Red Mud (RM) and Soil Amelioration: Improvement in Soil Quality

Red Mud (RM) and Soil Amelioration: Improvement in Soil Quality

Amit Kumar (Independent Researcher, India)
Copyright: © 2019 |Pages: 17
DOI: 10.4018/978-1-5225-7940-3.ch009

Abstract

Rapid growth in industrialization, which is necessary and inevitable for society progress, has also created negative encroachment. Red mud produced during alumina production has strong alkanity in a pH range of 10-13% because of the sodium hydroxide solution used in the refining process. The base is strong enough to kill plant and animal life, and due to finer particle and trace metal content, it creates soil contamination, ground water pollution, and suspension in ocean; hence, we need precautions while we use this waste to add with soil. Red mud occupies a large area or its deposition in it. Red mud has properties similar to sandy clay. Red mud has property similar to clay and sand, even if it does not contain quartz or clay mineral. Bauxite residue/red mud can be mixed with variant type of saline soils, acid soils organic rich material, and silicate soil suitable pH conditions were achieved to promote vegetation growth.
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Red Mud

The Red mud is the solid waste residue of the digestion of bauxite ores with caustic soda for alumina (Al2O3) production. It is a mixture of compounds originally present in the parent mineral bauxite and of compounds formed or introduced during the Bayer cycle. Red mud can be applied as soil ameliorant to acidic, sandy and micronutrient deficient soils. There are still knowledge gaps regarding the effects of red mud on the soil microbial community. According to average well color development, substrate average well color development and substrate richness 5–20% red mud increased the microbial activity of the acidic sandy soil over the short term, but the effect did not last for 10 months. Shannon diversity index showed that red mud at up to 20% did not change microbial diversity over the short term, but the diversity decreased by the 10th month. 30–50% red mud had deteriorating effect on the soil microflora. 5–20% red mud soil mixture in the low quality subsoil had a long lasting enhancing effect on the microbial community based on all parameters. However, 50% red mud soil mixture caused a decrease in diversity and substrate richness. The properties of red mud are listed in Table 1.

Table 1.
Properties of red mud
S. No.PropertiesValue
1.Specific gravity2.8
2.% Gravel size3.60
3.% Sand size18.80
4.% Silt and clay size77.60
5.Coefficient of Uniformity14.97
6.Coefficient of Curvature1.81
7.Liquid limit in percentage43.2
8.Plastic limit in percentage31.55
9.Plasticity Index in
percentage
11.65
10.Maximum dry density (in kN/m3)16.48
11.Optimum moisture content
in percentage
24.75
12.Void ratio at maximum dry
density and OMC
0.66

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