Description:FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

1 TITLE OF THE INVENTION :
A PROCESS FOR RECOVERY OF IRON BEARING MINERALS FROM BANDED HEMATITE QUARTZITE IRON ORE THROUGH MAGNETIC SEPARATION.



2 APPLICANT (S)

Name : JSW STEEL LIMITED.

Nationality : An Indian Company incorporated under the Companies Act, 1956.

Address : JSW CENTRE,
BANDRA KURLA COMPLEX,
BANDRA(EAST),
MUMBAI-400051,
MAHARASHTRA,INDIA.



3 PREAMBLE TO THE DESCRIPTION

COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to the beneficiation of low-grade iron ore from banded hematite quartzite (BHQ). Banded hematite quartzite iron ore is hard in nature, and it consists of low iron and high silica. For BHQ iron ore, it is more important to develop an effective beneficiation process to enrich the ore and produce pellet-grade fines to further utilize in pellet making. The BHQ iron ore is processed by applying a stage-wise wet magnetic separation process, i.e., for iron upgrading and the removal of silica for the iron and steel industries. The optimized beneficiation technique for BHQ iron ore with process stages directed to favour value addition in the optimized beneficiation technique. The process of banded hematite quartzite (BHQ) beneficiation would enable a better concentrate grade and higher recovery through three-stage magnetic separation on a ground sample at an optimum liberation size.
BACKGROUND
It is well known in the field of processing ore for input into the iron and steel-producing industries that very low-grade iron ore cannot be used in metallurgical plants and needs to be upgraded to increase the iron content and reduce the gangue content. A process adopted to upgrade ore is called beneficiation. Iron ore is upgraded to have a higher iron content through concentration. Iron ore is being beneficiated all around the world to meet the quality requirements of the iron and steel industries. However, each source of iron ore has its own peculiar mineralogical characteristics and requires specific beneficiation and metallurgical treatment to get the best product out of it. The choice of the beneficiation treatment depends on the nature of the gangue present and its association with the ore structure. Several techniques, such as washing, jigging, magnetic separation, advanced gravity separation, and flotation, are being used to enhance the quality of the iron ore.
With the enhanced steel production as envisaged hematite iron ore availability will not last long. In order to ensure a longer period of ore availability, it is pertinent to use beneficiated banded hematite quartzite (BHQ) and banded magnetite quartzite (BMQ) iron ores. Thus, with the fast depletion of the limited reserves of high grade iron ore and to meet the iron ore requirement of steel plants, the low grade iron ore like banded hematite quartzite (BHQ) and banded hematite jasper (BHJ) have been the focus of interest.
BHQ occurs as compact hard rocks or in the form of weathered soft rocks. The banded magnetite sandstone formation of sedimentary origin underwent metamorphic transformation several times due to heat and pressure from the tectonic movements of the earth in the later stages. As a result, banded magnetite sandstones altered to banded magnetite quartzite’s (BMQ’s). Some BMQs later got altered to banded martite quartzite and banded hematite quartzite due to further application of heat and pressure. Till date, not much research work has been carried out on the possibilities of making use of BHQ as a feed material for iron making and on standardizing an economically viable process for its beneficiation for effective utilization of such ores in industry.
Thus in spite of the need in the art to develop methodologies for BHQ beneficiation, no proven beneficiation methodology for BHQ beneficiation is available at present. There has therefore been a persistent need in the related art to develop a very specific and economically viable beneficiation technique for processing BHQ-based ore. The BHQ-based studies as given above revealed that BHQ is a hard material by nature and requires huge power for size reduction to liberate silica particles from iron-bearing particles. Detailed characterization and liberation studies on BHQ iron ore is more important. To get a better quality and grade of the product, we need to grind the material to the required liberation size of the particular BHQ ore. If we go for a larger size than the optimum liberation size, it will increase the number of beneficiation stages to obtain the desired concentrate, and processing costs will increase. If we go for too finer size other than optimum liberation size it will add more processing cost w.r.t to grinding. So in this work, based on the liberation size, we went for a three-stage magnetic separation process after size reduction (grinding) at the optimum liberation size.

