RU2712885C1 - Method of producing diopside glass (versions) - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method of producing mineral material-based dolomite (CaMg(CO₃)₂) and silicon dioxide (pure quartz sand) of diopside glass, close to composition of MgCaSi₂O₆, with different functional properties, in particular, for production of luminescent and colored diopside glass with additives of rare-earth oxides, which can be used for production of industrial, jewelry and decorative-art products. Method comprises preparation of a charge by heat treatment of a mixture of mineral material dolomite and silicon dioxide in molar ratio of 1:2 in an open alundum crucible by heating to 1,200 °C, melting of the prepared charge in a glass-carbon crucible in an inert atmosphere using high-frequency heating with melt overheating to 1,600–1,700 °C till clarification of melt and hardening of melt in mode of switched off furnace. Rare-earth oxides, such as praseodymium, neodymium, samarium, europium, terbium or dysprosium, are added to prepared charge in amount of 1–30 wt%.

EFFECT: use of dolomite simplifies preparation of charge, since dolomite contains a calcium and magnesium ratio close to both in diopside and required for production of diopside glass.

4 cl, 3 tbl, 3 dwg

Description

The invention relates to a method for producing dolomite (CaMg (CO ₃ ) ₂ ) and silicon dioxide (pure quartz sand) diopside glass, based on mineral raw materials, close to the composition of MgCaSi ₂ O ₆ , with various functional properties, in particular, to obtain luminescent and colored diopside glasses with additives of rare-earth oxides, which can be used for the manufacture of industrial, jewelry and decorative-artistic products, as well as in the manufacture of glass - ceramic products.

Pure pure diopside has the chemical formula MgCaSi ₂ O ₆ , is a white crystalline powder, in the form of crystals it is colorless transparent samples.

The use of dolomite in the glass industry is widely known and is due to the introduction of magnesium oxide in concentrations not exceeding 5 wt. % to increase the strength and chemical resistance of glasses [New reference chemist and technologist. Raw materials and products of the industry of organic and inorganic substances. Part I, section 7 Glass, 7.3. The composition of industrial glasses for various purposes - St. Petersburg: "Peace and Family", 2002, 988 S.]. Therefore, dolomite, as a source of magnesium oxide, is introduced into the mixture for glasses in low concentrations, the content of calcium oxide is regulated by lime additives. The quality of dolomite for industrial glasses is determined by GOST 23672-79 * Dolomite for the glass industry. Technical conditions

Upon receipt of special glasses, dolomite is introduced into the mixture in high concentrations. So, for example, in the patent [US 2961328 Refractory glass composition, publ. 11.22.1960, IPC: С03С 3/076, С03С 3/102] to obtain special multicomponent refractory glasses intended for use at high operating temperatures and resistant to damage from nuclear radiation, up to 7-30% of calcium and magnesium are introduced into the mixture oxides in the form of dolomite. Known composition of the charge for colored glass, which includes the use of the order of the order of 25 mass. % dolomite (magnesium-calcium carbonate) along with sand and lime and additives that lower the melting point of the mixture and color [RU 2569942, Batch for colored glass, publ. 12/10/2015, IPC: С03С 6/04]. Also known composition, including dolomite, sand and lime and additives containing iron, to obtain green glass for automotive and architectural glazing, absorbing infrared and ultraviolet radiation [EP 465645 BATCH COMPOSITION FOR MAKING INFRARED AND ULTRAVIOLET RADIATION ABSORBING GREEN GLASS, publ. 01/15/1992, IPC: C03C 3/087, C03C 3/095, C03C 4/02, C03C 4/08, C03 6/04].

Pure dolomite with silicic acid is used to hydrothermally obtain a crystalline diopside powder suitable for use as a raw material in the ceramic industry [US 3652207 PROCESS FOR THE PRODUCTION OF SYNTHETIC DIOPSIDE, publ. 03/28/1972, IPC: C04B 35/16, C04B 35/20, C01B 33/00, C01B 33/24, C04B 33/26]. The use of diopside prepared in such a way to obtain diopside glass is economically disadvantageous due to the complexity of the hydrothermal process, including preliminary decarbonization with the conversion of dolomite into a powder mixture of magnesium and calcium oxides.

Luminescence on powders of synthesized MgCaSi ₂ O ₆ : Ln (doped diopside) was studied in [Sahu Ishwar Prasad // J Mater Sci: Mater Electron, 2016, V. 27, P. 10353-10363] for rare-earth ions (Ce ³⁺ , Sm ³⁺ , Eu ³⁺ , Eu ²⁺ , Dy ³⁺ , Tb ³⁺ ) emitting in the visible spectrum. The prospects of using phosphors based on diopside for diode light sources are expressed.

