Production process for improving yield of granular magnesium oxide and production system of granular magnesium oxide

Abstract

The invention provides a production process for improving the yield of granular magnesium oxide and a production system of granular magnesium oxide, and belongs to the technical field of chemical production, and the production process comprises the following process steps: pre-mixing dressing water and a main raw material magnesium oxide to obtain a mixture; the obtained mixture is fed into a dry type granulator to be subjected to dry type prepressing, the volume of the prepressed main raw materials is controlled to be 1.4-1.6 ml / g, and the formed mixture comprises 40-65% of powder and 35-60% of particles; sucking the pre-pressed mixture into a fluidized bed under negative pressure, and carrying out boiling granulation; and screening to obtain granular magnesium oxide. The raw materials are mixed in advance and then pressed, the one-time yield is increased, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of fluidized bed granulation technology, specifically relating to a production process and system for improving the yield of granulated magnesium oxide. Background Technology

[0002] Existing fluidized bed granulation processes mostly employ a "magnesium oxide raw material + auxiliary materials" direct fluidized bed granulation production mode. Specifically, a single type of magnesium oxide is used as the raw material, and after adding auxiliary materials, it is directly fed into a fluidized bed equipment for fluidized bed granulation. Subsequently, the mixture is simply mixed in a buffer tank and sieved to obtain the final wet granulated product. This process for producing granulated magnesium oxide has the following drawbacks: (1) Low yield of finished product: The proportion of finished granular magnesium oxide and powdered magnesium oxide is unbalanced, resulting in serious waste of raw materials and failing to meet the batch demand for granular magnesium oxide in high-end fields (such as pharmaceuticals and electronics).

[0003] (2) High cost: Screened material cannot be reused directly and needs to be reworked separately. Otherwise, it can only be used for low-end products. The rework process requires equipment and manpower. Low-end products have low profits, which lowers the overall gross profit margin of the enterprise.

[0004] (3) Low production efficiency: The first-pass yield is low and the defect rate is high, requiring rework, which reduces production efficiency, leads to long production cycles, extended order delivery cycles, and affects the stability of customer cooperation.

[0005] (4) Poor quality stability: Direct boiling granulation is prone to particle agglomeration / breakage, large particle size deviation, large product quality fluctuation, and cannot meet the stringent requirements of high-end customers for particle uniformity. Summary of the Invention

[0006] This invention provides a production process and system for improving the yield of granular magnesium oxide, aiming to increase the yield of finished products, improve production efficiency, and reduce production costs by premixing raw materials before pressing.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a production process for improving the yield of granular magnesium oxide, comprising the following process steps: The dressing solution is premixed with the main raw material, magnesium oxide, to obtain a mixture; The resulting mixture is fed into a dry granulator for dry pre-compression. The volume of the main raw material after pre-compression is controlled at 1.4-1.6 ml / g. The resulting mixture contains 40%-65% powder and 35%-60% granules. The pre-compressed mixture is drawn into the fluidized bed under negative pressure for boiling granulation; Magnesium oxide particles were obtained by sieving.

[0008] In conjunction with the first aspect, in one feasible manner, the dry pre-compression process controls the operating parameters of the dry granulator as follows: Pre-compression pressure 18-25MPa, feeding speed 30-40r / min, pressure roller speed 15-22r / min, pelletizing speed 90-120r / min.

[0009] In conjunction with the first aspect, in one feasible manner, the main raw material comprises 90% magnesium oxide G-XB-QG-3W and 10% magnesium oxide W-HF-QG-2W; The magnesium oxide G-XB-QG-3W has a particle size of 80-100 mesh and a purity of ≥98.5%; the magnesium oxide W-HF-QG-2W has a particle size of 100-120 mesh and a purity of ≥97.5%. The dressing solution accounts for 40% of the mass of the main raw material.

[0010] In conjunction with the first aspect, in one feasible manner, when the dressing solution is premixed with the main raw material magnesium oxide, the feeding is carried out in the following order: First add the magnesium oxide G-XB-QG-3W, then add the magnesium oxide W-HF-QG-2W, and finally add the dressing solution.

[0011] In conjunction with the first aspect, in one feasible manner, the pre-mixing parameters of the dressing water and the main raw material magnesium oxide are as follows: The feeding speed is 18-20 kg / min, the mixing time is 20-25 min, and the discharge speed is 35-40 r / min.

[0012] In conjunction with the first aspect, in one feasible manner, the operating parameters of the fluidized bed granulation are: Water spray pressure: 0.3-0.45 MPa; drying air volume: 3000-4000 m³ / h; drying temperature: 80-90℃; water addition time: 30-40 min; heating time: 60-70 min.

