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The purpose of this study was to the low-temperature synthesis of cobalt-containing diopside pigments based on granulated blast furnace slag and to study the characteristics of the mineral formation processes, changes in the structure and colour indices.

Synthesis of cobalt-containing diopside pigments based was carried out by the directional formation of the mineralogical composition with the introduction of part of the components using granulated blast-furnace slag.

It has been established that the formation of the diopside phase in pigments containing blast-furnace slag as the main component proceeds at low temperatures (1,100°C–1,150 °C). The colour of diopside pigments is formed because of the isomorphic substitution of Si4+ ions for Al3+ ions and Mg2+ ions for Co2+ ions. It is expedient to add CoO in an amount of 0.9 mol (18 Wt.%) into the composition of diopside pigments based on blast-furnace slag to obtain defect-free violet glazes.

The developed diopside pigments enable obtaining of high-quality violet glazes for ceramics. The application of the obtained results can significantly reduce the consumption of traditional raw materials in the composition of silicate ceramic pigments, as well as reduce their firing temperature.

Calcium, magnesium and silicon oxides are the main components of blast-furnace slag. In addition, granulated blast furnace slag is mainly represented by the glassy phase, which determines its high activity during the firing process. These factors are prerequisites for using the blast-furnace slag as a valuable substitute for chemically pure or natural raw materials in silicate pigments and reducing their firing temperature.

The purpose of this paper is to establish physical-chemical patterns and process parameters for obtaining low-temperature pink pigments with the structure of tin sphene using granulated blast-furnace slag.

Thermodynamic calculations were made in the work to assess the probability of malayaite phase formation during firing of slag-containing pigments. Mineralogical composition of synthesized pigments was evaluated by X-ray phase analysis. Spectral characteristics of pigments absorption in the infrared region were determined with the use of Fourier IR-spectrometry. Colour characteristics of the developed pigments and glass coatings with their introduction were studied on the comparator colour. Density of ceramic pigments was determined by pycnometric method, and chemical resistance was found on their weight loss after boiling in 1 N hydrochloric acid solution and 1 N sodium hydroxide solution.

Peculiar features of formation of the mineralogical composition of pink pigments are studied in the system CaO-MgO-Al₂O₃-SiO₂-SnO₂-Cr₂O₃ with the use of granulated blast-furnace slag. The end product and carrier of the pink colour is the solid solution on the basis of tin sphene. It is established that the most rational concentration of chromium (III) oxide for the formation of pink colouring of the pigments is 2 Wt.%.

The usage of developed pigments provides obtaining high-quality pink-coloured glaze coatings, in particular for ceramic tiles.

Activity of the components of blast-furnace slag in combination with the effective mineralizing action of B₂O₃ additive allows performing the firing of pink of the pigments with the formation of tin sphene at reduced temperature of 1,200°C.