Manganese gypsum setting retarder for m32.5 cement, its application and m32.5 cement containing the same

Abstract

The application provides a manganese gypsum setting regulator for M32.5 cement and application and M32.5 cement containing the same, and relates to the technical field of concrete materials. The manganese gypsum setting regulator is prepared from electrolytic manganese residue, desulfurization waste ash and water in a mass ratio of (70-80):(10-20):10, and does not need high-temperature smelting or additional chemical reagents, so that the process is simple and the cost is low. After detection, the manganese gypsum setting regulator applied to the M32.5 cement can fully meet the technical requirements of M32.5 ordinary portland cement, and realizes direct resource utilization of electrolytic manganese residue and desulfurization waste ash.

Description

Technical Field

[0001] This invention relates to the field of concrete materials technology, and in particular to a manganese gypsum setting regulator for M32.5 cement, its application, and M32.5 cement containing the same. Background Technology

[0002] Electrolytic manganese slag is a large-scale hazardous solid waste generated by the electrolytic manganese industry, and its comprehensive resource utilization is a current global challenge. my country's electrolytic manganese industry generates approximately 10 million tons of manganese slag annually, with a massive historical stockpile. Currently, manganese slag is mainly disposed of by constructing dams for storage, which not only occupies a large amount of land resources but also poses safety hazards such as dam failure and leakage, seriously threatening groundwater and the surrounding ecological environment. Furthermore, electrolytic manganese slag has a complex composition, containing heavy metals such as manganese, lead, copper, zinc, and cadmium, as well as large amounts of sulfur and ammonia nitrogen, posing an extremely high environmental risk and has been classified as Class II general industrial solid waste.

[0003] To promote the resource utilization of electrolytic manganese slag, existing technologies mainly focus on its use in cement production, lightweight partition bricks, and cement admixtures after harmless treatment. For example, Ningxia Tianyuan Manganese Industry Group, in collaboration with the Chinese Academy of Environmental Sciences and other institutions, has developed technologies for the harmless treatment of electrolytic manganese waste slag and the recovery and utilization of ammonia nitrogen, realizing the transformation of manganese slag from Class II to Class I solid waste. Hunan Jianxiang High-Tech New Technology Development Co., Ltd., relying on the research strength of Central South University, has built a resource-based industrial demonstration line with an annual processing capacity of 300,000 tons of manganese-containing waste slag, producing recycled manganese powder and lightweight partition bricks. Despite some progress, existing technologies still generally face practical bottlenecks such as high processing costs, low product added value, and limited industrial scale. Patent CN118162447B discloses a method for treating electrolytic manganese slag: Electrolytic manganese slag is sealed and stirred with a modifier under negative pressure to obtain modified manganese slag and a first flue gas; the modified manganese slag is then mixed with a flux for oxidative smelting to obtain a first slag and a second flue gas; subsequently, the first slag is mixed with a reducing agent and a modifier for reduction smelting to obtain a second slag, a third flue gas, and a reduced metal liquid; a desulfurizing and phosphorus-removing agent is added to the reduced metal liquid for desulfurization and phosphorus removal to obtain a desulfurized and phosphorus-removed metal liquid; finally, the second slag is rapidly cooled and solidified into glass slag, and then ground together with an activator to produce active micro-powder. While this method can synergistically recover ammonia, sulfur, and valuable metals, the process is complex, integrating multiple high-energy-consuming and high-investment unit operations such as negative pressure ammonia removal, high-temperature oxidative smelting, reduction smelting, rapid cooling solidification, and grinding activation. The equipment system is large, and the operational stability requirements are high, making it difficult to scale up and apply in most electrolytic manganese enterprises or cement plants. Furthermore, there is no existing research or application of using modified electrolytic manganese slag directly as a setting regulator for M32.5 cement.

