2-ethyl hexyl) phosphoric acid, 2-ethyl-hexyl-2-ethylhexyl phosphonic acid (RD 577) and Cyanex CNX were used as extractants by Preston (J.S. Preston, Hydrometallurgy 9(2) (1982), 115-133). Extraction was studied for solutions containing 0.10 M Co(II)/Ni(II) as nitrates as well as 1.00 M ammonium nitrate. Other ammonium salts (chloride and sulphate) were used to investigate the effect of anion on extraction equilibria. Improved cobalt-nickel separations were obtained at elevated temperature for all three extractants. Thus, the present invention is entirely different from the reported studies and novel in that nickel extraction was studied at macro-level concentration (-0.5 M), that too in presence of sodium sulphate of-0.15 M concentration. The main object of the present invention is to provide a process for the solvent extraction of nickel at macro levels from solution containing nickel and sodium sulphate using di-(2 -ethyl hexyl) phosphoric acid which obviates the drawbacks as detailed above. Accordingly the present invention provides a process for the extraction of nickel at macro-level from a solution containing nickel and sodium sulphate which comprises contacting the said feed solution characterized in that with a partially neutralized organ phosphoric acid extracting reagent having the formula: (Formula Removed) and dissolved in an inert organic diluents, extracting the nickel values from the aqueous phase leaving sodium sulphate in the resultant aqueous phase (raffmate), stripping the loaded organic phase with mineral acid/spent electrolyte to recover nickel in a form suitable for nickel cathode production by conventional method. According to the process described in this invention, an acidic aqueous solution or a raffmate (obtained after cobalt separation) containing nickel and sodium sulphate is subjected to solvent extraction with a partially neutralized organ phosphoric acid based extractant dissolved in an inert organic diluent. During the extraction of metal values the organic phase becomes loaded with nickel while the sodium sulphate remains in the aqueous solution. The two phases are then separated and the organic phase containing the nickel is contacted with a mineral acid/spend electrolyte to strip the nickel values. The solvent thus regenerated could be reused in the extraction step. Sodium sulphate can be recovered by evaporation and crystallization from the raffmate obtained after nickel separation. The feed solution containing the nickel and sodium sulphate can be contacted with solvent extraction reagent employing the well known procedures followed in solvent extraction operations such as continuous counter-current, batch, continuous batch and batch counter-current methods. The particular ratio of the volume of the organic phase to the aqueous phase required for complete separation of nickel can be determined using the extraction isotherms. The loaded organic containing the nickel is advantageously contacted with mineral acid, e.g., sulphuric, nitric or hydrochloric, of required quantity, depending on the choice of the salt required. Alternatively, the metal values can be brought back from the loaded organic phase by contacting with the spent electrolyte, and the resulting strip solution is suitable for making a nickel salt by crystallisation or nickel metal by electrolysis. The raffinate containing sodium sulphate can be used to recover sodium sulphate. The present invention is illustrated by the following example and should not be contrued to limit the scope of the present invention. EXAMPLE 1 (a) Feed composition and reagents : A series of solvent extraction tests were carried out with a feed solution containing 34.4 kg/m3 of nickel and 20 kg/m3 of sodium sulphate. The commercial extraction reagent, di-(2-ethylhexyl) phosphoric acid supplied by Albright and Wilson, dissolved in kerosene (mostly aliphatic, b.p. 165-180°C) was used as the extractant. (b) Extraction procedure : All the extraction experiments were carried out at room temperature (30+2°C). Suitable volumes of the aqueous feed solution containing the nickel was contacted with the solvent extraction reagent in shake flasks for five minutes. After disengagement of the two phases, they were separated and analysed for the nickel concentration in the aqueous phase. The loaded organic containing the nickel was stripped with hydrochloric acid for determining the metal values, wherever necessary. (c) Effect of extractant concentration and neutrlaisation : A feed solution (pH : 4.5) of above mentioned