Fluorite synthetic stone and method for producing fluorite synthetic stone

Abstract

The fluorite synthetic stone comprises (a) a glass matrix containing Ca, Si, and O and having a predetermined weight ratio of Ca to Si, and (b) CaF dispersed in the glass matrix at a concentration of at least about 70% by weight. 2 The method for making a fluorite synthetic stone includes adding CaF crystals having a concentration of at least about 70% by weight. 2 The method includes blending a particulate mixture comprising the crystals and an excipient having a predetermined weight ratio of Ca and Si. An aggregate is prepared from the particulate mixture. The aggregate is heat treated to form a plurality of fluorite-type synthetic stones, each synthetic stone comprising a glass matrix comprising Ca, Si, and O, and CaF dispersed in the glass matrix at a concentration of at least about 70% by weight. 2 Crystals.

Description

[Technical field]

[0001] Related Applications This patent document claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 63 / 339,019, filed May 6, 2022, and is incorporated by reference herein in its entirety.

[0002] Technical Field The present disclosure relates generally to slag additives for the steel industry, and more specifically to fluorite-type synthetic minerals. [Background technology]

[0003] The refining process in steel production is an intensive process due to the injection of oxygen. Some reactions occur in the hot metal, others at the slag-metal interface or at the slag-gas interface. The interaction of the slag with the gas produces a "foam". Viscosity controls the foam properties. Secondary refining of steel aims to reduce the impurities of carbon, sulfur, and phosphorus to very low levels. The slag floats on the molten metal to protect the surface from oxidation and absorb the impurities dissolved in the molten metal. The typical composition of the slag is high in CaO with some addition of MgO. Fluorspar, a mineral containing CaF2, may be used as a slag additive or flux to improve the removal of impurities such as sulfur and phosphorus from the molten metal and / or to improve the fluidity of the slag. However, relying on fluorspar, a natural stone product with uncontrolled supply, can jeopardize the supply chain. [Brief description of the drawings]

[0004] [Figure 1] 1 is a flow chart of an exemplary method for producing a fluorite synthetic stone. [Diagram 2] 1 is a photograph of an exemplary fluorite synthetic stone. [Figure 3A]FIG. 1 shows a portion of the X-ray diffraction pattern of an aggregate (uncalcined sample) prepared from a blend of beneficiated fluorspar and slime having a Ca to Si weight ratio of approximately 2:1. [Figure 3B] A portion of the X-ray diffraction pattern of a synthetic stone (calcined sample) prepared from a blend of beneficiated fluorspar and slime with a Ca to Si weight ratio of approximately 2:1 is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] In this disclosure, fluorite synthetics with high CaF2 content and stone-like properties for use in steelmaking and other applications are described. The fluorite synthetics, fabricated using a novel method including compounding, agglomeration, and calcination, have a composite structure containing CaF2 crystals at a concentration of at least about 70% by weight (typically higher) dispersed in a glass matrix containing Ca, Si, and O. When prepared under suitable process conditions and with a predetermined weight ratio of Ca to Si, the fluorite synthetics may contain intergranular (matrix) phases surrounding the CaF2 crystals, which are believed to contribute to the exceptional properties of the synthetic stone products. For example, the synthetics may exhibit wear resistance, compressive strength, and / or water absorption properties equal to or greater than those of natural stones. The fabrication process may be controlled so that the fluorite synthetics contain little or no carbon, sulfur, and / or phosphorus, impurities that may be detrimental to steelmaking. The synthetics may be added to steelmaking furnaces containing molten steel and slag to reduce the viscosity of the slag and / or increase the ability of the slag to remove impurities (e.g., sulfur) from the molten steel. Typically, 2-10 kg of fluorite synthetic mineral may be added per tonne of steel.

[0006] Before the fluorite synthetics are described in detail, a method of making the synthetics will be described with reference to FIG. 1. It should be noted that the terms "fluorite synthetics" and "synthetic stones" are used interchangeably throughout this disclosure. Broadly speaking, the method (100) includes compounding (102) a particulate mixture including (a) CaF2 crystals at a concentration of at least about 70% by weight, and (b) an excipient having a predetermined weight ratio of Ca and Si. An aggregate is then prepared (104) from the particulate mixture, and the aggregate is heat treated (106) to form a plurality of fluorite synthetic stones, each of which has a composite structure including a glass matrix including Ca, Si, and O, and CaF2 crystals dispersed in the glass matrix at a concentration of at least about 70% by weight. More specifically, the glass matrix may include Ca and Si in a predetermined weight ratio, as discussed below.

