RU2082684C1 - Method and apparatus for manufacturing product from glass-forming melt (versions) - Google Patents

Abstract

FIELD: glass industry. SUBSTANCE: scope of invention covers manufacturing objects from glass-forming melts, for example, mineral and refractory wool and fibers, and immobilization of harmful industrial wastes. Method is realized by way of loading and melting initial raw material in induction furnace with cooled bowl, heat treatment of melt including superheating and attaining turbulent flow mode of melt in melting zone, and cooling and attaining laminar flow mode of melt in output zone with subsequent conversion of melt into product. Method is distinguished with that turbulent flow of melt is attained by overheating melt by 400-1000 C in relation to melt liquid temperature or melt crystallization upper limit temperature. Relative size of melt in melting zone is chosen in the range presented in description of invention. Laminar flow mode of melt is attained by way of lowering intensity of magnetic field of field magnet in output zone by 30-90% in relation to its value in melting zone. Apparatus includes induction furnace consisting of cooled metallic bowl and field magnet, raw material loading mechanism, and means for manufacturing product from glass- forming melt. Bowl is provided with melt discharge means and barrier separating bowl into melting and output zones. Filling coefficient of field magnet window in melting zone is determined from formulas presented in description. Similar coefficient for output zone is 1.4- 3.0 times lower. EFFECT: improved design of apparatus and optimized operation parameters. 7 cl, 4 dwg, 1 tbl

Description

 The invention relates to the production of products and products from glass-forming melts, for example, mineral and refractory wool and fibers, immobilization of environmentally harmful production waste, production of products using production waste based on glass-like materials and similar products. The invention can be used in the construction industry, as well as in solving environmental problems of the disposal and disposal of harmful inorganic substances, including radioactive ones.

 A known method of producing mineral fibers from silicate melt [1] which consists in melting in a cupola the feedstock, including the mineral part and coke, homogenizing the glass-forming melt, releasing the melt into a piggy bank and releasing the melt into a fiberizing agent, followed by obtaining the product in the form of mineral wool.

A device for implementing the method consists of a cupola having a lined shaft, a water jacket, tuyeres and a notch, a piggy bank, fiber forming means and a loading mechanism [1]
The disadvantages of the method are that the glass-forming melt obtained in the cupola has instability of characteristics due to the impossibility of precise control of the melting process of raw materials. As a result, product quality is poor.

 A known method of producing glass fiber using special glass vessels [2] the Method consists in melting the glass, heat treatment of the melt by dividing the melt stream into central and peripheral flows, additional heating of the peripheral stream and mixing the flows, followed by the issuance of the melt in the fiber formation tool.

The method is implemented on special spinneret glass melting vessels having peripheral melting chambers, which are equipped with additional heaters [2]
The disadvantage of this method is the low melting rate of the raw materials and insufficient homogenization of the glass-forming melt in the melting zone, caused by the inability to significantly overheat the melt in the glass melting vessel. Improving the productivity and improving the homogenization of the melt is achieved by increasing the residence time of the melt in the melting vessel, i.e. by increasing the mass-dimensional characteristics of the device.

 A known method of processing waste containing heavy metals [3] The waste is crushed, crushed and mixed with glass waste. Briquettes are formed from the mixture under pressure and high temperature, which are fed to the melting device. The molten mass is subjected to rapid cooling. The resulting slag-like material is used in construction.

A device for implementing the method consists of a mill, a mixer, a dispenser of the mixture, a press with a high-temperature heater, a melting chamber and means for producing the product from the melt [3]
The disadvantage of this method is the lack of a step for the synthesis of a glass-forming melt during waste treatment. As a result, the glass polymer structure does not form in the product and highly toxic heavy metals are leachable by water and pass from the product to the environment.

 Closest to the proposed one is a method for producing a product from glass-forming melts [4] The method consists in feeding and melting the feedstock in an induction furnace with a cooled metal crucible, heat preparing the glass-forming melt by overheating it in the melting and cooling zone in the production zone and then releasing it to means of obtaining the product.

 A device for implementing a method for producing a product from glass-forming melts [4] will restrain an induction furnace consisting of an inductor and a metal cooled crucible equipped with a drain toe and a baffle separating the crucible into communicating melting and working zones, a feed mechanism and a means of obtaining the product from the glass-forming melt.

 The disadvantage of the prototype method is the deterioration of product quality due to incomplete synthesis of a glass-forming melt in the production zone. At the same time, when trying to achieve optimal conditions for the synthesis of a glass-forming melt in the production zone, the melting rate sharply decreases and the technical and economic indicators of the device fall, and melt homogenization is not achieved. In this mode of the process, the quality of the product decreases and a loss of controllability of the process and uncontrolled termination of melting are possible.

 The aim of the invention is to improve the quality of the resulting product by local intensification of the melting process and the synthesis of glass-forming melt, respectively, in the melting and production zones.

 The goal is achieved by the fact that in the known method of producing a product from glass-forming melts, including the operation of feeding and melting the feedstock in an induction furnace with a cooled crucible, thermal preparation of the melt by overheating in the melting and cooling zone in the production zone and its subsequent delivery to the product preparation means , thermal preparation of the melt in the melting zone is carried out in the mode of turbulent melt flow, and cooling is carried out in the mode of laminar melt flow.

