Device and method for purifying chlorinated quartz sand by tower plate fractionation

Abstract

The device comprises a tower body, a heating system, a tail gas treatment system and a power system, the interior of the tower body is divided into a plurality of reaction stages through the tower plates, the tower plates are connected in series through a rotating shaft, a feeding port and a gas outlet are formed in the top of the tower body, and a discharging port and a gas inlet are formed in the bottom of the tower body; the solid quartz sand gradually passes through each layer of tower plate from top to bottom, and the chlorination reaction gas reversely passes through each layer of tower plate from bottom to top; the heating system is arranged in the tower body and forms a gradient temperature field of which the temperature is gradually reduced from bottom to top; the tail gas treatment system is communicated with a gas outlet in the tower body and treats waste gas generated in the tower body; the power system is in transmission connection with the rotating shaft to drive the tower plates to rotate. According to the method, impurities are removed more thoroughly through a multi-stage countercurrent fractionation mechanism, the impurities with different boiling points are separated stage by stage, cross contamination is avoided, the product purity can stably reach 99.998% or above, and the uniformity in batches and between batches is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-purity quartz sand preparation, in particular to a tray fractionation chlorination purification quartz sand device and method. BACKGROUND

[0002] High-purity quartz sand is a key basic material for high-end industries such as photovoltaic, semiconductor, and optical fiber communication. Its purity (usually requires SiO2 content greater than 99.99%) directly determines the performance of the final product. The main impurities in quartz sand include aluminum, iron, titanium, and alkali metals. Currently, the mainstream high-temperature chlorination purification technology is to react quartz sand with chlorinating agents (such as Cl2, HCl) at high temperature (1200℃), so that impurity elements are converted into gaseous chlorides (such as AlCl3, FeCl3, TiCl4) and escape. However, the existing technology mostly uses a rotary heating furnace. Quartz sand is still not fully contacted with the reaction gas due to over-dense stacking, and there are problems such as low mass and heat transfer efficiency, long reaction time, local overheating or incomplete reaction, high energy consumption, and poor uniformity of product purity. Therefore, high-purity quartz sand chlorination purification urgently needs a new method and device that can achieve efficient, uniform, and controllable contact between gas and solid phases, accurately control the reaction process, and finally stably produce ultra-high-purity quartz sand.

[0003] The current purification process of quartz sand involves a series of links. Natural quartz ore is crushed, ground, screened, magnetically separated, floated, and acid leached through conventional beneficiation and pretreatment methods and high-temperature chlorination roasting for deep purification. High-temperature chlorination purification can effectively remove impurity elements (such as Al, Fe, Cu, Ti, etc.) and inclusions in the quartz lattice, and is a key technology to break through the purity bottleneck of natural quartz sand. Chlorination roasting is usually carried out at a high temperature of 1200℃ or above, and Cl2 / HCl or other chlorinating agents are introduced to convert impurity elements into gaseous chlorides for volatilization and removal. However, this method usually has problems such as insufficient gas-solid reaction, insufficient chlorination contact reaction time, local overheating and low overall temperature, strict requirements for equipment corrosion resistance, high environmental protection pressure, and high operating cost.

[0004] In view of the deficiencies of the prior art, the present application provides a new method for purifying chlorinated quartz sand by tray fractionation. The purpose is to realize the countercurrent, multistage, and sufficient contact between quartz sand and hydrogen chloride gas by introducing a tray structure of a rectifying column, to upgrade the chlorination purification process from a simple chemical reaction to a precise purification reaction process with both reaction and fractionation effects, thereby significantly improving the impurity removal efficiency, product purity, and uniformity, and reducing energy consumption and chlorination gas consumption.

[0005] After searching, the following prior art is found: The patent specification with publication number CN119533119A discloses a rotary dispersion type quartz sand high-temperature chlorination furnace, which is installed in an inclined manner inside a furnace shell and can be driven to rotate slowly by a rotating device to drive the quartz sand to slide from top to bottom in the furnace, realizing continuous high-temperature chlorination treatment of the quartz sand. The baffle on the inner wall of the furnace body can effectively disperse the quartz sand, increase the contact area between the quartz sand and the chlorinating agent, and prolong the reaction time, fully removing the alkali metal impurities and improving the purity of the quartz sand.

