TWI708850B - Unstable reduction ballast recycling method - Google Patents

Abstract

The present invention provides a resource recycling method for unstabilized reduced ballast, which comprises: unstabilized reduced ballast, powder material, and water are all prepared, wherein the weight ratio of unstabilized reduced ballast to powder material is 1: 1 to 1:0.2; mixing the unstabilized reducing ballast, powder material, and water into a mixture, wherein the ratio of the molar number of calcium to the molar number of silicon and aluminum is 0.5 to 2.5; and the mixture At least one specimen is formed, and the at least one specimen undergoes a curing reaction at a vapor pressure of 4.855 kgf/cm ² to 40.55 kgf/cm ² and a curing temperature of 150° C. to 250° C. to obtain at least one cured product. With the above method, the unstabilized reducing ballast that is difficult to use can be converted into economically valuable materials in a short time, which improves the degree of decontamination and the way of use, thereby reducing the cost of steelmaking.

Description

Unstable reduction ballast recycling method

The invention relates to an electric arc furnace ballast treatment method. Specifically, the present invention relates to a resource treatment method of electric arc furnace ballast.

The iron and steel industry is a very important basic industry in my country, and its related industries are very extensive. The iron and steel plants produce more than one million tons of slag each year. If they are not used rationally, simply storing the slag will cause storage space problems. It will also cause environmental pollution.

The smelting process of electric arc furnace steelmaking is divided into three stages according to its chemical reaction, namely the melting period, the oxidation period and the reduction period. Electric arc furnace steelmaking ballast is the molten ballast discharged from the steelmaking process, and can be divided into oxidation ballast and reduction ballast according to the age of the ballast. Oxidized ballast has a high content of iron, a hard texture and a high specific gravity. It is a dark brown block with stable physical and chemical properties. The unstabilized reduced ballast contains less iron but more calcium oxide and magnesium oxide, which is gray-brown powder or lump. Since the reduced ballast contains free lime (f-CaO), it swells and disintegrates easily when exposed to water. Therefore, in addition to the raw material used in the cement process, the reduced ballast does not have an effective way to remove due to poor volume stability. They can only be stacked, which leads to waste of land costs.

Domestic public works and construction industries have a huge demand for concrete pellets every year. Among them, trench pipe projects such as sewage sewers, water pipes, natural gas pipelines and other projects require a large amount of Controlled Low-Strength Material (CLSM for short) ), the pellets in CLSM can be recycled pellets and industrial by-products instead of natural pellets. Due to the huge amount of reduced ballast produced by electric arc furnace steelmaking plants each year, under the condition that Taiwan’s natural resources are very limited, if the above-mentioned reduced ballast can be efficiently used to replace precious natural resources, it will ensure the eternal resources Continue to exist. Recently, some companies have first stabilized the unstabilized reduced ballast, and then used the stabilized reduced ballast to make CLSM. However, if a large amount of unstabilized reducing ballast can be directly converted into CLSM, it will not only save the time spent in a procedure, but also save the reagents used in this step. Therefore, there is a great need to develop a method that can directly use the unstabilized reducing ballast and convert a large amount of unstabilized reducing ballast into use-worthy renewable resources in a short time.

To solve the above problems, the purpose of the present invention is to develop a method that can directly convert a large amount of unstabilized reducing ballast into renewable resources in a short time.

In order to achieve the foregoing objective, the present invention provides a resource recycling method of unstabilized reduced ballast, which includes the following steps: (A) material preparation step: complete unstabilized reduced ballast, powder materials, and water, wherein the unsettled reducing ballast The reduced ballast includes 30% to 60% by weight of calcium oxide and 3% to 10% by weight of magnesium oxide, and the powder material includes silicon oxide powder, aluminum oxide powder or a combination thereof, and wherein the The weight ratio of stabilized reduced ballast to the powder material is 1:1 to 1:0.2, and the ratio of water to the total weight of the unstabilized reduced ballast and the powder material is greater than or equal to 0.20 And less than or equal to 0.65; (B) mixing step: mixing the unstabilized reduced ballast, the powder material, and the water into a mixture, wherein in the mixture, the number of moles of calcium is relative to that of silicon and aluminum. The ratio of the molar number of the other is greater than or equal to 0.5 and less than or equal to 2.5; and (C) curing step: first form the mixture into at least one test body, and the at least one test body is between 4.855 kgf/cm ² and 40.55 kgf/ The curing reaction is carried out under a pressure of cm ² and 150°C to 250°C to obtain at least one cured product.