PRIOR-ART-SEARCH
The patent titled“BENEFICIATION PROCESS OF HIGH SILICEOUS LOW GRADE IRON ORE EXHIBITING COMPLEX LIBERATION CHARACTERISTICS”, Application No: INKO000292012, The invention relates to the beneficiation process of high siliceous low grade iron ore. A process of froth flotation to recover Fe values from high siliceous low- grade iron ore through beneficiation, comprising crushing of banded hematite jasper ore to -10mm size for pre-concentration in Jig unit and grinding the jig concentrate to -0.1mm size for flotation. The maintained test conditions are: the percent solids in the slurry is 20-30% solids, pH modifier is NaOH solution and pH of slurry is 8.5-10, the stirrer speed is maintained at 800 - 1000 revolutions per minute, dispersant used is Sodium Hexametaphosphate and optimum dosing of dispersant is 2-3 kg/ton of flotation feed, the collector used is Ether monoamines (Sokem 503C) and optimum dosing of collector is 1-1.5 kg/ton of flotation feed, frother used is Methyl Isobutyl Carbinol, MIBC and optimum dosing of frother is 0.1 kg/ton of flotation feed. The Fe contnet in the concentrate is in the range of 61-62%.
The technical paper titled “Magnetic and flotation studies of banded hematite quartzite (BHQ) ore for the production of pellet grade concentrate”, B Das et.al., International Journal of Minerals, Metallurgy, and Materials volume 17, pages675–682 (2010), reveals The BHQ ore was assayed as 38.9wt% Fe, 42.5wt% SiO2, and 1.0wt% Al2O3. In this ore, hematite and quartz are present as the major mineral phases where goethite, martite, and magnetite are present in small amounts. The liberation of hematite particles can be enhanced to about 82% by reducing the particle size to below 63 µm. The rejection of silica particles can be obtained by magnetic and flotation separation techniques. Overall, the BHQ ore can be enriched to 65.3wt% Fe at 61.9% iron recovery. A flowsheet has been suggested for the commercial exploitation of the BHQ ore.
The technical paper titled “Characterization and beneficiation of BHQ from Karnataka, Lal et.al., Journal of Metallurgy and Materials Science, 55(4) (Non-SCI). pp. 323-327. Reveals that the ore assaying about 40% Fe content where hematite is main iron mineral occurring in association with quartz in the form of bands. The geometrical feature of minerals in the ore was found very complex nature in view of beneficiation. A banded hematite quartzite ore from Karnataka region was taken for beneficiation to explore the possibility of upgrading the Fe content up to the maximum possible extent with a optimum recovery of iron so that it may find better industrial utilization. The geometrical features of minerals are very complex in view of the beneficiation studies. The occurrences of quartz within the groundmass of hematite and vice-versa even below 10 micron size plays adverse role in obtaining the high grade and recovery of concentrate. The textural characteristics of the minerals compelled to choose the restricted route of gravity separation only for the better result. The best possible recovery of the iron concentrate obtained after beneficiation was in the range of 44% -59% withthe grade of Fe(T) ranging from 62% to 65%.
The technical Paper titled “Studies on beneficiation of BHQ samples by different methods” A. Anupam et.al., Material science, Dec’2010, reveals that Experiments have been carried out to beneficiate BHQ samples collected from two different states of the country viz. Karnataka and Orissa by different techniques such as jigging, magnetic separation and using hydrocyclones after their characterisation studies. Results of these tests have clearly indicated that it is possible to beneficiate the BHQ’s of both the states to a certain extent and can only be used to mix with high-grade haematitic iron ores. This would be helpful in conservation and utilisation of rich grade ores. Characterisation studies performed indicated that both the ores require fine grinding to a size of 200mesh to achieve effective liberation. The tests conducted on Barbil area BHQ sample resulted in an upgradation of iron content from a feed value of 42.8% Fe to a maximum of 56.8% Fe by magnetic separation with a yield of around 41%. Similarly, Bellary-Hospet sector ore has indicated that it is possible to increase the iron content from a feed assay value of 35% iron to as high as 55% iron with a yield of 20–24%. More details on the experiments performed and the results obtained are discussed in the paper.
The technical Paper titled “Recovery of Iron values through conventional beneficiation techniques from Banded Hematite Jasper of Eastern India with special reference to mineralogical and chemical characterization” S.K Nanda et.al. Indian Journal of Science and Technology, 2020, Volume: 13, Issue: 38, Pages: 3960-3969, reveals that Banded Hematite Jasper (BHJ) sample of Bonai-Keonjhar belt (BK belt), Odisha, India assayed 35.3 % Fe, 47.1% SiO2 and 0.96% Al2O3 was investigated in respect of mineralogy, liberation characteristics and chemistry to finding out its optimum beneficiation potential. In the present investigation, efforts have been made to characterize the BHJ sample with reference to its beneficiation response. The sample was subjected to various beneficiation operations like Jigging followed by hydrocyclone, two-stage tabling and magnetic Separation. Mineralogical studies indicate that quartz and hematite are the major mineral phases, whereas goethite, martitized magnetite and clay (kaolinite) are present in very minor amounts. The liberation characteristic indicates that the average band thickness of Iron bearing mineral is of 1680 microns and 80% of the iron bearing minerals are liberated at -105 microns size. The two stage tabling of jig concentrate with desliming gives better outcome as compared with direct tabling of jig concentrate. An iron ore concentrate assayed 64.5% Fe, 5.6% SiO2 and 0.80% Al2O3 with wt% recovery of 23.2% can be obtained from two stage tabling. Another concentrate from magnetic separation of table middling and hydrocyclone assayed 63.2% Fe, 7.2% SiO2 and 0.7% Al2O3 with wt% recovery of 12.4% can be obtained.

