Abstract: A grinding tool for grinding buttons of a rock drill bit includes a spindle having a longitudinal axis of rotation, and a grinding cup mounted on the spindle by a tongue-and-socket connection. A fastener in the form of a coil spring secures the grinding cup to the spindle. The grinding cup can be inserted into the inside of, or around the exterior of, the coil spring. When the spindle is rotated in a working direction, the spring tightens against the grinding cup. To install or remove the grinding cup, the grinding cup is rotated relative to the spindle in a direction corresponding to the working direction, whereby engagement between the grinding cup and the coil spring becomes loosened.

Abstract: A separation material of crosslinked agarose in which the agarose is crosslinked using at least one bi- or polyfunctional crosslinking agent, which gives a chain of 6 to 12 atoms between two binding points, on one hand and using at least one bifunctional crosslinking agent, which gives a chain of 2 to 5 atoms between two binding points on the other.The separation material is prepared by crosslinking agarose in two steps with (a) a bi- or polyfunctional crosslinking agent, which gives a chain of 6 to 12 atoms between two binding points and (b) a bifunctional crosslinking agent, which gives a chain of 2 to 5 atoms between two binding points, preferably in the order mentioned.