Russia is one of the world's leading steel producers, while about 33 % of production comes from the scrap remelted in arc steelmaking furnaces. The graphitized electrodes of SHP and UHP grades, mainly consisting of needle coke, are used for high current loads and temperatures in furnaces. USA, Japan, Korea, and China are focused on needle coke production, where coal (tar and pitch) and petroleum (decantoil), by-products of metallurgical factories and oil refineries, are used as raw materials. Russia's annual demand for needle coke is approximately 100 thousand tons, but all of it is covered by imports. Russia's raw material potential, established by the authors of the article, is more than 5 million tons per year and includes decantoil, coal tar and pitch, and heavy pyrolysis tar. The results of obtaining needle coke from decantoil and heavy pyrolysis tar are given below. The prototypes of needle coke were produced on specially designed delayed coking laboratory units (loading up to 0.25 and 80 kg). Raw materials were modified according to the original technology of Saint Petersburg Mining University, the convergence of target properties of which is confirmed by the results of quality analysis of the obtained needle coke, including after 100-fold scaling. The electrodes were molded from the obtained coke. After standardized stages of firing, mechanical processing and graphitization at 2,800-3,000 °C, the coefficient of linear thermal expansion was less than 1 × 10–6 К–1, and the value of specific electrical resistance was 7.1-7.4 μOhm, which proves that the obtained carbon material corresponds in quality to Japanese analogues and Super Premium needle coke.
Paper studies the effect of excess pressure during delayed coking of asphalt, obtained by propane deasphaltization of tar, on yield and physical and chemical properties of hydrocarbon fuels' components and solid-phase product – petroleum coke. Asphalt was coked at a temperature of 500 °C and excess pressure of 0.15-0.35 MPa in a laboratory unit for delayed coking of periodic action. Physical and chemical properties of raw materials and components of light (gasoline), medium (light gasoil), and heavy (heavy gasoil) distillates obtained during experimental study were determined: density, viscosity, coking ability, sulfur content, iodine number, pour points, flash points, fluidity loss and fractional composition. Quantitative group hydrocarbon and microelement compositions and properties of obtained samples of petroleum coke (humidity, ash content, volatiles' yield, sulfur content, etc.) were also studied. Comparative assessment of their quality is given in accordance with requirements of GOST 22898-78 “Low-sulfur petroleum coke. Specifications”. In addition, patterns of changes in excess coking pressure on yield and quality indicators of distillate products and petroleum coke were revealed. With an increase in excess pressure of coking process from 0.15 to 0.35 MPa, content of paraffin-naphthenic hydrocarbons in light and heavy gasoils of delayed coking decreases. Common pattern in asphalt coking is an increase in yield of coke and hydrocarbon gas with an increase in excess pressure from 0.15 to 0.35 MPa.
