WO2015007560A1

WO2015007560A1 - Crusher device

Info

Publication number: WO2015007560A1
Application number: PCT/EP2014/064485
Authority: WO
Inventors: Paul Tockert; Christian De Gruiter
Original assignee: Paul Wurth S.A.
Priority date: 2013-07-18
Filing date: 2014-07-07
Publication date: 2015-01-22
Also published as: LU92259B1; TW201509531A

Abstract

A crusher device (101, 201) for breaking up solidified slag cakes by gravity impact and evacuating the broken slag pieces, said crusher device comprising an impact grid (110) for receiving falling slag cakes, at least two support stands (120) having an upper and a lower end, wherein the upper end of each support stand (120) is attached to the impact grid (110) and the lower end is securable to the ground, wherein the impact grid (110) is arranged at an angle α between 10 and 40° relative to the horizontal, and wherein each support stand (120) comprises a passive vibrating element (122, 300), said vibrating element integrating a spring arrangement.

Description

CRUSHER DEVICE

Technical field

[0001 ] The present invention generally relates to granulation of slag from the metal industry, such as from the iron industry, and more particularly to the so- called dry slag granulation technology.

Background Art

[0002] Conventionally, metallurgical slag is granulated in water. Water quenching ensures fast solidification of the metallurgical slag, which, in the case of blast furnace slag, is a necessary condition for obtaining a valuable product.

[0003] More recently, an alternative solution for slag granulation has been proposed, the so-called dry slag granulation process, in which (cold) solid metallic particles are added to the hot liquid slag inside a mould to form a mixed slag- particle cake (WO 2012/034897, WO 2012/080364). The effect is that the slag rapidly solidifies in a vitreous state without requiring huge amounts of cooling water and without producing noxious gases. Furthermore, the solid metallic particles are chemically inert and may be easily separated, recovered and reused by breaking up the mixed slag-particle cake (see WO 2012/034897). Additionally, the heat from both solidified slag and metallic particles may be recovered in an appropriate device, such as a heat exchanger (see WO 2012/080364).

[0004] To fully benefit from the dry slag granulation process, it is therefore important to break up the mixed slag-particle cake to a sufficient degree to allow for the subsequent processing. Furthermore, in view of the quantities of slag produced in common metallurgical installations and to ensure appropriate working rates, the weight of typical slag-particle cakes is from 1000 to 10000 kg.

[0005] It has been proposed among others to drop the slag-particle cake out of the mould from a certain height onto a so-called impact plate where the slag cake is broken into smaller pieces. In practice, such an impact plate must not only be suitable to break up the cake, but it should also integrate means capable of evacuating the broken slag pieces. A further practical constraint is that such an evacuation should happen in a relatively short time, as the slag cakes usually are dropped at regular intervals from an endless conveyor type casting machine. A typical time to evacuate can be as short as a few seconds.

[0006] One possibility to obtain these two effects of breaking and evacuating is to provide an impact plate having a certain angle or slope relative to the horizontal. However, if this angle is too flat, the slag cake breaks but might not evacuate the plate at all or not without providing further means, such as a scraper or equivalent. Furthermore, the presence of broken slag pieces on the plate might prevent or at least impede the appropriate breaking of the next cake.

[0007] On the other hand, if this angle is too steep (which evidently increases the rate of evacuation due to gravity), the slag cake might not (sufficiently) break and, even worse, be projected as a whole massive block with all the potential risks associated with such a projection.

[0008] Other methods for breaking up a slag-particle cake that may be taken into consideration include conventional crushers, such as jaw or drum crushers. A major disadvantage of such (active) devices is however that they generally require substantial amounts of energy during operation and important maintenance efforts due to the heavy load and wear to which they are exposed.

Technical problem

[0009] It is therefore an object of the present invention to provide an apparatus or device, as well as a method allowing for effectively and efficiently breaking up slag-particle cakes, while permitting high working rates. Said apparatus, device and method should furthermore allow to rapidly evacuate the broken up slag pieces and particles, preferably without requiring complex and expensive auxiliary equipment.

General Description of the Invention

[0010] To achieve this object, the present invention therefore proposes, in a first aspect, a crusher device for breaking up solidified slag cakes by gravity impact and for evacuating the broken slag pieces, comprising an impact grid for receiving falling slag cakes, at least two, preferably three or more preferably four support stands having an upper and a lower end. The upper end of each support stand is attached to the impact grid and the lower end is securable to the ground. The impact grid is arranged at an angle a between 10 and 40° relative to the horizontal. Each support stand comprises a passive vibrating element integrating a spring arrangement.

[001 1 ] In practice, it appears that the requirements for high breaking power and high evacuation rates of a conventional impact plate type device are incompatible. The increase of the plate angle enhances the evacuation rate, but at the cost of a reliable breaking up of the cake and general safety at the surroundings of the device.

[0012] Hence, if an impact plate type device with a reliable and efficient breaking up of the slag cakes (relatively flat slope) were to be used, some kind of additional evacuation means and equipment was to be provided to address the deficiencies in promptly clearing the impact plate before the next impact. Furthermore, in view of the size and weight of the slag cakes, any solution proposed must be able to withstand high impact forces and heavy wear conditions.

[0013] Instead of addressing the evacuation of the material from the impact plate by additional dedicated means known for evacuating material from a surface, such as adding scrapers or providing means to temporarily change the slope of the plate between impacts, it has been found that by replacing the plate by a grid and by providing the above-mentioned passive vibrating elements, two apparently opposed requirements of adequate breaking up and prompt evacuation can be reconciled in a simple yet efficient way. It is to be noted that in the context of the present invention the expression "passive vibrating element" means that no additional actuator and no external power source is required to produce the desired vibration.

[0014] Hence, such a device does not only allow to efficiently break up slag and mixed slag-particle cakes dropped from a certain height, generally from 2 to 8 m, on the impact grid, thereby being exposed to huge impact forces. It also ensures a rapid evacuation of the broken up material (slag pieces and metallic particles) both by falling through the grid for pieces smaller than the distance between grid bars and by sliding down the grid for larger pieces due not only to gravity, but also due to the shaking effect of the passive vibrating element. [0015] In fact, the advantages of the device as presented herein are manifold:

• almost instantaneous evacuation of a significant part of the material directly through the impact grid,

• a more even flow of the rest of the material from the grid due to a more uniform distribution of the material on the grid, itself due to the short, yet effective impulse/rebound provided by the passive vibrating element,

• entirely passive solution swerving part of the impact energy to enhance evacuation, i.e. without requiring external energy,

• no moving and/or protruding parts or cumbersome tools, such as scrapers or the like, in the impact zone and hence no risk of damaging and no need to service such parts and tools,

• low operating and maintenance costs,

• low sensitivity to dust, and

• low sensitivity to harsh exterior temperature conditions.

[0016] A spring arrangement in the context of the present invention may be any device capable of temporarily storing at least part of the impact energy for conversion into a vibrating action. Hence, a suitable spring arrangement may be any compression or torsion type spring, such as helical springs; washer spring arrangements; friction spring arrangements or open or closed cell metal foams. Preferably the spring arrangement in the crusher device is a friction spring arrangement.

[0017] Friction springs or friction spring arrangements as used herein are known in the art. One particularly appropriate type consists of a series of separate inner and outer mating tapered rings which stack together to form a column or stack. A stack generally includes from two to 50 (or more if required or desirable), preferably from 10 to 40 rings. Inner and outer rings alternate down the length of the friction spring; under application of axial load, the wedge action of the taper faces expands the outer rings and radially contracts the inner rings.

[0018] In a further aspect, the crusher device comprises passive vibrating elements wherein the spring arrangement, preferably the friction spring arrangement is pre-tensionable. The advantage of pre-tensioning the (friction) spring arrangement is that the amplitude of the vibrating movement can be controlled, depending on the extent of vibration desired or required. Pre-tensioning arrangements are known and an appropriate solution can be based on a nut and bolt type system where the friction spring is pre-compressed between two spring seats by tightening or loosening the nut.

[0019] In a still further aspect, at least some of the vibrating elements comprise vibration control means counteracting the (friction) spring arrangement. Controlling the recoil of the (friction) spring arrangement allows containing the ricochet effect on the material and thus prevents material from being spread around the device. Appropriate vibration control means comprise (further) springs acting as a counter spring to the (friction) spring arrangement, such as helical springs, washer spring arrangements (also called Belleville springs) or elastomers. To still further control or to be able to fine tune the (friction) spring arrangement recoil, the counter spring may also be provided with a pre-tensioning system, such as a nut and bolt system similar to that described above. An appropriate control of the counter spring arrangement also contributes to reduce undesirable dust emissions.

