EP2222614A1 - Mold comprising metal residue and carbon carriers - Google Patents

Abstract

The invention relates to a solid mold comprising metal-containing residues from metal processing or metal production, and a solid carbon carrier bonded in a solid matrix, wherein the solid matrix is produced by reacting a binder comprising an aluminum phosphate and hardener comprising an alkali earth oxide.

Description

 Metal residues and carbon carriers containing molding

The present invention relates to a solid shaped body containing metal-containing residues from metal processing or metal production and a solid carbon support incorporated into a solid matrix.

In metalworking and metal fabrication, but also in other industrial processes, metal-containing residues accumulate as dusts, powders, granules, shavings or as sludges. In the iron and steel industry, these residues often have very high levels of iron and / or iron compounds. Not least due to rising raw material prices due to decreasing resources, increasingly difficult accessibility of resources and increasing demand, there is great interest in returning metal-containing residues from metal processing or metal production into the manufacturing or melting process and recovering reworkable metal from them.

The use of solid moldings for recycling metal-containing residues in the smelting or melting process is known per se. It is also known to agglomerate the metal-containing residues mixed with a solid carbon carrier in a binder, for example in the form of briquettes. The carbon support, such as coke breeze, petroleum coke or anthracite, serves as a reducing agent for a largely direct reduction of metal oxides and other metal compounds.

DE 199 32 334 C1 discloses, for example, agglomerates prepared in the form of paving stones from dust- and sludge-like residues containing iron and / or iron oxide and fine-grained carbon support, as well as additives and binders. Binders are molasses, cement or lime.

Cement has become established as a binder for such agglomerates, especially in high temperature applications. However, the binder content in such cementitious agglomerates is very high. For the slagging of the binder energy is consumed, which is removed from the melting or reduction process. For this reason, the lowest possible binder content is desired. Cement as a binder has the further disadvantage that the setting time is relatively long. Organic binders, such as molasses, bitumen or starch, have low strength and durability without calcination, especially at high temperatures. Premature undesirable decomposition of the agglomerates of organic binders can only be counteracted by energy-intensive sintering, which impairs the profitability of the end product and increases its production costs.

DE 197 12 042 C1 discloses agglomerates for use as blast furnace feedstocks, in which a proportion of more than 90% by weight of a powdery to coarse-grained metal or metal oxide-containing fine material is embedded in a glassy solidified silicate melt. The melting of the silicate matrix requires high temperatures above about 700 ⁰ C and is thus very e- nergieintensiv.

DE 197 08 376 C1 discloses the use of a briquette made of waste materials as aggregate for smelting furnaces of an iron foundry. The binders used are magnesium oxide and / or limestone filter dust.

The known from the prior art and containing metal-containing residues agglomerates or solid shaped body often have only a low durability and strength and often decay too fast. Furthermore, in some known binders for the production of such agglomerates, the cure is extremely slow or very fast, both of which can be associated with disadvantages in the manufacture.

The object of the present invention was therefore to incorporate metal-containing residues from metalworking or metal production together with a solid carbon support in a solid matrix to form a solid shaped body, which has a good durability and strength and overcomes the disadvantages of the prior art in the production.

This object is achieved by a solid molding of the type mentioned, in which the solid matrix is prepared by reacting a binder containing aluminum phosphate and a hardener containing alkaline earth oxide.

In a preferred embodiment of the invention, the aluminum phosphate in the binder is acid monoaluminum phosphate [Al (H ₂ PO ₄ ) _S ] (MALP). In the implementation of the acid monoaluminum phosphate with the generally basic alkaline earth oxide finds an exothermic Acid / base reaction (neutralization) instead. The aluminum phosphate undergoes a condensation reaction with polyphosphate, causing the binder to harden.

In general, "metal-containing residues from metal processing or metal production" for the purposes of this invention not only pure metals as such, but also metal-containing compounds such. As the oxidic compounds of the metals.

In one embodiment of the present invention, the metal-containing residues from metal processing include dusts and powders containing iron, powders, granules, chips or other particles. An advantage of incorporating such metal-containing residues into solid moldings is their compactness. The moldings can be better stored and transported compared to loose bulk material.

It is particularly advantageous if the metal-containing residues and thus the entire solid shaped body is magnetizable, for example, if the residues contain iron. A particular advantage of magnetizable solid moldings is their transportability with a magnetic crane, as it is commonly available in blast furnaces and foundries. The solid moldings can be transported with the magnetic crane directly into the furnace.

In one embodiment of the present invention, the solid carbon support in the molded article is selected from coke breeze, petroleum coke, carbon black, hard coal and / or anthracite. Particularly preferred is the solid carbon carrier coke breeze.

