Ultrafine grinding and cooling process for producing kaolin raw material

Abstract

The invention discloses a superfine grinding and cooling process for producing a kaolin raw material. The superfine grinding and cooling process comprises the following steps: (1) pulping; (2) front-section wet grinding; (3) cooling: pumping the slurry A in the step (2) into a cooling tower for cooling through a slurry pump at the flow rate of 30-70m < 3 > / h to obtain slurry B with the temperature of 30-45 DEG C and the mass concentration of 35-45%; and (4) carrying out rear-section wet grinding. The superfine grinding and cooling process for producing the kaolin raw material has the beneficial effects that the particle collision requirement of superfine grinding is met, the consumption of a dispersing agent is reduced due to low temperature, the total consumption of the dispersing agent is finally reduced, the use cost of the raw material is further reduced, the service life of rear-section wet grinding equipment is prolonged, the maintenance cost is reduced, and the service life of the kaolin raw material is prolonged. And the granularity D92 of the slurry is less than 2 microns, less impurities are introduced, and the qualified rate of the product is more than 95%.

Description

Technical Field

[0001] This invention patent relates to the technical field of kaolin grinding, specifically to an ultrafine grinding and cooling process for producing kaolin raw materials. Background Technology

[0002] Kaolin is a super-white, ultra-fine powder, widely used in papermaking, ceramics, pharmaceuticals, inks, and coatings. Currently, industrial production of kaolin can be divided into two processes: dry processing and wet processing. Dry processing is commonly used for the separation of hard kaolin, while wet processing is commonly used for the separation of soft and sandy kaolin. The wet processing flow includes raw ore crushing, wet grinding, drying, calcination, and reduction. This process mainly employs wet ultrafine processing, making it easy to achieve a product particle size of 2μm~90%, with reliable processing and easy handling of impurities such as iron and titanium.

[0003] Patent CN201520792375.6 discloses a kaolin ultrafine wet grinding system, which includes a slurry tank, a dispersant tank, wet grinding equipment, and finished product processing equipment. The wet grinding equipment consists of a front-end wet grinding unit and a rear-end wet grinding unit connected in series. The outlet of the slurry tank is connected to the inlet of the front-end wet grinding unit via a pump. The dispersant tank is connected to the rear-end wet grinding unit via a pipeline. The outlet of the rear-end wet grinding unit is opposite to the inlet of the finished product processing equipment, used to guide the ground slurry to the finished product processing equipment for further processing. This invention has advantages such as high grinding efficiency, low dispersant usage, and narrow particle size distribution of the ground kaolin, effectively avoiding the impact on subsequent processes caused by slurry agglomeration and increased viscosity due to repeated grinding and over-grinding.

[0004] Patent CN201010180259.0 discloses a method for wet production of ultrafine kaolin slurry. The method includes a pulping step to prepare a raw slurry with a solid content ≥45%; at least one wet milling step, in which the prepared raw slurry is pumped to a wet mill via a silo pump, the raw slurry and dispersant are added from the top of the wet mill, and the raw slurry is wet-milled by grinding balls placed inside the wet mill. The slurry after wet milling flows out from the bottom of the wet mill, and the outlet temperature of the slurry after each stage of wet milling is ≤65℃; a filtration step, in which the wet-milled slurry is fed to a vibrating screen to filter out broken grinding balls, obtaining the finished slurry. Preferably, a four-stage series wet milling process is used. This method can reduce the temperature of the slurry during wet milling, thereby reducing the viscosity of the slurry, reducing the amount of dispersant used, and reducing pipeline blockage. This method can ensure continuous production and improve production efficiency.

[0005] However, the aforementioned existing technology has the following problems: 1. When the solid content is controlled at ≥45% during the wet grinding slurry preparation stage, the particle spacing of coal gangue is compressed to ≤40nm, resulting in high van der Waals force strength and increased particle collision frequency, which easily leads to the formation of "particle clusters". If no dispersant is added, the grinding efficiency will drop sharply (coarse particles cannot be effectively broken). Therefore, a large amount of dispersant needs to be adsorbed on the particle surface to form electrostatic repulsion or steric hindrance to break up the clusters. As a result, in current production, the mass of dispersant is 0.5-0.8% of the coal gangue powder during the initial slurry preparation, and 0.4-0.6% of dispersant needs to be added during the later wet grinding process, thus increasing the cost of raw materials.

