A gap filler for a slag notch of a converter and a construction method thereof

Abstract

The present disclosure relates to the technical field of refractory materials for steel smelting, and provides a gap filler for a converter slag stopping taphole and a construction method; the gap filler is prepared from the following raw materials in percentage by mass: sintered magnesia 60-70%, fine powder of magnesium-containing waste brick 18-26%, fine powder of spinel-containing waste brick 6-10%, silicon powder 3-5%, sintered water reducing agent 0.5-1.5%, and retarder 0.1-0.3%. The present disclosure provides a gap filler for a converter slag stopping taphole, which is used for filling the gap between the converter slag stopping taphole and the seat brick; the gap filler has excellent erosion resistance and scouring resistance by adding specific components and regulating the content of the components, is easy to drill, and has the advantage of low cost.

Description

Technical Field

[0001] This disclosure relates to the field of refractory materials for iron and steel smelting, and in particular to a gap filler and construction method for use in the slag-blocking and steel tapping outlet of a converter. Background Technology

[0002] Converter steelmaking is the foundation of modern industry. Currently, the pace of steelmaking is accelerating, with tapping at the taphole being a crucial factor affecting this pace. Steel slag generated during converter steelmaking is harmful when it enters subsequent processes: it affects the lifespan of ladle refractory materials; it causes sulfur and phosphorus reversion in molten steel, impacting steel quality; it increases the consumption of ferroalloys after the furnace; it increases the amount of synthetic slag used in subsequent processes; and it prolongs the processing time in refining processes. Converter slag discharge consists of three parts: early-stage slag, vortex-effect slag during tapping, and late-stage slag. Currently, the commonly used slag-blocking methods in converter tapping both domestically and internationally are: slag-blocking caps for early-stage slag and slag-blocking balls or plugs for late-stage slag. In addition, pneumatic slag blocking and infrared slag detection methods are gradually being applied to converter tapping slag control. However, these methods cannot achieve slag blocking throughout the entire process before and after tapping, especially for early-stage slag, which is almost uncontrollable. Slide plate slag blocking effectively solves these problems. The slag-blocking mechanism uses a hydraulic cylinder to pull two sliding plate bricks to slide relative to each other, thereby opening and closing the sliding plate to adjust the flow rate of molten steel and control the amount of slag, thus ensuring the quality of the molten steel.

[0003] With increasingly fierce competition in the steel market, converter slag-blocking technology has become an inevitable choice for producing specialty and high-quality steel. Furthermore, converter production efficiency has become a crucial indicator pursued by steel mills annually, with every process affecting efficiency being monitored and improved. Among these improvements, the replacement time of the converter slag-blocking taphole (non-steelmaking time) has been continuously reduced by steel mills. The replacement of the converter slag-blocking taphole typically involves steps such as dismantling the mechanism, drilling, taphole fixing, filling the gap between the taphole and the bedding brick, sintering the filler material, and installing the mechanism. The time spent on dismantling the mechanism, fixing the taphole, and installing the mechanism is related to the skill level of the hot repair personnel; the drilling time is mainly related to the sintering strength of the filler material and the strength of the taphole brick; the time spent on filling the gap between the taphole and the bedding brick and sintering the filler material is mainly related to the properties of the filler material and the filling process. There is generally a 20-40mm gap between the taphole and the bedding brick that needs to be filled. Existing technologies include dry filling and spray filling.

[0004] Dry filling involves adding dry material into the furnace, shaking the furnace to 90-95°C, and using the furnace temperature to allow the material to flow naturally and fill the gaps, followed by baking and sintering. Spray filling uses spraying equipment to spray dry material and water into the gaps, followed by baking. The former method uses asphalt or resin as the binder, which requires softening to flow, resulting in longer filling and sintering times and significant smoke production. The latter method uses a higher proportion of water in the spraying process, leading to longer filling and sintering times, severely impacting tapping intervals and converter production. Furthermore, both dry and spray filling methods result in high filler sintering strength, leading to longer drilling times, typically 20-30 minutes, with a minimum of 15-20 minutes.

[0005] Based on the above problems, it is of great significance to provide a filling material for the gap of the slag-blocking and steel tapping outlet of a converter. Summary of the Invention

[0006] The technical problem solved by this disclosure is to provide a gap filler for the slag-blocking and steel tapping port of a converter. The gap filler provided by this disclosure is used for slag-blocking and filling of converters, and has excellent anti-erosion and anti-scouring properties. It is also easy to drill and has the advantage of low cost.

[0007] In view of this, the present disclosure provides a gap filler for the slag-blocking taphole of a converter, which is prepared from the following raw materials by mass percentage:

[0008] Sintered magnesia 60-70%, magnesium-containing waste brick fine powder 18-26%, spinel-containing waste brick fine powder 6-10%, silica fume 3-5%, sintering water-reducing agent 0.5-1.5%;

[0009] Based on the total amount of the sintered magnesia, the magnesium-containing waste brick fine powder, the spinel-containing waste brick fine powder, the silica powder, and the sintering water-reducing agent, the content of the retarder is 0.1~0.3%.

[0010] In some specific embodiments, based on the total mass of sintered magnesia, the sintered magnesia comprises 35-45% coarse sintered magnesia particles of 1-3 mm, 18-25% medium sintered magnesia particles of 0.5-1 mm, and 34-43% fine sintered magnesia particles of 0-0.5 mm.

[0011] In some specific embodiments, the content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm; the content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm; the content of the first silica powder in the silica powder is ≥85wt%, and the particle size of the first silica powder is ≤5μm; the content of the first sintering water-reducing agent in the sintering water-reducing agent is ≥85wt%, and the particle size of the first sintering water-reducing agent is ≤0.1mm; the content of the first retarder in the retarder is ≥85wt%, and the particle size of the first retarder is ≤0.1mm.

