FIELD OF THE INVENTION
This invention relates to a process for making composite agglomerates
utilizing ferromanganese plant waste as charge material for submerged arc
furnace which comprises making briquettes by extrusion method consisting of
fine and moist ultrafine manganese containing material obtained from gas
cleaning plant (GCP) sludge of ferromanganese plant and coarse manganese
ore fines in combination, such that the composite briquette contain not less
than 30% coarse (+3mm) manganese bearing material not less than 5% in
the composite briquette.
BACKGROUND OF THE INVENTION
Mining and sizing operations of manganese ore generate fines containing 25
to 40% Mn. Production of manganese alloys in the submerged arc furnace
generates metal and wastes such as slag, off-gas and fine dust. The fine
suspended dust is collected by scrubber and fed to a thickener. The thickener
underflow is sent to storage pit while the overflow of the thickener which is
clean water, recycled back to gas cleaning circuit. The sludge from the
storage pit is taken out and stacked in pile on the ground. Due to fine particle
size, high moisture content and presence of alkali, this material cannot be
recycled back as it is, to the furnace hence, need to be agglomerated.
Stringent regulations for the suppression of pollutants from ferroalloy
industries and increasing costs of raw materials has made it imperative to
recycle as much as possible the by-products from such plants. Ferro alloy
industry generates a wide variety of by-products rich in manganese / chrome,
which have a potential for recycling back. Since these by-products generally
have fine particle size, they cannot be, as such recycled back to the furnace,
hence, need to be agglomerated. Sintering, pelletizing and briquetting are
three principle technologies used for agglomeration of ores and concentrates.

Most of the ferroalloy (Fe-Cr) manufacturer’s particularly small producers use
ore fines due to its low cost and easy availability. The raw materials used for
smelting of ferroalloys in submerged arc furnaces are preferably lumps (25 to
150mm size), agglomerates and fines (<6mm size). Smooth and efficient
operation of manganese ferroalloys smelting furnace is achieved when closed
sizing control of raw material is practiced. Fines in the raw material are
detrimental, causing poor charge porosity, resulting in high power
consumption per ton of alloy produced, may cause pressure excursion inside
the furnace, excessive fume and dust losses and low productivity. As the
advantages derivable with the use of agglomerates in one or other form are
quite high, efforts must be made for switching over to agglomerates and
eliminate direct charging of fines in the furnaces. The three available
processes for agglomeration are sintering, briquetting and pelletisation. High
capital investment coupled with introduction of gangue through solid fuel
prohibits the use of sintering process. While sintering is one of the proven
process for agglomeration of high grade manganese fines, it will be essential
to locate sintering plant near the ferro manganese plant in order to avoid
undue fine generation by sinter handling. Briquetting is most commonly used
as the investment is quite low and the process is simple. On the other hand,
pelletisation although capital intensive is preferred by large producers due to
possibility of utilizing high grade concentrates which are available in very fine
form. In addition, the physical properties of the pellets are far superior to
briquettes, which can withstand degradation during processing for preheating
and even for pre reduction.
Prior art (IN2012KO00879) discloses a process, for making extruded briquette
produced by the stiff vacuum extrusion method for preparation of charge
materials for the production of ferro alloys in ore smelting furnaces. Particle
sizes of the substances in the charge for the BREX production do not exceed

5mm and the BREX mass do not exceed 0.5kg. A process for making
briquettes as a charge material for blast furnace from steel industry waste
(iron making and steel making waste) by stiff extrusion method is disclosed
(IN2012KO00687). Another disclosure (RU2506326) refers to ferrous
metallurgy, for making briquette by stiff vacuum extrusion method with
mineral binding agent, an iron-ore concentrate and/or iron ore, carbon-
containing materials for blast-furnace charge component. There are few
relevant prior art which discloses the process of converting steel industry
wastes as feed charge, however there is no clear information available on
direct utilization of fine ferromanganese dust and ore fines with high moisture
content. The challenge is to develop a techno economical viable process
which can be used to convert such anthropogenic material (sludge and fines)
into a suitable feedstock for electric arc furnace or mini furnaces
OBJECTS OF THE INVENTION:
• The object of the present invention is to propose a method for
producing reactive composite agglomerates comprising of manganese
bearing fine and moist materials and wastes.
• Another object of this invention is to propose a method to utilize the
ferromanganese plant waste and manganese ore fines for producing
ferromanganese;
• A still another object of the invention is to propose a low cost method
of producing feedstock for sub-shaft furnaces producing manganese
alloys.

