Production method of calcined kaolin with relatively good solubility

Abstract

The invention relates to an improved production method of calcined kaolin, in particular to extraction of kaolin from coal gangue and optimization of the production process so as to improve the solubility of a final product and reduce the viscosity of the final product. The method mainly comprises the steps of raw material pretreatment, dry grinding and nanoscale crushing, wet grinding and special additive application, optimized calcination process and product inspection and packaging. In the raw material pretreatment stage, coal gangue kaolin is firstly subjected to water washing and high-gradient magnetic separation so as to remove impurities and iron substances; then, the raw materials are crushed to be uniform in size, and preparation is made for the subsequent grinding process. In the dry-method grinding stage, a jet mill dry-method grinding technology is adopted, and nano-scale crushing is combined, so that finer powder is obtained. In addition, a surfactant and a dispersing agent are added in the wet grinding process, so that the wettability and dispersity of the kaolin are improved. The calcining process is optimized, and a segmented temperature control technology is adopted, so that the physical and chemical characteristics of kaolin are improved. Through a series of process optimization, the kaolin product disclosed by the invention is remarkably improved in solubility and viscosity, so that the kaolin product is more suitable for industries such as papermaking, coating and the like. In addition, the implementation of the method helps to improve energy utilization efficiency and environmental friendliness.

Description

Technical Field

[0001] The invention belongs to the technical field of non-metallic mineral modification, and in particular relates to a production method of calcined kaolin with good solubility. Background Art

[0002] Kaolin is an important non-metallic mineral, widely used in papermaking, ceramics, rubber, coatings and other industries. As a resource, the conversion of coal gangue into calcined kaolin is an important direction for comprehensive resource utilization. However, the existing kaolin production methods have the following main problems: 1. Product quality issues: In traditional calcination methods, the structure of kaolin is easily affected by calcination temperature and time, resulting in unstable product quality. In particular, the unevenness of particle size distribution and particle shape will directly affect its performance in downstream applications.

[0003] 2. Environmental protection and energy efficiency: The production process of kaolin, especially the calcination step, consumes a lot of energy and may produce harmful gases. The wet grinding process uses a lot of water resources, and the wastewater generated needs to be strictly treated, which not only increases costs but also puts pressure on the environment.

[0004] 3. Solubility and viscosity issues: During the calcination process, the physical and chemical structures of kaolin particles change, and these changes usually lead to reduced solubility in water and increased viscosity. Especially when used in the coating or papermaking industry, high viscosity calcined kaolin will affect product quality and production efficiency.

[0005] These technical problems not only increase production costs, but also limit the application of kaolin products in certain fields. For example, in the paper industry, when kaolin is used as a filler or coating, high viscosity will lead to processing difficulties, increased energy consumption and waste of raw materials. In the coating industry, poorly soluble kaolin will affect the uniformity and appearance quality of the coating.

[0006] Existing improvement efforts are mainly focused on optimizing the calcination process and grinding technology. Although these improvements have improved product quality to a certain extent, they are far from enough to solve the solubility and viscosity problems. Existing technologies rarely take into account the detailed control of the production process, such as the pretreatment of raw materials, particle size control and the use of chemical additives, which are key factors in improving product quality.

[0007] In summary, the existing calcined kaolin production technology has significant deficiencies in product quality, environmental protection and energy efficiency. These deficiencies not only affect the application of kaolin in specific industries, but also limit its market potential. Therefore, the development of a new, environmentally friendly and efficient kaolin production method is not only a technical demand, but also a market and environmental protection need. Summary of the invention

[0008] In order to solve the problem of insufficient adsorption capacity of kaolin adsorbents in the prior art in removing heavy metals from wastewater, the present invention provides a new method for modifying kaolin. The purpose of the present invention is to design a new kaolin adsorbent, which not only has high adsorption efficiency and selectivity for specific heavy metals, but also has an environmentally friendly production process, low cost, and is easy to industrialize. The method described in the present invention specifically includes the following steps: 1. Raw material pretreatment Water washing and magnetic separation: First, the gangue kaolin is soaked in water for 24 hours, and the water temperature is kept at room temperature. Then, the iron impurities are removed by a strong magnetic separator (magnetic field strength of 1500 gauss).