[0013] In conjunction with the first aspect, in one feasible manner, the working sequence of the fluidized bed granulation is as follows: First, air is introduced at a drying air volume of 3000-4000 m³ / h, then water is sprayed at a pressure of 0.3-0.45 MPa, and finally the temperature is raised to 80-90℃ for drying.

[0014] In conjunction with the first aspect, in one feasible manner, the fluidized bed granulation process involves the pre-compressed mixture being fed into the fluidized bed at a feed rate of 18-20 kg / min. After drying, the mixture is cooled to below 40-50℃ before being sieved.

[0015] In conjunction with the first aspect, in one feasible manner, the screening employs a double-layer screen, comprising: After drying and cooling, the mixture is sieved through a 25-mesh upper sieve and a 100-mesh lower sieve in sequence, with a sieving time of 10-15 minutes.

[0016] Secondly, embodiments of the present invention also provide a granular magnesium oxide production system for the aforementioned production process for improving the yield of granular magnesium oxide, comprising, in the following process sequence: a ribbon mixer, a dry granulator, a fluidized bed, and a vibrating screen; wherein the vibrating screen comprises upper and lower screens.

[0017] The production process for improving the yield of granular magnesium oxide provided by this invention has the following advantages compared with the prior art: First, addressing the problem of low yield and raw material waste caused by directly mixing a single type of magnesium oxide raw material with dressings and then directly fluidizing and granulating it in existing processes, this application adopts a process of dry pre-compressing after mixing the main raw material magnesium oxide with dressing water. The volume of the mixture is controlled at 1.4-1.6 ml / g, forming a mixture of 40-65% powder and 35-60% granules. When this mixture after dry pre-compressing enters the fluidized bed for fluidized bed granulation, the granule formation is more stable, which can significantly improve the granule conversion efficiency. Finally, the proportion of magnesium oxide in the finished product obtained after sieving is significantly increased, and the proportion of powder is significantly reduced, effectively improving the imbalance between the proportion of finished product and powder, reducing raw material waste, and significantly improving the yield of finished product in one step. This can meet the batch demand for granular magnesium oxide in high-end fields such as pharmaceuticals and electronics.

[0018] Secondly, addressing the issue of high costs, this invention optimizes pre-mixing and dry pre-compression processes, reducing the amount of undersize material generated at the source. On one hand, the pre-mixing and pre-compression processes improve the particle formation stability of subsequent fluidized bed granulation, significantly increasing the proportion of qualified particles after the first screening and substantially reducing the total amount of undersize material. On the other hand, the mixture formed after pre-treatment possesses stable physical properties. Even if a small amount of undersize material is generated, its compositional uniformity and basic particle morphology are superior to undersize material from existing processes, allowing it to be directly reused in the "pre-mixing" process without the need for a separate rework process. This optimization not only saves the equipment and labor costs required for separate rework but also avoids the profit loss from the downgraded use of undersize material, effectively improving the overall gross profit margin of the enterprise and reducing production costs.

[0019] Third, to address the problem of low production efficiency, this invention employs a pre-treatment design of pre-mixing + dry pre-compression. After the pre-compressed mixture enters the fluidized bed, the particles grow more uniformly and stably during the boiling granulation process, reducing defective products caused by particle agglomeration and breakage. At the same time, the screened material can be directly reused without additional rework, further shortening the production process.

[0020] The improved first-pass yield and simplified rework process significantly reduce the production cycle, increase equipment utilization and production efficiency, accelerate order delivery, and ensure the stability of customer cooperation.

[0021] Fourth, addressing the issue of poor quality stability, the dry pre-compression method of this invention provides a stable basic morphology for subsequent particle growth by precisely controlling the volume of the mixture (1.4-1.6 ml / g), reducing the risk of particle breakage during the fluidized bed granulation process, making the particle formation process more controllable, the particle size distribution more concentrated, effectively reducing particle size deviation, improving the uniformity of product particles, and reducing quality fluctuations in the subsequent granulation process. This can meet the stringent requirements of high-end customers for the quality stability and uniformity of granulated magnesium oxide.

[0022] Therefore, this invention achieves precise control of raw material volume (1.4-1.6 ml / g) by combining dry pre-compression with fluidized bed (wet) granulation. The pre-compressed mixture contains 40%-65% powder and 35%-60% granules, resulting in a finished granule yield of 95%-98%. This improves the first-pass yield and quality stability of granulated magnesium oxide, increases production efficiency, reduces production costs, and meets the needs of high-end customers for granule quality and batch size.