в которой f частота тока источника питания печи, Гц, κ - электропроводность расплава в зоне плавления при заданной температуре, Ом/м,
μ_o= 4π•10^-7 Гн/м магнитная проницаемость вакуума.The turbulent flow of the melt is achieved by heat treatment of the melt, overheating it in the melting zone at 400-1000 ^o C relative to the temperature of the upper limit of crystallization of the melt or liquidus temperature, while the relative melt size K _m in the melting zone is selected within the limits: for a circular cross section of the melting zone 6 , 0-14.0, for unequal and square cross-section of the melting zone 4.0-8.0,
K _m = D / Δ (I)
where D is the characteristic size of the melt in the melting zone, m,
Δ depth of current penetration into the melt in the melting zone, m, determined by the formula

in which f is the frequency of the current of the furnace power source, Hz, κ is the conductivity of the melt in the melting zone at a given temperature, Ohm / m,
μ _o = 4π • 10 ^-7 GN / m the magnetic permeability of vacuum.

 The laminar flow of the melt is achieved during the heat treatment of the melt with a decrease in the magnetic field strength of the inductor in the production zone by 30-90% relative to its value in the melting zone.

 The proposed method is implemented using two device options.

причем K_m выбирают в диапазоне 6,0-14,0, для неравноосного и квадратного поперечного сечения плавильной зоны
K_з≥0,57K_m 0,4K_a + 0,11G(2,1+K_a) 2 (4)
причем K_m выбирают в диапазоне 4,0-8,0,
где K_a=0,1-0,4 эмпирический коэффициент.The first version of the device for implementing the method contains, as well as the known, an induction furnace consisting of an inductor and a metal cooled crucible, equipped with a melt dispensing device and a partition separating the crucible into communicating melting and working zones, a raw material supply mechanism and a product preparation means. The difference between the device is that the fill factor of the inductor window K ₃ in the melting zone is selected by the formulas:
for a circular cross section of the melting zone

moreover, K _m choose in the range of 6.0-14.0, for unequal and square cross-section of the melting zone
K _s ≥0.57K _m 0.4K _a + 0.11G (2.1 + K _a ) 2 (4)
moreover, K _m choose in the range of 4.0-8.0,
where K _a = 0.1-0.4 is an empirical coefficient.

G≥1 parameter equal to the ratio of the dimensions of the cross section of the melting zone,
K _m - the relative size of the melting zone, determined from the ratio
K _m = D / Δ (5)
D is the characteristic size of the melting zone, m,
Δ depth of current penetration into the melt in the melting zone, m, determined by the formula (2).

The second version of the device for implementing the method contains, as well as the known, an induction furnace consisting of an inductor and a metal cooled crucible, equipped with a melt dispensing device and a partition separating the crucible into communicating melting and working zones, a raw material supply mechanism and a product preparation means. The difference between the device is that it is equipped with a short-circuited electric circuit, electromagnetically connected to the part of the inductor covering the production zone, and the fill factor of the inductor window K ₃ in the melting zone is performed according to formulas (3) or (4).

 The characteristic dimensions of the melt in the melting (loading) zone and the melting zone itself are the diameter or side of the load adopted in the theory of induction heating or crucibles with a round or square cross section or a smaller cross section if it is uneven, but has the shape of a rectangle, oval or other shapes . Considering that the thickness of the skull in the melting zone is much smaller than the characteristic dimensions of the melt and the melting zone of the crucible, they can be considered the same and the characteristic size of the melting zone can be taken as the characteristic size.

При реализации заявленных способа и вариантов устройства в зоне плавления создают условия для интенсивного плавления и гомогенизации расплава под воздействием турбулентных потоков. При поступлении расплава в зону выработки осуществляется его охлаждение и обеспечивают образование ламинарного потока расплава к приспособлению выдачи. В зоне плавления в результате перегрева расплава осуществляется интенсивная теплопередача к слою сырья на зеркале расплава, а под действием турбулентных потоков происходит интенсивный перенос расплавляемого сырья в объем расплава. Под воздействием высокой температуры происходит термическая диссоциация вещества вплоть до элементарных ионов, что обеспечивает интенсивность гомогенизации расплава, а по мере охлаждения расплава в зоне выработки происходит синтез стеклообразующих комплексов, например, на основе кремнозема
Si_nO $\genfrac{}{}{0ex}{}{\text{(2n+2)-}}{\text{3n+1}}$ ,
которые в ламинарном потоке выстраиваются в линейные цепи вдоль потока расплава, обеспечивая высокую степень синтеза стеклообразующих комплексов и включение в структуру стекла других ионов расплава. Достижение такого режима интенсифицирует процесс плавления. Подготовленный таким образом расплав обеспечивает высокие эксплуатационные свойства продуктов, получаемых после обработки расплава.As the fill factor of the inductor window K _{3 of the} induction furnace with a cooled metal crucible, take the ratio of the cross-sectional area of the corresponding crucible zone F to the cross-sectional area of the inductor window S _{1 of the} corresponding zone minus the total cross-sectional area of the crucible tubes S _T in this zone:

When implementing the claimed method and device options in the melting zone, conditions are created for intensive melting and homogenization of the melt under the influence of turbulent flows. When the melt enters the production zone, it is cooled and the laminar flow of the melt is formed to accommodate the output. In the melting zone as a result of overheating of the melt, intense heat transfer to the layer of raw materials on the melt mirror is carried out, and under the influence of turbulent flows, the molten raw materials are intensively transferred to the melt volume. Under the influence of high temperature, thermal dissociation of the substance occurs up to elementary ions, which ensures the intensity of melt homogenization, and as the melt cools in the production zone, glass-forming complexes, for example, based on silica, are synthesized.
Si _n O $\genfrac{}{}{0ex}{}{\text{(2n + 2) -}}{\text{3n + 1}}$ ,
which in a laminar flow are arranged in linear chains along the melt flow, providing a high degree of synthesis of glass-forming complexes and the inclusion of other melt ions in the glass structure. Achieving this regime intensifies the melting process. Thus prepared melt provides high performance properties of the products obtained after processing the melt.