By using the above method, a large amount of unstabilized reduced ballast can be directly converted into a usable solidified material in a short time, thereby reducing the waste of land costs and increasing the use of unstabilized reducing ballast.

According to the present invention, in the mixture, the ratio of the molar number of calcium to the molar number of silicon and aluminum is preferably greater than or equal to 0.5 and less than or equal to 2, more preferably greater than or equal to 0.5, and It is less than or equal to 1.5, and more preferably greater than or equal to 0.5 and less than or equal to 1.2, whereby the cured product can be formed in the most economical manner.

According to the present invention, the obtained cured product contains tobermorite. The cured product can further produce different specifications of cement products such as bricks, tiles, concrete slabs, etc., or be used as controlled low-strength materials and non-structural concrete pellets.

According to the present invention, the unstabilized reducing ballast includes 30 wt% to 60 wt% of calcium oxide, 3 wt% to 10 wt% of magnesium oxide, and 34 wt% to 60 wt% of iron oxide, manganese oxide, etc. substance. Wherein, the unstabilized reducing ballast preferably contains 40 wt% to 60 wt% calcium oxide, more preferably 45 wt% to 60 wt% calcium oxide, and still more preferably 50 wt% to 60 wt% The percentage of calcium oxide.

According to the present invention, the weight ratio of the unstabilized reducing ballast to the powder material may be 1:0.7 to 1:0.2, 1:0.6 to 1:0.2, or 1:0.5 to 1:0.2.

According to the present invention, the amount of water used in the method only needs 20% of the total weight of the unstabilized reduced ballast and the powder material. Excessive water does not affect the curing reaction. Because the excess water will vaporize into water vapor under high pressure.

According to the present invention, in the curing step, the temperature can be 150°C to 240°C, 150°C to 230°C, or 150°C to 220°C.

According to the present invention, in the curing step, the pressure may be 4.855 kgf/cm ² to 34.13 kgf/cm ² , 4.855 kgf/cm ² to 34.13 kgf/cm ² , or 4.855 kgf/cm ² to 23.66 kgf/cm ² .

According to the present invention, the D90 particle size of the unstabilized reducing ballast is less than or equal to 96 microns. In one embodiment, the median particle size (D50) of the unstabilized reduced ballast is less than or equal to 96 microns. In one embodiment, the median particle size of the unstabilized reducing ballast is greater than or equal to 45 microns and less than or equal to 96 microns; preferably, the median particle size of the unstabilized reducing ballast is greater than or equal to 45 Micron and less than or equal to 80 microns. According to the present invention, the unstabilized reduced ballast can be subjected to dry grinding or wet grinding. In one implementation aspect, the unstabilized reducing ballast can be wet-milled using condensed water generated by the autoclave or hot water from other sources during the wet grinding process. In addition to reusing water resources, heat Water wet milling also helps to accelerate the reaction during the curing step.

According to the present invention, the powder material can be fly ash powder, coal bottom ash powder, blast furnace stone powder, waste glass powder or a combination thereof. The fly ash powder is purchased from the coal-burning by-product of the Taichung Thermal Power Plant. It can be Class F fly ash powder, Class N fly ash powder or Class C fly ash powder. Coal-fired bottom ash powder is also purchased from the coal-fired by-products of the Taichung Thermal Power Plant. The blast furnace stone powder was purchased from China United Resources Co., Ltd. The blast furnace stone powder is a by-product "water quenched blast furnace ballast" in the ironmaking process of China Iron and Steel Co., Ltd. after grinding. It can use grade 80 blast furnace stone powder, 100 Grade blast furnace stone powder or 120 grade blast furnace stone powder. Waste glass comes from people's livelihood waste glass (such as beer bottles) or industrial waste glass (such as panels). Among them, the crystalline mineral composition in fly ash powder or coal bottom ash powder includes mullite (3Al ₂ O ₃ •2SiO ₂ ), quartz (SiO ₂ ), magnetite (Fe ₃ O ₄ ), gypsum (CaSO ₄₎ ), tricalcium aluminate (3CaO•Al ₂ O ₃ ), yellow feldspar (Ca ₂ Al ₂ SiO ₇ ), periclase (MgO), lime (CaO). The blast furnace stone powder may include SiO ₂ , Al ₂ O ₃ , CaO, and MgO bonded together to form a structure of CaO•SiO ₂ •Al ₂ O ₃ . The waste glass powder may contain structures such as CaO•SiO ₂ •Na ₂ O, CaO•SiO ₂ •K ₂ O, etc.

