Title of Invention	AN ECO-FRIENDLY PROCESS FOR THE PREPARATION OF MIXED OXIDE OF IRON, NICKEL, CHROMIUM & COBALT USEFUL FOR THE PRODUCTION OF VALUE ADDED NICKEL-FERROUS PRODUCTS
Abstract	An eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products by leaching lateritic nickel ore with mineral acid and traces of organic acid followed by filtration, heating the filtrate obtained in step (a) to boiling, adding neutralising agent to the boiling filtrate till the pH of the filtrate is in the range of 6-10 followed by filtration, washing the precipitate obtained in step (b) thoroughly with water and heating the washed precipitate so obtained in step (c) if required, to get the mixed oxide of iron, nickel, chromium & cobalt.

Title of Invention

AN ECO-FRIENDLY PROCESS FOR THE PREPARATION OF MIXED OXIDE OF IRON, NICKEL, CHROMIUM & COBALT USEFUL FOR THE PRODUCTION OF VALUE ADDED NICKEL-FERROUS PRODUCTS

Abstract

An eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products by leaching lateritic nickel ore with mineral acid and traces of organic acid followed by filtration, heating the filtrate obtained in step (a) to boiling, adding neutralising agent to the boiling filtrate till the pH of the filtrate is in the range of 6-10 followed by filtration, washing the precipitate obtained in step (b) thoroughly with water and heating the washed precipitate so obtained in step (c) if required, to get the mixed oxide of iron, nickel, chromium & cobalt.

