Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B3/00—General features in the manufacture of pig-iron
  • C21B3/04—Recovery of by-products, e.g. slag
  • C21B3/06—Treatment of liquid slag
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/14—Waste materials; Refuse from metallurgical processes
  • C04B18/141—Slags
  • C04B18/142—Steelmaking slags, converter slags
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/14—Waste materials; Refuse from metallurgical processes
  • C04B18/141—Slags
  • C04B18/145—Phosphorus slags
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B5/00—Treatment of  metallurgical  slag ; Artificial stone from molten  metallurgical  slag 
  • C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/04—Working-up slag
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B2400/00—Treatment of slags originating from iron or steel processes
  • C21B2400/02—Physical or chemical treatment of slags
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B2400/00—Treatment of slags originating from iron or steel processes
  • C21B2400/04—Specific shape of slag after cooling
  • C21B2400/044—Briquettes or moulded bodies other than sheets
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• the present invention relates to a method for treating a calcium silicate-containing molten slag formed during a metallurgical process according to the preamble of Claim 1. Furthermore, the invention relates to a device according to the preamble of Claim 16. In addition, the invention relates to a method according to Claim 21.
• one of the byproducts formed is a calcium silicate-containing residue stream in the form of a molten slag.
• this residue stream is referred to as a steel slag, and this molten slag is produced both in the production of pig iron and in the refining of the pig iron to steel.
• thermal phosphorus production the residue stream is referred to as phosphorus slag.
• These calcium silicate-containing molten slags are characterized by a high content of mineral components (mostly silicon and aluminium compounds).
• a composition of a steel slag which has been determined, for example, by x-ray fluorescence analysis typically contains CaO (40-50%), Si0 2 (10-20 %) , A1 2 0 3 (1-3%), MgO (5-10%), FeO (10-40%) and a small amount of Na 2 0 ( ⁇ 1%) as components.
• other elements may also be present. All of the percentages mentioned above and below are percentages by weight.
• a phosphorus slag is typically composed of CaO (45-50%), Si0 2 (40-45%), A1 2 0 3 (1- 3%), MgO (1-2%), P 2 0 5 (0-3%) and a small amount of Na 2 0 ( ⁇ 1%).
• other elements may also be present.
• the steel slag in particular contains reactive calcium and magnesium compounds. Due to the reactivity of these calcium and magnesium compounds, these calcium and magnesium compounds undergo further reactions in the solidified state when exposed to air and/or moisture. Effectively, the calcium and magnesium compounds formed during solidification of the steel slag are metastable.
• steel slags are only used to a very limited degree for high-performance applications. Annually, many hundreds of millions of tonnes of steel slag are being produced worldwide. Most steel slag is either taken to dumping sites or (in the case of a useful application) is used in relatively low-performance infrastructural applications.
• Phosphorus slag is also produced in large quantities. Although phosphorus slag often does not contain any reactive components, it too is only used for low-performance applications (if it is used at all).
• blast furnace slags are also already being used in high-performance applications in the cement industry.
• the molten slag contains a supersaturation of gases which do not escape from the molten slag or only to an insufficient degree during cooling down, remain in the solidified slag and can cause (local) weakening of the product due to, for example, the formation of coarse enclosures.
• the molten slag is removed from the production process as quickly as possible without considering the processing thereof. In this case, the molten slag is often cooled down as quickly as possible until it solidifies. This generally results in a molten slag which is made up of relatively weak material which may contain many (cooling) cracks.
• the smelt still contains reactive metastable constituents which only after cooling down and often in the long term lead to afterreactions in the solidified phase. Depending on the specific reactant, this afterreaction can result in an increase in volume. This may cause the formation of cracks in the product or other (visual) damage, such as for example by efflorescence. 4.
• the molten slag to form stone-like products having a great wall thickness (such as blocks) relatively large temperature differences often occur during solidification.
• the slag is mixed (intimately) with a gas which is supplied from the outside in an installation (part) which is specifically suited for this purpose, e.g. a gas (for example C0 2 or Ar) is allowed to flow through the slag in order to cause the melt to move vigorously, resulting in the dissolving power for the gases decreasing and a significant part of the dissolved gases being released.
• a gas for example C0 2 or Ar
• This also usually takes place in a separate (reaction) vessel which is provided with the necessary inlet and outlet for the gases.
• CA 2 278 099 describes a process by means of which high-performance building products are obtained, starting from a mineral melt.