According to the present invention, the silicon oxide powder includes silicon dioxide (SiO ₂ ) powder; in another embodiment, the aluminum oxide powder includes aluminum oxide (Al ₂ O ₃ ) powder.

In one embodiment, based on the total weight of the entire powder material, the powder material includes 65 to 75 weight percent of silica, 15 to 25 weight percent of aluminum oxide, and 5 to 20 weight percent of the remaining substances. In another embodiment, based on the total weight of the entire powder material, the powder material includes 55 wt% to 65 wt% silica, 17 wt% to 25 wt% aluminum oxide, and 14 weight percent to 22 weight percent of the remaining substances. In yet another embodiment, based on the total weight of the entire powder material, the powder material includes 60 wt% to 70 wt% silica, 15 wt% to 25 wt% aluminum oxide, And 5 weight percent to 15 weight percent of the remaining substances. In one embodiment, based on the total weight of the entire powder material, the powder material includes 45 wt% to 60 wt% silica, 15 wt% to 30 wt% aluminum oxide, and 15 Weight percent to 40 weight percent of the remaining substances.

In one embodiment, the powder material can be dry milled or wet milled. In one embodiment, in the wet grinding process of powder materials, the condensed water generated by the autoclave or hot water from other sources can be used for wet grinding. In addition to reusing water resources, hot water is used for powdering. Bulk material grinding helps to accelerate the curing reaction during the curing step. According to the present invention, in order to make the powder material fully react, the D90 particle size of the powder material is less than or equal to 96 microns. In another embodiment, the median particle size (D50) of the powder material is less than or equal to 96 microns. In one embodiment, the median particle size of the powder material is greater than or equal to 45 microns and less than or equal to 96 microns.

According to the present invention, the curing step may further include a granulation step or a molding step of the mixture, and then a curing reaction is performed at a high temperature saturated vapor pressure to form a cured product. According to the present invention, the granulation step includes preparing the mixture obtained in the mixing step through an extrusion granulation machine to prepare at least one test body that can be spherical or cylindrical, and then placing the at least one test body in an autoclave for curing The reaction is performed to increase the compressive strength, and then the at least one test body is taken out from the autoclave to obtain at least one cured product. According to the present invention, the molding step may include pouring the mixture obtained in the mixing step into at least one mold, then placing the at least one mold in an autoclave for curing reaction to increase compressive strength, and then self-steaming each mold The autoclave is taken out and demoulded to obtain at least one cured product. According to the present invention, it is also possible to first use a high-pressure molding brick-making machine to prepare at least one brick from the mixture obtained in the mixing step, and then place the at least one brick in an autoclave for curing reaction to increase the compressive strength, and then Then take out each brick from the autoclave to obtain at least one cured product.

According to the present invention, the time of the curing step can be 2 hours to 8 hours, 3 hours to 7 hours, or 3 hours to 6 hours, all of which can directly convert a large amount of unstabilized reducing ballast into usable The cured product.

According to the present invention, the method can produce a compressive strength of 20 kgf/cm ² to 300 kgf/cm ² , a compressive strength of 90 kgf/cm ² to 250 kgf/cm ² , or a compressive strength of 100 kgf/cm ² to 240 kgf/cm ² cured product.

In the following, several examples will be used to illustrate the method of recycling the unstabilized reduction ballast of the present invention. Those familiar with this technique can easily understand the advantages and effects of the present invention through the content of this specification. Various modifications and changes are made without departing from the spirit of the present invention to implement or apply the content of the present invention.

Example 1 to 5 : Cured

The cured products of Examples 1 to 5 were prepared by the following manufacturing method.

First of all, according to Table 1 below, complete unstabilized reduced ballast (D90 particle size less than or equal to 96 microns), fly ash (D90 particle size less than or equal to 96 microns), and water.

