TW202405194A - Fine slag made by refractory material and method of making the same - Google Patents

Abstract

The present invention provides a fine slag made by refractory material and a method of making the same, in which the refractory material can include magnesium oxide as well as is contaminated by molten iron, molten steel and/or steel slag, and the refractory material subjected to a desulfurization step and a cooling step makes a fine slag with a low expansion ratio, a low amount of magnesium oxide but without crystal structure of magnesium oxide. By adding the refractory material to molten iron during the desulfurization step, the refractory material can not only be recycled and reused to make fine slag with high qualities, but also maintain the temperature of the molten iron without heating.

Description

Mineral fine materials obtained from refractory materials and manufacturing methods thereof

The present invention relates to a kind of mineral fine material, in particular to a kind of mineral fine material made from refractory materials and its manufacturing method.

Refractory materials are widely used in metallurgy, chemical industry, petroleum, machinery manufacturing, power and other industrial fields. In the production lines of conventional steelmaking plants, many furnace bodies, equipment and/or pipelines use refractory materials as furnace linings. However, when the above-mentioned furnace body, equipment and/or pipelines reach the end of their service life, the refractory materials need to be removed, resulting in waste refractory materials.

Among the waste refractory materials, the refractory materials that are not contaminated by by-products generated during the steelmaking process (such as molten iron, molten steel and/or furnace ballast) can be remade into refractory materials. However, among refractory materials contaminated by molten iron, molten steel and/or furnace ballast, refractory materials that do not contain magnesium oxide (such as blast furnace runner refractory materials) can be added to cement as aggregates, but they contain oxides. When magnesium refractory materials (such as refractory materials used in converters, iron buckets and liquid steel distributors in the steelmaking process) are added to cement, magnesium oxide will easily hydrate into magnesium hydroxide, causing the cement to expand in volume when exposed to water. It needs to be handled in other ways. Among them, refractory materials with high magnesium oxide content (such as: 80% by weight) can be made into magnesia-alumina carbon bricks, but refractory materials with low magnesia content (such as: less than or equal to 40% by weight) can be made into magnesium-alumina carbon bricks. The quality and efficiency are poor, so they are often disposed of in landfills, which not only costs high but may also cause pollution.

In view of this, a method for manufacturing mineral fine materials is urgently needed to solve the above problems.

Therefore, one aspect of the present invention is to provide a method for manufacturing mineral fine materials. This manufacturing method includes adding refractory materials and desulfurizer to molten iron, and then performing a desulfurization step and a cooling step to obtain mineral fines.

Another aspect of the present invention is to provide a mineral fine material made from refractory materials, which is produced by the above method, wherein the magnesium oxide content of the mineral fine material can be, for example, less than or equal to 0.5% by weight, but the mineral fine material Does not contain magnesium oxide phase.

According to one aspect of the present invention, a method for manufacturing mineral fine materials is provided. First, refractory materials and desulfurization agents are added to the molten iron to perform a desulfurization step at 1300°C to 1550°C to form desulfurization ballast. Based on 100 parts by weight of molten iron, the amount of refractory material may be, for example, 0.5 to 2.0 parts by weight. Next, the desulfurized ballast is subjected to a cooling step to obtain mineral fines.

In one embodiment of the present invention, the method for producing mineral fines may optionally include a grinding step, a magnetic separation step and/or a water washing step after the cooling step. In one embodiment of the present invention, the particle size of the refractory material may be, for example, less than or equal to 70 mm. In one embodiment of the invention, the refractory material contains magnesium oxide (MgO). In one embodiment of the present invention, the refractory material may be contaminated by molten iron, molten steel and/or steel ballast, for example. In one embodiment of the present invention, after the desulfurization step, the temperature drop of the molten iron may be, for example, less than or equal to 30°C. In one embodiment of the present invention, the desulfurizer may include, but is not limited to, calcium oxide-based desulfurizer, magnesium or magnesium-based desulfurizer and/or calcium carbide-based desulfurizer.

