Title of Invention	AN IMPROVED PROCESS FOR THE EXTRACTION OF NICKEL, COBALT AND IRON FROM LATERITIC NICKEL ORES.
Abstract	An improved process for the extraction of nickel, cobalt and iron from the lateritic nickel ores which comprises: (a) leaching lateritic nickel are with mineral acid and traces of organic acid followed by filtration; (b) heating the filtrate obtained in step (a) to boiling, adding neutralizing agent to the boiling filtrate to separate iron as precipitate; (c) adding strong oxidizing agent to the filtrate obtained in step (b) to raise the pH of the filtrate in the range of 3 to 4, adding oxidizing acids to lower the pH below 0.7, followed by addition of neutralizing agent to the mixture to raise the pH in the range of 2.7 - 3, filtering the resultant mixture to separate cobalt as precipitate; (d) adding neutralizing agent to the filtrate obtained in step (e) till the pH is in the range of 8 to 10 followed by filtration to obtain nickel as precipitate.

Title of Invention

AN IMPROVED PROCESS FOR THE EXTRACTION OF NICKEL, COBALT AND IRON FROM LATERITIC NICKEL ORES.

Abstract

An improved process for the extraction of nickel, cobalt and iron from the lateritic nickel ores which comprises: (a) leaching lateritic nickel are with mineral acid and traces of organic acid followed by filtration; (b) heating the filtrate obtained in step (a) to boiling, adding neutralizing agent to the boiling filtrate to separate iron as precipitate; (c) adding strong oxidizing agent to the filtrate obtained in step (b) to raise the pH of the filtrate in the range of 3 to 4, adding oxidizing acids to lower the pH below 0.7, followed by addition of neutralizing agent to the mixture to raise the pH in the range of 2.7 - 3, filtering the resultant mixture to separate cobalt as precipitate; (d) adding neutralizing agent to the filtrate obtained in step (e) till the pH is in the range of 8 to 10 followed by filtration to obtain nickel as precipitate.