In a further preferred embodiment of the present invention, the binder contains more than 90% by weight of acid monoaluminum phosphate, based on the total weight of the dry matter of the binder. The binder may be provided and used both as a dry substance and in the form of an aqueous solution. Particularly preferred is the provision of the binder in the form of an aqueous solution containing from 25 to 60% by weight of monoaluminum phosphate. Since water is required for processing and reacting the binder with the hardening agent, the provision of the aluminum phosphate in the form of an aqueous solution has the advantage that the aluminum phosphate comes into uniform contact with the remaining constituents and at the same time provides the required water.

In a further embodiment of the invention, the alkaline earth oxide in the hardener comprises magnesium oxide [MgO]. The hardener particularly advantageously contains 15 to 75% by weight of magnesium oxide.

In a further embodiment of the invention, the magnet contained in the hardener comprises - -

Seawater magnesite and / or sintered magnesite, with sintered magnesite being particularly preferred.

It has proved to be very advantageous if the hardener in addition to the alkaline earth oxide, which is advantageous or at least magnesium oxide, further contains at least one clay mineral-containing aluminum silicate. Preferably, this clay mineral-containing aluminosilicate is selected from the groups of two-layer and / or three-layer clay minerals.

The use of the clay minerals in the hardener advantageously increases the strength of the shaped bodies according to the invention. In addition, the clay mineral-containing aluminum silicates in the hardener contribute to the controllability of the curing reaction. As stated above, an acid / base reaction takes place between the acidic aluminum phosphate in the binder and the alkaline earth alkaline earth oxide in the hardener. When magnesium oxide is used in the curing agent, this neutralization reaction is very strongly exothermic. The clay mineral-containing aluminum silicates in the hardener cause that strongly exothermic neutralization reaction does not proceed too vigorously and remains controllable. It is particularly advantageous if the hardener contains a premix of the alkaline earth oxide and the clay mineral. It is believed that in the premix the alkaline earth oxide particles are covered or coated by the clay mineral so that they come into contact with the acidic aluminum phosphate more slowly than in the pure form and the reaction is therefore slower and more controllable. Another of the inventors found and surprising advantage of the use of clay mineral-containing aluminum silicates in the curing agent was that by their use the mass for the production of moldings according to the invention receives a plasticity and tackiness, which supports the Kompaktie- tion of the moldings very beneficial and good adhesion causes the particles together. As a result, the strength of the cured molded body is improved.

In a further embodiment of the invention, the clay mineral-containing aluminum silicate contained in the hardener is selected from the two-layer clay minerals halloysite and kaolinite. Particularly preferred is kaolinite. The use of kaolinite has the advantage that it has a very low, possibly even the lowest, content of impurities among the clay minerals, and therefore a possibly interfering influence of foreign cations is kept very low. Kaolinite is a major constituent of most refractory clays and is commercially available in large quantities and at relatively low cost.

Three-layer minerals give the composition a much higher plasticity for the production of the moldings according to the invention and can therefore give it a too high tackiness and increase the - -

deteriorate compared to more kaolinithaltigen clay minerals. Therefore, preferably, no three-layer minerals are used.

In a further embodiment of the invention, the total content of metal-containing residues from the metal processing or metal production and solid carbon support in the solid molding 65 to 95 wt .-%, preferably 75 to 85 wt .-%, based on the weight of the solid molding. If the total content of metal-containing residues and solid carbon support is too high, the proportion of matrix material in which the residues and the carbon support are incorporated is too low, which has a disadvantageous effect on the strength of the shaped body. A too low total content of metal-containing residues and solid carbon support is uneconomical and would result in too high a proportion of binders and other substances, which are undesirable in the further processing and use of the solid shaped body.

In a further embodiment of the shaped article according to the invention, the total content of metal-containing residues from metal processing or metal production is from 30 to 76% by weight, preferably from 50 to 68% by weight, based on the weight of the solid shaped article. The achievable strength of the agglomerates depends not only on the binder content but also on the amount and physical nature of the metal-containing residues used. Within the aforementioned quantitative ranges very good strength properties were achieved.

In a further embodiment of the solid molding according to the invention the total content of solid carbon support is 13 to 19 wt .-%, preferably 15 to 17 wt .-%, based on the weight of the solid molding.

In a further embodiment of the molding according to the invention, the weight ratio of metal-containing residues from metal processing or metal production to solid carbon support is 1: 1 to 6: 1, preferably 3: 1 to 5: 1, more preferably about 4: 1.

In a further embodiment of the solid molding according to the invention, the total content of aluminum phosphate in the binder is 1.5 to 10.5% by weight, preferably 2.5 to 7.5% by weight, particularly preferably 3.0 to 6.5 Wt .-%, based on the weight of the solid molding. Too high a content of aluminum phosphate causes too high a moisture content in the mass in the production of moldings of the invention and thus a poorer pressability. If the content of aluminum phosphate is too low, the mass becomes too dry. and can not be processed well either. In both cases, the strength of the finished molded body deteriorates.

