Experimental study on supercritical phenomena of WO_3 solubility in NaCl-H_2O system

摘要

The solubility measurements of WO_3 in NaCl-H_2O system with 4.0% by weight salt were carried out to study the supercritical phenomena of solubility. These experiments were carried out using rapid-quench pressure vessels, with quantitative Na_2WO_4·2H_2O, HCl, NaCl and H_2O in Pt capsule to determine the solubility of WO_3 from supersaturated solution. The pressure was kept at 34 MPa, which was near the critical pressure 31.4 MPa and the temperatures varied from 250℃ to 550℃. The experimental results indicate that the solubility of WO_3 has the features of supercritical phenomenon in critical region and is sensitive to the change of system temperature and solvent density. The temperature and pressure in this experiment are close to those of ore-forming fluids in many tungsten deposits, so the features of supercritical geofluids can be helpful to investigating the ore-forming mechanism of tungsten deposit.