Ceramic green body wet-method powdering process utilizing recycled waste materials

Abstract

The invention discloses a ceramic green body wet-method powdering process utilizing recycled waste materials. The process comprises the following steps: A, standing and precipitating ball washing slurry containing a dispergator; b, the sediment is pumped into a transfer pool, the polishing waste residues are put into the transfer pool to be mixed and ball-milled, and first slurry is obtained; c, adding water into the raw waste powder with the fineness of less than 250 meshes for slurrying, and removing iron and impurities by sieving to obtain second slurry; d, performing dry grinding on the hard clinker of which the water content is less than 5wt% to obtain hard cooked powder, preparing a green body raw material, mixing the hard cooked powder with the green body raw material, and performing ball milling to obtain third slurry; e, the first slurry, the second slurry and the third slurry are put into a large slurry tank to be homogenized, green body slurry is sprayed into a spray tower to be subjected to wet-method powder making, and ceramic powder is obtained. According to the scheme, on the premise that the production quality of the ceramic green bodies is guaranteed, the recycling waste is classified, the utilization ratio of the recycling waste is increased, and the raw material cost of the ceramic green bodies is reduced.

Description

Technical Field

[0001] This invention relates to the field of building ceramics technology, and in particular to a wet powder-making process for ceramic blanks using recycled waste materials. Background Technology

[0002] Traditional ceramic tile production consumes a large amount of energy and non-renewable mineral resources such as clay, feldspar, and quartz. Furthermore, the production process generates substantial waste. For example, in polished tile production, waste powder and washing slurry containing adhesive-removing agents are produced during raw material processing (including spillage of raw materials and slurry), washing, and floor rinsing. Waste powder is also generated during powder transportation. Waste blanks and waste powder are produced during molding, drying, and firing. After firing, the polishing process, including edge grinding, leveling, polishing (including coarse grinding, fine grinding, and polishing), fine edge grinding, and chamfering, generates waste tiles, brick slag, brick chips, abrasive particles, and other waste residue, as well as a large amount of wastewater. Similarly, the production of glazed tiles generates glaze slurry and washing slurry, among other waste materials related to the glaze. The above-mentioned waste materials vary greatly in composition and properties, including raw materials and calcined clinker. Some contain various harmful impurities such as metals, silicon carbide, and cement. The particle size and hardness of the various waste materials also differ. Therefore, how to recycle and reuse various types of waste residues and slurries in ceramic production to achieve green production is a difficult problem in terms of technical production control.

[0003] In addition, industries outside the ceramics industry, such as thermal power generation, electrolytic aluminum, lithium batteries, rare earth refining, and steel, also generate a large amount of solid waste residue, which urgently needs the assistance of the ceramics industry for disposal. Summary of the Invention

[0004] The purpose of this invention is to propose a wet powder production process for ceramic green bodies using recycled waste materials. Under the premise of ensuring the production quality of ceramic green bodies, the process improves the utilization rate of recycled waste materials by classifying and processing them, thereby reducing the raw material cost of ceramic green bodies and overcoming the shortcomings of the prior art.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A wet powder production process for ceramic green bodies utilizing recycled waste materials includes the following steps:

[0007] A. The ball washing mud containing the degumming agent is allowed to stand and settle to obtain the supernatant in the upper layer and the sediment in the lower layer;

[0008] B. The sediment from step A is extracted into a transfer tank, and the polishing waste is added into the transfer tank for mixing, stirring and homogenization to obtain a neutralized slurry; the neutralized slurry is then sieved to remove impurities and iron, and then ball-milled to obtain the first slurry; wherein the ball milling time is less than 2 hours;

[0009] C. Add water to the raw waste powder with a fineness of <250 mesh to make slurry, and obtain the second slurry after iron removal and sieving to remove impurities;

[0010] D. Hard clinker with a moisture content of <5wt% is dry-milled to obtain hard clinker powder. The raw materials for the ceramic body are prepared according to the raw material formula of the ceramic body to be produced. The hard clinker powder and the raw materials for the body are mixed and then added to a ball mill to obtain the third slurry.

