TECHNICAL FIELD

The present disclosure relates to field of metallurgy and material sciences. The disclosure particularly relates to a method for separating iron bearing minerals from tailing product (discards) generated during iron ore beneficiation process, such as slime.

BACKGROUND OF THE DISCLOSURE
Slimes generated from iron ore beneficiation plant is considered as tailing product because of lean concentration of iron bearing mineral or iron oxide. Such slime or tailing product are discarded into slime pond as a waste material. However, due to high demand for iron oxides that has existed over many decades, various means and technology, such as gravity separation, magnetic separation, flotation and leaching technique have been explored to recover iron bearing minerals from such slime or tailing product generated from iron ore beneficiation process. However, due to presence of ultra-finely divided iron particles in the slime, employing gravity separation techniques and surface phenomenon techniques such as flotation and leaching do not lead to sufficient separation of iron ore bearing minerals from the slime. Moreover, the surface phenomenon techniques are noted to be very expensive to separate of iron bearing minerals from the slime.

Further, it is noted that, presence of blue dust in the slime hinders the process of separating iron bearing minerals through existing magnetic separation techniques. Thus, it is noted that the existing magnetic separation techniques are not able to sufficiently separate or recover iron bearing minerals from the slime.

Thus, there is a need for an efficient and economical separation or recovery technique/method for separating/recovering iron bearing minerals from the slime generated from iron ore beneficiation process.

The present disclosure describes an improved method for separating/recovering iron bearing minerals from the slime generated from iron ore beneficiation process, which overcomes all the limitations noted above in separating/recovering iron bearing materials by the available techniques or methods.

STATEMENT OF THE DISCLOSURE
Accordingly, the present disclosure describes a method for separating iron bearing minerals from slime generated in iron ore beneficiation process. The method is simple, economical, and efficient in providing improved separation or recovery of iron bearing minerals from the slime.

In an embodiment of the present disclosure, the method for separating iron bearing minerals from the slime, comprises- subjecting the slime to rougher high gradient magnetic separator (HGMS) to obtain magnetic concentrate comprising the iron bearing minerals and non-magnetic constituent; subjecting the non-magnetic constituent to hygroscopic surface treatment; and subjecting the surface treated constituent to scavenger HGMS to obtain further magnetic concentrate comprising the iron bearing minerals.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the present disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, where:

FIGURE 1: illustrates a flow chart depicting the method of separating iron bearing minerals from slime according to the present disclosure.

FIGURE 2: illustrates a plot describing yield and Fe(T) value in scavenger HGMS with dopant and without dopant.

FIGURE 3: illustrates a plot describing yield and Fe(T) value in the overall product with dopant and without dopant.

FIGURE 4: illustrates a plot describing improvement in the product yield and Fe(T) upon addition of dopant.

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.

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 describes an improved method for separating iron bearing minerals from slime generated from iron ore beneficiation process.

The inventors in the present disclosure have provided an improved method for separating iron bearing minerals from slime having blue dust, generated from iron ore beneficiation process.
In some embodiments of the present disclosure, the method for separating iron bearing minerals disclosed herein is simple, economical and efficient when compared to conventionally known techniques, such as gravity separation, surface phenomenon techniques, such as flotation and leaching and known magnetic separation techniques.

In some embodiments of the present disclosure, the method for separating iron bearing minerals from the slime involves combination of high gradient magnetic separator (HGMS), such as rougher HGMS and scavenger HGMS with intermittent hygroscopic surface treatment.

In some embodiments of the present disclosure, the method for separating iron bearing minerals from slime generated in iron ore beneficiation process, comprises-
- Subjecting the slime to rougher high gradient magnetic separator (HGMS) to obtain magnetic concentrate comprising the iron bearing minerals and non-magnetic constituent;
- Subjecting the non-magnetic constituent to hygroscopic surface treatment; and
- Subjecting the surface treated constituent to scavenger HGMS to obtain further magnetic concentrate comprising the iron bearing minerals.