[0012] In some specific embodiments, the magnesium-containing waste brick fine powder is prepared from waste magnesium bricks with MgO ≥ 95 wt% or waste magnesium chromium bricks with MgO + Cr2O3 ≥ 90 wt%, and / or, the spinel-containing waste brick fine powder is prepared from RH-grade magnesium spinel waste bricks.

[0013] In some specific embodiments, the sintered magnesia contains 90-95 wt% MgO and has a particle bulk density of 3.18-3.25 g / cm³. 3 .

[0014] In some specific embodiments, the sintering water-reducing agent includes one or both of sodium tripolyphosphate and sodium hexametaphosphate, and / or the retarder includes one or both of tartaric acid and citric acid.

[0015] In some specific embodiments, the method for preparing the gap filler includes:

[0016] After stirring the sintered magnesia, add magnesium-containing waste brick fine powder, spinel-containing waste brick fine powder, silica powder, sintering water-reducing agent and retarder, and stir to obtain a gap filler.

[0017] This application also provides a construction method using a gap filler, comprising the following steps:

[0018] S1. Mix the gap filler and water to obtain a self-flowing material; the gap filler is the gap filler described in the above scheme;

[0019] S2. Replace the old steel outlet with a new steel outlet, fill the gap between the steel outlet sleeve and the seat brick with the gravity flow material, and bake the gap after filling; then install the sliding plate slag blocking mechanism.

[0020] In some specific embodiments, the amount of water added is 13-14 wt% of the gap filler.

[0021] In some specific embodiments, the total time for filling and baking is 8 to 10 minutes.

[0022] This disclosure provides a gap filler for the slag-blocking taphole of a converter, which is prepared from the following raw materials: sintered magnesia, fine powder of magnesia-containing waste bricks, fine powder of spinel-containing waste bricks, silica powder, sintering water-reducing agent, and retarder. Sintered magnesia serves as aggregate, while the fine powder of magnesia-containing waste bricks, fine powder of spinel-containing waste bricks, silica powder, sintering water-reducing agent, and retarder serve as matrix. The fine powder of spinel-containing waste bricks in the matrix undergoes volume expansion due to the magnesium-aluminum spinelization reaction, which helps improve the filler's resistance to erosion and permeation. Precise control of the sintering water-reducing agent content ensures both drilling time and the filler's resistance to permeation. Silica powder, as a binder, gives the filler good fluidity and improves its resistance to permeation. The introduction of sintered magnesia and fine powder of magnesia-containing waste bricks reduces costs while ensuring good erosion resistance of the gap filler. Furthermore, the selection of aggregates and matrix in this disclosure allows for control of sintering strength while shortening drilling time. Detailed Implementation

[0023] To further understand this disclosure, preferred embodiments of this disclosure are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of this disclosure and are not intended to limit the scope of the claims of this disclosure.

[0024] In view of the problems of long filling, baking time, and drilling time in the existing technology for filling the gap between the tapping spout and the seat brick during the replacement of the converter slag-blocking tapping spout, this disclosure provides a gap filler for the converter slag-blocking tapping spout. This gap filler, by adding specific components and controlling the content of the components, exhibits excellent anti-erosion and anti-scouring properties, is easy to drill, and has the advantage of low cost. Specifically, this disclosure provides a gap filler for the converter slag-blocking tapping spout, prepared from the following raw materials by mass percentage:

[0025] Sintered magnesia 60-70%, magnesium-containing waste brick fine powder 18-26%, spinel-containing waste brick fine powder 6-10%, silica fume 3-5%, sintering water-reducing agent 0.5-1.5%;

[0026] Based on the total amount of the sintered magnesia, the magnesium-containing waste brick fine powder, the spinel-containing waste brick fine powder, the silica powder, and the sintering water-reducing agent, the content of the retarder is 0.1~0.3%.

[0027] In this disclosure, the raw materials for the interstitial filler (magnesia self-flowing material) include sintered magnesia, fine powder of magnesium-containing waste bricks, fine powder of spinel-containing waste bricks, silica powder, sintering water-reducing agent, and retarder. The key component, sintered magnesia, serves as aggregate, while the fine powder of magnesium-containing waste bricks, fine powder of spinel-containing waste bricks, silica powder, sintering water-reducing agent, and retarder form the matrix. Controlling the content of the sintered magnesia allows for better performance and flowability of the magnesium self-flowing material, meeting the requirements for controlling the drilling time at the taphole and the baking time of the filler. The sintered magnesia provides the basic framework of the magnesium self-flowing material. On the one hand, it reduces the cost of raw materials compared to fused magnesia and high-grade sintered magnesia. On the other hand, the slightly higher levels of impurities such as silica and iron oxide in the sintered magnesia facilitate high-temperature sintering of the matrix. Based on the total mass of sintered magnesia, the sintered magnesia comprises 35-45% coarse sintered magnesia particles of 1-3 mm, 18-25% medium sintered magnesia particles of 0.5-1 mm, and 34-43% fine sintered magnesia particles of 0-0.5 mm; that is, the sintered magnesia adopts a combination of coarse, medium, and fine particles, with a high content of coarse and fine particles and a low content of medium particles, in order to obtain larger and denser particle packing, thus ensuring the stability of the skeleton structure.

