Strategic reclamation of post-tin mining areas based on soil mineralogy,
heavy metal and particle size constituent of refused materials
Abstract
Characteristics of refused materials are prerequisite information
required to determine the strategic reclamation of extreme land
degradation in post-tin mining areas. The objective of the study was to
evaluate mineralogical, chemical, and physical properties and heavy
metals of spoil and tailing as the basis for reclamation measures. Seven
representative soil profiles were made and sampled to a depth of 130 cm
for various soil analyses. Results showed that tin mining has
drastically altered the soil texture from sandy clay loam under native
conditions to loamy sand and sand under post-tin mining. Mineralogical
constituents of refused materials were mainly mineral resistant to
chemical weathering, consisting of predominant quartz with small amounts
of tourmaline, opaque, zircon and garnet. Total X-ray fluoresce
elemental analysis showed extreme high SiO2 content (92-96%) associated
mainly with quartz mineral, and extremely low oxides of Ca, Mg, P, K and
S (< 0.2% altogether). This suggests all nutrients are severe
problems for crops. Type of total heavy metals showed the Cr2O3 was high
in sandy tailing (204 - 286 mg kg-1), while the SnO was low (0 -153 mg
kg-1) and they were preserved in the structure of host minerals, thereby
the health risk is negligible. Based on many serious constraints of
soils, the strategic reclamation to recover soil productivity and
ecological function was the building up soil organic matter,
establishing “pot planting point” technique, complete fertilizer
application, and selection of crops with an ability to fix N nutrient
from the atmosphere, and adaptive to low soil nutrients.