SLAG PROCESSING

Description

Field of invention

[0001] The present invention relates to the slag processing, in particular for recovering iron from this byproduct.

State of the art

[0002] Slag processing is disclosed in patent documents US 4 747 547, US 2013/0240415 and US 1 478 826.

[0003] EP 2 128 279 A1 describes a method for separating metal-containing fractions from slag comprising the successive steps of: Supplying the slag; processing the slag into fractions; pre-separating the fractions with a magnetic separator where substantially all iron-containing fractions are separated; and separating non-ferrous metal-containing fractions by using an eddy current separator.

[0004] WO 2009/089906 A1 describes a process for producing mortar or concrete comprising the steps of carbonating a fine fraction (24) of steel slag particles, containing a significant amount of y-dicalcium silicate, and then mixing at least this fine fraction (24) with at least a hydraulic binding agent and with water to produce said mortar or said concrete.

[0005] KR 2002 0074430 A describes a method and an apparatus for manufacturing aggregate using steelmaking slag is provided to use steelmaking slag as superior recycled product by installing a steelmaking slag recycling facility to crush steelmaking slag charged, remove foreign materials mixed in the slag, and age produced products, thereby remove sulfur.

[0006] Huiting Shen et al. analyzes and summarizes the generation, characteristics, and application of various slags, and discussed the potential effects of the slags on the environment as well as methods for recovery of metals from the slags.

[0007] WO 02/066164 A1 describes a facility for treating composite material containing metal as treating material, comprising a metal separator (22, 22a, 28) mounted upstream of an impact crushing mill (30, 50) -- and optionally an eddy current separator (54) mounted downstream of the impact crushing mill (30, 50) as device for separating the treating material by swirling.

[0008] Existing processes do not allow a complete recovery of iron from slag and are not fully integrated. They also not allow the separation of FeO.

General description of the invention

[0009] An object of the present invention is to provide a complete recovering of iron from slag.

[0010] Another object is to effectively break slag, in particular slag of relatively important size, typically above 300 mm.

[0011] Another object is to separate and recover FeO from slag.

[0012] Those and other objects are achieved with the system of the invention according to claim 1, which comprises a

[0013] Grizzly feeder adapted to separate a slag fraction of less than 60 mm, a single rotor crusher adapted to crush a slag sub-fraction of 30 to 60 mm, a centrifugal crusher adapted to crush a slag sub-fraction of less than 30 mm, and a drum magnet and a material spreader that are adapted for sorting said sub-fraction of less than 30 mm.

[0014] The inventors have surprisingly found that an efficient and complete iron recovery can be obtained when handling the above cited slag fractions. The "less than 30 mm" fraction is particularily useful for separating FeO.

[0015] The invention also relates to a method process according to claim 5 for slag processing comprising the following steps

• separating a slag fraction of less than 60 mm,
• crushing a slag sub-fraction of 30 to 60 mm,
• crushing a slag sub-fraction of less than 30 mm,
• sorting said sub-fraction of less than 30 mm by spreading the slag and imparting a magnetic force on it.

Detailed description of the invention

[0016] The invention will be better understood in the present chapter, with an illustrated non-limiting example.

Brief description of the figures

[0017] 

Figure 1 represents one system according to the invention.

Figure 2 illustrates an active free lime process

Figure 3 is a transparent view of a hydraulic breaker according to the invention

Figure 4 shows different positions of a hydraulic breaker according to the invention

Figure 5 illustrates the combination of a machine and a hydraulic breaker

[0018] The different elements that constitute the system are discussed below:

Grizzly feeder and pan feeder with hopper and chassis (1)

[0019] Slag is fed to the hopper by front loader, excavator or dumper. From hopper and Grizzly feeder (1) fraction 0-60 (100) mm is separated from the flow to conveyor line to Special crusher (4) passing the Jaw Crusher (3). Fraction 60-800 mm goes into a drum screen (2).