Full Text	An improved process for the extraction of nickel, cobalt and iron from laterite nickel ores. Lateritic nickel ore contains primarily nickel, cobalt iron and chromium. The present invention will separate the iron, nickel and cobalt components in directly usable forms. Iron will be available as iron (III) sulphate as solution or hydroxide/oxide form Ferric sulphate may be used as a starting material for making electrolytic iron powder, ferrites and several other value added iron compounds, namely, ferric oxalate, ferric stearate etc. Nickel will be obtained as hydroxides. This may conveniently be used for making either nickel metal or nickel sulfate. Cobalt will be obtained as cobalt (III) hydroxides. This may conveniently be used for making cobalt metal or cobalt sulfate. The first commercial process for the extraction of nickel from lateritic nickel ore was commissioned by the Freeport Sulfur Company. They had access to a huge reserve of iateritic nickel ore containing Though initial exploits of Freeport Sulfur did not succeed to the extent it was desired to be, they same up with a better process in 1957. lateritic nickel ore containing nickel Moa Bay Process has several advantages but the primary constraint 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 relatively recent where lateritic nickel ore is directly used for making ferro-nickel through reduction roasting followed by electric furnace smelting. Falcon bridge 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 are some of the important processes for the extraction of nickel from lateritic ores. However most of them have not yet been commercially exploited. In patent No. US4125588, 1977 a method has been given for the recovery of nickel and magnesia from laterites using low temperature sulfation. In patent No. US 41959865. 1978, a process has been described for the selective reduction of nickel lateritic ores for the extraction of non-ferrous metals. In patent No. US4301125, 1977, a method has been given for the extraction of Ni from pre-reduced lateritic ores with aqueous sulfuric aid in the presence of peroxidants. In Patent No. US4311520, a process has been given for the recovery of nickel, cobalt and manganese from their oxides and silicates. In Patent No. GB 2086872A, 181, acid leaching of lateritic nickel ores have been described. Acid leaching of nickel from serpentinic laterite ores have been described in patent no. US4410498. 1980. A method of liberating nickel and cobalt from laterites using high presence acid leaching has been given in patent Nos. US4541994, 1983 and US4541868, 1983, US4548794 1983. Existing processes are 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 are not operator friendly and involves toxic reagents like hydrogen sulfide, carbon monoxide etc. Lateritic nickel ores, especially those of Indian origin, are by nature lean ores. Available processes mostly deal with ores in which nickel content is more than 1%. India has a huge reserve of lateritic nickel ores. But unfortunately, the average nickel concentration in that lies between 0.4-0.6%. Presently, there is no available method to process nickel ores of such a low grade. Therefore R&D efforts have been made to develop an improved process for the extraction of nickel, cobalt and iron from lateritic nickel ores. The main objective of the present invention is to provide an improved process for the extraction of nickel, cobalt and iron separately from the lateritic nickel ore. Another objective of the present invention is to provide an improved process for the extraction of nickel, cobalt and iron from lateritic nickel ore containing nickel 0.1% and above. Yet another objective of the present invention is to provide an improved process for the extraction of nickel, cobalt and iron from lateritic nickel ore in an eco friendly way, thereby reducing environment pollution and operational hazards. The metal components of the raw ore are taken in the solution by atmospheric acid leaching using mineral acids and traces of organic acids, lateritic nickel ores are basically oxides of iron where Ni is embedded in the Goethite structure. Under reducing conditions, the dissolution is better through prior to that opening of the matrix is necessary HNO3 and H2SO4 helps in opening up the matrix. Presence of H2S04 causes sulfation and supplies energy for that by reacting with water. The leach liquor contains sulfate, chloride and nitrate solutions of nickel, iron, cobalt an dother soluble metals, Iron is separated as hydroxide at pH 2.7 using suitable precipitants. Nickel and cobalt remain in the solution. The reactions that take place are, (Equation Removed) To the solution containing nickel and cobalt, a strong oxidising is an PH of the solution is raised in the range of 3-4. The solution is allowed to settle for some time after which the PH of the solution is slowly lowered below 0.7 by drop wise addition of an oxidising acid. The solution is further allowed to settle for some time and the PH of the solution is again raised to 3 by the addition of an appropriate neutralising agent. Co(II) is oxidised to CO(III) and precipitated as Co(III) hydroxide. A part of the nickel along sets oxidised to its higher oxidation states and converted to their hydroxides oxide out they are brought back to the solution by the addition of oxidising acid. Co(III) hydroxide is filtered and separated. The solution contains only nickel. The reactions that take place are (Equation Removed) To the nickel solution, Na2C03 is added followed by a few pellets of NaOH till the PH is in the range of 8-10 Nickel hydroxide is precipitated out. The reactions that take place are . (Equation Removed) Accordingly, the present invention provides improved process for the extraction of nickel, cobalt and iron from the lateritic nickel ores which comprises: (a) leaching lateritic nickel are with mineral acid and traces of organic acid followed by filtration; (b) heating the filtrate obtained in step (a) to boiling, adding neutralizing agent to the boiling filtrate to separate iron as precipitate; (c) adding strong oxidizing agent to the filtrate obtained in step (b) to raise the pH of the filtrate in the range of 3 to 4, adding oxidizing acids to lower the pH below 0.7, followed by addition of neutralizing agent to the mixture to raise the pH in the range of 2.7 - 3, filtering the resultant mixture to separate cobalt as precipitate; (d) adding neutralizing agent to the filtrate obtained in step (c) till the pH is in the range of 8 to 10 followed by filtration to obtain nickel as precipitate. The present invention provides an improved process for the extraction of nickel, cobalt and iron from the lateritic nickel ores which comprises. a) leaching lateritic nickel ore with mineral acid and traces of organic acid followed by filtration: b) heating the filtrate obtained in steel (a) to boiling, adding neutralising agent to the boiling filtrate till the pH of the filtrate is in the range of 2.5 to 3 followed by filtration so separate iron as precipitate. c) adding strong oxidising agent to the filtrate obtained in step (b) to raise the pH of filtrate in the range of 3 to 4, adding oxiding acids to lower the pH below 0.7, followed by addition of neutralising agent to the mixture to raise the pH in the range of 2.7-3 filtering the resultant mixture to separate cobalt as precipitate. d) adding neutralising agent to the filtrate obtained in step till the pH is in the range of 8 to 10 followed by filtration to obtain nickel as precipitate. 