High-quality coke product

Abstract

To provide a high-quality coke product manufactured from an optimized blend of coal by using a horizontal-type furnace such as a heat recovery furnace, a non-recovery furnace, and a Thomson furnace.SOLUTION: There is provided a coke product, having a unique property such as an oblong shape, an improved Coke Strength after Reaction (CSR), and an improved Coke Reactivity Index (CRI).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to high quality coke products with unique properties produced in furnaces, including heat recovery furnaces, non-recovery furnaces, and horizontal furnaces such as Thompson furnaces. [Background technology]

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 019,405, filed May 3, 2020, which is incorporated by reference in its entirety.

[0003] Coke is a solid carbon fuel and carbon source used to melt and reduce iron ore in the production of steel. Foundry coke is a coke with very large dimensions (usually 4 inches or more in diameter) and very low impurity content, as well as exceptional qualities such as very high carbon content, very high strength, and very high stability. Foundry coke is used to melt iron in foundry cupolas to produce cast iron and ductile iron products. Summary of the Invention [Problem to be solved by the invention]

[0004] However, the production costs of foundry coke (including production costs, transportation costs, and environmental costs) are high. Thus, there is a need in the art for improved production processes, thereby obtaining high quality foundry coke with higher yields and / or at lower costs. The present invention fills this need by providing a high quality foundry coke that has many unique and improved properties. [Brief explanation of the drawings]

[0005] [Figure 1]Figure 1 compares the shape, size, and color of HD+™ foundry coke produced with 10% coke breeze by weight to commercially available foundry cokes. Commercial Foundry Coke 1 is produced in the United States at a conventional by-products plant and is shown on an 8.5" x 11" sheet of paper. Commercial Foundry Coke 2 has a very high density and is produced in a foreign country at a stamp-charge by-products plant and is shown on an 8.5" x 11" sheet of paper. [Figure 2] FIG. 1 compares the CSR and CRI of HD+™ foundry coke obtained with a 5 wt. % coke breeze loading (diamonds) and an 8.5 wt. % coke breeze loading (circles) with the CSR and CRI of conventional foundry coke (Met Coke) (squares) obtained from the literature (Diez et al., International Journal of Coal Geology 50: 389-412 (2002)). [Figure 3A] FIG. 1 shows simulated results of a packing test on coke pieces of uniform size (10 inches by 10 inches). [Figure 3B] FIG. 1 shows simulated results of a packing test on coke pieces of uniform size (4 inches by 10 inches). [Figure 3C] FIG. 10 shows simulated results of a packing test for randomly sized coke pieces. [Figure 4] FIG. 10 illustrates the variability from repeated runs resulting from the stochastic nature of the cupola charging test simulation. [Figure 5] FIG. 10 illustrates an example of a hydraulic radius calculation and an example of the resulting user output. DETAILED DESCRIPTION OF THE INVENTION

[0006] This application contains at least one color drawing. Copies of this application containing color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0007] Disclosed herein are high-quality HD+™ coke products, particularly HD+™ foundry coke, which possess unique properties. The coking process produces coke of various sizes and in various fractions. Traditionally, coke products have a substantially spherical shape and are classified based on size as follows: foundry coke, which has a size greater than 4 inches in diameter; egg (industrial coke), which has a size between 2 and 4 inches; stove, which has a size between 1 and 2 inches or 1 and 1.5 inches; nut, which has a size between 3 / 8 and 1 inch; and breeze, which has a size less than 3 / 8 inch. In an embodiment of the present disclosure, the HD+™ coke products disclosed herein are produced by a proprietary coking process using a predetermined coal blend containing specific proportions of inerts or coke breeze in a horizontal furnace, such as a heat recovery furnace, a non-recovery furnace, or a Thompson furnace. HD+™ coke products can be classified in various ways. In one example, HD+™ coke products include HD+™ foundry coke with a hydraulic diameter greater than 3.5 inches, HD+™ egg coke with a hydraulic diameter of 1.5 to 3.5 inches, HD+™ coke breeze with a hydraulic diameter of 0.5 to 1.5 inches, and HD+™ waste fines with a size less than 0.5 inches. While all of the HD+™ coke breeze can be crushed to 3 / 8 inch or smaller and recycled into blended coal for the coking process, the waste fines can pose heat recovery issues due to potential combustion losses and high ash content. Therefore, depending on the coking process, some or all of the waste fines are recycled. HD+™ egg coke is recycled only when additional coke breeze loading is required, but most often, HD+™ egg coke is sold and used in sugar beet production and mineral or rock wool production.

