Fluoride-free and nitrate-free cast iron enamel low-temperature acid-resistant ground coat and its preparation method and application

Abstract

The application discloses a cast iron enamel low-temperature acid-resistant base glaze without fluorinated salt and nitrate, and a preparation method and application thereof, and belongs to the technical field of enamel. The base glaze is prepared from quartz, zero-water borax, soda ash, calcium carbonate, titanium white, potassium feldspar, lithium carbonate and recycled ternary battery positive electrode material according to specific mass proportions. The preparation comprises raw material mixing, smelting at 1300+ / -10 DEG C under a pure oxygen environment, and rapid cooling after wire drawing detection of the smelting state. The base glaze completely avoids the use of fluorinated salt and nitrate, eliminates the fluorine emission and environmental protection equipment blockage problem from the source, the fluorine content of the product is not detected, and the limit value requirement of the EU REACH regulation is met. Meanwhile, by introducing the recycled ternary battery material, the adhesion of the base glaze is obviously enhanced, the synergistic effect between components is strengthened, other performances are promoted, and resource recycling and cost reduction are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of enamel technology, and particularly relates to a cast iron enamel low-temperature acid-resistant ground glaze without fluorinated salt and nitrate, and a preparation method and application thereof. BACKGROUND

[0002] As a transition layer between the metal substrate and the face glaze, the adhesion and firing performance of the enamel ground glaze directly affect the product quality, and the green environmental protection affects the survival and sustainable development of the industry. In the traditional enamel ground glaze formula, fluorinated salt (such as fluorite, sodium fluorosilicate) (accounting for 1-15%) is usually added as a fluxing agent and adhesion enhancer. The fluorinated salt is not an "optional" additive in the traditional enamel ground glaze, but an "indispensable" skeleton component. It lays the foundation for the firm combination of the glaze and the metal substrate from the physical and chemical dimensions through multiple synergies such as reducing the melting temperature, forming an alloy layer by corroding the interface, creating a mechanical anchoring effect, improving opalescence and wettability. Simply and roughly removing the fluorinated salt is equivalent to removing the load-bearing wall of the building, which does not lead to a "decrease" in performance, but a "collapse" of the entire enamel system. Any attempt to eliminate fluorinated salt must be based on the discovery or invention of a new substance or new process system that can completely simulate or replace the above-mentioned multiple functions, and this has so far been a major technical challenge in the enamel process field. Therefore, the importance of fluorinated salt in the traditional process cannot be overemphasized. However, research has shown that:

[0003] 1. Hydrogen fluoride (HF) and silicon tetrafluoride (SiF4) gases released during high-temperature melting process cause harm to health and the environment.

[0004] 2. The European Union REACH regulation lists fluorides as substances of very high concern (SVHC), and fluorinated salt products cannot meet the EU REACH regulation requirements for fluorine, with a fluorine (F) limit of 20 mg / kg.

[0005] 3. End environmental management equipment is blocked by fluorinated salt crystallization, severely restricting normal production of enterprises.

[0006] At the same time, nitrate, as a traditional oxidizing agent and adhesion promoting component, is prone to produce nitrogen oxides (NO x ) during high-temperature decomposition, also facing environmental pressure. Currently, the removal of nitrate from enamel glaze has solved the problem of nitrogen oxide emissions (such as CN114368912B, CN114315150B, CN114315151B, etc.), and further development of a fluorine-free and nitrate-free system is not only a necessary choice to respond to regulations, but also a forward-looking technical layout for the future.

[0007] The replacement of fluorinated salt is a major technical bottleneck at present, mainly reflected in:

[0008] (1) Fluorinated salt dependence is strong, and environmental risk is prominent: CN119710693A (high-temperature-resistant enamel glaze) uses cryolite (Na3AlF6) as a fluxing agent, although it improves temperature resistance, but does not solve the problem of fluorine emission; CN112342544A (low-temperature acid and alkali resistant cast iron enamel) contains sodium fluoride (5-7 parts) in the face glaze formula.

