Steel slag pavement brick and preparation method thereof

Abstract

The present application relates to the technical field of building materials, in particular to a steel tailing pavement brick and a preparation method thereof.According to the weight percentage, the raw material composition of the steel tailing pavement brick comprises: steel tailing 60-80%, silicon-aluminum phase material 5-10%, iron tailing 0-20%, and cementing material 10-20%.The steel tailing pavement brick of the present application can realize the bulk utilization of solid waste materials such as steel tailing, and can overcome the disadvantage of poor volume stability, and is a kind of green masonry material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a steel slag road brick and a preparation method thereof. BACKGROUND

[0002] Steel slag is an industrial solid waste with silicate and ferrite as main components, which is formed by the slagging agent added in the converter, hearth or electric furnace during steelmaking and the impurities and furnace lining in the molten steel. Due to the influence of many factors such as furnace charge, steel grade and operation method, the composition of steel slag fluctuates greatly. Moreover, there is a high content of free calcium oxide f-CaO and free magnesium oxide f-MgO in the steel slag, which is extremely easy to cause digestion, thereby causing volume expansion and forcing engineering damage. These influencing factors greatly limit the bulk utilization of steel slag in building materials.

[0003] In fact, not all free calcium oxide and free magnesium oxide will cause the problem of poor volume stability. For example, there are two types of free calcium oxide in steel slag, one is f-CaO with iron oxide (FeO) solid solution, and the other is f-CaO produced by the thermal decomposition of tricalcium silicate. The former has a dense structure and a very slow hydration rate; the latter can be hydrated at a certain temperature and high humidity, thereby causing poor volume stability. Therefore, targeted inhibition of free calcium oxide and free magnesium oxide to eliminate the risk of volume expansion is an effective way to realize the bulk utilization of steel slag in building materials. Based on this, the present application provides a steel slag road brick with excellent volume stability and a preparation method thereof. SUMMARY

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a steel slag road brick and a preparation method thereof, which solves the technical problem of poor volume stability of the existing steel slag, which causes expansion and damage to the engineering project.

[0005] In order to achieve the above-mentioned purpose, the main technical solutions adopted by the present application include:

[0006] On the one hand, the present application provides a steel slag road brick, according to the weight percentage, the raw material composition of the steel slag road brick is: steel slag 60% to 80%, silico-alumina phase material 5% to 10%, iron tailings 0% to 20% and cementitious material 10% to 20%.

[0007] Further, the steel slag is the waste slag discharged during steelmaking, which is divided into converter slag, hearth slag and electric furnace slag according to the furnace type, and the particle sizes of the converter slag, hearth slag and electric furnace slag are 0 to 2.36 mm, 2.36 mm to 4.75 mm and 4.75 to 9.5 mm, respectively.

[0008] Further, the silico-alumina phase material comprises one or more of slag, fly ash, and kaolin, and the silico-alumina phase material has a content of silicon dioxide greater than 35% and a content of aluminum oxide greater than 10% by weight percentage; and the silico-alumina phase material has a particle size less than 75 μm.

[0009] Further, the iron tailings are waste after beneficiation, and the iron tailings have a content of silicon dioxide greater than 65% by weight percentage and a particle size less than 75 μm.

[0010] Further, the cementitious material is composed of cement, sodium metasilicate, and sodium aluminate, and the cement accounts for 97%, the sodium metasilicate accounts for 2.8%, and the sodium aluminate accounts for 0.2% by weight percentage.

[0011] In another aspect, the application provides a preparation method of the steel tailings pavement brick, comprising the following steps:

[0012] (1) soaking the steel tailings in desulfurization wastewater for a certain time, and drying the steel tailings after being taken out;

[0013] (2) mixing the dried steel tailings, the silico-alumina phase material, the iron tailings, and the cementitious material according to a certain proportion;

[0014] (3) adding a certain amount of water to stir to form a plastic body and to press into a blank;

[0015] (4) finally obtaining the steel tailings pavement brick after steam curing for a certain time.