[0004] Therefore, it is essential and urgent to research and develop a simple, practical, low-cost method that does not require high-temperature smelting, is easy to implement, and produces stable products, to co-convert electrolytic manganese slag and desulfurization waste ash into a setting regulator that meets the requirements of M32.5 cement production, thereby achieving efficient resource utilization of the two types of industrial solid waste while ensuring environmental safety.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a manganese gypsum setting regulator for M32.5 cement. When applied to M32.5 cement, the manganese gypsum setting regulator can fully meet the requirements for setting time and strength, while also enabling low-cost, harmless, and direct resource utilization of two types of industrial solid waste: electrolytic manganese slag and desulfurization waste ash.

[0007] The second objective of this invention is to provide an application of manganese gypsum setting regulator.

[0008] A third objective of this invention is to provide an M32.5 cement.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The present invention provides a manganese gypsum setting regulator for M32.5 cement, wherein the manganese gypsum setting regulator is mainly prepared by mixing and aging electrolytic manganese slag, desulfurization waste ash and water; The mass ratio of electrolytic manganese slag, desulfurization waste ash and water is (70 ~ 80): (10 ~ 20): 10.

[0010] Furthermore, the mass ratio of the electrolytic manganese slag, desulfurization waste ash, and water is 80:10:10.

[0011] Furthermore, the electrolytic manganese slag is obtained by crushing, and the particle size of the electrolytic manganese slag is ≤10 mm.

[0012] Furthermore, the desulfurization waste ash originates from the waste residue discharged during the desulfurization process of float glass enterprises in Southwest China; The desulfurization waste ash contains 45-50% CaO and 30-35% SO3.

[0013] Furthermore, the aging time is 20 to 40 days, preferably 30 days.

[0014] Furthermore, the aging process is carried out under sealed conditions; The aging temperature is 20~30℃ and the humidity is ≥95%.

[0015] The use of the above-mentioned manganese gypsum setting regulator provided by the present invention in the preparation of M32.5 cement.

[0016] The present invention provides an M32.5 cement, wherein the M32.5 cement comprises the above-mentioned manganese gypsum setting regulator.

[0017] Furthermore, based on the mass of cement clinker, the amount of manganese gypsum used for setting in M32.5 cement is 1.0~3.0 wt%.

[0018] Furthermore, the initial setting time of the M32.5 cement is ≥60 min, and the final setting time is ≤720 min.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a manganese gypsum setting regulator for M32.5 cement. The manganese gypsum setting regulator is prepared from electrolytic manganese slag, desulfurization waste ash, and water in a mass ratio of (70~80):(10~20):10. It requires no high-temperature smelting or the addition of external chemical agents, resulting in a simple and low-cost process that directly utilizes the resources of two types of industrial solid waste: electrolytic manganese slag and desulfurization waste ash. Testing shows that when the manganese gypsum setting regulator of this invention is applied to M32.5 cement, the setting time meets national standards: initial setting time is 196~214 min, final setting time is 269~275 min; 28-day compressive strength is 34.9~35.5 MPa; mortar fluidity is 174~185 mm; and standard consistency water requirement is 27.2~27.8%. All properties fully meet the technical specifications of M32.5 general-purpose Portland cement.

[0020] The manganese gypsum setting regulator provided by this invention can be widely used in the preparation process of M32.5 cement.

[0021] The M32.5 cement provided by this invention, while meeting all the technical indicators of M32.5 cement, realizes the direct and large-scale resource utilization of electrolytic manganese slag and desulfurization waste ash in cement production, without changing the existing cement grinding process parameters. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] According to one aspect of the present invention, a manganese gypsum setting regulator for M32.5 cement is provided, wherein the manganese gypsum setting regulator is mainly prepared by mixing and aging electrolytic manganese slag, desulfurization waste ash and water; wherein the mass ratio of electrolytic manganese slag, desulfurization waste ash and water is (70 ~ 80): (10 ~ 20): 10.

