﻿FISH-SCRAP FERTILIZER INDUSTRY OF ATLANTIC COAST. 29 



again by bucket conveyer, to the warehouse where it is stored, 

 ground, and bagged. The transit through the drier consumes from 

 3 to 20 minutes, depending on the force of the blower, the rate of 

 rotation of the kiln, and the degree of fineness of the lumps of scrap 

 on entering the kiln. The moisture content is reduced to about 7 

 per cent. As some of the kilns are being operated, about 5 tons 

 of coal per day is consumed. According to the various estimates 

 of the operators, a million fish produce 75 to 85 tons of dry scrap ; 

 12,000 to 15,000 fish are required to make 1 ton of scrap. The drier, 

 complete and set up, may be purchased for $3,000, inclusive of blower, 

 bricks, etc. 



The hot-air drier for fish scrap is a useful piece of apparatus, 

 and its introduction marks an epoch in the fish-scrap industry. It 

 has rendered it almost altogether unnecessary to acidulate scrap, since 

 the drier practically always is able to handle the output of the cookers 

 and presses. In the plant equipped with a full set of the improved 

 machinery the fish are not moved by manual labor from the time 

 they are fed to the elevator in unloading until the dry scrap is being 

 bagged. The whole operation requires less than an hour. 



Theoretically, the hot-air drier is inefficient. Theory requires that 

 in drying the drying agent shall be passed over the material being 

 dried in a direction opposite to that in which that material is moving. 

 Thus, in drying by a stream of hot air, the hottest and driest air is 

 brought into contact with the driest material, and as it becomes more 

 heavily charged with water vapor, passes progressively over wetter 

 and wetter material. In this way the maximum moisture absorbing 

 power of the air is made of use. In the drier in use in the fish-scrap 

 industry, the opposite arrangement obtains, the hottest and driest 

 air is brought into contact with the wettest and coldest fish, and the 

 wettest and coldest air into contact with the driest and warmest 

 fish. The objection raised to the former procedure is that the dried 

 scrap is inflammable and a careful regulation of the temperature 

 would be required to prevent the scrap from catching fire. There 

 is little danger of this with the present scheme. However, it would 

 be a simple enough matter to lower the temperature of the drying 

 gases far below the ignition temperature of the dried scrap by intro- 

 ducing a sufficiently large volume of cold air into the gases from the 

 furnace ; or the fire could be largely reduced in size. Certainly the 

 same amount of drying could be effected with a smaller consumption 

 of coal, or with the same consumption of coal more efficient drying 

 and, possibly, more rapid drying could be made possible by the use 

 of a larger volume of air, and the process could be made as auto- 

 matic as the present process. 



A more serious objection to the present practice in drying scrap 

 is the undoubted destruction of a part of the scrap in the drying. 



