A debonder and its use

Abstract

This invention relates to the field of ceramic slurry preparation technology, and more particularly to a desiccant and its application. The invention provides a desiccant composed of lignin sulfonate and sodium n-heptyl-selenyl-n-octyl sulfate. The desiccant provided by this invention can utilize the reducing iron components (such as Fe) inherent in the slurry. 0 Fe 2+ As a reducing buffer, it keeps the active center (-Se-) of the degumming agent dynamically active and preferentially adsorbs and disperses iron-containing mineral particles, thereby achieving efficient and stable degumming effect in an alkaline environment and significantly improving the uniformity of the final green body and black spot (iron) defects.

Description

Technical Field

[0001] This invention relates to the field of ceramic slurry preparation technology, and in particular to a descaling agent and its application. Background Technology

[0002] In the production of ceramic products, slurry preparation is a crucial preliminary step. The dispersion stability, fluidity, and particle fineness of the slurry directly affect the efficiency of subsequent processes such as molding and drying, as well as the strength, uniformity, and quality of the final green body and fired product. Therefore, it is usually necessary to add a deflocculant (also known as a diluent or dispersant) to the slurry, and deflocculation is generally carried out under alkaline conditions with a pH of 8-10.

[0003] High-iron slurry mainly includes slurry for antique porcelain, celadon, and various pottery, as well as non-metallic mineral slurry from the metallurgical industry. There are many types and a large processing volume.

[0004] Currently, the commonly used ceramic slurry degelatinizers in industry mainly include the following categories: 1) Inorganic electrolytes, such as water glass (sodium silicate), sodium carbonate, sodium tripolyphosphate, etc., which mainly function through ion exchange and electrostatic repulsion, but require large quantities and have limited effects; 2) Organic polymers, such as sodium polyacrylate, sodium humate, etc., which mainly achieve dispersion through steric hindrance effect, have better effects and a wide range of dosages, and have become the mainstream choice.

[0005] However, in actual production, especially when using low-grade or impurity-containing raw materials, existing deflocculant technologies face major challenges: (1) Sensitive to divalent metal ions: Calcium (Ca) is commonly found in mud or process water. 2+ ), magnesium (Mg) 2+ Divalent metal ions, such as sodium polyacrylate, readily undergo cross-linking reactions with carboxylate groups in polymer degreasing agents, leading to the aggregation and failure of the degreasing agent molecular chains. This results in a sharp increase in mud viscosity, even solidification, poor fluidity, and low ball milling efficiency.

[0006] (2) Limited ability to disperse iron impurities: Free iron, rust, or iron-containing minerals (such as hematite and limonite) in the slurry are not only difficult to disperse, but also tend to form rich brown or black spots after firing, which seriously affects the appearance and whiteness of the product. Traditional degumming agents are not effective in targeting and dispersing these types of coloring impurities and cannot effectively solve the problem of dispersion of high iron slurry.

[0007] (3) Single function and unable to be intelligently controlled: Once the existing degumming agent is added, its dispersion state is fixed and it cannot be adjusted as needed according to the dynamic changes in the rheology of the mud (such as the need for high fluidity and the need for fast setting) at different process stages such as grouting, transportation and storage.

[0008] Therefore, developing a smart degumming agent that can withstand complex ionic environments, efficiently disperse iron-containing impurities, and has performance regulation capabilities is of great significance for improving the applicability of ceramic raw materials, ensuring production stability, and increasing product added value. Summary of the Invention

[0009] In view of this, the purpose of this invention is to provide a desiccant and its application. The desiccant provided by this invention can withstand complex ionic environments, efficiently disperse iron-containing impurities, and has performance regulation capabilities, which is beneficial for improving the applicability of ceramic raw materials, ensuring production stability, and increasing product added value.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a degumming agent, which is composed of packaged lignin sulfonate and sodium n-heptyl-selenyl-n-octyl sulfate.

[0011] Preferably, the lignin sulfonate includes sodium lignin sulfonate or potassium lignin sulfonate.

[0012] This invention provides the application of the deflocculant described above in the preparation of iron-containing ceramic slurry.

[0013] Preferably, the method for preparing the iron-containing ceramic slurry includes the following steps: The iron-containing ceramic blank, the deflocculant, and water are ball-milled and mixed to obtain the iron-containing ceramic slurry; the mass of lignin sulfonate in the deflocculant is 0.4-0.6% of the dry weight of the iron-containing ceramic blank, and the mass of sodium n-heptyl-selenyl-n-octyl sulfate is 0.02-0.08% of the dry weight of the iron-containing ceramic blank.

