Removal of Chloride in the Kraft Chemical Recovery Cycle of Pulp Mills Using the Ion-Exchange Process

Abstract

High levels of chloride in the kraft recovery cycle of pulp mills can cause serious problems, particularly in recovery boiler operation. The treatment of ash collected from the electrostatic precipitator (ESP) for chloride removal was investigated experimentally using the ion-exchange process based on an amphoteric resin (BIORAD AG 11 A8). Saturation and regeneration experiments in a fixed bed were carried out for different flow rates. Experimental adsorption results obtained in the saturation step were well predicted with a mathematical model that takes into account dispersed plug flow for the bulk liquid, external mass-transfer resistance, intraparticle mass transfer by pore diffusion, and instantaneous equilibrium of adsorption at the pore/wall interface. The equilibrium was modeled using an extended Langmuir-Freundlich isotherm for three components (Cl -, SO 4 2-, and CO 3 2-) based on single-component equilibrium data. The resin performance was tested during cyclic operation, in which a chloride removal efficiency of higher than 89% was achieved, along with a sulfate recovery of 67-74%.

Comparison of adsorption equilibrium models for the study of CL−, NO3− and SO42− removal from aqueous solutions by an anion exchange resin

“…It can be achieved quantitatively and independently of the solution pH, and the ion exchange resins can be regenerated thus offering long effective lifetime [1,2,[8][9][10][11][12][13].…”

Technologies for Halide Removal in Water Treatment – A State-of-the-Art Review

“…Chloride would be released from ESP because chlorine is one of the process elements which enters the kraft pulping process with wood and other chemicals and will accumulate [98]. The boiler burns the black liquor containing organic and inorganic materials such as chloride [99]. Chloride concentration from the inland mill is 0.1-0.8% of the liquor dry solid, while for the coastal mill, chloride concentration could be as high as 3-5%, and in the closed process, chloride concentration could be even higher [99].…”

“…The boiler burns the black liquor containing organic and inorganic materials such as chloride [99]. Chloride concentration from the inland mill is 0.1-0.8% of the liquor dry solid, while for the coastal mill, chloride concentration could be as high as 3-5%, and in the closed process, chloride concentration could be even higher [99]. Mining water also could contain high chloride concentrations, depending on the geological location, dissolved metals, and deposit characterizations in contact with water.…”

Polyhydroxyalkanoate production by Bacillus thuringiensis: an aspect of biorefining pulp and paper mill sludge.

“…PPMS with low ash content has also been reported by Dabrowska et al (2018) who report on sludge with ash content ranging from 5.19-7.11%. The low ash content in the PPMS sample can also be attributed to efforts in precipitating and collecting CaCO3 and recycling it during the kraft process (Ferreira et al 2004 to the production and recovery of VFAs due to their potential to serve as renewable carbon sources, cheap precursors and a promising feedstock for PHA production (Kumar et al 2019;Szacherska et al 2021). The synthesis of PHAs using VFAs is considered to be an economical approach.…”