[0016] Further, the cations in the desulfurization wastewater in the step (1) are sodium, calcium, and magnesium, and the anions are sulfate ions and chloride ions; the soaking time is 12 hours to 48 hours; and the drying conditions are a drying temperature of 40 to 60 ℃ and a drying time of 2 to 4 hours.

[0017] Further, the proportions of the steel tailings, the silico-alumina phase material, the iron tailings, and the cementitious material in the step (2) are 60% to 80%, 5% to 10%, 0% to 20%, and 10% to 20% by weight percentage, respectively.

[0018] Further, the amount of the water in the step (3) is 25% to 45% of the mass of the cementitious material.

[0019] Further, the conditions of the steam curing in the step (4) are 80 ℃ steam curing and a curing time of 4 to 10 hours.

[0020] The application provides a steel tailings pavement brick and a preparation method thereof, and the application has the following beneficial effects compared with the prior art:

[0021] (1) The free calcium oxide in the steel slag in the application can be significantly inhibited, and the prepared steel slag pavement brick has excellent mechanical strength and good volume stability, thereby providing technical support for the bulk utilization of steel slag in building materials.

[0022] (2) The steel slag has large reserves, is convenient to make and process, has fast hardening speed and good durability, and has a broad application prospect in construction engineering. DETAILED DESCRIPTION

[0023] In order to better explain the application and facilitate understanding, the application is described in detail below through specific embodiments.

[0024] The application provides a steel slag pavement brick, which inhibits free calcium oxide and free magnesium oxide in steel slag by using desulfurization wastewater and active silicon monomers and active aluminum monomers, so as to solve the technical problem of poor volume stability of steel slag, which leads to expansion damage of engineering projects, and provide a new technical scheme for bulk utilization of industrial solid wastes such as steel slag.

[0025] The steel slag pavement brick provided by the application has the following raw material composition according to weight percentage: 60% to 80% of steel slag, 5% to 10% of silicon-aluminum phase material, 0% to 20% of iron tailings, and 10% to 20% of cementitious material.

[0026] The steel slag is waste slag discharged in steel smelting, and is divided into converter slag, open-hearth furnace slag and electric furnace slag according to the type of the furnace. The particle size is divided into 0 to 2.36 mm, 2.36 mm to 4.75 mm and 4.75 to 9.5 mm.

[0027] The silicon-aluminum phase material is a material rich in active silicon and aluminum elements, and the content of silicon dioxide is greater than 35% and the content of aluminum oxide is greater than 10% according to weight percentage. The silicon-aluminum phase material is one or a mixture of more of slag, fly ash and kaolin, and the particle size is less than 75 μm.

[0028] The iron tailings are waste after ore dressing, and are a material rich in silicon, iron, calcium and aluminum elements. The content of silicon dioxide in the iron tailings is greater than 65% according to weight percentage, and the particle size is less than 75 μm.

[0029] The cementitious material is composed of cement, sodium metasilicate and sodium aluminate, and the content of cement is 97%, the content of sodium metasilicate is 2.8%, and the content of sodium aluminate is 0.2% according to weight percentage. The cementitious material in the embodiment is commercially available cement and industrial raw materials.

[0030] The application further provides a preparation method of the steel slag pavement brick, which specifically includes the following steps:

[0031] (1) Soak the steel tailings in desulfurization wastewater for 12 to 48 hours, and then dry them at 40 to 60°C for 2 to 4 hours.

[0032] (2) Mix 60% to 80% of the dried steel tailings with 5% to 10% of the silica-alumina phase material, 0% to 20% of the iron tailings and 10% to 20% of the cementitious material;

[0033] (3) Add water at a ratio of 25% to 45% of the mass of the cementitious material and stir to form a plastic body, then press it into a blank;

[0034] (4) The material obtained by steam curing at 80°C for 4 to 10 hours is the steel tailings paving brick of the present invention.

