A composite phosphate cementitious material based on solid waste and its preparation method

Abstract

This invention relates to a fully solid waste-based composite phosphate cementitious material, comprising the following raw materials in parts by weight: 30-80 parts waste magnesia-carbon bricks, 20-55 parts converter steel slag, 1-10 parts zinc-containing dust, 15-60 parts phosphate; 1-8 parts retarder, 1.5-5 parts water-reducing agent; 2-7 parts steel slag modified grinding agent, and 1.5-4 parts triethanolamine. This invention uses waste magnesia-carbon bricks and steel slag as the main raw materials. First, the waste magnesia-carbon bricks and zinc-containing dust are co-calcined, utilizing the inert zinc ferrite phase in the dust to react with the residual carbon in the waste magnesia-carbon bricks to generate active FeO and ZnO. Simultaneously, the steel slag is acid-modified to improve its reactivity. Then, the two modified raw materials are combined and reacted with phosphate to prepare the fully solid waste-based composite phosphate cementitious material. The prepared fully solid waste-based composite phosphate cementitious material exhibits rapid setting time, high compressive strength, and excellent water resistance, making it suitable for emergency repair and reconstruction of cement concrete structures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cementitious materials and building materials, in particular to a full solid waste-based composite phosphate cementitious material and a preparation method thereof. BACKGROUND

[0002] Phosphate cementitious material is a new type of inorganic cementitious material based on phosphate chemical bonding principle, which is usually formed by the reaction of metal oxides (Mg, Ca, Zn, Fe, Al) and acid phosphate under the action of water. It is between traditional ceramic materials and cement materials, so it also has the excellent properties of both materials. Among them, magnesium phosphate cementitious material has short setting time, high early strength, good wear resistance and strong heavy metal solidification ability, and is suitable for rapid repair and hazardous waste solidification fields. However, the raw material of magnesium phosphate cementitious material is heavy-burned magnesium oxide, which is obtained by grinding magnesite calcined at 1500-1700℃, so the energy consumption is very large, the preparation cost is high, and it is not low-carbon and environmentally friendly, which limits the further application of magnesium phosphate cementitious material.

[0003] Invention patent CN107827381A discloses a magnesium phosphate cementing agent and cementitious material. The cementitious material prepared by using heavy-burned magnesium oxide and waste concrete powder has strength performance meeting the use requirements, reduces production cost, and is also beneficial to environmental protection, but still needs to use heavy-burned magnesium oxide.

[0004] Invention patent CN117263646A discloses a solid waste-based phosphate grouting reinforcement material and a preparation method thereof. The solid waste-based phosphate grouting reinforcement material is formed by using red mud rich in metal oxides to partially replace heavy-burned magnesium oxide, and adding mineral admixtures and high-temperature resistant agents. It realizes large-scale utilization of solid waste with high additional value, and improves the high-temperature setting time and high-temperature water resistance of phosphate cementitious material, but red mud only partially replaces heavy-burned magnesium oxide.

[0005] The inventor's previous patent CN202211388918.9 discloses a preparation method of phosphate cementitious material. High-temperature co-calcination of magnesite and secondary aluminum ash is adopted, and copper slag and manganese slag are added. The prepared phosphate cementitious material realizes efficient resource utilization of hazardous solid waste secondary aluminum ash, and has the characteristics of fast hardening, early strength, high strength, good volume stability and strong durability, but still needs high-temperature calcination of magnesite, and the energy consumption is also high.

[0006] Therefore, it is of great significance to expand the material range, find new technologies and methods to effectively reduce the preparation cost and carbon emission of magnesium phosphate cementitious material for its further use.

[0007] Magnesia-carbon brick, namely MgO-C brick, is the main refractory material for the working lining of converter and ladle, and its main components are MgO, graphite C, SiO2, Al, wherein the content of MgO is usually more than 50%. During the use of MgO-C brick, it will be eroded by molten steel and steel slag, and the metal aluminum powder and part of the graphite carbon and silicon powder in it will react to form Al4C3 and SiC. When the MgO-C brick reaches the service life, it needs to be replaced with new MgO-C brick. In the past, due to the low cost and wide source of raw materials, the waste MgO-C brick generated by replacement was usually simply discarded and stored as garbage. With the influence of depletion of high-quality raw material resources and environmental protection policy, in recent years, the recycling of waste MgO-C brick has gradually been valued by people. At present, waste MgO-C brick has been used to prepare regenerated MgO-C brick, synthesize magnesia-alumina spinel, prepare converter modifier and tundish dry material, etc., but these researches on waste MgO-C brick are all focused on the preparation of regenerated products, and the research on the whole powder of waste MgO-C brick is very little. There is almost no report on the application of MgO-C brick powder in phosphate cementing materials.