Next, the unstabilized reduced ballast, fly ash, and water are mixed to obtain a mixture. The unstabilized reduced ballast includes calcium oxide (CaO), magnesium oxide, iron oxide, manganese oxide, etc. The content of calcium oxide is measured by an X-ray fluorescence analyzer (brand: Bruker, model: CTX 800); Ash contains silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), iron oxide, magnesium oxide, potassium oxide, sodium oxide, etc. The content of silicon dioxide and aluminum oxide are also determined by the above X-ray fluorescence analyzer measurement. After calculating the weight of calcium oxide, silicon dioxide, and aluminum oxide, divide the weight of calcium oxide, silicon dioxide, and aluminum oxide by their respective molecular weights to calculate calcium oxide, silicon dioxide, and aluminum oxide. And the number of moles of aluminum oxide, and the number of moles of calcium in the mixture, the number of moles of silicon, and the number of moles of aluminum are obtained from this, and then the number of moles of calcium in the mixture divided by silicon The ratio to the sum of the moles of aluminum (Ca/(Si+Al)).

Then, the mixture was stirred uniformly and poured into several molds with a volume of 50 mm (mm) * 50 mm * 50 mm. Then, each mold was put into the autoclave and steam was continuously injected until the autoclave reached The curing temperature and saturated vapor pressure in Table 1 below are followed by curing reaction for several hours, followed by pressure reduction and temperature reduction, and the cured products of Examples 1 to 5 are taken out from the autoclave.

Test example 1 : Compressive strength test

According to the CNS 1010 test method, the cured products of Examples 1 to 5 were applied to a universal material testing machine (model: H-300, brand: Hongda Instruments Co., Ltd.), with a load of 500 kg per minute (500 kgf/min) Perform a uniaxial load test for the pressing speed of ), record the maximum value after the cured product is destroyed, and divide it by the force area to obtain the compressive strength of each cured product, as shown in Table 1 below. Table 1: The weights of unstabilized reduced ballast, fly ash, and water, curing reaction conditions, and compressive strength of the cured products of Examples 1 to 5. Example 1 Example 2 Example 3 Example 4 Example 5 Unsettled reducing ballast (g) 1000 1000 1000 1000 1000 Fly ash weight (g) 1000 1000 510 290 200 Water weight (g) 460 700 347 297 420 CaO content (%) 45 55 45 45 35 CaO weight (g) 450 550 450 450 350 SiO ₂ content (%) 70 70 70 70 70 SiO ₂ weight (g) 700 700 357 203 140 Al ₂ O ₃ content (%) 20 20 20 20 20 Al ₂ O ₃ weight (g) 200 200 102 58 40 Ca molar number 8.04 9.82 8.04 8.04 6.25 Si mole number 11.67 11.67 5.95 3.38 2.33 Al molar number 3.92 3.92 2 1.14 0.78 Ca/(Si+Al) 0.52 0.63 1.01 1.78 2.00 Saturated vapor pressure (kgf/cm ² ) 12.8 12.8 4.86 4.86 19.55 Curing temperature (°C) 190 190 150 150 210 Curing time (hr) 3 6 3 6 3 Compressive strength (kgf/cm ² ) 153 237 114 105 130

Discussion of experimental results

As shown in Table 1 above, using the method for recycling unstabilized reduced ballast of the present invention, as long as the weight ratio of unstabilized reduced ballast to powder material is controlled at 1:1 to 1:0.2, water is The ratio of the total weight of the stabilized reduced ballast and the powder material is controlled to be greater than or equal to 0.20 and less than or equal to 0.65, and the ratio of the number of moles of calcium in the mixture to the number of moles of silicon and aluminum Control in the range of 0.5 to 2.5, and the curing reaction will be carried out at a saturated vapor pressure of 4.855 kgf/cm ² to 40.55 kgf/cm ² and a curing temperature of 150°C to 250°C, all of which can be obtained in a short time A cured product with a compressive strength of 20 kgf/cm ² to 300 kgf/cm ² . The cured material with the above-mentioned compressive strength is a material with economic value. It can be used in large quantities in CLSM materials and non-structural concrete materials. This increases the use of unstabilized reduced ballast and reduces the need for stacking unstable reduced ballast , Thereby reducing the cost of steelmaking.

It can be seen from Examples 1 to 5 that using the method of the present invention, as long as the ratio of the molar number of calcium in the mixture to the molar number of silicon and aluminum is controlled within the range of 0.5 to 2.00, it can be within 3 hours. A cured product with a compressive strength of 100 kgf/cm ² to 250 kgf/cm ² can be obtained within 6 hours.

