CHEMISTRY NIGHTMARE!!!!!!

CHEMICAL MAKE-UP

Pyrite Oxidation: 4 FeS₂ + 15 O₂ +14 H₂O 􀂼 4 Fe(OH)₃ (s) 􀂾 + 8 H₂SO₄ (1) 

Pyrite + Oxygen + Water 􀂼 Ferric Hydroxide + Sulfuric Acid 

Ferrous Oxidation: 4 Fe²⁺ + O₂ + 4 H⁺ 􀂼 4 Fe³⁺ + 2 H₂O (2) 

Ferrous Iron + Oxygen + Protons 􀂼 Ferric Iron + Water 

Iron Hydrolysis: 4 Fe³⁺ + 12 H₂O 􀂼 4 Fe(OH)₃(s) 􀂾 + 12 H⁺ (3) 

Ferric Iron +Water 􀂼 Ferric Hydroxide + Protons 

Additionally,

Pyrite Oxidation: FeS₂ + 14 Fe³⁺ + 8 H₂O 􀂼 15 Fe²⁺ + 2 SO₄^2- + 16 H⁺ (4) 

Pyrite + Ferric Iron + Water 􀂼 Ferrous Iron + Sulfate + Protons 

Acid Mine Drainage has proven to have significant environmental challenges as its roots stem from the process of mining certain natural resources. The mining process exposes iron sulfide and unremoved coal contained in sandstone. Therefore results in natural oxidation of the sulphide minerals being exposed to the atmosphere and water forming soluble hyrdous iron sulphates. The water acts as a medium for the transfer of oxidation to occur. As well as this there are forms of bacteria that contribute. The end results are yellow and white crystals that hold a low PH therefore highly acidic concentrations of metals and sulphates content around Ph 2.3 to 6.5. (Microbiology of fly acid mine drainage co-disposal process. Eloise M.R.Kuhn. November 2005).

(PERSPECTIVE)

Acid Mine drainage affects the surface and underground water systems while also impacting on land usage through agriculture.  The acidity and metal toxity has an obvious wide spread side effect impacting aquatic life and riverbeds far beyond the original source. As mentioned before the soluble deposits result in an orange reddish colour. This sedimentation occurs due to the precipitation of iron oxides and hydroxides. It is often called Ochre found at the bottom covering the riverbeds with fine silt therefore aquatic organisms can no longer feed. This is disruptive to the life cycle of animals and plants as in the environmental world everything is closely linked and therefore impacting on one another. Once in the river systems the acidic solubles (acid mine drainage) can be transported in the underground water systems or rivers nation wide. This rises the possibility of contaminating drinking water and reaching the river mouths and therefore having negative effects on marine life.   

(Acid Mine Drainage and its control. Pertha Das Sharma).

From the beginning mining has had an effect on the environment. The exploration of field surveys and research involves clearing of land and drilling which essentially has the risk of contributing to exposing high metal content. Once exposed these metals begin the process of oxidization and ultimately lead to acid mine drainage. On mine sites there are storage ponds from clearing the exploded soils, which in tern may become contaminated and then seep into the water systems. (Acid Mine Drainage and its control. Pertha Das Sharma).