Express Assessment of Apatite Content in Apatite–Nepheline Ores of Ultrabasic Alkaline Complexes Based on Its Luminescent Properties (The First Study Stage)

Abstract

The article presents the results of the first study stage aimed at analyzing the luminescent properties of the main and minor minerals composing the apatite–nepheline ores and host rocks in the deposits of the Khibiny rock massif (Kola Peninsula, Russia). The main purpose of the work was a search of a stable identification feature providing fast and safe determination of fluorapatite in the mineral mixture of apatite–nepheline ores and solving technological tasks, namely sampling the borehole walls in open pits. The first stage includes studies carried out on pure mono-fractions of four minerals occurring in fluorapatite deposits and possessing obvious luminescent properties: fluorapatite, nepheline, calcite, and sodalite. The authors have revealed luminescence spectra of these minerals and established correlation of their spectral characteristics with the literature data and their consistency. However, the high intensity of sodalite luminescence in a wide band can complicate identification of fluorapatite by the luminescence spectrum in many cases. Therefore, it is reasonable to use the color and intensity of luminescence rather than spectral characteristics.

Hardware and Software Solutions for the Generation of a Database of HSV-Color Characteristics for the Main Ores and Rocks of the Khibiny Massif

“…It is worth mentioning the convergence of the previously obtained results for the study of the color indicators on the monomineral fractions [1] and HSV-color characteristics of the minerals occurring on the surface of the core samples. The surfaces of the flat core halves were not subject to pre-treatment.…”

“…Nepheline reflects emission at the boundary of the visible light range, capturing the border areas of the ultraviolet range and the violet region of the visible light range, while apatite absorbs part of this range and contributes to the color characteristics with its fluorescence. The availability of narrow bands with maxima of 568 nm and 581 nm, 602 nm and 608 nm, and 648 nm in the luminescence spectra of apatite presented in [1] and their absence in nepheline provide a shift in the color palette of minerals from the blue-green region of the visible light range for nepheline to pink-violet for apatite.…”

“…This article flows from an earlier published study [1] aimed at the development of an efficient and quick method of identifying apatite in the apatite-nepheline ores (or the ANO) of the Khibiny deposits (Kola Peninsula, Russia) and thereupon predicting the P 2 O 5 content. The executed investigation confirms the ability of apatite to luminesce by a UV light source with a maximum wavelength of 365 nm [2][3][4][5][6] and evaluates the flow spectra of a series of luminescent minerals composing the ANO and host rocks of the Khibiny deposits such as nepheline, sodalite, a product of nepheline alteration, and calcite.…”

“…As a result, it will help in identifying parameters for reliable (fault-free or high-precision) apatite detection in the ANO or apatite-bearing rocks when investigating the surface of the blasting borehole walls. The relevance and necessity of making changes to the existing approaches to retrieve information about the distribution of a valuable component in the block being prepared for stripping is described in [1]. A comparative evaluation of the quantitative and qualitative indicators for the drilling block models was executed to find a strategy for the ore flow quality management and demonstrated, in most cases, a discrepancy between the planned and actual indicators.…”