[0023] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0024] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0025] Figure 1 This is a process flow diagram for improving the yield of granular magnesium oxide provided in Embodiment 1 of the present invention; Figure 2 This is a process flow diagram of premixing and precompression provided in Embodiment 2 of the present invention; Figure 3 This is a process flow diagram of fluidized bed granulation and sieving provided in Embodiment 2 of the present invention. Detailed Implementation

[0026] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0028] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0029] Example 1 Please see Figure 1 The production process for improving the yield of granular magnesium oxide provided by the present invention will now be described. The production process for improving the yield of granular magnesium oxide includes the following steps: S100, the dressing solution is premixed with the main raw material magnesium oxide to obtain a mixture; S200, the obtained mixture is fed into a dry granulator for dry pre-compression. The volume of the main raw material after pre-compression is controlled at 1.4-1.6 ml / g. The resulting mixture includes 40% powder and 60% granules. S300: The pre-compressed mixture is drawn into the fluidized bed under negative pressure for boiling granulation; S400, sieve to obtain granular magnesium oxide.

[0030] Example 2 S100, the dressing solution is premixed with the main raw material magnesium oxide. Please refer to [link / reference]. Figure 2 and Figure 3 : First, add 90% of magnesium oxide G-XB-QG-3W into the ribbon mixer, then add 10% of magnesium oxide W-HF-QG-2W, and then add 40% of purified water. Mix at a rate of 180 kg / batch for 25 minutes to ensure the uniformity of the mixture (deviation ≤0.5%).

[0031] The feeding speed is 20 kg / min. 90% of the magnesium oxide G-XB-QG-3W has a particle size of 80 mesh to ensure particle strength and improve the main performance of the product. 10% of the magnesium oxide W-HF-QG-2W has a particle size of 120 mesh to increase the flowability of the raw materials and avoid agglomeration during pre-compression.

[0032] The dressing solution is purified water, used as a binder in boiling granulation.

[0033] The mixing time should not be too short or too long. If the mixing time is too short, the materials will not be mixed evenly. If the mixing time is too long, the materials will turn gray and affect the final quality of the product.

[0034] The raw materials provided in Example 2 of this invention are shown in Table 1 below:

[0035] S200, dry preloading: The premixed mixture is fed into the dry pellet mill at a constant speed of 40 r / min. Pre-compression is performed according to the working parameters of 18MPa pre-compression, 20r / min roller speed, and 120r / min granulation speed until the volume of the main raw material is 1.4-1.6ml / g. The resulting mixture contains 65% powder and 35% granules.

[0036] S300, fluidized bed granulation: The pre-compressed mixture is fed into the FBD-800 fluidized bed at a feeding rate of 20 kg / min; First, air is introduced at a drying air volume of 3200 m³ / h, then water is sprayed at a pressure of 0.45 MPa for 10 minutes. The drying temperature is set at 90℃ and the drying time is 70 minutes. Then, the air intake, water spraying and heating are turned off. This sequence can prevent particle agglomeration. After cooling for 20 minutes, the pre-compressed mixture is allowed to reach a temperature below 50°C before sieving.

[0037] This step is a key factor in ensuring pellet formation.

[0038] Among them, the specific magnesium oxide type ratio (90%+10%) is matched with the granulation pressure to ensure the stability of raw materials for fluidized bed granulation.

[0039] S400, screening: After drying and cooling, the mixture is sieved through a 25-mesh upper sieve and a 100-mesh lower sieve for 10 minutes to obtain uniform rhomboid magnesium oxide particles. The sieve diameter is 1.2m.

[0040] We also use a magnetic detector (magnetic force ≥12000 Gauss) to detect foreign objects, remove impurities and large particles, and perform secondary sieving to ensure the uniformity of particle rhombus shape. Magnetic foreign objects ≥0.1mm are detected to ensure product quality.

[0041] In this step, by controlling the screening parameters and the mesh size, uniform rhomboid magnesium oxide particles are obtained, improving production efficiency by about 20-30%.

[0042] Large particles on the sieve undergo a secondary mixing and granulation process to obtain rhomboid-shaped magnesium oxide particles, thereby improving particle uniformity and yield.

[0043] The process steps and process parameter designs provided in Embodiment 2 of this invention are summarized in Table 2 below:

[0044] The process flow, process parameters, and equipment combination of dry pre-compression + fluidized bed granulation + two-stage screening provided in Embodiment 2 of this invention are compared with existing fluidized bed granulation methods as follows: In response to the existing low yield rate (65%-70%), the process provided by the embodiments of the present invention can increase the yield rate to 95%-98% and reduce the defect rate by 30%, thus solving the problems of low yield rate and production cost and efficiency.

