Draining sand containing an oxidizing agent and a method for its production

Abstract

The application provides a kind of oxidant-containing drainage sand and its preparation method, and belongs to the technical field of self-consumption interception device.A kind of oxidant-containing drainage sand is made of the following weight parts of raw materials: chrome ore sand 30-95 parts, quartz sand 0-65 parts, fused magnesite 0-65 parts, limestone 1-4 parts, carbonaceous material 1-2 parts, oxidant 1-3 parts;Among them, the total weight parts of the chrome ore sand, quartz sand, fused magnesite, limestone, carbonaceous material and oxidant are 100 parts.The application utilizes the closed environment in the nozzle after the ladle slide is closed, and under high temperature conditions, makes the drainage sand undergo redox reaction, produces a series of phase change expansion, generates low-strength sintered block that is easy to break, and makes the molten steel more easily break through the sintered layer under the same static pressure when pouring, to realize automatic pouring.

Description

Technical Field

[0001] The invention belongs to the technical field of self-consumable interception devices, and particularly relates to drainage sand containing an oxidant and a preparation method thereof. Background Art

[0002] After the smelting of molten steel is completed, in order to ensure the quality of the molten steel, the molten steel should be automatically flowed out of the ladle as much as possible and enter the tundish for casting through the protective sleeve, which is the so-called automatic ladle pouring, to avoid secondary oxidation caused by contact with air; if the molten steel does not flow out automatically, artificial oxygen burning is required to assist drainage, which will cause excessive oxidation of the molten steel and will seriously affect the quality of the steel.

[0003] The principle behind automatic ladle pouring is to fill the nozzle with high-quality drainage sand, creating a sintered layer of sufficient thickness and strength under high-temperature heat load conditions. This sintered layer must be formed during the initial tapping phase to prevent the molten steel from dislodging the drainage sand and preventing the molten steel from penetrating the nozzle. However, the sintered layer should be kept within a certain thickness and strength. During pouring, the static pressure of the molten steel is used to break through the sintered layer, allowing the molten steel to flow out automatically. Because the ladle capacity is essentially fixed, the static pressure of the molten steel is also essentially fixed.

[0004] Practice has proven that the compressive strength of drainage sand sinter plays a decisive role in the automatic pouring rate of the ladle, and is proportional to the heat load time and temperature: when a large amount of heat is transferred to the drainage sand, the low-melting-point mineral phase first precipitates in the liquid phase, and the drainage sand material particles adhere to each other and form a mass. As the heat load time increases and the temperature rises, the amount of liquid phase precipitation increases, exacerbating the adhesion of the drainage sand material particles, and ultimately forming a block with high flexural strength, which blocks the nozzle and affects the automatic pouring rate. The current measures adopted in the industry to improve the automatic pouring rate of the ladle include: optimizing ladle scheduling, and while ensuring the requirements of steel smelting, minimizing the heat load time or controlling the temperature of the molten steel treatment process to avoid excessive heat transfer that causes severe sintering of the drainage sand in the nozzle; on the other hand, optimizing the raw material combination and composition of the drainage sand product to reduce the flexural strength of the drainage sand sinter. For example, measures such as selecting materials with high refractoriness and adding raw materials with low thermal conductivity into drainage sand to form a heat-resistant layer to prevent heat transfer are used to prevent over-sintering, which has achieved certain improvement effects in improving the self-opening rate of the ladle.

[0005] To prevent the molten steel from floating the drainage sand and penetrating into the nozzle, a certain amount of raw materials that promote the formation of a sintered layer must be added. However, when the steel smelting process is complex, the heat load time is prolonged, and the temperature rises, these raw materials are the main cause of excessive sintering of the drainage sand. This problem has become an irreconcilable contradiction.