[0011] E. The first slurry from step B, the second slurry from step C, and the third slurry from step D are fed into a large slurry tank for homogenization to obtain a green body slurry. The green body slurry is then sprayed into a spray tower for wet powdering to obtain ceramic powder.

[0012] Preferably, in step D, the fineness of the hard cooked powder is <100 mesh.

[0013] Preferably, in step B, the first slurry has a water content of 28-35 wt%, a residue of 0.5-1.5 wt% on a 250-mesh sieve, a specific gravity of 1.68-1.73, and a flow rate of 25-60 s.

[0014] Preferably, in step D, the third slurry has a water content of 28-35 wt%, a residue of 0.5-1.5 wt% on a 250-mesh sieve, a specific gravity of 1.68-1.73, and a flow rate of 25-60 s.

[0015] Preferably, in step C, the water is the supernatant from step A.

[0016] The technical solution provided by this invention may include the following beneficial effects:

[0017] This solution proposes a wet powder production process for ceramic green bodies using recycled waste. While ensuring the production quality of ceramic green bodies, it improves the utilization rate of recycled waste by classifying and processing the recycled waste, thereby reducing the raw material cost of ceramic green bodies and overcoming the shortcomings of existing technologies. Detailed Implementation

[0018] A wet powder production process for ceramic green bodies utilizing recycled waste materials includes the following steps:

[0019] A. The ball washing mud containing the degumming agent is allowed to stand and settle to obtain the supernatant in the upper layer and the sediment in the lower layer;

[0020] B. The sediment from step A is extracted into a transfer tank, and the polishing waste is added into the transfer tank for mixing, stirring and homogenization to obtain a neutralized slurry; the neutralized slurry is then sieved to remove impurities and iron, and then ball-milled to obtain the first slurry; wherein the ball milling time is less than 2 hours;

[0021] C. Add water to the raw waste powder with a fineness of <250 mesh to make slurry, and obtain the second slurry after iron removal and sieving to remove impurities;

[0022] D. Hard clinker with a moisture content of <5wt% is dry-milled to obtain hard clinker powder. The raw materials for the ceramic body are prepared according to the raw material formula of the ceramic body to be produced. The hard clinker powder and the raw materials for the body are mixed and then added to a ball mill to obtain the third slurry.

[0023] E. The first slurry from step B, the second slurry from step C, and the third slurry from step D are fed into a large slurry tank for homogenization to obtain a green body slurry. The green body slurry is then sprayed into a spray tower for wet powdering to obtain ceramic powder.

[0024] To achieve the reuse of various recycled waste materials in the field of building ceramics while ensuring the production quality of ceramic products, this technical solution proposes a wet powdering process for ceramic green bodies using recycled waste materials. Based on the characteristics of various recycled waste materials, they are first classified, then pre-treated according to their characteristics, and finally fed into a large slurry tank for spray granulation in proportion. This helps to increase the utilization rate of recycled waste materials and reduce the raw material cost of ceramic green bodies.

[0025] Specifically, this solution can achieve the recycling of the following types of waste materials:

[0026] The first category is ball-washing slurry containing degumming agents, including glaze slurry and raw material ball-washing slurry. This type of slurry generally contains degumming agents such as sodium tripolyphosphate and water glass. In the field of architectural ceramics, degumming agents are crucial additives in the preparation of ceramic raw materials (especially slurry preparation). Their core function is to improve the fluidity and stability of ceramic raw material slurries, ensuring the smooth progress of subsequent molding, glazing, and other processes.