OBJECTS OF THE INVENTION
The basic objective of the present invention is to develop a precise benefaction process for low-grade BHQ iron ore to obtain maximum weight recovery and grade.
A further objective of the present invention is to process low-grade BHQ iron ore by adopting a crushing, grinding, and three-stage magnetic separation process using HGMS.
A still further objective of the present invention is to provide a process for recovery of iron-bearing minerals from low-grade BHQ iron ore wherein selective magnetic field strength is applied to each stage of said three-stage magnetic separation using HGMS (rougher, cleaner, and scavenger) to significantly improve the recovery of iron-bearing particles.
A still further objective of the present invention is to provide a process for recovery of iron-bearing minerals from low-grade BHQ iron ore wherein the cleaner HGMS nonmagnetic and scavenger HGMS magnetic products are combined and re-circulated to rougher HGMS to further improve the concentrate weight recovery and reduce the tailing loss with lesser Fe.
A still further objective of the present invention is to provide a process for recovery of iron-bearing minerals from low-grade BHQ iron ore wherein the cleaner HGMS nonmagnetic and scavenger HGMS magnetic products are combined and re-circulated to rougher HGMS by further grinding to 38µm to improve the concentrate weight recovery.

SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a process for recovery of iron bearing minerals from low-grade BHQ iron ore comprising the following steps:
subjecting the 100 to 200 mm size low grade BHQ feed sample to stage wise crushing to get the product size <3mm;
grinding of crushed ore to achieve 80 to 85% passing <-45 µm; and
subjecting the ground product through three stage HGMS comprising of :
(a) carrying out rougher HGMS involving selectively
Magnetic field intensity: 8000 to 10000 gauss,
Flow velocity: 62 to 137 mm/s,
Nozzle Size: 5 to 7 mm, and
Slurry density: 1.20 to 1.22 g/cc
(b) carrying out cleaner HGMS involving selectively:
Magnetic field intensity: 5000 to 7000, gauss,
Flow velocity: 62 to 137 mm/s,
Nozzle Size: 5 to 7 mm, and
Slurry density: 1.20 to 1.22 g/cc
(c ) carrying out scavenger HGMS involving selectively
Magnetic field intensity: 10000 to 12000 gauss,
Flow velocity: 62 to 137 mm/s,
Nozzle Size: 5 to 7 mm, and
Slurry density: 1.20 to 1.22 g/cc,
to thereby recover the iron bearing minerals from said low grade BHQ iron ore feed sample.
A further aspect of the present invention is directed to said process wherein to further increase the concentrate recovery and grade recirculation of cleaner HGMS non-mag and scavenger HGMS mag products the same is further subjected to rougher HGMS, further grinding in the ball mill such as to achieve < 38µm < 80 to 86%.
A still further aspect of the present invention is directed to said process wherein the low grade BHQ iron ore feed comprises of:
the Fe content in the feed sample varying from 28.81 to 43.78% and with the variation in other elements being as follows:
SiO2 – 32.50 to 55.06%
Al2O3 – 2.25 to 3.42% and
LOI – 1.90 to 2.85%.

A still further aspect of the present invention is directed to said process wherein the mineralogical phases present in the feed sample are as follows: Magnetite: 1.20 to 2.50%, Hematite: 36.5 to 55.0%, Goethite: 3.50 to 4.50%, Quartzite: 33.50 to 55.00%, Kaolinite: 3.70 to 4.50% and others : 2.00 to 2.50%.

A still further aspect of the present invention is directed to said process wherein the liberation of iron bearing minerals at different size fractions in the feed sample is as follows: -150 µm : 30 to 45%, -75 µm : 56 to 62 %, -45 µm : 65 to 72%, -38 µm : 73 to 78%, -25 µm : 80 to 92%.
A still further aspect of the present invention is directed to said process comprising subjecting the said low-grade BHQ iron ore sample to crushing and grinding followed by three-stage HGMS (rougher, cleaner, and scavenger) by maintaining various magnetic field intensities.
A still further aspect of the present invention is directed to said process wherein in said
Rougher HGMS:
Magnetic field intensity applied is 9000 gauss,
Flow velocity maintained is 88 mm/s ; and
Nozzle Size used is 6 mm;
Cleaner HGMS:
Magnetic field intensity applied is 7000 gauss,
Flow velocity maintained is 88 mm/s ; and
Nozzle Size: used is 6 mm;
Scavenger HGMS:
Magnetic field intensity applied is 11000 gauss,
Flow velocity maintained is 88 mm/s ;and
Nozzle Size: used is 6 mm.

Another aspect of the present invention is directed to saidprocess wherein the recovery and grade of final concentrate obtained by following said crushing, grinding followed by three stage magnetic separation including recirculation of cleaner HGMS mag and scavenger HGMS Non mag comprises maximum weight recovery varying from 20.5 to 39.6% with 60.4 to 63.8% Fe for input feed Fe 28.8 to 43.8%.
Yet another aspect of the present invention is directed to saidprocess wherein the recovery of final product was increased from 15.6 - 27.6 to 20.5 to 39.6% after recirculation of cleaner HGMS non-magnetic and scavenger HGMS magnetic product after further grinding to < 38µm size 80 to 86%.
A still further aspect of the present invention is directed to saidprocess wherein the silica content in the final concentrate obtained by following said crushing, grinding followed by three stage magnetic separation including recirculation of cleaner HGMS mag and scavenger HGMS Non mag comprises 6.62 to 13.50% SiO2 with input feed SiO2 32.50 to 55.06%.
A still further aspect of the present invention is directed to saidprocess wherein the Fe content in the final tailing of the process is 14.8 to 20.7 percent and SiO2 is 61.70 to 74.90% and the Fe recovery in final concentrate is varying from 43.3 to 57.7% and SiO2 reduction is varying from 75.5 to 80.2%.
The above and other aspects of the present invention are described hereunder in greater details with reference to following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: Optical micrographs of BHQ samples.
Figure 2: flow chart for developed beneficiation process for low grade BHQ iron ore according to present invention.

DETAILED DESCRIPTION OF INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention is directed to develop a precise benefaction process for low-grade BHQ iron ore to obtain maximum weight recovery and grade.
To recover maximum iron bearing minerals from low grade BHQ iron ore was processed through stage wise beneficiation process involving:
• Stage-wise crushing of a BHQ boulder of 100 to 200 mm to below 3 mm
• grinding of 3 mm-sized crushed product to achieve 80% passing 45 µm size by adopting open circuit grinding.
• Processing of ground product in three stage magnetic separation (rougher, cleaner and scavenger HGMS) by applying various magnetic field intensity to recover the iron bearing minerals as concentrate.
• Further grinding of cleaner HGMS magnetic product and scavenger HGMS nonmagnetic product in another ball mill for further liberation of iron bearing minerals from silica at the size of below -38 µm 80 to 86% by adopting open circuit grinding.
• The ground product of cleaner HGMS magnetic product and scavenger HGMS nonmagnetic product was further treated through rougher HGMS to recover the Fe bearing minerals to increase the concentrate recovery as well as Fe grade and to reduce the tailing loss with lower Fe content.

The overall concentrate weight recovery obtained from the 3-stage magnetic separation process is 20.5–39.6%, with 60.4–63.8% Fe, 6.62–13.50% SiO2, 0.62–0.85% Al2O3, and 1.02–1.70% LOI. The overall final tailing loss through three-stage magnetic separation is 60.4 to 79.5% by weight loss with 14.8 to 20.7% Fe, 61.7 to 74.90% SiO2, 2.40 to 6.60% AL2O3, and 2.07 to 4.78% LOI. The overall Fe recovery is varying from 43.3 to 57.7%, and the silica reduction is varying from 75.5 to 80.2%.
The low-grade BHQ iron ore was collected from JSW mines in the Sandur–Hospet region. The BHQ sample consists of various alternative bands of hematite and quartzite. The size of the collected BHQ sample was varying from 100 to 200mm size. The chemical analysis of the collected BHQ sample is shown in Table 1. The feed sample consists of Fe 28.81 to 43.78%, SiO2 32.50 to 55.06%, Al2O3 2.25 to 3.42%, and LOI 1.90 to 2.85%.
Table 1: Chemical analysis
Fe,% SiO2,% Al2O3,% LOI,%
28.81 to 43.78 32.50 to 55.06 2.25 to 3.42 1.90 to 2.85

Detailed characterization studies have been carried out on a BHQ feed sample using an optical microscope. The phase analysis of the sample is shown in Table 2, and the liberation analysis is shown in Table 3. The micrographs of the collected BHQ samples are shown in Figure 1. The low-grade BHQ iron ore consists of 36.5 to 55.0% hematite as the major iron-bearing mineral and 33.50 to 53.0% quartzite as the major gangue-bearing mineral. The other minor iron-bearing minerals are magnetite and goethite, and the only minor gangue-bearing mineral is kaolinite.
Table 2: Phase analysis
Phase %
Magnetite 1.20 to 2.50
Hematite 36.5 to 55.0
Goethite 3.50 to 4.50
Quartzite 33.50 to 53.00
Kaolinite 3.70 to 4.50
Others 2.00 to 2.50

Table 3: Liberation analysis
Size, mm %
-150 µm 30 to 45
-75 µm 50 to 62
-45 µm 65 to 72
-38 µm 73 to 78
-25 µm 80 to 92

The low-grade BHQ sample of 100 to 200 mm in size was crushed using a laboratory jaw and roll crusher to obtain a crusher discharge of 100% 3 mm in size. The crushed material was subjected to a grinding process using a laboratory ball mill. In ground product maintained the particle size <45 µm 80 to 85%. The particle size analysis of the ground sample was shown in Table 4.
Table 4: Size analysis of ground sample
Size, µm %
-200 100.0
-150 100.0
-125 100.0
-75 96 to 98.39
-63 92 to 95.69
-45 80 to 85.69
-32 71.36 to 75.39
-25 61.23 to 65
-10 35.8 to 37.8
-2 14.50 to 16.50

The ground material was subjected to rougher HGMS. In rougher HGMS, magnetic field intensity was maintained from 8000 to 10000 gauss, preferably about 9000 gauss, flow velocity was maintained from 62 to 137 mm/s, preferably 88 mm/s, nozzle size was 5 to 7 mm, preferably 6 mm, and slurry density was maintained at 1.20 to 1.30 g/cc, preferable at 1.25 g/cc.
The developed process flow sheet for low-grade BHQ iron ore is shown in Figure 2.
The rougher HGMS magnetic (mag) product was further treated in cleaner HGMS for further enrichment of Fe content. The cleaner HGMS operating parameters are as follows: Magnetic field intensity: 5000 to 7000, preferably about 7000 gauss, flow velocity: 62 to 137 mm/s, preferably 88 mm/s, nozzle size: 5 to 7 mm, Preferably 6 mm, slurry density: 1.20 to 1.22 g/cc. In cleaner, HGMS obtained 15.6 to 27.6% magnetic concentrate weight recovery with 60.4 to 63.8% Fe, 6.62 to 13.50% SiO2, 0.62 to 0.85% Al2O3, and 1.02 to 1.70% LOI. The nonmagnetic product of rougher HGMS was further processed in scavenger HGMS for further upgrading. In this product the Fe content was very low. It requires subsequent magnetic separation stages for further Fe upgradation. The scavenger HGMS operating parameters are as follows: Magnetic field intensity: 10000 to 12000, preferably about 11000 gauss, flow velocity: 62 to 137 mm/s, Preferably 88 mm/s; nozzle size: 5 to 7 mm, preferably 6 mm; slurry density: 1.20 to 1.22 g/cc. In scavenger, HGMS achieved 10.3 to 13.4% weight recovery with 48.4 to 57.2% Fe, 15.10 to 26.50% SiO2, 1.527 to 2.06% Al2O3, and 1.63 to 2.01% LOI. The scavenger HGMS non-magnetic product was considered as final tailing, and it is ranging from 42.4 to 60.4% weight recovery with 14.8 to 20.7% Fe, 61.70 to 74.90% SiO2, 2.40 to 6.60% Al2O3, and 2.07 to 4.78% LOI.
Further to increase the concentrate weight recovery the cleaner HGMS non- magnetic product and scavenger HGMS magnetic product was further processedthrough rougher HGMS (recirculation) after grinding in ball mill 2 as open circuit grinding to get the ball mill discharge <38 µm 80 to 86.0%. After a few cycles, the stabilized recirculating load varies from 31.5 to 43.0%. After reprocessing of cleaner HGMS non-magnetic and scavenger HGMS magnetic product the weight recovery of the final product (cleaner HGMS magnetic) was increased from 15.6 – 27.6 to 20.5 – 39.6% without affecting the product Fe grade. The overall final tailing loss through three-stage magnetic separation decreased from 60.4 to 79.5% weight loss with 14.8 to 20.7% Fe, 61.7 to 74.90% SiO2, 2.40 to 6.60% AL2O3, and 2.07 to 4.78% LOI. The overall Fe recovery is varying from 43.3 to 57.7%, and the silica reduction is varying from 75.5 to 80.2%.The test results are shown in Table 5.
Table 5: Beneficiation process test results of low grade BHQ iron ore

, Claims:WE CLAIM:
1. A process for recovery of iron bearing minerals from low-grade BHQ iron ore comprising the following steps:
subjecting the 100 to 200 mm size low grade BHQ feed sample to stage wise crushing to get the product size <3mm;
grinding of crushed ore to achieve 80 to 85% passing <-45 µm; and
subjecting the ground product through three stage HGMS comprising of :
(a) carrying out rougher HGMS involving selectively
Magnetic field intensity: 8000 to 10000 gauss,
Flow velocity: 62 to 137 mm/s,
Nozzle Size: 5 to 7 mm, and
Slurry density: 1.20 to 1.22 g/cc
(b) carrying out cleaner HGMS involving selectively:
Magnetic field intensity: 5000 to 7000, gauss,
Flow velocity: 62 to 137 mm/s,
Nozzle Size: 5 to 7 mm, and
Slurry density: 1.20 to 1.22 g/cc
(c ) carrying out scavenger HGMS involving selectively
Magnetic field intensity: 10000 to 12000 gauss,
Flow velocity: 62 to 137 mm/s,
Nozzle Size: 5 to 7 mm, and
Slurry density: 1.20 to 1.22 g/cc,
to thereby recover the iron bearing minerals from said low grade BHQ iron ore feed sample.
2. The process as claimed in claim 1 wherein to further increase the concentrate recovery and grade recirculation of cleaner HGMS non-mag and scavenger HGMS mag products the same is further subjected to rougher HGMS, further grinding in the ball mill such as to achieve < 38µm < 80 to 86%.
3. The process as claimed in anyone of claims 1 or 2 wherein the low grade BHQ iron ore feed comprises of :
the Fe content in the feed sample varying from 28.81 to 43.78% and with the variation in other elements being as follows:
SiO2 – 32.50 to 55.06%
Al2O3 – 2.25 to 3.42% and
LOI – 1.90 to 2.85%.

4. The process as claimed in anyone of claims 1 to 3 wherein the mineralogical phases present in the feed sample are as follows:
Magnetite: 1.20 to 2.50%, Hematite: 36.5 to 55.0%, Goethite: 3.50 to 4.50%, Quartzite: 33.50 to 55.00%, Kaolinite: 3.70 to 4.50% and others : 2.00 to 2.50%.
5. The process as claimed in anyone of claims 1 to 4 wherein the liberation of iron bearing minerals at different size fractions in the feed sample is as follows: -150 µm : 30 to 45%, -75 µm : 56 to 62 %, -45 µm : 65 to 72%, -38 µm : 73 to 78%, -25 µm : 80 to 92%.
6. The process as claimed in anyone of claims 1 to 5 comprising subjecting the said low-grade BHQ iron ore sample to crushing and grinding followed by three-stage HGMS (rougher, cleaner, and scavenger) by maintaining various magnetic field intensities.
7. The process as claimed in anyone of claims 1 to 6, wherein in said
Rougher HGMS
Magnetic field intensity applied is 9000 gauss,
Flow velocity maintained is 88 mm/s ; and
Nozzle Size used is 6 mm.
Cleaner HGMS:
Magnetic field intensity applied is 7000 gauss,
Flow velocity maintained is 88 mm/s ; and
Nozzle Size: used is 6 mm
Scavenger HGMS:
Magnetic field intensity applied is 11000 gauss,
Flow velocity maintained is 88 mm/s ;and
Nozzle Size: used is 6 mm.

8. The process as claimed in anyone of claims 1 to 7 wherein the recovery and grade of final concentrate obtained by following said crushing, grinding followed by three stage magnetic separation including recirculation of cleaner HGMS mag and scavenger HGMS Non mag comprises maximum weight recovery varying from 20.5 to 39.6% with 60.4 to 63.8% Fe for input feed Fe 28.8 to 43.8%.
9. The process as claimed in anyone of claims 1 to 8 wherein the recovery of final product was increased from 15.6 - 27.6 to 20.5 to 39.6% after recirculation of cleaner HGMS non-magnetic and scavenger HGMS magnetic product after further grinding to < 38µm size 80 to 86%.
10. The process as claimed in anyone of claims 1 to 9 wherein the silica content in the final concentrate obtained by following said crushing, grinding followed by three stage magnetic separation including recirculation of cleaner HGMS mag and scavenger HGMS Non mag comprises 6.62 to 13.50% SiO2 with input feed SiO2 32.50 to 55.06%.
11. The process as claimed in any of claims 1 to 10, wherein the Fe content in the final tailing of the process is 14.8 to 20.7 percent and SiO2 is 61.70 to 74.90%; and
the Fe recovery in final concentrate is varying from 43.3 to 57.7% and SiO2 reduction is varying from 75.5 to 80.2%.

Dated this the 30th day of March, 2023
Anjan Sen
Of Anjan Sen & Associates
(Applicant’s Agent)
IN/PA-199