[0006] Therefore, the problem of ladle failure due to excessive sintering strength of drainage sand is still common. In order to achieve better ladle automatic pouring effect, providing diversified and feasible technical solutions is still the key research work in this field. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a drainage sand containing an oxidant in response to the shortcomings of the existing technology. The drainage sand undergoes an oxidation-reduction reaction under high temperature conditions by utilizing the closed environment inside the water inlet after the ladle slide is closed, resulting in a series of phase change expansions and the formation of fragile low-strength sintered blocks. When pouring, the molten steel can more easily break through the sintered layer under the same static pressure, thereby realizing automatic pouring.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A drainage sand containing an oxidant is prepared from the following raw materials in parts by weight: 30-95 parts of chromium ore sand, 0-65 parts of quartz sand, 0-65 parts of fused magnesia sand, 1-4 parts of limestone, 1-2 parts of carbonaceous material, and 1-3 parts of an oxidant;

[0010] The total weight of the chromium ore, quartz sand, fused magnesia, limestone, carbonaceous material and oxidant is 100 parts.

[0011] Preferably, the chromium ore contains Cr2O3 in a weight percentage of ≥45%, Fe2O3 in a weight percentage of ≥27%, and Fe 2 + 、Fe 3+ All are measured in terms of Fe2O3, with a weight percentage of Al2O3 ≤ 16%, and a particle size of 0.15mm-0.8mm.

[0012] Preferably, the quartz sand contains SiO2 at a weight percentage of ≥93% and a particle size of 0.3 mm to 1.2 mm.

[0013] Preferably, the fused magnesia contains MgO in an amount of ≥95% by weight and has a particle size of 0.3 mm to 1.2 mm.

[0014] Preferably, the limestone contains CaO at a weight percentage of ≥50%, a loss on ignition of ≥40%, and a particle size of 0.3 mm to 1.2 mm.

[0015] Preferably, the carbonaceous material contains C 固 ≥95%, particle size ≤0.15mm.

[0016] Preferably, the oxidant is potassium permanganate, containing KMnO4 in a weight percentage of ≥90% and a particle size of ≤0.15 mm.

[0017] Preferably, the oxygen-containing agent-containing drainage sand has the following mass percentages of effective components: Cr2O3: 13.5%-43.0%, SiO2: 0%-61.0%, MgO: 0%-62.0%, Fe2O3: 8.0%-26.0%, Al2O3: 0%-14.3%, CaO: 0.5%-2.0%, KMnO4: 0.9%-3.0%, C 固 : 0.95%-2.0%, loss on ignition: 0.4%-1.6%, and the rest is inevitable impurities.

[0018] Preferably, the preparation method of the above-mentioned oxygen-containing agent-containing drainage sand comprises the following steps:

[0019] Step S1: After accurately measuring the chromium ore sand, quartz sand, fused magnesia and limestone, they are put into a drum mixer and stirred for 5-15 minutes, and then discharged for standby;

[0020] Step S2: The semi-finished product material obtained by uniformly stirring in step S1 is subjected to a roller drying treatment, and then discharged for standby. The water content of the dried product is <0.1%;

[0021] Step S3: After accurately measuring the carbonaceous material and the oxidizing agent, they are stirred for 7-12 minutes, and then discharged to obtain a finished product;

[0022] Step S4: The obtained finished product is conveyed to a finished product warehouse for metering and packaging.

[0023] Preferably, the air supply temperature of the drying treatment is 200°C-450°C.

[0024] In the prior art drainage sand, Si 2+ , Mg 2 , Cr 2+ , Al 3+ and other plasma elements are generally contained, and [Fe] exists in the form of Fe 2+ and Fe 3+ ; during the thermal load, the water gap is in a closed vacuum-like state without contact with external air sources, and the chemical properties of each element are relatively stable. The main mineral phase conversion reaction between solid-liquid phases occurs between the materials, and with the extension of the thermal load time and the increase of the temperature, the sintered thickness of the drainage sand will be larger and the strength will be higher, which seriously affects the automatic pouring effect of the ladle.

