JPH09150072A - Slurry manufacturing method and apparatus - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] A method and apparatus for suppressing the generation of ultrafine particles having a particle diameter of about 0.2 μm or less as much as possible and for manufacturing a slurry which is advantageous in manufacturing equipment, manufacturing time, manufacturing cost, etc. SOLUTION: A raw ore is pulverized to a particle diameter of 50 μm or less by subjecting a raw ore to a compression / shearing action at a dry ultra high pressure, and then a volume pulverization of ultrafine particles having a particle diameter of 5 μm or less by a wet medium stirring pulverization method. A method for producing a slurry, which is characterized in that the slurry is produced by a method to form a slurry.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a slurry having excellent characteristics by ultrafinely pulverizing a raw material ore, and more specifically, it enables volumetric pulverization to an ultrafine particle region to obtain a slurry. Particle diameter that reduces the properties of about 0.
A slurry capable of suppressing the generation of ultrafine particles of 2 μm or less as much as possible, and efficiently producing a slurry having properties significantly superior to those of a slurry produced by a conventional wet medium agitation mill, that is, a so-called grinding method. The present invention relates to a manufacturing method and device.

[0002]

2. Description of the Related Art Slurries of raw material ores used in industrial fields such as papermaking coating materials, various fillers and pigments are manufactured by the following method. That is, as shown in FIG. 10, the raw ore M mined from the mine is crushed to a diameter of about 25 mm or less by a crusher, and then put into a wet-type natural crusher 102 together with water and a dispersant to be stirred and self-generated. It is crushed and filtered by a self-crushing screen 104.
In the primary wet agitation mill 106, the raw material ore is agitated together with silica particles having a size of a go stone, and is filtered by the primary screen 107. Next, the secondary wet stirring mill 1
At 08, the raw ore is agitated with Ottawa sand and zircon particles having a diameter of 1.0 to 1.5 millimeters and filtered by a secondary screen 109.

After that, it is distributed to the tertiary wet stirring mill 112 by the buffer tank 110, and the tertiary wet stirring mill 1
At 12, the raw ore is further agitated with zircon particles and filtered by a tertiary screen 114.
Next, in the quaternary wet stirring mill 116, the raw material ore is stirred together with the Ottawa sand and the zircon particles, filtered by the quaternary screen 118, and further filtered by the magnet filter 120. The magnet filter 120 removes iron powder generated by abrasion of a stirring blade attached to a rotating shaft of a crusher or a mill. The slurry thus produced contains 70 to 90% of particles having a diameter of 2 μm or less. Here, the self-crushing by a wet stirring mill is to put raw ore particles and water as a solvent together with a dispersant in a water tank, stir these three kinds of processed products with a stirrer, and rub the raw ore with each other. It is a method of crushing into a slurry by. The inside of the wet medium stirring mill is filled with water as a solvent, ceramic balls or silica particles (generally Ottawa sand) with high hardness as a grinding medium, which have a high hardness. Stir the medium. When the slurry produced by the above-mentioned self-pulverization is supplied together with the dispersant, the raw materials are rubbed with the medium and the raw materials to be ultrafinely pulverized.

[0004]

Wet crushing is more suitable for producing ultrafine powder than dry crushing, and many wet crushers are used. Furthermore, among the wet pulverizers, the wet medium agitation mill is the most excellent ultrafine particle because the pulverizing medium in the agitation tank is relatively uniformly agitated, the energy density showing the agitation uniformity is high, and the pulverization efficiency is large. It is a crusher. Examining the compression fracture mode of individual ore particles, which is the basis of crushing, as shown in Fig. 2, a compressive force is usually applied as an external force, but inside the particle, it is converted into a tensile force and fractured by tension. To be done. Seen from another angle, when the particles are fractured by compression, the tensile strength is obtained from the fracture force. The stress is the force per unit area, and the stress when the material breaks is the strength of the material. Even with irregularly shaped particles, the tensile strength of the material can be determined by this method.
This is also called particle crushing strength. While the particle size is sufficiently large, the particles are elastically deformed by this tensile stress and then broken into several pieces. This mode of destruction is called elastic destruction. From the viewpoint of crushing and crushing, this is volume crushing.

