TY - JOUR
T1 - Insights on the additive formulation for the energy-efficient production of fused calcium magnesium phosphate fertilizer from waste sludge
AU - Qin, Pengfei
AU - Gu, Xiangyu
AU - Xuan, Guohui
AU - Song, Wenli
AU - Wu, Hao
AU - Li, Songgeng
PY - 2023
Y1 - 2023
N2 - The production of the fused calcium magnesium phosphate fertilizer (FCMP) from sludge
is a sustainable alternative to phosphate ore route. However, the
distinct compositions of sludge and extensive energy input make the
process under great uncertainty for the commercialization. In this study, a new method was proposed to determine the optimal addition amount of CaO and MgO
to sludge, realizing the high phosphorus (P) availability and
simultaneously reducing the melting point of the system for energy
saving. The effect of P content on the product structure and P
availability was first investigated at different metal oxide
addition levels. The modified non-bridging oxygen to tetrahedral cation
equation (NBO/T) was used to establish the linear relationship between
the NBO/T and the P availability. The threshold value of the modified
NBO/T ≥ 2.3 guaranteed a P-availability beyond 90%. Further, FTIR and Raman spectra
showed that there was a strong correlation between the modified NBO/T
and the actual glass structure. Finally, on the reference value of
NBO/T = 2.30, the system exhibited the minimum melting point at 1292 °C
when MgO/CaO = 0.83. This method offers a powerful tool to guide the
optimal amount of CaO and MgO addition to sludge ash by simple
calculations.
AB - The production of the fused calcium magnesium phosphate fertilizer (FCMP) from sludge
is a sustainable alternative to phosphate ore route. However, the
distinct compositions of sludge and extensive energy input make the
process under great uncertainty for the commercialization. In this study, a new method was proposed to determine the optimal addition amount of CaO and MgO
to sludge, realizing the high phosphorus (P) availability and
simultaneously reducing the melting point of the system for energy
saving. The effect of P content on the product structure and P
availability was first investigated at different metal oxide
addition levels. The modified non-bridging oxygen to tetrahedral cation
equation (NBO/T) was used to establish the linear relationship between
the NBO/T and the P availability. The threshold value of the modified
NBO/T ≥ 2.3 guaranteed a P-availability beyond 90%. Further, FTIR and Raman spectra
showed that there was a strong correlation between the modified NBO/T
and the actual glass structure. Finally, on the reference value of
NBO/T = 2.30, the system exhibited the minimum melting point at 1292 °C
when MgO/CaO = 0.83. This method offers a powerful tool to guide the
optimal amount of CaO and MgO addition to sludge ash by simple
calculations.
KW - Glass structure
KW - Melting point reduction
KW - NBO/T
KW - Phosphate fertilizer
KW - Sewage sludge ash
U2 - 10.1016/j.jclepro.2023.138804
DO - 10.1016/j.jclepro.2023.138804
M3 - Journal article
SN - 0959-6526
VL - 423
JO - Journal of Cleaner Production
JF - Journal of Cleaner Production
M1 - 138804
ER -
