Dry melting preparation process of high-purity sodium silicate

Abstract

The invention relates to the technical field of chemical preparation of silicate, and discloses a dry melting preparation process of high-purity sodium silicate, which comprises the following steps: adding an interface viscosity modifier into a mixture raw material formed by quartz sand and sodium carbonate, and establishing a central melt area in the center of a furnace chamber by utilizing high-frequency induction heating, a solid isolation layer is reserved between the central melt area and the furnace wall; the method comprises the following steps: preparing a eutectic temperature interval, adjusting the heat exchange amount to maintain a contact interface in the eutectic temperature interval, inducing local melt to supersaturated crystallization so as to generate a high-viscosity microcrystalline layer in situ, filling particle gaps of an isolation layer with the microcrystalline layer and blocking a physical permeation path, and constructing a physically compact microcrystalline barrier to cut off a diffusion path of impurities from a furnace wall to the melt, so that the eutectic temperature of the melt is greatly improved. The product purity depends on the intrinsic purity of raw materials, the continuous stability of the production process is maintained, and the loss of heat flow to the outside of the furnace is reduced.

Description

Technical Field

[0001] This invention relates to a dry melt preparation process for high-purity sodium silicate, belonging to the field of silicate chemical preparation technology. Background Technology

[0002] Sodium silicate is currently used as a basic raw material in the production of inorganic silicon compounds. It is produced by dry melting of silicon dioxide and sodium source at high temperature. This production method has a defined process path for industrial-scale applications. In the high-temperature melting system, the rheological properties and wetting properties of the melt determine its interaction with the contact interface. Sodium silicate melt at temperatures above 1000℃ has extremely low dynamic viscosity and exhibits strong wettability to solid particles such as quartz. Due to the surface tension gradient between the melt and the solid phase interface, capillary forces are generated in the high-temperature fluid. With the increasing demand for high-purity sodium silicate in fields such as high-precision optics, the improvement of product purity is limited by container contamination during the preparation process. Under high-temperature and strong alkaline conditions, the melt causes strong chemical erosion of furnace lining materials such as high-alumina bricks or zircon bricks. This erosion process causes metal impurities such as iron, aluminum, and titanium in the furnace lining to penetrate into the melt, resulting in irreversible systemic secondary pollution. Even with high-purity raw materials, the upper limit of the purity of the final product is still limited by the intrinsic material properties of the reaction vessel.

[0003] To reduce container contamination, the cold wall method, which utilizes the material itself as a static isolation layer, is an improvement in this field. However, the solid raw material layer is a porous medium. Under capillary pressure, the sodium silicate melt permeates along the micro-gap between material particles towards the furnace wall, creating a liquid bridge that reaches the furnace wall. The formation of this liquid phase path provides conditions for metal ions to undergo reverse mass transfer through liquid phase diffusion, causing impurities to migrate from the furnace wall to the core melt. Simply increasing the isolation layer thickness cannot block this kinetic path from a physicochemical perspective, and it is prone to causing structural erosion of the furnace body due to excessive local penetration. Stacked structure designs are ill-suited to address microscopic chemical penetration, and the accompanying process control methods are ineffective in blocking impurity migration. For example, Chinese invention patent CN101508441B discloses a direct dissolution process for molten sodium silicate, which optimizes the hardware form of the dissolution drum feeding screw and heat-resistant jacket, and uses the residual heat of the melt to improve the downstream dissolution efficiency. This approach focuses on the downstream products and ignores the intervention of interfacial dynamics in the core melting stage of the melt. It cannot induce spontaneous nucleation and crystallization at the solid-liquid interface and is difficult to block ion diffusion channels by coupling the concentration field and temperature field.

[0004] Therefore, the technical problem to be solved by this invention is how to cut off the migration channel of impurities from the furnace wall to the melt at the physicochemical level while maintaining the melting reaction, so as to achieve the continuous preparation of electronic grade sodium silicate. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A dry melt preparation process for high-purity sodium silicate, comprising the following steps:

[0006] Step S101: Quartz sand and soda ash are mixed to obtain a mixture raw material with a modulus of 2.0 to 3.5, and an interfacial viscosity modifier is added to the mixture raw material.

[0007] Step S102: The mixed raw materials are put into the melting reactor. A central melt zone with a temperature of 1350°C to 1450°C is established in the central area of ​​the furnace cavity using a high-frequency induction heating device with a frequency of 500Hz to 1500Hz. An isolation layer with a thickness of 150mm to 300mm composed of solid mixed raw materials is retained between the central melt zone and the furnace wall.