[0027] The second category is polishing waste, which is mainly a suspension slurry composed of fine particles, water, and a small amount of additives generated during ceramic polishing. The particle surface may adsorb water or a small amount of residual polishing liquid components, forming an unstable colloidal structure. This type of waste has a characteristic of changing its fluidity with shear force: when subjected to external shear force (such as stirring, vibration, pumping, etc.), the viscosity of the slurry will decrease and the fluidity will improve; when the shear force stops, the viscosity will gradually recover, or even become more viscous. This reversible change phenomenon of "shear thinning and standing thickening" is called thixotropy.

[0028] The third category is raw waste powder, including tail powder generated by the bag filter dust collector of the spray tower, powder leakage from the spray tower, the feeding process and the press, and waste green blanks after pressing. The fineness of this type of waste material is generally <250 mesh, which meets the production requirements and generally does not require additional treatment.

[0029] The fourth category is hard clinker, which includes edge-grinding slag, waste brick blanks and their crushed materials generated during the ceramic polishing process, as well as coal slag, aluminum slag, and other materials commonly found in other industries. This type of waste has a low moisture content, generally <5wt%, and has been fired at high temperatures, thus belonging to clinker. Adding it to the raw materials of ceramic blanks can effectively reduce the firing temperature of the blanks and save energy.

[0030] The recycling process in this plan specifically includes the following steps:

[0031] First, the ball-washing slurry containing the degumming agent is allowed to settle, resulting in sediment. Since the degumming agent is generally water-soluble, the sediment usually also contains it. Then, this sediment is mixed with polishing waste, which has thixotropic properties. The degumming agent can disperse particles and disrupt the network structure, weakening the thixotropic effect of the polishing waste, improving the fluidity and stability of the slurry, facilitating transportation, mixing, or subsequent processing, and increasing processing efficiency. This has practical significance for the recycling and environmental treatment of polishing waste. Furthermore, raw waste with a fineness meeting production requirements only needs to be slurried by adding water. The water used for slurrying can come from filter presses, rainwater, etc., further realizing the greening of the milling process. Next, since hard clinker with a moisture content of <5wt% is difficult to grind, it can be dry-ground separately (e.g., using a vertical dry grinder) before ball milling with other raw materials in the green body formulation (such as clay, feldspar, quartz, and other conventional raw materials in the green body formulation). This effectively avoids the accumulation of some hard clinker that cannot be ground finely in one go and remains inside the ball mill, causing problems such as green body formulation errors and low ball milling efficiency. Finally, the slurry obtained after the above waste material treatment is fed into a large slurry for homogenization, and then spray-granulated in a spray tower to obtain ceramic powder.

[0032] Preferably, the ball milling time for the sediment and polishing waste in step B should be less than 2 hours, i.e., a short ball milling should be performed to avoid problems such as thixotropy of the slurry and excessively low firing temperature caused by excessive ball milling of the sediment and polishing waste. Specifically, the neutralized slurry can be added to the last stage of the continuous ball mill for short ball milling, or it can be added within 2 hours before the batch ball mill stops for short ball milling.

[0033] It should be noted that in step B, the amount of polishing waste residue added can be calculated based on the solid content and chemical composition of the sediment, so that the degumming agent and polishing waste residue can achieve a better neutralization effect; in step D, the raw material of the green body can be calculated based on the chemical composition of the green body formula to be produced and the amount of various waste materials added.

[0034] To further clarify, in step D, the fineness of the hard cooked powder is <100 mesh.

[0035] This is beneficial for improving the ball milling efficiency of hard cooked powder and other raw materials.

[0036] To further explain, in step B, the first slurry has a water content of 28-35 wt%, a residue of 0.5-1.5 wt% on a 250-mesh sieve, a specific gravity of 1.68-1.73, and a flow rate of 25-60 s.

[0037] To further explain, in step D, the third slurry has a water content of 28-35 wt%, a residue of 0.5-1.5 wt% on a 250-mesh sieve, a specific gravity of 1.68-1.73, and a flow rate of 25-60 s.

