Green lightweight wet-mix mortar and method for preparing the same

Abstract

The application provides a green light-weight wet-mixed mortar and a preparation method thereof. The coal-fired slag is broken and sieved, and then divided into first slag and second slag according to different particle size ranges. Then, the weighed phosphogypsum, steel slag powder and lead-zinc tailing powder are mixed according to preset weight proportions, and wet grinding is performed to obtain a mixed slurry. Then, the required first slag and second slag are weighed according to preset weight proportions, pre-stirred, and then mixed with mortar glue, mortar regulator, the mixed slurry and water for sufficient stirring to obtain the green light-weight wet-mixed mortar. Through the above method, the synergistic effect between the raw materials can be effectively utilized, the formation of hydration products is promoted, and heavy metal ions are effectively solidified, so that the cheap and difficult-to-treat solid waste material is prepared into the green light-weight wet-mixed mortar with good mechanical properties, high stability and low apparent density, and has high economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of mortar preparation technology, and in particular to a green, lightweight wet-mixed mortar and its preparation method. Background Technology

[0002] Wet-mixed mortar is increasingly used in building construction due to its long plasticity retention time, stable quality, and convenient construction. Meanwhile, based on the recent requirements of the construction industry for carbon reduction and energy conservation, the application of lightweight mortar, which can achieve energy-saving effects through thermal insulation, is also increasing. However, the dry apparent density of ordinary wet-mixed mortar is typically around 1800 kg / m³. 3 The above methods do not meet the requirements for lightweight mortar. How to make wet-mixed mortar lightweight remains a pressing issue.

[0003] Patent CN105330215A discloses a method for preparing thermal insulation mortar. It uses cement, mineral powder, fly ash, talc, heavy calcium carbonate powder, silica fume, and lightweight particles as main raw materials. The addition of cement, mineral powder, and fly ash forms a high-strength, durable cement-based material, while the addition of lightweight particles reduces the overall apparent density of the mortar to meet lightweight requirements. However, based on this composition design, a large amount of lightweight particles leads to a decrease in mortar strength; a small amount makes it difficult to meet the lightweight requirement. The balance between lightweight and strength cannot be simultaneously achieved. Furthermore, the use of large amounts of cement, mineral powder, and fly ash significantly increases the mortar preparation cost and does not comply with energy conservation and emission reduction requirements.

[0004] Patent CN103360013A discloses a method for preparing gypsum-based thermal insulation mortar. The method involves using phosphogypsum, yellow phosphorus slag powder, cement, vitrified microspheres as lightweight aggregate, and additives as raw materials. After uniform mixing, a gypsum-based thermal insulation mortar with waste phosphogypsum and phosphorus slag as cementing materials is obtained. This patent effectively reduces preparation costs and improves the utilization rate of solid waste by using solid waste phosphogypsum and yellow phosphorus slag powder. However, the strength of the mortar in this patent is still mainly provided by cement. While replacing some cement with solid waste reduces costs, it also affects the strength of the resulting mortar.

[0005] In view of this, it is necessary to design an improved green lightweight wet-mixed mortar and its preparation method, which can effectively utilize solid waste to improve the strength of the mortar while achieving lightweighting, so as to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of the existing technology, the present invention aims to provide a green lightweight wet-mixed mortar and its preparation method. By pre-wetting and mixing phosphogypsum, steel slag powder, and lead-zinc tailings powder, and then adding coal slag with different particle size ranges, the synergistic effect between the raw materials is utilized to promote the formation of hydration products while effectively solidifying heavy metal ions. This method produces a green lightweight wet-mixed mortar with good mechanical properties, high stability, and low apparent density using inexpensive and difficult-to-treat solid waste materials, resulting in high economic and environmental benefits.

[0007] To achieve the above objectives, the present invention provides a method for preparing green lightweight wet-mixed mortar, comprising the following steps:

[0008] S1. Crush the coal-fired furnace slag to a maximum particle size of ≤4.75mm, screen it, and then sort it according to the required particle size to obtain the first slag with a particle size of ≤0.15mm and the second slag with a particle size of 0.15~4.75mm.

[0009] S2. Weigh out phosphogypsum, steel slag powder, lead-zinc tailings powder, mortar adhesive, mortar conditioner, water, and the first slag and the second slag obtained in step S1 according to the preset weight proportions.