[0009] (2) Non-fluorine substitution scheme has functional defects: CN105800935A (enamel underglaze material) attempts to use lanthanide oxides to enhance adhesion, but it still needs to add 8% fluorine to assist melting, and the high cost of rare earth makes it difficult to promote. CN116854374A (black enamel composite glaze) uses a cobalt-nickel underglaze system, but the anti-explosive agent used contains 8-10% fluorite powder.

[0010] (3) The field of ceramics involves fluorine-free schemes, but it is difficult to migrate and apply: CN110885189A relates to a zirconium-free tallow enamel and a positioning crystal flower ceramic tile made using the same, CN115626774A relates to a soft light skin ceramic rock plate and a preparation method thereof, CN112979271A relates to a preparation method of a light-weight high-strength pure-color glaze tile, and CN118754723A relates to a hydrophilic self-cleaning antique tile based on phase separation and a preparation method thereof. Although the above-mentioned prior art does not involve the use of fluorinated salt, its technical essence belongs to the field of building ceramic glaze, which is different from the field of enamel underglaze. There are essential differences between ceramic glaze and metal-based enamel glaze in terms of thermal expansion coefficient (the difference in expansion coefficient between the two is one order of magnitude), firing temperature (the firing temperature of ceramic glaze is higher than that of enamel glaze by more than 200°C), and bonding mechanism (the body of ceramic glaze is porcelain clay, while the body of enamel glaze is metal), thus it cannot be directly applied to the field of metal-based enamel.

[0011] In summary, on the basis of denitrification, the problem of defluorination is solved, and the quality of enamel products is improved, which has very important practical significance for promoting the green, low-carbon and high-quality development of the enamel industry. SUMMARY

[0012] In view of the excessive emission of fluorides in the production process of existing enamel glaze, which causes damage to health and the environment, the fluorinated salt-containing products cannot meet the requirements of the EU REACH regulation on fluorine, and the emitted fluorinated salt blocks environmental management facilities, which seriously restricts the normal production of enterprises, the present application provides a cast iron enamel low-temperature acid-resistant underglaze without fluorinated salt and nitrate, as well as a preparation method and application thereof.

[0013] The fluorine-free salt-free nitrate-free cast iron enamel low-temperature acid-resistant bottom glaze of the present application is composed of the following components in the following mass parts: quartz 46-50 parts, zero-water borax 27-30 parts, soda ash 6-9 parts, calcium carbonate 4.5-5.5 parts, titanium white 3.0-4.0 parts, potassium feldspar 2.0-3.5 parts, lithium carbonate 3.5-4.5 parts, and recycled ternary battery positive material 3.2-4.4 parts, wherein the recycled ternary battery positive material is a lithium, nickel, cobalt and manganese-containing powder material recovered from waste ternary lithium battery positive material.

[0014] Further, the quartz is 47-48 parts, the zero-water borax is 27-28 parts, the soda ash is 7-8 parts, the calcium carbonate is 4.5-5.0 parts, the titanium white is 3.0-3.5 parts, the potassium feldspar is 2.0-3.0 parts, the lithium carbonate is 3.5-4.0 parts, and the recycled ternary battery positive material is 3.4-4.0 parts.

[0015] Further, the mass percentage of SiO2 in the quartz is ≥99%, the mass percentage of SiO2 in the potassium feldspar is ≥71%, and K2O+Na2O is ≥11%, the mass percentage of TiO2 in the titanium white is ≥99%, and in the recycled ternary battery positive material, the mass percentage of Co, Ni, Mn and Li in the total mass of the material is ≥12.5wt%, ≥30.2wt%, ≥12.2wt% and ≥5.9wt% respectively, and the other raw materials are of industrial grade purity.