In some embodiments of the present disclosure, the slime comprises hematite ranging from about 20% to 50%, including all the values in the range, for instance, 21%, 22%, 23%, 24% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises goethite ranging from about 30% to 50%, including all the values in the range, for instance, 31%, 32%, 33%, 34% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises blue dust ranging from about 10% to 40%, including all the values in the range, for instance, 11%, 12%, 13%, 14% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises kaolinite ranging from about 1% to 10%, including all the values in the range for instance, 2%, 3%, 4%, 5% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises quartz ranging from about 0% to 5%, including all the values in the range for instance, 0.1%, 0.2%, 0.3%, 0.4% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises alumina ranging from about 5% to 15%, including all the values in the range, for instance, 6%, 7%, 8%, 9% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises Fe (T) ranging from about 50% to 58%, including all the values in the range, for instance, 51%, 52%, 53%, 54% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises SiO2 ranging from about 6% to 12% including all the values in the range, for instance, 7%, 8%, 9%, 10% and so on and so forth.

In some embodiments of the present disclosure, the slime comprises Al2O3 ranging from about 6% to 13% including all the values in the range, for instance, 7%, 8%, 9%, 10% and so on and so forth.

In some embodiments of the present disclosure, the slime has loss on ignition ranging from about 5% to 10%, including all the values in the range, for instance 5.1%, 5.2%, 5.3%, 5.4% and so on and so forth.

In some embodiments of the present disclosure, the rougher HGMS is carried out at magnetic intensity ranging from about 6000 Gauss to 8000 Gauss, including all the values in the range, for instance, 6001 Gauss, 6002 Gauss, 6003 Gauss, 6004 Gauss and so on and so forth.

In some embodiments of the present disclosure, the rougher HGMS is carried out by applying electric current ranging from about 600 Amps to 800 Amps, including all the values in the range, for instance, 601 Amps, 602 Amps, 603 Amps, 604 Amps and so on and so forth.

In some embodiments of the present disclosure, the rougher HGMS is carried out by employing matrix having size ranging from about 0.15 mm to 2 mm, including all the values in the range, for instance, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm and so on and so forth.
In some embodiments of the present disclosure, the scavenger HGMS is carried out at magnetic intensity ranging from about 8000 Gauss to 9000 Gauss, including all the values in the range, for instance, 8001 Gauss, 8002 Gauss, 8003 Gauss, 8004 Gauss and so on and so forth.

In some embodiments of the present disclosure, the scavenger HGMS is carried out by applying electric current ranging from about 700 Amps to 950 Amps, including all the values in the range, for instance, 701 Amps, 702 Amps, 703 Amps, 704 Amps and so on and so forth.

In some embodiments of the present disclosure, the scavenger HGMS is carried out by employing matrix having size ranging from about 0.15 mm to 2 mm, including all the values in the range, for instance, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm and so on and so forth.

In some embodiments of the present disclosure, the hygroscopic surface treatment is carried out by adding dopant including but not limited to sodium activated acrylamide.

In some embodiments of the present disclosure, the dopant is added in an amount ranging from about 10 g/Ton to 25 g/Ton, including all the values in the range, for instance, 10.1 g/Ton, 10.2 g/Ton, 10.3 g/Ton, 10.4 g/Ton and so on and so forth, based on the percentage of blue dust present in the slime.

In some embodiments of the present disclosure, the hygroscopic surface treatment is carried out at a pH ranging from about 8 to 12, including all the values in the range for instance, 8.1, 8.2, 8.3, 8.4 and so on and so forth.

In some embodiments of the present disclosure, the hygroscopic surface treatment is carried out at a pH ranging from about 8 to 12 when the blue dust in the non-magnetic constituent from the rougher HGMS is ranging from about 15% to 20%.

In some embodiments of the present disclosure, the hygroscopic surface treatment is carried out at a pH ranging from about 8 to 12 when the blue dust in the non-magnetic constituent from the rougher HGMS is greater than or equal to 40%.

