This application is the U.S. national phase of International Application No. PCT/FI2017/050743 filed 27 Oct. 2017 which designated the U.S. and claims priority to FI Patent Application No. 20165813 filed 27 Oct. 2016, the entire contents of each of which are hereby incorporated by reference.
There exists a great need for comminuting of material in the mining, mineral, and cement industries. The noteworthy issue is that comminuting material is the biggest energy-consuming process of these industrial sectors.
The energy consumption required by the comminuting process depends on the material type and its magnitude is typically 20-60 kWh/t, but in fine comminuting may be as much as 100-1000 kWh/t.
Friction and the heat it causes takes up most of the energy consumption in comminuting. The main part of the amount of energy required is used at the grinding stages, the costs of which in a mineral concentration process may be up to 70% of the concentration costs.
Some of the prior art apparatuses and methods are disclosed in publications U.S. Pat. Nos. 2,981,486, 1,704,823 and GB709729.
There are, however, problems associated with the prior art methods. The problem with the prior art methods and apparatuses is their high energy consumption and modest efficiency. A further problem is the low quality of the end product, that is, the fine particles, due to the breaking manner of the particles based on fast compression, which leads to arbitrary fracture planes in the area of principal stress fields, and the formation of a hyperfine fraction which is difficult to process.
An object of the invention is thus to develop an apparatus and a method so as to solve or alleviate the above problems.
The object of the invention is achieved by an apparatus and method which are characterized by what is stated in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.
The invention is based on a new kind of mutual positioning of conveyor surfaces, which in turn allows free crushing, in other words, particle-specific slow compression of solid material and its weakening by increasing micro-cracks.
The advantage of the inventive apparatus and method is low energy consumption, a high-quality end product, as well as a well-defined and reliable device structure. The invention additionally makes it possible to divide the end products into material flows according to different particle sizes.
The invention will now be described in more detail in connection with preferred embodiments and with reference to the accompanying drawings, in which
The invention relates to comminuting of material by compression, by way of example in particular to comminuting of elastoplastic material. Minerals, for example, serve as an example of a comminutable, at least partly elastoplastic material. If the material is homogeneous and fully elastic, the stress field formed in the material is distributed according to the location of the compression points and surface area in the material, and the stress field may be calculated relatively accurately based on the bond strength between atoms. In practise, all the comminutable material particles are non-homogeneous and at least slightly plastic, and they typically include a plurality of matter components unevenly distributed in the material and which have discontinuity points and micro-cracks at their boundary surfaces, in particular. In addition to minerals, ceramic material and glass are elastoplastic material.
The apparatus GD shown in the figures comprises a first conveyor structure C1 having a first conveyor surface B1. The apparatus also comprises a second conveyor structure C2 having a second conveyor surface B2. Both conveyor surfaces B1, B2 are conveyor surfaces rotatable in the direction of movement D, in a way like a chain track, which rotates according to its closed-loop shape full rotations supported by its support structure SS and powered by one or more motor M1A, M2A or another actuator M1A, M2A. The actuator M1A, M2A rotating the conveyor surface B1, B2 is an electric motor or a hydraulic motor or another actuator, for example. The actuator M1A, M2A forms means for bringing the conveyor surfaces B1, B2 in a movement in the direction of movement D where the two conveyor surfaces B1, B2 placed to face each other are arranged to move from a first end E1 of the conveyor structures C1, C2 towards a second end E2 of the conveyor structures. It is obvious that at the second end E2 of the apparatus, the movement direction of the conveyor surfaces becomes the opposite as the rotation movement of the conveyor surfaces B1, B2 turns the movement into the return direction, but the movement in the return direction takes place at the outer sides of the pair of conveyor structures C1, C2 and is at the rear end, so the second end E2, towards the front end, so the first end.
However, what is essential in the apparatus is the structures defining the comminuting space GS, so the edges of the area where the conveyor surfaces B1, B2 face each other. As mentioned, the conveyor surfaces B1, B2 define the comminuting space GS.
At least at one end of the conveyor surfaces B1, B2, the conveyor structures C1, C2 have under the conveyor surface, a drive wheel, drive gear of a similar drive transmitter GE1, GE2 that transfers the rotational force provided by the actuator MIA, M2A to the conveyor surface B1, B2. In addition, the conveyor structures have at the opposite end idler wheels TR1, TR2 on which the conveyor surfaces B1, B2 pass and turn into the return movement.