According to another aspect of the present invention, a mineral fine material produced using refractory materials is provided, which is produced using the above method. The magnesium oxide content of the mineral fines may, for example, be less than or equal to 0.5% by weight, but the mineral fines do not contain a magnesium oxide phase.

In one embodiment of the present invention, the refractory material may be contaminated by molten iron, molten steel and/or steel ballast, for example. In one embodiment of the present invention, the expansion rate of the mineral fines may be, for example, less than or equal to 5.0%.

The method for producing mineral fine materials of the present invention is to add refractory materials and desulfurizers to molten iron, and then perform a desulfurization step and a cooling step to produce mineral fine materials. By adding refractory materials to the molten iron during the desulfurization step, the refractory materials can not only be recycled and reused to produce high-quality mineral fines, but the temperature of the molten iron can also be maintained without additional heating.

The making and using of embodiments of the invention are discussed in detail below. It is to be appreciated, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are illustrative only and are not intended to limit the scope of the invention.

The "hot iron" mentioned in this article is obtained after the iron ore undergoes a blast furnace ironmaking step. In the blast furnace ironmaking step, raw materials such as coke are added. The resulting hot metal contains high concentrations of sulfur and/or sulfides, thus affecting the The quality of the steel subsequently produced. Therefore, after the blast furnace ironmaking step, the molten iron needs to go through a desulfurization step to reduce the sulfur content in the molten iron and produce desulfurization slag.

Based on the above, the present invention provides a mineral fine material made of refractory material and a manufacturing method thereof. Please refer to FIG. 1 , which is a flow chart of a method 100 for manufacturing mineral fines according to an embodiment of the present invention. First, as shown in step 102 of the method 100, refractory materials and desulfurization agents are added to the molten iron to perform a desulfurization step to form desulfurization ballast.

The "refractory material" described herein can be, for example, an alkaline refractory material that has better resistance to alkaline ballast erosion, wherein the components of the alkaline refractory material include oxides of alkali gold group elements, such as magnesium oxide. Refractory materials can be divided into different grades according to the magnesium oxide content in the refractory materials. In one embodiment, based on 100% by weight of the refractory material, the magnesium oxide content may be, for example, greater than 0 and less than or equal to 5% by weight. In one embodiment, based on 100% by weight of the refractory material, the magnesium oxide content may be, for example, greater than 5% by weight and less than or equal to 20% by weight. In one embodiment, based on 100% by weight of the refractory material, the magnesium oxide content may be, for example, greater than 20% by weight and less than or equal to 40% by weight. In one embodiment, based on 100% by weight of the refractory material, the magnesium oxide content may be, for example, greater than 40% by weight, such as greater than 40% by weight and less than or equal to 100% by weight, such as 60% by weight or 80% by weight. In one embodiment, the above-mentioned refractory materials may be, for example, waste refractory materials, such as refractory materials contaminated by molten iron, molten steel and/or steel ballast.

Before performing the desulfurization step (step 102), the refractory material may optionally undergo a grinding step to obtain refractory material with a smaller particle size. The grinding method is not limited, and may be, for example, crushing and granulation. The particle size of the refractory material is not limited, and may be, for example, less than or equal to 70 mm, so that the refractory material can be more easily melted into a liquid phase molten state during the desulfurization step. In one embodiment, the particle size of the refractory material may be, for example, greater than 0 mm and less than or equal to 10 mm. In one embodiment, the particle size of the refractory material may be, for example, greater than 10% by weight and less than or equal to 30% by weight. In one embodiment, the particle size of the refractory material may be, for example, greater than 30% by weight and less than or equal to 50% by weight. In one embodiment, the particle size of the refractory material may be, for example, greater than 50% by weight and less than or equal to 70% by weight.

Based on 100 parts by weight of molten iron, the amount of refractory material may be, for example, 0.5 to 2.0 parts by weight. If the amount of refractory material used is too low, the efficiency of recycling the refractory material will be poor, resulting in a significant increase in time and/or storage space costs. If the amount of refractory material is too high, the resulting mineral fines may contain too much magnesium oxide, which may cause hydration expansion problems.

