Preparation method of antimony trioxide nanoparticles

Abstract

The invention relates to the field of inorganic materials, in particular to a preparation method of antimony trioxide nanoparticles, which specifically comprises the following steps: uniformly mixing antimony sulfide ore with inorganic fused salt, transition metal oxide and a carbon material, grinding into powder, pressing the powder into blocks, smelting to obtain molten liquid, separating crude antimony from the molten liquid, dissolving the crude antimony with hydrochloric acid, and drying to obtain the antimony trioxide nanoparticles. Adding high-purity antimony powder, stirring and reacting to obtain an antimony trichloride crude solution, filtering the antimony trichloride crude solution, adding ammonia water and ionic liquid into the obtained filtrate, stirring and reacting, collecting a product, and drying. The inorganic molten salt contains metal fluoride, and antimony trioxide prepared by the method not only has a cubic crystal form, but also has a nano size, and is higher in economic added value and wider in application prospect.

Description

Technical Field

[0001] This invention relates to the field of inorganic materials, specifically to a method for preparing antimony trioxide nanoparticles. Background Technology

[0002] Antimony trioxide (STI) possesses unique physicochemical properties, making it an important and widely used industrial agent. It is commonly used as a white pigment in paints, plastics, and synthetic rubber, as well as a flame retardant, catalyst, and decolorizing agent in the chemical industry. STI exists in two crystal forms: cubic and orthorhombic. The crystal form significantly influences its properties; cubic STI has high whiteness and good light stability, while orthorhombic STI has low whiteness and is unstable under light. Currently, the cubic STI produced using existing technologies often struggles to achieve nanoscale dimensions, resulting in low economic added value. Summary of the Invention

[0003] Objective of the invention: To address the above-mentioned technical problems, this invention proposes a method for preparing antimony trioxide nanoparticles.

[0004] The technical solution adopted is as follows: A method for preparing antimony trioxide nanoparticles: Antimony sulfide ore is mixed with inorganic molten salt, transition metal oxides and carbon materials and ground into powder. The powder is pressed into blocks and then melted to obtain a molten liquid. Crude antimony is separated from the molten liquid and dissolved in hydrochloric acid. High-purity antimony powder is added and stirred to obtain a crude antimony trichloride solution. The crude antimony trichloride solution is filtered, and ionic liquid and ammonia are added to the obtained filtrate. After stirring and reacting, the product is collected and dried. The inorganic molten salt contains metal fluorides.

[0005] Furthermore, the mass fraction of antimony in the antimony sulfide ore is ≥35%.

[0006] Furthermore, the metal fluoride accounts for 1-10 wt% of the inorganic molten salt.

[0007] Furthermore, the metal fluoride is lanthanum fluoride. Furthermore, the inorganic molten salt is composed of sodium carbonate, sodium chloride, and metal fluoride.

[0008] Antimony sulfide can react with sodium carbonate in the following way: Sb2S3+3Na2CO3+6C→2Sb+3Na2S+9CO Na₂S + ZnO + CO₂ → Na₂CO₃ + ZnS The generated Na2S then reacts with transition metal oxides and CO2 to regenerate sodium carbonate, meaning that sodium carbonate retains its chemical form before and after smelting, thus achieving sodium carbonate regeneration.

[0009] Sodium chloride is not a standalone reagent, but rather forms the molten salt medium together with sodium carbonate. Its core function is to significantly improve the physicochemical properties of the molten salt system, creating crucial conditions for the efficient and clean extraction of metallic antimony. Sodium carbonate has a high melting point, requiring high start-up and maintenance temperatures when used alone. Sodium chloride has a lower melting point. When the two are mixed in a specific ratio, they form a eutectic mixture, allowing the molten salt system to remain in a molten state at lower temperatures. This directly reduces energy consumption and is a prerequisite for achieving "low-temperature" smelting. The fluidity of the molten salt is crucial for mass transfer efficiency and metal sedimentation and separation. The addition of sodium chloride effectively reduces the viscosity of the molten salt, achieving optimal fluidity, which has a significant impact on antimony recovery. Good fluidity ensures efficient diffusion and contact of reactants in the molten salt, allowing the reduction and desulfurization reaction to proceed rapidly and completely.

