fastment process in mineral processing engineering

1. FASTMET PROCESS
PRESENTED BY WAYNE CHIKWANE
DUDUZILE SELOME
VELAPHI MOYO
MELULEKI MOYO
NKOSINAMANDLA MOYO

2. INTRODUCTION
• FASTMET is a unique process which uses a Rotary Hearth Furnace (RHF) to
reduce agglomerates containing coal with a high reduction ratio and high
productivity.
• The process converts iron ore pellet feed, iron ore fines and metallurgical waste
from the steel plant into direct reduced iron using pulverized non coking coal as a
reductant.
• The FASTMET process is different from the gas-based reduction process using
reforming gas derived from natural gas, in that it heats and reduces composite
agglomerates, each consisting of iron ore, or steel mill waste, and coal.

3. cont
• The process involves rapid heating of the agglomerates placed in one
or two even layers by radiation heat to accomplish a rapid reduction
reaction in a rotary hearth furnace. This prevents the oxidation of the
agglomerates besides the in- furnace combustion exhaust gas which
has a high oxidation potential.
• The combustible gas ( CO) generated from the carbon in the
agglomerates undergoes secondary combustion above the
agglomerates. This suppresses the emission of NOx despite the fact
that the furnace is being operated at high temperatures.
• The reduced iron can either be fed into a blast furnace or directly into
a melting process

4. FASTMET PROCESS FLOW

5. REDUCTION IN FASTMET FURNACE

6. DESCRIPTION OF THE PROCESS
• The FASTMET process includes mixing steel mill waste consisting mainly of fine
ore (i.e., iron oxide) with pulverized coal, agglomerating the mixture into pellets
or briquettes using a pelletizer or a briquetter, drying the agglomerates in a dryer,
and placing the agglomerates over the hearth of an RHF in one or two even layers
.
• The agglomerates (pellets or the briquettes) must be isolated from air when they
enter the furnace , otherwise oxidation of the agglomerates will occur in the
furnace instead of reduction
• Their feed rate must be controlled precisely to ensure a uniform bed height in the
hearth
• FASTMET contains a feed pipe system enabling the adjustment of the number of
pipes according to the size of the furnace, thus simultaneously achieving isolation
from the air and feed rate control

7. cont
• A screw-type levelling system is adopted for placing the agglomerates in one or two even
layers.
• This is then followed by heating the pellets or briquettes using radiation heat rapidly
attaining a high temperature of 1,350℃.
• Once the composite pellets are heated, carbon monoxide inside them, promote the
reduction of iron oxide. Thus the reduction reaction proceeds faster in the carbon
composite pellets/briquettes than the reduction reaction happening in the conventional
direct reduction process. The following reactions occur in the furnace:
1. Fe2O3 + C → 2Fe ＋ 3CO
2. Fe3O4 ＋ 4C → 3Fe ＋ 4CO
3. Fe2O3 ＋ 3CO → 2Fe ＋ 3CO2
4. Fe3O4 ＋ 4CO → 3Fe ＋ 4CO2
5. FeO ＋ CO → Fe ＋ CO2

8. cont
• At temperatures below the melting point of iron, there is hardly any direct reaction
with the solid carbon of pulverized coal and hence the reaction given in equation 1
dominates the reaction kinematics.
• At elevated temperatures of 1000 0C and more, the reaction of the generation of
carbon monoxide by carbon solution loss and the reaction of iron oxide with the
generated CO take place in series inside the carbon composites pellets.
• CO gas generation controls the reaction kinematics with its highly endothermic
nature. Hence to promote the reaction, it is essential to supply the heat required for
the formation of CO.
• This means heat must be transferred efficiently by radiation from the atmosphere
to the surface of the pellets, and by conduction from the pellet to its interior.

9. cont
• Dwelling for 8 to 16 minutes, the agglomerates are converted into direct reduced
iron ("DRI"), which is discharged out of the furnace or supplied to the
downstream process, at a temperature of 1200 - 1000℃.
• The residence time varies depending on the material being processed, size of
pellets/briquettes, and other factors.
• The rapid reduction rate achieved in the FASTMET process is due to the high
reduction temperature, the high heat transfer rate, and the intimate contact of the
carbon contained inside the briquettes with the iron oxide
• The heat transfer is shown on slide #5 together with the reactions that take place in
the RHF.

10. PRODUCTS
• The DRI, discharged out of the furnace, is either transferred to a
melting furnace in a transportation container, or is cooled and supplied
into a blast furnace
• The DRI has many pores left after the reduction process. If exposed to
air for a long time, the metallic iron reoxidizes into iron oxide,
deteriorating its quality.
• If DRI is not used immediately as raw material for a melting furnace
or a blast furnace, compacting and densifying the DRI into hot
briquette iron (HBI) prevents reoxidation.
• This allows the storage of reduced iron for an extended period of time
without quality degradation.

11. cont
• The metallization achieved during the FASTMET process is more than 85% and
the hot metal has the following typical composition:
• Carbon – 3.0 % to 5.0 %
• Silicon – 0.3 % to 0.6 %
• Manganese – 0.6 % to 1.2 %
• Sulphur – <0.05 %
• Phosphorus – < 0.03 %

12. • The combustion gas (CO gas) emitted from the pellets/briquettes as a result of the
reduction reaction can be used as a fuel for the RHF, which significantly decreases
the amount of fuel supplied to the burner.

13. ADVANTAGES OF FASTMET PROCESS