Global warming impact of the magnesium produced in China using the Pidgeon process

Ramakrishnan, Sita; Koltun, Paul

doi:10.1016/j.resconrec.2004.02.003

Cited by 167 publications

(104 citation statements)

References 9 publications

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“…In separating the concentrates of bastnasite and monazite, a combination of separation processes (after grinding) are used including wet-magnetic separation and froth floatation. Since mining and beneficiation are established technologies, data is mostly based on our previous studies in mining and beneficiation [31,32].…”

Section: Stage 1: Mining and Beneficiation Bayan Obo Mineralmentioning

confidence: 99%

Life Cycle Impact of Rare Earth Elements

Koltun

Tharumarajah²

2014

ISRN Metallurgy

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The diverse properties of rare earth elements have seen broad and growing applications in clean energy technologies, hybrid vehicles, pollution control, optics, refrigeration, and so on. This study presents a "cradle-to-gate" life cycle assessment of the energy use, resource depletion, and global warming potential resulting from the production of rare earth elements (REEs) using the Bayan Obo rare earth operation in Inner Mongolia, China, as a representative system. The study aggregates data from the literature, LCI databases, and reasonable estimations. A novel economic value-based allocation method for the multiple coproducts of the process is proposed. It is found that four of the high priced REEs scandium, europium, terbium, and dysprosium have very high GWPs from production relative to the rest. A mass-based allocation is also provided for comparison. Impacts on immediate local environment from waste streams that can be toxic are not included in this study.

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Section: Stage 1: Mining and Beneficiation Bayan Obo Mineralmentioning

confidence: 99%

Life Cycle Impact of Rare Earth Elements

Koltun

Tharumarajah²

2014

ISRN Metallurgy

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“…[1][2][3][4][5][6][7][8] During the industrial production of magnesium using the Pidgeon process in China, calcium fluoride may be added at a nominal rate of 0.2 kg per 1 kg of pure magnesium. [9] Calcium fluoride also obviously enhances the reaction rate of magnesia in the preparation of magnesium using vacuum carbothermic reduction method.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

Jiang

Liu

et al. 2015

Metall Mater Trans B

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The use of a small amount of calcium fluoride as an additive greatly accelerated the reduction of magnesia during the preparation of magnesium from magnesia using the vacuum carbothermic reduction method. At 1573 K (1300°C), the magnesia reaction rates of the samples with 1, 3, and 5 pct CaF 2 were all approximately 26 pct, three times that of free CaF 2 , and they were arranged in order of the calcium fluoride weight percentages at 1673 K (1400°C). The residues were analyzed using chemical analysis, XRD, SEM, EDS, and XRF. The possible acceleration mechanism was discussed. Calcium fluoride combined with magnesia and silicon dioxide to form a eutectic that melted as a channel to aid the solid-solid reaction between carbon and magnesia at approximately 1573 K (1300°C). Calcium fluoride in the molten state offered free calcium ions and fluorine ions. Fluorine ions entered and distorted the magnesia crystal lattice. The structural strength and chemical stability of the magnesia crystal lattice decreased, which facilitated the magnesia reduction by carbon. Calcium ions were employed to generate the calcium and magnesium silicate. The easyly evaporating fluorides, including magnesium fluoride and silicon tetrafluoride, were regarded as the main reason for the loss of fluorine.

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“…The vapor condenses at the water-cooled feed end of the retort, forming a crystalline magnesium crown. The magnesium crowns are then refined to produce magnesium ingots [10][11][12][13][14]. The briquettes after the MgO reduction are discharged from the retorts as a by-product or waste.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand it is also energy and natural-resource intensive. There are several studies of environmental issues relating to the magnesium production, including emissions of air pollutants [11] and global warming impact [11,14]. The global warming impact of magnesium production in China has been estimated near to 42 kg CO 2 eq/kg Mg ingot [14], which is related largely to a high materials input.…”

Section: Introductionmentioning

confidence: 99%

“…Some calculations have shown that pellets or briquettes of 6.678 kg, made of calcined dolomite (5.385 kg), ferrosilicon (1.19 kg) and calcium fluoride, are needed for producing 1.096 kg crown magnesium [14], thus, generating a solid by-product or waste, the Magnesium slag, weighing 5.582 kg (6.678-1.096). (The Magnesium slag is hereafter abbreviated as Mg slag.)…”

Section: Introductionmentioning

confidence: 99%

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Treatments of Magnesium Slag to Recycle Waste from Pidgeon Process

Han

Yang

et al. 2011

AMR

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Magnesium slag powder from a local magnesium plant was treated to improve the volume stability for its application as building materials. The slag was mixed with borates, pressed into briquettes, and then sintered at high temperature. SEM studies show that at the higher temperature Ca2SiO4polymorphs were stabilized by Na and B ions in the added borates. The free MgO content in the slag was also decreased by the sintering treatment. The slag powder, after mixing with 0.4-0.6% of borates and sintered at 1200°C in 5-6 hours, has become volume stable aggregates. It is then possible to use the treated slag in constructions, saving valuable natural resources and decreasing the global warming impact from magnesium production via Pidgeon process.

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Global warming impact of the magnesium produced in China using the Pidgeon process

Cited by 167 publications

References 9 publications

Life Cycle Impact of Rare Earth Elements

Life Cycle Impact of Rare Earth Elements

Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

Treatments of Magnesium Slag to Recycle Waste from Pidgeon Process

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