Method for desalination of sea sand

Abstract

This invention provides a method for desalinating sea sand, belonging to the field of sea sand desalination technology. It solves the technical problems of existing sea sand desalination methods, such as high chlorine and mud content in the desalinated sea sand, and high consumption of freshwater or electricity resources. The desalination method includes the following steps: feeding sea sand into a desalination tank, injecting freshwater into the tank, and then blowing air into the tank through an air inlet pipe at the bottom. The air forms bubbles and foam within the tank and rises to the surface of the freshwater. The sea sand that settles to the bottom of the tank is then subjected to ultrasonic treatment. This invention employs purely physical techniques, resulting in lower chlorine content and significantly reduced mud content in the desalinated sea sand with lower electricity and water consumption.

Description

Technical Field

[0001] This invention belongs to the field of sea sand desalination technology, and specifically refers to a method for desalinating sea sand. Background Technology

[0002] Currently, my country produces approximately 2.5 billion cubic meters of cement concrete annually. Including mortar and other uses, the annual demand for construction sand exceeds 3 billion tons. Due to the limited availability of land-based and freshwater sand resources, the supply of river sand, a key fine aggregate for concrete, is increasingly strained, leading to shortages in many areas. Simultaneously, to prevent excessive exploitation of river sand from causing severe damage to natural landscapes and the ecological environment, various regions have gradually implemented measures to restrict its use. To address this supply-demand imbalance, attention has turned to the oceans, which cover 70.8% of the Earth's surface, making the rational development and utilization of marine sand resources an inevitable choice.

[0003] However, because the chloride ion content in seawater is around 0.3%, the surface and pores of sea sand are covered with a large amount of chloride, which is difficult to remove. The chloride salts in sea sand can cause steel reinforcement to rust, and the passivation film on the surface of the steel reinforcement is destroyed by chemical reaction, which in turn forms corrosion cells on the surface of the steel reinforcement, resulting in electrochemical corrosion. The rust products produced by the continuous corrosion of steel reinforcement increase in volume by 4 to 7 times, which will generate expansion stress around the steel reinforcement. When it accumulates to a certain point, it will cause the concrete protective layer to expand and peel off or the steel reinforcement to crack. In order to improve the service life and structural strength of buildings, sea sand desalination is an essential step in the use of sea sand in construction projects.

[0004] At the same time, sea sand also contains varying degrees of mud (particles with a diameter of less than 75μm in natural sand). A high mud content in the sand can lead to a decrease in concrete strength. Relevant national standards for construction sand also have content requirements for this, which need to be washed and separated during the sea sand desalination process.

[0005] An analysis of domestic and international research progress on sea sand desalination reveals that, addressing the main problem of excessive chlorine content in sea sand, the following are the main sea sand desalination technologies currently used both domestically and internationally:

[0006] 1. Immersion cleaning method: Place sea sand in a pool and soak it in water to remove salt;

[0007] 2. Natural deposition method: Deposition utilizes natural rainwater erosion and weathering;

[0008] 3. Mechanical method: By using mechanical devices to tumble and mix sea sand and fresh water, rapid desalination is achieved.

[0009] 4. Electrolysis method: Sodium chloride is decomposed by electrolysis to achieve desalination;

[0010] 5. Chemical dechlorination method: This method uses chemical substances, such as desalination agents, to react with chloride ions to remove chlorine.

[0011] Among them, the immersion cleaning method and the natural stacking method are gradually being phased out due to their low efficiency and low chloride ion removal rate. The mainstream methods now are mechanical and electrolytic methods.

[0012] Mechanical methods, such as the utility model application with application number 202021636950.0, disclose a sea sand desalination system that cleans sea sand three times through a first, second, and third washing chamber. Each washing process involves high-frequency vibration motors vibrating the sea sand in the water source to remove surface salts through mutual friction. However, this sea sand desalination system can only reduce the chloride ion content in the sea sand to about 0.02%, which is still relatively high. While it can meet the chloride content requirements of some engineering concrete, a chloride ion content of 0.01%-0.02% will still affect the quality of the concrete. This type of sea sand can only be used in concrete with a strength grade below C35, and cannot be used in concrete with a higher strength grade. Furthermore, this method consumes a large amount of water.

