National University of Science and Technology “MISIS”, Moscow, Russia:

T. I. Yushina, Candidate of Engineering Sciences, Professor, Acting Head of the Chair of Mineral and Waste Material Development and Processing, E-mail: yuti62@mail.ru
I. O. Krylov, Candidate of Engineering Sciences, Associate Professor
K. S. Popova, Candidate for a Master’s Degree
V. A. Vinnikov, Doctor of Physical and Mathematical Sciences, Professor, Head of the Chair of Physical Processes of Mining and Geocontrol

One of the most promising ways of enhancing value of low-grade manganese (ferriferous manganese) ores is their utilization in cleaning treatment of process gases in the capacity of synthetic scavengers, adsorbents and catalysts, or as a feed stock. It has been found that in the course of high-temperature removal of sulfur-bearing compounds from process gases using low-grade manganese (ferriferous manganese) ores as adsorbing agents, carbon nanotubes are generated on the adsorbent. The use of the natural ferriferous manganese catalyst for cleaning treatment of process gases and for carbon nanotubes production, and the follow-up re-use in purification circuits or in metallurgy allows enhancing profitability and ecological properties of the final product. Searching for new methods to produce low-cost carbon nanotubes is of interest both for applied and basic science. A carbon-catalyst composite obtained in the course of decomposition of carbon-bearing gases with the aid of ferriferous manganese ore at a temperature of 850 °С was analyzed. The catalyst was made of ferriferous manganese ore of Porozhin deposit, which exhibited the highest sorption activity in accordance with the evidence of the previous research findings on the use of manganese (ferriferous manganese) ore in the capacity of a catalyst in production of nano-carbon materials. It was found that samples contained carbon nanotubes after catalytic decomposition of methane. The samples contained single-layer and multilayer carbon nanotubes, and chains of carbon nanotubes. Mass fraction of the carbon phase was 32%. The objective was to qualitatively separate the generated carbon structures and the natural catalyst. Actual separation of carbon nanotubes and catalysts in the world involves grinding, high temperature oxidation owing to different oxidabilities of allotropic forms of carbon, and chemical dissolution of a catalyst in acids. The drawbacks of these methods are irretrievable loss of a catalyst and deterioration of properties of carbon nanotubes. The research accomplished by Ryabov Yu.V. and his fellows revealed high efficiency of carbon separation from fly ash of coal-fired electric power plants by flotation. The collecting agent was kerosene and the foam maker was pine oil and agents T-66 and T-80. The versatility of properties of acetylene alcohols-based agents DMIPEC and DC-80 enabled presuming foam separation of generated carbon nanotubes from the catalyst bottom layer with the use of these agents only (without kerosene). It was found that nonionic acetylene alcohols-based agents DMIPEC and DC-80 acted as efficient foaming and collecting agents both in flotation of nonferrous metals and carbon-bearing materials of coking coal and carbon nanomaterials. This article proposes a method of foam separation of carbon nanotubes, synthesized with the aid of natural ferriferous manganese ore catalyst, into flotation froth. From the test data, the best yield of carbon nanotubes is obtained with acetylene alcohols-based agent DC-80: the recovery in carbon concentrate reaches 80–90%. On the strength of the testing results, the technology of separation of carbon nanotubes from natural ferriferous manganese catalysts with the use of agents made of acetylene alcohols has been developed. This technology allows extraction of carbon nanotubes in concentrate in the form of powder intended for the subsequent use in modification of composite materials with a view to improving their useful quality and extending operational life of modernized production. Also, carbon concentrate can be used in agglomeration and blending of crushed waste manganese ore for production of ferromanganese. This factor, in is turn, will reduce the cost of ferromanganese.

The study has been carried in the framework of “Conducting scientific and research works (fundamental and applied scientific investigations and experimental researches) No. 816 of the target No. 2014/113 for execution of the state works in the field of scientific activity in the framework of the basic part of the State Target.

The authors express their deep gratitude to Malyshev O. A and Shchelkunov S. A., Innovation Resource, Moscow, for the chemical agents provided.

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