[0010] S3. After weighing out the phosphogypsum, steel slag powder and lead-zinc tailings powder, mix them together, add some water and wet grind them to obtain a mixed slurry.

[0011] S4. Place the weighed first slag and second slag in a mixing device, pre-mix them, and then add mortar adhesive, mortar conditioner, the mixed slurry obtained in step S3, and the remaining water. After thorough mixing, green lightweight wet-mixed mortar is obtained.

[0012] As a further improvement of the present invention, in step S2, the preset weight fraction is:

[0013] 10-20 parts phosphogypsum, 5-10 parts lead-zinc tailings powder, 1-3 parts steel slag powder, 0.5-1 part mortar adhesive, 0.1-0.3 parts mortar conditioner, 5-10 parts first furnace slag, 70-80 parts second furnace slag, and 10-14 parts water.

[0014] As a further improvement of the present invention, in step S2, the mass fraction of dihydrate gypsum in the phosphogypsum is ≥85%, the mass fraction of phosphate is 0.5% to 2%, and the mass fraction of free fluorine is 0.5% to 2%.

[0015] As a further improvement of the present invention, in step S2, the mass fraction of ZnO in the lead-zinc tailings powder is ≤0.6%, the mass fraction of PbO is ≤0.9%, and the mass fraction of SiO2 is ≥25%.

[0016] As a further improvement of the present invention, in step S2, the mass fraction of CaO in the steel slag powder is ≥35%, and the mass fraction of powder with a particle size ≤80μm in the steel slag powder is ≥10%.

[0017] As a further improvement of the present invention, in step S1, the mass fraction of SiO2 in the coal-fired slag is ≥30%, and the mass fraction of Al2O3 is ≥10%.

[0018] As a further improvement of the present invention, the mass ratio of water added during wet milling in step S3 to water added in step S4 is 1:(0.9-1.1); the wet milling time is 10-20 min.

[0019] As a further improvement of the present invention, in step S2, the mortar adhesive includes a thickener and an air-entraining agent; the mortar conditioner includes one or more of white sugar, tartaric acid, cellulose ether, sodium gluconate, and sodium tripolyphosphate.

[0020] To achieve the above objectives, the present invention also provides a green lightweight wet-mixed mortar, which is prepared by the preparation method described in any of the above technical solutions.

[0021] As a further improvement of the present invention, the green lightweight wet-mixed mortar has a mortar plastic retention time of ≥8h and an apparent density of ≤1300kg / m³. 3 The green lightweight wet-mixed mortar has a 14-day bond strength ≥ 0.31 MPa and a 28-day compressive strength ≥ 15.4 MPa after curing.

[0022] The beneficial effects of this invention are:

[0023] (1) The method for preparing green lightweight wet-mixed mortar provided by the present invention involves pre-wetting and mixing phosphogypsum, steel slag powder, and lead-zinc tailings powder with specific contents, and then adding coal slag with different particle size ranges. This promotes the formation of hydration products and effectively solidifies heavy metal ions. It can not only effectively reduce the density of mortar by utilizing the porous honeycomb structure inside the coal slag, but also enable the coal slag, phosphogypsum, steel slag powder, and lead-zinc tailings powder to work synergistically to improve the strength of mortar. Thus, green lightweight wet-mixed mortar with good mechanical properties, high stability, and low apparent density is prepared using inexpensive and difficult-to-treat solid waste materials, which effectively improves the utilization value of solid waste and has high economic and environmental benefits.

[0024] (2) This invention, by pre-mixing and wet-milling phosphogypsum, steel slag powder, and lead-zinc tailings powder, enables the free phosphate and fluoride ions in the phosphogypsum to combine with the free calcium, lead, and zinc cations in the steel slag powder and lead-zinc tailings, forming stable precipitates. On the one hand, this reduces the retardation effect of phosphate and fluoride ions in the phosphogypsum on the hydration reaction, improving early strength; on the other hand, it solidifies the heavy metal ions in the lead-zinc tailings, reducing the heavy metal hazards of the tailings, thus effectively solving the problem that lead-zinc tailings are difficult to utilize effectively due to the presence of harmful heavy metal elements. Furthermore, as the subsequent hydration reaction proceeds, the generated precipitate is encapsulated in the hydration products and cannot dissolve, further ensuring the safety and stability of the green lightweight wet-mixed mortar.