[0010] The addition of metal fluorides can improve the grade and yield of crude antimony. This may be because metal fluorides have a high melting point, and most of them do not melt or react immediately after being added alone. They tend to agglomerate into spherical particles, forming slag-like substances. They can selectively adsorb iron, lead, and copper sulfides or their reaction products with sodium carbonate and transition metal oxides. However, antimony sulfide and antimony have a weaker affinity for metal fluorides, so the amount adsorbed on their surface is less. Therefore, this not only improves the antimony extraction rate but also reduces the difficulty of subsequent separation and purification.

[0011] Furthermore, the transition metal oxide is zinc oxide and / or iron oxide.

[0012] The core function of transition metal oxides is to combine with sulfur in the reaction of antimony sulfide concentrate, fixing it in the smelting slag in the form of transition metal sulfides, thereby fundamentally avoiding the generation of sulfur dioxide flue gas and realizing the regeneration of sodium carbonate.

[0013] Furthermore, the mass ratio of antimony sulfide ore, inorganic molten salt, transition metal oxide and carbon material is 1:5-10:0.5-0.7:0.3-0.5.

[0014] In this invention, carbon materials refer to non-metallic materials whose entire composition is elemental carbon. Specifically, activated carbon, graphite, diamond, graphene, and carbon nanotubes can be selected, with carbon powder being the preferred option considering cost.

[0015] The acid leaching solution contains a certain amount of Sb 5+ To ensure the quality of the final product, metal ion impurities need to be reduced to Sb. 3+ Therefore, metallic antimony is the best reducing agent. Adding a certain amount of antimony powder to the acid leaching solution can reduce Sb. 5+ Restore to Sb 3+It also replaces metal ion impurities with weaker metallic properties than antimony, thereby achieving further purification, while excess antimony powder can be filtered and recycled.

[0016] Furthermore, the pressure during pressing is 10-100 MPa. Furthermore, the melting temperature is 850-950℃.

[0017] Furthermore, the ionic liquid is an imidazole chloride ionic liquid.

[0018] In existing technologies, tartaric acid, tartrates, or EDTA are often used as transforming agents to prepare cubic antimony trioxide. In this invention, the imidazole chloride ionic liquid simultaneously contains inorganic anions and organic cations (π-π stacking of the imidazole ring or Cl...). - The coordination ability of antimony can alter the hydrolysis process of antimony ions, the growth units of crystal nuclei, their dimensions, and their interconnections. It can form specific adsorption on the surface of cubic antimony oxide crystal nuclei, stabilizing their crystal structure. In contrast, the interaction with the surface of orthorhombic crystal nuclei is weaker, making it difficult to form stable growth centers, thus inhibiting the formation of orthorhombic crystals.

[0019] The beneficial effects of this invention are: This invention provides a method for preparing antimony trioxide nanoparticles. Molten salt smelting involves the reduction and sulfur fixation reaction of antimony sulfide ore and transition metal oxides in molten salt under the action of a reducing agent carbon material, generating metallic antimony and transition metal sulfides. The addition of metal fluorides can improve the reaction yield, possibly because metal fluorides have a high melting point. When added alone, most of them do not melt or react immediately, but easily agglomerate into spherical particles, forming slag-like substances. They can selectively adsorb iron, lead, and copper sulfides or their reaction products with sodium carbonate and transition metal oxides. However, antimony sulfide has a weak affinity for metal fluorides, resulting in less adsorption on its surface. Therefore, this method not only improves the antimony extraction rate but also reduces the difficulty of subsequent separation and purification.

