Fluorogypsum self-leveling mortar and preparation method thereof

Abstract

The application discloses a fluorogypsum self-leveling mortar and a preparation method thereof, which comprises the following steps: uniformly mixing fluorogypsum, hemihydrate gypsum, ordinary Portland cement, lime, potassium sulfate, a defoaming agent, a water reducing agent, a retarder and cellulose to prepare the fluorogypsum self-leveling mortar. The application improves the strength of the fluorogypsum self-leveling mortar by hydrating the industrial by-product fluorogypsum into dihydrate gypsum and generating ettringite from the dihydrate gypsum and the Portland cement. The application introduces the Portland cement and adjusts the proportion of the Portland cement to promote the setting of the material, generate high-strength ettringite from the fluorogypsum and improve the flowability of the material. Thus, the fluorogypsum self-leveling mortar has good physical performance, mechanical strength, water resistance and construction performance.

Description

Technical Field

[0001] This application relates to a fluorogypsum self-leveling mortar and its preparation method, and more particularly to an industrial by-product fluorogypsum self-leveling mortar and its preparation method, belonging to the field of industrial by-product gypsum. Background Technology

[0002] Gypsum-based self-leveling mortar is a dry powder mortar specifically designed for floor leveling, made primarily from gypsum with added fillers, aggregates, and additives. Currently, the cementing material in gypsum-based self-leveling mortars is mainly hemihydrate gypsum, which has limited applications due to poor water resistance, low strength, and low surface hardness. Furthermore, most gypsum-based self-leveling mortars currently use building gypsum, which requires crushing, drying, and high-temperature calcination processes, resulting in high energy consumption and raw material costs. Utilizing fluorogypsum to prepare self-leveling materials can add value to fluorogypsum products, maximizing resource efficiency. At the same time, fluorogypsum self-leveling materials have a lower cost, giving them a significant price advantage in promoting the application of self-leveling materials.

[0003] Industrial by-product gypsum is an excellent renewable resource. Its comprehensive utilization is beneficial to environmental protection and can save energy and resources. However, industrial by-product fluorogypsum is a polluting solid waste. Without any treatment, industrial by-product fluorogypsum is difficult to utilize effectively due to its low strength and difficulty in handling. Therefore, there is an urgent need for a self-leveling material based on industrial by-product gypsum. Summary of the Invention

[0004] In view of this, according to one aspect of this application, a fluorogypsum self-leveling mortar is provided, particularly a self-leveling mortar based on industrial by-product fluorogypsum, which improves the performance of existing gypsum-based self-leveling mortars while solving the problem of resource utilization of industrial by-product fluorogypsum. The specific solution is as follows:

[0005] A fluorogypsum self-leveling mortar, comprising: fluorogypsum, hemihydrate gypsum, ordinary silicate cement, lime, potassium sulfate, defoamer, water-reducing agent, retarder, and cellulose.

[0006] Preferably, the fluorogypsum self-leveling mortar comprises, by weight parts: 50-80 parts fluorogypsum, 15-40 parts hemihydrate gypsum, 20-50 parts ordinary silicate cement, 2-8 parts lime, 2-6 parts activator, 0.5-2 parts defoamer, 1-3 parts water-reducing agent, 0.5-1 part retarder, and 0.5-1 part cellulose.

[0007] Preferably, the fluorogypsum is an industrial by-product of fluorogypsum.

[0008] Preferably, the particle size of the industrial by-product fluorogypsum is 180-240 mesh;

[0009] The industrial by-product fluorogypsum is prepared by ball milling after calcination at 400℃.

[0010] Preferably, the water-reducing agent is selected from any one of SM high-efficiency water-reducing agent, sodium alkylbenzene sulfonate, sodium lignosulfonate water-reducing agent, or polycarboxylate water-reducing agent.