The "desulfurizing agent" mentioned in this article refers to an agent that can remove free sulfur and/or sulfide contained in molten iron. The type of desulfurizer is not limited, and can be, for example, calcium oxide-based desulfurizer [such as: fluorite (CaF ₂ ), quicklime (CaO) and/or calcium aluminate (CaO‧Al ₂ O ₃ ) minerals], pure magnesium Or magnesium-based desulfurizer and/or calcium carbide-based desulfurizer [such as calcium carbide (CaC ₂ )], among which pure magnesium or magnesium-based desulfurizer can be selectively used with lime, calcium carbide and/or coke, etc. In one embodiment, the amount of desulfurizer used is not limited. For example, based on 100% by weight of molten iron, the amount of desulfurizer used may be, for example, 0.2% to 0.6% by weight. When the dosage of the desulfurizer is within the above range, the desulfurization step can have better efficiency, and the quality of the produced mineral fines can be improved.

In the aforementioned desulfurization step, desulfurizers and refractory materials are added to the molten iron to reduce the sulfur content of the molten iron and obtain desulfurized slag. After the desulfurization step, the iron-incorporated portion of the refractory material contaminated by molten iron, molten steel and/or steel ballast will be dissolved back into the molten iron, while the remaining portion will be co-melted in the desulfurized ballast. In one embodiment, the desulfurization step can optionally add a silicone removal agent and/or a dephosphorization agent to remove other hindering elements (such as silicon and/or phosphorus) from the molten iron and blend them into the desulfurization furnace. middle. It should be added that the density of molten iron is about 7.4 g/cm ³ to 7.9 g/cm ³ , and the density of desulfurized ballast is about 2.0 g/cm ³ to 3.0 g/cm ³ , so the molten iron undergoes the desulfurization step Afterwards, the desulfurized ballast will float on the surface of the molten iron, which helps to collect the desulfurized ballast. The method of collecting desulfurized ballast is not limited, and it can be carried out, for example, by using a rake.

It is worth noting that the more uniformly the molten iron and the desulfurizer are mixed, the higher the efficiency of the desulfurization step, and the more effectively the sulfur content in the molten iron after the desulfurization step can be reduced. The method of uniformly mixing the molten iron and the desulfurizer is not particularly limited. It may be, for example, stirring and/or maintaining the molten iron at a high temperature (such as greater than or equal to 1150°C) so that the molten iron is in a molten state and has Helps in mixing desulfurizer and molten iron.

The method of the aforementioned stirring treatment is not particularly limited. In one embodiment, the stirring process can be performed, for example, by the Kambara Reactor (KR) method, which uses a cross-shaped stirring head poured with refractory material and baked to generate a vortex in the molten iron to fully mix the molten iron and the desulfurizer. , thereby improving the efficiency of the desulfurization step. In an application example, based on 100% by weight of the molten iron, the sulfur content of the molten iron after being stirred by the Kambara Reactor (KR) method and desulfurized is less than 0.005% by weight.

The aforementioned method of maintaining molten iron at a high temperature is not particularly limited. It can, for example, provide additional heat energy to the molten iron and/or reduce the temperature drop of the molten iron (i.e., the drop in temperature of the molten iron after the desulfurization step is performed, in which the smaller the temperature drop) , the smaller the temperature difference of molten iron). The method of reducing the temperature drop of the molten iron is not particularly limited, and may be, for example, a desulfurization step in a heat preservation device. The heat preservation device may be, for example, a milling barrel, and/or other devices that can effectively preserve molten iron. Secondly, since refractory materials have good thermal insulation effects, adding refractory materials to molten iron can not only reuse the refractory materials to produce mineral fines, but also reduce the temperature drop of the molten iron to ensure that the molten iron is in the desulfurization step. It maintains the molten state during the process and does not require additional heating, which can effectively reduce energy costs. In one embodiment, after the desulfurization step, the temperature drop of the molten iron is less than or equal to 30°C, such as 20°C to 26°C. When the temperature drop of the molten iron is no more than 30°C, the molten iron can be easily maintained in a molten state, which facilitates the mixing of the desulfurizer and the molten iron. It should be added that the smaller the particle size of the refractory material, the faster the melting rate, thereby increasing the efficiency of the desulfurization step.