[0020] In existing technologies, tartaric acid, tartrates, or EDTA are often used as transforming agents to prepare cubic antimony trioxide. In this invention, the ionic liquid simultaneously contains interactions with inorganic anions and organic cations (π-π stacking of imidazole rings or Cl-). - The coordination ability of antimony can alter the hydrolysis process of antimony ions, the growth units of crystal nuclei, their dimensions, and their interconnections. It can form specific adsorption on the surface of cubic antimony oxide crystal nuclei, stabilizing their crystal structure. In contrast, the interaction with the surface of orthorhombic crystal nuclei is weaker, making it difficult to form stable growth centers, thus inhibiting the formation of orthorhombic crystals.

[0021] The antimony trioxide prepared by the method of this invention not only has a cubic crystal form but also a nanoscale size, resulting in higher economic added value and broader application prospects. Attached Figure Description

[0022] Figure 1 The image shows the XRD pattern of antimony trioxide prepared in Example 1 of this invention. Detailed Implementation

[0023] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0024] Example 1: A method for preparing antimony trioxide nanoparticles: The chemical composition (mass fraction, %) of antimony sulfide ore is shown in the table below: Antimony sulfide ore was pulverized into 200-400 mesh powder and mixed with inorganic molten salt (composed of sodium carbonate, sodium chloride, and lanthanum fluoride in a mass ratio of 8:1.5:0.5), zinc oxide, and carbon powder in a mass ratio of 1:8:0.6:0.4. The mixture was then ground to obtain a homogeneous powder. This powder was pressed into test blocks using a single-column hydraulic press at 50 MPa. The test blocks were placed in a corundum crucible and then in a tube furnace. The mixture was smelted at 900℃ for 2 hours under a high-purity argon atmosphere to obtain a molten liquid. The bottom layer of the molten liquid was released and cooled at room temperature to obtain crude antimony (grade 96.32%). The crude antimony was crushed and added to a 10 mol / L... In L of hydrochloric acid, the solid-liquid mass ratio was 1:10. The solution was then stirred in a 40℃ water bath for 120 min to dissolve the antimony, yielding an acid leaching solution. High-purity antimony powder (1% of the crude antimony mass) was added to the acid leaching solution, and the mixture was stirred for 30 min to obtain a crude antimony trichloride solution. The crude antimony trichloride solution was filtered, and 1-butyl-3-methylimidazolium chloride (0.5% of the crude antimony mass) was added to the filtrate. Ammonia water was then added dropwise under stirring to adjust the pH to 9. After the addition was complete, the mixture was stirred for 30 min, centrifuged, and the product was collected and vacuum dried to obtain cubic antimony trioxide nanoparticles. The XRD pattern of these nanoparticles is shown below. Figure 1 The results are consistent with the standard spectrum of cubic antimony trioxide, with a purity of 99.96% and a particle size distribution of d. 10 =272nm, d 50 =446nm, d 90 =862nm.

[0025] Example 2: A method for preparing antimony trioxide nanoparticles: The chemical composition (mass fraction, %) of antimony sulfide ore is shown in the table below: Antimony sulfide ore was pulverized into 200-400 mesh powder and mixed with inorganic molten salt (composed of sodium carbonate, sodium chloride, and lanthanum fluoride in a mass ratio of 8:1.5:0.5), zinc oxide, and carbon powder in a mass ratio of 1:10:0.7:0.5. The mixture was then ground to obtain a homogeneous powder. This powder was pressed into test blocks using a single-column hydraulic press at 100 MPa. The test blocks were placed in a corundum crucible and then in a tube furnace. The mixture was smelted at 950℃ for 2 hours under a high-purity argon atmosphere to obtain a molten liquid. The bottom layer of the molten liquid was released and cooled at room temperature to obtain crude antimony (grade 96.10%). The crude antimony was crushed and added to a 10 mol / L... In hydrochloric acid, the solid-liquid mass ratio was 1:10. The solution was then stirred in a 40℃ water bath for 120 min to dissolve the antimony, yielding an acid leaching solution. High-purity antimony powder (1% of the crude antimony mass) was added to the acid leaching solution, and the mixture was stirred for 30 min to obtain a crude antimony trichloride solution. The crude antimony trichloride solution was filtered, and 1-butyl-3-methylimidazolium chloride (1% of the crude antimony mass) was added to the filtrate. Ammonia water was then added dropwise under stirring to adjust the pH to 9. After the addition was complete, the mixture was stirred for 30 min, centrifuged, and the product was collected and vacuum dried to obtain cubic antimony trioxide nanoparticles with a purity of 99.94% and a particle size distribution of: d 10 =334nm, d 50 =482nm, d 90 =905nm.