[0008] Steel slag is the main solid waste of steel enterprises, and about 0.15-0.20 tons of steel slag is discharged per ton of crude steel produced. According to statistics, the steel slag discharge in China in 2022 reached about 150 million tons, and the overall utilization rate of steel slag is only 30%. A large amount of steel slag will not only occupy valuable land resources, but also cause all-round pollution to the surrounding environment of the storage site. Steel slag mainly includes dicalcium silicate, tricalcium silicate, RO phase, free calcium oxide, free magnesium oxide and elemental iron, etc. Among them, dicalcium silicate and tricalcium silicate have hydration activity, but free calcium oxide and free magnesium oxide are difficult to digest, which leads to the expansion and cracking of steel slag products, poor stability; In addition, the high hardness of the iron oxide and magnesium oxide in the steel slag will lead to low grinding efficiency, and the specific surface area and reactivity of the ground steel slag powder often cannot meet the use requirements. At present, the utilization of steel slag in the field of Portland cementing materials has achieved certain results, such as the use of steel slag to prepare auxiliary cementing materials, concrete aggregate and road materials, etc., but the key problems such as difficult grinding, low activity and stability of steel slag limit its further safe and stable utilization in cementing material system, and the application research of steel slag in phosphate cement is also less. SUMMARY

[0009] In view of the above problems that the preparation of the phosphate cement material is single in material selection, high in energy consumption, not low-carbon and environment-friendly enough, and the waste magnesite-carbon brick and steel slag cannot be efficiently utilized, the present application provides a full solid waste-based composite phosphate cement material and a preparation method thereof, and the prepared cement material has fast setting time, high compressive strength, strong volume stability and excellent water resistance. The present application uses two solid wastes, i.e., waste magnesite-carbon brick rich in MgO and steel slag rich in CaO, as main raw materials to prepare the full solid waste-based composite phosphate cement material. The waste magnesite-carbon brick and the steel slag are modified respectively, so that the adverse elements in the waste magnesite-carbon brick are converted into useful substances, and the reactivity of the steel slag is improved. Then, the two modified raw materials are used in combination with phosphate to prepare the full solid waste-based composite phosphate cement material.

[0010] To achieve the above-mentioned object, the technical scheme of the present application is as follows:

[0011] A full solid waste-based composite phosphate cement material, comprising the following raw materials in mass parts: 30-80 parts of waste magnesite-carbon brick, 20-55 parts of converter steel slag, 1-10 parts of zinc-containing dust, 15-60 parts of phosphate, 1-8 parts of a retarder, 1.5-5 parts of a water reducing agent, 2-7 parts of a steel slag modification grinding agent, and 1.5-4 parts of triethanolamine.

[0012] MgO has short setting time, high early strength, but poor water resistance when used as a phosphate cement material; CaO has long setting time and low strength when used as a phosphate cement material; the waste magnesite-carbon brick rich in MgO and the steel slag rich in CaO are used in combination to prepare a composite phosphate cement material, each component plays its own characteristics, and the steel slag can play the effects of "micro aggregate" and "filling", so as to improve the micro cracks and gaps of the matrix, thereby the strength performance and water resistance of the prepared phosphate cement material are obviously improved. In addition, the residual carbon in the waste magnesite-carbon brick is an adverse element, the inert zinc ferrite phase (ZnFe2O4) in the zinc-containing dust reacts with the residual carbon in the waste magnesite-carbon brick at high temperature to form FeO and ZnO with reactivity, and the FeO and ZnO can together with the MgO in the waste magnesite-carbon brick to have a hydration reaction with the phosphate, so that the "carbon removal" is changed into "carbon utilization".

[0013] Further, the MgO content in the waste magnesite-carbon brick is 50wt.%-70wt.%, and the water content is less than 1wt.%; the waste magnesite-carbon brick is crushed and sieved, and then ground in a ball mill with the zinc-containing dust and triethanolamine as a grinding aid, so that the specific surface area of the powder as a whole reaches 300-350m 2 / kg, and the particle size D50 is 25-30μm.

