Academician Melnikov Institute of Integrated Mineral Development – IPKON, Russian Academy of Sciences, Moscow, Russia:

G. P. Dvoichenkova, Leading Researcher, Candidate of Engineering Sciences, dvoigp@mail.ru
Yu. A. Podkamennyi, Engineer

A. S. Timofeev, Junior Researcher

Research and Exploration Works, ALROSA Group, Mirny, Russia:

O. E. Kovalchuk, Chief Engineer

Based on a series of mineralogical studies, the identity of compositions of altered kimberlite and kimberlite processing slime has been found. The content of clayey minerals of the type of talc, talc-saponite, chloritesaponite, Na-saponite and X-ray amorphous phase is high—to 50%. Calcite, dolomite and serpentine are present, too. The surface composition of natural diamonds when interacting with the identified minerals is studied using the methods of optical and infrared spectroscopy of the X-ray spectrum microanalysis. The tests involved kimberlite of different material constitution, finely disperse slimes after kimberlite processing and diamond crystals from products of kimberlite ore processing. The natural diamond crystals extracted from kimberlite ore and processing products were of three types: naturally hydrophobic crystals free from mineral species on the surface; naturally hydrophobic crystals with a few mineral species on the surface; naturally hydrophilic crystals with the dense surface coating of mineral species. It is shown that the surface of natural diamonds with mineral species formed on it is nonuniform, characterized by spread of calcium and magnesium carbonate films and has a mosaic coat of microsize admixtures from hydrophilic magnesium silica of talc-serpentine type with the increased mass fraction of iron. The area and depth of spread of mineral species on the surfaces of naturally hydrophobic and hydrophilic diamonds is provisional. The mechanism of formation and attachment of mineral species on the surface of crystals in the course of processing of altered kimberlite consists in the degree of conformity between parameters of crystal lattices of a crystallizing substance and a crystal surface has for the first time been discovered, and the classification of 4 types of mineral species forming on the surface of natural diamonds has for the first time been proposed. The experiments have been implemented in the laboratories of IPKON and Yakutniproalmaz Institutes and at Research and Explorations Works, ALROSA.
The study has been carried out in the framework of IPKON RAS R&D Program No. 0138-2014-0002 under support of Academician V. A. Chanturia School, Grant No. 74820145.

1. Progressive technologies of complex processing of mineral raw materials : collection of materials. Ed.: V. A. Chanturiya. Moscow : “Ore and Metals” Publishing House, 2008. 283 p.
2. Goryachev B. E. Technology of diamond-bearing ores. Diamonds, kimberlites and kimberlite minerals. Mineral-resource base of the world diamond-mining industry : tutorial. Moscow : Izdatelstvo «MISiS», 2010. 326 p.
3. Danilov Yu. G., Leontev S. P. Diamond mining in the Arctic regions of the Sakha Republic (Yakutia). Kontsept. 2016. No. 11. pp. 125–130. Available at: https://e-koncept.ru/2016/16246.htm (accessed: 15.04.2017).
4. Dvoychenkova G. P. Mineral formations on natural diamond surface and their destruction using electrochemically modified mineralized water. Fiziko-tekhnicheskie problemy razrabotki poleznykh iskopaemykh. 2014. No. 4. pp. 159–171.
5. Trofi mova E. A., Bogachev V. I., Dvoychenkova G. P., Zuev A. V., Minenko V. G. Mechanism of passivation and activation of natural diamonds in the processes of their extraction from kimberlites. Reports of the II Congress of dressers of the CIS countries. Moscow : MISiS, 1999. p. 112.
6. Zhang J., Kouznetsov D. L., Yu M., Rylatt M., Yoon R.-H. Improving the separation of diamond from gangue minerals. Minerals Engineering. 2012. Vol. 36–38. pp. 168–171.
7. Kovalenko E. G. Substantiation and choice of the conditions of mineral films removing from diamond surface during thermal processing. Scientific basis and practice of processing of ores and technogenic raw materials : materials of the XVII International scientific-practical conference. Ekaterinburg, 2014. pp. 170–173.
8. Chanturiya V. A., Dvoychenkova G. P., Kovalchuk O. E., Timofeev A. S., Podkamennyy Yu. A. Analysis of distribution of secondary minerals and their associations in the metasomatically changed kimberlite ores and their processing products. Rudy i metally. 2016. No. 2. pp. 73–83.
9. Chanturiya V. А., Dvoychenkova G. P., Kovalchuk О. Ye. Mechanism of fine dispersed mineral formation on the surface of diamonds and their removal by water system electrolysis products. Proceedings of the XXVIII International Mineral Processing Congress – IMPC 2016. Québec, 2016.
10. Independent Expert Report on Reserves and Resources of the Diamond Assets of the ALROSA Group of Companies. Norwich : Micon International Co Ltd, 2013. 429 p. Available at: http://www.alrosa.ru/wp-content/uploads/2013/11/Alrosa_Independent_Expert_Report-20131.pdf (accessed: 15.04.2017).
11. Verkhoturov M. V., Amelin S. A., Konnova N. I. Diamond dressing. Mezhdunarodnyy zhurnal eksperimentalnogo obrazovaniya. 2012. No. 2. p. 61.
12. Maksimovskiy E. A., Fayner N. I., Kosinova M. L., Rumyantsev Yu. M. Investigation of structure of fine nanocrystalline films. Zhurnal strukturnoy khimii. 2004. Vol. 45. pp. 61–65.
13. Monachon C., Weber L. Effect of diamond surface orientation on the thermal boundary conductance between diamond and aluminum. Diamond and Related Materials. 2013. No. 39. pp. 8–13.
14. Garrels R. M., Christ Ch. L. Solutions, Minerals and Eguilibria. Translated from English. Moscow : Mir, 1968. 368 p.
15. Wang J., Wan L., Hao S., Chen J. Surface modification of diamond and its effect on the mechanical properties of diamond/epoxy composites. Science and Engineering of Composite Materials. 2017. Vol. 24, Iss. 2. pp. 271–278.
16. Strickland-Constable R. F. Kinetics and Mechanism of Crystallization. Translated from English. Leningrad : Nedra, 1971. 312 p.
17. Fang L. Morphology and Spectral Characteristics of Octahedral Diamond Crystals from Yubileinaya Diamond Pipe (Yakutiya). Journal of Superhard Materials. 2013. Vol. 35, No. 4. pp. 214–219.
18. Rossman G. R. Vibrational Spectroscopy of Hydrous Components. Reviews in Mineralogy. 1988. Vol. 18. Spectroscopic Methods in Mineralogy and Geology. pp. 193–206.