Full Text	This invention relates to an eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products. The end product produced by the process of the present invention will be a mixed oxide of iron, nickel, chromium and cobalt. This may be used as raw material for making ferro-nickel and/or stainless steel. The end product may also be used for making soft magnets. The first commercially known process for the extraction of nickel from lateritic nickel ore was commisioned by the Freeport Sulfur Company. They had access to a huge reserve of lateritic nickel ore containing Though Freeport succeeded in producing nickel under trying conditions, the process was not economically competitive primarily due to poor metal extraction. Though initial exploits of Freeport Sulfur did not succeed to the extent it was desired to be, they came up with a better process in 1957. Lateritic nickel ore containing nickel extracted as sull'nde by H2S precipilalion. This is also known as Freeport Moa Bay process. Moa Bay process has several advantages but the primary constarint is that it is an energy intensive process. Moa Bay project in Cuba was abandoned in 1959 even before the plant was actually operative. Falconbridge process is an another established process which is relatively recent and where lateritic nickel ore is directly used for making ferro-nickel through reduction roasting followed by electric furnace smelting. Falconbridge process enjoys certain advantages in its concept as well as regarding the direct relevance of its end product. However, the process is energy intensive. Given below arc some of the imporatanl known processes for the extraction of nickel from laterilic ores. However, most of them have not yet been commercially exploited. In patent no. US4125588, 1977, a methodd has been given for the recovery of nickel and magnesia from laleritcs using; Low temperature sulfalion. In patent no, US 41959865, 1978, a process has been described lor the selective reduction of nickel lateritic ores for the extraction of non-ferrous metals. In patent no. US430I 125, 1977, a melhod has been given for the exlraclion of Ni from pre-reduced laterilic ores with aqueous sull'iiric acid inthe presence of peroxidanls. In patent no. US4311520, a process has been given for Ihe recovery of nickel, cobalt and manganese from their oxides and silicates. In patent no. GB2086872A, 1981 acid leaching of lalerilic nickel ores have been described. Acid leaching of nickel from serpentinic lalerilc ores have been described in palent no. US44I0498, 1980. A method of liberating nickel and cobalt from laleriles using high pressure acid leaching has been given in patent nos. US454I994, 1983 and US454I868, 1983, US4548794, 1983. All these processes are essentially extraction processes for nickel and oilier valuable metals from lalcrilic nickel ore. Enrichment of metal values in (he lalerilic ore may be a part of these processes, as normal exlarclion processes are no! commercially viable unless the starling material is enriched to some exlenl. However, il was not possible lo gel explicit access lo. such information . The common enrichment processes include physical bencficiation through floatation, magnetic separation, hand picking etc. Under normal cicumstances these methods have not been round to be very efficient for ores of' very lean nature like lalerilie nickel ore. Available processes all deal with lalerilie ores having nickel concentration more than 1%. Existing processes arc generally energy intensive processes. Existing processes generate huge quantity of residues and wastes which are not environment friendly and cause serious disposal problems. Existing processes arc not operator friendly and involve toxic reagents like hydrogen sulfide, carbon monoxide etc. Lalerilie nickel ores, especially (hose of Indian origin, are by nature lean ores. Available processes mostly deal with ores in which nickel content is morethan 1%. India has a huge reserve of latcrUic nickel ores. But unfortunately, the average nickel concentration in that lies between 0.4-0.6%. Presently, there is no available method nationally or internationally lo process nickel ores of such a low grade. Therefor R&D efforts have been made lo develop a process which can enrich lalerilie nickel ores having nickel content less than 1% and produce less pollution. The main objective of the present invention is to provide an cco-friendly process for the enrichment of nickel, cobalt and iron contents in lalerilic nickel ores useful for the production of value added nickcli-ferrous products. Another objective of.the proposed invention is to provide an improved process for the enrichment of nickel, cobalt and iron content of lalerilic nickel ores having nickel concentration less than 1%, whereby making it useful for value added nickcli-ferrous products. Yel another objective of the present invention is to provide an improved process for the enrichment of nickel, cobalt and iron content of lalerilic nickel ores and thereby reducing environmental pollution and operational hazards. In the process of the present invention, the metal components of the raw ore are taken in the solution by atmospheric acid leaching using a mineral acids and (races of organic-acids. Latcrilic nickel ores ar basically oxitles of iron where Ni is embedded in the Goelhile structure. Under reducing conditions the dissolution is belter though prior to that opening of the matrix is necessary. HNO3 and H2SO4 help in opening up Ihe matrix. Presence of H2SO4 causes sulfalion and supplies energy for that by reacting vvilh waler. The leach liquor contains sulfate, chloride and nitrate solutions