[0008] Step S103: Adjust the heat exchange of the cooling water in the furnace wall cooling jacket to maintain the contact interface temperature between the isolation layer and the central melt zone within the eutectic temperature range of 790°C to 810°C, thereby inducing local melt at the contact interface to undergo supersaturated crystallization.

[0009] Step S104: Maintain the local mass concentration of the interfacial viscosity modifier at the contact interface at 0.8% to 1.5%, and precipitate a semi-solid slurry-like microcrystalline layer with a thickness of 200 μm to 500 μm in situ at the contact interface. The phase composition of the microcrystalline layer is a blend of precipitated sodium silicate microcrystalline phase, residual liquid phase and interfacial viscosity modifier, and its apparent dynamic viscosity at 800°C is 10000 Pa·s to 100000 Pa·s.

[0010] Step S105: The semi-solid slurry-like microcrystalline layer is used to fill the interparticle gaps on the side of the isolation layer facing the central melt zone, blocking the physical penetration path from the central melt zone to the furnace wall side, and continuously extracting sodium silicate melt.

[0011] Preferably, the interfacial viscosity modifier is one or more of titanium dioxide, nano-alumina, and calcium fluoride; the amount of interfacial viscosity modifier added is 0.1% to 0.5% of the total mass of the mixture raw materials; in step S104, the nucleation density of the precipitated phase is increased by the interfacial viscosity modifier, so that the microcrystalline layer maintains the integrity of its physical structure under the high temperature fluid scouring of the central melt region.

[0012] Preferably, in step S103, the heat exchange rate at the contact interface is adjusted by controlling the flow rate of cooling water in the furnace wall cooling jacket; when the isolation layer is partially melted, causing the contact interface to shift towards the furnace wall, the temperature gradient at the contact interface is used to drive the quartz component in the isolation layer to partially dissolve, and diffuse to the melted area through the concentration gradient and recrystallize.

[0013] Preferably, in step S102, an alternating magnetic field generated by a high-frequency induction heating device is used to apply an electromagnetic stirring force to the central melt zone to maintain the uniformity of the components in the central melt zone; an isolation layer is used to limit the heat transfer from the central melt zone to the furnace wall, thereby controlling the outer shell temperature of the molten reactor below 150°C.

[0014] Preferably, the quartz sand in the mixture has a particle size of 0.1 mm to 0.5 mm, and the soda ash has a particle size of 0.2 mm to 0.8 mm. In step S101, the mixture is dry-mixed using a drum mixer to achieve a mixing uniformity of not less than 98% and to allow the interfacial viscosity modifier to adhere to the surface of the quartz sand.

[0015] Preferably, after step S105, the following step is also included: Step S106, the extracted sodium silicate melt is introduced into the receiving tank, and the cooling rate is controlled at 50℃ / s to 100℃ / s to cool the sodium silicate melt to obtain solid sodium silicate product; wherein, the iron content in the solid sodium silicate product is less than 10ppm.

[0016] Preferably, the furnace lining material of the melting reactor is high-purity quartz brick, and no metal support components are provided in the contact area between the high-purity quartz brick and the mixed raw materials; the microcrystalline layer is used to establish a physical dense barrier between the central melt zone and the high-purity quartz brick.

[0017] Preferably, in step S103, the mass flow rate M of the cooling water follows the following relationship: M=(P×(1-μ)) / (C×ΔT), where M is the mass flow rate of the cooling water, in kg / s; P is the real-time input power of the high-frequency induction heating device, in W; μ is the thermal efficiency of the melting reactor, with a value range of 0<μ<1; C is the specific heat capacity of water at constant pressure, which is a constant value within the operating temperature range of the cooling water in this process, in J / (kg·K); ΔT is the temperature difference between the inlet and outlet water of the furnace wall cooling jacket, in K.

[0018] Preferably, in step S101, an oxidizing agent is added to the mixture raw materials. The oxidizing agent is sodium nitrate, and the amount added is 0.5% to 1.0% of the total mass of the mixture raw materials. The oxidizing agent is used to oxidize ferrous ions to ferric ions in the central melt zone.