[0006] 2. Multi-stage wet grinding will cause the heat generated by grinding to accumulate. Although the existing technology CN201010180259.0 limits the temperature of a single-stage wet grinding to ≤65℃, the slurry temperature of the wet grinding equipment will be higher and higher after four stages are connected in series, even reaching 60-70℃. High temperature will accelerate the aging and failure of the equipment, thus leading to a significant reduction in the equipment life.

[0007] 3. The kaolin component of coal gangue is extremely sensitive to grinding temperature. However, "temperature control" and "particle size maintenance" present an insurmountable contradiction. Existing cooling methods reduce the solid content of the slurry to decrease frictional heat generation between particles. However, a lower particle concentration in the slurry reduces the probability of collisions between the grinding media (such as ceramic beads) and the particles, leading to reduced grinding efficiency and failing to meet the ultrafine requirements of kaolin. On the other hand, maintaining high solid content and high grinding intensity to ensure particle size further increases the temperature. This causes surface lattice distortion in the kaolin particles in the coal gangue, and some particles soften due to high temperatures, resulting in the consumption of extra energy without achieving finer grinding. This wastes energy and reduces product quality stability. Simultaneously, high solid content increases the wear rate of steel balls, and high temperatures cause softening and detachment of ceramic ball surfaces, further increasing the content of Fe2O3 and Al2O3 impurities in the slurry. Consequently, the product qualification rate is only 85%. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide an ultrafine grinding and cooling process for producing kaolin raw materials. The ultrafine grinding and cooling process provided by this invention not only meets the particle collision requirements of ultrafine grinding, but also reduces the consumption of dispersant due to low temperature, ultimately reducing the total amount of dispersant used, thereby reducing the cost of raw materials, increasing the service life of the downstream wet grinding equipment, reducing maintenance costs, achieving a slurry particle size of D92 < 2μm, introducing fewer impurities, and achieving a product qualification rate of over 95%.

[0009] The present invention discloses an ultrafine grinding and cooling process for producing kaolin raw materials, which includes the following steps: (1) Pulping: Raw material powder with a particle size <5mm, dispersant with a particle size <5mm, and water are stirred and mixed to form a raw slurry with a solid content of 30-35%. The mass of the dispersant is 0.3-0.5% of the raw material powder. The raw material powder includes 92-100% coal gangue powder by mass, and the remainder is raw ore powder, which is one or more of kaolinite and purple wood knot. The solid content is reduced from the traditional ≥45% to 30-35%, and the particle spacing in the slurry is increased from ≤40nm to 100-120nm. The van der Waals forces are greatly reduced. Therefore, the following wet milling in the first stage does not require a large amount of dispersant to maintain the dispersion state. Among them, sodium hexametaphosphate, a dispersant, can achieve "complexation-double electric layer stabilization" without a high dose: Al exposed on the particle surface at low concentrations 3+ Fe 3+ With a lower density of active sites, a small amount of sodium hexametaphosphate can complete the complexation, avoiding the waste caused by the uncomplexed dispersant dissolving directly in water; at low concentrations, the particle collision frequency is low, and the double electric layer does not need to be too thick to maintain dispersion, and the adsorption capacity of sodium hexametaphosphate is reduced from the traditional 8 mg / g to 5 mg / g, so the amount used is naturally reduced.

[0010] (2) Pre-processing wet milling: The raw pulp from step (1) is milled at a flow rate of 30-70 m³ / h. 3 The slurry A discharged from the front-end wet grinding equipment is fed into the mill at a temperature of 50-65℃, a mass concentration of 30-42%, and a particle size distribution of D90 < 2μm. At low concentrations, the collision intensity between the grinding balls (steel balls) and the particles decreases, and the metal wear rate drops from the traditional 0.5% / thousand-hour to 0.4%, Fe... 3+ Impurity release is reduced by 20%. No additional sodium hexametaphosphate is required to complex the newly added Fe. 3+ This further reduces ineffective usage.

[0011] (3) Cooling: Cool the slurry A from step (2) at a flow rate of 30-70 m³ / h 3 The slurry is pumped to a cooling tower by a slurry pump to obtain slurry B with a temperature of 30-45℃ and a mass concentration of 35-45%. The cooling tower not only cools the slurry, but also concentrates it through evaporation, thereby increasing the concentration of sodium hexametaphosphate. This is equivalent to "increasing the concentration of the effective dispersant without increasing the dosage", laying the foundation for subsequent high-concentration grinding.