of nickel, iron, cobalt and other soluble metals. The iron, nickel and cobalt components are precipitated as corresponding hydroxides using sodium carbonate as a precipitant at pH higher than 10. To complete the precipitation, af pellets of NaOH is added finally. The chemical reactions that take place are, (Equation Removed) The precipitate is heated at 900ºC to make the corresponding oxides. The reactions that take place are, (Equation Removed) Accordingly, the present invention provides an eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products which comprises: (a) leaching lateritic nickel ore with mineral acid such as herein described and traces of organic acid such as herein described followed by filtration; (b) heating the filtrate obtained in step (a) to boiling, adding neutralising agent to the boiling filtrate till the pH of the filtrate is in the range of 6- 10 followed by filtration; (c) washing the precipitate obtained in step (b) thoroughly with water; (d) heating the washed precipitate so obtained in step (c) at a temperature of 25 to 900°C if required, to get the mixed oxide of iron, nickel, chromium & cobalt. According to a feature of the invention, lateritic nickel ores used may be selected from Ni:0.1% and above. Mineral acids used for leaching lateritic nickel ore may be such as H2SO4, HCI, HNO3, H3PO4 singly or in combination thereof. Traces of organic acids used for leaching lateritic nickel ore may be such as oxalic acid, tartaric acid, ascorbic acid singly or in combination thereof. According to another feature of the invention, for effecting precipitation in The leach liquor, a number of neutralising agents used may be such as Na2CO3, (NH4)2CO3, NH4OH, CaCO3 used singly or in combination thereof. Washed precipitate is heated to a temperature in the range of 25 to 900°C to get the final product. The following examples are given hy way of illuslralion of Ihe process of Ihe prescnl invention and should not be construed lo limit the scope of Ihe invention. Example I 500 g of the raw latlerilic nickel ore containing Ni in. Ihe range of 0.6-0.7% was taken and digested with triaeid mixture of HCI,H2SO4 and HNO3 Traces of organic acid was added to it and the entire mixture was digested for a definite period of lime al a particular temperature. The digested mixture was cooled and filtered. The filtrate was made lo a definite volume , analysed for Ni, Co, Cr and Fe and retained for next operation. The residue was dried and analysed for Ni, Co, Cr and Fc. The experimental details are given below. Experimental details Name of the ore I -alcrilic nickel ore Origin of the ore Sukinda Weight of the ore (g) 500 Volume of MCI (ml) 50 Volume of H2SO4 (ml) 100 Volume of UNO., (ml) 50 Volume of H20 (ml) 500 Leaching time 5 Final leach liquor volume (ml) 2000 Mealing clelails Open hot plate, occasional stirring, 70- 80ºC' The filtrate obtained in the digestion is analysed for Ni, Co, (V and Fc using aloinic absorption speclrometlric melliod.s. Calculations have been done on gpl basis in the leach liquor as well as on pcrcenlage basis with respect to the ore. Chemical analysis of'leach liquor (Total volume 2000 ml) Wt% gpl Ni 0.6 1.5 Co 0.03 0.075 Cr 0.49 1.22 Fe I5.68 39.2 Chemical analysis of residue obtained from leach liquor Alxnil 1 g of the residue was completely taken into the solution using normal triaeid HCI- HNO3-HCIO4 digestion technique. The solution was made to a definite volume and analysed for Ni, Co, Cr and Fe using atomic absorption speclromelric methods. The results are given below. Ni (%) 0.16 Co(%) 0.006 Cr(%) 0.25 Fe (%) 5.75 Filtrate obtained from the digestion of the raw ore is subjected to precipitation using neutralising agent Na2CO3. The details are given below. Precipitation details Volume of leach liquor (nil) 1990 Weight of . 292 Na2C03 (g) Volume of filtrate (ml) 7500 Weight of the product (g) I 12.46 The precipilatte so obtained is thoroughly washed, healed al 900º C and analysed for Ni, Co, Cr and Fc by atomic absorption speclromelric techniques. The result as are given below. Chemical analysis of the product: Element (%) Enrichment factor Ni 1.95 3.25 Co 0.11 3.67 Cr 2.56 5.22 Fe 68.32 4.36 Given below is the analysis of product as oxide Complete analysis of the product as oxide: % Fe2O, 97.6 NiO 1.27 Cr2O3 3.74 CoO 0.14 Example II 500 g of the raw latlerilic nickel ore containing nickel in Ihe range of 0.6-0,7% was laken and digested with triacid inixlure of HCI, H2SO4 and HNO3. Traces of organic acid was added to it and the entire mixture was digested for a definite period of 'time at a parrlicular temperature. The digested mixture was cooled and filtered. The filtrate was made to a definite volume , analysed for Ni, Co, Cr and Pe and retained for nex-H operation. The residue was dried and analysed lor Ni, Co, Cr and Fc. The experimental details are given below. Experimental details Name of the ore Lalerilic nickel ore Origin of the ore Sukinda Weight of the ore (g) 500 Volume of HCI (ml) 50 Volume of H2SO4 (ml) 100 Volume of HNO3 (ml) 50 Volume of H20 (ml) 500 Leaching time (hr) 3 Final leach liquor volume (ml) 2000 Heating details Reflux at 100ºC The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fe using atomic absorption speclrometlric methods. Calculations have been done on gpl basis in the leach liquor as well as on percentage basis with respect to the ore. Chemical analysis of leach liquor (Total volume 2000 ml) Wl % gpl Ni(%) 0.59 1.47 Co(%) 0.03 0.075 Cr (%) 0.27 0.675 Fc(%) 16.13 40.32 Chemical analysis of residue obtained from leach liquor About I g of the residue was completely taken into the solution using normal iriacid