In a cold rolling mill, the rolls used to process steel strip are turned and reground regularly to maintain strip surface quality. Because the rolls are not cleaned before machining, the coolant emulsion washes off large quantities of oil and grease. This contamination floats in a pre-separation basin with a surface area of approximately 1 m².
To stabilise emulsion quality and extend service life, the viscous oil-and-grease layer had to be removed from the bath surface. Earlier trials with suction systems and several other skimmers had not produced the required result.
A FRIESS 1U oil skimmer was initially installed temporarily above the basin to treat the large floating surface. Its 3 m collection tube reaches the entire basin surface, and the high-viscosity oil forms a thick layer on the oleophilic tube.
Depending on the oil-layer thickness, the skimmer removes more than 30 litres per hour. The rotating movement of the collection tube draws oil from the whole surface. Earlier systems treated only local areas and soon recovered a mixture with a high emulsion content and little tramp oil.