[0025] (3) This invention divides coal-fired furnace slag into first slag and second slag according to different particle size ranges, mixes them in a specific ratio, and then adds a slurry made by grinding phosphogypsum, steel slag powder, and lead-zinc tailings powder. This allows the phosphogypsum to release a large amount of calcium ions and sulfate ions in water, while the calcium oxide released from the steel slag powder in water creates an alkaline environment for the system and provides an excess calcium source. Together, they form a system containing Ca. 2+ SO4 2- and OH - The alkaline environment activates the lead-zinc tailings and the first furnace slag, promoting the formation of Al in the lead-zinc tailings and slag powder. 3+ The dissociation of lead-zinc tailings and slag powder allows for secondary hydration activity. Simultaneously, the second slag acts as aggregate, providing support for the formed gel system. Under these conditions, phosphogypsum and steel slag powder added in specific proportions can also form Ca... 2+ Excessive environmental factors lead to the release of free Ca. 2+ With SO4 2- This combination promotes the formation of hydrated calcium silicate gel, thereby enabling the lightweight wet-mixed mortar system to continue hydrating and promoting a continuous increase in its compressive strength. The cementitious material system has a high alkalinity in the initial stage of hydration, and the main hydration products are CSH gel and ettringite, which intertwine to form a network, creating a hydration product layer that coats the cementitious material particles. Due to the low content of steel slag powder, the system contains excess Ca... 2+ As the pH gradually decreases, the formation rate of AFt also gradually decreases, and the system gradually stabilizes. With the extension of the hydration age, the amount of hydration products increases, the structure becomes more and more compact, and the strength further improves. Unreacted phosphogypsum is gradually encapsulated by hydration products in the system, giving the over-wet mortar better physical and mechanical properties and durability. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to specific embodiments.

[0027] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0028] This invention provides a method for preparing green lightweight wet-mixed mortar, comprising the following steps:

[0029] S1. Crush the coal-fired furnace slag to a maximum particle size of ≤4.75mm, screen it, and then sort it according to the required particle size to obtain the first slag with a particle size of ≤0.15mm and the second slag with a particle size of 0.15~4.75mm.

[0030] S2. Weigh out phosphogypsum, steel slag powder, lead-zinc tailings powder, mortar adhesive, mortar conditioner, water, and the first slag and the second slag obtained in step S1 according to the preset weight proportions.

[0031] S3. After weighing out the phosphogypsum, steel slag powder and lead-zinc tailings powder, mix them together, add some water and wet grind them to obtain a mixed slurry.

[0032] S4. Place the weighed first slag and second slag in a mixing device, pre-mix them, and then add mortar adhesive, mortar conditioner, the mixed slurry obtained in step S3, and the remaining water. After thorough mixing, green lightweight wet-mixed mortar is obtained.

[0033] In step S1, the mass fraction of SiO2 in the coal-fired slag is ≥30%, and the mass fraction of Al2O3 is ≥10%.

[0034] In step S2, the preset number of weight parts is:

[0035] The composition comprises: 10-20 parts phosphogypsum, 5-10 parts lead-zinc tailings powder, 1-3 parts steel slag powder, 0.5-1 parts mortar binder, 0.1-0.3 parts mortar conditioner, 5-10 parts first furnace slag, 60-80 parts second furnace slag, and 10-14 parts water; wherein the phosphogypsum contains ≥85% dihydrate gypsum, 0.5%-2% phosphate, and 0.5%-2% free fluorine; wherein the steel slag powder contains ≥35% CaO and ≥10% powder with a particle size ≤80μm; wherein the lead-zinc tailings powder contains ≤0.6% ZnO, ≤0.9% PbO, and ≥25% SiO2.

[0036] The mortar adhesive includes a thickener and an air-entraining agent; the mortar conditioner includes one or more of the following: sugar, tartaric acid, cellulose ether, sodium gluconate, and sodium tripolyphosphate.

[0037] The mass ratio of water added during wet milling in step S3 to water added in step S4 is 1:(0.9-1.1); the wet milling time is 10-20 min.

[0038] This invention also provides a green lightweight wet-mixed mortar, which is prepared by the preparation method described in any of the above-mentioned technical solutions; the green lightweight wet-mixed mortar has a plastic retention time of ≥8h and an apparent density of ≤1300kg / m³. 3 The green lightweight wet-mixed mortar has a 14-day bond strength ≥ 0.31 MPa and a 28-day compressive strength ≥ 15.4 MPa after curing.

