Page 19 - Mines and Minerals Reporter eMagazine - Volume December 2024

IRON ORE MINING

No. Characteristics Data RESULTS AND DISCUSSION
NMDC iron ore mine, MASSIVE HIGH GRADE ANHYDROUS IRON OXIDE
1. [1]
Donimalai, Karnataka ORE FROM DONIMALAI, KARNATAKA
Hard lumpy/laminated The massive hard lumpy/laminated high grade iron ore with
2. Physical high grade iron ore with *30 % fines assaying 64.90 % Fe, 2.06 % SiO2, 0.60 % FeO, 2.13
*30 % fines
% Al2O3, 0.05 % P, 0.03 % S, 1.72 % LOI and containing hematite
64.90 % Fe, 2.06 % SiO2, [94 %], quartz [2 %], clay [4 %] goethite and martite[Tr] was the
0.60 % FeO, 2.13 % Al2O3, easiest ore that needs little beneficiation. The DAT produced
3. Chemical
0.05 % P, 0.03 % S, 1.72 a[67 % Fe concentrate with*90 %Fe recovery at 86 %yield. The
% LOI
results are given in Table 1. The process consists of primary,
Hematite [94 %], quartz [2 secondary, tertiary crushing in closed circuit with 100, 30 and
4. Mineralogy %], clay [4 %] goethite and 10 mm screens, classification of -10 mm fines produced a
martite[Tr] lumpy and sinter grade concentrate assaying[65 % Fe with 90
% Fe distribution similar to the results enumerated by IBM [1].
DAT: deslime, sink float[3SG], >67 % Fe concentrate with
5. isodynamic mag separation of sinks *90 % Fe
at -0.25 mm recovery at 86 % yield ALLUVIAL SANDS FROM RATNAGIRI,
MAHARASHTRA

Process: primary, secondary, >65 % Fe lumpy and sinter
tertiary crushing in closed circuit concentrate [-100 ? 30 and The black marine sands from Ratnagiri, Maharashtra assaying
6.
with 100, 30, and 10 mm screens, -30 ? 10 mm] and [-10 ? 0.1 10 % Fe containing mainly quartz with minor to sub ordinate
classification of fines mm] at *90 % yield amounts of free magnetite was the easiest to upgrade. The
DAT produced a[62 % Fe concentrate with *90 % Fe recovery
Table 1 Massive hard high grade anhydrous iron oxide ores at 8.6 % yield. The process comprised of particle size refining
by wet screening over 1 and 0.05 mm and WLIMS of -1 ?
MATERIALS AND METHODS 0.05 sand fraction yielded a sinter/pellet grade magnetic
concentrate assaying[67 % Fe with 75 % Fe recovery at 6 wt%
Iron ore samples from Donimalai [1], Bellary [3], Chitradurga yield. Mandre et al. [5] incidentally obtained similar results by
[4], Hospet [5], CN Halli [6], Sandur [6] from Karnataka, Gonda, WLIMS of black sands from Ratnagiri. The results are given in
Ratnagiri [2] from Maharashtra, Odisha and Goa [7] were Table 2.
collected for the above study. The samples were subjected to
standard feed preparation and sampling methods. The DAT
is as follows. The original sample was subjected to detailed
mineralogical and chemical analysis. A representative portion
of the sample as received was dry ground to -0.2 to 0.1 mm
based on degree of liberation, wet sieved over 500 mesh to
reject slimes [-500 mesh]. The sand fraction was subjected
to heavy liquid separation at 2.96 specific gravity using TBE
and also the sand fractions, sink and float products were
subjected to hand magnet, Frantz Iso dynamic separator at
various intensities. Mineral processing studies comprised of
controlled crushing and grinding (if needed), wet screening
for particle size refining to study the amenability of sample
to washing and particle size refining for high grade massive
ores and friable clayey iron ores and WLIMS for alluvial sands.
The siliceous iron ores and BMQ were subjected to controlled
closed circuit grinding with screens to liberation size followed
by gravity and magnetic separation processes. The BHQ
was subjected to fine grinding to unlock quartz followed by
wet high intensity high gradient magnetic separations. The
complicated ores like massive hydrated iron oxide ores, Mn Fig. 1 Clayey iron ore hematite (He) inclusions within the ferruginous clay/
bearing iron ores and Ti magnetite were subjected to chemical limonite (Fe Cl/Li). Free ferruginous clay/limonite (Fe Cl/ Li) and hematite
processing methods. (He) grains are seen in <400 lm size sample. (Reflected light, 920, air)

DECEMBER 2024 / MINES & MINERALS REPORTER 17