The apparatus structure is such that the means M1A, M2A for bringing the conveyor surfaces B1, B2 into a movement in the direction movement D are arranged to bring the conveyor surfaces B1, B2 into a rotational movement according to successive full rotations.
In addition, the conveyor structure such as C1, C2 comprises a support structures SS1, SS2 to support the rotational movement of its conveyor surface B1, B2, the support structure may be accomplished with supporting rolls, and naturally it is plausible to see the aforementioned idler wheels TR1, TR2 as included in the support structures and likewise the drive wheels GE1, GE12, GE2, GE22.
The conveyor surface such as B1 and correspondingly B2 is, as mentioned in the above, a closed loops that rotates successive full rotations supported by drive wheels GE1, GE12 and correspondingly GE2, GE21, as well as idler wheels TR1 and correspondingly TR2, and also the support rolls SS1 correspondingly SS2.
Referring to
Correspondingly, the axle A2 of the idler wheel TR1 is fitted with a bearing BR2 to a support member SM2 such as a slide rail SM2 by means of which an actuator HM2 such as a hydraulic actuator moves the lower end of the axle A2 in relation to the fixed frame FR of the apparatus.
Between the ends of the conveyor such as C1 there may be other vertical axles between axles A1, A2, and their ends may have device structures as the ones disclosed. There may be another number of drive wheels than the two drive wheel pairs in the example of the figures.
In the apparatus, the first conveyor surface B1 and the second conveyor surface B2 are positioned facing each other. This way, the conveyor surfaces B1, B2 are arranged to define the comminuting space GS where the material is comminuted by the compression provided by the moving conveyor surfaces B1, B2.
From the point of view of the material to be comminuted, the apparatus comprises an inlet IN, and from the point of view of material already comminuted, the apparatus comprises outputs OUT1 and OUT2. Output OUT 1 is at the substantially horizontal lower edge of the apparatus and in practise it is a gap left between the lower edges of the conveyor surface pair B1, B2, which extends at the lower edge of the conveyor towards the rear end E2. Output OUT2 is at the rear end E2 of the apparatus, where the movement direction D is aimed, in practise output OUT2 is the end point of the area facing each other in the conveyor surfaces B1, B2 at the second end E2, so the rear end, of the conveyor structures C1, C2.
To subject the material to compression, the structure is such that in the apparatus the conveyor surfaces B1, B2 positioned to face each other are placed in a convergent manner so that the gap between the conveyor surfaces B1, B2 narrows when examined in the movement direction D of the conveyor surfaces, so that the advancing movement of the conveyor surfaces B1, B2 is arranged to bring about compression in the material being comminuted.
The convergence angle of the convergence in the movement direction of the conveyor surfaces, that is, the wedge angle, is marked with INCL-D in
The convergence angle, transverse in relation to the movement direction of the conveyor surfaces, is marked with nip angle INCL-TD. The angle INCL-TD is in
Referring to
In the comminuting space GS the transverse convergence, so the nip angle INCL-TD (
Although the top view
With reference to
The comminuting ration, that is, crushing ration refers to the ratio between the size of the inlet IN and output OUT1 of the apparatus, and it is between 5-15. for example. The size of the inlet should be taken as a function of varying height as in
The magnitude of the wedge angle INCL-D (
With reference to
Depending on the length of the conveyor surfaces, the device settings (speed of motion of the conveyor surfaces, nip angle, wedge angle) and the particle size of the incoming material, there may also be more height positions for the compression point (three in the above) and particle size categories (three in the above, so incoming particle MP, daughter particle MPD1, and subparticle MD2 of daughter particle).
If the size of the subparticle MPD2 is already smaller than the exit gap OUT1 at the lower edge, the “finished” subparticle MPD2 can exit through output OUT1.
It may obviously also be the case that the incoming particle MP or daughter particle MPD1 is already small enough to exit through the output OUT1 at the lower edge.
Consequently in the invention, the grading/distribution, conveying and cracking is repeated everywhere in the comminuting space GS particle-specifically in a layer no more than one particle thick.