[0007] Blending the particulate mixture (102) may involve multiple steps, as shown in FIG. 1. First, particulate material may be obtained from a mining operation (108). This may involve collecting fluorspar from the mining operation as well as lower grade materials such as sludge, tailings, and slimes, followed by drying and / or sieving, as necessary, to obtain the particulate material. Various grades of fluorspar may be suitable. For example, the fluorspar may be acid grade or beneficiated fluorspar concentrated to 97% or more CaF2. Alternatively, non-compliant acid grade fluorspar containing about 90% CaF2 may be used.

[0008] The chemical content of the particulate material is then determined (110). Of particular interest are the concentrations of Ca, F, and Si, which may be used to estimate the amount of CaF2, SiO2CaO, and / or CaCO3 in the particulate material. Chemical analysis methods such as X-ray fluorescence (XRF), which is capable of determining concentrations of elements heavier than oxygen if suitable equipment is used, may be used to determine the chemical content (110).

[0009] Once the chemical content is known, selected fractions of the particulate materials are combined (112) to form the particulate mixture described above. The filler is believed to contain Ca, Si, and O, with little or no undesirable impurities such as S and P. Preferably, the filler contains S at a concentration of less than about 0.1% by weight and / or no S. Also, or alternatively, the filler preferably contains P at a concentration of less than about 0.1% by weight and / or no P. Any C present in the filler is substantially or completely removed during downstream processing steps (heat treatment). In some applications where it may be beneficial to have additional ceramic components in the fluorite-type synthetic stone product, one or more additional particulate materials, such as Al2O3 and / or MgO, may be added to the particulate mixture in desired amounts at this point in the process.

[0010] Agglomerates are then prepared from the particulate mixture (104), for example, by mixing a binder into the particulate mixture followed by granulation, compression, extrusion, pelletizing, briquetting, and / or another molding method to form the agglomerates. For example, granulation to form the agglomerates can be performed in a rotating drum / disk or a briquette machine or extruder can be used. The size of the agglomerates can range from a few millimeters to a few centimeters in linear size (width or diameter). The binder added to the particulate mixture can include organic binders, inorganic binders, and / or aqueous binders. In one example, the binder can include a sodium silicate solution (water glass). Typically, the binder is added to the particulate mixture in an amount of about 0.5% to about 10% by weight, or about 5% to about 7% by weight.

[0011] In some instances, the aggregates are dried to improve the green strength of the aggregates prior to further processing. Drying the aggregates may include evaporating or curing the binder and may be performed passively (e.g., in air) or actively (e.g., in an oven at a suitable temperature).

[0012] The aggregate undergoes a heat treatment (106) to perform calcination and decarburization. A plurality of calcined synthetics, such as those shown in FIG. 2, are formed in the heat treatment (106), each of which includes CaF2 crystals dispersed in a glass matrix including Ca, Si, and O at a concentration of at least about 70% by weight. More typically, the concentration of CaF2 crystals is 80% by weight or more, or 90% by weight or more. In some examples, the CaF2 crystals may be present at a concentration of at least about 92% by weight, or at least about 94% by weight, and / or as high as about 96% by weight. Under the conditions of the heat treatment, the filler having a predetermined ratio of Ca to Si forms a glass matrix at least partially surrounding the CaF2 crystals. In addition, the CaCO3 present in the filler may decompose into CO2 gas and CaO, which may combine with silicon. The heat treatment may be performed at a temperature of at least about 950° C., or at least about 1000° C. Typically, the temperature is about 1200° C. or less and / or below the melting temperature of CaF2. The duration of the heat treatment can be at least about 20 minutes, at least about 40 minutes, or at least about 60 minutes, and / or up to about 120 minutes. The heat treatment can be performed until CaCO3, CaO, and / or SiO2 crystals are not detectable by X-ray diffraction (XRD) and / or the carbon content is less than 1 wt.%. In some examples, as discussed below, the excipient may contain excess Si, and thus the SiO2 peak may not completely disappear from the XRD pattern. Preferably, the CaCO3 and / or CaO peaks completely disappear. The heat treatment can involve furnace heating or microwave heating. The heat treatment can be performed in air. In the latter case, the aggregates can be embedded in a susceptor material, such as carbon, before performing microwave heating.