[0019] Preferably, in step S104, an infrared thermal imaging sensor installed on the furnace wall is used to monitor the real-time heat flux density of the isolation layer; when the monitored local temperature is higher than 850°C, the operating frequency of the high-frequency induction heating device is increased to enhance the skin effect and concentrate the heat to the central melt area.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. In the dry melting preparation of high-purity sodium silicate, by setting a gradient distribution of interfacial viscosity modifier in the solid isolation layer, the high specific surface area and surface energy of fumed silica are used to adjust the rheological properties of the generated sodium silicate melt at the solid-liquid interface. During the melting reaction, in conjunction with the adjustment of the heat exchange intensity of the reactor wall, the interface temperature is maintained in the eutectic range of the raw materials, inducing local supersaturation crystallization of the melt at the contact surface, thereby constructing a high-viscosity microcrystalline barrier film in situ. The dynamic viscosity of this microcrystalline barrier film at 800℃ is not less than 10,000 Pa·s. From a kinetic perspective, it blocks the capillary permeation channels of the solid raw material layer and cuts off the path of impurity ions to diffuse to the central melt through the liquid phase bridge, so that the purity of the product achieves a fundamental leap from being limited by container erosion to being determined by the intrinsic purity of the raw materials.

[0022] 2. By utilizing the coupled regulation of the interface temperature field and concentration field, and based on the dynamic self-healing characteristics of the microcrystalline barrier film, when the local interface is eroded and lost due to heat flow impact, the supersaturated system is driven by the cold wall temperature gradient to replenish the raw materials and recrystallize, ensuring the integrity of the isolation barrier in long-term continuous operation. This changes the traditional dry melting process that requires periodic shutdowns to replace eroded furnace linings, transforming intermittent maintenance into long-term stable continuous service, reducing equipment structural wear and tear while improving the intrinsic stability of the production process.

[0023] 3. By constructing a composite heat insulation system through a static isolation layer and a microcrystalline barrier film, combined with a non-contact heating method, targeted injection of heat energy into the core reaction area is achieved. The solid raw material layer acts as a natural heat insulation barrier, reducing ineffective heat loss to the outside through the furnace wall, thus transforming the energy utilization mode from global diffusion to core focus and reducing the energy consumption index per unit product. By adjusting the power density of induction heating, a specific intensity of thermal convection is formed inside the sodium silicate melt. Utilizing the difference in the distribution coefficient of impurity ions during the melting process, trace metal ions are guided to accumulate at the phase interface and lock in the static isolation layer. This process, on the basis of achieving physical isolation between the melt and the container, further superimposes the purification effect of zone melting, ensuring that the product reaches electronic or optical grade purity standards. Attached Figure Description

[0024] Figure 1 This is a flow chart of the dry melting process for high-purity sodium silicate using the interface microcrystal blocking technology of this invention.

[0025] Figure 2 This is a block diagram illustrating the principle of the sodium silicate preparation system integrating high-frequency induction heating and automatic thermal field control as described in this invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a dry melting process for preparing high-purity sodium silicate, including stages such as raw material preparation, static isolation layer pre-setting, central melt zone establishment, and in-situ generation of interfacial microcrystalline layer. By maintaining a solid raw material layer with a viscosity gradient on the inner wall of the reactor and adjusting the interfacial heat transfer intensity, a dense microcrystalline structure is induced to block the penetration path of impurity ions, making the product purity dependent on the intrinsic purity of the raw materials. Sodium silicate melt has low viscosity and strong wettability in environments above 1000℃, and easily undergoes capillary penetration through porous media to form liquid phase bridges. To block this path, the raw material preparation procedure includes: mixing quartz sand and soda ash according to a modulus n of 2.0 to 3.5, and adding an interfacial viscosity modifier to the raw material mixture. To determine the feeding ratio of each component in the raw material mixture, the modulus n is defined as the molar ratio of silicon dioxide to sodium oxide in the raw material mixture, and its specific calculation formula is as follows: n = m SiO2 ×M Na2CO3 / m Na2CO3 ×M SiO2 Where n is the modulus of sodium silicate, and M SiO2 The mass of quartz sand in the mixture is expressed in kg or m³. Na2CO3 The mass of soda ash in the mixture is expressed in kg (m). SiO2 M represents the molar mass of silicon dioxide, taken as 60.08 g / mol. Na2CO3The molar mass of sodium carbonate is 105.99 g / mol; the interfacial viscosity modifier is at least one of titanium dioxide, nano-alumina, or calcium fluoride, and its addition amount is 0.1% to 0.5% of the total mass of the raw materials in the mixture; this modifier utilizes its surface energy characteristics to adjust the rheological characteristics of the sodium silicate melt at the phase interface, providing physicochemical conditions for subsequent blocking of ion diffusion channels; in this invention, nano-alumina is preferably spherical particles with a particle size between 20 nm and 50 nm. Due to the extremely high specific surface area and surface energy of nanomaterials, when the sodium silicate melt is in the eutectic temperature range (790℃ to 810℃), it can induce the melt molecules to oriented arrangement through the active sites on the surface, thereby producing a significant quasi-plastic thickening effect. Specifically, the spherical morphology is beneficial for its performance in dry mixing stages. The nanoparticles (step S101) are uniformly attached to the surface of the quartz sand. At the molten interface, the nanoparticles, as non-uniform nucleation centers, can significantly increase the nucleation density of the microcrystalline layer, causing the precipitated microcrystals to intertwine and form a dense network structure, thereby increasing the apparent dynamic viscosity of the interface to over 10,000 Pa·s, effectively blocking the physical penetration path of impurities. The inner wall of the molten reaction furnace is provided with a static isolation layer composed of mixed raw materials, with a thickness of 150 mm to 300 mm. A high-frequency induction heating device with a frequency of 500 Hz to 1500 Hz is used to establish a central melt zone with a temperature of 1350 °C to 1450 °C in the central area of ​​the furnace cavity. The molten reaction is encased inside a solid raw material layer of the same composition, so that the reaction area and the furnace lining material are spatially decoupled, avoiding systemic pollution caused by container erosion.