[0020] The impact grid preferably comprises a number of spaced apart parallel grating bars attached by a number of transverse elements. The grating bars are preferably steel bars mounted on edge of appropriate thickness and width to withstand the impact forces and wear of such a device. The distance between adjacent grating bars depends on the material to be treated. However, this distance is generally between 0.1 and 0.5 m, preferably between 0.3 and 0.4 m.

[0021 ] The material falling through the impact grid and the material sliding down said grid are ready to be further processed, such as for recovering heat and recycling the metallic particles (e.g. as described in the patent documents cited in the introduction).

[0022] In one embodiment, the material from the impact grid is channelled to a discharge region close to the crusher device, such as by providing a material chute beneath the impact grid. In a preferred embodiment, the chute is suspended to the impact grid, such as by means of rods. A particular advantage of this alternative is that the vibration of the impact grid will also serve to enhance evacuation of the material from the chute. Such a material chute is preferably arranged at an angle β between 15 and 60° relative to the horizontal.

[0023] Other collecting/moving devices can be used beneath the impact grid to collect and/or move the crushed material to any subsequent treatment, such as in particular a belt type conveyor.

[0024] In a still further aspect, the invention also encompasses a method for crushing slag cakes, wherein the slag cakes are dropped on an impact grid arranged at an angle a between 10 and 40° relative to the horizontal, said impact grid being mounted on at least two, preferably four support stands having an upper and a lower end, wherein the upper end of each support stand is attached to the impact grid and the lower end is secured to the ground, each support stand comprising a passive vibrating element integrating a spring arrangement, preferably a friction spring arrangement, to enhance evacuation of the crushed slag material from the grid. In particular, the invention also concerns the use of any embodiment, variant, alternative or preferred feature combination of the crusher device as described herein.

[0025] In a further aspect, the invention also relates to a method for dry slag granulation of hot liquid slag using a casting apparatus comprising casting moulds. Such a method generally comprises the steps of: a) pouring an amount of hot liquid slag into a casting mould,

b) adding solid metallic particles to the hot liquid slag containing casting mould,

c) cooling the metallic particles-slag mixture form step (b) to obtain a solidified slag cake, and

d) dropping the solidified slag cake from the mould on a crusher device as described herein or using the above method.

[0026] Finally, the invention also covers a slag treatment installation or plant comprising a crusher device as herein described.

Brief Description of the Drawings

[0027] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a schematic side view of one embodiment of a device according to the invention;

Fig. 2 is a schematic side view of a further embodiment of a device according to the invention;

Fig. 3 is a cross sectional view of a preferred embodiment of a passive vibrating element usable in a device according to the invention; and

Fig. 4 is a schematic top view of an embodiment of an impact grid usable in a device according to the invention.

[0028] Further details and advantages of the present invention will be apparent from the following detailed description of several not limiting embodiments with reference to the attached drawings.

Description of Preferred Embodiments

[0029] Fig. 1 is schematic representation of a preferred embodiment of a device 101 for breaking up solidified slag cakes by gravity impact and for simultaneously evacuating the broken slag pieces. Such a device is able to withstand huge impact forces. As an example, the impact energy acting on the grid for a slag cake having a mass of 4 t falling from a height of 2.5 m amounts to about 100000 J, or in other words forces corresponding to about 1750 t are acting on the grid at a rate of one impact every few seconds. The device of Fig. 1 comprises an impact grid 1 10 mounted to four support stands 120 by means of grid hinged mountings 123. The support stands 120 are safely secured to the ground by base plates 125.

[0030] Each of the support stands 120 comprises a passive vibrating element 122 (such as e.g. a vibrating element 300 as shown in Fig. 3) and preferably a spacer element 121 to yield the desired height and/or slope a of the assembly. As will be more clearly described in relation with Fig. 3 (see below), such a vibrating element 122 generally comprises two concentric telescoping sliding sleeves (see e.g. 310 and 350 in Fig. 3) with an inner spring arrangement, preferably a friction spring arrangement. [0031 ] To permit for a certain degree of movement of the grid 1 10 when hit by a slag cake, two of the support stands 120 further comprise a base hinged mounting 124, whereas the other support stands are secured to the ground without hinge.

