RU2230709C2 - Method and apparatus for pool-free melting of rock - Google Patents

Abstract

FIELD: production of melt from rock, domestic and industrial glass wastes.

SUBSTANCE: method involves providing convection jet-shock heating of burden at temperature of 1,700⁰C plus and minus 250⁰C and flame tongue and burden collision rate of 30-250 m/s; forming heat spots on ceramic tilt hearth and spilling burden onto heat spots in thin layers or in lumpy bulk layers; dividing furnace space into local melting zones by means of false walls. Height H of furnace crown above heat spots D of hearth is one of the most important parameters of jet-shock heating process. Depending on purpose of burners, i.e., melting, heat shielding or overheating of melt before delivery, H/D ratio is chosen within the range of 0.5-4.6. Method allows burden melting process to be carried out at high temperature stress considerably exceeding thermal stability of furnace refractory lining and furnace continuity to be kept. If necessary, melt is subjected to separation procedure before delivery to provide for removal of high-melting point by-product ingredients by gravitational jigging of unmelted burden lumps onto ceramic hearth followed by removal thereof through processing windows.

EFFECT: increased efficiency and intensified melt production process.

14 cl, 15 dwg

Description

The invention relates to the production of a melt from volcanic predominantly refractory impurity glasses-rocks, as well as from household and industrial waste glass, in particular to the intensification of the melting process, and can find application in technologies for the production of non-combustible fibrous insulation for various fields of industrial and civil engineering.

There is a method of intensive glass melting in gas-fired bath furnaces by thin-layer loading of the charge onto an overheated bath mirror, which can significantly reduce the time to obtain finished glass melt and increase melt removal from a square meter of the mirror / 1 /.

The disadvantage of this technical solution is the complexity of the process of charge preparation and loading of the charge into the furnace, as well as significant loss of the charge from the entrainment of fine fractions from the bath mirror into regenerative heating wells.

There is another method and device for intensive melting of a mineral charge in bath furnaces, melting in charge heaps using a directional high-temperature torch of single burners. At the same time, to intensify heat and mass transfer, a constant spray of superheated melt is carried out on charge heaps. The melt, flowing down the slope with a thin film, pulls particles of the charge behind it onto the mirror, ensuring their fast melt / 2 /.

A disadvantage of the known invention is the high energy consumption for maintaining a significant recirculation volume of the superheated melt to ensure the sprayed process, as well as the concomitant large droplet entrainment of the melt into the flue duct.

From / 3 /, another method is known for intensifying the process of melting a finely dispersed mineral mixture on inclined surfaces — shelves with gas-flame or indirect electric-arc heating. As the melt flows down from the heated slopes, the decrease in the melted layer is supported by fresh portions of the load. The resulting primary melt enters the fume and homogenization in a storage, gas-heated pool. The inclination angles of the melting slopes are selected taking into account the dispersion of the charge, the degree of flowability, as well as the fluidity of the melt.

The disadvantage of this method is its unsuitability for melting rocks, since this method can only be melted easily frit alkaline mixture, capable of hanging and melting when heated on steep slopes.

It should be noted that the production of the melt from silicate blends is carried out mainly using furnaces with a liquid storage-expendable bath, due to the contact of the particles of the loaded charge with the overheated melt. In this case, the melt and the bath, in turn, are heated by radiation heat, which radiate the arch and walls of the furnace. However, the maximum operating temperature of the arch and walls is limited by the heat resistance of refractories 1600 ° C. In order to heat the bath to a temperature equal to the temperature of the arch, the furnace must be idle for a long time without issuing a melt, since loading a cold charge will sharply reduce the temperature of the bath. All this makes the melting of silicates in a liquid bath with continuous melt delivery - inefficient and uneconomical. At the same time, it is quite obvious that it is impossible to increase the productivity of melting furnaces without mastering the heating temperatures of 1700 ... 2000 ° С, i.e. going beyond the heat resistance of industrial refractories. In gas furnaces with radiation heating, this problem cannot be solved. Nevertheless, the problem can be solved by using convective shock-jet heating of the mixture with high-temperature gases.