[0013] Electrolysis, such as the utility model application with application number 202022796145.0, discloses an electrolytic spiral sea sand desalination and washing machine that decomposes sodium chloride by electrolysis. A variable-distance spiral propels the sea sand flow, controlling the electrolysis distance and time. It uses a small amount of fresh water to achieve sea sand desalination without wastewater pollution. It can be directly applied to beaches lacking fresh water, making it environmentally friendly and clean. The above-mentioned electrolysis method can reduce the chloride ion content in sea sand to about 0.003%, but it consumes a large amount of electricity during operation, which is not environmentally friendly.

[0014] Chemical dechlorination methods, such as the utility model application with application number 201822060691.0, disclose a complete set of sea sand desalination equipment. This method involves adding a desalination agent to a washing drum; after catalytic decomposition by the agent, chloride ion inorganic salt deposits float on the surface of the washing water and are then discharged through the overflow port of an excavator, thus achieving the effect of dechlorination of sea sand. However, the desalination agent and its byproducts added in this method can easily cause environmental pollution, and the desalination effect is poor while requiring a large amount of fresh water.

[0015] The "Standard for Construction Industry of the People's Republic of China JG / T 494-2016" clearly stipulates the requirements for purified sea sand used in construction and municipal engineering. Class I standard is mud content ≤1.0% and chloride ion ≤0.003%; Class II standard is mud content ≤2.0% and chloride ion ≤0.005%. The mechanical washing method mentioned above can meet the Class II standard, but it is still far from the Class I standard, and it consumes a large amount of freshwater resources during operation. Although the electrolysis method mentioned above can meet the Class I standard, it consumes a large amount of electricity during operation.

[0016] In addition, none of the existing methods for sea sand desalination mentioned above can effectively remove mud from sea sand and reduce the mud content of the desalinated sea sand.

[0017] Therefore, how to provide a desalination method for sea sand that has lower chlorine and mud content, is more environmentally friendly, saves more energy and fresh water has become an urgent technical problem to be solved. Summary of the Invention

[0018] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a desalination method that reduces the chlorine and mud content in sea sand, is more environmentally friendly, saves more energy, and produces fresh water.

[0019] The objective of this invention can be achieved through the following technical solutions:

[0020] A method for desalinating sea sand, characterized by comprising the following steps:

[0021] After the sea sand is fed into the desalination tank and fresh water is poured into it, air is blown into the tank through the air inlet pipe at the bottom. The air forms bubbles and foam in the tank and rises to the surface of the fresh water. The sea sand that has settled to the bottom of the desalination tank is then subjected to ultrasonic treatment.

[0022] In this invention, injecting air causes the sand-water mixture inside the desalination tank to tumble upwards, slowing down the settling of the sea sand and preventing rapid sedimentation. This allows for more thorough mixing of the sea sand and fresh water, facilitating the further precipitation of chloride ions and mud. Furthermore, due to the high pressure at the bottom of the desalination tank, the air entering forms small bubbles. As these bubbles rise, they expand and grow larger as the pressure decreases, forming larger bubbles. These larger bubbles burst under the impact of the sea sand or the cutting action of the agitator, creating cavitation. This cavitation effectively removes chloride ions and fine mud adhering to the surface of the sea sand. The desiccant stripping process allows chloride ions adhering to the surface of the sea sand and deep crevices to be released, improving the dechlorination effect and reducing the mud content in the sea sand. Furthermore, the bubbles formed after air blowing adsorb chloride-rich film components and tiny mud particles, forming chloride foam. As the chloride foam rises and is discharged from the top of the desalination tank, a considerable portion of chloride ions and tiny mud particles are separated from the sea sand and fresh water. This reduces the absorption of chloride ions and tiny mud particles by the fresh water during the desalination process, thereby reducing the concentration of chloride ions and tiny mud particles in the fresh water in the desalination tank. This further improves the desalination effect of this sea sand desalination equipment and allows for more repeated recycling of fresh water, saving water.

[0023] Cavitation refers to the process of the formation, development, and collapse of cavities of vapor or gas inside a liquid or at the liquid-solid interface when the local pressure inside the liquid decreases. The pulse effect generated when these cavities collapse can knock down dirt (chloride ions and tiny mud particles) from the surface and deep crevices of sea sand. The knocked-down chloride ions and tiny mud particles dissolve in fresh water and then separate from the sea sand, thus achieving the desalination of the sea sand.