In some embodiments of the present disclosure, the non-magnetic constituent obtained after rougher HGMS is subjected to alkaline treatment by employing base including but not limited to about 2% to 5% concentrated alkaline, to adjust the pH of the constituent in the range of about 8 to 12, including all the values in the range, for instance, 8.1, 8.2, 8.3, 8.4 and so on and so forth, depending on the amount of blue dust present in the slime. After adjusting the pH to a desired value, i.e., in the range of about 8 to 12, dopant including but not limited to sodium activated acrylamide is added.

The inventors have identified that, blue dust iron bearing mineral constituents will be high in non-magnetic constituent obtained after rougher HGMS due to non-hygroscopic nature of the blue dust. Addition of dopant during the hygroscopic treatment enhances hygroscopic nature of the blue dust. The dopant selectively forms a coat on surface of the blue dust at the alkaline pH and thereby enhances the hygroscopic nature of the blue dust. Subjecting the hygroscopic treated non-magnetic constituent to scavenger HGMS captures blue dust as well as interlocked non-iron and iron bearing minerals, thereby providing for improved separation or recovery of iron bearing minerals from the slime.

In some embodiments of the present disclosure, the magnetic concentrate obtained from rougher HGMS comprises Fe (T) ranging from about 50% to 60%, including all the values in the range, for instance, 51%, 52%, 53%, 54% and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from rougher HGMS comprises SiO2 ranging from about 3% to 8%, including all the values in the range, for instance, 3.1%, 3.2%, 3.3%, 3.4% and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from rougher HGMS comprises Al2O3 ranging from about 4% to 12%, including all the values in the range, for instance, 4.1%, 4.2%, 4.3%, 4.4% and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from rougher HGMS has loss on ignition ranging from about 3% to 9%, including all the values in the range, for instance, 3.1%, 3.2%, 3.3%, 3.4% and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from scavenger HGMS comprises Fe (T) ranging from about 58% to 65%, including all the values in the range, for instance, 59%, 60%, 61%, 62% and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from scavenger HGMS comprises SiO2 ranging from about 1.5% to 4%, including all the values in the range, for instance, 1.6%, 1.7%, 1.8%, 1.9% and so on and so forth.
In some embodiments of the present disclosure, the magnetic concentrate obtained from scavenger HGMS comprises Al2O3 ranging from about 1.8% to 4.5%, including all the values in the range, for instance, 1.9%, 2.0%, 2.1%, 2.2% and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from scavenger HGMS has loss on ignition ranging from about 2% to 5%, including all the values in the range, for instance, 2.1%, 2.2%, 2.3%, 2.4% and so on and so forth.

In some embodiments of the present disclosure, yield of the iron bearing minerals from the rougher HGMS is ranging from about 40% to 70%, including all the values in the range, for instance, 41%, 42%, 43%, 44% and so on and so forth.

In some embodiments of the present disclosure, yield of the iron bearing minerals from the scavenger HGMS is ranging from about 15% to 35%, including all the values in the range, for instance, 16%, 17%, 18%, 19% and so on and so forth.

In some embodiments of the present disclosure total yield of the iron bearing minerals obtained according to the method described above is ranging from about 45% to 75%, including all the values in the range, for instance, 46%, 47%, 48%, 49% and so on and so forth.

In some embodiments of the present disclosure, cumulative magnetic concentrate (i.e., magnetic concentrate from rougher HGMS and scavenger HGMS, respectively) obtained from the method described above comprises- Fe (T) ranging from about 59% to 65%, including all the values in the range, for instance, 60%, 61%, 62%, 63% and so on and so forth.

In some embodiments of the present disclosure, cumulative magnetic concentrate obtained from the method described above comprises- Al2O3 ranging from about 1.8% to 4.5%, including all the values in the range, for instance, 1.9%, 2.0%, 2.1%, 2.2% and so on and so forth.