[0039] The green lightweight wet-mixed mortar and its preparation method provided by the present invention will be described below with reference to specific embodiments and comparative examples.

[0040] Example 1

[0041] This embodiment provides a method for preparing green lightweight wet-mixed mortar, including the following steps:

[0042] S1. Crush the coal-fired slag to a maximum particle size of ≤4.75mm, and then screen the crushed coal-fired slag through a 100-mesh sieve to obtain the first slag with a particle size of ≤0.15mm and the second slag with a particle size greater than 0.15mm and less than or equal to 4.75mm.

[0043] S2. Weigh the raw materials according to the following weight proportions:

[0044] 15 parts phosphogypsum, 7 parts lead-zinc tailings powder, 2 parts steel slag powder, 0.7 parts mortar adhesive, 0.2 parts mortar conditioner, 8 parts first furnace slag, 70 parts second furnace slag, and 12 parts water.

[0045] S3. Mix 15 parts of phosphogypsum, 2 parts of steel slag powder and 7 parts of lead-zinc tailings powder, add 6 parts of water and wet grind to obtain a mixed slurry.

[0046] S4. Place 8 parts of the first slag and 70 parts of the second slag into a mixer, pre-mix for 1 minute, then add 0.5 parts of mortar adhesive, 0.2 parts of mortar conditioner, the mixed slurry obtained in step S3, and the remaining 6 parts of water. After thorough mixing, green lightweight wet-mixed mortar is obtained.

[0047] In actual construction, the green lightweight wet-mixed mortar prepared in this embodiment is poured into the required location, left to stand and cure for a predetermined period of time to meet the requirements for use.

[0048] Specifically, in this embodiment, the coal-fired slag used is the waste residue discharged after coal combustion in coal-fired power plants, industrial and civil boilers and other equipment, and its chemical composition is shown in Table 1; phosphogypsum is a solid waste generated in the wet phosphoric acid process, and its chemical composition is shown in Table 2; lead-zinc tailings powder is obtained by grinding solid waste in the lead-zinc ore beneficiation process, and its chemical composition is shown in Table 3; steel slag powder is obtained by grinding the steel slag remaining after iron extraction from the slag produced in steelmaking, and the mass fraction of powder with a particle size ≤80μm in the steel slag powder is ≥10%, and its chemical composition is shown in Table 4.

[0049] Table 1 Chemical Composition of Coal-fired Furnace Slag

[0050]

[0051] Table 2 Chemical composition of phosphogypsum

[0052]

[0053] Table 3 Chemical composition of lead-zinc tailings powder

[0054]

[0055] Table 4 Chemical Composition of Steel Slag Powder

[0056]

[0057] To test the performance of the green lightweight wet-mixed mortar prepared in this embodiment, the plastic retention time and apparent density of the green lightweight wet-mixed mortar obtained in step S4 were measured, and the mortar was poured into a mold. After standing for 24 hours, the mold was removed, and the mortar was then placed under standard conditions (20±2℃, humidity ≥90%) for curing to the predetermined age for performance testing.

[0058] Specifically, the bond strength of green lightweight wet-mixed mortar cured for 14 days and the compressive strength of green lightweight wet-mixed mortar cured for 28 days were tested. The water stability coefficient and heavy metal release of green lightweight wet-mixed mortar cured for 28 days were also tested. The results are shown in Table 5.

[0059] Table 5 Performance parameters of the green lightweight wet-mixed mortar prepared in Example 1

[0060]

[0061]

[0062] Examples 2-13 and Comparative Examples 1-6

[0063] Examples 2-13 and Comparative Examples 1-6 each provide a method for preparing green lightweight wet-mixed mortar. Compared with Example 1, the difference is that the raw material ratio in step S2 is changed. The raw material ratios corresponding to each example and comparative example are shown in Table 6. The remaining steps and parameters are the same as those in Example 1, and will not be repeated here.

[0064] Table 6. Raw material ratios for Examples 2-13 and Comparative Examples 1-6 (unit: parts by weight)

[0065]

[0066]

[0067] The green lightweight wet-mixed mortars prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 7.