The physicochemical processes taking place in the melting and synthesis zones can be described as follows. As a result of significant overheating of the glass-forming melt at the first stage of thermal preparation, thermal destruction of large ionic complexes of the melt to simple ions of the type: Si occurs $\genfrac{}{}{0ex}{}{\text{4-}}{\text{4}}$ Al $\genfrac{}{}{0ex}{}{\text{1-}}{\text{2}}$ , AlO ¹⁺ , Ca ²⁺ , O ^2-, and the like. The melt viscosity, surface tension are reduced, and the electrical conductivity increases. Simultaneously with the achievement of the indicated structural state, the glass-forming melt is brought into a state of turbulent motion of flows. In the proposed technical solution, this is achieved by local overheating of 25-55% of the melt volume in the melting zone at 400-1000 ^o C relative to the temperature of the upper crystallization limit or the liquidus temperature of the melt of the processed material. In this case, a set of necessary conditions is achieved, including the physicochemical state of the melt, the hydrodynamic conditions for the appearance of melt flows and the electromagnetic effect of the inductor field on the melt, which lead to a turbulent flow of the melt.

 The essence of the technical solution is as follows. From experimental observations, it was found that the turbulent melt flow in the crucible occurs upon overheating of no more than 55% of the melt volume. It is known that 90% of the energy of the electromagnetic field of the inductor is released in the melt at a depth of current penetration into the melt. Therefore, one of the conditions for the emergence of a turbulent melt flow is that the relative size of the melting zone is such that the volume of the melt covered by the current penetration depth with respect to the volume of the melt in the melting zone is not more than 55%. It follows that the minimum value of the relative characteristic size of the melt in the melting zone should be as follows: for a circular cross section of the melting zone 6.0, for unequal and square 4.0.

It was also found that for glass-forming melts prone to complex formation, the emergence of a turbulent melt flow occurs when the melt overheats by at least 400 ^o C relative to the upper crystallization limit of the melt or its liquidus. The indicated overheating of the melt is its true liquid state, and the concentration of the electromagnetic field of the inductor at the periphery of the melting zone creates local overheating of part of the volume of the melt, leading to the appearance of strong convective melt flows. In addition, the interaction of the currents induced in the melt with the electromagnetic field of the inductor causes electromagnetic mixing of the melt, which affects the stronger, the higher the conductivity of the melt, i.e. the higher the overheating of the melt.

 Significant overheating of the melt and the turbulence of its flows provide intensive clarification of the melt, the release of the melt from crystallization centers, and a high degree of its homogenization.

 If the volume of the superheated melt is more than 55% of the melting zone, there are no hydrodynamic conditions for the formation of a turbulent melt flow, but a general increase in the temperature of the melt occurs.

If the volume of the superheated melt is less than 25% of the volume of the melting zone, the heat release is not enough to maintain the melt in the entire volume of the melting zone, in the central regions of the zone, the raw material may not melt, crystallization centers in the melt may appear, its inhomogeneity, which leads to a deterioration in product quality. This melting mode is achieved when K _m more than 14 for a circular cross section of the melting zone and more than 8 for unequal or square cross-section.

Overheated and homogenized melt enters the production zone under the influence of mass transfer caused by the outflow of the melt from the furnace. In the production zone, the melt is subjected to cooling, for example, by increasing heat transfer to the walls of the crucible or otherwise, and a laminar flow of the melt is organized to the place of its generation. Moreover, the laminar flow of the melt can be achieved by known methods, creating, for example, a channel of motion of the melt. However, the presence of an electromagnetic field in the production zone from the surrounding inductor makes it difficult to obtain a laminar melt flow. In the generation zone, both the release of Joule heat, causing convective melt flows, and the appearance of electrodynamic forces, which prevents the formation of a laminar flow, occur. A decrease in the magnetic field strength of the inductor in the production zone compared to its value in the melting zone changes the ratio of forces between the laminar flow of the melt caused by mass transfer and the above-mentioned forces that distort the laminar flow. There are conditions for the formation of a laminar flow without additional structural elements. Typically, the melt temperature in the production zone is lowered to values that exceed the upper crystallization limit or the liquidus temperature by 50-250 ^o C. At this temperature, intensive melt complexation occurs, and its laminar flow contributes to the formation of the polymer structure of the glass-forming melt. In addition, a decrease in the temperature of the melt in the production zone leads to a decrease in the electrical conductivity of the melt in the zone and, therefore, to an increase in the depth of penetration of the current in the melt. Thus, since the ratio between the volume of the induction-heated melt and the volume of the melt in the zone increases, one more condition for the appearance of a turbulent melt flow in the zone is excluded, which contributes to the formation of a laminar melt flow in the production zone.

 With an increase in the degree of overheating of the melt in the melting zone, it is necessary to reduce to a greater extent the magnetic field strength of the inductor in the production zone, since with increasing melt temperature the electromagnetic forces acting on the melt increase. If the device provides a large mass outflow of the melt stream, it is necessary to reduce the magnetic field by 90% of its value in the melting zone, since, in addition to reducing the effect of the field on the melt stream, cooling of the melt is required due to a decrease in the Joule heat in the production zone. At a high mass velocity of the outflow of the jet, the enthalpy of the melt entering the production zone is sufficient to maintain the substance in the liquid state zone practically without supplying energy from the inductor. In the case of small mass outflow of the melt from the working zone, the magnetic field strength in the working zone should be reduced by 30-40% of its value in the melting zone. With a decrease in the magnetic field strength of the inductor in the production zone by less than 30%, it is not possible to obtain a laminar melt flow, which leads to a deterioration in the quality of the melting product.

 Implementation of the claimed method for producing a product from glass-forming melts is carried out using device options.

