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doi: 10.1007/s10230-008-0037-5pmid: N/A
This paper presents a preliminary compilation and analysis of the water reported to have been consumed by a range of various mineral commodities and compares it to mine production data. This has been undertaken to assess and quantify the ‘embodied water’ of mineral products—a key aspect of sustainability (embodied water is the total water required to produce a good or service). At present, although the use of formal reporting protocols such as the global reporting initiative (GRI) is increasing, there are still critical weaknesses. Some key aspects to facilitate proper water accounting are not listed in sustainability reports, including the extent of recycled water used, mine site water inventories, the quality of various waters, and impacts on water resources. Based on the data compiled, there is wide variation in the water used for different mineral commodities as well as for the same commodity. There is little evidence for ‘economies of scale’ in base metals and bulk minerals, though for precious metals (gold, platinum), greater throughput does tend to lead to greater efficiency. For many mines, there is little evidence of improving efficiency over time, although some mines have made substantive improvements in reducing water consumed. The grade of ore being processed is clearly critical in understanding the embodied water of minerals, with declining ore grades leading to an increased chance of higher embodied water in the future. Given that many metals are declining in average ore grade, the sensitivity of embodied water to ore grade provides a major sustainability challenge for mining generally. In summary, the embodied water of minerals is clearly significant, and will likely gradually increase in the future, and so must be more completely accounted for to understand a fundamental aspect of sustainability and mining—that of water resources.
Hakkou, Rachid; Benzaazoua, Mostafa; Bussière, Bruno
doi: 10.1007/s10230-008-0036-6pmid: N/A
The Kettara site (Morocco) is an abandoned pyrrhotite ore mine in a semi-arid environment. The site contains more than 3 million tons of mine waste that have been deposited on the surface without concern for environmental issues. Tailings were stockpiled in a dyke and pond and in piles, over an area of about 16 ha, and have generated acid mine drainage (AMD) for more than 24 years. The mine waste and secondary precipitates from this mine were characterized using geochemical and mineralogical techniques. The Kettara wastes contain 1.6–14.5 wt% sulfur, mainly sulfide minerals (e.g., pyrrhotite, pyrite, chalcopyrite, galena, and sphalerite). The main gangue minerals were goethite, quartz, chlorite-serpentine, talc, muscovite, and albite. Carbonates occur at very low quantities (less than 1 wt%). The most abundant heavy metals were Cu, Zn, Cr, Pb, Co, As, Cd, and Ni. Acid–base accounting static test results showed that all the samples have low values of acid-neutralizing potential (NP) (0–9 kg CaCO3/t). The mine waste has high acid-producing potential (AP) (51–453 kg CaCO3/t). Abundant secondary mineralogy is present, consisting mainly of halotrichite, goethite, jarosite-hydroanion, hydroniumjarosite, starkeyite, gypsum, alunite, copiapite, butterite, and coquimbite. Hardpans, which can prevent water infiltration to fresh tailings beneath and thereby lessen the rate of sulfide reactivity, were observed during sampling of the fine tailings. Mineralogical analysis indicated that the cementitious phase of the hardpan is mainly goethite. The alteration observed in the tailings pond does not extend more than 5–15 cm.
Hakkou, Rachid; Benzaazoua, Mostafa; Bussière, Bruno
doi: 10.1007/s10230-008-0035-7pmid: N/A
Weathering and humidity cell tests were used to predict the potential for acid mine drainage (AMD) and to estimate the mineral reaction rates and depletion of fine and coarse tailings from the abandoned Kettara mine, Morocco. The geochemistry of the fine and coarse mine wastes was similar and, as expected by static tests, the wastes produced significant amounts of AMD. The sulfate production rate of both fine and coarse tailings was very high (2,000–8,000 and 2,400–560 mg SO4/kg/week, respectively) during the first weeks of kinetics tests. After 9 weeks, sulfate release became low, ranging between 600 and 78 mg SO4/kg/week for fine tailings and 500–120 mg SO4/kg/week for coarse tailings. Effluent water samples had low pH (2.9–4.2) and elevated concentrations of acidity, sulfate, iron, copper, and zinc. Most or all of the dissolved K, Na, Al, Mg, and Si in the AMD result from the acidic dissolution of silicates (chlorite, talc, muscovite, and albite). Fine tailings produce much higher concentrations of acidity and sulfate than coarse tailings. However, due to greater transport of oxygen and water within the coarse waste, coarse tailings could be of greater environmental significance than fine tailings. The coarse waste continued to release acid after 378 days of leaching, whereas the fine tailings naturally passivates. These laboratory results agree with field observations; the upper profile of the coarse waste rock dam is highly oxidized (75 cm) whereas oxidation in the fine tailings does not extend more than 5–15 cm beneath the surface. A comparison between weathering and humidity cell tests indicated that the general trend of dissolution of metals was essentially similar for both methods. However, sulfate depletion rates were higher for the weathering cell tests. These tests indicate that the Kettara tailings piles and dam will continue to release acid for a long time unless remedial action is taken.
Abed, Abdulkader; Sadaqah, Rushdi; Kuisi, Mustafa
doi: 10.1007/s10230-008-0039-3pmid: N/A
Representative samples were collected from various stages of phosphorite mining and beneficiation from the Al-Abiad and Al-Hasa mines in central Jordan and the Eshidiyya mine in southern Jordan. After open pit mining, the rock is crushed and dry-sieved to pass 12 mm in order to concentrate the ore. The sieved material is then agitated, washed with fresh water, and wet sieved to pass 4 mm. Samples were analyzed by ICP-MS for major elements and As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, U, V, and Zn. We found that throughout the above-mentioned processes, potentially toxic metals are partially removed from the ore. However, most of the contaminants are still retained within the final phosphorite product. The slime and slime water were analyzed; we found no effect of the slime water on the nearby ground water regime. The phosphorite is converted to fertilizer through reactions with sulfuric acid and then ammonia to produce diammonium phosphate (DAP). Gypsum is produced as a reject. The potentially toxic metals follow the behavior of P and are enriched by a factor of more than 1.5 in the DAP compared with the input phosphorite. The trace metal content in the phosphogypsum is very low.
Deb, Debasis; Deshpande, Vinayak; Das, Kamal
doi: 10.1007/s10230-008-0030-zpmid: N/A
Water samples collected from surface coal mine sites, adjacent rivers, and nearby tube wells were analyzed for pH, selected contaminant concentrations, electrical conductivity, total dissolved solids, total suspended solids, and total hardness. Statistical analysis of the data showed that most of the parameters (variables) were correlated with each other, having a correlation coefficient between 0.29 and 0.99. Hence, variability of output parameter, in this case, water quality around mine sites, cannot be explained explicitly by any single input parameter. Principal component analysis was used to evaluate the orthogonal and independent components of the original data sets. The first principal component and pH were used to compare water quality around the mine sites using fuzzy reasoning techniques based on Mamdani’s principle. Finally, a prediction map of water quality was prepared for the entire study area. Although the contaminants of concern will vary from site to site, this basic approach should be useful in assessing water quality at other locations where funds or site access limit ones ability to sample more intensely.
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