Description:TECHNICAL FIELD
The present disclosure relates to the field of metallurgy. The present disclosure particularly relates to a method for recovering metal including but not limited to nickel, cobalt, iron and chromite from ore material including but not limited nickel bearing lateritic chromite overburden and nickel laterite.

BACKGROUND OF THE DISCLOSURE
Nickel is a strategic and versatile metal with superior properties that make it ideal for use in various alloys, including stainless steel, alloy steel, non-ferrous alloys, high-temperature alloys, catalysts and rechargeable battery manufacturing. The majority of nickel production is used in the manufacturing of stainless steel. But in recent times, there has been a growing demand for nickel in battery applications, particularly for electric vehicles.

Nickel is found in both sulphide and oxide ore formations, and conventionally the high-grade sulfidic ores have been used to fulfil the demand for nickel. However, with the increasing scarcity of these high-grade ores, lateritic-based ore deposits are becoming more important as they contribute to 70% of total nickel resources. The extraction of nickel from these deposits requires specific pre-processing steps before utilization due to their low turnover of nickel and higher volume of gangue mineral phases.

Hydrometallurgical processing is a commonly used method for extraction of nickel from nickel laterite ores especially high-pressure acid leaching. The hydrometallurgical processing is less efficient and costly as the ores comprise low nickel content and high acid-soluble impurities content. The acid leaching process used in hydrometallurgical processing requires large quantities of acid which can result in significant operational costs and environmental concerns relating to acid disposal. Processing of nickel laterite ores through hydrometallurgical process require significant energy inputs because of high pressure acid leaching. The acid leaching employed in the hydrometallurgical processing generates large amount of waste products and pose environmental risks, including soil and water pollution. Also, the acid leaching in the hydrometallurgical process can be slow, thus, leading to longer processing times and reduced throughput. Further, precipitation of nickel from the leach solution can be challenging particularly in presence of impurities or competing metals, which can reduce the overall efficiency of the process.

Thus, there is a need for an improved process for extracting metals, such as iron, chromite, nickel and cobalt from ore materials which overcomes above described limitations while extracting the metals.

STATEMENT OF THE DISCLOSURE
Accordingly, the present disclosure describes a simple, environmentally friendly, economical and an improved process for extracting metals including but not limited to nickel, cobalt, iron and chromite from ore materials including but not limited to nickel bearing lateritic chromite overburden and nickel laterite.

In an embodiment of the present disclosure, the method of recovering metal selected from a group comprising nickel, cobalt, iron, chromite and combinations thereof from ore material selected from a group comprising nickel bearing lateritic chromite overburden, nickel laterite and a combination thereof, comprises- reducing the ore material at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material; and leaching the reduced ore material at a temperature ranging from about 30 °C to 90 °C, followed by solid-liquid separation to solid material comprising chromium and iron rich and leached liquor comprising nickel and cobalt.

In an embodiment of the present disclosure, the method comprises subjecting the solid material to magnetic separation to extract iron and chromite.

In another embodiment of the present disclosure, the method comprises subjecting the leached liquor to neutralization to extract nickel and cobalt.

In an embodiment, the method of the present disclosure provides for about 85% to 95% of nickel recovery, about 85% to 95% of cobalt recovery, about 80% to 90% of iron recovery and about 75% to 85% of chromite recovery, from the ore material.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIGURE 1 provides an exemplary illustration of steps involved in recovering metals from the ore material, according to the present disclosure.

FIGURE 2 provides an exemplary illustration of chemical reactions involved during recovering metals, such as nickel, cobalt, iron and chromite, according to the present disclosure.

FIGURE 3 illustrates a plot describing x-ray diffraction pattern of nickel-containing chromite overburden (siliceous Ni-overburden).

DETAILED DESCRIPTION OF THE DISCLOSURE
Unless otherwise defined, all terms used in the disclosure, including technical and scientific terms, have meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. By means of further guidance, term definitions are included for better understanding of the present disclosure.

As used herein, the singular forms ‘a’, ‘an’ and ‘the’ include both singular and plural referents unless the context clearly dictates otherwise.

