Asbestos cement waste treatment through mechanochemical process with KH₂PO₄ for its utilization in soil pH correction...

The manufacture of asbestos materials has been banished worldwide due to their toxicity, but discarding the existing wastes remains a challenge. We investigated an alternative mechanochemical method to treat asbestos-cement materials by loading them with potassium and phosphorus from KH₂PO₄ during the milling process to obtain a product used as liming and soil conditioner. The results showed total asbestos fibrous elimination after 7 to 8 h of milling. The materials showed a slow-release fertilizer profile. The liming property is maintained when the asbestos-cement weight proportion used is equal to or higher than KH₂PO₄. A comparative soil experiment with limestone also indicates that lower doses of the K- and P-enriched detoxified asbestos cement were required to reach similar liming effects. Maize cultivation (greenhouse) was used to evaluate its performance showing higher biomass production for the sample loaded with potassium and phosphorous.