Fluoride emissions from Pidgeon process for magnesium production

Publikation: Forskning - peer-reviewKonferensbidrag

Nedladdad 708 gånger

Laner Wu ; Fenglan Han ; Qixing Yang ; Shengwei Guo

  • School of Material Science & Engineering, Beifang University of Nationality, Yinchuan, Ningxia
Primary magnesium is nowadays produced in China via Pidgeon process. An important reaction in the process is silicothermic reduction of MgO from dolime near 1200ºC under pressure of 2-10 Pa to generate Mg vapor. Fluorite, ranging 2-3% (mass fraction), is usually mixed with the raw materials to catalyze the reaction. Under the process conditions, CaF2 in the fluorite may form some fluorides to vaporize, thus polluting air. The fluorides remaining in the solid process waste, the Mg slag, may be dissolved to cause water pollution.
In the present study, experiments were performed by using retorts of pilot scale in a maffle furnace to simulate the Pidgeon process for primary Mg production. The test materials, briquettes of 5.6-10 kg made of dolime, ferrosilicon and fluorite, were charged in the retorts and heated under conditions similar to the industry operation. Fluoride minerals in the Mg slag from the simulation experiments were identified by XRD and SEM-EDS techniques. Quantities of some F-containing phases formed in the process under equilibrium condition were calculated by FactSage 6.2 thermodynamic package. Fluoride distributions were determined to establish an F-balance among the input and output materials. Besides, slag samples from a magnesium plant were also characterized, including leaching test according to EN 12457-2.
Based on these results, fluoride impacts on the environment were evaluated and discussed. Suggestions were also presented to minimize the environmental impacts from primary Mg production using the Pidgeon process.
Datummar 2012
StatusPublicerad - mar 2012


KonferensInternational Conference on Solid Waste Technology and Management

Evenemang (konferens etc.)

International Conference on Solid Waste Technology and Management

mar. 11 2012 - mar. 14 2012

Philadelphia, USA

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