Method for removing iron and preparing green vanadium and iron-based pigment by using titanium white waste acid

The invention provides a method for removing iron and preparing green vanadium and an iron-based pigment by using titanium white waste acid. The method comprises the following steps: using titanium dioxide waste acid for carrying out acid leaching treatment on the titanium gypsum, so as to make iron in the titanium dioxide gypsum enriched in the titanium dioxide waste acid, and performing solid-liquid separation to obtain an iron-enriched acid leaching solution and a solid substance; circularly carrying out acid leaching treatment on the obtained acid leaching solution, and carrying out acid leaching treatment on new titanium gypsum by using the acid leaching solution obtained in each time of acid leaching treatment until iron impurities in the acid leaching solution are saturated; then treating the obtained iron saturated acid leaching solution and the solid in two ways: carrying out drying and crystal transformation treatment on the solid to obtain the high-strength alpha-type semi-hydrated gypsum which can