Method for recycling and regenerating a waste ceramic gypsum mold by compostable degradation

Abstract

The application provides a treatment method for recycling and regenerating compostable and degradable waste ceramic gypsum molds, which comprises the following steps: first, pressurized gypsum mortar is sprayed on the surface of the waste ceramic gypsum mold for cleaning; second, the cleaned waste ceramic gypsum mold is crushed, acetic acid is added for pickling, and the waste ceramic gypsum mold is dried and then sieved through a 200-300 mesh sieve to obtain solid powder; third, the obtained solid powder is poured into cold water, sulphoaluminate cement and wood ash are added, and the mixture is fully stirred at low temperature for 25-35 minutes; fourth, a glue adhesive is added and stirred for 5-10 minutes to obtain a mixture; fifth, the obtained mixture is added into an extruder for extrusion granulation, and then dried and sieved to obtain granular materials with a particle size of 0.5-1 cm; and finally, the obtained granular materials are scattered into soil to be planted, and microbial agents and urea are added for composting fermentation treatment. The treatment method can realize composting degradation of the waste ceramic gypsum mold, and provides nutrients for the soil.

Description

Technical Field

[0001] This invention relates to the field of gypsum degradation technology, and more specifically, to a method for recycling and regenerating waste ceramic gypsum molds into compostable and biodegradable materials. Background Technology

[0002] Plaster molds are a traditional material used in the ceramics industry for a long time. Their main component is dihydrate gypsum, which is generally processed to a high purity with a free water content of around 5%. It contains a certain amount of sodium sulfate impurities and anhydrous gypsum, and has a porous, network-like internal structure, resulting in low strength and poor water and corrosion resistance. However, ceramics production generates a large amount of waste gypsum that cannot be reused, and a large number of plaster molds are discarded every year. These molds are not utilized effectively, with very little use in the cement industry. Therefore, how to dispose of these waste ceramic plaster molds is one of the urgent problems that needs to be solved. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for recycling and regenerating waste ceramic plaster molds that can be composted and degraded. The waste ceramic plaster molds are utilized and degraded during the composting process, and the soil can be improved, thereby overcoming the defects in the prior art.

[0004] To achieve the above objectives, the present invention provides a method for recycling and regenerating waste ceramic plaster molds into compostable and biodegradable materials, the method comprising the following steps:

[0005] Step 1): Apply pressure and spray plaster mortar onto the surface of the waste ceramic plaster mold for cleaning;

[0006] Step 2): Crush the cleaned waste ceramic plaster mold, add acetic acid for acid washing, and after drying, pass it through a 200-300 mesh sieve to obtain solid powder;

[0007] Step 3): Pour the solid powder obtained in Step 2) into cold water, add sulfoaluminate cement and wood ash, stir thoroughly at low temperature for 25-35 minutes, and finally add adhesive and stir for 5-10 minutes to obtain a mixture.

[0008] Step 4): Add the mixture obtained in step 3) to an extruder for extrusion granulation, and then dry and screen it to obtain granules with a particle size of 0.5-1cm;

[0009] Step 5): Spread the granules obtained in step 4) into the soil to be planted, and add microbial agents and urea for composting and fermentation.

[0010] As a further explanation of the processing method of the present invention, preferably, in step 1), the gypsum mortar is made by mixing pure gypsum powder and pure water, and the concentration of the gypsum mortar is 55%-65%.

[0011] As a further explanation of the processing method of the present invention, preferably, in step 3), the mixture includes 50-80 parts by weight of gypsum powder, 25-40 parts by weight of cold water, 10-15 parts by weight of sulfoaluminate cement, 7-10 parts by weight of wood ash, and 2-3 parts by weight of adhesive.

[0012] As a further explanation of the processing method of the present invention, preferably, in step 3), the adhesive is selected from one or more of chitosan, sodium alginate, sodium carboxymethyl cellulose, and polyacrylate.

[0013] As a further explanation of the processing method described in this invention, preferably, in step 3), the low temperature is 10-15°C.

[0014] As a further explanation of the processing method of the present invention, preferably, in step 5), the amount of microbial agent added is 5-8 parts by weight, and the amount of urea added is 15-25 parts by weight.

[0015] As a further explanation of the processing method of the present invention, preferably, in step 5), the microbial agent is selected from one or more of Bacillus subtilis, Bacillus mucilaginosus, and Bacillus megaterium.

[0016] As a further explanation of the processing method described in this invention, preferably, in step 5), the temperature of the composting fermentation is 20-30°C.

[0017] As a further explanation of the processing method described in this invention, preferably, the mass concentration of the acetic acid is 10%-20%.

[0018] The beneficial effects of this invention are:

[0019] This invention discloses a method for recycling and regenerating waste ceramic gypsum molds into compostable and biodegradable products. First, the surface layer of the waste ceramic gypsum molds is peeled off using pressurized sprayed gypsum mortar to remove impurities. Then, the waste ceramic gypsum molds are crushed and acid-washed with acetic acid to remove heavy metals. Since the main component of gypsum is calcium sulfate, calcium acetate is obtained after acid washing and screened to obtain solid powder. Next, the solid powder is modified using sulfoaluminate cement, wood ash, and an adhesive. During mixing, the solid powder is uniformly mixed with sulfoaluminate cement and wood ash. The wood ash neutralizes acidic and harmful substances in the solid powder, reducing its harmfulness. The adhesive coats the uniformly mixed solid powder, sulfoaluminate cement, and wood ash to prevent moisture absorption. The sulfoaluminate cement increases the hardness of the granulated material, preventing it from failing to form properly. Finally, the granules are composted in soil with microbial agents and urea. The adhesive used is biodegradable chitosan, sodium alginate, sodium carboxymethyl cellulose, and polyacrylate. The outer adhesive is first degraded in the soil. Since the main component of wood ash is potassium carbonate, it can attract microorganisms, improving the degradation efficiency of the granular material. Then, the solid powder, sulfoaluminate cement, and wood ash gradually degrade. The calcium ions in the calcium acetate of the acidified solid powder more easily replace sodium ions in the soil, accelerating the degradation rate of the granular material and regulating the soil's pH. Sulfoaluminate cement can adsorb heavy metal ions in the soil, and during composting fermentation, wood ash provides potassium, and urea provides nitrogen, providing nutrients to the soil. Detailed Implementation

[0020] To further understand the structure, features, and other objectives of the present invention, a detailed description is provided below with reference to the accompanying drawings. The embodiments illustrated in these drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] Preparation of experimental materials:

[0022] Waste ceramic plaster molds can be collected from various ceramic factories.

[0023] The sulfoaluminate cement was purchased from Zhengzhou Jianwen Special Materials Technology Co., Ltd.

[0024] The wood ash was purchased from Tianjin Xinying Technology Co., Ltd.

[0025] Adhesives: Chitosan and sodium carboxymethyl cellulose were purchased from Shaanxi Runfeng Biotechnology Co., Ltd., sodium alginate was purchased from Hebei Lihua Biotechnology Co., Ltd., and polyacrylate was purchased from Shandong Jinan Huifengda Chemical Co., Ltd.

[0026] Microbial agents: Bacillus subtilis (CAS No. 68038-70-0, viable count 100 billion / g), Bacillus megaterium (CAS No. 219944-46-4, effective viable count ≥10 billion / g), and Bacillus mucilaginosus (effective viable count ≥5 billion / g) were purchased from Shandong Ruichen Biotechnology Co., Ltd.

[0027] Urea was purchased from Hubei Shiteng Chemical Technology Co., Ltd.

[0028] Example 1: A method for recycling and composting waste ceramic plaster molds

[0029] Cleaning: Plaster mortar is sprayed under pressure onto the surface of the waste ceramic plaster mold for cleaning. The plaster mortar is made of pure plaster powder and pure water, with a concentration of 55%. The pressure is set at 120MPa during the pressurized spraying process to peel off the surface layer of the waste ceramic plaster mold and remove impurities from the surface of the plaster mold.

[0030] Crushing and pickling: The cleaned waste ceramic plaster molds are crushed, pickled with acetic acid, and dried before being passed through a 200-mesh sieve to obtain solid powder. Pickling with 10% acetic acid can remove heavy metals from the plaster. Since the main component of plaster is calcium sulfate, calcium acetate is obtained after pickling, which is more easily degraded by composting in soil.

[0031] Pretreatment: Take 5 kg of the solid powder obtained in the crushing step, pour it into 2.5 kg of cold water, add 1 kg of sulfoaluminate cement and 0.7 kg of wood ash, and stir thoroughly at 10℃ for 25 minutes. Finally, add 0.2 kg of chitosan and stir for 5 minutes to obtain a mixture. During the stirring process, the solid powder, sulfoaluminate cement, and wood ash are uniformly mixed. The wood ash is used to neutralize the acidic and harmful substances in the solid powder, reducing its harmfulness. The adhesive is used to coat the uniformly mixed solid powder, sulfoaluminate cement, and wood ash to prevent the granules from getting damp. The sulfoaluminate cement is used to increase the hardness of the granules obtained after granulation, preventing the granules from not forming properly.

[0032] Granulation: The mixture obtained in the pretreatment step is added to an extruder for extrusion granulation, followed by drying and screening to obtain granules with a particle size of 0.5 cm. Granules facilitate observation of their degradation degree in the soil.

[0033] Composting Fermentation: The granules obtained in the granulation step are spread into the soil to be planted, along with 0.5 kg of microbial inoculant and 1.5 kg of urea. Composting fermentation is carried out at 20°C. The microbial inoculant consists of Bacillus subtilis, Bacillus mucilage, and Bacillus megaterium in a 1:1:1 mass ratio. The chitosan coating is first degraded in the soil. Since the main component of wood ash is potassium carbonate, it can attract microorganisms, improving the degradation efficiency of the granules. Then, the solid powder, sulfoaluminate cement, and wood ash gradually degrade. The calcium ions in the calcium acetate of the acidified solid powder more easily replace sodium ions in the soil, accelerating the degradation rate of the granules and regulating the soil pH. Sulfoaluminate cement can adsorb heavy metal ions in the soil. During composting fermentation, wood ash provides potassium, and urea provides nitrogen, providing nutrients to the soil.

[0034] Example 2: A method for recycling and composting waste ceramic plaster molds

[0035] Cleaning: Plaster mortar is sprayed under pressure onto the surface of the waste ceramic plaster mold for cleaning. The plaster mortar is made of pure plaster powder and pure water, with a concentration of 60%. The pressure is set at 120MPa during the pressurized spraying process to peel off the surface layer of the waste ceramic plaster mold and remove impurities from the surface of the plaster mold.

[0036] Crushing and pickling: The cleaned waste ceramic plaster molds are crushed, pickled with acetic acid, and dried before being passed through a 250-mesh sieve to obtain solid powder. Pickling with 15% acetic acid can remove heavy metals from the plaster. Since the main component of plaster is calcium sulfate, calcium acetate is obtained after pickling, which is more easily degraded by composting in soil.

[0037] Pretreatment: Take 6 kg of the solid powder obtained in the crushing step, pour it into 3 kg of cold water, add 1.2 kg of sulfoaluminate cement and 0.9 kg of wood ash, and stir thoroughly at 12℃ for 30 minutes. Finally, add 0.25 kg of chitosan and stir for 8 minutes to obtain a mixture. During the stirring process, the solid powder, sulfoaluminate cement, and wood ash are uniformly mixed. The wood ash is used to neutralize the acidic and harmful substances in the solid powder, reducing its harmfulness. The adhesive is used to coat the uniformly mixed solid powder, sulfoaluminate cement, and wood ash to prevent the granules from getting damp. The sulfoaluminate cement is used to increase the hardness of the granules obtained after granulation, preventing the granules from not forming properly.

[0038] Granulation: The mixture obtained in the pretreatment step is added to an extruder for extrusion granulation, followed by drying and screening to obtain granules with a particle size of 0.8 cm. Granules facilitate observation of their degradation degree in the soil.

[0039] Composting Fermentation: The granules obtained in the pelleting step are spread into the soil to be planted, along with 0.7 kg of microbial inoculant and 2 kg of urea. Composting fermentation is carried out at 25°C. The microbial inoculant consists of Bacillus subtilis, Bacillus mucilaginosus, and Bacillus megaterium in a 1:1:1 mass ratio. The chitosan coating is first degraded in the soil. Since the main component of wood ash is potassium carbonate, it can attract microorganisms, improving the degradation efficiency of the granules. Then, the solid powder, sulfoaluminate cement, and wood ash gradually degrade. The calcium ions in the calcium acetate of the acidified solid powder more easily replace sodium ions in the soil, accelerating the degradation rate of the granules and regulating the soil pH. Sulfoaluminate cement can adsorb heavy metal ions in the soil. During composting fermentation, wood ash provides potassium, and urea provides nitrogen, providing nutrients to the soil.

[0040] Example 3: A method for recycling and composting waste ceramic plaster molds

[0041] Cleaning: Plaster mortar is sprayed under pressure onto the surface of the waste ceramic plaster mold for cleaning. The plaster mortar is made of pure plaster powder and pure water, with a concentration of 65%. The pressure is set at 120MPa during the pressurized spraying process to peel off the surface layer of the waste ceramic plaster mold and remove impurities from the surface of the plaster mold.

[0042] Crushing and pickling: The cleaned waste ceramic plaster molds are crushed, pickled with acetic acid, and dried before being sieved through a 300-mesh sieve to obtain solid powder. Pickling with 20% acetic acid can remove heavy metals from the plaster. Since the main component of plaster is calcium sulfate, calcium acetate is obtained after pickling, which is more easily degraded by composting in soil.

[0043] Pretreatment: Take 8 kg of the solid powder obtained in the crushing step, pour it into 4 kg of cold water, add 1.5 kg of sulfoaluminate cement and 1 kg of wood ash, and stir thoroughly at 10-15℃ for 35 minutes. Finally, add 0.3 kg of chitosan and stir for 10 minutes to obtain a mixture. During the stirring process, the solid powder, sulfoaluminate cement, and wood ash are evenly mixed. The wood ash is used to neutralize the acidic and harmful substances in the solid powder, reducing its harmfulness. The adhesive is used to coat the evenly mixed solid powder, sulfoaluminate cement, and wood ash to prevent the granules from getting damp. The sulfoaluminate cement is used to increase the hardness of the granules obtained after granulation, preventing the granules from not forming properly.

[0044] Granulation: The mixture obtained in the pretreatment step is added to an extruder for granulation, followed by drying and screening to obtain granules with a particle size of 1 cm. Granules facilitate observation of their degradation degree in the soil.

[0045] Composting Fermentation: The granules obtained in the pelleting step are spread into the soil to be planted, along with 0.8 kg of microbial inoculant and 2.5 kg of urea. Composting fermentation is carried out at 30°C. The microbial inoculant consists of Bacillus subtilis, Bacillus mucilaginosus, and Bacillus megaterium in a 1:1:1 mass ratio. The chitosan coating is first degraded in the soil. Since the main component of wood ash is potassium carbonate, it can attract microorganisms, improving the degradation efficiency of the granules. Then, the solid powder, sulfoaluminate cement, and wood ash gradually degrade. The calcium ions in the calcium acetate of the acidified solid gypsum powder more easily replace sodium ions in the soil, accelerating the degradation rate of the granules and regulating the soil pH. Sulfoaluminate cement can adsorb heavy metal ions in the soil. During composting fermentation, wood ash provides potassium, and urea provides nitrogen, providing nutrients to the soil.

[0046] Example 4:

[0047] This embodiment 4 follows the processing method of embodiment 2, except that the adhesive used is sodium alginate. See Table 1.

[0048] Example 5:

[0049] This embodiment 5 follows the processing method of embodiment 2, except that the adhesive used is sodium carboxymethyl cellulose. See Table 1.

[0050] Example 6:

[0051] This embodiment 6 follows the processing method of embodiment 2, except that the adhesive used is polyacrylate. See Table 1.

[0052] Example 7:

[0053] This embodiment 7 follows the processing method of embodiment 2, except that the microbial agent is Bacillus subtilis and Bacillus mucilage in a 1:1 mass ratio. See Table 1.

[0054] Example 8:

[0055] This embodiment 8 follows the processing method of embodiment 2, except that the microbial agent used is Bacillus subtilis and Bacillus megaterium in a 1:1 mass ratio. See Table 1.

[0056] Example 9:

[0057] This embodiment 9 follows the processing method of embodiment 2, except that the microbial agent is a mixture of Bacillus mucilaginosus and Bacillus megaterium in a 1:1 mass ratio. See Table 1.

[0058] Comparative Example 1:

[0059] This comparative example 1 follows the processing method of example 2, except that wood ash is not added in the pretreatment step. See Table 1.

[0060] Comparative Example 2:

[0061] This comparative example 2 follows the processing method of example 2, except that acetic acid is not added during the crushing and acid washing step. Therefore, the main component of the obtained solid powder is calcium sulfate. See Table 1.

[0062] Comparative Example 3:

[0063] This comparative example 3 follows the processing method of example 2, except that acetic acid is not added during the crushing and acid washing step. Therefore, the main component of the obtained solid powder is calcium sulfate, and wood ash is not added during the pretreatment step. See Table 1.

[0064] Table 1

[0065]

[0066]

[0067]

[0068] Performance testing experiments:

[0069] In a certain area of ​​Fujian, a 50-square-meter greenhouse experimental field was selected. According to Examples 1-9 and Comparative Examples 1-3, 5 catties of granular material and corresponding weights of urea and microbial agents were prepared. The temperature inside the greenhouse was controlled at 20-30℃. The materials were sown during the land preparation and ridging process.

[0070] During the experiment, the 50-square-meter greenhouse experimental field was divided into several equal areas. Then, the granular material and the corresponding weight of urea and microbial agents were evenly distributed according to the area, and materials of different embodiments were sown in different areas.

[0071] After the material is spread, the soil is turned over regularly, and the size of the particles in the soil is observed on days 15, 30, 45, and 60. The degree of degradation is judged based on the volume. See Table 2.

[0072] Table 2

[0073]

[0074]

[0075] Based on the degradation data of Examples 1-9 in Table 2, it can be seen that the waste ceramic gypsum mold recycling and regeneration composting degradation treatment method of the present invention allows the granular material to degrade in the soil, and the degradation rate can reach more than 80% on the 60th day. Therefore, it can achieve the technical effect of recycling, composting, degrading and reusing waste ceramic gypsum molds.

[0076] Based on the degradation data of Comparative Example 1 in Table 2, it can be seen that the granules can degrade in the soil even without the addition of wood ash in the pretreatment step. However, the degradation rate without wood ash is significantly lower than that with the addition of wood ash in the pretreatment step. Since the main component of wood ash is potassium carbonate, which can attract microorganisms, the microorganisms are dispersed in the soil without wood ash, resulting in fewer microorganisms clustered around the granules and a slower degradation efficiency. Therefore, the addition of wood ash can improve the degradation efficiency of the granules.

[0077] Based on the degradation data of Comparative Example 2 in Table 2, it can be seen that the gypsum granules can also degrade in the soil without acid washing. However, the ability of calcium ions in unwashed calcium sulfate to replace sodium ions in the soil is significantly less than that of calcium ions in acidified calcium acetate. Therefore, the technical effect of making it easier for calcium ions in the acidified solid powder of calcium acetate to replace sodium ions in the soil can be achieved.

[0078] Based on the degradation data of Comparative Example 3 in Table 2, it can be seen that when the gypsum is not acid-washed and no wood ash is added, the degradation degree of the granular material in the soil will be lower.

[0079] In addition, the concentrations of nitrogen, phosphorus, and potassium in the soil were tested on days 15, 30, 45, and 60 according to the international standard NY / T 2017-2011, "Determination of Nitrogen, Phosphorus, and Potassium in Plants". The average increase in nitrogen, phosphorus, and potassium content is recorded in Table 3.

[0080] Table 3

[0081] Average increase % nitrogen concentration Phosphorus concentration potassium concentration Example 1 65％ 6.75％ 36.73％ Example 2 71.43％ 8.51％ 40.38％ Example 3 67.44％ 7.14％ 38.21％ Example 4 69.37％ 7.94％ 39.54％ Example 5 68.88％ 8.35％ 40.15％ Example 6 68.24％ 7.86％ 38.97％ Example 7 68.75％ 6.97％ 38.12％ Example 8 67.89％ 8.09％ 38.46％ Example 9 68.62％ 7.48％ 38.87％

[0082] As can be seen from Table 3, the waste ceramic gypsum mold recycling and composting treatment method of this invention increases the nitrogen, phosphorus and potassium content in the soil during the gradual degradation of gypsum powder, sulfoaluminate cement and wood ash. Therefore, it can provide nutrients to the soil and prevent nutrient loss.

[0083] This invention discloses a method for recycling and regenerating waste ceramic gypsum molds into compostable and biodegradable products. First, the surface layer of the waste ceramic gypsum molds is peeled off using pressurized sprayed gypsum mortar to remove impurities. Then, the waste ceramic gypsum molds are crushed and acid-washed with acetic acid to remove heavy metals. Since the main component of gypsum is calcium sulfate, calcium acetate is obtained after acid washing and screened to obtain solid powder. Next, the solid powder is modified using sulfoaluminate cement, wood ash, and an adhesive. During mixing, the solid powder is uniformly mixed with sulfoaluminate cement and wood ash. The wood ash neutralizes acidic and harmful substances in the solid powder, reducing its harmfulness. The adhesive coats the uniformly mixed solid powder, sulfoaluminate cement, and wood ash to prevent moisture absorption. The sulfoaluminate cement increases the hardness of the granulated material, preventing it from failing to form properly. Finally, the granules are composted in soil with microbial agents and urea. The adhesive used is biodegradable chitosan, sodium alginate, sodium carboxymethyl cellulose, and polyacrylate. The outer adhesive is first degraded in the soil. Since the main component of wood ash is potassium carbonate, it can attract microorganisms, improving the degradation efficiency of the granular material. Then, the solid powder, sulfoaluminate cement, and wood ash gradually degrade. The calcium ions in the calcium acetate of the acidified solid powder more easily replace sodium ions in the soil, accelerating the degradation rate of the granular material and regulating the soil's pH. Sulfoaluminate cement can adsorb heavy metal ions in the soil, and during composting fermentation, wood ash provides potassium, and urea provides nitrogen, providing nutrients to the soil.

[0084] It should be stated that the above-described invention content and specific embodiments are intended to demonstrate the practical application of the technical solution provided by this invention and should not be construed as limiting the scope of protection of this invention. Those skilled in the art can make various modifications, equivalent substitutions, or improvements within the spirit and principles of this invention. The scope of protection of this invention is defined by the appended claims.

Claims

1. A method for recycling and regenerating waste ceramic plaster molds into compostable and biodegradable materials, characterized in that... The processing method includes the following steps: Step 1): Apply pressure and spray plaster mortar onto the surface of the waste ceramic plaster mold for cleaning; Step 2): Crush the cleaned waste ceramic plaster mold, add acetic acid for acid washing, and after drying, pass it through a 200-300 mesh sieve to obtain solid powder; Step 3): Pour the solid powder obtained in Step 2) into cold water, add sulfoaluminate cement and wood ash, stir thoroughly at low temperature for 25-35 minutes, and finally add adhesive and stir for 5-10 minutes to obtain a mixture; the adhesive is selected from one or more of chitosan, sodium alginate, sodium carboxymethyl cellulose, and polyacrylate. Step 4): Add the mixture obtained in step 3) to an extruder for extrusion granulation, and then dry and screen it to obtain granules with a particle size of 0.5-1cm; Step 5): Spread the granules obtained in step 4) into the soil to be planted, and add microbial agents and urea for composting and fermentation.

2. The processing method as described in claim 1, characterized in that, In step 1), the gypsum mortar is made by mixing pure gypsum powder and pure water, and the concentration of the gypsum mortar is 55%-65%.

3. The processing method as described in claim 1, characterized in that, In step 3), the mixture includes 50-80 parts by weight of gypsum powder, 25-40 parts by weight of cold water, 10-15 parts by weight of sulfoaluminate cement, 7-10 parts by weight of wood ash, and 2-3 parts by weight of adhesive.

4. The processing method as described in claim 1, characterized in that, In step 3), the low temperature is 10-15℃.

5. The processing method as described in claim 1, characterized in that, In step 5), the amount of microbial agent added is 5-8 parts by weight, and the amount of urea added is 15-25 parts by weight.

6. The processing method as described in claim 1, characterized in that, In step 5), the microbial agent is selected from one or more of Bacillus subtilis, Bacillus mucilaginosus, and Bacillus megaterium.

7. The processing method as described in claim 1, characterized in that, In step 5), the temperature of the composting fermentation is 20-30℃.

8. The processing method as described in claim 1, characterized in that, In step 2), the mass concentration of the acetic acid is 10%-20%.

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