HCI HNO3-HClO4 digestion technique. The solution was made lo a definite volume and analysed for Ni. Co, Cr and Fe using atomic absorption spectrometric methods. The results are given below. Ni (%) 0.19 Co (%) 0.009 Cr (%) 0.29 Fc(%) 5.25 Filtrate obtained from (he digestion of the raw ore is subjected to precipitation using neutralising agent Na2CO3. The details are given below. Precipitation details Volume of leach liquor (ml) 1990 Weight of Na2CO3 (g) 327 Volume of filtrate (ml) 4250 Weight of the product (g) 129.79 The precipitate so obtained is thoroughly washed, heated at 900ºC and analysed for Ni, Co, Cr and Fc by atomic absorption speclromclric techniques. The resultas are given below. Chemical analysis of the product: Element (%) Enrichment factor Ni 2.7 4.58 Co 0.12 Cr 1.6 5.92 F'c 58.77 3.64 Given below is the analysis of product as oxide Complete analysis of the product as oxide: % Fe2O., 83.96 NiO 3.43 Cr2O3 2..34 CoO 0.15 Example III 500 g of the raw lalteritic nickel ore containing nickel 0.6-0.7 was taken and digested with triacid mixture of HCI, H2SO4 and HNO3. Traces of organic acid was added to it and the entire mixture was digested for a definite period of lime at a parrlicular temperature. The digested mixture was cooled and filtered. The fillrale was made to a definite volume , analysed for Ni, Co, Cr and Fe and retained for next operation. The residue was dried and analysed for Ni, Co, Cr and Fc. The experimental details arc given below. lixperimenlal details Name of the ore Lalerilic nickel ore Origin of the ore Sukinda Weight of the ore (g) 500 Volume of MCI (ml) . 50 Volume of H2SO4(ml) 100 Volume of MNO3 (ml) 50 Volume of M2O (ml) 500 Leaehing lime (hr) 3 Final leaeh liquor volume (ml) 2000 Heating details oxalie aeicl 10 g, Reflux at 100C The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fc using atomic absorption speclroinctliic methods. Calculations have been done on gpl basis in the leac liquor as well as on percentage basis with respect to the ore. Chemical analysis of leach liquor (Tola! volume 2000 ml) Wl% gpl Ni (%) 0.57 1.425 Co(%) 0.03 0.075 Cr(%) 0.42 1.05 Fe(%) M.78 -U).«)5 About I g of the residue was completely taken into the solution using normal triacid HCI-HNO3-HCIO4 cligeslion technique. The solulion was made to a definite volume and analysed for Ni, Co, Grand Fc using atomic ahsorplion spectrometric methods. The results are given below. Chemical analysis of residue obtained from leach liquor Ni (%) 0.17 Co(%) 0.007 Cr(%) 0.46 Fe (%) 5..37 Precipitation details: Volume of leach liquor (F,) (ml) I WO Weight of Na2CO3(g) 330 Volume of filtrale (F2) (ml) 2000 Weight of the product (P) (g) 120.19 The precipitate so obtained is thoroughly washed, healed at 900°C and analysed for Ni, Co, Cr and Fc by atomic absorption spcctromclric techniques. The resullas are given below. Chemical analysis of lite product: Element (%) Enrich men t factor Ni 2.44 4.28 Co 0.13 4.33 Cr 2.13 5.07 Fc 64.% 4.39 Given below is the analysis of product as oxide Complete analysis of the product as oxide: % Fe2O3 92.8 NiO 3.10 Cr2O3 3.11 CoO 0.16 The main advantages ollhe process of lhe present invenlion are: 1. The invenlion requires very low energy in comparison lo llie existing ones which are energy intensive processes. 2. The invention is operator friendly. All the reagents used are non toxic in nature whereas existing processes deal with toxic reagents like,H2S, CO etc.. 3. The invention involves simple operations, llssentially it consists ol' precipitation and filtration. The engineering involved in sealing up operation will he simple and less expensive. 4. The invention is eco-lriendly. The residues and nitrates may he conveniently used as useful hy-produts. The disposed effluents will not pose any threat to the environment. 5. The invention as a whole is a cost effective one in comparison lo other existing nickel extraction processes from both energy and reagent consideration. 6. The invention may he used for enrichment of ores as low as 0.1 % of nickel. 7. The invention may he used for ores of even higher concentration of nickel. We claim : 1. An eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products which comprises: (a) leaching lateritic nickel ore with mineral acid such as herein described and traces of organic acid such as herein described followed by filtration; (b) heating the filtrate obtained in step (a) to boiling, adding neutralising agent to the boiling filtrate till the pH of the filtrate is in the range of 6-10 followed by filtration; (c) washing the precipitate obtained in step (b) thoroughly with water; (d) heating the washed precipitate so obtained in step (c) at a temperasture of 25 to 900°C, (e) if required, to get the mixed oxide of iron, nickel, chromium & cobalt. 2. An eco-friendly process as claimed in claim I wherein lateritic nickel ore is used such as having nickel concentration 0.1% and above. 3. An eco-friendly process as claimed in claims 1 to 2 wherein concentrated mineral acids used for leaching lateritic nickel ores are such as H2SO4, HCI, HNO3, H3PO4 singly or in combination thereof. 4 An eco-friendly process as claimed in claims 1 lo 3 wherein organic acids such as oxalic acid, tartaric acid, ascorbic acid are used as solids in traces in the range of 1:50 with respect lo the lateritic nickel ore for leaching lateritic nickel ores. 5. An eco-friendly process as claimed in claims 1-4 wherein neutralizing agents used are CaCO4, (NH4)2CO4, Na2CO4, NaOH, NH4OH or mixtures thereof. 6. An eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products substantially as herein described with reference to the examples.

