Separation, treatment and utilization of inorganic residues of chemical pulp mills

Abstract

a b s t r a c tThe major inorganic solid residues of chemical pulp mills include green liquor dregs, various lime residues, recovery boiler fly ash, and salt cake produced at the chlorine dioxide generator. Only a small proportion of these residues is currently utilized outside the mill area: landfill disposal and reuse at the mill are the most typically applied methods. The situation should be improved in the future for environmental and economical reasons. The focus of this review is on the separation of inorganic pulp mill residues to enhance the possibilities of their utilization. Solid-liquid separation operations, such as filtration and sedimentation, and the associated treatment processes, are described in close detail. The review aims at recognizing the most promising residues for utilization, as well as enhancing the understanding of the material balance of chemical pulp mills. The review also covers the most potential industrial applications for the utilization of residues, as well as the possibilities of using them as raw material in value-added products.

Inorganic Waste Generated in Kraft Pulp Mills: The Transition from Landfill to Industrial Applications

“…The concentration of K and P in BFA can be interesting for the production of fertilizers. The high LOI associated with these wastes is normally due to the decarbonation of calcite instead of organic matter, which generally is low [30].…”

“…As aforementioned, LM is formed in the causticizing reaction, and thus the main phase (more than 90%) is calcite [30], while some minor or trace phases may contain Mg, Si, Al, Fe, Na, K, P, and S, but normally not detected through XRD. Besides calcite, which is clearly identified in X-ray diffraction spectra, in the literature some minerals containing Ca and Mg carbonates have been identified (Ca (1−x) Mg x CO 3 ) [31].…”

Wastes from pulp and paper mills - a review of generation and recycling alternatives

“…In 2013, world paper production reached 403 Mt, while pulp production reached 179 Mt [5], with the USA, China, Canada, Brazil, Sweden, Finland, Japan, Russia, Indonesia and Chile being the top ten pulp producers [6]. Kinnarinen et al [7] estimate that waste production is most likely over one million metric tonnes per year. Currently, various inorganic and organic substances are generated in pulp and paper mills, such as ashes, green liquor dregs, slaker grits, lime mud and pulp mill sludge of waste water treatment plants (WWTP) [8,9].…”

Corrosion Behavior of Duplex and Lean Duplex Stainless Steels in Pulp Mill

“…The combustion of the strong black liquor converts the recovered inorganic chemicals to smelt which is dissolved in water to give the green liquor, which are mainly sodium carbonate (Na 2 CO 3 ), and sodium sulfide (Na 2 S) generated during the liquor recovery cycle. The green liquor is causticized to regenerate the white liquor [8][9][10][11][12][13] . The scheme of the main operation of the chemical recovery cycle is shown in Figure 1.…”