CN109912997B - Production method of wet-process ultrafine needle-like wollastonite - Google Patents
Production method of wet-process ultrafine needle-like wollastonite Download PDFInfo
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Abstract
A wet process for preparing superfine acicular wollastonite includes such steps as superfine processing of wollastonite by wet grinding, adding maleic anhydride-butyl methacrylate-styrene as disperser, and adding silane as coupling agent to the middle segment of grinding machine for surface treatment. Compared with the existing product, the product prepared by the invention has the advantages of finer granularity, narrower granularity distribution, higher whiteness and larger specific surface area; compared with the prior art, the grinding process adopted by the invention for preparing the superfine needle-like wollastonite has the advantages of higher grinding efficiency, less pollution to products, low energy consumption and higher yield, and is more suitable for large-scale production. The fineness of the product is greatly improved, so that the covering power and the reinforcing performance of the product are improved.
Description
Technical Field
The invention relates to a production method of wet-process ultrafine needle-shaped wollastonite, belonging to the technical field of fine chemical engineering.
Background
Wollastonite is a functional mineral material with a high refractive index and a long fiber structure, has the advantages of good insulativity and dielectric property, good thermal stability and dimensional stability, excellent mechanical reinforcing effect and the like, and is widely applied to the fields of coatings, plastics, rubber, papermaking, ceramics and the like.
After the wollastonite is subjected to superfine deep processing, the whiteness is greatly improved, and the dispersibility, the suspension property and the leveling property are greatly improved. Especially, when the particle size of the wollastonite reaches 3um or below, the covering performance of the wollastonite can be improved, the wollastonite can be used for replacing titanium dioxide in paint, rubber and plastics to play a role of functional pigment, can be widely applied to papermaking coatings and adhesives, and can replace other expensive raw materials.
At present, the equipment for superfine processing of wollastonite is mainly an air flow mill, and although the process can well maintain the fiber structure of the product, the superfine processing of the wollastonite is difficult to realize, the processing cost is high, and the equipment is seriously abraded.
The production process of the superfine needle-like wollastonite mainly comprises the following steps: the method comprises the following steps of manually screening raw ores, feeding the raw ores into a jaw crusher through a vibrating feeder to perform primary crushing, conveying the raw ores to a storage bin through a hoist, performing secondary crushing on the raw ores into an impact crusher through a belt conveyor, grinding the two-stage crushed ores into a Raymond mill to 40-60 mu m, grinding the two-stage crushed ores into an airflow mill through a spiral feeding device, continuously crushing the materials under impact shear of high-speed airflow, feeding the ground materials into a classifier along with the airflow to classify, collecting particles with the particle size meeting the requirement through the classifier, and returning the particles without the particle size meeting the requirement into the mill to continuously grind. The prior art has the following defects: 1) the D50 of the superfine wollastonite produced by the process is more than or equal to 5 microns, so that the superfine wollastonite cannot be thinner, and the product has poor covering performance; 2) the wollastonite has higher hardness and large processing difficulty, and is ground by adopting an air flow mill, so that the grinding efficiency is not high, the energy consumption is large, the yield is low and the production cost is high; 3) the particle size of the product is mainly controlled by a classifier, and because wollastonite is of a fiber structure, the particles are easy to agglomerate together in the air due to static electricity to form a large amount of pseudo-aggregates, so that the classification precision is not high, and the particle size distribution of the product is wide.
The publication No. CN105855016A discloses a process and a device for producing superfine needle-like wollastonite powder, in which wollastonite raw ore is crushed to an average particle size of less than 1cm, the crushed wollastonite raw ore is crushed by a crusher to obtain needle-like powder with a sedimentation value of 60-90, the needle-like powder is subjected to vibration screening to obtain needle-like powder with a high length-diameter ratio, and then the needle-like powder is subjected to jet milling by an air jet mill to obtain the needle-like wollastonite powder with the fineness of 600 plus 3000 meshes and the length-diameter ratio of more than 10: 1.
Disclosure of Invention
The invention aims to overcome a series of defects of low grinding efficiency, insufficient product fineness, poor covering performance, large grinding abrasion, high production cost, low yield and the like of the current airflow grinding processing technology of ultrafine needle-shaped wollastonite, and discloses a production method of wet ultrafine needle-shaped wollastonite.
The technical scheme of the invention is as follows: a wet process for preparing superfine acicular wollastonite includes such steps as superfine processing of wollastonite by wet grinding, adding maleic anhydride-butyl methacrylate-styrene as disperser, and adding silane as coupling agent to the middle segment of grinding machine for surface treatment.