[0025] In some previous research, the applicant has addressed the issue of ladle failure due to prolonged steel pressing times, which can result from the inability to automatically open the ladle. This technology (see patent publication number CN109133951A) utilizes the excellent thermal stability and extremely low thermal conductivity of expanded perlite. After uniformly mixing it with other materials, it forms a heat-resistant layer between the sand particles within the drainage agent. This layer forms a sintered layer in the contact area between the drainage agent and the molten steel within the nozzle. Due to the presence of this heat-resistant layer, the drainage sand in the middle and lower parts of the nozzle is not significantly increased in heat transfer, even during extended steel pressing times (approximately 8 hours). This effectively prevents sintering of the drainage sand in the middle and lower parts of the nozzle, ultimately resolving the issue of ladle failure due to prolonged steel pressing times. In practical applications, this technology has achieved certain improvements in the ladle's automatic opening rate. However, in smelting processes involving small ladles or long steel retention times, the conflict between the inherent properties of drainage sand and the ladle's spontaneous opening remains prevalent. While a single technology has its own advantages and disadvantages, no single solution can perfectly address all ladle spontaneous opening issues. By shifting our thinking and seeking more diverse and feasible solutions, we can better meet practical needs.

[0026] In the present research and experiments, the applicant found that the Fe content of [Fe] in chromite 2+ 、Fe 3+ There are two forms of existence, which can change with the ambient atmosphere at high temperature, that is, when the oxygen potential in the ambient atmosphere is high, Fe 2+ →Fe 3+ The oxidation reaction of Fe 3+ →Fe 2+ The series of redox reactions will cause a large volume expansion in the chromite particles, resulting in cracks and a significant decrease in the strength of the material particles. In the present invention, a small amount of oxidant is added to the drainage sand. Under the heat load condition, the oxidant releases oxygen to form Fe 2+ →Fe 3+ The ambient atmosphere of the oxidation reaction; as the thermal decomposition of the oxidant ends, the oxygen partial pressure in the closed water inlet channel drops sharply, forming Fe 3+ →Fe 2+ The reduction reaction atmosphere causes the strength of the chromite particles, the skeleton material in the drainage sand sintering layer, to drop significantly, thereby reducing the overall flexural strength of the sinter, making it easier to be crushed by the molten steel under the net pressure, and promoting a significant increase in the automatic pouring rate of the ladle.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) The present invention adds an oxidant to the drainage sand to promote the redox reaction of [Fe] under heat load and high temperature conditions, and uses volume expansion to cause cracks in the drainage sand particles, thereby significantly reducing the strength of the sintered material and promoting a significant increase in the automatic pouring rate of the ladle.

[0029] 2) There are cracks in the drainage sand particles. In addition, when the ladle is poured, there is a huge temperature difference between the high-temperature area in the nozzle and the outside temperature. The sintering is rapid and broken, and the pulverization is smaller than the drainage sand sinter in the existing technology. The particles are easily captured and adsorbed by auxiliary materials such as covering agents in the molten steel, which can significantly reduce the problem of molten steel inclusion caused by the drainage sand product and improve the purity of the molten steel.

[0030] 3) The appropriate amount of oxidant added to the drainage sand of the present invention is uniformly attached to the surface of the drainage sand particles along with the carbonaceous material. The reaction residues are low-melting-point potassium manganate and manganese oxide, the content of which is very low and has almost no effect on the refractoriness of the drainage sand. It can also promote mild sintering between the drainage sand and the molten steel particles in the initial contact period, avoid the problem of floating particles caused by the large difference in density between the drainage sand and the molten steel, and promote the functional effect of the drainage agent.

[0031] 4) The drainage sand of the present invention is also mixed with a certain proportion of limestone with a large loss on ignition, which decomposes at high temperature to release CO2 gas, thereby alleviating the consumption of limited oxygen in the nozzle by the carbonaceous material with specific functional effects in the drainage sand. The decomposition residue is porous solid particles, which can also reduce the overall flexural strength of the sintered material, thereby facilitating an increase in the automatic pouring rate of the ladle. DETAILED DESCRIPTION

[0032] In order to better understand the present invention, the content of the present invention is further clearly set forth below in conjunction with the examples, but the protection content of the present invention is not limited to the following examples. In the following description, a large number of specific details are provided in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0033] All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0034] Unless otherwise specified, all raw materials are derived from commercially available products and do not contain other unspecified components except inevitable impurities.

[0035] The present invention provides drainage sand containing an oxidant. The drainage sand is prepared from the following raw materials in parts by weight: 30-95 parts of chromium ore, 0-65 parts of quartz sand, 0-65 parts of fused magnesia, 1-4 parts of limestone, 1-2 parts of carbonaceous material, and 1-3 parts of oxidant; wherein the total weight of the chromium ore, quartz sand, fused magnesia, limestone, carbonaceous material, and oxidant is 100 parts.

