DRY CRUSHING METHOD FOR STEELMAKING SLAG, AND CRUSHED STEELMAKING SLAG

Abstract

The present invention relates to the use of a crushing additive during the dry crushing of steelmaking slag, characterized in that the crushing additive is selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers, or mixtures thereof. The present invention also relates to crushed steelmaking slag comprising said additives and to the use of said crushed steelmaking slag in construction materials.

Description

DRY CRUSHING OF STEELMAKING SLAG, CRUSHED STEELMAKING SLAG AND ITS USE IN MATERIALS CONSTRUCTION Technical field The present invention relates to the dry crushing of steelmaking slag in the presence of crushing additives selected from alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers, or mixtures thereof. The present invention also relates to crushed steelmaking slag comprising such additives and its use in construction materials. Background Cement-based building materials, especially concrete and mortars, rely on cementitious materials as binders. Cementitious binders are typically hydraulic binders, the most abundant of which are cements, particularly ordinary Portland cement. However, the use of cements, and especially ordinary Portland cement, has a significant environmental impact. One of the main reasons is the high CO2 emissions associated with cement manufacturing. Therefore, considerable efforts have been made to replace, at least partially, cements as binders in building materials. One possibility is the use of materials with cementitious properties, pozzolans, and / or latent hydraulic materials as cement substitutes. Slag is a particularly attractive material of this type, as it is available in large quantities as a byproduct of various metallurgical processes, especially steelmaking. A specific type of steelmaking slag is converter slag, also called basic oxygen furnace (BOF) slag. BOF slag is generated during the steelmaking process when pig iron is oxidized in the converter using oxygen to reduce the carbon content of the pig iron. Steelmaking slag is usually found in granular form and, like cement, needs to be crushed in a crusher. 1729449 of 28 compression or in a friction mill to obtain a powder with a fineness suitable for use in construction materials. Possible methods for crushing slag include using a vertical roller mill or a ball mill. In a vertical roller mill, a compressive force is exerted on the slag granules by rotating cylinders, while in a ball mill, the impact of the balls on the granules leads to their disintegration. In either case, a powder with a defined fineness can be obtained. Crushing can be carried out in a dry or wet state, for example, when steelmaking slag is suspended in water. It is also well known in the technique of cement crushing or slag crushing that various crushing aids can be used during crushing to improve the overall efficiency of the crushing process. WO 2017 / 194329 discloses a method for wet crushing of slag where a crushing aid selected from polycarboxylate ether, phosphate polycondensation product, lignosulfonate, melamine-formaldehyde sulfonate, alkanolamine, amino acid, sugar, molasses or calcium silicate hydrate is added. Dry crushing of slag can be more advantageous than wet crushing because the resulting crushed slag does not need to be further dried before being formulated, for example, in dry mortars. Dry grinding of granulated blast furnace slag (GBFS) with the addition of triethanolamine, polyethylene glycol or ethanol has been previously described (Filio et al. in The fine grinding of GBFS quenched by water and its reactivity during grinding Shigen-to-Sozai, 107(11), 1991,795-799). The dry crushing of basic oxygen furnace slag has been described in document EP3315471. Due to its intrinsic nature, steelmaking slag is more difficult to crush than other hydraulic binders, such as Portland cement clinker or granulated blast furnace slag. This is because steelmaking slags typically have higher intrinsic hardness and fracture toughness. Furthermore, due to their phased composition, steelmaking slags have a greater tendency to generate ultrafine particles during crushing. Such ultrafine particles can lead to a softer character, increased adhesiveness, and a greater tendency to agglomerate in the crushing media. 1729449 of 28 (for example, the balls in a ball mill), in the crushing vessel or around the larger slag particles. Such agglomeration often results in lower crushing efficiency and / or more difficult air classification in the case of continuous crushing. There remains a need for improved methods of crushing steelmaking slag, and especially basic oxygen furnace slag. Specifically, improvements are needed in the dry crushing of steelmaking slag, and particularly basic oxygen furnace slag. Summary of the invention The object of the present invention is to provide methods for the dry crushing of steelmaking slag. In particular, the efficiency of dry crushing of steelmaking slag is to be improved. Another object of the present invention is to provide improved crushed steelmaking slag that can be used to manufacture construction materials. Surprisingly, it has been found that the objectives of the present invention can be achieved by means of the object of the independent claims. In particular, the use of selected crushing additives of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers or mixtures thereof, in the dry crushing of steelmaking slag, leads to an improvement in crushing efficiency and to an improved crushed steelmaking slag comprising these additives. The efficiency of dry crushing of steelmaking slag, and especially basic oxygen furnace slag, can be improved by using these additives. Specifically, a larger Blaine surface area is obtained from crushed steelmaking slag when crushing is carried out for the same amount of time with these additives present compared to when they are not. Additionally, the amount of crushed steelmaking slag adhering to the crushing tools (e.g., the balls and bowl of a ball mill) is significantly reduced when the additives of the present invention are used. It has also been found, surprisingly, that