[0024] After the ultrasonic device emits ultrasonic waves into the sand-water mixture, the ultrasonic waves propagating in the liquid can, under the action of cavitation, precipitate chloride ions and tiny mud particles from the surface and deep crevices of the sea sand. The specific principle is as follows: when the mechanical wave of the ultrasonic wave in the liquid reaches one atmosphere, its power density is 0.35 W / cm³. 2 At this point, the peak value of the ultrasound can reach a vacuum or negative pressure, but in reality, no negative pressure exists. Therefore, a large pressure is generated in the liquid, which tears the liquid molecules into cavitation nuclei. These cavitation nuclei are very close to a vacuum. They break when the ultrasound reaches its maximum in the reverse direction. The strong impact generated by the breakage knocks off dirt (chloride ions and tiny mud particles) from the surface and deep crevices of the sea sand. At the same time, the strong impact generated by the breakage also causes the relatively loose sand grains to break into tiny mud particles. These chloride ions and tiny mud particles separate from the larger sand grains and mix with the water, thus making the sea sand have a lower chloride content, less mud content, larger sand grains, and higher structural strength.

[0025] This desalination method combines cavitation phenomena generated by air blowing and ultrasonic waves. The two phenomena support each other functionally, resulting in lower chlorine and mud content in the sea sand. Furthermore, the entire desalination process requires no chemical additives, consumes less energy and fresh water, and is more environmentally friendly.

[0026] In one of the above-mentioned methods for desalinating sea sand, the sea sand is treated with ultrasound and then enters a sand-water separation device, where it is separated from the sand-water mixture by means of vibration, rotation, or sedimentation.

[0027] Even after ultrasonic treatment, sea sand still has a high water content, requiring sand-water separation to reduce the water content and meet the requirements for sea sand leaving the factory.

[0028] In one of the above-mentioned methods for desalinating sea sand, fresh water is sprayed into the sand-water separation device at the working front end.

[0029] After being treated with ultrasound, the sea sand is initially separated from the chlorine film and fine mud particles. By spraying fresh water at the front end of the sand-water separation device, the initially separated chlorine-containing components and fine mud particles can be mixed and diluted with the fresh water in a timely manner. The chlorine and mud content of the sea sand is further reduced by the sand-water separation device. This, combined with the ultrasound treatment, enhances the desalination effect of the method and further improves the desalination efficiency of the sea sand.

[0030] In one of the above-mentioned methods for desalinating sea sand, the sea sand is pre-treated with ultrasound before entering the desalination tank.

[0031] In this sea sand desalination method, ultrasonic treatment is performed on the sea sand before it enters the desalination tank. This treatment works in conjunction with the stirring and blowing in the subsequent process. It can promptly remove chloride ions and tiny mud particles that are released during the ultrasonic treatment process by stirring and mixing them in the fresh water. This can improve the desalination effect of the sea sand and further reduce the mud content of the sea sand.

[0032] In one of the above-mentioned methods for desalinating sea sand, air is injected into the desalination tank through an air inlet pipe at the bottom of the tank, while a stirring paddle is used to stir the sea sand and fresh water in the tank, so that the sea sand and fresh water are fully mixed.

[0033] The sea sand desalination method of the present invention actively stirs the sea sand by rotating a stirring paddle, which allows the sea sand to disperse in the water and avoid agglomeration, and provides sufficient contact and mixing with fresh water. This helps to dilute the chlorine film attached to the surface of the sea sand with the fresh water, and facilitates the precipitation of tiny mud particles. The precipitated chloride ions and tiny mud particles can dissolve in the fresh water and separate from the sea sand. The stirring of the stirring paddle can create horizontal flow in the water, which helps to slow down the settling of the sea sand and make the sea sand and fresh water mix more thoroughly.

[0034] During the desalination process, simple agitation with a stirring paddle often results in sea sand settling to the bottom of the tank, leading to poor sand-water mixing. Simply using air vents is also ineffective, as it's difficult to lift and disperse the sea sand in the water. This invention combines agitation with air vents; the two work together to effectively disperse the sea sand in the fresh water and ensure thorough sand-water mixing. A certain degree of cavitation effect allows for faster and more efficient precipitation of chloride ions and separation of fine mud particles. The combined action of air vents and agitation creates chloride foam within the desalination tank, causing chloride ions and fine mud particles to rise and be carried away, thus more effectively reducing the chloride and mud content of the sea sand and the absorption of chloride ions by the fresh water.