composition containing nickel and sodium sulphate was contacted with di-(2-ethylhexyl) phosphoric acid of 0.3-1.0 M concentration (neutralised to 60-90% with alkali) at an aqueous to organic volume phase ratio of 1:4 and 1:5. The results of these experiments are tabulated in the Table-1 below : TABLE-1 Effect of extractant concentration and extent of neutralisation (Table Removed) (d) Extraction isotherm for nickel: The extraction isotherm was obtained by contacting the aqueous feed and 0.4 M di-(2-ethylhexyl) phosphoric acid (neutralised to 80% with alkali) at different aqueous to organic (A:O) volume ratios ranging between 1:0.25 and 1:10, which showed that quantitative nickel extraction is possible in three counter-current stages at an aqueous to organic phase ratio of 1:4. Batch counter-current simulation test: A 3-stage batch counter-current simulation study was carried out under the above conditions at an aqueous to organic ratio of 1:4. At equilibrium, the raffinate and loaded organic phase were found to contain 0.12 and 8.57 kg/m3 of nickel, respectively. The extraction efficiency of nickel was 99.65%. (!) Stripping of nickel from the loaded organic : Nickel stripping from the loaded organic phase (LO) can be carried out at a suitable aqueous to organic phase ratio in two ways (i) contacting the LO with required quantity of sulphuric acid in order to obtain a concentrated nickel sulphate solution suitable for nickel sulphate preparation, (ii) contacting the LO with spent electrolyte containing 57 kg/m3 nickel and 12 kg/m3 of sodium sulphate and 12 kg/m3 of boric acid so as to enrich the nickel content of the pregnant electrolyte by around 4 kg/m3 suitable for electrolysis to produce cathode nickel using conventional cells. In this investigation, spent electrolyte of the above composition having pH in the range 1.65 to 1.8 at an A:O ratio of 2:1 was used for nickel stripping from the L.O. The results of single stage contact are tabulated in Table 2 given below : TABLE 2 EFFECT OF SPENT ELECTROLYTE pH ON NICKEL STRIPPING (Table Removed) Using a spent electrolyte (S.E) of pH 1.65, it is possible to achieve more than 97.9% nickel stripping to obtain pregnant electrolyte of pH 2.6. When the S.E. pH increased to 1.8, the resulting P.E. pH was 3.3 and the stripping efficiency was 84.4%. This necessitates a minimum of three stage in continuous operation to strip out nickel completely. We Claim: 1 . A process for the extraction of nickel at macro-level from a solution containing nickel and sodium sulphate which comprises contacting the said feed solution with a partially neutralized organophosphoric acid extracting reagent having the formula: (Formula Removed) and dissolved in an inert organic diluent, extracting the nickel values form the aqueous phase leaving sodium sulphate in the resultant aqueous phase (raffmate), stripping the loaded organic phase with mineral acid/spent electrolyte to recover nickel in a form suitable for nickel cathode production by conventional method. 2. A process as claimed in claim 1 wherein the extraction of nickel takes place from feed solution having pH in the range 4-5. 3. A process as claimed in claim 1 wherein the organ phosphoric acid compound is di(2-ethylhexyl) phosphoric acid neutralized with an alkali. 4. A process as claimed in claims 1&3 wherein the extracting reagent is dissolveed in inert organic diluents of aliphatic or aromatic hydrocarbons, halogenated hydrocarbons or petroleum derivatives such as benzene, toluene, carbon tetrachloride, chloroform or kerosene. 5. A process as claimed in claim 1 wherein quantitative nickel extraction is achieved from a feed solution having pH around 4.5 at an aqueous to organic phase ratio of 1:4 using 0.4M extracting reagent neutralized to 70 to 80% with alkali. 6. A process as claimed in claims 1-5 wherein the mineral acid is such as HC1. 7. A process as claimed in claims 1&5 wherein the nickel extraction efficiency was more than 99%. 8. A process as claimed in claims 1-6 wherein the spent electrolyte used contains 45- 57 kg/m3 of nickel, 10-40 kg/m3 of sodium sulphate and 10-20 kg/m3 of boric acid at an Aqueous:Organic phase of 2.2:1. 9. A process as claimed in claims 1&7 wherein the strip solution is suitable for electrolysis to produce cathode nickel. 10. A process for the extraction of nickel at macro level from solutions containing nickel and sodium sulphate using neutralized organophorous acid substantially as here described with reference to the example accompanying the specification.