[0036] For example, chromium ore can be added in an amount of 30, 35, 40, 45, 50, 55, 60, 70, 80, 90 or 95 parts by weight; quartz sand can be added in an amount of 1, 5, 10, 15, 20, 25, 30, 40, 50, 60 or 65 parts by weight; fused magnesia can be added in an amount of 1, 5, 10, 20, 25, 30, 35, 40, 50, 55, 60 or 65 parts by weight; limestone can be added in an amount of 1, 1.5, 2, 2.5, 3, 3.5 or 4 parts by weight; carbonaceous material can be added in an amount of 1, 1.2, 1.5, 1.7 or 2 parts by weight; and oxidant can be added in an amount of 1, 1.1, 1.3, 1.5, 2.0, 2.5 or 3 parts by weight, without limitation.

[0037] The weight percentage of Cr2O3 in chromium ore is ≥45%, the weight percentage of Fe2O3 is ≥27%, and the weight percentage of Fe 2+ 、Fe 3+ All are measured in terms of Fe2O3, with a weight percentage of Al2O3 ≤ 16%, and a particle size of 0.15mm-0.8mm.

[0038] The quartz sand can be any one or a combination of desert sand, sedimentary sand, and machine-made sand, wherein the weight percentage of SiO2 is ≥93% and the particle size is 0.3mm-1.2mm.

[0039] The weight percentage of MgO in fused magnesia is ≥95%, and the particle size is 0.3mm-1.2mm.

[0040] The weight percentage of CaO in the limestone is ≥50%, the loss on ignition is ≥40%, and the particle size is 0.3mm-1.2mm.

[0041] Carbonaceous materials can be graphite or carbon black, or a combination of the two. 固 ≥95%, particle size ≤0.15mm.

[0042] The oxidant may be potassium permanganate, containing KMnO4 in an amount of ≥90% by weight and a particle size of ≤0.15 mm.

[0043] The drainage sand containing oxidant has the following effective components in percentage by mass: Cr2O3: 13.5%-43.0%, SiO2: 0%-61.0%, MgO: 0%-62.0%, Fe2O3: 8.0%-26.0%, Al2O3: 0%-14.3%, CaO: 0.5%-2.0%, KMnO4: 0.9%-3.0%, C 固 : 0.95%-2.0%, loss on ignition: 0.4%-1.6%, and the rest are unavoidable impurities.

[0044] The preparation method of the above-mentioned drainage sand containing an oxidant includes the following steps: accurately measuring chromium ore sand, quartz sand, fused magnesia sand, and limestone, putting them into a drum mixer, stirring for 5-15 minutes, and then removing them from the drum for use; drying the semi-finished material obtained by uniform stirring in a drum, and then removing them from the drum for use, wherein the moisture content of the dried product is less than 0.1%; adding accurately measured carbonaceous material and oxidant, stirring for 7-12 minutes, and then removing them from the drum to obtain the finished product; and transporting the obtained finished product to a finished product warehouse for metering and packaging.

[0045] The air supply temperature for the drying process is 200° C.-450° C., and may be 200, 230, 250, 300, 350, 400 or 450° C., but is not limited thereto.

[0046] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 95 parts of chromium ore, 1 part of limestone, 1 part of graphite, and 3 parts of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 42.8%, Fe2O3: 25.7%, Al2O3: 14.3%, CaO: 0.5%, KMnO4: 2.7%, C 固 : 0.95%, loss on ignition: 0.4%, and the rest are inevitable impurities.

[0047] The method for preparing the above-mentioned drainage sand containing an oxidant comprises the following steps: accurately measuring chromium ore sand and limestone, adding them into a drum mixer, stirring for 10 minutes, and then removing them from the drum for later use; drying the semi-finished material obtained by uniform stirring in a drum, and then removing them from the drum for later use, wherein the air supply temperature for the drying process is 300°C, and the moisture content of the dried product is less than 0.1%; adding accurately measured graphite and potassium permanganate, stirring for 10 minutes, and then removing them from the drum to obtain a finished product; and transporting the obtained finished product to a finished product warehouse for metering and packaging.

