Rapid detection method for activity of lithium slag for concrete

Abstract

The invention discloses a method for rapidly detecting the activity of lithium slag for concrete, which comprises the following steps: (a) detecting the marked activity of lithium slag to be detected, and recording as K1; and (b) K1 is substituted into a formula to obtain 7d activity K7 and 28d activity K28 of the lithium slag to be detected, K7 is equal to 0.94 * K1 <-37.70 >, K28 is equal to 0.69 * K1 + 30.95, and the unit of K1, K7 and K28 is percentage%. According to the rapid detection method for the activity of the lithium slag for the concrete, the 7-day activity and the 28-day activity of the lithium slag can be rapidly and accurately detected, the deviation of the 7-day activity is smaller than or equal to 7.8%, and the deviation of the 28-day activity is smaller than or equal to 7.4%, so that the rapid detection method has relatively good prediction capability on the activity of the lithium slag for the concrete; and the concrete mix proportion design and production application related to the lithium slag can be effectively guided.

Description

Technical Field

[0001] The invention relates to a method for detecting the activity of lithium slag, in particular to a method for quickly detecting the activity of lithium slag for concrete. Background Art

[0002] Lithium slag is a byproduct of the production of lithium carbonate by high-temperature roasting of spodumene and then using the sulfuric acid method. Its main components are SiO2, Al2O3, and CaO. If it is not comprehensively utilized as a resource, it will be a solid waste resource and will cause secondary pollution. In order to meet the global demand for a low-carbon future, lithium is favored as a renewable energy, continuous energy storage, and the most promising material in energy storage equipment. It is expected that lithium production will increase five times in 2050 compared with 2018. As one of the main strategic countries for lithium salts, my country has significantly increased the emission of lithium slag with the expansion of the lithium salt application market and the rapid growth of demand. According to the current lithium extraction process, 8-10 tons of lithium slag will be produced for every ton of lithium products produced. A large amount of lithium slag is piled up in the open air or filled to occupy a large amount of land, causing serious harm to the environment. At the same time, it will also inhibit the sustainable development of lithium salts as a clean energy.

[0003] As the building material with the largest volume of use, concrete has a strong solid waste disposal capacity. Using lithium slag as an admixture in concrete can effectively utilize the volcanic ash activity of lithium slag, and can reduce the amount of cement while absorbing the lithium slag produced by lithium battery companies, which is conducive to the green development of the construction industry and the lithium battery industry. However, as a new type of admixture, lithium slag has certain differences in activity due to differences in the mineral sources and lithium extraction processes of lithium battery manufacturers. At present, the activity detection method of lithium slag is the detection method of lithium slag powder activity in "Lithium Slag Powder Used in Cement and Concrete" YB / T 4230-2010. The activity of lithium slag is obtained by making cement mortar specimens and lithium slag mortar specimens and testing their compressive strength. This detection method takes a long time when detecting the activity for 7 days and 28 days. Therefore, how to quickly detect the activity of lithium slag is crucial for the safe and reliable use of lithium slag. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for quickly detecting the activity of lithium slag for concrete, which can quickly obtain the activity of lithium slag in advance.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a rapid detection method for the activity of lithium slag for concrete, comprising the following steps:

[0006] (a) Detecting the labeling activity of the lithium slag to be tested, denoted as K1;

[0007] (b) Substitute K1 into formulas (1) and (2) to obtain the 7d activity K7 and 28d activity K of the lithium slag to be tested. 28,

[0008] K7=0.94×K1-37.70 (1)

[0009] K 28 =0.69×K1+30.95 (2)

[0010] Among them, K1, K7, K 28 The unit is percentage %.

[0011] Furthermore, the method for detecting the 1d activity of the lithium slag in step (a) is:

[0012] (a1) Take the lithium slag to be tested, measure the moisture content, and prepare cement mortar specimens and lithium slag mortar specimens according to the specimen preparation method in "Test Method for Cement Mortar Strength - ISO Method" GB / T 17671-2021;

[0013] (a2) After being placed in a standard curing box for 24±2 hours, the mold is removed and the specimen is moved to a saturated calcium hydroxide solution at a constant temperature of 75-85°C for heat curing for 24±1 hours. The specimen is then transferred from the solution to a room temperature dry environment. After the specimen temperature drops to room temperature, the mortar strength test is performed to measure the cement mortar specimen strength R 水泥 , and the strength of lithium slag mortar specimen R 锂渣 ;

[0014] (a3) R 水泥 and R 锂渣 Substituting into formula (3), we get the lithium slag labeled activity K1,

[0015]

[0016] Furthermore, when preparing the test specimen in step (a1), the fluidity L of the cement mortar sample is tested, and the fluidity L1 of the lithium slag mortar sample is adjusted to L1=L±5mm by adjusting the amount of water reducing agent.

