Soap Separation-A New Option for Removal of NPEs

摘要

Non-process elements(NPEs)are elements present in the process streams without taking part in the desired reaction.With increasing process closure and new NPE-rich input streams such as gasified bark in the lime kiln and the destruction of biosludge in the recovery boiler,the traditional purge points may prove insufficient.A new method to remove NPEs is suggested: removal of NPEs from tall oil brine.The idea is based on the fact that many elements are enriched in the soap and separated from the black liquor but are later led back to the black liquor with the brine.The results showed strong enrichment of Ba,Ca,Mg,Mn,P and Zn in soap;an enrichment factor of 8 or higher was observed.Laboratory experiments where tall oil brine has been alkalized and subjected to a separation stage have been conducted.The laboratory experiments showed that more than 90% of Al,Ba,Mg,Mn and P precipitates and could be removed with the solid phase if alkalized to pH 11.The separation efficiency varied for Ca and Si from 70-85 %.To conclude,removal of non-process elements from tall oil brine is a promising new kidney,especially for P and Si.