In a further embodiment of the solid molding according to the invention, the molar ratio of aluminum to phosphorus in the aluminum phosphate contained in the binder is 1: 2.5 to 1: 3.5, preferably 1: 2.9 to 1: 3.1.

In a further embodiment of the solid molded article according to the invention, the total content of alkaline earth oxide and aluminum silicate containing clay minerals in the hardener is 5 to 20% by weight, preferably 8 to 17% by weight, particularly preferably 10 to 14% by weight, based on the weight the solid molding. Too low or too high a total content of alkaline earth oxide and clay-mineral-containing aluminum silicate in the hardener causes the hardening of the mass to be too slow or not at all or too fast for the production of the shaped bodies according to the invention. Thus, a binding of the starting materials is not or only very badly possible.

In a further embodiment of the solid shaped body according to the invention, the weight ratio of alkaline earth oxide to clay mineral-containing aluminum silicate in the hardener is 1: 1 to 4: 1, preferably 2.0: 1 to 2.5: 1. Too low or too high a weight ratio of alkaline earth oxide to clay mineral-containing aluminum silicate in the hardener causes the hardening of the mass for the production of the moldings according to the invention is too slow or not at all or too fast.

The solid shaped articles according to the invention can be produced in any suitable form. Particularly advantageous they are produced in the form of briquettes or bricks. These can be transported very well and stored space-saving.

The present invention also encompasses processes for the preparation of the solid molding according to the invention. In one embodiment of the process according to the invention, the metal-containing residues from metal processing or metal production, the solid carbons and the alkaline earth oxide containing hardener are mixed as driers and then mixed with an aqueous solution of aluminum phosphate-containing binder to a pulp or preferably to a humid mass and formed into shaped bodies and / or pressed. In an alternative embodiment of the process, the metal-containing residues from the metal processing or the metal production, the solid carbon carrier, the alkaline earth oxide-containing hardener and the aluminum phosphate-containing binder are mixed as driers and then added with water or an aqueous solution - -

a pulp or preferably mixed into a moist earth and molded into moldings and / or pressed.

Both of the aforementioned methods are suitable according to the invention, wherein the addition of the aluminum phosphate contained in the binder as an aqueous solution has the advantage that the aluminum phosphate is very uniformly mixed with the other solids and brought into contact with the water required for processing and reaction. In addition, the contacting of the aluminum phosphate with the other solids takes place only when the water comes into contact with these solids. A premature reaction of aluminum phosphate with alkaline earth metal oxide can thus not take place.

Conveniently, the water content of the slurry or the earth-moist mass is 2 to 10 wt .-%, preferably 2.5 to 7 wt .-%, particularly preferably 3 to 5 wt .-%. If the water content is too high, the mass is too moist and the setting time becomes too long.

Further advantages, features and embodiments of the present invention are explained below with reference to non-limiting embodiments.

example 1

Iron oxide granules with a mean grain size of 0.49 mm and coke breeze are premixed dry in a ratio of 4: 1 (w / w). Subsequently, a hardener of 30% by weight of magnesium oxide (sintered magnesite) and 70% by weight of clay mineral-containing aluminum silicate is mixed in. The dry mixture of iron oxide granules, coke breeze and hardener is uniformly mixed with a 50% aqueous solution of acid monoaluminum phosphate (MALP) to a soil wet mass and formed into cylindrical moldings having a height of 50 mm and a diameter of 50 mm. The amounts of binder and hardener used were varied in relation to the mixture of iron oxide granules and coke breeze and are shown in Table 1 below.

Table 1

- -

Results:

Experiment 1: The mass was too moist, even plastic, and therefore not very easy to work.

The curing time was 10 minutes and was thus relatively long.

Experiment 2: Despite the 1/3 lower water content, the mass was still too moist, but no longer plastic. The curing time was also 10 min as in experiment 1.

Experiment 3: The mass was crumbly and well moistened and was very easy to process.

The curing time was only 5 minutes, with the test piece still slightly moist after curing.

Experiment 4: The mass was crumbly and well moistened as in experiment 3 and was very easy to process. The curing time was also only 5 minutes, with the specimen after the

Curing but already dry.