• the essence of this invention is that minerals are added in relatively large amounts (5 to 35%) in order to affect the composition and furthermore that the melt is pretreated in a vessel in which various kinds of deaeration are carried out and then, after casting, the moulds are placed in a furnace system in which the desired properties for the end product are achieved by reheating and cooling down the melt several times.
• Japanese patent JP2009270132 mentions converting the reactive components in the molten slag into stable compounds.
• an additive which is not described in any more detail is mixed in with the molten mass, following which the hot mixture is heated further to temperatures in excess of 1600 °C in order to cause the desired reactions to take place.
• Japanese patent JP6329450 mentions mixing mineral (semi)liquid molten slag with quartz or quartz-containing by-products using a modified bulldozer in order to produce stabilized granules.
• British patent GB 2 437 796 A mentions that a (glass) ceramic product based on blast furnace slag is produced by adding relatively large amounts of magnesium compounds. Subsequently, the other (process) properties of the blast furnace slag are improved by the addition of borax and rutile in order to produce a ceramic product (for example tiles).
• the invention relates to the abovementioned method
• the method furthermore comprises:
• a first additive which comprises at least one substance containing an alkali element to the separated liquid molten slag in order to form a liquid slag alloy for reducing a solidification point of the liquid slag alloy with respect to a solidification point of the molten slag
• the liquid slag alloy contains between approximately 1 and approximately 6% of alkali element oxide component, and the alkali element is selected from a group including at least one of sodium and potassium.
• the invention provides that by changing the composition of the molten slag, the solidification point (or the temperature of the solidification range) of the molten slag is reduced. Without wishing to limit oneself to one specific theoretical explanation, it is assumed that the change in the composition of the molten slag results in a composition which has a lower melting point in the phase diagram and has, for example, a more pronounced eutectic character of the liquid phase.
• the method has the advantage that the viscosity of the liquid molten slag reduces.
• the addition of the alkali element-containing substance reduces the viscosity of the molten slag, due to the alkali atoms preventing or suppressing a polymerisation of the silicate constituents of the molten slag. Due to the alkali elements being monovalent, the prevention/suppression is stronger than that of elements having a higher valency.
• the lower viscosity makes it easier for the dissolved gases to escape from the liquid.
• an improved supply to the casting die volume from the liquid phase can be achieved during the solidification process, so that a relatively thinner wall thickness of the moulded product can be achieved.
• the lowering of the solidification point increases the temperature difference between the actual process temperature of the molten slag and the solidification point, the lowering of the solidification point can also be used for significant energy recovery from the liquid slag.
• the invention makes it possible to form products by means of a continuous process, comparable to the possibilities in the steel industry.
• the invention provides a method as described above, in which the alkali element is selected from potassium and sodium. These elements have the desired effect and do not adversely affect the metastable Ca and Mg components in the molten slag.
• the invention provides a method as described above, wherein the calcium silicate-containing molten slag is a steel slag or a thermal phosphorus slag containing less than 1% Na 2 0.
• the invention provides a method as described above, wherein the liquid slag alloy contains between 1% and 5% alkali element oxide component, wherein the alkali element is selected from a group of at least one of sodium and potassium. Addition of such amounts to this composition results in a lowering of the solidification point in the order of magnitude of 200 to 300° (Celsius).
• the invention provides a method as described above, wherein the alkali element-containing substance is selected from a carbonate or a halogenide compound.
• Alkali carbonates decompose, during which process C0 2 is released which is finely distributed in the slag and can thus serve as a trigger for forming gas bubbles for gases dissolved in the slag, thereby assisting degassing.
• the use of alkali halogenide has the advantage that the halogenide can react with the metastable Ca and/or Mg components, in which case more stable Ca and/or Mg components are formed.
• the invention provides a method as described above, comprising the addition of a second additive comprising silicate compounds, wherein an amount of the second additive to be added depends on an amount of unstable reactive calcium and/or magnesium oxides, and wherein an active component of the silicate compounds to be added is not calcium or magnesium silicate and, in addition, fine-grained (preferably ⁇ 100 micrometres).
• This second additive serves to further stabilize the metastable Ca and Mg components in the slag in the form of a respective silicate compound.
• the invention provides a method as described above, wherein the second additive is an amorphous substance.
• This type of substance needs less energy in order to pass to the liquid phase, unlike crystalline substances which require additional energy in order to break the crystal lattice.
• the amorphous substance can become liquid more quickly and react with the metastable Ca and Mg components in the molten slag.
• the invention provides a method as described above, wherein the amorphous substance is fly ash, in particular carbon-containing fly ash. It has been found that fly ash from coal-fired power stations is highly suitable for this application. Moreover, the carbon in the fly ash amplifies the degassing by the formation of carbon dioxide in the liquid slag alloy.
