Process for expanded use of a kraft pulper for phosphorus refining with extended recovery

Abstract

The invention relates to a process for removing a phosphorus-rich lime product from a kraft pulping process, where at least one waste stream, or at least part of a waste stream, containing phosphorus from the kraft pulping process is purified, yielding a fraction of purified water and phosphorus-containing flocs. These dried phosphorus-containing flocs are added to the spent liquor recovery process, resulting in a phosphorus-containing lime sludge. Part of this sludge is removed as a phosphorus-rich lime product with a phosphorus content of at least 2 g / ton and a cadmium content relative to phosphorus in the product less than or equal to 100 g Cd / ton of P. Furthermore, a fertilizer product is provided, comprising the phosphorus-rich lime product as a phosphorus component.