Green preparation, microstructure and human health risk assessment of phosphorus tailings-based unfired artificial lightweight aggregates

Abstract

Aiming at the safety hazards brought about by the accumulation of industrial solid waste (SW) in Lianyungang City, Jiangsu Province, as well as the resource shortage and high energy consumption problems faced by the manufacture of traditional building materials. This work is based on the concept of "full solid waste utilization" and uses industrial SW materials such as phosphorus tailings (PT) and alkali slag (SR) to prepare non-fired artificial lightweight aggregates. The study systematically explored the impact of various kinds of mixed water and curing conditions on the physical characteristics, microstructure, and durability of phosphorus tailings-based lightweight aggregates (PT-LWA). Additionally, the potential human health risk assessment and potential ecological risk index models were employed to assess the environmental risks and human health impacts associated with heavy metals (HMs) in PT-LWA. In addition, the carbon emissions and economic costs of PT-LWA were analyzed. The findings indicated that the PT-LWA prepared with mixed water NS 12 exhibited the best performance when the steam curing temperature was 90 °C. Its water absorption, cylinder crush strength, softening coefficient, and apparent density were found to be 13.67 %, 10.5 MPa, 0.945, and 1054.11 kg/m³, respectively. All these parameters met the requirements laid out in the Chinese standard GB/T 17431.1-2010. According to the results obtained from the human health risk assessment, hand-to-mouth intake was revealed to be the primary exposure route for the non-carcinogenic risks of various HMs in PT-LWA. The carcinogenic risks for both adults and children were low and within the tolerable range for humans.