The characterisation of mineral and processing wastes is a key step during mining operations to mitigate risks associated with these wastes (Jamieson et al. 2015). This is made possible by providing appropriate remediation and waste management schemes. This characterisation help reveal the nature of the mine wastes and their potential interactions with the ecosystem (Hudson-Edwards and Dold 2015).
In the recent past, iron ore has been extracted in sedimentary rocks in different parts of the world over a long period (Lascelles 2011). Iron ore occurs as magnetite (Fe3O4), Goethite (FeO(OH)) and Hematite (Fe2O3)(Shrimali et al. 2016). Iron ore has very vast usage across the globe that makes it an essential commodity in industrialisation that has been continuously sought through mining (Cheneket 2018).
Mining of iron is associated with various mineral processing operations such as blasting, grinding, and magnetic separation, which results in the production of various solid mine wastes (Ferreira and Leite 2015).
According to Bett et al. (2016), significant iron ore deposits have been found in Marimanti in Tharaka Nithi County, Kitui County, Migori County, and Taita Taveta County, among other many areas.
Mine wastes constitute the largest percentage of any wastes produced by various industrial activities (Suleman and Baffoe 2017) & (Lottermoser and Lottermoser 2003).
In mining and mineral processing operations, mining wastes are sub-economic materials that contain low cutoff grades or do not contain any ore mineral (Lottermoser and Lottermoser 2003).
Mining operations, metallurgical extractions, and mineral processing produces various gaseous, liquid, and solid wastes. These are generated in different processes during mining, mineral processing, and metallurgical operations, as shown in Fig. 1.
During open pit mining and development, various mine wastes such as waste rocks, spoils, overburden, atmospheric emissions, and mine water may be emitted (Ferreira and Leite 2015). Mineral processing activities produce various processing wastes such as tailings, stockpiles of less grade materials, sludges, milling water, and emissions (David Meehan 2012).
The chemical and physical characteristics of mine wastes may vary in relation to the geochemistry and mineralogy of the resource, the size of the crushed mineral particles, processing chemicals, materials handling method, method and type of blasting techniques utilised, and the processing technology used (Jamieson et al. 2015), (Jelenová et al. 2018) and (Amos et al. 2015).
During materials handling at any mine, about 70% of the material handled is waste whose geochemical properties may be equivalent to the ore mined (Jamieson 2011). According Nordstrom (2011), drainage chemistry results from iron sulfide minerals oxidation such as pyrite, whose reaction generates acidity and various sulfates.
Most of the environmental challenges are associated with various mine wastes and their capability to react chemically with the water and air (Jamieson 2011). To carefully understand these reactions involved, it shall be needful to characterise the solid mine wastes in order to determine their geochemistry and mineralogy. This shall be done using XRD, XRF, and Petrographic techniques.