Process for replacing olivine sand with sea sand as facing sand
By using sea sand instead of olivine sand in the casting process and performing high-temperature sand recovery and regeneration technology, the sand cycle deterioration and casting defects caused by high ash content of olivine sand is solved, and higher hardness, stability and economy are achieved benefit.
Patent Information
- Application Number
- CN202411497325.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-08-26
- Filing Date
- 2024-10-25
- Publication Date
- 2025-02-07
AI Technical Summary
In the casting process, the high ash content of olivine sand causes deterioration of the sand circulation, increases water glass consumption, affects the quality of the molded sand and causes casting defects such as bulges, risers and pores.
Sea sand is used instead of olivine sand. Through washing, drying, screening and high-temperature sand recovery and regeneration technologies, the ash content is controlled and the residual sodium value on the surface of the sand particles is reduced, thereby improving the sand strength and fluidity.
Sea sand shows high hardness and stability in the casting process, avoiding deterioration of sand circulation, reducing water glass consumption, improving the quality and economic benefits of the castings, and reducing pore problems on the surface and interior of the castings.
Smart Images
Figure BDA0005101599440000121
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of new materials, and in particular to a process for using sea sand instead of olivine sand as surface sand. Background Art
[0002] Olivine sand is a sand material commonly used in casting process, usually a sand containing olivine mineral. Its main component is a high proportion of olivine (epidote), which is refractory at high temperatures and has good wear resistance and heat resistance. It is suitable for metal pouring in casting. In the casting process, olivine sand is used as part of the sand mold to form the shape of metal castings. It is characterized by being able to withstand high temperatures and not easy to melt or deform, playing an important role in the casting process.
[0003] Sea sand, as the name suggests, is sand and gravel in the sea. The larger the particle size, the more common it is in centimeters; the smaller the particle size, the more common it is in millimeters; both are natural, formed by the scouring, rolling, collision and grinding of seawater.
[0004] When using olivine sand as surface sand for casting, adding more olivine sand will increase the ash content of the recycled sand after sand regeneration. The increase in ash content leads to an increase in the subsequent water glass consumption, which affects the quality of the entire molding sand. Ultimately, all of these defects are reflected on the castings, such as bulging of the casting, insufficient shrinkage compensation at the root of the riser due to bulging, and pores. Since sea sand is naturally formed silica sand, its hardness and wear resistance are better than those of machine-made olivine sand. In view of this, a process of using sea sand instead of olivine sand as surface sand is explored and studied. Summary of the invention
[0005] The present invention proposes a process for using sea sand instead of olivine sand as surface sand to solve the technical problems existing in the background technology.
[0006] To solve the above problems, the technical solution of the present invention is:
[0007] A process for using sea sand instead of olivine sand as surface sand, the casting process using sea sand as surface sand comprises the following steps:
[0008] Step 1: Collect sea sand from the beach or seabed, and go through processes such as washing, drying and screening to obtain pre-treated sea sand;
[0009] Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand;
[0010] Step 3: pouring the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment;
[0011] Step 4: After the casting is insulated, the sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to separate the ash on the surface of the sea sand from the sand particles to obtain recycled sand;
[0012] Step 5: Perform air separation on the recycled sand in step 4 to obtain regenerated sea sand;
[0013] Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
[0014] Preferably, the method for treating the pretreated sea sand in step 1 comprises the following steps:
[0015] Step 1: Wash the sea sand with fresh water for 1-2 hours;
[0016] Step 2: Dry the washed sea sand through drying equipment at a temperature of 250-300°C for 2-2.5 hours;
[0017] Step 3: Screen the dried sea sand, and the particle size of the screened sea sand is 2-5mm.
[0018] Preferably, in step three, the insulation time of the casting is 24-30 hours, and the insulation temperature is 280-320°C.
[0019] Preferably, in step 4, after the casting is kept warm, the temperature of the sea sand is 90-110°C.
[0020] Preferably, in step 4, the residual sodium value on the surface of sand particles in the recycled sand is 2.8-3.2%.
[0021] Preferably, in step five, the ash content of the regenerated sea sand after air separation is controlled at 0.4-0.6%.
