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The Anatomy of a Mine
Published in Karlheinz Spitz, John Trudinger, Mining and the Environment, 2019
Karlheinz Spitz, John Trudinger
The cut-off grade allows one to calculate the enrichment factor, the multiplier by which the average concentration of a particular element must be increased to become economically mineable (Figure 5.3). Each mineral or metal has its own enrichment factor, which represents a balance between the price of the material and its average abundance in the Earth’s crust. In general, the enrichment factor is greatest for metals that are least abundant in the crust, such as gold or mercury. Rather surprisingly however, gold, even though one of the scarcest mined elements, does not rank at the top of the list - mercury does. If the price of a particular metal was to fall, it would require an even higher enrichment factor for the metal to be economically extractable. On the other side, due to technological advances in finding and mining ores, many deposits that are now considered as ore are well below the lowest grade ores some decades ago.
Toward the Implementation of Circular Economy Strategies: An Overview of the Current Situation in Mineral Processing
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Luis A. Cisternas, Javier I. Ordóñez, Ricardo I. Jeldres, Rodrigo Serna-Guerrero
The scenario of increasing production and lower ore grade is bearable under two scenarios: on the one hand, an increase in the efficiency of the processes that allows greater use of resources and waste generated in the past, and on the other, greater exploitation of minerals that compensates for the depletion of minerals. The enrichment factor represents a balance between the price of the material and its abundance in the earth’s crust and implies the number of times the species must be concentrated for its extraction to be economically viable. Minerals such as iron and bauxite have low enrichment factors (around 4), so the specific amount of waste generated per unit of product is relatively low, compared to minerals with higher enrichment factors such as gold and noble metals (over 400) (Spitz and Trudinger 2019). However, the production levels mark the waste volume that the mining industry exhibits.
Evaluation, source apportionment and health risk assessment of heavy metal and polycyclic aromatic hydrocarbons in soil and vegetable of Ahvaz metropolis
Published in Human and Ecological Risk Assessment: An International Journal, 2021
Soghra Bahrami, Farid Moore, Behnam Keshavarzi
The enrichment factor (Eq. (1)) is an indicator used to determine metals source (natural or anthropogenic sources) (Chen et al. 2015). This indicator is obtained from normalizing the content of an element in the soil to the concentration of a reference element (RE) (local background) (Barbieri 2016). To estimate the threshold values and the background data range, the mean ± 2MAD (MAD = mediani (| Xi – medianj (Xj) |)) is used (Esmaeili et al. 2014). This is a nonparametric method and is not dependent on the distribution of data sets (Esmaeili et al. 2014). In this study, Sc was selected as the reference element because it shows low occurrence variability. Sutherland et al. (2000) defined five classes of enrichment factor: EF > 40, extremely high enrichment; 20 < EF < 40, very high enrichment; 5 < EF < 20, significant enrichment; 2 < EF < 5, moderate enrichment; and EF < 2, depletion to minimal enrichment (Sutherland et al. 2000). where RE is the reference element in soil samples.
Assessment of Heavy Metal Pollution of Soil-water-vegetative Ecosystems Associated with Artisanal Gold Mining
Published in Soil and Sediment Contamination: An International Journal, 2020
Emmanuel Amoakwah, Shamim Ahsan, Mohammad Arifur Rahman, Eric Asamoah, D. K. Essumang, Mursheda Ali, Khandakar Rafiq Islam
To date, several studies have reported about the assessment of soil, sediments, water, and vegetative systems accumulated with heavy metals in southern Ghana. However, those studies did not elaborately identify and link the source-sink relationships of heavy metals among soil-water-vegetative ecosystems. Source-sink relationship indices such as the geo-accumulation index determines the metal level of contamination or accumulation with reference to background levels of the same element in the environment. The enrichment factor is an indication of the enrichment of a selected metal with reference to background metals, such as Fe, which complements the geo-accumulation index by indicating the source of enrichment as either natural or anthropogenic. Likewise, the bio-accumulation factor is often used to evaluate the level of contamination in soil, sediment, and plants.