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.
Get Grizzly Screens & More From Us
As a Mine Manager once said: “it’s not the cost of the steel, it’s the cost of the down time”.
Steel is a type of iron alloy that has a much lower carbon content than Wrought Iron or Cast Iron, as we discussed in a previous blog. The first thing to remember about steel is that it’s made from Iron. There are also thousands of different types of steels formulated and made to perform specific tasks under various working conditions. Conveniently, these can be grouped into 4 general classes of steels. (more…)
Most people refer to IRON as STEEL and STEEL as IRON. However, these are two very different products. Iron or iron ore is the fourth-most abundant element on the planet and can be found and mined in the earth to make various steels, cast iron, wrought iron, high/low alloy steels etc. Iron ore is the base element to make all grades of iron and steels, and is also an essential mineral which helps make hemoglobin in the human body. (more…)
When discussing abrasion resistant steel two terms that will often come up are ‘Hardness’ and ‘Hardenability,’ and while they may sound like the same thing because they have the same etymological root, they refer to very different aspects of abrasion resistant steel. While hardness is a characteristic of steel, hardenability describes the ability to do it. (more…)
Heat treating is a process used to change chemical and mechanical properties of wear resistant steel produced in its original form. A common example of this is heating the material to high temperature, quick cooling with water or oil (Quenching) and then re-heating at lower temperatures (Tempering).
Annealing, Normalizing and Stress Relieving do not involve any Quenching or Tempering. (more…)
What Does ISO Stand for?
Customers often inquire about our ISO Certification. ISO stands for “International Organization for Standardization”,despite the fact that the letters are out of sequence. The name in different languages results in different acronyms. Thus, all 164 countries (who use ISO) agreed to use the ISO designation. (more…)
What Is a Waterjet Cutter?
A waterjet cutter is a versatile industrial tool that can be used to cut a wide variety of wearresistant steels and other materials such as wood and glass. The waterjet cuts through material by combininga very high-pressure jet of waterwith fine particles of garnet (60,000 to 90,000 psi). This combination “gouges out” or removes tiny particles of the wearresistant steel, which effectively makes the cut. Water alone with no garnet can be used to cut softer material such as wood, plastic or rubber. (more…)
Austenite and Martensite, in steel, refers to the microstructure of steel at the atomic level. During the tempering process or cooling, Austenite is transformed intoMartensite. The ideal wear resistant steel would have a combination of retained Austenite as well as some transformed Martensite. (more…)
All steel mills produce standard sizes of bars (i.e. flat, round, square) and plates (i.e. 48” x 96”, 96” x 240”, 120” x 288” etc.). Consequently, the fabricator must have equipment to cut the bars or plate to a size which they can use for further processing. Other than shearing, sawing, grinding or water jet, wear resistant steel is usually cut using heat to melt the material. There are 3 main processes and each has its advantages. (more…)