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Dependence between the parameters of storage of artificial soils from their specific properties
Published in Vladimir Litvinenko, Scientific and Practical Studies of Raw Material Issues, 2019
V.N. Kondakova, G.B. Pospekhov
A heap is a constructed pile of crushed, and in most cases agglomerated rock material built on an impermeable fitted with a solution collection system. Underneath the heap aeration pipes are placed. The heap is irrigated from the top surface, either by sprinklers, sprays or drip emitters. Heap heights are typically 6-10 m, but taller heaps are also common to reduce the footprint of the operation. Another option is to construct series of a piles on top of one another. In this case the height of a heap may be rather significant. The main aim of all operations is to provide appropriate filtration properties besides adequate construction characteristics. Optimally, heap leaching should be a low-cost technology for the extracting from low-grade ores, suitable mostly for remote mine sites. However, the complexity of leach process is often underestimated, resulting in underperforming heaps.
Gold Ore Processing and Environmental Impacts: An Introduction
Published in Sadia Ilyas, Jae-chun Lee, Gold Metallurgy and the Environment, 2018
Despite being highly toxic, the cyanide leaching of gold is the most common technique in the exploitation of gold from its (high and low grade) ore bodies. Vat leaching is used for high grade ore processing, in which the ore slurry is treated under agitation in large tanks containing the solution of sodium cyanide. For low grade ores, heap leaching is practiced in which a dilute solution of sodium cyanide is sprayed from the top of the heaped pile. The cyanide solution percolates down with time and leaches the gold, and the gold bearing solution can be collected from the bottom of the heap. During cyanidation, the metallic gold is oxidized to leach in a dilute alkaline solution of cyanide. The cyanidation reaction of gold was originally given by Elsner in 1849; however, numerous studies on leaching mechanism and parametric influences have been carried out until now. These will be discussed separately in the cyanidation chapter.
Biotechnological Treatment of Liquid and Solid Inorganic Wastes
Published in Daphne L. Stoner, Biotechnology for the Treatment of Hazardous Waste, 2017
W. D. Gould, R. G. L. McCready
Techniques for contacting ores with the leaching solution include dump leaching, heap leaching, and tank leaching.125 Leach dumps are usually located in valleys in which low grade ores of varying particle size (<1.0 m diameter) are dumped in lifts of 50 to 100 ft in height. Copper leach dumps can contain up to 4 billion tons of material. Leach solutions are introduced on the surface of the dump by sprinkling or flooding. The solution is recovered from the base of the dump and processed to recover the metals. In a heap leaching operation, the ore is placed on an impermeable surface, and the leaching solution is applied to the top of the heap. Approximately 100,000 to 500,000 tons of ore are used in a single heap. Tank leaching can be done in a standard bioreactor such as a CSTR. The technology for the bacterial leaching of metals is well developed and could be a technically and economically feasible method for the removal of metals from contaminated sludges and soils.
Effects of physicochemical properties of Au cyanidation tailings on cyanide microbial degradation
Published in Journal of Environmental Science and Health, Part A, 2021
Cosmos Anning, Michael O. Asare, Wang Junxiang, Geng Yao, Lyu Xianjun
To recover Au particles, finely ground ores must be subjected to tank leaching, a technique used for Au leaching from ores using CN−, which consists of dissolving ore particles using CN− solution in tanks.[52,53] In addition, heap leaching is an advanced method used to recover Au particles (0.8–1.1 g/t) from low-grade ores; however, heap leaching can generate large quantities of waste. Heap leaching requires crushing ore-bearing rocks into small particles with diameters in the centimeter range and placing them on large pads to form heaps or piles. Thereafter, a CN− solution is sprinkled on the crushed ore particles to leach Au,[54] and the residual barren solution formed after Au extraction is released into ponds.
Biotechnological Avenues in Mineral Processing: Fundamentals, Applications and Advances in Bioleaching and Bio-beneficiation
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Srabani Mishra, Sandeep Panda, Ata Akcil, Seydou Dembele
With regards to bioleaching studies, stirred tank and heap leaching tests have been scaled up (Kuyucak 1998; Morin 2007; Panda et al. 2015a). Stirred (agitated) tank bioleaching has been quite attractive and industrially relevant for processing of sulphide concentrates esp. pyrite and arsenopyrite for recovery of base and precious metals; however, many successful demonstration operations have been carried out for sphalerite (ZnS), pentlandite ((FeNi)9S8), covellite (CuS), chalcocite (Cu2S), and chalcopyrite (CuFeS2) (Batty and Rorke 2005; Clark et al. 2005; Dew and Miller 1997; Morin 2007; Sandstrom, Sundkvist and Peterson 1997). The gradual evolution and application of stirred tank bioleaching (from lab to industrial scale) of sulphide ores is shown is Figure 6. More specific details of the method and operation of stirred tank bioleaching can be found elsewhere (Deveci 2004; Mahmoud et al. 2017; Morin 2007). On the other hand, as a hydrometallurgical process, heap leaching has been used for base metals such as copper, nickel, uranium and precious metals such as gold and silver recovery from their ores without the necessity for fine grinding (Ghorbani et al. 2011; Parbhakar-Fox 2016; Thenepalli et al. 2019). This process got its first application in the middle of 16th century in Hungary for copper extraction. The conventional heap leaching uses chemicals as lixiviant such as strong acid for base metals and cyanide for gold extraction (Thenepalli et al. 2019), which can pose environment problems (Assadi et al. 2008). On the other hand, heap bioleaching is an economic and eco-friendly process that, instead of using chemicals, need microorganism as lixiviant to extract metal values generally from sulphide low grade ore (Ghorbani, Franzidis and Petersen 2016; Panda et al. 2015a; Pradhan et al. 2008). Heap bioleaching has been applied for the first time at the beginning of the 1890s for copper (0.75% Cu grade) extraction at the Rio Tinto mines in Spain (Acevedo 2002; Brandl 2001; Natarajan 2018). This process is applied industrially for single metal ores such as copper, uranium, and gold ores and also for polymetallic nickel, zinc, cobalt, and copper ores treatment (Natarajan 2018). A lot of studies related to heap bioleaching is available today and specific details can be found elsewhere (Halinen et al. 2009; Ijaz et al. 2017; Leahy, Davidson and Schwarz 2007; Leahy, Schwarz and Davidson 2006; Panda et al. 2012; Petersen and Dixon 2007; Shiers, Collinson and Watling 2016; Watling 2006). The main industrial applications of heap bioleaching are listed in Table 4. Compared with stirred tank bioleaching, heap bioleaching presents constrain in terms of process control. Nevertheless, several studies have been undertaken in order to improve heap bioleaching process on different type of ores (Kremser et al. 2020; Marín et al. 2021; Staden and Petersen 2021).