1898 - Coalmininghistorypa.org

No. 11. BUREAU OF MINES. xxi.ishapes are reijuired of these tine bricks, which for the most partare made in or adjacent to the district. The additional cost of acoke phmt consists in the construction of the yard, its retainingwalls and the larry track rails which are laid on top of the ovens.This brings the coS't of a single oven up to |3U0. Exclusive of theJSemet-Solvay plant of 30 ovens at Dunbar, the cost of which hasnot been divulged, the remaining 18,503 ovens in this region representan investment of |5,577,JJU() for their construction alone. Thebeehive ovens are built in single rows and called bank ovens, andthose in double rows are called "block ovens." On block ovens thelarr}' track is laid directly between the trunnel heads of each rowof parallel ovens composing the block. On the bank ovens thistrack is laid in the rear of the trunnel heads of the single row ofovens composing the bank. The larry, or large iron wagon usedto charge the ovens with coal, is coiistructed with a discharge oneach side to reach both lines of ovens, and with but one dischargefor the single line or bank ovens. These liirries run on the tracksabove mentioned and are hauled either singly, by mules*, or in trainsby small locomotives.Process of Burning Coke in Beehive Ovens.The process of burning coke is very simple, rne coal, on beingbrought out of the mine is deposited in a large funnel-shaped bin,from whence it is delivered by simple appliances into the larries,which deliver it through the orifices in the top into the ovens. Thesecliurgesi vary from 120 to 165 bushels, and consequently the yieldof coke varies from three to five tons per oven.After the oven has been charged, the coal is evenly distributedover the bottom by means of a long iron rod with a scraper weldedon the end, through the door in front, which is 26x30 inches. Thisis now walled up with brick and plastered with a luting of finesharp sand or loam to exclude the air. In a short time a pale, bluesmoke slowly arises from the now open trunnel head. The smokegradually grows denser and darker, and in about half an hour asudden pufl", resembling somewhat an explosion of unconfined powder,is heard, which is notice that the coal is ignited. The chargeburns from the top down, and the })rocess of burning or "airing"the ovens is regulated by nutans of small holes made around thearch of the door in the form of a semicircle. Through these openiigsthe air is admitted, and the smoke and impurities are expelledthrough the oiiening in fhe top of the oven. The oven is "around"when the mass is properly coked. The "drawers" now take chargeof the oven, remove the bricks from the door, cool the coke by introducingwater into the oven by means of a hose to the end of which