[0014] Preferably, the mass ratio of the iron-containing ceramic blank to water, on a dry weight basis, is 2:1.

[0015] Preferably, the iron content in the iron-containing ceramic blank is 0.05-10% on a dry weight basis.

[0016] Preferably, on a dry weight basis, the iron-containing ceramic blank comprises 40-50% clay, 25-35% quartz, and 20-30% feldspar.

[0017] Preferably, the mass of the lignin sulfonate is 0.5% of the dry weight of the iron-containing ceramic blank.

[0018] Preferably, the fineness of the iron-containing ceramic slurry reaches a residue of less than 1.1% on a 250-mesh sieve.

[0019] Preferably, the clay comprises kaolin; the feldspar comprises potassium-sodium feldspar.

[0020] This invention provides a degumming agent composed of packaged lignin sulfonate and sodium n-heptyl-selenyl-n-octyl sulfate. The degumming agent provided by this invention can withstand complex ionic environments, efficiently disperse iron-containing impurities, and possesses performance regulation capabilities. This function stems from the unique redox response characteristics of the degumming agent molecules and its adaptive mechanism in complex mud environments. Specifically: The core of the redox responsiveness lies in the presence of a divalent selenium ether group (-Se-) embedded in the hydrophobic chain of the selenium-containing surfactant, sodium n-heptyl-selenyl-n-octyl sulfate. This group constitutes a reversible "chemical switch." Under mild reducing conditions, it remains in the hydrophobic -Se- state, giving the molecule excellent surface activity. Under oxidizing conditions, however, it can be controllably oxidized to the more hydrophilic selenium sulfoxide group (-SeO-), resulting in a significant decrease in surface activity or even a temporary "shutdown." This characteristic provides a foundation for the external intelligent control of mud rheology (e.g., through the addition of trace amounts of oxidizing / reducing agents).

[0021] Self-sustaining mechanisms in iron-containing alkaline slurries (utilizing the environment): Ceramic slurries are typically alkaline (pH 8-10) and often contain reducing iron components (such as Fe). 0 Fe 2+ An alkaline environment is conducive to maintaining the stability of -Se-, while reducing iron ions can dynamically reduce -SeO- that may be oxidized in the system back to the highly active -Se- state, thereby forming a self-repairing reduction buffer system inside the iron-containing mud, so that the activity of the degumming agent can be maintained for a long time.

[0022] Targeted dispersion mechanism: Selenium-containing groups have a special affinity for iron particles, allowing the desiccant molecules to preferentially adsorb onto the surface of iron-containing mineral particles. Through the strong electrostatic repulsion generated by its anionic hydrophilic head group (sodium sulfate), it can efficiently disintegrate iron agglomerates, achieving selective and efficient dispersion and inhibiting the formation of firing spots from the source.

[0023] The principle behind its high tolerance to calcium and magnesium ions: Unlike traditional sodium polyacrylate degumming agents that rely on carboxylate chelation, the degumming agent of this invention primarily relies on the electrostatic repulsion of sulfonic acid / sulfate ions and the responsive function of -Se-. Its active center (-Se-) does not react with Ca... 2+ / Mg 2+ The cross-linking reaction that leads to failure occurs, thus fundamentally avoiding the risk of mud flocculation caused by the presence of calcium and magnesium ions in water or raw materials, and exhibiting more stable dispersion performance in complex ionic environments.

[0024] In summary, the degumming agent provided by this invention does not passively act on the mud, but actively senses and utilizes the mud environment (such as Fe). 2+It can also respond to simple external chemical stimuli to achieve efficient, stable and intelligently controllable degumming of mud containing impurities such as iron, calcium and magnesium, thus precisely solving the industry pain points mentioned in the background technology. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation process of the iron-containing ceramic slurry of the present invention. Detailed Implementation

[0026] This invention provides a degumming agent composed of packaged lignin sulfonate and sodium n-heptyl-selen-n-octyl sulfate. In this invention, the lignin sulfonate preferably comprises sodium lignin sulfonate or potassium lignin sulfonate, more preferably sodium lignin sulfonate.

