Evaporative crystallization method and device for salt lake brine

Abstract

The invention discloses a salt lake brine evaporative crystallization method and device, and the crystallization method comprises the following steps: spreading and straightening a brine absorbing cloth, setting the included angle between the brine absorbing cloth and the horizontal plane to be 80-90 degrees, immersing the lower end of the brine absorbing cloth in brine, and carrying out evaporative crystallization; after evaporative crystallization, the lower end of the halogen absorbing cloth is removed from the brine, and salt on the halogen absorbing cloth is collected; the aperture of the halogen absorbing cloth is lt; the top end of the halogen absorbing cloth is positioned at the height gt above the brine; 7 m. Under the action of wind energy and solar energy, the brine evaporation speed of the brine absorption cloth per unit area is more than 20 times that of the salt pan solar pond per unit area, and the occupied area of the evaporation device and the salt pan can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of salt lake brine evaporation and crystallization, and in particular to a salt lake brine evaporation and crystallization method and device. Background Art

[0002] Salt lakes are rich in alkali and alkaline earth metals and boron and aluminum elements of the third main group. These elements exist in large quantities in the form of hydrochlorides, sulfates, and carbonates. In order to extract and separate these salts, the most commonly used method is to use salt pans or evaporators to precipitate them from brine one by one. The evaporation amount is mainly derived from the concentration of each salt phase point determined by the phase diagram of the water-salt system. The main advantage of salt pan evaporation is that it relies on solar energy for natural evaporation and does not require fuel. The disadvantage is that the evaporation amount depends entirely on the local gas phase conditions. If there is too much precipitation, the required salt pan area is huge. In addition to leakage, the constructed salt pan will partially change the groundwater composition in the area and may damage local water resources. The evaporator consumes a large amount of low-pressure steam or electricity to evaporate water. Although it is highly efficient, not restricted by the meteorological environment, and can achieve continuous mass production, the process consumes fossil energy. As the scale of evaporation increases, energy consumption increases, and the economy is poor.

[0003] A Chinese patent with publication number CN111943231A discloses an energy-saving salt-drying system and a salt-drying method using the same, including an energy-saving salt-drying system and a salt-drying method using the same, wherein the energy-saving salt-drying system includes an evaporation tank, a brine buffer tank, a slope crystallization system, and a solid-liquid separation system. A brine buffer tank connected to the evaporation tank is arranged below the slope crystallization system, and the brine buffer tank is connected to a brine distribution system arranged at the top of the slope crystallization system. By lifting and distributing the nearly saturated brine in the salt pool to the top of the slope, the brine forms a falling film and quickly evaporates and crystallizes during the process of flowing up and down the slope, and precipitates in the solid-liquid separation system at the bottom of the slope to obtain high-purity salt, which can be automatically transmitted to an external device. This scheme method realizes brine evaporation and crystallization through a slope crystallization system, and all salts are mixed and crystallized on the surface of the slope, and the subsequent separation and purification process is very complicated. Summary of the invention

[0004] The present invention aims to provide a salt lake brine evaporation crystallization method to achieve layered evaporation crystallization of different salts in the brine.

[0005] The present invention aims to provide a salt lake brine evaporation crystallization device to achieve layered evaporation crystallization of different salts in the brine.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for evaporating and crystallizing salt lake brine, comprising the following steps: unfolding and straightening a brine absorbing cloth, and setting the angle with the horizontal plane to 80° to 90°, and then immersing the lower end of the brine absorbing cloth in the brine to perform evaporation and crystallization; after evaporation and crystallization, removing the lower end of the brine absorbing cloth from the brine to collect salt on the brine absorbing cloth;

[0008] The pore size of the brine absorbing cloth is less than 2um, and the top of the brine absorbing cloth is located at a height of more than 7m above the brine.

[0009] The present invention is based on the capillary lifting principle. According to the capillary statics formula, the rising height of the solution in the capillary is: h=2γcosθ / (ρgr), wherein h is the suction height, γ is the surface tension, θ is the contact angle, ρ is the liquid density, g is the gravitational acceleration, and r is the capillary radius. Under the same conditions of other parameters, the surface tension γ of concentrated salt water is greater than the surface tension of pure water, the contact angle θ of pure water is greater than the contact angle of salt water (and θ<90°), then the salt water COS(θ)>pure water, although the density ρ of salt water is greater than the density of pure water, but the final γCOS(θ) / ρ of the salt water is greater than γCOS(θ) / ρ, therefore, for the same capillary radius r and gravitational acceleration g, the suction height of the salt water is greater than the suction height h of the pure water. Similarly, for salt waters of different concentrations, the lifting height of concentrated salt water is greater than that of dilute salt water.

