JPS5827983B2 - High speed fluid grinding and dispersion mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention A continuous high speed attrition and dispersion mill and screener for fluids is disclosed.

The mill allows high flow rates and therefore does not require cooling.

It consists of a closed container, an annular wear ring approximately in the center of the container, a helical axis rotating about a vertical axis terminating in approximately the center of the container and extending into the container, and an axis rotating within the wear ring. an impeller mounted at the end of the impeller, the impeller being in the form of a disk with a plurality of shear vanes around its periphery to form a high shear zone between the vanes and the wear ring.

An inlet is provided in the vessel directly below the impeller on the vertical axis, and an outlet is provided in the vessel located at a predetermined height directly above the impeller on the vertical axis, such that fluid flow from the inlet to the outlet is Pass through high shear regions.

Means are provided for rotating the shaft and impeller.

TECHNICAL FIELD This invention relates generally to apparatus for grinding, dispersing and sorting fluid materials.

More particularly, the present invention relates to apparatus for continuously deagglomerating and dispersing high solids compositions, such as pigments, and milling the slurry to reduce particle size.

This device is also capable of varying particle size.

Various types of equipment are well known in the art for grinding or dispersing homogeneous mixtures, emulsions, and the like.

For grinding, this type of equipment includes ball mills, roller mills, vibratory mills, sonic Fu stirrers, homogenizers, mixers, etc.

One device for dispersing substances is disclosed in U.S. Pat. No. 36,389.
No. 17, disclosed by Osten, in this case by passing the material through a constantly dynamic centrally curved channel where it is exposed to a region of high shear action.

A method of connective high shear dispersion of materials is obtained.

Osten's device does not act as a sorter.

This has no special features; the intensity of the grinding can only be varied by changing the speed of the impeller.

Additionally, this equipment generates too much heat and has low capacity for use with finished titanium dioxide slurries and the like.

It is an object of the present invention to provide a high capacity continuous high speed attrition and dispersion mill for fluid materials, in which the material has a high shear zone
multiple passes, and only this one pass through the high shear region.
It is sufficient to deagglomerate and disperse the high solids composition to such an extent that the titanium dioxide pigment slurry no longer settles after the dispersion process.

The mill is equipped with a variable outlet that allows variation of the ejected particle size, so the mill can act as a sorter.

This device generates only a small amount of heat and does not require any cooling jacket to cool the mill as it passes through the mill.

High speed performance allows large volumes of fluid material to be passed through the mill in a short period of time.

Furthermore, the mill itself is small in size relative to its capacity, easy to dismantle, is self-draining, and unlike Osten's device has curved sides on only one side, thus It is cheaper to manufacture than mills with curved sides.

This mill uses standard, commercially available equipment and does not introduce air into the slurry.

Also, pollution is reduced to a minimum.

The present invention provides a continuous high speed attrition and dispersion mill and sorter for fluids, the apparatus comprising a closed vessel with an annular wear ring approximately in the center of said vessel and a container terminating in said vessel approximately in the center thereof. a helical shaft rotating about a vertical axis extending within the wear ring; and an impeller mounted at the end of the shaft adapted to rotate within the wear ring, the impeller having a plurality of shear vanes around its periphery. In the form of a disk and forming a high shear zone between the vanes and the wear ring, the device further includes an inlet in the vessel directly below the impeller on the vertical axis and at a predetermined height directly above the impeller on the vertical axis. an outlet located in the vessel so that fluid flow from the inlet to the outlet passes through the high shear zone, and means for rotating the shaft and impeller.

In a preferred embodiment of the invention, the predetermined height of the outlet can be varied above the impeller to adjust the particle size of the fluid exiting the mill.

Therefore, the properties of the slurry exiting the mill can be tailored to meet process requirements.

In other embodiments, the axis extends downward into the container and the output [J is located about one axis.

In yet another embodiment, the top of the container exhibits a conical shape and includes an outlet, the outlet being tubular and extending downwardly into the interior of the container at a variable height above the impeller; The bottom of the container exhibits an inverted conical shape and includes an inlet that is tubular and extends upwardly into the interior of the container.

The container may include a removable annular wear ring.

- In an embodiment, the width of the high shear zone between the vanes and the wear ring ranges from about 2.54 to 7.62 cTL, and the fluid flow rate through the mill ranges from about 26.4.9 to 41.641 cTL per minute. is within the range of

In other embodiments, the impeller moves approximately 1.43-3.
It rotates to provide a circumferential speed in the range of 44 km.

Hereinafter, the invention will be further explained by way of example with reference to the accompanying drawings.

One embodiment of a high speed grinding and dispersion mill is shown in FIG.

The container is fabricated from mild steel or stainless steel and has a conical top half 10 with a tubular outlet 11 extending downwardly into the interior of the container and adjustable to different height positions within the top half 10. can do.

Top half 10 is joined to bottom half 12 and halves 10 and 12
An annular wear ring 13 is provided between the two.

The bottom half 12 of the container is inverted conical and includes a tubular inlet 14 extending upwardly into the interior of the container.

A drainage hole 15 is provided and extends through the wall defining the tubular population 14 to allow slurry to drain from the lower half of the vessel when high speed milling and dispersion is not occurring. make it possible.

The top half 10 and bottom half 12 are connected by a flange 16 so that the container can be easily separated for maintenance and cleaning purposes.

A bolt 17 with a special manual nut 18 joins the two halves 10 and 12 together.

Loosen the nut 18 and move the bolt 17 to pivot position 1.
9, the bottom half of the container 1
2 can be lowered from the top half 10 and the wear ring 13 can thus be inspected and replaced if necessary.

A rotating shaft 20 extends from the top downwardly through the tubular outlet 11 to approximately the center of the container and between the top and bottom halves 10 and 12 in the wear ring 13, with an impeller 21 at the end of the shaft 20. Attach.

The impeller 21 is in the form of a disk, has a plurality of blades 22 around its periphery, and rotates within the wear ring 13 .

The space between the vanes 22 and the wear ring 13 is a high shear region 23
The fluid material or slurry passes through this region 23 where dispersion and attrition occur.

In one embodiment, the impeller 21 used in the vessel is a commercially available "Colorless No-Isher Disc" mounted on a shaft 20 and driven by a variable speed electric motor (not shown).

The circumferential speed or tip speed of the impeller is preferably 1.0 per minute.
43-3.44 km, and the high shear zone 23 between the blade tip and the wear ring 13 is preferably about 2.5 km.
It ranges from 4 to 7.62 CrrL.

The high shear zone 230 area can be varied by inserting impellers 21 of different sizes or wear rings 13 of different inner diameters.

A seamount chamber 24 and a discharge pipe 25 may be provided to supply the dispersed slurry to a supply or storage tank.

The height of the inlet 14 below the impeller 21 can affect the attrition of particles in the slurry.

Maximum abrasion occurs if inlet 14 terminates just below impeller 21.

If the inlet is lower than that, attrition is reduced but agglomerates in the slurry are destroyed.

If the area of the high shear zone is small, there will be attrition of the slurry in the vessel; if the area is large, there will be less attrition and more dispersion, and less energy will be applied to the fluid passing through the high shear zone. is transmitted.

The height of the outlet 11 is varied depending on the required particle size exiting the mill.

That is, the location of the outlet 11 causes the mill to act as a sorter.

If the height of the outlet 11 is lowered, the buff 21A of the impeller 21
Reduce the exit area across.

This creates a restriction in the flow through the mill, which results in more attrition of the particles within the mill to a smaller particle size.

If the outlet 11 is raised within the container 10, the imperano tube 21
As A exits the outlet 11, the outlet diameter increases, also increasing the flow through the mill and resulting in less grinding and therefore larger particle size.

By positioning the outlet at different locations within vessel 10, the particle size of the slurry exiting the mill can be varied.

In one embodiment, the inlet 150 area is less than the area of the outlet 11, even when the outlet is in its lowest position spanning the impeller bub 21A, so there is little pressure build-up within the mill that could cause heating. or not occur at all.

In the case of finished titanium dioxide pigments, heating causes destruction of the organic dispersant.

The material of construction of the container is preferably mild steel or stainless steel.

The annular wear ring 13 can also be made from mild steel or stainless steel.

The wear ring can also be coated with a hard wear-resistant material, such as tungsten carbide, or if it consists of a ceramic insert.

The shaft 20 is preferably driven by an electric motor with variable speed drive.

Impeller 21 is preferably a standard collarless diffuser blade, a disc with adjacent vanes on either side of the disc.

The height of the vanes above the disc can be varied depending on the degree of abrasion required.

Making the blades higher on each side of the disk increases grinding in the mill.

In operation, a high solids slurry is continuously fed into the inlet pipette 14, and the slurry is passed through the shaft 20 directly below the impeller 21.
flows out along the vertical axis of.

As the slurry moves outward, it is captured by the far-flooding force of an impeller rotating at high speed within the vessel.

Particles that are small enough will flow upwardly through the high shear zone 23, larger particles will be blown out of the mill and returned to the bottom of the vessel.
After turning there, it passes upwardly through the high shear zone 23 in close proximity to the wear ring 13 .

The slurry is vigorously stirred by the centrifugal force of the impeller 21 and the blades 22 and rotates at high speed.

Larger particles tend to be kept outside the container and can fall back into the high shear zone 23 if they occur.

The outlet 11 creates a vortex that causes the slurry to fly up the conical side of the top half 10.

If the outlet is in its highest position, the vessel exhibits low efficiency as a sorter, but destroys agglomerates in the slurry.

When the outlet 11 is in its lowest position, the container exhibits maximum efficiency as a sorter, and larger particles return to the high shear zone and are destroyed.

The container is completely sealed and does not require an exhaust vent.
Air is not mixed with the slurry.

If it is necessary to clean the device, this can be done by loosening the special manual nut 18 and cleaning both halves 10 and 12 of the container.

The circumferential speed of the impeller 21 can be varied by changing the rotational speed of the shaft 200 in accordance with the specific material being processed.

For coated titanium dioxide materials, if the circumferential speed of the impeller is too slow, sufficient dispersion will not occur in the slurry.

If the circumferential speed is too high, the coating may peel off from the titanium dioxide pigment, which is unacceptable.

In one particular example, a 29.53 CTL diameter impeller was tested with a high shear zone distance between the blade tip and the wear ring of 6.19 cm.

The circumferential speed of the impeller was 2.42 krn/min.

The experimental material is a high solids slurry containing the finished pigment, in one case at least 63%, depending on the pigment application.
% solids, and in other examples at least 76%.

During each run, a sample of the mill slurry was taken and tested for color/tone and tinting strength to ensure that the slurry did not contain agglomerates.

It is clear that complete homogenization has occurred in the slurry;
Comparative tests showed that the properties of the resulting slurry were comparable to, if not better than, the dry finished pigment.

The rheological properties of the slurry were also excellent. Flow rate 2 per minute
6.49-4], 641 culm, the temperature difference through the mill was found to be about 7.22°C.

This temperature difference was reduced at higher throughputs as the slurry acted as a coolant in the mill.

This high slurry flow rate allows up to 1001 tons of solids to be processed through the mill each day.

It will be apparent to those skilled in the art that various modifications may be made to this mill without departing from the scope of the invention.

The cone angles of the top and bottom halves of the vessel can be selected depending on the particular flow and sorter requirements.

If so, it is desirable to provide a cooling jacket surrounding the lower half of the mill.

The mill itself can also be made of ceramic material to provide additional wear characteristics.

The wear link halves are easily replaceable and, if present, can be made integral with the container.

Alternatively, a special coating can be applied to the entire inside of the container to reduce wear.

[Brief explanation of the drawing]

The drawing is a cross-sectional front view of one embodiment of a continuous high speed attrition and dispersion mill. 10... Top half, 12... Bottom half, 1
3...Wear ring, 14...In ['',
15... Drain hole, 16... Flange,
17... Bolt, 18... Special manual nut, 19... Pivot, 20... Shaft, 21... Impeller, 21A-... ...)・
22... vane, 23... high shear area, 24... wetting chamber 25... discharge pipe.

Claims (1)

Claims: 1. A container comprising an annular wear ring approximately in the center of the container; a shaft rotatable about a vertical axis terminating in substantially the center of the container and extending into the container; a disc-shaped impeller mounted on the end of the shaft and having a plurality of shear vanes around its periphery to form a high shear zone between these vanes and the wear ring, and located directly below the impeller on the vertical axis; an inlet in the vessel located at a predetermined height directly above the impeller on the vertical axis such that fluid flow from the inlet to the outlet passes through a high shear zone; and means for rotating a fluid substance. 2. The device of claim 1, wherein the device extends downward into the container with two shafts and the outlet is positioned about the shaft. 3. The top of the container has a conical shape with an outlet tubular and extending downwardly into the container, and the bottom of the container has an inverted conical shape with an inlet tubular and extending upwardly into the container. 3. A device according to claim 2, comprising: 4. Apparatus according to claim 3, in which the population can be set at a variable distance below the impeller and is provided with drainage holes to prevent fluid from remaining in the mill. 5. The device according to claim 2, wherein the predetermined height of the outlet can be set at a variable distance above the impeller. 6 The width of the high shear zone between the vane and the wear ring is approximately 2.5
Claim 1 in the range of 4 to 7.62CrfL
Apparatus described in section. 7. The fluid flow rate through the mill is approximately 26.49 to 41.5% per minute.
64. 2. The device of claim 1 in the range g. 8. The apparatus of claim 3, wherein the circumferential speed of the impeller is in the range of about 1.43 to 3.44 km per minute. 9. The apparatus of claim 1, wherein the fluid flowing through the mill contains at least 60% solids. 10. The device according to claim 2, wherein the annular ring is removable. 11. The device of claim 2, wherein the inside of the container and the wear ring are coated with a wear-resistant material.