It is detected that the direction TD, transverse in relation to the movement direction D, in which direction said transverse convergence exists between the conveyor surfaces, is a substantially perpendicular transverse direction in relation to the movement direction D of the conveyor surfaces. It is furthermore the case that the existing conveyor structures are so positioned that the movement direction D of the conveyor surfaces is substantially horizontal.
Further, the conveyor structures facing each other are so placed that the direction TD transverse in relation to the movement direction D of the conveyor surfaces is substantially vertical.
This being the case, referring in particular to
The feed particles smaller than the gap-like lower part, so the output OUT1, in the comminuting space GS, fall freely in the vertical direction or, if need be, assisted by a gas or fluid flow, and exit the comminuting space at its gap-like output OUT1 at its lower edge.
Alternatively, feed particles larger than the gap-like lower part, so the output OUT1, are graded by stopping (because of the convergence according to the nip angle INCL-TD in the transverse direction in relation to the movement direction D, that is, vertical direction) at the height levels according to their sizes, that is, between the conveyor surfaces B1, B2. The walls, so the conveyor surfaces B1, B2, of the comminuting space GS then carry the particles in the movement direction D towards the rear end E2 and at the same time compress the particles that have got wedged between the walls, that is, the conveyor surfaces B1, B2, which may exit directly from the gap-like output OUT2 of the comminuting space GS, or before that crack according to their breaking strength and whereby the created daughter particles (or the latter subparticles MPD2 of the daughter particle) fall in the comminuting space vertically lower either through the output OUT1 at the lower edge, or if the transverse (in relation to movement direction) convergence of the comminuting space GS, so in practise the conveyor surfaces, stops the daughter particle MPD1 still too large, the conveyor surfaces B1, B2 transport the daughter particle in the movement direction towards the output OUT2 in which case the daughter particle MPD1 either breaks during the movement and creates the subparticle MPD2 or exits from the output OUT2 at the rear end E2 of the device. Correspondingly, the subparticle MPD2 either drops into the output OUT1 or due to the nip angle stops before the output OUT1 and joins the movement of the conveyor surfaces into the direction D towards the output OUT2 at the rear end.
This way, a long dwell time is achieved for the daughter particles MPD1 and their subparticles MPD2, that is, a slow compression which improves the compression and the comminuting quality. In the invention, particles are compressed slowly and widely enough so that the maximum number of micro-cracks weakening the material would develop into the material. Slow compression is an energy-efficient way to comminute material. In slow compression, the probability of a compression member to create additional, unwanted kinetic energy and friction to the daughter pieces is the smallest. Furthermore, slow compression results in more evenly sized daughter pieces that is daughter particles/subparticles and less non-selective small daughter pieces/subpieces in the areas of the principal stress fields than a fast, impact-like loading.
Slow compression is implemented successively, also for the daughter pieces created in the cracking, and repeated (that is, the stopping of the falling of the daughter piece due to the nip angle and the continuation of the movement in the movement direction made possible by the stopping) until the size of the resulting particles is small enough, so smaller than the output OUT1 at the lower part of the device. Elastic energy stored between the compressions in the compressions is released and the particles must have the chance to change their position before the subsequent compression stage leading to cracking. The repetition of such compression-release stages enhances the creation and growth of micro-cracks in the particle parts remaining intact. The compression-release cycles are implemented so that the material gradually weakens in all the size categories undergoing compression, also in the size categories preceding the product size (so, the size going to the output OUT1).
Referring to
According to the observations of the applicant, a suitable nip angle (INCL-TD (
The size of the material particles MP coming in to the inlet IN is between 0.10-200 mm, for example.
The comminuted particle size obtained from the output OUT1 is between 0.1-5 mm, for example. A suitable speed of motion for the conveyor surfaces B1, B2 in the movement direction D, as created by the motors MIA, M2A, is 0.02-0.5 m/s, for example. In connection with the motors, or controlling the motors, there may be a control unit by means of which the speed of the conveyor surfaces B1, B2 may be adjusted, in particular so that the speed of motion of the conveyor surfaces B1, B2 slightly differs from each other. So, the speed of motion of the conveyor surfaces B1, B2 maybe adjusted to slightly differ from each other. The purpose of the speed difference is to increase the effective ares of compression and to cause shear forces and twisting forces in the particle, increasing the micro-cracks. To avoid wear and tear as well as friction, the speed difference must be small, at most 5%, for example.