[0008] In certain embodiments, the present specification discloses HD+™ cokes having a shape distinguishable from commercially available foundry cokes (which have a substantially spherical shape and a diameter of at least 4 inches). Unlike conventional spherical black foundry cokes, the HD+™ foundry cokes disclosed herein have an elongated "finger shape" as shown in Figure 1. In certain embodiments, the HD+™ cokes disclosed herein have a gray or light gray color.

[0009] In certain embodiments, the HD+™ foundry coke has a high aspect ratio (ratio of length to width). For example, the HD+™ foundry coke has a length between 2 inches and 36 inches, between 3 inches and 15 inches, between 4 inches and 12 inches, or between 4 inches and 10 inches, and a width between 1.5 inches and 12 inches, between 2 inches and 8 inches, between 3 inches and 7 inches, between 2 inches and 4 inches, or between 4 inches and 6 inches. In some embodiments, the HD+™ foundry coke may have a length of at least 2 inches, at least 3 inches, at least 4 inches, at least 5 inches, at least 6 inches, at least 7 inches, at least 8 inches, at least 9 inches, at least 10 inches, at least 11 inches, at least 12 inches, at least 13 inches, at least 14 inches, at least 15 inches, at least 16 inches, at least 17 inches, at least 18 inches, at least 19 inches, at least 20 inches, at least 21 inches, at least 22 inches, at least 23 inches, at least 24 inches, at least 25 inches, at least 26 inches, at least 27 inches, at least 28 inches, at least 29 inches, at least 30 inches, at least 31 inches, at least 32 inches, at least 33 inches, at least 34 inches, at least 35 inches, or at least 36 inches. In some embodiments, the HD+™ foundry coke has a width of at least 1.5 inches, at least 2 inches, at least 3 inches, at least 4 inches, at least 5 inches, at least 6 inches, at least 7 inches, at least 8 inches, at least 9 inches, at least 10 inches, at least 11 inches, at least 12 inches, at least 13 inches, at least 14 inches, at least 15 inches, at least 16 inches, at least 17 inches, or at least 18 inches.In certain embodiments, the HD+™ foundry coke has a length:width ratio of at least 1.1, at least 1.5, at least 2.0, at least 2.5, at least 3.0, at least 3.5, at least 4.0, at least 4.5, at least 5.0, at least 5.5, at least 6.0, at least 6.5, at least 7.0, at least 7.5, at least 8.0, at least 8.5, at least 9.0, at least 9.5, or at least 10.0. In some embodiments, the HD+™ foundry coke has a length:width ratio of at least 2.0, at least 3.0, or at least 4.0.

[0010] In certain embodiments, HD+™ foundry coke is produced by a proprietary process in a horizontal furnace, such as a heat recovery furnace, a non-recovery furnace, or a Thompson furnace. In certain embodiments, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% of the total amount of coke from a single production run or a single furnace falls within the length, width, and length:width ratio ranges set forth above. In certain embodiments, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% of all foundry coke from a single production run or a single furnace falls within the above length, width, and length:width ratio ranges.

[0011] In certain embodiments, HD+™ foundry coke has a hydraulic diameter (Dh) that is greater than its actual or effective diameter, whereas conventional round foundry coke has a Dh that is substantially the same as its actual diameter. Dh is a function of hydraulic radius (Rh), defined by the following equation:

[0012]

number

[0013] where εb is the interparticle void fraction of the coke bed, calculated by the following formula:

[0014]

number

[0015] where ρb is the bulk density of the coke, ρa is the apparent density of the coke, and Dp is the harmonic mean particle size. Dp represents the size of a homogeneous coke with the same surface area:volume ratio as a heterogeneous coke, and is calculated by the following formula:

[0016]

number

[0017] where fi is the weight fraction of coke with diameter Di. For uniformly sized coke, Dp = Di.

[0018] In certain embodiments, the HD+™ foundry coke has a hydraulic diameter of at least 2 inches, at least 2.5 inches, at least 3 inches, at least 3.5 inches, at least 4 inches, at least 4.5 inches, at least 5 inches, at least 5.5 inches, at least 6 inches, at least 6.5 inches, at least 7 inches, at least 7.5 inches, at least 8 inches, at least 8.5 inches, at least 9 inches, at least 9.5 inches, at least 10 inches, at least 10.5 inches, at least 11 inches, at least 11.5 inches, at least 12 inches, at least 12.5 inches, at least 13 inches, at least 13.5 inches, at least 14 inches, at least 14.5 inches, at least 15 inches, at least 15.5 inches, at least 16 inches, at least 16.5 inches, at least 17 inches, at least 17.5 inches, or at least 18 inches. In certain embodiments, the HD+™ Egg has a hydraulic diameter between 1.5 inches and 3.5 inches, or between 1.5 inches and 2 inches.