[0028] To cut off impurity migration paths at the atomic level, the heat transfer intensity of the controlled interface is adjusted by regulating the mass flow rate M of the cooling water installed in the furnace wall cooling jacket. The mass flow rate M of the cooling water follows the following relationship: M=(P×(1-μ)) / (C×ΔT), where M is the mass flow rate of the cooling water, in kg / s; P is the real-time input power of the high-frequency induction heating device, in W; μ is the thermal efficiency of the melting reactor; C is the specific heat capacity of water at constant pressure, in J / (kg·K); and ΔT is the temperature difference between the inlet and outlet water of the furnace wall cooling jacket, in K. This calibration procedure maintains the contact interface temperature between the isolation layer and the central melt zone within the eutectic temperature range of 790℃ to 810℃, inducing local melting. The material undergoes supersaturated crystallization, resulting in the in-situ formation of a microcrystalline layer with a thickness of 200 μm to 500 μm. Its dynamic viscosity at 800 °C ranges from 10,000 Pa·s to 100,000 Pa·s. This semi-solid, slurry-like microcrystalline layer is microscopically a blend of precipitated sodium silicate microcrystalline phases, residual liquid phases, and interfacial viscosity modifiers. This specific phase composition allows the layer to possess both sufficient physical strength to block capillary penetration near the eutectic temperature and the micro-flowability of a quasi-plastic fluid, filling interparticle gaps and enabling online self-repair after damage. The microcrystalline layer fills the interparticle gaps on the side of the isolation layer facing the central melt region, constructing a viscosity gradient blocking barrier against metal ions, thus achieving the blocking of impurities in the furnace lining. Migration blocking; the local concentration enrichment of interfacial viscosity modifiers is achieved based on the mechanical repulsion mechanism caused by solubility differences. Since the melting point of modifiers such as titanium dioxide is significantly higher than the eutectic point temperature of sodium silicate, within the eutectic temperature range, melt crystallization generates mechanical repulsion, pushing the modifier dispersed in the raw material to the forefront of the solid-liquid interface. This forms a physical accumulation zone approximately 200 micrometers thick at the interface. By mapping a migration enrichment coefficient of 3.2 to 5.6 times, the initial addition of 0.1% to 0.5% in the raw material is converted into an effective concentration of 0.8% to 1.5% at the interface, thereby maintaining the local concentration of the interfacial modifier at 0.8% to 1.5%, resulting in in-situ precipitation of a thick layer at the contact interface. The process involves a semi-solid slurry-like microcrystalline layer with a thickness of 200μm to 500μm and a dynamic viscosity of 10000Pa·s to 100000Pa·s at 800℃. This process maintains operational stability by employing a dynamic self-healing method at the phase interface. An infrared thermal imaging sensor installed on the furnace wall monitors the real-time heat flux density of the isolation layer. When a local temperature exceeds 850℃, the operating frequency of the high-frequency induction heating device is increased to enhance the skin effect, concentrating heat towards the central melt region. Simultaneously, the temperature gradient at the interface drives the quartz components to migrate towards the melt-damaged area and recrystallize, achieving online repair of the microcrystalline layer during production. This process ensures that the iron content in the product is below 10ppm.

[0029] Example 1: In the preparation of electronic-grade sodium silicate, the iron content of the product needs to be controlled below 10 ppm. However, in the traditional dry melting process, the high-temperature strong alkali melt erodes the furnace lining materials such as high-alumina bricks or zircon bricks. Furthermore, the liquid phase bridge formed by the melt through the porous solid raw material layer causes reverse mass transfer of impurities. To address the pollution challenge caused by the diffusion of such impurities, this technical solution mixes quartz sand and soda ash according to the modulus requirement of 3.0, and adds 0.3% fumed silica as an interfacial viscosity modifier to the mixture. A static isolation layer with a thickness of 200 mm is preset on the inner wall of the melting reactor. A high-frequency induction heating device with a frequency set to 1000 Hz is turned on to maintain the temperature of the central melt zone at 1420°C. At the same time, the interfacial heat transfer intensity is adjusted by using a cooling jacket control system.

