Method for separating and extracting vanadium and chromium from vanadium and chromium reduction slag

The invention discloses a method for separating and extracting vanadium and chromium from vanadium and chromium reduction slag. The method includes the steps that firstly, acid leaching liquid is obtained by conducting filtering after the vanadium and chromium reduction slag is leached with acid liquid, wherein the H+ concentration of the acid liquid ranges from 2 mol/L to 10 mol/L; secondly, an oxidizing agent is put in the acid leaching liquid to conduct the oxidation reaction, and oxidized liquid is obtained, wherein the oxidizing agent is at least one of an Mn(III) compound and an Mn(IV) compound; thirdly, the pH value of the oxidized liquid is regulated to be 1.5 to 2.5 or is regulated to be 1.5 to 3.5 after ammonium salt is added, filtering is conducted after stirring and precipitating, and vanadium pentoxide is obtained after a filter cake is subjected to calcination processing; and fourthly, the pH value of filtrate obtained through filtering in the third step is regulated to be 4.0 to 7.0, filtering