[0009] Crushing: The gangue kaolin is processed by a crusher and crushed to a uniform size of about 3-5cm. The crushed materials are separated by a vibrating screen to ensure the consistency of particle size.

[0010] 2. Combination of dry grinding and nanotechnology Airflow mill dry grinding: The crushed gangue kaolin is ground to an average particle size of 5 microns using an airflow mill. The airflow speed is set at 2 meters per second and the crushing time is 30 minutes.

[0011] Nano-scale pulverization: A ball mill was further used with a ball milling time of 2 h and a ball-to-material ratio of 5:1 to reduce the particles to the nano-scale (average particle size of about 100 nm).

[0012] 3. Wet grinding and application of special additives Wet grinding: During wet grinding, the solid content was adjusted to 45% and the grinding time was 4 hours to ensure sufficient grinding.

[0013] Additives: Add special surfactants and dispersants. The surfactant is sodium dodecyl sulfate (SDS), and the addition ratio is 0.5% of the weight of kaolin; the dispersant is sodium polyacrylate (PAA), and the addition ratio is 0.3% of the weight of kaolin.

[0014] 4. Optimize calcination process Segmented temperature control: The calcination process is divided into three stages. The temperature of the first stage is set at 400°C for 2 hours to remove mechanical water and crystallization water; the temperature of the second stage is increased to 800°C for 1 hour to form the required crystal structure; the temperature of the third stage is increased to 1000°C and maintained for 30 minutes to improve the thermal stability of the product.

[0015] Temperature monitoring: Use high-precision temperature sensors to monitor the calcination process to ensure the accuracy of temperature control.

[0016] 5. Real-time monitoring and quality control system Online monitoring: Install online particle size analyzers and moisture sensors to monitor key parameters during grinding and calcination in real time.

[0017] Quality Control: An automatic feedback system is established. When parameter deviations are detected, the system automatically adjusts the grinding and calcining conditions to ensure the consistency and stability of product quality. The kaolin modification method of the present invention has the following technical effects: 1. Improve solubility and reduce viscosity: The present invention significantly improves the solubility of calcined kaolin by optimizing the crushing, grinding and calcining processes, especially the nano-scale crushing technology, which makes the particle size smaller and the surface area larger, thereby accelerating the dissolution process in water.

[0018] By adding special surfactants and dispersants, the wettability and dispersibility of kaolin are improved and its viscosity in water is reduced. This can significantly improve production efficiency and the quality of the final product for industries such as coatings and papermaking.

[0019] 2. Environmental friendliness and improved energy efficiency: By optimizing the calcination process, such as staged temperature control technology, energy consumption is reduced and the emission of harmful gases is reduced.

[0020] Special additives used in the wet grinding process reduce the demand for water resources and reduce the burden of wastewater treatment, thereby improving overall environmental friendliness.

[0021] 3.Consistency and stability of product quality: The implementation of online monitoring and automatic quality control systems ensures the stability of key parameters during the production process, thereby improving the consistency and stability of product quality.

[0022] By precisely controlling the calcination temperature and time, the physical and chemical properties of kaolin, such as crystallinity and pore structure, are optimized, further improving product performance.

[0023] 4. Expansion of application scope: Since the improved kaolin has better solubility and lower viscosity, its application range will be further expanded beyond traditional fields (such as ceramics, coatings, and papermaking). For example, it can be used in new composite materials, fine chemicals, Find the application in the product.

[0024] This optimized kaolin also provides the possibility for the research and development of new environmentally friendly products, such as environmentally friendly coatings, biodegradable plastic fillers, etc.

