B52 University Geological Survey of Kansas. 
WEAR OF ROLL SHELLS. 
The wear on shells is: First, on the edges: second, on the 
middle. Combined with the wear in the edges is a tendency 
to chip off, due to the roll shells striking together when un- 
der high tension. If the feed of the rolls is directed to one 
point, most of the wear comes there, thus causing the rolls 
to wear unevenly and in ridges, giving the surface of the 
roll a corrugated appearance, which in time break up into 
rings along the linesof weakness. As the roll shells are con- 
stantly wet with the acid waters, their wear and ultimate de- 
struction are hastened. The average life of a set of roll shells 
is: For the first set, three to six weeks; second set, four to 
seven weeks; third set, seven to ten weeks. For the first 
set, when made of steel, the average life is six weeks; for 
iron roll shells, about three weeks. The steel shells average 
600 pounds apiece, 1200 pounds per set, which, at 15 cents 
a pound, makes $90 apiece, or $180 per set. Iron shells cost 
10 cents per pound, and range in price from $60 to $120 per 
set. The price per week would then be $30 and $40, respect- 
ively, or $4.28 and $5.71 per day. : 
WEAR OF ELEVATOR BUCKETS. 
The wear of elevator buckets varies with the size, character 
and quantity of material handled. The dirt elevator, carry- 
ing all the material which passes through the crusher, has 
the most wear. The tailings elevator probably carries the 
next to the largest amount; ‘‘chats’’ elevator comes next in 
order of amount carried ; while the ‘‘smittem’’ elevator car- 
ries the least in bulk, but not necessarily in weight. The 
wear, therefore, comes proportionately on the different ele- 
vators. The wear may, however, depend more on the 
character of the material handled than on the amount. The 
two cases below illustrate this point. 
Wikevotadittwe leva tOrsOUCKC Lenehan ene 5 to 10 weeks. 
Life of tailings elevator buckets............... 8 to 12 weeks. 
Wikevotachatsrelevatonioucketse eee 11 to 15 weeks. 
liikevorsmittemnelevatorlbucketsmena eerie 15 to 20 weeks. 
Or, in a special case noted : 
’ Life of tailings elevator buckets............... 11 weeks. 
IGE Oie Choy SEANROIP |OWCOESUS 6 oc cccgoecovoudecd 3 to 4 months. 
Life of smittem elevator buckets.............. - 6 months. 