SUMMARY OF THE INVENTION:
Accordingly, there is provided a method for producing reactive composite
extruded agglomerates from ultrafine and wet (moisture in the range of 10 to
35%) sludge and fines having high manganese content. The method
comprises of the following steps: (1) Mix the raw material in suitable weight
ratio preferably 60:40 (sludge and fines) and homogenize with suitable
plasticizer and binder. (2) Feed the prepared mix in the feed chamber of
extruder (3) The mix is moved by screw and vacuum is applied in the
chamber containing homogenized mass in order to remove the entrapped air.
The vacuum is applied in such a manner to ensure maximum removal of
entrapped air/gases as well as moist air. The homogenized charge mixture
produced for extrusion is in such a manner that the moist ultrafine material is
not less than 30% and the coarse manganese bearing (+3mm) material is
not less than 5% in composite briquette on dry basis. The top size in the mix
is 10mm. The present invention also enables the use of coarse size fraction
(+6mm) in extrusion process to the extent up to 10% by weight and the
extrusion process is operate at high moisture levels up to 25% by weight.
The produced composite agglomerates are comparatively reactive material
compared to conventional lump feed due to high porosity which enables the
enhanced reduction inside the sub shaft furnaces such as submerged arc
furnace, rotary hearth furnace. Composite agglomerate comprise of carbon
reductant and suitable slag formers such as pyroxinite fines and or lime or
combination thereof, which helps in early slag formation and enhanced
prereduction of reducible oxides in manganese bearing ore or feedstock such
as iron oxide and lower oxygen containing manganese oxides. The method
can produce agglomerates at higher moisture containing mixture in the range
of 5 to 25% by weight. The disclosed method is low cost since drying of feed
stock is not required and with suitable combination of binder the manganese
bearing composite agglomerated with acceptable strength for sub shaft

furnace operation can be produced. It’s dust free process and can be
environmental friendly.
The invention thus provides:-
A process for producing reactive composite agglomerate for recovering metal
values from ferromanganese waste in an electric arc furnace, the process
comprising the steps of: forming a sludge of a ferromanganese waste, the
ferromanganese waste having chemical composition (all in wt. %) Mn: above
38, Fe(T): 4.65 CaO: 2.58, SiO2:7.4, MgO: 3.79, Al2O3: 4.07, K2O: 3.642,
LOI: 6.88, Na2O: 0.257, C: 1.44, P: 0.28 and size of <45 micron and moisture
content of 10% to 40% (by wt.); adding a manganese ore fines in the sludge
with chemical composition (all in wt. %) Mn- above 35, Fe(T)- above 16,
CaO- 0.001- 0.97, SiO2- 2-13, MgO - 0.001-0.15, Al2O3; 4.0 -10.0, K2O- 0.64-
0.88, LOI-about 12, Na2O- about 0.21, , P; 0.11-0.15, and size distribution of
-10mm and +6mm and up to 15% moisture (by wt.); mixing the sludge and
the manganese ore fines to form a mix; adding binder upto 5% (by wt.) of
the mix and mixing; adding water to make moisture content in the mix with
the binder upto 25% (by wt.); and extruding the mix with stiff vacuum
extrusion means applying 10-20 MPa.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 Granulometry of sludge
Figure 2 Extruded briquettes from the extruder
DETAILED DESCRIPTION OF THE INVENTION:
A 4kg batch feed mix is prepared using stoichiometric ratios sludge,
manganese ore fine and binder. The calculations for material balance were
done on dry basis with actual moisture content of the sludge, fines and
binder. The moisture is determined on dry basis using laboratory moisture

analyzer (RADWAG PMR 210/NH). The moisture content of the sludge varies
from 10% to 40% whereas the fines moisture varies from 1% to 12%. Size
distribution of manganese ore fines are carried out in lab scale sieve shaker
(RX-29-16). The size distribution of the sample is given in table 1. The sludge
being ultrafine in nature, the size analysis was carried out in a laboratory
camsizer (fig.1).