Drum screen RS 220 (2)

[0020] Drum screen, diameter 2,2 m, is made of highly wear-resistant steel. Slag is divided into 60- 300 mm and over 300 mm fractions. (Opening of the screen can be on range 200 - 300 mm). Drum is supported with four rubber wheels. There are 2 x 22 kW electric gear motor drives.

[0021] The drum speed is variable.

[0022] From drum screen fraction app 60-300 mm goes into a conveyor line and to Jaw Crusher (3). Pieces over 300 mm will be crushed by hydraulic breaker (12).

Special crusher

[0023] Special crusher (4) is fed by fraction 30-60mm. This crusher breaks the slag guaranteeing complete metal recovery. Crushed material goes by conveyor line to the screen (5).

Jaw Crusher with Automatic Metal Piece Control (3)

[0024] Robust Jaw Crusher (3) are designed for high performance, in order to achieve the lowest possible operating cost per ton of end product produced. Performance has been optimized through solid cavity design and kinematics. The robust Jaw Crusher feature a long stroke, optimized operating speed, and an aggressive motion of the pitman.

[0025] The crusher is fed by 60-300mm slag (no thicker metal pieces than 340mm). Materials are crushed in smaller fractions. Automatic metal piece control (AMPC) let unbroken pieces going thru without causing damage to Crusher. Materials continue with conveyor (6) to the inclined heavy-duty screen (5).

Inclined heavy-duty screen (5)

[0026] The screen is a horizontal with double decks. The top screen is very durable wire deck.

[0027] 0-300 mm slag will be screened to 0 - 30 mm, 30 - 60 mm and 60 - 300 mm fractions.

[0028] These fractions are very important that magnetic separators can be adjusted to optimize separation. 60 - 300 mm fraction goes from top deck (over size) to magnet (7).

[0029] 30 - 60 mm fraction goes from bottom deck (over size) to magnet (6).

[0030] 0 - 30 mm fraction goes through bottom deck (under size) by conveyor line via surge bin () to the conveyor and to High-Speed Centrifugal crusher (11) and then to special magnet (9).

Magnet IM 1200(7)

[0031] Magnet is for fraction 60 - 300 mm.

[0032] Magnet is belt drum magnet (7) where diameter of the drum is specified for this fraction. Inside of the drum is permanent magnet which position is fully adjustable.

[0033] Divider plate will guide steel scrap and slag to right conveyors. Position of the divider plate is fully adjustable.

[0034] Magnetic metal pieces will go to conveyor and to cleaning drum (8). Slag will go to conveyor and to the Jaw crusher.

Magnet PM630(8)

[0035] Magnet for fraction 30 - 60 mm.

[0036] Magnet is belt drum magnet where diameter of the drum is specified for this fraction. Inside of the drum is permanent magnet which position is fully adjustable.

[0037] Divider plate will guide steel scrap and slag to right conveyors. Position of the divider plate is fully adjustable.

[0038] Magnetic metal pieces will go to conveyor and to cleaning drum (8). Slag > 30 mm will go to the Special crusher (4) and back to the screen (5).

Special Crusher IC220 (4)

[0039] Special crusher (4) for fraction 30-60mm crushing. This crusher breaks the slag guaranteeing complete metal recovery. Crushed material goes by conveyor line to the screen (5).

Cleaning drum PR3000(8)

[0040] Magnetic metal pieces in fractions 30 - 60 and 60 - 300 are cleaned from slag residues in cleaning drum (8).

[0041] Magnetic metal pieces is fed to drum with conveyor. Diameter of the drum is 3.0 m. There are lifters, which lift metal pieces up. This rotation causes autogenous cleaning where falling of metal pieces will liberate slag residues. When metal pieces drop on steel bed on bottom there is very small amount of wearing.

[0042] Inside of the drum is manufactured with high wear-resistant steel.

[0043] In discharge end of the drum, there are two screening drums with openings #60 mm and #30 mm.