[0024] This invention provides a manganese gypsum setting regulator for M32.5 cement. The manganese gypsum setting regulator is prepared from electrolytic manganese slag, desulfurization waste ash, and water in a mass ratio of (70~80):(10~20):10. It requires no high-temperature smelting or the addition of external chemical agents, resulting in a simple and low-cost process that directly utilizes the resources of two types of industrial solid waste: electrolytic manganese slag and desulfurization waste ash. Testing shows that when the manganese gypsum setting regulator of this invention is applied to M32.5 cement, the setting time meets national standards: initial setting time is 196~214 min, final setting time is 269~275 min; 28-day compressive strength is 34.9~35.5 MPa; mortar fluidity is 174~185 mm; and standard consistency water requirement is 27.2~27.8%. All properties fully meet the technical specifications of M32.5 general-purpose Portland cement.

[0025] In a preferred embodiment of the present invention, the mass ratio of the electrolytic manganese slag, desulfurization waste ash and water is 80:10:10.

[0026] In a preferred embodiment of the present invention, the electrolytic manganese slag is obtained by crushing, and the particle size of the electrolytic manganese slag is ≤10 mm.

[0027] As a preferred embodiment, after the electrolytic manganese slag is crushed to a particle size of ≤10 mm, the uniformity of the slurry formed by mixing it with desulfurization waste ash and water is significantly improved, ensuring the sufficiency and consistency of the acid-base neutralization reaction and the formation of the gypsum phase during the subsequent aging process.

[0028] In a preferred embodiment of the present invention, the desulfurization waste ash originates from the waste residue discharged during the desulfurization process of float glass enterprises in Southwest China; The desulfurization waste ash contains 45-50% CaO and 30-35% SO3.

[0029] In a preferred embodiment of the present invention, the aging time is 20 to 40 days, preferably 30 days.

[0030] In a preferred embodiment of the present invention, the aging process is carried out under sealed conditions; In the preferred embodiment described above, the aging temperature is 20~30℃ and the humidity is ≥95%.

[0031] According to one aspect of the present invention, the manganese gypsum setting regulator provided by the present invention can be widely used in the preparation process of M32.5 cement.

[0032] According to one aspect of the present invention, an M32.5 cement comprises the aforementioned manganese gypsum setting regulator.

[0033] The M32.5 cement provided by this invention, while meeting all the technical indicators of M32.5 cement, realizes the direct and large-scale resource utilization of electrolytic manganese slag and desulfurization waste ash in cement production, without changing the existing cement grinding process parameters.

[0034] In a preferred embodiment of the present invention, the amount of manganese gypsum used for setting in M32.5 cement is 1.0 to 3.0 wt% based on the mass of cement clinker.

[0035] In a preferred embodiment of the present invention, the initial setting time of the M32.5 cement is ≥60 min and the final setting time is ≤720 min.

[0036] The technical solution of the present invention will be further described below with reference to the embodiments.

[0037] Note: In the following embodiments of this application, the electrolytic manganese slag is taken from the electrolytic manganese slag discharged during the production process of an electrolytic manganese enterprise in Southwest China (it is grayish-black muddy, pH≈2.5, and has a moisture content of about 25%). The desulfurization waste ash was taken from the desulfurization process of flue gas in a float glass enterprise in Southwest China. The composition of the desulfurization waste ash is shown in Table 1.

[0038] Table 1. Chemical composition analysis of desulfurization waste ash generated during flue gas desulfurization in a float glass enterprise in Southwest China:

[0039] Note: Loss refers to the percentage of mass loss of the sample after calcination at 950℃ for 20 minutes.

[0040] There are no special restrictions on the source of the water; any production water or tap water familiar to those skilled in the art can be used.