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, HC1, HNO3, H3PO4 singly or in combination thereof Traces of organic acids used for leaching lateritic nickel ore may be such as oxalic acid, trataric acid, ascorbic acid singly or in combination thereof. According to another feature of the invention, iron is separated from the filtrate using a suitable neutralising agent such as CaCO3, (NH4)2 CO3, Na2 CO3, NaOH, NH4OH According to yet another feature of the invention, strong oxidising agents may be used such as Ca(OCI)CI, Na(OCI), (NH4)2 S2O8, H2O2 According to still another feature of the invention, neutralising agent used for precipitating Ni may be used such as NaOH, Na2 CO3 , CaCO3, (NH4)2 CO3, NH4OH Strong oxidising acids used to lower the PH below 0.7 are such as HNO3 and HC1O4 Following examples are given by way of illustration of the process of the present invention and should not construed to limit the scope of the invention. Example 1 500 gm of the raw latteritic nickel are containing nickel int eh range of 0.6-0.7% was taken and digested with triacid mixture of HCI, H2SO4 and HNO3 . Traces of organic aid was added to it and the entire mixture was digested for a definite period of time at a particular temperature. The digested mixture was cooled and filtered. The filtrate was made to a definite volume, analysed for Ni, Co, Cr and Fe and retained for next operation. The residue ws dried and analysed for Ni, Co, Grand Fe. The experimental details are given below. Experimental details name of the ore Lateritic nickel ore origin of the ore Sukinda Weight of the ore (g) 500 Volume of HCL (ml) 50 Volume of H2,SO4 (ml) 100 Volume of HNO3 (ml) 50 Volume of H2O (ml) 700 Leaching time (hr) 6 Final leach liquor volume (ml) 3000 Heating details Open system. 100°C The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fe using atomic absorption spectromettric methods. Calculations have been done on gpl basis in the leach liquor as well as on percentage basis with respect to the ore. The results are given below Chemical analysis of the leach liquor Wt% gpl Ni 0.541 0.9 Co 0.031 0.05 Fe 10.3 17.17 Iron is separated from the leach liquor using CaCO3 as precipitant. Precipitant is added till the pH of the solution is raised to 2.7. Precipitated iron is separated by filtration precipitation details are given below : Precipitation details Volume of leach liquor (ml) 3000 Precipitation temperature °C 100 Amount of CaCo, (g) 270 Precipitation pH 2.7 Volume of filtrate 4000 The filtrate obtained after separating iron as precipitate is analysed for Ni. Co and Fe using atomic absorption spectrometric methods The results are given below Filtrate analysis Ni(gpl) 0.7 Co(gpl) 0.034 Fe(ppm) 4.85 To the filtrate, Ca(OCI) CI is added till the pH of the solution is raised to 4. An oxidising acid is added to it till the pH is brought down below 0.7. The pH is again raised by adding CaCo3 to 3. Co is separated as precipitate which is re-dissolved in dilute H2SO4/HCI for the purpose of analysis Ni, Co and Fe are analysed by atomic absorption spectrometric methods. The results are given below • analysis of cobalt concentrate (Total volume 250 ml) Ni(ppm) 482.95 Co(gpl) 0.45 Fe(ppm) trace The filtrate obtained after separating cobalt contains nickel which is precipitated using Na2C03 and NaOH until the pH of the solution is raised to 10. The nickel is filtered and separtd as precipitate and re-dissolved in H2SO4 / HC1 for chemical analysis Ni Co and Fe are analysed by atomic absorption spectrometric methods. Analysis of nickel concentrate (Total volume 250 ml) Ni(gpl) 11 Co(ppm) 63.9 Fe(ppm) 83 The filtrate obtained after separating Ni as precipitate is analysed for Ni. Co and Fe using atomic absorption spectrometric methods. The results are given below Residual filtrate analysis Ni(ppm) trace Co(ppm) trace Fe(ppm) trace EXPERIMENT II 500 gm of the raw lateritic nickel ore containing nickel in the range of 0.6-0.7 was taken and digested with triacid mixture of HC1, 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 particular temperature. The digested mixture was cooled and filtered. The filtrate was made to 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 Fe. The experiment details are given below. Experimental details Name of the ore Lateritic nickel ore Origin of the ORe Sukinda Weight of the Ore(g) 500 Volume of HCI(mi) Volume of H2SO4 (ml) 200 Volume of HNO3 (mi) Volume of H2O (ml) 200 Leaching time (hr) 1.5 Final leach liquor volume (ml) 2000 Heating details open system 100 °C The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fe using atomic absorption spectromeric methods. Calculations have been done on gpl basis in the leach liquor as well as on percentage basis with respect to the ore. The results are given below. Chemical analysis of the leach liquor Wt% gpl Ni 0.669 1.67 Co 0.033 0.08 Fe 19.71 49.27 Iron is separated from the leach liquor using CaCO3 as precipitant. Precipitant is added till the PH of the solution is raised to 2.7. Precipitated iron is separated by filtration Precipitation details are given below : Precipitation details volume of leach liquor (ml) 2000 Precipitation temperature, C 100 Amount of CaC03(g) 325 Precipitation Ph 2.7 Volume of filtrate 3000 The filtrate obtained after separating iron as precipitant is analysed for Ni, Co and Fe using atomic absorption spectrometric methods. The results are given below. Filtrate analysis Ni(gpl) 0.76 Co(gpl) 0.041 Fe(ppm) 1.1 To the filtrate Ca(OCl) Cl is added till the pH of the solution is raised to 4. An oxidising acid is added to it till the pH is brought down below 0.7. The pH is again raised by adding CaCO3 to 3. Co is separated as precipitate which is re-dissolved in dilute. H2SO4 / HCl/HNO3 for the purpose