[0012] (4) Subsequent wet grinding: The slurry B from step (3) is ground at a flow rate of 30-70 m³ / h. 3The raw material powder is fed into the downstream wet mill at a temperature of 40-45℃, with the dispersant added simultaneously. The resulting slurry C has a mass concentration of 40-50% and a particle size distribution of D92 < 2μm. The mass of the added dispersant is 0.2-0.4% of the raw material powder. Although the downstream wet milled slurry B has a high solids content of 38-41%, the cooling tower lowers the temperature to 30-45℃, far below the 60-70℃ of the traditional process. The low temperature slows down the Brownian motion of the particles, reduces the tendency to agglomerate, and lessens the load on the dispersant to maintain dispersion. Furthermore, the low temperature effectively reduces the hydrolysis rate of sodium hexametaphosphate, increasing the retention rate of effective dispersing groups (long-chain polyphosphates) from 40% to 90%. Therefore, the amount of dispersant added in the downstream wet mill is reduced by 50-33%.

[0013] Furthermore, the dispersant in steps (1) and (4) is one or more of sodium hexametaphosphate and sodium polyacrylate.

[0014] Furthermore, the front-end wet grinding equipment in step (2) includes a wet ball mill connected in series and 4-10 first wet ultrafine mills.

[0015] Furthermore, the grinding parameters of the wet ball mill are as follows: steel ball gradation: 20-25% steel balls with a diameter of 20-25mm, 30-35% steel balls with a diameter of 25-30mm, and 40-45% steel balls with a diameter of 3-3.5mm; steel ball filling rate: 15-30%; grinding speed: 18-20 r / min; grinding time: 20-50 min. The wet ball mill is manufactured by Henan Huahong Heavy Machinery Manufacturing Co., Ltd., and the model is Φ3.2*13.

[0016] Furthermore, the grinding parameters of the first wet ultrafine grinding mill are as follows: the filling rate of ceramic balls with a diameter of 2.0-3.5 mm is 10-25%; the grinding speed is 1400-1500 r / min; and the grinding time is 30-60 min.

[0017] Furthermore, the cooling tower in step (3) includes a tower frame, a tower body, slurry outlet pipes, and a slurry tank. The tower body is fixed on the tower frame, and several slurry outlet pipes are horizontally fixed above the tower body. Several water outlet holes are opened on the side walls of the slurry outlet pipes, and the outlet of the slurry pump is connected to the inlet of the slurry outlet pipes through a pipe. The slurry tank is fixed on the tower frame below the tower body. The bottom of the tower body is designed to be open, and several ventilation windows are opened on the side walls of the tower body. The outlet of the slurry tank is connected to the outlet of the slurry tank in step (4). The inlet of the downstream wet grinding equipment and the inlet of the reflux pump are connected by a pipeline, and the outlet of the reflux pump is connected to the inlet of the slurry outlet pipe by a pipeline. A concentration sensor and a level sensor are respectively installed in the slurry tank, and a solenoid valve is installed on the pipeline between the slurry tank and the downstream wet grinding equipment. The signal output terminals of the concentration sensor and the level sensor are both connected to the signal input terminal of the controller by a signal connection. The signal output terminal of the controller is connected to the signal input terminals of the slurry pump, the reflux pump and the solenoid valve by a signal connection.

[0018] Furthermore, the liquid level sensor and the concentration sensor continuously monitor the liquid level and slurry concentration in the slurry tank and transmit the signals to the controller. When the liquid level reaches the upper limit and the concentration does not reach the design value, the controller controls the slurry pump to shut down and the reflux pump to turn on for reflux. When the concentration reaches the set value, the controller controls the reflux pump to shut down and the solenoid valve to open. When the liquid level drops to the lower limit, the controller controls the solenoid valve to close and the slurry pump to open. When the liquid level reaches the upper limit and the concentration reaches the design value, the controller directly controls the solenoid valve to open.

[0019] Furthermore, a slurry distribution pipe is fixed on the tower, and the side wall of the slurry distribution pipe is fixedly connected to the inlet of each of the slurry outlet pipes. One end of the slurry distribution pipe is connected to the outlet of the slurry pump and the return pump through a pipe. A baffle is fixed around the perimeter of the bottom opening of the tower body. The bottom edge of the baffle is inclined towards the inside of the tower body, and the size of the outlet opening formed by the bottom edge of the baffle is smaller than the size of the top opening of the slurry tank.