[0041] Example 1 A manganese gypsum setting regulator for M32.5 cement, wherein the preparation method of the manganese gypsum setting regulator includes: 1. Place the electrolytic manganese slag in a crusher to crush it, pass it through a 10 mm square hole sieve, and collect particles with a particle size ≤10 mm for later use. 2. Weigh the crushed electrolytic manganese slag, desulfurization waste ash and water according to the mass ratio of 70:20:10, put them into a concrete mixer, and stir at 60 r / min for 15 min to obtain a uniform slurry. 3. Transfer the slurry to a well-ventilated, rain-proof, and sun-free storage area, and pile it into a trapezoidal pile about 1.2 m high. Allow it to age naturally for 30 days, during which the ambient temperature is 20~32℃ and the relative humidity is 60~85%.

[0042] 4. After aging, the pile is loosened and dried until the moisture content is ≤15%. It is then crushed by a hammer mill and passed through a 0.9 mm square hole sieve to obtain a grayish-white powder, which is the manganese gypsum coagulant.

[0043] Examples 2 and 3 Except for the mass ratio of electrolytic manganese slag, desulfurization waste ash and water in step 2, the embodiments of this application 2 and 3 are the same as those of embodiment 1, as detailed in Table 2.

[0044] Table 2. Manganese gypsum setting regulators with different mass ratios in Examples 2 and 3:

[0045] Example 4 Except for the natural aging time of 20 days in step 3, the rest of Embodiment 4 of this application is the same as Embodiment 1.

[0046] Comparative Examples 1-4 The comparative examples 1 to 4 of this application are the same as those in Example 1, except that the mass ratio of electrolytic manganese slag, desulfurization waste ash and water in step 2 is different from that in Example 1, as shown in Table 3.

[0047] Table 3. Proportions of manganese gypsum setting regulators for comparative examples 1-4:

[0048] Experimental Example 1 The manganese gypsum setting regulator prepared in Example 1 was applied to the preparation of M32.5 cement. The amount of manganese gypsum setting regulator added was investigated. The raw material composition is shown in Table 4.

[0049] Table 4. M32.5 cement raw material proportioning table for the gradient test of manganese gypsum setting regulator dosage in Example 1:

[0050] Note: The clinker used in this application is silicate cement clinker that fully complies with the technical requirements of GB 175 "General Silicate Cement". As the core base material for cement strength formation, it accounts for a constant 57.5%. The core mineral composition is mainly tricalcium silicate (C3S) and dicalcium silicate (C2S), supplemented with appropriate amounts of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF). This not only provides sufficient early and late strength for cement, but also creates an alkaline environment during hydration, laying the foundation for the retarding effect of setting regulators. In addition, the clinker must meet the key indicators of magnesium oxide content ≤5.0%, sulfur trioxide content ≤3.5%, loss on ignition ≤1.5%, and qualified boiling stability. In this application, the slag selected conforms to the GB / T 203 standard "Granulated Blast Furnace Slag for Cement" and accounts for a fixed proportion of 3.5%. This slag is glassy active particles formed by water quenching of molten blast furnace slag. As an active admixture, it can undergo a secondary hydration reaction with the calcium hydroxide generated during cement hydration to generate hydrated calcium silicate gel with gelling properties. This not only supplements the later strength of cement and optimizes the volume stability and erosion resistance of M32.5 cement, but also reduces clinker usage and production costs while ensuring product performance.

[0051] The coal slag in this application comes from a thermal power plant and is a solid waste formed by the melting, cooling, and separation of inorganic mineral residues after coal is burned at high temperatures in a boiler. The coal slag is in the form of lumps or granules, with a particle size of generally 5–50 mm; its composition is approximately SiO2 (silicon dioxide): 40%–50%, Al2O3 (alumina): 20%–35%, and Fe2O3 (iron oxide): 4%–20%.

[0052] The M32.5 cement prepared above was subjected to performance testing. The specific testing method is as follows: According to GB / T 2419, the flowability of cement mortar is tested as follows: prepare mortar with a ratio of cement, ISO standard sand and water of 1:3:0.50, fill the well mixed mortar into the flowability test mold, tamp it evenly with a tamping rod, level it, lift the test mold vertically, start the flowability tester immediately, measure the diameter of the mortar in two mutually perpendicular directions after diffusion, and take the average value as the flowability of the cement mortar.

