Modified sludge incineration ash and application thereof

Abstract

The invention discloses modified sludge incineration ash and application thereof. The modified sludge incineration ash comprises the steps of alkali liquor dipping, centrifuging or filtering, drying, exciting agent adding and mortar utilization. According to the method, the adverse effect of phosphorus in the sludge incineration ash on the cement hydration reaction is avoided, the activity of the sludge incineration ash is improved, meanwhile, the mixing amount of the sludge incineration ash in mortar is increased, a way is provided for large-mixing-amount application of the sludge incineration ash in building materials, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the field of solid waste resource utilization, and in particular to a modified sludge incineration ash and its application. Background Art

[0002] The chemical composition of sludge incineration ash is mainly SiO2, Al2O3, CaO and Fe2O3, and contains a certain glass phase. It has potential cementing activity and can replace part of cement as auxiliary cementing material for mortar, concrete and other building materials to reduce cement consumption. It can also be used to replace fly ash phase materials as filling materials for backfill projects, etc., to achieve the purpose of energy saving and carbon reduction. However, since the phosphate contained in the sludge is thermally stable and not easy to volatilize during the incineration process, the phosphorus element in the sludge is further enriched in this process, accounting for about 4.9% to 11.9% of the mass of sludge incineration ash. When phosphorus-rich sludge incineration ash is used for building materials, it will weaken the cement hydration reaction process, prolong the cement setting time, and affect the quality and safety of mortar, concrete and other projects. Therefore, it is necessary to pre-treat the phosphorus in the sludge incineration ash before using it in building materials to ensure its safe resource utilization. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a modified sludge incineration ash and application thereof, so as to solve the problems in the prior art.

[0004] The present application provides a method for preparing modified sludge incineration ash, comprising the following steps: 1) mixing sludge incineration ash with an alkaline solution, reacting to obtain a first substance; 2) removing liquid from the first substance, washing to a pH of 6.5 to 7.5, and drying to obtain a second substance; 3) mixing the second substance with a calcium-based additive to obtain modified sludge incineration ash.

[0005] The present application also provides modified sludge incineration ash prepared by the above-mentioned preparation method.

[0006] The present application also provides the use of the above-mentioned modified sludge incineration ash in the preparation of mortar.

[0007] The present application also provides a mortar, the raw materials for preparing the mortar include the above-mentioned modified sludge incineration ash.

[0008] The present application also provides a method for preparing the above-mentioned mortar, which comprises mixing the preparation raw materials in the above-mentioned mortar.

[0009] The beneficial effects of the present application include but are not limited to: (1) the use of alkaline solution to treat sludge incineration ash does not dissolve heavy metal elements, and the pH of the solution can be adjusted to control the dissolution rate of phosphorus in the sludge incineration ash in the reaction liquid phase, and can react with phosphate in the sludge incineration ash to form Al(OH)4 -、Fe(OH)3 - PO4 3- Etc. Furthermore, by regulating parameters such as the concentration of the alkali solution impregnation reagent, the solid-liquid ratio, the reaction temperature, and the reaction time, the P2O5 content can be effectively reduced while retaining the silicon-aluminum oxide phase in the sludge incineration ash. This ensures that the pretreated sludge incineration ash still has volcanic ash cementing activity, and avoids excessive phosphorus content affecting the cement hydration process and setting time, thereby affecting its quality and safety in preparing mortar. (2) After the sludge incineration ash is pretreated with phosphorus control technology, the addition of calcium-based additives to prepare mortar can significantly improve the strength of the mortar. This is because after the addition of calcium-based additives, calcium ions and phosphates in the sludge incineration ash form calcium phosphate precipitates, thereby reducing the adverse effects of phosphorus on the cement hydration reaction process. In addition, the remaining Ca2+ in the calcium-based additive can further accelerate the hydration process and improve the density and strength of the test block. DETAILED DESCRIPTION

[0010] As shown in this specification and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0011] The present application provides a method for preparing modified sludge incineration ash, comprising the following steps: 1) mixing sludge incineration ash with an alkaline solution, reacting to obtain a first substance; 2) removing liquid from the first substance, washing to a pH of 6.5 to 7.5, and drying to obtain a second substance; 3) mixing the second substance with a calcium-based additive to obtain modified sludge incineration ash.