Full Text

This invention relates to an eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products.
The end product produced by the process of the present invention will be a mixed oxide of iron, nickel, chromium and cobalt. This may be used as raw material for making ferro-nickel and/or stainless steel. The end product may also be used for making soft magnets.
The first commercially known process for the extraction of nickel from lateritic nickel ore was commisioned by the Freeport Sulfur Company. They had access to a huge reserve of lateritic nickel ore containing Though Freeport succeeded in producing nickel under trying conditions, the process was not economically competitive primarily due to poor metal extraction.
Though initial exploits of Freeport Sulfur did not succeed to the extent it was desired to be, they came up with a better process in 1957. Lateritic nickel ore containing nickel
extracted as sull'nde by H2S precipilalion. This is also known as Freeport Moa Bay process.
Moa Bay process has several advantages but the primary constarint is that it is an energy intensive process. Moa Bay project in Cuba was abandoned in 1959 even before the plant was actually operative.
Falconbridge process is an another established process which is relatively recent and where lateritic nickel ore is directly used for making ferro-nickel through reduction roasting followed by electric furnace smelting.
Falconbridge process enjoys certain advantages in its concept as well as regarding the direct relevance of its end product. However, the process is energy intensive.
Given below arc some of the imporatanl known processes for the extraction of nickel from laterilic ores. However, most of them have not yet been commercially exploited.
In patent no. US4125588, 1977, a methodd has been given for the recovery of nickel and magnesia from laleritcs using; Low temperature sulfalion.
In patent no, US 41959865, 1978, a process has been described lor the selective reduction of nickel lateritic ores for the extraction of non-ferrous metals.

In patent no. US430I 125, 1977, a melhod has been given for the exlraclion of Ni from pre-reduced laterilic ores with aqueous sull'iiric acid inthe presence of peroxidanls.
In patent no. US4311520, a process has been given for Ihe recovery of nickel, cobalt and manganese from their oxides and silicates.
In patent no. GB2086872A, 1981 acid leaching of lalerilic nickel ores have been described.
Acid leaching of nickel from serpentinic lalerilc ores have been described in palent no. US44I0498, 1980.
A method of liberating nickel and cobalt from laleriles using high pressure acid leaching has been given in patent nos. US454I994, 1983 and US454I868, 1983, US4548794, 1983.
All these processes are essentially extraction processes for nickel and oilier valuable metals from lalcrilic nickel ore. Enrichment of metal values in (he lalerilic ore may be a part of these processes, as normal exlarclion processes are no! commercially viable unless the starling material is enriched to some exlenl. However, il was not possible lo gel explicit access lo. such information . The common enrichment processes include physical bencficiation through floatation, magnetic separation, hand picking etc. Under

normal cicumstances these methods have not been round to be very efficient for ores of' very lean nature like lalerilie nickel ore.
Available processes all deal with lalerilie ores having nickel concentration more than 1%. Existing processes arc generally energy intensive processes.
Existing processes generate huge quantity of residues and wastes which are not environment friendly and cause serious disposal problems.
Existing processes arc not operator friendly and involve toxic reagents like hydrogen sulfide, carbon monoxide etc.
Lalerilie nickel ores, especially (hose of Indian origin, are by nature lean ores. Available processes mostly deal with ores in which nickel content is morethan 1%. India has a huge reserve of latcrUic nickel ores. But unfortunately, the average nickel concentration in that lies between 0.4-0.6%. Presently, there is no available method nationally or internationally lo process nickel ores of such a low grade.
Therefor R&D efforts have been made lo develop a process which can enrich lalerilie nickel ores having nickel content less than 1% and produce less pollution.

The main objective of the present invention is to provide an cco-friendly process for the enrichment of nickel, cobalt and iron contents in lalerilic nickel ores useful for the production of value added nickcli-ferrous products.
Another objective of.the proposed invention is to provide an improved process for the enrichment of nickel, cobalt and iron content of lalerilic nickel ores having nickel concentration less than 1%, whereby making it useful for value added nickcli-ferrous products.
Yel another objective of the present invention is to provide an improved process for the enrichment of nickel, cobalt and iron content of lalerilic nickel ores and thereby reducing environmental pollution and operational hazards.
In the process of the present invention, the metal components of the raw ore are taken in the solution by atmospheric acid leaching using a mineral acids and (races of organic-acids. Latcrilic nickel ores ar basically oxitles of iron where Ni is embedded in the Goelhile structure. Under reducing conditions the dissolution is belter though prior to that opening of the matrix is necessary. HNO3 and H2SO4 help in opening up Ihe matrix. Presence of H2SO4 causes sulfalion and supplies energy for that by reacting vvilh waler.