[0053] According to GB / T 1346-2024, the setting time of cement was tested as follows: First, cement paste was prepared according to the standard consistency water content, poured into a round mold and leveled, then placed in a moisture curing chamber for curing. At the specified temperature, a setting time test needle was used for vertical free-fall testing. Initial setting was determined when the needle sank 4±1 mm into the paste from the bottom plate, and final setting was determined when the needle sank no more than 0.5 mm. Timing started from the beginning of water addition and mixing, and the initial and final setting times were recorded. According to GB / T 17671, the strength of cement mortar was tested as follows: Mortar was prepared by mixing cement, ISO standard sand, and water in a ratio of 1:3:0.50. The mortar was poured into a 40×40×160mm mold and vibrated to form the mortar. After curing under specified conditions for 24 hours, the mortar was demolded, and further curing was continued until 3 days and 28 days of age, at which point the flexural and compressive strengths were measured. Specific test results are shown in Table 5.

[0054] Table 5. Test results of comprehensive performance of M32.5 cement with different amounts of manganese gypsum setting regulator:

[0055] The test results above show that the initial setting time of the above samples GX250601~GX250604 is between 196 and 214 min, and the final setting time is between 269 and 275 min, all of which meet the national standard requirements of M32.5 masonry cement: initial setting time ≥60 min and final setting time ≤720 min. Regarding the mortar flowability, all three groups (GX250601, GX250602, and GX250603) have a flowability of ≥180 mm, meeting the flowability requirements of M32.5 cement; the standard consistency water content is between 27.2% and 27.8%, with minimal fluctuation. In terms of strength, the 3-day flexural strength is 3.8~4.3 MPa, the 28-day flexural strength is 6.2~6.8 MPa, the 3-day compressive strength is 18.7~18.9 MPa, and the 28-day compressive strength is 34.9~35.5 MPa. All of these meet the requirements of M32.5 cement for 3-day compressive strength ≥10.0 MPa and 28-day compressive strength ≥32.5 MPa, as well as the corresponding flexural strength. The overall strength performance is stable and has a margin of safety.

[0056] Experiment Example 2 The manganese gypsum setting regulators prepared in Examples 1-4 and Comparative Examples 1-4 were applied to the preparation of M32.5 cement, and the raw material proportions are as follows: Clinker 57.5%, desulfurized gypsum 1.5%, limestone 20.5%, fly ash 5%, slag 3.5%, coal slag 10%, manganese gypsum setting regulator 2%; The manganese gypsum setting regulator was verified by comparing the manganese gypsum setting regulators prepared in Examples 1-4 and Comparative Examples 1-4. The raw material ratios are shown in Table 6.

[0057] Table 6: M32.5 cement mix proportions for manganese gypsum setting regulators in Examples 1-4 and Comparative Examples 1-4:

[0058] The test results are shown in Table 7.

[0059] Table 7 shows the effect of manganese gypsum setting regulator on the performance of M32.5 cement in Examples 1-4 and Comparative Examples 1-4.

[0060] As shown in Table 7 above, the M32.5 cement prepared by manganese gypsum setting regulators in Examples 1-4 has an initial setting time of 200-215 min, a final setting time of 263-275 min, a 28-day compressive strength of 35.1-35.6 MPa, a mortar flowability of 180-188 mm, and a standard consistency water requirement of 27.2-27.5%. All indicators fully meet the requirements of M32.5 grade cement and have significant performance margins and good workability.

