TITLE:
Study on the Recycling of P in Phosphogypsum Leachate
AUTHORS:
Shushu Zhao, Huali Zhang, Qin Liu, Yiyang He, Han Xiao, Li Ma
KEYWORDS:
Phosphorus Recovery, Industrial Wastewater, Precipitation, Phosphogypsum Leachate
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.5,
May
30,
2023
ABSTRACT: After washing and curing, P is transported from the phosphogypsum to the leachate
during the phosphogypsum detoxification process, providing two ideas for phosphorus
recovery from phosphogypsum leachate: 1) preparation of calcium hydrogen phosphate
for feed; 2) preparation of calcium phosphate. A ready-to-use calcium oxide slurry
was used to recover P from phosphogypsum leachate at a slurry concentration of 20%
and a quantitative link between calcium to phosphorus ratio and fixation rate was
fitted by mixed use batch experiments, reaction kinetics and thermodynamics, and theoretical calculations
were used to demonstrate that phosphorus cannot be completely reused in the preparation of calcium hydrogen phosphate.
The findings demonstrated that: a) the residual phosphorus concentration was in the range
of 1300 - 1500 mg/L for the preparation of type I feed grade calcium hydrogen phosphate
from phosphogypsum leachate; b) the P
removal effect could reach 99.99% for the preparation
of calcium phosphate from phosphogypsum using the theoretical equation: fixation
rate = 87.91- 10.96(Ca/P) + 3.22(Ca/P)2 (R2 =
0.9954); c) The procedure
follows the suggested secondary kinetics, and according to the Freundlich isothermal
model, the reaction process is under the control
of the chemical reaction, with a reaction index of 0.7605. This study can be used as a theoretical guide for the recovery
of P from phosphogypsum leachate, the preparation of products to bring about economic
by-products, and the purification of wastewater for reuse.