• the invention provides a method as described above, wherein the silicate compounds of the second additive do not comprise quartz. In this manner, the quartz content of the slag alloy is prevented from rising, and an increase of the thermal stress in the moulded product as a result of the 'quartz transition' at approximately 573 °C is prevented.
• the invention provides a method as described above, comprising withdrawing heat from the liquid slag alloy after the addition of at least the first additive and before casting.
• the invention provides a method as described above, comprising lowering the temperature of the liquid slag alloy to a temperature which is
• the invention provides a method as described above, comprising actively mixing the liquid molten slag and the at least first additive during the addition of at least the first additive.
• the invention provides a method as described above, comprising the addition of vibration energy to the liquid slag alloy and/or the liquid molten slag before casting it into the casting die.
• vibrations improves the degassing of the liquid slag.
• the reduction of the viscosity by the addition of the first additive facilitates the result obtained by the vibrations.
• the invention provides a method as described above, wherein the liquid slag alloy is divided into several casting streams before casting.
• the invention provides a method as described above, wherein, after casting into the casting die, the cooling rate in a range around 573 °C is adjusted to the amount of quartz present in the slag alloy.
• the invention comprises a method as described above, comprising granulating the slag alloy during casting.
• the invention also relates to the above-described device, comprising an inlet for a liquid molten slag which originates from a production process of a molten material from ore in a furnace, wherein the inlet is connected to the furnace for receiving the liquid molten slag; an outlet for casting the received liquid molten slag into a casting die; a conveyor runner which extends from the inlet to the outlet for enabling the liquid molten slag to flow from the inlet to the outlet, wherein the device furthermore comprises an inlet for adding at least one additive to the received liquid molten slag in order to form a liquid slag alloy, wherein the conveyor runner is provided with one or more blades or guides for mixing the at least first additive and the flowing liquid slag alloy during use.
• Fig. 1 shows a process diagram of a method according to an embodiment of the invention
• Figs. 2a, 2b diagrammatically show a device according to an embodiment of the invention.
• Fig. 1 shows a process diagram of a method of treating a molten slag which can be used in connection with a metallurgical process.
• a liquid base material often a liquid metal
• the ore(s) is (are) the raw material which contains the base material to be recovered, such as iron ore, or a phosphorus-containing ore, a non-ferrous ore and additional components, such as for example limestone.
• additive(s) are added to release or stabilize the base material from the ore.
• these processes produce a by-product in the form of a molten slag which is formed from a reaction product of the secondary components of the ore and/or components of the additive(s).
• Fig. 1 shows a flow diagram of a process 100 for treating and processing the molten slag.
• molten slag is separated from the liquid base material.
• the liquid base material together with the molten slag is situated in a furnace or reactor, where a process temperature prevails which is determined by the (metallurgical) process in order to release the base material.
• the process temperature is approximately between 1500 and 1700 °C.
• the molten slag therefore has a temperature which substantially corresponds to the process temperature in the thermal processing of ore.
• at least a first additive is added to the molten slag.
• An additive contains one or more alkali-containing components (elements or compounds) which have the property that they form an alloy using the separated liquid molten slag or that they react with the separated liquid slag, wherein the composition of the liquid slag alloy changes in such a manner that the solidification point or the solidification range temperature is lowered.
• a eutectic or peritectic composition is obtained or at least a composition which has a lower melting point and, according to the phase theory, comes closer to a eutectic or peritectic composition than the composition of the separated molten slag.
• the molten slag is a calcium silicate-containing residual product which is characterized by a high content of mineral components (mostly silicon and aluminium compounds).
• the steel slag may also contain reactive metastable calcium and magnesium compounds.
• the first additive comprises an alkali element-containing substance, such as sodium, and/or potassium compounds.
• This element ensures that the composition of the molten slag "moves" in the direction of a eutectic or peritectic point (range) which is known from phase diagrams and/or phase information for molten slag material.
• the liquid slag alloy contains between 1% and 5% of sodium and/or potassium oxide compound (in % by weight) or has a composition range between approximately 1% and approximately 6% of sodium or potassium oxide, or between approximately 2% and approximately 4% of sodium or potassium oxide.
• a second additive is optionally added for stabilizing the reactive calcium and/or magnesium compounds in the molten slag.
• This second additive contains silicate-containing substances which bond with the reactive calcium and magnesium compounds to form a stable calcium silicate and magnesium silicate, respectively. It will be clear that the composition of the separated liquid molten slag is determined before this alloying or reaction step. On the basis thereof, it can then be determined which amount of first additive and, if required, which amount of second additive is to be added.