[0013] The glass matrix of the fluorite synthetic stone may include one or more silicates and / or oxides, such as Ca-Si-O compounds (e.g., Ca2SiO3 and / or Ca2SiO4 (2CaO·SiO2)), Si-O compounds (e.g., SiO2), and / or Ca-O compounds (e.g., CaO). The glass matrix may be partially or completely amorphous (non-crystalline). Thus, in some examples, the glass matrix may be at least partially crystalline. It is also contemplated that under some process conditions, the glass matrix may be completely crystallized. Preferably, the synthetic stone includes less than about 1 wt. % free CaO (i.e., CaO that is not part of Ca-Si-O compounds) and other water-absorbing phases to reduce water absorption by the synthetic stone. The glass matrix may be partially fluorinated. Due to decarburization during heat treatment, the amount of carbon in the fired synthetic stone may be less than about 1 wt. %, less than about 0.1 wt. %, and / or preferably below the detection limit of the measurement method.

[0014] To obtain the desired glass matrix, the predetermined weight ratio of Ca to Si in the excipient is preferably greater than 1, for example, about 2:1 to about 4:1. With a Ca to Si ratio within this range, the fluorite synthetic stone produced upon firing may contain an amorphous intergranular phase that at least partially surrounds the CaF2 crystals. This amorphous intergranular phase, i.e., the glass matrix, may contain Ca and Si in a predetermined weight ratio (for example, greater than 1, or about 2:1 to about 4:1), which may contribute to the exceptional mechanical integrity and low water absorption of the fluorite synthetic stone.

[0015] In some applications, the filler may contain a Ca to Si weight ratio of 1 or less (e.g., 0.4:1 to 1:1). At lower Ca to Si ratios, the fluorite synthetic stone may contain Si-containing crystalline phases, such as SiO2, dispersed in the glass matrix in addition to CaF2 crystals. High amounts of Si (or low Ca to Si weight ratios) may hinder firing, but the resulting fluorite synthetic stone may have increased compressive strength values ​​due to the presence of Si-containing crystalline phases. At lower Si contents (e.g., Ca:Si>4:1), the water absorption of the fluorite synthetic stone produced by the method may be adversely increased due to free CaO remaining in the fired stone. As noted above, the fluorite synthetic stone preferably contains a limited amount of free CaO.

[0016] Figures 3A and 3B show portions of the X-ray diffraction patterns of an aggregate (unfired sample) and a synthetic stone (fired sample), respectively, prepared from a blend of beneficiated fluorspar and slime with a Ca to Si weight ratio of about 2. The fired sample was heat treated at 1200°C for 60 minutes. As can be seen, the peaks in Figure 3A corresponding to crystalline SiO2 and CaCO3 are absent in Figure 3B, indicating amorphization during heat treatment. In addition, new low intensity peaks (indicated by arrows) that may correspond to vitreous silicate phases (e.g., CaSiO3) are observed in Figure 3B.

[0017] The CaF2 crystals in the fluorite synthetic stone may have a linear size (e.g., length and / or width) ranging from about 500 nm to about 500 microns, or more typically from about 1 micron to about 150 microns. The CaF2 crystals may have a multimodal size distribution in the glass matrix. As discussed above with respect to the Ca:Si ratio, the synthetic stone may further include SiO2 crystals dispersed in the glass matrix in some examples. The synthetic stone may also, or alternatively, include additional ceramic components such as Al2O3 crystals and / or MgO crystals dispersed in the glass matrix. These optional additional ceramic crystals may have a linear size in the ranges described above for CaF2 crystals, and / or they may have a multimodal size distribution. Due to the high temperature of the heat treatment, the binder present in the aggregates may be thermally decomposed or evaporated, and thus the fluorite synthetic stone may be free of binders (e.g., organic or aqueous binders). In other instances, such as when inorganic binders are used, the binder may undergo chemical conversion during heat treatment and may remain in the synthetic stone product in the converted chemical state.

[0018] The porosity in the aggregates is significantly reduced during heat treatment and the resulting fired synthetic stone may contain primarily or exclusively closed pores. Fluorite-type synthetic stones have a porosity of about 2.2 g / cm3, as determined by a buoyancy test based on Archimedes' principle. 3 ~About 3g / cm 3 The fired stones may have a nominal linear size (width or diameter) ranging from a few millimeters to a few centimeters.