[0014] Further, the zinc-containing dust is one or more of blast furnace gas dust, converter dust and electric furnace dust produced by a steel plant, the total content of ZnO and ZnFe2O4 in the composition is 15wt.%-25wt.%, and the water content is less than 1wt.%.

[0015] Further, the zinc-containing dust is 3-10 parts, for example, 3 parts, 4 parts, 6 parts, 8 parts, and the mass ratio of the waste magnesite carbon brick to the zinc-containing dust is 8-12:1.

[0016] Further, the CaO content in the chemical composition of the converter steel slag is 40wt.%-50wt.%, the total content of CaO, MgO and Fe2O3 is 65wt.%-75wt.% of the total content, and the water content is less than 1wt.%;the specific surface area of the modified and ground converter steel slag is 400-450m 2 / kg, and the particle size D50 is 15-20μm.

[0017] Further, the phosphate is at least one of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, and is of an industrial pure grade with a mass purity of more than 95%.

[0018] Further, the retarder is at least one of boric acid, borax pentahydrate and disodium hydrogen phosphate, and is of an industrial pure grade;the water reducing agent is a polycarboxylic acid water reducing agent.

[0019] Further, the steel slag modification grinding agent is anhydrous ethanol solution of an acidic reagent, the acidic reagent is at least one of phosphoric acid (industrial pure, 85wt.%) or acetic acid (industrial pure, 85wt.%), and the specific preparation method of the steel slag modification grinding agent is as follows: the acidic reagent is uniformly dissolved in anhydrous ethanol at a proportion of 1wt.%-10wt.%, a stirrer is used for stirring until the components are fully mixed and uniformly dispersed.

[0020] The second object of the present application provides a preparation method of the full-solid-waste-based composite phosphate cementing material, which comprises the following steps:

[0021] (S1) mixing and calcining: the waste magnesite carbon brick is first crushed and sieved, then mixed with the zinc-containing dust, and then ground by adding triethanolamine as a grinding aid to obtain a waste magnesite carbon brick-zinc-containing dust mixed powder;the mixed powder is calcined and sieved to form a mixed clinker.

[0022] (S2) steel slag modification: the steel slag is pretreated by crushing and sieving, and then modified by grinding with a modified grinding agent by spraying in a cement mill to obtain a modified ground steel slag powder.

[0023] (S3) Hydration: Dissolve the phosphate in water, and stir at a low speed of 60-80 r / min for 40-70 s; after the phosphate is fully dissolved, add the modified ground steel slag powder in step (S2), first stir at a speed of 200-300 r / min for 30-50 s, then stir at a speed of 300-600 r / min for 80-120 s, and add the retarder and water reducing agent; after uniform mixing and stirring, add the mixed clinker in step (S1) to obtain a phosphate cementitious material slurry.

[0024] (S4) Curing: Pour the cementitious slurry obtained in step (S3) into a mold, vibrate on a vibration table for 90-120 s to form, and then place in an indoor environment for preliminary curing; after demolding, continue curing to the corresponding age to obtain a composite phosphate cementitious material.

[0025] There are a large number of pseudo-particles coexisting with the matrix in the initially crushed particles of the waste magnesium carbon brick, the pseudo-particles are usually less than 1 mm, have low bulk density, and have many pores and crack defects, which will significantly reduce the bulk density of the product during reuse, and secondary crushing is prone to occur during molding, affecting the mechanical properties of the product, so the pseudo-particles of the waste magnesium brick powder need to be removed. The pseudo-particles are removed by grinding to a smaller particle size in step (S1).

[0026] Further, the grinding time in step (S1) is 20-40 min, and the calcination temperature is 600-900 ℃ for 0.5-1.5 h.

[0027] Further, the grinding time in step (S2) is 45-90 min.

[0028] Further, the indoor curing condition in step (S4) is 23±2 ℃ and 50±5% relative humidity.

[0029] The basic principle of the present application is explained as follows:

[0030] The waste magnesium carbon brick rich in MgO and the steel slag rich in CaO are used together to prepare a composite phosphate cementitious material, each component can exert its own characteristics, at the same time, the steel slag can play the effects of "micro aggregate" and "filling", improving the micro cracks and gaps of the matrix, so that the strength performance and water resistance of the prepared composite phosphate cementitious material are improved. In addition, the residual carbon of the waste magnesium carbon brick is an unfavorable element, which will deposit on the surface of the MgO particles, hinder the hydration reaction with the phosphate, and thus reduce the strength of the cementitious material; and the low reactivity and poor stability of the steel slag will also reduce the strength of the cementitious material and prolong the setting time. Therefore, before being used to prepare the phosphate cementitious material, the waste magnesium carbon brick and the steel slag need to be modified and pretreated.