Luminescence of rare-earth ions in diopside glasses of MgCaSi ₂ O ₆ composition has not been studied. There is evidence of luminescence in multicomponent glass ceramics [Jinshu Cheng, Peijing Tian, Weihong Zheng, Jun Xie, Zhenxia Chen // Journal of Alloys and Compounds 471 (2009) 470-473; Peijing Tian, Jinshu Cheng, Gaoke Zhanga, Zhenxia Chen, and Qian Wang // Glass Physics and Chemistry, 2010, Vol. 36, No. 4, pp. 431-435], which includes grains of diopside glass with a brighter glow, which most likely belong to an impurity fusible diopside glass and the diopside phase crystallized at 1000 ° C with impurities, since it is known about the high solubility of metal oxides in diopside.

To conduct structural studies of melts along a series of MgSiO ₃ -CaSiO ₃ compounds with rapid cooling (quenching) of the melt, transparent glasses of the composition (Ca _2x Mg _2-2x Si ₂ O ₆ , where x = 0, 0.25, 0.75 and 1 . [Cormier L., Cuello GJ // Geochimica et Cosmochimica Acta, 2013, V. 122, P. 498-510]. To obtain the melt using a mixture of SiO ₂ , MgO and CaCO ₃ , which is pre-subjected to decarbonization overnight at 800 ° C, then melted in air at a temperature of 100 ° C above the melting temperature for an hour in a platinum-rhodium crucible. This method of producing diopside glass is suitable for research purposes and is not technologically advanced: a long decarbonization time, the use of expensive platinum and expensive reagents, the low-tech melt quenching process.

The technical task is to develop an economical method of producing both pure diopside glass close to the composition of MgCaSi ₂ O ₆ and containing rare-earth oxide additives to produce luminescent and colored diopside glasses suitable for the manufacture of industrial, jewelry and decorative items, and also in the manufacture of glass - ceramic products.

The technical result of the invention is achieved through the use of a mixture containing the mineral-forming components of diopside - mineral raw materials pure dolomite CaMg (CO ₃ ) ₂ and quartz sand in a ratio of 1: 2 mol. %, which is pre-decarbonized by heating to 800 ° C at a speed of 20-30 ° C / min, followed by slow heating at a speed of 3-4 ° C / min to 1000 ° C, is kept at this temperature for at least an hour, then heated to 1200 ° C for one hour, followed by exposure for at least 2 hours, while the mixture is homogenized by grinding during exposure at 1000 ° C and 1200 ° C, then the mixture is loaded into a glass-carbon crucible and melted in an inert atmosphere using high-frequency heating with overheating of the melt to 1600 ° C, after clarification of the melt pr They conduct hardening of the melt in the off-furnace mode.

The technical result is also achieved by introducing into the mixture containing the mineral-forming components of diopside, mineral raw materials, the pure dolomite CaMg (CO ₃ ) ₂ and quartz sand in a ratio of 1: 2 mol. %, rare earth oxides in an amount of from 1 to 30 mass. % The mixture containing dolomite and silica sand is pre-decarbonized by heating to 800 ° C at a speed of 20-30 ° C / min, followed by slow heating at a speed of 3-4 ° C / min to 1000 ° C, holding at this temperature for at least an hour, then heated to 1200 ° C for an hour, followed by exposure for at least 2 hours, while the mixture is homogenized by grinding during exposure at 1000 ° C and 1200 ° C.

After the introduction of rare-earth oxides, the mixture is homogenized, then loaded into a glassy carbon crucible and melted in an inert atmosphere using high-frequency heating with overheating of the melt to 1600-1700 ° C; after clarification of the melt, the melt is quenched in the off-furnace mode.

As rare earth oxide, praseodymium or neodymium or samarium or europium or terbium or dysprosium oxide is used. To obtain luminescent glasses in the composition of the charge is introduced from 1 to 5 mass. % rare earth oxide: Pr, or Nd, or Sm, or Eu, or Tb or Dy, whose ions emit in the visible region of the spectrum. To obtain colored glasses in the composition of the charge is introduced from 5 to 30 mass. % of rare-earth oxide: Pr, or Nd or Ei, whose ions give the glass a green, lilac, red color, while the melt overheating is increased to 1700 ° C, followed by quenching by switching off the induction heating.

The transparency and uniformity of the resulting glasses is shown in FIG. 1. In FIG. Figure 2 shows the luminescence spectra of diopside glasses doped with rare-earth oxides (3 wt.%) Upon excitation at λ = 300 nm. In FIG. 3 shows the diffuse reflectance spectra (DLS) of powders of ground glass: 1-30 mass. % praseodymium oxide; 2-10 mass. % europium oxide; 3-30 mass. % europium oxide.

The essence of the invention is disclosed by examples.

For the preparation of the mixture used white dolomite grade DK-19-0.5 (Quarry Taenzinsky, Sheregesh), practically free of iron impurities. According to the results of elemental analysis, it is pure magnesium calcium carbonate of the composition Mg _1-x Ca (CO ₃ ) ₂ . The results of elemental analysis are presented in table 1.