the use of a slag of 1729449 of 28 Dry-crushed steelmaking slag in the presence of a crushing additive of the present invention improves the performance of a construction material comprising said slag compared to the same construction material comprising crushed slag without said additives. In particular, the early strength of the construction material is improved when dry-crushed steelmaking slag in the presence of a crushing additive is used. Other aspects of the present invention are the subject of independent claims. Preferred embodiments of the present invention are the subject of dependent claims. Ways to carry out the invention In the present context, the terms crushing and grinding have the same meaning and can be used interchangeably. In a first aspect, the present invention relates to the use of a crushing additive during the dry crushing of a steelmaking slag, characterized in that the crushing additive is selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers or mixtures thereof. Steelmaking slag, in this context, is a byproduct of the steelmaking process. Steelmaking slag is obtained, for example, in the Thomas process, the Linz-Donawitz process, the Siemens-Martin process, or in the electric arc furnace when iron is converted into steel. Steelmaking slag is generated when hot pig iron is treated with oxygen to remove carbon and other elements that have a greater affinity for oxygen than iron. Typically, fluxes and / or fixatives, such as limestone or dolomite, are added during the process. The fluxes and fixatives combine with silicates and oxides to form liquid slag. The liquid slag is then separated from the pig iron and cooled in pits or earthen chambers to form crystalline or partially crystalline steelmaking slag.The cooled slag can then be crushed, ground, and sieved to a desired fineness. Preferably, the steelmaking slag of the present invention is a type of slag that has not been further treated in the hot state or during the cooling process. The particle size of a steelmaking slag can be analyzed 1729449 of 28 by sieve analysis, as described, for example, in ASTM C136 / C136M. The process separates fine particles from coarser particles by passing the material through several sieves of different mesh sizes. The material to be analyzed is vibrated through a series of sequentially decreasing sieves using a single motion or a combination of horizontal, vertical, or rotary motion. As a result, the percentage of particles retained on a sieve of a given size is obtained. Another measure of the fineness of steelmaking slag is its Blaine surface area. The Blaine surface area can be determined according to the NF EN 1966 standard. According to a preferred embodiment, steelmaking slag before crushing has a Blaine surface area of ​​between 1000 and 4000 cm² / g. However, it is also possible to use steelmaking slag with a higher specific surface area. Steelmaking slag can be any slag resulting from steelmaking. Specifically, steelmaking slag includes granulated blast furnace slag (GBFS), basic oxygen furnace (BOF) slag, ladle slag, and electric arc furnace slag. However, it is preferred that steelmaking slag not be granulated blast furnace slag. A highly preferred type of steelmaking slag in this context is basic oxygen furnace (BOF) slag. Another common name for basic oxygen furnace slag is basic oxygen slag (BOS). The chemical composition of BOF slag can be determined by XRF, as described in ASTM D5381-93. Typical BOF slag has a chemical composition of 27–60 wt% CaO, 8–38 wt% iron oxides, 7–25 wt% SiO2, 1–15 wt% MgO, 1–8 wt% Al2O3, 0.5–8 wt% MnO, 0.05–5 wt% P2O5, and some minor components, especially Ti, Na, K, and Cr oxides, in amounts less than 1 wt%. The chemical composition of a BOF slag can vary depending on the steel plant and the operating parameters of the basic oxygen furnace.A particularly preferred BOF slag has a chemical composition with 35-55 wt% CaO, 10-30 wt% iron oxides, 10-20 wt% SiO2, 2-10 wt% MgO, 1-5 wt% AlO3, 0.5-5 wt% MnO, 0.5-3 wt% P2O5 and some minor components, especially oxides of Ti, Na, K and. 1729449 of 28 Cr, with <1% by weight. A preferred steelmaking slag, especially a basic oxygen furnace slag, has an iron oxide content expressed as Fe2O3 of 8-38% by weight, preferably 10-30% by weight, and a sulfur content expressed as SO3 of <1% by weight, preferably <0.5% by weight, especially <0.1% by weight, in each case, with respect to the total dry weight of the steelmaking slag. It is especially preferred that steelmaking slag does not comprise dicalcium silicate (C2S, belite) in an amount exceeding 66% by weight of the total dry weight of the slag. The term "dry crushing" in this context refers to a crushing operation where there is a very low water content or, better, essentially no water present. A very low water content means that the water content during the crushing of steelmaking slag is less than 1% by weight, preferably less than 0.1% by weight, and more preferably equal to or less than 0.06% by weight, in each case, with respect to the total weight of the steelmaking slag. According to the embodiments, the amount of water present during crushing does not exceed 1% by weight, preferably 0.1% by weight, and more preferably 0.06% by weight, with respect to the total dry weight of the slag. The trituration aid is selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers or mixtures thereof. Suitable alkanolamines are preferably selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), isopropanolamine, diisopropanolamine, triisopropanolamine (TIPA), N-methyldiisopropanolamine (MDIPA), N-methyldiethanolamine (MDEA), tetrahydroxyethylethylenediamine (THEED), and tetrahydroxyisopropylethylenediamine (THIPD), as well as mixtures of two or more of these alkanolamines. Triethanolamine should not be used when the steelmaking slag is granulated blast furnace slag. The most preferred alkanolamines are TIPA, MDIPA, MDEA, DEIPA, EDIPA, THEED, and THIPD. The most preferred alkanolamines are TIPA and DEIPA. 