[0032] The impact grid 1 10 basically comprises grating bars 1 101 (not visible in Fig. 1 , see Fig. 4) arranged in parallel in the direction of the intended flow down from the upper to the lower side of the grid 1 10. These grating bars 1 101 are spaced apart by transverse elements 1 102 (not visible in Fig. 1 , see Fig. 4) at an appropriate distance, such as e.g. 0.1 to 0.5 m. It is clear that grating bars 1 101 , preferably flat steel bars mounted on edge, must be correctly dimensioned to withstand the huge forces generated on impact. The impact grid 1 10 preferably also comprises on its sides lateral splashboards 1 103 having a certain height above the grid to help laterally ejected slag pieces to either stay on the grid or to fall through it depending on their size. The impact grid 1 10 may also comprise lateral deflectors 1 104 below the plan of the grid 1 10 to guide the falling pieces e.g. into the chute 130.

[0033] Indeed, the embodiment of Fig. 1 further comprises a chute or runner 130 suspended by connecting rods 131 with an angle β below the impact grid 1 10. A particular advantage of this configuration is that the vibration impulse of the impact grid 1 10 is passed to chute 130 thereby also accelerating the evacuation of the slag pieces. Indeed, when a slag cake hits the grid 1 10, the smaller pieces of the broken cake directly fall through the impact grid 1 10 on said chute 130 and slide down this chute due to gravity.

[0034] Fig. 2 is schematic representation of a further, preferred embodiment of a device 201 for breaking up solidified slag cakes, said device comprising an impact grid 1 10 mounted to four support stands 120 by means of grid hinged mountings 123. The support stands 120 are safely secured to the ground by base plates 125.

[0035] The basic design of the impact grid 1 10 mounted on support stands 120 as shown in Fig. 2 is similar to that of the corresponding elements in Fig. 1 . The major difference is that the chute is replaced by a conveyor 240, such as a belt conveyor, directly below the device. Contrary to the chute, the conveyor is not connected to the impact grid 1 10. In order to facilitate and control the feeding of the conveyor, a collector 250 may be provided wherein the material is collected in a hopper 251 and distributed on the conveyor 240 by means of charger 252. In further embodiments, collector 250 may integrate a controllable material gate (not shown) to regulate the flow of material on the conveyor 240. Furthermore, collector 250 may also integrate or be replaced by and/or an active crusher unit (not shown) to further reduce the size of the material and/or to crush cake pieces which did not sufficiently fragment on impact.

[0036] Fig. 3 is a cross-sectional view of a passive vibrating element 300 with a friction spring arrangement, which may be used in the context of the present invention, for example as vibrating element 122 in Fig. 1 and 2. It is to be understood that Fig. 3 shows optional elements not required to benefit from the described vibrating or shaking effect.

[0037] In one of its most simple forms, a passive vibrating element useable in the present invention comprises an upper sleeve 310 slidingly inserted in a lower sleeve 350. Inside this assembly, a friction spring arrangement made of a stack of a number of alternating inner and outer friction rings 31 1 and 312 is arranged to dissipate some of the impact energy to heat and, more importantly, to convert part of it to convey a vibrating or shaking effect of the impact grid 1 10 (and, if applicable, to a suspended chute 130, as shown in Fig. 1 ). A bellow type sealing (not shown) may be provided between lower and upper sleeve to prevent dust from entering the vibrating element.

[0038] In a further preferred embodiment (additional elements also shown in Fig. 3), the (friction) spring arrangement may be pre-tensioned by providing e.g. lower and upper friction spring seats 320, 321 , as well as a pre-tensioning arrangement, such as a bolt and nut assembly (e.g. pre-tensioning shaft 322, nut 324 and nut lock 325 in Fig. 3). The pre-tensioning of the (friction) spring allows to control the amount of energy to allocate to the shaking/vibrating of the grid, the more the friction spring is pre-tensioned, the lower the amplitude of the shaking/vibrating will be.

[0039] In a still further preferred embodiment (additional elements also shown in Fig. 3), the passive vibrating element 300 may also comprise a counter spring arrangement 331 , advantageously also pre-tensionable as shown in Fig. 3: counter spring 331 is secured between lower and upper spring seats 332, 334 by means of a nut and bolt assembly 333, 335, 336.

[0040] The counter spring arrangement allows controlling the speed of the rebound of the (friction) spring arrangement. This may be used to avoid that the material is projected back after the impact of the slag cake.

[0041 ] In such a configuration both spring and counter spring arrangements are preferably positioned concentrically as shown in Fig. 3. Other configurations are of course also within the context of the invention.