[0017] Furthermore, the temperature of thermal curing of cement mortar specimens and lithium slag mortar specimens in a constant temperature saturated calcium hydroxide solution was 80°C.

[0018] Furthermore, the comparison cement used to make cement mortar specimens is a general-purpose Portland cement with a strength grade of 42.5 as specified in GB175, and a 3d flexural strength of 5-6Mpa, a 3d compressive strength of 29-30.5Mpa, a standard consistency water consumption of 26%-28%, a sulfur trioxide content of 2.9%-3.0%, an admixture content of 8%-14%, and a slag content in the admixture of ≤4%.

[0019] The beneficial effects of the present invention are as follows: the rapid detection method for the activity of lithium slag for concrete of the present invention can quickly and accurately detect the 7-day activity and 28-day activity of the lithium slag, the deviation of the 7-day activity is ≤7.8%, and the deviation of the 28-day activity is ≤7.4%. Therefore, the method has good prediction ability for the activity of lithium slag for concrete, and can effectively guide the concrete mix design and production application related to lithium slag. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with embodiments.

[0021] Example:

[0022] 14 groups of lithium slag samples from different batches of different lithium extraction manufacturers were obtained. The test cement was a general Portland cement with a strength grade of 42.5 as specified in GB175 produced by a certain factory, and the 3d flexural strength was 5.2 MPa, the 3d compressive strength was 29.7 MPa, the standard consistency water consumption was 27.3%, the sulfur trioxide content was 2.97%, the admixture content was 10.4%, of which the slag content was 2.2%, and the fineness (45μm square hole sieve residue) was 5.10%.

[0023] (1) The moisture content p of the lithium slag samples was measured respectively. According to the specimen preparation method in "Test Method for Strength of Cement Mortar-ISO Method" GB / T17671-2021, cement mortar specimens and lithium slag mortar specimens were prepared respectively. When preparing the specimens, the fluidity L of the cement mortar specimens was tested. At the same time, the fluidity of the lithium slag mortar specimens was adjusted to L1=L±5mm by the amount of water reducer A1. The detected moisture content and the amount of water reducer A1 are shown in Table 1, and the test mix ratio is shown in Table 2 below.

[0024] Table 1

[0025]

[0026]

[0027] Table 2

[0028] project Cement / g Lithium slag / g Water / g Standard sand / g Water reducing agent / g Cement mortar sample 450 0 225 1350 0 Lithium slag mortar sample 315 135×(1+p) 225-135×p 1350 <![CDATA[A1]]>

[0029] (2) The prepared cement mortar specimens and lithium slag mortar specimens were placed in a standard curing box for 24±2 hours, then removed from the mold and moved to a saturated calcium hydroxide solution at 80°C for heat curing for 24±1 hours. They were then transferred from the solution to a room temperature dry environment. After the specimen temperature dropped to room temperature, the mortar strength test was performed to measure the cement mortar strength R 水泥 , and lithium slag mortar strength R 锂渣 .Depend on The lithium slag labeling activity K1 was calculated.

[0030] (3) Substitute the obtained K1 into (1) and (2) to calculate the lithium slag 7-day activity K7 and 28-day activity K 28 , the results are shown in Table 3.

[0031] K7=0.94×K1-37.70 (1)

[0032] K 28 =0.69×K1+30.95 (2)

[0033] Table 3

[0034]

[0035]

[0036] (4) The lithium slag samples were tested for the 7-day activity K7 and 28-day activity K of the corresponding lithium slag using the test method for lithium slag powder activity in "Lithium slag powder for cement and concrete" YB / T 4230-2010. 28 The tested cement is cement A, and the test results are shown in Table 2.