1729449 of 28 Several regioisomers of TIPA exist. Throughout the present invention, the preferred regioisomers of TIPA are 1,1',1-nitrilotris(propan-2-ol) and 1,1',Γ'-nitrilotris(propan-1-ol). Preferably, throughout the present invention, TIPA is not 2,2',2''-nitrilotris(propan-1-ol). Examples of suitable glycols include monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, polyethylene glycol (particularly those with 6 or more ethylene units, such as PEG-200), neopentyl glycol, hexylene glycol, propylene glycol, dipropylene glycol, and polypropylene glycol. It is also possible to use mixtures of two or more different glycols, as well as mixtures of at least one glycol and glycerin. In one embodiment, glycerol is called bioglycerin, which can be produced from a renewable raw material. A sugar, in the sense of the present invention, is a carbohydrate having an aldehyde group. In particularly preferred embodiments, the sugar belongs to the group of monosaccharides or disaccharides. Examples of sugars include, but are not limited to, glyceraldehyde, threose, erythrose, xylose, lyxose, ribose, arabinose, allose, altrose, glucose, mannose, gulose, idose, galactose, talose, fructose, sorbose, lactose, maltose, sucrose, lactulose, trehalose, cellobiose, chitobiose, isomaltose, palatinose, manobiose, raffinose, and xylobiose. Sugars in the form of, for example, vinasse or molasses, may also be used. A sugar acid, in the context of the present invention, is a monosaccharide having a carboxyl group. This may belong to any of the classes of aldonic acids, ursonic acids, uronic acids, or aldaric acids. Preferably, it is an aldonic acid. Examples of sugar acids useful in connection with the present invention include, but are not limited to, glyceric acid, xylonic acid, gluconic acid, ascorbic acid, neuraminic acid, glucuronic acid, galacturonic acid, iduronic acid, tartaric acid, mucilic acid, and saccharic acid. The sugar acid may be in the form of the free acid or as a salt. Depending on the embodiment, the salts of sugar acids may be salts with metals from groups Ia, IIa, Ib, IIb, IVb, and VIIIb of the periodic table of elements. The preferred salts of sugar acids are salts of alkali metals, alkaline earth metals, iron, cobalt, copper, or zinc.Salts with monovalent metals, such as lithium, sodium, and potassium, are especially preferred. The term carboxylic acid means any organic molecule with a carboxylate group, except for sugar acids. Carboxylic acids especially 1729449 of the 28 preferred carboxylic acids are oxalic acid, malonic acid, adipic acid, lactic acid, citric acid, and tartaric acid. The carboxylic acid may be in the form of the free acid or in the form of a salt. Depending on the embodiment, carboxylic acid salts may be salts with metals from groups Ia, IIa, Ib, IIb, IVb, and VIIIb of the periodic table of elements. Preferred sugar acid salts are salts of alkali metals, alkaline earth metals, iron, cobalt, copper, or zinc. Calcium salts of carboxylic acids are especially preferred. The term superabsorbent polymers refers to polymers that can absorb large quantities of water. When superabsorbent polymers come into contact with water, the water molecules disperse into the cavities of the polymer network and hydrate the polymer chains. In this way, the polymer can swell and form a polymer gel or slowly dissolve. This process is reversible, so superabsorbent polymers can be regenerated in their solid state by removing the water. The water absorption property is indicated by the swelling ratio, that is, the ratio of the weight of a swollen superabsorbent polymer to its weight in the dried state.The swelling ratio is influenced by the degree of branching of the superabsorbent polymer, any crosslinking that may be present, the chemical structure of the monomers that form the superabsorbent polymer network, and external factors such as pH, ion concentration of the solution, and temperature. Due to their ability to interact with water, superabsorbent polymers are also called hydrogels. Examples of superabsorbent polymers useful in the context of the present invention include, but are not limited to, natural polymers such as starch, cellulose such as cellulose ether, chitosan or collagen, alginates, synthetic polymers such as poly(hydroxyethyl methacrylate), poly(ethylene glycol) or poly(ethylene oxide), or synthetic ionic polymers such as polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyacrylamides (PAM), polylactic acid (PLA), polyethyleneimine, polyvinyl alcohol (PVA) or polyvinylpyrrolidone. The superabsorbent polymers that are particularly suitable in the context of the present invention are ionic superabsorbent polymers, in particular those based on acrylic acid-modified polyacrylamide, which can be of linear or cross-linked structure. 1729449 of 28 Superplasticizers useful as trituration aids are especially polycarboxylate ether and / or polycarboxylate ester (PCE). The PCE of the present invention comprise (i) repeating units A of the general structure (I), O^OH (I) and (ii) repeating units B of the general structure (II), (CH2)m(o=c) IP or R1(II) wherein each Ru independently represents hydrogen or a methyl group, each Rv independently represents hydrogen or COOM, wherein M is independently H, an alkali metal or an alkaline earth metal, m = 0, 1, 2 or 3, p = 0 or 1, each R1 is independently -(CH2)z-[YO]n-R4, wherein Y is a C2 to C4 alkylene and R4 is H, C1 to C20 alkyl, -cyclohexyl, -alkylaryl or an -N(-Ri)j-[(CH2)z-PO3M]3-j, z = 0, 1, 2, 3 or 4, n = 2 - 350, j = 0, 1 or 2, Ri represents a hydrogen atom or an alkyl group having 1 - 4 carbon atoms and M represents a hydrogen atom, an alkali metal, an alkaline earth metal or an ion ammonium, and wherein the repeating units A and B in the PCE have a molar ratio of A:B in the range of 10:90 - 90:10. In a preferred embodiment, n = 10 - 250, more preferably 30 9 1729449 of 28 200, particular and preferably 35 - 200, especially 40 - 110. In a further preferred embodiment, z = 0. In a further preferred embodiment, z = 4. In a particularly preferred embodiment, the PCE comprises repeating units A of the general structure (I), as well as repeating units B of the general structure (II), the molar ratios of A to B being in the range of 20:80 - 80:20, more preferably 30:70 - 80:20, in particular, 