[0027] In this invention, the lignin sulfonate is a commercially available product well known in the art; the sodium n-heptyl-selen-n-octyl sulfate is prepared by a method well known in the art, and the synthetic route is as follows: using 1-bromoheptane and 8-bromo-1-octanol as starting materials, the intermediates 1,2-diheptyldiselenes and sodium 8-bromooctyl sulfate are first synthesized, and then coupled by a nucleophilic substitution reaction to obtain the target product sodium n-heptyl-selen-n-octyl sulfate. Specifically, it can be prepared by referring to "Zhang Y, Liu L, Liu X, et al. Reversibly switching wormlike micelles formed by a selenium-containing surfactant and benzyl tertiary amine using CO2 / N2 and redox reaction[J]. Langmuir, 2018, 34(6): 2302-2311." or "Liu Deqiong, Zhang Yongmin, Fan Ye, et al. Synthesis and properties of selenium-containing surfactant sodium n-heptyl-selenyl-n-octyl sulfate[J]. Daily Chemical Industry, 2020, 50(10):669-675." In this invention, the structural formula of sodium n-heptyl-selenyl-n-octyl sulfate is as follows: C7H 15 -Se-(CH2)8-OSO3Na.

[0028] This invention provides the application of the deflocculant described above in the preparation of iron-containing ceramic slurry.

[0029] In this invention, the method for preparing the iron-containing ceramic slurry preferably includes the following steps: The iron-containing ceramic blank, the deflocculant, and water are ball-milled and mixed to obtain the iron-containing ceramic slurry; the mass of lignin sulfonate in the deflocculant is 0.4-0.6% of the dry weight of the iron-containing ceramic blank, and the mass of sodium n-heptyl-selenyl-n-octyl sulfate is 0.02-0.08% of the dry weight of the iron-containing ceramic blank.

[0030] In this invention, the iron content in the iron-containing ceramic body is preferably 0.05-10%, and in specific embodiments it can be 0.05%, 0.1%, 1%, 1.6%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. On a dry weight basis, the iron-containing ceramic body preferably comprises: 40-50% clay, 25-35% quartz, and 20-30% feldspar. In this invention, the clay can specifically be kaolin; the feldspar can specifically be potassium-sodium feldspar. In specific embodiments, the clay content can be 40%, 42%, 45%, 48%, or 50%; the quartz content can be 25%, 28%, 30%, 32%, or 35%; and the feldspar content can be 20%, 22%, 25%, 27%, or 30%. In an embodiment of this invention, the iron-containing ceramic body specifically comprises 45% kaolin, 30% quartz, and 25% potassium-sodium feldspar.

[0031] In this invention, the preferred mass ratio of the iron-containing ceramic blank to water, based on dry weight, is 2:1.

[0032] In this invention, the mass of lignin sulfonate in the degumming agent is 0.4-0.6% of the dry weight of the iron-containing ceramic green body, and in specific embodiments it can be 0.4%, 0.5% or 0.6%; the mass of sodium n-heptyl-selenyl-n-octyl sulfate in the degumming agent is 0.02-0.08% of the dry weight of the iron-containing ceramic green body, and in specific embodiments it can be 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07% or 0.08%.

[0033] This invention does not have special requirements for the ball milling mixture; any ball milling mixture method well known in the art can be used. In an embodiment of this invention, the ball milling mixture is made using a rolling ball mill; the mass ratio of material:balls:water in the ball milling mixture is 1:2:0.5, and the ball milling time is 16 hours.

[0034] In this invention, the fineness of the iron-containing ceramic slurry can reach a residue of less than 1.1% on a 250-mesh sieve.

[0035] The following detailed description of the degumming agent and its application provided by the present invention, in conjunction with specific examples, should not be construed as limiting the scope of protection of the present invention.

[0036] The preparation process of sodium n-heptyl-selenyl-n-octyl sulfate in the following examples and comparative examples is as follows: Step 1: Synthesis of intermediate 1,2-diheptyldiselenic ether Under nitrogen protection, selenium powder (31.6 g, 0.40 mol) and a mixture of 400 mL ethanol and 100 mL water were added to a 1 L three-necked flask equipped with a stir bar and a condenser. The flask was then cooled to 0°C in an ice-water bath. Sodium borohydride (9.46 g, 0.25 mol) was slowly added in portions with vigorous stirring. The addition rate was controlled to prevent violent gas release. After the addition was complete, the ice bath was removed, and the mixture was heated to 70°C and refluxed for approximately 2 hours until the selenium powder was completely dissolved, yielding a deep red sodium diselenide (Na₂Se₂) solution.

