چكيده به لاتين
Nowadays, the extraction of rare earth elements (REEs) has become one of the active fields in industry due to their unique characteristics. Various methods are available for separating REEs from their containing sources, such as monazite. Alkali roasting is one of the processes related to the treatment of primary sources containing these elements. The goal of this process is to alter the structure of the raw material containing REEs, which in this research is monazite, in such a way that the phase components involved are more easily separated in later stages and impurities can be more easily removed. In this context, the study examines the parameters affecting the alkali roasting process, including the roasting temperature, roasting time, and flux-to-ore ratio. To enhance the efficiency of the alkali roasting process, optimization was performed. The effect of these parameters was investigated using the response surface method with 20 roasting experiments. The flux-to-ore ratio ranged from 0.8 to 1.2 by weight, the temperature ranged from 400 to 800°C, and the roasting time varied from 15 to 60 minutes. After completing these 20 experiments, the optimal conditions for the alkali roasting process of monazite ore were determined by modeling. The optimal conditions for this process were a roasting temperature of 800°C, a roasting time of 60 minutes, and a flux-to-ore ratio of 1. Under these conditions, the average efficiency of the alkali roasting process was 93%. After the alkali roasting stage, the solution was subjected to aqueous dissolution to remove the phosphate content. The solution was then filtered, and after filtration, its phosphorous content was titrated. The aqueous dissolution residue was sent to the acid dissolution stage. After the acid dissolution, the sample was filtered, and the solid was separated. The resulting solution was then subjected to solvent extraction. After the solvent extraction stage, the REEs were precipitated as oxalate solids using oxalic acid as the precipitating agent. The product was then calcined to remove oxalates, and the sodium content was eliminated by dissolution in water. Finally, after the removal of sodium, the rare earth oxide, including cerium oxide, was obtained.