[0048] The drainage sand in this embodiment is used in a steel plant in Daye, with a ladle capacity of 50T, steel grades of axle and bearing series steel, LF-VD refining method, 6-8h molten steel residence time, 102 furnaces in use, 101 self-opening furnaces, and a self-opening rate of 99.0%.

[0049] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 30 parts of chromium ore sand, 65 parts of quartz sand, 3 parts of limestone, 1 part of graphite, and 1 part of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 13.5%, SiO2: 60.5%, Fe2O3: 8.1%, Al2O3: 4.5%, CaO: 1.5%, KMnO4: 0.9%, C 固 : 0.95%, loss on ignition: 1.2%, and the rest are inevitable impurities.

[0050] The method for preparing the above-mentioned drainage sand containing an oxidant includes the following steps: accurately measuring chromium ore sand, quartz sand, and limestone, placing them in a drum mixer, stirring for 5 minutes, and then removing them from the drum for later use; drying the semi-finished material obtained by uniform stirring in a drum, and then removing them from the drum for later use, wherein the air supply temperature for the drying process is 450°C, and the moisture content of the dried product is less than 0.1%; adding accurately measured graphite and potassium permanganate, stirring for 12 minutes, and then removing them from the drum to obtain the finished product; and transporting the obtained finished product to a finished product warehouse for metering and packaging.

[0051] The drainage sand of this embodiment is used in a steel plant in Xining. The ladle capacity is 80T, the steel grades are bearing, nuclear power, and military steel, the refining method is CAS-LF-VD, the molten steel residence time is 4-6h, 114 furnaces are used, 113 furnaces are self-opened, and the self-opening rate is 99.1%.

[0052] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 32 parts of chromium ore, 65 parts of fused magnesia, 1 part of limestone, 1 part of graphite, and 1 part of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 14.4%, MgO: 61.8%, Fe2O3: 8.6%, Al2O3: 4.8%, CaO: 0.5%, KMnO4: 0.9%, C 固 : 0.95%, loss on ignition: 0.4%, and the rest are inevitable impurities.

[0053] The method for preparing the above-mentioned drainage sand containing an oxidant comprises the following steps: accurately measuring chromium ore, fused magnesia, and limestone, placing them in a drum mixer, stirring for 15 minutes, and then removing them from the drum for later use; drying the semi-finished material obtained by uniform stirring in a drum, and then removing them from the drum for later use, wherein the air supply temperature for the drying process is 200°C, and the moisture content of the dried product is less than 0.1%; adding accurately measured graphite and potassium permanganate, stirring for 7 minutes, and then removing them from the drum to obtain a finished product; and transporting the obtained finished product to a finished product warehouse for metering and packaging.

[0054] The drainage sand of this embodiment is used in a steel plant in Chengde. The ladle capacity is 70T, the steel grades are flange steel and alloy pipe series steel grades, the refining method is LF-VD, the molten steel residence time is 5-6h, 108 furnaces are used, 107 furnaces are self-opened, and the self-opening rate is 99.1%.

[0055] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 80 parts of chromium ore, 8 parts of quartz sand, 6 parts of fused magnesia, 2.5 parts of limestone, 1 part of carbon black, and 2.5 parts of potassium permanganate; the mass percentages of the effective ingredients are as follows: Cr2O3: 36.0%, SiO2: 7.4%, MgO: 5.7%, Fe2O3: 21.6%, Al2O3: 12.0%, CaO: 1.3%, KMnO4: 2.3%, C 固 : 0.95%, loss on ignition: 1.0%, and the rest are unavoidable impurities.

[0056] The method for preparing the above-mentioned drainage sand containing an oxidant comprises the following steps: accurately measuring chromium ore sand, quartz sand, fused magnesia sand, and limestone, placing them in a drum mixer, stirring for 10 minutes, and then removing them from the drum for later use; drying the semi-finished material obtained by uniform stirring in a drum, and then removing them from the drum for later use, wherein the air supply temperature for the drying process is 370°C, and the moisture content of the dried product is less than 0.1%; adding accurately measured carbon black and potassium permanganate, stirring for 9 minutes, and then removing them from the drum to obtain a finished product; and transporting the obtained finished product to a finished product warehouse for metering and packaging.