[0030] To achieve deterministic control of the thickness of the interfacial microcrystalline layer, the mass flow rate M of the cooling water in the cooling jacket is adjusted to 0.67 kg / s according to the calculation formula M = (P × (1-μ)) / (C × ΔT), where M is the mass flow rate of the cooling water in kg / s; P is the real-time input power of the high-frequency induction heating device, taken as 150000 W; μ is the thermal efficiency of the melting reactor, taken as 0.85; C is the specific heat capacity of water at constant pressure, taken as 4200 J / (kg·K); and ΔT is the temperature difference between the inlet and outlet water of the cooling jacket, set to 8 K. This specific heat transfer intensity and power matching process locks the real-time temperature of the solid-liquid interface at 800℃, inducing… The process induces supersaturated crystallization in the local melt, resulting in an in-situ microcrystalline layer with a thickness of 350 μm. This microcrystalline layer exhibits a dynamic viscosity of 50,000 Pa·s at 800°C, and its physical structure blocks the capillary permeation channels inside the static isolation layer. By adjusting the interfacial surface energy with fumed silica and coordinating precise heat exchange calibration, the dense microcrystalline layer atomically severs the diffusion path of impurity ions from the furnace wall to the central melt region, enabling the product purity to shift from the upper limit of the container material to the intrinsic purity of the raw material. Ultimately, the measured iron content in the product remains stable below 8 ppm, and the heat flux density of the reactor wall is maintained within the preset process safety range throughout the production cycle.

[0031] Example 2: In verifying the effectiveness of the high-purity sodium silicate preparation process, the experimental background focused on solving the performance bottleneck of iron contamination exceeding 10 ppm in the product due to high-temperature melt penetration. The experiment was conducted in a molten reactor equipped with a precise thermal field control and fluid circulation system, featuring a mass flow meter with a measurement accuracy of 0.01 kg / s and an infrared temperature sensor with a resolution of 0.1 °C. The raw materials and interfacial viscosity modifiers used in the experiment were obtained through a physical experimental platform, and their functional specifications and performance boundaries met electronic-grade production standards. During the experimental design phase, the setting of the cooling water mass flow rate M followed the following decision logic chain: First, the key factor affecting the interfacial crystallization rate was identified as the heat transfer intensity of the cooling jacket. Second, the essence of the technical trade-off lay in balancing the supercooling required for supersaturated crystallization at the interface with the heat loss of the high-frequency induction heating system. Based on the principle of thermal balance, a judgment model was established between the cooling water flow rate, input power, and target interface temperature. Finally, an engineering example was determined for the cooling water mass flow rate M at an input power of 150,000 W. The value is 0.67 kg / s; the heat transfer intensity of the controlled interface is given by the cooling water mass flow rate M, which follows the formula: M = (P × (1-μ)) / (C × ΔT), where M is the mass flow rate of the cooling water in kg / s; P is the real-time input power of the high-frequency induction heating device, which is 150000 W; μ is the thermal efficiency of the melting reactor, which is 0.85; C is the specific heat capacity of water at constant pressure, which is 4200 J / (kg·K); ΔT is the temperature difference between the inlet and outlet water of the furnace wall cooling jacket, which is set to 8 K; the experimental system consists of the sample group of this invention and the control group for comparison, wherein the sample group of this invention implements the complete process parameters of this invention; the control group design includes partially missing control groups A and B, and out-of-range control groups C and D; control group A removes the interface viscosity modifier, control group B adjusts the cooling water flow rate to raise the interface temperature to 950℃; control group C sets the mass fraction of the interface viscosity modifier to 0.03%; control group D sets the mass fraction of the interface viscosity modifier to 0.9%.