[0011] Preferably, the defoamer is an additive prepared by neutralization reaction of modified polyether, esterified and higher alcohol substances under vacuum and normal pressure, at a temperature of 100℃~140℃.

[0012] Preferably, the activator is a sulfate;

[0013] The activator is any one of K2SO4, Na2SO4, CuSO4 or Al2(SO4)3.

[0014] According to another aspect of this application, a method for preparing fluorogypsum self-leveling mortar is provided, the method comprising: mixing fluorogypsum, hemihydrate gypsum, ordinary silicate cement, lime, potassium sulfate, defoamer, water-reducing agent, retarder, and cellulose evenly to obtain the fluorogypsum self-leveling mortar.

[0015] The beneficial effects that this application can produce include:

[0016] In this invention, the material strength comes from the hydration of fluorogypsum to form dihydrate gypsum, and from the ettringite formed by the dihydrate gypsum and silicate cement. By introducing silicate cement and adjusting its proportion, the material's setting is promoted, and high-strength ettringite is formed with fluorogypsum, thereby improving the material's fluidity.

[0017] This invention provides a gypsum self-leveling mortar with good physical properties, mechanical strength, water resistance, and workability, while mainly solving the problem of resource utilization of industrial by-product fluorogypsum, namely, a fluorogypsum self-leveling material and its preparation method using industrial by-product fluorogypsum as the main raw material. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a hydrofluoric acid production process in one embodiment of this application. Detailed Implementation

[0019] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0020] A fluorogypsum self-leveling mortar, comprising: fluorogypsum, hemihydrate gypsum, ordinary silicate cement, lime, potassium sulfate, defoamer, water-reducing agent, retarder, and cellulose.

[0021] Furthermore, by weight, the fluorogypsum self-leveling mortar comprises: 50-80 parts fluorogypsum, 15-40 parts hemihydrate gypsum, 20-50 parts ordinary silicate cement, 2-8 parts lime, 2-6 parts activator, 0.5-2 parts defoamer, 1-3 parts water-reducing agent, 0.5-1 part retarder, and 0.5-1 part cellulose.

[0022] Furthermore, the fluorogypsum is an industrial by-product of fluorogypsum.

[0023] Furthermore, the particle size of the industrial by-product fluorogypsum is 180–240 mesh;

[0024] The industrial by-product fluorogypsum is prepared by ball milling after calcination at 400℃.

[0025] Furthermore, the water-reducing agent is selected from any one of SM high-efficiency water-reducing agent, sodium alkylbenzene sulfonate, sodium lignosulfonate water-reducing agent, or polycarboxylate-based water-reducing agent.

[0026] Furthermore, the defoamer is an additive made from modified polyether, esterified and higher alcohol substances using special industrial refining methods.

[0027] Among them, characteristic industrial refining refers to an additive process that uses ethylene oxide and propylene oxide as raw materials, and adds initiators (glycerol, pentaerythritol) and catalysts (KOH) during the neutralization reaction under vacuum and normal pressure, and at a temperature of 100℃~140℃ to prepare an additive.

[0028] Furthermore, the activator is a sulfate;

[0029] The activator is any one of K2SO4, Na2SO4, CuSO4 or Al2(SO4)3.

[0030] Furthermore, a method for preparing fluorogypsum self-leveling mortar is provided, the method comprising: mixing fluorogypsum, hemihydrate gypsum, ordinary silicate cement, lime, potassium sulfate, defoamer, water-reducing agent, retarder, and cellulose evenly to obtain the fluorogypsum self-leveling mortar.

[0031] It should be noted that:

[0032] Without any treatment, industrial by-product fluorogypsum is difficult to utilize effectively due to its low strength and difficulty in processing. Therefore, this application prepares a fluorogypsum self-leveling material by mixing industrial by-product fluorogypsum with hemihydrate gypsum, cement and other materials, giving it good physical properties, mechanical strength and water resistance.