35:65 75:25. A PCE preferably has an average molar mass Mw in the range of 1,000–1,000,000, more preferably 1,500–500,000, more preferably 2,000–100,000, and in particular, 3,000–75,000 or 3,000–50,000 g / mol. The molar mass Mw is determined in this case by gel permeation chromatography (GPC) with polyethylene glycol (PEG) as a standard. This technique is known per se to the person skilled in the art. The PCEs according to the invention can be random or non-random copolymers. Non-statistical copolymers are, in particular, alternative copolymers or block or gradient copolymers or mixtures thereof. According to preferred embodiments, the grinding additive is selected from the group consisting of triisopropanolamine (TIPA), triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose, or mixtures thereof. According to preferred embodiments, the grinding additive is DEIPA, or a mixture of TIPA and a sugar, or a mixture of TIPA and DEIPA, or a mixture of TIPA and glycerol, or a mixture of TIPA and diethylene glycol, or a mixture of DEIPA and glycerol, or a mixture of DEIPA and diethylene glycol. The sugar is preferably galactose, glucose, lactose, maltose, sucrose, or fructose. According to the embodiments, when the grinding additive is a mixture of TIPA and a sugar, preferably galactose, glucose, lactose, maltose, sucrose, or fructose, the molar ratio of TIPA to sugar is 1:1. According to the embodiments, when the grinding additive is a mixture of TIPA and DEIPA, the weight ratio is 1:1.According to the embodiments, when the grinding additive is a mixture of TIPA and glycerol, or is a mixture of TIPA and diethylene glycol, or is a mixture of DEIPA and glycerol or is a mixture of DEIPA and diethylene glycol, the ratio. 1729449 of 28 in respective weight is 1:1 or higher, especially from 9:1 - 1:1. The particularly preferred embodiments of the present invention are the use of a crushing aid selected from TIPA, TEA, DEIPA, EDIPA, lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose, or mixtures thereof, preferably DEIPA or a mixture of TIPA with a sugar, for the dry crushing of basic oxygen furnace slag. The crushing aids can be added to the steelmaking slag before and / or during crushing in a total amount of between 0.001 and 3% by weight, preferably 0.002 and 1% by weight, more preferably 0.01 and 0.1% by weight, in each case, with respect to the total dry weight of the slag. It is preferable that fines and / or powdered material be removed from the crushing zone during crushing. This increases crushing efficiency. Removal is preferably carried out continuously, for example, by blowing air through the crushing zone. The method of the present invention may further comprise a step of separating the crushed slag according to particle size. According to the embodiments, the separation is carried out at a predefined cut-off particle size in order to recover crushed slag with a particle size of at least the predefined cut-off particle size and / or to recover crushed slag with a particle size below the predefined cut-off particle size. According to further embodiments, it is also possible to separate the crushed slag into fractions of different particle sizes. According to the embodiment, the separation is carried out by filtration, sieving, sedimentation, density separation, wind sieving, for example, in cyclones, and / or centrifugation. The method of the present invention can be carried out in a batch or continuous process. The equipment, especially the crushers and mills, useful for the practice of the present invention are not particularly limited and are well known. According to the embodiments, the crushing is carried out in a friction mill or a compression crusher, especially a ball mill or a vertical roller mill. However, other types of mills, such as hammer mills, pebble mills, cone mills, electric mills, or jaw crushers, are equally suitable. 1729449 of 28 According to the embodiment, the dry crushing of steelmaking slag is carried out in a ball mill using steel balls with a diameter between 0.5 and 3 mm. The weight ratio of slag to steel balls is between 1:1 and 20:1. The dry crushing time can vary between 1 minute and 3 hours, preferably between 5 minutes and 1 hour, and especially between 10 and 30 minutes. In a second aspect, the present invention also relates to a crushed steelmaking slag obtained by dry crushing a steelmaking slag in the presence of a crushing additive selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers or mixtures thereof. It should be understood that all the features and embodiments described above as preferred also refer to crushed steelmaking slag. In some embodiments, the present invention relates, therefore, to a crushed basic oxygen furnace slag obtained by dry crushing a basic oxygen furnace slag in the presence of a crushing additive selected from TIPA, TEA, DEIPA, EDIPA, lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose or mixtures thereof, preferably DEIPA or a mixture of TIPA and a sugar, or a mixture of TIPA and DEIPA, or a mixture of TIPA and glycerol, or a mixture of TIPA and diethylene glycol, or a mixture of DEIPA and glycerol or a mixture of DEIPA and diethylene glycol. According to the embodiments, the steelmaking slag is a basic oxygen furnace slag and the crushing additive is diethanolisopropanolamine (DEIPA) or is a mixture of triisopropanolamine (TIPA) and a sugar, preferably galactose, glucose, lactose, maltose, sucrose or fructose, or is a mixture of TIPA and DEIPA, or is a mixture of TIPA and glycerol, or is a mixture of TIPA and diethylene glycol, or is a mixture of DEIPA and glycerol or is a mixture of DEIPA and diethylene glycol. It is preferred that the crushed steelmaking slag obtained as described above have a Blaine surface area higher than that of the steelmaking slag before crushing. Specifically, the Blaine surface area is increased by more than 10%, preferably more than 50%, and especially more than 100%. 