[0044] 60 - 300 mm fraction falls out at the end of the drum, and it is ready to be loaded. Metal concentration in this product is high, usually above 85%.

[0045] 30 -60 mm fraction goes to conveyor and to stockpile. Metal concentration in this product is still high, usually above 80%.

[0046] 0 - 30 mm fraction goes to conveyor and to High-Speed Centrifugal crusher (11). Metallic iron is bound with the lime and that is why it need to be crushed by High-Speed Centrifugal crusher.

[0047] Cleaning Drum is supported with four rubber wheels.

Surge bin for LF slag feeding (13)

[0048] The LF slag-processing utilizes a smaller equipment footprint since the slag is already in a small size and can be fed, screened, and run through a specialized centrifugal mill for crushing and metallic separation. To maximize the utilization of equipment capacity and reduce the footprint of the plant.

[0049] The plant process LF slag in the same high speed centrifugal crusher as the steel slag and then continue through the same processing equipment.

[0050] Because of the significant amount of calcium aluminate in ladle furnace slags, which is the main compound of ladle fluxes, the remaining LF slag fines after metal recovery are best used back in the Ladle Furnace as a fluxing agent.

[0051] These fluxes are widely used to clean steel production processes. Hence, using of ladle furnace slags as a part of ladle fluxes can be considered as an economic recovery for these materials.

High-Speed Centrifugal Crusher (11)

[0052] The High-Speed Centrifugal crusher (11) is for crushing the steel slag in fraction 0-30 mm. This mill liberates rest of metallic pieces from lime and silicate. Crushed material goes by conveyor to the fine magnet (9).

[0053] With high performance impact (160 m/s) with a vertical shaft, outer and inner special rotors with special hard metal impact pins.

• The input material is fed from above into the center of the centrifugal mill. Material is thrown from the inner rotor to the opposite direction rotating outer rotor by high-speed centrifugal force.
• The input material hits to the outer rotor impact pins at high speed. This leads to an optimized impact resulting effective liberating for the metallic particles and pieces from the lime.
• The twin rotor eliminates the risk of clogging and allow high throughput rates.
• High throughput rates
• Reduced risk of clogging
• Directed material acceleration
• Optimal energy efficiency
• Reduced wearing of the materials
• Increase rapidly the recovery of Fe-metals from smaller than 30 mm slag fines
• Unique high-speed centrifugal mill with ring speed 160meter/second
• Twin rotors rotating in opposite directions
• Special hard metal impact pins
• No stacking
• Hydraulic cover opening for maintenance

Special magnet HM 900 with material spreaders (9)

[0054] Special magnet for fraction 0 - 30 mm.

[0055] Magnet is High Speed drum magnet with High Intensity magnet field, where diameter of the drum is specified for this fraction. Inside of the drum is permanent, high intensity magnet, which position is fully adjustable.

[0056] This enables the efficient separation of fine metal grains. There is electric motor drive and adjustable rotation speed.

[0057] Material spreaders expand the slag for the whole width of the magnet, in this way the magnet separation is more efficient, and flow can be higher. Material spreader is designed for the harsh environment against material sticking.

[0058] Divider plate will guide magnetic pieces and slag to right conveyors. Position of the divider plate is fully adjustable.

[0059] Metals 0 - 30 mm will go by conveyor to Flip flop screen (10) and to storage silos. Slag 0 - 5 mm will go by conveyor to storage silo.

Special Screen (10 and 14)

[0060] Screen is a horizontal flip flop screen with one deck. The screen is very durable 60 mm rubber screen. Deck has surface area app 15 m2.

[0061] 0-30 mm slag metals will be screened to 0-2 mm and 2 - 30 mm fractions. 2 - 30 mm fraction goes over the deck (over size) to conveyor and silo.

[0062] 0-2 mm fraction goes through the deck (under size) by conveyor to the storage silo.

[0063] 0-5 mm non-magnetic slag go to storage silo.