[0031] In steel mill zinc-containing dust, useful Fe and Zn elements mainly exist in the form of ZnO and inert zinc ferrite phase (ZnFe2O4). When zinc-containing dust is co-calcined with magnesia-carbon bricks, the residual carbon in the waste magnesia-carbon bricks undergoes a carbothermic reduction reaction with the inert zinc ferrite phase in the zinc-containing dust, generating reactive FeO and ZnO. Based on the principle of phosphate chemical bonding, FeO and ZnO can synergistically undergo hydration reactions with phosphates in a neutral to slightly acidic environment with MgO in the waste magnesia-carbon bricks, generating hydration products such as potassium struvite (MgKPO4·6H2O), Fe3(PO4)2·8H2O, and Zn2(OH)PO4 (see attached). Figure 2 (As shown), this process transforms "carbon removal" into "carbon utilization." The relevant reaction equations are as follows:

[0032] MgO+KH2PO4+5H2O=MgKPO4·6H2O

[0033] ZnFe₂O₄ + C = ZnO + 2FeO + CO

[0034] 3ZnFe₂O₄ + C = 3ZnO + 2Fe₃O₄ + CO

[0035] 3ZnFe₂O₄ + CO = 3ZnO + 2Fe₃O₄ + CO₂

[0036] ZnFe₂O₄ + CO = ZnO + 2FeO + CO₂

[0037] Fe3O4 + CO = 3FeO + CO2

[0038] 3Fe 2+ +2PO4 3- +8H₂O→Fe₃(PO₄)₂·8H₂O

[0039] 2Zn 2+ +PO4 3- +OH - →Zn2(OH)PO4

[0040] In-situ modification of steel slag during grinding is achieved using modified grinding agents. The acidic components in the grinding agents disrupt the covalent bonds of the steel slag mineral phases (such as C2S, C3S, C2F, and f-CaO), promoting the mutual dissociation of the mineral phases and generating pre-reaction products such as calcium phosphate. This facilitates the conversion and dissolution of free calcium oxide, reducing the hardness of the steel slag while increasing its specific surface area and reactivity. The modified steel slag powder can also react with phosphates to generate products such as calcium phosphate (reaction formula below). Furthermore, calcium-modified steel slag can improve the microcracks and gaps in the matrix by leveraging the physical "micro-aggregate" and "filling" effects. In summary, the combined effects of physical effects and chemical hydration reactions between magnesia-based waste magnesia-carbon bricks and calcium-based steel slag result in a denser and more compact microstructure in the prepared composite multi-component Mg-Ca-Fe-Zn phosphate cementitious material matrix, further improving its macroscopic mechanical properties and water resistance.

[0041] 3Ca 2+ +2PO4 3- →Ca3(PO4)2

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1) This invention provides a multi-element solid waste co-processing and utilization scheme for steel plants. It uses MgO-rich waste magnesia-carbon bricks and CaO-rich steel slag as main raw materials to prepare a fully solid waste-based phosphate cementitious material, achieving large-scale, high-value-added utilization of steel plant solid waste in a green, low-carbon, and environmentally friendly manner. By rationally selecting the raw material components and their dosages, and through the synergistic effect of each component, the prepared fully solid waste-based composite phosphate cementitious material exhibits rapid setting time, high compressive strength, strong volume stability, and excellent durability, making it suitable for emergency repair and reconstruction of cement concrete structures.

[0044] 2) This invention utilizes the residual carbon in waste magnesia-carbon bricks and zinc-containing dust in a synergistic calcination process at high temperatures to fully utilize the carbon in the waste magnesia-carbon bricks and react it with the inert zinc ferrite phase in the dust to generate reactive FeO and ZnO. This transforms "carbon removal" into "carbon utilization," and the prepared waste magnesia-carbon brick-zinc-containing dust clinker also exhibits good reactivity. Attached Figure Description

[0045] Figure 1 Flowchart of the preparation process for all-solid waste-based phosphate cementitious materials;

[0046] Figure 2 XRD patterns of hydration products of all-solid waste-based phosphate cementitious material after 28 days of curing. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. The following embodiments are provided to facilitate a better understanding of this invention, but do not limit the invention.

