KR20080056254A - Coated slag - Google Patents

Abstract

The invention relates to a coated slag, characterized in that it is coated with a layer of a hydrophobic polyurethane.

Description

Coated Slag {COATED SLAG}

The present invention relates to slag coated with hydrophobic polyurethane.

Slag is obtained in many processes, especially metallurgy. Depending on the production process, slag is divided into furnace, smelting and steelmaking slag. Depending on the process, they are produced from metal ore, coke, limestone and dolomite as by-products of the actual production process. Furnace slag is commonly used as a raw material for cement, in road construction, and in limited cases also as a fertilizer. Steel mill slag, which is obtained in somewhat lower amounts, is mainly used in the field of building materials and less often as a fertilizer. A small fraction, typically about 10%, is disposed of in landfills.

Some of the steel slag is also used in hydraulic engineering in addition to road construction. Practical requirements relating to engineering rocks are specified in the 'Technische Lieferbedingungem fuer Wasserbausteine', which includes requirements relating to rock density, size and weight classification, rock morphology, compressor strength, scratch resistance and volume invariance. do. Slags used in hydraulic engineering now frequently replace structures previously created from lattice pores. In general, slag rocks are no longer set in a complex way, but are disposed of randomly.

The disadvantage of using slag is first that the mechanical stability is insufficient. Thus, for example, it has been found that 10-20% of the slag disintegrates to very fine particle sizes when used in hydraulic engineering. The milling process leads to a cementing time course that is substantially impermeable to water over time to constitute a latent crack point of the top layer.

It is also necessary to prevent the release of toxic substances from the slag to the surroundings, or in the case of water engineering, into water. Consequences of adverse effects on the biocommunity, and at the same time on the self-cleaning of the body of water, are of concern.

The prior art discloses the use of slag in combination with plastics in civil and hydraulic engineering.

Thus, DE 1 946 469 describes a sealing layer for inclined surfaces, consisting of rocks, slags and binders, in particular in engineering. The binders used are especially asphalt and thermoplastics. Adding the plastic to the binder prevents the sealing layer from flowing out and disappearing.

U.S. patent application-numbering application-and KR 2002008805 describe the use of slag and polymer resins as materials in road construction. The document mentions enhancing the strength of the material.

JP 2001163649 describes industrial wastes coated with mixtures comprising inorganic materials, for example sulfur containing melts. The document provides <44 mm of building material which can be used in road construction as well as in coastal areas. Elution of toxic substances is prevented by coating so that the mixture can also be used as building material.

JP 53137222 describes providing a porous material, for example slag, with a photocurable coating. As a result, the hardness, heat resistance and chemical stability of the material are improved.

KR 2002001916 describes hydraulic coatings surrounding silica, glass or slag. The coating consists of sodium-polyacrylate. The composite has good resistance to seawater.

JP 2004236546 describes the coating of slag with calcium carbonate. The slag provided by the coating is applied to the beach or the bottom of the water, and it is mentioned to control the pH of the sea water and reduce the construction cost.

JP 7048187 describes recycling of waste slag in the construction field by coating with liquid resins, in particular epoxy resins or fiber reinforced resins.

Disadvantages of these liquids are in particular that they generally have insufficient resistance to environmental influences. This may cause the coating to break and its benefits no longer valid.

The goal was to treat slag rock for high mechanical stability and environmental friendliness. The treatment of slag rock should be simple and reliable.

This object could surprisingly be achieved by coating the slag with a hydrophobic polyurethane layer.

Accordingly, the present invention relates to slag coated with a hydrophobic polyurethane layer.

The invention also relates to a process for producing coated slag, wherein the slag is coated with a liquid starting component of hydrophobic polyurethane that cures on this surface.

The slag used can be any type known in the industry. In particular, it may be a furnace, smelting and steelmaking slag. The slag is generally present in the form of a piece having a diameter in the range of 0.5 to 50 cm, preferably 0.5 to 20 cm, particularly preferably 2 to 15 cm and especially 2.5 to 6.5 cm. Small amounts of pieces smaller than fine dust can be tolerated because they can be introduced into the coating. However, the amount of dust should not exceed 10% by weight, based on slag, since otherwise interference may occur in the polyurethane.

The polyurethane layer on the rock is generally only several mm thick, preferably no more than 5 mm, in particular 0.1-5 mm. The slag is coated substantially completely.