[0033] The difficulty in preparing fluorogypsum self-leveling materials from industrial by-product fluorogypsum lies in the high viscosity of fluorogypsum itself. Therefore, this application uses a dispersion device to break up the fluorogypsum before putting it into production, thereby avoiding an increase in water consumption.

[0034] The fluorogypsum in this application can be obtained from any industrial by-product of fluorogypsum. In one embodiment of this application, the fluorogypsum is derived from the industrial by-product fluorogypsum discharged during the production of hydrofluoric acid. The preparation principle of hydrofluoric acid is: CaF2 + H2SO4 → 2HF + CaSO4.

[0035] Furthermore, the desulfurized building gypsum meets the following technical parameters and physical and mechanical properties: hemihydrate gypsum phase ≥85%, anhydrous gypsum phase ≤8%, dihydrate gypsum phase ≤4%, and chloride ion content ≤600mg / kg.

[0036] The performance parameters of fluorogypsum self-leveling materials are shown in Table 1.

[0037] Table 1 Performance parameters of fluorogypsum self-leveling material

[0038]

[0039] The production process of hydrofluoric acid is shown in the attached figure. Figure 1 As shown.

[0040] Fluorite powder and sulfuric acid are heated and reacted in a rotary reactor to produce hydrogen fluoride gas and calcium sulfate solid. The hydrogen fluoride gas is cooled, dusted, and condensed by a scrubbing system and then purified by a condensing system before entering a distillation system to obtain the final product, anhydrous hydrogen fluoride liquid. After testing and analysis, it is sent to the tank area for storage and sale. The calcium sulfate solid (gypsum slag) is cooled, loaded onto trucks, and sold. The tail gas is recovered through an absorption tower, washed with water and alkali, and then introduced into the centralized tail gas treatment. The fluorosilicic acid produced by the side reaction is sent to the tank area for storage.

[0041] High-quality fluorogypsum produced by ball milling the industrial by-product fluorogypsum emitted during the production of hydrofluoroacrylic acid has a particle size of 180-240 mesh.

[0042] In this application, the activator used is a sulfate, preferably any one of K2SO4, Na2SO4, CuSO4, or Al2(SO4)3. The activator is used to promote the early hydration and hardening of the industrial by-product fluorogypsum composite cementitious material, shortening the setting time. In addition, when the incorporated activator provides sufficient Al... 3+When the hydrolysis occurs, the amount of Al(OH)3 colloid with strong adsorption capacity increases. The adsorbed particles of Al(OH)3 colloid aggregate into large flocculents. These flocculents have a large solid surface area, which enhances their water adsorption capacity, thereby reducing the water bleeding rate. When the amount of activator increases, more ettringite is produced inside the specimen. The expansion of ettringite leads to local microcracks inside, increasing the water absorption rate.

[0043] The water-reducing agent used in this application must be any one of SM high-efficiency water-reducing agent, sodium alkylbenzene sulfonate, sodium lignosulfonate water-reducing agent, or polycarboxylate water-reducing agent. This is because these water-reducing agents do not have a retarding effect on fluorogypsum-based materials, and are thus used to improve the fluidity of the slurry and reduce the amount of water used.

[0044] The defoamer used in this application is prepared by pumping raw materials propylene oxide and ethylene oxide into a dosing tank. Initiators (glycerol, pentaerythritol) and catalyst (KOH) are pre-added to the polymerization reactor, and the mixture is vacuum-dehydrated at above 100°C for approximately 30 minutes. After vacuum evacuation, nitrogen is added for protection. The reaction temperature is controlled between 100°C and 140°C, and the pressure is less than 0.35 MPa before feeding begins. After the reaction is complete, ethylene oxide is added. After the reaction is finished, the mixture is kept at atmospheric pressure at 100°C to 140°C for 30 minutes to ensure sufficient neutralization. The filtrate after the neutralization reaction is completed is the defoamer. This defoamer is suitable for defoaming and foam suppression under alkaline conditions, is resistant to high temperatures and strong alkalis, and can be used to reduce the surface tension of self-leveling mortar, improve the surface smoothness of the hardened body, and requires a small dosage, thus saving costs to some extent.

