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STATE GEOLOGIST. BS 
bins, side by side, one for the limestone and one for the clay. Here 
they are weighed out by means of a double scale and dumped into a 
large mixer of the granulator type consisting of a large box, V-shaped, 
in cross section, in which, at the bottom, a screw conveyor shaft revolves, 
carrying also larger mixing blades. The shaft is to be very heavy. The 
bottom of the mixer slopes from the discharge end down to the inlet end 
so that the space at the inlet end is far greater than at the discharge end 
and can be made to hold several tons of material. Being about 106 feet 
long, the mixer discharges the raw stock in a steady stream into a screw 
conveyor, not less than 8 feet long, which feeds another smaller storage 
bin, from which the ball-mills are supplied. This bin thus brings about 
additional mixing and blending. Since the material has. been through 
an intermediate grinder before, the ball-mill has a greater capacity and 
its principal function is to produce further mixing and blending  to- 
gether with additional grinding. Two of these mills should supply four 
tube mills without any difficulty. Thus, starting from the separate lime- 
stone and clay bins, we have the following equipment: 
double bin, 
scales, 
mixer, 
screw conveyor, 
feeding bin, 
ball mill, 
tube mills, 
storage bin over kilns, 
1 rotary kilns. 
} clinker cooler, 
k Kent mill, 
1 wind separator, 
m Griffin mill, 
n to storage bin. 
Sats Yehe) fam (9) (Gly (2). jor YO 
The principal advantage claimed for this arrangement is the fact 
that the mixture is under the best control possible in a dry plant, since 
storage bins are provided for, which permit of analyzing and checking 
the limestone and clay in bins which are independent units. Until 
analyzed and approved by the chemist, the bin is not to be emptied. 
By calculating the mixture for one limestone bin and one clay bin, 
which is considerably smaller, these two bins are emptied and_ their 
contents weighed out in the proportion calculated. By supplying each 
bin with an automatic sampling device on top its exact average compo- 
sition may be obtained. Of course it is important that the bins be not 
too large. Such an arrangement would lessen one of the greatest ob- 
jections to the dry process in which, as it is well known, errors in the com- 