[0068] Table 7 Performance data of Examples 2-13 and Comparative Examples 1-6

[0069]

[0070]

[0071] According to Table 7, comparing Examples 2 and 3, it can be seen that reducing the amount of phosphogypsum in Example 2 reduces its activation effect on lead-zinc tailings powder and the first slag, leading to a decrease in hydration rate and degree, further increasing the plasticity retention time of the wet-mixed mortar and decreasing the 14-day bond strength and 28-day compressive strength. While increasing the amount of phosphogypsum in Example 3 can increase early hydration and shorten the plasticity retention time, the low content of cementitious materials also reduces the final strength, thus decreasing the 14-day bond strength and 28-day compressive strength. Comparing Examples 4 and 5, it can be seen that increasing the amount of lead-zinc tailings increases the apparent density and consistency loss of the mortar, mainly because the density of lead-zinc tailings powder is greater than that of the first slag powder. Simultaneously, lead-zinc tailings help remove phosphate and fluoride ions from the phosphogypsum, accelerating the reaction rate. Comparing Examples 6 and 7, it can be seen that adjusting the amount of steel slag powder results in several effects. Too low a steel slag powder content leads to low alkalinity and free calcium ion concentration in the early hydration system, hindering the hydration reaction and affecting mortar strength. Conversely, too high a steel slag powder content results in higher alkalinity and free calcium ion concentration in the early hydration system, leading to a faster early hydration rate. However, excessive calcium ions in the later stages generate excessive ettringite, causing volume expansion and reducing mortar strength. Comparing Examples 8 and 9, it can be seen that reducing the mortar binder content leads to lower mortar consistency and a shorter plasticity retention time. Increasing the mortar binder content improves the mortar's water retention properties and extends the plasticity retention time, but negatively impacts the mortar's hardening strength. Comparing Examples 10 and 11, it can be seen that the mortar conditioner has a certain activating effect, promoting the hydration of the cementitious material system, shortening the mortar setting time, and improving both early and later strength. Decreasing the dosage of mortar conditioner leads to a longer mortar plasticity retention and setting time, while also reducing the mechanical properties of the hardened mortar. Conversely, increasing the content of mortar conditioner shortens the plasticity retention and setting time, while improving the later-stage mechanical properties of the mortar. Comparing Examples 12 and 13, it can be seen that reducing the dosage of the second slag increases the mortar powder content, improves both mortar consistency and water retention, and reduces the plasticity retention time. Increasing the dosage of the second slag decreases the mortar powder content, increases the fineness modulus, and reduces the mortar consistency and water retention.

[0072] Compared with Example 1, the content of phosphogypsum in Comparative Example 1 was too low, resulting in insufficient activation effect in the mortar system and a significant decrease in the 14-day bond strength and 28-day strength of the mortar. Further testing was conducted on the 28-day heavy metal release of the green lightweight wet-mixed mortar prepared in Comparative Example 1, and the results showed that Pb... 2+ The highest concentration was 0.057 mg / L, Zn 2+ The highest concentration was 0.062 mg / L, indicating that phosphogypsum has a significant adsorption effect on heavy metals in lead-zinc tailings. However, if the phosphogypsum dosage is too low, it will increase the adsorption of Pb. 2+ and Zn2+ The leaching rate increased. In Comparative Example 2, the absence of lead-zinc tailings resulted in insufficient adsorption of phosphate and fluoride ions from the phosphogypsum, leading to a slow hydration rate in the mortar and further affecting its strength. In Comparative Example 3, the lack of steel slag powder resulted in insufficient alkalinity and a deficiency of free calcium ions, leading to a very slow hydration reaction and low mortar strength. Further testing of the 28-day heavy metal leaching of the green lightweight wet-mixed mortar prepared in Comparative Example 3 revealed that Pb... 2+ The highest concentration was 0.039 mg / L, Zn 2+ The highest concentration was 0.043 mg / L, indicating that no steel slag powder was added, which would still increase Pb. 2+ and Zn 2+ The leaching rate is low, mainly because the lack of steel slag components hinders the hydration reaction of the mortar, reduces the overall density of the structure, and increases the leaching rate of heavy metal Pb. 2+ and Zn 2+ It is also easier to dissolve. In Comparative Example 4, the absence of mortar adhesive resulted in a poor initial state of the mortar, with low consistency and a short plastic retention time. In Comparative Example 5, the absence of mortar conditioner led to slow hydration of the cementitious material system, excessively long plastic retention time, and affected later strength. In Comparative Example 6, the amount of second slag was too low, the mortar powder content was too high, the mortar consistency was too high, the workability was poor, and cracking was likely to occur.