[0037] The reaction mixture was cooled to room temperature, and 1-bromoheptane (96.0 g, 0.53 mol) was added in a single batch with stirring. The mixture was heated to 60 °C and stirred for 12 h. After the reaction was complete, the mixture was cooled to room temperature, and most of the ethanol was removed by vacuum distillation. 500 mL of water and 300 mL of dichloromethane were added to the residue, and the mixture was transferred to a separatory funnel, shaken thoroughly, and separated. The aqueous phase was then extracted with dichloromethane (2 × 200 mL). All organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. After filtration, the mixture was concentrated under reduced pressure to obtain the crude product.

[0038] The crude product was purified by silica gel column chromatography (300-400 mesh silica gel, eluent: petroleum ether / ethyl acetate = 20:1, v / v). The main fraction was collected and concentrated under reduced pressure to obtain a pale yellow oily liquid, which solidified into a pale yellow waxy solid upon cooling, namely 1,2-diheptyldiselenic ether.

[0039] Step 2: Synthesis of intermediate sodium 8-bromooctyl sulfate Under nitrogen protection, 50.0 g (0.224 mol) of 8-bromo-1-octanol and 200 mL (anhydrous N,N-dimethylformamide) were added to a dry 500 mL three-necked flask and stirred until dissolved. Sulfur trioxide-pyridine complex (35.7 g, 0.224 mol) was added in portions while cooling and stirring in an ice-water bath. After the addition was complete, the ice bath was removed, and the reaction mixture was stirred at room temperature for 4 h. The reaction was monitored for completeness by TLC (evolving solvent: dichloromethane / methanol = 8:1).

[0040] The reaction solution was slowly poured into 1 L of vigorously stirred ice water, resulting in the formation of a white precipitate. Subsequently, under ice-water bath cooling, a 5 M sodium hydroxide aqueous solution was slowly added dropwise to adjust the pH of the mixture to 9-10. The precipitate dissolved, yielding a clear or slightly turbid solution. This aqueous solution was transferred to a separatory funnel and washed with dichloromethane (3 × 150 mL) to remove DMF and possible byproducts. The aqueous phase was concentrated to dryness under reduced pressure at 40 °C using a rotary evaporator, yielding a white or off-white solid. Recrystallization of this solid from anhydrous ethanol yielded a white powdery sodium 8-bromooctyl sulfate.

[0041] Step 3: Synthesis of the target product, sodium n-heptyl-selen-n-octyl sulfate. Under nitrogen protection, 1,2-diheptyldiselenic ether obtained in step one and freshly distilled anhydrous tetrahydrofuran (400 mL) after reflux with calcium hydride were added to a dry 1 L three-necked flask and stirred to dissolve. A suspension of sodium borohydride (3.78 g, 0.10 mol) in 50 mL of anhydrous tetrahydrofuran was slowly added dropwise while cooling in an ice-water bath. After the addition was complete, the ice bath was removed, and stirring was continued at room temperature for 1 h to obtain an orange-red sodium selenohydride solution.

[0042] In another dry 500 mL flask, the sodium 8-bromooctyl sulfate obtained in step two was suspended in 200 mL of anhydrous tetrahydrofuran and sonicated to ensure thorough dispersion. This suspension was then slowly added dropwise to the sodium selenide solution using a constant-pressure dropping funnel over approximately 30 minutes. After the addition was complete, the reaction mixture was heated to 50 °C and stirred at this temperature for 6 hours. The reaction was monitored by TLC (evolving solvent: dichloromethane / methanol = 5:1) until the starting material spot disappeared.

[0043] After the reaction was complete, the reaction solution was cooled to room temperature and concentrated under reduced pressure to 1 / 3 of its original volume. The concentrate was slowly poured into 500 mL of ice-cold diethyl ether, and a large amount of white solid precipitated. The solution was filtered, and the solid was washed with cold diethyl ether (3 × 50 mL). The crude product was further purified by silica gel column chromatography (300-400 mesh silica gel, eluent gradient: dichloromethane → dichloromethane / methanol = 10:1 → 5:1). The fractions containing the target product were collected, combined, and concentrated under reduced pressure. The residue was recrystallized from the ethanol / diethyl ether mixture to give a white crystalline solid, namely sodium n-heptyl-selen-n-octyl sulfate.

