Scalping is typically the first screening process and is used to remove material that’s difficult to screen, like clay-bound material. Because scalping screens are located early in the flowsheet, they have to be robust and heavy duty, capable of handling oversized material. For this reason, all Weir Minerals’ Trio scalping screens feature all-bolted construction using locking bolts to ensure structural integrity.
Weir Minerals’ range of Trio scalping screens generate maximum excitation to stratify the material and remove as much undersized material as possible. Weir Minerals has two ranges of scalping screens: the Trio TIOSP and the THDS series. Both are available in stationary and mobile options and suitable for wet and dry applications. Both the Trio TIOSP and THDS are utilised in aggregate processing and industrial minerals screening applications, environmental mitigation and recycling separation processes.
There are some key differences, however; they differ in terms of where they feature in the flowsheet and they each have different design features as a result of that. The Trio THDS is usually utilised in primary screening applications, whereas the TIOSP can be used in secondary screening and final sizing applications, depending on the material.
Removing clay-bound material
Trio THDS scalping screens have long been a fixture in quarries, where it’s important to remove clay-bound and reactive material from the feed as quickly as possible to ensure it doesn’t contaminate the hard rock that’s required to make concrete. Weir Minerals has had a lot of success installing Trio THDS scalping screens in limestone applications, for instance.
Limestone absorbs a lot of moisture and, in applications where the moisture level is above 3%, scalping screens are often required, as opposed to using vibrating grizzly feeders. When the moisture level is 5% or above, scalping screens become non-negotiable; at these levels, the material acts like plasticine when it enters compression crushers, inhibiting performance and potentially damaging the processing plant.
It’s in the best interests of operators to remove this material as early as possible, which the Trio THDS scalping screen – generally, used in conjunction with the Trio EF series pan feeder to ensure even process flow – does effectively. Having removed this ‘sticky’ material, it can then be treated separately, ensuring that the processing plant operates efficiently and all the valuable ore is recovered.
Trio THDS series
Trio THDS scalping screens are usually placed between the ROM (‘Run Of Mine’) bin and primary jaw crusher; they have to be rugged and robust enough to handle large lump sizes, up to 700mm. They’re engineered to remove undersized material. A crusher’scapacity is, after all, volumetrically limited. The removal of fines via scalping – specifically, those sized below the crusher’s closed side setting (CSS) – improves crushing efficiency and increases throughput.
The Trio THDS features a stepped deck design with adjustable grizzly bars. This allows the material to tumble across the deck; the fines material are given an opportunity to be presented to the grizzly bar apertures and, therefore, the likelihood of it passing through the apertures. The grizzly bars can be aligned or offset, depending on the specific operating requirements. They can be adjusted on-site; Weir Minerals has an experienced team of engineers who can partner with operators to evaluate screening performance and provide assistance to ensure optimal results are achieved.
Trio TIOSP series
Trio TIOSP scalping screens are usually utilised following the primary crusher; the screened oversized material is then fed into the secondary crusher. Because of this configuration, it doesn’t have to deal with lump sizes as large as the THDS series; however, it is still a heavy-duty screen, capable of accepting feed sizes up to 400mm. It’s available in a single, double or triple deck configuration. The TIOSP series’ primary role is still to deal with and separate material that is oversized and would potentially damage equipment downstream. The Trio TIOSP can also be used in scalping duties, where it’s responsible for making the scalps product, which can be utilised in road base.
The TIOSP series typically operates at an inclination from 15 to 20 degrees and can be supplied with a steel punch plate, steel-backed rubber media and cascading grizzly bars. It has a flat or cambered deck that’s cross-tensioned, which ensures it performs well in heavy duty applications. The side tension clamp rails prevent the wire mesh from sagging and breaking when handling large lump sizes.
The Trio TIOSP can also be fitted with rubber or polyurethane modular parts, which reduces noise pollution, offers exceptional wear life and reduces the chance of blockages. The stroke can also be adjusted using counterweights that are bolted to the flywheels and, depending on the size of the machine, the TIOSP can be supplied in either a single or dual drive.
Unrivalled support
With a global footprint covering over 70 countries, Weir Minerals operates more than 120 facilities providing expert manufacturing and service support. This is how we have successfully manufactured over and delivered 1000s of screens across the globe. Whether greenfield or brownfield operations, there is a Weir Minerals screening solution for you. Get in touch with a Weir Minerals screening expert today.