[0026] Example 3: A method for preparing antimony trioxide nanoparticles: The chemical composition (mass fraction, %) of antimony sulfide ore is shown in the table below: Antimony sulfide ore was pulverized into 200-400 mesh powder and mixed with inorganic molten salt (sodium carbonate, sodium chloride, and lanthanum fluoride in a mass ratio of 8:1.5:0.5), zinc oxide, and carbon powder in a mass ratio of 1:5:0.5:0.3. The mixture was then ground to obtain a homogeneous powder. This powder was pressed into test blocks using a single-column hydraulic press at 10 MPa. The test blocks were placed in a corundum crucible and then in a tube furnace. The mixture was smelted at 850℃ for 2 hours under a high-purity argon atmosphere to obtain a molten liquid. The bottom layer of the molten liquid was released and cooled at room temperature to obtain crude antimony (grade 95.69%). The crude antimony was crushed and added to 10 mol / L hydrochloric acid. In the process, the solid-liquid mass ratio was 1:10. The solution was then stirred in a 40℃ water bath for 120 min to dissolve the antimony, yielding an acid leaching solution. High-purity antimony powder (1% of the crude antimony mass) was added to the acid leaching solution, and the mixture was stirred for 30 min to obtain a crude antimony trichloride solution. The crude antimony trichloride solution was filtered, and 1-butyl-3-methylimidazolium chloride (0.1% of the crude antimony mass) was added to the filtrate. Ammonia water was then added dropwise under stirring to adjust the pH to 9. After the addition was complete, the mixture was stirred for 30 min, centrifuged, and the product was collected and vacuum dried to obtain cubic antimony trioxide nanoparticles with a purity of 99.92% and a particle size distribution of d. 10 =204nm, d 50 =413nm, d 90 =850nm.

[0027] Example 4: A method for preparing antimony trioxide nanoparticles: The chemical composition (mass fraction, %) of antimony sulfide ore is shown in the table below: Antimony sulfide ore was crushed into 200-400 mesh powder and mixed with inorganic molten salt (sodium carbonate, sodium chloride, and lanthanum fluoride in a mass ratio of 8:1.5:0.5), zinc oxide, and carbon powder in a mass ratio of 1:10:0.5:0.5. The mixture was then ground to obtain a homogeneous powder. This powder was pressed into test blocks using a single-column hydraulic press at 50 MPa. The test blocks were placed in a corundum crucible and then in a tube furnace. The mixture was smelted at 850℃ for 2 hours under a high-purity argon atmosphere to obtain a molten liquid. The bottom layer of the molten liquid was released and cooled at room temperature to obtain crude antimony (grade 94.97%). The crude antimony was crushed and added to 10 mol / L hydrochloric acid. In the process, the solid-liquid mass ratio was 1:10. The solution was then stirred in a 40℃ water bath for 120 min to dissolve the antimony, yielding an acid leaching solution. High-purity antimony powder (1% of the crude antimony mass) was added to the acid leaching solution, and the mixture was stirred for 30 min to obtain a crude antimony trichloride solution. The crude antimony trichloride solution was filtered, and 1-butyl-3-methylimidazolium chloride (0.1% of the crude antimony mass) was added to the filtrate. Ammonia water was then added dropwise under stirring to adjust the pH to 9. After the addition was complete, the mixture was stirred for 30 min, centrifuged, and the product was collected and vacuum dried to obtain cubic antimony trioxide nanoparticles with a purity of 99.91% and a particle size distribution of d. 10 =255nm, d 50 =439nm, d 90 =842nm.