[0019] The fluorite-type synthetic stone prepared as described herein may exhibit properties and characteristics equal to or greater than those of natural stone. For example, the synthetic stone may exhibit high resistance to wear when subjected to a 60-minute rotating drum test, with mass loss from the sample being about 7% by weight or less. Preliminary experiments reveal that the synthetic stone can withstand an average compressive force of at least about 1330 N before fracturing. The synthetic stone may also, or alternatively, exhibit water absorption of about 0.1% by weight or less after 6 days in a humidity chamber (relative humidity greater than 90%).

[0020] The subject matter of the present disclosure can also relate to, among other aspects, the following aspects:

[0021] Aspect 1 relates to a fluorite synthetic stone, the fluorite synthetic stone including a glass matrix containing Ca, Si, and O and having a predetermined weight ratio of Ca to Si, and CaF2 crystals dispersed in the glass matrix at a concentration of at least about 70% by weight.

[0022] Aspect 2 relates to the fluorite-type synthetic stone according to Aspect 1, wherein the predetermined weight ratio of Ca to Si exceeds 1 and / or the predetermined weight ratio of Ca to Si is from about 2:1 to about 4:1.

[0023] Example 3 relates to a fluorite-type synthetic stone according to any one of the preceding examples, wherein the predetermined weight ratio of Ca to Si is less than 1.

[0024] Example 4 relates to a fluorite synthetic stone of any one of the preceding examples, wherein the concentration is at least about 80% by weight, at least about 90% by weight, at least about 92% by weight, or at least about 94% by weight, and / or as high as about 96% by weight.

[0025] Example 5 relates to a fluorite synthetic stone according to any one of the preceding examples, wherein the glass matrix comprises one or more silicates and / or oxides.

[0026] Example 6 relates to the fluorite synthetic stone of Example 5, wherein the glass matrix comprises a Ca-Si-O compound selected from the group consisting of Ca2SiO3 and Ca2SiO4 (2CaO·SiO2).

[0027] Example 7 relates to a fluorite synthetic stone according to any one of the preceding examples, wherein the glass matrix is ​​partially fluorinated.

[0028] Example 8 relates to the fluorite synthetic stone of any one of the preceding examples, comprising free CaO at a concentration of less than about 1 wt.%.

[0029] Example 9 relates to the fluorite synthetic stone of any one of the preceding examples, wherein the CaF2 crystals have a linear size ranging from about 500 nm to about 500 microns.

[0030] Example 10 relates to the fluorite synthetic stone of Example 9, having a linear size ranging from about 1 micron to about 150 microns.

[0031] Example 11 relates to the fluorite synthetic stone of any one of the preceding examples, wherein the CaF2 crystals have a multimodal size distribution.

[0032] Example 12 relates to the fluorite synthetic stone of any one of the preceding examples, further comprising SiO2 crystals dispersed in the glass matrix.

[0033] Example 13 relates to the fluorite synthetic stone of any one of the preceding examples, further comprising Al2O3 crystals and / or MgO crystals dispersed in the glass matrix.

[0034] Example 14 relates to a fluorite synthetic stone of any one of the preceding examples, comprising C in a concentration of less than about 1 wt. % and / or no C.

[0035] Example 15 relates to the fluorite synthetic stone of any one of the preceding examples, comprising CaC0 in a concentration of less than about 2 wt.% and / or comprising no CaC0.

[0036] Example 16 relates to a fluorite synthetic stone of any one of the preceding examples, comprising S at a concentration of less than about 0.1 wt.% and / or no S.

[0037] Example 17 relates to a fluorite synthetic stone of any one of the preceding examples, comprising P at a concentration of less than about 0.1 wt.% and / or no P.

[0038] Example 18 relates to a fluorite synthetic stone of any one of the preceding examples that does not include a binder.

[0039] Embodiment 19 has a buoyancy of about 2.2 g / cm as determined by the Archimedes principle buoyancy test. 3 ~About 3g / cm 3 The present invention relates to a fluorite-type synthetic stone as described in any one of the preceding embodiments, having a density in the range of

[0040]

[0023] Example 20 relates to a fluorite synthetic stone of any one of the preceding examples, having high resistance to abrasion, wherein a sample of the fluorite synthetic stone loses no more than about 7% by weight after being subjected to a 60 minute rotating drum test.

