Process for cleaning short mineral fibers

A process for cleaning short mineral fibers, in which the fibers contaminated with foreign bodies are separated from the foreign bodies which have at least a starting size, comprising:

• (a) adding a contaminated fiber material to a carrier medium and setting the carrier medium in a flowing motion;
• (b) circulating the carrier medium through a separation apparatus having an upstream side and a downstream side with at least one slot-like recess between the upstream and the downstream in the direction of a longitudinal extension of the recess;
• and
• wherein the fibers to be cleaned have an E-modulus of at least 100 GPa,
• whereby at least a part stream of the carrier medium passes form the upstream side through the recess together with the fibers, forming a fiber filtrate at the downstream side of which the degree of purity is solely determined by the width of the recess.

A process for cleaning short mineral fibers and for testing the shot content of short fibers, in which the fibers are contaminated with shot and are separated from the shot which have a starting size of greater than 100 .mu.m, comprising:

• (a) adding a contaminated fiber material to a aqueous carrier medium and setting the carrier medium in a flowing motion;
• (b) circulating the carrier medium through a separation apparatus having an upstream side and a downstream side with at least one slot-like recess between the upstream and the downstream in the direction of a longitudinal extension of the recess;
• (c) whereby at least a part stream of the carrier medium passes from the upstream side through the recess together with the fibers, forming a fiber filtrate at the downstream side of which the degree of purity is solely determined by the width of the recess;
• and
• (d) the aqueous carrier medium on the upstream side containing the shot, the shot being isolated as a shot filtrate by filtering off shot, and determining the shot concentration either microscopically or gravimetrically, based on this shot filtrate.