Recycling thermally detoxified asbestos-cement in stone-wool: An end-less-life material!

Deactivated (detoxified) asbestos-cement (DAC), i.e. asbestos-cement slates thermally treated at 1100 °C in order to convert the harmful asbestos fibers into non harmful mineral phases, has been successfully mixed with 74.6 wt% quartz sand and up to 63.2 wt% basalt sand, to produce stone wool with mechanical properties and composition competitive with commercial stone wool. The sample with 50 % DAC and 50 % basalt provided the best comparison with commercial stone wool in terms of liquidus temperature (lower than for the other mixtures) and Young's modulus (higher). Through further composition optimization and utilization of multiple components, we estimate that future batches could utilize 70–75 % of DAC. These promising results and expectations highlight a feasible reuse of DAC as secondary raw material for stone wool production and a possible route to the elimination of a toxic waste from the environment and the preservation of primary raw materials.