In some embodiments of the present disclosure, cumulative magnetic concentrate obtained from the method described above comprises- SiO2 is ranging from about 1.5% to 4%, including all the values in the range, for instance, 1.6%, 1.7%, 1.8%, 1.9% and so on and so forth.

In some embodiments of the present disclosure, the method described above by employing the combination of two stage HGMS (i.e., rougher HGMS and scavenger HGMS) with intermittent hygroscopic surface treatment provides for weight recovery (yield) of iron bearing minerals ranging from about 40% to 62% with Fe (T) ranging from about 59% to 65% from an input slime having Fe (T) ranging from about 48% to 60%.

In some embodiments of the present disclosure, the slime employed in the method described above has solid density ranging from about 12% to 30%, including all the values in the range for instance, 13%, 14%, 15%, 16% and so on and so forth.

In some embodiments of the present disclosure, about 40% to 70% of the slime employed in the method described above has particle size ranging from about 0.1 microns to 10 microns, including all the values in the range for instance, 0.2 microns, 0.3 microns, 0.4 microns, 0.5 microns and so on and so forth.

In some embodiments of the present disclosure, the magnetic concentrate obtained from rougher HGMS and the magnetic concentrate obtained from scavenger HGMS respectively, is subjected to concentrate thickener to obtain enriched iron oxide material (iron bearing minerals).

In some embodiments of the present disclosure, the non-magnetic constituent obtained from the scavenger HGMS is subjected to rougher HGMS to obtain additional magnetic concentrate.

In some embodiments of the present disclosure, the method of separating iron bearing minerals from slime generated in iron ore beneficiation process, comprises:
- Subjecting the slime to rougher HGMS to obtain magnetic concentrate comprising the iron bearing minerals and non-magnetic constituent;
- Subjecting the non-magnetic constituent to hygroscopic surface treatment;
- Subjecting the surface treated constituent to scavenger HGMS to obtain further magnetic concentrate comprising the iron bearing minerals; and
- subjecting the magnetic concentrate obtained from the scavenger HGMS to rougher HGMS to obtain additional magnetic concentrate comprising the iron bearing minerals.

In some embodiments of the present disclosure, the obtained additional magnetic concentrate is also subjected to concentrate thickener to obtain enriched iron oxide material.

In an exemplary embodiment of the present disclosure, the method of separating iron bearing minerals from slime generated in iron ore beneficiation process, comprises-
- Subjecting the slime to rougher HGMS at a magnetic intensity ranging from about 6000 Gauss to 8000 Gauss by employing electric current ranging from about 600 Amps to 800 Amps to obtain magnetic concentrate comprising the iron bearing minerals and non-magnetic constituent;
- Subjecting the non-magnetic constituent to hygroscopic surface treatment at a pH ranging from about 8 to 12 and adding dopant including but not limited to sodium activated acrylamide; and
- Subjecting the surface treated constituent to scavenger HGMS at a magnetic intensity ranging from about 8000 Gauss to 9000 Gauss by employing electric current ranging from about 700 Amps to 950 Amps to obtain further magnetic concentrate comprising the iron bearing minerals.

The method for separating iron bearing minerals from the slime generated in iron ore beneficiation process disclosed herein provides for many advantages, such as-
- Improved weight recovery (yield) of about 40% to 60% of iron bearing minerals is achieved from the slime having blue dust.
- the method is simple and economical when compared to conventionally known separation techniques such as gravity separation, floatation and leaching techniques.
- Combination of HGMS (i.e., rougher HGMS and scavenger HGMS) with intermittent hygroscopic surface treatment described in the method is identified to provide improved recovery or separation of iron bearing mineral from the slime having blue dust in the range of 10% to 40%.
- Weight recovery (yield) enhancement of at least 10% of iron bearing minerals is achieved in the method disclosed herein when compared to the method carried out without hygroscopic surface treatment.

