Process and facility for removing metal contaminants from fertilizer streams

摘要

A process and system for producing fertilizers with reduced levels of contaminants, and particularly a flue gas scrubbing process and facility that produce a fertilizer byproduct which is treated to remove heavy metals originally present in the scrubbed flue gas. The process entails contacting a flue gas with a scrubbing solution to remove acidic gases and produce a byproduct containing a fertilizer compound precipitate and dissolved metals and/or metal compounds. A fertilizer solution containing dissolved fertilizer and dissolved metals and/or metal compounds is then produced by adding water to the byproduct, after which the pH of the fertilizer solution is adjusted one or more times with a gaseous and/or liquid alkali to form precipitates of one or more metal species. The precipitates are then removed from the fertilizer solution and the solution dewatered to yield a fertilizer product with lower contaminant levels.