About the electric furnaces' technology of slag-free steel tapping, how much do you know?

Technology of slag-free steel tapping in electric furnaces

HOT (horizontal rotating steel tapping)

In the early days, the direction of rotation of the closing mechanism of the tap hole of DEMAC was vertical, and later it was mostly changed to the horizontal direction. For example, the BSE tapping technology in Germany, its advantage is that the plate that closes the tap hole moves horizontally, and the total height is low. Shorten the distance from the tapping port to the top of the ladle to the shortest extent, so that the tapping process is shorter, and the ladle can be covered and tapped easily.

In Mexico I987, the original 100t electric furnace was transformed into a horizontal rotary tapping electric furnace. The tapping strip slag amount is less than 5%, the electrode consumption is reduced, the average tapping temperature is reduced by 4℃, and the tapping time is shortened by 3~8min. The power consumption can be saved by 12kWh/t. The productivity is increased by 5%, the water cooling area of the furnace wall is increased by 13% compared with that before the renovation, and the consumption of refractory materials is reduced by 9%.

Slide valve tap

The slide valve tapping port was successfully used in the open hearth furnace in Europe in 1980. Based on this experience, the American Special Steel Company uses this technology on a 220t electric furnace. The device is similar to the sliding nozzle of the ladle. This device is hydraulically driven and electronically controlled. It can completely cut off the steel stream with a diameter of 178mm within 1s, and the slag thickness brought into the ladle is less than 25.4mm.

In order to achieve slag-free tapping of electric furnaces, a series of new technologies have been developed:

1. The stopper rod water tapping of the flow blocking method.

2. Steel tapping with sliding nozzle.

3. Continuous steelmaking method with slag steel separation.

EBT replacement and slag display system

The German Didier company has developed a convenient replacement system for the EBT system. The system can replace the refractory bricks at the end of the tapping port or the entire tapping port with pre-manufactured spare parts. In order to ensure slag-free tapping, the company has successfully developed a slag detection system. The key of the detection system is to use the magnetic difference between steel and slag. By measuring the induced current and electromagnetic field formed by the primary winding in the molten pool, the presence of slag makes the sliding nozzle Close to prevent slag from flowing out.

Stopper tap

Stopper tapping, that is, tapping on the side of the furnace bottom, is also called STB method. It is the tapping port of the siphon tapping steel stopper switch. The tapping hole stopper of the electric furnace has the same operation as the ladle stopper, and it is easy to maintain. The picture below shows the Iectmslag device sold by Iectromek in the United States. It is said to be used on a 200t electric furnace to control the amount of slag carried below 250kg. Using this device with steel retention operation, using 5-6kg/t desulfurization slag, the desulfurization rate can reach 70%-80%; using 2kg/tCa-Si powder, the desulfurization rate can reach 90%; the required amount of A1 is reduced by 0.5kg/ t; The yield of Si is improved.