[0035] The principle of this invention:

[0036] This invention first involves immersing steel tailings in desulfurization wastewater. The calcium, magnesium, sulfate, and chloride ions in the wastewater initially inhibit the free calcium oxide and magnesium oxide. In the weakly acidic environment of the wastewater, magnesium and chloride ions react with free magnesium oxide (f-MgO) in the steel tailings to form the main product of magnesium oxychloride cement. Sulfate and sulfite ions in the wastewater react with free calcium oxide (f-CaO) in the steel tailings to form calcium sulfate and calcium sulfate. Furthermore, the pH shift from weakly acidic to alkaline during the reaction is beneficial for reaction stability. After immersion, drying is performed to provide air curing, further stabilizing the reaction products of free oxides in the steel tailings. The specific reaction mechanism is as follows:

[0037] 5MgO+MgCl2+13H2O→5Mg(OH)2·MgCl2·8H2O

[0038] 3MgO+MgCl2+11H2O→3Mg(OH)2·MgCl2·8H2O

[0039] 2CaO + 2H₂O + SO₃ 2- +SO4 2- =CaSO4 + CaSO3 + 4OH-

[0040] Furthermore, the steel tailings, which initially suppress free oxides, are mixed with fly ash, slag, iron tailings powder, sodium metasilicate, sodium aluminate, cement, etc., and water is added to stir and form a plastic body, which is then pressed into brick blanks. In the hydration reaction, firstly, cement hydration produces hydration products such as calcium hydroxide and calcium silicate hydrate gel (CSH), while also providing sufficient OH- ions for the reaction environment; secondly, the highly alkaline environment gradually depolymerizes the silica-alumina phase materials, sodium metasilicate, and sodium aluminate in the raw materials into Al(OH)4. -monomers such as Si(OH)4; at the same time, free oxide hydrolysis forms Ca 2+ ions, and Al(OH)4 - monomers such as Si(OH)4 to form porous calcium alumino-silicate hydrate gel (C-A-S-H), thereby achieving maximum inhibition of free oxide. The specific reaction mechanism is as follows:

[0041] CaO + H2O → Ca(OH)2+ Al(OH)4 - + Si(OH)4→ CaO·Al2O3·SiO2·H2O

[0042] (C-A-S-H)

[0043] CaO + H2O → Ca(OH)2+ Si(OH)4→ CaO·SiO2·H2O (C-S-H)

[0044] Example 1:

[0045] ① Steel slag: Fushun New Iron and Steel Co., Ltd., steel slag 1 (4.75-9.5 mm), steel slag 2 (2.36-4.75 mm), steel slag 3 (0-2.36 mm).

[0046] ② Silico-alumina phase material: slag, Fushun New Iron and Steel Co., Ltd.

[0047] ③ Iron tailings: Benxi Longxin Mining Co., Ltd.

[0048] ④ Cement: Portland cement 42.5, Liaoning Hengwei Cement Group.

[0049] ⑤ Sodium metasilicate, sodium aluminate: chemical pure, Shenyang Chemical Group Co., Ltd.

[0050] ⑥ Water: Shenyang tap water.

[0051] Table 1: Mix proportion of steel slag pavement brick Example 1

[0052]

[0053] First, the steel slag is soaked in desulfurization wastewater for 12 hours, and then dried at 60°C for 2 hours. Second, the raw materials are mixed according to the above proportions, and water accounting for 35% of the mass of cementitious materials (cement, sodium metasilicate, sodium aluminate) is added to form a plastic body and pressed into a brick blank. Finally, steam curing at 80°C for 8 hours. The final material is a steel slag pavement brick. After performance testing, the 28-day compressive strength reaches 43.2 MPa, and the volume expansion rate is 0.48%.

[0054] Example 2:

[0055] ① Steel slag: Fushun New Iron and Steel Co., Ltd.

[0056] ② Silicate-aluminate phase material: slag, Fushun New Iron and Steel Co., Ltd.

[0057] ③ Cement: common silica 42.5 cement, Liaoning Hengwei Cement Group.

[0058] ④ Sodium metasilicate and sodium aluminate: chemical pure, Shenyang Chemical Group Co., Ltd.