[0041] Example 21 relates to a fluorite synthetic stone of any one of the preceding examples, wherein the fluorite synthetic stone maintains an average compressive force of at least about 1330 N before failure.

[0042] Example 22 relates to a fluorite synthetic stone of any one of the preceding examples, exhibiting water absorption of about 0.1% by weight or less after 6 days in a humidity chamber (relative humidity greater than 90%).

[0043] Example 23 relates to a fluorite synthetic stone of any one of the preceding examples having a nominal size ranging from a few millimeters to a few centimeters.

[0044]

[0023] Example 24 relates to a method of using the fluorite synthetic ore of any one of the preceding embodiments, the method comprising adding a plurality of the fluorite synthetic ores to a steelmaking furnace containing slag and molten steel.

[0045] Example 25 relates to a method according to the preceding example, wherein the addition of a fluorite synthetic stone reduces the viscosity of the slag.

[0046] Example 26 relates to the method of any one of the preceding examples, wherein the addition of the fluorite synthetic mineral increases the ability of the slag to remove sulfur from the molten steel.

[0047]

[0023] Aspect 27 relates to a method of making a fluorite synthetic stone, the method including: compounding a particulate mixture including CaF2 crystals at a concentration of at least about 70% by weight and an excipient having a predetermined weight ratio of Ca and Si; preparing an agglomerate from the particulate mixture; and heat treating the agglomerate to form a plurality of fluorite synthetic stones, each fluorite synthetic stone including a glass matrix including Ca, Si, and O, and CaF2 crystals dispersed in the glass matrix at a concentration of at least about 70% by weight.

[0048] Example 28 relates to a method as described in the preceding example, where blending the particulate mixture includes obtaining particulate material from a mining operation, determining a chemical content of the particulate material, and combining selected fractions of the particulate material to form the particulate mixture.

[0049] Example 29 relates to the method of any one of the preceding examples, wherein determining the chemical content of the particulate material includes determining a Ca, F, and Si content.

[0050] Example 30 relates to the method of the preceding example, wherein determining the chemical content of the particulate material further comprises estimating the amount of CaF2, SiO2, CaO, and / or CaCO3.

[0051] Example 31 relates to a method of any one of the preceding examples, wherein determining the chemical content of the particulate material includes performing X-ray fluorescence analysis on the particulate material.

[0052] Example 32 relates to the method of any one of the preceding examples, further comprising adding one or more additional particulate materials to the particulate mixture after combining the particulate mixture.

[0053] Example 33 relates to a method according to the preceding example, wherein the one or more additional particulate materials are selected from the group consisting of Al2O3 and MgO.

[0054] Example 34 relates to the method of any one of the preceding examples, wherein the predetermined weight ratio is greater than 1.

[0055] Example 35 relates to the method of any one of the preceding examples, wherein the predetermined weight ratio is from about 2:1 to about 4:1.

[0056] Example 36 relates to the method of any one of the preceding examples, wherein the predetermined weight ratio is less than 1.

[0057] Example 37 relates to the method of any one of the preceding examples, wherein preparing the aggregate comprises mixing a binder with the particulate mixture, and the binder is selected from the group consisting of organic binders, inorganic binders, and aqueous binders.

[0058] Example 38 relates to a method according to the preceding example, wherein the binder comprises a sodium silicate solution (waterglass).

[0059] Example 39 relates to the method of any one of the preceding examples, wherein the binder is added in an amount between about 2% and about 10% by weight, or between about 5% and about 7% by weight.

[0060] Example 40 relates to the method of any one of the preceding examples, wherein preparing the agglomerates comprises granulation, compression, extrusion, pelletizing, and / or briquetting.

[0061] Example 41 relates to the method of any one of the preceding examples, further comprising drying the agglomerates to improve green strength before heat treating the agglomerates.

[0062] Example 42 relates to the method of any one of the preceding examples, wherein drying comprises evaporating or hardening the binder.

[0063] Example 43 relates to the method of any one of the preceding examples, wherein the aggregates are heat treated at a temperature of at least about 950° C., or at least about 1000° C., and / or up to about 1200° C.

[0064] Example 44 relates to the method of any one of the preceding examples, wherein the aggregates are heat treated for a duration of at least about 20 minutes, at least about 40 minutes, at least about 60 minutes, and / or up to about 120 minutes.

[0065] Example 45 relates to the method of any one of the preceding examples, wherein the aggregates are heat treated until CaCO, CaO, and / or SiO crystals are no longer detectable by X-ray diffraction.