First look at Implementation 1 and Example 2. Under the same saturated vapor pressure and curing temperature, Ca/(Si+Al) is 0.52 and the curing time is 3 hours (Example 1), the compressive strength is 153 kgf. /cm ² of the cured product, and for Example 2 where Ca/(Si+Al) is 0.63, the curing time is further extended to 6 hours, and the compressive strength exceeds 200 kgf/cm ² , even close to 250 kgf /cm ² of cured product. It can be seen from the above experimental results that when Ca/(Si+Al) is equivalent and under the same curing reaction conditions, increasing the curing time will help increase the compressive strength of the cured product.

Considering Example 3 and Example 4, under the same saturated vapor pressure and curing temperature, the compressive strength of the cured product with Ca/(Si+Al) of 1.01 (Example 3) is 114 kgf/cm ² , which A cured product with a compressive strength of 105 kgf/cm ² higher than Ca/(Si+Al) of 1.78 (Example 4). The above implementation results indicate that when the ratio of Ca/(Si+Al) is lower, it helps to increase the compressive strength of the cured product.

Looking at Example 5 again, when Ca/(Si+Al) is 2, it means that under the condition of using a large amount of unstabilized reducing ballast, at a curing temperature of 210°C and a saturated vapor pressure of 19.55 kgf/cm ² Carrying out the curing reaction for 3 hours can quickly obtain a cured product with a compressive strength of 130 kgf/cm ² .

Based on the above experimental results, using the method of the present invention, a large amount of unstabilized reduced ballast can be converted into a renewable resource with a use path in a short time, which can be used in large quantities in CLSM materials and non-structural concrete materials, thereby increasing Use of unstabilized reducing ballast and reducing the processing cost of unstabilized reducing ballast.

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Claims (8)

An unstabilized reduction ballast recycling method comprising the following steps: (A) material preparation step: complete unstabilized reduction ballast, powder materials, and water, wherein the unstabilized reduction ballast contains 30 weight percent Up to 60% by weight of calcium oxide and 3% to 10% by weight of magnesium oxide, and the powder material includes silicon oxide powder, aluminum oxide powder or a combination thereof, based on the total weight of the entire powder material, The powder material contains 45 weight percent to 75 weight percent silicon dioxide and 15 weight percent to 25 weight percent aluminum oxide, and the weight ratio of the unstabilized reduced ballast to the powder material is 1: 1 to 1:0.2, and the ratio of water to the total weight of the unstabilized reduced ballast and the powder material is greater than or equal to 0.20 and less than or equal to 0.65; (B) mixing step: the unsettled The reduced ballast, the powder material, and the water are mixed into a mixture, wherein in the mixture, the ratio of the molar number of calcium to the molar number of silicon and aluminum is greater than or equal to 0.5 and less than or equal to 2.0; and (C) curing step: first the mixture is formed into at least one test body, and the at least one test body undergoes a curing reaction at a pressure of 4.855kgf/cm ² to 40.55kgf/cm ^{2 and} a temperature of 150°C to 250°C to At least one cured product is obtained. The method for recycling unstabilized reduced ballast according to claim 1, wherein the ratio of the molar number of calcium to the molar number of silicon and aluminum in the mixture is greater than or equal to 0.5 and less than or equal to 1.5. The method for recycling unstabilized reduced ballast as described in claim 1, wherein the median particle size of the unstabilized reduced ballast is less than or equal to 96 microns. The method for recycling unstabilized reduced ballast according to claim 1, wherein the median particle size of the powder material is less than or equal to 96 microns. The method for recycling unstabilized reduced ballast according to claim 4, wherein the powder material is fly ash powder, coal bottom ash powder, blast furnace stone powder, waste glass powder or a combination thereof. The method for recycling unstabilized reduced ballast according to claim 4, wherein the curing step takes 2 hours to 8 hours. The method for recycling unstabilized reduced ballast according to claim 6, wherein the compressive strength of each of the at least one cured product is 20kgf/cm ² to 300kgf/cm ² . The method for recycling unstabilized reduced ballast according to any one of claims 1 to 7, wherein the curing step comprises: (c1) first filling the mixture in at least one mold, and placing the mixture in the at least one mold. The at least one test body is formed in a mold; (c2) the at least one test body undergoes a curing reaction at a pressure of 4.855 kgf/cm ² to 40.55 kgf/cm ^{2 and} a temperature of 150° C. to 250° C.; and (c3) demolding, To obtain the at least one cured product.