Grizzly screen

Types of Grizzly Screens

A grizzly screen, also known as a vibrating grizzly feeder, comes in various types. These are generally used to reduce and filter materials. Splitters, grids, bars, classifiers, and g's honeycombed are some types of grizzly screens where the materials are divided through a honeycomb structure or grids and bars. The idea is to analyze or separate particular materials. Other types include vibrating, static, and trench grizzlies.

The working principle of vibrating feeders is similar to that of the feeder and screen machine combination, but its amplitude is larger, and the frequency is higher. Static grizzlies are simply a set of angled bars or rods placed in a fixed position. Larger rocks fall through, while vibrating ones shake and segregate particles in a similar fashion. Grizzly screens are usually installed at the beginning of processing lines and can be found in quarries, mines, and recycling centers.

Framed and tubular grizzlies are another example; framed ones have a rectangular frame, and tubular ones are made with pipes, usually fixed at an angle. Framed ones are more common and preferred because the rectangular frames are easier to stack and can carry heavier weight.

Heavy-duty vibrating grizzlies use a large vibrating motor to shake the screen and separate larger materials. Some have variable speeds to adjust how fast they work. Another distinction is static and mobile grizzly screens. A static one is fixed at an angle, while a mobile one can be moved and adjusted according to requirements. They are usually connected to a hopper that can be adjusted according to need.

No matter the type, all grizzlies are designed to optimize production, minimize downtime, and improve safety. They do this by ensuring that only the right-sized materials proceed further down the processing line.

Specification and maintenance of grizzly screens

Specification

• Dimensions

  The overall dimensions of the grizzly screen are critical for compatibility with upstream and downstream processing units within the material-handling circuit. Typically, the width of a grizzly screen ranges from 2 m to 4 m, while its length varies from 4 m to 12 m, depending on the material quantity and the screen's separation efficiency requirements.

• Screen Type and Materials

  The screen type of a grizzly screen affects the characteristics of the material separation. Common grizzly screen types include steel rod screens, traditional grizzly bars, and diagonal plate screens. The screen materials are often made of high-strength steel to ensure that the screen can withstand the abrasion of various materials and harsh operating environments.

• Screen Separation Size

  The screen separation size determines the screen's capacity and material separation efficiency. The screen separation may be adjustable based on the specific application to meet different processing requirements. Generally, the separation size ranges from 50 mm to 150 mm.

• Supporting Structure

  The supporting structures of a grizzly screen provide support and fixation for the screen. They also determine the screen's installation method and the height of the feed inlet. Common supporting structures include steel frames, concrete platforms, etc.

• Vibration System

  Some grizzly screens are equipped with a vibrating system to enhance the screen's capacity and separative efficiency. The parameters of the vibrating system include the motor power, vibrating frequency, and amplitude, etc. For example, the motor power may range from 5 kW to 15 kW.

Maintenance

Grizzly screens play a critical role in material separation and handling. Regular maintenance is vital for their long-term and efficient operation, ensuring the separation accuracy and quality of the materials. Here are some critical maintenance methods for grizzly screens:

• Regular Inspection

  Users should formulate a regular inspection plan based on the operating conditions and specifications of the grizzly screen. They should routinely check whether the components of the screen are worn, deformed, or damaged. Pay particular attention to the separation bars and screen frames. Timely repair or replacement of the damaged parts can prevent small particles from passing through the screen, which would defeat its purpose.

• Lubrication and Maintenance

  Users should maintain and lubricate the supporting frames according to the grizzly screen's lubrication manual and schedules. Regularly lubricating screen supporting frames ensures proper screen operation. During this process, users should also clean the debris on the screen support and check for any blockages in the drainage system, thus preventing overheating and extending the life of the screen supporting frames.

• Tension Adjustment

  With time, the screen may become loose due to material abrasion and vibration. Therefore, users must periodically check the tension of the screen and adjust it if necessary to ensure that the screen operates stably and performs its separation function effectively.