of analysis Ni, Co and Fe are analysed by atomic absorption spectrometric methods. The results are given below. Analysis of cobalt concentrate (Total volume 750ml) Ni(ppm) 121.16 Co(gpl) 0.058 Fe9ppm) 9.3 Analysis of residual filtrate The filtrate obtained after separating cobalt contains nickel which is precipitated using Na2CO3 and NaOH until the pH of the solution is raised to 10. The nickel is filtered and separated as precipitate and re-dissolved in H2S04 / HC1/HNO3 for chemical analysis Ni, Co and Fe are analysed by atomic absorption spectrometric methods. Results are given below. Analysis of the nickel concentrate (750 ml) Ni gpl 2.43 Co(ppm) 102.25 Fe(ppm) 1.08 The filtrate obtained after separating Ni as precipitate is analysed for Ni. Co and Fe using atomic absorption spectrometric methods. The results are given below. Residual filtrate analysis Ni (ppm) 7.83 Co(ppm) 0.244 Fe(ppm) not found Experiment III 500 g of the raw lateritic nickel are containing nickel in the range of 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 time at a particular temperature. The digested mixture was cooled and filtered. The filtrate 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 Fe. The experimental details are given below. Experimental details Name of the ore Lateritic nickel ore Origin of the ore Sukinda Weight of the ore(g) 500 Volume of HCI (ml) 50 Volume of H,SO4 (ml) 100 Volume of HNO3 (ml) 50 Volume of H2O (ml 700 Leaching time (hr) 6 Final leach liquor volume (ml) 3000 Heating details Open system 100°C The filtrate obtained in the digestion is analysed for Ni,Co, Cr and Fe using atomic absorption spectrometric methods. Calculations have been done on gpl basis in the leach liquor as well as on percentage basis with respect to the ore. The results are given below. Chemical analysis of the leach liquor wt% gpl Ni 0.81 1.35 Co 0.032 0.05 Fe 13.44 22.4 Iron is separated from the leach liquor using CaCO3 as precipitant. Precipitant is added till the pH of the solution is raised to 2.7. Precipitated iron is separated by filtration. Precipitation details are given below. Precipitation detail volume of leach liquor (ml) 3000 Precipitation temperature, C 100 Amount of CaCO3(g) 265 Precipitation pH 2.7 Volume of filtrate F2 3255 The filtrate obtained after separating iron as precipitate is analysed for Ni, Co and Fe using atomic absorption spectrometric methods. The results are given below. Filtrate analysis Ni(gpl) 1.121 Co(gpl) 0.052 Fe(ppm) not found To the filtrate, Ca(OCI) Cl is added till the PH of the solution is raised to 4. An oxidising acid is added to it till the pH is brought down below 0.7. The pH is again raised by adding CaCO3 to 3. Co is separated as precipitate which is re-dissolved in dilute H2SO4/HC1/HNO3 for the purpose of analysis, Ni, Co and Fe are analysed by atomic absorption spectrometric methods. The results are given below. Analysis of cobalt concentrate (Total volume 250 ml) Ni (ppm) 228.59 Co(gpl) 0.24 Fe(ppm) 0.63 The filtrate obtained after separating cobalt contains nickel which is precipitated using Na2CO3 and NaOH until the PH of the solution is raised to 10. The nickel is filtered and separated as precipitate and redissolved in H2SO4/HC1/HNO3 for chemical analysis. Ni Co and Fe are analysed by atomic absorption spectrometric methods. Results are given below. Analysis of nickel concentrate (Total volume 250 ml) Ni(gpl) 13.44 Co(ppm) 300 Fe (ppm) 25 The filtrate obtained after separating Ni as precipitate is analysed for Ni, Co and Fe using atomic absoiption spectrometric methods. The results are given below. Residual filtrate analysis Ni (ppm) trace Co(ppm) trace Fe(ppm) trace The main advantages of the process of the present invention are : 1. The invention requires very low energy in comparison to the existing ones 2. In the present invention, metallic values in the lateritic nickel ore are obtained in the separated form. 3. The present invention is eco-friendly and it does not pollute the environment. 4. The present invention is operator friendly as it does not involve any hazardous reagents. 5. The present invention may be used for the extraction of nickel from lateritic nickel ore containing Ni 0.1% and above. 6. The present invention may be used for extraction of nickel from lateritic nickel ore having even higher percentage of nickel. 7. The present invention is cost effective in comparison to other nickel extraction processes. 8. The present invention is cost effective in comparison to other existing nickel, cobalt and iron extraction processes. We claim: 1. An improved process for the extraction of nickel, cobalt and iron from lateritic nickel ores which comprises: (a) leaching laleritic nickel ore with mineral acid and traces of organic acid followed by filtration; (b) heating the filtrate obtained in step (a) to boiling, adding neutralising agent to the boiling filtrale till the pH of the filtrate is in the range of 2.5 to 3 followed by filllration to separate iron as precipilate; (c) adding strong oxidising agent to the fillrate obtained in step (b) lo raise the pM of the fillrale in the range of 3 lo 4, adding oxidising acids lo lower I.he pil below 0.7, followed by addition of neutralising agent lo the mixture lo raise the pi I in Ihe range of 2.7 lo 3, filtering (he resultant mixture to separate cobalt as precipitate; (d) adding neutralising agent to the fillrate obtained in slep (c) till the pH is in the range of 8 to 10 followed by filtration to obtain nickel as precipitate; 2. An improved process as claimed in claim I wherein lateritic nickel ore is used such as having nickel concentration less than 0.1% and above. 3. An improved process as claimed in claims I to2 wherein concentrated mineral acids used for leaching lalerilie nickel ores such as H2SO4, HCI, HNO3, H3PO4 singly or in combination thereof. 4. An improved process as claimed in claims I lo 3 wherein organic acids such as oxalic acid, larlaric acid, ascorbic acid are used as solids in traces in the range of 1:50 with respecl to the laleritic nickel ore for leaching lateritic nickel ores. 5. An improved process as claimed in claims I lo 4 wherein neutralising agents used are such as CaCO3, (NH4)2CO3 , Na2CO3 , NaOH, NH4OH or mixtures thereof. 6. An improved process as claimed in claims I to 5 wherein strong oxidising agents used are such as Ca(OCI)CI, Na(OCI), H2O2, (NH4)2S2O8. 7. An improved process as claimed in claims 1 lo 6 wherein oxidising acids used arc such as HNO3, HCIO4. 8. An improved process for the exlraclion of nickel, cobalt and iron from laleriiic nickel ores substantially as herein described wilh reference to the examples.

