Method of regeneration of fluoride glass

FIELD: reworking of wastes of glass industry; regeneration of fluoride glass and waste of its process; production of optically transparent glass.

SUBSTANCE: proposed method includes dissolving of wastes in ammonium bifluoride at their mass ratio of 1:3-5, evaporation of excessive bifluoride and obtaining powder-like product which is then treated with gaseous fluorine in the amount of 18-20 g per 100 g of powder for obtaining charge used for making glass.

EFFECT: enhanced efficiency.

1 dwg, 2 ex

The invention relates to the recycling of the glass industry, in particular to methods of regeneration of fluoride glass and waste (of the battle), which is formed when they are received, and can be used at the enterprises of the glass and optical industry to obtain optically transparent fluoride glasses.

Fluoride glass, which has high transparency in the region of 0.2-12 mm (from UV to IR region) and low loss of signal attenuation in the wavelength interval 1.7 to 3 microns, are the source material for IR optics, resonator and auxiliary optics, continuous chemical lasers. Bulk samples of the glasses used for visual observation and registration of radiation fields of the IR lasers, create lasers and LEDs with different light color, small alphanumeric indicators.

It is known that when the receiving quality of the fluoride glass makes high demands on the purity of the original compounds, in particular fluorides, the content of trace contaminants (iron, cobalt, Nickel, copper and Oh-groups) which should not be more than 10^-7%because the presence of these impurities leads to a sharp increase in the attenuation of infrared radiation, the emergence of centers of crystallization, and hence the quality of the resulting glass. It is known that salts of hydrofluoric acid was subjected to what are the hydrolysis not only in solution, but when interacting with water vapor at elevated temperatures - pyrohydrolysis to flow which is sufficient even traces of adsorbed moisture, available in almost any powdered sample, which is also one of the reasons for the deterioration of the optical characteristics of the glass, i.e. the appearance of marriage, and inability to use waste fluoride glass as such as raw materials for re-use in the process of melting the fluoride glass with the desired optical properties.

Generally, methods of obtaining fluoride glasses based on the melting of the charge source corresponding fluorides of metals in an inert atmosphere at 850°-1000°C, homogenization and cooling (p. the Russian Federation No. 2102346, publ. 20.01 1998), A.S. of the Russian Federation No. 1712329, publ. 15.02.1992 and 1705247, publ. 15.01.92). In the process of obtaining them, for various reasons, produce large amounts of waste (of the battle). Primarily this is due to physico-chemical properties of the glass itself, which has a narrow temperature interval vitrification (the crystallization temperature of the glass for a few tens of degrees above the glass transition temperature), making it difficult to obtain bulk samples of glass and optical fibers of high quality and leads to marriage. In addition, the glass melting process is associated with a number of specific hard the TEI, due to the chemical properties of the original fluoride (interaction of melts of these compounds with crucibles materials, chemical interaction with the environment, hydrolysis, high volatility of some fluorides), technological difficulties, leading to the formation of smiley due to the impact of the gas phase in the molten glass when pouring into moulds.

All the above reasons have led to the fact that experimentally so far failed simple perevorot waste (battle) fluoride glass again to obtain high-quality optically transparent glass, with the necessary physico-chemical characteristics.

Given the high cost included in the glass composition of the starting components, the task of regeneration and glass waste (of the battle) of its production to obtain bulk samples fluoride glass, which would satisfy the requirements of optical materials is relevant and currently unresolved.

The objective of the invention is to develop a method of regeneration of the fluoride glass.

The problem is solved by the method of regeneration fluoride glass by dissolving in the melt byflorida ammonium in a mass ratio of glass:before from 1:3 to 1:5, heating the obtained melt at the temperature of boiling byflorida ammoniate education powdery product keeping the obtained product to constant weight at a temperature of 400-500°With subsequent treatment of the product with gaseous fluorine in the number of 18 to 20 g per 100 g of powder and melting glass by melting the resulting mixture in an inert atmosphere at a temperature of 850-950°C.

The method is as follows.

The recycled glass making in the melt byflorida ammonium in the claimed ratio and the resulting mass is stirred until complete dissolution. While the fluorides of some metals (Zr, Al, Hf, In, and so on)included in the glass composition, form herocomplex, other (Na, Ba, La, etc.) dissolved without the formation of herocomplex. Excess byflorida ammonia is evaporated at the temperature of boiling byflorida to obtain a powdery product. Then the resulting powder was maintained at a temperature of 400-500°C to constant weight. During this time, there is a practically complete decomposition formed in the process of dissolution in byflorida ammonium herocomplex metals in the glass composition. And then handle the powder with gaseous fluorine based 18-20 g of fluorine per 100 g of powder. The resulting mixture is directed through glass melting, which is carried out in an inert atmosphere at a temperature of 850-950°C.

The claimed relationship recycled glass and byflorida ammonium and consumption of gaseous torus determined experimentally, this criterion estimates of their number was the quality of the glass, as measured by its optical characteristics, specifically, the absence of the IR spectrum, the absorption bands of Oh-groups in the field of transmission fluoride glass shows high quality glass.