[0066] Example 46 relates to the method of any one of the preceding examples, wherein the heat treatment comprises furnace heating or microwave heating.

[0067] Example 47 relates to a method according to the preceding example, wherein the aggregates are embedded in a susceptor material prior to performing microwave heating.

[0068] Example 48 relates to the method of any one of the preceding examples, wherein the glass matrix comprises one or more silicates and / or oxides.

[0069] Example 49 relates to the method of any one of the preceding examples, wherein the glass matrix comprises a Ca—Si—O compound selected from the group consisting of CaSiO and CaSiO (2CaO SiO).

[0070] Example 50 relates to a method according to any one of the preceding examples, wherein the glass matrix is ​​partially fluorinated.

[0071] Example 51 relates to the method of any one of the preceding examples, wherein the glass matrix comprises free CaO at a concentration of less than about 1 wt.%.

[0072] Example 52 relates to a method according to any one of the preceding examples, wherein the CaF2 crystals have a linear size ranging from about 500 nm to about 500 microns.

[0073] Example 53 relates to a method according to the preceding example, wherein the linear size is in the range of about 1 micron to about 150 microns.

[0074] Example 54 relates to the method of any one of the preceding examples, wherein the CaF2 crystals have a multimodal size distribution.

[0075] Example 55 relates to the method of any one of the preceding examples, wherein each fluorite synthetic stone further comprises SiO2 crystals dispersed in the glass matrix.

[0076] Example 56 relates to the method of any one of the preceding examples, wherein each fluorite synthetic stone further comprises Al2O3 crystals and / or MgO crystals dispersed in the glass matrix.

[0077] Example 57 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone comprises C at a concentration of less than about 1 wt.% and / or is free of C.

[0078] Example 58 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone comprises CaC0 at a concentration of less than about 2 wt.% and / or does not comprise CaC0.

[0079] Example 59 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone contains S at a concentration of less than about 0.1 wt.% and / or is free of S.

[0080] Example 60 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone contains P at a concentration of less than about 0.1 wt.% and / or is free of P.

[0081] Example 61 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone does not include a binder.

[0082]

[0033] In an embodiment 62, the fluorite synthetic stone has a buoyancy of about 2.2 g / cm3 as determined by the Archimedes principle buoyancy test. 3 ~About 3g / cm 3The method of any one of the preceding aspects, wherein the densities are in the range of

[0083] Example 63 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone loses less than or equal to about 7% by weight of mass after the fluorite synthetic stone is subjected to a 60 minute rotating drum test.

[0084] Example 64 relates to a method as in any one of the preceding examples, wherein the fluorite synthetic stone maintains an average compressive force of at least about 1330 N before failure.

[0085] Example 65 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone exhibits water absorption of about 0.1% by weight or less after 6 days in a humidity chamber (greater than 90% relative humidity).

[0086] Example 66 relates to the method of any one of the preceding examples, wherein the fluorite synthetic stone has a nominal size ranging from a few millimeters to a few centimeters.

[0087] Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible without departing from the present invention. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein. All embodiments that fall within the meaning of the claims are intended to be embraced therein, either literally or by equivalence.

[0088] Moreover, the advantages described above are not necessarily the only advantages of the present invention, and it is not necessarily expected that all of the described advantages will be achieved in every embodiment of the present invention.

Claims

1. A fluorite-type synthetic stone, A glass matrix containing Ca, Si, and O and having a predetermined weight ratio of Ca to Si; and CaF dispersed in the glass matrix at a concentration of at least about 70% by weight. ２ A fluorite synthetic stone that contains crystals.

2. 2. The fluorite synthetic stone of claim 1, wherein the predetermined weight ratio of Ca to Si is greater than 1 and / or the predetermined weight ratio of Ca to Si is from about 2:1 to about 4:

1.

3. 2. The fluorite synthetic stone according to claim 1, wherein the predetermined weight ratio of Ca to Si is less than 1.

4. 2. The fluorite synthetic stone of claim 1, wherein the concentration is at least about 80% by weight, at least about 90% by weight, at least about 92% by weight, or at least about 94% by weight, and / or as high as about 96% by weight.

5. 2. The fluorite synthetic stone of claim 1, wherein the glass matrix comprises one or more silicates and / or oxides.