[0035] In one of the above-mentioned methods for desalinating sea sand, the sea sand is pretreated by screening for impurities before entering the desalination tank or before undergoing ultrasonic treatment, in order to remove impurities such as stones, shells, and plastics present in the sea sand.

[0036] Stones, shells, plastics and other debris in the sea sand are screened out to avoid affecting the desalination process; the screened sea sand is then transported to an ultrasonic device or desalination tank.

[0037] In the above-mentioned method for desalination of sea sand, during the desalination process, a sensor for detecting the height of sea sand deposition and a switch device for controlling the sand discharge rate are installed at the bottom of the desalination tank. The switch device can control the sand discharge rate based on the sea sand deposition height measured by the sensor, so that the sea sand deposition rate and the sand discharge rate can be kept in dynamic balance.

[0038] The sensor and switching device work together to control the sedimentation height and discharge rate of sea sand in the desalination tank. When the sensor detects sea sand, the switching device starts to work, discharging the sea sand from the bottom of the desalination tank, thereby reducing the sedimentation height of the sea sand in the tank. This provides space for the sea sand to accumulate, preventing the sea sand in the tank from piling up too high, which would affect the normal cleaning process of the sea sand in the tank. It also prevents the already deposited sea sand from re-entering the upper part of the desalination tank for repeated cleaning cycles, which is beneficial to improving the desalination efficiency of the sea sand desalination method. Furthermore, it allows the entire desalination process to be continuous and uninterrupted, which is beneficial to improving desalination efficiency and desalination capacity.

[0039] In one of the above-mentioned methods for desalinating sea sand, sufficient fresh water is injected into the desalination tank, allowing some of the fresh water to overflow from the top of the tank, which facilitates the removal of air bubbles and foam that rise to the surface.

[0040] In this desalination method, the combined action of injected air and agitator generates a large amount of chloride foam in the desalination tank. This chloride foam rises to the surface of the sand-water mixture. Chloride ions precipitated from the sea sand and some of the detached micro-mud adhere to the chloride foam. Continuous injection of fresh water causes the bubbles and foam to overflow from the desalination tank, thus promptly carrying away the precipitated chloride ions and micro-mud with the chloride foam. This reduces the overall chloride ion content and mud content in the desalination tank, preventing chloride ions and micro-mud that have been detached from the sea sand from re-integrating into the fresh water. This reduces the absorption of chloride ions and micro-mud by the fresh water during the desalination process, allowing for more repeated recycling of fresh water and saving water.

[0041] In one of the above-mentioned methods for desalinating sea sand, air bubbles and foam that rise to the surface are actively scraped out of the desalination tank using a scraper.

[0042] The aforementioned scraper design can actively, quickly, and promptly remove chloride foam floating on the liquid surface from the desalination tank, preventing chloride foam from floating on the top of the tank for too long. This prevents chloride ions and tiny mud particles attached to the chloride foam from re-integrating into the water as the chloride foam breaks up. This helps to further improve the desalination effect of this sea sand desalination method, resulting in lower chloride and mud content in the sea sand. It can also effectively reduce the absorption of chloride ions by fresh water during the desalination process, allowing for more repeated recycling of fresh water and saving water.

[0043] In the above-mentioned method for desalinating sea sand, the blades of the stirring paddle are tilted, with the leading edge of the blades being lower and the trailing edge higher in the direction of rotation, which facilitates giving the sea sand and fresh water an upward lift force.

[0044] The inclined agitator blades cut and guide the sand and water in the desalination tank during rotation, causing the sand and water to rise along the upper side of the blades. This upward lift prevents the sand from settling rapidly under gravity or the agitator's action, allowing sufficient contact time and opportunity between the sand and fresh water, thus improving the desalination effect and reducing the chlorine content in the sand. Simultaneously, the agitator design accelerates bubble bursting, and the multi-layered blades cut the bubbles multiple times, enhancing cavitation and further improving the desalination effect.

[0045] Compared with the prior art, the technical effects of the present invention are as follows:

[0046] This desalination method combines mechanical stirring, air blowing to create cavitation, and ultrasonic devices to create cavitation. These three elements support each other functionally, continuously and intensely impacting the surface and deep crevices of the sea sand. This results in a very good desalination and mud removal effect, leading to lower chlorine and mud content in the sea sand.