[0012] In some embodiments, in the step 1), the alkaline solution may be an aqueous solution of NaOH or KOH. In some embodiments, in the step 1), preferably, the concentration of the alkaline solution may be 0.5 to 1.5 mol / L. For example, the concentration of the alkaline solution may be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5 mol / L. It also includes any range characterized by a combination of the above end values, which will not be repeated here. In some embodiments, in the step 1), more preferably, the concentration of the alkaline solution may be 0.8 to 1.0 mol / L.

[0013] In some embodiments, in the step 1), the mass volume ratio (g / mL) of sludge incineration ash to alkaline solution may be (1-5):50. In some embodiments, in the step 1), the mass volume ratio (g / mL) of sludge incineration ash to alkaline solution may be (1.5-4.5):500. In some embodiments, in the step 1), the mass volume ratio (g / mL) of sludge incineration ash to alkaline solution may be (2-4):500. In some embodiments, in the step 1), the mass volume ratio (g / mL) of sludge incineration ash to alkaline solution may be (2.5-3.5):500. In some embodiments, in the step 1), the mass volume ratio (g / mL) of sludge incineration ash to alkaline solution may be 3:500.

[0014] In some embodiments, in step 1), the stirring speed during mixing can be 300 to 500 r / min. For example, the stirring speed during mixing can be 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490 or 500 r / min. Any range characterized by a combination of the above end values ​​is also included, which will not be repeated here.

[0015] In some embodiments, in step 1), the reaction temperature may be 40 to 60°C. For example, the reaction temperature may be 40, 42, 44, 46, 48, 50, 52, 54, 56, 58 or 60°C. Any range characterized by a combination of the above end values ​​is also included, which will not be repeated here. In some embodiments, in step 1), preferably, the reaction temperature may be 50°C.

[0016] In some embodiments, in step 1), the reaction time may be 4 hours to 6 hours. For example, the reaction time may be 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8 or 6 hours. Any range characterized by a combination of the above end values ​​is also included, which will not be repeated here.

[0017] In some embodiments, in step 1), the sludge incineration ash can be taken from a sewage treatment plant, and the total mercury in the sludge incineration ash is ≤5 mg / / kg, the total arsenic is ≤75 mg / / kg, the total cadmium is ≤5 mg / / kg, the total chromium is ≤600 mg / / kg, and the total lead is ≤300 mg / / kg.

[0018] In some embodiments, in step 2), the liquid can be removed by filtration or centrifugation.

[0019] In some embodiments, in step 2), washing is performed until the pH value is 7.0.

[0020] In some embodiments, in step 2), the drying temperature may be 40 to 60°C. For example, the drying temperature may be 40, 42, 44, 46, 48, 50, 52, 54, 56, 58 or 60°C. Any range characterized by a combination of the above end values ​​is also included, which will not be repeated here. In some embodiments, in step 2), preferably, the drying temperature may be 50°C.

[0021] In some embodiments, in step 2), the drying time can be 20 to 28 hours. For example, the drying time can be 20, 21, 22, 23, 24, 25, 26, 27 or 28 hours. It also includes any range characterized by a combination of the above end values, which will not be repeated here. In some embodiments, in step 2), preferably, the drying time can be 24 hours.

[0022] In some embodiments, in step 3), the calcium-based additive may include any one or more of CaCl2, CaO, Ca(OH)2 or CaSO4.

[0023] In some embodiments, in the step 3), the mass ratio of the second substance to the calcium-based additive may be (90.0-99.5): (0.5-10.0). In some embodiments, in the step 3), the mass ratio of the second substance to the calcium-based additive may be (91.0-99.0): (1.0-9.0). In some embodiments, in the step 3), the mass ratio of the second substance to the calcium-based additive may be (92.0-98.0): (2.0-8.0). In some embodiments, in the step 3), the mass ratio of the second substance to the calcium-based additive may be (93.0-97.0): (3.0-7.0). In some embodiments, in the step 3), the mass ratio of the second substance to the calcium-based additive may be (94.0-96.0): (5.0-6.0). In some embodiments, in the step 3), the mass ratio of the second substance to the calcium-based additive may be (95.0-96.0): (5.0-6.0). In some embodiments, in step 3), preferably, the mass ratio of the second substance to the calcium-based additive may be (98.5-99.0): (1.0-1.5).