Hydraulic breaker (12)

[0064] This machine is used for effectively braking slag of relatively important size, i.e. above 300 mm. Its main componets are described below (see also figures 3, 4 and 5).

a) Carrier machine: Stationary carrier machine with legs or mobile version with tracks. Power is produced by electric current or by diesel engine.

b) Chassis: This consists mainly of the main pipe in which the hammerhead and coupler operates.

c) Power train: This consists mainly of adouble luff, which operates on 2 slide bars. A hydraulic double acting main cylinder, which expands and lifts the hammerhead and coupler to the top of the chassis.

d) Hammer head: The hammer head runs inside the chassis and consists of several parts. One replaceable hammer point and one ballast block. Moreover, there is a carriage with rollers that control the hammer head as it falls freely through the base. which control the hammerhead as it falls freely through the chassis. The hammerhead weight is preferably between 4 and 8 tons. It may generate an impact energy between 200 000 and 400 000 Joules, depending on its weight and dropping height.

e) Coupler: The Power train activates a wire, which lifts the coupler. The coupler has electromagnet catcher. The magnet field activates when the coupler reaches the hammerhead and catcher attaches itself to the lifting tap. The coupler has a mechanical locking to prevent the head from falling in the event of a power failure.

f) Carrier machine coupler: The hydraulic coupler is the attachment to the carrier machine.

[0065] The following description refers to figure 4 which shows a basic work cycle. The breaker has a hydraulic drop hammer. The principle of operation is as follows:

1. Place the hammer upon the surface of the object - 1

2. The hydraulics of the carrier machine lifts the hammerhead to the top of the pipe -

3. The coupler releases as it reaches the highest limitation of the chassis.

4. When the coupler is released the hammerhead falls freely toward the object, upon which the hammer is placed -3

5. When the hammerhead impacts the object, the energy from the hammerhead is transferred to the object and it will split depending upon the material.

6. The coupler lowers onto the hammerhead - 4

7. When the coupler reaches the hammer head it attaches itself to the lifting tap and the breaker is ready to repeat the process.

[0066] As the breaker to a large proportion only requires lifting the hammerhead the only other active force being the earth's gravitational force it means that this breaker is a very cost-effective tool. The hammerhead drops by its own weight on the object without the use of active propellants. Thus, the operation principle is free of the vibrations known from other splitting methods, which significantly extend the wear life of the carrier machine while improving.

Active free lime process (figure 2)

[0067] The invention also concerns the production and stabilization of active free lime from slag tailings n fraction 0-5 mm.

[0068] The resulting product comes from the slag processing process. It is a unique ecological product which binds carbon dioxide from the air, because of the multiplied surface area.

[0069] The product can be recycled and 100% reused in replacing cement in concrete production.

1. In the process slag tailings are grinded in to fraction below 50 microns.

2. While the grinding of the slag, environmentally friendly ingredients are fed into slag. It helps deactivating active free lime from slag.

3. For every ton of product used in replacement of cement in concrete production, CO2 emissions are reduced by 500 kg.

Claims

1. System for slag processing comprising a Grizzly feeder (1) configured to separate a slag fraction of less than 60 mm, a special crusher (4) configured to crush a slag sub-fraction of 30 to 60 mm, a centrifugal crusher (11) configured to crush a slag sub-fraction of less than 30 mm, a drum magnet (9) and a material spreader configured to sort said sub-fraction of less than 30 mm, characterized in that the material spreader is further configured to expand said sub-fraction of less than 30 mm across the whole width of the drum magnet (9).

2. System according to claim 1, comprising at least one flip-flop screen for sorting said sub-fraction of less than 30 mm.

3. System according to claims 1 or 2, comprising a jaw crusher (3) configured to crush a slag fraction of 60 to 300mm.

4. System according to anyone of claims 1 to 3, comprising an hydraulic breaker configured to crush a slag fraction of more than 300mm.