[0047] This sea sand desalination method employs purely physical techniques, resulting in lower chlorine content and significantly reduced mud content in the desalinated sea sand with lower electricity and water consumption. It solves a major technical challenge in global sea sand desalination and represents a significant technological contribution. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the overall structure of the desalination equipment used in this invention.

[0049] Figure 2 This is a schematic diagram of the desalination tank used in this invention.

[0050] Figure 3 This is a flowchart of the process of the present invention.

[0051] In the diagram, 1. Desalination tank; 11. Agitator; 111. Blade; 12. Scraper; 13. Air inlet pipe; 14. Sensor; 2. Upper ultrasonic device; 3. Lower ultrasonic device; 4. Switching device; 5. Rotary screen; 6. Sand-water separation device; 61. Spraying device; 7. Feed conveyor belt; 8. Discharge conveyor belt. Detailed Implementation

[0052] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0053] The desalination method for this sea sand includes the following steps:

[0054] First, impurity screening pretreatment is carried out to remove debris such as stones, shells, and plastics from the sea sand;

[0055] After sea sand is fed into desalination tank 1 and fresh water is poured into desalination tank 1, the sea sand and fresh water in desalination tank 11 are stirred with a stirring paddle 11 to make the sea sand and fresh water fully mixed. At the same time, air is blown into desalination tank 11 through air inlet pipe 13 at the bottom of desalination tank 1. The air forms bubbles and foam in desalination tank 1 and rises to the surface of fresh water.

[0056] The sea sand that has settled to the bottom of desalination tank 1 is subjected to ultrasonic treatment.

[0057] The sea sand is pre-treated with ultrasonic waves before entering desalination tank 1;

[0058] After being treated with ultrasound, the sea sand enters the sand-water separation device 6, where it is separated from the sand-water mixture by means of vibration, rotation, or sedimentation. Fresh water is sprayed into the sand-water separation device 6 at its working front end.

[0059] Furthermore, during the desalination process, the bottom of the desalination tank 1 is equipped with a sensor 14 for detecting the height of sea sand deposition and a switch device 4 for controlling the sand discharge speed. The switch device 4 can control the sand discharge speed based on the sea sand deposition height measured by the sensor 14, so that the sea sand deposition speed and the sand discharge speed can maintain a dynamic balance.

[0060] Furthermore, during the desalination process, sufficient fresh water is injected into the desalination tank 1, allowing some of the fresh water to overflow from the top of the desalination tank 1, which facilitates the removal of bubbles and foam that rise to the surface.

[0061] Furthermore, during the desalination process, air bubbles and foam that rise to the surface are actively scraped out of the desalination tank 1 using a scraper 12.

[0062] Furthermore, the blades 111 of the stirring paddle 11 are inclined, with the leading edge of the blades 111 being low and the trailing edge being high in the direction of rotation, which facilitates giving the sea sand and fresh water an upward lift.

[0063] The desalination equipment corresponding to this method includes, in sequence, a rotary screen 5, a feeding conveyor belt 7, an upper ultrasonic device 2, a desalination tank 1, a lower ultrasonic device 3, a switching device 4, a sand-water separation device 6, and a discharge conveyor belt 8. During operation, the rotary screen 5 removes impurities such as stones, shells, and plastics from the sea sand. The upper ultrasonic device 2 performs upper ultrasonic treatment on the sea sand. The sea sand in the desalination tank 1 is stirred and aerated. The scraper 12 scrapes out the salt foam and slurry from the upper side of the desalination tank 1. The lower ultrasonic device 3 performs lower ultrasonic treatment on the sea sand. The sand-water separation device 6 separates the desalinated sea sand from the water. A spray device 61 is positioned above the front end of the sand-water separation device 6, spraying fresh water onto the sea sand at its front end during operation.

[0064] Example 1

[0065] A method for desalinating sea sand, characterized by comprising the following steps:

[0066] S1. Pretreatment: Remove impurities such as stones, shells, and plastics from the sea sand before conveying it to desalination tank 1;

[0067] S2. Air blowing: After the sea sand and fresh water enter the desalination tank 1, air is injected into the desalination tank 1 through the air blowing hole. The air forms bubbles in the desalination tank 1 and bursts during the rising process, producing cavitation.