[0024] In some embodiments, in step 3), after the second substance is mixed with the calcium-based additive, it is necessary to grind it to obtain the modified sludge incineration ash.

[0025] The present application also provides modified sludge incineration ash prepared by the above-mentioned preparation method.

[0026] The present application also provides the use of the above-mentioned modified sludge incineration ash in the preparation of mortar.

[0027] In some embodiments, the mortar can be a premixed mortar. In some embodiments, preferably, the mortar can be a plaster mortar. In some embodiments, more preferably, the mortar can be an M10 plaster mortar.

[0028] The present application also provides a mortar, the raw materials for preparing the mortar include the above-mentioned modified sludge incineration ash.

[0029] In some embodiments, the raw materials for preparing the mortar may include water and dry powder. In some embodiments, the dry powder may include cellulose ether and mortar dry powder. In some embodiments, the mortar dry powder may include any one or more of cement, fly ash, medium sand or the above-mentioned modified sludge incineration ash.

[0030] In some embodiments, the mass ratio of the cellulose ether to the dry mortar powder can be (0.01-0.03): (95-105). In some embodiments, the mass ratio of the cellulose ether to the dry mortar powder can be (0.015-0.025): (97.5-102.5). In some embodiments, the mass ratio of the cellulose ether to the dry mortar powder can be (0.02-0.025): (100-102.5). In some embodiments, preferably, the mass ratio of the cellulose ether to the dry mortar powder is 0.02:99.98.

[0031] In some embodiments, the mortar dry powder may include cement, fly ash, modified sludge incineration ash and medium sand. In some embodiments, preferably, the mass ratio of the cement, fly ash, modified sludge incineration ash and medium sand is (10-20): (5-9): (1-5): (80-120). In some embodiments, the mass ratio of the cement, fly ash, modified sludge incineration ash and medium sand is (12-18): (6-8): (2-4): (90-110). In some embodiments, the mass ratio of the cement, fly ash, modified sludge incineration ash and medium sand is (14-16): (7-8): (3-4): (100-110). In some embodiments, more preferably, the mass ratio of the cement, fly ash, modified sludge incineration ash and medium sand is 15:7:3:100.

[0032] In some embodiments, the fly ash may be Loucheng grade II ash.

[0033] In some embodiments, the medium sand particle size ranges from 0.5 to 1 mm. In some embodiments, the medium sand particle size ranges from 0.6 to 0.9 mm. In some embodiments, the medium sand particle size ranges from 0.7 to 0.8 mm.

[0034] In some embodiments, the cement may be P·O42.5 ordinary Portland cement.

[0035] In some embodiments, the mass ratio of water to dry powder is (10-20): (80-120). In some embodiments, the mass ratio of water to dry powder is (11-19): (85-115). In some embodiments, the mass ratio of water to dry powder is (12-18): (90-110). In some embodiments, the mass ratio of water to dry powder is (13-17): (95-105). In some embodiments, the mass ratio of water to dry powder is (14-16): (100-105). In some embodiments, the mass ratio of water to dry powder is (15-16): (100-105). In some embodiments, preferably, the mass ratio of water to dry powder is 15:100.

[0036] In some embodiments, the mortar is a premixed mortar. In some embodiments, preferably, the mortar is a plaster mortar. In some embodiments, more preferably, the mortar is an M10 plaster mortar.

[0037] The present application also provides a method for preparing the above-mentioned mortar, which comprises mixing the preparation raw materials in the above-mentioned mortar.

[0038] The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from conventional biochemical reagent companies unless otherwise specified. The quantitative tests in the following examples are repeated three times, and the results are averaged.

[0039] The sludge incineration ash used in this application was taken from a municipal sewage treatment plant in Shanghai. The total mercury in the sludge incineration ash was ≤5 mg / / kg, the total arsenic was ≤75 mg / / kg, the total cadmium was ≤5 mg / / kg, the total chromium was ≤600 mg / / kg, and the total lead was ≤300 mg / / kg.

