The extraction of tungsten from scheelite was carried out using a sulfuric acid solution with oxalic acid as the chelating agent. Tungsten was obtained in the form of highly soluble hydrogen aqua oxalato tungstate (H₂[WO₃(C₂O₄)·H₂O]) during the leaching process, while calcium remained in the residue as calcium sulfate dihydrate (CaSO₄·2H₂O). About 99.2% of the tungsten was leached at 70 °C, 1.5 mol/L sulfuric acid, 1 mol/L oxalic acid, a liquid/solid ratio of 25:1 (mL/g), an oxalic acid to sulfuric acid molar ratio of 1:1, a stirring speed of 300 r/min and a leaching time of 2 h. H₂[WO₃(C₂O₄)·H₂O] was thermally decomposed into tungstic acid (H₂WO₄), and tungsten trioxide (WO₃) was directly produced by calcining H₂WO₄ at 700 °C for 2 h. The surface chemical reaction was determined to be the controlling step during tungsten leaching, and the apparent activation energy was calculated to be 51.43 kJ/mol.