Known continuous gas furnace with vault heating for high-speed shock-jet heating of metal blanks for forging, hardening, etc. targets to a temperature of 1200 ... 1300 ° C / 4 /. The heated metal is located on a carborundum movable hearth, which rests on a roller platform with a crank reciprocating drive. To supply high-temperature gases, four high-speed gas burners of the GV type, developed by the Institute of VNIIpromgaz / 5 /, are installed in the roof of the furnace. The GV torch includes an air-cooled combustion chamber made of heat-resistant steel X23H18 and a casing of steel X18H10T. The remaining components and parts are made of Art. 3. The flow rate of the products of fuel combustion is 100 ... 200 m / s. Gas consumption 1.75 ... 14.0 nm ³ / h. The burner is equipped with an electric spark ignition device. When heating combustion air, the flame temperature can reach 1900 ° С. The speed of heating with the shock-jet method is 6-10 times higher than with the usual lay torch. Impact-jet furnaces are close in intensity to the induction electric furnaces used to heat the metal in terms of heating intensity.

Studies have shown / 5 / that in furnaces with shock-jet high-speed heating, the greatest heat transfer from the jet falls on the bottom and the adjacent base of the side wall, and the amount of heat transferred to the arch and part of the wall adjacent to the arch is 4-5 times less than on the bottom.

A disadvantage of the known technical solution is the unsuitability of the hearth of the furnace to obtain a melt from a silicate charge, as well as the limited technological and design capabilities of the ceramic arch for multi-row placement of burners and charge charge feeding devices.

The closest in its technical essence and the achieved effect to the present invention is a method for producing a melt on a pitched hearth without an accumulative bath, implemented in the invention / 6 / for producing glass from fiberglass production wastes. The furnace contains a pool with a ceramic sloping hearth inclined at an angle of 3-5 °. A duct is laid out in the pool, the bottom hearth of which at the end has a vertical groove for the formation of a glass jet. At a distance of 150-200 mm from the bottom edge of the beam, a cone-shaped hole is made in the hearth, through which the glass melt stream freely falls. A side pocket is used to load waste into the oven. The furnace is heated by two medium-pressure gas burners, which are installed on the trading side of the pool. The furnace operates as follows. They light the heating burners and when the temperature in the furnace reaches 1380-1400 ° C through the side pocket, the first portion of fiberglass waste is loaded onto the bottom. Then, a hot air supply fan is turned on, which enhances the burnout of the organic components of the binder, after which the annealed glass melts and flows along the inclined bottom to the working duct - the tray, which, passing through the vertical groove with a thin stream, freely falls in the center of the hearth hole.

The disadvantage of the selected prototype is the inability to obtain a melt from more refractory than glass materials, such as rocks.

The aim of the present invention is to intensify the process of obtaining melt from volcanic glass - rocks, as well as domestic and industrial waste glass.

This goal is achieved by the fact that in the method of melting volcanic rocks containing refractory impurities - quartzite and others, including loading and melting the charge on a solid base with continuous gravitational selection of the melt for delivery, the charge is melted on overheated local areas of the solid base - fire spots, which are formed using directional shock-jet heating at a temperature of 1700 ± 250 ° C, moreover, the charge on the frypot is dosed with a thin layer and / or in the form of lumpy bulk, and the resulting melt in the process the selection is continuously separated from the non-melt onto a solid base with periodic removal from the furnace using a scraper. According to the invention, one heat spot is formed by at least two shock-jet streams; on a solid base, locally or over the entire area of the melting zone, in order to protect the hearth from being washed away by a high-speed torch, a constant layer of reduced metal is left.

