Organization of production of metallized pellets technology Midrex of brown iron ore deposits Velihovskogo for high quality grades of steel rails Aktobe rail and plant

Organization of production of metallized pellets technology "Midrex" of brown iron ore deposits Velihovskogo for high quality grades of steel rails Aktobe rail and plant

Student: Alimbaev S.A.

Scientific adviser: Ph.D., Kaskin K.K.

Currently Aktobe rail and plant commissioning are on a hot reheating furnace. It is planned to produce 430 thousand. Tons of high quality steel a year, including 200 thousand. Tonnes of thermomechanical rail length of 120 meters for the high-speed rail lines, as 230 thousand. Tons of rolled steel - beams, angles, channels.

In the future, rail and Aktobe plant is planned, construction of the steel plant for import substitution of imported steel - blooms and economically cheaper production costs 2 - 4 times.

Due to the growing needs for iron ore with high requirements on the content of harmful (S - 0,001%, P - 0.01%) and non-ferrous contaminants, (Pb, Cu, the As <0,01%; Zn <0,003%). We offer the production of metallized pellets technology "Midrex", with brown iron ore (Fe2O3 content of 48 - 50%) Velihovskogo fields of Aktobe region.

The offered project is as follows:

1. Preparation of brown iron ore (crushing, grinding, wet magnetic separation, filtration) to obtain iron ore concentrate Fe 67 - 68%;

2. Agglomeration to obtain green pellets diameter of 8 - 25 mm;

3. Drying and calcination at temperatures of 1200 - 1300 ⁰C at the burning car "Lurgi" oxidized to obtain pellets;

4. metallization furnace Shakhno "Midrex" to produce metallized pellets Fe_total - 95%, Fe_met - 90%;

5. Submission of metallized pellets hot 800 - 850 ⁰C in an electric arc or ore-smelting furnace.

Velihovskoe burozheleznyakovyh ore deposit located in the contours of the balance of nickel and titanium-magnetite ore. The average content of Fe in the ore 48%, Ni – 0,49%, TiO₂ – 2,16%, Co – 0,067%, Cr₂О₃ – 1,2%, Al₂O₃ – 12,06%, SiO₂ – 23,92%, P₂О₅ – 0,03%, S – 0,049%.

For concentrate with Fe content of 67 - 68% is necessary to prepare limonite on the following scheme: (Figure 1).

Figure 1 - Technological scheme of brown iron ore beneficiation:

1 - ore conveyor; 2 - bin ore; 3 - a conveyor belt; 4 - Cascade mill; 5 - sump; 6 - vibrating screen; 7 - electromagnetic separator; 8 - the pump; 9 - hydrocyclone; 10 - ball mill; 11 - bunker desliming; 12 - winding demagnetization enriched product; 13 - three-drum magnetic separator; 14 - drum filter; 15 - conveyor concentrate; 16 - concentrate tank; 17 - pump tailings; 18 – tails

To intensify the process of pelletizing, crushing strength and increase resistance to dynamic loads, to the iron ore concentrate in a binder is applied during pelletization bentonite and 7 kg per 1 ton. Concentrate and bentonite to the feed bins before pelletizing are thoroughly mixed in a mixer with two high speed rotors. Humidity is regulated charge supplying water to the mixer. The charge, blended in a mixer is supplied to the drum pelletizer, where the process of forming the green pellets with diameter 8 - 25 mm (Figure 2).

Figure 2 - The technological scheme of the pelletizing and sieving pellets

The green pellets are exposed to the screened roller sizer established under the discharge end of the drum pelletizer. These green pellets are separated on a vibrating screen fractions: < 8 mm; 8 - 25 mm. The fine fraction (< 8 mm) is returned to the conveyor feed materials. Fraction 8 - 25 mm is fed to the roasting machine to remove moisture and hardening of the pellets at temperatures of 1200 - 1300 ⁰C (Figure 3).

Figure 3 - roasting machine for oxidized pellets

The kiln is divided into two zones of drying, heating, firing and cooling of the three zones. The green pellets conditioned size 8-25 mm (with an average area of ​​the roller screen) arrive on the feeder conveyor and the kiln.

Oxidized pellets in chemical composition to obtain a low content of impurities (see table 1).

Table 1 - Chemical composition of oxidized pellets

Materials	Chemical composition,%
Fe	Fe2О3	FeO	А12О3	СаО	MgO	SiO2	P	S
Oxidized pellets	67,31	95,74	0,37	0,17	0,14	0,23	3,15	0,01	0,001

The resulting oxidized pellets are fed into the shaft furnace metallization "Midrex", resulting in a counterflow of reducing gas (CO - 35% H₂ - 65%) at a temperature of 900 ⁰C and iron oxide (Figure 4), we obtain vysokometallizovanny product from the Fe metallization degree of 95 - 97 % and a low content of impurities (Table 2).

Table 2 - Chemical composition of metallized pellets

Materials	Chemical composition,%
Feобщ	Feмет	С	А12О3	СаО	MgO	SiO2	P	S
Metallized pellets	94,3		1,2	0,15	0,2	0,23	3,9	0,01	0,001

Figure 4 - The technology of production of metallized pellets

Reduction reaction gazoobraznymi reducing iron oxides in a shaft furnace "Midrex":

3Fe₂О₃ + СО = 2Fe₃О₄ + СО₂ + 37.25 MJ; (1)

Fe₃О₄ + СО = 3FeO + СО₂- 20.96 MJ; (2)

FeO + CO = Fe + CO₂ + 13.65 MJ; + 13.65 MJ; (3)

3 Fe₂О₃ + H₂ = 2Fe3O4 + N₂O - 4.2 MJ; (4)

Fe₂О₃ + H₂ = 3FeO + H₂O - 62.41 MJ; (5)

FeO + H₂ = Fe + H₂O - 27.80 MJ. (6)

Metallized pellets of the shaft furnace "Midrex" hot at a temperature of 800 - 850 ⁰C is fed into electric arc furnace (Figure 5), the molten metal is drained into the machine "ladle-furnace", adjusted chemical composition is applied to the continuous casting machine, ready blooms are rolled on the rolling mill to produce 120m long rails for railways.

Figure 5 - Technological scheme of the rails on the basis of Aktyubinsk rail and plant

Thus, the proposed technology is innovative because it includes the rational use of local mineral deposits of iron ore Velihovskogo to produce the precursor in the form of metallized pellets for melting high-quality steel products.

Дата добавления: 2015-11-04