[0022] Preferably, in step six, the content of water glass is 0.25-0.35%.
[0023] Preferably, in step six, the sand strength of the new sea sand is 0.6-0.8 MPa.
[0024] The above technical solution of the present invention has the following beneficial technical effects:
[0025] 1. The present invention uses sea sand instead of olivine sand as surface sand, which has strong hardness and stability advantages in the casting process. The hardness of sea sand itself is higher than that of olivine sand, and it is not easy to pulverize. It can maintain good sand grain shape and surface quality, and avoid the deterioration of sand circulation caused by pulverization. After the sea sand is sintered at high temperature, the residual sodium content on its surface will be reduced, which is beneficial to the addition amount of water glass in the subsequent secondary sand mixing, saving energy and improving economic benefits.
[0026] 2. The present invention uses sea sand instead of olivine sand as surface sand. During the high-temperature sand regeneration process, the ash content can be effectively controlled at a low level to ensure the quality and stability of the recycled sand; the sea sand helps the molding sand to reach the required strength after hardening, and reduces the porosity problem on the surface and inside of the casting through its good fluidity and filling properties; during the sintering and high-temperature sand regeneration process, the sea sand can further reduce the residual sodium value on the surface of the sand particles, which has a significant improvement effect on the subsequent sand mixing effect and helps to ensure the quality of the casting. DETAILED DESCRIPTION
[0027] The specific implementation of the present invention is further described below in conjunction with the examples. The present invention can adjust the formula appropriately according to the environmental action level and the concrete performance requirements, and operate according to the method described in the following examples to prepare a concrete composite admixture that meets the performance requirements.
[0028] Preparation Example 1 Pretreated sea sand A
[0029] A method for processing pretreated sea sand comprises the following steps:
[0030] Step 1: Wash the sea sand with fresh water for 1 hour;
[0031] Step 2: Dry the washed sea sand through drying equipment at a drying temperature of 250°C for 2 hours;
[0032] Step 3: Screen the dried sea sand, and the particle size of the screened sea sand is 5mm.
[0033] Preparation Example 2 Pretreated sea sand B
[0034] A method for processing pretreated sea sand comprises the following steps:
[0035] Step 1: Wash the sea sand with fresh water for 2.5 hours;
[0036] Step 2: Dry the washed sea sand through a drying device at a drying temperature of 275°C for 2.25 hours;
[0037] Step 3: Screen the dried sea sand, and the particle size of the screened sea sand is 3.5mm.
[0038] Preparation Example 3 Pretreated sea sand C
[0039] A method for processing pretreated sea sand comprises the following steps:
[0040] Step 1: Wash the sea sand with fresh water for 2 hours;
[0041] Step 2: Dry the washed sea sand through a drying device at a temperature of 300°C for 2.5 hours;
[0042] Step 3: Screen the dried sea sand, and the particle size of the screened sea sand is 2mm.
[0043] Example 1
[0044] A process for using sea sand instead of olivine sand as surface sand, the casting process using sea sand as surface sand comprises the following steps:
[0045] Step 1: Collect sea sand from the beach or the seabed, and obtain pre-treated sea sand A through processes such as washing, drying and screening;
[0046] Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand;
[0047] Step 3: Pour the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment. The heat preservation time of the casting is 24-30 hours and the heat preservation temperature is 280°C.
[0048] Step 4: After the casting is insulated, the temperature of the sea sand is 90°C. The sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to separate the ash on the surface of the sea sand from the sand particles to obtain recycled sand;
[0049] Step 5: The recycled sand in step 4 is subjected to air separation to obtain regenerated sea sand, wherein the ash content of the regenerated sea sand after air separation is 0.6%;
[0050] Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
[0051] In Example 1, during the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was reduced to 3.2%, and the water glass content was reduced to 0.35% during the secondary sand mixing process. The sand mold strength after the secondary sand mixing hardening was 0.6 MPa, which met the production requirements.