Next, as shown in steps 104 and 106 of the method 100, a cooling step is performed on the desulfurized ballast to obtain mineral fines. Since the cooling rate does not affect the quality of the mineral fines, the method of the cooling step is not particularly limited. For example, it can be left standing indoors until the desulfurized ballast slowly cools to room temperature to save the energy required for cooling.

In one embodiment, after the cooling step, the obtained mineral fines can optionally undergo a grinding step, a magnetic separation step and/or a water washing step to improve the quality of the obtained mineral fines. The method of the grinding step is not particularly limited. It may be, for example, using a crusher for crushing treatment to obtain mineral fines with a particle size that meets the requirements of the cement plant, such as less than or equal to 8 mm. The method of magnetic separation is not particularly limited. For example, electromagnets can be used to adsorb iron in mineral fines to recover and reuse the iron. The method of water washing is not particularly limited, and may be, for example, rinsing the mineral fines with clean water to clean dust and/or water-soluble impurities attached to the mineral fines.

The mineral fines obtained by the above method have a lower expansion rate and a lower magnesium oxide content, and its crystalline phase does not contain a magnesium oxide phase. The expansion rate of the obtained mineral fines may be, for example, less than or equal to 5.0%, and the magnesium oxide content may be, for example, less than or equal to 0.5% by weight, based on 100% by weight of the mineral fines.

In some application examples, the manufacturing method of the present invention can utilize refractory materials with different magnesium oxide contents and different particle size ranges (not larger than 70 mm) to produce mineral fines. The expansion rate of the produced mineral fines can be no more than 5.0%, and the magnesium oxide content can be no more than 0.5% by weight, thereby meeting the requirements for reuse.

Several examples are used below to illustrate the application of the present invention, but they are not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. polish. Pre-treatment of refractory materials

Based on the magnesium oxide content, waste refractory materials can be divided into first-level refractory materials, second-level refractory materials, third-level refractory materials and fourth-level refractory materials. Among them, based on the total weight of the refractory materials, the magnesium oxide content of the first-level refractory materials is less than or equal to 5% by weight, and the magnesium oxide content of the second-level refractory materials is greater than 5% by weight and less than or equal to 20% by weight. The magnesium oxide content of the third-level refractory materials is greater than 20% by weight and less than or equal to 40% by weight, and the magnesium oxide content of the fourth-level refractory materials is greater than 40% by weight.

Use a crushing and grinding machine (model FCJS-3105, Fengchuan Machinery) to grind various levels of refractory materials, and use 70 mm, 50 mm, 30 mm and 10 mm sieves to obtain different particle size ranges of waste refractory materials. Preparation Example 1

For every 10 tons of molten iron, add 50±45 kg of lime and 4.5±0.5 kg of fluorite and 100 kg of first-level refractory material (magnesium oxide) with a particle size ranging from greater than 0 mm to less than or equal to 10 mm. The content is less than 5% by weight) is added to the milling barrel, and the desulfurization step is performed by the KR method, wherein the milling barrel contains 10 tons of molten iron. Then, use a raking device to collect the desulfurized slag floating on the molten iron into a slag bucket. After the desulfurized ballast is cooled, the desulfurized ballast is subjected to grinding steps, magnetic separation steps and water washing steps to obtain mineral fines. Preparation Example 2 to Preparation Example 4

The preparation method of the mineral fines of Preparation Examples 2 to 4 is the same as that of Preparation Example 1. The difference is that the particle size range of the refractory material used in Preparation Example 2 is from greater than 10 mm to less than or equal to 30 mm, and the refractory material used in Preparation Example 3 The particle size range of the material is greater than 30 mm to less than or equal to 50 mm, and the particle size range of the refractory material used in Preparation Example 4 is greater than 50 mm to less than or equal to 70 mm. Preparation Example 5 to Preparation Example 7