Full Text

An improved process for the extraction of nickel, cobalt and iron from laterite nickel ores.
Lateritic nickel ore contains primarily nickel, cobalt iron and chromium. The present invention will separate the iron, nickel and cobalt components in directly usable forms.
Iron will be available as iron (III) sulphate as solution or hydroxide/oxide form Ferric sulphate may be used as a starting material for making electrolytic iron powder, ferrites and several other value added iron compounds, namely, ferric oxalate, ferric stearate etc.
Nickel will be obtained as hydroxides. This may conveniently be used for making either nickel metal or nickel sulfate.
Cobalt will be obtained as cobalt (III) hydroxides. This may conveniently be used for making cobalt metal or cobalt sulfate.
The first commercial process for the extraction of nickel from lateritic nickel ore was commissioned by the Freeport Sulfur Company. They had access to a huge reserve of iateritic nickel ore containing Though initial exploits of Freeport Sulfur did not succeed to the extent it was desired to be, they same up with a better process in 1957. lateritic nickel ore containing nickel Moa Bay Process has several advantages but the primary constraint 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 relatively recent where lateritic nickel ore is directly used for making ferro-nickel through reduction roasting followed by electric furnace smelting.
Falcon bridge 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 are some of the important processes for the extraction of nickel from lateritic ores. However most of them have not yet been commercially exploited. In patent No.

US4125588, 1977 a method has been given for the recovery of nickel and magnesia from laterites using low temperature sulfation.
In patent No. US 41959865. 1978, a process has been described for the selective reduction of nickel lateritic ores for the extraction of non-ferrous metals.
In patent No. US4301125, 1977, a method has been given for the extraction of Ni from pre-reduced lateritic ores with aqueous sulfuric aid in the presence of peroxidants.
In Patent No. US4311520, a process has been given for the recovery of nickel, cobalt and manganese from their oxides and silicates.
In Patent No. GB 2086872A, 181, acid leaching of lateritic nickel ores have been described.
Acid leaching of nickel from serpentinic laterite ores have been described in patent no. US4410498. 1980.
A method of liberating nickel and cobalt from laterites using high presence acid leaching has been given in patent Nos. US4541994, 1983 and US4541868, 1983, US4548794 1983.
Existing processes are 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 are not operator friendly and involves toxic reagents like hydrogen sulfide, carbon monoxide etc.
Lateritic nickel ores, especially those of Indian origin, are by nature lean ores. Available processes mostly deal with ores in which nickel content is more than 1%. India has a huge reserve of lateritic nickel ores. But unfortunately, the average nickel concentration in that lies between 0.4-0.6%. Presently, there is no available method to process nickel ores of such a low grade.
Therefore R&D efforts have been made to develop an improved process for the extraction of nickel, cobalt and iron from lateritic nickel ores.
The main objective of the present invention is to provide an improved process for the extraction of nickel, cobalt and iron separately from the lateritic nickel ore.
Another objective of the present invention is to provide an improved process for the extraction of nickel, cobalt and iron from lateritic nickel ore containing nickel 0.1% and above.
Yet another objective of the present invention is to provide an improved process for the extraction of nickel, cobalt and iron from lateritic nickel ore in an eco friendly way, thereby reducing environment pollution and operational hazards.

The metal components of the raw ore are taken in the solution by atmospheric acid leaching using mineral acids and traces of organic acids, lateritic nickel ores are basically oxides of iron where Ni is embedded in the Goethite structure. Under reducing conditions, the dissolution is better through prior to that opening of the matrix is necessary HNO3 and H2SO4 helps in opening up the matrix. Presence of H2S04 causes sulfation and supplies energy for that by reacting with water.
The leach liquor contains sulfate, chloride and nitrate solutions of nickel, iron, cobalt an dother soluble metals, Iron is separated as hydroxide at pH 2.7 using suitable precipitants. Nickel and cobalt remain in the solution. The reactions that take place are,
(Equation Removed)
To the solution containing nickel and cobalt, a strong oxidising is an PH of the solution is raised in the range of 3-4. The solution is allowed to settle for some time after which the PH of the solution is slowly lowered below 0.7 by drop wise addition of an oxidising acid. The solution is further allowed to settle for some time and the PH of the solution is again raised to 3 by the addition of an appropriate neutralising agent. Co(II) is oxidised to CO(III) and precipitated as Co(III) hydroxide. A part of the nickel along sets oxidised to its higher oxidation states and converted to their hydroxides oxide out they are brought back to the solution by the addition of oxidising acid. Co(III) hydroxide is filtered and separated. The solution contains only nickel. The reactions that take place are
(Equation Removed)
To the nickel solution, Na2C03 is added followed by a few pellets of NaOH till the PH is in the range of 8-10 Nickel hydroxide is precipitated out. The reactions that take place are .
(Equation Removed)
Accordingly, the present invention provides improved process for the extraction of nickel, cobalt and iron from the lateritic nickel ores which comprises:
(a) leaching lateritic nickel are with mineral acid and traces of organic acid followed by filtration;