The term ‘comprising’, ‘comprises’ or ‘comprised of’ as used herein are synonymous with ‘including’, ‘includes’, ‘containing’ or ‘contains’ and are inclusive or open-ended and do not exclude additional, non-recited members, elements, or method steps.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

The term ‘about’ as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of ±10% or less, preferably ±5% or less, more preferably ±1% or less and still more preferably ±0.1% or less of and from the specified value, insofar such variations are appropriate to perform the present disclosure. It is to be understood that the value to which the modifier ‘about’ refers is itself also specifically, and preferably disclosed.

The term ‘exemplary’ or ‘exemplary embodiment’ as used herein refers to ‘serving as an example, instance, or illustration.’ Any embodiment of implementation of the present subject matter described herein as ‘exemplary’ is not necessarily to be construed as preferred or advantageous over other embodiments.

Reference throughout this specification to ‘some embodiments’, ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases ‘in some embodiments’, ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification may not necessarily all refer to the same embodiment. It is appreciated that certain features of the disclosure, which are for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The present disclosure relates to a simple, environmentally friendly, economical and an improved method of recovering metal from ore material. The method of present disclosure overcomes the limitations noted in conventional methods for recovering metals, including but not limited to nickel, cobalt, iron, chromite and combinations thereof from ore material including but not limited to nickel bearing lateritic chromite overburden and nickel laterite.

In some embodiments, the present disclosure relates to a method of recovering metals, such as nickel, cobalt, iron and chromite from ore material, such as nickel bearing lateritic chromite overburden and nickel laterite, the method comprises subjecting the ore material to pre-processing and reduction with hydrogen gases generated in situ by action of carbonaceous material and steam, followed by acid leaching to recover metals, such nickel, cobalt, iron and chromite.

In some embodiments, the present disclosure relates to a method of recovering metals, such as nickel, cobalt, iron and chromite from ore material, such as nickel bearing lateritic chromite overburden and nickel laterite, the method comprises-
- reducing the ore material at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material; and
- leaching the reduced ore material at a temperature ranging from about 30 °C to 90 °C, followed by solid-liquid separation to obtain solid materials comprising chromium and iron and leached liquor comprising nickel and cobalt.

In some embodiments, in the method of the present disclosure, reducing the ore material is carried out at a temperature ranging from about 350 °C to 650 °C, 400 °C to 650 °C, 450 °C to 650 °C, 500 °C to 650 °C, 550 °C to 650 °C, 350 °C to 600 °C, 350 °C to 550 °C, 350 °C to 500 °C, 350 °C to 450°C or 350 to 400 °C. In an embodiment, the reducing the ore material is carried out at a temperature ranging from about 350 °C to 650 °C, including all the values in the range, for instance, 360 °C, 370 °C, 380 °C, 390°C and so on and so forth, up until 650 °C.

In some embodiments, in the method of the present disclosure, reducing the ore material is carried out for a duration ranging from about 10 minutes to 60 minutes, including all the values in the range, for instance, 11 minutes, 12 minutes, 13 minutes, 14 minutes and so on and so forth, up until 60 minutes.

In some embodiments, in the method of the present disclosure, reducing the ore material is carried out by mixing the ore material including but not limited to nickel bearing lateritic chromite overburden, nickel laterite, with carbonaceous material selected from a group comprising charcoal, coke, coal, biochar, pet coke, bagasse and combinations thereof. The carbonaceous material comprises carbon content ranging from about 70% to 90%, including all the values in the range, for instance, 71%, 72%, 73%, 74% and so on and so forth, up until 90%, and subranges of the range 70% to 90%. In an embodiment, the carbonaceous material is employed in an amount ranging from about 2% to 7%. In another embodiment, the carbonaceous material is employed in an amount of about 2%, about 3%, about 4%, about 5%, about 6% or about 7%.

In some embodiments, in the method of the present disclosure, the reduction of the ore material is carried out by hydrogen gas generated in situ by the reaction of carbonaceous material and steam.

In some embodiments, in the method of the present disclosure, the reduction of the ore material is carried out in vertical bed reactor, moving bed reactor or fluidised bed reactor.

In an embodiment, in the method of the present disclosure, the reduction of the ore material is carried out in vertical bed reactor, moving bed reactor or fluidised bed reactor, at a temperature ranging from about 350 °C to 650 °C, in presence of carbonaceous material ranging from about 2% to 7% and steam, for a duration ranging from about 10 minutes to 60 minutes.

In some embodiments of the present disclosure, prior to reducing the ore material, the ore material is subjected to size reduction by employing technique selected from a group comprising crushing, grinding, sieving and combinations thereof.

