Screening Efficiency
Sir,
If you do not have a more specific question we will have to delete your post.
I am sure you will understand.
Dr. Reinhard H. Wohlbier ■
Re: Calculation Of Screening Efficiency And The Parameters Invo…
Dear Shri Deepak,
Firstly, it is necessary to be clear about screening efficiency. Suppose 50 tonne of feed material has say 40 tonne of (-) 10 mm size material. If you are screening for passing size of (-)10 mm, then if the screened content happens to be say 28 tonnes then the screening efficiency would be 28/40 = 70%. So, this is the understanding about the screening efficiency.
As I know, there are no simple calculations about the screening efficiency. In general, the screening surface area say square feet / mtph (or square meter / mtph) is chosen considering the material, material feed size analysis, screen-out size, type of screen, etc. based on the data with the manufacturer or from the applicable literature. It is understood that such area per mtph would be in context of some percentage of screening efficiency. What % has been considered, can only be said by the creator of the data / chart. But it seems the figure could be in the range of 75% to 90%. This will greatly depend upon the size distribution in the feed material. If the % of passing size is more, then efficiency would be also more. Contrary, if the material you intend to screen out is itself very small in quantity, then sizable portion will be missed and one will get a very poor efficiency. The subject is complex and thereby the experience and data bank is very important for screening efficiency.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Author of Book : Belt Feeder Design and Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 25882916 ■
Efficiency
Efficiency as per VSMA calculation formula: CHECK OUT VSMA PAGE 3 explains this theory in full detail.
The plug in factor for screen efficiency in the VSMA formula is 95% screen efficiency on the the top deck.
90% on second deck
85% on third deck
OF THE SAME VIBRATING SCREEN BODY. Efficiency gets less as the transfer to decks below has the material passing landing further down each LOWER DECK POSITION.
the DIFFERENT TYPES OF material whether sand, gravel, iron ore, or woodchips......MATTERS not......except the material effects the TPH per sq ft that will pass a given opening. ■
Calculation of screening efficiency and the parameters involved in screening
calculation of screening efficiency for iron ore screening or paremeters involved in screening ■