(b) heating the filtrate obtained in step (a) to boiling, adding neutralizing agent to the boiling
filtrate to separate iron as precipitate;
(c) adding strong oxidizing agent to the filtrate obtained in step (b) to raise the pH of the
filtrate in the range of 3 to 4, adding oxidizing acids to lower the pH below 0.7, followed
by addition of neutralizing agent to the mixture to raise the pH in the range of 2.7 - 3,
filtering the resultant mixture to separate cobalt as precipitate;
(d) adding neutralizing agent to the filtrate obtained in step (c) till the pH is in the range of 8
to 10 followed by filtration to obtain nickel as precipitate.
The present invention provides an improved process for the extraction of nickel, cobalt and iron from the lateritic nickel ores which comprises.
a) leaching lateritic nickel ore with mineral acid and traces of organic acid followed by
filtration:
b) heating the filtrate obtained in steel (a) to boiling, adding neutralising agent to the boiling
filtrate till the pH of the filtrate is in the range of 2.5 to 3 followed by filtration so separate
iron as precipitate.
c) adding strong oxidising agent to the filtrate obtained in step (b) to raise the pH of filtrate in
the range of 3 to 4, adding oxiding acids to lower the pH below 0.7, followed by addition of
neutralising agent to the mixture to raise the pH in the range of 2.7-3 filtering the resultant
mixture to separate cobalt as precipitate.
d) adding neutralising agent to the filtrate obtained in step till the pH is in the range of 8 to 10
followed by filtration to obtain nickel as precipitate.
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, HC1, HNO3, H3PO4 singly or in combination thereof Traces of organic acids used for leaching lateritic nickel ore may be such as oxalic acid, trataric acid, ascorbic acid singly or in combination thereof.
According to another feature of the invention, iron is separated from the filtrate using a suitable neutralising agent such as CaCO3, (NH4)2 CO3, Na2 CO3, NaOH, NH4OH
According to yet another feature of the invention, strong oxidising agents may be used such as Ca(OCI)CI, Na(OCI), (NH4)2 S2O8, H2O2

According to still another feature of the invention, neutralising agent used for precipitating Ni may be used such as NaOH, Na2 CO3 , CaCO3, (NH4)2 CO3, NH4OH
Strong oxidising acids used to lower the PH below 0.7 are such as HNO3 and HC1O4 Following examples are given by way of illustration of the process of the present invention and should not construed to limit the scope of the invention. Example 1
500 gm of the raw latteritic nickel are containing nickel int eh range of 0.6-0.7% was taken and digested with triacid mixture of HCI, H2SO4 and HNO3 . Traces of organic aid was added to it and the entire mixture was digested for a definite period of time at a particular temperature. The digested mixture was cooled and filtered. The filtrate was made to a definite volume, analysed for Ni, Co, Cr and Fe and retained for next operation. The residue ws dried and analysed for Ni, Co, Grand Fe. The experimental details are given below. Experimental details
name of the ore Lateritic nickel ore
origin of the ore Sukinda
Weight of the ore (g) 500
Volume of HCL (ml) 50
Volume of H2,SO4 (ml) 100
Volume of HNO3 (ml) 50
Volume of H2O (ml) 700
Leaching time (hr) 6
Final leach liquor volume (ml) 3000
Heating details Open system. 100°C
The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fe using atomic absorption spectromettric methods. Calculations have been done on gpl basis in the leach liquor as well as on percentage basis with respect to the ore. The results are given below Chemical analysis of the leach liquor
Wt% gpl
Ni 0.541 0.9
Co 0.031 0.05
Fe 10.3 17.17

Iron is separated from the leach liquor using CaCO3 as precipitant. Precipitant is added till the pH
of the solution is raised to 2.7. Precipitated iron is separated by filtration precipitation details are
given below :
Precipitation details
Volume of leach liquor (ml) 3000
Precipitation temperature °C 100
Amount of CaCo, (g) 270
Precipitation pH 2.7
Volume of filtrate 4000
The filtrate obtained after separating iron as precipitate is analysed for Ni. Co and Fe using
atomic absorption spectrometric methods The results are given below
Filtrate analysis
Ni(gpl) 0.7
Co(gpl) 0.034
Fe(ppm) 4.85
To the filtrate, Ca(OCI) CI is added till the pH of the solution is raised to 4. An oxidising acid is
added to it till the pH is brought down below 0.7. The pH is again raised by adding CaCo3 to 3.
Co is separated as precipitate which is re-dissolved in dilute H2SO4/HCI for the purpose of
analysis Ni, Co and Fe are analysed by atomic absorption spectrometric methods. The results are
given below •
analysis of cobalt concentrate (Total volume 250 ml)
Ni(ppm) 482.95
Co(gpl) 0.45
Fe(ppm) trace
The filtrate obtained after separating cobalt contains nickel which is precipitated using Na2C03
and NaOH until the pH of the solution is raised to 10. The nickel is filtered and separtd as
precipitate and re-dissolved in H2SO4 / HC1 for chemical analysis Ni Co and Fe are analysed by
atomic absorption spectrometric methods.
Analysis of nickel concentrate (Total volume 250 ml)
Ni(gpl) 11
Co(ppm) 63.9
Fe(ppm) 83