[0020] Furthermore, the downstream wet grinding equipment in step (4) includes 4-10 second wet ultrafine grinding mills connected in series.

[0021] Furthermore, the grinding parameters of the second wet ultrafine grinding mill are as follows: the filling rate of ceramic balls with a diameter of 2.0-3.5 mm is 10-25%; the grinding speed is 1400-1500 r / min; and the grinding time is 30-60 min.

[0022] The manufacturer of the first and second wet ultrafine grinding mills is Jiangsu Zhongyuan Machinery Equipment Manufacturing Co., Ltd., and the model number is SCM-25000.

[0023] Advantages of this invention: 1. This invention discloses an ultrafine grinding and cooling process for producing kaolin raw materials. When preparing the raw slurry, the solid content can be reduced to 30-35%. After passing through the wet grinding stage A, the slurry is cooled in a cooling tower, and the water evaporates by 2-5%. The resulting slurry B has a lower temperature and higher concentration. The subsequent wet grinding equipment receives the cooled "high concentration + low temperature" slurry B, which not only meets the particle collision requirements of ultrafine grinding, but also reduces the consumption of dispersant due to the low temperature, ultimately reducing the total amount of dispersant used and thus reducing the cost of raw materials.

[0024] 2. This invention discloses an ultrafine grinding and cooling process for producing kaolin raw materials. Through cooling tower cooling, the temperature of the slurry B in the subsequent wet grinding stage drops to 30-45℃. The low temperature increases the service life of the seals, bearings, etc. of the subsequent wet grinding equipment, thereby increasing the service life of the subsequent wet grinding equipment and reducing maintenance costs.

[0025] 3. This invention discloses an ultrafine grinding and cooling process for producing kaolin raw materials. The first stage is low-concentration wet grinding, which prevents excessive particle agglomeration and results in a more uniform particle size distribution after coarse crushing, laying the foundation for the subsequent ultrafine grinding. The subsequent low-temperature high-concentration wet grinding avoids particle lattice distortion and reduces wear of the grinding media. The temperature is controllable throughout the process, and there is no "over-grinding without refinement" phenomenon. The slurry particle size reaches D92 < 2μm, with less impurity introduction and a product qualification rate of over 95%. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a system flowchart of Embodiment 1 of the present invention.

[0028] Figure 2 This is a schematic diagram of the cooling tower structure of the present invention.

[0029] Figure 3 This is a schematic diagram of the connection structure between the slurry distribution pipe and the slurry outlet pipe.

[0030] Figure 4 This is a schematic diagram of the control system for the cooling tower of the present invention.

[0031] The equipment includes: front-end wet grinding equipment 1, wet ball mill 11, first wet ultrafine grinding mill 12, slurry pump 3, cooling tower 4, tower frame 401, tower body 402, ventilation window 4021, slurry outlet pipe 403, water outlet hole 4031, slurry tank 404, reflux pump 405, concentration sensor 406, liquid level sensor 407, solenoid valve 408, controller 409, slurry distribution pipe 410, baffle 411; rear-end wet grinding equipment 5, second wet ultrafine grinding mill 51. Detailed Implementation

[0032] The present invention will be further described in detail below through embodiments.

[0033] Example 1: As Figure 1-4 As shown, an ultrafine grinding and cooling process for producing kaolin raw materials includes the following steps: (1) Pulping: The raw material powder with a particle size <5mm, the dispersant with a particle size <5mm and water are stirred and mixed to form a raw slurry with a solid content of 30%, wherein the mass of the dispersant is 0.3% of the raw material powder, and the dispersant is sodium hexametaphosphate. The raw material powder includes 95% coal gangue powder and 5% raw ore powder by mass, and the raw ore powder is one or more of kaolinite and purple wood knot. (2) Pre-processing wet milling: The raw pulp from step (1) is processed at a flow rate of 30-70 m³ / h. 3 The slurry A discharged from the front-end wet grinding equipment 1 is fed into the front-end wet grinding equipment 1 for grinding. The temperature of the slurry A is 50-65℃, the mass concentration is 30-42%, and the particle size distribution is D90<2μm. The front-end wet grinding equipment 1 includes a wet ball mill 11 and four first wet ultrafine mills 12 connected in series.