A preparation method of wet-process superfine needle-like wollastonite comprises the following steps:
(1) selecting wollastonite concentrate with calcium silicate content of more than 95%, coarsely crushing by a jaw crusher, then grinding by a vertical ring roller mill, and controlling by a grader to obtain 400-mesh wollastonite dry powder;
(2) preparing 400-mesh wollastonite dry powder and water into slurry with the solid content of 55-65% in a high-speed dispersion barrel, and adding a certain amount of dispersant in the process of preparing the slurry;
(3) continuously feeding the prepared wollastonite slurry into a vertical stirring mill through a diaphragm pump for grinding, and adding a coupling agent into the slurry from a drug adding port in the middle of the mill; controlling the grinding time of the material in the grinding machine by controlling the feeding speed of the slurry, and further controlling the final granularity of the slurry to obtain finished slurry;
(4) and feeding the finished slurry into a pulsating high-gradient magnetic separator for iron removal, and drying and scattering to obtain the finished product of the superfine acicular wollastonite.
The grinding medium of the vertical stirring mill adopts high-strength wear-resistant ceramic balls, the volume filling rate is 63% -68%, the size of the medium is 1.2-1.4mm, the size distribution is narrow, and the fineness and the narrow particle size distribution of the ground slurry are ensured.
The dispersant is maleic anhydride-butyl methacrylate-styrene, and the addition amount of the dispersant is 0.4-0.6% of the dry powder amount of wollastonite.
The coupling agent is prehydrolyzed vinyltrimethoxysilane, and the addition amount of the coupling agent is 0.3-0.5 percent of the dry powder amount of the wollastonite.
The drying and scattering treatment adopts a rotary flash evaporation dryer with a powerful scattering function.
The method adds maleic anhydride-butyl methacrylate-styrene as a grinding dispersant in the wet grinding process, and simultaneously adds a coupling agent, namely the hydrolyzed vinyl trimethoxy silane, into a grinding machine, and the coupling agent organically coats wollastonite particles during grinding, so that the grinding efficiency is further improved, and the dispersibility of the wollastonite particles is improved. The rotary flash evaporation dryer with a powerful scattering function is adopted to dry the slurry, and the mechanical force is applied during drying, so that the good particle size reducibility of the dried wollastonite dry powder is effectively ensured.
Compared with the existing products, the product prepared by the invention has the advantages of finer granularity, narrower granularity distribution, higher whiteness and larger specific surface area; compared with the prior art, the grinding process adopted by the invention for preparing the superfine needle-like wollastonite has the advantages of higher grinding efficiency, less pollution to products, low energy consumption and higher yield, and is more suitable for large-scale production. The fineness of the product is greatly improved, so that the covering power and the reinforcing performance of the product are improved.
Drawings
FIG. 1 is a process flow diagram of the method of the present invention;
FIG. 2 is the ultra fine needle wollastonite of example 1 that was wet ground;
FIG. 3 shows the ultra fine needle-like wollastonite obtained by wet grinding in example 2.
Detailed Description
A specific embodiment of the present invention is shown in fig. 1.
Example 1
In the embodiment, the vertical stirring mill is adopted for wet superfine grinding, the vertical stirring mill adopts an alumina ceramic lining, the filled grinding medium is 92 high-purity alumina ceramic balls, and the true density is 3.62g/cm3The size is 1.2-1.4mm, and the medium filling rate is 65%.
Selecting wollastonite concentrate with calcium silicate content of more than or equal to 95%, coarsely crushing by a jaw crusher, then grinding by a vertical ring roller mill, and controlling by a grader to obtain 400-mesh wollastonite dry powder.
Preparing the wollastonite dry powder with 400 meshes and water into slurry with the solid content of 55% in a high-speed dispersion barrel, and simultaneously adding maleic anhydride-butyl methacrylate-styrene dispersant accounting for 0.4% of the wollastonite dry powder in the process of preparing the slurry to obtain crude slurry A.
And continuously conveying the slurry A into a vertical stirring mill through a diaphragm pump, wherein the diaphragm pump adopts frequency conversion regulation and control to control the feeding speed, the grinding time of the slurry A in the mill is controlled to be 46min, meanwhile, a certain amount of vinyl trimethoxy silane is added into a chemical adding port in the middle of the mill through a metering pump in the grinding process, and the adding amount of the coupling agent is 0.3 percent of the amount of wollastonite dry powder, so that the slurry B is obtained.
D50 for slurry B as measured by a sedimentation sizer: 1.5 μm; and feeding the slurry B into a pulsating high-gradient magnetic separator for iron removal to obtain finished slurry C.
The content of the magnetic iron was measured to be 0.08%; and (3) continuously feeding the slurry C into a high-speed rotary flash evaporation dryer through a screw pump for scattering and drying, controlling the drying temperature to be 350 ℃, performing dust removal and packaging to obtain a final finished product, and detecting the granularity D50 of the finished product through a laser granularity analyzer: 1.7 μm. FIG. 1 is a picture of the ultra-fine needle-like wollastonite obtained by wet grinding in this example.
Example 2
In the embodiment, the vertical stirring mill is adopted for wet superfine grinding, the vertical stirring mill adopts an alumina ceramic lining, the filled grinding medium is 92 high-purity alumina ceramic balls, and the true density is 3.62g/cm3The size is 1.2-1.4mm, and the medium filling rate is 67%.
Selecting wollastonite concentrate with calcium silicate content of more than or equal to 95%, coarsely crushing by a jaw crusher, then grinding by a vertical ring roller mill, and controlling by a grader to obtain 400-mesh wollastonite dry powder.
Preparing 400-mesh wollastonite dry powder and water into slurry with solid content of 60% in a high-speed dispersion barrel, and simultaneously adding maleic anhydride-butyl methacrylate-styrene dispersing agent accounting for 0.5% of the wollastonite dry powder in the process of preparing the slurry to obtain crude slurry A.
And continuously conveying the slurry A into a vertical stirring mill through a diaphragm pump, wherein the diaphragm pump adopts frequency conversion regulation and control to control the feeding speed, the grinding time of the slurry A in the mill is controlled to be 50min, meanwhile, a certain amount of vinyl trimethoxy silane is added into a chemical adding port in the middle of the mill through a metering pump in the grinding process, and the adding amount of the coupling agent is 0.3 percent of the amount of wollastonite dry powder, so that the slurry B is obtained.
D50 for slurry B as measured by a sedimentation sizer: 1.7 μm; and feeding the slurry B into a pulsating high-gradient magnetic separator for iron removal to obtain finished slurry C.
The content of the magnetic iron was measured to be 0.08%; and (3) continuously feeding the slurry C into a high-speed rotary flash evaporation dryer through a screw pump for scattering and drying, controlling the drying temperature to be 350 ℃, performing dust removal and packaging to obtain a final finished product, and detecting the granularity D50 of the finished product through a laser granularity analyzer: 1.8 μm. FIG. 2 is a picture of the ultra-fine needle-like wollastonite obtained by wet grinding in this example.
Example 3
In the embodiment, the vertical stirring mill is adopted for wet superfine grinding, the vertical stirring mill adopts an alumina ceramic lining, the filled grinding medium is 92 high-purity alumina ceramic balls, and the true density is 3.62g/cm3The size is 1.2-1.4mm, and the medium filling rate is 65%.
Selecting wollastonite concentrate with calcium silicate content of more than or equal to 95%, coarsely crushing by a jaw crusher, then grinding by a vertical ring roller mill, and controlling by a grader to obtain 400-mesh wollastonite dry powder.
Preparing 400-mesh wollastonite dry powder and water into slurry with the solid content of 65% in a high-speed dispersion barrel, and simultaneously adding a maleic anhydride-butyl methacrylate-styrene dispersing agent accounting for 0.6% of the wollastonite dry powder in the process of preparing the slurry to obtain crude slurry A.
And continuously conveying the slurry A into a vertical stirring mill through a diaphragm pump, wherein the diaphragm pump adopts frequency conversion regulation and control to control the feeding speed, the grinding time of the slurry A in the mill is controlled to be 55min, meanwhile, a certain amount of vinyl trimethoxy silane is added into a chemical adding port in the middle of the mill through a metering pump in the grinding process, and the adding amount of the coupling agent is 0.4 percent of the amount of wollastonite dry powder, so that the slurry B is obtained.
D50 for slurry B as measured by a sedimentation sizer: 1.9 μm; and feeding the slurry B into a pulsating high-gradient magnetic separator for iron removal to obtain finished slurry C.
The content of the magnetic iron was measured to be 0.08%; and (3) continuously feeding the slurry C into a high-speed rotary flash evaporation dryer through a screw pump for scattering and drying, controlling the drying temperature to be 350 ℃, performing dust removal and packaging to obtain a final finished product, and detecting the granularity D50 of the finished product through a laser granularity analyzer: 2.0 μm.
Example 4
In the embodiment, the superfine needle-shaped wollastonite prepared in the embodiments 1 to 3 is detected according to JC/T535-2007, and the relevant indexes are as follows:
| detecting the index | Example 1 | Example 2 | Example 3 |
| Whiteness degree | 94.8 | 94.5 | 94.3 |
| Product particle size D50 | 1.7 | 1.8 | 2.0 |
| Oil absorption number | 32 | 30 | 28 |
| The content of ferric oxide% | 0.08 | 0.08 | 0.08 |
Claims (2)
1. A preparation method of wet-process superfine needle-like wollastonite is characterized in that a wet grinding process is adopted in wollastonite superfine processing, an added dispersing agent is maleic anhydride-butyl methacrylate-styrene, and a silane coupling agent is added in the middle section of a grinding machine to carry out surface treatment on wollastonite particles;
the method specifically comprises the following steps:
(1) selecting wollastonite concentrate with calcium silicate content of more than 95%, coarsely crushing by a jaw crusher, then grinding by a vertical ring roller mill, and controlling by a grader to obtain 400-mesh wollastonite dry powder;
(2) preparing 400-mesh wollastonite dry powder and water into slurry with the solid content of 55-65% in a high-speed dispersion barrel, and adding a dispersant maleic anhydride-butyl methacrylate-styrene in the process of preparing the slurry, wherein the addition amount of the dispersant maleic anhydride-butyl methacrylate-styrene is 0.4-0.6% of the wollastonite dry powder;
(3) continuously feeding the prepared wollastonite slurry into a vertical stirring mill through a diaphragm pump for grinding, and adding a silane coupling agent into the slurry from a middle dosing port of the mill; the silane coupling agent is prehydrolyzed vinyltrimethoxysilane, and the addition amount of the silane coupling agent is 0.3-0.5 percent of the dry powder amount of wollastonite; controlling the feeding speed of the slurry to control the grinding time of the material in the mill, and further controlling the final granularity of the slurry to obtain the finished slurry;
(4) feeding the finished slurry into a pulsating high-gradient magnetic separator for iron removal, and drying and scattering to obtain a finished product of superfine needle-like wollastonite;
the grinding medium of the vertical stirring mill adopts high-strength wear-resistant ceramic balls, the volume filling rate is 63% -68%, and the size of the medium is 1.2-1.4 mm.
2. The method for preparing the wet-process ultrafine acicular wollastonite according to claim 1, wherein the drying and scattering treatment adopts a spin flash dryer with powerful scattering function.
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| CN110951278A (en) * | 2019-11-14 | 2020-04-03 | 江西广源化工有限责任公司 | Preparation method of high-reinforcement ultrafine wollastonite special for pipes |
| CN115010994B (en) * | 2022-05-13 | 2023-12-05 | 江西广源化工有限责任公司 | Modified superfine wollastonite powder and preparation method and application thereof |
| CN114988420A (en) * | 2022-07-11 | 2022-09-02 | 福建长泰万泰矿物制品有限公司 | Silica iron-removing bleaching process |
Citations (3)
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|---|---|---|---|---|
| CN1043150A (en) * | 1988-12-06 | 1990-06-20 | 张春芳 | The preparation method of wollastonite packing |
| CN104448110A (en) * | 2013-09-15 | 2015-03-25 | 徐丽萍 | Synthesis method for SML hyperdispersant |
| CN104744971A (en) * | 2015-03-04 | 2015-07-01 | 江西科越科技有限公司 | Preparation process of wet-process superfine modified calcium carbonate |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1043150A (en) * | 1988-12-06 | 1990-06-20 | 张春芳 | The preparation method of wollastonite packing |
| CN104448110A (en) * | 2013-09-15 | 2015-03-25 | 徐丽萍 | Synthesis method for SML hyperdispersant |
| CN104744971A (en) * | 2015-03-04 | 2015-07-01 | 江西科越科技有限公司 | Preparation process of wet-process superfine modified calcium carbonate |
Non-Patent Citations (1)
| Title |
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| 硅灰石矿功能化微粉制备新工艺研究;张银年，丁浩，张克仁等;《非金属矿开发利用》;20011031(第5期);第13-18页 * |
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