Abstract: A method of removing silicon dioxide from a waste liquid is described. A solution containing fluoride ions is added into the waste liquid to form a reaction product. A method of cleaning a membrane tube for processing waste water is also described, wherein the membrane tube contains residues of waste water that include a first residue and a second residue containing silicon dioxide. A first cleaning step is conducted to reduce the concentration of the first residue in the membrane tube to a first concentration. A solution containing fluoride ions is added into the tube to react with the second residue to form a reaction product. A second cleaning step is then conducted to reduce the concentration of the residual fluorine ions in the membrane tube to a second concentration.

Abstract: A computer controlled grinding machine grinds a cylindrical region and an annular shoulder of a rotatable workpiece. Relative movement is effected between the workpiece and a grinding wheel along a line of action which subtends an angle of approach of less than 90 degrees to the Z axis of rotation of the workpiece. Such an angle of approach enables the wheel to grind the annular shoulder of the workpiece simultaneously with grinding the cylindrical portion.

Abstract: An abrasive article including (i) a first backing, (ii) a plurality of protrusions attached to the first surface of the first backing and including a grinding aid, wherein the first surface of the first backing is contoured by the protrusions so as to define a plurality of peaks and valleys, and (iii) a coating of abrasive particles adhered to the contoured first surface of the first backing so as to cover at least a portion of both the peaks and the valleys.

Abstract: An abrasive article including (i) a backing, (ii) a plurality of grinding aid-containing protrusions integrally molded on the first surface of the backing, wherein the first surface of the backing is contoured by the protrusions so as to define a plurality of peaks and valleys, and (iii) a coating of abrasive particles adhered to the contoured first surface of the first backing so as to cover at least a portion of both the peaks and the valleys.

Abstract: An abrasive article including (i) a first backing, (ii) a plurality of protrusions attached to the first surface of the first backing and including a grinding aid, wherein the first surface of the first backing is contoured by the protrusions so as to define a plurality of peaks and valleys, and (iii) a coating of abrasive particles adhered to the contoured first surface of the first backing so as to cover at least a portion of both the peaks and the valleys.