[0059] ⑤ Water: Shenyang tap water.

[0060] Table 2 Mixing ratio of steel slag pavement brick in Example 2

[0061]

[0062] First, the steel slag is soaked in desulfurization wastewater for 48 hours, and then dried at 40°C for 4 hours after being taken out; second, the raw materials are mixed according to the above-mentioned ratio, water accounting for 30% of the mass of cementing materials (cement, sodium metasilicate and sodium aluminate) is added to stir to form a plastic body and then pressed into a brick blank; finally, the brick blank is cured by steam at 80°C for 6 hours. The material obtained finally is a steel slag pavement brick. After performance test, the 28-day compressive strength of the brick is 48.7 MPa, and the volume expansion rate is 0.36%.

[0063] Example 3

[0064] ① Steel slag: Fushun New Iron and Steel Co., Ltd., steel slag 1 (4.75-9.5 mm), steel slag 2 (2.36-4.75 mm), and steel slag 3 (0-2.36 mm).

[0065] ② Silicate-aluminate phase material: slag, Fushun New Iron and Steel Co., Ltd.

[0066] ③ Iron tailings: Benxi Longxin Mining Co., Ltd.

[0067] ④ Cement: common silica 42.5 cement, Liaoning Hengwei Cement Group.

[0068] ⑤ Sodium metasilicate and sodium aluminate: chemical pure, Shenyang Chemical Group Co., Ltd.

[0069] ⑥ Water: Shenyang tap water.

[0070] Table 3 Mixing ratio of steel slag pavement brick in Example 3

[0071]

[0072] Firstly, the steel tailings are soaked in desulfurization wastewater for 48 hours, and then dried at 60℃ for 2 hours; secondly, the raw materials are mixed according to the above-mentioned proportion, 25% of water in the mass of cementing materials (cement, sodium metasilicate, sodium aluminate) is added to form a plastic body and is pressed into a brick blank; finally, the brick blank is cured by steam at 80℃ for 10 hours. The material obtained finally is the steel tailings pavement brick. After performance test, the 28-day compressive strength reaches 40.6MPa, and the volume expansion rate is 0.27%.

[0073] Example 4

[0074] ① Steel tailings: Fushun Xingang Iron and Steel Co., Ltd., steel tailings 1 (4.75-9.5mm), steel tailings 2 (2.36-4.75mm), steel tailings 3 (0-2.36mm).

[0075] ② Silicate material: slag, Fushun Xingang Iron and Steel Co., Ltd.

[0076] ③ Iron tailings: Benxi Longxin Mining Co., Ltd.

[0077] ④ Cement: ordinary Portland cement 42.5, Liaoning Hengwei Cement Group.

[0078] ⑤ Sodium metasilicate, sodium aluminate: chemical pure, Shenyang Chemical Group Co., Ltd.

[0079] ⑥ Water: Shenyang tap water.

[0080] Table 4: Mix proportion of steel tailings pavement brick of Example 4

[0081]

[0082] Firstly, the steel tailings are soaked in desulfurization wastewater for 12 hours, and then dried at 40℃ for 4 hours; secondly, the raw materials are mixed according to the above-mentioned proportion, 45% of water in the mass of cementing materials (cement, sodium metasilicate, sodium aluminate) is added to form a plastic body and is pressed into a brick blank; finally, the brick blank is cured by steam at 80℃ for 4 hours. The material obtained finally is the steel tailings pavement brick. After performance test, the 28-day compressive strength reaches 41.1MPa, and the volume expansion rate is 0.37%.

[0083] The steel tailings pavement brick prepared by the present application can realize the bulk utilization of steel tailings and other solid waste materials, and can overcome the defect of poor volume stability, and is a kind of green masonry material.

[0084] Example 5

[0085] ① Steel slag: Fushun New Iron and Steel Co., Ltd., Steel Slag 1 (4.75-9.5 mm), Steel Slag 2 (2.36-4.75 mm), Steel Slag 3 (0-2.36 mm).