Raw material mix combined with water was first homogenized in a laboratory
Hobart mixture. The feed mix is then taken out from the Hobart mixture and
a small sample was analyzed for the moisture content of the mix. Due to
thixotropic nature of the raw material, after the bentonite, water addition,
and before the cement addition, the moisturized mix was sheared once in the
lab extruder. This creates better water distribution and enhances plasticity of
the mix body. Particle size distribution improves the extrudability of the
material. This high pressure and shear has the added benefit of intensively
mixing the materials to a high degree of homogeneity. Once the material is
sheared, sample was taken to check the moisture of the feed mix. After
evaluating the moisture of the feed after shearing, the material was fed in the
extruder feed chamber. The laboratory extruder consists of two chambers
with a sealing die between. The rear chamber is fitted with a feed hopper,
from where the material is fed into the chamber. The feed mix

passes through a shear plate into the second chamber. The second chamber
contains vacuum facility. In this chamber the material is subjected to intense
vacuum prior to extrusion in order to remove all of the compressible air from
the material before it is compressed under high pressure. The application of
the vacuum has its result in the lower content of the binder required for the
briquette to achieve the desired level of strength as compared to
conventional briquetting technologies. It is also fitted with a screw auger that
extrudes material through the die of required diameter. It can also be fitted
with a shearing plate for proper shear of the material. Then the mix was
processed through in the laboratory extruder under vacuum. The laboratory
extruder simulates the feed material through the sealing auger and die, into
the vacuum chamber, and then final extrusion. For the lab extrusion process
<-3mm fractions were taken, as +3mm fractions will block the extruder. The
detailed feed mix with moisture content is presented of one test is given in
table 2.



The mix was then fed in the lab extruder. The feed mix was first placed in the
second chamber and extruded using the shear plates. Once the material is
sheared the moisture of the mix was taken using the moisture analyzer. Then
the total mix was fed in the rear chamber and extrusion process was carried
out. The feeding rate was kept low keeping in view of the extrusion rate. The
extrusion data like die pressure, temperature etc., were recorded in PC-based
data system. The extruded briquettes produced from the extruder are shown
in fig. 2.
The feed mix and the green briquettes were subjected to moisture analysis.
The moisture of the briquettes varies from 20% to 26% based on the
proportion of feed mix. The briquettes were kept for drying under normal
atmosphere or room temperature. After curing for seven days the briquettes
were subjected to cold compressive strength to understand the compression
strength of the material and to withstand the load in the bunker. To
understand the reactive nature of the composite briquette, porosity,
reducibility index (RI) and reduction disintegration index (RDI) were
calculated. The test result and its comparison with conventional composite
are given in table 3.


Advantage:
Comprise of partly reduced low oxygen containing reducible iron and
manganese oxides, carbonaceous reluctant an low temperature slag formers
and suitable binders or plasticisers.

WE CLAIM:
1. A process for producing reactive composite agglomerate for recovering
metal values from ferromanganese waste in an electric arc furnace,
the process comprising the steps of:
forming a sludge of a ferromanganese waste, the ferromanganese
waste having chemical composition (all in wt. %) of Mn: above 38,
Fe(T): 4.65 CaO: 2.58, SiO2:7.4, MgO: 3.79, Al2O3: 4.07, K2O: 3.642,
LOI: 6.88, Na2O: 0.257, C: 1.44, P: 0.28 and size of <45 micron and
moisture content of 10% to 40% (by wt.);
adding a manganese ore fines in the sludge with chemical composition
(all in at. %) Mn- above 35, Fe(T)- above 16, CaO- 0.001- 0.97, SiO2-
2-13, MgO - 0.001-0.15, Al2O3; 4.0 -10.0, K2O- 0.64-0.88, LOI-about
12, Na2O- about 0.21, , P; 0.11-0.15, and size distribution of -10mm
and +6mm and up to 15% moisture (by wt.);
mixing the sludge and the manganese ore fines to form a mix;
adding binder upto 5% (by wt.) of the mix and mixing;
adding water to make moisture content in the mix with the binder upto
25% (by wt.); and
extruding the mix with stiff vacuum extrusion means applying 10-20
MPa.
2. The process as claimed in claim 1, wherein the binder is cement or
plasticizer or there combination.

3. The process as claimed in claim 1, wherein the reactive composite
agglomerate have strength of >100kgf.
4. The process as claimed in claim 1, wherein the reactive composite
agglomerate have porosity of >25%.
5. The process as claimed in claim 1, wherein the reactive composite
agglomerate have reducibility index (RI) >75%.
6. The process as claimed in claim 1, wherein the reactive composite
agglomerate has moisture in the range of 10-25%.
7. The process as claimed in claim 1, wherein the electric arc furnace has
low or minimal shaft height.