The preparation methods of Preparation Examples 5 to 7 are the same as Preparation Example 3. The difference is that Preparation Example 5 uses second-level refractory materials (magnesium oxide content is greater than 5% by weight and less than or equal to 20% by weight), and Preparation Example 6 uses The third level refractory material (the magnesium oxide content is greater than 20% by weight and less than or equal to 40% by weight), and Preparation Example 7 uses the fourth level refractory material (the magnesium oxide content is greater than 40% by weight). Preparation Comparative Example

The preparation method of the mineral fines in the comparative example is the same as that in the preparation example. The difference is that no refractory material is added during the desulfurization step in the preparation of the comparative example. In other words, in the preparation of the comparative example, only the desulfurizer was added to the molten iron to perform the desulfurization step.

Regarding the magnesium oxide content, particle size range, and evaluation results (temperature drop of molten iron, expansion rate of the produced mineral fines, magnesium oxide content, and crystalline phase of the refractory materials used in Preparation Examples 1 to 7 and Comparative Examples) Whether it has a magnesium oxide phase) and the definition of high quality of mineral fines are recorded in Table 1 and will not be repeated here. Evaluation method 1. Temperature drop of molten iron

Before performing the desulfurization step, the temperature of the molten iron (T _i ) is measured using an infrared thermometer. After the desulfurization step is carried out and the desulfurization slag is removed, the temperature of the molten iron (T _f ) is measured again using an infrared thermometer. Calculate the difference between _Ti and T _f to obtain the temperature drop of molten iron.

As shown in Table 1, compared with the preparation comparative example, preparation examples 1 to 7 added refractory materials in the desulfurization step, and the temperature drop of the molten iron was smaller, ranging from 21.4°C to 25.2°C, confirming that Waste refractory materials can reduce the temperature drop of molten iron before and after the desulfurization step.

It is worth noting that when the particle size range of the refractory material is less than or equal to 30 mm (Preparation Example 1 and Preparation Example 2), the temperature drop of the molten iron desulfurization step is 21.4°C to 22.2°C, and when the refractory material The particle size range is greater than 30 mm to less than or equal to 70 mm (Preparation Example 3 to Preparation Example 7). The temperature drop in the molten iron desulfurization step is 23.7°C to 25.2°C, indicating that the smaller the particle size of the refractory material, the lower the iron content. The temperature drop in the water desulfurization step tends to be smaller. 2. Expansion rate of mineral fines

The expansion rate of the mineral fines in Preparation Examples 1 to 7 and Preparation Comparative Examples was measured using the "Portland Cement Hot Pressure Expansion Test Method" of National Standards of the Republic of China (CNS) No. 1258. .

As shown in Table 1, the expansion rates of the mineral fines in Preparation Examples 1 to 7 are all less than 5.0%, confirming that adding a refractory particle size less than or equal to 70 mm, regardless of the magnesium oxide content, the expansion of the mineral fines obtained The rate can meet the evaluation standards of mineral fine materials. In the preparation comparative example, since no refractory material was added in the desulfurization step, the mineral fines produced by utilizing the desulfurization slag formed did not contain magnesium oxide. Therefore, its expansion rate is also less than 5.0%.

It is worth noting that, from the evaluation results of Preparation Example 3, Preparation Example 5 to Preparation Example 7, it can be seen that as the magnesium oxide content of the refractory material increases, although the expansion rate of the mineral fines tends to increase, its expansion rate is still It is less than 5.0%, so the mineral fines obtained are still high-quality mineral fines. 3. Magnesium oxide content of mineral fines

The magnesium oxide content of the mineral fines of Preparation Examples 1 to 7 and Preparation Comparative Example was detected using the "Hydraulic Cement Chemical Analysis Method" of CNS 1078.

