Recovery of gallium from coal fly ash

Fang, Zheng; Gesser, H. D.

doi:10.1016/0304-386x(95)00055-l

Cited by 98 publications

(35 citation statements)

References 12 publications

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“…For example, Simonetti et al (2000) reported that Ba, Rb, and Sr concentrations in snowpack samples collected in eastern Ontario were approximately 2-3 times higher than concentrations measured in northeastern Quebec sites that are more distant from industrial emission sources. While deposition data for many elements in Ontario are lacking, several of the trace elements considered in this study, including As, Be, Cr, Fe, Ga, Tl, U, and V are released from a variety of activities; notably coal burning, metal smelting, diesel and gasoline burning and agriculture (Ahier and Tracy 1997;Brewer and Belzer 2001;Fang and Gesser 1996;Helsen 2005;Hope 1997;Kazantzis 2000;Neal et al 1996), which are prevalent in south-central Ontario. Base cations such as Ca, K, and Mg are also released from industrial emissions such as coal burning (Lee and Pacyna 1999).…”

Section: Resultsmentioning

confidence: 99%

Element mobility and partitioning along a soil acidity gradient in central Ontario forests, Canada

Watmough

2007

Environ Geochem Health

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The potential environmental risk posed by metals in forest soils is typically evaluated by modeling metal mobility using soil-solution partitioning coefficients (K(d)), although such information is generally restricted to a few well-studied metals. Soil-solution partitioning coefficients were determined for 17 mineral elements (Al, As, Be, Ba, Ca, Cr, Cu, Fe, Ga, K, Li, Mg, Rb, Sr, Tl, U and V) in A-horizon (0-5 cm) soil at 46 forested sites that border the Precambrian Shield in central Ontario, where soil pH(aq) varied from 3.9 to 8.1. Sites were dominated by mature sugar maple (Acer saccharum Marsh.), white birch (Betula papyrifera Marsh.), balsam fir (Abies balsamea (L.) Mill.) or white pine (Pinus strobus L.). Log K(d) values for all elements could be predicted by empirical linear regression with soil pH (r(2) = 0.17-0.77) independent of forest type, although this relationship was greatly affected by positive relationships between acid-extractable metal concentration and pH(aq) for 13 of the 17 elements. Elements that exhibited strong or moderate (r(2) > 0.29; p < 0.001) relationships with soil pH(aq) in soil water extracts include Al, Ba, Fe, Ga, K, Li, Rb, Tl, V (negative) and Ca (positive). Elemental partitioning in mineral soil was independent of forest type; tree species differed in their response to chemical differences in mineral soil. For example, Rb, Ba, and Sr concentrations in foliage of sugar maple and white birch significantly increased with increasing soil acidity, whereas Rb, Ba, and Sr concentrations in balsam fir and white pine foliage exhibited no response to soil pH(aq). While K(d) values can provide useful information on the potential mobility and bioavailability of mineral elements in forest soils, care must be used when interpreting the relative contribution of solid and aqueous phases to this relationship and the differing responses of vegetation in elemental cycling in forests must also be considered.

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Section: Resultsmentioning

confidence: 99%

Element mobility and partitioning along a soil acidity gradient in central Ontario forests, Canada

Watmough

2007

Environ Geochem Health

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“…Owing to the volatility, gallium has no chance to condense on the bottom ash and is scavenged from the gas phase by high surface area fly ash particles via the heterogeneous condensation and adsorption mechanisms during coal combustion. Generally, the more the fine particles of fly ash, the higher the Ga content [31][32][33].…”

Section: Overall Distribution Of Gamentioning

confidence: 99%

Distribution, occurrence and enrichment causes of gallium in coals from the Jungar Coalfield, Inner Mongolia

Wang

Qin

Liu

et al. 2011

Sci. China Earth Sci.