The leach liquor contains sulfate, chloride and nitrate solutions of nickel, iron, cobalt and other soluble metals. The iron, nickel and cobalt components are precipitated as corresponding hydroxides using sodium carbonate as a precipitant at pH higher than 10. To complete the precipitation, af pellets of NaOH is added finally. The chemical reactions that take place are,
(Equation Removed)
The precipitate is heated at 900ºC to make the corresponding oxides. The reactions that take place are,
(Equation Removed)

Accordingly, the present invention provides an eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products which comprises:
(a) leaching lateritic nickel ore with mineral acid such as herein described
and traces of organic acid such as herein described followed by
filtration;
(b) heating the filtrate obtained in step (a) to boiling, adding neutralising
agent to the boiling filtrate till the pH of the filtrate is in the range of 6-
10 followed by filtration;
(c) washing the precipitate obtained in step (b) thoroughly with water;
(d) heating the washed precipitate so obtained in step (c) at a temperature
of 25 to 900°C if required, to get the mixed oxide of iron, nickel,
chromium & cobalt.
According to a feature of the invention, lateritic nickel ores used may be selected from Ni:0.1% and above. Mineral acids used for leaching lateritic nickel ore may be such as H2SO4, HCI, HNO3, H3PO4 singly or in combination thereof. Traces of organic acids used for leaching lateritic nickel ore may be such as oxalic acid, tartaric acid, ascorbic acid singly or in combination thereof.
According to another feature of the invention, for effecting precipitation in The leach liquor, a number of neutralising agents used may be such as Na2CO3, (NH4)2CO3, NH4OH, CaCO3 used singly or in combination thereof. Washed precipitate is heated to a temperature in the range of 25 to 900°C to get the final product.

The following examples are given hy way of illuslralion of Ihe process of Ihe prescnl invention and should not be construed lo limit the scope of Ihe invention.
Example I
500 g of the raw latlerilic nickel ore containing Ni in. Ihe range of 0.6-0.7% was taken and digested with triaeid mixture of HCI,H2SO4 and HNO3 Traces of organic acid was added to it and the entire mixture was digested for a definite period of lime al a particular temperature. The digested mixture was cooled and filtered. The filtrate was made lo a definite volume , analysed for Ni, Co, Cr and Fe and retained for next operation. The residue was dried and analysed for Ni, Co, Cr and Fc. The experimental details are given below.
Experimental details
Name of the ore I -alcrilic nickel ore
Origin of the ore Sukinda
Weight of the ore (g) 500
Volume of MCI (ml) 50
Volume of H2SO4 (ml) 100
Volume of UNO., (ml) 50
Volume of H20 (ml) 500
Leaching time 5
Final leach liquor volume (ml) 2000

Mealing clelails Open hot plate, occasional stirring, 70-
80ºC'
The filtrate obtained in the digestion is analysed for Ni, Co, (V and Fc using aloinic absorption speclrometlric melliod.s. Calculations have been done on gpl basis in the leach liquor as well as on pcrcenlage basis with respect to the ore. Chemical analysis of'leach liquor (Total volume 2000 ml)
Wt% gpl
Ni 0.6 1.5
Co 0.03 0.075
Cr 0.49 1.22
Fe I5.68 39.2
Chemical analysis of residue obtained from leach liquor
Alxnil 1 g of the residue was completely taken into the solution using normal triaeid HCI-
HNO3-HCIO4 digestion technique. The solution was made to a definite volume and
analysed for Ni, Co, Cr and Fe using atomic absorption speclromelric methods. The
results are given below.
Ni (%) 0.16
Co(%) 0.006
Cr(%) 0.25
Fe (%) 5.75

Filtrate obtained from the digestion of the raw ore is subjected to precipitation using
neutralising agent Na2CO3. The details are given below.
Precipitation details
Volume of leach liquor (nil) 1990
Weight of . 292
Na2C03 (g)
Volume of filtrate (ml) 7500
Weight of the product (g) I 12.46
The precipilatte so obtained is thoroughly washed, healed al 900º C and analysed for Ni,
Co, Cr and Fc by atomic absorption speclromelric techniques. The result as are given
below.
Chemical analysis of the product:
Element (%) Enrichment factor
Ni 1.95 3.25
Co 0.11 3.67
Cr 2.56 5.22
Fe 68.32 4.36
Given below is the analysis of product as oxide Complete analysis of the product as oxide:
%