As shown in Table 1, based on 100% by weight of the mineral fines, the magnesium oxide content of the mineral fines in Preparation Examples 1 to 7 ranges from 0.38 to 0.48% by weight. It is worth noting that from the evaluation results of Preparation Example 1 to Preparation Example 4, it can be seen that the smaller the particle size range of the refractory material, the smaller the magnesium oxide content of the prepared mineral fines, and from Preparation Example 3, Preparation Example 5 to The evaluation results of Preparation Example 7 show that the higher the magnesium oxide content of the refractory material, the higher the magnesium oxide content of the produced mineral fines, but they are still high-quality mineral fines. 4. Magnesium oxide phase of mineral fines

X-ray diffractometer (XRD) was used to analyze whether the crystalline phase of the mineral fines in Preparation Examples 1 to 7 and Preparation Comparative Example contained a magnesium oxide phase. As shown in Table 1, the mineral fines of Preparation Examples 1 to 7 do not contain magnesium oxide phase, which proves that the desulfurization step is performed using refractory materials with a particle size range of less than or equal to 70 mm, regardless of the magnesium oxide content of the refractory materials. The mineral fines produced are all high quality mineral fines.

Table 1

As can be seen from the above, the advantage of the mineral fine materials produced by using refractory materials and the manufacturing method of the present invention is that after adding the refractory materials and desulfurization agent to the molten iron, the desulfurization step and the cooling step are performed. Not only can the low expansion rate be obtained , high-quality mineral fines with low magnesium oxide content, and the crystalline phase does not contain magnesium oxide, and during the desulfurization step, the temperature drop of the molten iron can be reduced without additional heating, which can help improve The efficiency of the molten iron desulfurization step. According to this, general waste refractory materials can be effectively reused, thereby improving the efficiency of the desulfurization step and effectively reducing the cost of waste disposal.

Although the present invention has been disclosed above in terms of several specific embodiments, various modifications, changes and substitutions may be made to the foregoing disclosure, and it should be understood that, in some cases, without departing from the spirit and scope of the present invention, Certain features of embodiments of the invention may be employed without corresponding use of other features. Therefore, the spirit and scope of the claims of the present invention should not be limited to the above illustrated embodiments.

100:Method 102,104,106: Steps

In order to make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the detailed description of the accompanying drawings is as follows: [Fig. 1] is a flow chart illustrating a method for producing mineral fine materials according to an embodiment of the present invention.

100:Method

102,104,106: Steps

Claims (10)

A method for manufacturing mineral fine materials, including: A refractory material and a desulfurization agent are added to the molten iron to perform a desulfurization step at 1300°C to 1550°C to form a desulfurization slag, wherein the amount of the refractory material is based on 100 parts by weight of the molten iron. is 0.5 parts by weight to 2.0 parts by weight; and The desulfurized ballast is subjected to a cooling step to obtain the mineral fines. The manufacturing method of mineral fines as described in claim 1 further includes performing a grinding step, a magnetic separation step and/or a water washing step after the cooling step. The manufacturing method of mineral fines as described in claim 1, wherein a particle size of the refractory material is less than or equal to 70 mm. The method for producing mineral fines as claimed in claim 1, wherein the refractory material contains magnesium oxide (MgO). The manufacturing method of mineral fines as described in claim 1, wherein the refractory material is contaminated by molten iron, molten steel and/or steel ballast. The manufacturing method of mineral fines as described in claim 1, wherein after the desulfurization step, a temperature drop of the molten iron is less than or equal to 30°C. The method for producing mineral fines as claimed in claim 1, wherein the desulfurizer includes calcium oxide-based desulfurizer, magnesium or magnesium-based desulfurizer and/or calcium carbide-based desulfurizer. A kind of mineral fine material made from refractory materials, which is made by using the manufacturing method of mineral fine material as described in any one of claim 1 to claim 7, wherein a content of the magnesium oxide in the mineral fine material is Less than or equal to 0.5% by weight, but the mineral fines do not contain magnesium oxide phase. The mineral fines produced by using refractory materials as described in claim 8, wherein the refractory materials are contaminated by molten iron, molten steel and/or steel ballast. The mineral fine material made from refractory materials as described in claim 8, wherein the expansion rate of the mineral fine material is less than or equal to 5.0%.

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