Another take: Crusher safety

By |  July 18, 2015

Kelly Graves, senior technical sales manager at Kleemann, offers his thoughts on crusher blockages and some solutions that have helped to minimize the problem over the years.

P&Q: How much of a problem are crusher blockages today, and how does the procedure of clearing a crusher today compare with clearing one in the past?  

KG: Blockages create downtime, which lowers production and decreases tons per man-hour. With the advancement and increased use of hydraulics, downtime is greatly reduced.

Compared to the old-style machines utilizing mechanical devices to open the crushing chamber, the hydraulic machines are much faster and more importantly safer than machines of the past. Clearing blockages on a newer hydraulic machine can be as simple as pushing a button on the crusher control cabinet or remote control, or reversing the motion of the swing jaw with the flip of a switch.

P&Q: How do you and Kleemann work with customers to address the blockage issue?

KG: We try to teach producers and recyclers the importance of material prep and feeding concepts to minimize crusher blockages. For example, feeding a portable or track machine in a recycle application is best with an excavator from an elevated position. Position the excavator in such a way where you can see into the feed hopper and feeder.

By using this method, you can see material that may be too large for the crusher inlet, or perhaps see a non-crushable before it enters the crushing chamber.

P&Q: Does one application – aggregates or recycling – encounter more crusher blockages than the other?

KG: Recycling applications tend to create more blockages than aggregate. In an aggregate application, the material appears more uniformed and provides a more consistent feed to the crusher, whereas recycle material, specifically concrete with rebar, tends to be less consistent in size and shape.

A recycle application contains material that is not conducive to crushing such as wood, steel, trash and soils. These types of material increase the probability of a crusher blockage.

Preparation of recycle material is essential to minimize crusher blockages and downtime. Removing as much steel, rebar and soils prior to crushing will greatly reduce crusher blockages. The use of hydraulic processors, hammers and shears creates a more consistent feed size, [and it] separates the steel and rebar.

P&Q: What other factors have helped to minimize blocked crushers as a health and safety issue?

KG: Machine design has also played an important role in minimizing blocked crushers. For example some impact crushers utilize an inlet hood that will rise hydraulically to allow more clearance into the crusher feed opening. This feature is especially important in the recycle industry.

Another design feature is the material flow concept. Think of this concept as an upside-down funnel. The feeder is smaller in width than a pre-screen or a crusher with the discharge belt being the widest. This feature reduces bridging, increases the dimensions of transfer points throughout the machine, and increases material flow through the machine.

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