[0040] Example 1

[0041] A method and application for controlling ash phosphorus from sludge incineration, the specific steps are:

[0042] a. Mix 50g of sludge incineration ash with 500ml of 1.0mol / L NaOH solution, stir on a magnetic stirrer at a speed of 300-500r / min, the reaction temperature is 50℃, and the reaction time is 6h;

[0043] b. The mixture obtained in step a is filtered or centrifuged to obtain a solid substance, and the solid substance is repeatedly washed with deionized water until the pH is 7.0;

[0044] c. Place the solid material obtained in step b into a 50°C oven for 24h;

[0045] d. Add 0.5% Ca(OH)2 to the solid obtained after drying in step c and grind for 10 minutes to obtain modified sludge incineration ash.

[0046] e. The modified sludge incineration ash obtained in step d is used for the preparation of M10 plaster mortar. The specific process is as follows:

[0047] (1) P·O42.5 ordinary silicate cement, fly ash (Loucheng grade II ash), modified sludge incineration ash, medium sand (purchased from Xiamen Ace Standard Sand Co., Ltd., with a particle size range of 0.5-1 mm) and cellulose ether (purchased from Shanghai Shangnan New Materials Co., Ltd., brand: HK 40000S, type: HPMC) were weighed and stirred according to mass. After mixing evenly, a dry mortar powder was prepared. The specific ratio was: cement: fly ash: modified sludge incineration ash: medium sand = 15:7:3:100; the amount of cellulose ether added was 0.02% of the total mass of cement, fly ash, modified sludge incineration ash and medium sand.

[0048] (2) Add water to the dry mortar powder obtained in step (1), add water while stirring, mix the dry mortar powder and water evenly, and obtain a premixed mortar. The amount of water added is about 15% of the total mass of the dry mortar powder.

[0049] The chemical components and strength activity index of the sludge incineration ash before pretreatment and the sludge incineration ash obtained in step c were tested, and the test results are shown in Table 1. The sludge incineration ash obtained in step d was used to prepare a plaster mortar with a strength grade of M10, and the compressive strength and tensile bond strength of the mortar were measured. The test results are shown in Table 2.

[0050] Table 1 Performance indicators of sludge incineration ash before and after pretreatment

[0051]

[0052] Table 2 Performance indicators of mortar

[0053] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 7.8 15.2 0.44 GB / T 25181-2019 / ≥10.0 ≥0.2

[0054] As shown in Table 1, after pretreatment, the P2O5 content of the sludge incineration ash decreased from 11.79% to 7.26%, a decrease of 38.4%, and the 28d strength activity index increased from 58.5% to 72.2%, an increase of 23.4%. It can be seen that the method of the present invention successfully reduces the P2O5 content in the sludge incineration ash, improves the activity of the sludge incineration ash, and the strength activity index meets the requirements of "Fly ash used in cement and concrete" (GB / T 1596-2017) (≥70%).

[0055] It can be seen from Table 2 that the mortar prepared with the sludge incineration ash obtained in step d has a 28d compressive strength of 15.2 MPa and a 14d tensile bond strength of 0.44 MPa, and the performance meets the mechanical properties requirements of "Premixed Mortar" (GB / T 25181-2019).

[0056] Example 2

[0057] A method and application for controlling ash phosphorus from sludge incineration, the specific steps are:

[0058] a. Mix 10g of sludge incineration ash with 500ml of 0.8mol / L NaOH solution, stir on a magnetic stirrer at a speed of 300-500r / min, the reaction temperature is 50℃, and the reaction time is 4h;

[0059] b. The mixture obtained in step a is filtered or centrifuged to obtain a solid substance, and the solid substance is repeatedly washed with deionized water until the pH is 7.0;

[0060] c. Place the solid material obtained in step b into a 50°C oven for 24h;

[0061] d. Add 1.0% CaCl2 to the solid obtained after drying in step c and grind for 10 minutes to obtain modified sludge incineration ash.

[0062] e. The modified sludge incineration ash obtained in step d is used for the preparation of M10 plaster mortar. The specific process is as follows:

[0063] (1) P·O42.5 ordinary silicate cement, fly ash (Loucheng grade II ash), modified sludge incineration ash, medium sand (purchased from Xiamen Ace Standard Sand Co., Ltd., with a particle size range of 0.5-1 mm) and cellulose ether (purchased from Shanghai Shangnan New Materials Co., Ltd., brand: HK 40000S, type: HPMC) were weighed and stirred according to mass. After mixing evenly, a dry mortar powder was prepared. The specific ratio was: cement: fly ash: modified sludge incineration ash: medium sand = 15:7:3:100; the amount of cellulose ether added was 0.02% of the total mass of cement, fly ash, modified sludge incineration ash and medium sand.