The filtrate obtained after separating Ni as precipitate is analysed for Ni. Co and Fe using atomic
absorption spectrometric methods. The results are given below
Residual filtrate analysis
Ni(ppm) trace
Co(ppm) trace
Fe(ppm) trace
EXPERIMENT II
500 gm of the raw lateritic nickel ore containing nickel in the range of 0.6-0.7 was taken and
digested with triacid mixture of HC1, 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 particular temperature. The
digested mixture was cooled and filtered. The filtrate was made to 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 Fe. The experiment details are given below.
Experimental details
Name of the ore Lateritic nickel ore
Origin of the ORe Sukinda
Weight of the Ore(g) 500
Volume of HCI(mi)
Volume of H2SO4 (ml) 200
Volume of HNO3 (mi)
Volume of H2O (ml) 200
Leaching time (hr) 1.5
Final leach liquor volume (ml) 2000
Heating details open system 100 °C
The filtrate obtained in the digestion is analysed for Ni, Co, Cr and Fe using atomic absorption
spectromeric methods. Calculations have been done on gpl basis in the leach liquor as well as on
percentage basis with respect to the ore. The results are given below.
Chemical analysis of the leach liquor
Wt% gpl
Ni 0.669 1.67
Co 0.033 0.08
Fe 19.71 49.27

Iron is separated from the leach liquor using CaCO3 as precipitant. Precipitant is added till the PH
of the solution is raised to 2.7. Precipitated iron is separated by filtration Precipitation details are
given below :
Precipitation details
volume of leach liquor (ml) 2000
Precipitation temperature, C 100
Amount of CaC03(g) 325
Precipitation Ph 2.7
Volume of filtrate 3000
The filtrate obtained after separating iron as precipitant is analysed for Ni, Co and Fe using
atomic absorption spectrometric methods. The results are given below.
Filtrate analysis
Ni(gpl) 0.76
Co(gpl) 0.041
Fe(ppm) 1.1
To the filtrate Ca(OCl) Cl is added till the pH of the solution is raised to 4. An oxidising acid is
added to it till the pH is brought down below 0.7. The pH is again raised by adding CaCO3 to 3.
Co is separated as precipitate which is re-dissolved in dilute.
H2SO4 / HCl/HNO3 for the purpose of analysis Ni, Co and Fe are analysed by atomic absorption
spectrometric methods. The results are given below. Analysis of cobalt concentrate (Total volume
750ml)
Ni(ppm) 121.16
Co(gpl) 0.058
Fe9ppm) 9.3
Analysis of residual filtrate
The filtrate obtained after separating cobalt contains nickel which is precipitated using Na2CO3
and NaOH until the pH of the solution is raised to 10. The nickel is filtered and separated as
precipitate and re-dissolved in H2S04 / HC1/HNO3 for chemical analysis Ni, Co and Fe are
analysed by atomic absorption spectrometric methods. Results are given below.
Analysis of the nickel concentrate (750 ml)
Ni gpl 2.43
Co(ppm) 102.25

Fe(ppm) 1.08
The filtrate obtained after separating Ni as precipitate is analysed for Ni. Co and Fe using atomic
absorption spectrometric methods. The results are given below.
Residual filtrate analysis
Ni (ppm) 7.83
Co(ppm) 0.244
Fe(ppm) not found
Experiment III
500 g of the raw lateritic nickel are containing nickel in the range of 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 time at a particular temperature. The
digested mixture was cooled and filtered. The filtrate 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 Fe. The experimental details are given below.
Experimental details
Name of the ore Lateritic nickel ore
Origin of the ore Sukinda
Weight of the ore(g) 500
Volume of HCI (ml) 50
Volume of H,SO4 (ml) 100
Volume of HNO3 (ml) 50
Volume of H2O (ml 700
Leaching time (hr) 6
Final leach liquor volume (ml) 3000
Heating details Open system 100°C
The filtrate obtained in the digestion is analysed for Ni,Co, Cr and Fe using atomic absorption
spectrometric methods. Calculations have been done on gpl basis in the leach liquor as well as on
percentage basis with respect to the ore. The results are given below.
Chemical analysis of the leach liquor
wt% gpl
Ni 0.81 1.35
Co 0.032 0.05