[0016] Further, the recycled ternary battery positive material is a commercially available material, which meets the above-mentioned percentage contents of lithium, nickel, cobalt and manganese, and other impurities contained therein do not affect the performance and use of the bottom glaze.

[0017] The preparation method of the fluorine-free salt-free nitrate-free cast iron enamel low-temperature acid-resistant bottom glaze described above comprises the following steps:

[0018] (1) The raw materials are weighed according to the above mass parts;

[0019] (2) The raw materials in step (1) are stirred and mixed uniformly;

[0020] (3) The uniformly mixed material is added to a melting furnace for melting, and pure oxygen environment is used in the melting furnace, and the temperature is controlled at 1300±10℃;

[0021] (4) After the material in step (3) is completely melted, a borosilicate glass body is obtained, the molten borosilicate glass body is tapped, and is quickly drawn into a 1.2-1.5 meter glass filament for detection, and the detection requirement is that no node continues to melt for 10-15 minutes within 1 meter of the glass filament, which is the completion of melting;

[0022] (5) The molten borosilicate glass body is rapidly cooled, and the product is obtained.

[0023] Further, in step (5), the rapid cooling is performed by water quenching or tabletting.

[0024] The application of the cast iron enamel low-temperature acid-resistant base glaze without fluorinated salt and nitrate salt is applied to a blank with a cast iron base body, and the firing temperature of the finished product is 740-760 DEG C.

[0025] The application introduces the recycled ternary battery positive material into the cast iron enamel low-temperature acid-resistant base glaze formula, so that the adhesion of the base glaze is obviously enhanced, the synergistic effect between components is strengthened, and the promotion of the base glaze porcelain surface, gloss and other performances is promoted.

[0026] The application has the following beneficial effects:

[0027] (1) The fluorinated salt is discharged in an ultra-low standard;

[0028] (2) The product is detected by SGS, the fluorinated salt detection result shows that it is not detected, and the limit value requirement of SVHC (high concern material) of the EU REACH regulation is met.

[0029] (3) The end environmental protection equipment blockage problem is solved: by completely removing the fluorinated salt (fluorite, sodium fluorosilicate, etc.), the fluorinated salt crystallization source is eliminated from the source, and the end environmental protection equipment blockage problem is solved. According to the actual measurement of the production line, the continuous operation period of the equipment is prolonged from the original 10-15 days to more than 180 days, and the maintenance cost is significantly reduced.

[0030] (4) The core performance of the base glaze is not attenuated: by replacing the fluorinated salt with the recycled ternary battery positive material, the adhesion grade is 1-2 (the traditional fluorine-containing base glaze is 1-2).

[0031] (5) Low-temperature firing adaptability: the eutectic composite fluxing system (multi-element carbonate + borate) interacts with other components, so that the firing temperature is stably controlled at 740-760 DEG C, the porcelain layer flow flatness and bubble elimination rate are equivalent to those of the fluorine-containing base glaze.

[0032] (6) Resource recycling and cost optimization: the use of recycled ternary battery positive material not only reduces the cost of cobalt-nickel-lithium raw materials by more than 25%, but also avoids heavy metal waste pollution. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The photo of the enamel plate made of cast iron for the product obtained in example 1 of the application. DETAILED DESCRIPTION

[0034] The application will be further described in detail below in combination with specific embodiments, but the application is not limited thereto.

[0035] The equipment used in the embodiments of the application is:

[0036] Batching: The full-automatic batching and mixing system is adopted. The system is fully automatic computer control, which has the characteristics of accurate weighing, uniform mixing and high batching efficiency.

[0037] Melting: The automatic feeding system, automatic pure oxygen combustion control system and automatic discharging system are adopted.

[0038] Packaging: The automatic packaging system is adopted.

[0039] In addition to the recovered ternary battery positive electrode material, the purity of the raw materials used in the embodiment meets the requirements of the industrial grade.