[0057] The drainage sand of this embodiment is used in a steel plant in Taiyuan. The ladle capacity is 60T, the steel grade is high-grade pipeline steel, the refining method is LF-RH, the molten steel residence time is 4-5h, the number of furnaces used is 120, the number of self-opening furnaces is 119, and the self-opening rate is 99.2%.

[0058] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 65 parts of chromium ore, 5 parts of quartz sand, 24 parts of fused magnesia, 2 parts of limestone, 2 parts of carbon black, and 2 parts of potassium permanganate; the mass percentages of the effective ingredients are as follows: Cr2O3: 29.3%, SiO2: 4.7%, MgO: 22.8%, Fe2O3: 17.6%, Al2O3: 9.8%, CaO: 1.0%, KMnO4: 1.8%, C 固 : 1.9%, loss on ignition: 0.8%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0059] The drainage sand in this embodiment is used in a steel plant in Wuyang. The ladle capacity is 80T, the steel type is axle series die-cast steel, the refining method is LF-VD, the steel liquid residence time is 5-7h, 154 furnaces are used, 153 furnaces are self-opened, and the self-opening rate is 99.4%.

[0060] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 50 parts of chromium ore, 32 parts of quartz sand, 10 parts of fused magnesia, 4 parts of limestone, 2 parts of carbon black, and 2 parts of potassium permanganate; the mass percentages of the effective ingredients are as follows: Cr2O3: 22.5%, SiO2: 29.8%, MgO: 9.5%, Fe2O3: 13.5%, Al2O3: 7.5%, CaO: 2.0%, KMnO4: 1.8%, C 固 : 1.9%, loss on ignition: 1.6%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0061] The drainage sand of this embodiment is used in a steel plant in Taiyuan. The ladle capacity is 70T, the steel grade is ultra-pure series stainless steel, the refining method is VOD-LF, the molten steel residence time is 5-7h, 180 furnaces are used, 179 furnaces are self-opened, and the self-opening rate is 99.4%.

[0062] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 35 parts of chromium ore, 19 parts of quartz sand, 41 parts of fused magnesia, 2 parts of limestone, 2 parts of carbon black, and 1 part of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 15.8%, SiO2: 17.7%, MgO: 39.0%, Fe2O3: 9.5%, Al2O3: 5.3%, CaO: 1.0%, KMnO4: 0.9%, C 固 : 1.9%, loss on ignition: 0.8%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0063] The drainage sand in this embodiment is used in a steel plant in Handan. The ladle capacity is 40T, the steel grade is high-alloy series die-cast steel, the refining method is LF-VD, the steel liquid residence time is 3-5h, 167 furnaces are used, 166 furnaces are self-opened, and the self-opening rate is 99.4%.

[0064] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 30 parts of chromium ore, 50 parts of quartz sand, 15 parts of fused magnesia, 2 parts of limestone, 2 parts of carbon black, and 1 part of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 13.5%, SiO2: 46.5%, MgO: 14.3%, Fe2O3: 8.1%, Al2O3: 4.5%, CaO: 1.0%, KMnO4: 0.9%, C 固 : 1.9%, loss on ignition: 0.8%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0065] The drainage sand of this embodiment is used in a steel plant in Baotou, with a ladle capacity of 50T, a heavy rail series steel, a refining method of LF-VD, a molten steel residence time of 3-5h, 196 furnaces in use, 195 self-opening furnaces, and a self-opening rate of 99.5%.

[0066] The statistical results of the application of the above-mentioned drainage sand show that the self-opening rate of the drainage sand of the present invention is above 99%, and the self-opening effect is particularly significant for small-capacity ladles or ladles with long molten steel retention time.

[0067] Comparative Example 1

[0068] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 52 parts of chromium ore sand, 33 parts of quartz sand, 11 parts of fused magnesia sand, 2 parts of carbon black, and 2 parts of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 23.4%, SiO2: 30.7%, MgO: 10.5%, Fe2O3: 14.0%, Al2O3: 7.8%, KMnO4: 1.8%, C 固 :1.9%, the rest are inevitable impurities. Its preparation method is reference to Example 4.