[0044] Example 1 Iron-containing ceramic blanks (specifically composed of 45% kaolin, 30% quartz, and 25% potassium sodium feldspar, with iron impurities of 1.6%), sodium lignosulfonate, sodium n-heptyl-selen-n-octyl sulfate, and water were ball-milled. The ball-milling conditions were: a rolling ball mill, a material:ball:water mass ratio of 1:2:0.5, and a ball-milling time of 16 hours, to obtain the iron-containing ceramic slurry. The mass of sodium lignosulfonate is 0.6% of the dry weight of the iron-containing ceramic blank, and the mass of sodium n-heptyl-selenyl-n-octyl sulfate is 0.02% of the dry weight of the iron-containing ceramic blank.

[0045] Example 2 The only difference from Example 1 is that the sodium lignosulfonate content is 0.5% of the dry weight of the billet, and the sodium n-heptyl-selenyl-n-octyl sulfate content is 0.05% of the dry weight of the billet.

[0046] Example 3 The only difference from Example 1 is that the amount of sodium lignosulfonate is 0.4% of the dry weight of the billet, and the amount of sodium n-heptyl-selenyl-n-octyl sulfate is 0.08% of the dry weight of the billet.

[0047] Comparative Example 1 The only difference from Example 1 is that no degumming agent is used.

[0048] Comparative Example 2 Sodium lignosulfonate is added at 0.5% of the dry weight of the billet. Sodium n-heptyl-selenyl-n-octyl sulfate is not added.

[0049] Comparative Example 3 The mainstream degumming agent in the industry is adopted. Specifically, the water glass content is 0.5% of the dry weight of the billet, and the sodium tripolyphosphate content is 0.3% of the dry weight of the billet.

[0050] Comparative Example 4 The mainstream degumming agent in the industry is used. Specifically, the water glass content is 0.5% of the dry weight of the billet.

[0051] Comparative Example 5 The sodium n-heptyl-selenyl-n-octyl sulfate content is 0.08% of the dry weight of the billet, without the addition of sodium lignosulfonate.

[0052] The performance of the iron-containing ceramic slurries prepared in the examples and comparative examples was tested, and the results are shown in Table 1. Among them: the outflow time was measured using a Ford 4 viscometer; the shorter the time, the better the fluidity. Fineness: determined by the commonly used sieving method in ceramics, i.e., using a 250-mesh sieve and measuring the sieve residue. Firing product: the presence or absence of black spots indicates the degree of slurry dispersibility; the presence of black spots indicates poor dispersibility, and the absence of black spots indicates good dispersibility.

[0053] Table 1 Performance of the mud in the examples and comparative examples

[0054] Note: The firing conditions for the fired products are as follows: firing in an oxidizing atmosphere in an electric furnace, heating rate of 3℃ / min, firing temperature of 1280℃, and natural cooling.

[0055] As shown in Table 1, the degumming agent provided by the present invention can effectively disperse iron-containing ceramic slurry, and the slurry has good fluidity and fineness.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A degumming agent, characterized in that, It consists of separately packaged lignin sulfonate and sodium n-heptyl-selenyl-n-octyl sulfate.

2. The degumming agent according to claim 1, characterized in that, The lignin sulfonate includes sodium lignin sulfonate or potassium lignin sulfonate.

3. The application of the desiccant according to claim 1 or 2 in the preparation of iron-containing ceramic slurry.

4. The application according to claim 3, characterized in that, The preparation method of the iron-containing ceramic slurry includes the following steps: The iron-containing ceramic blank, the deflocculant, and water are ball-milled and mixed to obtain the iron-containing ceramic slurry; the mass of lignin sulfonate in the deflocculant is 0.4-0.6% of the dry weight of the iron-containing ceramic blank, and the mass of sodium n-heptyl-selenyl-n-octyl sulfate is 0.02-0.08% of the dry weight of the iron-containing ceramic blank.

5. The application according to claim 4, characterized in that, The iron-containing ceramic blank has a dry weight ratio of 2:1 to water.

6. The application according to claim 4, characterized in that, On a dry weight basis, the iron content in the iron-containing ceramic blank is 0.05-10%.

7. The application according to claim 4, characterized in that, On a dry weight basis, the iron-containing ceramic blank comprises 40-50% clay, 25-35% quartz and 20-30% feldspar.

8. The application according to claim 4, characterized in that, The mass of the lignin sulfonate is 0.5% of the dry weight of the iron-containing ceramic blank.

9. The application according to claim 4, characterized in that, The fineness of the iron-containing ceramic slurry reaches a sieve residue of less than 1.1% on a 250-mesh sieve.

10. The application according to claim 7, characterized in that, The clay includes kaolin; the feldspar includes potassium-sodium feldspar.

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