Solubility of Nb 2O 5 and leaching behaviors of Nb and Ta from niobite in KOH solution have been investigated in order to develop an alkali hydrothermal leaching process of Nb and Ta. The solubility of Nb 2O 5 was mea...Solubility of Nb 2O 5 and leaching behaviors of Nb and Ta from niobite in KOH solution have been investigated in order to develop an alkali hydrothermal leaching process of Nb and Ta. The solubility of Nb 2O 5 was measured in the range of 40 ℃ to 200 ℃ at various molar ratios of K 2O to Nb 2O 5 ( n (K 2O)/ n (Nb 2O 5)). It has been found that Nb 2O 5 shows the maximum solubility at the solution composition of n (K 2O)/ n (Nb 2O 5)=4/3 at a given temperature; the rise of temperature increases the solubility of Nb 2O 5 below 120 ℃, but decreases it above 120 ℃. The leaching behaviors of Nb and Ta were studied in the range of 150 ℃ to 250 ℃ and 0.1 MPa to 5 MPa. With the rise of temperature, the leaching degree increases when the leaching temperature is below 200 ℃, but it decreases when the leaching temperature is above 200 ℃. The maximum leaching degree is about 90% at 200 ℃. It was proved that the alkali hydrothermal leaching process is effective for the recovery of Nb and Ta from niobite concentrate.展开更多
文摘Solubility of Nb 2O 5 and leaching behaviors of Nb and Ta from niobite in KOH solution have been investigated in order to develop an alkali hydrothermal leaching process of Nb and Ta. The solubility of Nb 2O 5 was measured in the range of 40 ℃ to 200 ℃ at various molar ratios of K 2O to Nb 2O 5 ( n (K 2O)/ n (Nb 2O 5)). It has been found that Nb 2O 5 shows the maximum solubility at the solution composition of n (K 2O)/ n (Nb 2O 5)=4/3 at a given temperature; the rise of temperature increases the solubility of Nb 2O 5 below 120 ℃, but decreases it above 120 ℃. The leaching behaviors of Nb and Ta were studied in the range of 150 ℃ to 250 ℃ and 0.1 MPa to 5 MPa. With the rise of temperature, the leaching degree increases when the leaching temperature is below 200 ℃, but it decreases when the leaching temperature is above 200 ℃. The maximum leaching degree is about 90% at 200 ℃. It was proved that the alkali hydrothermal leaching process is effective for the recovery of Nb and Ta from niobite concentrate.
