Abstract: Various embodiments disclosed relate to an abrasive sheet. The abrasive sheet includes a first layer including an abrasive major surface and an opposite second layer defining a second major surface. The second major surface includes a plurality of protrusions extending outwardly from the second major surface. The protrusions include a first polymer component having at least one of a Shore A hardness ranging from about 5 to about 100 and a Shore D hardness ranging from about 1 to about 70. The first layer and the second layer are directly joined to each other.

Abstract: Coal is extracted using a mixed solvent which includes a substantially aromatic component and a substantially naphthenic component, at a temperature of 400.degree. to 500.degree. C. Although neither component is an especially good solvent for coal by itself, the use of mixed solvent gives greater flexibility to the process and offers efficiency gains.

Abstract: Coal extracts from hydrogenative liquid extraction of coals can be more easily and more quickly filtered if the extraction is carried out at a temperature over 420.degree. C. and the resulting extract is fractionated using a cut point in the range 200.degree. to 300.degree. C. to remove low boiling material. The product is then filtered to give a filtrate containing less than 0.1% by weight of mineral matter.

Abstract: In the extraction of coal using a liquid solvent oil, filtration can be assisted by using a filter aid which is of coal origin. The filter aid is produced by high temperature processing of coal or an ash-rich coal-derived residue under conditions at which the ash component of the coal or residue does not fuse. A preferred starting material is filter cake from a coal extraction process.