Scalping Screen

(not verified)
Posted in: , on 20. Jul. 2004 - 12:15

I am deciding whether a scalping screen with grizzly bars to take the 300mm lump would be more appropriate or a screen w/ rubber meshing with an impact plate.

A brief description of the plant flowsheet is as follows:

The Primary Sizer discharges -300mm material which is transfered to a surge bin via conveyor.

The bin is connected to a vibrating feeder which in turn loads the scalping screen

Overflow from the scalping screen goes into a Secondary Cone crusher (75mm setting) (Approx 910 TPH)

Underflow goes into a product conveyor (-75mm) (Approx 940 TPH)

Scalping screen unit selection information

Fall Height (m)1.0 - 1.3m

Feed Rate (mTPH)2000

Bulk density (kg / m3)2000 - 2200

Clay contentminimal

Moisture content8 - 10%

Primary sizer discharge setting-300mm

Estimated feed gradation45% > 75mm 65% <75mm

Secondary crusher C.S.S (scalped material is fed to this crusher)75mm

What type of scalping screen is most appropriate and why?

Re: Scalping Screen

Erstellt am 21. Jul. 2004 - 08:15

Dear Sir,

Of course you can put on your scalping screen the prebuild screen panels with "superelastic" impact-wear resistant polyurethane conical bars.

The steel frame and p.u bars can be build as per your screen machine dimension.

For any additional information not hesitateto contact me



Re: Scalping Screen

Erstellt am 23. Jul. 2004 - 07:46

Hello mcmc2626,

The material bulk density mentioned by you is 2 tonne/m3. So, lump density could be more than 3 tonne/m3. Such high lump density in combination with the lump size mentioned by you will require heavy class and robust screen.

Single deck screen may suit the application. The other solution could be to have two-deck screen. Upper deck with aperture opening somewhere around 150 mm and this can be constructed to take sever impact from 300 mm size lump. The lower deck will have less size of lump so it can be constructed to suit 75 mm passing size with sufficient net screening area. The upper deck aperture size depends upon balanced screening condition for both the decks.

I suggest you to refer to the manufacturer of heavy class screen. Their tried and tested recommendation can only be the reliable solution.


Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Advisor / Consultant for Bulk Material Handling System & Issues.

Email :

Tel.: 0091 (0)20 25882916

Screening Help

Erstellt am 25. Jul. 2004 - 06:04


I would like to offer my opinion for your querry regarding screening.

As A mechanic with many years of experience involving screening and screening plant operation I have found that the simpler you keep everything the better.

If I were to do what you are examining first I would purchase the largest wobble feeder that would fit in your desired screening location then I would purchase a pair of smaller wobble feeders to use under the wobble feeder to feed the tertiary crusher.

By using the wobble feeder you will reduce maintenance and screening headaches and have fewer screen problems as you could purchase a very heavy screen or another wobble feeder to feed the crusher further reducing maintenance.

The beauty of these units is they are simple to maintain and repair-not like the problematic elliptical screens.

Please understand that I am not saying that elliptical screens are bad to use but that they require a lot of maintenanace and production is what pays the bills and as a result maintenanace is sidelined until it is more convenient. IE- a maintenance shut down or a total unit failure.

my two cents

Scalping Screen

Erstellt am 26. Jul. 2004 - 10:07


Of course the application of polyurethane conical bars is on heavy duty stell screen frame

This technical solution are working very well in a ferro-crome scraps (density 8-8,5 ton/mc) crushing plant.

Only must to applicate correct polyurethane bars thickness for to prevent damages due to the impact and wear problems.

On the mentioned plant the ferro -crome fall from 1, 30 mt. and the polyurethane thick. is 60 mm.

The replacement of the polyurethane bars is very easy and fast.

The use of traditional screen is low expensive and the mechanical parameters should be changed according to the process conditions.

In general for scalping process must to choice low speed and low vibration (with "super elastic polyurethane)