comprise anthracite duff (as to approximately 20 to 30% of the total weight), petroleum coke (as to approximately 40 to 45% of the total weight), bituminous coal (as to approximately 12 to 22% of the total weight) and molasses and phosphoric acid binder (as to the remaining weight);

were manufactured from those constituents by a process involving roll-pressing and heat treatment at about 300°C;

are pillow-shaped briquettes marked with two parallel indented lines running latitudinally around the briquette;

have an average weight of 160 grams; and

have a sulphur content not exceeding 1.5% of the total weight.