Quality requirements of electrode paste in the steelmaking process of electric arc furnace
In the process of steelmaking in electric arc furnaces, the quality requirements of electrode paste are very strict, because it is directly related to the performance of the electrode and the efficiency of steelmaking.The following are the main quality requirements of electrode paste in the steelmaking process of electric arc furnace：
1. Chemical composition and content
Fixed carbon: Fixed carbon is the main component of electrode paste, which directly affects the conductivity and high temperature resistance of the electrode.The higher the fixed carbon content, the better the performance of the electrode paste.
Ash: Ash is a non-carbon residue in the electrode paste. The lower the content, the higher the purity and conductivity of the material.Excessive ash content will affect the electrical conductivity and corrosion resistance of the electrode, resulting in increased resistivity, reduced strength, increased power consumption, increased electrode consumption, and prone to hard break accidents.
Volatile components: Volatile components in electrode paste refer to components that will evaporate at high temperatures.Moderate volatile content helps the bonding and forming of the electrode, but too high volatile content may lead to pores and electrode cracks, affecting the strength and stability of the electrode; too low volatile content may lead to fast electrode sintering speed, poor adhesion, large contact resistance between the electrode and the controller, and it is also prone to hard breakage and electrode puncture accidents.
Sulfur content: Sulfur is a harmful impurity that may cause the electrode to become brittle at high temperatures, so its content needs to be strictly controlled.
2. Physical properties
Particle size: The particle size of the electrode paste should meet the standards. Too small particles will affect the sintering performance and density of the electrode, while too large particles will lead to an increase in the amount of residual carbon during electrode sintering.At the same time, the particle size also affects the uniformity of the electrode forming process and the density of the final electrode, and the particle size distribution of the electrode paste is usually required to be uniform.
Compressive strength: Compressive strength is the ultimate compressive load per unit area of the sample after the electrode paste is calcined, and it is an important indicator to measure the mechanical strength of the electrode.Electrodes with low compressive strength and poor mechanical strength are prone to hard break accidents in use.
Flexural strength: The flexural strength tests the fracture resistance of the electrode paste under bending conditions to ensure the stability and durability of the electrode during use.
Resistivity: Resistivity is the size of the resistance per unit sample of the electrode paste after roasting, and it is a physical quantity that represents the conductivity of the electrode.The resistivity is small, the electrode resistance is small, and the power consumption is low.At the same time, there is an inverse relationship between resistivity and thermal conductivity. The resistivity is low, the thermal conductivity is large, the temperature conductivity is high, the heat stress value generated is small, the thermal stability is good, and the electrode is not susceptible to rapid cold and heat and breaks.
Bulk density: Bulk density refers to the mass per unit volume of the sample after the electrode paste is calcined, and it is a physical quantity that measures the density of the macroscopic structure of the carbon material.The bulk density is large, the true porosity is small, the denser the electrode, the higher the mechanical strength, the stronger the oxidation resistance, and the better the thermal conductivity and thermal shock resistance.
Softening point: The softening point is the temperature at which the electrode paste begins to soften when it is heated to a certain temperature, which determines the forming and sintering properties of the electrode paste.
Adhesion: Adhesion evaluates the cohesion of the electrode paste and the adhesion to the electrode skeleton, which are the key properties in the electrode forming and sintering process.
Coefficient of thermal expansion: The coefficient of thermal expansion refers to the dimensional change of the electrode paste when the temperature changes.The lower coefficient of thermal expansion helps to avoid cracking or deformation of the electrode during use.
Thermal conductivity: The thermal conductivity tests the ability of the electrode paste to conduct heat at high temperatures, which is an important factor to ensure the stability of the electrode.
3. Other properties
Thermal stability: The electrode paste should have good thermal stability, that is, it is not easy to decompose or deteriorate at high temperatures, in order to ensure that the electrode can work stably at high temperatures.
Conductivity: The electrode paste should have good electrical conductivity to ensure that energy can be transmitted smoothly when the current passes through.Conductivity is the reciprocal of resistivity, which directly affects the current conduction ability of the electrode.
Corrosion resistance: The electrode paste should have good corrosion resistance to resist the erosion of various chemicals.
Environmental protection performance: The electrode paste should meet environmental protection requirements and do not contain substances harmful to the human body and the environment.
In summary, the quality requirements of electrode paste in the steelmaking process of electric arc furnace cover chemical composition, physical properties and many other aspects.These requirements are designed to ensure that the electrode paste can meet the harsh conditions such as high temperature and high current density in the steelmaking process of electric arc furnaces, so as to ensure the smooth progress of the steelmaking process and product quality.
