The invention relates to a method for synchronously recovering
vanadium and
chromium from
vanadium-
chromium slag by an acid process. The method comprises the steps: (1) carrying out water-washing desalting: washing water-soluble salts in the
vanadium-
chromium slag with water, filtrating so as to obtain a
filter cake and a washing solution, cyclically washing the washing solution with water, and finally precipitating salts through cooling
crystallization; (2) carrying out
oxidizing acid-dissolving: adding the
filter cake obtained in the step (1) into a
sulfuric acid solution for acid dissolving, and adding an
oxygen enrichment agent for closed
oxygen-enriched leaching during acid dissolving, so as to obtain a vanadium-chromium solution and
tailings; (3) carrying out purifying
impurity removal: adding a
calcium containing compound into the vanadium-chromium solution obtained in the step (2) for
impurity removal-desulfurization, so as to obtain a purified vanadium-chromium solution; (4) carrying out
calcification vanadium precipitating: adding a
calcification agent into the vanadium-chromium solution obtained in the step (3) for
calcification vanadium precipitating, so as to obtain
calcium vanadate and a vanadium precipitated solution; (5) carrying out hydrolyzing chromium precipitating: reducing the vanadium precipitated solution obtained in the step (4) through a
reducing agent, adding alkali to adjust the pH value of the solution to 7-9, precipitating to obtain chromic
hydroxide, and calcining to obtain a
chrome green product. According to the method provided by the invention, the consumption of additives is reduced, the production process is simplified, the production cost is reduced, and the clean and efficient utilization of the vanadium-chromium
slag is realized.