[0045] This application uses lime as an alkali activating material, which can enhance the hydration and hardening of fluorogypsum in the later stage, and improve its strength and water resistance. By adding a retarder, the hydration and hardening time of the slurry is extended, so that the freshly mixed slurry can maintain its plasticity for a longer period of time, ensuring normal construction. The addition of cellulose can increase the adhesion of the self-leveling mortar, improve its tensile strength and durability, and the cellulose in the slurry can play a role in water retention and thickening. The hydroxyl groups are not easily soluble in water. When they react fully with water, a three-dimensional network gel structure is formed and precipitated. At this time, it has a good water retention and thickening effect, which can improve the water resistance of the self-leveling mortar to a certain extent.

[0046] To further illustrate the present invention, the following embodiments are provided for detailed explanation. In each embodiment, the raw materials were weighed and proportioned according to the prescribed formula. The amount of cementitious material was 1 kg, and the admixture was added externally. The amounts (g) of each raw material are shown in Table 2:

[0047] Table 2

[0048]

[0049]

[0050] Mix the ingredients in Table 2 according to the specified ratio, add an appropriate amount of water and stir until well combined before use.

[0051] To verify the performance characteristics of the fluorogypsum self-leveling mortar provided in this application, mechanical performance tests were conducted on the fluorogypsum self-leveling mortar provided in this application and existing building gypsum self-leveling mortars. The test results are shown in Table 3.

[0052] Table 3 Test Results of Building Gypsum Self-Leveling Mortar

[0053]

[0054] The test results above show that, compared with building gypsum self-leveling mortar, the fluorogypsum self-leveling mortar provided in this application has an average increase of 11.5% in 28-day flexural strength, an average increase of 32.65% in 28-day compressive strength, and an increase of 9.75% in softening coefficient. Therefore, the fluorogypsum self-leveling material provided by this invention has good physical properties, good mechanical strength, good water resistance, and good construction and road performance.

[0055] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A fluorogypsum self-leveling mortar, characterized by, The fluorogypsum self-leveling mortar comprises industrial by-product fluorogypsum, hemihydrate gypsum, ordinary Portland cement, calcium oxide, potassium sulfate, defoaming agent, water reducing agent, retarder and cellulose. The industrial by-product fluorogypsum is prepared by high-temperature calcination at 400 DEG C and ball milling, and has a particle size of 180-240 mesh. The content of each component is as follows in mass fraction: 50-80 parts of industrial by-product fluorogypsum, 15-40 parts of hemihydrate gypsum, 20-50 parts of ordinary Portland cement, 2-8 parts of calcium oxide, 2-6 parts of potassium sulfate, 0.5-2 parts of defoaming agent, 1-3 parts of water reducing agent, 0.5-1 part of retarder and 0.5-1 part of cellulose. The defoaming agent is prepared by neutralization reaction under vacuum and at a temperature of 100-140 DEG C, using ethylene oxide and propylene oxide as raw materials, adding initiator glycerol or pentaerythritol and catalyst KOH.

2. A fluorogypsum self-leveling mortar according to claim 1, characterized in that, The water reducing agent is selected from any one of SM high-efficiency water reducing agent, sodium alkyl benzene sulfonate, sodium lignosulfonate water reducing agent and polycarboxylic acid water reducing agent.

3. A method of preparing a fluorogypsum self-leveling mortar according to any one of claims 1-2, characterized in that, The preparation method comprises uniformly mixing industrial by-product fluorogypsum, hemihydrate gypsum, ordinary Portland cement, calcium oxide, potassium sulfate, defoaming agent, water reducing agent, retarder and cellulose to obtain the fluorogypsum self-leveling mortar.

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