[0052] Example 2
[0053] A process for using sea sand instead of olivine sand as surface sand, the casting process using sea sand as surface sand comprises the following steps:
[0054] Step 1: Collect sea sand from the beach or the seabed, and obtain pre-treated sea sand B through processes such as washing, drying and screening;
[0055] Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand;
[0056] Step 3: Pour the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment. The heat preservation time of the casting is 27 hours and the heat preservation temperature is 300°C.
[0057] Step 4: After the casting is insulated, the temperature of the sea sand is 100°C. The sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to separate the ash on the surface of the sea sand from the sand particles to obtain recycled sand;
[0058] Step 5: The recycled sand in step 4 is subjected to air separation to obtain regenerated sea sand, wherein the ash content of the regenerated sea sand after air separation is 0.5%;
[0059] Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
[0060] In Example 2, during the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was reduced to 3.0%, and the water glass content was reduced to 0.30% during the secondary sand mixing process. The sand mold strength after the secondary sand mixing hardening was 0.7 MPa, which met the production requirements.
[0061] Example 3
[0062] A process for using sea sand instead of olivine sand as surface sand, the casting process using sea sand as surface sand comprises the following steps:
[0063] Step 1: Collect sea sand from the beach or the seabed, and obtain pre-treated sea sand C through processes such as washing, drying and screening;
[0064] Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand;
[0065] Step 3: Pour the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment. The heat preservation time of the casting is 30 hours and the heat preservation temperature is 320°C.
[0066] Step 4: After the casting is insulated, the temperature of the sea sand is 110°C. The sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to separate the ash on the surface of the sea sand from the sand particles to obtain recycled sand;
[0067] Step 5: The recycled sand in step 4 is subjected to air separation to obtain regenerated sea sand, wherein the ash content of the regenerated sea sand after air separation is 0.4%;
[0068] Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
[0069] In Example 3, during the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was reduced to 2.8%, and the water glass content was reduced to 0.25% during the secondary sand mixing process. The sand mold strength after the secondary sand mixing hardening was 0.8 MPa, which met the production requirements.
[0070] Comparative Example 1
[0071] A process for using sea sand instead of olivine sand as surface sand, the casting process using sea sand as surface sand comprises the following steps:
[0072] Step 1: Collect sea sand from the beach or the seabed, and obtain pre-treated sea sand B through processes such as washing, drying and screening;
[0073] Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand;
[0074] Step 3: Pour the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment. The heat preservation time of the casting is 12 hours and the heat preservation temperature is 300°C.
[0075] Step 4: After the casting is insulated, the temperature of the sea sand is 80°C. The sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to obtain recycled sand;
[0076] Step 5: The recycled sand in step 4 is subjected to air separation to obtain regenerated sea sand, wherein the ash content of the regenerated sea sand after air separation is 0.75%;
[0077] Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
[0078] In Comparative Example 1, when the sea sand was reprocessed using the high-temperature sand regeneration technology, a small amount of ash was not separated from the sand particles. During the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was 5.0%. During the secondary sand mixing process, the water glass content was reduced to 0.55%. The sand mold strength after the secondary sand mixing and hardening was above 0.6MPa, meeting the production requirements.
[0079] Comparative Example 2
[0080] A process for using sea sand instead of olivine sand as surface sand, the casting process using sea sand as surface sand comprises the following steps:
[0081] Step 1: Collect sea sand from the beach or the seabed, and obtain pre-treated sea sand B through processes such as washing, drying and screening;
[0082] Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand;
[0083] Step 3: Pour the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment. The heat preservation time of the casting is 12 hours and the heat preservation temperature is 150°C.
[0084] Step 4: After the casting is insulated, the temperature of the sea sand is 50°C. The sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to obtain recycled sand;
[0085] Step 5: The recycled sand in step 4 is subjected to air separation to obtain regenerated sea sand, wherein the ash content of the regenerated sea sand after air separation is 0.85%;
[0086] Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
[0087] In Comparative Example 2, when the sea sand was reprocessed using the high-temperature sand regeneration technology, a large amount of ash was not separated from the sand particles. During the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was 7.5%. During the secondary sand mixing process, the water glass content was slightly reduced to 0.75%. The sand mold strength after the secondary sand mixing and hardening did not meet the production requirements.