Fe2O, 97.6
NiO 1.27
Cr2O3 3.74
CoO 0.14
Example II
500 g of the raw latlerilic nickel ore containing nickel in Ihe range of 0.6-0,7% was laken and digested with triacid inixlure of HCI, H2SO4 and HNO3. Traces of organic acid was added to it and the entire mixture was digested for a definite period of 'time at a parrlicular temperature. The digested mixture was cooled and filtered. The filtrate was made to a definite volume , analysed for Ni, Co, Cr and Pe and retained for nex-H operation. The residue was dried and analysed lor Ni, Co, Cr and Fc. The experimental details are given below.
Experimental details
Name of the ore Lalerilic nickel ore
Origin of the ore Sukinda
Weight of the ore (g) 500
Volume of HCI (ml) 50
Volume of H2SO4 (ml) 100
Volume of HNO3 (ml) 50
Volume of H20 (ml) 500

Leaching time (hr) 3
Final leach liquor volume (ml) 2000
Heating details Reflux at 100ºC
The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fe using atomic absorption speclrometlric methods. Calculations have been done on gpl basis in the leach liquor as well as on percentage basis with respect to the ore.
Chemical analysis of leach liquor (Total volume 2000 ml)
Wl % gpl
Ni(%) 0.59 1.47
Co(%) 0.03 0.075
Cr (%) 0.27 0.675
Fc(%) 16.13 40.32
Chemical analysis of residue obtained from leach liquor
About I g of the residue was completely taken into the solution using normal iriacid HCI HNO3-HClO4 digestion technique. The solution was made lo a definite volume and analysed for Ni. Co, Cr and Fe using atomic absorption spectrometric methods. The results are given below.

Ni (%) 0.19
Co (%) 0.009
Cr (%) 0.29
Fc(%) 5.25
Filtrate obtained from (he digestion of the raw ore is subjected to precipitation using
neutralising agent Na2CO3. The details are given below.
Precipitation details
Volume of leach liquor (ml) 1990
Weight of Na2CO3 (g) 327
Volume of filtrate (ml) 4250
Weight of the product (g) 129.79
The precipitate so obtained is thoroughly washed, heated at 900ºC and analysed for Ni,
Co, Cr and Fc by atomic absorption speclromclric techniques. The resultas are given
below.
Chemical analysis of the product:
Element (%) Enrichment factor
Ni 2.7 4.58
Co 0.12 Cr 1.6 5.92

F'c 58.77 3.64
Given below is the analysis of product as oxide Complete analysis of the product as oxide:
%
Fe2O., 83.96
NiO 3.43
Cr2O3 2..34
CoO 0.15
Example III
500 g of the raw lalteritic nickel ore containing nickel 0.6-0.7 was taken and digested with triacid mixture of HCI, H2SO4 and HNO3. Traces of organic acid was added to it and the entire mixture was digested for a definite period of lime at a parrlicular temperature. The digested mixture was cooled and filtered. The fillrale was made to a definite volume , analysed for Ni, Co, Cr and Fe and retained for next operation. The residue was dried and analysed for Ni, Co, Cr and Fc. The experimental details arc given below.

lixperimenlal details
Name of the ore Lalerilic nickel ore
Origin of the ore Sukinda
Weight of the ore (g) 500
Volume of MCI (ml) . 50
Volume of H2SO4(ml) 100
Volume of MNO3 (ml) 50
Volume of M2O (ml) 500
Leaehing lime (hr) 3
Final leaeh liquor volume (ml) 2000
Heating details oxalie aeicl 10 g, Reflux at 100C
The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fc using atomic absorption speclroinctliic methods. Calculations have been done on gpl basis in the leac liquor as well as on percentage basis with respect to the ore. Chemical analysis of leach liquor (Tola! volume 2000 ml)
Wl% gpl
Ni (%) 0.57 1.425
Co(%) 0.03 0.075
Cr(%) 0.42 1.05
Fe(%) M.78 -U).«)5

About I g of the residue was completely taken into the solution using normal triacid HCI-HNO3-HCIO4 cligeslion technique. The solulion was made to a definite volume and analysed for Ni, Co, Grand Fc using atomic ahsorplion spectrometric methods. The results are given below. Chemical analysis of residue obtained from leach liquor
Ni (%) 0.17
Co(%) 0.007
Cr(%) 0.46
Fe (%) 5..37
Precipitation details:
Volume of leach liquor (F,) (ml) I WO
Weight of Na2CO3(g) 330
Volume of filtrale (F2) (ml) 2000
Weight of the product (P) (g) 120.19
The precipitate so obtained is thoroughly washed, healed at 900°C and analysed for Ni, Co, Cr and Fc by atomic absorption spcctromclric techniques. The resullas are given below.

