Paper pulp mill with steel grinding discs - having grooves of three sizes aligned in direction of flow

摘要

The groove system on the grinding discs of a mill for producing special type of paper and pulp, includes grooves of three types. These are straight, aligned in the direction of the flow of material and open into each other. The first, widest and deepest grooves, subtend with the vertical line through the centre of the disc, an angle of alpha against the direction of rotation of the disc in the region of 10 to 20 degrees. The second, narrower and flatter grooves similarly subtend an angle beta- alpha. The third, narrowest and flattest grooves, are aligned against the direction of rotation of the disc and subtend with the second grooves an angle in the region of 80 to 100 degrees. At least two of the second type of groove are allocated to each of the first broadest and deepest grooves, whilst to each cm of length of the second type of groove, 1,25 to 2 of the third type of groove are allocated. The first type of groove on the fixed disc is closed at the inlet and open at the end, whilst those on the rotating disc are open at the inlet and closed at the end. The grooves of the second type areopen at the outer circumference of the fixed disc and are closed at the outer circumference of the rotating dsc. The grooves of the third type are closed at their ends. Prcess provides a paper mill with steel grinding organs with which the throughput and the quality of the prod. are at least equal to those of mills using basalt grinding elements.