A steel grizzly screen (sometimes referred to as a grizzly deck, a grizzly scalper, or a grizzly feeder) is a rugged heavy-duty type of screen that is placed just before the first crusher in a mine or quarry. It “sizes” the rocks that have been blasted from the mine or quarry so that the crushing machine (often a jaw crusher or cone crusher) is not fed oversized rocks it cannot handle or undersized “fines” which will slow production.
There are several ways that a steel grizzly screen can be set up. Sometimes the grizzly is on an incline or circular and vibrates to ‘sift out’ appropriate-sized rocks, while others are stationary and flat, so that the oversized rocks can be ‘broken apart’ by a hydraulic jack right on the screen itself.
Steel grizzly screens have to compensate for an extreme amount of stress, which is why it is typically made of work-hardening manganese steel. With steels such as Titus Manganese, the more impact the steel experiences, the harder it gets—and the harder it gets, the longer it lasts.
More recently, some mines and quarries have begun making steel grizzly screens from ENDURA and ENDURA Dual with titanium carbides. These have the ability to work harden as well, but also have a TRIP EFFECT (Transformation Induced by Plasticity), which is achieved by the spontaneous rearrangement of metallic atoms under stress.
To understand how the TRIP effect works, think of catching a baseball. If you hold your hand in a rigid position, the ball crashes into and damages your hand. Now imagine letting your hand “give a little” as you catch the ball, like closing a catcher’s mitt. By diffusing the pressure of the impact, you massively reduce the damage to your hand.
Much like your hand in a catcher’s mitt, the TRIP effect of ENDURA and ENDURA Dual reduces the damage of particularly heavy impacts of rocks, gravel, and other abrasive materials, often outlasting other steel grizzly screens by a surprising amount. ENDURA and ENDURA Dual might be a little more effective than the old standards, but they don’t need to be replaced nearly as often.
And as a Mine Manager once said: “it’s not the cost of the steel, it’s the cost of the down time”.
If you want to learn more about the various applications of Titus’ steels, check out our other articles. If you’re interested in learning more about any specific steel mentioned, or if you’d like a hand figuring out which steel is right for your particular application, feel free to give us a call.