[0032] Table 1: Comparison of Experimental Processes for Preparing High-Purity Sodium Silicate

[0033]

[0034] According to the test data in Table 1, in the absence of interfacial viscosity modifier, even when the interfacial temperature was maintained, the viscosity of the generated microcrystalline layer in control group A was only 800 Pa·s, the penetration depth of the melt along the interparticle gaps reached 158.4 mm, and the iron content of the product increased to 25.6 ppm. This indicates that the interfacial viscosity modifier plays a role in improving the density of the crystallized layer by adjusting the surface energy. The data of control group B show that after the interfacial temperature rises to 950℃, the microcrystalline layer remelts, causing the viscosity gradient blocking effect to disappear and the impurity contamination path to recover. The verification of the parameter boundary shows that the addition amount of control group C is lower than the lower limit, resulting in insufficient nucleation sites and failure to form a continuous barrier. In control group D, when the addition amount reaches 0.9%, although the iron content of the product is 9.1 ppm, the decrease in melt fluidity leads to a slower material melting rate, and the production efficiency is 22.4% lower than that of the present invention sample group. This indicates that when the mass fraction of the interfacial viscosity modifier is in the range of 0.1% to 0.5%, the iron content of the product and the production efficiency both meet the predetermined index requirements.

[0035] Example 3: This example combines Figures 1 to 2 The dry melt preparation process for a high-purity sodium silicate is described below. Figure 1 As shown, in step S101, quartz sand and soda ash are mixed to obtain a mixture raw material with a modulus of 2.0 to 3.5. An interfacial viscosity modifier is added to the mixture raw material. In step S102, the mixture raw material is put into a melting reactor. A central melt zone with a temperature of 1350°C to 1450°C is established in the center of the furnace cavity using a high-frequency induction heating device with a frequency of 500Hz to 1500Hz. A solid isolation layer with a thickness of 150mm to 300mm is maintained between the central melt zone and the furnace wall. Then, in step S103, the furnace wall cooling is adjusted. The water heat exchange maintains the contact interface temperature in the eutectic temperature range of 790℃ to 810℃, inducing local supersaturation crystallization of the melt at the contact interface. In step S104, the local concentration of the interface modifier is maintained at 0.8% to 1.5%, and a microcrystalline layer with a thickness of 200μm to 500μm is precipitated in situ at the contact interface, exhibiting a dynamic viscosity of 10000Pa·s to 100000Pa·s at 800℃. Finally, in step S105, the microcrystalline layer is used to fill the gaps between particles, blocking the physical penetration path and impurity migration, and sodium silicate melt is continuously extracted.

[0036] like Figure 2As shown, the reaction core of the device is located inside the furnace wall cooling jacket, which is filled with a static isolation layer composed of solid raw materials and a central melt zone with a temperature maintained at 1350-1450℃. On the raw material supply side, there is a drum mixer containing quartz sand, soda ash and additives to provide mixed raw materials to the inside of the molten reaction furnace. The control center of the system is a central control unit that integrates thermal field algorithm and logic control. It receives wall heat flow data from infrared thermal imaging sensor and sends power control commands and flow control commands to the high-frequency power driver and cooling water flow regulating valve group, respectively. The high-frequency power driver adjusts the frequency in the range of 500-1500Hz according to the command and outputs high-frequency current to the induction coil. The cooling water flow regulating valve group precisely controls the heat exchange according to the command and manages the supply of cooling water to the furnace wall cooling jacket. The product generated by the reaction is extracted through the melt and enters the cooling receiving tank for rapid cooling and molding.

[0037] Example 4: In an electronic-grade sodium silicate production system with a continuous operating cycle exceeding 168 hours and a single furnace output reaching 50 tons, the static isolation layer at the bottom edge of the molten reactor experiences localized thinning due to thermomechanical stress concentration caused by long-term convective erosion in the central melt zone. This results in the heat flux density on the outer wall of this area, as monitored by the infrared thermal imaging sensor, decreasing from the baseline of 5 kW / m³. 2 Increased to 12kW / m 2 Furthermore, when the local interface temperature feedback value exceeds the preset safety threshold of 850℃, the high-temperature melt penetrates along the damaged area and tends to form a liquid phase channel directly reaching the furnace wall. This poses a risk that metallic impurities in the furnace lining material may enter the melt. To implement the dynamic self-repair procedure of the phase interface, the control unit dynamically increases the operating frequency of the high-frequency induction heating device from the reference 1000Hz to 1450Hz based on the real-time monitored interface temperature deviation value. Utilizing the electromagnetic induction principle that the skin depth of the induced electromagnetic field is negatively correlated with frequency, the Joule heat generated by the induced current is concentrated towards the radial core of the central melt region by shortening the penetration depth of the electromagnetic wave in the melt. This increases the temperature gradient between the central melt region and the phase interface. The formula for calculating the skin depth δ is as follows: Where δ is the skin depth in meters (m); f is the operating frequency of the high-frequency induction heating device in Hz; μ is the magnetic permeability of the melt in H / m; and σ is the electrical conductivity of the melt in S / m.

