Cementing material prepared based on zinc slag as well as preparation method and application thereof

Abstract

The invention relates to a cementing material prepared on the basis of zinc slag and a preparation method and application thereof in the technical field of inorganic cementing materials. The cementing material comprises the following components in parts by weight: 60-70 parts of modified zinc slag powder; 25-35 parts by weight of slag powder; 5-10 parts by weight of gypsum; wherein the chemical components of the modified zinc slag powder meet the condition that in terms of CaO, the mass fraction of Ca is 50%-55%; in terms of SO3, the mass fraction of the element S is greater than 5%; in terms of CaF2, the mass fraction of the element F is greater than 0.8%; in terms of GeO, the mass fraction of the Ge element is greater than 0.5%; the initial setting time of the cementing material is longer than or equal to 30 min, and the final setting time of the cementing material is shorter than or equal to 50 min; the volume performance is stable, and the volume change rate in the hardening process is smaller than or equal to 0.1%; and application scenes such as concrete cracking repair and grouting construction can be well met, the connection reliability of building components is improved, and the construction quality is improved.

Description

Technical Field

[0001] This invention relates to the field of inorganic cementitious materials technology, and in particular to a cementitious material prepared based on zinc slag, its preparation method, and its application. Background Technology

[0002] my country's zinc smelting capacity accounts for about half of the world's total output. It is estimated that my country produces approximately 6 million tons of waste slag annually, of which over 5 million tons are hazardous waste from smelting leaching. Less than 2 million tons of leaching slag can be treated harmlessly using rotary kilns or fumigation methods. At least 50% of the total leaching slag production (3 million tons) remains unutilized and urgently needs treatment.

[0003] In the zinc smelting process, the tailings produced often contain rare metals such as indium and germanium, in addition to naturally occurring elements like Si, Ca, and Al. However, the germanium content in the raw ore is relatively low, averaging about 250 g / t. This results in germanium remaining in the zinc slag during beneficiation and subsequent smelting processes, leading to a waste of germanium.

[0004] Reinforced concrete structures are currently the most widespread and widely used building form. Due to the composition of cement and aggregate raw materials, as well as the erosion caused by external environmental conditions, cracking inevitably occurs in concrete structures during their service life. Cracking severely affects the performance of concrete structures and can even lead to structural failure and major accidents such as building collapse. Repairing cracks in existing concrete structures is a major challenge facing the construction industry in the future. Meanwhile, applications such as grouting in bridge and tunnel construction, and the connection of prefabricated building components, all require materials with good compatibility with existing interfaces, excellent bonding performance, and good volume stability to meet application requirements. Currently, commonly used inorganic grouting materials have insufficient bonding performance and poor volume stability control, while organic grouting materials are prone to aging and failure, and are also costly.

[0005] Given the difficulty in effectively utilizing existing zinc smelting slag, we adopted zinc slag as the main component and designed a special cementitious material based on zinc slag for applications such as concrete structure repair and grouting connections, thus finding a way to utilize the resources of zinc slag. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention discloses a cementitious material prepared based on zinc slag, its preparation method, and its application.

[0007] This invention utilizes the fact that germanium, under certain conditions, can replace some silicon and enter the silicate mineral lattice to form minerals such as calcium germanate. Compared with ordinary silicate cement, it possesses better cementitious properties. Specifically, it exhibits good volume stability, excellent bonding performance, good compatibility with existing concrete interfaces, and the cementitious material containing calcium germanate sets faster and has stable strength growth without shrinkage. By adding limestone, gypsum, and calcium fluoride to the undisturbed zinc slag to increase the Ca, S, and F content, and if necessary, oxidizing germanium to increase the Ge content, and then modifying it through high-temperature chemical reconstruction, the cementitious properties are fully realized. During the calcination process, the main minerals in the zinc slag, such as mica, quartz, calcite, and pyrite, undergo decomposition or crystal transformation. They react with CaO formed from the decomposition of limestone, undergoing chemical reconstruction to form high-temperature minerals such as CA, CF, C12A7, and C2F. These metastable substances possess high chemical reactivity and quickly react with other components in the cementitious material, such as the slag, upon contact with water, improving the mechanical properties and volume expansion performance of the cementitious material. Furthermore, during high-temperature heating, sulfur (S) and phosphorus (F) elements have a mineralizing effect on the decomposition of zinc slag and limestone minerals. Through the formation of transition compounds such as anhydrous calcium sulfoaluminate (4CaO•3Al2O3•SO3) with CaO and SiO2, they enhance the early strength of the cementitious material and promote solid-phase chemical reactions. Simultaneously, residual metals such as lead (Pb), zinc (Zn), cadmium (Cd), indium (In), and silver (Ag) in the tailings dissolve in the newly formed silicate and aluminate lattices, playing a role in chemical solidification.