[0069] The drainage sand of this embodiment is used in a steel plant in Taiyuan. The ladle capacity is 70T, the steel grade is ultra-pure series stainless steel, the refining method is VOD-LF, the molten steel residence time is 5-7h, 180 furnaces are used, 162 furnaces are self-opened, and the self-opening rate is 89.4%.

[0070] Comparative Example 2

[0071] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 35 parts of chromium ore, 20 parts of quartz sand, 41 parts of fused magnesia, 2 parts of limestone, and 2 parts of carbon black; the mass percentages of its effective ingredients are: Cr2O3: 15.8%, SiO2: 18.6%, MgO: 39.0%, Fe2O3: 9.5%, Al2O3: 5.3%, CaO: 1.0%, C 固 : 1.9%, loss on ignition: 0.8%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0072] The drainage sand in this embodiment is used in a steel plant in Handan. The ladle capacity is 40T, the steel grade is high-alloy series die-cast steel, the refining method is LF-VD, the steel liquid residence time is 3-5h, 167 furnaces are used, 138 furnaces are self-opened, and the self-opening rate is 82.6%.

[0073] Comparative Example 3

[0074] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 30 parts of chromium ore, 50 parts of quartz sand, 12 parts of fused magnesia, 2 parts of limestone, 2 parts of carbon black, and 4 parts of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 13.5%, SiO2: 46.5%, MgO: 11.4%, Fe2O3: 8.1%, Al2O3: 4.5%, CaO: 1.0%, KMnO4: 3.6%, C固 : 1.9%, loss on ignition: 0.8%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0075] The drainage sand of this embodiment is used in a steel plant in Baotou. The ladle capacity is 50T, the steel grade is heavy rail series steel, the refining method is LF-VD, the molten steel residence time is 3-5h, the number of furnaces used is 196, the number of self-opening furnaces is 184, and the self-opening rate is 93.9%.

[0076] Comparative Example 4

[0077] A drainage sand containing an oxidant is made from the following raw materials in parts by weight: 20 parts of chromium ore, 70 parts of quartz sand, 6 parts of fused magnesia, 2 parts of limestone, 1 part of carbon black, and 1 part of potassium permanganate; the mass percentages of the effective ingredients are: Cr2O3: 9.0%, SiO2: 65.1%, MgO: 5.7%, Fe2O3: 5.4%, Al2O3: 3.0%, CaO: 1.0%, KMnO4: 0.9%, C 固 : 0.95%, loss on ignition: 0.8%, and the rest are inevitable impurities. The preparation method thereof is referred to Example 4.

[0078] The drainage sand of this embodiment is used in a steel plant in Baotou. The ladle capacity is 50T, the steel grade is heavy rail series steel, the refining method is LF-VD, the molten steel residence time is 3-5h, 153 furnaces are used, 133 furnaces are self-opened, and the self-opening rate is 86.9%.

[0079] 1. To evaluate the effect of drainage sand production on inclusions in molten steel, inclusions were detected in the steel slabs obtained in the above examples and comparative examples. The inclusions in the steel slab samples were analyzed using a scanning electron microscope and a large-area energy dispersive spectrometer. The inclusions were categorized by size, the number of inclusions of different sizes was counted, and a rating was performed in accordance with GB / T 10561. Three batches of drainage sand produced using Examples 1-8 and Comparative Examples 1-4 were randomly selected for inclusion testing. The test results were averaged, with the integer rounded. The statistical results are shown in the table below:

[0080]

[0081] The statistical results above show that the content of inclusions of different sizes varies in different steel billets produced using the drainage sand of the present invention. Inclusions of 2-5 μm are the most abundant, followed by inclusions of 1-2 μm, and DS inclusions ≥13 μm are the least abundant. The number of DS inclusions in Comparative Examples 2-4 increases significantly, and the number of inclusions of other sizes is also higher than that of the present invention. This demonstrates that the drainage sand of the present invention can reduce the size and content of inclusions in molten steel, thereby improving steel quality.