[0064] (2) Add water to the dry mortar powder obtained in step (1), add water while stirring, mix the dry mortar powder and water evenly, and obtain a premixed mortar. The amount of water added is about 15% of the total mass of the dry mortar powder.

[0065] The chemical components and strength activity index of the sludge incineration ash before pretreatment and the sludge incineration ash obtained in step c were tested, and the test results are shown in Table 3. The sludge incineration ash obtained in step d was used to prepare plaster mortar with a strength grade of M10, and the compressive strength and tensile bond strength of the mortar were measured. The test results are shown in Table 4.

[0066] Table 3 Performance indicators of sludge incineration ash before and after pretreatment

[0067]

[0068] Table 4 Performance indicators of mortar

[0069] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 8.2 15.1 0.42 GB / T 25181-2019 / ≥10.0 ≥0.2

[0070] As shown in Table 3, after pretreatment, the P2O5 content of the sludge incineration ash decreased from 14.14% to 8.25%, a decrease of 41.7%, and the 28d intensity activity index increased from 48.2% to 68.9%, an increase of 42.9%. It can be seen that the method of the present invention successfully reduces the P2O5 content in the sludge incineration ash and improves the activity of the sludge incineration ash.

[0071] It can be seen from Table 4 that the mortar prepared with the sludge incineration ash obtained in step d has a 28d compressive strength of 15.5 MPa and a 14d tensile bond strength of 0.42 MPa, and the performance meets the mechanical properties requirements of "Premixed Mortar" (GB / T 25181-2019).

[0072] Example 3

[0073] A method and application for controlling ash phosphorus from sludge incineration, the specific steps are:

[0074] a. Mix 30g of sludge incineration ash with 500ml of 0.8mol / L KOH solution, stir on a magnetic stirrer at a speed of 300-500r / min, the reaction temperature is 50℃, and the reaction time is 4h;

[0075] b. The mixture obtained in step a is filtered or centrifuged to obtain a solid substance, and the solid substance is repeatedly washed with deionized water until the pH is 7.0;

[0076] c. Place the solid material obtained in step b into a 50°C oven for 24h;

[0077] d. Add 0.6% CaSO4 to the solid obtained after drying in step c and grind for 10 minutes to obtain modified sludge incineration ash.

[0078] e. The modified sludge incineration ash obtained in step d is used for the preparation of M10 plaster mortar. The specific process is as follows:

[0079] (1) P·O42.5 ordinary silicate cement, fly ash (Loucheng grade II ash), modified sludge incineration ash, medium sand (purchased from Xiamen Ace Standard Sand Co., Ltd., with a particle size range of 0.5-1 mm) and cellulose ether (purchased from Shanghai Shangnan New Materials Co., Ltd., brand: HK 40000S, type: HPMC) were weighed and stirred according to mass. After mixing evenly, a dry mortar powder was prepared. The specific ratio was: cement: fly ash: modified sludge incineration ash: medium sand = 15:7:3:100; the amount of cellulose ether added was 0.02% of the total mass of cement, fly ash, modified sludge incineration ash and medium sand.

[0080] (2) Add water to the dry mortar powder obtained in step (1), add water while stirring, mix the dry mortar powder and water evenly, and obtain a premixed mortar. The amount of water added is about 15% of the total mass of the dry mortar powder.

[0081] The chemical components and strength activity index of the sludge incineration ash before pretreatment and the sludge incineration ash obtained in step c were tested, and the test results are shown in Table 5. The sludge incineration ash obtained in step d was used to prepare plaster mortar with a strength grade of M10, and the compressive strength and tensile bond strength of the mortar were measured. The test results are shown in Table 6.

[0082] Table 5 Performance indicators of sludge incineration ash before and after pretreatment

[0083]

[0084] Table 6 Performance indicators of mortar

[0085] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 6.9 12.5 0.40 GB / T 25181-2019 / ≥10.0 ≥0.2

[0086] As shown in Table 5, after pretreatment, the P2O5 content of the sludge incineration ash decreased from 13.97% to 9.05%, a decrease of 35.2%, and the 28d intensity activity index increased from 47.3% to 60.2%, an increase of 27.3%. It can be seen that the method of the present invention successfully reduces the P2O5 content in the sludge incineration ash and improves the activity of the sludge incineration ash.