[0008] Slag, a waste product generated during iron smelting, is a potential hydraulic cementitious material. Under the stimulation of alkaline substances such as Ca(OH)₂ and sulfates, the active substances in the slag dissolve and harden through recrystallization and lattice reconstruction, thus exhibiting cementitious properties. Furthermore, the high alkalinity environment provided by modified zinc slag (pH > 13 after adding water) and the addition of gypsum to increase sulfate content further enhance its cementitious properties.

[0009] To achieve the above objectives, the present invention specifically adopts the following technical solution: A cementitious material based on zinc slag includes 60-70 parts by weight of modified zinc slag powder, 25-35 parts by weight of slag powder, and 5-10 parts by weight of gypsum. The chemical composition of the modified zinc slag powder meets the following conditions: The mass fraction of Ca, calculated as CaO, is 50%–55%. The mass fraction of sulfur (S) in SO3 is greater than 5%. The mass fraction of F element in CaF2 is greater than 0.8%; The mass fraction of Ge element, calculated as GeO, is greater than 0.5%.

[0010] Furthermore, the modified zinc slag powder is prepared by adding limestone, gypsum, calcium fluoride, and germanium oxide to the original zinc slag discharged from the zinc smelting industry for chemical component modification, and then heat treatment.

[0011] Furthermore, the preparation method of the modified zinc slag powder includes the following steps: Drying: Dry the raw zinc slag until the moisture content is ≤1.5%; Chemical modification: Based on the chemical composition determination results of the dried original zinc slag, limestone, gypsum, calcium fluoride and germanium oxide are added and mixed to make the chemical composition of the mixture meet the requirements of the above-mentioned claims; One-time grinding: Ball mill the mixture for 5-10 minutes. The residue on the 45μm sieve after grinding should be less than 5%. Calcination: Heat to 900-950℃ at a heating rate of 20-25℃ / min, and hold for 2-3 minutes; Rapid cooling: Cools to room temperature within 30 minutes.

[0012] Furthermore, the undisturbed zinc slag is dried using natural drying or oven drying methods. Furthermore, the slag powder is S95 pure slag powder that conforms to the GB / T 18046-2008 standard "Slag powder for use in cement and concrete".

[0013] Furthermore, the gypsum used is natural gypsum or industrial by-product gypsum, and the SO3 mass fraction in the gypsum should be greater than 45%.

[0014] The present invention also provides a method for preparing a cementitious material, comprising the following steps: Ingredients: Modified zinc slag powder, slag powder, and gypsum are mixed according to the weight proportions. Secondary grinding: The mixed material is put into a ball mill for grinding for 3 to 5 minutes. The residue on the 80μm sieve after grinding should be less than 10%.

[0015] The present invention also provides an application of a cementitious material in the repair, grouting or connection of prefabricated components of concrete structures, wherein the cementitious material, quartz sand aggregate and water are mixed, wherein the cementitious material is 40-50 parts by weight, the quartz sand aggregate is 50 parts by weight and the water is 25-30 parts by weight.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The cementitious material prepared by this invention has an initial setting time of ≥30min and a final setting time of ≤50min; stable volume properties, with a volume change rate of ≤1‰ during hardening; bonding strength with existing concrete interface (after 1 day of construction) ≥9MPa; compressive strength ≥40MPa at 3h and ≥60MPa at 1d; it can better meet the application scenarios such as concrete crack repair and grouting construction, improve the reliability of building component connections, and enhance construction quality. 2. The raw materials required in this invention are mainly hazardous waste from the zinc smelting industry. Through processing methods such as grinding and calcination, as well as adjustments to process parameters, resources are effectively reused. The production process is simple and mature, making it easy to produce and promote. Materials such as slag powder, limestone, and gypsum can be solid wastes emitted by other industries. Using these substances in the preparation of cementitious materials can effectively dispose of existing solid wastes, meeting the policy requirements of low-carbon and environmental protection. Moreover, the cost is lower compared with the grouting and repair materials currently used in construction. Detailed Implementation

[0017] The present invention will be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention.