[0025] 5. User cost: Due to the improved solubility and reduced viscosity of kaolin, users can reduce the processing time and energy consumption required when using this improved kaolin, thereby reducing the cost of use.

[0026] Due to the improvement of product quality, the product rework rate and scrap rate are reduced, further reducing the overall cost of users. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined. Implementation method 1: Optimized calcined kaolin production process

[0029] 1. Preparation and pretreatment: Screen out kaolin blocks of suitable size from coal gangue to ensure the quality of raw materials.

[0030] The kaolin is first soaked in distilled water at pH 7 for 24 hours at 25°C. This step is intended to soften the minerals and remove soluble impurities.

[0031] A high gradient magnetic separator is used for magnetic separation, and the magnetic field strength is set to 2000 Gauss to ensure that all iron impurities are removed.

[0032] Use a low-speed rotary crusher to crush the gangue kaolin into 3-4cm size to reduce dust generation, and separate it through a vibrating screen to ensure uniform particle size.

[0033] 2. Grinding and nano-scale crushing: The crushed kaolin was ground into an average particle size of 5 microns by dry grinding using an air jet mill. The air velocity was controlled at 2.5 meters per second and the grinding time was 45 minutes.

[0034] A ball mill was further used for nano-scale crushing. The ball milling time was set to 3 hours and the ball-to-material ratio was 4:1 to obtain a finer powder with an average particle size of 100 nanometers.

[0035] 3. Grinding and additive application: During the wet grinding process, the solid content of the powder was adjusted to 45% and the grinding time was set to 4 hours to ensure that the particles were fully ground.

[0036] During the grinding process, 0.5% sodium dodecyl sulfate (SDS) and 0.3% sodium polyacrylate (PAA) were added as surfactants and dispersants to improve the wettability and dispersibility of kaolin.

[0037] 4. Process optimization: The calcination process is divided into three stages for temperature control. The temperature of the first stage is set at 400°C for 2 hours to remove mechanical water and crystallization water. The temperature of the second stage is raised to 800°C for 1 hour to form the desired crystal structure. The temperature of the third stage is raised to 1000°C for 30 minutes to improve the thermal stability of the product.

[0038] High-precision temperature sensors are used throughout the calcination process to strictly control the temperature and ensure product quality.

[0039] 5. Inspection and packaging: After calcination, the kaolin undergoes strict quality inspections, including particle size analysis, viscosity testing and solubility assessment, to ensure that it meets the predetermined standards.

[0040] Qualified products are packaged in moisture-proof packaging to maintain their quality and ensure that they are not contaminated during transportation.

Claims

1. A method for producing calcined kaolin with good solubility, comprising the following steps: (a) Pre-treatment of gangue kaolin, including water washing and magnetic separation; (b) crushing the pretreated kaolin into pieces of 3-4 cm in size; (c) grinding the crushed kaolin to an average particle size of 5 μm using a jet mill dry grinding technique; (d) nano-scale pulverization by ball mill; (e) adding surfactants and dispersants during wet grinding; (f) staged temperature-controlled calcination treatment; (g) Carry out product quality inspection and packaging.

2. The production method according to claim 1, wherein the pretreatment step (a) comprises soaking the kaolin in water at pH 7 for 24 hours and performing magnetic separation using a high gradient magnetic separator.

3. The production method according to claim 1, wherein the air flow velocity of the dry grinding step (c) is controlled to be 2.5 meters per second and the grinding time is 45 minutes.

4. The production method according to claim 1, wherein the nano-scale pulverization step (d) uses a ball milling time of 3 hours and a ball-to-material ratio of 4:

1.

5. The production method according to claim 1, wherein the surfactant added in the wet grinding step (e) is sodium dodecyl sulfate (SDS) and the dispersant is sodium polyacrylate (PAA).

6. The production method according to claim 1, wherein the staged temperature-controlled calcination step (f) comprises temperature control at 400°C for 2 hours, 800°C for 1 hour, and 1000°C for 30 minutes.