[0038] Under this thermal field distribution, the temperature gradient at the interface drives the quartz component in the static isolation layer to migrate towards the lower temperature side. The interfacial viscosity modifier pre-retained in the raw material utilizes its surface active silanol groups to form silicon-oxygen bonds with the migrated particles, creating non-uniform nucleation centers at the interfacial temperature of 795℃. This induces supersaturated crystallization of the sodium silicate component in the melt. The repaired microcrystalline layer thickness recovers to 450μm with an internal porosity of less than 2%, and the heat flux density in the damaged area drops to 5.2kW / m² within 15 minutes. 2 Furthermore, the iron content of the produced sodium silicate remains at around 7.5 ppm.

[0039] Example 5: In a production scenario where different batches of quartz sand raw materials are replaced, to determine the thermal efficiency μ of the melting reactor and eliminate the influence of material particle size distribution on the heat conduction path, the system executes a benchmark calibration procedure, selects a mixture of raw materials with the required mass percentage for filling the furnace cavity, controls the high-frequency induction heating device to operate at a real-time input power P of 50000W, measures the constant value of the cooling water mass flow rate M using a mass flow meter, and monitors the steady-state value of the temperature difference ΔT between the inlet and outlet of the furnace wall cooling jacket using a temperature sensor. The current system thermal efficiency μ is determined according to the formula μ=1-(M×C×ΔT) / P, where μ is the thermal efficiency of the melting reactor, M is the mass flow rate of the cooling water in kg / s, and C is the constant pressure of the water. Specific heat capacity, taken as 4200 J / (kg·K), ΔT is the temperature difference between the inlet and outlet of the furnace wall cooling jacket, in K, and P is the real-time input power of the high-frequency induction heating device, in W. In the actual production cycle, the thermal efficiency is determined by the idle speed thermal balance calibration method, that is, the first 30 minutes after the start of each batch of production is set as the calibration window period. At this time, the control central unit commands the cooling water flow regulating valve group to maintain a constant flow of 0.5 kg / s. When the temperature difference between the inlet and outlet water is less than 0.2℃ within 5 minutes, the system substitutes the real-time value measured at this time into the formula to calculate and lock the thermal efficiency benchmark value of this production cycle. This thermal efficiency μ is used to correct the given deviation of the cooling water mass flow rate M in the melting stage, so that the heat flow equilibrium point at the phase boundary is in the crystallization temperature zone.

[0040] When the system is in a cold start-up condition after furnace shutdown and maintenance, the in-situ construction of the interface microcrystalline layer follows the energy gradient distribution and flow rate following procedure. The high-frequency induction heating device drives the temperature of the central melt zone to rise from room temperature to 1400℃ at a rate of 10℃ / min. The control unit drives the cooling water mass flow rate M to increase stepwise according to the real-time heat load calculation results. During this process, the infrared thermal imaging sensor captures the grayscale gradient change on the inner surface of the static isolation layer to determine the critical point of interface crystallization. By maintaining the operating frequency f at the frequency point that makes the skin depth δ cover the interparticle gaps, the interface viscosity modifier is induced to complete nucleation growth at around 800℃. When the thickness of the interface microcrystalline layer reaches more than 200μm and the mass content of sodium iron silicate produced is reduced to less than 10ppm, the physical barrier is completed at the interface.

[0041] Example 6: In a reactor deployment scenario with a furnace cavity radius R of 800mm and a rated input power P of 250000W, in order to determine the compatibility between the thickness d of the static isolation layer and the geometry of the furnace body, the control unit sets the thickness d of the static isolation layer to 200mm according to the furnace cavity radius R with a proportional coefficient of 0.25. The physical boundary is established by laying a layer of mixed raw materials with a thickness equal to the thickness d on the inner side of the furnace wall, and the raw materials to be melted are filled into the central area. At the same time, the cooling jacket control system preheats the circulating water to an initial reference temperature of 40°C.