In the device for implementing the proposed method, comprising a furnace with a ceramic arch and an inclined single-hearth furnace, a batch feeder, burners for burning hydrocarbon fuel with a chimney system, a production tray mounted inside the furnace, a channel with a vertical channel at the end, under which a cone-shaped drain hole is formed in the bottom melt, - the hearth or part of it is laid horizontally, and the furnace arch is water-cooled in the form of at least one burner panel welded from sheet steel, with a cylinder assembly companies, technological holes for loading the charge, measuring temperatures, taking gas and slag samples, etc., the panel is lined on the fire side with a lightweight heat-insulating refractory, mounting grips and ribs are made on the outside of the panel, and burners are installed in the lances for burning gas and / or liquid fuel, the torch of which interacts with the hearth of the furnace at a collision speed of 30 ... 250 m / s and the ratio of the height of the arch "N" to the average diameter of the heat spot "D" in the limit x, N / A: 0.5 ... 4.0. As an embodiment, the arch or part of the arch is made with an inclination in accordance with the profile of the hearth. In the tuyeres of the arch gas shock-burner gas burners with a nominal / 7 / thermal power of 100 ... 1200 kW are installed at a flow rate of the products of fuel combustion at the nozzle exit 160 m / s. In accordance with the invention, at least one massive reflective false wall made of highly refractory material is installed inside the furnace parallel to the main walls, the gap between the walls being 0.1 ... 2.5 of the average diameter of the heat stain. The hearth of the furnace in the charge melting zone is blocked by a slag shutter with a partial deepening into liquid metal and equipped with a tap hole for draining metal profit. In addition, the hearth is made with a slope of two slopes, and the skate ridge is common and located in the transverse and / or longitudinal sections of the hearth. The slopes of the ramps of the bottom are oriented opposite each other, and their lower ends are adjacent to the common working tray. As an embodiment, the slopes of the gable bottom are oriented in opposite directions to the individual working trays. According to the claimed device, the hearth or its individual sections are equipped with grate ledges and / or partitions in the form of truncated pyramids, cones, hemispheres, gratings or other pheometric shapes made of welded cast iron-chromium alloy with a chromium content of 35 ... 75%.

The working tray is made by a weld-cast method of iron-chromium alloy with a chromium content of 35 ... 75%. As another embodiment, the hearth of the furnace is lined with ceramic oxide refractories with a chromium oxide content of 92.5 ... 96.0%.

Figure 1 shows a General view of the proposed device, a side section and a schematic diagram of a vannless method for melting rocks containing refractory impurities with separation and removal of non-melt from the furnace; figure 2 presents a side section of a furnace with a partially inclined hearth and a horizontal working section; figure 3 is a variant of the melting of the charge on a horizontal hearth, protected by a layer of molten iron; figure 4 - node sludge and continuous discharge of profit of the recovered metal; 5-6 schematically depict a melting furnace with a gable hearth with a slope of each slope to a common production tray; 7-8 show a furnace with a gable hearth, the slopes of which are oriented in opposite directions, to individual production trays; figure 9 is a diagram of the interaction of convective shock-jet flows of the burners with the charge / a / and the bottom / b /; figure 10 shows various options for the placement in the furnace space of false walls and heat spots on the hearth, as well as a fragment of the smoke exhaust circuit.

The device for the wireless melting of rocks according to the proposed method is a melting furnace 1, which includes a ceramic lined from refractory bars 2 under, a working 3 tray with a vertical 4 channel, a hollow water-cooled 5 arch made in the form of a burner panel welded from sheet steel with cylindrical 6 tuyeres and 7 technological holes for loading the charge, taking slag and gas samples, measuring temperatures, etc. The arch on the firing side is lined with refractory 8 light weight, on the outer side of the arch 5 there are mounting eyes and power elements of longitudinal-transverse stiffness / not shown /. The power frame and other structural stiffeners can be located inside the cavity of the vault panel, and vault 5 may consist of several independent water-cooled burner panels with a different number of tuyeres and technological holes. In tuyeres 6 of vault 5, fuel-burning devices are installed - gas burners or nozzles 9, the torches of which interact rigidly with the solid hearth 2, informing them of heat spots 10. When using refractory or coarse-grained batch, it is advisable to use high-pressure heating, with a jet flow rate above 100 m / c, in order to avoid erosion of the hearth, a protective layer is formed on the latter from molten iron loaded into the furnace in the form of scrap metal, or by reduction of iron silicates from the mixture. To maintain the appropriate level of liquid metal in the melting section of the hearth, the profit of molten iron is continuously drained through the side or end walls of the furnace using a special notch 11 and a settling pocket 12, which communicates through the bottom flow 13 with the melting section 14 of the hearth 2. In order to increase the efficiency heating in the melting zone, the furnace contains false walls 15, which enclose local volumes of the furnace space, smoke channels can be provided in the false walls to divert the products of fuel combustion in smoke conductive path 16.

