Also the content of the key component benzopyrene (c. 25 mg/kg) is not critical. Green coke is therefore classified as a nontoxic substance [3].
No classification and labeling regarding toxicity, carcinogenicity, flammability, and environmental effects is required. Contents of Ni, V, Na, Ca, and Fe originating from the crude oil residues used as feed are accumulated in green coke. These levels can rises up to approximately 10–500 mg/kg. Small amounts of metals and anions are introduced with the cutting water, which makes up to 5–15% of green coke (cutting water content: Na, Ca, Cl,
The following classification is employed for the combustion and explosion behavior (measurement of Deutsche Montan Technologie [DTM], mining test circuit, Dortmund):
| Combustion behavior | BZ 3 (local combustion or glowing without spreading) |
| Glow temperature | 300 °C |
| Ignition temperature | 700 °C |
| Dust explosiveness | Contents >60 g/m3 and with ignition source of >10 000 J |
Green coke is normally stored in open piles with sidewalls as protection against the wind. In order to reduce the dust discharge, green coke piles are sprinkled with water.
The potential dust emission is visibly improved by means of dosing antidust additives (polyacrylate types or extract of orange peel) to the sprinkling water.
The general explosive boundary value at work of 6 mg/m3 for fine dust concentrations is to be complied with.
6.1.2.6.2 Calcined Petroleum Coke
All hydrocarbons in green coke are eliminated by calcination. The remaining hydrogen content is <0.1%. Therefore, no polycyclic aromatics are traceable. The content of S, N, and metals is virtually unchanged. With water, only part of the salt content of the cutting water can be elutriated. No classification and labeling is required.
Due to the dryness of the calcinate, irritation of eyes and throat by the dust is possible. The general boundary value at work (maximum 6 mg/m3 for fine dust concentration) is to be complied with.
Calcined coke is usually stored in closed silos or bins to keep the material dry. To reduce dust formation, the calcinate is sucked off during transport and loading and the dust held back by filter stations. Sprinkling the calcinate with residue parts of 0.2–0.4 wt% (old process) or an aqueous emulsion of dust binder prevents environmental problems from dust. The dust forming factor (“R+D‐Carbon” method) must be <0.02 wt%. The combustion and explosive behavior of calcined coke presents no problem:
| Combustion behavior | BZ1 (no combustion) |
| Glow temperature | No glowing up to 450 °C |
| Ignition temperature | No ignition up to 850 °C |
| Dust explosive | No |
Since no combustible dust–air mixture is formed, calcined dust is a material that has no security zone classification (zone 11) and does not come under the risk management regulation.
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