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Table S1 Elemental composition of a composite of mine waste rocks used for laboratory tests

Element Unit Concentration Al % 1.26 Ba mg kg-1 307 Ca % 2.13 Cr mg kg-1 58 Cu mg kg-1 17.4 Fe % 3.16 K % 0.43 Li mg kg-1 4 Mg % 0.81 Mn mg kg-1 499 Na % 0.03 P mg kg-1 1720 S % 1.4 Sr mg kg-1 185 Zn mg kg-1 74 As mg kg-1 42 Cd mg kg-1 0.09 Cs mg kg-1 4.12 Hg mg kg-1 0.09 Mo mg kg-1 1.02 Pb mg kg-1 12 Se mg kg-1 <1 U mg kg-1 1.88

1 Table S2 Compositions of groundwater and mine seepage water used for the initial and boundary conditions in model simulations

Unit Groundwater Seepage water

pH - 7 3.64

-1 Alkalinity (as CaCO3) mg L 148.9 0

2- -1 SO4 mg L 195 4732

Cl- mg L-1 14.1 15

F- mg L-1 0.987 13.9

Al mg L-1 0.0238 125

As mg L-1 0.0179 0.14

Ca mg L-1 74.8 45

Cd mg L-1 0.000056 0.49

Cr mg L-1 0.00058 0.10

Cu mg L-1 0.0016 8.2

Fe mg L-1 0.357 658

K mg L-1 8.2 26

Mg mg L-1 24.5 9.1

Mn mg L-1 0.792 0.90

Na mg L-1 29.6 1262

Pb mg L-1 0.000728 0.19

Se mg L-1 <0.001 0.0081

Zn mg L-1 0.0152 52

2 Fig. S1 Composite rock samples, separated with coarser materials (-3/4 +1/2"), (b) reaction bottles packed with rock samples, (c) perforated sampling tubes, wrapped with paper filters (placed in the center of the reaction bottles, capped with blue caps in (b)), and (d) saturation of the reaction bottle with the seepage water, using a peristaltic pump

Fig. S2 Changes in (a) pH, (b) alkalinity, and dissolved concentrations of (c) Ca, (d) Mg, (e) Fe, and (f)

2- SO4 in a repeated laboratory test for bottle 3

Fig. S3 Changes in dissolved concentrations of (a) Al, (b) Zn, (c) Cd, (d) Cu, (e) Cr, and (f) Mn in a repeated laboratory test for bottle 3

Fig. S4 Simulated volume fractions of the key primary minerals (calcite, ankerite, and pyrite) in (a) 7,

(b) 20, (c) 30, and (d) 50 years

Fig. S5 Simulated volume fractions of gibbsite, gypsum, ferrihydrite, and siderite in (a) 7, (b) 20, (c) 30, and (d) 50 years

Fig. S6 Simulated volume fractions of covellite, smithsonite, and rhodochrosite in (a) 7, (b) 20, (c) 30, and (d) 50 years

Fig. S7 Simulated volume fractions of otavite and Cr(OH)3(am) in (a) 7, (b) 20, (c) 30, and (d) 50 years

9 Fig. S8 Simulated concentration of F- at 500 m distance from the infiltration point over time. The symbol at 0 year represents the seepage concentration