Lesson 1/Learning Event 3
The primary unit (Figure 13) is used to accomplish the first stage of reduction of quarry run rock.
The primary unit is so large that it would not be practical to use it in gravel deposits.
The first intermediate unit (Figure 14) is used to receive material from the jaw crusher and
accomplish a second stage of reduction. It can also be used very effectively as a primary or first stage of
reduction unit in gravel deposits. It may be used to produce a finished product and to reject fines.
FIGURE 13. MATERIAL FLOW THROUGH THE PRIMARY CRUSHER
UNIT OF A 225-tph CRUSHING AND SCREENING PLANT