[0034] The grinding parameters of the wet ball mill 11 are as follows: steel ball gradation: 20-25% steel balls with a diameter of 20-25mm, 30-35% steel balls with a diameter of 25-30mm and 40-45% steel balls with a diameter of 3-3.5mm; steel ball filling rate: 15-30%; grinding speed: 18-20r / min; grinding time: 20-50min.

[0035] The grinding parameters of the first wet ultrafine grinding mill 12 are as follows: the filling rate of ceramic balls with a diameter of 2.0-3.5mm is 10-25%; the grinding speed is 1400-1500r / min; and the grinding time is 30-60min.

[0036] (3) Cooling: Cool the slurry A from step (2) at a flow rate of 30-70 m³ / h 3 The slurry is pumped by pump 3 to cooling tower 4 at a temperature of 30-45℃ and a mass concentration of 35-45% to obtain slurry B.

[0037] The cooling tower 4 includes a tower frame 401, a tower body 402, slurry outlet pipes 403, and a slurry tank 404. The tower body 402 is fixed on the tower frame 401. Several slurry outlet pipes 403 are horizontally fixed above the tower body 402. Several water outlet holes 4031 are opened on the side wall of the slurry outlet pipes 403. The outlet of the slurry pump 3 is connected to the inlet of the slurry outlet pipes 403 through a pipe. The slurry tank 404 is fixed on the tower frame 401 below the tower body 402. The bottom of the tower body 402 is open. Several ventilation windows 4021 are opened on the side wall of the tower body 402. The outlet of the slurry tank 404 is connected to the outlet of the slurry tank 404 in step (4). The inlet of the wet grinding equipment 5 and the inlet of the reflux pump 405 are connected by a pipeline. The outlet of the reflux pump 405 is connected to the inlet of the slurry outlet pipe 403 by a pipeline. A concentration sensor 406 and a level sensor 407 are respectively installed in the slurry tank 404. A solenoid valve 408 is installed on the pipeline between the slurry tank 404 and the downstream wet grinding equipment 5. The signal output terminals of the concentration sensor 406 and the level sensor 407 are both connected to the signal input terminal of the controller 409 by a signal. The signal output terminal of the controller 409 is connected to the signal input terminals of the slurry pump 3, the reflux pump 405 and the solenoid valve 408 by a signal.

[0038] The level sensor 407 and the concentration sensor 406 continuously monitor the level and concentration of the slurry in the slurry tank 404 and transmit the signals to the controller 409. When the level reaches the upper limit and the concentration does not reach the design value, the controller 409 controls the slurry pump 3 to shut down and opens the return pump 405 for reflux. When the concentration reaches the set value, the controller 409 controls the return pump 405 to shut down and the solenoid valve 408 to open. When the level drops to the lower limit, the controller 409 controls the solenoid valve 408 to shut down and the slurry pump 3 to open. When the level reaches the upper limit and the concentration reaches the design value, the controller 409 directly controls the solenoid valve 408 to open.

[0039] A slurry distribution pipe 410 is fixed on the tower 401. The side wall of the slurry distribution pipe 410 is fixedly connected to the inlet of each slurry outlet pipe 403. One end of the slurry distribution pipe 410 is connected to the outlet of the slurry pump 3 and the return pump 405 through a pipe. A baffle 411 is fixed around the bottom opening of the tower body 402. The bottom edge of the baffle 411 is inclined inward towards the tower body 402. The size of the outlet opening formed by the bottom edge of the baffle 411 is smaller than the size of the top opening of the slurry tank 404.

[0040] 4) Subsequent wet grinding: The slurry B from step (3) is ground at a flow rate of 30-70 m³ / h. 3 The material is fed into the downstream wet grinding equipment 5 at a temperature of 40-45℃, with a mass concentration of 40-50% and a particle size distribution of D92 < 2μm. The mass of the added dispersant is 0.2% of the raw material powder, and the dispersant is sodium hexametaphosphate.

[0041] The downstream wet grinding equipment 5 includes four second wet ultrafine grinding mills 51 connected in series. The grinding parameters of the second wet ultrafine grinding mills 51 are as follows: the filling rate of ceramic balls with a diameter of 2.0-3.5mm is 10-25%; the grinding speed is 1400-1500r / min; and the grinding time is 30-60min.

[0042] Example 2: The overall method is the same as in Example 1, except that in step (1), a slurry with a solid content of 32% is formed, wherein the mass of the dispersant is 0.4% of the raw material powder; in step (2), the front-end wet grinding equipment 1 includes a wet ball mill 11 and five first wet ultrafine mills 12 connected in series. In step (4), the mass of the added dispersant is 0.3% of the raw material powder; the rear-end wet grinding equipment 5 includes five second wet ultrafine mills 51 connected in series.