1729449 of 28 According to the embodiments, the crushed steelmaking slag of the present invention has a Blaine surface area of ​​2000 - 12000 cm2 / g, preferably 3000 - 10000 cm2 / g, more preferably 4000 - 9000 cm2 / g, especially 6000 - 8000 cm2 / g. According to the embodiments, the crushed steelmaking slag is characterized by a residue on a 45 pm sieve not exceeding 25% and / or by a residue on a 32 pm sieve not exceeding 45%, preferably not exceeding 35%. In a third aspect, the present invention relates to a construction material, especially a mortar or concrete, comprising crushed steel manufacturing slag, as described above. The crushed steelmaking slag of the present invention is used in the construction material as a binder, as part of the binder, and / or as an aggregate. Preferably, the construction material of the present invention further comprises at least one mineral binder and, optionally, other aggregates. Preferably, the at least one mineral binder is selected from the group consisting of cement, gypsum, lime, latent hydraulic binders, pozzolans, and geopolymers. The cements may be, in particular, Portland cements described in EN 197-1, calcium aluminate cements described in EN 14647, and / or calcium sulfoaluminate cements. The term gypsum is intended to encompass CaS₄ in various forms, in particular, CaS₄ anhydrite, CaS₄ α- and β-hemihydrate, and CaS₄ dihydrate. The term lime is intended to encompass natural hydraulic lime, formulated lime, hydraulic lime and air lime, as described in EN 459-1:2015.Pozzolans and latent hydraulic materials are preferably selected from the group consisting of clay, calcined clay, especially metakaolin, kiln dust, microsilica, fly ash, zeolite, rice husk ash, burnt oil shale, and natural pozzolans such as pumice and tar. Geopolymers are aluminosilicate polymers. A particular example of a geopolymer is water-glass-activated furnace slag. The construction materials in this context optionally include additional aggregates. Aggregates can be any material that is non-reactive in the hydration reaction of hydraulic binders. Aggregates can be any aggregate normally used in construction materials. Typical aggregates include, for example, rock, crushed stone, gravel, 1729449 of 28 sand, especially quartz sand, river sand and / or artificial sand, recycled concrete, glass, expanded glass, hollow glass beads, glass ceramics, volcanic rock, pumice, perlite, vermiculite, quarry waste, raw, fired or fused clay or earth, porcelain, electrofused or sintered abrasives, firing support, silica xerogels. The aggregates may also be fine aggregates or fillers, such as crushed limestone, crushed dolomite and / or crushed aluminum oxide. The aggregates useful for the present invention may have any shape and size normally found in such aggregates. A particularly preferred aggregate is sand. Sand is a naturally occurring granular material composed of finely divided particles of rock or mineral. It is available in various shapes and sizes. Examples of suitable sands are quartz sand, limestone sand, river sand, or crushed aggregates.Suitable sands are described, for example, in ASTM C778 or EN 196-1 standards. According to the forms of realization, the aggregates can also be one or more of the following (i) - (v): (i) bio-source materials, preferably of plant origin, more preferably bio-source materials of plant origin composed essentially of cellulose and / or lignin, especially bio-source materials selected from the group comprising or consisting of hemp, flax, cereal straw, oats, rice, rapeseed, maize, sorghum, flax, Miscanthus, rice hulls, sugar cane, sunflower, kenaf, coconut, olive pits, bamboo, wood, or mixtures thereof. According to the embodiments, the bio-source materials of plant origin have a defined form and are preferably selected from fibers, fibrils, fine powder, powders, shavings, pith, in particular, pith of sunflower, maize, rapeseed, and mixtures thereof; (ii) non-mineral synthetic materials, preferably selected from the group comprising or consisting of thermoplastics, thermosets, elastomers, rubbers, textile fibers, and plastic materials reinforced with glass or carbon fibers. The non-mineral synthetic materials may be filled or unfilled; (iii) aggregates of an inorganic nature from the deconstruction of engineering structures or civil buildings, preferably selected from the group comprising or consisting of concrete waste, mortar, bricks, natural stone, asphalt, tiles, paving stones, aerated concrete, clinker, metal scrap; (iv) aggregates of an organic nature from the recycling of products 1729449 of 28 industrial materials, in particular, composite materials that are difficult to recycle, especially recycled insulating materials. Especially preferred examples are polystyrenes, polyurethanes, phenolic resins, wood insulating materials and mixtures thereof; (v) non-hazardous granular materials normally destined for landfills, such as used foundry sands, catalyst supports, Bayer process de-weeding treatment supports, clinker aggregates, charges from excavation sludge treatment, sewage sludge, mud, paper waste, paper incineration ash, household waste incineration ash. Most preferably, the aggregates are in particulate form. Optionally, a construction material of the present invention may further comprise at least one additive selected from the group consisting of plasticizers, superplasticizers, shrinkage reducers, air entrainers, deaerating agents, stabilizers, viscosity modifiers, water reducers, accelerators, retarders, water-resistant agents, strength-enhancing additives, fibers, blowing agents, defoamers, redispersible polymer powders, chromate reducers, pigments, and steel passivating agents. A construction material of the present invention may be in a dry state. Typically, dry construction materials are in powder form. A dry construction material may be, in particular, a dry mortar or a dry concrete. Dry construction materials preferably have a water content of no more than 5%, more preferably no more than 2%, and especially no more than 1%, in each case, with respect to the total weight of the binder present in the dry construction material. A construction material of the present invention may also be in a wet state. Typically, wet construction materials are in the form of slurries in water. A wet construction material may be, in particular, a dry mortar or a dry