Full Text

The present invention relates to a process for the extraction of nickel at macro-levels from solutions containing nickel and sodium sulphate using di-(2-ethylhexyl) phosphoric acid in which the nickel is extracted using a partially neutralised extractant (with alkali/ammonia) leaving with sodium sulphate in the aqueous solution.
Processes are reported for the separation of cobalt and nickel from acidic sulphate solutions in which the separation of cobalt is carried out with partially neutralised organophosphoric acid based extractants, viz., di-(e-thylhexyl) phosphoric acid (D2EHPA), PC-88A and Cyanex 272 leaving the nickel values in the aqueous solutions. Ashbrook and Ritcey (A.W. Ashbrook, G.. Ritcey, Can. Pat. 795, 724, 1968) studied the extraction of cobalt from a feed solution containing 11.7-12.2 kg/m3 cobalt and 13.32-14.1 kg/m3 nickel. The cobalt recovery was about 98% when extraction was carried in the pH range 5-6.5 using an ammonia neutralised solvent of 5-40 vol.%. Cobalt stripping from the loaded organic was carried out using a mineral acid. Fugimoto et al. (A. Fugimoto, I. Muira, K. Noguchi, U.S. Patent, 4, 196, 076 (1980)) reported the separation of cobalt from nickel using 10-40% PC-88A at pH 5-6.5.. TBP and isodecanol was added to prevent emulsification. 0.5-5N inorganic acid was used to reextract cobalt salts from , the organic solvent. Rickelton et al. (W.A. Rickelton, D.S. Flett, D.W. West, Solvent extraction ion exchange, 2(6), (1984) 815-838) described a process for the separation of cobalt from nickel using Cyanex 272 as the extractant. The results indicated that Cyanex 272 is superior to the analogous phosphoric acid and phosphonic acids in terms of Co-Ni selectivity.
The major sources for the generation of aqueous solutions containing nickel and sodium sulphate pertaining to the present invention are lateritic ore, supper-alloy scrap, catalyst, etc., which are processed through pyro-hydrometallurgical routes. Most of the studies reported are on the separation of cobalt from nickel from the leach solutions leaving nickel and sodium/ammonium sulphate (depending on the alkali or ammonia used for extractant neutralisation) in the raffinate.
The raffinate obtained after cobalt separation generally contains 20-35 kg/m3 nickel and 15-20 kg/m3 sodium/ammonium sulphate, depending on the cobalt

concentration in the leach solutions. Nickel recovery from these raffinate solutions can be affected by evaporation and crystallisation which requires lot of heat energy.
Most of the research work reported in the literature on solvent extraction of nickel using D2EHPA, PC-88A and Cyanex 272 is concerned with the structure, selectivity and nature of the extracted metal species usually from micro-level concentrations. For example, Danesi et al. (P.R. Danesi, L. Reichley-Yinger, G. Mason, L. Kaplan, E.P. Horwitz, H. Diamond, Solvent Extn. Ion Exch. 3(4), (1985), 435-452) studied the extraction of cobalt and nickel using the phosphoric, phosphonic and phosphinic extractants to establish correlation between structure of the extractants and their selectivity for cobalt over nickel. The studies were mostly carried out in nitrate medium (0.3 NFLtNCh) at tracer level concentration (10~6 M) of the metals and a few experiments were carried out at 10"3 M metal concentrations. Preston (J.S. Preston, Journal of the South African Institute of Mining and Metallurgy, 33(6), (1983), 126-132) studied the extraction of cobalt and nickel using D2EHPA, PC 88A and Cyanex 272 from a feed solution containing 3 kg/m3 of cobalt and nickel and 40 kg/m3 of ammonium sulphate. He established the PC-88A and Cyanex 272 were better than D2EHPA so far as selectivity is concerned and also that these two reagents can be used at ambient temperature in contrast to D2EHPA where higher temperatures are required for Co-Ni separation. Di(2-ethyl hexyl) phosphoric acid, 2-ethyl-hexyl-2-ethylhexyl phosphonic acid (RD 577) and Cyanex CNX were used as extractants by Preston (J.S. Preston, Hydrometallurgy 9(2) (1982), 115-133). Extraction was studied for solutions containing 0.10 M Co(II)/Ni(II) as nitrates as well as 1.00 M ammonium nitrate. Other ammonium salts (chloride and sulphate) were used to investigate the effect of anion on extraction equilibria. Improved cobalt-nickel separations were obtained at elevated temperature for all three extractants.
Thus, the present invention is entirely different from the reported studies and novel in that nickel extraction was studied at macro-level concentration (-0.5 M), that too in presence of sodium sulphate of-0.15 M concentration.

