Title of Invention	AN IMPROVED PROCESS FOR SIMULTANEOUS EXTRACTION OF NICKEL AND COBALT FROM PRECIPITATED SULPHIDES
Abstract	The invention relates to an improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides. The nickel and cobalt containing sulphides precipitated from nickel and cobalt sulphate solutions, or obtained from pilot plant/ commercial plants are dried at 100-150°C for two hours and ground. The nickel and cobalt values are simultaneously extracted by treating the ground sulphide in sulphuric acid, if required, in the presence of an oxidizing agent. Depending on the conditions 90 to 99% extraction of nickel and cobalt is achieved in this process.

Title of Invention

AN IMPROVED PROCESS FOR SIMULTANEOUS EXTRACTION OF NICKEL AND COBALT FROM PRECIPITATED SULPHIDES

Abstract

The invention relates to an improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides. The nickel and cobalt containing sulphides precipitated from nickel and cobalt sulphate solutions, or obtained from pilot plant/ commercial plants are dried at 100-150°C for two hours and ground. The nickel and cobalt values are simultaneously extracted by treating the ground sulphide in sulphuric acid, if required, in the presence of an oxidizing agent. Depending on the conditions 90 to 99% extraction of nickel and cobalt is achieved in this process.

Full Text	This invention relates to an improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides. More particularly this invention relates to an improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides in sulphuric acid medium optionally in the presence of an oxidant. Both nickel and cobalt are strategic metals due to their wide applications. Cobalt is an important constituent of many permanent , magnets and special alloys whereas nickel is important for stainless steel special alloys and electroplating. About 95% of world's cobalt production is as a by-product from nickel and copper from copper-cobalt sulphides (55%), nickel-copper sulphides (20%), and nickeliferous laterites (20%). The mixed nickel-cobalt sulphides are precipitated from ammoniacal process liquors derived from nickel sulphide concentrates, sulphides obtained by pyrometallurgical treatment of nickel-cobalt containing ores (mattes), reduced nickeliferous laterites, manganese nodule ammoniacal leach liquors etc. The conventional method for dissolution of these sulphides is either by acid pressure leaching (Nippon Mining Corporation) or by oxidative ammoniacal leaching ( Sherrit Gordon ). During acid pressure leaching temperature of 120 to 130°C is maintained with oxygen partial pressure as 3 to 5 kg/cm2 ( Jhon H. Canterford and Norman f. Dyson, Proc. Australas. Inst. Min. Metall, 1981, vol. 280, p55-59 ). Ammoniacal leaching is carried out at 80 to 90°C in presence of compressed air keeping the total system pressure at 7-8 kg/cm2. The further down stream processing of ammoniacal solutions for production of nickel/ cobalt powders is done through hydrogen reduction (system pressure 50-60 kg/cm2 ). Processing of acid leach solutions is done through solvent extraction-electrowinning to produce nickel and cobalt cathodes. The main disadvantage of both the above mentioned acid and ammoniacal routes is the requirement of high pressure reactors to carry out dissolution of sulphides which need high capital costs. In India, such vessels for carrying out solid-liquid-gas reactions at high temperatures are not commercially available and import of these reactors for small capacity plants will not be economical. Therefore, a modified route which does not require sophisticated equipment has been developed to extract nickel and cobalt from precipitated sulphides. The dissolved metals can be separated and recovered using solvent extraction/precipitation-electrowinning techniques. The main object of the present invention is to extract nickel and cobalt in sulphuric acid at 60-90°C from the sulphides precipitated synthetically from nickel and cobalt sulphate solutions using sodium sulphide as the precipitant. Another object of the present invention is to extract nickel and cobalt from precipitated nickel-cobalt sulphides obtained during processing of manganese nodules in ammoniacal medium. Yet another object of the present invention is to extract nickel and cobalt from precipitated sulphide obtained from a commercial plant from Cuba. Accordingly the present invention provides an improved process for the simultaneous extraction of nickel and cobalt from precipitated suphides which comprises; a) precipitating the sulphides from nickel and cobalt sulphate solutions or obtaining the precipitated sulphides from pilot or commercial plant, b) characterized in that drying the precipitated sulphide at a temperature ranging between 100-150°C for about two hours, c) grinding the above said dried sulphide to obtain -100 mesh British standard size and d) treating the above said ground sulphides with 0.8 to 1% sulphuric acid (v/v), optionally in the presence of an oxidizing agent at a temperature ranging between 60 to 90°C to obtain the desired product. In an embodiment of the present invention the extraction of nickel and cobalt is in the range of 90 to 99%. In an anoOther embodiment the composition of nickel and cobalt in the precipitated nickel-cobalt sulphides is in the range of 9.73-38.65 and 2.1-12.7 respectively. In yet another embodiment the oxidizing agent used is selected from the group consisting of H2C>2, gaseous oxygen and compressed air. Novelty of the present invention is (a) drying of nickel - cobalt precipitated sulphides at a temperature of 100-150°C for two hours which results in thermal activation of the precipitated sulphide (b) grinding of the activated sulphide and (c) extracting simultaneously both nickel and cobalt in sulphuric acid at a temperature of 60 to 90°C and (d) extracting nickel and cobalt in the presence of an oxidant, if required. The following examples are given to illustrate how the process of the present invention is carried out in actual practice and should not be construed to limit the scope of the invention. Example 1 1000 millilitres of water was taken and 54.30 grams of nickel sulphate, 4.78 grams of cobalt sulphate were dissolved. The pH of the solution was adjusted to 6.35 by adding 25% (wt./vol.) ammonia solution. 