64 BULLETIN 983, TJ. S. DEPARTMENT OF AGRICULTURE. 



a long, open, covered shed with an inclined bottom sloping into a 

 trough, similar to those used for the storage of sugar beets, would 

 answer the purpose; or the material may be windrowed in piles and 

 permitted to hopper itself, the danger of its rotting in the hoppers 

 being obviated by this plan. 



All hoppers, both in the storage building and over the digesters, 

 as well as all other parts of these buildings coming in contact with 

 the hogged and shredded waste, should be either of steel or of heavily 

 creosoted timber construction in order that decay may be avoided. 

 The green shredded wood makes an ideal medium for the cultiva- 

 tion of wood-destroying fungi, and even in exposed places too dry 

 it would seem, for decay to take place, the writer has found it pro- 

 gressing rapidly wherever there were accumulations of fine stuff. 



DISINTEGRATING EQUIPMENT. 



The disintegrating equipment should consist of hogs or chippers, 

 shredders, and screens. A chip one-half an inch long in the direction 

 of the grain will be penetrated thoroughly with acid, but the ease 

 with which the sugar can be leached out is a problem that requires 

 attention. However, as the residual digested sawdust or waste after 

 extraction is ample for power production, and as all exhaust steam 

 from the engine has value for heating and distillation purposes, the 

 extra power required to chip down to a three-sixteenths or one- 

 quarter inch chip would not be prohibitive, and the greater efficiency 

 of extraction would probably make the chipping down very desirable. 

 After being screened — for the screenings should be reshredded — the 

 fine stuff should go by belt to the loading bin over the digester. 



SAWDUST AND ACID STORAGE. 



The loading bins should be of sufficient size to serve as intermediate 

 storage for the material as it comes from the screen on its way to the 

 digester. Each of the bins should hold several digesterfuls and 

 should be placed over the digester, being tapered down so that the 

 material may flow directly into the digester, according to the arrange- 

 ment in chemical-pulp plants. 



The acid intended for the plant should be in concentrated form, 

 to permit of shipment in tank cars and storage in steel tanks. The 

 concentrated acid should be pumped into a lead-lined tank above the 

 digester and be diluted in order that the dilute acid may flow into 

 the digester along with the sawdust. If rotating digesters are used, 

 no special mixing apparatus will be necessary; at least, no appre- 

 ciable quantities of uncooked material have ever been found at the 

 Forest Products Laboratory when such digesters were used. 