In some embodiments of the present disclosure, the ore material is subjected to crushing by employing jaw crusher, gyratory crusher or high pressure grinding roll. In an embodiment, the crushing is carried out to obtain ore material having particle size ranging from about 1 micron to 150 microns, including all the values in the range, for instance, 2 microns, 3 microns, 4 microns, 5 microns and so on and so forth, up until 150 microns, and subranges of the range 1 micron to 150 microns.

In some embodiments of the present disclosure, the crushed ore material having particle size ranging from about 1 microns to 150 microns is subjected to grinding using ball mill, rod mill, vertical agitation mill or horizontal agitation mill, to obtain ore material having particle size ranging from about 200 µm to 500 µm, including all the values in the range, for instance, 201 µm, 202 µm, 203 µm, 204 µm and so on and so forth, up until 500 µm, and subranges of the range 200 µm to 500 µm.

In some embodiments of the present disclosure, the grounded ore having particle size ranging from about 200 µm to 500 µm is subjected to sieving to obtain ore material having D80 size ranging from about 90 microns to 105 microns, including all the values in the range, for instance 91 microns, 92 microns, 93 microns, 94 microns and so on and so forth, up until 105 microns, and subranges of the range 90 microns to 105 microns.

In an exemplary embodiment, in the method of the present disclosure, the ore material, including but not limited to nickel bearing lateritic chromite overburden, nickel laterite is subjected to crushing to obtain ore material having particle size ranging from about 1 micron to 150 µm. The crushed ore having particle size ranging from about 1 µm to 150 µm is subjected to grinding to obtain ore material having particle size ranging from about 200 µm to 500 µm. The ground ore material having particle size ranging from about 200 µm to 500 µm is subjected to sieving to obtain ore material having D80 size ranging from about 90 microns to 150 microns. The ore material obtained after crushing, grinding, sieving or combination thereof is subjected to reduction at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material.

In another exemplary embodiment, the crushed ore material having particle size ranging from about 1 µm to 150 µm, ground ore material having particle size ranging from about 200 µm to 500 µm or sieved ore material having D80 size ranging from about 90 µm to 150 µm, can be independently or in any combination subjected to reduction at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material. For instance, the crushed and ground ore material can be subjected to reduction at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and a steam to obtain reduced ore material or the crushed, followed by sieved ore material can be subjected reduction at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material.

The inventors of the present disclosure have identified that subjecting the ore material to crushing, grinding, sieving or combinations thereof will remove gangue materials, such as quartz. Thereby, improving reduction of the ore material at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material. The inventors noted that removal of gangue materials increases the metal content, including but not limited to nickel, iron, chromite and cobalt.

In some embodiments, in the method of the present disclosure, the reduced ore is subjected to cooling to a temperature ranging from about 150 °C to 250 °C, including all the values in the range, for instance, 151 °C, 152 °C, 153 °C, 154 °C and so on and so forth, up until 250 °C, and subranges of the range 150 °C to 250 °C. In an embodiment, the cooled ore is quenched with water to obtain a slurry. The obtained slurry is subjected to magnetic separation to separate out gangue materials.

In some embodiments, in the method of the present disclosure, leaching of the reduced ore material is carried out at a temperature ranging from about 30 °C to 90 °C, about 30 °C to 80°C, about 30 °C to 70 °C, about 30 °C to 60 °C, about 30 °C to 50 °C, about 30 °C to 40 °C, about 40 °C to 90 °C, about 50 °C to 90 °C, about 60 °C to 90°C, about 70 °C to 90 °C or about 80 °C to 90 °C. In an embodiment, the leaching is carried out at a temperature ranging from about 30 °C to 90 °C, including all the values in the range, for instance, 31 °C, 32 °C, 33 °C, 34 °C and so on and so forth, up until 90 °C. In an embodiment, the leaching is caried out under atmospheric pressure.

In some embodiments, in the method of the present disclosure, the leaching of the reduced ore is carried out under stirring for a duration ranging from about 60 minutes to 480 minutes, including all the values in the range, for instance, 61 minutes, 62 minutes, 63 minutes, 64 minutes and so on and so forth, up until 480 minutes, and subranges of the range 60 minutes to 480 minutes. In another embodiment, the leaching of the reduced ore is carried out for a duration ranging from about 1 hour to 8 hours, including all the subranges.

