Materials for high-temperature and high-pressure hydrogen peroxide bleaching equipment
To determine the suitability of grade 705 zirconium (UNS R60705) as a candidate material of construction for high-temperature and pressure hydrogen peroxide (P{sub HT}) pulp-bleaching reactors, a series of electrochemical experiments were carried out in simulated P{sub HT} environments. Because the P{sub HT} process may be incorporated into a closed cycle mill or a mill that also uses chlorine-based chemicals to bleach pulp, the effect of chloride ion concentration on the corrosion of zirconium in P{sub HT} environments was studied. It was found that at the potential measured in P{sub HT} environments, zirconium was passive ({minus}100 mV vs. saturated calomel electrode [SCE]). Breakdown potentials of {approximately}500 mV{sub SCE} were measured in chloride-containing solutions. However, when the chloride ion concentration was increased >50 ppm, the repassivation potential of the zirconium was reduced significantly. Based on these results, grade 705 zirconium was determined to be suitable for a wide range of P{sub HT} process conditions.
- Research Organization:
- Pulp and Paper Research Inst. of Canada, Vancouver, BC (CA)
- OSTI ID:
- 20013152
- Journal Information:
- Corrosion (Houston), Journal Name: Corrosion (Houston) Journal Issue: 7 Vol. 55; ISSN 0010-9312; ISSN CORRAK
- Country of Publication:
- United States
- Language:
- English
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