[0061] In Comparative Example 1, with a mass ratio of electrolytic manganese slag, desulfurization waste ash, and water of 45:45:10, Table 7 shows that the fluidity of the resulting M32.5 cement mortar decreased to 173 mm. The flexural strength at 3 days and 28 days was 3.3 MPa and 5.8 MPa, respectively, and the compressive strength at 3 days and 28 days was 17.7 MPa and 34.4 MPa, respectively. All of these values ​​are lower than those in Examples 1-4, indicating that excessive amounts of desulfurization waste ash are not conducive to the overall performance of the setting regulator, resulting in poor performance.

[0062] In Comparative Example 2, with a mass ratio of electrolytic manganese slag, desulfurization waste ash, and water of 60:30:10, Table 7 shows that the final setting time of the resulting M32.5 cement was shortened to 256 min, the mortar fluidity was 173 mm, and the 28-day flexural strength and 28-day compressive strength were only 5.6 MPa and 33.9 MPa, respectively, which are lower than those in Examples 1-4. This indicates that the synergistic effect of the components under this ratio is insufficient, resulting in a poor setting regulation effect.

[0063] In Comparative Example 3, with a mass ratio of electrolytic manganese slag, desulfurization waste ash, and water of 85:5:10, Table 7 shows that the initial and final setting times of the resulting M32.5 cement were shortened to 194 min and 254 min, respectively, the mortar fluidity decreased to 164 mm, and the 28-day flexural strength and 28-day compressive strength were 5.5 MPa and 33.7 MPa, respectively. This indicates that when the amount of desulfurization waste ash is too low, the setting regulator has insufficient effect on improving workability and strength, and the effect is poor.

[0064] In contrast to Example 4, which did not include desulfurization waste ash, Table 7 shows that the initial and final setting times of the resulting M32.5 cement were 191 min and 251 min, respectively, the mortar fluidity was only 161 mm, the flexural strength at 3 days and 28 days were 3.1 MPa and 5.1 MPa, and the compressive strength at 3 days and 28 days were 17.1 MPa and 33.0 MPa, respectively, all of which were the lowest among all groups. This indicates that the lack of desulfurization waste ash significantly weakens the effect of the setting regulator on improving the cement performance, resulting in a poor effect.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A manganese gypsum setting regulator for M32.5 cement, characterized in that, The manganese gypsum setting regulator is mainly prepared by mixing and aging electrolytic manganese slag, desulfurization waste ash and water. The mass ratio of electrolytic manganese slag, desulfurization waste ash and water is (70 ~ 80): (10 ~ 20):

10.

2. The manganese gypsum setting regulator according to claim 1, characterized in that, The mass ratio of electrolytic manganese slag, desulfurization waste ash and water is 80:10:

10.

3. The manganese gypsum setting regulator according to claim 1, characterized in that, The electrolytic manganese slag is obtained by crushing, and the particle size of the electrolytic manganese slag is ≤ 10 mm.

4. The manganese gypsum setting regulator according to claim 1, characterized in that, The desulfurization waste ash comes from the waste residue discharged during the desulfurization process of float glass enterprises in Southwest China; The desulfurization waste ash contains 45-50% CaO and 30-35% SO3.

5. The manganese gypsum setting regulator according to claim 1, characterized in that, The aging time is 20 to 40 days, preferably 30 days.

6. The manganese gypsum setting regulator according to claim 1, characterized in that, The aging process is carried out under sealed conditions; The aging temperature is 20~30℃ and the humidity is ≥95%.

7. The use of the manganese gypsum setting regulator according to any one of claims 1 to 6 in the preparation of M32.5 cement.

8. An M32.5 cement, characterized in that, The M32.5 cement includes the manganese gypsum setting regulator as described in any one of claims 1 to 6.

9. The M32.5 cement according to claim 8, characterized in that, The amount of manganese gypsum used to adjust the setting of cement in M32.5 cement is 1.0 ~ 3.0 wt% based on the weight of cement clinker.

10. The M32.5 cement according to claim 8, characterized in that, The initial setting time of the M32.5 cement is ≥60 min, and the final setting time is ≤720 min.

Images