Coal deposits as promising alternative sources for gallium

Qin, Shenjun; Sun, Yuzhuang; Li, Yanheng; Wang, Jinxi; Zhao, Cunliang; Gao, Kang

doi:10.1016/j.earscirev.2015.07.010

Cited by 96 publications

(51 citation statements)

References 56 publications

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“…Recently, a variety of trace elements including Li, Ge, U, Hg is reported to be enriched in coal seams worldwide (Dai et al, 2014;Qin et al, 2015aQin et al, , 2015bSeredin et al, 2013;Sun, 2015;Sun et al, 2012Sun et al, , 2013aSun et al, , 2013bSun et al, , 2016. Most of these studies focused on the anomalous concentration of trace elements in coals and the affinity of these elements to the organic matters or the inorganic parts can be discerned on the level of mineral (Chu et al, 2015;Kang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Binding characteristics of Cd²⁺, Zn²⁺, Cu²⁺, and Li⁺ with humic substances: Implication to trace element enrichment in low-rank coals

Xing

Zhang

et al. 2016

Energy Exploration & Exploitation

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Binding characteristics of metal ions (Li + , Cd 2+ , Zn 2+ , Cu 2+ ) with humic substances (HSs) are investigated by first principle calculation at BP86/SDD level. In the present work, HSs are well represented by singly deprotonated alkyl/aryl carboxylic acid. The results reveal that the bidentate is the strongest complexation form. Moreover, with the increase of ionic potential, the binding energies of HSs to chelate metal ions increase in order, Li + < Cd 2+ < Zn 2+ < Cu 2+ . The nature of the ligand also exerts important influence on the stability of organometallic complexes. Specifically, for Li + , the ionic bond-forming part occurs as electroneutrality. Whatever electrondonating groups or electron-withdrawing groups including alkyl, aryl and its derivatives (salicylic acid and m (p)-substituted gallic acid by hydroxyl or amino) and carbon-carbon double bond connects to the carboxylate group, the electron density of the ionic bond-forming part will be changed resulting in the decrease of binding energy (BE). However, for ions with high ionic potential or high positive charge density (Cd 2+ , Cu 2+ and Zn 2+ ), the ionic bond-forming part is positively charged. From electron-withdrawing groups to electron-donating groups, the extent to deviate from electroneutrality is gradually decreased, although the quantity of electron is possibly insufficient to balance the extra positive charge. As a result, the BE value gradually increases, but does not reach a maximum for studied ions and ligands. Besides, mixed functional groups are able to stabilize organometallic complexes. The optimal mixed functional group is carboxyl and hydroxyl on ortho position, followed by two hydroxyls, hydroxyl and carbonyl, carboxyl and carbonyl, In the end, the geochemical behavior of trace elements in coalification is predicted: small organic acids generated by decomposition of dead plants in relatively oxidized environments will facilitate the enrichment of lithium and this proportion of lithium will be released into pore water in the polymerization of small molecules, possibly accumulating in secondary minerals in low-rank coals; metal ions with high ionic potential bonded by organic molecules will be released in a later stage and accumulate in slightly higher rank coals.

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Section: Introductionmentioning

confidence: 99%

Binding characteristics of Cd²⁺, Zn²⁺, Cu²⁺, and Li⁺ with humic substances: Implication to trace element enrichment in low-rank coals

Xing

Zhang

et al. 2016

Energy Exploration & Exploitation

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“…The lithium content of this CFA generally exceeds the comprehensive industrial recycling index of the Chinese national standard for Specifications for Rare Metal Mineral Exploration (DZ/T/0203-2002) regarding pegmatite-associated lithium. Considering its high aluminum and lithium content [5,9], this CFA can be utilized as a substitute for bauxite and allophytin, high quality sources of which are scarce in China. The fly ash covered in this study was markedly enriched in a number of trace elements in comparison with that of the other regions shown in Figure 2 [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…CFA can cause serious dust pollution [1], and the toxic elements contained in CFA can leach into soil and cause serious secondary pollution [2][3][4]. Millions of tonnes of CFA, containing high proportions of aluminum and lithium, are released each year from coal-fired power stations in the Inner Mongolia, Ningxia, and Shanxi provinces in northern China [5][6][7][8], which is illustrated in Figure 1. Typically, the CFA in these areas contains 40-50% aluminum and more than 0.2% lithium.…”

Section: Introductionmentioning

confidence: 99%

An Efficient Approach for Lithium and Aluminum Recovery from Coal Fly Ash by Pre-Desilication and Intensified Acid Leaching Processes