[0028] In this disclosure, the amount of sintered magnesia is 60-70 wt%, in some specific embodiments it is 62-67 wt%, and in some specific embodiments it is 63-65 wt%. Furthermore, based on the total mass of the sintered magnesia, the sintered magnesia comprises 35-45% coarse sintered magnesia particles of 1-3 mm, 18-25% medium sintered magnesia particles of 0.5-1 mm, and 34-43% fine sintered magnesia particles of 0-0.5 mm; in some specific embodiments, the sintered magnesia comprises 38-43% coarse sintered magnesia particles of 1-3 mm, 19-24% medium sintered magnesia particles of 0.5-1 mm, and 36-41% fine sintered magnesia particles of 0-0.5 mm; in some specific embodiments, the sintered magnesia comprises 39-40% coarse sintered magnesia particles of 1-3 mm, 20-22% medium sintered magnesia particles of 0.5-1 mm, and 38-39% fine sintered magnesia particles of 0-0.5 mm.

[0029] In this disclosure, the sintered magnesia has an MgO content of 90-95 wt% and a particle density of 3.18-3.25 g / cm³. 3 .

[0030] In this disclosure, both the magnesium-containing waste brick fine powder and the spinel-containing waste brick fine powder are waste bricks that have been used in high-temperature environments, resulting in more stable performance. In some specific embodiments, the magnesium-containing waste brick fine powder is prepared from waste magnesium bricks with MgO ≥ 95 wt% or waste magnesia-chrome bricks with MgO + Cr2O3 ≥ 90 wt%. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is ≥ 85 wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤ 0.074 mm. The content of the magnesium-containing waste brick fine powder is 18~26 wt%, in some specific embodiments it is 19~25 wt%, in some specific embodiments it is 21~24 wt%, and in some specific embodiments it is 22~23 wt%.

[0031] In this disclosure, the content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm. In some specific embodiments, the spinel-containing waste brick fine powder is prepared from RH-processed magnesium spinel waste bricks. In some specific embodiments, the spinel-containing waste brick fine powder is spinel-containing waste brick fine powder with a magnesium-aluminum spinel content of ≥90%. The content of the magnesium spinel fine powder is 6~10wt%, in some specific embodiments it is 7~9wt%, and in some specific embodiments it is 8~9wt%. The addition of the spinel-containing waste brick fine powder to the magnesium self-flowing material is due to the good erosion and permeability resistance and high-temperature volume stability of spinel itself, and also to the volume expansion generated by the spinelization reaction of magnesium oxide and aluminum oxide to offset part of the high-temperature sintering shrinkage of the self-flowing material.

[0032] In this disclosure, both the magnesium-containing waste brick fine powder and the spinel-containing waste brick fine powder are added in the form of fine powder. Compared with the addition method in the form of waste brick particles, the fine powder has a more uniform composition and is easier to sinter, thus obtaining a stable homogeneous self-flowing material and improving its erosion resistance and impermeability.

[0033] In this disclosure, the silica powder acts as a binder, combined with sintering water-reducing agents and retarders, to achieve good flowability and moderate room-temperature, medium-temperature, and high-temperature strength in magnesia self-flowing materials. Specifically, the silica powder is at the micro-powder level. At room to medium temperatures, the Si-OH (silanol groups) on the surface of the silica powder undergoes dehydration and condensation to form a Si-O-Si network structure. After hydration, it forms a silica-like Si-OH structure. During drying, the Si-OH dehydrates and polymerizes into long chains, further cross-linking into a three-dimensional network. This structure remains stable below 2500℃, providing strength to the magnesia self-flowing material at low to medium temperatures. At high temperatures, the silica powder reacts with magnesium oxide to form high-temperature bonding phases such as dicalcium silicate and tricalcium silicate. Furthermore, the silica powder also acts as a filler and densifier. Its extremely fine particles effectively fill the tiny gaps in refractory aggregates, reducing the amount of mixing water, lowering apparent porosity, and improving the bulk density and compactness of the material. In some specific embodiments, the content of the first silicon micropowder in the silicon micropowder is ≥85wt%, and the particle size of the first silicon micropowder is ≤5μm. The content of the silicon micropowder is 3~5wt%, in some specific embodiments it is 3.5~4.5wt%, and in some specific embodiments it is 3.5~4wt%.

[0034] In the interstitial filler provided in this disclosure, the water-reducing effect of the sintering water-reducing agent is mainly achieved through dispersion, electrostatic repulsion, and ion chelation. In some specific embodiments, the sintering water-reducing agent includes one or both of sodium tripolyphosphate and sodium hexametaphosphate. The sodium tripolyphosphate in the sintering water-reducing agent has a melting point of 622°C, and the sodium hexametaphosphate has a melting point of 616°C, which can promote sintering and improve the strength at medium and high temperatures. The content of the first sintering water-reducing agent in the sintering water-reducing agent is ≥85wt%, and the particle size of the first sintering water-reducing agent is ≤0.1mm. The content of the sintering water-reducing agent is 0.5~1.5wt%, and in some specific embodiments, the content of the sintering water-reducing agent is 0.5~1.0wt%.

[0035] In this disclosure, the content of the first retarder in the retarder is ≥85wt%, and the particle size of the first retarder is ≤0.1mm; in some specific embodiments, the retarder includes one or both of tartaric acid and citric acid. In this disclosure, the amount of retarder added is based on the total amount of the sintered magnesia, the magnesium-containing waste brick fine powder, the spinel-containing waste brick fine powder, the silica powder, and the sintering water-reducing agent, that is, the total mass of the sintered magnesia, the magnesium-containing waste brick fine powder, the spinel-containing waste brick fine powder, the silica powder, and the sintering water-reducing agent is 100%, and the content of the retarder is 0.1~0.3wt% of the total mass of the above components. In some specific embodiments, the content of the retarder is 0.2~0.3wt%.

[0036] The interstitial filler disclosed herein uses ordinary sintered magnesia as aggregate, with an MgO content of 90.0-95.0% and a particle density of 3.18-3.25 g / cm³. 3 The aggregate is entirely selected from ordinary sintered magnesia. On the one hand, this reduces the cost of raw materials compared to fused magnesia and high-grade sintered magnesia. On the other hand, the slightly higher levels of impurities such as silica and iron oxide in sintered magnesia contribute to the high-temperature sintering of the matrix. The matrix fine powder mainly consists of magnesia-containing waste brick fine powder and spinel-containing waste brick fine powder. The use of magnesia as the primary material for both the aggregate and matrix fine powder ensures good erosion resistance of the self-flowing material. The matrix fine powder consists mainly of magnesia-containing waste brick fine powder and spinel-containing waste brick fine powder. The former is sourced from kilns in the building materials industry, such as... Waste magnesia-chrome bricks or waste magnesia bricks recycled from cement kilns or glass kilns are obtained through impurity removal, crushing, and ball milling; the latter is obtained from waste spinel bricks from RH furnaces through impurity removal, crushing, and ball milling. Both are recycled and reused after high-temperature use, resulting in lower production costs and more stable and reliable performance. Furthermore, the spinel-containing waste brick powder in the matrix fine powder can eliminate some of the matrix sintering shrinkage by utilizing the volume expansion generated by the magnesium-aluminum spinelization reaction, thereby improving the matrix's resistance to erosion and permeation.

[0037] The amount of sintering water-reducing agent added must be strictly controlled. Too much will lead to excessive strength of the self-flowing material after firing, affecting drilling speed and drilling time; too little will affect the strength of the self-flowing material after firing and reduce its impermeability. Using silica powder as a binder and controlling the ratio of aggregate to fine powder can achieve better fluidity, ensure dense filling without dead corners, and greatly improve the impermeability of the self-flowing material.

[0038] In this disclosure, the method for preparing the gap filler includes:

[0039] After stirring the sintered magnesia, add magnesium-containing waste brick fine powder, spinel-containing waste brick fine powder, silica powder, sintering water-reducing agent and retarder, and stir to obtain a gap filler.

[0040] In the above preparation process, the sintered magnesia is prepared by mixing sintered magnesia of different particle sizes and stirring for 2 to 3 minutes. The stirring time for adding magnesium-containing waste brick fine powder, spinel-containing waste brick fine powder, silica powder, sintering water-reducing agent and retarder is 3 to 5 minutes. In some specific embodiments, the stirring time is 3.5 to 5 minutes.

[0041] In this disclosure, the magnesium-containing waste brick fine powder can be prepared according to the following method:

[0042] Waste magnesia bricks with MgO ≥ 95% or waste magnesia-chrome bricks with MgO + Cr2O3 ≥ 90% are recycled. After removing impurities manually, they are crushed, pulverized, and ball-milled to obtain fine powder of magnesia-containing waste bricks. The content of the first type of magnesia-containing waste brick fine powder in the fine powder is required to be ≥ 85 wt%, and the particle size of the first type of magnesia-containing waste brick fine powder is ≤ 0.074 mm.

[0043] The spinel-containing waste brick fine powder can be prepared according to the following method:

[0044] RH is recycled from magnesium spinel waste bricks. After manual removal of impurities, the waste bricks are crushed, pulverized, and ball-milled to obtain spinel-containing waste brick fine powder. The content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm.

[0045] Furthermore, this disclosure also provides a construction method using a gap filler, comprising the following steps:

[0046] S1. Mix the gap filler and water to obtain a self-flowing material; the gap filler is the gap filler described in the above scheme;

[0047] S2. Replace the old steel outlet with a new steel outlet, fill the gap between the steel outlet sleeve and the seat brick with the gravity flow material, and bake the gap after filling; then install the sliding plate slag blocking mechanism.

[0048] In the above construction method, the amount of water added is 13-14 wt% of the gap filler. The amount of water added is to ensure the fluidity of the gap filler. If the amount added is too small, the gap filler will not flow properly, resulting in poor filling effect. If the amount added is too large, the baking time will be prolonged, and the physicochemical properties of the gap filler will also be affected. For example, excessive water will increase the apparent porosity of the gap filler, reduce its bulk density and strength, thereby affecting its resistance to erosion and permeability. The total filling and baking time is 8-10 minutes.

[0049] Specifically, the on-site application method for gap filler is as follows:

[0050] 1) At the slag blocking site, first turn on the mixer, hoist the interstitial filler ton bag into the mixer, add water while mixing, strictly control the amount of water added at a ratio of 13~14%, mix for 8~10 minutes, and put the obtained magnesium self-flowing material into a ton bag with a plastic liner.

[0051] 2) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, shake the furnace to the scrap steel loading position in front of the furnace, hoist the prepared bagged self-flowing material into the furnace, shake the furnace quickly to 92°, and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill it.

[0052] 3) Bake immediately after filling, with the total filling and baking time controlled at 8-10 minutes;

[0053] 4) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the sliding plate slag-blocking mechanism;

[0054] 5) Once the mechanism is installed, converter production can begin.

[0055] The gap filler (water-based magnesium self-flowing material) used in this disclosure fills the steel tap hole. Compared with the existing dry material filling technology, on the one hand, it is more environmentally friendly, safer, and greener because there is no smoke pollution caused by asphalt or resin. On the other hand, the filling and baking time is greatly shortened compared with the dry material filling and baking. The dry material filling and baking generally takes 25 to 30 minutes, and at least 15 to 20 minutes, while the filling and baking time of this disclosure is generally controlled within 8 to 10 minutes.

[0056] This disclosure uses water-based magnesium self-flowing material to fill the steel outlet. Compared with the existing spray filling technology, the amount of water added is only about half that of the spray filling and the filling speed is faster, thus saving a lot of filling and baking time. The spray filling process generally takes 20 to 30 minutes for filling and baking, and at least 15 to 20 minutes, while the filling and baking time of this disclosure is generally controlled at 8 to 10 minutes.