In an embodiment of the present disclosure, the Figure 1 illustrates a flow chart describing the method described above for separating iron bearing minerals from the slime. As described in the flow chart- the slime or tailing product (11) is generated from hydrocyclone overflow (10) from the iron beneficiation process. The slime (11) is a feed material for rougher HGMS (12). Rougher HGMS (12) generates two products- magnetic concentrate (17) and non-magnetic constituent (13). The magnetic concentrate (17) is subjected to concentrate thickener (23) and the non-magnetic constituent (13) is subjected to hygroscopic surface treatment (14). The hygroscopic surface treated material (15) is subjected to scavenger HGMS (16). The magnetic concentrate (18) obtained from scavenger HGMS (16) is subjected to concentrate thickener (23) to obtain enriched iron oxide containing material (20). In other words, the magnetic concentrate (17) obtained from rougher HGMS and the magnetic concentrate (18) obtained from scavenger HGMS (16) is subjected to concentrate thickener (23) respectively, to obtain iron oxide containing material (20).

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: Separating iron bearing minerals employing combination of HGMS (rougher HGMS and scavenger HGMS) and hygroscopic treatment.
Slime having pulp density of about 17% solid was subjected rougher HGMS. Chemical specification of the slime is provided in Table 1. Table 2 describes the operational parameters employed during rougher HGMS. Table 3 describes output details of the rougher HGMS.

Attributes Weight % Fe (T) % SiO2% Al2O3% LOI %
Feed 100 55.94 5.65 7.07 7.2858
Table 1: Chemical specification of the slime (feed)

Rougher magnetic separation operational parameters
Operational attributes Matrix magnetic intensity pulp density Current
Value 2mm 8000 gausses 17 % solid 800 amps
Rougher Stage Magnetic separation
Attributes Weight % Fe (T) % SiO2 % Al2O3 % LOI %
Magnetic Concentrate
(Concentrate-1) 54 63.15 2.42 3.25 4.0255
Tailing-1 (non-magnetic constituent) 46 47.48 9.44 11.55 11.11
Table 2: Operational parameters of rougher HGMS

Table 3: Output details of rougher HGMS

The non-magnetic constituent (tailing 1) from rougher HGMS was subjected to surface treatment with sodium activate acrylamide at an amount of 25 g per ton feed material. Further, the surface treated constituent was subjected to scavenger HGMS. Operational parameters of scavenger HGMS is described in Table 4. The output details of the scavenger HGMS is described in Table 5.

Scavenger magnetic separation operational parameters
Operational attributes Matrix magnetic intensity pulp density Current
Value 2mm 6000 gausses 15 % solid 620 amps
Table 4: Operational parameters of scavenger HGMS

Scavenger Stage Magnetic separation (with dopant)
Attributes Weight % Fe (T) % SiO2 % Al2O3 % LOI %
Feed 46 47.48 9.44 11.55 11.11
Magnetic Concentrate (Concentrate-2) 15 61.8 3.2 3.8 4.63
Tailing-2 (non-magnetic constituent) 31 40.55 12.46 15.31 14.25
Table 5: Output details of scavenger HGMS

Data in Table 5 shows that surface treatment of non-magnetic constituent with the dopant, followed by scavenger treatment provides magnetic concentrate having enhanced total Fe [Fe (T)] which is quantified as 61.8% with 32% yield. The tailing-2 from the scavenger HGMS is fed to tailing thickener as a final discard material.

The overall product yield obtained by the combination of two stage HGMS (rougher HGMS and scavenger HGMS) and hygroscopic surface treatment is provided in table 6.

Overall product Magnetic separation (with dopant)
Attributes Weight % Fe (T), % SiO2, % Al2O3, % LOI, %
Concentrate 1 (magnetic concentrate from rougher HGMS) 54 63.15 2.42 3.25 4.0255
Concentrate 2 (magnetic concentrate from scavenger HGMS) 15 61.8 3.2 3.8 4.63
Overall product 69 62.94 2.54 3.34 4.12
Table 6: Overall product yield

Data in Table 6 shows that the overall product yield of iron bearing minerals is 69% with Fe (T) (total Fe) content of about 62.94%.