[0019] The coke reactivity index (CRI) is calculated by the Boudouard reaction (CO2 + C) in a heated kiln over a period of 2 hours. (コークス) The CRI indicates the percentage of weight loss after the CRI (=2CO). The post-reaction coke strength (CSR) is based on a tumble strength test of the coke remaining after the CRI kiln reaction. The Boudoir reaction, which occurs on the surface of foundry coke in the cupola, is undesirable because it removes heat from the iron melt and reduces the efficiency of the process. Therefore, a lower CRI is desirable to ensure the coke is sufficiently inert to prevent the Boudoir reaction. On the other hand, the CRI should not be so low that it renders the coke inert and prevents combustion. As shown in Figure 2, CSR and CRI are inversely related. Conventional foundry cokes have a CSR of 10% to 15%, which correlates with a high CRI of 60% or more.

[0020] Unless otherwise specified, all percentages described herein are by weight. In certain embodiments, the HD+™ foundry coke disclosed herein has a CSR ranging between 5% and 60%, between 5% and 50%, between 15% and 50%, or between 15% and 40%. In certain embodiments, the HD+™ coke has a CRI of less than 40%, between 20% and 45%, between 25% and 40%, or between 31% and 37%. The percentage of coke breeze loading during the coking process affects the CSR of the HD+™ coke, with higher coke breeze loading resulting in lower CSR, as shown in Figure 2. According to aspects of the present disclosure, the CRI remains low even when the CSR increases significantly. According to one embodiment of the present disclosure, the HD+™ coke disclosed herein has a combination of a low CRI, such as between 25% and 40%, and a mid-to-high CSR, such as between 15% and 50%.

[0021] In certain embodiments, the HD+™ egg coke has the same or substantially the same CSR as the HD+™ foundry coke described above. In certain embodiments, the HD+™ egg coke has the same or substantially the same CRI as the HD+™ foundry coke described above.

[0022] After production from the oven and before shipping and delivery to customers, HD+™ foundry coke undergoes quality control and screening. As used herein, the term "pre-processed" coke product means the coke product is fresh from the oven and prior to screening, shipping, and delivery to customers, and the term "processed" coke product means the coke product has undergone screening, shipping, and delivery to customers. In certain embodiments, when using starting material having a dimension of at least 4 inches in an industry-standard drop crush test, the pre-treated HD+™ foundry coke has a 4-inch drop crushability of at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90%. In certain embodiments, when starting material having a dimension of at least 4 inches is used in an industry-standard drop crush test, the pretreated HD+™ foundry coke has a 2-inch drop crushability of at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%. In certain embodiments, when starting material having a dimension of at least 4 inches is used in an industry-standard drop crush test, the treated HD+™ foundry coke has a 4-inch drop crushability of at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or at least 90%. In certain embodiments, the treated HD+™ foundry coke has a 2-inch drop crushability of at least 80%, at least 85%, at least 90%, or at least 95% when using starting material having a dimension of at least 4 inches in the industry standard drop crush test.

[0023] In certain embodiments, HD+™ foundry coke has the following customization criteria: Ash content between 5% and 12%, less than 10%, less than 9.5%, less than 9%, less than 8%, less than 7.5%, or less than 7%; sulfur content less than 1%, less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, or less than 0.5%; Volatile matter (VM) content of less than 2%, less than 1%, between 0.4% and 1%, about 0.5%, or about 0.3%; a moisture content of less than 15%, less than 10%, less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or between 1% and 10%; and At least 80%, at least 85%, at least 90% or at least 95% fixed carbon.

[0024] In certain embodiments, the total coke produced by the unique process has a size distribution as follows: HD+™ foundry coke is at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80%; medium size coke, including HD+™ egg coke and HD+™ coke breeze, is between 5% and 35%, between 10% and 30%, or between 15% and 20%, and waste fines is less than 10%, less than 8%, or less than 5%. Preferably, the fraction of HD+™ foundry coke is as high a percentage of the total coke produced as possible.

[0025] Due to its unique size and shape, the HD+™ coke disclosed herein has the advantage of achieving a desirable packing density as demonstrated in the examples below. [Example]

[0026] (Example 1: Filling test) This example shows the simulation of a cupola packing using a simplified 2D random packing model. Compared to uniformly sized coke, coke with a broad particle size distribution is expected to have a higher bulk density, a larger surface area, and lower bed porosity when charged into the furnace.

