EAF electrodes are conductive rods used to make steel, and it takes about 2kg to make a tonne of steel. It accounts for less steelmaking cost, but it is very important.
Eaf electrodes chemical composition
The chemical composition of the electrode is carbon, graphite is simply an allotrope of carbon, and therefore only contains carbon atoms in its chemical formula.
The structure of graphite is as follows:
In graphite, unlike diamond each carbon atom is bonded to three other carbon atoms as shown in the figure. The hybridization of carbon is and the geometry is trigonal planar. Graphite is made up of only carbon atoms.
Therefore, the chemical formula of graphite is C.
Graphitization is the use of thermal activation to orderly convert thermodynamically unstable carbon atoms from chaotic layer structure to graphite crystal structure.
EAF electrode is composed of the electrode body and the electrode nipple
Eaf electrode producers
1) Raw materials
60% of the production cost of eaf electrodes comes from raw materials, mainly petroleum coke, with needle coke and coal pitch added.
Petroleum coke is a type of easily graphitized carbon and is the main raw material for the production of graphite products. Needle coke is a high-quality coke with fibrous texture, low thermal expansion coefficient, and easy graphitization.
In the calcination process, the raw materials remove the moisture and volatiles, which improves the physical and chemical properties of the raw materials. Generally, the maximum calcination temperature is 1250-1350℃, and the equipment adopts tank calciner, rotary kiln and electric calciner.
The mixed raw materials are extruded and molded by an extruder. By changing the nozzle on the extrusion cylinder, an electrode with a certain diameter and length can be formed. The extrusion equipment is a horizontal hydraulic extruder and a screw extruder.
Baking can greatly improve the thermal stability, mechanical strength and electrical conductivity of the material. The coal pitch in the green body is coked during the roasting process, and about 10% of volatile matter is discharged, while the volume shrinks by 2-3% and the mass loss is 8-10%.
The calcined product is put into a pressure vessel, and the liquid impregnant pitch is immersed in the electrode pores under certain pressure and temperature conditions. The purpose of impregnation is to reduce the porosity of the product, increase the volume density and mechanical strength of the electrode, and improve the electrical and thermal conductivity of the electrode.
It refers to the high temperature heat treatment process in which the semi-finished electrode product is heated to above 2300-3000 ℃ in a high temperature electric furnace to transform the amorphous chaotic layer structure carbon into a three-dimensional ordered graphite crystalline structure. Acheson graphitization furnace and internal heat series (LWG) furnace are used.
Graphitization is the process of controlling the temperature.
The purpose of electrode machining is to rely on automatic or semi-automatic CNC machining to achieve the required size, shape, precision, etc., to make the electrode body and joints that meet the requirements of use.
To read more about the EAF electrode manufacturing process click on this link: EAF electrode manufacturing process
Eaf electrode wear mechanism
The calculation of electrode consumption during the smelting process has two concepts, net consumption and gross consumption. Net consumption refers to the technical consumption of the technical water pump during the smelting process where the electrodes are sublimated, oxidized, and reacted. The sum lost without participating in smelting. At present, the iron and steel industry evaluates the physical quality of eaf electrodes by gross loss. eaf electrode consumption rate formula:
The first method: yield method
The production method is based on the amount of molten steel (finished product) produced in a certain period of time, and the consumption of eaf electrode input during the same period minus the remaining amount on the furnace.
Gross consumption of ton steel eaf electrode: MM = MZ / MG
Net consumption of ton steel eaf electrode: MJ = MC / MG
Among them: MZ is the total consumption of the electrode (input amount-remaining amount on the furnace), KG / T;
MC is the pure consumption of the electrode (input amount-remaining amount on the furnace-loss amount), KG / T;
MG is the finished product quantity of molten steel, T.
The second method: power consumption method
The power consumption method is based on the cumulative power consumption of the pure heating time in a certain period, and the eaf electrode input during the same period minus the remaining amount on the furnace is the consumption amount (the LF furnace calculates the power consumption and electrode every 1℃heating ).
Consumption of electrode per kWh:
MX = 1000 * MC / QH
Among them: MC is the pure consumption of the electrode (input amount-remaining amount on the furnace-loss), KG / T; QH is the cumulative power consumption in pure heating time, KW * H.
The output method basically uses gross consumption as the calculation method, and all use the output of the finished product as the calculation base. Although the power consumption method does not consider the loss other than the consumption of the smelting technology, it is still necessary to consider this loss in the assessment of the steel plant. This method will have a clear comparison between the batches of the electrodes.
In summary, the consumption evaluation of eaf electrodes in smelting at this stage is unfair. As the carbon industry, comprehensive evaluation methods should be actively recommended. That is, the industry should actively recommend the comprehensive evaluation method based on the output method.
Eaf electrode 28 inch
EAF electrode technical specifications:
Eaf electrode clamping arms steel type and eaf electrode arm assembly with column
The following automatic adjusting devices are mainly used for the electrode lifting of electric furnace.
First, thyristor - dc motor type automatic regulator.
Second, SCR - electromagnetic differential clutch regulator.
Third, electro-hydraulic proportional valve - hydraulic transmission type regulator.
The first two kinds of regulating devices are composed of electronic components of the insert board. Due to the unstable performance of the electronic components, the maintenance work is large. Compared with the former two kinds of adjusting method, using the hydraulic transmission type regulator, the hydraulic system of inertia is small, the rise and fall of start, brake speed, torque, at the same time adopt SIEMEN S7-300 series programmable controller to control, the entire electrical system compact structure, stable performance, therefore low failure rate, convenient maintenance, by modifying the program to meet different smelting process requirements, very suitable for used as a regulator, is widely used in large and medium-sized electric furnace.
Eaf electrode cooling ring hole digre
The arc furnace uses water cooling or air cooling devices, and the arc furnace electrode USES spray cooling system.
Eaf electrode resitivity measurement
The resistivity measurement of graphite chemical sequence can be carried out according to the carbon material resistivity measurement method YB/T120-1997, which is defined as a property representing the resistance of a material when passing through an electric current, which is numerically equal to the resistance value of a conductor with a length of 1m and a cross-sectional area of 1m2.
The principle is based on Ohm's law and the characteristics of conductors to derive the following formula:
U -- Voltage drop at both ends of the conductor, mV
I -- the strength of the current passing through the conductor, A
S -- the cross-sectional area of the electrode, mm2
L -- length of conductor, m
Read resistivity detection methods and resistivity detection instruments at this link: Graphite electrode resistivity measuring instrument
and Eaf electrode resistivity measurement
EAF graphite electrode assembly procedure
Graphite electrode use and connection steps
Eaf electrodes price 2020
Unit: USD/MT 2020.09
Read more prices
Data source bid prices of various manufacturers. for reference only. The quotation is subject to the quotation of the eaf electrode manufacturer Dancarbon on the day.
Eaf electrode catalogue
Read more eaf electrodes manufacturing process pdf, Please Dowload: Graphite Electrodes PDF
Eaf electrode supplier
Dan Carbon EAF Electrode (formerly Dandong Xinxing Carbon) is the top 3 eaf electrode manufacturer and the largest eaf electrode manufacturer. Internationally, there are eaf electrode companies including UCAR in the United States, HEG in India, TOKAI in Japan etc. Of all eaf electrode manufacturers, China has the lowest cost of eaf electrodes, followed by India and Russia.