Dewatering Screens are one of the go-to pieces of equipment for removing excess moisture from a final product. They produce a drip-free material that is conveyable, stackable and ready for immediate sale. Additionally, these units are capable of dewatering up to three products on the same screen.
When a Dewatering Screen is configured to process more than one product, the screen is divided lengthwise by a divider extension, or extensions in the case of three products. These divider extensions separate the products being dewatered on the screen so that the coarse material is on one side and the fine material is on the other side. In the case of three products being dewatered, an in-between size of material would take up the middle portion.
Dewatering Screens that are used to dewater more than one product also include multiple discharge chutes and a blending gate. The blending gate allows fine material to be combined with the coarse material upon discharge to maximize the specification product.
Say you are dewatering a concrete sand on one side of the screen and a mason sand on the other side of the screen. If your concrete sand is your primary moneymaker, you can blend some of the finer mason sand in with the coarser concrete sand to maximize the amount of salable product while still remaining in spec.
Dewatering multiple products on one screen
The main reasons to dewater more than one product on the same screen are equipment footprint and cost.
When a single Dewatering Screen is used to dewater multiple products, it is doing the job of multiple screens and thus eliminates the need for those other screens. One screen takes up less space than two or more, so the footprint of the dewatering system is smaller.
Purchasing one Dewatering Screen instead of several also offers a cost savings, as dewatering multiple products on the same screen lowers capital equipment costs as well as eliminates the structural costs necessary for supporting the additional screen(s).
There are also the indirect cost savings of operation and maintenance of one screen versus multiple screens.
Dewatering multiple products on a single screen is often more suited to smaller operations than to larger ones because the cost-savings benefits can be realized more completely and make more of an impact.
However, there are some limitations with dewatering multiple products on the same Dewatering Screen. The first is throughput.
If a Dewatering Screen is rated for 400 tons per hour and your operation can make 400 tons per hour of a coarse concrete sand and 200 tons per hour of a fine mason sand, then having two Dewatering Screens will allow you to maximize throughput of those products. If you wanted to dewater both products on the same screen and the screen is still rated at 400 tons per hour, total throughput will be affected. The coarse side will have to be derated to accommodate the fine side, so your tons per hour of the coarse sand will be reduced.
Throughput is one of the reasons dewatering multiple products on one screen is more economically beneficial for smaller applications.
The second limitation of dewatering multiple products on the same screen is the risk of screen imbalance. An imbalanced screen can cause undue wear and tear on the screen and increase the potential of component breakage.
The divider extensions help to balance out the screen, but getting the proper balance can sometimes be difficult.
The third limitation of dewatering multiple products on the same screen is the risk of cross contamination. With two products being dewatered on the same screen, there is the risk that some of the fines will end up on the coarse side and vice versa. However, this isn’t always a limitation, especially if the producer was planning to mix the material via the discharge blending gate anyway.
When considering dewatering multiple products on a single machine, also consider this: just because you eliminate a Dewatering Screen doesn’t mean you eliminate the number of Hydrocyclones or Pumps required for the system. If you’re making two products on the same screen, you will still need at least two Hydrocyclones (for the coarse side and for the fines side) and two Pumps to feed those Hydrocyclones. The cost savings benefit will come only from eliminating the second Dewatering Screen.
You also want to consider sizing the Dewatering Screen slightly larger to achieve the expected level of throughput. Larger screens are more expensive than smaller screens.
While there are cost-savings benefits to dewatering multiple products on one Dewatering Screen, it may not be the right configuration for every application. You’ll want to keep in mind how these cost-savings weigh against decreased throughput and increased component wear.