Hilary Bauerman

“ For this reason the yield on the coal charged is usually less than that obtained in retort ovens, although the quality may be better. Coals containing at most about 35% of volatile matter are best suited for the beehive oven. With less than 25% the gas is not sufficient to effect the coking completely, and when there is a higher percentage the coke is brittle and spongy and unsuited for blast furnace or foundry use. The spent flame from the ovens passes to a range of steam boilers before escaping by the chimney. ”

“ This property is utilized in several large coking plants in America, where the gas from the first ten hours’ working is drawn off by a second hydraulic main and sent directly to town gas-works, where it passes through the ordinary purifying treatment, the gas from the second period being alone used for heating the ovens.
Coke is essentially a partially graphitized carbon, its density being about midway between that of coal and graphite, and it should therefore occupy less space than the original coal ”

“ A railway along the top of the bank brings the coal from the screens or washery. The largest ovens take a charge of about 5 tons, which is introduced through the hole in the roof, the brickwork of the empty oven being still red hot from the preceding charge, and when levelled fills the cylindrical part nearly to the springing of the roof. The gas fires as it is given off and fills the dome with flame, and the burning is regulated by air admitted through holes in the upper part of the door stopping. ”

“ The yield of by-products averages about 1% of ammonium sulphate, about 31⁄2% of tar, and 0.6 to 0.9% of benzene, of the weight of the coal carbonized. After the ovens have been heated and steam supplied for the machinery of the condensing plant and the coke ovens, there is usually a surplus of gas, which may be used for lighting or driving gas-engines. ”

“ In the further treatment of the condensed products by distillation the tar gives burning oil and pitch, the benzene is separated from the creosote oil by steam-heated stills, and the ammoniacal liquor, after some lime has been added to decompose fixed ammonium compounds, is heated to vaporize the ammonia, which is condensed in lead or copper-lined tanks containing strong sulphuric acid to produce a crystalline powder of ammonium sulphate, which accumulates in the receiver and is fished out from time to time. ”

“ It is this combination of properties that gives it its chief value in iron smelting, the substance being sufficiently dense to resist oxidation by carbon dioxide in the higher regions of the furnace, while the vesicular structure gives an extended surface for the action of heated air and facilitates rapid consumption at the tuyeres. ”

“ When produced rapidly and at a low heat, as in gas-making, it is of a dull black colour, and a loose spongy or pumice-like texture, and ignites with comparative ease, though less readily than bituminous coal, so that it may be burnt in open fire-places ”