[0043] Example 3: The overall method is the same as in Example 1, except that in step (1), a slurry with a solid content of 35% is formed, wherein the mass of the dispersant is 0.5% of the raw material powder; in step (2), the front-end wet grinding equipment 1 includes a wet ball mill 11 and 10 first wet ultrafine mills 12 connected in series. In step (4), the mass of the added dispersant is 0.4% of the raw material powder; the rear-end wet grinding equipment 5 includes 10 second wet ultrafine mills 51 connected in series.

[0044] Comparative Example 1: The process disclosed in the prior art CN201010180259.0, wherein the solid content of the pulp is 45%, the mass of the dispersant added in the early wet mill is 0.8% of the coal gangue powder, and the mass of the dispersant added in the later wet mill is 0.6% of the coal gangue powder.

[0045] Comparative Example 2: The overall method is the same as in Example 1, except that step (3) is not performed. The slurry A obtained from the wet grinding in step (2) is directly subjected to the wet grinding in step (4).

[0046] Experiment: A daily production capacity of 50 tons of kaolin was used, with an experimental period of 72 hours (3 consecutive production cycles). The average data was taken. Specific test results are as follows:

[0047] As can be seen from the table above, the dispersant consumption in Example 1 was 5.0 kg / ton, which was 33.3% lower than that in Comparative Example 2 (7.5 kg / ton). The low temperature reduced the hydrolysis rate of sodium hexametaphosphate by 60%, and the retention rate of effective dispersing groups increased from 60% in Comparative Example 2 to 90%, without the need for additional dispersant.

[0048] The Fe2O3 impurity in Example 1 was 0.10%, and the Al2O3 impurity was 0.06%, which was lower than that in Comparative Example 2. As a result, the finished product qualification rate of Example 1 was 98.5%, which was higher than that of Comparative Example 2 (90%). Low temperature reduces wear of grinding media, avoids the introduction of impurities, and prevents lattice distortion of kaolin particles, thus reducing the phenomenon of "over-grinding without fineness".

[0049] The high solids content of 45% in Comparative Example 1 resulted in severe particle agglomeration, with the total dispersant usage reaching 1.4% (14.0 kg / ton), and 40% was wasted due to high-temperature hydrolysis. Examples 1-3 of this invention, with low solids content (30-35%), reduced agglomeration, with dispersant usage of only 0.5-0.9%, and the unit consumption was 35.7-64.3% lower than that of Comparative Example 1. Based on sodium hexametaphosphate at 8000 yuan / ton, this translates to a saving of 72 yuan per ton of finished product.

[0050] The finished product of Comparative Example 1 has a D92 of 2.8 μm, Fe2O3 of 0.29%, and a pass rate of only 70%. The finished products of Examples 1-3 of this invention have a D92 of 1.6-1.8 μm, impurities of ≤0.12%, and a pass rate of over 97.5%, and can be directly used in electronic ceramics (priced at RMB 1500 / ton), which increases the added value by 87.5% compared to the product of Comparative Example 1 (RMB 800 / ton).

[0051] Example 2 has the best overall benefits, namely, the finished product D92=1.6μm (uniform particle size), energy consumption of 92kWh / ton (low), and a pass rate of 98% (stable). It avoids the "risk of insufficient grinding" caused by the small number of equipment stages in Example 1, and avoids the "redundant energy consumption" caused by the large number of stages in Example 3.

[0052] The above are preferred embodiments of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An ultrafine grinding and cooling process for producing kaolin raw materials, characterized in that, It includes the following steps: (1) Pulping: Mix raw material powder with a particle size <5mm, dispersant with a particle size <5mm and water to form a raw slurry with a solid content of 30-35%, wherein the mass of the dispersant is 0.3-0.5% of the raw material powder, the raw material powder includes 92-100% coal gangue powder by mass, the remainder being raw ore powder, the raw ore powder being one or more of kaolinite and purple wood knot; (2) Pre-processing wet milling: The raw pulp from step (1) is milled at a flow rate of 30-70 m³ / h. 3 The slurry A discharged from the front-end wet grinding equipment is fed into the front-end wet grinding equipment at a temperature of 50-65℃, a mass concentration of 30-42%, and a particle size distribution of D90 < 2μm. (3) Cooling: Cool the slurry A from step (2) at a flow rate of 30-70 m³ / h 3 The slurry is pumped to a cooling tower by a slurry pump at a temperature of 30-45℃ and a mass concentration of 35-45% to obtain slurry B. (4) Subsequent wet grinding: The slurry B from step (3) is ground at a flow rate of 30-70 m³ / h. 3 The raw material is fed into a downstream wet grinding equipment at a temperature of 40-55℃, with a mass concentration of 40-50% and a particle size distribution of D92 < 2μm. The mass of the added dispersant is 0.2-0.4% of the raw material powder.

2. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 1, characterized in that, The dispersant in steps (1) and (4) is one or more of sodium hexametaphosphate and sodium polyacrylate.

3. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 1, characterized in that, The front-end wet grinding equipment in step (2) includes a wet ball mill connected in series and 4-10 first wet ultrafine mills.

4. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 3, characterized in that, The grinding parameters of the wet ball mill are as follows: steel ball gradation: 20-25% steel balls with a diameter of 20-25mm, 30-35% steel balls with a diameter of 25-30mm, and 40-45% steel balls with a diameter of 3-3.5mm; steel ball filling rate: 15-30%; grinding speed: 18-20r / min; grinding time: 20-50min.

5. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 3, characterized in that, The grinding parameters of the first wet ultrafine grinding mill are as follows: the filling rate of ceramic balls with a diameter of 2.0-3.5 mm is 10-25%; the grinding speed is 1400-1500 r / min; and the grinding time is 30-60 min.

6. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 1, characterized in that, The cooling tower in step (3) includes a tower frame, a tower body, slurry outlet pipes, and a slurry tank. The tower body is fixed on the tower frame, and several slurry outlet pipes are horizontally fixed above the tower body. Several water outlet holes are opened on the side walls of the slurry outlet pipes. The outlet of the slurry pump is connected to the inlet of the slurry outlet pipes through a pipe. The slurry tank is fixed on the tower frame below the tower body. The bottom of the tower body is open, and several ventilation windows are opened on the side walls of the tower body. The outlet of the slurry tank is connected to the outlet of the cooling tower in step (4). The inlet of the downstream wet grinding equipment and the inlet of the reflux pump are connected by a pipeline, and the outlet of the reflux pump is connected to the inlet of the slurry outlet pipe by a pipeline. A concentration sensor and a level sensor are respectively installed in the slurry tank. A solenoid valve is installed on the pipeline between the slurry tank and the downstream wet grinding equipment. The signal output terminals of the concentration sensor and the level sensor are both connected to the signal input terminal of the controller by a signal connection. The signal output terminal of the controller is connected to the signal input terminals of the slurry pump, the reflux pump and the solenoid valve by a signal connection.

7. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 6, characterized in that, The liquid level sensor and the concentration sensor continuously monitor the liquid level and slurry concentration in the slurry tank and transmit the signals to the controller. When the liquid level reaches the upper limit and the concentration does not reach the design value, the controller controls the slurry pump to shut down and the reflux pump to turn on for reflux. When the concentration reaches the set value, the controller controls the reflux pump to shut down and the solenoid valve to open. When the liquid level drops to the lower limit, the controller controls the solenoid valve to close and the slurry pump to open. When the liquid level reaches the upper limit and the concentration reaches the design value, the controller directly controls the solenoid valve to open.

8. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 6, characterized in that, A slurry distribution pipe is fixed on the tower. The sidewall of the slurry distribution pipe is fixedly connected to the inlet of each slurry outlet pipe. One end of the slurry distribution pipe is connected to the outlet of the slurry pump and the return pump through a pipe. A baffle is fixed around the perimeter of the bottom opening of the tower body. The bottom edge of the baffle is inclined towards the inside of the tower body. The size of the outlet opening formed by the bottom edge of the baffle is smaller than the size of the top opening of the slurry tank.

9. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 1, characterized in that, The downstream wet grinding equipment in step (4) includes 4-10 second wet ultrafine grinding mills connected in series.

10. The ultrafine grinding and cooling process for producing kaolin raw materials according to claim 9, characterized in that, The grinding parameters of the second wet ultrafine grinding mill are as follows: the filling rate of ceramic balls with a diameter of 2.0-3.5 mm is 10-25%; the grinding speed is 1400-1500 r / min; and the grinding time is 30-60 min.

Images