Pyrolysis Process for the Recycling of Cork Dust Waste from the Processing of Cork Agglomerate Caps in Lightweight Materials

This study aimed to investigate the possibility of recycling cork scraps derived from the production of agglomerated bottle caps containing organic additives (glues and adhesives) in addition to virgin wood. The study involved pyrolysis treatment followed by the use of char to obtain lightweight material prototypes. The scrap was pyrolysed in order to achieve the thermal degradation of unwanted molecules with decomposition temperatures lower than the pyrolysis temperatures, but also to achieve the reduction in mass and size of the starting material. The substitution of 15% by weight of weight-lightening agent (char from pyrolysed cork, or half char and half spent coffee grounds) into the clayey matrix made it possible to obtain lightweight aggregates with pH and conductivity values that could be exploited in an agronomic context. The substitution of clay with of 5 to 15% by weight of pyrolysed cork char in the production of specimens pressed at 25 bar and fired slowly at 1000 °C led to lightweight ceramics with particularly interesting porosity (from 41 to 68%) and bulk density (850–1600 kg/m3) values.