Example 1. 10 g of crushed and sifted dolomite is mixed with 6.52 g of powdered silicon dioxide, grade chda (GOST 9428-73). The mixture of components in the alundum crucible was preliminarily subjected to heat treatment by rapid heating at a speed of 20-30 ° C / min to 800 ° C, followed by slow heating at a speed of 3-4 ° C / min to 1000 ° C, one-hour exposure at 1000 ° C, so that the process of decomposition of carbonate is not intense and there is no release of the mixture from the crucible due to gas evolution. Subsequent heating to 1200 ° C for 1 hour with exposure for 2 hours and grinding the mixture during aging at 1000 ° C and 1200 ° C provides additional homogenization of the mixture, the final removal of gas impurities and bringing the mixture to a constant weight. According to the results of x-ray phase analysis, the mixture is a mixture of magnesium, calcium and silicon oxides, possibly with passivation of the surface of magnesium and calcium oxides with a thin diopside film, since during storage of the mixture thus prepared, no change in its weight was observed. After cooling, the mixture is ready for storage and use for melting and obtaining diopside glass. To obtain diopside glass, 3 g of the mixture are placed in a glassy carbon crucible with a diameter of 15 mm and a height of 60 mm. The charge is melted using induction heating to 1600 ° C until the melt is clarified and the melt quenched in the off furnace mode. It is known that induction heating creates a magnetic field that contributes to the mixing of the melt and to obtain uniform tempering during tempering. Table 2 presents the results of the analysis of diopside glass.

Example 2. In 3 g of the mixture prepared according to example 1 is introduced from 1 to 5 mass. % rare earth oxide: Pr, or Nd, or Sm, or Eu, or Tb or Dy. Mixtures after thorough mixing are ready to obtain glasses with luminescent properties. Glasses were obtained by quenching of the charge melt from 1600 ° С, the luminescence spectra of which are shown in FIG. 2.

Example 3. In 3 g of the mixture prepared according to example 1, enter from 5 to 30 mass. % proseodymium oxide, or neodymium oxide or europium oxide. The mixture, after thorough mixing, is ready to obtain brightly colored diopside glasses. Glasses were obtained by quenching of the charge melt from 1700 ° С with a characteristic green earth, green, lilac or red hue, respectively (Fig. 1).

The color characteristics of a number of colored diopside glasses obtained from diffuse reflectance spectra (DDS) of powdered ground glasses (Fig. 3) are presented in Table 3.

Color parameters calculated from SDO in accordance with GOST R 52489-2005 and GOST R 52662-2006. Light source: D65. Observer 10 ° (1964).

Claims (4)

1. The method of producing diopside glass, including decarbonization of a mixture containing mineral-forming components of diopside — magnesium oxide, calcium carbonate and silicon dioxide during heating in air, melting and quenching of the obtained melt, characterized in that a charge containing mineral-forming components of diopside — mineral raw materials is used pure dolomite CaMg (CO _{3) 2} and silica sand in a ratio of 1:. 2 mol%, which had been previously dekarboniziruyut heating to 800 ° C at a rate 20-30 ° C / min, followed by slow heating at a speed of 3-4 ° C / min to 1000 ° C, maintained at this temperature for at least an hour, then heated to 1200 ° C for an hour, followed by exposure for at least 2 hours, while the mixture is homogenized by grinding during aging at 1000 ° С and 1200 ° С, then the charge is loaded into a glassy carbon crucible and melted in an inert atmosphere using high-frequency heating with overheating of the melt to 1600 ° С, after clarification of the melt, the melt is quenched in the off-furnace mode. 2. A method for producing diopside glass, including decarbonization of a mixture containing mineral-forming components of diopside — magnesium oxide, calcium carbonate and silicon dioxide during air heating, melting and quenching of the obtained melt, characterized in that a charge containing mineral-forming components of diopside — mineral raw materials is used pure dolomite CaMg (CO _{3) 2} and silica sand in a ratio of 1:. 2 mol%, which had been previously dekarboniziruyut heating to 800 ° C at a rate 20-30 ° C / min, followed by slow heating at a speed of 3-4 ° C / min to 1000 ° C, maintained at this temperature for at least an hour, then heated to 1200 ° C for an hour, followed by exposure for at least 2 hours, while the mixture is homogenized by grinding during aging at 1000 ° С and 1200 ° С, 1-30 wt.% Of rare-earth oxide is introduced into the mixture, homogenized, then the mixture is loaded into a glass-carbon crucible and melted in an inert atmosphere using high-frequency heating with melt overheating to 1600-1700 ° С, after clarification of the melt conduct hardening of the melt in the off mode of the furnace. 3. The method of producing diopside glass according to claim 2, characterized in that the rare-earth oxide is introduced into the charge from 1 to 5 wt.% To obtain luminescent diopside glass or from 5 to 30 wt.% To obtain colored diopside glass. 4. The method of producing diopside glass according to claim 2 or 3, characterized in that the oxide of praseodymium, or neodymium, or samarium, or europium, or terbium or dysprosium is used as the rare-earth oxide.

Images