UHP Graphite Electrodes in Electric Arc Furnace Technology

UHP graphite electrodes are used in EAF and LF, and electric arc furnace steelmaking is one of the important steelmaking methods.

Electric arc furnace in steel making

The arc zone temperature of the electric arc furnace is as high as 3000-6000°C. It heats up quickly and can melt various high melting point alloys.

The real value of this process is in making steel using all scrap steel or all solid metal.

Ultra-high power generally refers to the power of an electric furnace transformer being 2-3 times that of an ordinary electric furnace of the same tonnage, so it is relative.

Main advantage

As the power is doubled, the main advantages of ultra-high-power electric furnaces are to shorten the melting time and increase productivity.

To improve electric heating efficiency and reduce power consumption. And to be easily matched with refining outside the furnace and continuous casting,

Finally,  achieve high production, high quality, and low consumption.

The smelting cycle is less than 60 minutes and the power consumption is less than 400kwh/t.

What is graphite electrode used for?

Its function is to introduce electric current into the furnace and generate an arc with the charge to convert electrical energy into heat energy.

When the graphite electrode is working, it must conduct a large current，and withstand high temperatures.

At the same time, it will be affected by high temperature, furnace gas oxidation, and collapse material impact, which requires it to work normally under the harsh conditions of smelting.

Graphite electrode properties requirements

It has good electrical conductivity, high current density (28-15A/cm2), and small resistance coefficient (8-10Ω mm2/m).

The electrode has high thermal conductivity, small linear expansion coefficient and small elastic modulus to improve its thermal shock resistance.

Sufficient mechanical strength at high temperatures.

The shape is regular, the surface is smooth and the curvature is small, ensuring a good connection with the nipple.

High volume density, small porosity, good oxidation resistance, and not easy to oxidize, sublimate or melt under arc high temperatures.

Graphite electrode consumption rate

The consumption rate of graphite electrodes and the production rate of molten steel during the eaf  steelmaking process are affected by many factors.

Including electrode quality, furnace type, operating conditions, etc. Generally, the consumption rate of an electrode can be estimated by the following formula:

Electrode consumption rate=Electrode consumption /Amount of molten steel produced×100%

Reasons for consumption

The specific electrode consumption is usually determined by factors such as the diameter of the electrode, current density, and furnace temperature.

Electrode consumption accounts for 8%-10% of the production cost of electric furnace steel.

The electrode consumption level per ton of steel is 0.2-1.1kg.

The main reasons are breakage, oxidation, erosion of slag and furnace gas, as well as spalling and sublimation under the action of arc.

Specific measures to reduce electrode consumption.

Reduce electrode breakage and damage caused by mechanical external force and electromagnetic force.

The electrodes should be stored in a dry place and protected from moisture, as they may easily fall off and peel off at high temperatures.

Reduce the electrical loss of the electrode connector, and the nipple will be more firmly connected when driven into the pin.

Reducing oxidation consumption can enhance furnace sealing and shorten high-temperature refining time.

Growing demand for graphite electrodes in electric arc furnace steelmaking

Electric arc furnace steelmaking uses graphite electrodes to conduct electrical current to melt scrap steel and other recycled metals.

It’s more energy efficient while allowing for Increased flexibility in the eaf steelmaking process.

Wood McKenzie, a research firm that specializes in renewables, energy and natural resources, estimates that “EAF share of global steel production will increase from the current 28% to almost 50% by 2050.”

Conclusion

Graphite electrodes are indispensable in the electric arc furnace steelmaking production . Quality is the key factor in this process.

Optimizing the smelting process during the production process can reduce the consumption of tons of steel. Finally you can achieve maximum conversion rate and benefits.