The above-mentioned particle crush strength increases as the volume of the particles decreases. That is, there are many latent cracks inside brittle materials such as ores,
They are activated when an external force is applied, resulting in a large number of localized fractures inside the particle. Of these activated latent cracks, the weakest one is the source of destruction. This idea is called the "weakest link theory", but the strength increases gradually as the size of the particle decreases, the number of latent cracks contained in the particle decreases as the volume of the particle decreases, and At the same time, latent cracks, which are weak in strength and become the root of destruction, are gradually used up as the crushing progresses. As can be understood from the change in particle crush strength depending on the particle diameter (schematic diagram) and the mode of fracture shown in FIG. 3, when the particle diameter decreases, this elastic fracture, that is, volume pulverization, occurs until the particle diameter reaches around 20 to 30 μm. However, when the particle size further decreases and reaches 10 to 20 μm, elastic fracture and plastic fracture coexist. Plastic fracture is a crushing method of crushing clay in the extreme case. It is considered that this is because the particles are repeatedly subjected to an external force inside the crusher and the crusher as the crushing progresses, so that strain is accumulated inside the particles and the crystal structure is gradually disturbed to become amorphous.

This mode of fracture continues up to a particle size of 1 to 2 μm, but fine particles smaller than that exhibit complete plastic failure due to compression and no longer exhibit a strength failure point. Therefore, in order to pulverize ore particles having a particle size of several tens of μm to obtain ultrafine particles having a particle size of 1 μm or less, the above-mentioned volume pulverization due to elastic fracture cannot achieve the purpose, and particles of a small size or a mutual size of particles can be achieved. It must be carried out by stirring with a grinding medium and rubbing each other to separate the surface to produce ultrafine powder, that is, surface grinding. Whether wet or dry, this is the principle of ultrafine milling with conventional media agitation mills. However, when a slurry is produced by this method, the particle size distribution of the ultrafine powder produced is relatively wide, and the particle size that reduces the characteristics of the slurry is about 0.2 μm.
There arises a problem that the following ultrafine particles are contained in a large amount. The presence of a large amount of ultrafine particles having a particle size of about 0.2 μm or less causes the viscosity of the slurry to increase. On the other hand, with regard to the specific surface area of dispersoids, the value becomes too large, which causes the problem of excessive consumption of chemicals such as dispersants. In addition, regarding thixotropy (thixotropic), the presence of ultrafine particles causes structural viscosity. It includes the problem of easy occurrence. In addition, at present, there is no technically established wet classification method excluding ultrafine particles with a particle size of about 0.2 μm or less. From an industrial point of view, preliminary grinding is performed by wet self-grinding as described above. The method of performing ultra-fine pulverization by the wet medium stirring method is complicated and inefficient in manufacturing process, and inevitably consumes a large amount of expensive electric power, which causes an increase in slurry manufacturing cost. It was an economically disadvantageous manufacturing method.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional slurry manufacturing method and apparatus, and suppresses the generation of ultrafine particles having a particle diameter of about 0.2 μm or less as much as possible, and An object of the present invention is to provide a method and an apparatus capable of producing a slurry which is advantageous in terms of production equipment, production time and production cost.

[0008]

The first invention of the present application is to finely pulverize a raw ore into a particle size of about 50 μm or less by applying a compression / shear action at a dry ultrahigh pressure, and then by a wet medium stirring pulverization method. It is a method for producing a slurry, which is characterized in that ultrafine particles having a diameter of about 5 μm or less are mainly produced by a volume pulverization method to form a slurry. A second invention is a method for producing a slurry, characterized in that the dry ultra-high pressure fine pulverization is performed by a vertical roller mill. A third aspect of the invention is a method for producing a slurry, wherein the wet medium stirring and pulverizing method includes self-pulverizing. A fourth invention is a method for producing a slurry, wherein the wet medium stirring and pulverizing method uses ordinary silica particles as a pulverizing medium. A fifth aspect of the present invention is the method for producing a slurry, wherein the wet medium stirring and pulverizing method uses Ottawa sand as a pulverizing medium.
A sixth aspect of the invention is a method for producing a slurry, wherein the wet medium stirring and pulverizing method uses zircon particles as a pulverizing medium.

A seventh invention is a dry crusher for finely crushing a raw ore to a particle size of about 50 μm or less by applying a compression / shear action to the raw material ore, and a particle size of about 5 particles arranged downstream thereof.
A slurry production apparatus comprising: a wet medium agitating pulverizer that mainly produces ultrafine particles of μm or less by a volume pulverizing method. An eighth invention is a slurry manufacturing apparatus, wherein the dry crusher is a vertical roller mill. A ninth aspect of the invention is a slurry producing apparatus, wherein the wet medium agitating pulverizer includes an autogenous pulverizer. A tenth aspect of the present invention is the wet medium stirring and crushing machine,
This is a slurry manufacturing apparatus characterized by using ordinary silica particles as a grinding medium. An eleventh aspect of the invention is a slurry manufacturing apparatus, wherein the wet medium stirring and pulverizing method uses Ottawa sand as a pulverizing medium. First
A second aspect of the invention is a method for producing a slurry, wherein the wet medium stirring and pulverizing method uses zircon particles as a pulverizing medium.

[0010]

The supplied raw material ore is pulverized by a high pressure dry pulverizer to produce fine particles. At the same time, although it was difficult to realize with the conventional method, even the very strong microscopic latent cracks contained in these fine particles are forcibly activated all at once,
Ultrafine particles are produced by subjecting this to a volume pulverization mainly by a wet medium stirring pulverizer. By doing so, the production of ultrafine particles having a particle diameter of about 0.2 μm or less, which adversely affects the slurry characteristics, is suppressed as much as possible to produce a high quality slurry.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A slurry manufacturing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The raw ore is heavy calcium carbonate, and ore particles of several tens of millimeters or less are stored in the mill feed bin 8 by the vibrating feeder 2, the belt conveyor 4 and the bucket elevator 6, as shown in FIG. The raw ore stored in the mill feed bin 8 is taken out by the screw feeder 10 and supplied to the vertical roller mill 12. Here, the raw material ore is crushed by the high-pressure roller 13 (see FIG. 4). Of the crushed raw ore, fine powder having a predetermined particle size or less passes through the separator 14 and is pneumatically transported to the back filter 16 to be separated into fine powder and clean air. The clean air is discharged into the atmosphere by the exhaust fan 18. The fine powder collected by the tap filter 16 is temporarily stored in the preliminary crushed product bin 26 via the screw conveyor 20, the bucket elevator 22, and the screw conveyor 24. It is taken out from here by the rotary feeder 28, crushed by the primary wet agitation mill 32 by the screw conveyor 30, and then stored in the buffer tank 36 through the primary screen 34. After that, it is supplied to the secondary wet stirring mill 40 by the primary distributor 38, further pulverized therein, and coarse particles are removed by the secondary screen 42. After that, the slurry product is supplied to the tertiary wet stirring mill 46 by the secondary distributor 44, further pulverized therein, coarse particles are removed by the tertiary screen 47, and a trace amount of iron mixed by the magnet filter 48 is removed to finally store the slurry product. Store in tank 49.

The primary wet agitation mill 32, the secondary wet agitation mill 40, and the tertiary wet agitation mill 46 are filled with ceramic balls or silica particles having a particle diameter of several millimeters as a grinding medium, and a dispersant is appropriately added. Is added. The screw feeder 10, the vertical roller mill 12, and the separator 14 are arranged and assembled as shown in FIG. The particles of the raw ore are supplied to the center of the table 50 which is horizontally rotated by the screw feeder 10. Table 50 rotated by a motor 51 with a reducer
The raw material ore is moved in the outer peripheral direction by the centrifugal force of. The several rollers 13 mounted along the race recess 54 on the outer peripheral portion are attached to the table 5 by the hydraulic unit 55.
Pressurized in 0 direction. The raw material ore is crushed between the roller 13 and the race recess 54, and then moved to the outer peripheral portion.
In the outer ring of the table 50, a swirl upward airflow is generated through the nozzle 60, and the crushed raw material ore is carried to the rotor portion 62 that rotates at a high speed in the upper separator 14 and is classified. Here the coarse powder falls and is reground with fresh raw ore. The pressing force of the roller 13 is several times that of a normal rigid roller mill, for example, about twice that of a normal rigid roller mill in this embodiment. The classified powder is sent to the primary wet agitation mill 32. In addition, foreign matter such as metal pieces,
Falling in the nozzle 60 against the upward air flow, foreign matter discharge port 64
Is discharged to the outside of the device through.

The rigid roller mill 12 shown in FIG. 4 is a typical type of roller race mill. Other roller race mills include a mill in which both the table race and the crushing surface of the roller are horizontal, and a mill in which the table race and the crushing surface of the roller are inclined. In addition, these mills should be replaced with ring roller mills, in which an annular fixed crushing surface (tire) and pendulum-shaped rollers make vertical contact by centrifugal force to crush, and ball race mills in which large steel balls are crushed instead of rollers. You can also

[0014]

The results of the comparison of the properties of the slurry containing about 75% of the heavy calcium carbonate fine particles produced by the method according to the present invention and the conventional method are shown in FIG. (1) Particle size distribution The particle size distributions of both slurries are almost the same. The reason is that in the Microtrac particle size distribution measuring device,
This is because it is impossible to accurately measure the particle size distribution of 17 μm or less. In the specific surface area, viscosity, and thixotropy described below, the difference between the two is clearly recognized. Particle size distribution measuring device: Laser diffraction type particle size distribution measuring device. Microtrac SPA Nikkiso Co., Ltd.

(2) Specific surface area: The slurry produced according to the present invention has a surface area of 9.55 m ² /
g, which is about 30% less than that obtained by the conventional grinding method. This indicates that the content of ultrafine particles having a particle diameter of 0.17 μm or less is small and the present invention is more advantageous. This is because when the ultra-fine particles are contained in a large amount, the value of the specific surface area becomes large and various adverse effects are caused as described above.

(3) Slurry viscosity The slurry produced according to the present invention is 6.4 poise, about 40% less. The lower the viscosity, the higher the slurry concentration and the higher the transport efficiency of heavy calcium carbonate. This result also shows that the slurry produced by the method of the present invention produces less ultrafine particles. Slurry Viscometer: RION VISCOTESTER VT-04

(4) High shear viscosity and thixotropy As shown in FIGS. 5, 6 and 7, the high shear viscosity is N44.
At 00 rpm, the slurry produced by the conventional method is 0.86 poise, while the slurry produced by the method of the present invention is 0.67 poise, about 20% lower.
This indicates that the method according to the present invention is less thixotropic and easier to handle as a coating amount, which is advantageous. The thixotropy is 280.5 × 10 ⁴ dy at 2400 rpm for the slurry produced by the conventional method.
228.5 × 10 ⁴ dyne at ne ・ cm and 3000 rpm
Cm, whereas the slurry produced by the method of the present invention has 176.5 × 10 ⁴ dyne at 2400 rpm.
・ Cm at 3200γpm 150.8 × 10 ⁴ dyne ・
It has a low cm and a low thixotropy, and the slurry produced according to the present invention has a lower structural viscosity and is much easier to handle than a slurry produced by a conventional method. These measurement conditions are shown in FIGS. 6 and 7.

(5) Abrasion Degree The slurry according to the present invention is 54.1 mg, which is about 10% less than that by the conventional method. The lower the degree of wear, the less the main parts of the paper machine are worn, and the higher the quality. Abrasion degree measuring instrument: Nippon Filcon Corporation type abrasion tester Bronze wire abrasion degree (roll: A roll)

(6) Electric power consumption rate (kWh / t) The electric power consumption rate is a specific grinding energy and is an important value representing the grinding efficiency in an industrial sense, and the slurry according to the present invention is more conventional. This is about 16% less than the product produced by the above method, which shows that the slurry production method of the present invention is very economically advantageous as compared with the conventional method.

(7) Scanning electron microscope photograph An electron microscope photograph of the slurry according to the present invention is shown in FIG.
An electron micrograph of the slurry by the conventional method is shown in FIG. The slurry according to the present invention has less fine powder having a particle size of 0.2 to 0.3 μm or less, and the slurry produced according to the present invention is less advantageous in producing ultrafine powder than the slurry produced by the conventional method. Shows. Scanning electron microscope: S-2500 Hitachi, Ltd.

Therefore, according to the first invention and the seventh invention of the present application, it is possible to suppress the generation of ultrafine particles having a particle size of about 0.2 μm or less as much as possible, and to obtain a slurry which is advantageous in manufacturing equipment, manufacturing time and manufacturing cost. It has a manufacturable effect. That is, fine particles are produced by crushing the supplied raw material ore in a high pressure dry crusher in an anterograde manner. At the same time, even microscopic latent cracks with extremely strong strength contained in these fine particles, which were difficult to achieve by the conventional method, are forcibly activated at once, and then the wet medium agitation grinding is performed. When the finishing pulverization is performed with a machine, it is possible to generate ultrafine particles mainly by volume pulverization, and as a result, it is possible to suppress the generation of ultrafine particles having a particle size of about 0.2 μm or less, which adversely affects the slurry characteristics. Is possible.

Further, regarding the second and eighth inventions, the vertical roller mill can easily obtain an ultra-high pressure as compared with the other dry pre-mills, and can efficiently generate the above-mentioned microscopic latent cracks. It has the effect of being able to be activated. With regard to the third and ninth aspects of the invention, preliminary dry crushing can activate even microcracks having extremely high strength, which were impossible by the conventional method. Depending on the type and properties of the raw ore, it may be effective to apply the wet autogenous crushing method to the subsequent wet ultrafine crushing. Regarding the fourth and tenth inventions, the use of commonly used siliceous sand as a grinding medium has the effect of producing ultrafine particle slurry with less contamination at low cost.

Regarding the fifth and eleventh inventions, Ottawa sand which is often used has the same effect as above when used as a grinding medium. Regarding the sixth and twelfth inventions,
The use of zircon particles having high hardness as a grinding medium has a better effect of ultrafine grinding in wet ultrafine grinding.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view of a slurry manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a compression fracture mode of ore single spherical particles.

FIG. 3 is a graph showing the relationship between the particle diameter of ore particles and the particle crush strength in the case of quartz, and the mode of destruction.

FIG. 4 is an explanatory sectional view showing the arrangement and structure of a screw feeder, a vertical roller mill and a separator.

FIG. 5 is a table showing a comparison of properties between the slurry manufactured by the method of the present invention and the slurry manufactured by the conventional method.

FIG. 6 is a graph showing the thixotropy of a slurry according to the method of the present invention.

FIG. 7 is a graph showing thixotropy of a slurry manufactured by a conventional method.

FIG. 8 is an electron micrograph of a slurry produced by the method of the present invention.

FIG. 9 is an electron micrograph of a slurry manufactured by a conventional method.

FIG. 10 is a structural explanatory view of a conventional slurry manufacturing apparatus.

[Explanation of symbols]

 2 Vibration Feeder 4 Belt Conveyor 6 Bucket Elevator 8 Mill Feed Bin 10 Screw Feeder 12 Rigid Roller Mill 13 Roller 14 Separator 16 Bac Filter 18 Exhaust Fan 20 Screw Conveyor 22 Bucket Elevator 24 Screw Conveyor 26 Preliminary Product Bin 28 28 Rotary Feeder 30 Screw Conveyor 32 Primary wet agitation mill 34 Primary screen 36 Buffer tank 38 Primary distributor 40 Secondary wet agitation mill 42 Secondary screen 44 Secondary distributor 46 Tertiary wet agitation mill 47 Tertiary screen 48 Magnet filter 49 Storage tank 50 Table 54 Race recess 55 Hydraulic pressure Unit 60 Nozzle 62 Rotor part

[Procedure amendment]

[Submission date] March 22, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a structural explanatory view of a slurry manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a compression fracture mode of ore single spherical particles.

FIG. 3 is a graph showing the relationship between the particle diameter of ore particles and the particle crush strength in the case of quartz, and the mode of destruction.

FIG. 4 is an explanatory sectional view showing the arrangement and structure of a screw feeder, a vertical roller mill and a separator.

FIG. 5 is a chart showing a comparison of properties between a slurry produced by the method of the present invention and a slurry produced by a conventional method.

FIG. 6 is a graph showing the thixotropy of a slurry according to the method of the present invention.

FIG. 7 is a graph showing thixotropy of a slurry manufactured by a conventional method.

FIG. 8 is an electron micrograph of a slurry produced by the method of the present invention.

FIG. 9 is an electron micrograph of a slurry manufactured by a conventional method.

FIG. 10 is a structural explanatory view of a conventional slurry manufacturing apparatus.

[Explanation of Codes] 2 Vibratory Feeder 4 Belt Conveyor 6 Bucket Elevator 8 Mill Feed Bin 10 Screw Feeder 12 Vertical Roller Mill 13 Roller 14 Separator 16 Back Filter 18 Air Discharger 20 Screw Conveyor 22 Bucket Elevator 24 Screw Conveyor 26 Preliminary Grinding Product Bin 28 28 Rotary Feeder 30 Screw conveyor 32 Primary wet agitation mill 34 Primary screen 36 Buffer tank 38 Primary distributor 40 Secondary wet agitation mill 42 Secondary screen 44 Secondary distributor 46 Tertiary wet agitation mill 47 Tertiary screen 48 Magnet filter 49 Storage tank 50 Table 54 race concave part 55 hydraulic unit 60 nozzle 62 rotor part

Claims (12)

[Claims] 1. A raw ore is pulverized to a particle size of 50 μm or less by applying a compression / shearing action to a raw ore at a dry ultra-high pressure, and then ultrafine particles having a particle size of 5 μm or less are produced by a volume pulverization method by a wet medium stirring pulverization method. A method for producing a slurry, which comprises: 2. The method for producing a slurry according to claim 1, wherein the dry ultra-high pressure fine pulverization is performed by a vertical roller mill. 3. The method for producing a slurry according to claim 1, wherein the wet medium stirring and pulverizing method includes self-pulverizing. 4. The method for producing a slurry according to claim 1, wherein the wet medium stirring and pulverizing method uses silica particles as a pulverizing medium. 5. The Otawa sand is used as a grinding medium in the wet medium stirring grinding method.
The described method for producing a slurry. 6. The wet medium agitation pulverization method uses zircon particles as a pulverization medium.
The described method for producing a slurry. 7. A dry crusher for finely crushing a raw ore to a particle size of 50 μm or less by applying a compression / shearing action to the raw material ore and a volume crushing of ultrafine particles having a particle size of 5 μm or less, which is arranged downstream thereof. And a wet medium agitating and crushing machine which is produced by a method. 8. The slurry manufacturing apparatus according to claim 7, wherein the dry crusher is a vertical roller mill. 9. The slurry manufacturing apparatus according to claim 7, wherein the wet medium agitation crusher includes an autogenous crusher. 10. The wet media agitation crusher uses silica particles as a crushing medium.
The described slurry manufacturing apparatus. 11. The slurry manufacturing apparatus according to claim 7, wherein the wet medium stirring and pulverizing method uses Ottawa sand as a pulverizing medium. 12. The method for producing a slurry according to claim 1, wherein the wet medium stirring and pulverizing method uses zircon particles as a pulverizing medium.