[0018] A cementitious material based on zinc slag includes 60-70 parts by weight of modified zinc slag powder, 25-35 parts by weight of slag powder, and 5-10 parts by weight of gypsum.

[0019] Specifically, the slag powder is S95 pure slag powder that conforms to the GB / T 18046-2008 standard "Slag powder for use in cement and concrete".

[0020] To ensure the optimal gelling properties of zinc slag powder, chemical modification and heat treatment processes were employed to increase the Ca2+ content in the mixture. + SO4 2- F - 、Ge 2+ The ion content meets the requirements for the target mineral content of cementitious materials.

[0021] The preparation method of the modified zinc slag powder includes the following steps: Since undisturbed zinc slag generally has a high moisture content and varying particle size, it needs to be dried to meet processing requirements. Therefore, the undisturbed zinc slag must first be dried; that is, the undisturbed zinc slag is naturally dried or oven-dried until the moisture content is ≤1.5%.

[0022] Depending on the requirements, virgin zinc slag refers to untreated zinc slag discharged from the zinc smelting industry. It should be noted that virgin zinc slag refers to untreated zinc slag.

[0023] Chemical modification: Due to differences in mineral sources and processes, the chemical composition of raw zinc slag powder is complex and fluctuates greatly. Therefore, it is necessary to add commonly found natural materials such as limestone, gypsum, calcium fluoride, and germanium oxide to the raw zinc slag based on the chemical composition determination results after drying. This will ensure that the chemical composition of the mixture meets the following requirements: as calculated by CaO, the mass fraction of Ca is 50%~55%; as calculated by SO3, the mass fraction of S is greater than 5%; as calculated by CaF2, the mass fraction of F is greater than 0.8%; and as calculated by GeO, the mass fraction of Ge is greater than 0.5%.

[0024] Primary grinding: The mixture is ball-milled for 5-10 minutes. The residue on the 45μm sieve after grinding should be less than 5%. This is used to reduce the particle size of the material, improve the efficiency of subsequent chemical reactions, and at the same time achieve the homogenization of different components to achieve the formation of the target mineral.

[0025] Calcination: The temperature is increased to 900–950℃ at a rate of 20–25℃ / min and held for 2–3 minutes; that is, the liquid phase of the low-melting-point substance melts at high temperature and then re-condenses after cooling. By controlling the calcination heating regime and temperature, a scientifically reasonable time is ensured for the decomposition of the original minerals and the formation of the target minerals in the components.

[0026] Rapid cooling: Cool to room temperature within 30 minutes to ensure that highly reactive minerals such as calcium silicate and calcium germanate formed under high temperature conditions can be retained in the cementitious material and avoid re-decomposition.

[0027] It should be noted that the gypsum used is natural gypsum or industrial by-product gypsum, and the SO3 mass fraction in the gypsum should be greater than 45%.

[0028] The preparation method of this cementitious material includes the following steps: Ingredients: Modified zinc slag powder, slag powder, and gypsum are mixed according to the weight proportions. Secondary grinding: The mixed materials are put into a ball mill for grinding for 3 to 5 minutes. The residue on the 80μm sieve after grinding should be less than 10%. This is used to reduce the particle size of the mixed materials to meet the performance requirements of the cementitious materials during hydration, and at the same time to make the three components more fully mixed.

[0029] This cementitious material can be used in the repair of concrete structures, grouting, or connection of prefabricated components. Specifically, it is made by mixing cementitious material, quartz sand aggregate, and water, wherein the cementitious material is 40-50 parts by weight, the quartz sand aggregate is 50 parts by weight, and the water is 25-30 parts by weight.