[0006] The patent specification with publication number CN118698480A discloses a high-purity quartz sand chlorination purification equipment and purification method, which fully utilizes the high thermal efficiency of the vertical furnace, preheats the raw materials, and prolongs the residence time of the raw materials in the first furnace body by using the baffle, so that the materials can reach a lower preset temperature in a shorter time. In addition, the spatial arrangement of the first and second furnace bodies shortens the length of the first feeding chute, avoiding temperature loss.

[0007] The patent specification with publication number CN104418334B discloses a chlorination system and method for producing high-purity quartz sand. The chlorination system includes a cavity, a dust removal device, a gas compressor, a hot blast furnace, a cooling bin, a blower, and a chlorination gas absorption device. The chlorination method is as follows: quartz sand is reacted with a circulating flow of chlorination reaction gas at 800-1200℃ for 20-60 minutes to remove fluid impurities and elemental impurities in the quartz sand while completing chlorination. The quartz sand flows in a "boiling" state in the system, greatly improving the chlorination efficiency and capacity, and the chlorination gas can be recycled, effectively reducing the consumption of chlorination gas and environmental pressure.

[0008] The patent specification with publication number CN214880247U discloses a high-purity quartz sand chlorination device. The method is to set side feed ports and side mounting ports on both sides of the high-purity quartz tube. The gas inlet assembly includes a gas inlet pipe, a fixed end, and a quartz sand filtration assembly. Chlorination gas enters the quartz sand through the gas inlet port and the gas inlet port is always located below the quartz sand, which can ensure that the chlorination gas entering the device can fully contact the quartz sand and will not directly flow to the side feed port. At the same time, the rotation of the high-purity quartz tube makes the quartz sand tumble in the high-purity quartz tube, and all the quartz sand will contact with fresh chlorination gas, improving the contact area and reaction efficiency.

[0009] The above prior art has the following disadvantages: the solid quartz sand and gaseous chlorinating agent cannot be fully mixed during the chlorination and purification process of high-purity quartz sand, the existing chlorination and purification quartz sand equipment does not consider the recycling of chlorination gas, the use cost is high, and there are limitations such as pollution and safety risk in gas tail gas treatment. SUMMARY

[0010] In view of the problems in the prior art, the present application provides a device and method for purifying quartz sand by tower plate fractionation chlorination to overcome the above technical problems existing in the prior art.

[0011] To this end, the present application adopts the following specific technical solutions: A device for purifying quartz sand by tower plate fractionation chlorination, characterized in that it comprises: A tower body, which is internally separated into multiple reaction stages by tower plates, the tower plates being connected in series by a rotating shaft, a feed inlet and a gas outlet being provided at the top of the tower body, and a discharge outlet and an air inlet being provided at the bottom of the tower body; solid quartz sand passes through each layer of tower plates in turn from top to bottom, and chlorination reaction gas passes through each layer of tower plates in countercurrent from bottom to top; A heating system, which is arranged in the tower body and forms a gradient temperature field with gradually decreasing temperature from bottom to top; An exhaust gas treatment system, which is in communication with the gas outlet on the tower body and treats the exhaust gas generated in the tower body; A power system, which is in driving connection with the rotating shaft to drive the rotation of the tower plates.

[0012] Preferably, the tower plates are sieve plates or bubble cap plates, which are made of high-purity quartz glass or silicon carbide, the rotating shaft passes through the center of the tower plates to allow gas to pass through and carry a certain thickness of solid quartz sand particles to form a "solid thin layer".

[0013] Preferably, the tower plates are provided with flow guide pipes or adjustable weirs for controlling the downward flow and residence time of the solid quartz sand.

[0014] Preferably, the heating system comprises an upper heating unit, a middle heating unit and a lower heating unit, the upper heating unit is a heating furnace, the middle heating unit is a heating pump, and the lower heating unit is a heating rod.

[0015] Preferably, the exhaust gas treatment system comprises a gas-solid separator or filter for blocking quartz sand dust, a water cooling pipe for cooling high-temperature exhaust gas, a desiccant pipe for drying and cooling gas, and a circulating pump for recycling the gas into the tower body; the gas outlet is connected with the water cooling pipe through the gas-solid separator or filter, the water cooling pipe is connected with the desiccant pipe, the desiccant pipe is connected with the circulating pump, and the circulating pump is connected with the air inlet.