The process of melting chargeless melting can be illustrated by the following example. To obtain the melt, natural glasses are used - volcanic rocks, unsaturated with silicon dioxide / from 52 to 40% / basalts, diabases, gabbro, porphyrites having, for example, the following basic chemical composition,%: SiO ₂ - 48-51; Al ₂ O ₃ - 10-13; Fe ₂ O ₃ - 13-17; CaO - 10-14; MgO - 2-5. The fractional composition of the charge is set within 10 ... 50 mm. Lump mixture require more stringent shock-jet heating at a torch speed at the burner nozzle exit of 100 ... 250 m / s. The mixture is loaded into the furnace either periodically dosed by weight in portions, or continuously, for example by vibro-brook feed, through the arch hole. In this case, the general principle of loading is the supply of the mixture to the heat spots, in the epicenter of heating. Only under this loading condition is the greatest effect of convective heat transfer from the torch to the charge achieved. Heat spots are not a conditional concept of the proposed method, they are clearly indicated on the general high-temperature field of the hearth melting zone. Varying the conditions of fuel combustion / heating of air, gas, enrichment of a gas-air mixture with oxygen, etc. / it is possible to conduct melting in a wide heating range - 1700 ± 250 ° C. In this case, it is necessary to constantly monitor the continuity of the coating with the mixture of heat spots, to reduce the thermal power of the burners in case of failures in the bootloader or forced downtime of the furnace. Fluctuations in the thermal stresses of the furnace space do not entail the need to tighten or dissolve the vaulted ceiling.

A feature of melting by the method of shock-jet heating is the requirement to limit and localize the furnace space by means of fences made of false walls, which act as high-temperature beam screens, i.e. sectioning into melting zones. Properly organized heating by high-speed burners makes it possible to regulate the redox environment in each section of the hearth smelting zone, which is very important for melts from iron-containing rocks. The sectional principle of building a melting furnace allows one to achieve high heat stresses in the melting zone and to obtain a heating temperature that is much higher than the heat resistance of the walls and arch, without jeopardizing them, since when the hearth is heated by a torch with a directional torch, the coefficient of heat transfer to the charge by convection is greater than to masonry . The convective component of heat transfer in this case can reach 80% / 5 /. The false walls inside the furnace are laid out from refractory materials of increased heat resistance, for example, from chromium oxide, the temperature of use of which with prolonged heating can reach 1800 ° C. The gap between the false walls and the walls of the furnace is 0.1 ... 2.5 of the average diameter of the heat spots, the lower limit values correspond to the thermal expansion of the wall masonry, and the upper limit values relate to the gaps between the walls localizing the melting zone, beyond which the convective heating coefficient decreases sharply. The mixture melts on a horizontal or pitched bottom with an angled slope. The purpose of the slopes and the angle of their inclination are related to the intensity of the melt discharge into the working duct, and is also due to specific technological tasks: operation of the furnace on one or two production lines, increase or decrease the time of thermal or chemical homogenization of the melt, the purity of separation of the melt from refractory impurities, and t .P.

The life of the hearth in the melting zone can be significantly increased if the charge is loaded onto the grate - ledges of various geometric shapes in the form of separate easily replaceable elements cast from high-chromium alloys. In this case, the choice of alloy composition must be approached taking into account the operating temperature, mechanical load, and other conditions, in particular, the gas medium of the torch. Studies / 8 / showed that in terms of heat resistance, an iron-chromium alloy with a chromium content of 35% surpasses alloys with a higher chromium content, up to 75%, but in terms of strength characteristics, high-chromium alloys have significant advantages over low-chromium alloys. In addition, alloys with a chromium content of 35% have maximum fluidity - all this also needs to be taken into account when designing welded-cast or solid-cast structures. In our example, the most loaded elements are the grates, and the vertical channel at the end of the working tray, it is desirable to cast these elements with their high-chromium composition, and the bottom and the tray - from an alloy with a lower chromium content.

