Method for preparing concrete aggregate from smelting steel slag

Abstract

The invention relates to the technical field of building materials, in particular to a method for preparing concrete aggregate by utilizing smelting steel slag, which comprises the following steps: step 1, preparing the smelting steel slag for preparing the concrete aggregate; 2, the prepared smelting steel slag is subjected to crushing treatment; 3, impurities are removed through multi-stage screening; 4, the treated steel slag is pretreated, wherein the pretreatment comprises a hot braising process and carbonization treatment; 5, detecting the aggregate obtained in the step 4; 6, a modifier is added for modification treatment; and 7, balling the modified aggregate raw material, pre-curing, and then carrying out carbonization treatment. According to the method, the particle size of the crushed steel slag meets the requirements of concrete aggregate, impurities in the steel slag are removed in a multi-stage manner, and the treated steel slag is subjected to pretreatment including a hot braising process and carbonization treatment to improve the stability, so that the method can be used for thoroughly removing the impurities and comprehensively and fully pretreating the steel slag, and the quality of the aggregate is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and specifically to a method for preparing concrete aggregates by using smelted steel slag. Background Art

[0002] Steel slag is a by-product in the steelmaking process, which is composed of various oxides formed by the oxidation of impurities such as silicon, manganese, phosphorus, and sulfur in pig iron during the smelting process, as well as salts formed by the reaction of these oxides with solvents. For the utilization of steel slag, it can generally be recycled as a smelting solvent in steel plants or used as a raw material for building materials.

[0003] Steel slag gravel has the advantages of high strength, rough surface, wear resistance, good durability, large bulk density, good stability, and firm combination with asphalt. Compared with ordinary gravel, it also has the characteristic of resistance to low-temperature cracking. Therefore, in the prior art, steel slag is often used to replace gravel and fine and coarse aggregates to prepare concrete.

[0004] In the process of preparing concrete aggregates by using smelted steel slag, it is necessary to remove the metal impurities mixed in the smelted steel slag. At present, most of the existing methods for preparing concrete aggregates by using smelted steel slag have the problems of incomplete impurity removal and insufficient pretreatment of steel slag, which affect the quality of aggregates. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides a method for preparing concrete aggregates by using smelted steel slag, which has the advantages of thorough impurity removal and comprehensive pretreatment of steel slag, and solves the above problems.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing concrete aggregates by using smelted steel slag, comprising the following steps:

[0010] Step 1: Prepare the smelted steel slag for preparing concrete aggregates;

[0011] Step 2: Crush the prepared smelted steel slag;

[0012] Step 3: Remove impurities through multi-stage screening;

[0013] Step 4: Pretreat the processed steel slag, including the hot stewing process and carbonization treatment;

[0014] Step 5: Detect the aggregates obtained in Step 4;

[0015] Step 6: Add a modifier for modification treatment;

[0016] Step 7: Form the modified aggregate raw materials into balls, perform pre-curing and then carbonization treatment to form high-strength artificial aggregates.

[0017] Preferably, in Step 2, ensure that the particle size of the crushed steel slag meets the requirements of concrete aggregates, such as 5-40 mm coarse aggregates or 0.5-3 mm fine aggregates.

[0018] Preferably, in Step 3, remove impurities in the steel slag through multiple stages to ensure the quality of the aggregates.

[0019] Preferably, in Step 4, the thermal soaking process: calcine and digest the free CaO in the steel slag by roasting at a high temperature of 600-800 °C to reduce the risk of later expansion; carbonization treatment: react the steel slag particles with carbon dioxide to solidify the free CaO and MgO and improve the soundness (requires a closed environment, CO2 concentration of 100%, air pressure of 0.2 MPa, carbonization for 4 hours).

[0020] Preferably, in Step 5, grind the steel slag aggregates to a specific surface area of more than 500 m 2 / kg, and detect the soundness according to the standard: free CaO ≤ 4.0%, autoclave expansion rate ≤ 0.50%.

[0021] Preferably, in Step 6, by mixing admixtures such as fly ash and brick fine powder, and adding additives such as EDTA and sodium carbonate (concentration 0.02-3%), improve the carbonization efficiency and the strength of the aggregates.

[0022] (III) Beneficial effects

[0023] Compared with the prior art, the present invention provides a method for preparing concrete aggregates using smelting steel slag, having the following beneficial effects:

[0024] 1. In the present invention, by ensuring that the particle size of the crushed steel slag meets the requirements of concrete aggregates, and removing impurities in the steel slag through multiple stages to ensure the quality of the aggregates, and then performing pretreatment on the treated steel slag, including the thermal soaking process and carbonization treatment, calcine and digest the free CaO in the steel slag by roasting at a high temperature of 600-800 °C to reduce the risk of later expansion; react the steel slag particles with carbon dioxide to solidify the free CaO and MgO and improve the soundness, so that the method can thoroughly remove impurities and comprehensively and sufficiently pretreat the steel slag, effectively improving the quality of the aggregates.

