What is calcined petroleum coke?
Calcined petroleum coke is derived from the calcination of petroleum coke, which is a by-product of the delayed coking unit's feedstock oil cracking at high temperatures to produce light oil. The yield of petroleum coke is about 25-30% of the feedstock oil. Petroleum coke is a black or dark gray hard solid petroleum product with metallic luster and porosity. It is a carbonaceous material composed of tiny graphite crystals in the form of granules, columns or needles. The petroleum coke component is a hydrocarbon containing 90-97% carbon, 1.5-8% hydrogen, and nitrogen, chlorine, sulfur and heavy metal compounds.
In order to adapt the petroleum coke (green coke) to the requirements, the green coke must be calcined. The calcination temperature is generally around 1300 ° C, in order to remove the petroleum coke volatiles as much as possible. This can reduce the hydrogen content of petroleum coke re-products, and according to the degree of calcination, the temperature is about 1300 ° C for calcined petroleum coke, and at about 2700 ° C is graphitized petroleum coke, so that the degree of graphitization of petroleum coke is increased, thereby improving graphite The high temperature strength and heat resistance of the electrode and the conductivity of the graphite electrode are improved.
What are the uses of calcined petroleum coke?
Calcined petroleum coke can be used in industries such as graphite, steel casting and chemical industry depending on the index. Graphitized petroleum coke is of higher quality and more expensive. According to the different sulfur content, it can be divided into high sulfur coke (sulfur content above 3%) and low sulfur coke (sulfur content below 3%). Low sulfur coke can be used as anode paste and prebaked anode for aluminum plant and for steel The graphite electrode used in the factory. Among them, high quality low sulfur coke (sulphur content less than 0.5%) can be used to produce graphite electrode and carbonizer. General quality low sulfur coke (sulphur content less than 1.5%) is commonly used in the production of prebaked anodes. Low-quality petroleum coke is mainly used for smelting industrial silicon and producing anode paste. High-sulfur coke is generally used as fuel for cement plants and power plants.
1. Used as prebaked anode material for aluminum
The prebaked anode is made of petroleum coke and pitch coke, and the coal bitumen is made of a binder, and then calcined to have a stable geometric shape, which is called a carbon anode block for aluminum electrolysis. The sulfur content of this calcined coke is mainly 3.0% or 2.0%, and some have requirements for vanadium content, and the particle size is mainly 0-30mm.
2. Petroleum coke recarburizer: calcined petroleum coke and graphitized petroleum coke
The sulfur content of the calcined petroleum coke is generally in the range of 0.5% to 1%, and the sulfur content of the graphitized petroleum coke is 0.05% to 0.3%. The calcined petroleum coke recarburizer is generally used for gray iron casting, and the graphitized petroleum coke recarburizer is used for ductile iron.
3. Graphite electrode
Graphite electrode refers to a kind of calcined petroleum coke and pitch coke as the main material, coal tar pitch as the binder, which is made by calcination of raw materials, crushing and milling, compounding, kneading, forming, roasting, impregnation, graphitization and mechanical processing. The high temperature resistant graphite conductive material, called artificial graphite electrode, is distinguished from the natural graphite electrode prepared by using natural graphite as a raw material.
Calcined petroleum coke can be used in the industries of graphite, smelting and chemical industry depending on its quality. Low-sulfur, high-quality cooked coke, such as needle coke, is mainly used to manufacture ultra-high-power graphite electrodes and some special carbon products. In the steel-making industry, needle coke is an important material for developing new technologies for electric steelmaking. Medium sulfur, ordinary cooked coke, used in large quantities for aluminum smelting. High sulfur and ordinary coke are used in chemical production, such as the manufacture of calcium carbide, silicon carbide, etc., as well as fuel for metal casting. Most of the petroleum coke produced in China belongs to low-sulfur calcined petroleum coke, which is mainly used for aluminum smelting and graphite production.