As mentioned above, the coating of slag is effected by applying the liquid starting component of the polyurethane to the slag which this component cures. Slag rock can be disposed and wetted by the liquid starting component of the polyurethane. The wetting can be effected, for example, by injection or spraying, as well as by simple mechanical mixing, but spraying is preferred.

The process can be designed so that the coating slag is in the form of individual pieces.

The coating slag is present in the form of a composite, ie the individual pieces are preferably joined to each other by polyurethane. The individual pieces of slag are firmly bonded with polyurethane, and the bonding occurs only at the point of contact. As a result, voids are formed inside the molding.

The composite can be prepared by introducing slag into a mold, to which the liquid starting component of the polyurethane is added, preferably by the aforementioned injection or spraying. The size of the mold is not critical, but should be large so that the liquid starting component of the polyurethane can wet the entire slag before curing. The size of the molding is preferably 100 + 50 x 100 + 50 x 15 + 10 cm.

In a further embodiment of the process according to the invention, the slag is applied where it is used, for example embankments, dams, weirs or traffic routes, where it is wetted by the liquid starting component of the polyurethane where it is cured.

In a further aspect of the invention, the slag is mixed with the liquid starting component of the polyurethane in a mixer. The mixture is then discharged from the mixer and the polyurethane cures.

The mixer used to mix the slag with the starting component of the plastic may be any type of mixer capable of substantially complete wetting of the slag with the starting component of the plastic. It has been found to be particularly suitable for an open container, preferably a mixer consisting of drums, to be equipped with internals. For mixing, the drum can be rotated or the interior can be moved.

Such mixers are known and are used, for example, in the building industry for the production of concrete mixtures.

If the mixture is applied directly to the surface to be solidified, it may be advantageous to mount the mixer on a conveyer, for example a tractor, a front loader or a truck. In this embodiment of the process according to the invention, the mixture can in each case be transferred to the point to be applied. After the mixer is empty, the mixture can be dispensed manually, for example by raking.

In an embodiment of the process according to the invention, the mixing of the liquid starting component of the polyurethane with the slag takes place continuously. For this purpose, the liquid starting components of the slag and polyurethane are continuously introduced into the mixer and the wetted rock is continuously discharged. In this procedure, the starting material should be ensured to remain in the mixer until the slag can be wetted exorbitantly. The mixing device is suitably able to move along the site to be solidified at a rate such that the slag moistened with the liquid starting component of the plastic is discharged from the mixer in the amount required for solidification. It is also possible to operate the continuous mixing apparatus in a steady state and to transfer the wetted slag discharged from the mixture to a predetermined position.

In a further embodiment of the continuous design of the process according to the invention, the mixer may be a rotating drum into which slag is continuously fed. The drum is provided with a nozzle for continuously dispensing the starting component of the plastic onto the rock. Here, the rotation of the drum ensures thorough mixing of the plastic and the rock. The plastic / slag composite is then discharged continuously through the opening at the drum end. The rotating drum may be horizontal, but may also be inclined at various angles to facilitate the discharge.

In a further aspect of the continuous process, the slag is continuously transported on a conveyor belt moving through the tunnel. It has an opening through which the starting material of the plastic is continuously discharged onto the slag. At the end of the conveyor belt, the slag then falls into an open mixing drum which discharges the composite at a set conveyor speed.

With regard to the hydrophobic polyurethanes it may be mentioned as follows.

In the context of the present invention, components of polyurethane are very generally understood to mean compounds having free isocyanate groups and compounds having groups reactive with isocyanate groups. The group reactive with the isocyanate group is generally a hydroxyl group or an amino group. The hydroxyl group is preferred because the amino group is very reactive and therefore the reaction mixture must be processed quickly. Products formed by the reaction of these components are generally mentioned below as polyurethanes.

The polyurethane used may be a common and known compound of this type. Polyurethanes are prepared by reacting a compound having two or more active hydrogen atoms with a polyisocyanate. The polyisocyanates used can be substantially all polyisocyanates, mixtures and prepolymers which are liquid at room temperature and have at least two isocyanate groups.

Preferably aromatic polyisocyanates are used, particularly preferably isomers of toluene diisocyanate (TDI) and isomers of diphenylmethane diisocyanate (MDI), in particular MDI and polyphenylenepolymethylene polyisocyanate (crude MDI) A mixture of uses. The polyisocyanates can also be modified, for example, by the addition of isocyanate groups, in particular the addition of urethane groups. The last mentioned compounds are prepared by reacting polyisocyanates with lower stoichiometric amounts of compounds having at least two active hydrogen atoms, which are generally referred to as NCO prepolymers. Its NCO content is generally in the range from 2 to 29% by weight.

