Fate of Cu, Cr, and As During Combustion of Impregnated Wood with and without Peat Additive
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- 作者：Karin Lundholm ; Dan Boströ ; m ; Anders Nordin ; Andrei Shchukarev
- 刊名：Environmental Science & Technology
- 出版年：2007
- 出版时间：September 15, 2007
- 年：2007
- 卷：41
- 期：18
- 页码：6534 - 6540
- 全文大小：341K
- 年卷期：v.41,no.18(September 15, 2007)
- ISSN：1520-5851
文摘
The EU Directive on incineration of waste regulates theharmful emissions of particles and twelve toxic elements,including copper, chromium, and arsenic. More informationis critically needed on the speciation and behavior of thesetrace elements during combustion, including the effectsof different process variables, as well as of different fuelsand fuel mixtures. Using a 15 kW pellets-fueled grateburner, experiments were performed to determine the fateof copper, chromium, and arsenic during combustion ofchromate copper arsenate (CCA) preservative wood. Theeffects of co-combustion of CCA-wood with peat were alsostudied since peat fuels previously have proved togenerally reduce ash related problems. The fate andspeciation of copper, chromium, and arsenic were determinedfrom analysis of the flue gas particles and the bottomash using SEM-EDS, XRD, XPS, and ICP-AES. In addition,chemical equilibrium model calculations were performedto interpret the experimental findings. The results revealedthat about 5% copper, 15% chromium, and 60% arsenicwere volatilized during combustion of pure CCA-wood, whichis lower than predicted volatilization from the individualarsenic, chromium, and copper oxides. This is explained bythe formation of more stable refractory complex oxidephases for which the stability trends and patterns arepresented. When co-combusted with peat, an additionalstabilization of these phases was obtained and thus a smallbut noteworthy decrease in volatilization of all threeelements was observed. The major identified phasesfor all fuels were CuCrO2(s), (Fe,Mg,Cu)(Cr,Fe,Al)O4(s),Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified inthe fine particles as KH2AsO4(s) and As2O3(s). A strongindication of hexavalent chromium in the form of K2CrO4or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2was found in the fine particles. Good qualitative agreementwas observed between experimental data and chemicalequilibrium model calculations.