High-nickel, high-vanadium petroleum coke requires special attention before calcination. The core reason is that the chemical behavior of nickel and vanadium at high temperatures seriously interferes with the stability of the calcination process and product quality. This is manifested in the following aspects:
I. Low-melting-point oxides cause equipment corrosion and slag blockage
Vanadium generates low-melting-point oxides such as V₂O₃ at high temperatures (above approximately 900°C). These substances are highly corrosive and rapidly erode the firebrick lining of the calcination furnace, significantly shortening equipment life. At the same time, low-melting-point vanadium oxides cause abnormal increases in slag viscosity, easily leading to blockages at the slag discharge port and disrupting the material balance inside the furnace. Nickel also appears in gaseous forms such as Ni(g) and NiS(g) above 1400°C, similarly eroding the furnace body.
II. Complex morphological transformations at high temperatures increase process control difficulty
Nickel exists primarily as Ni₃S₂ in the early stage of calcination. Above 900°C, it begins converting to NiS in the liquid slag, reaching a maximum NiS content of approximately 22.4% in the slag at 1200°C, and then reconverts to Ni₃S₂ as temperature rises further. This repeated transformation means nickel behaves completely differently across different temperature ranges, posing great challenges for temperature control. Vanadium can also catalyze the conversion of SO₂ to SO₃ in a gasification environment, aggravating flue gas pollution and equipment corrosion.
III. Fatal impact on downstream product quality
Sulfur, vanadium, nickel, and titanium are inherent elements in the macromolecular petroleum heterocyclic chains, existing in the coke in compound form and extremely difficult to remove by conventional calcination. Calcination to around 1300°C has limited desulfurization effect; the temperature must be raised to 1450°C for noticeable results, and some sulfides are only expelled at the even higher temperatures of graphitization. When high-nickel, high-vanadium coke is used to produce graphite electrodes, “gas swelling” occurs during graphitization, causing product cracking. When used for aluminum electrolytic anodes, vanadium and nickel transfer into the aluminum melt, directly affecting aluminum quality. When used as a reducing agent for industrial silicon, they reduce the conversion rate and selectivity of organosilanes.
IV. High volatile matter compounded with coking risk
High-nickel, high-vanadium petroleum coke is often accompanied by high volatile matter (8%–15%). Excessive volatile matter easily causes coking inside the furnace during calcination, not only increasing operational difficulty but also accelerating the abnormal migration and volatilization of nickel and vanadium due to localized overheating, creating a vicious cycle.
Therefore, before using high-nickel, high-vanadium petroleum coke, strict trace element testing of the raw material must be conducted. The calcination temperature curve should be adjusted according to nickel and vanadium content (typically pushed up to 1450°C or higher), and corrosion-resistant furnace linings and enhanced slag discharge measures must be equipped. Otherwise, the consequences range from unqualified products to outright equipment destruction.
Post time: May-27-2026