The essence of the technical solution for choosing the parameters of the melting zone of the furnace in the first and second variants of the device is identical and consists in the following. To realize overheating of the glass-forming melt in the range of 400-1000 ^° C, the characteristic size of the melting zone is selected from expression (5) taking into account the corresponding range of K _m . However, this condition is necessary, but insufficient for the implementation of the method. A sufficient condition for the implementation of the method is to provide stability conditions for a given range of melt overheating in the melting zone. This condition is realized by choosing the fill factor of the inductor window in the melting zone in accordance with empirical expressions (3) or (4), which are obtained as a result of a generalization of experimental experience. Moreover, when calculating these ratios, the value of the melt conductivity is taken at the minimum temperature of the overheating range specified by the technological requirements, and if it is not specified, then at a temperature corresponding to 400 ^° C of the melt overheating.

 The fulfillment of the fill factor of the inductor window in the melting zone in accordance with relations (3) and (4) ensures a stable state of the melting process, without going beyond the boundaries of the conditions of occurrence of a turbulent melt flow. In this case, higher values of the overheating of the melt in the melting zone reach an increase in the power supplied to the melt (an increase in the voltage across the inductor).

The maximum value of K ₃ , determined from relations (3) and (4), reflects the inadmissibility of the ratio of the volume of the superheated melt and its volume in the melting zone of less than 25%, which corresponds to the maximum value of K _m = 16 and K _m = 8, respectively, for round and unequal sections of the melting zone. Often in practice, the limitation of the increase in K ₃ is to ensure the electric strength of the gap between the crucible and the inductor.

The empirical coefficient K _a reflects the influence of the depth of the melt pool in the melting zone on the value of K ₃ and can be determined from the relation
K _a = 0.18D / a _b
where a _{b is the} depth of the molten bath, which is approximately equal to the depth of the crucible in the melting zone.

 Thus, the interdependent determination of the device parameters makes it possible to realize and stably maintain a turbulent melt flow in the melting zone.

 In the first embodiment of the device, performing the fill factor of the inductor window in the production zone is 1.4-3.0 times less than in the melting zone, they provide a decrease in the magnetic field strength in the production zone by 30-90% since induction furnaces for melting oxide materials have high operating frequency of the current, the reactance of dispersion of the air gap is a significant part of the resistance of the inductor and is proportional to the cross-sectional area of the gap, i.e. inversely proportional to the fill factor of the inductor. Therefore, a decrease in the fill factor of the inductor in the production zone by 1.4 times leads to a decrease in the magnetic field strength by about 30% of its value in the melting zone. With a further decrease in the fill factor of the inductor window, an almost linear decrease in the magnetic field intensity occurs. A three-fold decrease in the fill factor ensures a decrease in the magnetic field strength to 90%. This eliminates the disturbing effect of the electromagnetic field of the inductor on the melt flow in the working zone and achieves a laminar melt flow to the melt dispenser.

 A decrease in the fill factor of the inductor in the production zone by more than 3 times does not significantly reduce the magnetic field strength of the inductor, but significantly increases its equivalent resistance, therefore it is inefficient.

 Thus, by changing the electromagnetic field of the inductor in the production zone by selecting the furnace parameters, a laminar melt flow is formed, thereby achieving an increase in product quality.

 The essence of the technical solution of the second variant of the device for implementing the proposed method lies in the fact that, along with the fulfillment of the furnace parameters in the melting zone, similarly to the first variant, decreasing the magnetic field strength of the inductor in the generation zone is achieved by placing a short-circuited electric circuit, which is electromagnetically connected to the part of the inductor located at the production zone. Due to electromagnetic coupling, a current is induced in the circuit, causing the electromagnetic field of the circuit with a direction opposite to the field of the inductor in the production zone. It is essential that the short-circuited circuit is electromagnetically connected only with the part of the inductor, the electromagnetic field of which acts on the production zone. This eliminates the influence of a short-circuited circuit on the electromagnetic field of the inductor in the melting zone and the conditions for the formation of a turbulent melt flow in the melting zone remain unchanged. Otherwise, with the mutual induction of the entire inductor with a short-circuited circuit, the electromagnetic field in the melting zone changes and a turbulent melt flow is not formed. By choosing the configuration of the circuit, its position relative to the inductor and the working zone, they achieve a decrease in the magnetic field strength in the working zone by 30-90% relative to its value in the melting zone. Reducing the magnetic field by more than 90% is practically not enough, because the coefficient of mutual induction of the inductor and the circuit is always less than unity.

 The execution of the circuit with the ability to move allows you to debug the optimal value of the magnetic field in the production zone directly in the process of obtaining the product.

 In the case of a large mass emission of the melt and the need for a significant reduction in the magnetic field, the circuit is placed in the melt volume of the working zone. In this case, a maximum decrease in the magnetic field of the inductor in the production zone is achieved.

 The inclusion in the electrical circuit of the circuit of the structural elements of the crucible, forming a zone of development, and / or partitions, as its parts, allows you to combine the functions of the partitions and the elements of the crucible and the contour in one structural element.

 Thus, the analysis of physicochemical and electrochemical phenomena occurring during the implementation of the method shows that the use of the claimed method and device variants qualitatively changes the mechanism of melting, homogenization and complexation of the glass-forming melt in the furnace, thereby improving the efficiency of these processes and improving the quality of the resulting product . This indicates a solution to the problem of the invention and the availability of novelty of the claimed technical solutions.

 Induction furnaces with a cooled metal crucible and an outlet sock for dispensing a melt are known in electrothermics.

