RU2559063C1 - Colloid mill - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: in the colloid mill casing the actuating elements (1, 2) are installed coaxially with clearance between them with possibility of relative mutual rotation. The mill contains adjustment unit for clearance (5) between the actuating elements. The actuating elements material contains two or more components, and is characterised by hard strength matrix and presence of nodular soft inclusions with size 1-100 mcm.

EFFECT: invention increases operation life of the actuating elements under conditions of increased cavitation, and their simple manufacturing process.

4 cl, 4 dwg

Description

FIELD OF THE INVENTION

The invention relates to the field of dispersion and activation of materials using hydraulic shocks and hydrodynamic cavitation, and can be used in technological equipment for the preparation of suspensions, emulsions, solutions and other liquid products in the production of building materials, chemical, and other industries.

State of the art

Known colloidal mill for wet grinding, consisting of a housing with a conical socket in the middle, in which a rotor mounted on a vertical shaft rotates at a high speed (see book. L. Kasatkin. Main processes and apparatuses of chemical technology. Publishing house 7, M. , 1961, p. 796, fig. 561). There is a negligible gap between the rotor and the socket (less than 0.05 mm). The liquid entering through the inlet with the suspended solids in it passes between the conical socket and the rotor, while the abrasion (dispersion) of solid particles occurs only due to the large forces in a thin layer of liquid between the working surfaces of the rotor and the socket (stator), which does not provide high the intensity of the process.

Known rotary hydraulic mill (patent RU 2081701, IPC: В02С 7/00, ВВВ 17/02, publ. 06/20/97), comprising a housing with inlet and outlet nozzles installed in the housing of the stator and rotor in the form of removable disks with alternating cavities and protrusions on work surfaces. The protrusions and depressions of the movable disk move with great speed, breaking the flow of pulp, disrupting its continuity and creating a cavitation zone. In front of the moving protrusions and troughs, a high pressure zone is created, and behind them is a zone of flow discontinuity and low pressure. In the latter, the formation and growth of cavitation bubbles occurs. At the moment of contact between the high and low pressure zones, the bubbles rupture (collapse), as a result of which the kinetic energy accumulated by them is released, which destroys the particles of solid material that are close at this moment.

Known colloidal wet grinding mill KLM GlobeCore, LLC "Plant UKRBUDMASH" (http://globecoremill.com/ru/), containing a rotating and stationary working bodies, in the gap between which the product is crushed. On the working surfaces of the stator and rotor facing each other, complex geometric reliefs are formed in the form of cylindrical, radially milled teeth. The teeth create increased turbulence and conditions for hydrodynamic cavitation, which contributes to the high intensity of grinding material.

In both of the aforementioned mills, during operation, the working surfaces of the stator and rotor are subject to wear: the protrusions are erased, the depressions are clogged, the reliefs of the working surfaces are leveled, which leads to a decrease in grinding intensity. To increase the service life of the working bodies, they are made of expensive high-strength materials.

Known micro-vortex disintegrator (patent RU 119261 U1, IPC: V02C 19/18, publ. 08.20.2012), designed to obtain stable colloidal systems and structured emulsions, containing a sealed housing, inside which rotor and stator are rotatably mounted. A dispersible viscous medium with crushed material is fed into the space between the working surfaces of the rotor and the stator through the input device. The working surfaces of the rotor and stator are made with micro-relief in the form of local recesses, which contributes to the formation of cavitation zones and increase the grinding intensity. To increase the service life, the rotor and stator of the disintegrator are made of heat-resistant and wear-resistant material or coated with a wear-resistant coating.

As the closest analogue to the claimed technical solution adopted colloidal mill for wet grinding, disclosed in the source L. Kasatkin Basic processes and apparatuses of chemical technology. Vol. 7, M., 1961, p. 796.

Signs of the closest analogue, similar to the essential features of the proposed technical solution: the presence of a pair of working bodies mounted coaxially with the possibility of relative mutual rotation and with a gap between the working surfaces into which the processed material is fed, and the presence of a mechanism for regulating the said gap.

The disadvantage of the closest analogue is the low intensity of grinding, due to the execution of the working surfaces smooth, because in this case, grinding of material particles occurs only due to high velocity gradients obtained as a result of large velocity drops at small distances corresponding to the thickness of the gap between the stator and rotor.

To increase the grinding intensity due to cavitation processes in the mentioned mill, it is possible to perform relief on the working surfaces. However, cavitation processes not only contribute to the destruction of particles of the crushed material, they also have a destructive effect on the surface of the working bodies, contributing to their rapid wear and smoothing of reliefs.

Disclosure of invention

The technical problem, which is aimed by the invention, is to ensure efficient and continuous operation of the working bodies of the mill in conditions of increased cavitation.

A positive technical result of the proposed solution is a significant increase in the service life of working bodies in conditions of increased cavitation while simplifying the process of their manufacture.

The solution of the technical problem and the aforementioned positive technical results are achieved due to the fact that in a colloid mill containing coaxially mounted working bodies with a gap between each other and with the possibility of relative mutual rotation and the regulation mechanism of the said gap, according to the claimed invention, the working bodies are made of material consisting of of two components or more, characterized by a solid strong matrix and the presence of spherical soft inclusions (inclusions of a softer component cient), particle size from 1 to 100 microns.

The rotation of the working bodies, both or, as in the prototype, one, is carried out relative to their common axis. In the case of a fixed installation of one of the working bodies, the device has a simpler technological design. A rotating working body is called a rotor, motionless - a stator. The processed material is fed into the gap between the working bodies.

A distinctive feature of the prototype of the proposed colloidal mill is the implementation of the working bodies of a two- or multicomponent material, characterized by a solid, solid matrix and the presence of soft spherical inclusions. Such two- or multicomponent materials include various alloys and composite materials.

The great advantage of such working bodies is that initially they can be made smooth, which greatly simplifies and reduces the cost of their production, and the microrelief of the working surfaces is formed during operation as a result of interaction with the crushed material. Under the action of the friction forces of the material on the surface of the working bodies, soft grains are opened, which quickly break down and are washed out of the stronger matrix by the flow of the processed material. As a result, spherical micron-sized shells (microcavities) are formed on the surface of the disks. The dimensions of these cavities are determined by the grain size of the soft inclusions. Microcavities create conditions for hydrodynamic cavitation processes, which increases the degree of grinding of the material, and also helps to accelerate the formation of new microcavities.

As the working surfaces wear, these shells (microcavities) are destroyed, but new grains of soft inclusions are opened and new spherical shells are formed on the working surfaces of the working bodies.

Thus, the formation of the microrelief of the working surfaces is achieved due to the structure of the material of the working bodies and their interaction with the crushed material during the operation of the device. The result is a long and efficient operation of the mill working bodies and their high cavitation ability throughout the entire service life.

The proposed technical solution allows, firstly, to eliminate the need for teeth or other relief on the working bodies in their manufacture, and secondly, provides a significant increase in the working life of the working bodies, almost to their complete erasure. During operation of the device, it is only necessary to periodically adjust the gap between the working bodies.

The analysis of the prior art by the applicant did not reveal solutions characterized by features that coincide with the distinguishing features of the proposed solution. This allows you to positively judge the compliance of the proposed technical solution with the requirements of "novelty" and "inventive step".

As you know, various alloys and composite materials (aka composites) belong to two- or multicomponent materials.

The most widely known alloy that meets the characteristics contained in the formula is cast iron, namely high-strength nodular cast iron (GOST-7293), the essential advantage of which is availability and relatively low cost.

Cast iron is an iron-carbon alloy. Durable cast iron matrix is formed by iron. Carbon in cast iron is contained in the form of graphite, whose grains are gray. In addition to the advantages mentioned above, this material is characterized by a fairly high impact strength and fatigue strength, good machinability, antifriction properties, and low sensitivity to external stress concentrators (recesses, holes, junctions). Due to microvoids filled with graphite, cast iron dampens vibration well (see Prince Lakhtin Yu.M., Leontyeva V.P. et al. Materials Science. Moscow: Mashinostroenie, 1990, pp. 150-152).

It is also possible to use other alloys with a similar microstructure consisting of a matrix (otherwise, a basic solid solution based on some solvent metal) and precipitated particles of another solid solution (inclusions).

As a material for the manufacture of the working bodies of the proposed colloidal mill can be used composite material (composite). Composite is called an artificially created inhomogeneous continuous material consisting of two or more components that differ in chemical composition and physico-mechanical properties, separated in the material by a clearly defined border.

The components of the composite material are geometrically different. A component that has continuity throughout its volume is a matrix. The nature of the matrix component distinguishes between polymer, metal, carbon, ceramic and other composites.

An intermittent (discrete) component, divided in the volume of the composite material, is a filler. The filler in its structure may take the form of dispersed particles or granules, including spherical. Most often, the filler is a reinforcing component, however, it is possible to specify any properties of the filler when creating a composite material (see materials of the Physical Encyclopedia, Chemical Encyclopedia, Prince Materials Science and Technology of Metals, edited by GP Fetisov, M. Higher School , 2006, p. 390-393).

The principles and methods of creating composite materials with desired properties are widely known and covered in the technical literature. Using the latter, new composites can be created that meet the specified characteristics and have a solid, solid matrix and spherical soft inclusions in it, with a particle size of 1-100 microns.

Composite materials are expensive, however, due to the fact that the working bodies of the proposed colloid mill have a long service life, the use of composite materials for their manufacture is economically justified.

The working bodies in the proposed mill can have a different design. For example, they can be made in the form of disks with a flat working surface, or in the form of cones with a conical working surface, or otherwise. In this case, both working bodies can be installed with the possibility of rotation or only one.

In a preferred embodiment of the colloid mill, the working bodies are made in the form of two disks, the upper of which is fixed to the motor shaft, and the lower one is mounted motionless by means of racks. The mechanism for regulating the gap between the disks is made in the form of a screw mechanism for regulating the height of the racks on which the lower disk is fixed.

Brief Description of the Drawings

The possibility of industrial feasibility of the proposed technical solution is confirmed by the following example and illustrative materials, where: in Fig.1 - shows a colloidal mill, a general view, schematically; figure 2 is a photograph of the original working surface of the rotor disk; figure 3 is a photograph of the working surface of the rotor disk after 12 hours of operation; figure 4 is a photograph of the working surface of the rotor disk after 24 hours of operation.

The implementation of the invention

The proposed colloidal mill contains coaxially mounted working bodies in the form of disks 1 and 2. The upper disk 1 is mounted on the shaft of the electric motor 3. The lower disk 2 is mounted motionless by means of struts 4. A gap is formed between the working surfaces of the disks 1 and 2 5. The clearance adjustment mechanism 5 made in the form of microscrews 6, regulating the height of the racks 4.

In the above example, both discs 1 and 2 are made of ductile iron with spherical inclusions of graphite. In another example implementation of the mill discs 1 and 2 can be made of composite material.

In any case, the material for the manufacture of disks consists of at least two components and is characterized by a solid, solid matrix and the presence of spherical soft inclusions, 1-100 microns in size.

The device operates as follows.

The engine 3 is turned on and the disk 1 is rotated. A slip funnel 7 is fed into the gap 5 between the disks 1 and 2, where clay particles are crushed to colloidal sizes (less than 200 nm) due to high velocity gradients and cavitation processes. During the grinding process, centrifugal forces move the material to the periphery, from where it is discharged into the hopper of the crushed material.

To confirm the effect of constant formation during operation of the microrelief of the working surfaces, a survey was made of the same working surface of the rotor with a given time interval. To obtain photographs, an Altami MET5C optical microscope with a polarizing filter and a magnification of × 200 was used.

Initially, the working surfaces of the disks 1 and 2 do not have a significant relief, which is clearly seen in figure 2, which shows a photograph of the original - polished working surface of the rotor disk. In the process, under the action of friction forces from the side of the crushed material, soft grains of spherical graphite are opened, which are quickly destroyed and washed out by the stream of the processed material from a more durable iron matrix. As a result, spherical shells of micron sizes corresponding to the sizes of graphite inclusions are formed on the working surfaces of the disks. This is clearly visible in the photograph of the rotor working surface taken after 12 hours of its operation. The stator surface has a similar structure.

Microcavities create conditions for the formation and growth of cavitation bubbles and the flow of hydrodynamic cavitation, which increases the degree of grinding of the material.

As the device operates, wear of the working surfaces of the disks 1 and 2 occurs, a gradual erasure, destruction of the sinks existing on the working surfaces of the disks occurs. However, at the same time, the opening of new grains of graphite and the formation of new spherical shells, already in another place on the surface.

As can be seen in the images of the same working surface of the rotor, made after 24 hours of operation of the mill (see figure 4), the microrelief of the working surface changes. Dark graphite inclusions move, the microrelief pattern changes, but it remains and ensures the course of cavitation processes.

The result is a long and efficient operation of the working bodies of the mill, as well as their high cavitational ability throughout the entire service life.

Periodically during operation of the mill, the microscrews 6 adjust the amount of clearance 5 between the disks 1 and 2.

Claims (4)

1. A colloid mill containing coaxially mounted in the housing with a gap between each other and with the possibility of relative mutual rotation of the working bodies and the regulation mechanism of the said gap, characterized in that the working bodies are made of a material consisting of two components or more, characterized by a solid strong matrix and the presence of spherical soft inclusions with a particle size of 1-100 microns. 2. The mill according to claim 1, characterized in that high-strength cast iron with spherical inclusions of graphite is used as a material for the manufacture of working bodies. 3. The mill according to claim 1, characterized in that as a material for the manufacture of working bodies used composite material. 4. The mill according to claim 1, characterized in that the working bodies are made in the form of two disks, the upper of which is mounted on the motor shaft, and the lower is fixedly mounted by means of racks, while the mechanism for regulating the gap between the disks is made in the form of a screw mechanism for regulating the height of the racks on which the lower disk is mounted.

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