[0073] In summary, this invention provides a green lightweight wet-mixed mortar and its preparation method. The method involves crushing and screening coal-fired boiler slag, dividing it into first and second slags according to different particle size ranges. Then, phosphogypsum, steel slag powder, and lead-zinc tailings powder are mixed according to preset weight proportions and wet-milled to obtain a mixed slurry. Next, the required first and second slags are weighed according to preset weight proportions, pre-mixed, and then mortar adhesive, mortar conditioner, the mixed slurry, and water are added and thoroughly mixed to obtain the green lightweight wet-mixed mortar. Through this method, this invention effectively utilizes the synergistic effect between the raw materials, promoting the formation of hydration products while effectively solidifying heavy metal ions. This allows for the preparation of inexpensive and difficult-to-treat solid waste materials into a green lightweight wet-mixed mortar with good mechanical properties, high stability, and low apparent density, resulting in significant economic and environmental benefits.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing green lightweight wet-mixed mortar, characterized in that, Includes the following steps: S1. Crush the coal-fired furnace slag to a maximum particle size ≤ 4.75 mm, screen it, and then sort it according to the required particle size to obtain the first slag with a particle size ≤ 0.15 mm and the second slag with a particle size greater than 0.15 mm and less than or equal to 4.75 mm. S2. Weigh out phosphogypsum, steel slag powder, lead-zinc tailings powder, mortar adhesive, mortar conditioner, water, and the first slag and the second slag obtained in step S1 according to the preset weight proportions. The preset weight percentage is: 10-20 parts phosphogypsum, 5-10 parts lead-zinc tailings powder, 1-3 parts steel slag powder, 0.5-1 part mortar adhesive, 0.1-0.3 parts mortar conditioner, 5-10 parts first furnace slag, 70-80 parts second furnace slag, and 10-14 parts water. In the phosphogypsum, the mass fraction of phosphate is 0.5%~2%, and the mass fraction of free fluorine is 0.5%~2%. The mortar adhesive includes a thickener and an air-entraining agent; the mortar conditioner includes one or more of the following: sugar, tartaric acid, cellulose ether, sodium gluconate, and sodium tripolyphosphate. S3. After weighing out the phosphogypsum, steel slag powder and lead-zinc tailings powder, mix them together, add some water and wet grind them to obtain a mixed slurry. S4. Place the weighed first slag and second slag in a mixing device, pre-mix them, and then add mortar adhesive, mortar conditioner, the mixed slurry obtained in step S3, and the remaining water. After thorough mixing, green lightweight wet-mixed mortar is obtained.

2. The method for preparing green lightweight wet-mixed mortar according to claim 1, characterized in that: In step S2, the mass fraction of dihydrate gypsum in the phosphogypsum is ≥85%.

3. The method for preparing green lightweight wet-mixed mortar according to claim 1, characterized in that: In step S2, the mass fraction of ZnO in the lead-zinc tailings powder is ≤0.6%, the mass fraction of PbO is ≤0.9%, and the mass fraction of SiO2 is ≥25%.

4. The method for preparing green lightweight wet-mixed mortar according to claim 1, characterized in that: In step S2, the mass fraction of CaO in the steel slag powder is ≥35%, and the mass fraction of powder with a particle size ≥80 μm in the steel slag powder is ≤10%.

5. The method for preparing green lightweight wet-mixed mortar according to claim 1, characterized in that: In step S1, the mass fraction of SiO2 in the coal-fired slag is ≥30%, and the mass fraction of Al2O3 is ≥10%.

6. The method for preparing green lightweight wet-mixed mortar according to claim 1, characterized in that: The mass ratio of water added during wet milling in step S3 to water added in step S4 is 1:(0.9~1.1); the wet milling time is 10~20 min.

7. A green, lightweight, wet-mixed mortar, characterized in that: The green lightweight wet-mixed mortar is prepared by the preparation method according to any one of claims 1 to 6.

8. The green lightweight wet-mixed mortar according to claim 7, characterized in that: The green light-weight wet-mixed mortar has a mortar plastic retention time of 8 h or more, an apparent density of 1300 kg / m 3 3 or less; and a 14 d bonding strength of 0.31 MPa or more and a 28 d compressive strength of 15.4 MPa or more after solidification and molding.

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