Known recommendations for choosing the parameters of such furnaces. The recommendations are based on the incomplete interdependence of the inductor-melt parametric system for the stability of a given melting mode. In this regard, recommendations are given for choosing a stable mode only on the basis of the condition for the size of the furnace and the depth of current penetration into the melt. The range of the diameter of the crucible from 2.7 to 7.0 is indicated as a stable range of operation of the device, which in our case corresponds to the relative size of the crucible for a circular cross section from 3.8 to 9.9. However, since the recommendations for choosing K _{3 are} not related to the stability of the melting mode, this does not provide the desired mode. When implementing a device for producing a product from glass-forming melts using the above recommendations, it is not possible to obtain a stable state of melting under given conditions: either the required level of melt overheating in a stable state of melting is not achieved, or a turbulent melt flow in the melting zone is not achieved, or both of these melting mode parameter. In addition, in the production zone it is not possible to obtain a laminar melt flow due to the action of the inductor on the melt in this zone, similar to the effect on it in the melting zone. Therefore, to solve the problem of the invention, well-known recommendations for selecting device parameters are unsuitable.

 The claimed technical solutions, due to the identification of new interdependencies between the structural parameters of the device and the modes of the method, formulated in the form of empirical relationships, ensure the implementation of the method with the achievement of the modes indicated in it.

 Induction furnaces are known in electrothermics, equipped with an electric short-circuited circuit, electromagnetically coupled to an inductor. In the known device, a short-circuited circuit reduces the magnetic field strength in the lower part of the melt bath, providing a reduction in melt overheating. This reduces the likelihood of melt flowing to the walls of the crucible and improves the shaping of the surface of the refractory block.

 In the claimed device there is a similar sign to a well-known one - a short-circuited electrical circuit. However, the circuit in the claimed device is electromagnetically coupled to a part of the inductor covering the production zone. This device gains a new quality: two zones are formed in the same furnace with turbulent and laminar melt flows.

 In FIG. 1 shows a diagram of a first embodiment of the proposed device, a longitudinal section; figure 2 is the same, a cross section; figure 3 diagram of a second variant of the proposed device, a longitudinal section; figure 4 is the same, cross section.

 The drawings show: 1 metal cooled crucible assembled from tubes cooled by water; 2 inductor connected to a power source (not shown); 3 device for issuing a melt, made in the form of a drain sock; 4 a partition dividing the melting zone 5 and the working zone 6; 7 - feed mechanism; 8 - a means of obtaining the product from the melt; 9 layer of raw materials on the mirror of the baths of the melt in the melting zone; 10 skull; 11 jet of melt; 12 product received; 13 turbulent melt flows in the melting zone; 14 laminar melt flows in the production zone; 15 - electrical short-circuited circuit.

 The arrows in the drawings show the supply and discharge of cooling water.

Example 1. Obtaining mineral fiber from the volcanic rock gabbro. The average chemical composition of the rock is as follows, wt. SiO ₂ 50.0; Al ₂ O ₃ 17.0; CaO 10.0; MgO 7.0; Fe ₂ O ₃ + FeO 10.0; Na ₂ O + K ₂ O 4.0; other 2.0. When the rock is melted, a glass-forming melt with an upper crystallization limit of 1240 ^° C is formed. Based on the experimental data, the optimal temperature range of the melt for fiber production is 1370-1450 ^° C. The melt conductivity in the range of 1400-2200 ^° C is approximated by the dependence of the form log κ -2936 / T +1.488 (T in degrees K). The feedstock was prepared by crushing the rock to fractions of less than 3 mm.

The melt overheating would be set in the range of 600-800 ^o C relative to the temperature of the upper limit of melt crystallization, i.e. the technological range of the melt temperature is 1840-2040 ^o C. The range of the temperature of the melt when it is discharged from the furnace is 1400-1450 ^o C.

 To obtain fiber, a 60 kW furnace power source and an operating frequency of 1.76 MHz were used. The cross section of the melting zone of the furnace was chosen round.

In accordance with the technologically prescribed minimum temperature of the melt in the melting zone of 1840 ^o C the conductivity of the melt is 125 Ohm / m Assuming a value of K _m = 8.5, the diameter of the crucible in the melting zone was determined from relations (5) and (2), which amounted to 0.29 m. The indicated diameter of the crucible is the minimum allowable for the given melting conditions and reflects the condition of melt overheating in a volume of 40 % of the melt volume in the melting zone. The achievement of stability of the melting mode at the minimum temperature is ensured by the fulfillment of K ₃ = 0.876 calculated from relation (3). In the calculations, K _a = 0.4 was taken into account, taking into account that the depth of the melt pool in the melting zone is 0.4-0.5 of D. Structurally, the crucible was made of copper water-cooled tubes of square section with a side of 0.01 m, located on a circle with a diameter 0.29 m and forming a melting zone. The number of tubes in the melting zone was 80 pcs. Given this, the diameter of the inductor in the melting zone was determined from formula (6), which amounted to 0.325 m. The crucible working zone was made narrowing to the melt dispenser, and the fill factor of the inductor window in this zone was 0.47, which is 1.9 times less than in the melting zone.

 To implement the method, the furnace was performed in accordance with the calculations. The crucible 1 (Fig. 1) and inductor 2 had inner diameters of 0.29 and 0.325 m in the melting zone 5, respectively. The working zone 6 of crucible 1 was made in the form of a tapering part of the crucible ending with a melt dispensing device with a drain toe 3 associated with the melting zone 5. The inductor 2 in the working zone differed from the cross-sectional shape of the crucible in this zone. The fill factors of the inductor window in the melting and production zones were 0.88 and 0.47, respectively. The working zone 6 was separated by a partition 4 from the melting zone 5.