[0048] Unless otherwise specified, "parts" in the embodiments of the present invention refers to parts by mass, and "%" refers to percentage by mass unless otherwise specified.

[0049] The waste magnesia-carbon bricks and steel slag both came from a steel company in Tangshan. The MgO content in the waste magnesia-carbon brick powder was 50wt.%-70wt.%, and the moisture content was less than 1wt.%. The CaO content in the converter steel slag was above 40wt.%-50wt.%, and the combined content of CaO, MgO, and Fe2O3 accounted for more than 65wt.%-75wt.% of the total content, with a moisture content less than 1wt.%. The total content of ZnO and ZnFe2O4 in the zinc dust was 15wt.%-25wt.%, with a moisture content less than 1wt.%. Phosphoric acid (85wt.%) was selected as the steel slag modifying grinding agent. Commercially available industrial pure potassium dihydrogen phosphate and ammonium dihydrogen phosphate with a purity of 99% were selected as phosphates. Commercially available industrial pure pentahydrate borax and borax (100 mesh) were selected as retarder.

[0050] Example 1

[0051] Raw material composition (parts by weight): 60 parts waste magnesia-carbon bricks, 30 parts steel slag, 5 parts zinc-containing dust, 45 parts potassium dihydrogen phosphate; 5 parts borax pentahydrate retarder, 5 parts polycarboxylate superplasticizer; 4 parts steel slag modified grinding agent; 2 parts triethanolamine.

[0052] The preparation method includes the following steps:

[0053] (S1) Mixed calcination: Waste magnesia-carbon bricks are first crushed and sieved, then mixed with zinc-containing dust, and triethanolamine is added as a grinding aid for grinding for 30 minutes to obtain a mixed powder of waste magnesia-carbon bricks and zinc-containing dust; the mixed powder is calcined at 900℃ for 0.5 hours and sieved to produce mixed clinker with a specific surface area of ​​340 m². 2 / kg, with a particle size D50 of 29μm.

[0054] (S2) Steel slag modification: Phosphoric acid is uniformly dissolved in anhydrous ethanol at a ratio of 5%, and stirred thoroughly to obtain a modified grinding agent. This agent is then sprayed during the steel slag grinding process to ensure uniform mixing with the steel slag. After grinding in a cement mill for 60 minutes, modified milled steel slag powder with a specific surface area of ​​450 m² is obtained. 2 / kg, with a particle size D50 of 15μm.

[0055] (S3) Hydration reaction: Dissolve potassium dihydrogen phosphate in water and stir at a low speed of 70 r / min for 60 s; after the potassium dihydrogen phosphate is fully dissolved, add the modified milled steel slag powder obtained in step (S2), stir at a speed of 300 r / min for 30 s, then stir at a speed of 500 r / min for 90 s, and add the retarder pentahydrate borax and polycarboxylate superplasticizer; after mixing and stirring evenly, add the mixed clinker obtained in step (S1) to obtain phosphate cementitious material slurry.

[0056] (S4) Curing: The gel slurry obtained in step (S3) is injected into the mold, vibrated on the vibrating table for 120s to form, and then placed in an indoor environment (23±2℃, 50±5% relative humidity) for preliminary curing. After demolding, it continues to be cured to the corresponding age to obtain composite phosphate gel material.

[0057] Example 2

[0058] The rest is the same as in Example 1, except for the raw material composition: 30 parts waste magnesia-carbon bricks, 20 parts steel slag, 3 parts zinc-containing dust, 15 parts potassium dihydrogen phosphate; 1 part borax pentahydrate retarder, 1.5 parts polycarboxylate superplasticizer; 2 parts steel slag modified grinding agent, and 1.5 parts triethanolamine.

[0059] The preparation method includes the following steps:

[0060] (S1) Mixed calcination: Waste magnesia-carbon bricks are first crushed and sieved, then mixed with zinc-containing dust, and triethanolamine is added as a grinding aid for 20 minutes to obtain a mixed powder of waste magnesia-carbon bricks and zinc-containing dust; the mixed powder is calcined at 600℃ for 1 hour and sieved to produce a mixed clinker with a specific surface area of ​​300 m². 2 / kg, with a particle size D50 of 25μm.