[0057] Furthermore, this disclosure uses water-based magnesia self-flowing material, which reduces drilling time to 5-8 minutes compared to existing technologies due to strict control of the sintering strength of the self-flowing material. The water-based magnesia self-flowing material used in this disclosure fills the taphole, reducing drilling time by 10-12 minutes compared to existing technologies, and reducing filling and baking time by 7-10 minutes. Under the condition that other factors affecting the process remain unchanged, each taphole replacement saves 17-22 minutes. Based on the actual steelmaking rhythm of a 210-ton converter in a steel plant, with a smelting time of 28 minutes per heat, a taphole lifespan of 240 cycles, a slag-blocking slide lifespan of 20 cycles, an inner nozzle lifespan of 60 cycles, a replacement mechanism time of 10 minutes, a replacement mechanism + inner nozzle time of 14 minutes, and a replacement mechanism + inner nozzle + taphole time of 45 minutes, the time required to use up one set of tapholes = 28 * 240. + (240 / 60-1)*14+(240 / 20-240 / 60+1)*10+45=6897min. The number of tapping spouts needed per month (calculated as 30 days) = (30*24*60) / 6897=6.26 sets. Using this disclosure, each set of tapping spouts can save 17~22 minutes, so it can save 106.4~137.7 minutes per month. Based on the smelting time of 28 minutes per furnace, it can produce 3.8~4.9 more furnaces of steel per month, and 45.6~58.8 more furnaces of steel per year. Based on two 210-ton converters in a steel plant, it can produce 19152~24696 tons of steel per year.

[0058] In summary, by using magnesia self-flowing material to fill the gap between the tap hole guide and the seat brick, this disclosure not only shortens the drilling time but also achieves a better filling effect, greatly reduces the filling and baking time, increases the tap hole replacement speed, and improves the converter production efficiency.

[0059] To further understand this disclosure, the gap filler for converter slag-blocking and steel tapping outlet provided in this disclosure will be described in detail below with reference to the embodiments. The scope of protection of this disclosure is not limited to the following embodiments.

[0060] Example 1

[0061] 1) Preparation of magnesium-containing waste brick fine powder: Waste magnesium bricks with MgO content of 96.12% are recycled, impurities are removed manually, and then crushed and ball-milled to obtain magnesium-containing waste brick fine powder. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm.

[0062] 2) Preparation of spinel-containing waste brick fine powder: RH with a magnesium aluminum spinel (MA) content of 91.25% is recycled with spinel waste bricks. After manual removal of impurities, the waste bricks are crushed and ball-milled to obtain spinel-containing waste brick fine powder. The content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm.

[0063] 3) Fully premixed matrix fine powder: 22% magnesium-containing waste brick fine powder, 8% spinel-containing waste brick fine powder, 4% silica powder (≤5μm), 1% sintering water-reducing agent sodium tripolyphosphate (≤0.1mm) and 0.2% retarder tartaric acid (≤0.1mm) are added to a premixing device for vigorous premixing for 15 minutes to obtain premixed fine powder;

[0064] 4) Put 1-3 mm of 26% MS90 sintered magnesia, 0.5-1 mm of 14% MS90 sintered magnesia and 0-0.5 mm of 25% MS90 sintered magnesia into a sand mixer and stir for 2 minutes. Then add the premixed fine powder and stir for 5 minutes. Discharge the material into a ton bag to obtain the gap filler.

[0065] 5) At the slag blocking site, first turn on the mixer, hoist the interstitial filler obtained in step 4) into the mixer, add water while mixing, strictly control the amount of water added at a ratio of 13.5wt% (the amount of water added is 13.5wt% of the interstitial filler), mix for 8 minutes, and put the obtained magnesium self-flowing material into the ton bag with a plastic inner liner.

[0066] 6) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, the furnace is moved to the scrap steel loading position in front of the furnace. The self-flowing material obtained in step 5) is hoisted into the furnace using a furnace dismantling machine. The furnace is then quickly moved to 92°, and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill the gap.

[0067] 7) Bake immediately after filling, with the total filling and baking time controlled within 8 minutes;

[0068] 8) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the sliding plate slag-blocking mechanism;

[0069] 9) Once the mechanism is installed, converter production can begin.

[0070] 10) Replace the tap hole after 242 uses. The drilling time during the replacement process is 6 minutes.

[0071] Example 2

[0072] 1) Preparation of magnesium-containing waste brick fine powder: Waste magnesium bricks with MgO content of 95.24% are recycled, impurities are removed manually, and then crushed and ball-milled to obtain magnesium-containing waste brick fine powder. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm.

[0073] 2) Preparation of spinel-containing waste brick fine powder: RH with MA content of 90.14% is recycled with spinel waste bricks, and after manual removal of impurities, it is crushed and ball-milled to obtain spinel-containing waste brick fine powder. It is required that the content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm.

[0074] 3) Fully premixed matrix fine powder: 21% magnesium-containing waste brick fine powder, 7% spinel-containing waste brick fine powder, 4.5% silica powder (≤5μm), 0.5% sintering water-reducing agent sodium tripolyphosphate (≤0.1mm) and 0.3% retarder citric acid (≤0.1mm) are added to a premixing device for vigorous premixing for 10 minutes to obtain premixed fine powder;

[0075] 4) Put 1-3 mm of 28% MS92 sintered magnesia, 0.5-1 mm of 13% MS92 sintered magnesia and 0-0.5 mm of 26% MS92 sintered magnesia into a sand mixer and stir for 3 minutes. Then add the premixed fine powder and stir for 4 minutes. Discharge the material into a ton bag to obtain the gap filler.