[0040] Example 1

[0041] (1) The raw materials are weighed according to the mass parts of each component as follows:

[0042] 46 parts of quartz, 30 parts of anhydrous borax, 7 parts of soda ash, 4.5 parts of lithium carbonate, 4.5 parts of calcium carbonate, 3 parts of titanium white, 2 parts of potassium feldspar, 3.2 parts of recovered ternary battery positive electrode material,

[0043] The mass percentage of SiO2 in quartz is ≥99%, the mass percentage of SiO2 in potassium feldspar is ≥71%, K2O+Na2O is ≥11%, the mass percentage of TiO2 in titanium white is ≥99%, and in the recovered ternary battery positive electrode material, the mass percentage of Co, Ni, Mn and Li in the total mass of the material is ≥12.5wt%, ≥30.2wt%, ≥12.2wt% and ≥5.9wt% respectively, and the other raw materials are of industrial purity.

[0044] (2) The above raw materials are stirred and mixed uniformly.

[0045] (3) The uniformly mixed material is added to the melting furnace for melting. Pure oxygen environment is adopted in the melting furnace during melting, and the temperature is controlled at 1300±10℃ for melting.

[0046] (4) After the above material is completely melted, a borosilicate glass body is obtained. The molten borosilicate glass body is tapped and quickly drawn into a glass filament of 1.2-1.5 meters for detection. The detection requirement is that no node continues to melt for 10 minutes within 1 meter of the glass filament, which is the completion of melting.

[0047] (5) The melted borosilicate glass body is water quenched, and the product is obtained.

[0048] The photo of the product obtained in Example 1 applied to the enamel plate made of cast iron is shown in Figure 1 The cast iron enamel low-temperature bottom glaze enamel surface is flat and delicate, the low-temperature sintering performance and adhesion performance are excellent, the acid resistance is A level or above, and it is widely used in cast iron enamel products.

[0049] Example 2

[0050] The preparation process of this embodiment is basically the same as that of Example 1, except that the mass parts of each component in step (1) are: quartz 47 parts, anhydrous borax 27.1 parts, soda ash 8 parts, lithium carbonate 3.5 parts, calcium carbonate 4.5 parts, titanium dioxide 4 parts, potassium feldspar 2.5 parts, and recycled ternary battery cathode material 3.4 parts.

[0051] Example 3

[0052] The preparation process of this embodiment is basically the same as that of Example 1, except that the mass parts of each component in step (1) are: quartz 48 parts, anhydrous borax 28 parts, soda ash 6 parts, lithium carbonate 4 parts, calcium carbonate 5.5 parts, titanium dioxide 3.5 parts, potassium feldspar 3 parts, and recycled ternary battery cathode material 4 parts.

[0053] Example 4

[0054] The preparation process of this embodiment is basically the same as that of embodiment 1, except that the mass parts of each component in step (1) are: 50 parts of quartz, 27 parts of anhydrous borax, 9 parts of soda ash, 3.5 parts of lithium carbonate, 5 parts of calcium carbonate, 4 parts of titanium dioxide, 3.5 parts of potassium feldspar, and 4.4 parts of recycled ternary battery cathode material.

[0055] Comparative Example 1

[0056] The rest is the same as in Example 1, except that the mass parts of each component in step (1) are: quartz 47.5 parts, anhydrous borax 26.6 parts, soda ash 5.9 parts, manganese oxide 1.3 parts, cobalt oxide 0.7 parts, sodium fluorosilicate 3.9 parts, titanium dioxide 3.5 parts, potassium feldspar 2.0 parts, and lithium carbonate 3.6 parts.

[0057] The test results of the products obtained from the above embodiments and comparative examples are shown in Table 1 below.

[0058] Table 1. Test results of products obtained from each embodiment and comparative example.