In addition to the localization of the melting zone, the distance from the arch / entry of the torch torch / to the hearth is of great importance for a vannless melting method, i.e. zone of formation, hot spots. In the proposed technical solution, the vault height parameter "H" is associated with the diameter of the formed heat spot "D" by ratios within the interval 0.5 ... 4.0. The lower limit is designed for heaters with a short or flat torch, and the upper one is focused on long-torch and high-speed burners.

The furnace free melting rock of the rocks according to the proposed method was built at JSC "Sudogodsky fiberglass", the city of Sudogda, Vladimir region. and is currently in pilot commercial operation for the production of thin and superthin fiber according to the filterless technology, with a productivity of 100 ... 200 kg / h.

The trenchless method of rock melting makes it possible to start using the inexhaustible reserves of Russian basalt raw materials, potentially suitable for obtaining fibers that are unique in their physicochemical properties, but have been practically unclaimed until now because of the high content of refractory impurities - /12...15%/ - quartzites, plagioclase and other minerals, the melting temperature of which is 400 ... 500 ° C higher than the temperature of the liquid-flowing state of the base melt. All this is the main reason that the Russian market for the production of thin and superthin fibers is dominated by relatively clean from impurities, but expensive because of the customs and transport margins of the Ukrainian basalts, and quartz Russian ones are used mainly as crushed stone and for adding roads . With the introduction of the girderless method of producing melt from rocks, Russian basalt, as a local cheap raw material, will find application in technologies for the production of environmentally friendly and durable insulation for civil and industrial construction and continuous threads for composite materials.

As another example of the use of the proposed method, the real process of obtaining the melt from the diabase porphyrites of the Bugotak deposit "Stone quarry", pos. Gorny, Novosibirsk region / 9 / at JSC "Sudogodskoe fiberglass" in the production of thin and superthin fibers.

Chemical composition, %:

SiO ₂ 43.57-47.7; Al ₂ O ₃ - 11.5-16.3; Fe ₂ O ₃ - 11.69-15.2; CaO 9.26-12.0; MgO - 6.4-13.8.

Mineralogical composition,%:

Albitized plagioclase - 57-68

Augit - 20-25

Actinolite - 4-14

Chlorite - 6-8

Epidote - 5-6

Sericite - 1-4

Magnetite - 1

From the above list of minerals, the whole group is practically refractory with varying degrees of heat resistance. However, the high content in the charge of glass-forming oxides of silicon, calcium and strong flux-thinning agents / iron silicates, magnesium / makes the melt of diabase porphyrites quite fluid and technologically advanced in fiber processing. Due to the fact that the hearth in the furnace is tilted towards the mine, fast gravitational continuous leaving of the formed base melt is ensured, and heat-resistant minerals, mostly not having time to eutectically dissolve, are deposited / remain / on a solid hearth, with which they are easily removed as they accumulate through technological windows using steel scrapers.

Sources of Patent Technical Information

1. Thin-layer glass melting. In the book. Glass technology. Total ed. I.I.Kitaygorodsky. M. Publishing House Building Literature. 1967, p. 105-108.

2. The method of cooking mineral raw materials. Auth. testimonial. USSR No. 1208023.

3. Patent No. 4564379, USA, 1986

4. Bark S.E. and others. High-speed gas heating of cylindrical billets of aluminum alloys. Zhl "Technology of light alloys. No. 1, 1976, S. 72-78.

5. Asstaturov et al. High-speed jet heating of metal. Publishing house "Technique", Kiev, 1984, p. 77-97.

6. Melting furnace. Auth. testimonial. USSR No. 284255, 1968 / prototype /.

7. 3 application No. 200113064 for a patent of the Russian Federation dated 10.12.2001

8. "Development of a heat-resistant alloy, structures and manufacturing technology for elements of the unit for issuing and blowing the mineral melt into a superthin fiber." The final report on x / d No. 1830 dated 02.12.1985, IPL AS USSR.