In some embodiments, in the method of the present disclosure, the leaching of the reduced ore is carried out with an acid selected from a group comprising sulphuric acid, hydrochloric acid and nitric acid. In an embodiment, the acid is at a concentration ranging from about 0.25 M to 1 M, including all the values in the range, for instance, 0.26 M, 0.27 M, 0.28 M, 0.29 M and so on and so forth, up until 1 M, and subranges of the range 0.25 M to 1M.

In some embodiments, in the method of the present disclosure, the leaching of the reduced ore is carried out by adding acid to the reduced ore at a solid to liquid ratio ranging from about 10% to 30%, including all the values in the range, for instance, 11%, 12%, 13%, 14% and so on and so forth, up until 30%, and subranges of the range 10% to 30%.

In some embodiments, in the method of the present disclosure, during the leaching, slurry obtained is subjected to filtration to obtain filtrate and residue, wherein the filtrate and the residue are subjected to additional leaching, independently. The filtrate and the residue is independently subjected to leaching in presence of acid selected from a group comprising sulphuric acid, hydrochloric acid and nitric, having concentration ranging from about 0.25 M to 1 M, including all the values in the range, for instance, 0.26 M, 0.27 M, 0.28 M, 0.29 M and so on and so forth, up until 1 M, and subranges of the range 0.25 M to 1M. In an embodiment, the filtrate is subjected to leaching alongside fresh batch of reduced ore material and the residue is subjected to leaching directly with acid selected from a group comprising sulphuric acid, hydrochloric acid and nitric, having concentration ranging from about 0.25 M to 1 M, including all the values in the range, for instance, 0.26 M, 0.27 M, 0.28 M, 0.29 M and so on and so forth, up until 1 M, and subranges of the range 0.25 M to 1M.

In some embodiments of the present disclosure, nickel in the range of about 90% to 98% and cobalt in the range of about 90% to 98%, respectively from the ore material is obtained in leached liquor, i.e., in the liquid phase after leaching.

In some embodiments of the present disclosure, nickel of about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97% or about 98% from the ore material is obtained in leached liquor, i.e., in the liquid phase after leaching.

In some embodiments of the present disclosure, cobalt of about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97% or about 98% from the ore material is obtained in leached liquor, i.e., in the liquid phase after leaching.

In some embodiments, in the method of the present disclosure, the leaching is followed by solid-liquid separation to obtain solid material comprising chromium and iron and leached liquor comprising nickel and cobalt. In an embodiment, the solid-liquid separation is carried out by technique including but not limited to filtration, settling, counter-current decantation and centrifugation.

In an exemplary embodiment of the present disclosure, the method of recovering metal, such as nickel, cobalt, iron and chromite from ore material, such as nickel bearing lateritic chromite overburden and nickel laterites, comprises-
- crushing the ore material to obtain ore material having particle size ranging from about 1 micron to 150 µm;
- grinding the crushed ore material to obtain ore material having a particle size ranging from about 200 µm to 500 µm;
- sieving the ground ore material to obtain ore material having D80 size ranging from about 90 µm to 105 µm;
- reducing the sieved ore material at a temperature ranging from about 350 °C to 650 °C, for a duration ranging from about 10 minutes to 60 minutes, in the presence of about 2% to 7% of carbonaceous material and steam, wherein the reaction of the carbonaceous material and steam releases hydrogen gas, aiding in reduction of the ore material; and
- leaching the reduced ore material at a temperature ranging from about 30 °C to 90 °C with an acid having concentration ranging from about 0.25 M to 1 M, for a duration ranging from about 60 minutes to 480 minutes, followed by solid-liquid separation to obtain solid material comprising chromium and iron and leached liquor comprising nickel and cobalt.

In some embodiments, in the method of the present disclosure, the solid material obtained from solid-liquid separation is subjected to magnetic separation to extract iron and chromite. In an embodiment, the magnetic separation is carried out with magnetic intensity ranging from about 2000 gauss to 5000 gauss, including all the values in the range, for instance, 2001 gauss, 2002 gauss, 2003 gauss, 2004 gauss and so on and so forth, up until 5000 gauss, and subranges of the range 2000 gauss to 5000 gauss. The magnetic separation separates iron and chromite from non-magnetic gangue materials, such as silica, alumina and other associated impurities.

