Crust Elution-deposited Rare Earth Ore Research Articles

Leaching process of rare earths from weathered crust elution-deposited rare earth ore

In order to strengthen the leaching procedure, the chemical processes of leaching rare earths (RE) from the weathered crust elution-deposited rare earth ore were investigated frow the viewpoints of kinetics, hydrodynamic and mass transfer. The results show that the leaching hydrodynamics follows the Darcy law. The leaching kinetics can be described by the shrinking core model; the leaching process is controlled by diffusion of porous solid layer; and the mass transfer can be described with Van Deemter equation. This provides a theoretic basis and a scientific approach with high efficiency and optimized extraction conditions in industrial practice.

Optimisation of mass transfer in column elution of rare earths from low grade weathered crust elution-deposited rare earth ore

An investigation was carried out to optimize the leaching and mass transfer of rare earth metals with ammonium sulfate solution during the column elution of a low grade weathered crust elution-deposited rare earth ore. The effects of flow rate, concentration of leach reagent and ore grade on the leaching performance were examined. The experimental data was analyzed using chromatographic non-equilibrium plate theory in order to elucidate the mass transfer phenomena. It was found that the relationship between the height equivalent to a theoretical plate (HETP) and the leaching flow rate can be described by the Van Deemter equation and there is an optimum flow rate in the leaching process. Compared with similar higher grade ores which have a sharp peak followed by a short tail, the leach curve of low grade ores has a long tail following a broader peak.

Kinetics on leaching rare earth from the weathered crust elution-deposited rare earth ores with ammonium sulfate solution

In this paper, the kinetic of leaching rare earth from the weathered crust elution-deposited rare earth ores with ammonium sulfate solution was investigated. The effects of the main leaching parameters such as temperature and ore particle size on leaching process were examined and discussed in order to elucidate the kinetics and mechanism of leaching rare earth. It was found that the higher the leaching temperature or the smaller the ore particle size, the faster the leaching progress. The leaching mechanism was analyzed with different kinetics models. The results show that the leaching process can be described by the shrinking-core model, the leaching rate was controlled by the inner diffusion of reactants and leaching products through mineral porous layer, the leaching process follows the kinetic model 1 − 2/3 α − (1 − α) 2/3 = kt, the apparent activation energy was 9.24 kJ/mol obtained from calculating the experimental data and the order of the ore particle size found to be approximately 2. An empirical equation relating the rare earth leached rate constant with ore particle size and leaching temperature was established as 1 – 2 / 3 α – ( 1 – α ) 2 / 3 = 1 . 5 0 ⋅ r 0 − 2 ⋅ e 9240 R T ⋅ t .