Fe 13.44 22.4
Iron is separated from the leach liquor using CaCO3 as precipitant. Precipitant is added till the pH
of the solution is raised to 2.7. Precipitated iron is separated by filtration. Precipitation details are
given below.
Precipitation detail
volume of leach liquor (ml) 3000
Precipitation temperature, C 100
Amount of CaCO3(g) 265
Precipitation pH 2.7
Volume of filtrate F2 3255
The filtrate obtained after separating iron as precipitate is analysed for Ni, Co and Fe using
atomic absorption spectrometric methods. The results are given below.
Filtrate analysis
Ni(gpl) 1.121
Co(gpl) 0.052
Fe(ppm) not found
To the filtrate, Ca(OCI) Cl is added till the PH of the solution is raised to 4. An oxidising acid is added to it till the pH is brought down below 0.7. The pH is again raised by adding CaCO3 to 3. Co is separated as precipitate which is re-dissolved in dilute
H2SO4/HC1/HNO3 for the purpose of analysis, Ni, Co and Fe are analysed by atomic absorption
spectrometric methods. The results are given below.
Analysis of cobalt concentrate (Total volume 250 ml)
Ni (ppm) 228.59
Co(gpl) 0.24
Fe(ppm) 0.63
The filtrate obtained after separating cobalt contains nickel which is precipitated using Na2CO3 and NaOH until the PH of the solution is raised to 10. The nickel is filtered and separated as precipitate and redissolved in H2SO4/HC1/HNO3 for chemical analysis. Ni Co and Fe are analysed by atomic absorption spectrometric methods. Results are given below.

Analysis of nickel concentrate (Total volume 250 ml)
Ni(gpl) 13.44
Co(ppm) 300
Fe (ppm) 25
The filtrate obtained after separating Ni as precipitate is analysed for Ni, Co and Fe using atomic absoiption spectrometric methods. The results are given below.
Residual filtrate analysis
Ni (ppm) trace
Co(ppm) trace
Fe(ppm) trace
The main advantages of the process of the present invention are :
1. The invention requires very low energy in comparison to the existing ones
2. In the present invention, metallic values in the lateritic nickel ore are obtained in the
separated form.
3. The present invention is eco-friendly and it does not pollute the environment.
4. The present invention is operator friendly as it does not involve any hazardous reagents.
5. The present invention may be used for the extraction of nickel from lateritic nickel ore
containing Ni 0.1% and above.
6. The present invention may be used for extraction of nickel from lateritic nickel ore having
even higher percentage of nickel.
7. The present invention is cost effective in comparison to other nickel extraction processes.
8. The present invention is cost effective in comparison to other existing nickel, cobalt and iron
extraction processes.

We claim:
1. An improved process for the extraction of nickel, cobalt and iron from
lateritic nickel ores which comprises:
(a) leaching laleritic nickel ore with mineral acid and traces of organic acid
followed by filtration;
(b) heating the filtrate obtained in step (a) to boiling, adding neutralising
agent to the boiling filtrale till the pH of the filtrate is in the range of 2.5
to 3 followed by filllration to separate iron as precipilate;
(c) adding strong oxidising agent to the fillrate obtained in step (b) lo raise
the pM of the fillrale in the range of 3 lo 4, adding oxidising acids lo lower
I.he pil below 0.7, followed by addition of neutralising agent lo the
mixture lo raise the pi I in Ihe range of 2.7 lo 3, filtering (he resultant
mixture to separate cobalt as precipitate;
(d) adding neutralising agent to the fillrate obtained in slep (c) till the pH is in
the range of 8 to 10 followed by filtration to obtain nickel as precipitate;

2. An improved process as claimed in claim I wherein lateritic nickel ore is
used such as having nickel concentration less than 0.1% and above.
3. An improved process as claimed in claims I to2 wherein concentrated
mineral acids used for leaching lalerilie nickel ores such as H2SO4, HCI,
HNO3, H3PO4 singly or in combination thereof.

4. An improved process as claimed in claims I lo 3 wherein organic acids
such as oxalic acid, larlaric acid, ascorbic acid are used as solids in traces
in the range of 1:50 with respecl to the laleritic nickel ore for leaching
lateritic nickel ores.
5. An improved process as claimed in claims I lo 4 wherein neutralising
agents used are such as CaCO3, (NH4)2CO3 , Na2CO3 , NaOH, NH4OH or
mixtures thereof.
6. An improved process as claimed in claims I to 5 wherein strong oxidising
agents used are such as Ca(OCI)CI, Na(OCI), H2O2, (NH4)2S2O8.
7. An improved process as claimed in claims 1 lo 6 wherein oxidising acids
used arc such as HNO3, HCIO4.
8. An improved process for the exlraclion of nickel, cobalt and iron from
laleriiic nickel ores substantially as herein described wilh reference to the
examples.

Documents:

3511-del-1997-abstract.pdf

3511-del-1997-claims.pdf

3511-del-1997-correspondence-others.pdf

3511-del-1997-correspondence-po.pdf

3511-del-1997-description (complete).pdf

3511-del-1997-form-1.pdf

3511-del-1997-form-19.pdf

3511-del-1997-form-2.pdf

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Patent Number

232754

Indian Patent Application Number

3511/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-110 001, INDIA.

Inventors:

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

PCT International Classification Number

C22B 23/06

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA