PL190297B1 - Method of and apparatus for dry-grinding solid substances, method of treating flue gas as well as method of and apparatus for removing solid particles from flue gas stream - Google Patents

Abstract

20. A device for dry grinding solid substances, consisting of a semi-permeable element and at least one stage of rotational grinding arranged in a vertical succession. The grinding stage consists of a fixed and a mobile element with a gap in between, which forms a rotational grinding zone. The device also contains elements for directing solid particles approximately upwards, into the rotational grinding zone. It is characterised in that at least one stage of rotational grinding contains at least one rotating semi-permeable element (60) and elements that form a ring-shaped gap (70B) between a fixed plate (70), with a flat surface and a round opening (70A), and a rotating round full disk (61) in the opening (70A). The rotating semi-permeable element (60) and the ring-shaped gap (70B) are arranged to ensure, that a part of particles going upwards can pass through them. Each rotational grinding stage contains a rotating expelling ventilator (62), located behind a rotating semi-permeable element (60) to screen particles going upwards according to their size.

Description

The invention relates to a method and an apparatus for dry grinding of solids.

Until now, the dry grinding process has been carried out in hammer mills, impact mills, ball mills, ring-spring mills or roller mills equipped with internal sorters that classify the required fine fractions and return coarse particles to the grinding chamber. Where super and ultra-fine particles are required, similar solutions are used with vibratory mills, abrasive mills or jet mills. All known mills are poorly efficient for fine grinding, use excessive amounts of energy, and exhibit very high wear.

The disadvantage of dry impact milling in known mills is the accumulation of fine particles of solids produced during grinding and their electrostatic fusing into larger particles, which absorb them during subsequent collisions, which reduces the grinding efficiency.

The problem of electrostatic charge in hammer mills does not occur in jet mills that use high pressure gases, but in turn they consume a lot of energy, require careful maintenance and have limited efficiency.

U.S. Patent No. 3,071,330 discloses a fine-milling apparatus that uses an impeller having radial blades that move along a vertically crimped blade, thereby creating vortices behind the blades that subject the material to be ground to varying high pressures. The substance to be ground is introduced into the air current below the impeller and the material is evenly distributed over the entire cross section of the device before it reaches the grinding degree.

U.S. Patent No. 4,749,133 discloses an apparatus for pulverizing and burning solid fuels such as coal, in which a roughly pulverized solid fuel is introduced into a distal portion of a vertically disposed, closed casing in which one or more throwing machines cast material of housing walls in order to break it.

The main object of the invention is to eliminate the drawbacks of the methods and devices known to date, and to provide a method and apparatus for dry grinding solids, which produces very fine particles in a safe, energy-saving and environmentally friendly manner, with low investment and operating costs.

190 297

A dry solids milling process in which the solids are directed approximately upward into a spin milling zone and the upwardly directed solids are milled in a spin milling zone by passing a portion of the particles through a spin milling zone containing at least one sequentially disposed vertically, a vortex grinding step wherein the particles are passed upward through the semipermeable element and the aperture is characterized according to the invention by passing the particles upward through at least one rotating semipermeable element and an annular aperture defined by a stationary flat surface a disc with a round hole and a full rotating round disc situated in the round hole.

Preferably, in the step of passing the particles upward through the rotating semipermeable element, the particles are passed through an assembly comprising the rotating screen.

Preferably, as part of the step of passing the particles through the rotating sieve, the particles are passed through a sieve not thinner than 2.5.

Preferably, the screen has a number in the range of 2.5 to 60.

Preferably, the screen has a number in the range of 4 to 10.

Preferably, in the step of passing the particles through the annular gap, the particles are passed through an annular gap having a width of 12.7 mm to 152.4 mm (0.5 to 6 inches).

Preferably in each stage the particles are passed through the rotating semi-permeable body and then through the annular gap.

It is preferred to further recycle the particles externally by a centrifugal fan downstream of the rotating semi-permeable member and having a recycle channel to receive the particles from the rotating fan and having an outlet below at least one vortex grinding stage.

Preferably, the particles are also removed above the grinding zone.

Preferably, in the removal step, at least one centrifugal fan is rotated after at least one grinding stage.

It is also preferred to pre-mill the coarse particles to a fine particle before the fine particles are directed into the vortex grinding zone.

It is also preferred to pre-mill the coarse and fine particles by feeding the solids into the chamber, forming a fluidized bed of solids in the chamber, directing air upwards in the chamber, and creating controlled vortices in the fluidized-bed grinding zones with self-grinding operation.

Preferably, the particles are internally recycled by introducing the swirling semipermeable element into the coarse pre-milling zone, and rotating the swirling semipermeable element at a speed sufficient to prevent portions of the oversized particles from passing therethrough and returning the particles to the coarse pre-milling zone.

Preferably, moreover, the particles are recirculated externally to the fluidized bed.

Preferably, a plurality of vortex grinding stages are used and a further stage of external recycle of the particles to the previous stage is used.

Preferably, the removal step removes particles in two vertically arranged removal steps removing particles of increasingly smaller dimensions.

Preferably, the controlled vortex generation step comprises means for creating a controlled vortex in the form of rotors.

Preferably, the rotating semipermeable element and the rotating disc on the common shaft rotate.

Preferably, the milling is performed in an inactive atmosphere in the presence of a chemical reagent to effect controlled surface modification.

Dry solids milling apparatus comprising a semipermeable element and at least one successively vertically oriented vortex grinding stage comprising a fixed and a movable element with a gap therebetween to form a vortex grinding zone and including means for directing the solids approximately upward into the zone spin-milling, characterized according to the invention in that at least one spin-milling step comprises at least one rotating semi-space element.

190 297 admission and annular gap elements comprising a flat surface stationary plate with a circular opening and a rotating solid circular disc disposed in the opening, the rotating semi-permeable member and the annular gap being configured to pass a portion of the upwardly directed particles therethrough. and each vortex grinding stage includes a rotary stripper located downstream of the spinning dimensionally semipermeable member to screen the upwardly directed particles.

Preferably, the rotating semipermeable element comprises an assembly comprising the rotating screen.

Preferably, the rotating screen comprises a screen no less than 2.5 in size.

Preferably, the screen has a number in the range of 2.5 to 60.

Preferably, the screen has a number in the range of 4 to 10.

Preferably, the annular gap is 12.7 to 152.4 mm wide.

Preferably, each stage comprises a rotating semipermeable element and elements forming an annular gap and a centrifugal elimination fan positioned downstream of the semipermeable element.

Preferably, the device comprises an internal recycle device comprising means for rotating the semipermeable element at a speed sufficient to prevent part of the particles from passing therethrough.

Preferably, the apparatus further comprises an external recycle unit that includes a rotating centrifugal stripper downstream of the rotating semi-permeable member and a recycle channel that receives particles from the rotating stripper and has an outlet below at least one spin mill stage.

Preferably, the apparatus further comprises means for removing particles above the vortex grinding zone.

Preferably, the removal means include means for rotating the at least one stripping centrifugal fan by at least one spin grinding stage.

Preferably, the apparatus further comprises an assembly for pre-grinding the coarse particles to fine particles before directing the fines to the vortex grinding zone.

Preferably, the apparatus comprises a pre-milling unit including means for supplying solids to the chamber, means for forming a fluidized bed of solids in the chamber, means for directing air upwards in the chamber, and means for creating a controlled swirl in the fluidized bed for self-grinding.

Preferably, the device comprises means for externally returning the particles to the fluidized bed.

Preferably, the apparatus comprises a plurality of grinding stages and means for external recycling of the particles to the previous stage.

Preferably the removal means are removers in two vertically arranged removal stages removing particles of ever smaller dimensions.

Preferably, the means for creating a controlled vortex include rotors.

Preferably, the device comprises means for rotating the rotating semi-permeable member, the spinning disk and the rotating elimination fan on the common shaft.

The invention uses controlled swirling of a fluidized bed to grind solids into coarse and fine particles at low static pressures, and then grind and shear the particles with gas in a vertical or horizontal vortex at high jet pressures to obtain fine, very fine and superfine products. According to the invention, the dimensional sorting of the particles of the material fed into the de-agglomeration zone into fine, very fine and superfine particles is performed by subjecting the particle mix to gravity separation by means of a centrifugal fan and allowing a gas stream containing the sorted particles to enter the vertical vortex grinding zone.

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Unlike conventional mills, in the apparatus of the invention, fine particles are immediately removed by a powerful upward air stream, which makes dry grinding more efficient. According to the invention, the oversized particles are returned inside the apparatus to the coarse particle pre-grinding step by means of a semi-permeable rotating unit.

Unlike jet mills, the invention does not use pressurized gases as an energy source for grinding, which significantly reduces capital investment, energy requirements and maintenance, while increasing productivity.

The invention uses rotors that produce a controlled swirl of a fluidized bed that grinds mainly by self-hammering and abrasion, and vortex generators that include spinning semi-permeable elements that produce a vertical vortex and grind mainly by gas erosion, and spinning disks that produce a horizontal vortex and grind mainly by shear forces.

The invention can be used to micronize coal or limestone. It enables the use of cheap, finely divided materials in such applications as energy raw materials, petrochemical raw materials, environmentally safe industrial power plants and combined heat and power plants, transport of finely divided solids via pipelines, production of building materials, production of new or improved materials such as load-bearing insulators, production of ceramic materials and semiconductors, as well as metal production and metallurgy related to the preparation of ores, including precious metals.

In the following parts of the description, the wording concerning the dimensions of the products is used, defined as follows:

Product dimensions

Fat

Small

Superfine

Ultrafine

Sieve (Tyler sieve) + 270 2770 &

500 & -500 -500 to -4500 microns> 56 <= 56 <= 32 <= 32 to <5

In relation to the present application, reference is made to "microparticulate" solids, eg, microparticulate carbon and limestone. For this purpose, the term "micromolecular" is defined as solids with dimensions ranging from 7>% of the sieve class - 400 (7>% <40 micrometers).

The invention omits the costly problems of direct impact of particles on the moving internal parts of the grinding machine as in impact mills, which is associated with high energy costs and excessive wear and intensive maintenance for these devices. The invention uses the principle of fast-moving airbags where the particles are crushed by self-collision and abrasion, gas erosion and shear. The grinding mechanism according to the invention works in such a way that collisions between the solid particles and the internal mechanisms of the mill are avoided. In the process of producing a controlled vortex in a fluidized bed, the rotors in the apparatus of the invention operate in a manner similar to rotating fans, the rotor blades impinge the gas, and the gas in turn transfers the resulting kinetic energy to the rotating particles in the coarse pre-grinding zone. Thus, in order to reduce the dimensions of the abrasive elements, the invention may use cast polyurethane or polyurethane lined or coated internals while still exhibiting low wear rates. This explains the grinding efficiency, low energy requirement, low consumption and low maintenance costs of the device according to the invention.

The invention relates to a fluid energy mill, i.e. a gas such as air, carbon dioxide, nitrogen or a noble gas acts as a working fluid and transfers the energy necessary to accelerate the suspended particles to be ground. In typical fluid energy mills, such as jet mills, the velocity imparted to the particles is created by high external pressures which give the particles an initial velocity. However, such

190 297 speed drops in a short distance resulting in inefficiency and high turn rates as well as high wear rates in jet mills. In contrast, the particles supplied to the device according to the invention are continuously accelerated by the centrifugal forces and their velocity height is renewed by the air bags fed with the energy of the rapidly rotating mill rotor assemblies. The device according to the invention operates at low static pressures up to 3736 Pa (up to 381 mm of water column), but generates very high velocity pressures due to the constriction phenomena propagating in the internal units of the device. The rotational speeds of the shafts are between 3,000 and 10,000 revolutions per minute (RPM).

The rotors in the grinding chamber according to the invention are a source of centrifugal forces. The agitation of the fluidized bed of particles takes place by means of the turbulent air movement generated by the rotors in cooperation with the flow-intensifying rods placed vertically on the inner walls of the mill. The design of the rotor blades is selected to produce optimal acceleration conditions and controlled airbag turbulence. In addition, this type of design ensures minimum energy consumption and eliminates collisions between the rotor blades and the supplied particles. With fine, ultra-fine and ultra-fine particles, collisions do not occur due to the buoyancy of the boundary layer.

The distance between the impeller blades and the mill housing wall determines the width of the grinding zone of the fluidized bed. By shortening the rotor arms, the fluidized bed is widened and the efficiency of the coarse pre-grinding zone is enhanced.

The device according to the invention operates on the principle of vortex grinding with the aid of a gas acting as a working fluid. Due to the initial size reduction, it makes use of the controlled swirling of a fluidized bed where the centrifugal forces and the mixing action of the vortex are generated by the impeller assembly. The fluidized bed is assisted by a powerful upward air stream which also ensures the constant removal of fine particles. The unique internal recycle mechanism causes the coarse or oversized particles which have been blown with the fines by the ascending air stream to be recycled at low energy costs to the coarse pre-grinding zone for mixing with the incoming incoming air stream. vortex. In the grinding and super-grinding process, the invention employs two novel methods of grinding semi-permeable rotating elements by means of a vortex; and rotating discs.

In the main milling process, according to the invention, a fluidized bed with a low static pressure is used, while the auxiliary milling process takes place at high stream pressures. In this second process, the fine particles can be converted into superfine and ultrafine particles in an amount of 1/4 to 1/2 of all particles produced. Thus, the ratio of fine to superfine particles produced is 4 to 2 without significantly increasing the energy costs compared to the energy costs of the main grinding process. By changing the design of the internal equipment, the auxiliary grinding process can be eliminated. The grinding system can work with the recovery of the working fluid, which makes it safe for the environment. In addition to the ecological benefits, the grinding system according to the invention is very quiet.

The controlled vortex generation used in the invention allows for adequate heat dissipation during the fluidized bed coarse milling and precise control of the reduction process in the pre-grinding chamber. As a result, the invention overcomes the drawbacks of known mills that operate under uncontrolled eddy conditions, which lead to uncontrolled accumulation of heat, inaccurate control of the size reduction process, and undesirable changes in product parameters.

It is known to use spinning sieves for dimensional separation of solids. Centrifugal screens operate on this principle, separating the milled product of given dimensions, allowing smaller particles to pass through the mesh and removing the coarse particles remaining on them centrifugally. These screens operate at speeds of 30 to 120 revolutions per minute (RPM). In the event of increasing the rotational speed of the screen above 1200 rpm, its rotating sieve becomes clogged, which

190 297 causes the dimensional separation to stop due to the blinding of its meshes. When using a screen number 100 in the grinding system according to the invention, at a rotation speed of 1500 to 4500 rpm, the screen immediately becomes clogged with fine particles and becomes unusable. The sieve size of the solids resulting from the vortex grinding in the fluidized bed in the pre-grinding chamber and transported upwards in the ascending gas stream is from 40 to 500.

One object of the invention is to use swirling permeable assemblies that include a spinning screen assembly with large meshes that will not clog at high rotational speeds. One application of the permeable elements is to recycle coarse or oversized particles suspended in a gaseous medium. As a result, cheap recycle of oversized particles from the rapidly moving gas stream is achieved. The partitions in a fast rotating sieve number 4 to 10 act on slower moving particles like a static barrier. A rotating semipermeable element cannot distinguish particle size like a centrifugal screen, and therefore a rotating screen with screen number 4 cannot block particles with screen number 40. A rotating semi-permeable unit can only distinguish particle velocities. The particles lifted up from the fluidized bed grinding zone reach their velocity in the laminar gas stream as a function of their aerodynamic drag, whereby larger particles are slower than smaller particles. The slower moving particles, on the other hand, are less likely to strike the baffles of the high-speed spinning sieve in the spinning semi-permeable assembly and are thrown therethrough back down to the preliminary coarse grinding zone. Hence, the ratio of the speed of the rotating screen to the velocity of the particles rising in the gas stream defines those particles which are retained by the baffles of the fast rotating screen with wide meshes. By changing the speed of the rapidly rotating screen, the dimensions of the particles passing through it can be adjusted. This explains the lack of relationship between the particle size and the mesh size of the rotating screen according to the invention. The rotating semipermeable elements may block particles with sieve numbers 60 to 150 depending on the above-mentioned ratio of the speed of the rotating sieve to the speed of upward movement of the particles. In turn, the speed of the particle depends on the speed of the ascending gas stream and the size of the particle from which the aerodynamic drag results.

The above phenomenon of "statistical rejection" of particles by the large-mesh high-speed spinning screen system due to the variation in velocity that underlies the internal recycle of larger or oversized particles to the pre-grinding zone according to the invention is limited to systems containing rapidly suspended solids. a moving stream of gas. This phenomenon does not occur in denser media, i.e. in fluids such as water. The semipermeable members of the invention are effective at rotation speeds in the range of 1500 to 10,000 rpm, and preferably in the range of 3000 to 4500 rpm. The semi-permeable elements according to the invention effectively overcome the difficulties of the prior art screens which clog up and become unusable during high-speed centrifugation.

The particles discharged from the coarse pre-grinding chamber are sized in the sieve size range from 150 to 500 or smaller, so that with such small sizes the drag forces drop sharply. As a result, speed sorting by means of the rotating semi-permeable elements becomes negligible for smaller particles, which predominate outside the coarse pre-grinding chamber.

The purpose of the further use of the permeable elements outside the coarse pre-milling chamber is to grind the fine particles by creating a vertically directed vortex. This makes it possible to cheaply grind the particles to a superfine and ultrafine state. High velocity gas flowing through the rotating semi-permeable element is divided into streams by screens with wide meshes; these jets are twisted as a result of the fast-spinning moment of the screen, creating a vertical spiral vortex. In this vertical vortex, the particles are disintegrated by the action of gas erosion. The effectiveness of this comminution depends on the gas velocity in the milling zone

190 297 vortex, which determines the residence time of the particle in the vortex, and the spin speed of the semipermeable element, which determines the moment of turbulence acting on the gas jets forming the vortex.

Outside the coarse particle pre-grinding chamber, the sole task of the rotating semipermeable element is to efficiently produce a vortex. Only of a kind according to the invention, the vortex generators are located in the sorting chambers, where the gravitational separation of the coarse particles in the ascending gas stream takes place by means of centrifugal fans. The sorted particles remaining in the upwardly flowing gas stream are crushed by the vortex produced by the semi-permeable elements. By repeating this process in steps, each of which includes gravity separation and vortex milling, fine to ultrafine particles can be reduced. The milling of fine to superfine and ultrafine particles with the gas vortices produced by a rotating sieve is unexpected and occurs with very little energy consumption. It is recommended to use steel sieves with mesh numbers 2.5 to 60, preferably in the range from 4 to 10. The optimal size of the mesh of the rotating sieve and the rotational speed must be selected experimentally. Generation of a vortex by a rotating semipermeable element can only take place in the gaseous medium. In denser media, such as fluids such as water, the vortices produced by the rotating sieves are localized and damped by the action of friction.

Another task of the rotating semi-permeable element is to effectively eliminate solids from a high-velocity gas stream of high temperature and pressure, with negligible pressure losses and temperature drops. A semi-permeable element for this purpose has a rotating screen with a mesh size ranging from 2.5 to 60, preferably in the range 4 to 10, and is made of a metal or alloy such as tungsten or steel suitable for use at temperatures and speeds. the rotary ones that act on it. The ratio of the velocity of the rotating screen to the velocity of the pressurized gas stream should be determined in such a way as to obtain a suitable variation in the velocity of the suspended solids at which the rotating semi-permeable element obstructs them. Further purification of the gas stream by gravity separation by means of a centrifugal fan takes place after the gas stream passes through the rotating semi-permeable element.

According to the invention, an annular gap delimited by a stationary circular bore and a circular rotating disk disposed therein is provided for grinding fine particles in the annular gap due to the production of a horizontally directed vortex by the rotating disk. The width of the annular gap is 12.7 to 152.4 mm, preferably about 76.2 mm, and the height is 12.7 to 152.4 mm. The effectiveness of grinding in the annular gap depends on the residence time of the fine particles and the prevailing shear forces. Hence, the effectiveness of the annular gap results from the velocity of the ascending gas stream and the velocity of the rotating disk. The reduction in dimensions in the annular gap occurs with very little energy consumption.

In common spinning wheel applications to control the size of the particles entering the de-agglomeration zone, the annular gap width (when used for producing fine and superfine particles) should be in the range of 3.175 to 5.08 mm. With such a small annular gap width, the vortex generation becomes unusable for particle size reduction through shear and the energy consumption could be too high. However, exceptionally, in the method according to the invention, the vortex generator with the annular gap is placed in a sorting chamber, where the smaller-sized particles flowing out of the horizontal vortex of the annular gap are dimensionally separated in the gravitational field generated by the centrifugal fan.

For the production of the superfine and ultrafine particles according to the invention, vortex generators are used, which include a rotating semi-permeable element and an annular gap inside the sorting chamber, where said additional grinding takes place with lower energy consumption and lower maintenance costs.

As a result, the invention eliminates the disadvantages of previously known devices in which abrasive mills are used to produce superfine and ultrafine particles,

190 297 and the milling process takes place in the pre-grinding chamber by uncontrolled vortex formation in the narrow space between the rotors and the housing wall, and by producing interscapular and inter-plate vortices (intensified in some cases by the generation of ultrasonic waves). All the hitherto used vortex and acoustic assist processes are processes of low efficiency in the production of fine particles, they consume a lot of energy and are associated with high maintenance costs.

Another task is to use the inherent grinding medium and / or shear or gaseous erosion devices of the solid particles suspended in the gaseous working fluid to immediately modify the active surfaces of said freshly ground particles with organic or inorganic reagents. The surface reactivity of the freshly ground particles and their modification with chemicals are well known, but the modification processes in prior art grinding plants, for example in abrasive impact mills or jet mills, have been uncontrolled. Hence, the economics of the surface modification process is not favorable due to the excessive consumption of reagents and the resulting limitations in controlling the properties of the end products. In the grinding plant according to the invention, it is possible to closely control the production of fresh surfaces by shearing in the annular gap, and to modify the desired surface portions with economical use of chemicals in order to give the modified product the desired surface properties.

Yet another aspect of the invention is the use of vortex generators combining a spinning semi-permeable element composed of an assembly comprising a rotating screen with an annular gap formed by a rotating disk in a circular stationary bore for grinding solids into superfine and ultrafine particles with low energy consumption. Only of a kind, such a combination of vortex generators is used in the device according to the invention inside a sorting chamber in which the particles of given dimensions flowing out of the horizontal vortex in the annular gap are gravity-sorted by means of a centrifugal fan, before the purified gas stream with reduced particles flows in. desired dimensions to the vertical vortex zone produced by the spinning semi-permeable element. The repeated use of such combinations in a vertical stack of sorting chambers results in the production of ultrafine products. The oversized particles eliminated in a given sorting chamber are returned externally to the previous sorting chamber in the vertical stack to further reduce the size by vortex milling.

According to the invention, a grinding system consisting of a chamber with impellers for pre-grinding coarse particles and for grinding fine solids in a fluidized bed milling zone with a controlled vortex with an additional grinding zone in which the abovementioned solids are ground into superfine and ultrafine particles with generators eddies containing rotating semi-permeable elements and an annular gap, where a split drive is provided allowing the screen and disk to spin very quickly with low energy consumption. The split drive screen is capable of spinning at more than 10,000 rpm and the rotor assembly is rotating less than 3200 rpm, with the installation still maintaining the characteristics such as low energy and component consumption. In order to obtain an internal recycle function inside the coarse pre-grinding chamber including sorting the particles by varying their individual velocities in the ascending gas stream, the spinning semipermeable element must be at a speed of less than 4500 rpm.

Yet another aspect is a system where the rotor assembly is covered with rubber, polyurethane or other plastic materials, or the rotor assembly is made by casting these parts from such materials. Alternatively, the rotor assembly may be coated with ceramics (e.g., chromium carbide, tungsten carbide) or alumina.

190 297

Another aspect is the system, the walls of which, as well as the rotating sieve and disc, are covered with rubber, polyurethane, other plastic materials, ceramics or aluminum oxide.

These and other tasks and advantages of the invention are achieved in accordance with the invention by a method of dry grinding solids, which consists in directing the fine solids essentially upwards into the vortex grinding zone and grinding the upwardly directed fine particles by vortex generators arranged in the vortex grinding zone. by passing a portion of the particles through a vortex milling zone, the vortex milling zone comprising at least one vertically sequential milling stage in which the particles are passed upward through at least one swirling semi-permeable element and an annular gap defined by a stationary plate with a round hole in it and a rotating circular disc situated in the round hole.

The step of passing the particles upward through said rotating semipermeable element comprises passing the particles through a rapidly rotating screen. The screen is not less than 2.5, and preferably its number is from 2.5 to 60, and most preferably it has a mesh size in the range of 4 to 10 and is spun at a speed in the range of 1500 to 10,000 rpm. and most preferably in the range from 3,000 to 4,500 rpm.

The step of passing the particles through the annular gap comprises passing the particles through an annular gap having a width of 12.7 to 152.4 mm, preferably about 76.2 mm, and a height ranging from 12.7 to 152.4 mm.

Preferably, in each step the particles are passed through the rotating semipermeable body and then through the annular gap. For the dimensional sorting of the particles flowing out of the annular gap, the upward gas stream with the mixture suspended therein is subjected to gravity sorting by means of a centrifugal fan, and the upward flow of gas, with the dimensionally sorted particles, is introduced into a spinning grinding zone containing a vertical vortex. semi-permeable element.

In a coarse pre-grinding chamber according to the method of the invention, the particles are internally recycled by spinning said semi-permeable body at a speed sufficient to prevent some of the oversized particles from passing therethrough. Further, the method recycle the particles externally by means of a centrifugal fan rotating downstream of the rotating semipermeable member and a recycle channel is provided to receive the particles from the rotating fan and having an outlet below at least one vortex grinding stage.

In addition, the method includes a particle removal step above the vortex grinding zone. In the removal step, at least one centrifugal fan downstream of the at least one vortex grinding stage is rotated.

In one embodiment, the method also comprises the step of pre-grinding the coarse particles to fine particles prior to directing the fines to a grinding zone containing vortex generators. In the pre-milling step, a solid is fed into the chamber, a fluidized bed is formed from the solid in the chamber by directing air upwards in the chamber and creating a controlled vortex in the fluidized bed for self-grinding. The particles are recirculated externally to the fluidized bed as part of the external recycle step.

The method may include multiple grinding stages with vortex generators and with external recycle of the oversized particles to the previous stage. Preferably, the separation and removal step removes the particles in two vertically arranged removal stages to separate and remove particles of progressively smaller dimensions.

In another embodiment, a controlled vortex by means of impellers is created as part of the coarse pre-grinding step.

Vortex generators comprising a rotating semipermeable element and a rotating disk can rotate on a common shaft.

The milling step may be performed in an inactive gas atmosphere in the presence of a chemical reagent to effect controlled modification of the surface of the solids.

190 297

The invention also relates to an apparatus for dry grinding solids comprising means for creating a vortex grinding zone with vortex generators, including at least one vertically arranged vortex grinding stage for grinding fine solids, and means for directing the fine solids approximately up into the zone. spin grinding. The at least one vortex grinding stage includes vortex generators comprising at least one rotating semi-permeable element and annular gap forming elements comprising a stationary circular bore plate and a rotating circular disc positioned in the circular bore, and wherein the rotating semi-permeable element and annular fracture are configured to that they pass a portion of the upwardly directed reduced particles through them and have a particle size sorter for products flowing out of the horizontal vortex zone of the annular gap, the oversized particles being separated by gravity by means of a centrifugal fan.

Preferably, the rotating semipermeable element comprises a rotating screen with mesh numbers not greater than 2.5, preferably numbers in the range from 2.5 to 60, and preferably numbers in the range of 4 to 10. The width of the annular gap is from 12. 7 to 152.4 mm, preferably about 76.2 mm, and a height from 12.7 to 152.4 mm. Both of these vortex generators are used to effectively mill fine particles in a vertically flowing gas stream and to reduce these particles to superfine and ultrafine products.

In one embodiment, each stage includes a rotating semipermeable element and elements forming an annular gap downstream of the rotating semipermeable element and having a gravity sorter of oversized particles in the vertically flowing gas stream containing a centrifugal fan.

In another embodiment, the apparatus comprises an internal recycle device for coarse particles in the pre-grinding chamber comprising means for rotating the rotating semi-permeable body at a speed sufficient to prevent part of the particles from passing therethrough, such part containing the slower velocity particles present in the pre-grinding chamber. in an upward flow of gas. The apparatus also includes an external recycle assembly including a rotary centrifugal fan positioned downstream of the spinning semi-permeable member in the coarse pre-grinding chamber, and a recycle channel for particles received from the spinning fan having an outlet below at least one vortex grinding stage.

The device also includes particle removal means located above the coarse pre-grinding zone. In one embodiment, the removal means include means for rotating at least one centrifugal fan located downstream of the at least one grinding stage.

In a further embodiment, the apparatus comprises a unit for pre-grinding the coarse particles to fine particles before they are directed to the grinding zone containing the vortex generators. The pre-grinding unit preferably comprises means for feeding solids into the chamber, means for forming a fluidized bed of solids in the chamber, including means for directing air upwards in the chamber, and means for creating a controlled swirl in the fluidized bed for automatic operation. grinding. The elements for external recycle of the particles are means for the external recycle of the particles to the fluidized bed.

In a further embodiment, the apparatus comprises a plurality of grinding stages, each with vortex generators and means for gravity separation and external recycling of oversized particles to the previous stage.

The removal means are preferably removers in two vertically arranged removal stages for separating and removing particles of ever smaller dimensions. The pre-grinding elements include rotors for producing a controlled vortex.

The vortex generators comprise rotating semipermeable elements and a rotating disc, preferably rotating on a common shaft.

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In yet another embodiment of the invention, the method and apparatus for dry grinding solids comprises means for feeding solids into the chamber, means for forming a fluidized bed of solids in the chamber by directing air upwards in the chamber, and means for creating controlled vortices in the bed. fluid bed for self-grinding. Preferably, the apparatus in this embodiment comprises means for separating and removing particles downstream of the fluidized bed and preferably means for returning the removed particles to the fluidized bed.

When removing particles, preferably at least one centrifugal fan is rotated downstream of the fluidized bed, while during recycling, preferably, a centrifugal fan is rotated downstream of the fluidized bed and a return passage is provided to receive particles from the rotating fan and having an outlet to the fluidized bed. The particles may be removed in two vertically arranged removal stages to separate and remove particles having progressively smaller dimensions.

Preferably, rotating rotors are used to produce a controlled swirl, while grinding may take place in an inactive gas atmosphere in the presence of a chemical reagent to effect controlled surface modification of the solids.

Another embodiment of the invention relates to a method and apparatus for removing solid particles from a gas stream, comprising rotating at least one rotating semi-permeable member, directing at least one rotating semi-permeable member gas stream through the at least one rotating semi-permeable member, and removing non-flowing particles therethrough. one rotating semipermeable element and removing particles flowing through the rotating fan behind the rotating semipermeable element.

The at least one rotating semi-permeable element preferably comprises a rotating screen unit, preferably a screen with no more than 2.5 meshes, more preferably a screen with no more than 2.5 to 60 meshes, and most preferably with a screen with meshes no larger than a number in the range of 4 to 10.

The subject matter of the invention is explained in the examples of the drawing in which Fig. 1 shows a dry grinding device according to the invention for carrying out the dry grinding method of the invention according to the invention, schematically, Fig. 2 - the apparatus of Fig. 1 using grinding fluid energy, cross-section, schematically, fig. 3 - modified device according to the invention using fluid energies for grinding, in cross-section, schematically, fig. 4 - device according to the invention for producing ultrafine particles with the help of fluid energy, in cross-section, schematically Figs. 5A and 5B are a top plan view and sectional view of the centrifugal ascending fan of Figs. 6A and 6B - two different coaxial impellers used in the apparatus of Fig. 2 in a top view of Figs. 7A and 7B. - the rotating semi-permeable element of Fig. 2, top and side view, Figs. 8A and 8B - the rotating disk of Fig. 2, top and side view, Figs. 9A and 9B - the rotating plate of Fig. 2; in top and side views, Fig. 10 shows the inner bearing assembly of the device of Fig. 2, and Fig. 11, the flow-enhancing rods of the device of Fig. 2, in a top view.

As can be seen in Fig. 1, the grinding unit 10 comprises a lower coarse and fine grinding zone in the form of a chamber 11, into which the solid material is fed through the feed inlet 14, and into which gas, e.g. air, is introduced from below through the inlet 15. The particles from the lower zone in the form of chamber 11 are led by a gas stream into the intermediate vortex grinding zone 12 for further milling. In the intermediate zone 12 there are two recycle channels 18, 19 intended to recycle the oversized particles to the lower zone in the form of a chamber 11. The particles ground in the intermediate zone 12 are fed by a gas stream to the upper separation zone 13 with the element 13 to particle removal. The upper separation zone functions to separate the end product (such as superfine particles) which exit via line 16 to cyclone 30 where the superfine product is separated. The fines are fed from the upper zone with the particle removal means 13 through the outlet line 17 to the cyclone 20 to isolate the fines.

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The cyclone 20 passes the recycle gas via line 23 to the bottom of chamber 11 and carries the particles via line 24 to the fine particle drum 21. The cyclone 30 recycles its gas through line 22 to the bottom of the lower chamber 11. The superfine particles flow through line 33 to the product drum 31. Alternatively, the cyclone 30 may pass some or all of the carrier gas through outlet conduit 40 to a collective bag filter.

Figure 2 shows the grinding assembly 10 of fig. 1 in detail. As can be seen, the grinding assembly includes an internal shaft> 1 driven by a motor> 2 and embedded in a bearing> 3; this shaft drives all internal components> 4-68 of the grinding unit. A shaft> 1 with a motor> 2 is the means for rotating at least the semi-permeable member 60, and is also the means for rotating one centrifugal fan 68. In order to stabilize the rotating shaft against vibration, the device is provided with one or more internal bearings as shown in Fig. 10, the bearings 7> being mounted by steel arms 76 in the outer wall of the mill. For speeds above 4000 rpm, a hollow shaft can be used to prevent runout. The device can be equipped with a split shaft, the shaft part located in the lower chamber 11 containing the rotors, running at a slower rotational speed, while the remaining rotating elements are mounted on a shaft with a higher rotational speed.

In the lower chamber 11 there is a rotating plate> 4 positioned below the upward air directing means in the form of an internal rising fan >>. The> 4 plate protects the fan from turbulence caused by the recovered gas streams flowing in through the inlet conduits 22 and 23. The riser fan >> works to provide an ascending air flow through the grinding assembly.

The riser fan >> is shown in detail in Fig.> A and> B. As can be seen from these, the fan consists of a hub >> A and a plurality of blades >> B, each twisted at an angle of about 1> °, alternating both above and below the hub to produce a lift when spinning.

Above the fan >> there are four rows of elements for creating a controlled vortex in the form of transversely staggered coaxial twin impellers> 6-> 9. Preferably, the rotors have arms of flat bars or round bars mounted on a spline on a shaft and with coaxial blades mounted at each end. The rotor blades are shown in detail in Figures 6A and 6B.

Figure 6A shows a flat bar arm rotor having a flat plate> 61 with> 62 and> 63 rotor blades mounted at its ends. The rotor blades are positioned at a twist angle of approximately 70 ° to the horizontal plane of the plate> 61. Fig. 6B shows a round blade rotor which includes a> 64 round blade with> 6> and> 66 rotor blades at its end set at an angle of twist of about 70 ° to the> 64 blade.

The fan >> produces a circumferential air curtain assisted by an apron (not shown) attached to the lower end of the flow-intensifying rods 77 &apos; that are attached to wall 78 as shown in Figure 11. Wall 78 can be covered with rubber or polyurethane and are therein. embedded flow enhancement rods 77 preferably 76.2mm to 177.8mm spaced along the wall. The rotor blades mix the fluidized bed produced by the fan >>. The rotor blades may have different torsion or twisting angles with respect to the horizontal plane, different pitch angles, i.e. they may deviate from the vertical plane, or they may have yaw angles with respect to the rotor arms. Furthermore, the rotors may also be provided with deflectors (not shown) to increase the turbulence of the vortex or to enlarge the grinding zones by deflecting air flows.

Above the impeller> 9, at the start of the intermediate vortex zone 12, there is a swirling semi-permeable element 60 which facilitates the internal recycle of coarse or oversized particles into the pre-grinding chamber 11 and also supports fine and super fine grinding by creating a vertical vortex acting on the particles in an upward direction inside the intermediate zone 12. The structure of the rotating semipermeable element 60 is shown in Figures 7A and 7B.

As can be seen from these figures, the rotating semi-permeable member 60 has a frame 60A including a hub 60B mounted on a spline on a shaft> 1. On the bottom of the support plate

190 297 of the 60A frame there is a 60C screen. The screen may have mesh numbers ranging from 2.5 to 60, preferably from 4 to 10. Preferably, the screen is made of steel. There is a deflector 60D below the screen to prevent particles from passing through the center of the rotating screen 60C. The diameter of the deflector disk may vary from 101.6 mm to 254 mm depending on the desired amount and degree of fineness of the particles passing through it.

The particles flowing through the rotating semipermeable element 60 must then pass through the annular gap 70B between the stationary plate 70 and the rotating disk 61 located in the opening 70A of the stationary plate 70. Figures 8A and 8B show in more detail the position of the rotating disk in the central opening of the stationary plate between which an annular gap 70B is formed. The width of the annular gap 70B is 12.7 mm to 152.4 mm, preferably about 6.2 mm, and the height is 12.7 mm to 152.4 mm. The distance between the semipermeable element 60 and the plate 70 is preferably greater than 50.8 mm. Preferably, the rotating disc 61 and the stationary plate 70 are in the same plane, but the plane of the disc 61 is allowed to lie up to about 25.4 mm above or below the plane of the plate 70. Preferably, the rotating disc and the stationary plate are made of steel.

In the intermediate zone 12 is a centrifugal fan 62 which extracts coarse or oversize particles passing through the rotating semi-permeable element 60 and the annular gap 70B between the rotating disk 61 and the stationary plate 70. These coarse or oversized particles are recycled through channels 18 and 19 to pre-grinding chambers 11.

Above the fan 62 is a rotating semi-permeable member 63 which has the same structure as the rotating semi-permeable member 60. The rotating semi-permeable member 63, which only serves to create a vortex, no longer removes or recycle particles which have become small. Above the element 63 is a stationary plate 71 with a rotating disc 64 positioned in the opening 71A and forming the annular gap 7IB. These elements have the same structure as the stationary plate 70 and the rotating disc 61.

Above the rotating disc 64 is a centrifugal fan 65 which ejects fine particles through the exhaust conduit 17. Above the centrifugal fan 65 is a spinning plate 66 which has the same structure as the spinning plate 54 and is shown in detail in Figures 9A and 9B. As can be seen from these figures, the rotating plate 66 has a hub 661 which is seated on a spline on shaft 51 so as to rotate with it. The task of the plate 66 is to reduce the upward turbulence inside the zone with the particle removal members 13 and to assist in the dimensional separation by the fans 65 and 68 through the receiving exhaust lines 17 and 16. In case a more accurate dimensional sorting of fine and superfine particles is desired, the exhaust lines 17 and 16 can be connected to a dust classifier.

Above the rotating plate 66 is a stationary plate 72 with the rotating disk 67 rotating in a central hole 72A and forming an annular gap 72B. Its structure is the same as the aforementioned stationary plates with a rotating disc.

Above the rotating disc 67 is a centrifugal fan 68 which ejects the superfine particles through the exhaust conduit 16.

The lower chamber 11 may operate as a closed atmosphere system; in this case, inlet 15 and outlet conduit 40 are closed. If a wet substance is to be supplied, an air dryer is connected to the inlet 15, which dries the feed substance to a moisture content of less than 4% while grinding. In order to remove the water vapor generated during such drying, appropriate measures must be taken to form outlets at the outlet of the cyclones, these outlets being located at the inlets of lines 22 and 23. The lines 22 and 23 shown in Fig. 1 serve to transport the gas recovered from the cyclones.

The influencing particles supplied to the inlet 14 are forced into the periphery by the action of the air bags generated by the rotors 56-59 and there they form a fluidized bed in the form of particles suspended by the continuously acting upward forces of the gas stream generated by the fan 55.

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The height of the velocity of the particles colliding with each other in the circular fluidized bed is produced by the centrifugal forces of the rotors 56-59 and transmitted by the gaseous working fluid. This speed height is renewed with each revolution of the rotors which are attached to the rotating shaft 51. The mixing and control of the fluidized bed is accomplished by the rotating blades of the rotor and by selecting their twist and pitch angles. The mixed fluidized bed is modulated by flow-enhancing rods mounted vertically in the inner wall of the grinding assembly, which force the particles to flow into "closed pockets" and exert "venturi pumping" on them due to pressure fluctuations in the stream.

The particles are ejected from the circular fluidized bed through a fixed upward air curtain created by the fan 55 and assisted by the spiral ascension of gaseous working fluid produced by the cross shifting of the rotor pairs 56-59.

In terms of the forces exerted on the particles in the lower zone, the centrifugal forces generated by the spinning rotors act more intensively on the larger particles and force them out to the outer periphery, while the aerodynamic drag forces keep the particles suspended in the vortex zone, provided it is kept constant. the speed of the rising currents. After the particles are reduced in size as a result of spontaneous collision, friction, shear or erosion, they reach a smaller size range, which results in a decrease in the intensity of the centrifugal forces. In this way they move towards the inner circumference of the vortex. After the particle size is reduced, the aerodynamic drag is reduced to the point where the flow dynamics of the ascending jet entrain and transport such smaller particles towards the rotating semipermeable body 60.

The rotating semipermeable element functions to enhance the more efficient internal recycle of oversized particles by "statistical removal". In addition, it disturbs the flowing gas stream by splitting it into streams and twisting them, resulting in vertically directed vortex forces which create additional fine particles, mainly due to gas erosion and shear. At higher shaft speeds, the efficiency of the rotating semi-permeable element in grinding the substance into fine particles increases significantly.

The rotating discs 61, 64 and 67 disposed in the central openings 70A, 71A and 72A of the stationary plates 70, 71, 72 cause throat phenomena and high flow pressures. Thus, the grinding of substances into superfine particles is mainly due to the intensification of the circular shear forces of the vortex acting on the fine particles.

For a given feed capacity and rotor speed, there exists, for a swirling fluidized bed, a maximum density of particles therein at which the effects of the vortex energy used to comminute such suspended particles are maximum. With the invention, it is possible to achieve this maximum density value and to maintain an optimal controlled spin effect by adjusting the internal density and process variables. As a result, thanks to the controlled swirling of the fluidized bed, the invention provides the most efficient transfer of the input energy via the gaseous working fluid to the actual grinding of the incoming particles.

In order to improve the technical performance of existing grinding plants using ball mills, spring ring mills, roller mills or other percussion devices, and to enable, at low cost, an intensification of grinding into fine and superfine particles, a fluid powered device can be used as shown in Fig. 3. In this figure, like elements are denoted with the same numerals. This device differs from the device of Fig. 2 in that the lower zone is mainly used for batch preparation and has only two rotors, while the external regenerative product recycling takes place from the intermediate grinding zone through channels 18 'and 19' back to the bed. fluidized bed to obtain the final product in the form of the desired fine and superfine particles. In this fluid energy device, the rotating semipermeable member 73 of Fig. 3 is used as a vortex generator instead of the plate 66 of Fig. 2. As with the embodiment of Fig. 2, this device uses the rotating semipermeable member 60 for the most efficient internal recycle. for circulation of overweight products18

190 297 grooves in the coarse particle pre-grinding chamber and the rotating semipermeable elements 63 and 73 and the spinning discs 61, 64 and 67 as vortex generators for intensifying the grinding of substances into fine and superfine particles. Grinding to superfine particles in a fluid energy device can be suppressed or enhanced by selecting inserts and internal mill adjustments.

As part of the modernization, a fluid energy device could receive end products from existing grinding plants and use them as material for further processing.

The device for the production of ultrafine particles shown in Fig. 4 is intended to be a cheap and effective ultrafine particle mill, which uses the grinding capabilities of vortex generators with spinning semi-permeable elements (80, 82, 86, 89, 91 and 95) and spinning discs (84). , 87, 90, 93, 96 and 99) for more intensive production of fine, superfine and ultrafine particles. The effectiveness of such a solution results from the use of stages in which the subsequent recycling of oversized products in each stage is carried out by gravity separation by means of centrifugal fans (81, 85, 88, 91 and 94) and transport of the ejected oversized products to the next lower stage through the channels (110A-114A and 110B-114B) of recycling, which enhances the operation of the ascending vortex generators with spinning semi-permeable elements and spinning discs arranged in a vertical stack. Outside the coarse particle pre-milling chamber 11, the size of the solid particles in the upward flowing gas stream is sufficiently reduced and any internal recycle by the rotating semi-permeable elements becomes negligible. Consequently, in the ascending steps of the ultra-comminution device, the rotating semi-permeable elements function solely as vortex generators.

An unexpected effect is to intensify the reduction of the particle size to superfine by the use of steps and subsequent recycle with low energy consumption.

The apparatus of Fig. 4 for producing ultrafine particles is a low pressure particle size reduction apparatus that operates at high shaft speeds and low energy consumption. The ultra-grinding device produces high flow pressures at low static pressures, thereby effectively reducing the 270 mesh (56 micron) feed material to the desired end product 4500 mesh (5 micron) or even finer.

In Figure 4, like numbers refer to like elements. Above the rotors 58 and 59 is a rotating semi-permeable member 80, followed by a stationary plate 101. Behind these assemblies is a series of five stages with centrifugal fans 81, 85, 88, 91 and 94, rotating semi-permeable members 82, 86, 89, 92 and 95, the stationary plates 102-106 and the rotating discs 84, 87, 90, 93 and 96 forming annular gaps 102B-106B. These stages include recycle channels 110A-114A and 110B-114B. At the top are superfine and ultrafine particle separators including fans 91 and 100, a spinning plate 98, a spinning disk 99, and a stationary plate 107 forming the annular gap 107B. Fans 97 and 100 pump the particles into exhaust ducts 17 and 16. ...

The lower zone serves as an inlet in which the feed material flowing through the inlet 14 is suspended by the uplift forces generated by the centrifugal fan 55 'and the vortices generated by the cross-arranged rotors 58-59. As a result, the particles are acted upon by a vortex generated by the rotating semipermeable element 80 forcing them to a series of degrees. In addition to the gas inlet at the bottom of the feed inlet chamber, there are also inlet conduits 22-23 that recycle gas from the cyclones (after passing, if necessary, through a booster box, not shown, to be pasteurized).

The intermediate zone for ultra-fine and ultra-fine grinding is divided into five steps. In each of these stages, the incoming particles are successively acted upon by vortex generators comprising rotating semi-permeable elements and rotating discs arranged in an ascending arrangement. Each stage includes an associated centrifugal fan to remove the oversized product after it exits the horizontal vortex

190 297 of the annular gap through the recycle exhaust channels to the next lower stage. Thanks to this solution, gravity sorting of the solid fractions takes place and the limitation of the size of the particles that flow into the next vortex grinding zone with a vertical vortex generator containing a rotating semi-permeable element.

The upper zone is for classification and includes centrifugal fans 97 and 100 which eject the end products through the exhaust conduits 17 and 16 to the respective cyclones. If a finer particle size separation is required, the products from the exhaust conduits 17 and 16 can be led to a dust classifier.

The ultra-shredding device can be 61 cm in diameter and 213.5 cm high, with a variable power drive, allowing for rotational speeds from 3000 to 500 rpm. The inserts for this device can be seated on the splines inside the hollow shaft 51. The walls of the device can be rubber lined and circumferentially spaced 76.2 mm to 177.8 mm with flow-intensifying rods.

The fluid energy grinding device shown in Fig. 2 has inherent versatility in operation when it is required to separate particles of a feed material in the form of coarse concentrates. In that case, its activity in terms of vortex production and recycling must be limited. To this end, the rotating plate 66 (Fig. 9A) is positioned directly over the rotating semi-permeable member 60 (Fig. 2), limiting its activity to internal recycling to the lower coarse pre-grinding zone, while removing the spinning disks 61 and 64. , together with the rotating semi-permeable element 63 and centrifugal fan 62 limit the capacity or close the recycle channels 18 and 19 and increase the gas supply to the mill through the inlet 15. Coarse concentrates exit through the exhaust duct 17, while the fines are ejected through the exhaust duct 16.

In the ultrafine particle obtaining device, the smallest particles flow upwards in a stream at relatively low static pressures up to 3736 Pa (up to 381 mm of water column) and are acted upon by very fast, vertically directed spiral cyclones produced by a spinning semi-permeable element and flowing transversely through the upper circular shear zones produced in annular gaps. Particle size reduction is accomplished by shear and gas erosion. The centrifugal fan found in each stage provides gravity separation and helps to recycle the oversized particles to the next lower stage to further reduce their size. As a result, in each subsequent step, the smaller sized particles are separated, facilitated by the vortex grinding zones produced by the spinning semi-permeable elements and the spinning discs and located higher up in the ultra-refining device.

It is possible to enlarge the ultra-grinding device by increasing the diameters of individual stages. The efficiency of the device can also be increased by increasing the number of its ascents.

Due to the finer feed material and the use of impellers mainly for mixing the feed material, the ultra-comminution device of Fig. 4 can operate at much higher shaft speeds than the fluid energy device of Fig. 2, which increases its efficiency while maintaining low energy consumption.

Typically, the feed material for the fine milling process is 12.7mm to 3.175mm particulate material, which is obtained at lower cost with a variety of crushers. Fine particle mills are generally air mills equipped with sorting plants that return oversized particle fractions to the milling circuit for further processing into finer particles. This task is fulfilled by a variety of impact mills - a ball mill, a ball mill, a hammer mill, a ring-spring mill, a roller mill and other impact pulverizers. The main grinding process in all types of these devices is based on the physical impact of the impactors on the supplied particles.

The utility and advantages of impact mills are well known; these are devices with high efficiency and effectiveness in reducing particle size. Their disadvantages are also well known - high wear, high energy costs and low efficiency in the case of fine grinding. Attempts to extend the useful scope are well documented

190,297 impact mills by creating vortices in them. Rotating hammers with radial beating plates and covering discs are used in spin-percussion mills or percussion mills. Grinding takes place due to the direct mechanical impact of the particles on the beating plates and the abrasion of the particles as a result of collisions with the surfaces of the device. The value of secondary spinning effects is well known - abrasion due to collision of particles with each other, erosion and shear by gases flowing in the vortex at very high velocity. The uncontrolled vortex zones produced in impact mills are located in narrow spaces between the impeller and the housing wall, in the areas between the blades, or between the plates within the impeller assembly. Vortex generation can be intensified by creasing the wall of the housing and assisted by ultrasonic vibrations produced by attached vibrating blades or vibrating discs. The disadvantages of vortex percussion mills are high energy consumption, excessive wear of components, intense heat generation, low efficiency and relatively low efficiency of fine particle production. As a result, they are difficult to expand into large workgroups.

The structure of the apparatus according to the invention shown in Fig. 2 does not suffer from these drawbacks due to the use of a controlled swirl of a fluidized bed for the main reduction in size, situated on the periphery of the mill, in which the vortex of particles impinging against each other, being forced out by the centrifugal forces generated by the rotors and effectively carried by the gas working fluid. The width of the fluidized bed can be increased by retracting the rotor blades (shortening the rotor arms) and increasing the spin speed and the speed of the ascending jet accordingly. Abrasion occurs due to spontaneous collisions of particles at appropriate angles to minimize the effect of abrasion at high shear rates. The efficiency of coarse and fine grinding is due to the very high efficiency of internal recycling of oversized particles to the pre-grinding chamber 11 (Fig. 1) thanks to the use of the speed-sorting effect of the rotating semi-permeable element, as a result of which particles moving more slowly, mostly of larger dimensions, are removed floating upwards in the gas stream. Contrary to prior art devices, most of the fine and superfine grinding does not take place in the main grinding zone. In the present invention, most of the milling into fine and superfine particles takes place in the vortex grinding zones where the rotating semi-permeable elements and the spinning discs act as vortex generators and intensify the milling of substances into fine particles, superfine and ultrafine particles by gas erosion and shear at high flow pressures. As a result, the invention is characterized by low energy consumption, minimal mechanical wear and minimal heat accumulation, and is characterized by a very efficient production of fine and superfine particles.

The ultrafine particle maker shown in Fig. 4 provides low-cost ultrafine milling due to its design that uses vertical helical cyclones to erode the particles in a gaseous manner in combination with horizontal circular shear zones where the particles are sheared at high flow pressures and low. static pressures. This vortex generation system uses swirling semipermeable elements to create a vertical helical vortex zone and swirling disks to create a horizontal vortex zone, both of these vortex generators acting as effective particle size reduction devices for vertically displacing fine particles in the gas stream and therein. shredding with low energy consumption. In each stage, after the particles have flowed through the horizontal vortex zone, the oversized particles are separated by gravity separation by means of a centrifugal fan. The eliminated oversized particles are recirculated internally to the next lower vortex grinding zone to further reduce their size. The fine particles which remain by gravity sorting in the vertically flowing gas stream flow to the next vortex grinding zone to further reduce the size, and thus the grinding effect is magnified in the successive steps of ascending the devices by platforming. The ultra-grinding device provides ultra-grinding with low mechanical wear, low energy consumption and low capital expenditure.

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Coarse limestone has long been the main industrial product used in construction, cement making and agriculture, and finely ground limestone has been used in animal feed and water treatment plants. Ultrafine limestone is an expensive product used as a paper sizing agent, pigment, industrial admixture component, and in environmental purification.

Inexpensive super-fine and ultra-fine matte would be a very valuable material in flue gas desulphurization processes and would facilitate the use of cheap high-sulfur coal with high caloric values. Microparticulate limestone is a valuable dopant material for coal fuels. Super-fragmented dolomites and magnesites are valuable desulphurization additives for various fuel oils, heavy crude oil or petroleum coke.

The invention, when used in the production of microparticulate carbon or limestone, enables the removal of SO2 and nitrogen oxides at low cost.

In the present arrangement, microparticulate carbon and limestone can be introduced together through the burner nozzles into the combustion chamber. In the case of particles of this size, combustion is instantaneous, proceeding at a similar rate as in the case of supplying oil and natural gas to the burners. A prerequisite for allowing SO2 to complete the reaction with limestone may be the recirculation of the exhaust gases around the boiler tubes. The result of complete combustion of coal and very fine ash particles is the elimination of clumping and adhesion of these particles and the minimization of contamination, erosion and corrosion of conductive and convective surfaces. Complete combustion of coal lowers heat losses due to the emission from the chimney and increases the thermal efficiency of the boiler. Moreover, a low carbon fly ash content (less than 0.5%) is thus obtained, which is advantageous in terms of profitably replacing cement and additives in the production of concrete.

When using low sulfur coal, such as Wyoming Powder River coal, the enthalpy of the coal is lower compared to high sulfur coal from the Eastern and Midwest Basins. Consequently, by using the same amount of low sulfur ground coal (size 75 micrometers, sieve number 200), the rated load of the boiler system is reduced due to the reduction of the thermal efficiency of the combusted fuel. Using finely divided coal with a low sulfur content (particle size 40 micrometers, sieve number 400) significantly accelerates combustion and improves the performance of the boiler, thanks to its increased ability to burn larger amounts of fuel per hour.

Microparticulate fly ash should reduce the wear intensity of rotating and stationary gas turbine blades. Optionally, the hot exhaust gas can be cleaned of volatile particles without significantly reducing the pressure or temperature by using swirling semi-permeable elements.

Likewise, sulfur sorbents, alkali sorbents, and ash modifiers may be added to the hot flue gas and treated in a similar manner with the help of rotating semi-permeable elements. The cleaning can be enhanced by introducing a centrifugal fan downstream of the exhaust gas outlet through the rotating semi-permeable elements.

If it is necessary to use complex fuels in the combustion chamber (mixtures of coal with natural gas, fuel oil, heavy oil fractions or water), it should be sufficient to premix the fuel with microparticulate limestone, provided that the mixture is stabilized in such a way that SO2 remover is available. The use of microparticulate coal in composite fuels (fuel oil, heavy fractions of crude oil, alcohol) with the intention of using such fuel in gas and oil fired boilers, without significantly compromising the efficiency of such a boiler, is facilitated by the increased surface area of microparticulate coal, its increased volatility and ease combustion, which contributes to an increase in high volumetric thermal efficiency. Such composite fuels can be burned with burners adapted to a small excess of air, which eliminates or minimizes the formation of nitrogen oxides.

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The most economical means of low pressure SO ₂ removal is the injection of microparticulate limestone into the combustion zone or into the hot flue gas exiting. The invention allows for the combustion of cheaper high sulfur fuels - coal and lignite, petrochemical coal, asphalt oil, heavy crude oil and asphaltenes - by being able to remove SO2 cheaply with microparticulate limestone / dolomite. Micronized iron oxide may be added to the limestone / dolomite as a liquefying agent to accelerate the reaction.

High-sulfur microparticulate carbon prepared by the process of the invention can be added to asphalt oils and heavy crude oil fractions prior to processing such blends by high-pressure hydrogenation (Coal H, Crude Oil H, Flexicoke processes) for processing into high-value petrochemical liquids (transport fuels, naphtha, diesel) while removing and recovering sulfur impurities in the form of elemental sulfur.

Microparticulate carbon for these purposes is in the form of particles, 80% of which are less than 30 microns (sieve number 525) and 20% are less than 20 microns (sieve number 875). Such blends of oil with microparticulate carbon contain up to 50% microparticulate carbon in the system. The result of the presence of such carbon in the mixture is, in the hydrogenation process, a higher yield of petrochemical liquids and an improvement in the economy of the process.

Certain applications of coal in composite fuels for internal combustion engines (passenger car, truck or diesel locomotive) require very high purity coal. For this type of purpose, the coal particles should be reduced to a mesh size of 400 (less than 40 microns) and then froth flotated to remove ash from them. The thus improved carbon can be dried and subjected to a particle reduction process in an ultra-refining device to a size below 1 micrometer. Low-cost pure ultra-fine coal is an important substitute for fuels in the automotive industry by itself or in the form of mixtures with gasoline, petroleum, methyl alcohol, MTBE (Methyl T-Butyl Ether) or as a fuel in the form of a carbon-water slurry.

Surface modification of the reduced sized solids is of particular importance for their transport via pipelines or for their use as fillers, pigments, absorbents, abrasives, cements, carbonaceous suspension fuels for high pressure injection engines, or as intermediates for further processing.

The surfaces freshly formed in the process of spontaneous shear grinding and gas erosion used for particle size reduction according to the present invention have active sides in the form of mechanical radicals (i.e. active sides resulting from the breakage of chemical bonds in the particle regions on the surface of the feed materials) or in the form of residual valences (i.e., active sides resulting from fracture of the lattice structure on the surface of such feeds). Such active sides tend to have a short lifetime and are saturated with oxygen or carbon dioxide in the air or with water particles from ambient moisture during the normal course of the process.

The invention, with an inert atmosphere (e.g. when a working fluid consisting of nitrogen or noble gases is used in the mill and operating in a system for full recycle of the working fluid), allows, in situ, the modification of freshly exposed and active surfaces with chemical reagents, both organic and inorganic, yielding valuable new materials for commercial and industrial purposes.

In order to modify the surface in the process of the invention, the chemicals are allowed to evaporate, if volatile, as part of the system's working fluid regeneration process, or they are dispersed as aerosols if they evaporate at a higher temperature or are solid, and then dissolve. them in an inert gas which is the working fluid of the system. In order to saturate mechanical radicals, alcohols (e.g. methyl alcohol up to stearyl alcohol), fatty acids (e.g. formic acid up to

190 297 of stearic acid) or vinyl compounds (e.g. vinyl alcohol, acrylic acid, acrylonitrile, vinyl chloride, styrene, butadiene), amines, ammonium salts, carboxyamine, urea and epoxy resins (e.g. ethylene oxide, propylene oxide, epichlorohydrin). Chemicals such as salts (for example alkali, alkaline or basic metal halides or stearates, or ammonium salts) are used to saturate the residual valences.

Particulates with reduced dimensions with chemically modified in situ surfaces are new components of matter with valuable properties - different surface wettability and surface tension, lower cohesiveness between particles, fluidity similar to dry powders, lower dynamic viscosity in a suspended state in hydrocarbons or aqueous substances.

The in-situ chemical surface modification according to the invention produces new microparticulate carbon substances which are suitable for the production of composite fuels (i.e. carbon suspensions in alcohol, in fuel oils, heavy crude oil) or for use as active substances. indirect. Modified carbon products show better dispersion, lower viscosity at high carbon contents in the slurries (e.g. fuels in the form of a slurry of carbon in water or composite fuels), better storage stability, and less erosive and shear properties.

A modification of this type is important for the preparation of microparticulate solids transporting feed materials via pipelines, which substances have satisfactory rheological properties at high solids contents and thus contribute to reducing transport costs per ton of solids.

Micromolecular limestone with chemically modified in situ surface is suitable for the preparation of fuels with high sulfur content (heavy crude oil, asphalt oils, bunker fuels, asphaltenes, high sulfur coals and petrochemical coals) meeting the environmental protection requirements after combustion.

Other surface-modified microparticle products include metal ores and other minerals, which are "pre-reacted" products for later use in various dry separation methods (e.g. gravity, magnetic or electrostatic separation) and wet separation (gravity, froth flotation or oil agglomeration).

The surface modification according to the invention can be used in the grinding of fillers and pigments. In the case of fillers (e.g. carbon black, silicas, clay, calcium carbonates), the modified substances have better properties in terms of their dispersion and reinforcement of polymeric materials. In the case of pigments, the modified substances show better properties in terms of dispersion and color saturation (e.g., tinting strength).

To prepare surface modified feed materials for high temperature heterogeneous chemical reactions, surface modification contributes to higher reaction yields and better end product yields, which reduces processing costs.

For cement and stone, the in situ modification process of microparticle products results in improved storage properties, faster setting and improved aging properties.

The device according to the invention is compact and lightweight and transportable to production sites for the rapid production of fresh microparticulate powders. In this way, it is possible to produce cement powder from crushed clinker or mini-clinker. The currently used clinker preparations use slow-hardening substances that prevent the ground cement from hardening during storage. The method according to the invention makes it possible to prevent hardening of the ground cement by producing fresh cement at construction sites. Likewise, in the method of the invention, quick setting agents for cement clinkers can be used in order to obtain a fresh cement that allows accelerated building. The possibility of producing fresh cement at construction sites can result in significant savings in grinding, packing, storage and transport costs.

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The effect of self-grinding according to the process of the invention is more economical separation of the desired components of the ore aggregates than can be achieved with impact mills. This is due to the intrinsic grinding phenomena releasing such ingredients at larger particle sizes than is the case during impact milling. With impact milling, some of the desired ingredients are lost in the exhaust facilities and milling energy is wasted due to the excessive grinding necessary to isolate the desired ingredient. For these reasons, the invention can be economically used in technologies such as the preparation of carbonaceous raw materials, requiring cheap separation of pyrites and the accompanying inorganic sulfur compounds.

By controlling the swirl, shear and erosive forces of the system, the invention also allows differential grinding to separate the components of mineral aggregates, provided that the grindability of the individual components is sufficiently different. For example, it is possible to concentrate precious metal ores by differential dry grinding of alluvial sediments containing high clay concentrations. Likewise, it is possible to concentrate gold ores by differential dry grinding of gold-bearing black sands. Differential dry milling according to the invention may be used to upgrade and separate high clay "wash coal" after drying such feeds prior to feeding them to the mill.

The reduction of solid reagents to powders containing 80% of particles smaller than 30 micrometers (sieve number>2>) and 20-60% particles smaller than> micrometers (sieve number 4> 00) allows the cheap production of many microparticulate chemicals, including earth metal carbides alkali, silicon, and metals of heavy metals (e.g., MgCl 2, CaCl ?, SiC, Cr3 _C2, Fe3 C, W ₂ C, NiC _2).

This process is so cheap that it should not only reduce the current production costs of such carbides, but also enable their new applications.

The above description relates in principle to certain fields of application of the invention. Some detailed examples of its specific applications are presented below.

Examples

1. Micromolecular carbon for power industry. The coal is ground by the method of the invention for direct combustion in the combustion chamber of the boiler, where 80% of the ground coal particles are smaller than 32 micrometers (sieve number> 00). Coal burns with a short, bright flame, similar to fuel oil No. 2 or natural gas. The combustion of coal is much faster and is above 99%, the dry exhaust gas losses are less than 6% compared to 96% combustion and 9% dry exhaust gas losses for crushed coal with particles size 7> micrometer (sieve number 200) incinerated in a shallow fluidized bed installation.

2. Clean coal fuel for boiler applications. Micronized coal fuel and microparticulate limestone acting as an absorption agent (for example limestone or a mixture of limestone and alkaline oxide) are milled by the method according to the invention for direct combustion in the combustion chamber of the boiler, where the coal is ground to 90% of the particles below 32 microns (sieve number> 00) and the limestone is ground to 90% less than 30 microns (sieve number>2>) and 1>% below> microns (mesh number sieve 4> 00). Coal burns in a similar way to fuel oil No. 2, with coal combustion being 99%, losses to dry flue gas are less than 6%, and limescale is washed out above 9>% SO ₂ and NOx.

3. Clean coal fuel to power gas turbines. Microparticulate coal fuel and microparticulate limestone acting as an absorbing agent are separately ground according to the process of the invention for direct combustion in a gas turbine, where the coal and limestone are ground to a state where 90% of the particles are less than 30 microns ( sieve number>2>),3>% of the particles are smaller than 10 microns (sieve number 2000) and 1>% of the particles are smaller than> microns (sieve number 4> 00). Coal burns in a similar manner to No. 2 fuel oil, limescale washing away more than 9>% of SO ₂ and NOx, and microparticles derived from the combustion process do not erode or contaminate gas turbine steer blades or impellers.

4. Clean coal fuel for gasification. Micronized coal fuel and microparticulate limestone acting as an absorbing agent are separately ground by the process of the invention to be combusted with oxygen in a high pressure coal gasification chamber to produce a medium calorific gas, where the coal and limestone are ground to a state where 80% of the particles are smaller than 32 microns (sieve number 525) and 25% of the particles are smaller than 20 microns (sieve number 875). The resulting medium calorific gas can be used as a fuel for a gas turbine, it can serve as a feed to fuel cells, or it can be used as an intermediate for the production of liquid fuels (e.g. methyl alcohol, gasoline, diesel) or chemical raw materials. Compared to coarse coal grades, microparticulate coal burns faster and gives higher gasification efficiencies.

5. Pure gold-plated fuel: Coal / gas. The fuel mixture consists of natural gas, microparticulate carbon and microparticulate limestone, and its solid components are separately ground according to the invention to a state where 90% of the particles are smaller than 32 micrometers (sieve number 500) and 15% smaller than 5 micrometers. (sieve number 4500). Compared to pure natural gas, this type of fuel blend reduces the costs of co-generation and combined energy generation.

6. Clean composite fuel: Coal / Oil. The sulfur-containing fuel mixture consists of a liquid sulfur-containing fuel, microparticulate carbon and microparticulate limestone acting as an absorption agent, the solids thereof being separately ground according to the invention to a state where 90% of the particles are smaller than 32 micrometers (sieve number 500 ) and 15% less than 5 microns (sieve number 4500) and both solids in the blend were chemically modified in situ during grinding. Surface modification makes it possible to obtain higher solids concentrations (up to 70%) in the liquid fuel mixture (with acceptable rheological properties) than would otherwise be possible.

7. Clean liquid fuel: heavy oil. The sulfur-containing liquid fuel consists of microparticulate limestone acting as an absorption agent, ground by the method of the invention to a state where 90% of the particles are smaller than 30 micrometers (sieve number 525) and 20% are less than 5 micrometers (sieve number 4500), wherein its surface has been chemically modified in situ during grinding. This blend allows the use of low-cost sulfur-containing fuel oils, bunker fuels, asphalt oils and heavy crude oil, allowing cheap heat and / or electricity generation from direct fired boilers or combined cycle power generators while allowing in situ absorption of 90% SO2 and ΝΟχ.

8. Clean slurry fuel containing carbon and water. Pure fuel in the form of a slurry of coal in water consists of coal and limestone acting as an absorbing agent, separately ground according to the invention to a state where 90% of the particles are smaller than 32 micrometers (sieve number 500) and 15% are smaller than 5 micrometers. (sieve number 4500), its surface having been chemically modified in situ during grinding. This carbon-water suspension fuel has a stable flame and high combustion rates, is stable during storage and tolerates carbon concentrations up to 80%. SO2 and ΝΟχ are absorbed in situ by microparticulate limestone during the combustion process. Due to their high carbon content and ease of use, such carbon-water suspension fuels can be used as useful means of transporting coal through pipelines, inland barges or sea tankers. Savings in grinding, handling and transport are achieved with this type of liquid carbonaceous fuels in the form of carbon-water slurries compared to conventional coarse coal. Moreover, fuels of this type can be easily stored in storage tanks. This type of carbon-water suspension fuel can be used as CO26 fuel

190,297 universal tanks or as feedstock to high-pressure coal gasification plants.

9. Control of SCf / NCf content: Co-combustion with production of calcium carbide. According to the invention, coal and limestone are ground to be burned directly in the combustion chamber of the boiler, the coal and limestone being ground separately until 70-90% of the particles are smaller than 30 micrometers (sieve number 525) and 20 -70% is smaller than 5 microns (sieve number 4500), carefully mixed to the molar ratio of carbon to limestone = 4: 1, and then injected for combustion in the boiler chamber. Calcium carbide is formed at the combustion temperature in a chamber (1604.4 ° C to 1843.3 ° C), where it combines with sulfur oxides and nitrogen oxides. Calcium carbide reduces SO ₂ to calcium sulphide (CaS) and NOx to nitrogen (N2) with an absorption efficiency of 90% -99%. The resulting particles, which can be collected further in the bag filter, greatly reduce (or eliminate) the need for a further wet scrubbing of the exhaust flue gas.

10. Regulation of SOU / NCf content: Co-combustion and recirculation. Elimination of SO2 and NOx generated during combustion of sulfur-containing fuels by co-combustion of fuel containing microparticulate limestone acting as an absorption agent, ground according to the method of the invention to a state where 80% of the particles are less than 20 microns (sieve number 875) and 20% of the particles are less than 10 microns (sieve number 2000) and allowing the fuel gases to circulate at 871.1 ° C to complete a rinse before being discharged into the dust collection bag. With the above particle sizes, the absorption of SO2 and NOx is over 99%.

11. Regulation of SC2 / NOx content: Co-combustion and hydration. Elimination of SO2 and NOx generated during combustion of sulfur-containing fuels by co-combustion of fuel containing microparticulate limestone acting as an absorption agent, ground according to the invention to a state where 80% of the particles are smaller than 20 micrometers (sieve number 875) and 20% of the particles are smaller than micrometers (sieve number 4500) and treatment of the resulting flue gas with fine droplet water mist to further activate the absorption means and reduce the temperature of the flue gas to a level of 760 ° C-982.2 ° C before discharge into the dust collection bag. Using a finely divided water mist with compressed air, the quicklime (calcium oxide, CaO) present in the flue gas is converted into slaked lime [calcium hydroxide, Ca (OH) a] which absorbs any residual SO2 and NOx. The above method enables the SO2 and NOx absorption degree to be over 99%.

12. SCf / NCfi content control: Sorbent injection. As an alternative to co-firing microparticulate coal with microparticulate limestone acting as an absorbing agent, microparticulate limestone can be used to inject sorbent into hot gases swirling over the combustion area. For injection of the sorbent, microparticulate limestone acting as an absorbent is ground by the process of the invention to a state where 80% of the particles are smaller than 20 microns (sieve number 875) and 20% of the particles are less than 10 microns (sieve number 2000). In order to improve the sorption effect, the microparticulate limestone can be further activated by adding microparticulate zinc ferrite or microparticulate iron oxide. The above method enables the absorption of more than 96% of SO2 and NOx13. Regulation of the NOx content 'Afterburning. As an alternative to NOx control, the microparticulate carbon is ground by the process of the invention to a state where 80% of the particles are smaller than 32 micrometers (sieve number 500), and then injected directly over the combustion zone to "burn" it. an oxygen deficiency zone is created, which eliminates the possibility of emitting residual amounts of NOx.

14. Improved cement clinker. Cement clinker is produced by grinding the cement marl (e.g. limestone, clay, stones / silicates, iron ore and other components) to a state where 90% of the particles are smaller than 32 microns ( sieve number 500) and 15% of the particles are less than 5 microns (sieve number 4500); such cement marls are mixed and burned in a kiln for the finished cement clinker.

190 297

Clinker made of cement marl containing the above-described super-comminuted and ultra-comminuted particles has a better and more constant quality than clinker made without such preparation of its active ingredients.

15. Improved cements. The cement particles have surfaces chemically modified in situ during grinding according to the invention. Surface modification of microparticulate cement improves strength and contributes to faster development of final physical properties in cement mixtures.

16. Improved preparation of cement. Reducing the size of the cement clinker where the cement product is ground by the process of the invention to a state where 90% of the particles are less than 30 microns (sieve number 525) and 20% less than 5 microns (sieve number 4500), 10% being less than 2 micrometers. Cement containing the above-specified superfine and ultrafine particles has higher strength, better aging properties and binds faster in cement mixtures.

17. New cement recipes. Volcanic glaze (e.g. volcanic pozzolana, ash, volcanic tuff or rhiolite) can be processed into microparticulate glazes (e.g. the rhiolite is ground by the process of the invention to a point where 80% of the particles are smaller than 32 micrometers (sieve number 500) and 20% particles are smaller than 10 micrometers (sieve number 2000) Cement mixes containing microparticulate volcanic glazes give concrete with high initial strength and fast setting, resistant to compressive forces of 276 x 10 ⁵ Pa or more. a by-product of power plants, and used in high-strength concrete mixes for mixing with Portland cement, silica exudates and appropriate aggregates, resulting in a cement with a compressive strength of 1173 x 105Pa to 1380 x 105Pa. the state of the microparticulate product should give the result reduction of electricity production costs.

18. Regeneration of cement. The spent cement is processed into a mixture of microparticulate regenerated cement according to the method of the invention, by dry grinding it into particles of dimensions suitable for their use in new concrete mixes in combination with fresh cement, constituting an additional binder. The effect of the possibility of on-site regeneration of used concrete is significant savings in material, transport, waste disposal and labor costs.

19. New building materials. Reducing the dimensions of granite, quartz, wollastonite or other hard silicates and igneous rocks where the comminuted materials are ground by the method of the invention to a state where 90% of the particles are smaller than 32 microns (500 mesh number) and 20% of the particles are less than 5 microns (sieve number 4500), and then these products are reacted with the binder to obtain new building materials. Products made of microparticulate hard rocks have excellent mechanical strength and different physical properties compared to products typically used in construction, such as mortars, bricks, blocks, tiles and slabs. Concrete mixes with high compressive strength, prepared with the addition of ingredients such as silica fumes and fly ash, exhibit high compressive strength but poor ductility, become brittle and show lower shear strength. The replacement of conventional aggregates used in mixtures of this type with microparticulate hard rocks prepared by the method according to the invention eliminates this disadvantage and makes it possible to obtain concrete with high mechanical strength, high compressive strength and high shear strength.

20. New insulation materials. Cellular cement foams with microparticulate rhyolite or other volatile glazes have a closed cell structure, which is characteristic of these minerals due to the bubbles of volcanic gases trapped in them. Such foams are characterized by a strong insulating properties and additional structural strength (k values of 30 to 40 and compressive strengths up to 138 x 10 ⁵ Pa). In addition to complete fire resistance, it contains micro28 cellular rhiolite

190 297 particulate foam concrete mixes are excellent thermal and acoustic insulators, as well as good shock absorbers. Such cheap foams can replace expensive polyurethane foam insulations, which emit poisonous gases (e.g. hydrogen cyanide) when exposed to fire. These types of foams can also reduce the requirement for solid reinforcement of highly spongy structures, they can be used to erect low-cost insulated warehouses, and can serve as foundations for road beds, thus reducing the maintenance costs associated with road damage due to temperature fluctuations.

21. Production of iron anthrax and spongy iron. In order to convert the iron ore into powdered iron carbide, the method of the present invention grinds the dry iron ore to a state where 90% of the particles are less than 32 microns (sieve number 500) and 15% are less than 5 microns (sieve number 4500). Microparticulate iron ore is mixed with microparticulate carbon where 90% of the particles are less than 30 micrometers (sieve number 525) and 15% are less than 5 microns (sieve number 4500), and the resulting mixture is processed in a reducing furnace on iron carbide. The effect of processing iron ore into iron carbide at the site of its extraction is a product with a much higher iron content (Fe3 C with 93.22% Fe compared with Fe2C> 3 with 69.94% Fe), which reduces transport costs to the market. Iron carbide can be used directly in the technology of steel processing in electric furnaces using it instead of scrap iron in mini-mills, thus avoiding the costly step of reducing iron ore pellet in blast furnaces.

In order to convert the iron ore into sponge iron, the method of the present invention grinds dry iron ore into a microparticulate product in which 60% of the particles are smaller than 32 micrometers (sieve number 500). Micronized iron ore is processed in a reducing furnace together with gasified coal derived from microparticulate coal and oxygen. The resulting sponge iron is a synthetic cast iron scrap that can replace the cast iron scrap used to make steel in electric furnaces in minutes.

22. Micronized coal for blast furnaces. Micronized carbon, ground by the process of the invention to a state where 80% of the particles are less than 32 microns (sieve number 500), can be used directly in conventional iron ore reduction blast furnaces by introducing such micronized carbon into the air nozzles of said furnaces. Up to 40% of coal can be replaced with such low-cost microparticulate coal containing a lot of sulfur, and all natural gas used as auxiliary fuel in such processes, with the sulfur derived from such coal absorbing the blast furnace slag. By introducing microparticulate carbon and oxygen into the blast furnace processes, up to 90% of the carbon can be replaced with microparticulate carbon obtained by the process according to the invention, which reduces the costs of steel production.

23. Recovery of strategic metals. Due to the availability of cheap microparticulate ores obtained by the method of the invention and cheap hydrogen from gasification of microparticulate coals with high sulfur content, it is possible to recover strategic metals (manganese, nickel, cobalt, tin, titanium, chromium, molybdenum, tungsten and vanadium) from their poor ores. The lean ores of strategic metals are ground by the process of the invention to a state where 90% of the particles are smaller than 30 microns (sieve number 525). These microparticulate powders are treated with hydrogen in a reducing furnace, thereby releasing strategic metal particles which can then be separated by gravity from the undesirable gangue.

24. Dry separation of precious metals. The reduction of dimensions according to the invention can be used to separate precious metals from alluvial deposits with high clay content, black sands or their concentrates and to recover these metals from their refractory ores. Due to the fact that it is a dry technology, it saves water and water treatment, which reduces processing costs when recovering precious metals, especially in the case of deposits located in areas with a dry climate.

25. Releasing gold and platinum from ores. The downsizing process according to the invention can be used to release elemental gold from hard-containing ores

190 297 quartz or silicates and to release elemental platinum encased in magnetite rolls. The released gold can be recovered on concentration tables or by chemical leaching, and platinum can be enriched by wet magnetic separation.

26. Production of hydrogen. Coal and limestone are ground separately in the process according to the invention, and then burned in oxygen in the presence of water in a high-pressure gasification plant, thus obtaining a mixture of carbon monoxide (CO) and hydrogen (H ₂ ), the coal being ground to the state of in which 80% of its particles are smaller than 32 microns (sieve number 500) and the limestone is ground to a state where 80% of its particles are smaller than 30 microns (sieve number 525) and 25% smaller than 5 microns. Due to the microparticulate carbon, runtime is reduced and reaction control is improved, which reduces the cost of hydrogen production below those of using less comminuted coal. It is one of the cheapest methods of producing hydrogen.

27. Flue gas treatment for turbines with direct coal firing. Exhaust gas from coal direct firing turbines, which burns the coal into 75 micron particles (sieve number 200), is passed horizontally through the rotating semi-permeable elements of the apparatus of the invention. The rotating semi-permeable element is a unit consisting of a rotating sieve between the combustion chamber and the gas turbine, with a trap below the rotating sieve. Most of the hot molten ash particles formed from the coal are removed from the gas stream with negligible pressure losses and temperature drops, while the size of the ash particles remaining in the gas stream is reduced so as not to damage the guide vanes or spinning turbines. Likewise, swirling semi-permeable elements can be used to clean hot gases when sulfur sorbents, alkali materials or ash modifiers are injected into the gas stream to eliminate erosion and corrosion of the gas turbine and meet environmental emission standards. The effectiveness of such cleaning can be increased by using, additionally, a centrifugal fan after the hot gases pass through the rotating semi-permeable elements.

28. Treatment of exhaust gases for PFBC. The exhaust gases discharged from the fluidized bed combustion chamber containing ash and alkali particles are cleaned by passing the hot gases through a device according to the invention containing rotating semi-permeable elements, and only then fed to the gas turbine inlet, which eliminates the need for expensive and brittle cross-flow ceramic filters. The efficiency of such cleaning can be increased by using a centrifugal fan located behind the rotating semi-permeable element, which eliminates the residual amounts of solid particles in the hot gas stream.

29. Treatment of flue gases for coal-fired boilers. The tungsten rotating semi-permeable element of the device according to the invention is placed horizontally in the combustion chamber in the zone of the boiler tubes of the coal-fired boiler in the form of particles with a size of 75 microns (mesh number 200). Larger particles are removed by the rotating semi-permeable element and kept in the combustion chamber long enough to supply additional heat to the boiler tubes, as a result of which the coal combustion rate rises to 99% and the dry flue gas loss drops below 8%.

30. Preparation of calcium carbide. By the process of the invention, limestone and coal are ground separately until 80% of the particles are less than 30 microns (sieve number 525) and 20-60% are less than 5 microns (sieve number 4500). The combustion of the microparticulate carbon in the cyclone combustion chamber is then initiated and maintained at a temperature in the range of 1604.4 ° C-1843.3 ° C. Microparticulate limestone and microparticulate carbon are carefully mixed to the molar ratio of limestone to carbon = 1: 4, after which the resulting mixture is blown into the combustion zone where calcium carbide is formed. The thus formed calcium carbide is removed by means of an air stream through a conduit where the reaction products are cooled to 149 ° C, whereafter powdered calcium carbide is separated from the entraining air stream in the cyclone.

190 297

In the foregoing description, the preferred embodiments of the invention have been presented for purposes of illustration and not intended to limit applications. Professionals in the field will readily find application variants equivalent to those described. All such variations, modifications and equivalents are within the scope of the invention.

Claims (37)

Method and device for dry grinding of solids Patent claims 1 A dry solids milling process in which the solids are directed approximately upwards into a vortex grinding zone and the upwardly directed solids are milled in a vortex grinding zone by passing a portion of the particles through a vortex grinding zone containing at least one successively in a vertical orientation, a vortex grinding step, wherein the particles are passed upward through a semipermeable element and a slit characterized in that the particles are passed upward through at least one rotating semipermeable element (60) and an annular gap (70B) defined by having a flat surface, a stationary plate (70) with a circular hole (70A) and a rotating solid circular disk (61) disposed in the circular hole. 2. The method according to p. The process of claim 1, wherein in the step of passing the particles upward through the rotating semipermeable member (60), the particles are passed through an assembly comprising the rotating screen (60C). 3. The method according to p. Process according to claim 2, characterized in that in the step of passing the particles through the rotating sieve (60), the particles are passed through a sieve not thinner than 2.5. 4. The method according to p. The process of claim 3, wherein the screen has a number ranging from 2.5 to 60. 5. The method according to p. The method of claim 3, wherein the screen has a number ranging from 4 to 10. 6. The method according to p. The process of claim 1, wherein the step of passing the particles through the annular gap (70B) passes the particles through an annular gap (70B) that is 12.7 mm to 152.4 mm (0.5 to 6 inches) wide. 7. The method according to p. The process of claim 1, characterized in that in each stage the particles are passed through a rotating semi-permeable element (60, 63, 73) and then through an annular gap (70b, 71B, 72B). 8. The method according to p. The process of claim 1, further comprising recycle the particles externally by a centrifugal fan (62) downstream of the rotating semipermeable member (60) and having a recycle channel (18) to receive particles from the rotating fan (62) and having an outlet. below at least one degree (61, 70, 70A, 70B) of vortex grinding. 9. The method according to p. The process of claim 1, further comprising removing particles above the grinding zone (12). 10. The method according to p. The process of claim 9, wherein the removing step rotates at least one centrifugal fan (68) after at least one grinding stage (62, 72, 72A, 72B). 11. The method according to p. The process of claim 1, further comprising pre-milling the coarse particles to fines before directing the fines to the vortex grinding zone (12). 12. The method according to p. A process as claimed in claim 1, characterized in that the coarse and fine particles are further pre-milled by introducing solids into the chamber (11), forming a fluidized bed of solid particles in the chamber (11), directing air upwards in the chamber (11) and creating controlled vortices in the zones. milling in a fluidized bed with the implementation of automatic grinding. 13. The method according to p. The process of claim 12, wherein the particles are internally recycled by introducing the swirling semipermeable element (60) into the coarse pre-grinding zone, and by rotating the swirling semipermeable element (60) at a speed sufficient to prevent portions of the oversized particles from passing therethrough and returning the particles to the zone. pre-grinding coarse particles. 14. The method according to p. A process as claimed in claim 12, further comprising externally returning the particles to the fluidized bed. ... 15. The method according to p. The process of claim 1, wherein the plurality of vortex grinding stages are used, and further a stage of external recycle of the particles to the previous stage. 190 297 16. The method according to p. The process of claim 9, characterized in that the removal step removes particles in two vertically arranged removal steps removing particles of increasingly smaller dimensions. 17. The method according to p. The process of claim 12, wherein the controlled vortex generation step consists of rotors (56, 57, 58, 59). 18. The method according to p. The process of claim 7, characterized in that the rotating semipermeable element (60, 63, 73) and the rotating disk (61, 64, 67) rotate on the common shaft (51). 19. The method according to p. The process of claim 1, wherein the grinding is performed in an inactive atmosphere in the presence of a chemical reagent to effect controlled surface modification. 20. Dry solids milling apparatus comprising a semi-permeable element and at least one successively vertically oriented vortex grinding stage comprising a fixed and a movable element with a gap therebetween forming a vortex grinding zone, and comprising means for directing the solids approximately upwards to a vortex grinding zone, characterized in that the at least one vortex grinding stage comprises at least one rotating semi-permeable element (60) and annular gap forming elements (70B) comprising a flat surface stationary plate (70) with a circular opening (70A) and a rotating solid circular disk (61) disposed in the opening (70A), the spinning semi-permeable member (60) and the annular gap (70B) being configured to pass a portion of upward facing particles therethrough and the composition of each vortex grinding stage enters a rotary stripper (62) located behind the swirling The semipermeable element (60) dimensionally screens the upwardly directed particles. 21. The device according to claim 1 20, characterized in that the rotating semipermeable element (60) comprises an assembly comprising a rotating screen (60C). 22. The device according to claim 22 A screen according to claim 21, characterized in that the rotating screen comprises a screen (60) not thinner than 2.5. 23. The device according to claim 1 The method of claim 22, wherein the screen has a number ranging from 2.5 to 60. 24. The device according to claim 24 The method of claim 22, wherein the screen has a number between 4 and 10. 25. The device of claim 1 20, characterized in that the annular gap (70B) has a width of 12.7 to 152.4 mm. The device of claim 26 20, characterized in that each stage comprises a rotating semipermeable element (60, 63, 73) and elements (61, 70, 70A; 67, 71, 71A; 67, 72, 72A) forming an annular gap (70B, 71B, 72B) and a centrifugal elimination fan (62, 65, 68) positioned downstream of the semipermeable member (62, 63, 73). The device of claim 27 20, characterized in that it comprises an internal recycle device comprising means (51, 52) for rotating the semipermeable element (60) at a speed sufficient to prevent part of the particles from passing therethrough. The device of claim 28 27, further comprising an external recycle unit comprising a rotary stripping centrifugal fan (62) downstream of the rotating semi-permeable member (60) and a recycle channel (18) that receives particles from the rotating fan. stripper (62) and has an outlet below at least one vortex grinding stage. The device of claim 29 20. The apparatus of claim 20, further comprising means (13) for removing particles above the vortex grinding zone (12). 30. The device of claim 1 29, characterized in that the removal means (13) include means (51, 52) for rotating at least one stripping centrifugal fan (68) after at least one spin grinding stage. 31. The device of claim 1 20. The process of claim 20, further comprising means for pre-grinding the coarse particles to fine particles prior to directing the fines into the vortex grinding zone (12). 190 297 The device of claim 32 30, characterized in that it comprises a pre-milling unit comprising means for feeding solids into the chamber (11), means (15, 55) for forming a fluidized bed of solids in the chamber (11), comprising means (55) for directing air upwards in the chamber and means (56, 57, 58, 59) for creating a controlled swirl in the fluidized bed to perform self-grinding. The device of claim 33. 32, characterized in that it comprises means (18, 19) for externally returning the particles to the fluidized bed. 34. The device of claim 34 20, characterized in that it comprises a plurality of grinding stages and means (18, 19) for external recycling of the particles to the previous stage. The device of claim 35 29, characterized in that the removal means are removal means in two vertically arranged removal stages (16, 17) removing particles of increasingly smaller dimensions. 36. The device of claim 36 The method of claim 32, characterized in that the means for producing a controlled vortex comprises rotors (56, 57, 58, 59). The device of claim 37. 26, characterized in that it comprises means (52) for rotating the rotating semipermeable element (60, 62, 73), the rotating disk (61, 64, 67) and the rotating elimination fan (62, 65, 68) on the common shaft (51) .