40 Questions
What is the primary function of a primary crusher?
To reduce the particle size of the stone
What is the primary advantage of true gyratories as primary crushers?
They provide continuous crushing
What is the purpose of screening in aggregate production?
To separate the aggregate into different size ranges
What is the main difference between jaw crushers and true gyratories?
Jaw crushers can handle slabby material well
What is the final step in the aggregate production process?
Handling and moving the crushed materials
What is the purpose of washing in aggregate production?
To eliminate undesirable materials from the aggregate
What type of crusher is commonly used for primary crushing by hurling the stone against interior steel apron walls?
Impact crusher
How many crushers may the stone pass through before it is reduced to the desired size?
Four or more
What is the purpose of the eccentric bushing in a cone crusher?
To produce the gyratory effect as the shaft rotates
What is the unit weight of the material used in Table 13.5?
100 lb/cf
What is the main function of roll crushers?
To produce additional reductions in the sizes of stone
What is the advantage of single roll crushers?
Simplicity in design and operation, compact size, and ease of maintenance
What is a limitation of single roll crushers?
They are not suitable for materials that are very hard or abrasive
What is the main difference between a single roll crusher and a double roll crusher?
The number of rolls
What is an advantage of double roll crushers?
They are compact in design and have high capacity
What is the surface of the rolls in a roll crusher?
Either smooth or textured with narrow beads
What characterizes gyratory crushers?
Gyrating mantle within a deep bowl
What is one of the major advantages of gyratory crushers compared to jaw crushers?
Higher capacity and uniform product size
What function does the spring-loading or hydraulic adjustment serve in gyratory crushers?
To protect from uncrushable objects and overload
What indicates an excessive feed rate in a gyratory crusher?
Surge of aggregate at the top of the shaft
What distinguishes a cone crusher from a true gyratory crusher?
Shorter cone and higher speed
What is a notable disadvantage of gyratory crushers?
More complex maintenance requirements
What is the material of the conical head on a cone crusher typically made of?
Manganese steel
What is a balance goal for optimizing gyratory crusher performance?
Highest allowable feed rate and closed setting for required product size
What size of finished product is achieved with a roll setting of 20 in. in roll crushers?
Finished product size of 20 in.
What is the key difference between horizontal shaft impactors (HSI) and vertical shaft impactors (VSI)?
Rotor orientation
What are the two main configurations for the number of rotors in impact crushers?
Single and double
Which is NOT an advantage of impact crushers?
Suitability for high-abrasiveness materials
What production rate can primary and secondary phase models of impact crushers achieve?
Over 800 tph
Which materials are commonly reduced using impact crushers?
Limestone, concrete, and asphalt
How do single-rotor impact crushers break down stones?
By impact action and striking against aprons
What factors affect the production rate of single-rotor impact crushers?
Rotor speed
What is a key disadvantage of double roll crushers?
They are not suitable for very hard or abrasive materials.
What is a distinct feature of triple roll crushers?
They provide two-stage reduction in one crusher assembly.
What is the relationship between feed size and roll diameter in roll crushers?
Feed size is directly proportional to the roll diameter.
How do triple roll crushers handle stone differently than double roll crushers?
They use a two-stage reduction process within one crusher.
What is one advantage of triple roll crushers?
They offer high capacity and efficient crushing performance.
What angle is defined as the angle of nip?
16°45′
What does the equation $D = R ext{cos} B = 0.9575R$ represent in roll crushers?
The maximum feed size.
What limitation is associated with triple roll crushers in terms of installation?
They may have a larger footprint and require more space for installation.
This quiz covers the characteristics and uses of gyratory crushers, including their efficiency and continuous crushing action. Learn about the benefits and features of these primary-type crushers.
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