Chemical analysis of lite product:
Element (%) Enrich men t factor
Ni 2.44 4.28
Co 0.13 4.33
Cr 2.13 5.07
Fc 64.% 4.39
Given below is the analysis of product as oxide Complete analysis of the product as oxide:
%
Fe2O3 92.8
NiO 3.10
Cr2O3 3.11
CoO 0.16

The main advantages ollhe process of lhe present invenlion are:
1. The invenlion requires very low energy in comparison lo llie existing ones which
are energy intensive processes.
2. The invention is operator friendly. All the reagents used are non toxic in nature
whereas existing processes deal with toxic reagents like,H2S, CO etc..
3. The invention involves simple operations, llssentially it consists ol' precipitation
and filtration. The engineering involved in sealing up operation will he simple and
less expensive.
4. The invention is eco-lriendly. The residues and nitrates may he conveniently used
as useful hy-produts. The disposed effluents will not pose any threat to the
environment.
5. The invention as a whole is a cost effective one in comparison lo other existing
nickel extraction processes from both energy and reagent consideration.
6. The invention may he used for enrichment of ores as low as 0.1 % of nickel.
7. The invention may he used for ores of even higher concentration of nickel.

We claim :
1. An eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products which comprises:
(a) leaching lateritic nickel ore with mineral acid such as herein
described and traces of organic acid such as herein described
followed by filtration;
(b) heating the filtrate obtained in step (a) to boiling, adding
neutralising agent to the boiling filtrate till the pH of the filtrate is in
the range of 6-10 followed by filtration;
(c) washing the precipitate obtained in step (b) thoroughly with water;
(d) heating the washed precipitate so obtained in step (c) at a
temperasture of 25 to 900°C,
(e) if required, to get the mixed oxide of iron, nickel, chromium &
cobalt.
2. An eco-friendly process as claimed in claim I wherein lateritic nickel ore is
used such as having nickel concentration 0.1% and above.
3. An eco-friendly process as claimed in claims 1 to 2 wherein concentrated
mineral acids used for leaching lateritic nickel ores are such as H2SO4, HCI,
HNO3, H3PO4 singly or in combination thereof.
4 An eco-friendly process as claimed in claims 1 lo 3 wherein organic acids
such as oxalic acid, tartaric acid, ascorbic acid are used as solids in traces in

the range of 1:50 with respect lo the lateritic nickel ore for leaching lateritic nickel ores.
5. An eco-friendly process as claimed in claims 1-4 wherein neutralizing agents used are CaCO4, (NH4)2CO4, Na2CO4, NaOH, NH4OH or mixtures thereof.
6. An eco-friendly process for the preparation of mixed oxide of iron, nickel, chromium & cobalt useful for the production of value added nickel-ferrous products substantially as herein described with reference to the examples.

Documents:

3510-del-1997-abstract.pdf

3510-del-1997-claims.pdf

3510-del-1997-correspondence-others.pdf

3510-del-1997-correspondence-po.pdf

3510-del-1997-description (complete).pdf

3510-del-1997-form-1.pdf

3510-del-1997-form-19.pdf

3510-del-1997-form-2.pdf

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Patent Number

232753

Indian Patent Application Number

3510/DEL/1997

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

21-Mar-2009

Date of Filing

08-Dec-1997

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	SANTANU BHATTACHARJEE	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
2	SUNANDA GHOSAL	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
3	PRANAB DASGUPTA	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
4	KALYAN KUMAR GUPTA	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
5	RABINDRA NATH BHATTACHARJEE	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
6	ADHIR RANJAN PAUL	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
7	SWAPAN CHATTERJEE	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
8	VENKATESH RAO	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
9	LALLAN PRASAD PANDEY	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.
10	PATCHA RAMACHANDRA RAO	NATIONAL METALLURGICAL LABORATORY JAMSHED PUR, BIHAR, INDIA.

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