Virginia Chemicals Inc.

Karsten R Minzghor

Edwin D Little

Aqueous sodium dithionite slurries or suspensions, which are nonsettling during shipment thereof and are thereafter pumpable after storage at 32.degree.-40.degree. F. for at least fourteen days, comprise, on a weight basis, about 34% of sodium dithionite, about 0.17% of a xanthan gum, 5.5-6.5% of 50% sodium hydroxide, about 0.26% of a chelate, and about 1.96% of sodium tripolyphosphate which is added after adding the sodium dithionite. Preferably, the sodium tripolyphosphate is added last in making the slurry which is used as a woodpulp bleaching composition.

Method of preparing reproducibly stable aqueous suspensions of sodium

Aqueous sodium dithionite slurries, which are non-settling during shipment thereof and are thereafter pumpable, and a method for their manufacture are provided. The slurries contain at least 25% by weight of crystalline pure sodium dithionite and at least about 0.13% by weight of a xanthan gum. As textile bleaching compositions, the slurries comprise, on a weight basis, at least about 36% of commercial sodium dithionite, at least about 3% of sodium hydroxide, at least about 0.25% of a chelate, and at least about 0.25% of a xanthan gum. As woodpulp bleaching compositions, the slurries comprise, on a weight basis, about 28% of commercial sodium dithionite, at least about 2% of sodium carbonate, at least about 2% of sodium tripolyphosphate, and at least about 0.13% of a xanthan gum.

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Portsmouth, VA, United States of America

Karsten R Minzghor