[0059]

[0060] The above embodiments and test results demonstrate that the low-temperature acid-resistant base glaze for cast iron enamel, which is free of fluoride salts and nitrates and produced by the method of the present invention, produces no fluorides during the preparation process. The various properties of the resulting product (ceramic surface, acid resistance, gloss, adhesion, firing temperature) all meet the requirements of low-temperature acid-resistant base glaze for cast iron enamel. The fluoride test results show that no fluoride was detected, which meets the limit requirements of the EU REACH regulation for SVHC (substances of very high concern). This fundamentally solves the technical problems of existing low-temperature acid-resistant base glazes for cast iron enamel generating fluoride gas emissions that pollute the environment and the fluoride salts emitted that clog environmental protection facilities during the production process.

Claims

1. A low-temperature acid-resistant base enamel for cast iron that is free of fluoride salts and nitrates, characterized in that, The formula consists of the following components by weight: quartz 46-50 parts, anhydrous borax 27-30 parts, soda ash 6-9 parts, calcium carbonate 4.5-5.5 parts, titanium dioxide 3.0-4.0 parts, potassium feldspar 2.0-3.5 parts, lithium carbonate 3.5-4.5 parts, and recycled ternary battery cathode material 3.2-4.4 parts. The recycled ternary battery cathode material is a powder material containing lithium, nickel, cobalt, and manganese obtained by recycling waste ternary lithium battery cathode materials.

2. The low-temperature acid-resistant base glaze for cast iron enamel that is free of fluoride salts and nitrates as described in claim 1, characterized in that, Quartz 47-48 parts, anhydrous borax 27-28 parts, soda ash 7-8 parts, calcium carbonate 4.5-5.0 parts, titanium dioxide 3.0-3.5 parts, potassium feldspar 2.0-3.0 parts, lithium carbonate 3.5-4.0 parts, recycled ternary battery cathode material 3.4-4.0 parts.

3. The low-temperature acid-resistant base glaze for cast iron enamel that is free of fluoride salts and nitrates as described in claim 1, characterized in that, In the recycling of ternary battery cathode materials, the percentage of metal mass in the total mass of the material is as follows: Co≥12.5wt%, Ni≥30.2wt%, Mn≥12.2wt%, and Li≥5.9wt%.

4. The low-temperature acid-resistant base glaze for cast iron enamel that is free of fluoride salts and nitrates as described in claim 1, characterized in that, The mass percentage of SiO2 in quartz is ≥99%.

5. The low-temperature acid-resistant base enamel for cast iron that is free of fluoride salts and nitrates as described in claim 1, characterized in that, The mass percentage of SiO2 in potassium feldspar is ≥71%, and the mass percentage of K2O+Na2O is ≥11%.

6. The low-temperature acid-resistant base glaze for cast iron enamel that is free of fluoride salts and nitrates as described in claim 1, characterized in that, In titanium dioxide, TiO2 accounts for ≥99% by mass.

7. The method for preparing a low-temperature acid-resistant base coat for cast iron enamel that is free of fluoride salts and nitrates as described in any one of claims 1 to 6, comprising the following steps: (1) Weigh the raw materials of each component; (2) Stir and mix the raw materials described in step (1) until they are evenly mixed; (3) Add the mixed material into the melting furnace for melting. The melting furnace is in a pure oxygen environment and the temperature is controlled at 1300±10℃. (4) After the material described in step (3) is completely melted, a borosilicate glass body is obtained. The molten borosilicate glass body is drilled and quickly drawn into a glass wire of 1.2 to 1.5 meters for testing. The testing requirement is: the glass wire is melted without knots within 1 meter for 10 to 15 minutes to complete the melting process. (5) The molten borosilicate glass body is rapidly cooled to obtain the product.

8. The preparation method according to claim 7, characterized in that, In step (5), the rapid cooling is achieved by water quenching or tableting.

9. The application of the low-temperature acid-resistant base glaze for cast iron enamel that is free of fluoride salts and nitrates as described in any one of claims 1 to 6, characterized in that, It is applied to blanks with cast iron as the base material, and the firing temperature of the finished product is 740-760℃.

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