In some embodiments, in the method of the present disclosure, the leached liquor obtained from solid-liquid separation is subjected to neutralization to extract nickel and cobalt. In an embodiment, the neutralization is carried out by adding reduced ore material. In an embodiment, the neutralized leach liquor is having pH ranging from about 3 to 4, including all the values in the range, for instance, 3.1, 3.2, 3.3, 3.4 and so on and so forth, up until 4, and subranges of the range 3 to 4.

In some embodiments, in the method of the present disclosure, the neutralized leached liquor is treated with a base selected from a group comprising ammonia, sodium hydroxide, calcium hydroxide and combinations thereof. Treatment of neutralized leached liquor with the base precipitate impurities and retains nickel and cobalt in the solution. In an embodiment, the nickel or the cobalt are precipitated as oxalates or sulphates, respectively.

In an exemplary embodiment, in the method of the present disclosure, the nickel is precipitated as oxalate or sulphate.

In another exemplary embodiment, in the method of the present disclosure, the cobalt is precipitated as oxalate or sulphate.

In an exemplary embodiment of the present disclosure, the method of recovering metal, such as nickel, cobalt, iron and chromite from ore material, such as nickel bearing lateritic chromite overburden and nickel laterite, comprises-
- crushing the ore material to obtain ore material having particle size ranging from about 1 µm to 150 µm;
- grinding the crushed ore material to obtain ore material having particle size ranging from about 200 µm to 500 µm;
- sieving the ground ore material to obtain ore material having D80 size ranging from about 90 µm to 105 µm;
- reducing the sieved ore material at a temperature ranging from about 350 °C to 650 °C, for a duration ranging from about 10 minutes to 60 minutes, in presence of about 2% to 7% of carbonaceous material and steam, wherein the reaction of the carbonaceous material and steam releases hydrogen gas, aiding reduction of the ore material;
- leaching the reduced ore material at a temperature ranging from about 30 °C to 90 °C with an acid having concentration ranging from about 0.25 M to 1 M, for a duration ranging from about 60 minutes to 480 minutes, followed by solid-liquid separation to obtain solid material comprising chromium and iron and leached liquor comprising nickel and cobalt;
- the solid material is subjected to magnetic separation with magnetic intensity ranging from about 2000 gauss to 5000 gauss to extract iron and chromite; and
- the leached liquor is subjected to neutralization by adding reduced ore material to adjust the pH to a range of about 3 to 4, followed by treating with a base to precipitate impurities and retain the nickel and the cobalt in solution; and
- precipitating the nickel and the cobalt as oxalates or sulphates, respectively.

In some embodiments, the method of the present disclosure recovers nickel in the range of about 85% to 95%, including all the values in the range, for instance, 85.1%, 85.2%, 85.3%, 85.4% and so on and so forth, up until 95%, and subranges of the range 85% to 95%, from the ore material.

In some embodiments, the method of the present disclosure recovers cobalt in the range of about 85% to 95%, including all the values in the range, for instance, 85.1%, 85.2%, 85.3%, 85.4% and so on and so forth, up until 95%, and subranges of the range 85% to 95%, from the ore material.

In some embodiments, the method of the present disclosure recovers iron in the range of about 80% to 90%, including all the values in the range, for instance, 80.1%, 80.2%, 80.3%, 80.4% and so on and so forth, up until 90%, and subranges of the range 80% to 90%, from the ore material.

In some embodiments, the method of the present disclosure recovers nickel in the range of about 75% to 85%, including all the values in the range, for instance, 75.1%, 75.2%, 75.3%, 75.4% and so on and so forth, up until 95%, and subranges of the range 85% to 95%, from the ore material.

Accordingly, the method of the present disclosure provides for recovering about 85% to 95% of the nickel, about 85% to 95% of the cobalt, about 80% to 90% of the iron and about 75% to 85% of the chromite, from the ore material, including but not limited to nickel bearing lateritic chromite overburden and nickel laterite.

The inventors of the present disclosure have particularly identified that carrying out leaching under atmospheric pressure, at a temperature ranging from about 30 °C to 90 °C, for a duration ranging from about 60 minutes to 480 minutes and adding acid having concentration ranging from about 0.25 M to 1 M at a solid to liquid ratio ranging from about 10% to 30%, aids in maximizing recovery of nickel and cobalt from liquid phase and avoids flow of iron into the liquid phase.