[0068] S3. Sedimentation: Over time, some sea sand gradually settles to the bottom of desalination tank 1 and is discharged from desalination tank 1 through the sand outlet at the bottom of desalination tank 1;

[0069] S4. Lower Ultrasonic Wave: The sea sand and fresh water discharged from the bottom of the desalination tank 1 enter the lower ultrasonic wave device 3. The lower ultrasonic wave device 3 emits ultrasonic waves into the mixture of sea sand and fresh water inside. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand, thus completing the desalination process.

[0070] In this embodiment, the desalination method for sea sand combines the cavitation phenomenon generated by air blowing and the cavitation phenomenon generated by ultrasound. The two support each other functionally, resulting in lower chlorine and mud content in the sea sand. Furthermore, no chemical agents need to be added during the entire desalination process, consuming less energy and fresh water, making it more environmentally friendly.

[0071] Example 2

[0072] A method for desalinating sea sand, characterized by comprising the following steps:

[0073] S1. Pretreatment: Remove impurities such as stones, shells, and plastics from the sea sand before conveying it to desalination tank 1;

[0074] S2. Air blowing: After the sea sand and fresh water enter the desalination tank 1, air is injected into the desalination tank 1 through the air blowing hole. The air forms bubbles in the desalination tank 1 and bursts during the rising process, producing cavitation.

[0075] S3. Sedimentation: Over time, some sea sand gradually settles to the bottom of desalination tank 1 and is discharged from desalination tank 1 through the sand outlet at the bottom of desalination tank 1;

[0076] S4. Lower ultrasonic wave: The sea sand and fresh water discharged from the bottom of the desalination tank 1 enter the lower ultrasonic wave device 3. The lower ultrasonic wave device 3 emits ultrasonic waves into the sea sand and fresh water mixture inside. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates the chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand.

[0077] S5. Sand-water separation: After being subjected to ultrasonic waves, the sea sand enters the sand-water separation device 6. Through methods such as vibration, rotation, or sedimentation, the sea sand is separated from the sand-water mixture, completing the desalination process.

[0078] In this embodiment, the sea sand desalination method combines cavitation phenomena generated by air blowing and cavitation phenomena generated by ultrasound. These two phenomena functionally support each other, resulting in lower chlorine and mud content in the sea sand. Furthermore, the entire desalination process requires no chemical additives, consuming less energy and fresh water, making it more environmentally friendly. Further, the aforementioned sand-water separation device 6 can dehydrate the desalinated sea sand, preventing chlorine and muddy water stains from adhering to the surface, thus further reducing the chlorine and mud content and improving the desalination effect of this method.

[0079] Example 3

[0080] A method for desalinating sea sand, characterized by comprising the following steps:

[0081] S1. Pretreatment: Remove impurities such as stones, shells, and plastics from the sea sand before conveying it to desalination tank 1;

[0082] S2. Air blowing: After the sea sand and fresh water enter the desalination tank 1, air is injected into the desalination tank 1 through the air blowing hole. The air forms bubbles in the desalination tank 1 and bursts during the rising process, producing cavitation.

[0083] S3. Sedimentation: Over time, some sea sand gradually settles to the bottom of desalination tank 1 and is discharged from desalination tank 1 through the sand outlet at the bottom of desalination tank 1;

[0084] S4. Lower ultrasonic wave: The sea sand and fresh water discharged from the bottom of the desalination tank 1 enter the lower ultrasonic wave device 3. The lower ultrasonic wave device 3 emits ultrasonic waves into the sea sand and fresh water mixture inside. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates the chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand.

[0085] S5. Sand-water separation: After being subjected to ultrasonic waves, the sea sand enters the sand-water separation device 6. Fresh water is sprayed onto the front of the sand-water separation device 6, and the sea sand is separated from the sand-water mixture by methods such as vibration, rotation or sedimentation, thus completing the desalination process.