[0016] Preferably, the power system comprises a motor, a transmission belt, a driving wheel and a driven wheel; the motor is in driving connection with the driving wheel, the driving wheel is in driving connection with the driven wheel through the transmission belt, and the driven wheel is connected with the rotating shaft.

[0017] Preferably, a rotary valve or double gate valve is arranged at the discharge outlet at the bottom of the tower body for continuous and sealed discharge.

[0018] Preferably, the tower body bottom is provided with a chlorinated gas inlet system for uniform distribution of the reaction gas.

[0019] A tower plate fractionation chlorination quartz sand purification method, comprising the following steps: Step 1, first, the entire device is purged with inert gas, the multi-stage heating unit is started, the lower section of the tower body is heated to 1400℃, the middle section is heated to 1300℃, and the upper section is heated to 1200℃, and remains stable; Step 2, the solid quartz sand raw material is continuously added to the top of the tower body through the feed inlet at the top, the solid quartz sand flows to the tower plate through the flow guide pipe or adjustable weir plate of the first layer of tower plate under the action of gravity, forming a certain thickness of solid bed layer; at the same time, high-purity hydrogen chloride gas is introduced from the gas inlet, uniformly distributed through the tower plate, and then upwardly passes through each layer of tower plate to react with the quartz sand on the tower plate in gas-solid phase reaction; Step 3, the solid quartz sand is gradually downwardly passed through the environment with higher and higher temperature and higher and higher concentration of chlorination gas, the impurities are removed by step-by-step chlorination, and the gaseous impurity chlorides generated by the reaction are discharged from the gas outlet at the top of the tower body along with the upward airflow, after the dust entrained is recovered through a gas-solid separator or a filter, the metal chlorides are condensed and precipitated in a water-cooled pipe, and the remaining chlorine / hydrogen chloride enters a dryer to remove moisture, and is continuously pumped into the tower body by a circulating pump to participate in the chlorination reaction; Step 4, the high-purity quartz sand purified through multiple stages in the tower body finally reaches the tower bottom, is continuously discharged through the discharge outlet controlled by a rotary valve, and the final product is obtained after cooling.

[0020] Compared with the prior art, the present application has at least the following obvious advantages and effects: 1. Extremely high and uniform purity: the multi-stage countercurrent fractionation mechanism makes the impurity removal more thorough, different boiling point impurities are separated by stages, cross contamination is avoided, the product purity (SiO2 content) can be stably reached above 99.998%, and the batch and batch uniformity is extremely good.

[0021] 2. High reaction efficiency and low energy consumption: the gas-solid two-phase is in intense contact on the tower plate, the mass and heat transfer area is large and the efficiency is high, and the reaction rate is fast. Compared with the rotary rotating furnace, the reaction time can be shortened by more than 30%, and due to the countercurrent heat exchange, the heat energy utilization rate is high, and the comprehensive energy consumption is significantly reduced.

[0022] 3. High utilization rate of chlorination agent: the upward hydrogen chloride gas contacts with the quartz sand which is “varied in purity” layer by layer, the gas concentration gradient matches the solid purity gradient, so that the chlorination agent is fully utilized in the tower body, the residual chlorine in the tail gas is removed after condensing the metal chlorides to continue to participate in the circulation, reducing the subsequent treatment burden and raw material consumption.

[0023] 4. Operation is flexible and easy to control: by independently adjusting the temperature, gas flow and solid flow rate of each section, it can be flexibly adapted to different origins and different initial impurity contents of quartz sand raw materials, and the process has strong adaptability.

