Search Results (4)

Spodumene is a characteristic mineral in lithium-rich granitic pegmatites, serving both as a valuable mineral resource and an important gem material. This study incorporates three different color varieties of spodumene—pink to violet, yellow-green, and colorless—into a unified research framework. X-ray powder diffraction (XRD), electron probe microanalyzer (EPMA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), and photoluminescence spectroscopy (PL) were employed to systematically analyze the chemical composition, crystal structure, and spectroscopic properties of spodumene. Furthermore, the coloration mechanism and fluorescence emission of the different color samples were investigated and analyzed. The results indicate that the presence and mixed valence states of the transition metals Fe and Mn primarily influence the color and photoluminescence of the three types of spodumene. Mn³⁺ is the primary color-causing element in pink to violet spodumene, while Fe³⁺ is the primary color-causing element in yellow-green spodumene. Photoluminescence in all three color varieties is dominated by Mn²⁺. These findings contribute to a deeper understanding of the color and luminescence mechanisms of spodumene, expanding its potential applications as both a gem material and a luminescent material. Full article

This study investigates the activation behavior and mechanism of calcium ions on the flotation of spodumene with different colors. Using NaOL as a collector, in descending order of flotation recoveries were purple, pink, and white spodumene, while in the presence of CaCl₂, the flotation recoveries were increased and the order was pink, white, and purple spodumene. The zeta potential, adsorption amount, contact angle, and AFM measurements demonstrated that calcium ions adsorbed on the spodumene surface and promoted NaOL adsorption in alkaline conditions. Species distribution analysis showed that Ca²⁺, Ca(OH)⁺, and Ca(OH)₂ were essential components that play an activation role at pH = 12. The adsorption capacity and XPS results illustrated that CaCl₂ activated spodumene flotation in two ways. One possibility involves calcium ions and their hydroxyl compounds being adsorbed on the spodumene surface, where Ca and Al sites favored OL⁻ adsorption. The other possible way involves calcium ions and their hydroxyl compounds forming complexes with NaOL firstly in solution and then co-adsorbing on the spodumene surface. Quantum chemical calculations showed that the adsorption affinity on the spodumene surface in descending order was Ca²⁺, Ca(OH)₂, and Ca(OH)⁺, and the pink spodumene was most preferably adsorbed, followed by the white spodumene, also consistent the flotation results. Full article

Lithium-bearing polymetallic pegmatite ores are an important raw material for lithium extraction. They contain not only lithium but also other associated elements such as beryllium, tantalum, and niobium, with great recovery values. It is therefore often called lithium-bearing polymetallic pegmatite ore (LPPO). The recovery and utilization of Be-bearing minerals in LPPOs have yet to be further studied. This paper briefly expounds the geological aspects of LPPO deposits in China and Chinese experiences on the beneficiation of LPPOs, with special emphasis on the flotation separation of lithium-beryllium minerals. In LPPO, spodumene is the main target mineral for lithium, while beryl is the main Be-bearing mineral in a fine-grained embedded state. If the BeO grade of LPPO is greater than the industrial grade (BeO ≥ 0.04%), it will be processed for recovery. Tantalum and niobium minerals are mainly in the form of tantalite, columbite, or ferrotapiolite, which may be recovered by gravity separation or magnetic separation. Gangue minerals are mainly composed of albite and quartz. Currently, the most commonly used methods for separating the target minerals from gangue are dense medium separation and flotation. The manual sorting method has become obsolete and is expected to be replaced by machine sorting methods such as color sorters and X-ray transmission sorters. Flotation is the main method for the separation of fine-grained beryl and spodumene. The success of flotation depends on the selection of suitable pretreatment methods and appropriate flotation reagents for altering the surface properties of spodumene and beryl and for expanding the floatability differences between spodumene and beryl and between spodumene and gangue. Full article

Kunzite, the pink variety of spodumene is famous and desirable among gemstone lovers. Due to its tenebrescent properties, kunzite always remains a hot research candidate among physicists and mineralogists. The present work is continuing the effort towards value addition to kunzite by enhancing its color using different treatments. Before color enhancement, it is essential to identify the chromophores and their oxidation states. In this paper, the authors investigated the main impurities in natural kunzite from the Nuristan area in Afghanistan and their valence states. Some impurities in the LiAlSi₂O₆ spodumene structure were identified and quantified by using sensitive techniques, including Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), UV−VIS and X-ray absorption near-edge structure (XANES). LA-ICP-MS indicated many trace elements as impurities in kunzite, among which Fe and Mn are the main elements responsible for coloration. The oxidation states of these two transition elements were determined by the XANES technique. The study reveals that Mn is present in both Mn²⁺ and Mn³⁺ oxidation states, while Fe is present only in Fe³⁺ oxidation state. Full article