[0086] ② Silicate-aluminate phase material: Slag, Fushun New Iron and Steel Co., Ltd.

[0087] ③ Iron tailings: Benxi Longxin Mining Co.

[0088] ④ Cement: Ordinary Portland cement 42.5, Liaoning Hengwei Cement Group.

[0089] ⑤ Sodium metasilicate, sodium aluminate: Chemical pure, Shenyang Chemical Group Co., Ltd.

[0090] ⑥ Water: Shenyang tap water.

[0091] Table 5 Mix proportion of steel slag pavement brick Example 1

[0092]

[0093] First, the steel slag was soaked in desulfurization wastewater for 30 hours, and then dried at 50°C for 3 hours. Second, the raw materials were mixed according to the above proportions, and water accounting for 35% of the mass of cementitious materials (cement, sodium metasilicate, sodium aluminate) was added to form a plastic body and pressed into a green brick. Finally, the green brick was cured in steam at 80°C for 8 hours. The final material obtained was a steel slag pavement brick. The 28-day compressive strength of the steel slag pavement brick was 39.9 MPa, and the volume expansion rate was 0.17%.

Claims

1. A steel slag pavement brick, characterized by, The raw material composition of the steel tailings pavement brick comprises, in percentage by weight, 60-80% of steel tailings, 5-10% of silico-alumina phase material, 0-20% of iron tailings and 10-20% of cementing material; The preparation method of the steel tailings pavement brick comprises the following steps: (1) soaking the steel tailings in desulfurization wastewater for a certain time, and drying after taking out; (2) mixing the dried steel tailings, silico-alumina phase material, iron tailings and cementing material according to a certain proportion; (3) adding a certain amount of water to stir to form a plastic body and press into a blank; (4) finally obtaining the steel tailings pavement brick after steam curing for a certain time.

2. A steel slag pavement brick according to claim 1, characterized in that, The steel tailings are waste slag discharged in steelmaking, which is divided into converter slag, open-hearth slag and electric furnace slag according to the furnace type, and the particle sizes of the converter slag, open-hearth slag and electric furnace slag are 0-2.36 mm, 2.36 mm-4.75 mm and 4.75-9.5 mm respectively.

3. A steel slag paving brick according to claim 1, characterized in that, The silico-alumina phase material comprises one or more of slag, fly ash and kaolin mixed, and the silico-alumina phase material contains more than 35% of silicon dioxide and more than 10% of aluminum oxide in percentage by weight; the particle size of the silico-alumina phase material is less than 75 μm.

4. A steel slag paving brick according to claim 1, characterized in that, The iron tailings are waste after ore dressing, and the iron tailings contain more than 65% of silicon dioxide in percentage by weight; the particle size of the iron tailings is less than 75 μm.

5. A steel slag paving brick according to claim 1, wherein The cementing material is composed of cement, sodium metasilicate and sodium aluminate, and the cementing material contains 97% of cement, 2.8% of sodium metasilicate and 0.2% of sodium aluminate in percentage by weight.

6. The method of claim 1, wherein the steel slag pavement brick is prepared by the steps of: The cations in the desulfurization wastewater in the step (1) are sodium, calcium and magnesium, and the anions are sulfate ions and chloride ions; the soaking time is 12-48 hours; and the drying conditions are a drying temperature of 40-60 ℃ and a drying time of 2-4 hours. ​ 7. The method for preparing steel tailings paving bricks according to claim 1, characterized in that, The proportioning of the steel tailings, silico-alumina phase material, iron tailings and cementing material in the step (2) is 60-80% of steel tailings, 5-10% of silico-alumina phase material, 0-20% of iron tailings and 10-20% of cementing material in percentage by weight.

8. The method for preparing steel tailings paving bricks according to claim 1, characterized in that, The amount of water in the step (3) is 25-45% of the mass of the cementing material.

9. The method for preparing steel tailings paving bricks according to claim 1, characterized in that, The steam curing conditions in the step (4) are 80 ℃ steam curing and a curing time of 4-10 hours.

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