Example 2: Separating iron bearing minerals employing combination of HGMS (rougher HGMS and scavenger HGMS) and hygroscopic treatment.
Slime having pulp density of about 17% solid was subjected rougher HGMS. Chemical specification of the slime is provided in Table 7. Table 8 describes the operational parameters employed during rougher HGMS. Table 9 describes output details of the rougher HGMS.

Attributes Weight % Fe (T) % SiO2% Al2O3% LOI %
Feed 100 55.94 5.65 7.07 7.2858
Table 7: Chemical specification of the slime (feed)

Rougher magnetic separation operational parameters
Operational attributes Matrix magnetic intensity pulp density Current
Value 2mm 8000 gausses 17 % solid 800 amps
Table 8: Operational parameters of rougher HGMS

Rougher Stage Magnetic separation
Attributes Weight % Fe (T) % SiO2% Al2O3% LOI %
Magnetic Concentrate
(Concentrate-1) 54 63.15 2.42 3.25 4.0255
Tailing-1 (non-magnetic constituent) 46 47.48 9.44 11.55 11.11
Table 9: Output details of rougher HGMS

The non-magnetic constituent (Tailing-1) from the rougher HGMS was subjected to surface treatment with sodium activate acrylamide at an amount of 25 g per ton feed material in alkaline medium at pH of about 10.5. The surface treated constituent was subjected to scavenger HGMS. Operational parameters of scavenger HGMS is described in Table 10. The output details of the scavenger HGMS is provided in Table 11.

Scavenger magnetic separation operational parameters
Operational attributes Matrix magnetic intensity pulp density Current pH
Value 2mm 6000 gausses 15 % solid 620 amps 10.5
Table 10: Operational parameters of Scavenger HGMS

Scavenger Stage Magnetic separation (with dopant pH 10.5)
Attributes Weight % Fe (T) % SiO2% Al2O3% LOI%
Feed 46 47.48 9.44 11.55 79.00
Concentrate 2 (Magnetic Concentrate) 18 61.9 3.1 3.6 93.30
Tailing 2 (non-magnetic constituent) 28 40.50 12.51 15.40 72.09
Table 11: Output details of Scavenger HGMS

Data in Table 11 shows that surface treatment of non-magnetic constituent with the dopant, followed by scavenger treatment provides magnetic concentrate having enhanced total Fe [Fe (T)] which is quantified as 61.9% with 39.13% yield. The tailing-2 from the scavenger HGMS is fed to tailing thickener as a final discard material.

The overall product yield obtained by the combination of two stage HGMS (rougher HGMS and scavenger HGMS) and hygroscopic surface treatment at pH of about 10.5 is provided in table 12.
Overall product Magnetic separation (with dopant at pH 10.5)
Attributes Weight % Fe (T) % SiO2% Al2O3% LOI %
Concentrate 1 (magnetic concentrate from rougher HGMS) 54 63.15 2.42 3.25 94.33
Concentrate 2 (magnetic concentrate from scavenger HGMS) 18 61.9 3.1 3.6 93.30
Overall product 72 62.95 2.53 3.30 94.17
Table 12: Overall product yield

Data in Table 12 shows that the overall product yield of iron bearing minerals is 72% with Fe (T) (total Fe) content of about 62.95%.

Example 3 (Comparative Example): Separating iron bearing minerals employing HGMS (rougher HGMS and scavenger HGMS) without hygroscopic treatment.
Slime having pulp density of about 17% solid was subjected rougher HGMS. Chemical specification of the slime is provided in Table 13. Table 14 describes the operational parameters employed during rougher HGMS. Table 15 describes output details of the rougher HGMS.