• step 103 the additive(s) added in step 102 is (are) actively mixed with the molten slag in order to assist the alloying/reaction process. Mixing creates a liquid slag alloy from the molten slag.
• the solidification point (or melting point) thereof will be changed (i.e. lowered).
• the melting point is lowered in the direction of the minimum liquidus temperature which occurs at the eutecticum by "moving" to the eutectic point in the phase diagram.
• the slag thus remains liquid down to relatively low temperatures than without alloying or reaction step 102. For a steel slag, this results in a lowering of the temperature from approx. 1500 to approx. 1200 °C.
• the alloying of the slag as described above has the result that the solidification range is reduced in relative terms (with a modified, but non-eutectic composition) and the solidification range only takes place at the relatively lower temperature than with the separated liquid slag.
• the 'two-phase' range in which the slag consists of a solid and a liquid component is reduced by the alloying step moves to a lower temperature, which increases the castability of the slag alloy.
• phase systems may be binary, ternary, quaternary or of an even higher order.
• the second additive in an embodiment is an amorphous substance: compared to crystalline substances, a substance having an amorphous structure has the advantage that no transformation of the crystal structure to the liquid phase has to take place. As a result thereof, mixing or dissolution of the additive(s) is facilitated and accelerated in relative terms.
• the method comprises that the slag alloy is subjected to a degassing treatment.
• Degassing may take place by shaking the slag alloy, in which case gas bubbles can escape from the slag alloy. With this form of degassing, the amount of residual gas in the slag alloy decreases, so that an improved solidification structure of the slag is achieved. This step is also advantageous in order to reduce the build-up of internal stress in the solidified slag by any gas which may be present.
• the degassing is also improved by the added additive(s) which, inter alia, result in a lower viscosity.
• a step 104 heat is actively withdrawn from the slag alloy, for example by means of a heat-exchanging element.
• a heat-exchanging element As has already been explained above, the formation of the slag alloy lowers the melting/solidification point (or the
• the energy recovery 104 can also take place (at least partly) simultaneously with the addition phase 102 and/or the mixing phase 103, depending on the actual temperature of the molten slag.
• the temperature of the slag alloy can be lowered to about 50° (degrees Celsius) above the melting/solidification point (or the temperature of the start of solidification). Due to the reduced viscosity of the slag alloy, the liquidity is sufficient at this point in time for carrying out a casting process.
• the process diagram comprises two alternatives 105 - 107; 108 - 1 10 for the further treatment of the cooled-down liquid slag alloy.
• the liquid slag alloy is cast into a casting die in step 105.
• this step comprises dividing the slag alloy into a number (more than one) casting streams. This has the advantage that the exchange of gases from the slag alloy to the atmosphere is improved.
• the slag alloy in the casting die solidifies and cools down. Due to the lowered viscosity, a thinner wall thickness and higher form definition of the moulded product is possible than with a steel slag from the prior art.
• molten slag which has already solidified in the casting die in the form of a stack of pieces or granules between which there are spaces.
• the liquid molten slag is cast thereon and, due to its low viscosity, fills the spaces between the pieces or granules. In addition, this reduces the wall thickness of the melt in the mould, so that in addition fewer thermal stresses will occur.
• the pieces should preferably have the same composition as the melt in order to obtain an end product which is as homogenous as possible. Due to the fact that a part of the mass in the casting die has already solidified, the total shrinkage in the casting die volume resulting from the solidification of the liquid material which is added will be relatively low. In this way, it is possible to produce a product with a reduced degree of thermal stress.
• the cooling down is controlled in such a manner that the region of the so-called quartz transition (that is to say the phase transformation of quartz at approx. 573 °C) is passed through at a low cooling rate.
• This phase transformation is accompanied by a change in volume which may generate a mechanical stress in the cast material.
• a second alternative 108 - 1 10 for the further treatment of the liquid slag alloy follows after the step 104 of cooling down to close to the eutectic point.
• the liquid slag alloy is cast and granulated in step 108, that is to say the solidified slag alloy material consists of granular material, granules.
• the granules are collected and held in a storage volume.
• a subsequent step 109 which may, at least in time, partly coincide with the granulating process 108, the granules are cooled down.
• step 109 is used to withdraw heat (forced cooling) from the granules for the purpose of, for example, energy recovery.
• This forced cooling is advantageously possible because, although any increased thermal and/or internal stress resulting from the forced cooling may lead to the formation of cracks and breakage of the solidified slag material, in granules cracks in and/or crumbling of the material is permissible.
