Abstract: The invention relates to a device for dissolving compressed blocks of loose-fill cellulose thermal insulation material. The device includes a support surface for the compressed blocks of insulation and a cylinder with protruding members arranged on the cylinder mantel surface. Said cylinder is rotatable around a substantially horizontal axis to process and dissolve the compressed blocks of insulation between the protruding members and a processing zone arranged by an edge of said support surface. The invention discloses that said protruding members arranged on the cylinder mantel surface are elongated protrusions extending substantially parallel to the horizontal axis. The invention further discloses that the cylinder is arranged to rotate inside of an arc-shaped surface partly covering the cylinder mantel surface and prolonging the milling zone in a peripheral direction of the cylinder. Further, the invention relates to a loose fill insulation apparatus.