SE452990B - SET FOR MANUFACTURE OF STEEL IN A LIGHT BACK OVEN PROVIDED WITH THROUGH CHANNEL ELECTRODE - Google Patents

Description

452 990 2 material is controlled so that the desired final carbon content is obtained for the steel. You can thus directing the process to finished steel through the material feed and proportion reducing agent: highly reduced material.

The invention thus relates to a process for producing steel in a DC arc furnace by reduction and refresh. The DC arc furnace is provided with at least one electrode with a through-hole channel, intended for continuous feeding of fine-grained material. The flow of the iron containing the material in the oven consists of one or arbitrary combinations of: a) Highly reduced fine-grained material of the rolling furnace pellet type. Of course can other forms of such material are also fed, for example in powder form material. b) Scrap.

Charging of scrap preferably takes place in batches, preferably at the start of the oven cycle. The fine-grained iron carrier can be fed continuously under the oven the cycle through the hole electrode or batchwise. During the oven cycle, the following granular materials are fed continuously through the hole electrode. a) Slag formers (eg lime). b) Reducing agents in the form of carbon supports.

The cycle ends with bottling of steel with the desired carbon content. This steel quality is adapted to a subsequent ladle metallurgical treatment. After tapping a swamp is preferably left in the oven to facilitate starting next cycle. This swamp can also include smaller parts of slag.

During the cycle, temperature and material feed can be controlled to optimize the process. Through the hole electrode, carbon supports can be effectively put the metal bath.

It is particularly advantageous to run the oven cycle in two stages with intermediate spirit draining.

Step 1: Relatively high carbon content (about 1%) in the steel. This carbon content entails relatively low temperature (approx. 1500 OC) and low basicity (approx 1,2) in the slag. The high carbon content leads to an effective reduction. : fr 20 25 30 452 990 Step 2: The carbon feed decreases or stops completely. The carbon content in the bath decreases to the desired level (about 0.25%). Thus, the temperature must be increased (approx 1600 OC) and also the basicity (about 2) in the slag.

With the previously stated reduction in DC ovens, it was normally reached down to about 2% C, possibly 1.5-1.7%. Here you can reach down to 0.25% or less weight percent carbon.

Preferably, the electrode is connected cathodically and the bath anodically.

The two steps can be performed so that in the first step the carbon content is brought down to 0.3-1.5% - in the embodiment shown above, the percentage was '1 - and in the second step down to a carbon content of, for example, 0.1-0.1%, preferably 0.25%, with intermediate slag tapping taking place.

As an example of the relationships between highly reduced material and slag formers and scrap and reducing agents can be mentioned the following.

Highly reduced material 86% Reducing agent 2% Slag Former U% Scrap 5% A certain part of the molten steel is preserved in the furnace to facilitate starting of the next cycle. The slag is preserved to minimize the action of slag formers.

The basicity is measured as the ratio of CaO to S102, as shown the case is about 1.2.

In another case, the basicity can be set to 2.

The attached figure shows a direct current furnace, where an electrode 1 is provided a filling tube 2 for highly reduced material in powder and / or pellet form, as well as for slag formers and reducing agents. The mission is fed down through the hole channel 3 in the electrode 1. As shown, the electrode is negative connected. Scrap can be entered in a suitable manner, for example at the arrow 4, and in the arc 5 the reduction takes place.

The procedure as above can be varied in many ways within the framework for the following claims.

Claims (3)

452 990 PATENT CLAIMS A process for producing steel of any carbon content in an arc furnace, provided with at least one through-channel electrode (1), connected to one pole by a direct current source, while the charge and at least one bottom electrode (6) are connected to the other pole, characterized in that steel material, after being reduced to a highly reduced material in powder and / or pellet form and together with slag formers and reducing agents, is fed down through the channel (3) in the electrode, and that any scrap is charged ( U), the proportion of reducing agent and highly reduced material being controlled so that the desired final carbon content is obtained for the steel. 2. A method according to claim 1, characterized in that the electrode is connected to the negative and the melt to the positive pole of a direct voltage source. Process according to Claim 1 or 2, characterized in that the steel production takes place in two stages, a first with a reducing carbon content down to 0.8-1.5%, preferably 1%, and a second down to a low carbon content. , for example 0.1-0, Ä%, preferably 0.25%, with intermediate slag tapping. H. A method according to any one or more of the preceding claims. is characterized by the fact that a certain part of molten steel and possibly slag is preserved in the furnace in order to minimize the consumption of slag formers. fl MH