PIT WALL LEACHING TEST AND PREDICTION WATER QUALITY OF PIT LAKE IN MINE CLOSURE IN COAL MINE
The main activity of coal mining with an open pit system is extracting coal from the overburden. Overburden can contain sulfide minerals so that when exposed to air and water it will produce acid mine drainage. The biggest impact due to coal mining activities with an open pit system is the format...
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| Format: | Theses |
| Language: | Indonesia |
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| Online Access: | https://digilib.itb.ac.id/gdl/view/51581 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | The main activity of coal mining with an open pit system is extracting coal from the
overburden. Overburden can contain sulfide minerals so that when exposed to air
and water it will produce acid mine drainage. The biggest impact due to coal
mining activities with an open pit system is the formation of a pit lake. The quantity
and quality of pit lakes can be predicted and known so that prevention or control
can be made. Geochemical characterization of rocks is an initial step in
understanding the process of forming acid mine drainage which consists of static
test and can be validated by kinetic tests. The kinetics testing method used is pit
wall leaching.
The results of the static test sample PRI-01 were categorized as NAF, samples PRI-
02 and PRI-03 were categorized as PAF. The results of the pit wall leaching test,
the pH value of the PRI-01 sample was 7.59, the pH value of the PRI-02 sample
was 2.15, and the pH value of the PRI-03 sample was 3.51. The pyrite oxidation
rate based on moles of iron is much smaller than the pyrite oxidation rate based on
moles of sulfate and the geochemical modeling of PHREEQC. The PRI-01 samples
had iron species Fe(OH)3 which tended to settle in the leach water, while the PRI-
02 and PRI-03 samples had iron Fe2+ species which tended to be dissolved in the
leach water. The results of the pit lake prediction scheme, the former coal mining
pit will be fully filled with water in year 5.5 with a total water volume of 45,238,444
m3 at an elevation of 14 masl and in the first year the water quality of the pit lake
has a pH value of 2.81 which is not much different from the pH value of the sump
of 2.86 and in the final year of filling the pit lake or in the year 5.5 the water quality
of the pit lake has a pH value of 4.6. |
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