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We collected eleven bench samples of No. 6 coal from the Heidaigou Surface Mine, Jungar Coalfield, Inner Mongolia, China, and four samples from the affiliated coal preparation plant. Based on these samples, we used inductively coupled-plasma mass spectroscopy, X-ray diffraction, scanning electron microscope with an energy-dispersive X-ray spectrometer techniques, and borehole exploration data, to investigate the distribution, occurrence and enrichment causes of gallium (Ga) in the coals. Our results show: (1) Gallium is significantly enriched in the coal seams from the study area, with an average content of 18.8-26.0 ppm. Gallium is distributed heterogeneously in the coals, and reaches ore-forming scales only in No. 6 coal of Heidaigou Surface Mine, not in the other mining districts of Jungar Coalfield. (2) On the horizontal plane, Ga is enriched in the main minable coals from the northern and middle part of the coalfield. In the vertical profile, Ga content in the coal seams is higher at the base of Taiyuan Formation (Nos. 8 and 9) and Shanxi Formation (Nos. 3 and 4) than at the top of the Taiyuan Formation. Within the identical coal seam, Ga content is higher in the benches near the roof and floor than in the middle section. (3) Gallium in the coals is associated mainly with kaolinite and boehmite. Additionally, Ga may be adsorbed to some extent by humic acid, resulting in a high level in weathering coal. (4) Geological factors affect Ga enrichment in coal, such as the property of parent rocks in the source area, the sedimentary environment, organic matter, structure, and past magmatic hydrothermal activity. Especially, Ga content in parent rocks plays a leading role. (5) The mobility and precipitation of trace elements like Ga are controlled principally by the geochemical behavior of the major element Al. Terrestrial and transgressive environments can cause the precipitation of bauxite, whereas marine-continental depositional environments may cause the separation of Ga from Al. In addition, Ga may migrate in the form of gas, and may be affected by the ground temperature. Thus, it is relatively enriched in high-volatile coal. coal, gallium, distribution, occurrence, enrichment causes, Jungar Citation:Wang W F, Qin Y, Liu X H, et al. Distribution, occurrence and enrichment causes of gallium in coals from the Jungar Coalfield, Inner Mongolia.

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“…Gallium in fly ash occurs in the oxide and sulphide form in the oxidation state of +3 as substitutes for Al 3+ [40,41]. These forms are prone to acid and alkalis attack and the acid and or alkalis leach can provide the better recovery method [36][37][38][39].…”

Section: Extraction From Coal Fly Ash In Energy Plantsmentioning

confidence: 99%

The Growing Global Demand for Element Gallium: Electrical and Electronic Waste and Coal Fly Ash as Alternative Sources for its Sustainable Supply

2017

IJSR

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Gallium (Ga) is listed among the critical elements because of its high demand, low crustal concentration and dispersed occurrence. Growth in demand for this element is a response to proliferation in production of electronic devices and a global effort to decarbonised power production. This situation calls for exploitation of alternative sources such as fly ash and recycling processes from finished products. Wide implementation of these options is yet to be witnessed or still in their infancy with only a few facilities worldwide. This is attributable to low material intensity per unit product and the fact that this kind of waste has not accumulated high enough to attract recycling for instance. Most gallium bearing devices though have other critical, precious and or non-precious elements that co-exist with it. These co-existing elements are relatively high in concentrations and some of them are already being recycled from the same end-of-life products. Therefore an option that involves co-recovery of gallium together with other co-existing elements which are already being recycled and extraction from other sources such as fly ash is to be a viable pursuit in sustaining gallium supply. Viability stems on the similarities of gallium concentration in those sources, recovery methods and conditions used in recycling of gallium. More research however, to explore potential combinations of co-existing metals to be co-extracted with and methods to be employed is vital.

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Recovery of gallium from coal fly ash

Cited by 98 publications

References 12 publications

Element mobility and partitioning along a soil acidity gradient in central Ontario forests, Canada

Element mobility and partitioning along a soil acidity gradient in central Ontario forests, Canada

Distribution, occurrence and enrichment causes of gallium in coals from the Jungar Coalfield, Inner Mongolia

The Growing Global Demand for Element Gallium: Electrical and Electronic Waste and Coal Fly Ash as Alternative Sources for its Sustainable Supply

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