Mogensen has received an order for a further Type S2056 Sizer from the El Nasr phosphate rock processing plant in Egypt. The new machine, scheduled to be delivered in early August, is to be used to supplement the two machines currently in operation and increase capacity (Fig.).
Mogensen’s connection with the El Nasr plant goes back 28 years. Two S2056 Sizers lined with wear-resistant vulcanised rubber were delivered in 1984; they operated successfully under very arduous conditions meeting all specified requirements for 17 years. In 2001 they were replaced by two identical machines, which have continued the previous satisfactory performance. The feed to the Sizers is an abrasive phosphate rock slurry delivered from a rotary crusher via a trommel fitted with 30 mm aperture screen panels. Each Sizer takes 150 t/h of < 30 mm rock in 150 t/h water and makes a separation at 1.5 mm, 60 % of the feed being less than the separation size. Oversize material is recycled via a cone crusher to the machines thus increasing the feed rate by an estimated 50 %. Each Sizer is driven by two counter-rotating Invicta BL50‑75/6 rotary electric vibrators delivering a linear vibration.
Mogensen reports that this continuing business at El Nasr results from the advantages offered by the Sizers’ screening technique, which is based on using a bank of relatively steeply declined decks with apertures greater than the aimed-for separation size; typically, the bottom deck aperture is twice the separation size. The large open area available for material flow allows the Mogensen machine to process a much larger volume of feed than would be possible using a conventional screen occupying the same floor area. The resulting benefits are that the machine is much lighter than would be the case with a conventional screen of the same capacity, the support steelwork needs to be less massive and power consumption in relation to the feed rate is comparatively low. Maintenance is quicker and cheaper as the Mogensen screen decks are relatively small and easy to handle.