32 gram of sodium sulphide was dissolved in 50 millilitres of water. This solution was slowly added to Ni-Co sulphate solution while stirring the contents. The precipitated sulphide was filtered through whatman filter paper no. 1 using water suction. The wet cake was kept in an oven at 150°C for two hours. The dried cake was ground and weighed 30.54 grams and contained 38.67% Ni and 3.11% Co. Weighed amount of this dried and ground sulphide was subjected to leaching under conditions given in Table 1. It is observed that in the presence of hydrogen peroxide 97% Ni and 95.2 % cobalt can be extracted. Table 1 Dissolution of Ni and Co from synthetically prepared sulphide. (Table Removed) Example 2 1000 millilitres of water was taken and 100 grams of ammonium sulphate was added to it (usually the Ni-Co sulphides are precipitated from ammonical solutions containing ammonium sulphate in commercial plants). 25.0 grams of nickel sulphate and 17 grams of cobalt sulphate were dissolved in the ammonium sulphate solution. The pH of the solution was adjusted to 4.68 by adding 60 ml of 25% (wt./vol.) ammonia solution. 32 gram of sodium sulphide was dissolved in 50 millilitres of water. This solution was slowly added to Ni-Co sulphate solution while stirring the contents. The precipitated sulphide was filtered through whatman filter paper no. 1 using water suction. The wet cake was kept in an oven at 150°C for two hours. The dried cake was ground and weighed 30.18 grams. The composition of the dried sulphide was: 19.14% Ni and 12.69 % Co. 7.5 grams of this material was leached for two hours at 70°C using 1ml sulphuric acid , 3 ml of 30% H2O2 and 97 ml of water. 96.45% Ni and 98.8% Co dissolution took place. Example 3 The bulk sulphide precipitated from the ammoniacal leach liquor obtained by processing of ocean nodules was treated under the following conditions: drying the sulphide precipitate at 150°C for two hours, grinding the dried material to obtain 100% less than 100 mesh B.S.S. 10 gram of the sieved material was leached at 90°C for two hours with 1 ml H2SO4, 3 ml H2O2 and 96 ml of water. 96% Ni and 92% Co dissolved under the above mentioned conditions. Example 4 In another experiment the precipitated sulphide was obtained as given in Example3. 10 gram was leached under the following conditions: leaching temperature 90°C, leaching time two hours, 1 ml H2SO4, 97 ml of water and pO2 0.5kg/cm2. 98.7% Ni and 96.5% Co dissolved under the above mentioned conditions. Example 5 The precipitated sulphide from an ammoniacal leach liquor obtained from a laterite plant of Cuba had the following composition : Ni 9.73%, Co 7.43%, Zn 0.011% and Cu 1.69% with moisture content as 18%. 20 gram of this sulphide was dried at a temperature of 100°C for two hours. The dried sulphide was ground and leached under the conditions given in Table 2. The extractions of nickel and cobalt were 93.8 and 89.2% respectively. Table 2 Dissolution of Ni-Co sulphide obtained from laterite plant of Cuba (Table Removed) Example 6 The precipitated sulphide as mentioned in example 6 (obtained from a commercial plant at Cuba) was used. 20 gram of this sulphide was dried at a temperature of 125°C for two hours. The dried sulphide was ground and leached under the conditions given in Table 3. The extractions of nickel and cobalt were 94.3 and 92.7% respectively. Table 3 Dissolution of Ni-Co sulphide obtained from laterite plant of Cuba (Table Removed) Example 7 The precipitated sulphide as mentioned in example 6 (obtained from a commercial plant at Cuba) was used. 20 gram of this sulphide was dried at a temperature of 150°C for two hours. The dried sulphide was ground and leached under the conditions given in Table 4. The extractions of nickel and cobalt were 99.3 and 99% respectively. Table 4 Dissolution of Ni-Co sulphide obtained from laterite plant of Cuba (Table Removed) The main advantages of the process are : 1. The process steps for dissolution of nickel and cobalt from precipitated sulphides are drying at 150°C, grinding and dissolving in acidified solution in presence of H2O2/ O2/air. 2. The leaching temperature required is only 60-90°C and ordinary reactors made of mild steel with FRP coating can be used for the purpose. 3. The earlier processes being used require high pressure reactors for dissolution of precipitated sulphides both under ammoniacal as well as acid medium. 4. 95 to 99% extraction of nickel and cobalt is achieved from synthetic sulphides of varying compositions, sulphides obtained from processing of ocean nodules and the sulphides obtained from commercial plant generating such sulphides. 5. In many commercial plants the sulphide is precipitated from solutions containing ammonium sulphate. The process will also be applicable to any such nickel-cobalt precipitated sulphides. We Claim: 1. An improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides which comprises; a) precipitating the sulphides from nickel and cobalt sulphate solutions or obtaining the precipitated sulphides from pilot or commercial plant, b) characterized in that drying the precipitated sulphide at a temperature ranging between 100-150°C for about two hours, c) grinding the above said dried sulphide to obtain -100 mesh British standard size and d) treating the above said ground sulphides with 0.8 to 1% sulphuric acid (v/v), optionally in the presence of an oxidizing agent at a temperature ranging between 60 to 90°C to obtain the desired product. 2. An improved process as claimed in claim 1, wherein the extraction of nickel and cobalt is in the range of 90 to 99%. 3. An improved process as claimed in claims 1&2, wherein the composition of nickel and cobalt in the precipitated nickel-cobalt sulphides is in the range of 9.73-38.65 and 2.1-12.7 respectively. 4. An improved process as claimed in claims 1-3, wherein the oxidizing agent used is selected from the group consisting of tbC^, gaseous oxygen and compressed air. 5. An improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides as herein described with reference to examples.