[0024] 5. Continuous production: the device can realize the continuous feeding and discharging of solids, and can control the motor to drive the rotation of the tray to accelerate the discharge of quartz sand according to the production needs, which breaks the bottleneck of traditional batch production and is conducive to large-scale industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the present application; Figure 2 is a structural schematic diagram of the tray in the present application; Component list in the present application: 1, tower body; 2, heating system; 3, tail gas treatment system; 4, power system; 5, tray; 6, rotating shaft; 11, feed inlet; 12, gas outlet; 13, discharge outlet; 14, gas inlet; 21, first heating unit; 22, second heating unit; 23, third heating unit; 31, gas-solid separator; 32, water cooling pipe; 33, desiccant pipe; 34, circulating pump; 41, motor; 42, transmission belt; 43, driving wheel; 44, driven wheel. DETAILED DESCRIPTION

[0026] The specific embodiments of the present application are described in conjunction with the drawings and the following description to teach those skilled in the art how to make and use the best mode of the present application. The following conventional aspects have been simplified or omitted in order to teach the principles of the application. Those skilled in the art should understand that variations from these embodiments fall within the scope of the present application. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present application. The terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present application are only for the convenience of clear description, and are not used to limit the scope of the application, and the change or adjustment of the relative relationship without substantial change of the technical content is also regarded as the scope of the application. Therefore, the present application is not limited to the following specific embodiments, but is defined by the claims and their equivalents.

[0027] Example 1 As Figure 1 and Figure 2As shown, the present embodiment relates to a tower plate fractionation chlorinated quartz sand purification device, characterized in that it comprises a tower body 1, a heating system 2, a tail gas treatment system 3 and a power system 4, the tower body 1 is a vertically arranged high-temperature-resistant and chlorine-resistant cylindrical structure, which is internally provided with multiple layers of tower plates 5 from top to bottom, the tower plates 5 are connected in series through a rotating shaft 6, which divides the tower body 1 into multiple series of reaction stages, the top of the tower body 1 is provided with a feeding port 11 and a gas outlet 12, the bottom of the tower body 1 is provided with a discharge port 13 and an air inlet 14, the discharge port 13 at the bottom of the tower body 1 is provided with a rotary valve or a double gate valve for continuous and sealed discharge. The air inlet 14 at the bottom of the tower body 1 is provided with a chlorination air inlet system for uniform distribution of reaction gas. The heating system 2 is arranged in the tower body and forms a gradient temperature field with gradually decreasing temperature from bottom to top; the tail gas treatment system 3 is communicated with the gas outlet 12 on the tower body to treat the waste gas generated in the tower body and pass the treated waste gas into the tower body 1 for recycling; the power system 4 is drivingly connected with the rotating shaft 6 to drive the rotation of the tower plates 5.

[0028] In the embodiment of the present application, the tower plate 5 is a sieve plate or a bubble cap plate structure, which is made of high-purity quartz glass or silicon carbide, and the surface thereof can be coated with a silicon carbide coating to enhance the corrosion resistance, the rotating shaft 6 penetrates through the center of the tower plate 5, and the tower plate 5 itself allows gas to pass through and can carry a certain thickness of solid quartz sand particles to form a "solid thin layer".

[0029] The tower plate 5 is provided with a flow guide pipe for controlling the downward flow and residence time of the solid quartz sand. By adjusting the size or setting the adjustable weir plate of the flow guide pipe, the residence time of the quartz sand on each tower plate 5 can be accurately controlled to ensure that the reaction is fully carried out.

[0030] The quartz sand raw material is added from the feeding port 11 at the top of the tower body 1 and flows downward layer by layer through each tower plate 5 under the action of gravity; and the high-temperature hydrogen chloride gas is introduced from the air inlet 14 at the bottom of the tower body 1 and flows upward through the solid quartz sand bed layer on each tower plate 5 in counterflow. On each tower plate 5, the downward solid quartz sand and the upward hot hydrogen chloride gas carry out sufficient gas-solid phase mass transfer and reaction. Once the volatile impurity chlorides (such as FeCl3 and TiCl4) are generated, they are carried to the top of the tower by the upward flow to avoid recondensation in the lower temperature range; and the less volatile impurities need to continue to react and separate on the lower tower plate 5 with higher temperature. This multi-stage countercurrent process is similar to the fractionation effect in the rectifying tower, which realizes the step-by-step and efficient removal of impurities with different boiling points.