6. The glass matrix is ​​Ca ２ SiO ３ and Ca ２ SiO ４ (2CaO.SiO ２ 6. The fluorite synthetic stone according to claim 5, comprising a Ca-Si-O compound selected from the group consisting of:

7. 2. The fluorite synthetic stone of claim 1, wherein the glass matrix is ​​partially fluorinated.

8. 2. The fluorite synthetic stone of claim 1, comprising free CaO at a concentration of less than about 1% by weight.

9. The CaF ２ 2. The fluorite synthetic stone of claim 1, wherein the crystals have a linear size ranging from about 500 nm to about 500 microns.

10. 10. The fluorite synthetic stone of claim 9, wherein said linear size ranges from about 1 micron to about 150 microns.

11. The CaF ２ 2. The fluorite synthetic stone of claim 1, wherein the crystals have a multimodal size distribution.

12. SiO dispersed in the glass matrix ２ The fluorite synthetic stone of claim 1 further comprising crystals.

13. Al dispersed in the glass matrix ２ O ３ The fluorite synthetic stone according to claim 1, further comprising MgO crystals and / or MgO crystals.

14. 2. The fluorite synthetic stone of claim 1, containing C at a concentration of less than about 1 wt. % and / or being C-free.

15. CaCO at a concentration of less than about 2% by weight ３ and / or CaCO ３ The fluorite synthetic stone according to claim 1, which does not contain

16. 2. The fluorite synthetic stone of claim 1, containing S at a concentration of less than about 0.1 wt.% and / or being S-free.

17. 2. The fluorite synthetic stone of claim 1, containing P at a concentration of less than about 0.1 wt.% and / or being P-free.

18. 2. The fluorite synthetic stone of claim 1, which does not contain a binder.

19. Approximately 2.2 g / cm, as determined by the Archimedes principle buoyancy test ３ ~Approx. 3g / cm ３ 2. The fluorite synthetic stone of claim 1 having a density in the range of

20. 10. The fluorite synthetic stone of claim 1, having high resistance to abrasion, wherein the fluorite synthetic stone sample loses no more than about 7% by weight of mass after being subjected to a 60 minute rotating drum test.

21. 10. The fluorite synthetic stone of claim 1, which maintains an average compressive force of at least about 1330 N before failure.

22. 10. The fluorite synthetic stone of claim 1, exhibiting water absorption of about 0.1% by weight or less after six days in a humidity chamber (relative humidity greater than 90%).

23. 2. The fluorite synthetic stone of claim 1, having a nominal size ranging from a few millimeters to a few centimeters.

24. 2. A method of using the fluorite synthetic stone of claim 1, said method comprising: adding a plurality of said fluorite type synthetic minerals to a steelmaking furnace containing slag and molten steel.

25. 25. The method of claim 24, wherein the addition of the fluorite synthetic stone reduces the viscosity of the slag.

26. 25. The method of claim 24, wherein the addition of the fluorite synthetic increases the ability of the slag to remove sulfur from the molten steel.

27. 1. A method for making a fluorite-type synthetic stone, the method comprising: A particulate mixture comprising: CaF at a concentration of at least about 70% by weight ２ and a filler having a predetermined weight ratio of Ca and Si; preparing an aggregate from the particulate mixture; and heat treating the aggregate to form a plurality of fluorite-type synthetic stones, each fluorite-type synthetic stone comprising a glass matrix comprising Ca, Si, and O and a CaF crystal dispersed in the glass matrix at a concentration of at least about 70% by weight. ２ and heat treating.

28. Blending the particulate mixture 28. The method of claim 27, comprising obtaining particulate material from a mining operation, determining a chemical content of the particulate material, and combining selected fractions of the particulate material to form the particulate mixture.

29. 30. The method of claim 28, wherein determining the chemical content of the particulate material comprises determining a Ca, F, and Si content.

30. Determining the chemical content of the particulate material comprises: ２ , SiO ２ , CaO, and / or CaCO ３ 30. The method of claim 29, further comprising estimating the amount of.

31. 30. The method of claim 28, wherein determining the chemical content of the particulate material comprises performing an X-ray fluorescence analysis on the particulate material.

32. 30. The method of claim 27, further comprising adding one or more additional particulate ingredients to the particulate mixture after blending the particulate mixture.

33. The one or more additional particulate materials are ２ O ３ and MgO.

34. 28. The method of claim 27, wherein the predetermined weight ratio is greater than 1.