Full Text

This invention relates to an improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides.
More particularly this invention relates to an improved process for the simultaneous extraction of nickel and cobalt from precipitated sulphides in sulphuric acid medium optionally in the presence of an oxidant.
Both nickel and cobalt are strategic metals due to their wide applications. Cobalt is an important constituent of many permanent , magnets and special alloys whereas nickel is important for stainless steel
special alloys and electroplating. About 95% of world's cobalt

production is as a by-product from nickel and copper from copper-cobalt sulphides (55%), nickel-copper sulphides (20%), and nickeliferous laterites (20%). The mixed nickel-cobalt sulphides are precipitated from ammoniacal process liquors derived from nickel sulphide concentrates, sulphides obtained by pyrometallurgical treatment of nickel-cobalt containing ores (mattes), reduced nickeliferous laterites, manganese nodule ammoniacal leach liquors etc.
The conventional method for dissolution of these sulphides is either by acid pressure leaching (Nippon Mining Corporation) or by oxidative ammoniacal leaching ( Sherrit Gordon ). During acid pressure leaching temperature of 120 to 130°C is maintained with oxygen partial pressure as 3 to 5 kg/cm2 ( Jhon H. Canterford and Norman f. Dyson, Proc. Australas. Inst. Min. Metall, 1981, vol. 280, p55-59 ). Ammoniacal leaching is carried out at 80 to 90°C in presence of compressed air keeping the total system pressure at 7-8 kg/cm2. The further down stream processing of ammoniacal solutions for production of nickel/ cobalt