[0045] In response to the low production efficiency (65%-70%) of existing production processes, the yield of finished products in a single pass can be increased to 95%-98%, and the production efficiency can be increased by 30% using the process provided in the embodiments of the present invention.

[0046] To address the issue of high existing production costs, production costs can be reduced by 25-30% by decreasing screened material (down to 2-5%).

[0047] To address the issue of poor product quality, the particle size deviation is controlled to ≤5%, and a magnetic detector is used in the screening process to simultaneously detect foreign objects, thus meeting the needs of high-end fields.

[0048] In the magnesium oxide G-XB-QG-3W, G represents high purity, XB represents the manufacturer, QG represents light high-purity magnesium oxide, and 3W represents a magnesium oxide content of 98.5%. Characteristics: high purity, sticky material, prone to agglomeration.

[0049] In the magnesium oxide W-HF-QG-2W series, W represents externally sourced magnesium oxide, HF represents the manufacturer, QG represents lightweight high-purity magnesium oxide, and 2W indicates a magnesium oxide content of 97.5%. Characteristics: High-purity magnesium oxide, sticky material.

[0050] Example 3 The difference from Example 2 is in the adjustment of parameters: the dry pre-compression pressure is adjusted to 20 MPa, the volume of the main raw material after pre-compression is 1.4-1.6 ml / g, the powder accounts for 40%, and the granules account for 60%.

[0051] Example 4 The difference from Example 2 is in the adjustment of parameters: the pre-compression pressure is adjusted to 22 MPa, the volume of the main raw material after pre-compression is 1.4-1.6 ml / g, the powder ratio is 55%, and the particle ratio is 45%.

[0052] Through comparative experiments of Examples 2, 3, and 4, the following conclusions were drawn: In Example 2, when the pre-compression pressure was 18 MPa, the volume of the main raw material was 1.4-1.6 ml / g, with a powder ratio of 65% and a particle ratio of 35%, which is the core condition for product stability. Changing the process parameters resulted in a powder ratio and particle ratio that were within a reasonable control range.

[0053] Comparative example: The existing fluidized bed granulation process uses magnesium oxide as raw material and auxiliary materials for direct fluidized bed granulation. The specific scheme is as follows: using a single type of magnesium oxide as raw material, after adding auxiliary materials, it is directly fed into a fluidized bed equipment, and fluidized bed granulation is carried out using parameters of "spray water pressure 0.15-0.5MPa, air volume 4500-5000m³ / h, drying temperature 99℃, and reaction time 40-60 minutes". Subsequently, it is simply mixed in a buffer tank and screened once by a vibrating screen (only one layer of screen) to finally obtain the wet granulated product. The yield of finished product in one pass is only 65-70%, the ratio of finished particles to powder is unbalanced (particles 60-70%, powder 30-40%), the proportion of undersize material is 30-40%, the defect rate is 30-40%, the particle size deviation is more than ±15%, and the quality stability is poor.

[0054] The defects of using the above-mentioned existing technology to prepare granular magnesium oxide are shown in Table 3 below:

[0055] The comparison data between Example 2 and the comparative example are shown in Table 4 below:

[0056] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0057] Based on the same inventive concept, this application also provides a production system for granular magnesium oxide, which, in the following process sequence, includes: a ribbon mixer, a dry granulator, a fluidized bed, and a vibrating screen; wherein the vibrating screen includes upper and lower screens. The fluidized bed is an FBD-800 type fluidized bed.

[0058] The production system provided by this invention can improve the yield of finished products, reduce the defect rate, increase production efficiency, and reduce production costs by pre-mixing raw materials evenly, performing dry pre-compression, boiling granulation in a fluidized bed, and finally passing through two layers of sieving.

[0059] The following is a description of the aforementioned equipment: A ribbon mixer is an industrial device used for mixing viscous powders or liquids. It achieves efficient and uniform mixing by creating a convective vortex through the counter-rotating inner and outer spiral ribbons. The core working principle and structural design of the mixing mechanism are as follows: The equipment consists of a U-shaped container, double / triple-layer spiral blades, and transmission components. The outer spiral gathers the material towards the center, while the inner spiral conveys it to both sides, forming a convective vortex.

[0060] Dry granulation machines are powder forming equipment that uses a dry roller pressing process. They are mainly used to process powdery materials with a moisture content of ≤5% and are widely used in chemical, pharmaceutical, and food industries. The core process involves compressing the material into flakes using rollers, followed by crushing, granulation, and screening to convert them into uniform particles. No binders or drying treatment is required, thus meeting GMP and other production standards.

[0061] This equipment consists of components such as a pre-feeder, a pellet mill, and a crusher / granulator. It employs hydraulically driven double-roller counter-current extrusion molding technology, with perforations on the roll surface to improve compression efficiency. Equipped with a variable frequency speed-regulating motor and a PLC automated control system, it can adjust pressure, feeding speed, and particle strength, featuring continuous production, low energy consumption, and a compact structure. The equipment is primarily constructed of stainless steel and alloys to enhance wear and corrosion resistance. Some models are equipped with water cooling, screening and dust removal functions, and intelligent operation modes.

[0062] Fluidized bed dryers, also known as boiling bed dryers, are steelmaking equipment that uses fluid agitation to dry materials. They are mainly used in the dehydration of powdery and paste-like materials in chemical, metallurgical and other fields.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A production process for improving the yield of granular magnesium oxide, characterized in that, The process includes the following steps: The dressing solution was premixed with the main raw material, magnesium oxide, to obtain a mixture; The resulting mixture is fed into a dry granulator for dry pre-compression. The volume of the main raw material after pre-compression is controlled at 1.4-1.6 ml / g. The resulting mixture contains 40%-65% powder and 35%-60% granules. The pre-compressed mixture is drawn into the fluidized bed under negative pressure for boiling granulation; Magnesium oxide particles were obtained by sieving.

2. The production process for improving the yield of granular magnesium oxide as described in claim 1, characterized in that, The dry pre-compression process controls the operating parameters of the dry granulator as follows: Pre-compression pressure 18-25MPa, feeding speed 30-40r / min, pressure roller speed 15-22r / min, pelletizing speed 90-120r / min.

3. The production process for improving the yield of granular magnesium oxide as described in claim 1, characterized in that, The main raw materials include 90% magnesium oxide G-XB-QG-3W and 10% magnesium oxide W-HF-QG-2W; The magnesium oxide G-XB-QG-3W has a particle size of 80-100 mesh and a purity of ≥98.5%; the magnesium oxide W-HF-QG-2W has a particle size of 100-120 mesh and a purity of ≥97.5%. The particle size of magnesium oxide G-XB-QG-3W includes a lower limit of 80 mesh and an upper limit of 100 mesh, while the particle size of magnesium oxide W-HF-QG-2W excludes the lower limit of 100 mesh and includes the upper limit of 120 mesh. The dressing solution accounts for 40% of the mass of the main raw material.

4. The production process for improving the yield of granular magnesium oxide as described in claim 3, characterized in that, When the dressing solution is premixed with the main raw material magnesium oxide, the feeding shall be carried out in the following order: First, add the magnesium oxide G-XB-QG-3W, then add the magnesium oxide W-HF-QG-2W, and finally add the dressing solution.

5. The production process for improving the yield of granular magnesium oxide as described in claim 1, characterized in that, The pre-mixing parameters for the dressing solution and the main raw material magnesium oxide are as follows: The feeding speed is 18-20 kg / min, the mixing time is 20-25 min, and the discharge speed is 35-40 r / min.

6. The production process for improving the yield of granular magnesium oxide as described in claim 1, characterized in that, The operating parameters for fluidized bed granulation are as follows: Water spray pressure: 0.3-0.45 MPa; drying air volume: 3000-4000 m³ / h; drying temperature: 80-90℃; water addition time: 35-40 min; heating time: 60-70 min.

7. The production process for improving the yield of granular magnesium oxide as described in claim 6, characterized in that, The working sequence of the fluidized bed granulation is as follows: First, air is introduced at a drying air volume of 3000-4000 m³ / h, then water is sprayed at a pressure of 0.3-0.45 MPa, and finally the temperature is raised to 80-90℃ for drying.

8. The production process for improving the yield of granular magnesium oxide as described in claim 6, characterized in that, In the fluidized bed granulation process, the pre-compressed mixture is fed into the fluidized bed at a rate of 18-20 kg / min. After drying, the mixture is cooled to below 40-50℃ before being sieved.

9. The production process for improving the yield of granular magnesium oxide as described in claim 1, characterized in that, The screening process employs a double-layer screen, comprising: After drying and cooling, the mixture is sieved through a 25-mesh upper sieve and a 100-mesh lower sieve in sequence, with a sieving time of 10-15 minutes.

10. A production system for granular magnesium oxide, used in the production process for improving the yield of granular magnesium oxide as described in any one of claims 1-9, characterized in that, The process sequence includes, in order: ribbon mixer, dry granulator, fluidized bed and vibrating screen; The vibrating screen includes upper and lower screens.

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