Investigation of vanadium compounds in ashes from a CFBC firing 100% petroleum coke

An ash sample from a CFBC boiler burning petroleum coke has been examined using a variety of chemical and physical techniques both before and after phase separation. In the original sample, preliminary XRD work provided tentative evidence of one V compound. However, more detailed results were obtained from an enriched sample, and also from a sample with CaSO4 removed. These enriched samples were examined again by XRD using longer data acquisition times, resulting in scans collected over 3 days. This approach yielded XRD data with markedly improved signal-to-noise ratio. Low-abundance phases could be identified and they included a vanadium-based compound: calcium vanadium oxide hydrate (Ca2V2O7.2H(2)O). One sample underwent a waste extraction test (WET). The sample showed very little change apart from the expected hydration of CaO to Ca(OH)(2). Vanadium was still present as calcium vanadium oxides, albeit different ones from the bulk sample. Vanadium was also shown to have a negligible solubility in the WET process, with only 0.013% of the total vanadium being extracted.