• Hazard Prevention

  Users should regularly check for potential hazards around the grizzly screen, such as equipment, materials, and personnel. They should ensure that the vicinity of the screen is adequately managed and that safe distances are maintained to prevent overload and damage to the screen.

• Cleanliness

  Users should establish a cleaning schedule and remove materials and debris that accumulate on the grizzly screen in a timely manner to prevent recontamination and improve the separation efficiency of the screen.

Uses of grizzly screens

Due to their simplicity and robustness, grizzly screens have a broad spectrum of uses in various industries such as construction, mining, recycling, and agriculture.

• Mining: Grizzly screens are valuable assets in mining operations. Here, they help filter out oversized ores, rocks, and debris from mined materials before transporting the correct sizes to crushers.
• Farming: In agriculture, grizzly screens are used in livestock feeding situations where large hay bales are broken up for cattle or horses. They can also separate unwanted weed seed hoppers and aggregate foreign objects from crops.
• Water Treatment: Grizzly screens act as primary water treatment facilities in waste treatment plants. They capture large solids, such as sticks, leaves, and debris, before passing flow into the screening process.
• Construction: In the construction industry, grizzly screens help break up large aggregates and separate finer coal, material, sand, and slag. They also separate large construction debris, including forms, wood, and plastic, from reusable aggregates like concrete and asphalt.
• Coal and Bulk Material Handling: When handling coal and other bulk materials, grizzly screens separate unwanted oversized materials, such as slate and stones, before they enter belt conveyors.
• Pebble and Stone Separation: Grizzly screens are used to separate pebbles and stones in riverbeds or shorelines. Here, they detect and capture large stones while smaller particles flow through. This operation is sometimes referred to as "stone fishing."

How to choose grizzly screens

When selecting the appropriate grizzly screens, attention needs to be paid to numerous factors which are intended to meet the requirements of specific applications and circumstances while ensuring efficiency, safety, and cost-effectiveness.

• Material Characteristics

Industrial materials' features, including kind, size, and weight, should be considered. Iron ore has a different screening requirement than food products because of the unique characteristics of its materials.

• Screening Efficiency and Capacity

The screening efficiency and production capacity must match the processing requirements of enterprises. Choosing a screen with sufficient capacity can prevent future bottlenecks and delays in industrial processes.

• Structure and size

The design, such as the screen angle and aperture, affects the separation effect. The dimensions of the grizzly screen, including length, width, and height, should fit the available space and connection requirements of the entire production line.

• Durability and Maintenance

Consider the screen's durability and maintenance requirements. Selecting screens with prolonged lifespans and simplified maintenance can reduce long-term operating costs and downtime.

• Energy Consumption and Cost

It is necessary to consider the factors, including energy consumption, spare part costs, and service expenses, to estimate the overall operating costs of the equipment to select an economically viable solution.

• Safety and Environmental Requirements

Safety standards and environmental regulations should be taken into consideration to ensure that the chosen equipment conforms to the necessary safety requirements and environmental norms, thereby mitigating risks and potential legal penalties.

Grizzly screen q and a

Q1: How are grizzly screens different from traditional screens?

A1: Grizzly screens use a rake-like design to separate products by size. They rely on an open-frame structure and different sized gaps to separate coarse materials. On the other hand, traditional screens use woven mesh to separate materials of different sizes.

Q2: Can people build DIY grizzly screens?

A2: In some cases, people can build grizzly screens if they have the skills and experience to handle the materials and build the screen effectively. However, it is always better to buy screens if they are available in the local market.

Q3: Are grizzly screens used in conjunction with other types of screens?

A3: Yes, in some cases, grizzly screens are used along with other types of screens. They may act as primary separators in the system, while other screens may separate materials further after the grizzly screen separation.

Q4: What handling capacity do grizzly screens offer?

A4: The handling capacity of grizzly screens depends on the machine's dimensions and the material's characteristics. However, large-scale screens can have handling capacities of over 1,000 tons per hour.