[0088] Comparative Example 3
[0089] This comparative example is basically the same as Example 2, except that the ash content of the regenerated sea sand after air separation in step 5 is 1.2%.
[0090] In Comparative Example 3, when the sea sand was reprocessed using the high-temperature sand regeneration technology, a large amount of ash was not separated from the sand particles. During the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was 8.2%. The water glass content was not reduced during the secondary sand mixing process, and the sand mold strength after the secondary sand mixing and hardening did not meet the production requirements.
[0091] Comparative Example 4
[0092] The casting process using olivine sand as surface sand includes the following steps:
[0093] Step 1: washing, drying and screening the olivine sand to obtain pre-treated sea sand olivine sand with a particle size of 4 mm;
[0094] Step 2: Stir and mix the olivine sand pretreated in step 1 with water glass to obtain mortar, add the mortar into a sand mold and compact it to obtain an olivine sand mold;
[0095] Step 3: pouring the melted metal in step 2 into the olivine sand mold to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment. The heat preservation time of the casting is 27 hours and the heat preservation temperature is 300°C.
[0096] Step 4: After the casting is heat-insulated, the temperature of the olivine sand is 100°C. The olivine sand used in the above steps is reprocessed by high-temperature sand regeneration technology to obtain recycled sand;
[0097] Step 5: performing air separation on the recycled sand in step 4 to obtain regenerated olivine sand;
[0098] Step 6: Mix the olivine sand regenerated in step 5 with water glass for a second time to obtain a new olivine sand mold.
[0099] In Comparative Example 4, when the olivine sand was reprocessed using the high-temperature sand regeneration technology of olivine sand, a large amount of ash was not separated from the sand particles, resulting in the ash content of the sea sand after air separation and regeneration being above 2.5%. During the high-temperature sand regeneration process, the residual sodium value on the surface of the sand particles in the recycled sand was 9.5.0%. The water glass content did not decrease during the secondary sand mixing process, and the sand mold strength after the secondary sand mixing and hardening was above 0.6 MPa, meeting production requirements.
[0100] Combining the data of Examples 1-3 and Comparative Examples 1-4 in the above description, it can be seen that using sea sand as surface sand, because its hardness is higher than that of olivine sand, will not be pulverized due to sintering and other reasons, and will not cause the ash content of the entire sand system to be high, resulting in continuous deterioration of the sand cycle. Moreover, after the casting is completed, the use of sea sand as surface sand will reduce the residual sodium content on the surface of the sand particles due to the close distance to the surface of the casting. The reduction in the residual sodium value will directly affect the amount of water glass added during the secondary sand mixing in the later stage, which has a good energy-saving economic value. After the casting is calcined at high temperature for more than 24 hours, the surface temperature of the casting is still around 300 degrees when it is unpacked. At this time, the temperature of the sea sand used as surface sand can reach about 100 degrees. Immediate regeneration of the sand return system at this temperature will reduce the probability of ash adhering to the sand particles and separate the ash from the sand particles. After air separation, the ash content is controlled at about 0.5%, ensuring the quality of the recycled sand. High-temperature sand return will reduce the moisture content of the entire recycled sand, ensuring its content at about 0.3%. The strength of the molding sand after secondary sand mixing and hardening reaches 0.6-0.8MPa, which meets production needs. The residual sodium value on the surface of the sand particles can also be further reduced during the high-temperature sand return regeneration process. The residual sodium drops to about 3.0%, which will significantly improve the subsequent sand mixing effect.
[0101] Performance Testing
[0102] The molding sands of the secondary sand mixing prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-4 are marked as Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, respectively. The molding sands of Examples 1-3 and Comparative Examples 1-4 are tested, and the specific test results are shown in the following table:
[0103]
[0104] It can be seen from the data in the table that the molding sand of the secondary sand mixing prepared by Examples 1-3 has a smooth surface and a cavity strength that meets the standards, which can effectively reduce the bulging phenomenon on the surface of the casting. Compared with olivine sand, sea sand can fill the mold space more evenly, avoid the formation of cavities and bulges, and the use of sea sand can also help improve the problem of insufficient shrinkage compensation due to bulges at the root of the riser. The performance of sea sand in the casting process may be more stable, and it can better support the riser area, ensuring that the riser shape and shrinkage compensation meet the requirements. Sea sand molding sand helps to reduce the pore problem on the surface and inside of the casting. Its particle morphology and chemical properties may be conducive to the release of gas during exhaust and casting, reducing the formation of pores.
