The Mechanical Handling and Storing of Material

3Ö2 THE MECHANICAL HANDLING OF MATERIAL is a gutter with drainage about a yard away from its lower edge and running the whole length of the hearth. I he modus operandi is as follows : As soon as the coke has been pressed out of the oven it is played upon with a hose, and quenched externally; the coke is then broken up and raked apart with hooks and rods, and is finally quenched throughout. As soon as the surplus water has evaporated and the coke is sufficiently cooled it is forked into barrows and transferred into the railway trucks on the adjoining track. I his is all very simple, but also very cumbersome, and attempts have not been wanting to replace this method by mechanical devices ; certain conditions, however, have to be observed, whether the treatment is manual or mechanical, and it is therefore well to make this quite clear before going closely into the mechanical means employed. The coke should be drenched immediately it leaves the oven, and, if possible, before it has had time to come into much contact with the air, as otherwise it will become discoloured and of less value. Ihen it is of great importance that the quenching and cooling should be uniform throughout the whole mass, as otherwise pieces might reignite in the railway trucks and damage them; it is therefore necessary to spread the coke well, let it cool for at least a quarter of an hour, and thus give time for the heat of the material to evaporate the surplus moisture and become uniformly cool. The coke as loaded should not contain more than 4 to 5 per cent, of moisture. Large coke alone is loaded into the railway trucks; the breeze and imperfectly coked portions, such as occur in ovens of old pattern, and round the doors of ovens'with horizontal flues, should be eliminated. 1 he object of the systems now to be described is to substitute mechanical means for one or more of the operations hitherto performed by hand, and thereby to reduce the cost of production as well as to make the work of those employed less onerous. It has already been mentioned that railway trucks to be loaded should be so situated, relatively to the platform, as to prevent waste from breakage, and yet to enable the operation to be carried on conveniently, say 18 in. from the platform to the top of the trucks; if it is more the fall of the coke into the trucks is too great, and likely to break the coke and thus lessen its value. Such a position between the truck and the hearth is undoubtedly the best, but in older installations it is frequently found that the hearth is much lower than that, and since the hearth, and with it the ovens, cannot be raised without rebuilding the whole installation, matters can sometimes be improved by lowering the siding for the trucks sufficiently to bring them below the hearth, but where this is impossible there is no other alternative but to lift the coke from the hearth into the trucks. . Under such circumstances the best plan is to fill the coke into iron crates or into skips, preferably with bottom discharge, and raise them by a crane over and into the railway trucks. Grabs are unsuitable on account of the brittle nature of the coke. In order to save shunting, loading cranes in large installations are made with a sufficient reach of jib to load two or three lines of trucks. Where coke ovens serve blast-furnaces direct, the coke is generally forked into tip- trucks, which convey it to the furnace, or the skips may be placed by the crane on plat- form wagons, as is the custom at the Port Clarence Ironworks at Middlesbrough. Here large electrically driven platform trucks are used to carry the skips to the furnaces, some distance off. In this particular case the height of the platform truck is such as to be on a level with the hearth, but this arrangement is here mentioned as it might equally well be applied in cases where the height of the platform truck is lower. Having now dealt with these expedients under existing circumstances, we will pay attention to mechanical installations for more modern cokeries, where the hearth is higher than the trucks.