[0087] It can be seen from Table 6 that the mortar prepared with the sludge incineration ash obtained in step d has a 28d compressive strength of 12.5 MPa and a 14d tensile bond strength of 0.40 MPa, and the performance meets the mechanical properties requirements of "Premixed Mortar" (GB / T 25181-2019).

[0088] Comparative Example 1

[0089] Compared with Example 1, the difference is that untreated sludge incineration ash is directly used to prepare plaster mortar with strength grade M10, and the compressive strength and tensile bond strength of the mortar are measured. The test results are shown in Table 7.

[0090] Table 7 Performance indicators of mortar

[0091] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 4.5 7.8 0.12 GB / T 25181-2019 / ≥10.0 ≥0.2

[0092] It can be seen from Table 7 that the mortar prepared with untreated sludge incineration ash has a 28d compressive strength of 7.8 MPa and a 14d tensile bond strength of 0.12 MPa, and its performance does not meet the mechanical properties requirements of "Premixed Mortar" (GB / T 25181-2019).

[0093] Comparative Example 2

[0094] Compared with Example 1, the difference is that no calcium-based additive is added, and only the sludge incineration ash obtained in step c is used to prepare plaster mortar with a strength grade of M10. The compressive strength and tensile bond strength of the mortar are measured. The test results are shown in Table 8.

[0095] Table 8 Performance indicators of mortar

[0096] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 5.5 9.6 0.13 GB / T 25181-2019 / ≥10.0 ≥0.2

[0097] It can be seen from Table 6 that the mortar prepared by using the sludge incineration ash obtained in step c has a 28d compressive strength of 9.6 MPa and a 14d tensile bond strength of 0.13 MPa, and the performance does not meet the mechanical properties requirements in "Premixed Mortar" (GB / T 25181-2019).

[0098] Comparative Example 3

[0099] Compared with Example 1, the difference is that the concentration of NaOH solution is 3.0 mol / L, and the other steps remain the same. The chemical components and strength activity index of the sludge incineration ash before pretreatment and the sludge incineration ash obtained in step c are tested, and the test results are shown in Table 9. The sludge incineration ash obtained in step d is prepared into a plaster mortar with a strength grade of M10, and the compressive strength and tensile bond strength of the mortar are measured. The test results are shown in Table 10.

[0100] Table 9 Performance indicators of sludge incineration ash before and after pretreatment

[0101]

[0102] Table 10 Performance indicators of mortar

[0103] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 7.5 13.8 0.42 GB / T 25181-2019 / ≥10.0 ≥0.2

[0104] As shown in Table 8, the mortar prepared by using the sludge incineration ash obtained in step c has a 28d compressive strength of 13.8MPa and a 14d tensile bond strength of 0.42MPa, which meets the mechanical property requirements of "Premixed Mortar" (GB / T 25181-2019). It is comparable to the mortar prepared by using sludge incineration ash pretreated with 1.0mol / L NaOH solution, and has no obvious advantages. In addition, alkali-aggregate reaction is prone to occur after high-concentration alkali forming mortar, resulting in expansion and deformation of the specimen.

[0105] Comparative Example 4

[0106] Compared with Example 1, the difference is that the phosphorus in the sludge incineration ash is not pretreated. Instead, the sludge incineration ash composite admixture obtained by ball milling for 10 minutes and compounding with fly ash is used to replace part of the raw materials in the mortar (admixture, treated sludge incineration ash) to prepare plastering mortar with strength grade M10, and the compressive strength and tensile bond strength of the mortar are measured. The test results are shown in Table 11.

[0107] Table 11 Performance indicators of mortar

[0108] Test items 7d compressive strength / MPa 28d compressive strength / MPa 14d tensile bond strength / MPa Test results 6.3 10.7 0.32 GB / T 25181-2019 / ≥10.0 ≥0.2

[0109] It can be seen from Table 9 that the mortar prepared with sludge incineration ash composite admixture has a 28d compressive strength of 10.7 MPa and a 14d tensile bond strength of 0.32 MPa, which meet the mechanical properties requirements of "Premixed Mortar" (GB / T 25181-2019), but are lower than the mechanical properties of the mortar prepared by the technical means in the patent of this invention.