With respect to byflorida ammonium and recycled glass by weight less than 3 cannot achieve complete dissolution of the original glass in byflorida that further leads to deterioration in the quality of the resulting glass, and an excessive amount of byflorida ammonium does not affect the quality of the glass and therefore impractical because only increases the consumption of reagent and energy consumption for its removal. The increase in consumption of fluoride over the claimed also impractical, as it does not affect the quality of the glass, while its deficiency leads to incomplete fluorination HE^-groups, and thus to a deterioration in the quality of the final product.

Temperature regimes of the proposed method are determined by the properties of byflorida ammonium and produced herocomplex and charge. It is known that the melting temperature of byflorida ammonium 126°C, the temperature of its boiling point at atmospheric pressure 240°C. the decomposition Temperature of herocomplex lie in the interval 300-400°and the melting point of policevisit above 550° C. Failure to comply with these temperature intervals results in further deterioration of the quality of the glass.

The method allows to regenerate as any type of fluoride glasses, including ftortsirkonatnye, or florinate, or perilunate glass, worn out or lost its original quality during operation (battle), and the corresponding waste generated in their production process.

Thus, the developed method of regeneration fluoride glass lets through secondary parivara glass waste to obtain bulk samples of optically transparent fluoride glass high quality in which the compositions and the properties of the original glass first cooking and recycled glass are practically identical.

The invention is illustrated by the following examples.

Example 1.

120 g of byflorida ammonium in a platinum crucible with a capacity of 200 ml are placed in an oven and heated to melt the entire mass of byflorida ammonium. Then, without lowering the temperature in the crucible portions of 10 grams make when mixing 30 grams of shredded recycled glass composition 53ZrF₄-20BaF₂-4LaF₃-3AlF₃-20NaF (ratio of glass:before is 1:4). The optical properties of this original glass (before grinding) are characterized by a transmittance curve 1 shown in the drawing. Glass after decade, minutolo mixing is dissolved in the melt NH ₄HF₂. Next, the excess byflorida ammonia is evaporated, increasing the temperature of the crucible to 240°and maintaining at this temperature for one hour. After removal of excess byflorida ammonium at the bottom of the crucible remains a fine powder. Then increase the oven temperature to 400°and maintain the resulting powder at this temperature for 30 minutes during this time is almost complete decomposition formed in the process of dissolution in byflorida of herocomplex metals in the glass composition. The decomposition process leads to a constant weight, i.e. up to the moment when the mass of the obtained powder becomes almost equal to the mass taken for the dissolution of glass (30 g), and then the resulting powder was treated with gaseous fluorine at a temperature of 450°C for 0.5 hour. The feed rate of the fluorine 12 grams per hour (flow rate of fluorine 6 g 30 g powder). Then carry out the glass. For that, the resulting mixture is melted in a dry chamber in an argon atmosphere at a temperature of 950°C, cooled to a temperature of 600°C, poured into the form and annealed at a temperature 270-275°C. are optically transparent, without swiley glass.

By conducted chemical analysis of the obtained glass, mol.%:

the zirconium fluoride (ZrF₄) - 53

fluoride barium - 20

lanthanum fluoride - 4

the aluminum fluoride - 3

ftory the sodium - 20,

you can see that its composition corresponds to the composition of the original recycled glass.

The IR spectra of the original and regenerated glasses coincide (see drawing, curve 1), whereas the IR spectrum of waste (crushed recycled glass) there is a strip in the region of absorption of HE^-groups (see drawing, curve 2).

Example 2.

A portion (100 g) of the glass composition 52ZrF₄-20BaF₂-3,5LaF₃-3AlF₃-20NaF-0,5InF₃-1rF₃pour in the melted byflorida ammonium (500 g), which in a platinum vessel. The attitude component of the solution is 1:5.

The vessel, equipped with a platinum stirrer and an outlet for gaseous products, cover and place in oven. With constant stirring of the melt gradually increase the temperature to 240°C (boiling point of byflorida ammonium) until complete dissolution of the glass and obtain a clear melt.

Further heating of the obtained melt causes the evaporation of excess byflorida ammonium and obtaining a precipitate, which represents a fine powder. Then raise the temperature to 450°and carry out the decomposition of herocomplex until constant weight of the powder.

The resulting powder was treated with gaseous fluorine at 450°C. the Flow rate of fluorine was 20 g per 100 g of powder, then hold the glass under the conditions shown in the ore 1.

The resulting glass has a chemical composition identical with the composition of the original recycled glass. Optical (IR-spectrum) features fully correspond to the original glass.

Thus, the inventive method of regeneration fluoride glasses for the first time allowed to regenerate as any type of fluoride glasses, worn out or lost its original quality during operation (battle), and the corresponding waste generated in the process of obtaining, getting a fluoride glass optical quality, which previously was not possible.

The regeneration process of the fluoride glass by dissolving in the melt byflorida ammonium mass ratio of glass:before from 1:3 to 1:5, heating the obtained melt at the temperature of boiling byflorida ammonium to the formation of the powdery product, keeping the obtained product to constant weight at a temperature of 400-500°With subsequent treatment of the product with gaseous fluorine in the number of 18 to 20 g per 100 g of powder and melting glass by melting the resulting mixture in an inert atmosphere at a temperature of 850-950°C.