concrete mixed with water. Wet construction materials preferably have a water-to-mineral binder mass ratio of between 0.1 and 0.8, preferably 0.25 and 0.6, and especially 0.3 and 0.5. A construction material of the present invention can also be in a hardened state. The hardening of a dry construction material of the present invention begins when water is added. After hardening, the material 1729449 of 28 construction reaches its final strength. A hardened building material can have any desired shape. A hardened building material can be a building or be part of a building. Specifically, a building material can be dry concrete or dry mortar. A construction material of the present invention comprises or consists of (in each case, with respect to the total dry mass of the construction material) a) 1-99% by weight of a crushed steelmaking slag as described above; b) 1-99% by weight of at least one mineral binder, preferably selected from the group consisting of cement, gypsum, lime, latent hydraulic binders, pozzolans and geopolymers; c) optionally, 15-85% by weight of aggregates; d) optionally, 0.1–10% by weight of additional additives; and e) optionally, water in an amount to obtain a water:mineral binder mass ratio between 0.1 - 0.8, preferably 0.25 - 0.6, especially 0.3 - 0.5. According to the embodiments, a construction material of the present invention comprises a) 5-75% by weight, preferably 6-20% by weight or 25-75% by weight of crushed steelmaking slag as described above; b) 1-75% by weight, preferably 5-50% by weight of at least one mineral binder, preferably selected from the group consisting of cement, gypsum, lime, latent hydraulic binders, pozzolans and geopolymers; c) 15-85% by weight of aggregates; d) optionally, 0.1–10% by weight of additional additives; and e) optionally, water in an amount to obtain a water:mineral binder mass ratio between 0.1 - 0.8, preferably 0.25 - 0.6, especially 0.3 - 0.5. According to the additional embodiments, a construction material of the present invention consists of a) 5-75% by weight, preferably 6-20% by weight or 25-75% by weight of crushed steelmaking slag as described above; b) 1-75% by weight, preferably 5-50% by weight of at least one binder 1729449 of 28 mineral, preferably selected from the group consisting of cement, gypsum, lime, latent hydraulic binders, pozzolans and geopolymers; c) 15-85% by weight of aggregates; d) optionally, 0.1–10% by weight of additional additives; and e) optionally, water in an amount to obtain a water:mineral binder mass ratio between 0.1 - 0.8, preferably 0.25 - 0.6, especially 0.3 - 0.5. According to the additional embodiments, a construction material of the present invention comprises a) 5-75% by weight, preferably 6-20% by weight or 25-75% by weight of a crushed basic oxygen slag as described above; b) 1-75% by weight, preferably 5-50% by weight of Portland cement; c) 15-85% by weight of aggregates; d) optionally, 0.1–10% by weight of additional additives; and e) optionally, water in an amount to obtain a water:mineral binder mass ratio between 0.1 - 0.8, preferably 0.25 - 0.6, especially 0.3 - 0.5. According to the embodiments, a construction material of the present invention comprises or consists of (with respect to the total dry mass of the construction material, unless otherwise stated) a) 0.9901 - 99% by weight of crushed steelmaking slag; a1) 0.001 - 3% by weight, preferably 0.002 - 1% by weight, more preferably 0.01 - 0.1% by weight, with respect to the total dry weight of the slag, of at least one additive selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers and superabsorbent polymers; b) 0.9901 - 99% by weight of at least one mineral binder, preferably selected from the group consisting of cement, gypsum, lime, latent hydraulic binders, pozzolans and geopolymers; c) optionally, 15-85% by weight of aggregates; d) optionally, 0.1–10% by weight of additional additives; and e) optionally, water in an amount to obtain a water:mineral binder mass ratio between 0.1 - 0.8, preferably 0.25 - 0.6, especially 0.3 - 0.5. 1729449 of 28 All the embodiments described above also apply to this embodiment. In particular, the crushed steelmaking slag is as described above and the at least one additive is selected from triisopropanolamine (TIPA), triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose or mixtures thereof, preferably selected from DEIPA or a mixture of TIPA and a sugar, or is a mixture of TIPA and DEIPA, or is a mixture of TIPA and glycerol, or is a mixture of TIPA and diethylene glycol, or is a mixture of DEIPA and glycerol or is a mixture of DEIPA and diethylene glycol. In a fourth aspect, the present invention relates to a method for increasing the efficiency of dry crushing of steelmaking slag, characterized in that the steelmaking slag is dry crushed together with an additive selected from triisopropanolamine (TIPA), triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose or mixtures thereof, preferably selected from DEIPA or a mixture of TIPA and a sugar, or a mixture of TIPA and DEIPA, or a mixture of TIPA and glycerol, or a mixture of TIPA and diethylene glycol, or a mixture of DEIPA and glycerol or a mixture of DEIPA and diethylene glycol, and in that said additive is added to the slag before and / or during crushing. An increase in dry crushing efficiency is, for example, a shorter crushing time required to achieve a specific Blaine surface area of ​​the crushed slag. The Blaine surface area can be measured as described above. An increase in dry crushing efficiency is also, for example, a smaller amount of material adhering to mill parts during and after crushing. Therefore, the present invention relates to a method for increasing the efficiency of dry crushing of steelmaking slag, said method comprising the steps of (i) providing steelmaking slag as described above, (ii) providing an additive selected from triisopropanolamine (TIPA), triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, 1729449 of 28 sucrose, fructose or mixtures thereof, preferably selected from DEIPA or a mixture of TIPA and a sugar or a mixture of TIPA and DEIPA, or a mixture of TIPA and glycerol, or a mixture of