Attributes Weight % Fe (T)% SiO2% Al2O3% LOI %
Feed 100 55.94 5.65 7.07 7.2858
Table 13: Chemical specification of the slime (feed)

Rougher magnetic separation operational parameters
Operational attributes Matrix magnetic intensity pulp density Current
Value 2mm 8000 gausses 17 % solid 800 amps
Table 14: Operational parameters of rougher HGMS

Rougher Stage Magnetic separation
Attributes Weight % Fe (T) % SiO2% Al2O3% LOI%
Magnetic Concentrate
(Concentrate-1) 54 63.15 2.42 3.25 4.0255
Tailing-1 (non-magnetic constituent) 46 47.48 9.44 11.55 11.11
Table 15: Output details of rougher HGMS

The Tailing-1 (non-magnetic constituent) from the rougher HGMS was subjected to scavenger HGMS. The operational parameters of scavenger HGMS is described in Table 16. The output details of the scavenger HGMS is described in Table 17.

Scavenger magnetic separation operational parameters
Operational attributes Matrix magnetic intensity pulp density Current
Value 2mm 6000 gausses 15 % solid 620 amps
Table 16: Operational parameters of Scavenger HGMS

Scavenger Stage Magnetic separation (without Dopant)
Attributes Weight % Fe (T)% SiO2% Al2O3% LOI%
Feed 46 47.48 9.44 11.55 11.11
Concentrate 2 (Magnetic Concentrate) 10 60.2 3.8 4.1 6.01
Tailing 2 (non-magnetic constituent) 36 43.94 11.01 13.63 17.10
Table 17: Output details from scavenger HGMS

Data in Table 17 shows that scavenger treatment (without hygroscopic surface treatment) provides magnetic concentrate having enhanced total Fe [Fe (T)] which is quantified as 60.2% with 21.7% yield. The tailing-2 from the scavenger HGMS is fed to tailing thickener as a final discard material.

The Table 18 describes the overall yield obtained after subjecting the slime to rougher HGMS and scavenger HGMS (without hygroscopic surface treatment).

Overall product Magnetic separation (Without Dopant)
Attributes Weight % Fe (T) % SiO2% Al2O3 % LOI%
Concentrate 1 (magnetic concentrate from rougher HGMS) 54 63.15 2.42 3.25 4.0255
Concentrate 2 (magnetic concentrate from scavenger HGMS) 10 60.2 3.8 4.1 6.01
Overall product 64 62.69 2.64 3.38 4.34
Table 18: Overall product yield
The data in table 18 shows that the overall product yield is 64% with total Fe content (Fe (T) of 62.69%.

Results from Examples 1 and 2 and the Comparative Example shows that the overall yield of the iron bearing minerals is improved when the slime is subject to combination of HGMS (rougher HGMS and scavenger HGMS) and hygroscopic surface treatment when compared to subjecting the slime only to HGMS (rougher HGMS and scavenger HGMS).

The Figures 2 and 4 demonstrates that the yield improvement of at least 10% was observed when the slime was treated with combination of HGMS (rougher HGMS and scavenger HGMS) and hygroscopic surface treatment when compared to subjecting the slime only to HGMS (comparative example). Also, the Figures 2 and 4 demonstrate that scavenger HGMS performed after hygroscopic surface treatment enhanced iron bearing mineral content (Fe (T)) by at least 1.6% when compared to method without hygroscopic surface treatment (comparative Example).

Further, the Figure 3 demonstrates that the overall product yield with combination of HGMS (rougher HGMS and scavenger HGMS) and hygroscopic surface treatment was enhanced by at least 5% and the overall iron bearing mineral content (Fe (T)) was enhanced by at least 0.7% when compared to method without hygroscopic surface treatment (comparative Example).

Example 4: Preparation of Sodium activated acrylamide
About 20% of acrylamide and sodium acrylate aqueous solution was mixed in a ratio of about 1:5. About 200 parts of this mixed monomer was added to about 1 part of 1% EDTA solution, followed by adding into about 460 parts of deionized water to obtain a mixture. Then about 2-3 parts of both 5% ammonium persulfate and sodium hydrogen sulphite solution was added to the mixture under continuous flow of nitrogen, followed by stirring for about 3 to 4 hours at a temperature of about 40 to 50 °C. Scheme-1 describes the preparation of sodium activated acrylamide.

