If you are working in the aggregate industry, you will need to get intimately familiar with screening plants. Screening plants, in general, work to separate large materials from smaller ones, so that each aggregate application has materials of the proper size(s).
Beyond that basic commonality, though, there are many varieties of screening plants that function in different ways to achieve different functions. They are set up to accept different types of material inputs and deliver different types of material outputs.
Static Screens
A static screen is the most basic type of screening plant. It just consists of one or more stationary screens with holes that catch large materials but allow small materials to fall through.
Static screens can be just a single screen or multiple screens. The screens can be level to catch the large materials or angled to encourage the materials to slide off to one side.
Although the screens are static, there may be a conveyor to collect the fines that pass through the screen(s). Static screens are more likely to reject fines than pass large items, and extracting maximum value from the raw input might require putting the reject pile back on the screen.
Static screens are easy and inexpensive to operate. They can be used in all industries including aggregates, demolition, recycling, agriculture, and more.
Scalping Screen
A scalping screen is a rough-sorting screen that uses vigorous shaking motions to rapidly separate different grades of material. They are typically first-sort screens that separate out materials that might be problematic for later machinery. Scalping screens separate out large materials, wet materials, and sticky materials from the feed to avoid clogging or damaging later machinery.
Scalping screens most often use grizzly bars separated at a specific distance to limit the passage of material. The grizzly screen allows for rapid separation but doesn’t ensure that separated materials are uniform in all three dimensions. Because of this potential for uneven sorting, scalping screens are not usually considered final screening plants.
Precision Screen
Unlike scalping screens, precision screens are often used to produce one or more final grades of aggregate. These screens generally differ from scalping screens in three ways:
- Mesh screens or perforated metal instead of grizzly bars
- Less vigorous shaking
- Slower throughput
The less vigorous shaking and slower throughput encourage material to fit through the screens in a way that is consistent with all three dimensions fitting the desired dimensions. This means that the sorted materials are more uniform with fewer oversized items. Precision screens are designed to work as final screening plants. The products that they produce are ready for sale or use in specific applications.
The biggest disadvantage of precision screens is that they process materials more slowly, which means that they can’t handle as much production as scalping screens.
Trommel Screens
Trommel screens are a type of rotating screen. They have a drum or barrel that rotates on its axis, like the interior of a clothes dryer. The drum has holes in it that allow small materials to pass through, while larger materials are retained in the drum, either for disposal or further processing. There is also a corkscrew structure within the drum to encourage the movement of material through the trommel screening plant
Trommel screens are favored in agricultural, soil, and waste management applications, but they can be used in all industries, including mining and aggregate processing.
Star Screen
Star screens get their name from the star-shaped wheels within the plant that propel materials along. These wheels are attached to numerous shafts within the plant that rotate, driving large material from the input port to the output area while allowing small material to fall through, where it is collected by a conveyor and moved to a different output area.
Star screens are popular for sorting organic components, such as peat moss, compost, mulch, soil, bark, manure, and wood shavings. The stars are typically rubber or polyurethane, allowing them to gently handle soft materials, but are typically unsuited for rocks and metal.
Rip Rap Plants
Rip rap, also known as shot rock or rubble, is an erosion control measure that protects the land from destruction by moving water. The stone should be hard and angular with a mixture of sizes to help stabilize and fill the bank or coastline. Although rip rap can be harvested directly, it is most often quarried and processed to create the ideal shape and size distribution.
Because of the different source materials for rip rap, rip rap plants are often composed of multiple components, which may include:
- Jaw crusher
- Impact crusher
- Cone crusher
- Screen(s)
The crushers take suitable rocks that are too large for the application and break them down. These rocks are then screened to form portions in different sizes, which can then be remixed in proper proportions to create the most effective rip rap for the application.
Help Finding the Right Screening Plant for Your Operation
Are you looking for a screening plant in Colorado, New Mexico or Utah, but aren’t sure what kind you need? Let the experts at Power Screening help. Since 1984, we’ve been helping people in many industries find the perfect screening plant for their needs. We work with people in:
- Aggregates
- Construction
- Demolition
- Agriculture
- Waste management
- Recycling
As well as many others. No matter the application, we have probably helped someone find the right equipment for it.
We’ve been able to stay in business for more than 40 years by focusing on developing long-term relationships with our customers. We want to deliver heavy equipment that you will be happily using for decades. We’ll match the machine to your needs and help you perform the maintenance necessary to extend the life of your equipment.
Not ready to invest in new heavy equipment? We also rent equipment and sell used machines so you can get the performance you need at a price point you can afford.
Please contact Power Screening today to get matched to the ideal machine for your operation.a