[0031] In the embodiment of the present application, the heating system 2 comprises an upper heating unit 21, a middle heating unit 22 and a lower heating unit 23. The upper heating unit 21 is a heating furnace, the middle heating unit 22 is a heating pump, and the lower heating unit 23 is a heating rod. By precisely controlling the temperature of the upper, middle and lower parts of the tower body 1, a temperature gradient gradually decreasing from bottom to top is established in the tower body 1. For example, the temperature at the bottom of the tower is the highest (about 1400-1500℃), which is used to remove the most difficult impurities; the temperature at the top of the tower is lower (about 1100-1200℃), which is used for preliminary reaction and to prevent the premature condensation of the already vaporized impurity chlorides.

[0032] In the embodiment of the present application, the tail gas treatment system 3 comprises a gas-solid separator 31 for blocking quartz sand dust, a water-cooled pipe 32 for cooling high-temperature tail gas, a desiccant pipe 33 for drying the cooled gas, and a circulating pump 34 for pumping the gas back into the tower body; the gas outlet 12 is connected to the water-cooled pipe 32 through the gas-solid separator 31, the water-cooled pipe 32 is connected to the desiccant pipe 33, the desiccant pipe 33 is connected to the circulating pump 34, and the circulating pump 34 is connected to the gas inlet 14.

[0033] In addition, the power system 4 comprises a motor 41, a transmission belt 42, a driving wheel 43 and a driven wheel 44; the motor 41 is in driving connection with the driving wheel 43, the driving wheel 43 is in driving connection with the driven wheel 44 through the transmission belt 42, and the driven wheel is in connection with the rotating shaft, so that the motor 41 can be controlled to drive the tower plate 5 to rotate and accelerate the discharge of quartz sand according to production needs.

[0034] Embodiment 2 The present embodiment relates to a tower plate fractional distillation method for purifying chlorinated quartz sand, which specifically comprises the following steps: Step 1: First, the entire device is purged with inert gas (such as nitrogen), and the multi-stage heating unit is started. The lower part of the tower body is heated to 1400℃, the middle part is heated to 1300℃, and the upper part is heated to 1200℃, and the temperature is kept stable.

[0035] Step 2: Solid quartz sand raw materials (particle size range of 100-500μm) are continuously added to the top of the tower through the feed inlet at the top of the tower. Under the action of gravity, the solid quartz sand flows through the flow guide pipe or adjustable weir plate of the first layer of tower plate to the tower plate, forming a certain thickness of solid bed layer; at the same time, high-purity hydrogen chloride gas is introduced from the gas inlet, uniformly distributed through the tower plate, and then upwardly passes through each layer of tower plate to carry out gas-solid phase reaction with the quartz sand on the tower plate. Step 3, the solid quartz sand is layered downward, and experiences an environment with higher and higher temperature and higher and higher concentration of chlorinated gas, impurities are removed by step-by-step chlorination, and gaseous impurity chlorides (such as AlCl3, FeCl3, etc.) generated by the reaction are discharged from the gas outlet at the top of the tower body along with the rising gas flow, after gas-solid separation or filtration to recover the entrained dust, the metal chlorides are condensed and precipitated in the water-cooled pipe, and the remaining chlorine / hydrogen chloride enters the dryer to remove moisture, and is continuously pumped into the tower body by the circulating pump to participate in the chlorination reaction; Step 4, the high-purity quartz sand purified by multiple stages in the tower body finally reaches the bottom of the tower, is continuously discharged through the discharge port controlled by the rotary valve, and is cooled to obtain the final product. After detection, the SiO2 content in the product quartz sand is greater than 99.998%, and the contents of key impurities Ti, Fe, K and Na are all lower than 2ppm.

[0036] The application introduces a tray fractionation structure in the high-purity quartz sand high-temperature chlorination process, and achieves the effect of sufficient gas-solid reaction chlorination purification through uniform dispersion and multi-stage temperature control of the fractionation tower. The application circulates the tail gas, recovers a large amount of unreacted chlorinated gas after condensation and precipitation of the chlorinated gaseous product, reduces the consumption of chlorinated gas, and reduces the cost.

[0037] Any modification, equivalent replacement, improvement, etc. made within the concept and principle of the application can be included in the scope of the claims of the application.

