Acid and Thermal Activation of Clay Separated from Kaoline for Uranium Purification

G. Maldybayev — 2026-04-02

Clay minerals are commonly used as adsorbents due to their wide availability, large specific surface area, and cation exchange capabilities, making them suitable for removing heavy metal ions from wastewater. This study investigated the activation of clay by acid and thermal treatment to obtain an adsorbent for the purification of uranium from impurities such as iron and magnesium. Acid modification of clay samples was carried out with sulfuric acid (15%) at a temperature of 80–90 °C for 3 hours. While the activation of the clay using the thermal process was performed at 600–650 °C for 12–24 hours. X-Ray Diffraction, Electron Paramagnetic Resonance (EPR), and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyse the clay's chemical composition and structural changes before and after activation. FTIR identified free OH groups and hydrated SiO2. EPR showed a high level of paramagnetic centers linked to structural defects and oxygen vacancies, which contribute to the material's strong adsorption and catalytic activity. After acid treatment, the clay particles exhibited a notable rise in specific surface area, expanding from 35.2 m²/g to 342.5 m²/g. Additionally, the specific pore volume grew substantially, increasing from 0.024 cm³/g to 0.30 cm³/g.

Purification of metallic ions from technological solutions before sorption recovery of rhenium under JSC Almalyk MMC

Kh.M. Azizova — 2026-04-08

In this article, rhenium’s distinct physicochemical characteristics, which make it essential for petrochemistry, electrical technology, rocket and aviation engineering, and the manufacturing of catalysts and high-precision tools, account for the metal's rising demand. The main source of rhenium at JSC "Almalyk MMC" is the off-gases produced when molybdenum concentrates are roasted, where rhenium is mostly found as Re2O7. High selectivity and overall efficiency are ensured by optimizing the process parameters at each of the multiple subsequent technical phases involved in rhenium recovery. Perrhenate sorption is less efficient when organic molecules and Mn²⁺ and Cu²⁺ ions are present in the process fluids. Oxidative-precipitation techniques were used for the first purification: Mn ions were oxidized and precipitated using potassium permanganate, and Cu2+ ions were selectively precipitated using an ammonium sulfide solution (NH4)2S. ICP-OES was used to assess the composition of the solutions, while SEM and EDS were used to examine the roasting gas-dust products. Using contemporary analytical methods, a thorough investigation of the applicable phases of selective purification was conducted for the first time under the circumstances of JSC "Almalyk MMC." It was shown that treating the solutions with KMnO4 and (NH4)2S efficiently eliminates interfering elements without causing rhenium and molybdenum losses, resulting in ideal circumstances for the sorption of perrhenate ions later on. Manganese and copper concentrations dropped from 1.44 to 0.0039 and 2.68 to 0.0036 g/l, respectively, demonstrating the great purification process efficiency. Rhenium and molybdenum concentrations did not alter during these phases, suggesting that they were fully preserved.

Kompleksnoe Ispolzovanie Mineralnogo Syra = Complex use of mineral resources

Acid and Thermal Activation of Clay Separated from Kaoline for Uranium Purification

Purification of metallic ions from technological solutions before sorption recovery of rhenium under JSC Almalyk MMC