[0061] (S2) Steel slag modification: Phosphoric acid is uniformly dissolved in anhydrous ethanol at a ratio of 5%, and stirred thoroughly to obtain a modified grinding agent. This agent is then sprayed during the steel slag grinding process to ensure uniform mixing with the steel slag. The mixture is then ground in a cement mill for 45 minutes to obtain modified milled steel slag powder with a specific surface area of ​​400 m². 2 / kg, with a particle size D50 of 20μm.

[0062] (S3) Hydration reaction: Dissolve potassium dihydrogen phosphate in water and stir at low speed for 50s at 60r / min. After the potassium dihydrogen phosphate is fully dissolved and dispersed, add the modified milled steel slag powder obtained in step (S2), stir at 250r / min for 30s, then stir at 400r / min for 80s, and add the retarder pentahydrate borax and polycarboxylate superplasticizer. After mixing and stirring evenly, add the mixed clinker obtained in step (S1) to obtain phosphate cementitious material slurry.

[0063] (S4) Curing: The gel slurry obtained in step (S3) is injected into the mold, vibrated on the vibrating table for 90 seconds to form, and then placed in an indoor environment (23±2℃, 50±5% relative humidity) for preliminary curing. After demolding, it continues to be cured to the corresponding age to obtain composite phosphate gel material.

[0064] Example 3

[0065] The rest is the same as in Example 1, except for the raw material composition: 80 parts of waste magnesia-carbon bricks, 55 parts of steel slag, 10 parts of zinc-containing dust, 60 parts of potassium dihydrogen phosphate; 8 parts of borax pentahydrate retarder, 5 parts of polycarboxylate superplasticizer; 7 parts of steel slag modified grinding agent, and 4 parts of triethanolamine.

[0066] Example 4

[0067] The rest is the same as in Example 1, except for the raw material composition: 45 parts waste magnesia-carbon bricks, 40 parts steel slag powder, 5 parts zinc-containing dust; 50 parts potassium dihydrogen phosphate; 4 parts borax retarder, 3 parts polycarboxylate superplasticizer; 4 parts steel slag modified grinding agent, and 3 parts triethanolamine.

[0068] Example 5

[0069] The rest is the same as in Example 1, except that ammonium dihydrogen phosphate is used instead of potassium dihydrogen phosphate.

[0070] Comparative Example 1

[0071] The rest is the same as in Example 1, except that the raw material composition is as follows: 60 parts waste magnesia-carbon bricks, 5 parts zinc-containing dust, 30 parts potassium dihydrogen phosphate; 3 parts borax pentahydrate retarder, 3 parts polycarboxylate superplasticizer; 4 parts steel slag modified grinding agent, and 2 parts triethanolamine. That is, steel slag is not used, and step (S3) is correspondingly deleted.

[0072] Comparative Example 2

[0073] The rest is the same as in Example 1, except that the raw material composition is as follows: 30 parts steel slag powder, 15 parts potassium dihydrogen phosphate; 1.5 parts borax pentahydrate retarder, 1.5 parts polycarboxylate superplasticizer; and 4 parts steel slag modified grinding agent. That is, waste magnesia-carbon bricks and zinc-containing dust are not used; only steel slag is used.

[0074] Comparative Example 3

[0075] The rest is the same as in Example 1, except for the raw material composition: 60 parts waste magnesia-carbon bricks, 30 parts steel slag, 45 parts potassium dihydrogen phosphate; 5 parts borax pentahydrate retarder, 5 parts polycarboxylate superplasticizer; 4 parts steel slag modified grinding agent, and 2 parts triethanolamine. That is, zinc-containing dust is not used, and correspondingly, in step (S1), only the waste magnesia-carbon bricks are ground, without calcination.

[0076] The raw material components of the above embodiments and comparative examples are shown in Table 1.

[0077] Test case

[0078] The phosphate gelling materials prepared in the examples and comparative examples were tested for setting time, compressive strength, volume stability and water resistance.

