Method for preparing graphite tailing-based tubular ceramic membrane

Abstract

The invention relates to the technical field of inorganic ceramic membrane materials, and discloses a method for preparing a graphite tailing-based tubular ceramic membrane, which realizes low preparation cost of the ceramic membrane by adopting a waste utilization mode: the solid waste utilization rate is greater than or equal to 50%, the raw material cost is reduced by more than 40%, and the production cost is reduced by more than 40% by changing the production process. The bending strength of the support is greater than or equal to 35MPa, and the thermal expansion coefficient is less than or equal to 4.5 * 10 <-6 > / DEG C; the aperture of the membrane layer is 0.1-0.3 mu m, and the pure water flux is greater than or equal to 800L / (m < 2 >. H. Bar

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic ceramic membrane materials, and particularly relates to a method for preparing a tubular ceramic membrane using graphite tailings as a main raw material. Background Art

[0002] As a high-performance separation material, ceramic membranes have been widely used in water treatment, gas separation, biomedicine, and other fields due to their unique physical and chemical properties. However, in practical application, ceramic membranes also face significant technical bottlenecks and economic challenges. Existing ceramic membrane raw materials rely on high-purity minerals, which are expensive and have insufficient solid waste utilization. Traditional ceramic membrane supports are brittle and have high thermal expansion coefficients, which lead to membrane cracking and shedding. Furthermore, the membranes in emulsified oil wastewater treatment face technical bottlenecks such as rapid flux decay and short service life. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing a graphite tailings-based tubular ceramic membrane, with a solid waste utilization rate of ≥50%, a raw material cost reduction of more than 40% and low cost; the support body has a flexural strength of ≥35 MPa and a thermal expansion coefficient of ≤4.5×10 -6 / ℃ achieves good performance.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a graphite tailings tubular ceramic membrane based on solid waste utilization, comprising the following steps:

[0005] A. Support preparation:

[0006] (1) Raw material ratio (weight parts): 40-50 parts of graphite tailings, 10-15 parts of fly ash, 15-20 parts of potassium feldspar, 8-12 parts of talc (the total proportion of solid waste is ≥50%); pore-forming agent: calcium carbonate and soluble starch mixed in a ratio of 3:1, added in an amount of 5-8 parts; binder: polyvinyl alcohol solution (concentration 8-10wt%), added in an amount of 10-15 parts;

[0007] (2) ball-milling the raw materials to a particle size of ≤50 μm, adding water and mixing until the moisture content reaches 18-22%;

[0008] (3) using a screw extruder to form a tubular blank (inner diameter 8-12 mm, wall thickness 2-3 mm);

[0009] (4) The green body is aged for 24-36 hours at a humidity of 80% and a temperature of 25°C; stepwise sintering:

[0010] (5) Raise the temperature to 600°C at 3°C / min and keep it at that temperature for 1 hour (to discharge organic matter), then raise the temperature to 1150-1200°C at 2°C / min and keep it at that temperature for 2 hours, and then cool it down with the furnace;

[0011] B. Film preparation:

[0012] (1) 30-35 parts of graphite tailings powder (D50 = 2-5 μm), binder: polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) in a ratio of 4:1, with a total concentration of 6-8 wt%, dispersant: polyacrylic acid (PAA) 0.5-1 part, and deionized water as the balance;

[0013] (2) Stir the coating solution in a 60-70°C water bath for 2-3 hours, and control the viscosity at 200-300 mPa·s;

[0014] (3) Forming a 20-50 μm film layer on the outer surface of the support body by using an immersion pulling method (pulling speed 2-4 mm / s) or a spraying method (pressure 0.3-0.5 MPa);

[0015] (4) Secondary sintering: Raise the temperature to 1000-1050°C at 1.5°C / min and keep at this temperature for 1.5h.

[0016] The present invention is further configured as follows: the base material solid waste in step A accounts for ≥50wt% and the sintering temperature is 1150-1200°C.

[0017] The present invention is further configured as follows: the mass ratio of calcium carbonate to soluble starch in the composite pore-forming agent is 3:1.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] Low cost: solid waste utilization rate ≥50%, raw material cost reduced by more than 40%;

[0020] High performance: support body bending strength ≥35MPa, thermal expansion coefficient ≤4.5×10 -6 / ℃; membrane pore size 0.1-0.3μm, pure water flux ≥800L / (m 2 ·h·bar). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The effects of different sintering temperatures and aluminum-silicon ratios on the shrinkage of ceramic membranes;

[0022] Figure 2 The effect of different sintering temperatures and aluminum-silicon ratios on the shrinkage of the support and ceramic membrane. DETAILED DESCRIPTION

[0023] The present invention will be described in more detail below by way of examples. These examples are merely illustrative and do not limit the scope of the present invention in any way.

[0024] The present invention provides a technical solution: a method for preparing a graphite tailings-based tubular ceramic membrane, comprising the following steps:

[0025] A. Support preparation:

[0026] (1) Raw material ratio (weight parts): 40-50 parts of graphite tailings, 10-15 parts of fly ash, 15-20 parts of potassium feldspar, 8-12 parts of talc (the total proportion of solid waste is ≥50%); pore-forming agent: calcium carbonate and soluble starch mixed in a ratio of 3:1, added in an amount of 5-8 parts; binder: polyvinyl alcohol solution (concentration 8-10wt%), added in an amount of 10-15 parts;

[0027] (2) ball-milling the raw materials to a particle size of ≤50 μm, adding water and mixing until the moisture content reaches 18-22%;

[0028] (3) using a screw extruder to form a tubular blank (inner diameter 8-12 mm, wall thickness 2-3 mm);

[0029] (4) The green body is aged for 24-36 hours at a humidity of 80% and a temperature of 25°C; stepwise sintering:

[0030] (5) Raise the temperature to 600°C at 3°C / min and keep it at that temperature for 1 hour (to discharge organic matter), then raise the temperature to 1150-1200°C at 2°C / min and keep it at that temperature for 2 hours, and then cool it down with the furnace;

[0031] B. Film preparation:

[0032] (1) 30-35 parts of graphite tailings powder (D50 = 2-5 μm), binder: polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) in a ratio of 4:1, with a total concentration of 6-8 wt%, dispersant: polyacrylic acid (PAA) 0.5-1 part, and deionized water as the balance;

[0033] (2) Stir the coating solution in a 60-70°C water bath for 2-3 hours, and control the viscosity at 200-300 mPa·s;

[0034] (3) Forming a 20-50 μm film layer on the outer surface of the support body by using an immersion pulling method (pulling speed 2-4 mm / s) or a spraying method (pressure 0.3-0.5 MPa);

[0035] (4) Secondary sintering: Raise the temperature to 1000-1050°C at 1.5°C / min and keep at this temperature for 1.5h.

[0036] The present invention is further configured as follows: the base material solid waste in step A accounts for ≥50wt% and the sintering temperature is 1150-1200°C.

[0037] The present invention is further configured as follows: the mass ratio of calcium carbonate to soluble starch in the composite pore-forming agent is 3:1.

[0038] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a graphite tailings-based tubular ceramic membrane, characterized in that: The following steps are involved: A. Support preparation: (1) Raw material ratio (weight parts): 40-50 parts of graphite tailings, 10-15 parts of fly ash, 15-20 parts of potassium feldspar, 8-12 parts of talc (the total proportion of solid waste is ≥50%); pore-forming agent: calcium carbonate and soluble starch mixed in a ratio of 3:1, added in an amount of 5-8 parts; binder: polyvinyl alcohol solution (concentration 8-10wt%), added in an amount of 10-15 parts; (2) ball-milling the raw materials to a particle size of ≤50 μm, adding water and mixing until the moisture content reaches 18-22%; (3) using a screw extruder to form a tubular blank (inner diameter 8-12 mm, wall thickness 2-3 mm); (4) The green body is aged for 24-36 hours at a humidity of 80% and a temperature of 25°C; stepwise sintering: (5) Raise the temperature to 600°C at 3°C / min and keep it at that temperature for 1 hour (to discharge organic matter), then raise the temperature to 1150-1200°C at 2°C / min and keep it at that temperature for 2 hours, and then cool it down with the furnace; B. Film preparation: (1) 30-35 parts of graphite tailings powder (D50 = 2-5 μm), binder: polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) in a ratio of 4:1, with a total concentration of 6-8 wt%, dispersant: polyacrylic acid (PAA) 0.5-1 part, and deionized water as the balance; (2) Stir the coating solution in a 60-70°C water bath for 2-3 hours, and control the viscosity at 200-300 mPa·s; (3) Forming a 20-50 μm film layer on the outer surface of the support body by using an immersion pulling method (pulling speed 2-4 mm / s) or a spraying method (pressure 0.3-0.5 MPa); (4) Secondary sintering: Raise the temperature to 1000-1050°C at 1.5°C / min and keep at this temperature for 1.5h.

2. The method for preparing a graphite tailings-based tubular ceramic membrane according to claim 1, wherein: The base material solid waste in step A accounts for ≥50wt%, and the sintering temperature is 1150-1200°C.

3. A method for preparing a graphite tailings-based tubular ceramic membrane according to claim 1, characterized in that: The mass ratio of calcium carbonate to soluble starch in the composite pore-forming agent is 3:1.

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