The main object of the present invention is to provide a process for the solvent extraction of nickel at macro levels from solution containing nickel and sodium sulphate using di-(2 -ethyl hexyl) phosphoric acid which obviates the drawbacks as detailed above.
Accordingly the present invention provides a process for the extraction of nickel at macro-level from a solution containing nickel and sodium sulphate which comprises contacting the said feed solution characterized in that with a partially neutralized organ phosphoric acid extracting reagent having the formula:
(Formula Removed)
and dissolved in an inert organic diluents, extracting the nickel values from the aqueous phase leaving sodium sulphate in the resultant aqueous phase (raffmate), stripping the loaded organic phase with mineral acid/spent electrolyte to recover nickel in a form suitable for nickel cathode production by conventional method.
According to the process described in this invention, an acidic aqueous solution or a raffmate (obtained after cobalt separation) containing nickel and sodium sulphate is subjected to solvent extraction with a partially neutralized organ phosphoric acid based extractant dissolved in an inert organic diluent. During the extraction of metal values the organic phase becomes loaded with nickel while the sodium sulphate remains in the aqueous solution.
The two phases are then separated and the organic phase containing the nickel is contacted with a mineral acid/spend electrolyte to strip the nickel values. The solvent thus regenerated could be reused in the extraction step. Sodium sulphate can be recovered by evaporation and crystallization from the raffmate obtained after nickel separation.
The feed solution containing the nickel and sodium sulphate can be contacted with
solvent extraction reagent employing the well known procedures followed in solvent extraction operations such as continuous counter-current, batch, continuous batch and batch counter-current methods.
The particular ratio of the volume of the organic phase to the aqueous phase required for complete separation of nickel can be determined using the extraction isotherms. The loaded organic containing the nickel is advantageously contacted with mineral acid, e.g., sulphuric, nitric or hydrochloric, of required quantity, depending on the choice of the salt required. Alternatively, the metal values can be brought back from the loaded organic phase by contacting with the spent electrolyte, and the resulting strip solution is suitable for making a nickel salt by crystallisation or nickel metal by electrolysis.
The raffinate containing sodium sulphate can be used to recover sodium sulphate.
The present invention is illustrated by the following example and should not be contrued to limit the scope of the present invention.
EXAMPLE 1
(a) Feed composition and reagents :
A series of solvent extraction tests were carried out with a feed solution containing 34.4 kg/m3 of nickel and 20 kg/m3 of sodium sulphate. The commercial extraction reagent, di-(2-ethylhexyl) phosphoric acid supplied by Albright and Wilson, dissolved in kerosene (mostly aliphatic, b.p. 165-180°C) was used as the extractant.
(b) Extraction procedure :
All the extraction experiments were carried out at room temperature (30+2°C). Suitable volumes of the aqueous feed solution containing the nickel was contacted with
the solvent extraction reagent in shake flasks for five minutes. After disengagement of the two phases, they were separated and analysed for the nickel concentration in the aqueous phase. The loaded organic containing the nickel was stripped with hydrochloric acid for determining the metal values, wherever necessary.
(c) Effect of extractant concentration and neutrlaisation :
A feed solution (pH : 4.5) of above mentioned composition containing nickel and sodium sulphate was contacted with di-(2-ethylhexyl) phosphoric acid of 0.3-1.0 M concentration (neutralised to 60-90% with alkali) at an aqueous to organic volume phase ratio of 1:4 and 1:5. The results of these experiments are tabulated in the Table-1 below :
TABLE-1 Effect of extractant concentration and extent of neutralisation