[0028] Comparative Example 1: It is basically the same as Example 1, except that the inorganic molten salt does not contain lanthanum fluoride; The prepared crude antimony grade was 87.42%, and the obtained product was antimony trioxide with cubic crystal form, purity 99.17%, and particle size distribution: d 10 =294nm, d 50 =456nm, d 90 =912nm; A comparison between Example 1 and Comparative Example 1 shows that the addition of lanthanum fluoride can improve the grade of the prepared crude antimony.

[0029] Comparative Example 2: This is basically the same as Example 1, except that 1-butyl-3-methylimidazolium chloride is not added; The prepared crude antimony grade was 94.26%, and the obtained product was antimony trioxide with orthorhombic crystal form, purity 99.89%, and particle size distribution: d 10 =9.17μm, d 50 =30.46μm, d 90 =82.89μm; A comparison between Example 1 and Comparative Example 2 shows that the addition of 1-butyl-3-methylimidazolium chloride can regulate the crystal form of the generated antimony trioxide and refine its particle size.

[0030] Comparative Example 3: This is basically the same as Example 1, except that ammonium tartrate is used instead of 1-butyl-3-methylimidazolium chloride. The prepared crude antimony grade was 94.80%, and the obtained product was antimony trioxide with cubic crystal form, purity 99.93%, and particle size distribution: d 10 =3.17μm, d 50 =22.52μm, d 90 =53.08μm; A comparison between Example 1 and Comparative Example 3 shows that, compared to ammonium tartrate, the addition of 1-butyl-3-methylimidazolium chloride can effectively control the particle size of the generated antimony trioxide.

[0031] Comparative Example 4: This is essentially the same as Example 1, except that EDTA is used instead of 1-butyl-3-methylimidazolium chloride. The prepared crude antimony grade was 93.88%, and the obtained product was antimony trioxide with cubic crystal form, purity 99.92%, and particle size distribution: d 10 =2.41μm, d 50 =15.06μm, d 90 =35.60μm.

[0032] A comparison between Example 1 and Comparative Example 4 shows that, compared to EDTA, the addition of 1-butyl-3-methylimidazolium chloride can effectively control the particle size of the generated antimony trioxide.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing antimony trioxide nanoparticles, characterized in that, Antimony sulfide ore is mixed with inorganic molten salt, transition metal oxides and carbon materials and ground into powder. The powder is pressed into blocks and then melted to obtain a molten liquid. Crude antimony is separated from the molten liquid and dissolved in hydrochloric acid. High-purity antimony powder is added and stirred to obtain a crude antimony trichloride solution. The crude antimony trichloride solution is filtered, and ionic liquid and ammonia are added to the obtained filtrate. After stirring and reacting, the product is collected and dried. The inorganic molten salt contains metal fluorides.

2. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The antimony content in the antimony sulfide ore is ≥35% by mass.

3. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The metal fluoride accounts for 1-10 wt% of the inorganic molten salt.

4. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The metal fluoride is lanthanum fluoride.

5. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The inorganic molten salt is composed of sodium carbonate, sodium chloride, and metal fluoride.

6. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The transition metal oxide is zinc oxide and / or iron oxide.

7. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The mass ratio of antimony sulfide ore, inorganic molten salt, transition metal oxides and carbon materials is 1:5-10:0.5-0.7:0.3-0.

5.

8. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The pressure during pressing is 10-100 MPa.

9. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The melting temperature is 850-950℃.

10. The method for preparing antimony trioxide nanoparticles as described in claim 1, characterized in that, The ionic liquid is an imidazole chloride ionic liquid.

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