研究目的
The determination of mineral species of mineralogical rocks in the copper mining industry is an important and complex task. The validation of geological models and the optimization of mineral processing chains depend on mineral characterization. This process must include the identification of mineral species and their classification by composition, in addition to extensive chemical analysis.
研究成果
The main result of this work is the direct identification of seven sulfur mineral species contained in mineralogical rocks by using LIBS and chemometric methods. The supervised methods show improved classification in the ascending order viz., PLS-DA, KNN, SIMCA and ANN, in terms of accuracy. A relevant achievement is the correct identification of very similar species in terms of their elemental composition such as bornite/chalcopyrite and chalcocite/covellite. Finally, it is a natural step to translate all these methodologies for real time mineral analysis and in situ geological exploration.
研究不足
The study focuses on sulfide rocks relevant to the copper industry, which may limit its applicability to other types of minerals or industries. The robustness of the models was tested with known and unknown samples, but the performance may vary with samples from different geographical locations or with different elemental compositions.
1：Experimental Design and Method Selection:
The study utilized laser induced breakdown spectroscopy (LIBS) for the direct identification of mineral species in raw rocks. Unsupervised multivariate methods like PCA and dendrogram analysis, and supervised pattern recognition techniques such as SIMCA, PLS-DA, KNN, decision tree analysis, and ANNs were compared.
2：Sample Selection and Data Sources:
A total of 162 sulfide rocks with mineralogical relevance in the copper industry were analyzed. These contained bornite, chalcocite, chalcopyrite, covellite, enargite, molybdenite, and pyrite. The samples were collected from different mining locations to account for sample variability.
3：List of Experimental Equipment and Materials:
The LIBS setup included a fourth harmonic of a Nd:YAG laser at 266 nm, a coaxial-confocal optical coupling system, and an Aurora spectrometer operated by 6 channels between 185.36 and 1049.36 nm.
4：36 and 36 nm.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The minerals in the rocks were analyzed using LIBS without any sample pretreatment. The measurements were carried out at five different point locations on each rock sample and 35 laser shot spectra were recorded in each sample point.
5：Data Analysis Methods:
The data were processed mathematically by eliminating outliers, using correlation distance analysis to obtain an average spectrum for each sample. PCA, SIMCA, PLS-DA, KNN, and ANN were used for data analysis.
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