35. 35. The method of claim 34, wherein the predetermined weight ratio is from about 2:1 to about 4:

1.

36. 28. The method of claim 27, wherein the predetermined weight ratio is less than 1.

37. 28. The method of claim 27, wherein preparing the aggregate comprises mixing a binder with the particulate mixture, the binder being selected from the group consisting of organic binders, inorganic binders, and aqueous binders.

38. 38. The method of claim 37, wherein the binder comprises a sodium silicate solution (waterglass).

39. 38. The method of claim 37, wherein the binder is added in an amount of about 2% to about 10% by weight, or about 5% to about 7% by weight.

40. 28. The method of claim 27, wherein preparing the agglomerates comprises granulating, compressing, extruding, pelletizing, and / or briquetting.

41. 30. The method of claim 27, further comprising drying the agglomerates to improve green strength prior to heat treating the agglomerates.

42. 42. The method of claim 41, wherein the drying comprises evaporating or hardening the binder.

43. 28. The method of claim 27, wherein the aggregates are heat treated at a temperature of at least about 950°C, or at least about 1000°C, and / or up to about 1200°C.

44. 28. The method of claim 27, wherein the aggregates are heat treated for a duration of at least about 20 minutes, at least about 40 minutes, at least about 60 minutes, and / or up to about 120 minutes.

45. The aggregate is CaCO ３ , CaO, and / or SiO ２ 28. The method of claim 27, wherein the crystals are heat treated until they are no longer detectable by X-ray diffraction.

46. 28. The method of claim 27, wherein the heat treatment comprises furnace heating or microwave heating.

47. 47. The method of claim 46, wherein the agglomerates are embedded in a susceptor material prior to performing the microwave heating.

48. 28. The method of claim 27, wherein the glass matrix comprises one or more silicates and / or oxides.

49. The glass matrix is ​​Ca ２ SiO ３ and Ca ２ SiO ４ (2CaO.SiO ２ 28. The method of claim 27, comprising a Ca-Si-O compound selected from the group consisting of:

50. 28. The method of claim 27, wherein the glass matrix is ​​partially fluorinated.

51. 28. The method of claim 27, wherein the glass matrix contains free CaO at a concentration of less than about 1 wt.%.

52. The CaF ２ 28. The method of claim 27, wherein the crystals have a linear size ranging from about 500 nm to about 500 microns.

53. 53. The method of claim 52, wherein the linear size is in the range of about 1 micron to about 150 microns.

54. The CaF ２ 28. The method of claim 27, wherein the crystals have a multimodal size distribution.

55. Each fluorite type synthetic stone is made of SiO dispersed in the glass matrix. ２ 28. The method of claim 27 further comprising a crystal.

56. Each fluorite-type synthetic stone is made of Al dispersed in the glass matrix. ２ O ３ 28. The method of claim 27, further comprising:

57. 28. The method of claim 27, wherein the fluorite synthetic stone contains C at a concentration of less than about 1 wt.% and / or is C-free.

58. The fluorite synthetic stone has a concentration of less than about 2% by weight of CaCO ３ and / or CaCO ３ 28. The method of claim 27, wherein the method does not include

59. 28. The method of claim 27, wherein the fluorite synthetic stone contains S at a concentration of less than about 0.1 wt.% and / or is S-free.

60. 28. The method of claim 27, wherein the fluorite synthetic stone contains P at a concentration of less than about 0.1 wt.% and / or is P-free.

61. 28. The method of claim 27, wherein the fluorite synthetic stone is binder-free.

62. The fluorite synthetic stone has a buoyancy of about 2.2 g / cm as determined by the Archimedes principle buoyancy test. ３ ~Approx. 3g / cm ３ 28. The method of claim 27, having a density in the range of

63. 28. The method of claim 27, wherein the fluorite synthetic stone loses no more than about 7% by weight of mass after the fluorite synthetic stone is subjected to a 60 minute rotating drum test.

64. 28. The method of claim 27, wherein the fluorite synthetic stone maintains an average compressive force of at least about 1330 N before failure.

65. 28. The method of claim 27, wherein the fluorite synthetic stone exhibits water absorption of about 0.1% by weight or less after 6 days in a humidity chamber (greater than 90% relative humidity).

66. 28. The method of claim 27, wherein the fluorite synthetic stone has a nominal size ranging from a few millimeters to a few centimeters.

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