Claims

1. A purification apparatus for chlorinated silica sand by fractional distillation on a tray, characterized in that, It includes tower body, the tower body inside is separated into multiple reaction stages by tower plate, the tower plate is connected by rotating shaft, the tower body top is equipped with feeding port and gas outlet, the tower body bottom is equipped with discharge port and air inlet; Solid quartz sand is passed through each layer of tower plate from top to bottom, chlorination reaction gas is countercurrently passed through each layer of tower plate from bottom to top; Heating system is arranged in the tower body and forms gradient temperature field from bottom to top; Tail gas treatment system is communicated with the gas outlet on the tower body and treats the waste gas generated in the tower body; Power system is transmission connected with rotating shaft to drive the rotation of tower plate.

2. The tray fractionating fused silica purification apparatus of claim 1, wherein, The tower plate is sieve plate or bubble cap plate structure, and the material is high-purity quartz glass or silicon carbide, and the rotating shaft passes through the center of the tower plate.

3. The tray fractionating fused silica purification apparatus of claim 1, wherein, The tower plate is equipped with flow guide pipe or adjustable weir plate for controlling the downward flow and residence time of solid quartz sand.

4. The tray fractional distillation of chlorinated silica sand purification apparatus according to claim 1, characterized by, The heating system includes upper heating unit, middle heating unit and lower heating unit, the upper heating unit is heating furnace, the middle heating unit is heating pump, and the lower heating unit is heating rod.

5. The tray fractional distillation of chlorinated silica sand purification apparatus according to claim 1, characterized by, The tail gas treatment system includes gas-solid separator or filter for blocking quartz sand dust, water cooling pipe for cooling high temperature tail gas, drying agent pipe for drying and cooling gas, and circulating pump for recycling gas into the tower body; The gas outlet is connected with the water cooling pipe through the gas-solid separator or filter, the water cooling pipe is connected with the drying agent pipe, the drying agent pipe is connected with the circulating pump, and the circulating pump is connected with the air inlet.

6. The tray fractional distillation of chlorinated silica sand purification apparatus according to claim 1, characterized in that, The power system includes motor, transmission belt, driving wheel and driven wheel; The motor is transmission connected with the driving wheel, the driving wheel is transmission connected with the driven wheel through the transmission belt, and the driven wheel is connected with the rotating shaft.

7. The tray fractional distillation of chlorinated silica sand purification apparatus of claim 1, wherein, The discharge port at the bottom of the tower body is equipped with rotary valve or double gate valve for continuous and sealed discharge.

8. The tray fractional distillation of chlorinated silica sand purification apparatus according to claim 1, characterized by, The air inlet at the bottom of the tower body is equipped with chlorination air inlet system for uniform distribution of reaction gas.

9. A purification method of chlorinated silica sand by fractional distillation on a tray, for the apparatus according to any one of claims 1 to 8, characterized in that, It includes the following steps: Step 1, first, the whole device is purged with inert gas, the multi-stage heating unit is started, the lower section of the tower body is heated to 1400℃, the middle section is heated to 1300℃, and the upper section is heated to 1200℃, and the temperature is kept stable; Step 2, solid quartz sand raw material is continuously added to the top of the tower body through the feeding port at the top of the tower body, the solid quartz sand flows to the tower plate through the flow guide pipe or adjustable weir plate of the first layer of tower plate under the action of gravity, and forms a certain thickness of solid bed layer; At the same time, high-purity hydrogen chloride gas is introduced from the air inlet, uniformly distributed through the tower plate, and then upwardly passes through each layer of tower plate to carry out gas-solid phase reaction of chlorination purification with the quartz sand on the tower plate; Step 3, the solid quartz sand is passed through the environment with higher and higher temperature and higher and higher concentration of chlorination gas layer by layer downwardly, the impurities are removed by chlorination step by step, the gaseous impurity chlorides generated by the reaction are discharged from the gas outlet at the top of the tower body along with the upward airflow, the dust entrained after the gas-solid separator or filter is recovered, the metal chlorides are condensed and precipitated in the water cooling pipe, the remaining chlorine / hydrogen chloride enters the dryer to remove water, and then is continuously pumped into the tower body by the circulating pump to participate in the chlorination reaction; Step 4, the high-purity quartz sand purified by multiple stages in the tower body finally reaches the tower bottom, is continuously discharged through the discharge port controlled by the rotary valve, and the final product is obtained after cooling.

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