[0076] 5) At the slag blocking site, first turn on the mixer, hoist the interstitial filler obtained in step 4) into the mixer, add water while mixing, strictly control the amount of water added according to the ratio of 13wt% (the amount of water added is 13wt% of the interstitial filler), mix for 9 minutes, and put the obtained magnesium self-flowing material into the ton bag with plastic liner.

[0077] 6) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, the furnace is moved to the scrap steel loading position in front of the furnace. The self-flowing material obtained in step 5) is hoisted into the furnace using a furnace dismantling machine. The furnace is then quickly moved to 92°, and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill the gap.

[0078] 7) Bake immediately after filling, with the total filling and baking time controlled within 10 minutes;

[0079] 8) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the sliding plate slag-blocking mechanism;

[0080] 9) Once the mechanism is installed, converter production can begin.

[0081] 10) The converter tapping spout should be replaced after 238 uses. The drilling time during the replacement process is 7 minutes.

[0082] Example 3

[0083] 1) Preparation of magnesium-containing waste brick fine powder: Waste magnesium chrome bricks with MgO+Cr2O3 content of 91.22% are recycled, impurities are removed manually, and then crushed and ball-milled to obtain magnesium-containing waste brick fine powder. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm.

[0084] 2) Preparation of spinel-containing waste brick fine powder: RH with MA content of 90.46% is recycled with spinel waste bricks, and after manual removal of impurities, it is crushed and ball-milled to obtain spinel-containing waste brick fine powder. It is required that the content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm.

[0085] 3) Fully premixed matrix fine powder: 22% magnesium-containing waste brick fine powder, 9% spinel-containing waste brick fine powder, 5% silica powder (≤5μm), 1% sintering water-reducing agent sodium hexametaphosphate (≤0.1mm) and 0.1% retarder tartaric acid (≤0.1mm) are added to a premixing device for vigorous premixing for 14 minutes to obtain premixed fine powder;

[0086] 4) Put 1-3mm of 24%MS94 sintered magnesia, 0.5-1mm of 15%MS94 sintered magnesia and 0-0.5mm of 24%MS94 sintered magnesia into a sand mixer and stir for 2.5 minutes. Then add the premixed fine powder and stir for 4.5 minutes. Discharge the material into a ton bag to obtain the gap filler.

[0087] 5) At the slag blocking site, first turn on the mixer, hoist the interstitial filler obtained in step 4) into the mixer, add water while mixing, strictly control the amount of water added according to the ratio of 14wt% (the amount of water added is 14wt% of the interstitial filler), mix for 9 minutes, and put the obtained magnesium self-flowing material into the ton bag with plastic liner.

[0088] 6) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, the furnace is moved to the scrap steel loading position in front of the furnace. The self-flowing material obtained in step 5) is hoisted into the furnace using a furnace dismantling machine. The furnace is then quickly moved to 92°, and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill the gap.

[0089] 7) Bake immediately after filling, with the total filling and baking time controlled within 9 minutes;

[0090] 8) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the sliding plate slag-blocking mechanism;

[0091] 9) Once the mechanism is installed, converter production can begin.

[0092] 10) The converter tapping spout should be replaced after 244 uses. The drilling time during the replacement process is 7 minutes.

[0093] Example 4

[0094] 1) Preparation of magnesium-containing waste brick fine powder: Waste magnesium chrome bricks with MgO+Cr2O3 content of 92.01% are recycled, impurities are removed manually, and then crushed and ball-milled to obtain magnesium-containing waste brick fine powder. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm.

[0095] 2) Preparation of spinel-containing waste brick fine powder: RH with MA content of 90.88% is recycled with spinel waste bricks, and after manual removal of impurities, it is crushed and ball-milled to obtain spinel-containing waste brick fine powder. It is required that the content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm.

[0096] 3) Fully premixed matrix fine powder: 23% magnesium-containing waste brick fine powder, 8% spinel-containing waste brick fine powder, 3.5% silica powder (≤5μm), 0.5% sintering water-reducing agent sodium tripolyphosphate (≤0.1mm) and 0.2% retarder tartaric acid (≤0.1mm) are added to a premixing device for vigorous premixing for 14 minutes to obtain premixed fine powder;

[0097] 4) Put 1-3 mm of 25% MS95 sintered magnesia, 0.5-1 mm of 14% MS95 sintered magnesia and 0-0.5 mm of 26% MS95 sintered magnesia into a sand mixer and stir for 2 minutes. Then add the premixed fine powder and stir for 3.5 minutes. Discharge the material into a ton bag to obtain the gap filler.

[0098] 5) At the slag blocking site, first turn on the mixer, hoist the interstitial filler obtained in step 4) into the mixer, add water while mixing, strictly control the amount of water added at a ratio of 13.5wt% (the amount of water added is 13.5wt% of the interstitial filler), mix for 10 minutes, and put the obtained magnesium self-flowing material into the ton bag with a plastic inner liner.

[0099] 6) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, the furnace is moved to the scrap steel loading position in front of the furnace. The self-flowing material obtained in step 5) is hoisted into the furnace using a furnace dismantling machine. The furnace is then quickly moved to 92°, and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill the gap.

[0100] 7) Bake immediately after filling, with the total filling and baking time controlled within 10 minutes;

[0101] 8) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the sliding plate slag-blocking mechanism;

[0102] 9) Once the mechanism is installed, converter production can begin.

[0103] 10) Replace the converter taphole after 240 uses. The drilling time during the replacement process is 8 minutes.

[0104] Comparative Example 1

[0105] 1) Preparation of magnesium-containing waste brick fine powder: Waste magnesium bricks with MgO content of 96.12% are recycled, impurities are removed manually, and then crushed and ball-milled to obtain magnesium-containing waste brick fine powder. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm.