Claims

Patent claims A solid shaped article containing metal-containing residues from metalworking or metal fabrication and a solid carbon support incorporated into a solid matrix, said solid matrix being formed by reacting an aluminum phosphate-containing material Binder and a Erdalkalioxidhaltigen hardener is made. 2. Solid molded article according to claim 1, characterized in that the metal-containing residues from the metal processing iron and / or iron compounds containing dusts, powders, granules, chips or particles. 3. Solid molding according to one of the preceding claims, characterized in that the solid carbon support comprises coke breeze, petroleum coke, carbon black, hard coal and / or anthracite. 4. Solid molded article according to one of the preceding claims, characterized in that the aluminum phosphate in the binder acid monoaluminum phosphate is. 5. Solid molding according to one of the preceding claims, characterized in that the binder more than 90 wt .-% acidic monoaluminum phosphate [Al (H ₂ PO ₄ ) ₃ ] based on the dry substance. 6. Solid molded article according to one of the preceding claims, characterized in that the alkaline earth metal oxide in the hardener comprises magnesium oxide [MgO]. 7. Solid molding according to one of the preceding claims, characterized in that the hardener contains 15 to 75 wt .-% magnesium oxide [MgO]. 8. Solid molding according to one of the preceding claims, characterized in that the magnesium oxide contained in the hardener comprises seawater magnesite and / or sintered magnesite. 9. Solid shaped article according to one of the preceding claims, characterized in that the hardener further contains at least one aluminum silicate containing clay minerals, preferably selected from the groups of two-layer and / or three-layer clay minerals. 10. Solid molded article according to the preceding claim, characterized in that the clay mineral-containing aluminum silicate contained in the hardener is selected from the two-layer clay minerals Halloysite and kaolinite and preferably comprises kaolinite. 1 1. Solid molding according to one of the preceding claims, characterized in that it is made in the form of briquettes. 12. Solid shaped article according to one of the preceding claims, characterized in that the total content of metal-containing residues from the metal processing or metal production and solid carbon support 65 to 95 wt .-%, preferably 75 to 85 wt .-% based on the weight of solid shaped body is. 13. Solid molding according to one of the preceding claims, characterized in that the total content of metal-containing residues from the metal processing or metal production 30 to 76 wt .-%, preferably 50 to 68 wt .-% based on the weight of the solid molding. 14. Solid molded article according to one of the preceding claims, characterized in that the total content of solid carbon support 13 to 19 wt .-%, preferably 15 to 17 wt .-% based on the weight of the solid molding. 15. Solid molding according to one of the preceding claims, characterized in that the weight ratio of metal-containing residues from the metal processing or metal production to solid carbon support 1: 1 to 6: 1, preferably 3: 1 to 5: 1, more preferably about 4: 1 is. 16. Solid molding according to one of the preceding claims, characterized in that the total content of aluminum phosphate in the binder, expressed in wt .-% Al ₂ O ₃ 1, 5 to 10.5 wt .-%, preferably 2.5 to 7 , 5 wt .-%, particularly preferably 3.0 to 6.5 wt .-% based on the weight of the solid molding. 17. Solid molding according to one of the preceding claims, characterized in that the molar ratio of aluminum to phosphorus in the aluminum phosphate contained in the binder 1: 2.5 to 1: 3.5, preferably 1: 2.9 to 1: 3.1 is. 18. Solid molded article according to one of the preceding claims, characterized in that the total content of alkaline earth metal oxide and clay-containing aluminosilicate in the hardener 5 to 20 wt .-%, preferably 8 to 17 wt .-%, particularly preferably 10 to 14 wt .-% based on the weight of the solid molding. 19. Solid molding according to one of the preceding claims, characterized in that the weight ratio of alkaline earth oxide to clay mineral-containing aluminum silicate in the curing agent 1: 1 to 4: 1, preferably 2.0: 1 to 2.5: 1. 20. A process for the preparation of a solid molded article according to any one of the preceding claims, in which one mixes metal-containing residues from metal processing or metal production, solid carbon and alkaline earth oxide containing hardener as driers and these then with an aqueous solution of aluminum phosphate binder containing a slurry or a earth-moist mass mixes and forms into moldings and / or presses. 21. A process for the preparation of a solid molded article according to any one of the preceding claims, comprising mixing metal-containing residues from metal processing or metal production, solid carbon support, alkaline earth oxide-containing hardener and aluminum phosphate-containing binder as driers and then with water or an aqueous solution to a pulp or an earth-moist mass mixes and forms into moldings and / or presses. 22. The method according to any one of claims 20 or 21, characterized in that the water content of the slurry or the earth-moist mass 2 to 10 wt .-%, preferably 2.5 to 7 wt .-%, particularly preferably 3 to 5 wt. % is. 23. Use of an aluminum phosphate, preferably acid monoaluminum phosphate [Al (H ₂ PO ₄ ) ₃ ] containing binder and an alkaline earth, preferably magnesium oxide [MgO] -containing hardener for producing a solid molding according to one of the preceding claims. 4. Use of solid moldings according to one of the preceding claims as feedstocks in the production of molten metals, in particular cast iron, pig iron or steel, in melting units or production plants.