 The production of mineral wool was carried out as follows. The raw material was loaded into the crucible 1 using the raw material supply mechanism 7 and melted it by known methods using the inductor 2, forming a melt bath in the melting zone 5. The raw material was continuously fed into the melting zone 5 with a layer 9 on the mirror of the melt bath. As the raw material melted, the melt filled the melting zone 5 and the working zone 6, and its level rose to the level of the drain sock 3. A skull was formed near the walls of the crucible 1 and the partition 4. The melt flowed down along the toe 3 and the jet 11 entered the product receiving means 8, made in the form of a gas nozzle. Under the influence of gas flows from the melt jet, fibers 12 formed, which entered the deposition chamber (not shown). The melting mode turned into a quasistationary state, characterized by the constancy of the parameters of the regime of both the furnace and the power source of the tube generator.

When the lamp generator was operating in the mode with an anode voltage of 9.0 kV and anode current of 6.9 A, a stable state of melting with a melt temperature in the melting zone of 1840-1860 ^o C was achieved. Attempts to reduce the melt temperature to 1400 ^o C led to instability of melting and crystallization of the melt, which characterizes the temperature of 1840 ^o C as the minimum stable melting temperature in the created furnace. An increase in the mode of the tube generator to 10 kV and 9.5 A ensured a rise in the melt temperature to 2030-2050 ^o C. The ratio of the superheated melt volume to the melt volume in the zone was about 35%. The temperature was recorded with a Primin optical pyrometer with complete melting of the layer raw materials 9 on the mirror of the bath of the melt of the melting zone 5.

 A pattern of convective flows 15 with a very fast movement and a change in the configuration of the pattern was observed on the mirror of the melt bath. The ratio between the actively heated volume of the melt and the volume of the melt in the melting zone was from 40 to 35%. Due to the turbulence of the flows in the melting zone, the raw materials were rapidly melted with a productivity of 30-55 kg / h and the melt was subjected to intensive homogenization.

 From the melting zone 5, the superheated and homogenized melt flowed under the baffle 4 into the working zone 6, where it was cooled. The melt was cooled due to incomplete compensation of heat losses from the melt mirror of the zone of generation and heat transfer to the walls of the crucible 1 and the partition 4 with the power released in the zone of generation by the electromagnetic field of the inductor. This was achieved by reducing the magnetic field strength of the inductor in the production zone by 60% compared to the melting zone by reducing the fill factor of the inductor window in the production zone compared to the melting zone. As a result of lowering the temperature of the melt in the production zone, its electrical conductivity decreased, the ratio between the volumes of the heated melt and the melt in the zone reached more than 60%, and the viscosity of the melt increased. Together, these phenomena caused the formation of a laminar flow of melt 14 to the drain toe in the production zone. The presence of a laminar flow of melt 14 is observed visually: the pattern of convective flows has a constant shape with elongated cells in the direction of the drain toe.

 As a result of the implementation of the method obtained mineral wool, the main characteristics of which are given in the table.

Example 2. Obtaining mullite-siliceous fiber. The chemical composition of the mixture to obtain the following fiber, wt. SiO ₂ 48.0; Al ₂ O ₃ 50.0; other 2. The mixture was mixed from alumina and quartz sand. The melt overheating range was set at 800-1000 ^o C. The mullite-siliceous composition has a liquidus temperature of 1800 ^o C. The technological temperature range in the melting zone is 2600-2800 ^o C. At a melt temperature of 2600 ^o C, the melt conductivity is about 50 Ohm / m (according to the extrapolation data at a temperature of 1800-2000 ^o C). The temperature range of the melt when released from the furnace 1860-2000 ^o C.

 A tube generator with a capacity of 500 kW and an operating frequency of 1.76 MHz was used as a furnace power source. The furnace was made with a circular cross section of the melting zone.

analogously to example 1, the parameters of the melting zone of the furnace were calculated according to formulas (5), (2), (3) and (6), taking K _m = 14, K _a = 0.3 as the initial ones. As a result of the calculations, the furnace parameters were obtained: D = 0.76 m, K ₃ = 0.958.

A structural embodiment of the device shown in figure 3 and 4. The crucible 1 was made of copper tubes of rectangular cross-section 0.02 x 0.05 m ² . The diameter of the inductor 2 in the melting zone was 0.816 m. The working zone 6 of crucible 1 was made in the form of a rectangular section of the crucible docked with a circular melting zone 5. A decrease in the magnetic field in the working zone 6 was achieved by placing an electrically closed cooled circuit 15 from the copper tube above the zone, electromagnetically connected with the part of the inductor 2, covering the production zone 6. The dimensions and position of the circuit 15 above the zone was determined from the condition of decreasing the magnetic field strength of the inductor in the production zone 6 by average pared with the melting zone 5 at 70-80% filling factor of the inductor in the window area generation furnace was performed randomly, based on the constructive convenience of the device.

The operation of the device is basically similar to the operation of the device described in example 1. Raw materials using the feed mechanism 7, made in the form of a pneumatic feeder, were continuously fed into the crucible 1. After the formation of the melt bath in the melting zone 5 and the production zone 6, the jet of melt 11 drained from the sock 3 and entered the means of obtaining the product 8. The operation mode of the device passed into quasi-stationary. When the power source was at a level of 80% of the nominal power, the melt temperature in the melting zone reached 2600 ^o C. An increase in the generator power to the nominal one increased the melt temperature to 2800 ^o C. Here intense turbulent melt flows 13 were formed. The volume of the heated melt relative to the melt in the zone was 25-30%. The high temperature of the melt in melting zone 5 and its turbulent flows created the conditions for intensive melting of the charge layer 9 and homogenization of the melt. The productivity of the furnace reached 250-290 kg / h.