With the inventive calculated rubbing, the load is directly aimed at the particles. By deliberately making use of the speed difference between the conveyor surfaces B1, B2 to create rubbing, small particle sizes are accomplished with a significantly lower volumetric energy consumption.
The following is remarked about the conveyor surfaces B1, B2. Referring to
To be discussed next are adjustment structures AD1-AD4 shown in
It is a good idea to be able to adjust one or more of the following: adjustment of the convergence angle INCL-D of the convergence in the movement direction, so the wedge angle, adjustment of the convergence angle INCL-TD of the convergence in the direction TD transverse in relation to the movement direction D, so the nip angle, adjustment of the distance between the conveyor surfaces B1, B2 and/or adjustment of the speed of motion of the conveyor surfaces.
The device structures for performing the various adjustments may be partly or entirely the same device structures AD1-AD4. The apparatus thus comprises adjustment means AD1-AD4 for the conveyor surfaces B1, B2 for adjusting the convergence angle INCL-D of the convergence in the movement direction, so the wedge angle, and the same or different adjustment means for adjusting the convergence angle INCL-TD of the convergence in the direction TD transverse in relation to the movement direction D, so the nip angle, and the same or different adjustment means for adjusting the speed of motion and distance between the conveyor surfaces B1, B2.
In
In
The adjustment means AD1 comprise an actuator HM1, such as a hydraulic motor/hydraulic piston HM1, and a support member SM1 such as a slide rail SM1 by means of which the actuator HM1 moves in the spot in question a subentity that includes the end axle A1 with its bearing housing, the drive gear GE1, rotating motor M1A of the end axle.
Each of the conveyor structures C1, C2 may be separately adjusted with the adjustment means AD1-AD4 within the limits set for the device. By moving the conveyor structure, the distance between the conveyor surfaces B1, B2 as well as the nip angle INCL-TD and wedge angle INCL-D are adjusted, so the relative transition created by the conveyors and the sizes of the inlet IN or output OUT1, OUT2 may be adjusted. The conveying speed of each conveyor surface B1, B2 consisting of lamellas and/or a belt is adjusted according to the material properties and capacity with the speeds of the motors MIA, M2A.
The adjustment of the wedge angle INCL-D, so the convergence in the movement direction, is performed for the conveyor C1 by adjusting, with the adjustment structures AD2 (actuator HM2, in particular), AD4 at the front edge E1 of the conveyor, the conveyor C1 to move by its front edge E1 more to the right horizontally, so away from the second conveyor structure (C2, only lower corner seen in
The adjustment of the nip angle INCL-TD, so the convergence in the transverse direction in relation to the movement direction, is carried out by adjusting the top edge of the conveyor structure C1 by the adjustment structures AD3, AD4 therein to tilt more to the right, that is, away from the second conveyor structure (C2, only lower corner seen in
The adjustment of the distance between the conveyor surfaces B1, B2, when it is not desired to change the nip angle INCL-TD or the wedge angle INCL-D, but when it is desired to change the size of the comminuting space GS, takes place by performing a horizontal move right or left with all the adjustment means AD1-AD4.
Referring to
The core of the method is that the method uses said conveyor surfaces B1, B2 defining the comminuting space D, in which method the comminuting space GS is also convergent when examined in the transverse direction in relation to the movement direction, the converging conveyor surfaces B1, B2 stopping between the conveyor surfaces the falling movement of such a daughter particle MPD1 formed in the comminuting space GS, after which with these still moving conveyor surfaces, a movement into the movement direction is also achieved for one or more daughter particles MPD1.
It is naturally the case that the comminuting space GS converging transversely (in relation to movement direction) in accordance with the nip angle INCL-TD, so in practise the conveyor surfaces B1, B2 defining it in a convergent manner stop the incoming material particle, so one that falls through the inlet IN, and so it will be subjected to the movement in the movement direction of the conveyor surfaces, so movement in the direction D.
