A grizzly screen or deck is a simple way to separate oversized rocks before they are fed into a crushing unit that will be crushed into smaller pieces for further processing. There is a rich history behind grizzly screens, as they were first used a few hundred years ago when mining first became mechanized. Since then, grizzly screens/decks have evolved into essential equipment which enhances the automated refining operation of the modern era.
Development of the Grizzly Screen
The early grizzly screen was a series of metal bars that miners used to separate or size the rocks and feed it into the refining process. The workers simply spread the material over the bars and moved the screens back and forth by hand.
Over a 100 years later, the grizzly screen became automated by employing a motor-run vibrator to help separate the various sized rocks. This flat design was used for years, but lacked the efficiency for faster processing. Modern grizzly decks now incorporate a sloping design and vibrator into a hopper. Some units have multiple grizzly decks to improve sorting of the material.
The Best Steel for Grizzly Screens
The bars of any grizzly screen takes a horrendous pounding so wear becomes the main issue. When the bars have to be replaced, the entire production line must be shut down and the worn bars removed and replaced. This can take days and the downtime costs significantly more than the cost of a new grizzly.
Recently, some mines and quarries have begun making steel grizzly decks from ENDURA and ENDURA Dual with titanium carbides. These 2 steels both have the ability to “Work Harden”, meaning the more they are impacted, the harder they get. Hit them once and they get harder, hit them again and they get even harder.
They also have something called TRIP EFFECT (Transformation Induced by Plasticity). 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. By diffusing the pressure of the impact, you massively reduce the damage to your hand, and the same goes for the grizzly bars.
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As a Mine Manager once said: “it’s not the cost of the steel, it’s the cost of the down time”.