 The melt entering the working zone 6 with a high mass velocity had a high enthalpy, which is sufficient to preserve the liquid state of the substance without additional heating. For cooling the melt, the working zone 6 had a length to width ratio of about 2. The short-circuited circuit 15 was electromagnetically connected to the inductor 2 with the part that directly surrounded the working zone 6, which reduced the magnetic field strength in the working zone by 75-80% Electromagnetic field there was practically no inductor in the working zone, however, the electromagnetic field of the inductor in the melting zone remained unchanged. The melt temperature in the working zone decreased, laminar melt flows 14 formed to the outlet tip 3. At the same time, the ion clusters became larger in the melt, and then the mullite-siliceous structure of the fiber formed in the product preparation 8, made in the form of a fiber formation, was synthesized.

The resulting fiber had the following main characteristics: fiber diameter 2.5-3.0 μm, average length 90 mm, bulk density 123 kg / m ³ .

 Example 3. Obtaining mullite-siliceous fiber according to example 2. In the device, the crucible development zone was made in the form of a welded copper cooled structure joined to the crucible melting zone. In this case, the partition separating the melting zone from the working zone was performed in one piece with the crucible working zone. Thus, the crucible development zone and the partition together formed a short-circuited electrical circuit, electromagnetically coupled to an inductor in the development zone. This design of the furnace provided up to 90% relative to its value in the melting zone. During operation of the device, a laminar melt flow in the production zone was formed in a large volume of the zone due to the almost complete absence of the electromagnetic field of the inductor here.

 The resulting fiber in its characteristics did not differ from the fiber obtained in example 2.

Example 4. Immobilization of heavy metals dust of a foundry having an average chemical composition, wt. CaO 14.5; Mn ₂ O ₃ 3.4; Fe ₂ O ₃ 30.0; Cr ₂ O ₃ 5.3; SiO ₂ 42.3; other 4,5. Ecologically dangerous are the compounds of chromium and manganese. When the dust melts, glass-like structures are formed, in the matrix of which chromium and manganese ions are well included. Thus, it is possible to immobilize environmentally hazardous waste without the use of fluxes to obtain stone-like building materials.

The appearance of the liquid phase during heating of dust of the specified composition occurs at a temperature of 1200 ^o C. Overheating of the melt in the melting zone was set in the range of 400-550 ^o C. The technological temperature in the melting zone was 1600-1750 ^o C. The conductivity of the melt at the minimum technological temperature in the melting zone is 110 ohm / m.

 A 60 kW tube generator and an operating frequency of 880 kHz were used as a furnace power source.

The furnace was made with a melting zone of a rectangular cross section with an aspect ratio of 2, i.e. G 2. Calculation of the furnace parameters was carried out analogously to example 1 according to formulas (5), (2), (4) and (6), taking K _m = 4.0 and K _a = 0.2 as the initial values. As a result of the calculations, the values D 0.205 and K ₃ 0.706 were obtained. The cooled crucible was made of stainless steel tubes with a diameter of 0.012 m. The transverse dimension of the inductor in the melting zone was 0.29 m, and the gap between the crucible and inductor around the entire perimeter of the melting zone was 0.032 m.

 The furnace working zone was made along the narrow side of the crucible in the form of a tapering part of the crucible with an outlet toe along the major axis of the crucible. A septum separated the working zone along the lower side of the crucible. The magnetic field strength of the inductor in the working zone was reduced by 30% relative to the melting zone, which was achieved by reducing the fill factor of the inductor window in the working zone to a value of 0.5, i.e. 1.4 times less with respect to the melting zone.

 The device operates similarly to that described in Example 1. The indicated decrease in the magnetic field strength in the melting zone is sufficient to ensure cooling of the melt, since its enthalpy is small and the mass velocity of the melt entering the production zone is low (device productivity 27 kg / h). At the same time, a decrease in the temperature of the melt in the production zone provides a decrease in the electromagnetic forces acting on the melt. Together, this results in the formation of a laminar melt flow to the outlet toe.

 In the melting zone, the charge is intensively melted and the melt is homogenized. Homogenized melt, entering the production zone, goes through the stage of synthesis of clusters, the bulk of which are silicate matrices. Due to the high homogeneity of the melt and the laminar flow of its flows in the production zone, the inclusion of chromium and manganese ions in the structure of silicates is facilitated. The stream of structured melt enters the product preparation means, made in the form of a rotating disk, and breaks up into droplets solidified in granules. Granules can be used in construction as a filler.

 Sanitary-chemical studies of the resulting product showed the absence of leaching of heavy metals when testing granules in boiling water.

 Experiments were conducted to obtain mineral fiber from gabbro rock under various melting conditions and furnace design parameters.

The melting mode was set with the ratio of the volume of the heated melt in the melting zone to the volume of the entire melt in the zone of 60-65%, which corresponds to the choice of K _m when calculating the furnace parameters less than 6.0 for the round melting zone or less than 4.0 for the uneven and square melting zone. As a result, the melting rate of the raw material fell and mineral fiber with the worst quality indicators was obtained compared to the fiber obtained by the claimed method and device variants (see table).

When creating a furnace in which K _m = 15 for a circular melting zone and K _m = 8.5 for a non-axial melting zone, melt supercooling was observed in the center of the crucible, the temperature of which was lower than the temperature of delivery. This led to a significant decrease in the smelting productivity and the appearance of crystallization centers in the melt, as well as its incomplete homogenization. Ultimately, fiber quality deteriorated (see table).

 Smelting was carried out in a mode with a decrease in the magnetic field strength in the production zone by 20%, for which a furnace with a fill factor of the inductor window in the production zone was 1.3 times less than in the melting zone. In the experiment, it was not possible to obtain a stable laminar melt flow in the production zone to the output device. The quality of the product has deteriorated (see table).