It is the case that the daughter particle MPD1 is conveyed by the movement of conveyor surfaces in the opposing conveyor structures of the comminuting apparatus in the movement direction D in the comminuting space between the conveyor surfaces B1, B2. By conveying the daughter particle MPD1 further and further in the movement direction D, the daughter particle is comminuted, when examined in the movement direction D, in a converging (angle INCL-D
Daughter particles MPD1 and/or subparticles MPD2 of daughter particles and/or still smaller material particles comminuted from subparticles are removed from the comminuting space through the output at the lower edge of the comminuting space. OUT1. This takes place when the particle size during comminuting becomes smaller than the output OUT1 at the lower edge.
In parallel or alternatively daughter particles MPD1 and/or subparticles MPD2 of daughter particles and/or still smaller material particles comminuted from subparticles are removed from the comminuting space through the output at the rear end, so output OUT2, of the comminuting space, where the movement direction D is directed. This takes place when the particle size during comminuting remains larger than the output OUT1 at the lower edge of the apparatus.
It is practical when the movement direction D of the conveyor surfaces B1, B2 is substantially horizontal, and the conveyor surfaces stop a particle MP, or daughter particles MPD1 and/or subparticle MPD2 of a daughter particle and/or even smaller material particles comminuted from a subparticle in a substantially vertical falling movement.
The slow compression characteristic of the method is individually targeted directly to the particle in all the size categories and implemented in an open space so that the compressed particles and the created daughter particles (and their sub-pieces) have as little contact with each other as possible and may immediately exit their breaking spot by the effect of gravity or the release of the force caused by the elastic energy stored therein in compression. So, particles small enough have the chance to exit the comminuting space GS altogether through the output OUT1 at the lower edge, which reduces the probability of product-sized (=the desired particle size) comminuting. When dealing with fine particle sizes, the exit of daughter pieces may be primarily boosted by a gas flow or, if further processing so dictates, with a fluid flow, such as water. When hot gas is used, the material being comminuted may be dried, or when a chemically appropriate inert gas is used (in other words, the proportion of nitrogen or carbon dioxide in the gas), it is possible to control the chemical state of the surfaces parts of the material particles. With a liquid flow, the redox state of the particles may be controlled, if it is justified to perform further processing with a flotation process.
As a summary, it may be set forth that: The compression of particles takes place freely, without side support by other particles or support points, whereby the growth of micro-cracks during compression is facilitated and the break occurs more easily. Compression takes mostly place in a layer of one particle, whereby the compression force of the conveyor surfaces B1, B2 is always focused directly on the particle and with a lower energy consumption that if a group of particles were compressed. Compression takes place slowly, whereby the energy used for breaking per a new surface area is the smallest. The compression of particles in the comminuting space GS is performed at different times as the particle size decreases and as successive events when the conveyor surfaces B1, B2 stop all the particles too big for a product according to their sizes at the height level according to the nip angle INCL-TD for further compression. Particles and daughter particles formed from them coming in with the incoming particle feed, the size of which is already small enough, do not after exiting affect the conveying or compression events of the conveyor surfaces B1, B2, so there will be no added friction or lower compression effect. In the comminuting space GS, only particles larger than the product size (which comes through the output OUT1) are conveyed and comminuted/crushed, whereby as little energy as possible is used for the conveying of the particles and the capacity of the comminuting space GS is used efficiently. With a gas or liquid flow opposite to the conveying direction, the exit of the product particles may be enhanced and the chemical state of new particles may be changed without interfering with the cracking events taking place in the comminuting space.
A person skilled in the art will find it obvious that, as technology advances, the basic idea of the invention may be implemented in many different ways. The invention and its embodiments are thus not restricted to the above-described examples but may vary within the scope of the claims.
Number | Date | Country | Kind |
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20165813 | Oct 2016 | FI | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FI2017/050743 | 10/27/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2018/078221 | 5/3/2018 | WO | A |
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2475936 | Feb 2002 | CN |
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Entry |
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International Search Report for PCT/FI2017/050743, dated Feb. 21, 2018, 4 pages. |
Written Opinion of the ISA for PCT/FI2017/050743, dated Feb. 21, 2018, 5 pages. |
Search Report for FI 20165813, dated Apr. 28, 2017, 1 page. |
Office Action for FI 20165813, dated Apr. 28, 2017, 4 pages. |
Search Report issued in EP Appln. No. 17865680.7 dated Jun. 15, 2020. |
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Number | Date | Country | |
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20190118189 A1 | Apr 2019 | US |