[0030] In this embodiment, zinc slag from two beneficiation sites, A and B, from different years, was selected and dried in a ventilated drying oven at 90°C for 1 hour, ensuring that the moisture content after drying was ≤1.5%. After grinding, the chemical composition was determined using X-ray fluorescence spectroscopy. Based on calculations, limestone, gypsum, calcium fluoride, and germanium oxide were added for chemical modification. The composition and main chemical components of the modified material are shown in Table 1. Table 1: Information on the modified material components and main chemical components in Examples 1-6

[0031] The modified material was subjected to grinding and calcination processes sequentially. Grinding was performed using a ball mill, and calcination was carried out in a muffle furnace. The preparation process parameters are shown in Table 2. Table 2: Process parameters for preparing modified materials in Examples 1-6

[0032] Modified zinc slag, prepared through chemical modification and calcination, was mixed with S95 grade slag powder and gypsum (SO3 mass fraction 46.3%) in a metered ratio, and then added to a ball mill for secondary grinding and mixing to form a cementitious material. The component information and grinding regime are shown in Table 3. Table 3: Information on each component and grinding process of cementitious materials in Examples 1-6

[0033] The prepared cementitious materials were added to quartz sand and water respectively for molding. The setting time, volume change rate, compressive strength, and bond strength were determined according to GB / T 1346 "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement" and GB / T 17671 "Test Methods for Strength of Cement Mortar (ISO Method)". The specific results are shown in Table 4. Table 4: Application Examples and Main Properties of Cementitious Materials

[0034] The cementitious materials prepared in Examples 1-6, based on the test results of properties such as setting time, hardening volume change rate, and strength, indicate that the cementitious materials prepared by zinc slag in this invention are well applicable to the needs of existing concrete building crack repair, grouting connection, and other applications.

[0035] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the above embodiments should be regarded as exemplary and non-limiting in all respects. The scope of this invention is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this invention.

Claims

1. A cementitious material prepared based on zinc slag, characterized in that: include: 60-70 parts by weight of modified zinc slag powder; 25-35 parts by weight of slag powder; 5-10 parts by weight of gypsum; The chemical composition of the modified zinc slag powder meets the following conditions: The mass fraction of Ca, calculated as CaO, is 50%–55%. The mass fraction of sulfur (S) in SO3 is greater than 5%. The mass fraction of F element in CaF2 is greater than 0.8%; The mass fraction of Ge element, calculated as GeO, is greater than 0.5%.

2. The cementitious material prepared based on zinc slag according to claim 1, characterized in that: The modified zinc slag powder is prepared by adding limestone, gypsum, calcium fluoride and germanium oxide to the original zinc slag discharged from the zinc smelting industry for chemical component modification, and then heat treatment.

3. The cementitious material prepared based on zinc slag according to claim 2, characterized in that: The preparation method of the modified zinc slag powder includes the following steps: Drying: Dry the raw zinc slag until the moisture content is ≤1.5%; Chemical modification: Based on the chemical composition determination results of the dried original zinc slag, limestone, gypsum, calcium fluoride and germanium oxide are added and mixed to make the chemical composition of the mixture meet the requirements of claim 1; One-time grinding: Ball mill the mixture for 5-10 minutes. The residue on the 45μm sieve after grinding should be less than 5%. Calcination: Heat to 900-950℃ at a heating rate of 20-25℃ / min, and hold for 2-3 minutes; Rapid cooling: Cools to room temperature within 30 minutes.

4. The cementitious material prepared based on zinc slag according to claim 3, characterized in that: The original zinc slag is dried by natural drying or oven drying.

5. The cementitious material prepared based on zinc slag according to claim 1, characterized in that: The slag powder is S95 pure slag powder that conforms to the GB / T 18046-2008 standard "Slag powder for cement and concrete".

6. A cementitious material prepared based on zinc slag according to claim 1 or 2, characterized in that: The gypsum used is natural gypsum or industrial by-product gypsum, and the SO3 mass fraction in the gypsum should be greater than 45%.

7. A method for preparing a cementitious material as described in any one of claims 1 to 6, characterized in that: Includes the following steps: Ingredients: Modified zinc slag powder, slag powder, and gypsum are mixed according to the weight proportions. Secondary grinding: The mixed material is put into a ball mill for grinding for 3 to 5 minutes. After grinding, the material residue on the 80μm sieve is less than 10%.

8. The application of a cementitious material as described in any one of claims 1 to 6 in the repair, grouting, or connection of prefabricated components of concrete structures, characterized in that: The cementitious material, quartz sand aggregate, and water are mixed, wherein the cementitious material is 40-50 parts by weight, the quartz sand aggregate is 50 parts by weight, and the water is 25-30 parts by weight.

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