[0105] The present invention uses sea sand instead of olivine sand as surface sand, which has strong advantages in hardness and stability in the casting process. The hardness of sea sand itself is higher than that of olivine sand, and it is not easy to pulverize. It can maintain good sand grain morphology and surface quality, and avoid the deterioration of sand circulation caused by pulverization; after the sea sand is sintered at high temperature, the residual sodium content on its surface will be reduced, which is beneficial to the amount of water glass added during the subsequent secondary sand mixing, saving energy and improving economic benefits; sea sand is used as surface sand, and in the high-temperature sand regeneration process, the ash content can be effectively controlled at a low level to ensure the quality and stability of the recycled sand; sea sand helps the strength of the molding sand to meet the requirements after hardening, and through its good fluidity and filling properties, it reduces the pore problem on the surface and inside of the casting; in the sintering and high-temperature sand regeneration process, sea sand can further reduce the residual sodium value on the surface of the sand grains, which has a significant improvement effect on the subsequent sand mixing effect and helps to ensure the quality of the casting. The above examples show that the process provided in the present invention that uses sea sand instead of olivine sand as surface sand has a better market application prospect.
[0106] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.
Claims
1. A process for using sea sand instead of olivine sand as surface sand, characterized in that: The casting process using sea sand as surface sand comprises the following steps: Step 1: Collect sea sand from the beach or seabed, and go through processes such as washing, drying and screening to obtain pre-treated sea sand; Step 2: Stir and mix the sea sand pretreated in step 1 with water glass to obtain mortar, add the mortar into the sand mold and compact it to obtain sea sand molding sand; Step 3: pouring the molten metal into the sea sand mold sand prepared in step 2 to perform a casting process. After the casting is completed, the casting is subjected to a heat preservation treatment; Step 4: After the casting is insulated, the sea sand used in the above steps is reprocessed by using the high-temperature sand regeneration technology to separate the ash on the surface of the sea sand from the sand particles to obtain recycled sand; Step 5: Perform air separation on the recycled sand in step 4 to obtain regenerated sea sand; Step 6: Mix the sea sand regenerated in step 5 with water glass for a second time to obtain new sea sand molding sand.
2. A process for using sea sand instead of olivine sand as surface sand according to claim 1, characterized in that: The method for processing the pre-treated sea sand in step 1 comprises the following steps: Step 1: Wash the sea sand with fresh water for 1-2 hours; Step 2: Dry the washed sea sand through drying equipment at a temperature of 250-300°C for 2-2.5 hours; Step 3: Screen the dried sea sand, and the particle size of the screened sea sand is 2-5mm.
3. The process of using sea sand instead of olivine sand as surface sand according to claim 1, characterized in that: In the step 3, the insulation time of the casting is 24-30 hours, and the insulation temperature is 280-320°C.
4. The process of using sea sand instead of olivine sand as surface sand according to claim 1, characterized in that: In the step 4, after the casting is heat-insulated, the temperature of the sea sand is 90-110°C.
5. The process of using sea sand instead of olivine sand as surface sand according to claim 1, characterized in that: In the step 4, the residual sodium value on the surface of the sand particles in the recycled sand is 2.8-3.2%.
6. The process of using sea sand instead of olivine sand as surface sand according to claim 1, characterized in that: In the step 5, the ash content of the regenerated sea sand after air separation is controlled at 0.4-0.6%.
7. The process of using sea sand instead of olivine sand as surface sand according to claim 1, characterized in that: In the step six, the content of water glass is 0.25-0.35%. The process of using sea sand instead of olivine sand as surface sand according to claim 1 is characterized in that: In the step six, the sand strength of the new sea sand is 0.6-0.8MPa.