the students of the group ЕМ – 10 1/9Yuhno A.

Muravyov E.

Rational Technology of Fe-Si 45 Production Process

Ferrosilicon is alloy of silicon and iron. It is mainly used as a dioxidant and alloying element in producing steel.

Grade

Mass fraction of elements, %

SiMn C P S

Not more

Fe-Si 45from 42 to

47 inclusive1.0 0.8 0.06 0.02

Fe-Si 45 requirements

The alloy characteristics and use

IndicatorWeight for quartzite fractions 25-

80 (CM-80)

More than max D,% by mass 15

Less than max d,% by mass 7

CharacteristicsMetallurgical quartzite fractions

25-80Fraction weight SiO2,% 97,5+0,2А1203, % not more 1,5

Fe203, % not more 0,6

Moisture,% max 5,0Loss of weight on ignition,% max -

Fraction requirements

Metallurgical quartzite requirements

The charge materials characteristics. Metallurgical quartzite.

SiO2 + SiFe = 2SiO;

SiO + C = Si + CO.

 As an intermediate product formed at 1700 о C carbide silicon is

SiO + 2C = SiС + CO.

At the appropriate temperature silicon carbide destroys iron:

SiС + Fe = FeSi+ C

For that part of the silicon which forms iron silicide the reaction is :

SiO2 + 2C = Si + 2CO2

Si+ Fe= FeSi

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SiO2 + 2C + Fe = FeSi + 2CO2

Figure 1.1 - Diagram of the Fe-Si

Physico-chemical basis of the process

Theoretical temperature of the recovery silica with carbon by reaction:

 SiO2 + 2C = Si + 2CO is (ΔGo = 0 at T = 1962 K), and eutectic temperature in the system FeO - SiO2 T = 1451 K. The reaction of silicon recovery from silica using solid carbon is

performed by the total reaction :

SiO2 + 2CО = 2CO2 + Si; ∆H = 306,18 kJ/mol

2CO2+ 2C= 4CO; ∆H = 345,392 kJ/molSiO2 + 2C = Si + 2CO; ∆H = 651,572 kJ/mol

During the silica process the pressure on the throat is equal to atmospheric and in the area of silicon recovery it is a bit higher than atmospheric. Due to the iron which dissolves silicon in the reaction zone the balance shifts to the right and recovery of the silica starts at 1150 о C.

Physico-chemical process

the formation of silicon carbide by the interaction of silica dioxide with quartzite and solid carbon from coke;

retention by coke carbon gaseous silicon monoxide , which is formed in the lower high-temperature horizon of the throat and rises to the upper horizon. As a result of this reaction silicon carbide is produced;

the exothermic reaction of disproportionation. This is the process of disintegration of gaseous silicon monoxide, carbon coke which has not been detained on silicon and fine (powdered) silica.

1) carbon monoxide in a state of gas all the time allocated from the furnace, so achieved a high degree of extraction of the lead element from the ore (up to of 95-98%);

2) Affinity of carbon relative to oxygen increases with increasing temperature, which makes it possible to restore various oxides;3) Carbon is a cheap reductant. As carbon reductant elements can be used: coke, nut coke, anthracite, wood sawdust, peat coke and pitch;

ParametersValue

min max

Operating voltage 150 V 210 V

Current 35000 A 70000 A

Current/voltage relation 230 330

Pressure 2 Pa 5 Pa

Parameters of the normal run of the furnace

1. Even gas evolution on the entire surface of the throat.

2. Absence of dark sintered areas and local excessive gassing – “fistulas”.

3. Even chargefall near the electrodes and in the triangle between them.

4. Stable submergence of electrodes deep in the charge.

5. Stable downloading of charge.

6. Regularly output of rare movable slag in each output of the melt.

The technological process is characterized by: