Environmental Engineering Reference
In-Depth Information
soil is 2.67 with 41% porosity. The presence of sand, silt and clay content in
soil is 8.44%, 46.55 % and 45.01% respectively. The texture of the soil is silty
clay in nature and the plasticity index of soil is 12.84 %. However, CCRs
andjarosite waste, do not deserve Atterberg limits properties. The high
electrical conductivity in jarosite (13597 µmohs/cm) indicates that the
presence of ions is higher than that of CCRs (261.5 µmohs/cm). The pH of
jarosite waste when released from extraction process is in the range of 2.6 - 4.0
(Mymrin and Vaamonde, 1999 & 2005; Dutrizac, 1980), but it is neutralized
using lime before discharge in to dump site and hence pH showed almost
neutral.
Table 3. Particle size variation of jarosite waste and PCCRs
%
Particle
size in
m
Jarosite waste (µm)
PCCRs ( m)
R1
R2
R3
Mean
SD
R1
R2
R3
Mean
SD
D 50
3.89
3.94
3.91
3.91
0.03
139.5
140.0
145.2
141.56
2.57
D 90
15.99
16.39
16.25
16.21
0.20
19.74
19.88
19.53
19.72
0.18
SSA
(cm 2 /g)
10524.9 10463.5 10500.1 10496.2 30.90
1456.7 1496.5 1338.6 1430.6
67.1
SSA- Specific surface area.
Table 4. Physico-chemical characteristics
of PCCRs, jarosite waste and Clay
Properties
PCCRs
Jarosite waste
Clay
Bulk density (g/cm 3 )
0.93
0.98
1.49
Specific gravity
1.77
2.92
2.38
Porosity (%)
49.4
67.00
36.31
Water holding capacity (%)
65.25
109.96
43.00
pH
8.30
6.78
7.64
Electrical conductivity (dS/m)
261.5
13597
6506
355
16.2
18.4
Particle Size (D 90 ) m
Texture
Sandy loam
Silt clay loam
Silty clay
The major chemical constituents in the jarosite waste, CCRs and clay are
shown in Table 5. Results revealed that a major portion of jarosite consists of
oxides of iron, sulphur and zinc but, CCRs constitutes silica, alumina and iron
oxide. The toxic elements in jarosite waste and CCRs is shown in Table 6.
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