[0082] 2. To evaluate the flexural strength of drainage sand, the following experiment was conducted: 50g samples of drainage sand prepared in Examples 1-8 and Comparative Examples 1-4 were heated in a unidirectional heating furnace at 1550°C (a typical molten steel temperature) for 2 hours. The samples were then cooled naturally to room temperature, and their room-temperature flexural strength was measured. The specific testing method was in accordance with "Monomorphous Refractories - Part 6: Determination of Physical Properties (GB / T 4513.6-20175)". Type A specimens were used. The test results are shown in the following table:

[0083]

[0084] The above statistical results show that the room temperature flexural strength of the drainage sand of the present invention after heat treatment is 6-8 MPa. Practice has shown that the self-opening rate of the ladle is higher at this flexural strength.

[0085] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention may be improved in only one or several aspects, without having to simultaneously solve all the technical problems listed in the prior art or background art. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as limiting the claim.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A drainage sand containing an oxidant, characterized in that: The drainage sand is made from the following raw materials in parts by weight: 30-95 parts of chromium ore, 0-65 parts of quartz sand, 0-65 parts of fused magnesia, 1-4 parts of limestone, 1-2 parts of carbonaceous material, and 1-3 parts of oxidant; wherein the total weight of the chromium ore, quartz sand, fused magnesia, limestone, carbonaceous material, and oxidant is 100 parts, the oxidant is potassium permanganate, and the weight percentage of KMnO4 is ≥90%, and the room temperature flexural strength of the drainage sand is 6-8 MPa.

2. The oxidant-containing drainage sand according to claim 1, wherein: The chromium ore contains Cr2O3 in a weight percentage of ≥45%, Fe2O3 in a weight percentage of ≥27%, Fe 2+ 、Fe 3+ All are measured in terms of Fe2O3, with a weight percentage of Al2O3 ≤ 16%, and a particle size of 0.15mm-0.8mm.

3. The oxidant-containing drainage sand according to claim 1, wherein: The weight percentage of SiO2 in the quartz sand is ≥93%, and the particle size is 0.3mm-1.2mm.

4. The oxidant-containing drainage sand according to claim 1, wherein: The fused magnesia contains MgO in an amount of ≥95% by weight and has a particle size of 0.3 mm to 1.2 mm.

5. The oxidant-containing drainage sand according to claim 1, wherein: The limestone contains CaO at a weight percentage of ≥50%, has a loss on ignition of ≥40%, and has a particle size of 0.3 mm to 1.2 mm.

6. The oxidant-containing drainage sand according to claim 1, wherein: The carbonaceous material contains C 固 ≥95%, particle size ≤0.15mm.

7. The oxidant-containing drainage sand according to claim 1, wherein: The particle size of the oxidant is ≤0.15 mm.

8. The oxidant-containing drainage sand according to any one of claims 1 to 7, characterized in that: The mass percentages of its effective ingredients are: Cr2O3: 13.5%-43.0%, SiO2: 0%-61.0%, MgO: 0%-62.0%, Fe2O3: 8.0%-26.0%, Al2O3: 0%-14.3%, CaO: 0.5%-2.0%, KMnO4: 0.9%-3.0%, C 固 : 0.95%-2.0%, loss on ignition: 0.4%-1.6%, and the rest are inevitable impurities. The sum of the mass percentages of the effective ingredient, loss on ignition and impurities is 100%.

9. The method for preparing drainage sand containing an oxidant according to claim 8, wherein: The following steps are involved: Step S1: After accurately measuring chromium ore, quartz sand, fused magnesia, and limestone, the mixture is placed in a drum mixer and stirred for 5-15 minutes before being removed from the mixer for later use; Step S2: The semi-finished product obtained by uniformly stirring in step S1 is subjected to drum drying and then removed from the drum for later use. The moisture content of the dried product is less than 0.1%; Step S3: Add accurately measured carbonaceous material and oxidant, stir for 7-12 minutes, and then remove from the pan to obtain the finished product; Step S4: The finished products are transported to the finished product warehouse for metering and packaging.

10. The method for preparing drainage sand containing an oxidant according to claim 9, wherein: The air supply temperature of the drying process is 200°C-450°C.

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