[0042] Fig. 4 presents a top view of a preferred embodiment of an impact grid 1 10, comprising a number of spaced apart grating bars 1 101 (in this case 7 bars) assembled on edge and held together by transverse elements 1 102. In Fig. 4, two of these spacer elements 1 102 are provided with mounting pins 1 105 for receiving the grid hinged mountings 123 of the respective support stands 120.

[0043] Fig. 4 also shows on each side of the impact grid 1 10 a lateral splashboard 1 103 projecting outwardly and at a certain height above the grating bars 1 101 . Below the grating bars 1 101 , lateral deflectors 1 104 are arranged to guide the material into the chute or conveyor (not shown).

Legend:

101 , 201 Device for breaking up solidified slag cakes

1 10 Impact grid

1 101 Grating bar

1 102 Transverse element

1 103 Lateral splashboard

1 104 Lateral deflector

1 105 Mounting pin for grid hinged mounting

120 Support stand

121 Spacer element

122, 300 Passive vibrating element

123 Grid hinged mounting

124 Base hinged mounting

125 Base plate

130 Chute, runner

131 Connecting rod

240 Conveyor

250 Collector

251 Hopper

252 Charger

310 Upper sliding sleeve

31 1 Inner friction ring of a friction spring arrangement

312 Outer friction ring of a friction spring arrangement

320 Lower friction spring seat

321 Upper friction spring seat

322 Friction spring pre-tensioning shaft

324 Friction spring pre-tensioning nut

325 Friction spring pre-tensioning nut lock

330 Counter spring pre-tensioning shaft

331 Counter spring

332 Lower counter spring seat

333 Lower counter spring nut

334 Upper counter spring seat

335 Counter spring pre-tensioning nut

336 Counter spring pre-tensioning nut lock

350 Lower sliding sleeve

Claims

1 . A crusher device (101 , 201 ) for breaking up solidified slag cakes by gravity impact and evacuating the broken slag pieces, comprising

an impact grid (1 10) for receiving falling slag cakes,

at least two, preferably four support stands (120) having an upper and a lower end, wherein the upper end of each support stand (120) is attached to the impact grid (1 10) and the lower end is securable to the ground,

wherein the impact grid (1 10) is arranged at an angle a between 10 and 40° relative to the horizontal,

wherein each support stand (120) comprises a passive vibrating element (122, 300), said passive vibrating element integrating a spring arrangement.

2. The crusher device as claimed in claim 1 , wherein said spring arrangement is a friction spring arrangement.

3. The crusher device as claimed in claim 1 or 2, wherein said spring arrangement is pre-tensionable.

4. The crusher device as claimed in any of claims 1 to 3, wherein at least some of the passive vibrating elements comprise vibration control means counteracting the spring arrangement.

5. The crusher device as claimed in claim 4, wherein vibration control means comprises a helical spring, a washer ring arrangement or an elastomer.

6. The crusher device as claimed in claim 4 or 5, wherein vibration control means is pre-tensionable.

7. The crusher device as claimed in any of claims 1 to 6, wherein the impact grid comprises a number of spaced apart parallel grating bars attached by a number of transverse elements.

8. The crusher device as claimed in claim 7, wherein the distance between adjacent grating bars is between 0.1 and 0.5 m, preferably between 0.3 and 0.4 m.

9. The crusher device as claimed in any of claims 1 to 8, further comprising a material chute suspended beneath the impact grid.

10. The crusher device as claimed in claim 9, wherein the material chute (130) is arranged at an angle β between 10 and 60° relative to the horizontal.

1 1 . A method for crushing slag cakes by gravity impact and evacuating the broken slag pieces, wherein slag cakes are dropped on an impact grid arranged at an angle a between 10 and 40° relative to the horizontal, said impact grid being mounted on at least two, preferably four support stands having an upper and a lower end, wherein the upper end of each support stand is attached to the impact grid and the lower end is secured to the ground, each support stand comprising a passive vibrating element integrating a spring arrangement to enhance evacuation of the crushed slag material from the grid.

12. The method as claimed in claim 1 1 using a crusher device as claimed in any of claims 1 to 10.

13. A method for dry slag granulation of hot liquid slag using a casting apparatus comprising casting moulds, the method comprising the steps of:

a) pouring an amount of hot liquid slag into a casting mould,

d) dropping the solidified slag cake from the mould on a crusher device as claimed in any of claims 1 to 10 or using a method as claimed in claim 1 1 or 12.