TIPA and diethylene glycol, or a mixture of DEIPA and glycerol or a mixture of DEIPA and diethylene glycol, (iii) dry crushing said steelmaking slag, and (iv) intermixing said additive with said steelmaking slag before and / or during step (iii). All the features and embodiments described above as preferred also apply to this aspect. In a fifth aspect, the present invention relates to a method for increasing the early strength of a construction material comprising crushed steelmaking slag, characterized in that an additive is added to a steelmaking slag before and / or during the crushing of said steelmaking slag and characterized in that the additive is selected from triisopropanolamine (TIPA), triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose or mixtures thereof, preferably selected from DEIPA or a mixture of TIPA and a sugar, or a mixture of TIPA and DEIPA, or a mixture of TIPA and glycerol, or a mixture of TIPA and diethylene glycol, or a mixture of DEIPA and glycerol or a mixture of DEIPA and diethylene glycol.There is no complete extraction stage of the crushing additive from the crushed steelmaking slag after dry crushing. Early strength refers to the compressive and / or flexural strength of a building material after it has hardened for no more than 7 days, preferably after hardening for 1, 2, and / or 3 days. Compressive strength can be measured according to EN 12190 on 4 x 4 x 16 cm prisms. Flexural strength can be measured according to EN 196-1 on 40 x 40 x 160 mm prisms. In particular, the early strength of a construction material comprising crushed steelmaking slag of the present invention is improved with respect to the same construction material, but comprising crushed steelmaking slag, having the same Blaine surface and / or particle size and crushed without the addition of an additive of the present invention. Therefore, the present invention relates to a method for increasing the 1729449 of 28 early strength of a cementitious material comprising crushed steelmaking slag, said method comprising the steps of (i) providing crushed steelmaking slag as described above, (ii) intermixing said crushed steelmaking slag with at least one mineral binder, (iii) optionally, intermixing the mixture obtained in step (ii) with additional aggregates and additives, and (iv) optionally, intermixing the mixture obtained in step (ii) or (iii) with water. All the features and embodiments described above as preferred also apply to this aspect. According to the particular embodiments, the method is characterized in that the crushed steelmaking slag comprises an additive selected from triisopropanolamine (TIPA), triethanolamine (TEA), diethanolisopropanolamine (DEIPA), ethanoldiisopropanolamine (EDIPA), lactic acid, malonic acid, adipic acid, citric acid, galactose, glucose, lactose, maltose, sucrose, fructose or mixtures thereof, preferably selected from DEIPA or a mixture of TIPA and a sugar, or a mixture of TIPA and DEIPA, or a mixture of TIPA and glycerol, or a mixture of TIPA and diethylene glycol, or a mixture of DEIPA and glycerol or a mixture of DEIPA and diethylene glycol, the additive being added to said steelmaking slag before and / or during the crushing of said steelmaking slag. The following examples will provide the person skilled in the art with additional details and ways of carrying out the present invention. Examples Table 1 below shows a summary of the raw materials used. Table 1: Raw materials BOF slag Basic oxygen furnace slag with an initial Blaine surface of 1410 g / cm2 56% retained on a 45 µm sieve; 68% retained on a 32 µm sieve TIPA Triisopropanolamine (1,1',1''-nitrilotris(propan-2-ol)), Sigma-Aldrich, 95% purity 1729449 of 28 TEA Triethanolamine, Sigma-Aldrich, purity >99% DEIPA Diethanolisopropanolamine, Sigma-Aldrich, purity 94% EDIPA Ethanoldiisopropanolamine, purity 95% Polyaspartic acid Baypure Lactic acid Sigma-Aldrich, purity >98% Malonic acid Sigma-Aldrich, purity 99% Adipic acid Sigma-Aldrich, purity 99% Citric acid Sigma-Aldrich, purity 99% Calcium lactate Pentahydrate, Sigma-Aldrich Fructose D-(-)-fructose, Sigma-Aldrich, purity >99% Glucose D-(+)-glucose, Sigma-Aldrich, purity >99.5% GLY Glycerol, Sigma-Aldrich, purity >99.0% DEG Diethylene glycol, Sigma-Aldrich, purity >99.0% The Blaine surface measurement was performed in accordance with the NF EN standard 196-6. The sieve analysis was performed in accordance with ASTM C136 / C136M. The amount of material adhering to the balls and the container was determined by weighing. The compressive strength was measured according to EN 12190 on 4 x 4 x 16 cm prisms after 7 days of curing at 23 °C / 50% RH of a mixture consisting of 90% by weight of crushed BOF slag as per the respective example and 10% by weight of hydrated air-dried lime mixed with water in a water:powder weight ratio of 0.36. Example 1 40 g of BOF slag were heated to 100 °C and then loaded into a ball mill. 260 g of steel balls were then added (the container and balls were preheated to 100 °C). The respective crushing aids were then added as shown in Table 2 below at a rate of 0.015 wt% relative to the weight of the BOF slag. All crushing aids were diluted with water prior to addition to introduce 0.06 wt% of water relative to the BOF slag. In the event that a mixture of two crushing aids was used, each of the 21 1729449 of 28 crushing aids was introduced in an amount of 0.015% by weight relative to the weight of the BOF slag and the mixture was diluted in water prior to addition in an amount to introduce 0.06% by weight of water relative to the BOF slag. Next, grinding was carried out for 5 minutes. After this time, a sample was taken for Blaine surface analysis, and grinding continued for another 5 minutes. After a total grinding time of 10 minutes, the Blaine surface of the resulting slag was measured, and the amount of material adhering to the grinding balls and the container was determined. Table 2 below provides a summary of the results. Example 1 is a comparative example not in accordance with the invention. Examples 2-13 are in accordance with the present invention. Table 2: Results 1 2 3 4 5 6 7 8 Type of grinding aid none TIPA TEA DEIPA