[0027] Figure 3A shows a two-dimensional simulated packing test of coke with uniform dimensions of 10 inches by 10 inches. The circle represents the cross section of the cupola with a radius of 60 inches. Each square represents a foundry coke piece, a cube with a side length of 10 inches. Coke pieces were added sequentially at random locations and with random rotations. If a new coke piece did not overlap any of the previous pieces, it was placed; otherwise, it was discarded. Overlap was determined by the intersection of the coke ends. In this simulation, 10,000 coke pieces were tried, and only 61 fit.

[0028] The overall assumptions of this model are: (1) the next layer of coke pieces will lie on top of this layer; (2) any coke pieces outside the circle are ignored as minor errors; (3) this cross section is essentially equivalent to the other cross sections of the cupola; (4) the relative density of the coke packing is proportional to the ratio of the sum of the square areas to the total area of ​​the circle; and (5) although not strictly accurate, the relative surface area is approximately proportional to the sum of the perimeters of the coke pieces.

[0029] In a side-by-side comparison of fittings for 10" x 10" coke pieces (shown in Figure 3A) and 4" x 10" coke pieces (shown in Figure 3B), the ratio of coverage area to total perimeter of the coke pieces is compared. For the 10" x 10" pieces, 58 coke pieces were placed, resulting in 51% coverage of the 11,309 square inch cupola area ([10 x 10 x 58] / 11309 = 51%) and a total perimeter of 2,320 inches (2 x [10 + 10] x 58 = 2320). For the 4-inch by 10-inch coke pieces, 58 coke pieces were placed, resulting in 49% coverage of the cupola area of ​​11,309 square inches ([4 x 10 x 138] / 11309 = 49%) and a total perimeter of 3,864 inches (2 x [4 + 10] x 138 = 3864).

[0030] The next improvement in the simulation is (1) The coke pieces are allowed to vary in length and width between user-defined maximum and minimum values, with each piece having a square edge (i.e., L x W x W); and (2) Tilt the coke piece so that the smaller "corner" of the piece can fit into the allowed space. If the full range of tilt was allowed, the simulation would have preferred that the coke pieces stand on the small end, so the maximum tilt angle was arbitrarily limited to 30 degrees.

[0031] Based on this assumption, coke pieces of various dimensions were fitted into a 60-inch radius cupola, as shown in Figure 3C. The coke pieces ranged in length from 4 inches to 10 inches and in width from 3 inches to 5 inches, and 10,000 fitting attempts were performed. For the various size pieces, 209 coke pieces were placed, resulting in 47% coverage of the 11,309 square inch cupola area (5,365 / 11,309 = 47%) and a total perimeter of 4,383 inches. Thus, while the relative surface area increases significantly compared to the packing simulations in Figures 3A-3C, the packing tests demonstrate that the coke loading density does not change significantly. The results are summarized in Table 1 below.

[0032] [Table 1]

[0033] Figure 4 shows the variability across repeated runs due to the stochastic nature of the simulation.

[0034] (Example 2: Calculating hydraulic radius) A model in Excel was used to calculate the hydraulic radius of the foundry coke based on the measured size distribution, bottom screen cut estimates, and bulk density using the formula previously described.

[0035] The elongated shape of the coke of the present invention can result in a sparse packing density and therefore an increased effective hydraulic radius. This can improve foundry cupola performance by reducing latent heat losses in the reactions that form CO and CO from the coke at the coke surface. Increasing the ratio of void volume to coke surface area assists in this factor.

[0036] Trimming small coke pieces can also improve the hydraulic radius, but at the expense of yield. An elongated coke shape may prove to offer significant advantages in cupola performance.

[0037] The bulk density of the sorted coke as well as the bulk density of the unsorted coke can be measured in the same way and used in the calculations. The calculation results are shown in Figure 5.

[0038] From the foregoing, it will be understood that, although specific embodiments of the present technology have been described herein for illustrative purposes, various modifications may be made without departing from the spirit and scope of the present technology. Furthermore, certain aspects of the new technology described in the context of particular embodiments may be combined with or excluded from other embodiments. Furthermore, while advantages associated with particular embodiments of the present technology have been described in the context of those embodiments, other embodiments may also exhibit those advantages, although not all embodiments necessarily exhibit those advantages for the embodiments to fall within the scope of the present technology. Accordingly, the present disclosure and related technology may encompass other embodiments not expressly shown or described herein. Accordingly, the present disclosure is not limited except as by the appended claims.

Claims

[Claim 1] 1. A foundry coke having a hydraulic diameter (Dh) greater than the actual diameter of the foundry coke, characterized in that the foundry coke has a reactivity index (CRI) between 20% and 45%, a coke strength after reaction (CSR) between 15% and 40%, and a sulfur content of less than 1%.

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