Lesson 2
ANSWER SHEET FOR PRACTICE EXERCISE
1.
a.
Type of rock being crushed
b.
Feed size of raw material
c.
Size of finished product desired
2.
a.
Assignment of rock crushing tasks
b.
Adequate lead time for rock crushing plant design and erection
c.
Maintenance of equipment and facilities
d.
Coordinate quarry and rock crushing operations
e.
Calculate production rates
f.
Establish priorities of aggregates
g.
Record rock crushing operations statistics
h.
Evaluate rock crushing operations
3.
Top screen for 1 3/4 inch aggregate is a 2 inch screen.
Bottom screen for 3/8 inch aggregate is a 7/16 inch screen.
4.
Product setting is 1 3/4 inch roll crusher setting
Stage of reduction is 1 3/4 inches
Maximum feed size is 3 1/2 inches by adding product setting and stage of reduction.
5.
Jaw setting for 3 1/2 inches jaw crusher product is 3 inches.
6.
a.
Jaw capacity (20 x 36 in.) is 110 for 8 inch jaw setting (Table 5).
b.
Material hardness production factor is 0.80 for fine-grained granite (Table 6).
c.
Calculate 110 x 0.80 = 88 tph.
7.
a.
Interpolate roll crusher capacity from Table 7 (p.55) for 30 x 24 inch rollers. Product site is 1 3/4
inches, which is halfway between 1 1/2 and 2 inches. Calculate (125 tph + 175 tph) + 2 = 150
tph.
b.
The material hardness production factor is 0.80 (Table 6).
c.
Calculation:
Roll crusher capacity x hardness factor = capacity in tph
150 tph x 0.80 = 120 tph
72
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