[0106] 2) Preparation of spinel-containing waste brick fine powder: RH with MA content of 91.25% is recycled with spinel waste bricks, and after manual removal of impurities, it is crushed and ball-milled to obtain spinel-containing waste brick fine powder. It is required that the content of the first spinel-containing waste brick fine powder in the spinel-containing waste brick fine powder is ≥85wt%, and the particle size of the first spinel-containing waste brick fine powder is ≤0.074mm.

[0107] 3) Fully premixed matrix fine powder: 22% magnesium-containing waste brick fine powder, 8% spinel-containing waste brick fine powder, 4% silica powder (≤5μm), 1% sintering water-reducing agent sodium tripolyphosphate (≤0.1mm) and 0.2% retarder tartaric acid (≤0.1mm) are added to a premixing device for vigorous premixing for 15 minutes to obtain premixed fine powder;

[0108] 4) Put 1-3 mm of 32% MS90 sintered magnesia and 0-0.5 mm of 33% MS90 sintered magnesia into a sand mixer and stir for 2 minutes. Then add the premixed fine powder and stir for 5 minutes. Discharge the material into a ton bag to obtain the gap filler.

[0109] 5) At the slag blocking site, first turn on the mixer, hoist the interstitial filler obtained in step 4) into the mixer, add water while mixing, strictly control the amount of water added at a ratio of 13.5wt% (the amount of water added is 13.5wt% of the interstitial filler), mix for 8 minutes, and put the obtained magnesium self-flowing material into the ton bag with a plastic inner liner.

[0110] 6) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, the furnace is moved to the scrap steel loading position in front of the furnace. The self-flowing material obtained in step 5) is hoisted into the furnace using a furnace dismantling machine. The furnace is then quickly moved to 92°, and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill the gap.

[0111] 7) Bake immediately after filling, with the total filling and baking time controlled within 8 minutes;

[0112] 8) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the sliding plate slag-blocking mechanism;

[0113] 9) Once the mechanism is installed, converter production can begin.

[0114] 10) The converter tapping spout should be replaced after 218 uses. The drilling time during the replacement process is 6 minutes.

[0115] Comparative Example 2

[0116] 1) Preparation of magnesium-containing waste brick fine powder: Waste magnesium bricks with MgO content of 96.12% are recycled, impurities are removed manually, and then crushed and ball-milled to obtain magnesium-containing waste brick fine powder. The content of the first magnesium-containing waste brick fine powder in the magnesium-containing waste brick fine powder is required to be ≥85wt%, and the particle size of the first magnesium-containing waste brick fine powder is ≤0.074mm.

[0117] 2) Fully premixed matrix fine powder: 30% magnesium-containing waste brick fine powder, 4% silica powder (≤5μm), 1% sintering water-reducing agent sodium tripolyphosphate (≤0.1mm) and 0.2% retarder tartaric acid (≤0.1mm) are added to a premixing device for vigorous premixing for 15 minutes to obtain premixed fine powder;

[0118] 3) Put 1-3 mm of 26% MS90 sintered magnesia, 0.5-1 mm of 14% MS90 sintered magnesia and 0-0.5 mm of 25% MS90 sintered magnesia into a sand mixer and stir for 2 minutes. Then add the premixed fine powder and stir for 5 minutes. Discharge the material into a ton bag to obtain the gap filler.

[0119] 4) At the slag blocking site, first turn on the mixer, hoist the interstitial filler obtained in step 3) into the mixer, add water while mixing, strictly control the amount of water added at a ratio of 13.5wt% (the amount of water added is 13.5wt% of the interstitial filler), mix for 8 minutes, and put the obtained magnesium self-flowing material into the ton bag with a plastic inner liner.

[0120] 5) During the replacement of the tapping outlet, after drilling and fixing the new tapping outlet, the furnace is moved to the scrap steel loading position in front of the furnace. The furnace dismantling machine is used to hoist the self-flowing material obtained in step 4) into the furnace. The furnace is quickly moved to 92° and the self-flowing material immediately flows into the gap between the tapping outlet sleeve and the seat brick to fill the gap.

[0121] 6) Bake immediately after filling, with the total filling and baking time controlled within 8 minutes;

[0122] 7) After baking, move the converter to the front of the furnace, remove the tapping port installation tools, and then install the inner water inlet and slag-blocking mechanism.

[0123] 9) Once the mechanism is installed, converter production can begin.

[0124] 10) The converter tapping spout should be replaced after 206 uses. The drilling time during the replacement process is 6 minutes.

[0125] The interstitial fillers obtained in Examples 1-4 and Comparative Examples 1-2 were tested for their chemical composition (MgO, SiO2), apparent porosity, bulk density, room temperature pressure resistance, and permanent linear shrinkage rate upon heating. The testing methods are as follows:

[0126] (1) The test methods, including sample preparation, shall be carried out in accordance with YB / T 5202.1-2003 Method for preparing specimens of unshaped refractory materials, Part 1: Refractory castables;

[0127] (2) The MgO content in the magnesium self-flowing material was determined by EDTA complexometric titration (13.1) in GB / T 5069-2007 Chemical Analysis Methods for Magnesium-Aluminum Refractory Materials;

[0128] (3) The SiO2 content in the magnesium self-flowing material was determined according to the molybdenum blue spectrophotometric method (8.1) in the chemical analysis methods of magnesium-aluminum refractories in GB / T 5069-2007;

[0129] (4) The apparent porosity and bulk density of magnesia self-flowing material were tested according to the test method for apparent porosity and bulk density of dense refractory castables in YB / T 5200-1993.

[0130] (5) The compressive strength of magnesia self-flowing material at room temperature was tested according to GB / T 5072-2008 Test Method for Compressive Strength of Refractory Materials at Room Temperature;

[0131] (6) The permanent linear change rate of magnesia self-flowing material under heating was tested according to GB / T 5988-2007 Test Method for Permanent Linear Change of Refractory Materials.

