Tertiary DDC-Sizers

Tertiary DDC-Sizers can be used in surface and underground mining operations for the tertiary reduction of friable, low-silica materials, such as coal, salt, gypsum, phosphate, limestone, bauxite, petroleum coke, lignite, trona, carbon anodes, oil sands, clay, shale and more. Unlike Primary and Secondary DDC-Sizers, which feature inward rotating rolls, the tertiary design features outward rotating rolls. This provides two crushed product streams in one machine and allows feed material that is already to size to pass through the openings between the rolls, minimising additional fines from inter-particle crushing.

Why McLanahan Tertiary DDC-Sizers

McLanahan Tertiary DDC-Sizers have a direct drive arrangement and low-profile design that allows wheel mounting for a movable configuration. The preferred method of installation is to mount the unit on rails with a non-rigid connection between the feed and discharge chutes. Equipped with hydraulic lift cylinders for ease of wheel activation and drive arrangements that are attached to the mainframe of the sizer, the unit can be rolled out from the feed stream to facilitate maintenance.

The Tertiary DDC-Sizer frame is a heavy-duty fabricated steel assembly with easily replaceable wear parts. The crushing rolls consist of interchangeable alloy steel segments bolted to a heavy-duty barrel. The shafts are supported through self-aligning double row spherical roller bearings.

The drive configuration consists of an electric motor, fluid coupling and gear reducer. A combination of underspeed sensors and fluid couplings protect the drives in the event the sizer encounters a stall condition.

How Tertiary DDC-Sizers Work

Tertiary DDC-Sizers are compact direct drive crushers that feature low-speed outward-rotating rolls that accept a constant, controlled feed rate of material and size the feed against adjustable sizing combs. The material that is already to size can pass around the crushing zone, which helps in generating less fines.  

Popular Applications for Tertiary DDC-Sizers

Tertiary DDC-Sizers are typically used in applications where the material being crushed lends itself to compression crushing rather than attrition crushing or impact crushing.

Coal, salt, phosphate and other friable materials are very common applications where DDC-Sizers are specified. DDC-Sizers deliver excellent control on product size and consistency.

The standard ratio of reduction is 4:1; therefore, it is common in applications that require higher ratios of reduction to have multiple units running in series to accomplish the necessary reduction.

Benefits of McLanahan Tertiary DDC-Sizers

  • Minimum dust and fines generation
  • Can fit in low headroom areas
  • Provides a smaller footprint
  • Product setting size can be adjusted if requirements change
  • Interchangeable segments and sizing combs throughout the machine
  • Rail-mounted to be rolled out from the feed stream to facilitate maintenance or tramp removal
  • Replaceable/interchangeable crushing elements.

Frequently Asked Questions

How can I gauge tooth wear?

You can check tooth wear by measuring the height of the tooth from the base and comparing it to the as supplied tooth height. You can also use a tooth profile template to accomplish this.

To build up the tooth profile on some types of sizer teeth, consider hardface welding to increase throughput capacity.

How important is even feed distribution?

Even feed distribution allows even wear across and along the rolls, maximizing the life of the wear parts as well as the capacity of the sizer.

How often should I grease the gear reducer shaft seals?

Once a week. Make sure you add enough grease that all old grease is purged from the seal.