Scheme-1

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.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

Claims:

1. A method for separation of iron bearing minerals from slime generated in iron ore processing, said method comprises:
- subjecting the slime to rougher high gradient magnetic separator (HGMS) to obtain magnetic concentrate comprising the iron bearing minerals and non-magnetic constituent;
- subjecting the non-magnetic constituent to hygroscopic surface treatment; and
- subjecting the surface treated constituent to scavenger HGMS to obtain further magnetic concentrate comprising the iron bearing minerals.

2. The method as claimed in claim 1, wherein the method comprises subjecting the further magnetic concentrate from scavenger HGMS to rougher HGMS.

3. The method as claimed in claim 1, wherein the rougher HGMS is carried out at magnetic intensity ranging from about 6000 Gauss to 8000 Gauss by applying electric current ranging from about 600 Amps to 800 Amps.

4. The method as claimed in claim 1, wherein the scavenger HGMS is carried out at magnetic intensity ranging from about 8000 Gauss to 9000 Gauss by applying electric current ranging from about 700 Amps to 950Amps.

5. The method as claimed in any one of claims 1 to 4, wherein the HGMS is carried out by employing matrix having size ranging from about 0.15 mm to 2 mm.

6. The method as claimed in claim 1, wherein the hygroscopic surface treatment is carried out by adding dopant, wherein the dopant is sodium activated acrylamide.

7. The method as claimed in claim 6, wherein the dopant is in an amount ranging from about 10 g/Ton to 25 g/Ton based on % of blue dust in the slime.

8. The method as claimed in claim 1, wherein the hygroscopic surface treatment is carried out at pH ranging from about 8 to 12.

9. The method as claimed in claim 1, wherein the magnetic concentrate obtained from rougher HGMS comprises- Fe (T) ranging from about 50% to 60%, SiO2 ranging from about 3% to 8%, and Al2O3 ranging from about 4% to 12%; and the magnetic concentrate has loss on ignition ranging from about 3% to 9%.

10. The method as claimed in claim 1, wherein the magnetic concentrate obtained from scavenger HGMS comprises- Fe (T) ranging from about 58% to 65%, SiO2 ranging from about 1.5% to 4%, and Al2O3 ranging from about 1.8% to 4.5%; and the magnetic concentrate has loss on ignition ranging from about 2% to 5%.

11. The method as claimed in claim 1, wherein yield obtained from rougher HGMS is ranging from about 40% to 70%; and yield obtained from scavenger HGMS is ranging from about 15% to 35%.

12. The method as claimed in claim 1, wherein total yield obtained is ranging from about 45 % to 75%.

13. The method as claimed in claim 1, wherein cumulative magnetic concentrate obtained by the method comprises- Fe (T) ranging from about 59% to 65%, SiO2 ranging from about 1.5% to 4% and Al2O3 ranging from about 1.8% to 4.5%; and the magnetic concentrate has loss on ignition ranging from about 2% to 5%.

14. The method as claimed in claim 1, wherein the slime comprises- hematite ranging from about 20% to 50%; goethite ranging from about 30% to 50%; blue dust ranging from about 10% to 40%; kaolinite ranging from about 1 % to 10%; quartz ranging from about 0% to 5%; and alumina ranging from about 5% to 15%.

15. The method as claimed in claim 1, wherein the slime comprises- Fe (T) ranging from about 50 % to 58%, SiO2 ranging from about 6% to 12%, and Al2O3 ranging from about 6% to 13%; and wherein the slime has loss on ignition ranging from about 5% to 10%.

16. The method as claimed in claim 1, wherein solid density of the slime is ranging from about 12% to 30%.

17. The method as claimed in claim 1, wherein the slime has 40 % to 70% of particles in size ranging from about 0.1 microns to 10 microns.