In an embodiment of the present disclosure, Figure 1 provides an exemplary description of the steps involved in the method of recovering metals, such as nickel, cobalt, iron, chromite and combinations thereof from ore material including but not limited to nickel bearing lateritic chromite overburden and nickel laterite. According to the illustration in Figure 1, the feed ore, i.e., the ore material is subjected to steps, such as- size reduction (for e.g., crushing, griding or combination thereof) and sieving; reduction of the ore material; leaching of the reduced ore material; solid liquid separation to obtain solid material, which is subjected to magnetic separation to obtain iron and chromite, and leached liquor; the leached liquor is subjected to purification, and; the purified leached liquor is subjected to selective precipitation to obtain cobalt and nickel as oxalates or sulphates, respectively.

In an embodiment of the present disclosure, Figure 2 exemplifies chemical reactions occurring during the method of recovering metals, such as nickel, cobalt, iron and chromite.

In some embodiments of the present disclosure, the ore material, such as nickel bearing lateritic chromite overburden ore comprises about 40% to 60% of Fe2O3, about 40% to 60% of SiO2, about 3% to 7% of Cr2O3, about 0.3% to 1% of Ni and about 0.01% to 0.05% of Co.

The method of recovering metals, such as nickel, cobalt, iron and chromite, according to the present disclosure provides following advantages-
- Reduction of the ore material is carried out at lower temperature by employing in-situ generated hydrogen gas, which effectively reduces metals, such as nickel, cobalt, iron and chromite, thereby making it susceptible to leaching, thereby efficient extract of the metals.
- The method allows for efficient extraction/recovery of metals, such as nickel, cobalt, iron and chromite while minimizing the impact of gangue materials dissolution.
- The method is environmentally friendly as it does not release any toxic chemicals and employs optimal chemicals for recovering the metals so that there is no excess usage or wastage of the chemicals.

It is to be understood that the foregoing description is illustrative not a limitation. While considerable emphasis has been placed herein on particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. Similarly, additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein.

Descriptions of well-known/conventional methods/steps and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for examples illustrating the above-described embodiments, and in order to illustrate the embodiments of the present disclosure, certain aspects have been employed. The examples used herein for such illustration are intended merely to facilitate an understanding of ways in which the embodiments may be practiced and to further enable those of skill in the art to practice the embodiments. Accordingly, following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES

Example 1: Recovering metals, such as nickel, cobalt, iron and chromite from nickel bearing chromite overburden.
Nickel-bearing chromite overburden was partially disintegrated and was wet classified to below about 500 µm (D80 is 50 to 105 microns) and coarser than about 500 µm was rejected as silicious gangue material. The dried ore rich in iron, nickel, cobalt and chromite was mixed with 5% charcoal containing 80% fixed carbon. The mixture was then heated to about 450 °C in a fluidised bed reactor and passed steam for about 1 hour. The hot reducing material was cooled to about 200 °C and then quenched in water and a slurry was obtained. The slurry was subjected to magnetic separation to separate out gangue. Subsequently, sulphuric acid was added equivalent to 0.5 M in the leachant for leaching at a solid-liquid ratio of 15%. The slurry was then leached with constant stirring at a temperature of about 80 °C for about 3 hours. The slurry was then filtered to obtain filtrate and residue, the filtrate was again leached with fresh batch of reduced ore material. The residue obtained was again leached with fresh leachant. Final leached liquor was used for nickel and cobalt recovery.

The leached liquor was neutralized using fresh batch of reduced ore material to pH of 3.0 to 4.0. The neutralized liquor was treated with ammonia to precipitate oxide impurities (like R2O3) and metallic impurities, thereby keeping nickel and cobalt in solution. Subsequently, cobalt was precipitated to cobaltic oxide and nickel was precipitated to nickel hydroxide and then to nickel sulphate. Further, the ammonia was recycled into the system for further precipitation.
Table 1 provides characteristics of the nickel-bearing chromite overburden employed for recovery of the metals, such as iron, chromite, nickel and cobalt.
Parameters Unit Value
Fe2O3 % 49.54
SiO2 % 40.25
Cr2O3 % 3.90
Al2O3 % 2.6
NiO % 0.86
CoO % 0.001
MnO % 0.91
SO3 % 0.17
P2O5 % 0.11
Moisture content % 2.2
LOI % 6.0
Table 1:

Example 2:
Recovering metals, such as nickel, cobalt, iron and chromite from chromite ore overburden
Chromite overburden ore was partially disintegrated and was wet classified to below about 500 µm, and coarser than 500 µm was rejected as silicious gangue material. The dried ore rich in iron, nickel, cobalt and chromite was mixed with 4% charcoal containing 75% fixed carbon. The mixture was then heated to 550 °C, taken in a fluidised bed reactor, and passed steam for about 2 hours. The hot reducing material was cooled to 200 °C and then quenched with water and a slurry was obtained. Sulphuric acid was added equivalent to 01 M in the leachant at a solid-liquid ration of about 20%. The slurry was then leached with constant stirring at a temperature of about 90°C for about 2 hours. The slurry was then filtered, and the filtrate was again leached with fresh reduction mass. The residue obtained was again leached with fresh leachant and repulped in fresh water and subjected to magnetic separation to obtain iron and chromite, and non-magnetic residue was rejected.

The leached liquor was neutralized using fresh batch of reduced ore material to pH of 3.0 to 4.0. The final liquor was neutralized with ammonia and precipitate oxide impurities (like R2O3) and metallic impurities, thereby keeping nickel and cobalt in solution. Subsequently, cobalt was precipitated to cobaltic oxide and nickel was precipitated to nickel hydroxide and then to nickel sulphate. Further, the ammonia was recycled into the system for further precipitation.

Table 2 provides characteristics of the chromite overburden ore employed for recovery of the metals, such as iron, chromite, nickel and cobalt.
Parameters Unit Value
Fe % 56.0
SiO2 % 11.0
Cr2O3 % 5.90
Al2O3 % 0.40
NiO % 0.005
CoO % 0.00
MnO % 0.0
SO3 % 0.17
P2O5 % 0.11
Moisture content % 2.2
LOI % 6.0
Table 2:

Example 3:
Recovering metals, such as nickel, cobalt, iron and chromite from chromite ore overburden
The ore is partially disintegrated and was wet classified to below about 500 µm and coarser than 500 µm was rejected as silicious gangue material. The dried ore rich in iron, nickel, cobalt and chromite was mixed with 6% charcoal containing 90% fixed carbon. The mixture was then heated to 550 °C, taken in a fluidised bed reactor, and passed steam for about 2 hours. The hot reducing material was cooled to 200 °C and then quenched with water and a slurry was obtained. Sulphuric acid was added equivalent to 1.5 M in the leachant at a solid-liquid ration of about 30%. The slurry was then leached with constant stirring at a temperature of about 70°C for about 1 hour. The slurry was then filtered, and the filtrate was again leached with fresh reduction mass. The residue obtained was again leached with fresh leachant and repulped in fresh water and subjected to magnetic separation to obtain iron and chromite, and non-magnetic residue was rejected.

The leached liquor was neutralized using fresh batch of reduced ore material, which contains 1.1 g/l Fe, 1.33 g/l Ni and 4 ppm Co, besides other minor impurities. The solution was treated with 10% ammonia solution, pH raised to 8.5, and oxide impurities (like R2O3) were filtered out besides manganese. The amine liquor was treated with NiOOH to precipitate out cobaltic oxide. The purified solution was subjected to ammonia stripping. The nickel sulphate solution evaporated and crystallized for nickel sulphate.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

The foregoing description of the specific embodiments reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification, the term ‘combinations thereof’ or ‘any combination thereof’ or ‘any combinations thereof’ are used interchangeably and are intended to have the same meaning, as regularly known in the field of patents disclosures.