• step 110 the cooled down granules are collected as an end product.
• step 110 the process diagram ends with step 112 in this second variant.
• Figs. 2a, 2b diagrammatically show a device according to an embodiment of the invention.
• the device 200 is configured for use in carrying out the method 100 according to the invention.
• the device 200 comprises a tubular body 201.
• the tubular body 201 is provided with an inlet 202.
• the inlet 202 is configured to receive the liquid molten slag from the furnace.
• the inlet may be coupled to an outlet of the furnace or may be provided with, for example, an opening where a casting stream 300 from the furnace can be introduced into the tubular body.
• the tubular body is provided with an outlet 203.
• the tubular body is provided with an insulating cladding, for example in the form of a refractory layer.
• the tubular body is arranged at an angle in such a way that, compared to ground level, the inlet is situated above the outlet. Furthermore, the inlet 202 is configured to receive an additive stream 301 to form the slag alloy with the molten slag material.
• the tubular body 201 On an internal wall 201a of the tubular body 201, a number of mixing blades or ridges 205 are arranged which are configured, in use, to disturb a flow of the combination of molten slag 300 and additives 301 flowing past, resulting in an improvement in the mixing of the slag alloy and the additives and in an improvement in the degassing.
• the tubular body 201 has a length which is such that, during the passage time of the combination of flowing molten slag 300 and additives 301 , the formation of the slag alloy (that is to say the formation of the mainly eutectic or peritectic composition) is achieved/completed.
• the length may also depend on a distance to be bridged between the inlet location from the furnace and a processing location of the slag alloy.
• the tubular body has a diameter between approximately 20 and approximately 40 cm.
• the device 200 is also provided with a vibrating or shaking installation 206, 207 which is configured to supply vibration energy to the tubular body 201.
• a vibrating or shaking installation 206, 207 which is configured to supply vibration energy to the tubular body 201.
• the supply of vibrations makes it easier for the gas bubbles present in the slag alloy to escape, as a result of which the structure of the solidified slag alloy has fewer large inclusions and the porosity can be controlled or reduced.
• pores of a similar size such as are found in, for example, sand lime and (foamed) concrete are usually acceptable in the moulded slag product.
• the outlet 203 for the discharge of the slag alloy is situated at the end of the tubular body 201.
• a heat-exchanging element 208 is connected to the outlet 203 and is configured to collect the liquid slag alloy after it has passed through the tubular body 201 and to withdraw heat from the slag alloy which is in contact with the heat- exchanging element.
• the heat-exchanging element comprises a heat-conducting plate 208 which is provided with ducts 209 on the inside.
• a liquid medium can be passed through the ducts 209 in order to withdraw heat from the heat-conducting plate 208.
• the heat-exchanging element is controlled in such a manner that the liquid slag alloy is cooled to approximately 50° (Celsius) above the melting point of the slag alloy.
• the heat which has been withdrawn can be used as a source of heat in other locations, for example within the installation(s) where this process is being carried out, and it is also possible to apply energy-recovery techniques to the heat (stream) which has been withdrawn.
• Fig. 2b shows a cross section of the tubular body at the location of the line Ilb-IIb in Fig. 2a.
• the tubular body 201 comprises an insulating cladding which is situated on the inner wall of the tubular body or at least on the part of the inner wall with which the liquid slag could come into contact.
• one of the mixing blades 205 is visible in the bottom section (which is situated at a lower level) of the tubular body .
• the mixing blade 205 is configured as a body which tapers from the wall, possibly as a plate-shaped or fin-shaped body.
• the device according to the invention can also be used in a method in which a silicate- containing additive is added to the molten slag.
• the aim of this method is to transform the metastable or reactive calcium and/or magnesium compounds into stable components in the molten slag.
• the method relates to a treatment of a calcium silicate-containing molten slag in a metallurgical process, comprising:
• the method furthermore comprises:
• adding at least an additive which comprises silicate compounds wherein an amount of this additive to be added is dependent on an amount of unstable reactive calcium and/or magnesium oxides in the molten slag, and wherein an active component of the silicate compounds to be added is not calcium or magnesium silicate.

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Citations (15)

• 2011
  • 2011-07-28 NL NL2007190A patent/NL2007190C2/nl not_active IP Right Cessation
• 2012
  • 2012-07-26 WO PCT/NL2012/050536 patent/WO2013015690A1/en active Application Filing
  • 2012-07-26 EP EP12750856.2A patent/EP2737091A1/en not_active Withdrawn

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