[0110] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0111] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0112] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0113] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A method for preparing modified sludge incineration ash, characterized in that: The following steps are involved: 1) mixing sludge incineration ash with an alkaline solution to react and obtain a first substance; 2) removing liquid from the first substance, washing until the pH value is 6.5 to 7.5, and drying to obtain a second substance; 3) Mixing the second substance with a calcium-based additive to obtain modified sludge incineration ash.

2. The preparation method according to claim 1, characterized in that In the step 1), The alkaline solution is an aqueous solution of NaOH or KOH, preferably, the concentration of the alkaline solution is 0.5-1.5 mol / L, more preferably, the concentration of the alkaline solution is 0.8-1.0 mol / L; and / or, the mass volume ratio of sludge incineration ash to alkaline solution is (1-5):50; and / or, the stirring speed during mixing is 300 to 500 r / min; and / or, the reaction temperature is 40-60°C, preferably, the reaction temperature is 50°C; and / or, the reaction time is 4 h to 6 h; And / or, the sludge incineration ash is taken from a sewage treatment plant, and the total mercury in the sludge incineration ash is ≤5mg / / kg, the total arsenic is ≤75mg / / kg, the total cadmium is ≤5mg / / kg, the total chromium is ≤600mg / / kg, and the total lead is ≤300mg / / kg.

3. The preparation method according to claim 1, characterized in that: In the step 2), the liquid is removed by filtration or centrifugation; And / or, in step 2), washing to a pH of 7.0; And / or, in the step 2), the drying temperature is 40-60°C, preferably, the drying temperature is 50°C; And / or, in step 2), the drying time is 20 to 28 hours, preferably, the drying time is 24 hours; And / or, in step 3), the calcium-based additive includes any one or more of CaCl2, CaO, Ca(OH)2 or CaSO4; And / or, in step 3), the mass ratio of the second substance to the calcium-based additive is (90.0-99.5): (0.5-10.0), Preferably, the mass ratio of the second substance to the calcium-based additive is (98.5-99.0): (1.0-1.5); And / or, in the step 3), after the second substance is mixed with the calcium-based additive, it is necessary to grind them to obtain the modified sludge incineration ash.

4. Modified sludge incineration ash prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the modified sludge incineration ash according to claim 4 in preparing mortar.

6. The use according to claim 5, characterized in that The mortar is a premixed mortar, preferably, the mortar is a plaster mortar, and more preferably, the mortar is an M10 plaster mortar.

7. A mortar, wherein the raw materials for preparing the mortar include the modified sludge incineration ash as described in claim 4.

8. The mortar according to claim 7, characterized in that The raw materials for preparing the mortar include water and dry powder, the dry powder includes cellulose ether and mortar dry powder, and the mortar dry powder includes any one or more of cement, fly ash, medium sand or modified sludge incineration ash.

9. The mortar according to claim 8, characterized in that The mass ratio of the cellulose ether to the mortar dry powder is (0.01-0.03):(95-105), preferably, the mass ratio of the cellulose ether to the mortar dry powder is 0.02:99.98; And / or, the mortar dry powder comprises cement, fly ash, modified sludge incineration ash and medium sand, preferably, the mass ratio of the cement, fly ash, modified sludge incineration ash and medium sand is (10-20):(5-9):(1-5):(80-120), more preferably, the mass ratio of the cement, fly ash, modified sludge incineration ash and medium sand is 15:7:3:100; And / or, the fly ash is Loucheng grade II ash; And / or, the medium sand particle size ranges from 0.5 to 1 mm; And / or, the cement is P·O42.5 ordinary Portland cement; And / or, the mass ratio of water to dry powder is (10-20):(80-120), preferably, the mass ratio of water to dry powder is 15:100; And / or, the mortar is a premixed mortar, preferably, the mortar is a plaster mortar, more preferably, the mortar is M10 plaster mortar.

10. The method for preparing mortar according to any one of claims 7 to 9, characterized in that: The raw materials for preparing the mortar according to any one of claims 7 to 9 are mixed.

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