[0038] It should be noted that in the ceramics field, the flowability of ceramic slurry is generally measured using a flow rate cup. The time it takes for the slurry to completely flow out of the cup indicates the slurry's flowability. Specifically, before testing the flow rate, the flow rate cup must be leveled and wiped clean with a damp cloth, leaving the inner surface slightly moist. Press down on the flow rate cup's outlet with your middle finger and slowly pour the slurry into the cup until a convex surface forms. Smooth the slurry until the surface is flush with the cup's opening. Then, while releasing your middle finger, start a stopwatch and observe the slurry flow. When the slurry reaches the dripping stage, stop the stopwatch immediately. The time displayed on the stopwatch is the flow rate. Therefore, in this method, the flow rate of the first and third slurries is expressed in "s".

[0039] It should be further explained that specific gravity, also known as relative density, is a dimensionless quantity, meaning it has no unit value and generally varies with temperature and pressure. In the ceramics industry, a specific gravity cup is typically used to measure the specific gravity of the glaze slurry on glaze production lines. This device usually involves filling the specific gravity cup with glaze until a convex surface appears. The lid is then slowly closed, and excess glaze overflows from a small hole in the lid. The total weight of the specific gravity cup and the glaze slurry is measured. The weight of the glaze slurry is then subtracted from the total weight. Specific gravity = mass / volume, and thus, the specific gravity is determined.

[0040] To further clarify, in step C, the water is the supernatant from step A.

[0041] In a preferred embodiment of this technical solution, the supernatant from step A can be used to pulp the raw waste powder, which is more conducive to achieving a green and environmentally friendly powder making process.

[0042] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0043] Example

[0044] A. The ball washing mud containing the degumming agent is allowed to stand and settle to obtain the supernatant in the upper layer and the sediment in the lower layer;

[0045] The chemical composition of the sediment, calculated by mass percentage, includes SiO2 50–59%, Al2O3 16–25%, Fe2O3 0.3–0.6%, CaO 5.0–7.0%, MgO 4.0–5.0%, K2O 1.0–2.0%, Na2O 3.0–4.0%, ZnO 4.0–5.0%, and loss on ignition 1.0–2.0%.

[0046] B. The sediment from step A is extracted into a transfer tank, and the polishing waste is added into the transfer tank for mixing. After stirring and homogenization, a neutralized slurry is obtained. The neutralized slurry is then sieved to remove impurities and iron, and then ball-milled for 1 hour to obtain the first slurry.

[0047] The chemical composition of the polishing waste residue, calculated by mass percentage, includes 65-70% SiO2, 16-20% Al2O3, 0.9-1.3% Fe2O3, 2.0-2.5% CaO, 1.5-2.0% MgO, 3.0-4.0% K2O, 2.5-3.5% Na2O, and 4.0-5.0% loss on ignition. The mixing mass ratio of sediment and polishing waste residue is 1:3. The water content of the first slurry is 28-35 wt%, the residue on a 250-mesh sieve is 0.5-1.5 wt%, the specific gravity is 1.68-1.73, and the flow rate is 25-60 s.

[0048] C. Add the raw waste powder with a fineness of <250 mesh to the supernatant liquefaction slurry from step A, and obtain the second slurry after iron removal and sieving to remove impurities;

[0049] The chemical composition of the raw waste powder, calculated by mass percentage, includes 65-70% SiO2, 17-20% Al2O3, 0.6-0.9% Fe2O3, 0.7-0.9% CaO, 0.8-1.2% MgO, 1.5-4.0% K2O, 2.0-2.5% Na2O, and 4.0-7.0% loss on ignition.

[0050] D. Hard clinker (composed of ceramic waste bricks and coal slag) with a water content of <5wt% is dry-milled to obtain hard clinker powder with a fineness of <100 mesh. The raw material of the green body is prepared according to the raw material formula of the low water absorption ceramic green body. The hard clinker powder and the green body raw material are mixed and added to the ball mill to obtain the third slurry.

