Environmental Risk Assessment System for Phosphogypsum Tailing Dams

Table 4

List for investigation of the tailings of the XX phosphorus chemical industry in Yunnan.

General information
Total storage capacity	9.8 million m^3
Starting date	2003.06
Service period	14.86 years
Type of tailings	Valley Type
Dam height	45 m
Storage capacity	8639737 t
Damming mode	Upstream tailings dam
Comprehensive utilization	6.84 × 10^5 t
Disposed quantity	1.15 × 10^7 t
Physical-chemical analysis of phosphogypsum
Element	Content (%)
Water content	24.20
CaO	27.8
Fe2O3	0.10
Al2O3	0.53
MgO	0.05
K2O	0.13
Na2O	0.13
SO4^−	33.9
F	0.49
SiO2	11.85
P	0.7
Extraction toxicity
Index	Unit (mg/L)
pH	5.73
Cu	<0.02
Pb	<0.1
Zn	0.126
Cr	<0.05
Cd	<0.005
Be	<0.005
Ba	4
Ni	<0.04
As	0.0088
Se	0.0004
Ag	<0.01
Hg	0.0015
Cr^6+	<0.004
Cyanide	<0.001
Fluoride	6.49
Methyl mercury	<10 ng/L
Ethyl mercury	<20 ng/L