In general, polyfunctional alcohols, so-called polyols, or less preferably polyfunctional amines, are generally used as compounds having at least two hydrogen atoms reactive with isocyanate groups.

In a preferred embodiment of the process according to the invention, the compressed polyurethane used is hydrophobic. The hydrophobicity can be produced, in particular, by adding a hydroxyl functional component known in local chemistry to at least one of the starting components of the polyurethane system, preferably the polyol component.

Numerous hydroxyl-functional ingredients are known in fatty chemistry and can be used. Examples thereof include castor oil, oils modified by hydroxyl groups such as grape seed oil, black cumin oil, pumpkin seed oil, borage seed oil, soybean oil, malt oil, rapeseed oil, sunflower oil, peanut oil, apricot seed oil, Pistachio seed oil, almond oil, olive oil, macadamia nut oil, avocado oil, seed buckthorn oil, sesame oil, hazelnut oil, evening primrose oil, wild rose oil, hemp oil, safflower oil, walnut oil, hydroxyl group and modified in advance It is composed mainly of stoleic acid, palmitoleic acid, oleic acid, basenic acid, petroleum acid, gadoleic acid, erucic acid, nerbonic acid, linoleic acid, linolenic acid, stearic acid, arachidonic acid, timnodonic acid, gluphananoic acid and serbonic acid. Fatty acid esters. Preference is given in the present invention to the use of castor oils and their reaction products with alkylene oxides or ketone-formaldehyde resins. The last mentioned compound is sold by Bayer AG, for example under the trade name Desmophen® 1150.

Groups more preferably used in the known polyols in the local chemistry can be obtained by simultaneous reaction with alcohols and, if necessary, by ring opening of the epoxidized fatty acid esters by further transesterification reactions. The introduction of hydroxyl groups into oils and fats is mainly carried out by epoxidation of the olefinic double bonds present in the product, followed by reaction of the formed epoxide groups with monohydric or polyhydric alcohols. In the case of hydroxyl groups or polyfunctional alcohols, structures having a greater number of OH groups are obtained from the epoxide ring. Since oils and fats are generally glyceryl esters, an equilibrium transesterification reaction also occurs for this reaction. The compound thus obtained preferably has a molecular weight in the range of 500 to 1500 g / mol. Such products are available, for example, from Henkel.

In a particularly preferred embodiment of the process according to the invention, the compressed polyurethane used is a compound having at least two reactive hydrogen atoms, which can be prepared by the reaction of a polyisocyanate with a compound having at least two hydrogen atoms reactive with isocyanate groups. Is one or more polyols known in local chemistry and one or more phenol modified aromatic hydrocarbon resins, in particular indene / coumarone resins. The polyurethanes and their components have high hydrophobicity so that they can cure substantially even in water.

Preferably used phenol-modified aromatic hydrocarbon resins having terminal phenol groups include industrial compounds of phenol-modified indene / coumarone resins, particularly preferably aromatic hydrocarbon resins, in particular as compounds of the formula (I) have:

In said formula, n is 2-28. Such products are commercially available and are provided, for example, by Ruetgers VTF AG under the trade name NOVARES®.

Phenol-modified aromatic hydrocarbon resins, in particular phenol-modified indene / coumarone resins, generally have an OH content of 0.5 to 5.0% by weight.

Polyols and phenol modified aromatic hydrocarbon resins, in particular indene / coumarone resins, known in local chemistry, are preferably used in a weight ratio of 100: 1 to 100: 50.

Further compounds with two or more active hydrogen atoms can be used with the compounds. Polyether alcohols are preferred because of their high stability to hydrolysis. They are prepared by conventional known processes, generally by the addition reaction of H-functional starting materials with alkylene oxides. Incidentally used polyether alcohols have a functional group of at least 3 and a hydroxyl group of at least 400 mg KOH / g, preferably at least 600 mg KOH / g, especially 400 to 1000 mg KOH / g. They are prepared by conventional methods by reacting alkylene oxides with trifunctional or higher starting materials. Starting materials that can be used are preferably alcohols having three or more hydroxyl groups in the molecule, for example glycerol, trimethylolpropane, pentaerythritol, sorbitol or sucrose. Preferred alkylene oxides are propylene oxides.