(Table Removed)
(d) Extraction isotherm for nickel:
The extraction isotherm was obtained by contacting the aqueous feed and 0.4 M di-(2-ethylhexyl) phosphoric acid (neutralised to 80% with alkali) at different aqueous to organic (A:O) volume ratios ranging between 1:0.25 and 1:10, which showed that quantitative nickel extraction is possible in three counter-current stages at an aqueous to organic phase ratio of 1:4.
Batch counter-current simulation test:
A 3-stage batch counter-current simulation study was carried out under the above conditions at an aqueous to organic ratio of 1:4. At equilibrium, the raffinate and loaded
organic phase were found to contain 0.12 and 8.57 kg/m3 of nickel, respectively. The extraction efficiency of nickel was 99.65%.
(!) Stripping of nickel from the loaded organic :
Nickel stripping from the loaded organic phase (LO) can be carried out at a suitable aqueous to organic phase ratio in two ways (i) contacting the LO with required quantity of sulphuric acid in order to obtain a concentrated nickel sulphate solution suitable for nickel sulphate preparation, (ii) contacting the LO with spent electrolyte containing 57 kg/m3 nickel and 12 kg/m3 of sodium sulphate and 12 kg/m3 of boric acid so as to enrich the nickel content of the pregnant electrolyte by around 4 kg/m3 suitable for electrolysis to produce cathode nickel using conventional cells.
In this investigation, spent electrolyte of the above composition having pH in the range 1.65 to 1.8 at an A:O ratio of 2:1 was used for nickel stripping from the L.O. The results of single stage contact are tabulated in Table 2 given below :
TABLE 2
EFFECT OF SPENT ELECTROLYTE pH ON NICKEL STRIPPING

(Table Removed)
Using a spent electrolyte (S.E) of pH 1.65, it is possible to achieve more than 97.9% nickel stripping to obtain pregnant electrolyte of pH 2.6. When the S.E. pH increased to 1.8, the resulting P.E. pH was 3.3 and the stripping efficiency was 84.4%. This necessitates a minimum of three stage in continuous operation to strip out nickel completely.

We Claim:
1 . A process for the extraction of nickel at macro-level from a solution containing nickel and sodium sulphate which comprises contacting the said feed solution with a partially neutralized organophosphoric acid extracting reagent having the formula:
(Formula Removed)
and dissolved in an inert organic diluent, extracting the nickel values form the aqueous phase leaving sodium sulphate in the resultant aqueous phase (raffmate), stripping the loaded organic phase with mineral acid/spent electrolyte to recover nickel in a form suitable for nickel cathode production by conventional method.
2. A process as claimed in claim 1 wherein the extraction of nickel takes place from
feed solution having pH in the range 4-5.
3. A process as claimed in claim 1 wherein the organ phosphoric acid compound is
di(2-ethylhexyl) phosphoric acid neutralized with an alkali.
4. A process as claimed in claims 1&3 wherein the extracting reagent is dissolveed
in inert organic diluents of aliphatic or aromatic hydrocarbons, halogenated
hydrocarbons or petroleum derivatives such as benzene, toluene, carbon
tetrachloride, chloroform or kerosene.
5. A process as claimed in claim 1 wherein quantitative nickel extraction is achieved
from a feed solution having pH around 4.5 at an aqueous to organic phase ratio of
1:4 using 0.4M extracting reagent neutralized to 70 to 80% with alkali.
6. A process as claimed in claims 1-5 wherein the mineral acid is such as
HC1.

7. A process as claimed in claims 1&5 wherein the nickel extraction efficiency was
more than 99%.
8. A process as claimed in claims 1-6 wherein the spent electrolyte used contains 45-
57 kg/m3 of nickel, 10-40 kg/m3 of sodium sulphate and 10-20 kg/m3 of boric acid
at an Aqueous:Organic phase of 2.2:1.
9. A process as claimed in claims 1&7 wherein the strip solution is suitable for
electrolysis to produce cathode nickel.
10. A process for the extraction of nickel at macro level from solutions containing
nickel and sodium sulphate using neutralized organophorous acid substantially as
here described with reference to the example accompanying the specification.

Documents:

270-del-2001-abstract.pdf

270-del-2001-claims.pdf

270-del-2001-correspondence-po.pdf

270-del-2001-correspondence.pdf

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

270-del-2001-form-1.pdf

270-del-2001-form-2.pdf

270-del-2001-form-3.pdf

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Patent Number

231043

Indian Patent Application Number

270/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

12-Mar-2001

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	PERVELA VENKATA RAMA BHASKARA SARMA	REGIONAL RESEARCH LABORATORY, BHUBNESHWAR-751013, INDIA
2	BONTHA RAMACHANDRA REDDY	REGIONAL RESEARCH LABORATORY, BHUBNESHWAR-751013, INDIA

PCT International Classification Number

C22B 3/08

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA