Process for preparing sodium formaldehyde sulfoxylate

摘要

Zinc dust is mixed with water and added with soluble cadmium salt, whereupon at room temperature to 45.degree. C adds SOi2 and removed after the reduction is treated with formaldehyde, whereupon, after the disproportionation, the second time with added zinc dust and a second reduction, added with sodium hydroxide and finally the usual finishing of the product. Sul dvojmocnéhokadmia was added in an amount of 0.03 to 0.08, optimally from 0.035 to 0.045 g of cadmium per 100 g of zinc dust, based on the weight of zinc powder in the starting aqueous slurry, and it is preferably a sulphate, chloride, acetate or cadmium. Preferably a zinc powder containing less than 96 wt%. kovovéhozinku, of dp 9-20 .mi.ma retained on a 0.06 mm at most 0.5 wt%.