[0025] 2. In the present invention, by grinding the steel slag aggregates to a specific surface area of more than 500 m 2 / kg, detecting the soundness according to the standard to further detect the aggregates, and finally by mixing admixtures such as fly ash and brick fine powder, and adding additives such as EDTA and sodium carbonate (concentration 0.02-3%), improve the carbonization efficiency and the strength of the aggregates. Detailed implementation manners

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] The present invention relates to a method for preparing concrete aggregate by using smelting steel slag, which includes the following steps:

[0028] Step 1: Prepare the smelting steel slag for preparing concrete aggregate;

[0029] Step 2: Crush the prepared smelting steel slag to ensure that the particle size of the crushed steel slag meets the requirements of concrete aggregate, such as 5-40 mm coarse aggregate or 0.5-3 mm fine aggregate;

[0030] Step 3: Remove impurities through multi-stage screening to ensure the quality of the aggregate;

[0031] Step 4: Pretreat the processed steel slag, including heat-curing process and carbonization treatment;

[0032] Heat-curing process: Burn and decompose free CaO in the steel slag at a high temperature of 600-800 °C to reduce the risk of later expansion; Carbonization treatment: React the steel slag particles with carbon dioxide to solidify free CaO and MgO and improve the soundness (a closed environment is required, CO2 concentration 100%, air pressure 0.2 MPa, carbonization for 4 hours);

[0033] Step 5: Detect the aggregate obtained in Step 4, grind the steel slag aggregate to a specific surface area of more than 500 m 2 / kg, and detect the soundness according to the standard: free CaO ≤ 4.0%, autoclave expansion rate ≤ 0.50%;

[0034] Individual aggregate detection: Randomly select at least 100 steel slag aggregates for autoclave test (216 °C, 2 MPa, 6 hours), and require the breakage rate < 5%. Further verification is carried out through the immersion expansion rate (90 °C water bath for 14 days) or the autoclave pulverization rate (the proportion of pulverized particles < 1.18 mm);

[0035] Step 6: Add a modifier for modification treatment, by mixing admixtures such as fly ash and brick fine powder, and adding additives such as EDTA and sodium carbonate (concentration 0.02-3%) to improve the carbonization efficiency and aggregate strength;

[0036] Step 7: Form the modified aggregate raw materials into balls, and carry out carbonization treatment after pre-curing to form high-strength artificial aggregates.

[0037] Prepare concrete according to the designed ratio, and conduct autoclave curing tests (80°C, 7 days) after 28 days of curing to ensure no visible damage to the naked eye. Conduct autoclave tests (216°C, 2 MPa, 6 hours) to verify that the strength loss rate ≤ 10%.

[0038] The beneficial effects of the present invention are as follows: By ensuring that the particle size of the crushed steel slag meets the requirements of concrete aggregates, and through multi-stage removal of impurities in the steel slag to ensure the quality of the aggregates, then pre-treat the processed steel slag, including the thermal steaming process and carbonization treatment. Roast at a high temperature of 600 - 800°C to decompose free CaO in the steel slag, reducing the risk of later expansion; React the steel slag particles with carbon dioxide to solidify free CaO and MgO, improving the soundness. Thus, this method can thoroughly remove impurities and comprehensively and fully pre-treat the steel slag, effectively improving the quality of the aggregates;

[0039] By grinding the steel slag aggregate to a specific surface area of more than 500 m 2 / kg, test the soundness according to the standard to further test the aggregates. Finally, by mixing admixtures such as fly ash and brick fines, and adding additives such as EDTA and sodium carbonate (concentration 0.02 - 3%), improve the carbonization efficiency and the strength of the aggregates.

[0040] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing concrete aggregate using smelting steel slag, characterized in that: The following steps are involved: Step 1: preparing smelting steel slag for preparing concrete aggregate; Step 2: crushing the prepared smelting steel slag; Step 3: Remove impurities through multi-stage screening; Step 4: pre-treating the treated steel slag, including hot stewing process and carbonization treatment; Step 5: Testing the aggregate obtained in step 4; Step 6: Adding modifier for modification; Step 7: Form the modified aggregate raw materials into balls, perform carbonization treatment after pre-curing, and form high-strength artificial aggregate.

2. The method for preparing concrete aggregate by using smelting steel slag according to claim 1, characterized in that: In the step 2, it is ensured that the particle size of the crushed steel slag meets the requirements of concrete aggregate, such as 5-40 mm coarse aggregate or 0.5-3 mm fine aggregate.

3. The method for preparing concrete aggregate by using smelting steel slag according to claim 1, characterized in that: The step three removes impurities in the steel slag through multiple stages.

4. The method for preparing concrete aggregate by using smelting steel slag according to claim 1, characterized in that: The hot stewing process in step 4: the free CaO in the steel slag is digested by stewing at a high temperature of 600-800° C.; the carbonization treatment: the steel slag particles are reacted with carbon dioxide to solidify the free CaO and MgO.

5. The method for preparing concrete aggregate by using smelting steel slag according to claim 1, characterized in that: In step 5, the steel slag aggregate is ground to a specific surface area of ​​500m 2 / kg or above, stability test according to the standard: free CaO ≤ 4.0%, pressure steam expansion rate ≤ 0.50%.

6. The method for preparing concrete aggregate by using smelting steel slag according to claim 1, characterized in that: In step six, fly ash, brick fine powder and other admixtures are mixed, and admixtures such as EDTA and sodium carbonate (concentration 0.02-3%) are added to improve carbonization efficiency and aggregate strength.