Operating Procedures for 100-ton DC Electric Arc Furnace Smelting Technology (3)

Operating Procedures for 100-ton DC Electric Arc Furnace Smelting Technology (3)

III. Feed Material

Before feeding, it is necessary to verify the material basket number and the material list. Only when the material basket number matches the heat number, feeding sequence, smelting steel type, weight, and composition on the batching sheet can the material be fed.

2. When the charging basket is positioned above the center of the DC Electric Arc furnace, slowly lower it to about half the height of the upper furnace shell before gradually opening the lower part of the basket to discharge the material. This minimizes the impact of the furnace material on the furnace bottom and ensures that the scrap steel is evenly distributed within the furnace.

3. After feeding, check whether there is scrap steel along the upper edge of the furnace wall to prevent it from obstructing the lower cover of the furnace lid and to avoid arcing during power-on. When the charging material rises above the lower edge of the furnace lid ring, it must be compressed before rotating the furnace lid. It is strictly prohibited to use the furnace lid to compress the charging material.

IV. Melting of Scrap Steel

1. The electric furnace can only be powered on when the cooling system, hydraulic system, electrical equipment, dust removal device, etc. of the furnace are ready and functioning properly.

2. Before power-on, notify the general transformer substation to apply filtering.

3. When starting the power-on melting process, use a short arc and medium-low power (gear positions 1-3). After 1.5 minutes, switch to a long arc and full power (gear positions 7-9). When the electric energy consumption reaches approximately 250 kWh/ton of scrap steel, stop power supply, blow oxygen, and proceed to the second basket of material. During the entire melting period, use the maximum allowable power to accelerate the melting of scrap steel.

4. When all materials are ready and the scrap steel at the furnace door is red-hot, insert the C-O lance, clear the scrap steel from the furnace door, and then withdraw the lance to facilitate slag tapping.

(1) Operating control parameters for carbon-oxygen spray gun (right-handed PARPI)

Oxygen lance nozzle size: 3"     

Oxygen lance nozzle angle: 30°

Critical nozzle diameter: at a pressure of 1.0 MPa, the diameter of the first hole is 33mm (5000Nm3/h)

Carbon-oxygen gun inclination: 13°

Working spacing: 5500mm

Distance between the electric furnace carbon spray gun platform and the furnace door sill: 2000mm Oxygen impact angle: 43°

(2) Dielectric parameters

Oxygen: Supply pressure 1.0-1.8 MPa

Set operating pressure: 1.0 MPa, minimum flow rate: 400 Nm3/h

Maximum flow rate: 5000 Nm3/h

Compressed air: minimum supply pressure 0.6MPa, flow rate 30Nm3/h

Water: maximum inlet pressure 0.8 MPa, differential pressure, minimum 0.4 MPa

Flow rate: 120Nm3/h

Inlet water temperature 35°

Carbon powder: Refer to the requirements in "Auxiliary Materials (3)".

5. After each feeding and power-on, operate the furnace wall gun according to the operating requirements to accelerate the melting of scrap steel.

6. After each feeding, when the lance reaches a high velocity on the furnace wall, a suitable amount of carbon powder can be intermittently sprayed in (intermittent spraying rate is about 10-20kg/min) to accelerate the melting of scrap steel and promote slagging in advance, which is beneficial for dephosphorization.

7. During the smelting process, according to process requirements, various bulk materials such as limestone, fluorite, and carbon powder are added into the furnace through the high-level material storage and feeding system on the raw material side, via the top of the furnace.

8. At the end of melting, while performing oxygen blowing, carbon powder (about 10-60kg/min) should be sprayed intermittently or continuously to quickly form foam slag, and submerged arc smelting should be carried out to prevent arc light exposure and radiation onto the furnace wall.