High-Density Artificial Graphite Electrode via Coke Shape Changing
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Solution Overview
Problem
Conventional methods for manufacturing artificial graphite electrodes struggle to achieve high density without altering particle size, binder pitch proportion, or increasing molding pressure, leading to voids and thermal shock cracks, especially in larger electrodes.
Innovation Solution
The method involves pulverizing needle coke, kneading it with binder pitch, and performing coke shape changing treatment to increase the enveloping perimeter to perimeter ratio by 1% or more, which enhances the bulk density of the electrode without significant changes in particle size or molding pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If needle coke is pulverized and classified into various particle sizes to increase filling density, then the density of the molded product improves, but voids derived from crystal structure irregularities remain and thermal shock resistance deteriorates
Solution Approach 1:
The invention changes the shape parameter of needle coke particles through coke shape changing treatment, transforming elongated irregular particles into more spherical shapes. This parameter change increases the enveloping perimeter to perimeter ratio, improves filling density, and eliminates voids while maintaining thermal shock resistance
Solution Approach 2:
The coke shape changing treatment is performed preliminarily before extrusion molding to transform the particle shape of needle coke. This preliminary action of rounding particles and increasing sphericity ensures optimal packing density and eliminates void formation during subsequent molding, preventing thermal shock cracks
2Productivity
If electrode diameter is increased for large-scale electric furnaces, then productivity improves, but temperature difference in radial direction increases and cracks due to thermal shock are easily generated
Solution Approach 1:
The invention changes the particle shape parameter of needle coke to increase sphericity and enveloping perimeter to perimeter ratio. This parameter change enables production of large-diameter electrodes with uniform density distribution, reducing radial temperature differences and preventing thermal shock cracks while maintaining large electrode dimensions for high productivity
3Quantity of substance
If conventional pulverization and classification methods are used to increase filling density, then aggregate density improves, but fine irregularities from crystal structure generate voids
Solution Approach 1:
The invention applies spheroidality by transforming elongated needle coke particles into more spherical shapes through coke shape changing treatment. This curvature change increases the enveloping perimeter to perimeter ratio, improves filling density through better particle packing, and eliminates voids by removing angular irregularities and fine crystal structure defects
Data Source
AI summary
Provided is a method for manufacturing a high-density artificial graphite electrode without substantially changing a particle size or a proportion of needle coke used, increasing an amount of binder pitch, or performing extrusion molding at a high molding pressure. The method for manufacturing a high-density artificial graphite electrode is kneading binder pitch into needle coke, performing extrusion molding thereof, and then calcining and graphitizing thereof, wherein needle coke obtained by performing coke shape changing treatment for at least some of pulverized needle coke to be used, thereby increasing a ratio of an enveloping perimeter/a perimeter by 1% or more as compared with a value before the changing is used. Here, the enveloping perimeter is a length of a perimeter when apexes of convex portions of the pulverized needle coke are connected to each other via the shortest distance, and the perimeter is a length of a perimeter of a particle.