[0086] In this embodiment, the sea sand desalination method combines cavitation phenomena generated by air blowing and cavitation phenomena generated by ultrasound. These two phenomena functionally support each other, resulting in lower chlorine and mud content in the sea sand. Furthermore, the entire desalination process requires no chemical additives, consuming less energy and fresh water, making it more environmentally friendly. Further, the aforementioned sand-water separation device 6 can dehydrate the desalinated sea sand, preventing chlorine and muddy water stains from adhering to the surface, thus further reducing the chlorine and mud content and improving the desalination effect of this method. During sand-water separation, spraying fresh water into the sand-water separation device 6 further rinses the sea sand, allowing residual chlorine and muddy water stains on the surface to be separated more thoroughly, reducing the chlorine and mud content in the dehydrated sea sand and further improving the desalination effect of this method.

[0087] Example 4

[0088] A method for desalinating sea sand, characterized by comprising the following steps:

[0089] S1. Pre-treatment: Remove stones, shells, plastics and other debris from the sea sand and then convey it to the ultrasonic device 2.

[0090] S2. Ultrasonic treatment: After the sea sand enters the ultrasonic treatment device 2, the ultrasonic treatment device 2 injects fresh water into the sea sand and emits ultrasonic waves. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand.

[0091] S3. Air blowing: After the sea sand and fresh water enter the desalination tank 1, air is injected into the desalination tank 1 through the air blowing hole. The air forms bubbles in the desalination tank 1 and bursts during the rising process, producing cavitation. The bubbles burst under the cutting of the stirring paddle 11 and the rotating sea sand, producing cavitation.

[0092] S4. Sedimentation: Over time, some sea sand gradually settles to the bottom of desalination tank 1 and is discharged from desalination tank 1 through the sand outlet at the bottom of desalination tank 1;

[0093] S5. Lower ultrasonic wave: The sea sand and fresh water discharged from the bottom of the desalination tank 1 enter the lower ultrasonic wave device 3. The lower ultrasonic wave device 3 emits ultrasonic waves into the sea sand and fresh water mixture inside. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates the chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand.

[0094] S6. Sand-water separation: After being subjected to ultrasonic waves, the sea sand enters the sand-water separation device 6. Fresh water is sprayed onto the front of the sand-water separation device 6, and the sea sand is separated from the sand-water mixture by methods such as vibration, rotation or sedimentation, thus completing the desalination process.

[0095] In this embodiment, the sea sand desalination method combines cavitation phenomena generated by air blowing with cavitation phenomena generated by upper and lower ultrasonic waves. These three phenomena support each other functionally, resulting in lower chlorine and mud content in the sea sand. Furthermore, the entire desalination process requires no chemical additives, consuming less energy and fresh water, making it more environmentally friendly. Further, the aforementioned sand-water separation device 6 can dehydrate the desalinated sea sand, preventing chlorine and muddy water stains from adhering to the surface, thus further reducing the chlorine and mud content and improving the desalination effect of this method. During sand-water separation, spraying fresh water into the sand-water separation device 6 further rinses the sea sand, allowing residual chlorine and muddy water stains on the surface to be separated more thoroughly, reducing the chlorine and mud content in the dehydrated sea sand after dehydration by the sand-water separation device 6, further improving the desalination effect of this method.

[0096] Example 5

[0097] A method for desalinating sea sand, characterized by comprising the following steps:

[0098] S1. Pre-treatment: Remove stones, shells, plastics and other debris from the sea sand and then convey it to the ultrasonic device 2.

[0099] S2. Ultrasonic treatment: After the sea sand enters the ultrasonic treatment device 2, the ultrasonic treatment device 2 injects fresh water into the sea sand and emits ultrasonic waves. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand.

[0100] S3. Stirring and blowing: After the sea sand and fresh water enter the desalination tank 1, the stirring paddle 11 rotates to form a vortex, which drives the sea sand and fresh water to rotate, thereby making the sea sand and fresh water fully mixed; at the same time, air is injected into the desalination tank 1 through the blowing hole. The air forms bubbles in the desalination tank 1 and bursts during the rising process, producing cavitation; the rotating stirring paddle 11 can generate negative pressure and guide the sea sand to reduce the sea sand deposition rate; the bubbles burst under the cutting of the stirring paddle 11 and the rotating sea sand, producing cavitation.

[0101] S4. Sedimentation: Over time, some sea sand gradually settles to the bottom of desalination tank 1 and is discharged from desalination tank 1 through the sand outlet at the bottom of desalination tank 1;

[0102] S5. Lower ultrasonic wave: The sea sand and fresh water discharged from the bottom of the desalination tank 1 enter the lower ultrasonic wave device 3. The lower ultrasonic wave device 3 emits ultrasonic waves into the sea sand and fresh water mixture inside. The cavitation phenomenon generated by the ultrasonic waves propagating in the liquid precipitates the chloride ions and tiny mud particles protruding from the surface and crevices of the sea sand.

