46 MANUFACTURE OF FERTILIZING MATERIALS 



ported. The time is not far distant, however, when 

 an equally strong demand will come from the ex- 

 hausted soils of our own country. The hydraulic 

 and steam-shovel methods of stripping the over- 

 burden and the mining of rock, to a certain extent, 

 is described in Chapter I of this work. In the 

 pits in the hard rock section, steam dipper dredges 

 are used, which load the skips that are hauled up an 

 incline and delivered to the top of the washer. 

 The phosphate ore thus carried from the pits is 

 dumped upon " grizzlies, " where it is sized. That 

 which passes through the bars of the "grizzlies" 

 is ready for sizing by the " separator, " or trommel, 

 but that which is too large to pass through the bars 

 is broken by hand with a pick, axe or dynamite 

 and made ready to pass through the bars of the 

 grizzly. The ore passing into the "separator" 

 is sized for the first time for the set of double 

 log washers where it receives its first treatment 

 for the removal of the clay which adheres to 

 the phosphate material. That part of the ore 

 which is too large to pass through the per- 

 forations of the revolving screen, passes out 

 the lower end and falls into a roll-jaw crusher 

 and after being crushed it falls through a chute 

 into the first set of log washers where it is 

 washed with ore which has been sized by the re- 

 volving screen or trommel. In the log washer, one 

 end of the washer revolves in a gudgeon placed 

 below the water in the box containing the ore to be 

 washed; the other end works in journals. The 



