Laboratory corrosion studies were carried out in green, white, and black liquors from a pulp and paper mill in the Northwestern US. The corrosion potential behavior and corrosion rates of carbon steel, stainless steel, and cast irons were determined at the service temperatures of the equipment from which the liquors were sampled, including storage tanks, evaporators, and concentrators. Both low-and high-silicon content carbon steels were found to be spontaneously active and had unacceptably high corrosion rates in the green liquor, white liquor, and strong black liquor. Carbon steels were spontaneously passive in the weak black liquor and also tended to passivate in the intermediate black liquor. Nickel-alloyed cast irons used for valves in the evaporators had corrosion behavior similar to or poorer than the carbon steels. Stainless steels such as type 304L austenitic stainless steel and type 2205 duplex stainless steel were found to have excellent resistance to corrosion in all the alkaline pulping liquors.

Subject
Materials, Hydroxides, Corrosion rate, Liquor, Solids, Pulping, Black liquors, Steel, Cast iron, Carbon steel, Duplex stainless steel, Stainless steel, Corrosion potential
Keywords:
black liquor, corrosion testing, digesters, evaporators, green liquor, storage tanks, white liquor
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2004
Association for Materials Protection and Performance (AMPP)
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