Sepg. zinc from pyrolusite by washing with dil. mineral acid - also giving manganese di:oxide useful in pigment, oxidant and ferrite mfr. and e.g. zinc sulphate

摘要

Sepn. of Zn from pyrolusite (I) (MnO2) contg. Zn is effected by treating (I) with dil. mineral acid (II) and sepg. a soln. contg. Zn and (I) contg. little Zn. (I) is pref. obtd. by sepg. Mn from Zn salt solns. (II) is HNO3, HCl, H3PO4 or esp. H2SO4, pref. with a concn. of 1-5 (wt.)%. USE/ADVANTAGE - The process gives Zn salt solns. contg. less than 10, pref. less than 1 mg/l Mn, which is recycled to the pure Zn liquor obtd. in the sepn. of Mn; and a (I) filter cake contg. less than 2, pref. less than 1% Zn, which is used as starting material for the prodn. of pigments, for pigmenting clay tiles, as oxidant in chemical processes and for the mfr. of ferrites contg. Mn (all claimed). A high Mn content is harmful in ZnSO4 used for making pigments and electrolytic Zn, whilst contamination with Zn makes (I) unsuitable for pigment mfr. or as oxidant in chemical processes. The process is useful for purifying (I) recovered from scrap batteries. The use of dil. acid and treatment at room temp. makes the process more economical than usual.