[0079] The compressive strength of the samples was tested according to standard GB / T17671-1999 "Test Method for Strength of Cement Mortar"; the setting time, volume stability, and water resistance were tested according to standard JC / T2537-2019 "Magnesium Phosphate Repair Mortar". The performance data shown in Table 2 below were obtained according to the test methods:

[0080] Table 1 Raw material composition (parts by mass)

[0081]

[0082]

[0083] Table 2 Performance Data

[0084]

[0085] As can be seen from the table above, the solid waste composite phosphate gelling materials prepared in the embodiments of the present invention, especially the preferred embodiments 1-4 and embodiment 7, have high compressive strength, short setting time, and good water resistance.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A full solid waste-based composite phosphate cement material, characterized by, The raw materials include the following quality parts: waste magnesite carbon brick 30-80 parts, converter steel slag 20-55 parts, zinc-containing dust 1-10 parts, phosphate 15-60 parts; retarder 1-8 parts, water reducing agent 1.5-5 parts; steel slag modified grinding agent 2-7 parts, triethanolamine 1.5-4 parts; the steel slag modified grinding agent is anhydrous ethanol solution of acidic reagent, and the acidic reagent is at least one of phosphoric acid or acetic acid; the preparation method of the steel slag modified grinding agent is: the acidic reagent is uniformly dissolved in anhydrous ethanol at a ratio of 1 wt.% to 10 wt.%; the full-solid-waste-based composite phosphate cementing material is prepared by the following preparation method: (S1) mixing and calcining: the waste magnesite carbon brick is first crushed and sieved, then mixed with zinc-containing dust, and then ground with triethanolamine as a grinding aid to obtain a waste magnesite carbon brick-zinc-containing dust mixture; the mixture is calcined and sieved to obtain a mixed clinker; (S2) steel slag modification: the steel slag is pretreated by crushing and sieving, then modified by spraying the modified grinding agent, and then ground in a cement mill to obtain modified ground steel slag powder; (S3) hydration reaction: the phosphate is dissolved in water and stirred at a speed of 60-80 r / min for 40-70 s; after the phosphate is fully dissolved, the modified ground steel slag powder in step (S2) is added, first stirred at a speed of 200-300 r / min for 30-50 s, then stirred at a speed of 300-600 r / min for 80-120 s, and then the retarder and the water reducing agent are added; after uniform mixing and stirring, the mixed clinker in step (S1) is added to obtain a phosphate cementing material slurry; (S4) curing: the cementing slurry obtained in step (S3) is poured into a mold, vibrated on a vibration table for 90-120 s to form a shape, then placed in an indoor environment for preliminary curing, and after demolding, the curing is continued to the corresponding age to obtain a composite phosphate cementing material.

2. The full solid waste-based composite phosphate cement material according to claim 1, characterized in that, The MgO content in the waste magnesite carbon brick is 50 wt.%-70 wt.%, and the water content is less than 1 wt.%;The waste magnesite carbon brick is crushed, sieved and sieved, and zinc-containing dust is added in a ball mill with triethanolamine as a grinding aid, and the obtained powder has a specific surface area of 300-350m 2 / kg, and the particle size D50 is 25-30μm.

3. The full solid waste-based composite phosphate cement material according to claim 1, characterized in that, The zinc-containing dust is at least one of blast furnace gas dust, converter dust and electric furnace dust produced by a steel plant, and the total content of ZnO and ZnFe2O4 in the composition is 15 wt.% to 25 wt.%, and the water content is less than 1 wt.%.

4. The full-solid-waste-based composite phosphate cement material according to claim 1, characterized in that, The mass ratio of the waste magnesite carbon brick to the zinc-containing dust is 8-12:

1.

5. The full-solid-waste-based composite phosphate cement material according to claim 1, characterized in that, The CaO content in the converter steel slag chemical composition is 40 wt.%-50 wt.%, the total content of CaO, MgO and Fe2O3 is 65 wt.%-75 wt.% of the total content, and the water content is less than 1 wt.%; the specific surface area of the modified and ground converter steel slag is 400-450 m 2 / kg, and the particle size D50 is 15-20 μm.

6. The full-solid-waste-based composite phosphate cement material according to claim 1, characterized in that, The phosphate is at least one of potassium dihydrogen phosphate or ammonium dihydrogen phosphate; the retarder is at least one of boric acid, borax pentahydrate and disodium hydrogen phosphate; and the water reducing agent is a polycarboxylic acid water reducing agent.

7. The full-solid-waste-based composite phosphate cement material according to claim 1, characterized in that, In step (S1), the grinding time is 20-40 min, the calcination temperature is 600-900℃, and the calcination time is 0.5-1.5 h; in step (S2), the grinding time is 45-90 min.

8. The full-solid-waste-based composite phosphate cement material according to claim 1, characterized in that, In step (S4), the conditions of the indoor environment are 23±2℃ and 50±5% relative humidity.

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