[0042] When the system starts the melting reaction, the control logic follows the power step and heat flow stability judgment. The real-time input power P of the high-frequency induction heating device is increased to 180000W at a rate of 5000W / min. The control unit monitors the fluctuation of the temperature difference ΔT between the inlet and outlet of the furnace wall cooling jacket in real time. When the temperature difference variation within 20 minutes is less than 0.3K, the system determines that the central melt zone and the phase boundary have reached a dynamic thermal equilibrium state. The interfacial viscosity modifier is induced to complete the crystal nucleus anchoring and generate a microcrystalline layer at the phase boundary. When the thickness of the microcrystalline layer reaches more than 300μm and the mass content of sodium silicate iron element produced is reduced to less than 8ppm, the system continuously collects molten sodium silicate through the bottom discharge port and cools and solidifies it into a finished product through the air-cooled conveyor line. At this time, the measured temperature of the outer wall of the reactor remains below 65℃ under this operating condition.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A dry melt preparation process for high-purity sodium silicate, characterized in that, Includes the following steps: Step S101: Quartz sand and soda ash are mixed to obtain a mixture raw material with a modulus of 2.0 to 3.5, and an interfacial viscosity modifier is added to the mixture raw material. Step S102: The mixed raw materials are put into the melting reactor. A central melt zone with a temperature of 1350°C to 1450°C is established in the central area of ​​the furnace cavity using a high-frequency induction heating device with a frequency of 500Hz to 1500Hz. An isolation layer with a thickness of 150mm to 300mm composed of solid mixed raw materials is retained between the central melt zone and the furnace wall. Step S103: Adjust the heat exchange of the cooling water in the furnace wall cooling jacket to maintain the contact interface temperature between the isolation layer and the central melt zone within the eutectic temperature range of 790°C to 810°C, thereby inducing local melt at the contact interface to undergo supersaturated crystallization. Step S104: Maintain the local mass concentration of the interfacial viscosity modifier at the contact interface at 0.8% to 1.5%, and precipitate a semi-solid slurry-like microcrystalline layer with a thickness of 200 μm to 500 μm in situ at the contact interface. The phase composition of the microcrystalline layer is a blend of precipitated sodium silicate microcrystalline phase, residual liquid phase and interfacial viscosity modifier, and its apparent dynamic viscosity at 800°C is 10000 Pa·s to 100000 Pa·s. Step S105: The semi-solid slurry-like microcrystalline layer is used to fill the interparticle gaps on the side of the isolation layer facing the central melt zone, blocking the physical penetration path from the central melt zone to the furnace wall side, and continuously extracting sodium silicate melt.

2. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, The interfacial viscosity modifier is one or more of titanium dioxide, nano-alumina, and calcium fluoride; the amount of interfacial viscosity modifier added is 0.1% to 0.5% of the total mass of the mixture raw materials; in step S104, the nucleation density of the precipitated phase is increased by the interfacial viscosity modifier, so that the microcrystalline layer maintains the integrity of its physical structure under the high temperature fluid scouring of the central melt region.

3. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, In step S103, the heat exchange rate at the contact interface is adjusted by controlling the flow rate of cooling water in the furnace wall cooling jacket; when the isolation layer is partially melted, causing the contact interface to shift towards the furnace wall, the temperature gradient at the contact interface is used to drive the quartz component in the isolation layer to partially dissolve, and diffuse to the melted area through the concentration gradient and recrystallize.

4. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, In step S102, an alternating magnetic field generated by a high-frequency induction heating device is used to apply electromagnetic stirring force to the central melt zone to maintain the uniformity of the components in the central melt zone; an isolation layer is used to limit the heat transfer from the central melt zone to the furnace wall, thereby controlling the outer shell temperature of the molten reactor below 150°C.

5. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, The quartz sand in the mixture has a particle size of 0.1 mm to 0.5 mm, and the soda ash has a particle size of 0.2 mm to 0.8 mm. In step S101, the mixture is dry-mixed using a drum mixer to ensure that the mixing uniformity of the mixture is not less than 98%, and to allow the interfacial viscosity modifier to adhere to the surface of the quartz sand.

6. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, After step S105, the following steps are also included: Step S106, the extracted sodium silicate melt is introduced into the receiving tank, and the cooling rate is controlled at 50℃ / s to 100℃ / s to cool the sodium silicate melt, thereby obtaining solid sodium silicate product; wherein, the iron content in the solid sodium silicate product is less than 10ppm.

7. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, The furnace lining material of the melting reactor is high-purity quartz brick, and no metal support components are set in the contact area between the high-purity quartz brick and the mixed raw materials; the microcrystalline layer is used to establish a physical dense barrier between the central melt zone and the high-purity quartz brick.

8. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, In step S101, an oxidizing agent, sodium nitrate, is added to the mixture raw materials, and the amount added is 0.5% to 1.0% of the total mass of the mixture raw materials; the oxidizing agent is used to oxidize ferrous ions to ferric ions in the central melt zone.

9. The dry melt preparation process for high-purity sodium silicate according to claim 1, characterized in that, In step S104, an infrared thermal imaging sensor installed on the furnace wall is used to monitor the real-time heat flux density of the isolation layer; when the monitored local temperature is higher than 850°C, the operating frequency of the high-frequency induction heating device is increased to enhance the skin effect and concentrate the heat to the central melt area.

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