china pigment lithopone

Lithopone or sulphide of zinc white has been in general use for twenty years or more in many industries where a white pigment of considerable body or hiding power is required that is not subject to change like lead carbonate and has not the brittle character of zinc oxide, besides being sold at a lower figure than either of these. Nevertheless it is still comparatively new to the general painting trade. Because of our tariff protection its manufacture in this country has made great progress. Yet in spite of this and the duty imposed on it, the imports are still in excess of the quantity manufactured here. A short history of its origin will no doubt prove of interest to our readers.

...
...

 5公斤氟钠钠。 In the leaching step, each cubic meter of ammonia - ammonium sulfate solution was added 0. 3~0. 5kg sodium fluorosilicate. The purpose is to make the ammonia leaching reaction easier and more thorough. Adding an appropriate amount of sodium fluorosilicate can break the package of zinc-containing particles by a kind of ultrafine particles such as calcium hydroxide formed during the dissolution and conversion process of calcium sulfate in the ammonia solution. , the ultra-fine particles are layered and peeled off to achieve leaching.

...