[0103] S6. Sand-water separation: After being subjected to ultrasonic waves, the sea sand enters the sand-water separation device 6. Fresh water is sprayed onto the front of the sand-water separation device 6, and the sea sand is separated from the sand-water mixture by methods such as vibration, rotation or sedimentation, thus completing the desalination process.

[0104] In this embodiment, the sea sand desalination method combines the mechanical stirring of the stirring paddle 11, the cavitation phenomenon generated by air blowing, and the cavitation phenomenon generated by upper and lower ultrasonic waves. These four elements support each other functionally, resulting in lower chlorine and mud content in the sea sand. Furthermore, the entire desalination process requires no chemical additives, consumes less energy and fresh water, and is more environmentally friendly. Further, the aforementioned sand-water separation device 6 can dehydrate the desalinated sea sand, preventing chlorine and muddy water stains from adhering to the surface of the desalinated sea sand, thus further reducing the chlorine and mud content and improving the desalination effect of this sea sand desalination method. During sand-water separation, spraying fresh water into the sand-water separation device 6 further rinses the sea sand, allowing residual chlorine and muddy water stains on the surface of the sea sand to be separated more thoroughly, reducing the chlorine and mud content in the sea sand after dehydration by the sand-water separation device 6, and further improving the desalination effect of this sea sand desalination method.

[0105] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection defined by the claims of the present invention.

Claims

1. A method for desalinating sea sand, characterized in that, Includes the following steps: After the sea sand is sent into the desalination tank (1) and fresh water is injected into the desalination tank (1), air is blown into the desalination tank (1) through the air inlet pipe (13) at the bottom of the desalination tank (1). The air forms bubbles and foam in the desalination tank (1) and rises to the surface of the fresh water. The sea sand that has settled to the bottom of the desalination tank (1) is subjected to ultrasonic treatment.

2. The method for desalinating sea sand according to claim 1, characterized in that: After being treated with ultrasonic waves, the sea sand enters the sand-water separation device (6) and is separated from the sand-water mixture by means of vibration, rotation or sedimentation.

3. The method for desalinating sea sand according to claim 2, characterized in that: Fresh water is sprayed into the sand-water separation device (6) at the working front end.

4. The method for desalinating sea sand according to claim 3, characterized in that: The sea sand is subjected to ultrasonic treatment before entering the desalination tank (1).

5. The method for desalinating sea sand according to claim 4, characterized in that: While air is being blown into the desalination tank (1) through the air inlet pipe (13) at the bottom of the desalination tank (1), the sea sand and fresh water in the desalination tank (1) are stirred by the stirring paddle (11) so that the sea sand and fresh water are fully mixed.

6. A method for desalinating sea sand according to claim 4 or 5, characterized in that: Before the sea sand enters the desalination tank (1) or is subjected to ultrasonic treatment, impurity screening pretreatment is carried out to remove impurities such as stones, shells, and plastics present in the sea sand.

7. A method for desalinating sea sand according to any one of claims 1-5, characterized in that: During the desalination process, the bottom of the desalination tank (1) is equipped with a sensor (14) for detecting the height of sea sand deposition and a switch (4) for controlling the sand discharge speed. The switch (4) can control the sand discharge speed according to the height of sea sand deposition measured by the sensor (14), so that the speed of sea sand deposition and the speed of sand discharge can be kept in dynamic balance.

8. A method for desalinating sea sand according to any one of claims 1-5, characterized in that: Pour enough fresh water into the desalination tank (1) so that some of the fresh water overflows from the top of the desalination tank (1), which makes it easier to remove the bubbles and foam that rise to the surface of the liquid.

9. A method for desalinating sea sand according to claim 8, characterized in that: Use a scraper (12) to actively remove bubbles and foam that rise to the surface of the liquid from the desalination tank (1).

10. A method for desalinating sea sand according to claim 5, characterized in that: The blades (111) of the stirring paddle (11) are set at an angle, with the leading edge of the blades (111) being low and the trailing edge being high in the direction of rotation, so as to provide an upward lift to the sea sand and fresh water.

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