Alternative Alkalis in Peroxide Bleaching of Mechanical Pulp, 2007 International Mechanical Pulping Conference

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Suitability of Magnesium Hydroxide, Magnesium Oxide, Calcium Hydroxide and Calcium Oxide as Sodium Hydroxide-replacing alkali in oxidizing hydrogen peroxide bleaching of mechanical pulp was studied. In the first stage, bleaching experiments of laboratory scale were carried out both using Sodium Silicate stabilizer and without it in medium consistency (10%). It was found that the most suitable alternative alkali is Magnesium Hydroxide, which needed no Sodium Silicate-stabilisation to achieve maximum brightness result of 77.0%-ISO whereas NaOH with Sodium Silicate gave 78.4%-ISO.