[0051] The mixing ratio of ceramic waste bricks and coal slag in the hard clinker is 9:1. The chemical composition of the ceramic waste bricks, calculated by mass percentage, includes SiO2 65–70%, Al2O3 17–20%, Fe2O3 0.6–0.9%, CaO 0.7–0.9%, MgO 0.8–1.2%, K2O 3.0–4.0%, Na2O 2.0–2.5%, and loss on ignition 4.0–7.0%. The chemical composition of the coal slag, calculated by mass percentage, includes SiO2 45–50%, Al2O3 36–40%, Fe2O3 5.0–5.5%, CaO 4.5–5.0%, MgO 0.8–1.0%, TiO2 1.0–1.5%, K2O 0.5–1.5%, and Na2O. The content of the third slurry is 1.0-1.3% and the loss on ignition is 1.0-2.0%; the water content of the third slurry is 28-35 wt%, the residue on a 250-mesh sieve is 0.5-1.5 wt%, the specific gravity is 1.68-1.73, and the flow rate is 25-60 s.

[0052] E. The first slurry from step B, the second slurry from step C, and the third slurry from step D are mixed in a mass ratio of 1:1:8 and added to a large slurry tank for homogenization to obtain a green body slurry. The green body slurry is then sprayed into a spray tower for wet powdering to obtain ceramic powder.

[0053] The ceramic powder obtained in the above embodiments is pressed and dried to obtain a green body, which is then fired in a kiln to obtain a green body. After conventional testing in the ceramics field, the surface of the green body is smooth and free of bubbles, and the core of the green body does not show any blackening. It can be fully fired at a firing temperature of 1225℃, and the resulting green body has a water absorption rate of 0.05% and a modulus of rupture of 42MPa, which meets the production standards for low water absorption bricks.

[0054] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A wet powder-making process for ceramic green bodies using recycled waste materials, characterized in that, Includes the following steps: A. The ball washing mud containing the degumming agent is allowed to stand and settle to obtain the supernatant in the upper layer and the sediment in the lower layer; B. The sediment from step A is extracted into a transfer tank, and the polishing waste is added into the transfer tank for mixing, stirring and homogenization to obtain a neutralized slurry; the neutralized slurry is then sieved to remove impurities and iron, and then ball-milled to obtain the first slurry; wherein the ball milling time is less than 2 hours; C. Add water to the raw waste powder with a fineness of <250 mesh to make slurry, and obtain the second slurry after iron removal and sieving to remove impurities; D. Hard clinker with a moisture content of <5wt% is dry-milled to obtain hard clinker powder. The raw materials for the ceramic body are prepared according to the raw material formula of the ceramic body to be produced. The hard clinker powder and the raw materials for the body are mixed and then added to a ball mill to obtain the third slurry. E. The first slurry from step B, the second slurry from step C, and the third slurry from step D are fed into a large slurry tank for homogenization to obtain a green body slurry. The green body slurry is then sprayed into a spray tower for wet powdering to obtain ceramic powder.

2. The wet powder production process for ceramic green bodies using recycled waste materials according to claim 1, characterized in that, In step D, the fineness of the hard cooked powder is <100 mesh.

3. The wet powder production process for ceramic green bodies using recycled waste materials according to claim 1, characterized in that, In step B, the first slurry has a water content of 28-35 wt%, a residue of 0.5-1.5 wt% on a 250-mesh sieve, a specific gravity of 1.68-1.73, and a flow rate of 25-60 s.

4. The wet powder production process for ceramic green bodies using recycled waste materials according to claim 1, characterized in that, In step D, the third slurry has a water content of 28-35 wt%, a residue of 0.5-1.5 wt% on a 250-mesh sieve, a specific gravity of 1.68-1.73, and a flow rate of 25-60 s.

5. The wet powder-making process for ceramic green bodies using recycled waste materials according to claim 1, characterized in that, In step C, the water is the supernatant from step A.