As regards the embodiments characterized in this specification, it is intended that each embodiment be read independently as well as in combination with another embodiment. For example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2 reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned otherwise.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. , C , Claims:WE CLAIM:
1. A method for recovering metal selected from a group comprising nickel, cobalt, iron, chromite, and any combination thereof from ore material selected from a group comprising nickel bearing lateritic chromite overburden, nickel laterite and a combination thereof, said method comprising-
- reducing the ore material at a temperature ranging from about 350 °C to 650 °C in presence of carbonaceous material and steam to obtain reduced ore material; and
- leaching the reduced ore material at a temperature ranging from about 30 °C to 90 °C, followed by solid-liquid separation to obtain Chromium and Iron rich solid material and nickel and cobalt containing leached liquor.
2. The method as claimed in claim 1, wherein the method comprises subjecting the solid material comprising chromium and iron to magnetic separation to extract iron and chromite.
3. The method as claimed in claim 1, wherein the method comprises subjecting the leached liquor comprising nickel and cobalt to neutralization to extract nickel and cobalt.
4. The method as claimed in claim 1, wherein prior to reducing ore material, the ore material is subjected to crushing, grinding, sieving or combination thereof.
5. The method as claimed in claim 4, wherein the crushing is carried using jaw crusher, gyratory crusher or high pressure grinding roll, wherein the crushing is carried out to obtain ore material having particle size ranging from about 1 microns to 150 microns.
6. The method as claimed in claim 5, wherein the crushed ore material is subjected to grinding using ball mill, rod mill, vertical agitation mill or horizontal agitation mill, to obtain the ore material having particle size ranging from about 200 µm to 550 µm.
7. The method as claimed in claim 6, wherein the ground ore material is subjected to sieving to obtain the ore material having D80 size ranging from about 90 microns to105 microns.
8. The method as claimed claim 1, wherein the reduction of the ore material is carried out by mixing the ore material with carbonaceous material selected from a group comprising charcoal, coke, coal, biochar, pet coke, bagasse, and combinations thereof wherein the carbonaceous material is in an amount ranging from about 2% to 7% and wherein the carbonaceous material comprises carbon content ranging from about 70% to 90%.
9. The method as claimed in claim 1, wherein the reduction is carried out by employing hydrogen rich gases generated in situ by the action of the carbonaceous material and steam.
10. The method as claimed in claim 1, wherein the reduction is carried out in vertical bed reactor, moving bed reactor or fluidised bed reactor.
11. The method as claimed in claim 1, wherein the reduced ore material is subjected to cooling to a temperature ranging from about 150 °C to 250 °C, followed by quenching with water to obtain a slurry.
12. The method as claimed in claim 11, wherein the slurry is subjected to magnetic separation to separate out gangue material.
13. The method as claimed in claim 1, wherein the leaching is carried out with an acid selected from a group comprising sulphuric acid, hydrochloric acid and nitric acid; and wherein the acid is at a concentration ranging from 0.25 M to 1 M.
14. The method as claimed in claim 13, wherein the acid is added to the reduced ore material at a solid-liquid ratio ranging from about ranging from about 10% to 30%.
15. The method as claimed in claim 1, wherein the leaching is carried out with stirring for a duration ranging from about 1 hour to 8 hours.
16. The method as claimed in claim 1, wherein slurry obtained during leaching is subject to filtration to obtain filtrate and residue, wherein the filtrate and the residue are subjected to additional leaching, independently.
17. The method as claimed in claim 16, wherein the filtrate is subjected to leaching in presence of fresh batch of reduced ore material and the residue is subjected to leaching directly with the acid.
18. The method as claimed in claim 1, wherein about 90% to 98% of the nickel and about 90% to 98% of the cobalt, respectively from the ore material is obtained in liquid phase after leaching.
19. The method as claimed in claim 2, wherein the magnetic separation is carried out with magnetic intensity ranging from about 2000 gauss to 5000 gauss.
20. The method as claimed in claim 3, wherein the neutralization of the leach liquor is carried out by adding reduced ore material and pH of the neutralized leach liquor is ranging from about 3 to 4.
21. The method as claimed in claim 20, wherein the neutralized solution is further treated with a base selected from a group comprising ammonia, sodium hydroxide, calcium hydroxide, and combinations thereof, thereby precipitating impurities and retaining nickel and cobalt in solution.
22. The method as claimed in claim 21, wherein the nickel and the cobalt are precipitated as oxalates or sulphates.
23. The method as claimed in claim 1, wherein about 85% to 95% of the nickel is recovered from the ore material; about 85% to 95% of the cobalt is recovered from the ore material; about 80% to 90% of the iron is recovered from the ore material; and about 75% to 85% of the chromite is recovered from the ore material.
24. The method as claimed in claim 22, wherein the nickel bearing lateritic chromite overburden comprises about 40% to 60% of Fe2O3, about 40% to 60% of SiO2, about 3% to 7% of Cr2O3, about 0.3% to 1% of Ni and about 0.01% to 0.05% of Co.