[0037] It can be seen from Table 2 that the maximum deviation between the measured value and the calculated value of the 7-day activity is 7.8%, the minimum is 0.9%, and the average is 3.9%; the maximum deviation between the measured value and the calculated value of the 28-day activity is 7.4%, the minimum is 0.7%, and the average is 3.8%; the average deviation is ≤5%, which has a good predictive ability for the activity of lithium slag for concrete; therefore, the activity of lithium slag for concrete can be detected and estimated by a rapid detection method, and the data can effectively guide the concrete mix design and production application related to lithium slag.

[0038] Comparative Example 1:

[0039] The test cement is a general-purpose Portland cement with a strength grade of 42.5 as specified in GB175 produced by a certain factory, and has a 3d flexural strength of 6.2Mpa, a 3d compressive strength of 31.9Mpa, a standard consistency water consumption of 24.94%, a sulfur trioxide content of 1.96%, an admixture content of 17.7%, of which slag content is 6.4%, and a fineness (45μm square hole sieve residue) of 6.5%.

[0040] The remaining test methods are the same as those in the embodiment. Sample 14 is tested and calculated, and the results are shown in Table 3.

[0041] Comparative Example 2:

[0042] Step (2) The prepared cement mortar specimens and lithium slag mortar specimens are placed in a standard curing box for curing for 24±2 hours, then demolded and moved to a 60°C calcium hydroxide solution for heat curing for 24±1 hours. The remaining test methods are the same as those in the embodiment. Sample 14 is tested and calculated, and the results are shown in Table 3.

[0043] Analyzing the data of Example Sample 14 and Comparative Examples 1 and 2, it is found that the test results of Comparative Examples 1 and 2 are significantly different from the actual values, and the test results are biased toward the larger value. If the data are used for mix design, the design richness coefficient will be too low.

Claims

1. A rapid detection method for the activity of lithium slag for concrete, characterized in that: The following steps are involved: (a) Detecting the labeling activity of the lithium slag to be tested, denoted as K1; (b) Substitute K1 into formulas (1) and (2) to obtain the 7d activity K7 and 28d activity K of the lithium slag to be tested. 28 , K7=0.94×K1-37.70 (1) K 28 =0.69×K1+30.95 (2) Among them, K1, K7, K 28 The unit is percentage %.

2. The rapid detection method for the activity of lithium slag for concrete according to claim 1, characterized in that: The method for detecting the 1d activity of the lithium slag in step (a) is: (a1) Take the lithium slag to be tested, measure the moisture content, and prepare cement mortar specimens and lithium slag mortar specimens according to the specimen preparation method in "Test Method for Cement Mortar Strength - ISO Method" GB / T 17671-2021; (a2) After being placed in a standard curing box for 24±2 hours, the mold is removed and the specimen is moved to a saturated calcium hydroxide solution at a constant temperature of 75-85°C for heat curing for 24±1 hours. The specimen is then transferred from the solution to a room temperature dry environment. After the specimen temperature drops to room temperature, the mortar strength test is performed to measure the cement mortar specimen strength R 水泥 , and the strength of lithium slag mortar specimen R 锂渣 ; (a3) R 水泥 and R 锂渣 Substituting into formula (3), we get the lithium slag labeled activity K1, 3. A rapid detection method for the activity of lithium slag for concrete according to claim 2, characterized in that: When preparing the test piece in step (a1), the fluidity L of the cement mortar sample is tested, and the fluidity L1 of the lithium slag mortar sample is adjusted to L1=L±5mm by adjusting the amount of water reducing agent.

4. A rapid detection method for the activity of lithium slag for concrete according to claim 2, characterized in that: The thermal curing temperature of cement mortar specimens and lithium slag mortar specimens in a constant temperature saturated calcium hydroxide solution is 80℃.

5. A rapid detection method for the activity of lithium slag for concrete according to any one of claims 1 to 4, characterized in that: The comparison cement used to make cement mortar specimens is general-purpose Portland cement with a strength grade of 42.5 as specified in GB175, and a 3d flexural strength of 5-6Mpa, a 3d compressive strength of 29-30.5Mpa, a standard consistency water consumption of 26%-28%, a sulfur trioxide content of 2.9%-3.0%, an admixture content of 8%-14%, and a slag content in the admixture of ≤4%.

Images