[0132] The test results are shown in Table 1:

[0133] Table 1. Performance results of the gap fillers obtained in Examples 1-4 and Comparative Examples 1-2

[0134]

[0135] As can be seen from the test results in Table 1 and the examples and comparative examples, the magnesia self-flowing material for converter slag baffles provided in this disclosure is made from sintered magnesia particles with an MgO content of less than 95wt% and fine powder ground from recycled magnesia-containing waste bricks and spinel-containing waste bricks as the main raw materials, resulting in low cost; moreover, the self-flowing material has a moderate magnesium oxide content, suitable low, medium and high temperature strength, and a maximum compressive strength not exceeding 36.5MPa; Examples 1-4 The permanent linear changes at 1550℃ showed slight expansion, while Comparative Examples 1 and 2 showed shrinkage. The slight expansion indicates that the filler has good integrity at high temperatures and no shrinkage, and its resistance to corrosion and erosion is better than that of the comparative examples. The filled taphole has a high number of uses, showing excellent resistance to corrosion and erosion. The drilling time of the taphole mainly depends on the strength of the filler and the strength of the taphole brick itself. The taphole brick is made of high-grade magnesium carbon material with a room temperature strength of 30-35 MPa, which is similar to the strength of the filler in Examples 1-4. Therefore, the drilling time of Examples 1-4 is 6-8 minutes. The drilling time of Comparative Examples 1-2 is mainly determined by the time required to drill through the taphole (the strength of the magnesium self-flowing material is low, while the strength of the taphole is higher than that of the self-flowing material, making it more difficult to drill through the taphole), which is about 6 minutes. The present invention saves drilling time mainly because it is easier to drill compared with the prior art (non-comparative example), saving drilling time by 10-12 minutes per cycle, which is a considerable advantage; the comparative example mainly affects the erosion resistance and anti-permeability erosion performance of the filler, and affects the service life of the steel tapping outlet.

[0136] The disclosed process is simple, pollution-free, and reduces filling and baking time by 7-10 minutes per cycle. Taking two 210t converters in a steel plant as an example, it can produce an additional 19,152-24,696 tons of steel per year, generating significant economic and social benefits.

[0137] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this disclosure. It should be noted that those skilled in the art can make several improvements and modifications to this disclosure without departing from the principles of this disclosure, and these improvements and modifications also fall within the protection scope of the claims of this disclosure.

[0138] The above description of the disclosed embodiments enables those skilled in the art to make or use this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gap filler for use at the slag-blocking taphole of a converter, prepared by means of the following raw materials by mass percentage: Sintered magnesia 60-70%, magnesium-containing waste brick fine powder 18-26%, spinel-containing waste brick fine powder 6-10%, silica fume 3-5%, sintering water-reducing agent 0.5-1.5%; Based on the total amount of the sintered magnesia, the magnesium-containing waste brick fine powder, the spinel-containing waste brick fine powder, the silica powder, and the sintering water-reducing agent, the content of the retarder is 0.1~0.3%.

2. The gap filler according to claim 1, characterized in that, Based on the total mass of sintered magnesia, the sintered magnesia comprises 35-45% coarse sintered magnesia particles of 1-3 mm, 18-25% medium sintered magnesia particles of 0.5-1 mm, and 34-43% fine sintered magnesia particles of 0-0.5 mm.

3. The gap filler according to claim 1, characterized in that, The magnesium-containing waste brick fine powder contains a first magnesium-containing waste brick fine powder with a content ≥85wt% and a particle size ≤0.074mm; the spinel-containing waste brick fine powder contains a first spinel-containing waste brick fine powder with a content ≥85wt% and a particle size ≤0.074mm; the silica powder contains a first silica powder with a content ≥85wt% and a particle size ≤5μm; the sintering water-reducing agent contains a first sintering water-reducing agent with a content ≥85wt% and a particle size ≤0.1mm; the retarder contains a first retarder with a content ≥85wt% and a particle size ≤0.1mm.

4. The gap filler according to claim 1, characterized in that, The magnesium-containing waste brick fine powder is prepared from waste magnesium bricks with MgO ≥ 95 wt% or waste magnesium chromium bricks with MgO + Cr2O3 ≥ 90 wt%, and / or the spinel-containing waste brick fine powder is prepared from RH-grade magnesium spinel waste bricks.

5. The gap filler according to claim 1 or 2, characterized in that, The sintered magnesia contains 90-95 wt% MgO and has a particle bulk density of 3.18-3.25 g / cm³. 3 .

6. The gap filler according to claim 1, characterized in that, The sintering water-reducing agent includes one or both of sodium tripolyphosphate and sodium hexametaphosphate, and / or the retarder includes one or both of tartaric acid and citric acid.

7. The gap filler according to claim 1, characterized in that, The method for preparing the gap filler includes: After stirring the sintered magnesia, add magnesium-containing waste brick fine powder, spinel-containing waste brick fine powder, silica powder, sintering water-reducing agent and retarder, and stir to obtain a gap filler.

8. A construction method using a gap filler, comprising the following steps: S1. Mix the gap filler with water to obtain a self-flowing material; the gap filler is the gap filler according to any one of claims 1 to 7; S2. Replace the old steel outlet with a new steel outlet, fill the gap between the steel outlet sleeve and the seat brick with the gravity-flow material, and bake the gap after filling; then install the sliding plate slag-blocking mechanism.

9. The construction method according to claim 8, characterized in that, The amount of water added is 13-14 wt% of the interstitial filler.

10. The construction method according to claim 8, characterized in that, The total time for filling and baking is 8-10 minutes.

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