9. Information on the mineralogical and chemical composition of diabases and diabase porphyrites. AOOT "Stone quarry", 633411, Novosibirsk region pos. Mountain.

Claims (14)

1. The method of melting volcanic rocks containing refractory impurities, including loading and melting the mixture on a solid base with continuous gravitational selection of the melt for delivery, characterized in that the mixture is melted on overheated local areas of the solid base - heat spots, which are formed using directional shock -jet heating at a temperature of (1700 ± 250) ° C, moreover, the charge on the heat spots is dosed with a thin layer and / or in the form of lump, and the resulting melt is continuously separated from refractory impurities by depositing non-melt on a solid base with periodic removal from the furnace using a scraper. 2. The method according to claim 1, characterized in that one heat spot is formed by at least two shock-jet streams. 3. The method according to any one of claims 1 and 2, characterized in that on a solid base, locally or over the entire area of the melting zone, to protect the hearth from being washed away by a high-speed torch, leave a constant layer of reduced metal. 4. The device for implementing the method of melting volcanic rocks according to claim 1, including a furnace with a arch and a ceramic inclined single-hearth furnace, a charge loader, burners for burning hydrocarbon fuel with a flue system, a production tray mounted inside the furnace with a channel with a vertical channel at the end, under by which a cone-shaped opening for melt discharge is formed in the hearth, characterized in that the hearth or part thereof is laid horizontally, and the furnace arch is water-cooled in the form of at least one a burner panel, welded from sheet steel, with cylindrical mounting lances, technological holes for loading the charge, measuring temperatures, taking gas and slag samples, the panel is lined on the fire side with a lightweight heat-insulating refractory, mounting grips and longitudinal-transverse ribs are made on the outside of the panel rigidity, and in tuyeres burners are installed for burning gas and / or liquid fuel, the torch of which interacts with the hearth of the furnace at a collision speed of 30 ... 250 m / s and ratios of the height yes "N" to the average diameter of the hot spot "D" within, N / A: 0.5 ... 4.0. 5. The device according to claim 4, characterized in that the arch or part of the arch is made with an inclination in accordance with the profile of the hearth. 6. The device according to claim 5, characterized in that gas lances of shock-jet heating with a rated thermal power of 100 ... 1200 kW are installed in the tuyeres of the roof at a velocity of expiration of the combustion products at the nozzle exit 160 m / s. 7. A device according to any one of claims 4 to 6, characterized in that at least one massive reflective false wall of highly refractory material is installed inside the furnace parallel to the main walls, the gap between the walls being 0.1 ... 2.5 of the average value diameter of the hot spot. 8. A device according to any one of claims 4 to 7, characterized in that the hearth of the furnace in the charge melting zone is partitioned off with a slag shutter with a partial deepening into molten metal and equipped with a tap hole for discharge. 9. The device according to any one of claims 4 to 8, characterized in that the hearth is made with a slope of two slopes, the skate ridge being common and located in the transverse and / or longitudinal sections of the hearth. 10. The device according to any one of claims 4 to 9, characterized in that the slopes of the slopes of the bottom are oriented oppositely to each other, and their lower ends are adjacent to the common working tray. 11. The device according to any one of claims 4 to 10, characterized in that the slopes of the gable bottom are oriented in opposite directions to the individual production trays. 12. A device according to any one of claims 4-11, characterized in that the hearth or its individual sections are provided with grate ledges and / or partitions in the form of truncated pyramids, cones, hemispheres, gratings, or other geometric shapes made of welded cast iron-chromium alloy with a chromium content of 35 ... 75%. 13. The device according to any one of paragraphs.4-12, characterized in that the development tray is made of welded cast iron-chromium alloy with a chromium content of 35 ... 75%. 14. The device according to any one of claims 4 to 13, characterized in that the hearth of the furnace is laid out of chromoxide ceramic refractories with a chromium oxide content of 92.5 ... 96.0%.

Images