powders is done through hydrogen reduction (system pressure 50-60 kg/cm2 ). Processing of acid leach solutions is done through solvent extraction-electrowinning to produce nickel and cobalt cathodes.
The main disadvantage of both the above mentioned acid and ammoniacal routes is the requirement of high pressure reactors to carry out dissolution of sulphides which need high capital costs. In India, such vessels for carrying out solid-liquid-gas reactions at high temperatures are not commercially available and import of these reactors for small capacity plants will not be economical. Therefore, a modified route which does not require sophisticated equipment has been developed to extract nickel and cobalt from precipitated sulphides. The dissolved metals can be separated and recovered using solvent extraction/precipitation-electrowinning techniques.
The main object of the present invention is to extract nickel and cobalt in sulphuric acid at 60-90°C from the sulphides precipitated synthetically from nickel and cobalt sulphate solutions using sodium sulphide as the precipitant.
Another object of the present invention is to extract nickel and cobalt from precipitated nickel-cobalt sulphides obtained during processing of manganese nodules in ammoniacal medium.
Yet another object of the present invention is to extract nickel and cobalt from precipitated sulphide obtained from a commercial plant from Cuba.
Accordingly the present invention provides an improved process for the simultaneous extraction of nickel and cobalt from precipitated suphides which comprises;
a) precipitating the sulphides from nickel and cobalt sulphate solutions or obtaining
the precipitated sulphides from pilot or commercial plant,
b) characterized in that drying the precipitated sulphide at a temperature ranging
between 100-150°C for about two hours,
c) grinding the above said dried sulphide to obtain -100 mesh British standard size
and
d) treating the above said ground sulphides with 0.8 to 1% sulphuric acid (v/v),
optionally in the presence of an oxidizing agent at a temperature ranging between
60 to 90°C to obtain the desired product.
In an embodiment of the present invention the extraction of nickel and cobalt is in the range of 90 to 99%.
In an anoOther embodiment the composition of nickel and cobalt in the precipitated nickel-cobalt sulphides is in the range of 9.73-38.65 and 2.1-12.7 respectively.
In yet another embodiment the oxidizing agent used is selected from the group consisting of H2C>2, gaseous oxygen and compressed air.
Novelty of the present invention is (a) drying of nickel - cobalt precipitated sulphides at a temperature of 100-150°C for two hours which results in thermal activation of the precipitated sulphide (b) grinding of the activated sulphide and (c) extracting simultaneously both nickel and cobalt in sulphuric acid at a temperature of 60 to 90°C and (d) extracting nickel and cobalt in the presence of an oxidant, if required.
The following examples are given to illustrate how the process of the present invention is carried out in actual practice and should not be construed to limit the scope of the invention.
Example 1
1000 millilitres of water was taken and 54.30 grams of nickel sulphate, 4.78 grams of cobalt sulphate were dissolved. The pH of the solution was adjusted to 6.35 by adding 25% (wt./vol.) ammonia solution. 32 gram of sodium sulphide was dissolved in 50 millilitres of water. This solution was slowly added to Ni-Co sulphate solution while stirring the contents. The precipitated sulphide was filtered through whatman filter paper no. 1 using water suction. The wet cake was kept in an oven at 150°C for two hours. The dried cake was ground and weighed 30.54 grams and contained 38.67% Ni and 3.11% Co. Weighed amount of this dried and ground sulphide was subjected to leaching under conditions given in Table 1. It is observed that in the presence of hydrogen peroxide 97% Ni and 95.2 % cobalt can be extracted. Table 1 Dissolution of Ni and Co from synthetically prepared sulphide.
(Table Removed)
Example 2
1000 millilitres of water was taken and 100 grams of ammonium sulphate was added to it (usually the Ni-Co sulphides are precipitated from ammonical solutions containing ammonium sulphate in commercial plants). 25.0 grams of nickel sulphate and 17 grams of cobalt sulphate were dissolved in the ammonium sulphate solution. The pH of the solution was adjusted to 4.68 by adding 60 ml of 25% (wt./vol.) ammonia solution. 32 gram of sodium sulphide was dissolved in 50 millilitres of
water. This solution was slowly added to Ni-Co sulphate solution while stirring the contents. The precipitated sulphide was filtered through whatman filter paper no. 1 using water suction. The wet cake was kept in an oven at 150°C for two hours. The dried cake was ground and weighed 30.18 grams. The composition of the dried sulphide was: 19.14% Ni and 12.69 % Co. 7.5 grams of this material was leached for two hours at 70°C using 1ml sulphuric acid , 3 ml of 30% H2O2 and 97 ml of water. 96.45% Ni and 98.8% Co dissolution took place.
Example 3
The bulk sulphide precipitated from the ammoniacal leach liquor obtained by processing of ocean nodules was treated under the following conditions: drying the sulphide precipitate at 150°C for two hours, grinding the dried material to obtain 100% less than 100 mesh B.S.S. 10 gram of the sieved material was leached at 90°C for two hours with 1 ml H2SO4, 3 ml H2O2 and 96 ml of water. 96% Ni and 92% Co dissolved under the above mentioned conditions.
Example 4
In another experiment the precipitated sulphide was obtained as given in Example3. 10 gram was leached under the following conditions: leaching temperature 90°C, leaching time two hours, 1 ml H2SO4, 97 ml of water and pO2 0.5kg/cm2. 98.7% Ni and 96.5% Co dissolved under the above mentioned conditions.
Example 5
The precipitated sulphide from an ammoniacal leach liquor obtained from a laterite plant of Cuba had the following composition : Ni 9.73%, Co 7.43%, Zn 0.011% and Cu 1.69% with moisture content as 18%. 20 gram of this sulphide was dried at a temperature of 100°C for
two hours. The dried sulphide was ground and leached under the conditions given in Table 2. The extractions of nickel and cobalt were 93.8 and 89.2% respectively.
Table 2 Dissolution of Ni-Co sulphide obtained from laterite plant of Cuba
(Table Removed)
Example 6
The precipitated sulphide as mentioned in example 6 (obtained from a commercial plant at Cuba) was used. 20 gram of this sulphide was dried at a temperature of 125°C for two hours. The dried sulphide was ground and leached under the conditions given in Table 3. The extractions of nickel and cobalt were 94.3 and 92.7% respectively.
Table 3 Dissolution of Ni-Co sulphide obtained from laterite plant of Cuba
(Table Removed)
Example 7
The precipitated sulphide as mentioned in example 6 (obtained from a commercial plant at Cuba) was used. 20 gram of this sulphide was dried at a temperature of 150°C for two hours. The dried sulphide was ground and leached under the conditions given in Table 4. The extractions of nickel and cobalt were 99.3 and 99% respectively.
Table 4 Dissolution of Ni-Co sulphide obtained from laterite plant of Cuba
(Table Removed)
The main advantages of the process are :
1. The process steps for dissolution of nickel and cobalt from
precipitated sulphides are drying at 150°C, grinding and dissolving
in acidified solution in presence of H2O2/ O2/air.
2. The leaching temperature required is only 60-90°C and ordinary
reactors made of mild steel with FRP coating can be used for the
purpose.
3. The earlier processes being used require high pressure reactors for
dissolution of precipitated sulphides both under ammoniacal as
well as acid medium.
4. 95 to 99% extraction of nickel and cobalt is achieved from
synthetic sulphides of varying compositions, sulphides obtained
from processing of ocean nodules and the sulphides obtained from
commercial plant generating such sulphides.
5. In many commercial plants the sulphide is precipitated from
solutions containing ammonium sulphate. The process will also be
applicable to any such nickel-cobalt precipitated sulphides.