Qin

Kang

et al. 2017

Metals

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A novel technique was developed for the recovery of lithium and aluminum from coal fly ash using a combination of pre-desilication and an intensified acid leaching process. The main components of the high-aluminum fly ash were found to be Al 2 O 3 and SiO 2 , and the Al/Si ratio increased from 1.0 to 1.5 after desiliconization. The lithium content of the coal fly ash met national recycling standards. The optimal acid leaching conditions, under which the leaching efficiencies of lithium and aluminum were 82.23% and 76.72%, respectively, were as follows: 6 mol/L HCl, 1:20 solid to liquid ratio, 120 • C and 4 h. During the hydrochloric acid pressure leaching process, spherical particles of desilicated fly ash were decomposed into flakes. Part of the mullite phase was dissolved, and most of the glass phase leached into the liquor. The generation of the silicates hindered lithium transport, which decreased the leaching rate of lithium. This work suggests that the preprocessing is a promising option for effective recovery of high-aluminum and fly ash-associated lithium.

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“…High concentrations of economically important elements, such as Li, Ga, and rare earth elements and yttrium (REY), have been reported in Carboniferous coals from North China (e.g. Lin et al, 2013;Qin et al, 2015aQin et al, , 2015bSun et al, 2012Sun et al, , 2016. Recently, Late Permian coals in southwestern China have also become a topic of interest in coal geology and ore deposit research due to extremely enrichments of critical elements.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of elements associated with Late Permian coal in the Zhongliangshan mine, Chongqing, Southwest China

Qin

Gao

et al. 2018

Energy Exploration & Exploitation

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The enrichment and geochemical significance of elements associated with Late Permian coals in Southwest China have always gained widespread interest in the field of coal geology. The present study focuses on the geochemical characterization of Late Permian coal in the Zhongliangshan mine. Twenty-three samples were collected from the K1a coal seam of the Zhongliangshan mine, and the major and trace elements in the coal were analyzed by using X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry. The composition of minerals in the Zhongliangshan coal, and the modes of occurrence of coal-associated elements, especially those with elevated contents, were studied through a combination of microscopic analyses, X-ray powder diffraction, and scanning electron microscope -energy dispersive X-ray spectrometer. The minerals in coal mainly consist of kaolinite, pyrite, calcite, and quartz, as well as small amount of gypsum and anatase. Compared with the average elemental concentrations in world coal, the Zhongliangshan coal is enriched in Cr, and slightly enriched in Li, U, Sr, V and Ag. Combining the correlation analysis and sequential chemical extraction experiments, it can be inferred that many trace elements in the Zhongliangshan coal have both inorganic and organic affinities. The elements Cr, Li, and V mainly occur in clay minerals, and also are related to organic matter in the coal. Uranium presents firstly in the organic and then silicate states. Strontium shows multiple modes of occurrence including carbonate, silicate, and exchangeable ion states, and Ag primarily occurs in sulfides followed by silicates. The terrigenous debris input from the Emeishan basalt is the major reason for the enrichment of above elements in the Zhongliangshan coal.

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Coal deposits as promising alternative sources for gallium

Cited by 96 publications

References 56 publications

Binding characteristics of Cd²⁺, Zn²⁺, Cu²⁺, and Li⁺ with humic substances: Implication to trace element enrichment in low-rank coals

Binding characteristics of Cd²⁺, Zn²⁺, Cu²⁺, and Li⁺ with humic substances: Implication to trace element enrichment in low-rank coals

An Efficient Approach for Lithium and Aluminum Recovery from Coal Fly Ash by Pre-Desilication and Intensified Acid Leaching Processes

Geochemistry of elements associated with Late Permian coal in the Zhongliangshan mine, Chongqing, Southwest China

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Coal deposits as promising alternative sources for gallium

Cited by 96 publications

References 56 publications

Binding characteristics of Cd2+, Zn2+, Cu2+, and Li+ with humic substances: Implication to trace element enrichment in low-rank coals

Binding characteristics of Cd2+, Zn2+, Cu2+, and Li+ with humic substances: Implication to trace element enrichment in low-rank coals

An Efficient Approach for Lithium and Aluminum Recovery from Coal Fly Ash by Pre-Desilication and Intensified Acid Leaching Processes

Geochemistry of elements associated with Late Permian coal in the Zhongliangshan mine, Chongqing, Southwest China

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Binding characteristics of Cd²⁺, Zn²⁺, Cu²⁺, and Li⁺ with humic substances: Implication to trace element enrichment in low-rank coals

Binding characteristics of Cd²⁺, Zn²⁺, Cu²⁺, and Li⁺ with humic substances: Implication to trace element enrichment in low-rank coals