5. Method for slag processing comprising the following steps:

- separating a slag fraction of less than 60 mm,

- crushing a slag sub-fraction of 30 to 60 mm,

- crushing a slag sub-fraction of less than 30 mm,

- sorting said sub-fraction of less than 30 mm by expanding said sub-fraction of less than 30 mm across the whole width of a drum magnet and imparting a magnetic force on it.

Ansprüche

1. System zur Schlackenverarbeitung, umfassend einen Stabrostbeschicker (1), der dazu ausgelegt ist, einen Schlackenanteil von weniger als 60 mm abzusondern, einen Spezialbrecher (4), der dazu ausgelegt ist, einen Schlackenunteranteil von 30 bis 60 mm zu zerkleinern, einen Zentrifugalbrecher (11), der dazu ausgelegt ist, einen Schlackenunteranteil von weniger als 30 mm zu zerkleinern, einen Trommelmagneten (9) und einen Materialverteiler, der dazu ausgelegt ist, den einen Unteranteil von weniger als 30 mm zu sortieren, dadurch gekennzeichnet, dass der Materialverteiler ferner dazu ausgelegt ist, den Unteranteil von weniger als 30 mm über die gesamte Breite des Trommelmagneten (9) auszubreiten.

2. System nach Anspruch 1, umfassend mindestens ein Kippsieb zum Sortieren des Unteranteils von weniger als 30 mm.

3. System nach Anspruch 1 oder 2, umfassend einen Backenbrecher (3), der dazu ausgelegt ist, einen Schlackenanteil von 60 bis 300 mm zu zerkleinern.

4. System nach einem der Ansprüche 1 bis 3, umfassend einen Hydraulikbrecher, der dazu ausgelegt ist, einen Schlackenanteil von mehr als 300 mm zu zerkleinern.

5. Verfahren zur Schlackenverarbeitung, das die folgenden Schritte umfasst:

- Absondern eines Schlackenanteils von weniger als 60 mm,

- Zerkleinern eines Schlackenunteranteils von 30 bis 60 mm,

- Zerkleinern eines Schlackenunteranteils von weniger als 30 mm,

- Sortieren des Unteranteils von weniger als 30 mm durch Ausbreiten des Unteranteils von weniger als 30 mm über die gesamte Breite eines Trommelmagneten und Aufbringen einer magnetischen Kraft darauf.

Revendications

1. Système de traitement de scories comprenant un dispositif d'alimentation à grille (1) conçu pour séparer une fraction de scories de moins de 60 mm, un concasseur spécial (4) conçu pour concasser une sous-fraction de scories de 30 à 60 mm, un concasseur centrifuge (11) conçu pour concasser une sous-fraction de scories de moins de 30 mm, un séparateur magnétique à tambour (9) et un épandeur de matériaux conçu pour trier ladite sous-fraction de moins de 30 mm, caractérisé en ce que l'épandeur de matériaux est en outre conçu pour épandre ladite sous-fraction de moins de 30 mm sur toute la largeur du séparateur magnétique à tambour (9).

2. Système selon la revendication 1, comprenant au moins un tamis à bascule pour trier ladite sous-fraction de moins de 30 mm.

3. Système selon la revendication 1 ou 2, comprenant un concasseur à mâchoires (3) conçu pour concasser une fraction de scories de 60 à 300 mm.

4. Système selon l'une quelconque des revendications 1 à 3, comprenant un brise-roche hydraulique conçu pour concasser une fraction de scories de plus de 300 mm.

5. Procédé de traitement de scories comprenant les étapes suivantes :

- séparation d'une fraction de scories de moins de 60 mm,

- concassage d'une sous-fraction de scories de 30 à 60 mm,

- concassage d'une sous-fraction de scories de moins de 30 mm,

- tri de ladite sous-fraction de moins de 30 mm en épandant ladite sous-fraction de moins de 30 mm sur toute la largeur d'un séparateur magnétique à tambour et en lui appliquant une force magnétique.

Drawing