 Comparative experiments were also carried out to obtain mineral fiber from gabbro rock by the prototype method. When creating the furnace were guided by recommendations (Petrov Yu. B. Induction smelting of oxides. 1983). The fill factor of the inductor window was chosen from the structural convenience of the furnace and the electric strength of the inductor-crucible gap.

 A 60 kW tube generator and an operating frequency of 1.76 MHz served as a power source. The furnace was made of rectangular cross-section with dimensions D = 0.21 m, G = 2.1. The fill factor of the inductor window in the working zone did not differ from its value in the melting zone. The inductor window dimensions were 0.29x0.58 m.

 As a result of experiments, it was possible to achieve melting regimes when a turbulent melt flow was formed in the melting zone. However, a turbulent melt flow was also formed in the production zone. The melt entered the means of processing the melt overheated, which during the formation of fibers led to an increase in the number of non-fibrous inclusions (kings), and a decrease in the fiber yield.

 An attempt to obtain a laminar melt flow in the production zone led to the need to lower the melt temperature in the melting zone. As a result, a turbulent melt flow in the melting zone was not formed. This led to a decrease in the furnace productivity, deterioration in the homogenization of the melt, and deterioration in the quality of the fiber (see table). In some modes, the process lost stability and melt crystallized in the furnace.

 A comparative analysis of the results of the experiments shows that the solution of the problem is achieved only when using the totality of the features of the invention, otherwise the process is disrupted or a positive effect is not achieved.

 Compared with the known, the proposed method and device variants for its implementation have the following advantages: improving the quality of products such as mineral fibers and mineral wool; increases the resistance to leaching of environmentally hazardous inorganic substances during their immobilization in glass-forming melts; the productivity of the melting process and the homogenization of glass-forming melts are increased; product yield increases.

Claims (7)

 1. A method of producing a product from a glass-forming melt, including supplying and melting the feedstock in an induction furnace with a cooled crucible, overheating of the melt in the melting zone and cooling in the workings area, followed by feeding into the product preparation means, characterized in that the melt overheating in the melting zone is in the mode of turbulent melt flow, and cooling in the production zone in the mode of laminar melt flow. 2. The method according to p. 1, characterized in that the melt in the melting zone is overheated at 400 1000 ^o C relative to the liquidus temperature of the melt or the temperature of the upper limit of its crystallization, while the relative size of the melt K _m in the melting zone is selected in the following ranges: for round section of the melting zone 6 14, for unequal and square section of the melting zone 4 8, and
K _m = D / Δ,
where D is the characteristic size of the melt in the melting zone, m;
Δ depth of current penetration into the melt in the melting zone, m, determined by the formula

where f is the current frequency of the furnace power source, Hz;
κ conductivity of the melt in the melting zone at a given temperature, Ohm / m;
μ _o = 4π • 10 ^-7 GN / m the magnetic permeability of vacuum.  3. The method according to PP. 1 and 2, characterized in that the cooling of the melt in the production zone is carried out while reducing the magnetic field of the inductor by 30 - 90% relative to its value in the melting zone. 4. A device for producing a product from a glass-forming melt, comprising an induction furnace, consisting of an inductor and a metal cooled crucible, equipped with a dispensing device and a partition separating the crucible into communicating melting and working zones, a feed mechanism and a means for producing a product from a glass-forming melt, characterized in that the fill factor of the inductor window K _s in the melting zone is selected according to the following formulas: for a round cross section of the melting zone

moreover, K _{m is} selected in the range of 6.0 to 14.0, for an unequal and square cross section of the melting zone
K _s ≥0.57 K _m 0.4 K _a + 0.11 G (2.1 + K _a ) 2,
where K _{m is} selected in the range of 4.0 to 8.0;
where K _a 0.1 0.4 empirical coefficient;
G ≥ 1 parameter, equal to the ratio of the dimensions of the cross section of the melting zone;
K _{m the} relative size of the melting zone, determined from the ratio
K _m = D / Δ,
D is the characteristic size of the melting zone, m;
Δ depth of current penetration into the melt in the melting zone, m, determined by the formula

where f is the current frequency of the furnace power source, Hz;
κ conductivity of the melt in the melting zone at a given temperature, Ohm / m;
m _o 4 • 10 ^-7 GN / m vacuum magnetic permeability.  5. The device according to claim 4, characterized in that the fill factor of the inductor window in the working zone is 1.4 times less than in the melting zone. 6. A device for producing a product from a glass-forming melt, comprising an induction furnace consisting of an inductor and a metal cooled crucible equipped with a dispensing device and a baffle separating the crucible into interconnected melting and working zones, a feed mechanism and means for producing a product from a glass-forming melt, characterized in that it is equipped with a short-circuited electric circuit, electromagnetically connected with a part of the inductor, covering the production zone, and the window duty ratio nduktora _of K in the melting zone is selected from the following formulas: For circular cross-section of the melting zone

moreover, K _m choose in the range of 6.0 to 14.0;
for unequal and square cross section of the melting zone
K _s ≥ 0.57 K _m 0.4 K _a + 0.11 G (2.1 + K _a ) 2,
moreover, K _m selected in the range of 4.0 to 8.0;
where K _a 0.1 0.4 empirical coefficient;
G ≥ 1 parameter, equal to the ratio of the dimensions of the cross section of the melting zone;
K _{m the} relative size of the melting zone, determined from the ratio
K _m = D / Δ,
D is the characteristic size of the melting zone, m;
Δ depth of current penetration into the melt in the melting zone, m, determined by the formula

where f is the current frequency of the furnace power source, Hz;
κ conductivity of the melt in the melting zone at a given temperature, Ohm / m;
m _o 4 • 10 ^-7 GN / m vacuum magnetic permeability.  7. The device according to p. 6, characterized in that the short-circuited electrical circuit is made in one piece with the elements of the crucible working zone and / or partition.

Images