| Popis: |
Introduction: The aim of this article was to determine methods to overcome the existing problems of implementing new technologies for the extraction of noble metals from black shale ores. The main ones are: 1) a profound study of black shales in terms of their origin, nature, and forms of carbon presence; 2) studying the mineral forms of noble metals at the nanoscale; 3) natural conditions for the self-organisation (self-assembly) of noble metal nanostructures; 4) modelling of the natural conditions of self-assembly, and 5) the search for effective methods of developing nano-sized particles of precious metals and their compounds. The authors analysed the existing perspectives based on the concept of “black shales”, their origin, sedimentation conditions, geodynamic conditions of formation, and nature and forms of carbonaceous matter present in them. The reasons for the increased noble metal ore potential of black shale formations were considered in detail. Methodology: the study of nanoscale noble metals was carried out on a Swiss-made X-ray diffractometer using a huge database (up to 453,000 definitions) and appropriate software. The article provides data on the existing mineral forms of noble metals, including the nanoscale state according to the literature and original data, obtained during the study of ores of the Sukhoi Log-type deposits in Russia and Kazakhstan. The role of nanostructured ore matter in such types of deposits was shown. Reasons were indicated for both the under-extraction of Au and the complete “disregard” of platinum group metals during the development of deposits. Results and discussion: The natural processes of crust formation (for black shales), leading to the self-assembly of noble metals, were considered. Examples are given when alluvial metal sources are formed from negligible Au contents in parent rocks as a result of crust-forming processes. We believe that the issue of the involvement of the ore potential of platinum group metals in industrial production may be resolved by the use of nature-like technologies. Their theoretical and practical foundations were laid several decades ago by a group of scientists from Kazakhstan. The technologies of the future should be based on the processes of super-grinding and the transfer of particles of noble metals into a state of self-assembly. Self-assembly is possible only for “native” particles with no valence bonds. Conclusions: To process ores with a high carbon content, we need to find the most effective ways to eliminate active carbon for the technologies of the future, and one of the methods of its neutralization is hydrogenation. With the introduction of new technologies, it will be possible not only to increase the recovery of Au from primary ores, but also to involve in the re-extraction the processing tailings accumulated by existing enterprises. In conclusion, the most important observations were provided regarding the noble metal potential of black shale and future extraction technologies, including: 1) the positive and negative roles of carbon were determined; 2) the importance of studying black shale weathering crusts as natural self-assembly “factories” was shown; 3) on the basis of clause 2, methods for the complex extraction of noble metals were outlined, which are based on cavitation. |
