Kinetics of Sulfuric-Acid Nickel Leaching from the Grinding Wastes of Rhenium-Containing Superalloys

Kinetics and Optimization of Metal Leaching from Heat-Resistant Nickel Alloy Solid Wastes

“…99.9 99.9 99.9 15 99.9 75 99.9 8 ---For example, chromium, cobalt, aluminum, titanium, and iron were leached ficiently, while rhenium practically remained undissolved. It can be noted that w parable amounts of iron and rhenium in the initial powder, when leached with acid, rhenium passed into the solution at a concentration 20 times lower than i cording to the literature data [6], indeed, as a result of the treatment of the al sulfuric acid at a temperature of 85 °C, the leaching of rhenium into the solution From the data obtained, it can be seen that when solutions were heated from room temperature to 70 • C for the first 6 h, the nickel concentration in the solution increased from 2-3 g/L to 30-50 g/L (at the same time, Ni leaching efficiency was 46.9-78.1%). An increase in temperature to 100 • C increased the concentration of nickel ions in solution to 56 g/L in the first 4 h from the start of dissolution; in 6 h of contact, the concentration of nickel ions reaches 64 g/L.…”

“…It can be noted that with comparable amounts of iron and rhenium in the initial powder, when leached with sulfuric acid, rhenium passed into the solution at a concentration 20 times lower than iron. According to the literature data [ 6 ], indeed, as a result of the treatment of the alloy with sulfuric acid at a temperature of 85 °C, the leaching of rhenium into the solution did not exceed 5%. For effective leaching of rhenium, it is necessary to carry out electrochemical dissolution of the grinding waste, while the efficiency of rhenium extraction into solution reaches about 80% [ 28 ], or use oxidants such as chlorine, in which case the degree of rhenium extraction increases to 90% [ 29 ].…”

“…Along with cobalt, molybdenum, and aluminum, the heat-resistant nickel alloy contains other valuable and refractory metals, such as tungsten, niobium, and rhenium. The approximate composition of nickel alloy (wt.%) is as follows: Cr, 4.9–5.0; Co, 9–9.3; Mo, 1–1.1; W, 8.5; Al, 5.9–6.0; Ta, 4.0; Nb, 1.6; Re, 4.0; Ni, 57.4–60 [ 5 , 6 ].…”

“…Nickel is soluble in mineral acid solutions only under certain conditions. The rate of its transition to a solution, regardless of the method of dissolution (chemical or electrochemical), increases with an increase in the temperature of the process and the concentration of acids to certain values at which its passivation is observed [ 6 ]. Due to the heterogeneity and differences in the chemical composition of waste heat-resistant alloys, passivation of the alloy surface during leaching and slowing down the process speed, as well as the not always possible adaptation of the literature data, the choice of methods, conditions for their opening, and further separation of the main components are determined experimentally for a specific waste.…”

Review: Rhenium and its smelting and recycling technologies

“…After pulverization of superalloy scraps, the superalloy powders are usually dissolved in aqueous solutions of HCl (with Cl 2 ( g )), 144,150–154 H 2 SO 4 155–158 or aqua regia, 159,160 followed by separation and purification through ion exchange and solvent extraction. The types of superalloy constituent elements leached into acids change depending on the types of the acid and oxidizing agent.…”