We Claim:
1. An improved process for the simultaneous extraction of nickel and cobalt from
precipitated sulphides which comprises;
a) precipitating the sulphides from nickel and cobalt sulphate solutions or obtaining
the precipitated sulphides from pilot or commercial plant,
b) characterized in that drying the precipitated sulphide at a temperature ranging
between 100-150°C for about two hours,
c) grinding the above said dried sulphide to obtain -100 mesh British standard size
and
d) treating the above said ground sulphides with 0.8 to 1% sulphuric acid (v/v),
optionally in the presence of an oxidizing agent at a temperature ranging between
60 to 90°C to obtain the desired product.

2. An improved process as claimed in claim 1, wherein the extraction of nickel and
cobalt is in the range of 90 to 99%.
3. An improved process as claimed in claims 1&2, wherein the composition of
nickel and cobalt in the precipitated nickel-cobalt sulphides is in the range of
9.73-38.65 and 2.1-12.7 respectively.
4. An improved process as claimed in claims 1-3, wherein the oxidizing agent used
is selected from the group consisting of tbC^, gaseous oxygen and compressed
air.
5. An improved process for the simultaneous extraction of nickel and cobalt from
precipitated sulphides as herein described with reference to examples.

Documents:

1301-del-2001-abstract.pdf

1301-del-2001-claims.pdf

1301-del-2001-correspondence-others.pdf

1301-del-2001-correspondence-po.pdf

1301-del-2001-description (complete).pdf

1301-DEL-2001-Form-1.pdf

1301-del-2001-form-18.pdf

1301-del-2001-form-2.pdf

1301-del-2001-form-3.pdf

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Patent Number

220677

Indian Patent Application Number

1301/DEL/2001

PG Journal Number

30/2008

Publication Date

25-Jul-2008

Grant Date

02-Jun-2008

Date of Filing

31-Dec-2001

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	SASMITA MOHANTY
2	DEVABRATA MISHRA
3	RADHANATH PRASAD DAS
4	SHASHI ANAND
5	MALAY KUMAR GHOSH

PCT International Classification Number

C22B 23/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA