FIELD OF THE INVENTION
The present invention relates to a developed process to recover the
ferromanganese grade ore from low grade ore fines.
BACKGROUND OF THE INVENTION
Manganese ores are primarily used in the ferromanganese making and these
ferroalloys are used in steel making process to refine the steel. Quality of
ferromanganese depends on the feed grade ores and the ore should contain
Mn: 38-48% and Mn/Fe >5.5 to produce the high carbon ferromanganese.
High-grade manganese ore lumps (+10mm) are supplied to the
ferromanganese plant and the low-grade fines generated in this process are
disposed at waste dumps. These fines usually contain Mn: 25-40% and
Mn/Fe: 1-2.5. The high-grade manganese ore resources are depleting rapidly
and there is huge demand of these ores. There is an economic sense to
beneficiate the low-grade manganese ore fines to generate the
ferromanganese grade ores. Three different types of low-grade manganese
ore fine samples were collected from Keonjhar district of Orissa and a process
flowsheet has been proposed to recover the ferromanganese grade ore
concentrate.
Mineral association and liberation characteristics play a vital role in developing
a beneficiation methodology. Characterization and liberation studies were
carried out for the low-grade manganese ore fines generated in the mining of
high-grade manganese ores at Joda manganese mines (Orissa). These low-
grade fines contains manganese minerals (mainly Pyrolusite, Pislomelane
minor of Jacobosite, Braunite, Cryptomelene), Iron Minerals (Hematite,
Goethite, Limonite) and Gangue Minerals (Quartz, Feldspar, Mica, Calcite,
Apatite, Diopside, Amphibole, Chlorite). It was found that 40-45, 35-45 and

40-45% manganese, iron and gangue minerals are in liberated form,
respectively. The mineral association was found between all the three mineral
categories and 25-35%, 30-35% and 25-30% manganese-iron, manganese-
gangue and iron-gangue minerals were associated, respectively.
Characterization studies directed to explore magnetic separation, heavy media
separation, and reduction roasting methods to develop a beneficiation process
flowsheet.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a developed
process to recover the ferromanganese grade ore from low grade ore fines
which eliminates the disadvantages of the prior art.
Another object of the present invention is to propose a developed process to
recover the ferromanganese grade ore from low grade ore fines which saves
national geological property.
A further object of the present invention is to propose a developed process to
recover the ferromanganese grade ore from low grade ore fines which saves
the economic value of mineral.
A still further object of the present invention is to propose a developed
process to recover the ferromanganese grade ore from low grade ore fines
which is eco-friendly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig 1- Process flowsheet for beneficiation of low-grade Mn ore fine to high
grade ferromanganese ore

BRIEF DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The present invention relates to a developed process flow sheet to produce
ferromanganese grade ore concentrate from low-grade ore fines from run of
mines. The proposed process comprising a two stage of seperation-
1st stage of Ore Concentration: The run of mine ore fine samples having
composition [Mn: 25.7-36.8, Fe: 11.7-15.5, SiO2: 3.0-37.0, AI2O3: 1.8-3.5,
Mn/Fe: 2.2-2.4, Wt(%): 100] were crushed in <10mm size (1) and classified
I at 0.05mm (2) to remove unwanted gangue and iron minerals. This process
can remove 42-47%; 30-47% and 24-30% alumina, silica and iron,
respectively and the rejected (1) part contains [Mn: 11.7-27.6, Fe: 11.7-17.70,
SiC>2:6-52.0, Wt(%): 23-26.1]. The manganese recovery was found between
80-88.09% for the process. This material was further concentrated by heavy
media separation (3) and a liquid of 2.88 density was used. The manganese
losses in the process varied between 1 and 3.5% with the weight losses
between 5.5 and 12.2% and the rejection (2) contains [Mn: 2-7, Fe: 1.5-12.7,
SiO2: 15-70.5, Wt(%): 5.5-12.2]. The concentrated product was crushed in
<3mm size (4) and passes through high intensity magnetic separator (5) at
11000-13000 gauss to separate the magnetic and nonmagnetic fraction. A
product of desired grade was achieved after the 1st stage with the manganese
recovery 38-42% and the weight recovery was 25-31%. The manganese
content was found between 38 to 47% and Mn/Fe ratio was ~5.5. [Stage 1
product- Mn: 38.6-47, Fe: 7.5-8.6, SiO2: 18.4-20.2, Mn/Fe: 5.5-5.7, Mn
Recovery: 39-44, Wt(%): 27-31]
IInd stage of Ore Concentration: In the first stage of beneficiation i.e.
Stage I Product[Mn: 38.6-47, Fe: 7.5-8.6, SiO2: 18.4-20.2, Mn/Fe: 5.5-5.7,
Mn Recovery: 39-44, Wt(%): 27-31] recovery of the manganese minerals was
low and it was tried to improve the recovery of minerals by reduction roasting
(6) followed by low intensity magnetic separation (7). The optimum

temperature for roasting was 650°C to achieve Mn/Fe >5.5 for the size range
0-3mm. The coal of l-3mm size range was used as a reductant and 15% coal
was mixed in the ore and kept at 650°C for 30 minutes. The reduction
roasting of the magnetic fraction can improve the manganese recovery ~18%
with the increased weight recovery of ~12%. The overall process recovery
was found between 55 to 62% and the weight recovery was between 37 to
44% and the rejected (3) part contains Mn: 28.8-36.2, Fe: 21-24, SiO2: 15-
36.2, Wt(%): 20.1-23.3.

WE CLAIM
1. A developed process to recover the ferromanganese grade ore from
low grade ore fines comprises a two stage of ore concentration which
comprises
- a first crushing (1) the run of mine ore fine sample below 10
mm size;
- classifying (2) at 0.05mm to remove wanted gangue and iron
minerals;
- a heavy media separation (3) and liquid of 2.88 density was
used;
- a second crushing (4) to make below 3mm size;
- a first high intensity magnetic separation (5) to separate
magnetic and non-magnetic fraction;
- a reduction roasting (6) with coal;
- a second low intensity magnetic separation (7);
Characterised inthat the said process yield overall 55 to 62% recovery and
weight recovery 37 to 44% and Mn/Fe >5.5.
2. The process as claimed in claim 1 wherein after 1st stage of
classification manganese recovery was found 80 to 88.09%.
3. The process as claimed in claim 1 wherein after heavy media
separation, manganese losses between 1 to 1.5% and weight losses
between 5.5 to 12.2%.
4. The process as claimed in claim 1 wherein the high intensity magnetic
separator applied at 11000-13000 gauses.

5. The process as claimed in claim 1 wherein after high intensity magnetic
separator manganese recovery 38-47% and weight recovery was 25-
31%.
6. The process as claimed in claim 1 wherein the reduction roasting is
carried out using coal of 1-3mm size and 15% coal was mixed in the
ore and kept at 650°C for 30 min.
7. The process as claimed in claim 1 wherein after reduction roasting, the
manganese recovery is 18% with the increased weight recovery of
12%.
Dated this 16th day of April 2008

A developed process to recover the ferromanganese grade ore from low grade ore fines comprises a two stage of ore concentration which comprises
- a first crushing (1) the run of mine ore fine sample below 10 mm size;
- classifying (2) at 0.05mm to remove wanted gangue and iron minerals;
- a heavy media separation (3) and liquid of 2.88 density was used;
- a second crushing (4) to make below 3mm size;
- a first high intensity magnetic separation (5) to separate magnetic and non-magnetic fraction;
- a reduction roasting (6) with coal;
- a second low intensity magnetic separation (7);
Characterised inthat the said process yield overall 55 to 62% recovery and weight recovery 37 to 44% and Mn/Fe >5.5.