OEDIPA Polyaspartic acid Lactic acid Adipic acid Blaine at 5 min [g / cm2] 2050 2250 2340 2900 2250 2220 2320 2160 Blaine at 10 min [g / cm2] 2470 2630 2630 3220 2640 2630 2770 2700 Residue on 45 pm sieve [%] 22 21 15 13 13 14 16 22 Residue on 32 pm sieve [%] 48 42 37 29 40 32 37 37 Adhesive material*1 [%] 14 11 10 4 10 8 5 5 Compressive strength [MPa] 0.7 9.7 nm 7.6 nm *1 sum of material that adheres to the balls and the container with respect to the slag 1729449 of 28 total BOF entered nm: not measured Table 2 (continued) 9 10 11 12 13 Type of trituration aid Malonic acid Calcium lactate TIPA and glucose TIPA and fructose TIPA and citric acid Blaine at 5 min [g / cm2] 2390 2480 2630 2520 2520 Blaine at 10 min [g / cm2] 2710 2670 2850 2950 3170 Residue on 45 pm sieve [%] 19 16 22 18 18 Residue on 32 pm sieve [%] 40 41 38 35 38 Adhesive material*1 [%] 7 4 8 5 4 *1 Sum of material adhering to the balls and the container with respect to the total BOF slag introduced As can be seen from the previous results, adding an additive during the dry crushing of basic oxygen slag leads to a larger Blaine surface area, which can be achieved after 5 or 10 minutes of crushing. This means that the crushing efficiency is higher with the respective added crushing additive. A larger Blaine surface area can be obtained in the same crushing time, or less time is needed to crush the BOF slag to reach the desired Blaine surface area. It can also be deduced from the above results that the use of the 15th invention of crushing aids during crushing leads to a crushed BOF slag comprising finer particles. This means that the overall particle size is reduced. This is evident from the lower number of particles retained on a 45 µm or 32 µm sieve, in the case where crushing was carried out 1729449 of 28 with the additive compared to the case where no additive was added. Finally, the above results show that the use of the invention's crushing aids leads to a smaller amount of crushed material adhering to the balls and the ball mill bowl. This is also an indication of increased crushing efficiency. Example 2 Example 2 was carried out in the same manner as Example 1, except that the type and quantities of grinding aids used were as indicated in Table 3 below. Examples 14-29 are in accordance with the present invention. Table 3: Results 14 15 16 17 Type of grinding aid TIPA and DEIPA (25:75 wt. %) TIPA and DEIPA (50:50 wt. %) TIPA and DEIPA (75:25 wt. %) TIPA and DEIPA (75:25 wt. %) Total amount of grinding aid added*1 0.015 0.015 0.015 0.075 Blaine at 5 min [g / cm2] 2260 2310 2520 3170 Blaine at 10 min [g / cm2] 2920 2830 3030 3400 Residue on 45 µm sieve [%] 14 5 6 8 Residue on 32 µm sieve [%] 34 39 33 24 Adhesive material*2 [%] 2.5 1.9 2 0.9 Resistance to 6.5 6.1 6.5 8.9 1729449 of 28 compression [MPa] 1% by weight with respect to the weight of BOF slag *2 sum of material adhering to the balls and the vessel with respect to the total BOF slag introduced Table 3 (continued) 18 19 20 21 Type of grinding aid TIPA and GLY (50:50 wt.) DEIPA and GLY (50:50 wt.) TIPA and DEG (50:50 wt.) DEIPA and DEG (50:50 wt.) Total amount of grinding aid added*1 0.015 0.015 0.015 0.015 Blaine at 5 min [g / cm2] 2320 2470 2370 2390 Blaine at 10 min [g / cm2] 3020 2470 2370 2390 Residue on 45 µm sieve [%] 12 14 13 4 Residue on 32 µm sieve [%] 39 30 32 30 Adhesive material*2 [%] 1.6 1.6 1.9 1.8 Compressive strength [MPa] 6.8 7.1 6.6 6.5 % by weight with respect to the weight of BOF slag *2 sum of material adhering to the balls and the container with respect to the total BOF slag introduced 1729449 of 28 Table 3 (continued) 22 23 24 25 Type of grinding aid TIPA and DEG (80:20 wt. %) TIPA and DEG (30:70 wt. %) DEIPA and DEG (60:40 wt. %) DEIPA and DEG (33:66 wt. %) Total amount of grinding aid added*1 0.075 0.075 0.1 0.1 Blaine at 5 min [g / cm2] 2970 2750 3420 2860 Blaine at 10 min [g / cm2] 3250 3250 3540 3390 Residue on 45 pm sieve [%] 6 10 4 15 Residue on 32 pm sieve [%] 22 25 22 20 Adhesive material*2 [%] 0.9 1.3 0.7 0.8 Compressive strength [MPa] 10 6.9 10.6 10.5 1% by weight with respect to the weight of BOF slag *2 sum of material adhering to the balls and the vessel with respect to the total BOF slag introduced 1729449 of 28 Table 3 (continued) 26 27 28 29 Type of grinding aid TIPA and GLY (60:40 wt. %) TIPA and GLY (14:86 wt. %) DEIPA and GLY (60:40 wt. %) DEIPA and GLY (33:66 wt. %) Total amount of grinding aid added*1 0.1 0.1 0.1 0.1 Blaine at 5 min [g / cm2] 3090 2760 3170 2930 Blaine at 10 min [g / cm2] 3380 3250 3390 3410 Residue on 45 µm sieve [%] 6 10 6 15 Residue on 32 µm sieve [%] 20 28 20 24 Adhesive material*2 [%] 0.8 1.3 1.0 1.5 Compressive strength [MPa] 10.0 10.1 11.4 10.2 *1 *2 % by weight with respect to the weight of BOF slag; sum of material adhering to the balls and the vessel with respect to the total BOF slag introduced It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A method for dry crushing steelmaking slag, characterized in that the crushing additive is selected from mixtures of triisopropanolamine and diethanolisopropanolamine, triisopropanolamine and glycerol, triisopropanolamine and diethylene glycol, diethanolisopropanolamine and glycerol, diethanolisopropanolamine and diethylene glycol, triisopropanolamine and glucose, triisopropanolamine and fructose, triisopropanolamine and citric acid, diethanolisopropanolamine and glucose, diethanolisopropanolamine and citric acid, triisopropanolamine and glucose and diethylene glycol, triisopropanolamine and citric acid and diethylene glycol, triisopropanolamine and diethylene glycol and tri(isobutyl)phosphate, diethanolisopropanolamine and diethylene glycol and tri(isobutyl)phosphate, and diethanolisopropanolamine and fructose and glycerol;wherein the steelmaking slag has an iron oxide content expressed as Fe2O3 of 8-38% by weight, and a sulfur content expressed as SO3 of <1% by weight, in each case, with respect to the total dry weight of the steelmaking slag, and wherein the crushing additive is added to the steelmaking slag before and / or during crushing in a total amount of between 0.001-3% by weight with respect to the total dry weight of the slag. Seven claims follow;