Customary further components, such as catalysts and customary auxiliaries and additives, may be added to the reaction mixture. In particular, a desiccant such as zeolite should be added to the reaction mixture to prevent water from accumulating in the components and foaming of the polyurethane. The substance is preferably added to a compound having at least two hydrogen atoms reactive with isocyanate groups. Such mixtures are often referred to in the industry as polyol components. In order to improve the long term stability of the composite, it is more advantageous to add an agent for preventing the attack of microorganisms. Moreover, the addition of UV stabilizers is beneficial to prevent embrittlement of the molding.

The polyurethanes used can be prepared substantially without catalyst. In order to improve curing, catalysts may be used incidentally. Preferably the chosen catalyst should be one which induces the longest possible reaction time. As a result, the reaction mixture may remain liquid for a long time. As described, it may function substantially entirely without catalyst.

Compounds having at least two hydrogen atoms reactive with isocyanate groups and polyisocyanates should be blended in such a proportion that a stoichiometric excess of the isocyanate group, preferably at least 5%, in particular in the range of 5 to 60%.

Hydrophobic polyurethanes which are preferably used are distinguished by particularly good processability. Thus, the polyurethanes exhibit particularly good adhesion with wet substrates such as wet rocks, in particular granite rubble. The polyurethane cures substantially in compressed form despite the presence of water. The compression polyurethanes used indicate that they are fully compression set even in the case of thin layers.

Thus, the polyurethanes which are preferably used are remarkably suitable for the solidification of banks, in particular dams and dams. The bond between rock and polyurethane is very strong. Moreover, by using particularly hydrophobic polyurethanes, there is virtually no hydrolysis of the polyurethanes, thus the durability of the embankments solidified by the process according to the invention is long lasting.

In order to carry out the process according to the invention, the polyisocyanate is preferably mixed with a compound having at least two active hydrogen atoms, the mixture being mixed with rock. Practically, it may also be possible to add both starting components of the polyurethane separately to the rock and mix with them. In this case, however, non-uniform mixing and consequent poor mechanical properties of the polyurethane may occur.

The starting components of the polyurethanes can be mixed by known methods. In the simplest case, the ingredients are introduced in a proportion, such as a bucket, into a bucket, mixed by simple stirring, and then mixed with the rock in a mixing device. It is also possible to mix the starting components of the polyurethanes in a mixing element customary in polyurethane chemistry, such as a mixing head, and to bring this mixture into contact with the rock.

By hydrophobic treatment of the polyurethane, its hydrolysis can be suppressed. Thus, the coating has a substantially infinite lifetime.

As a result of the coating with the hydrophobic polyurethane, no soluble metal compound is released from the slag. Thus, coated slag can be used in all applications, in particular in hydraulic engineering.

The coated slag according to the invention is high in strength and can be widely used. It can be used both in the form of individual rocks and in the form of complexes.

The advantage of composites in hydraulic engineering is their high strength, in particular. Moreover, due to the voids therein and the resulting water impermeability, they can absorb the wavelength energy and effectively protect the weirs.

Claims (11)

Coated slag coated with a hydrophobic polyurethane layer. The coated slag of claim 1, wherein the polyurethane layer has a thickness of 5 mm or less. The coated slag of claim 1, wherein the polyurethane layer has a thickness of 0.1 to 5 mm. The coated slag of claim 1, wherein the particles of slag are joined by polyurethane to provide molding. The coating slag of claim 1, wherein the polyurethane is prepared by reacting a polyisocyanate with a compound having at least two active hydrogen atoms. The coating slag of claim 5, wherein the compound having at least two active hydrogen atoms comprises at least one hydroxy functional component known in local chemistry. 6. The coating slag of claim 5, wherein the compound having at least two active hydrogen atoms comprises at least one phenol modified indene / coumarone resin. A method of making a coated slag, wherein the slag is wetted with a liquid starting component of hydrophobic polyurethane that cures on its surface. The method of claim 8, wherein the wetting of the slag with the liquid starting component of the hydrophobic polyurethane is effected by spraying. The method of claim 8, wherein the wetting of the slag with the liquid starting component of the hydrophobic polyurethane is effected by injection.  The method of claim 8, wherein the wetting of the slag with the liquid starting component of the hydrophobic polyurethane is carried out in a mixer.