RU2026834C1 - Method of preparing of glass ceramic material - Google Patents

Abstract

FIELD: building materials. SUBSTANCE: method involves charge heating up to 1600-2000 C at the rate 10³-10⁴ degree/h using plasma heat-carrier, boiling, melt forming, crystallization and annealing. Energy consumption an average does not exceed 5 kWh/kg. The different waste can be subjected for processing: slags, ashes, broken glass, furrow of mining plants. EFFECT: improved method of material preparing. 1 tbl

Description

 The invention relates to the field of production of consumer goods and building materials, mainly glass-crystalline materials, and can be used to produce ceramic and stone castings with a contrasting color pattern such as malachite, jasper, etc.

In the production of decorative glass crystal products of various functional purposes, a casting method is used, which includes filling the molds with a chopped charge, heating and melting the charge, crystallization and cooling of the melt [1]. This method allows to obtain decorative materials and products with high consumer properties. However, the process according to this method is slow and periodic, which entails unproductive heat loss. Thus, heating of the charge before melting is at a rate of 180-200 ^{° C} per hour, and cooling - at a rate ^of 20-30 C per hour. In addition, forms from traditional refractories (corundum, chamotte, etc.) can withstand the indicated heating rate only with small volumes (up to 1-2 l) and with a limited number of heats. Non-traditional refractories (platinum, graphite, refractory metals, titanium nitride, etc.) are either extremely expensive or wear out due to intense chemical interaction with the melt. The cooking temperature of 1500 ^° C is limited in air.

 Closest to the invention in technical essence is a method for producing a melt from minerals or raw materials by loading into a furnace, supplying there gas that is heated by plasma, followed by melting and production [2].

 The disadvantage of this method is that the melting of the mixture occurs slowly, in equilibrium, which leads to complete homogenization of the composition and eliminates the possibility of obtaining products with a decorative fire-polished surface. The known method requires the introduction of special additives to the mixture: catalysts, including rather expensive ones, which cause bulk crystallization of glass.

 The aim of the invention is the intensification of processes and the expansion of the raw material base.

To provide the method using a plasma coolant. Plasma coolant, for example, air, heated by electric discharge to a temperature of 3000-4000 ^о С, has a high heat content (1000-2000 kcal / kg) and provides intensive heating of a charge of any composition to a temperature of 1600-2000 ^о С at a speed of 10 ³ -10 ⁴ degrees in hour. With such heating, homogenization of the molten glass melt does not occur and the components of the glass melt are located and volume in accordance with the sequence of their melting. This creates the prerequisites for the crystallization of glass components in the surface layer without special catalysts, which provides decoration of the product surface. On the other hand, intensive heating of the mixture to a high temperature of 1600-2000 ^о С provides quick gas removal from the glass melt and obtaining at the stages of molding crystallization and annealing of the fiery polished surface of the products without defects: cracks, bubbles, etc.

 A schematic diagram of the proposed method for producing glass crystalline materials is as follows. The components of the mixture in powdered form by metering devices are fed into the mixer, the resulting mixture is continuously fed by the feeder into the plasma furnace. Air or other plasma forming gas is supplied to the plasma generator. The resulting plasma coolant is sent to the furnace for heating and melting the charge. From the furnace, molten glass is poured into molds. After the temperature of the melt in the surface layer is reduced to the crystallization temperature, the products are sent to an annealing furnace.

 Examples of the method for producing glass crystalline materials and stone casting are given in the table.

EXAMPLES EXAMPLE 1. In a plasma melting furnace lined corundum lightweight concrete, was heated to a temperature of 1600-2000 ^{° C} and the furnace wall charge comprising the refractory products of apatite flotation tailings. As used coolant air plasma with a temperature ^of 3000-4000 C. Inject portion of the charge and under the influence of the walls of the radiation heat and melt is heated to a temperature of 1600-2000 ^{° C} for 10-90 min (10 ⁴ -10 ³ K / h). The charge heating rate is controlled by the plasma coolant flow rate. A portion of the melt corresponding to the introduced portion of the charge is poured into the prepared forms. The resulting products are cooled to the temperature at which crystallization of the refractory charge components begins in the surface layer of the melt and the products are placed in an annealing furnace. The temperature in the annealing furnace is reduced at an empirically determined speed. The resulting products have a variably decorated, fiery-polished surface without visible defects (cracks, bubbles, etc.) and are characterized by high physical and technical properties: strength, hardness, heat resistance. The main factor of intensification - the heating rate of the charge in the melting furnace - has limitations associated with ensuring high quality surface of the product. Too slow heating - less than 10 ³ deg / h - leads to the dissolution of the colorizing components in the melt, homogenization of the melt and the decorative properties of the surface of the resulting products disappear, since it does not completely remove gases from the melt and leads to the surface manifesting as a result of gas bubble formation .

Another factor of intensification - the high temperature of glass melting - has thermophysical limitations. If cooking temperature exceeds 2000 ^{° C,} there are difficulties in the selection of material for the furnace lining. Available refractories can not withstand heating above 2000 ^° C. Cooling the walls of the furnace leads to high energy costs. Reduced cooking temperatures lower than 1600 ^{° C} provides no melting of refractory batch components, resulting in stresses occur during the crystallization, which leads to cracks in the products.

In example 3, the main components of the charge are SiO ₂ 41-44 wt.%, CaO 10-24 wt.%, TiO ₂ 14-16 wt.%, Al ₂ O ₃ 11-13 wt.%. To obtain high-quality products, such a charge has to be heated to a temperature of 1700 ^o C. Here the components of apatite production wastes are used.

The use of the invention in comparison with known methods provides the following advantages:
- the stage of heating and melting of glass is intensified, which allows to reduce the dimensions of the melting furnace and reduce energy consumption (energy consumption on average is 5 kWh / kg of weight, dimensions 0.5x0.3x0.3 m ³ );
- various waste can be subjected to processing into ceramic and stone casting: dumps of mining enterprises and their components, slags of metallurgical industries, spent catalysts, ashes and slags of heat generating units, cullet, etc., which contributes to solving environmental problems, the integrated use of minerals and expanding the raw material base for the production of glass and stone casting;
- products with a glossy fire-polished surface with a multi-color pattern are obtained that imitate the surface of polished natural stones such as jasper, malachite, etc., which significantly expands the scope of economic, cultural and artistic use of the products obtained.

Claims (1)

METHOD FOR PRODUCING GLASS-CRYSTAL MATERIAL by preparing a charge, heating and melting glass using a plasma coolant, molding, crystallization and annealing, characterized in that, in order to intensify the process and expand the raw material base, heating to 1600 - 2000 ^o C is carried out at a speed of 10 ³ - 10 ⁴ degrees / h.

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