Operating Procedures for 100-ton DC Electric Arc Furnace Smelting Technology (2)

Operating Procedures for 100-ton DC Electric Arc Furnace Smelting Technology (2)

II. Maintenance of the furnace body and bottom electrode, and preparation before feeding. 

1. Inspection, Replacement, and Filling of the Tap Hole 

(1) After tapping, inspect the erosion degree of the tap hole sleeve brick to decide whether to repair it. If the tap hole is straight.

If the diameter is greater than 230mm or if the damage is severe, promptly notify the relevant personnel and arrange for the next furnace to discharge clean steel slag to replace the taphole. The taphole should be replaced after 100-150 normal smelting batches.

(2) After tapping, if there is no need to replace the taphole, immediately clean the tail brick of the taphole and any remaining metal or brick fragments from the entire taphole. If there are local defects, they can be repaired with refractory materials. Then, close the taphole support plate, align the charging funnel with the taphole, and place the filler material to fill the taphole. Ensure that the top of the filler material forms a Mantou shape, and then cover it with the filler cover plate.

2. The replacement and adjustment of electrodes

The replacement and adjustment of electrodes can be carried out after the power is cut off for 2-3 minutes during the "well-drilling" process of scrap steel.

(1) Electrode extension:

Lift the electrode to be connected to the electrode extension device, activate the clamping device to secure it, and then lift the new electrode,

Align its electrode connector with the electrode being connected in a timely manner, tighten the electrode connector, align the electrode with the tightening mark, and use the electrode tensioning device to tension it again. The total length of the electrode cannot exceed 8100mm.

(2) Electrode replacement:

When the electrode length is less than 5400mm, use a crane to lift the electrode to the electrode storage position for cooling. After two hours, the electrode can be extended. Then lift the spare, extended electrode. The height of the electrode on the top of the electrode holder must not exceed 2500mm, and the electrode holder must not be clamped within ±230mm of the electrode joint.

3. Inspection, Maintenance, and Replacement of Furnace Lid

The maintenance of the furnace cover is best carried out during the maintenance period. If individual parts of the furnace cover (such as pipes, valves, mounting parts, etc.) urgently need to be replaced, it should be done after the furnace has discharged the steel and after adding cold scrap steel, which can isolate thermal radiation.

Minor repairs to the furnace lid: Minor leaks can be urgently repaired and eliminated, and the furnace can remain in operation until the next maintenance. The steps are as follows:

-- Rotating out of the furnace;
-- Adding waste;

-- Close the pneumatically operated butterfly valve in the water supply pipeline of the furnace cover, and the return water pipeline will be automatically closed by the check valve;
-- Remove the slag from the damaged area;

-- Open the ventilation plug at the upper ring of the spider to drain the water accumulated in the damaged circuit and prepare for welding;
-- Collect the drained water to the collection port;

-- Grinding and welding of damaged areas;

-- At the same time, close the manual butterfly valve (installed on the wall of the transformer room) and open the pneumatically operated butterfly valve again;

-- Complete the repair work, slightly open the manual valve in the water supply circuit, ventilate the furnace cover, and allow the infiltrated air to be discharged through the ventilation screw.

When the thickness of the small furnace cover is too thin or the inner hole is too large, which cannot guarantee normal smelting in the lower furnace, or when there is a large area of leakage, the furnace cover should be replaced in a timely manner. The newly replaced small furnace cover should have its center hole aligned and must not deviate from the electrode.

4. Replacement of Slag Ladle

The slag ladle should be replaced for each furnace to prevent slag leakage and difficulty in turning over the slag. The slag ladle should be kept dry, and a small amount of debris or waste slag should be added to the bottom of the ladle to prevent overheated steel slag from damaging the ladle and to facilitate turning over the ladle.