[0010] According to calculations, as the capillary pore size decreases, the brine lifting height gradually increases. When the capillary pore size is 5um, the brine absorption height is 2.8m, when the capillary pore size is 1um, the brine absorption height is 14m, and when the capillary pore size is 0.5um, the brine absorption height is 28m. Therefore, when the capillary pore size transitions from micron level to nano level, the free absorption height of the aqueous solution can be significantly improved. With the expansion of the vertical surface area, the traditional solar plane evaporation mode of salt lake brine can be developed into a three-dimensional evaporation mode with the simultaneous action of solar energy and wind energy.

[0011] Depending on the different capillary pore sizes, the smaller the pore size, the higher the brine absorption height can be, the clearer the salt deposition area is, the larger the amount of salt precipitation at a single time is, and it is easier to extract and separate the salt.

[0012] As the thickness of the crystallized salt increases, the weight of the brine absorption cloth increases at the same time, and the degree of natural peeling of the salt crust also increases accordingly. At the same time, the salt formation speed will also be significantly reduced as the evaporation rate slows down. Therefore, the designed salt formation thickness should be determined comprehensively based on factors such as salt adhesion, salt crust strength, brine absorption cloth tensile strength, and salt formation speed. Within the safe brine absorption cloth tensile strength, salt adhesion, and salt crust overall strength, when the salt formation speed does not decay significantly, it is better to set the maximum salt formation thickness. Its value is usually determined by setting a fixed brine absorption time based on experimental results, and then the lower end of the brine absorption cloth is removed from the brine to collect the salt on the brine absorption cloth.

[0013] According to the embodiments of the present invention, the present invention can be further optimized. The following is the technical solution formed after optimization:

[0014] In one of the preferred embodiments, the pore size of the brine absorbing cloth is ≤1 um, and the height of the brine absorbing cloth above the brine is ≥14 m.

[0015] In one of the preferred embodiments, the pore size of the brine absorbing cloth is ≤0.5um, and the height of the brine absorbing cloth above the brine is ≥28m.

[0016] In one of the preferred embodiments, the angle between the halogen absorbing cloth and the horizontal plane is 90°.

[0017] Preferably, the salt lake brine evaporation and crystallization method further includes separating the lower end of the brine absorbing cloth from the brine after the evaporation and crystallization is completed, blowing heated pulse wind into the salt-forming areas of the same composition on one side for pressurized excitation, and sucking air at the same pulse frequency in the salt collection port on the other side. Blowing and sucking air alternately for several times to fully collect the crystallized salt on the brine absorbing cloth.

[0018] The hot air carrying salt particles is separated into gas and solid in a traditional dust collector to achieve crystallization, separation and storage of different salts in the brine.

[0019] The present invention also discloses a salt lake brine evaporation and crystallization device, comprising a support frame, the top of a brine absorption cloth is fixed in the support frame, the lower side of the brine absorption cloth is fixed in a tensioning device and is tensioned and unfolded, the lower end of the brine absorption cloth is immersed in a brine pool, the angle between the brine absorption cloth and the horizontal plane is 80° to 90°, the pore size of the brine absorption cloth is <2um, and the height of the brine absorption cloth above the brine is >7m.

[0020] In one of the preferred embodiments, corresponding salt mining frames are respectively arranged on both sides of the brine absorption cloth, and the salt mining frames are arranged in multiple layers, each layer of the salt mining frames can cover a salt mining area, and two salt mining ports are respectively arranged on both sides of each layer of the salt mining frame, and the salt mining ports are connected to the wind salt mining system, and the salt mining frames are fixed on the translation devices on both sides of the brine absorption cloth.

[0021] In one of the preferred embodiments, the wind-powered salt mining system includes a hopper, a spiral feeding device, and a drum dryer which are connected in sequence, and the hopper feed port is connected in sequence to a bag dust collector and a bag induced draft fan.

[0022] The air outlet of the drum dryer is connected to the feed inlet of the hopper through a drying induced draft fan.

[0023] The material outlet of the drum dryer is connected with the circular vibrating screen and the packaging machine in sequence.

[0024] In one preferred embodiment, the tensioning device is installed in a lifting system, and the lifting system controls the lower edge of the brine absorbing cloth to be immersed in the brine at all times.

[0025] In one of the preferred embodiments, high-strength fibers are added to the halogen-absorbing cloth as an anti-tension matrix.

[0026] Correspondingly, the strength requirement for brine cloth is higher, and high-strength fiber needs to be added as a tensile-resistant matrix, on this basis, it is woven into capillary fiber brine-absorbing cloth.

[0027] The specific operation mode of the device of the present invention is as follows:

[0028] (1) Chemical fiber cloth with pore size <2um (absorption height>7m) is used as the main component of capillary halogen absorption, referred to as halogen absorption cloth.

[0029] (2) The large area brine absorption cloth is straightened by a heavy hammer or other tensioning device. The lower edge of the brine absorption cloth is always immersed in the brine under the control of the lifting system.

[0030] (3) According to the different lifting heights of the capillary force of brine with different concentrations, the brine can be crystallized naturally in layers. That is, due to the different saturation concentrations of solution crystallization, the brine absorption cloth will automatically crystallize different salts at different heights; the higher the brine concentration, the higher the crystallization position. For example, for a certain brine, sodium chloride salt will first be crystallized at the lowest point of the brine absorption cloth, then potassium salt will be crystallized at its upper part, and then carnallite will be crystallized at a higher point, and then hydrochloric acid bischofite will be crystallized at a certain height, and lithium chloride salt will be crystallized at the top of the brine absorption cloth.

[0031] (4) Under the action of wind energy and solar energy, the evaporation rate of brine per unit area of ​​the brine absorption cloth is more than 20 times that of the salt field solar pond per unit area, which can effectively reduce the land area of ​​evaporation equipment and salt fields.

[0032] (5) In order to collect crystallized salt at different heights, salt collection ports are arranged on both sides of the brine absorption cloth according to different salt formation heights. The length of each layer of salt collection ports is equivalent to the horizontal width of the cloth, and the height of the salt collection ports can cover the corresponding salt formation area, and the salt collection ports are arranged adjacent to each other.

[0033] (6) When taking salt, the lifting system allows the cloth to be separated from the brine first; the translation device allows the salt collection ports on both sides of the brine absorption cloth to contact and press the brine absorption cloth on both sides at the same time to prevent crystallized salt from falling into other areas.

[0034] (7) When salt extraction begins, first blow heated pulse air into the salt extraction port on one side for pressurized stimulation (the air pressure is within the tolerance range of the brine absorption cloth), and at the same time, suction is performed at the salt extraction port on the other side at the same pulse frequency. The salt on the suction side is peeled off and enters the salt extraction port, and the salt on the blowing side is broken into small pieces and attached to the cloth surface. Then the suction and blowing directions are swapped, and ventilation stimulation is performed at the same time at the pulse frequency to suck the small pieces of salt on the blowing side into the salt extraction port. This method is used to alternate blowing and suction for several times to fully collect the crystallized salt on the brine absorption cloth. The hot air carrying the salt particles is then separated into gas and solid in a traditional dust collector to achieve the crystallization separation and storage of different salt contents in the brine.

[0035] (8) In order to collect the salt accumulated in the initial compression area and prevent it from affecting the sealing of the next salt collection port, the brine absorption cloth should be controlled to move slightly up, down, left and right so that the cloth is offset and compressed around each salt collection port and sucked into the salt collection port.

[0036] (9) After the salt extraction is completed, the salt extraction ports on both sides of the brine absorption cloth are separated from the cloth, and the lower bottom edge of the brine absorption cloth is controlled to re-extend to a certain depth below the brine liquid surface, thereby carrying out the next round of brine stratification evaporation.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] When the capillary pore size changes from micron to nanometer, the free adsorption height of the aqueous solution can be significantly increased. With the expansion of the vertical surface area, the traditional solar plane evaporation mode of salt lake brine can be developed into a three-dimensional evaporation mode with the simultaneous action of solar energy and wind energy.

[0039] Under the action of wind energy and solar energy, the evaporation rate of brine per unit area of ​​brine absorption cloth is more than 20 times that of salt field solar pond per unit area, which can effectively reduce the land occupied by evaporation equipment and salt fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural principle diagram of an embodiment of the present invention.

[0041] Figure 2 yes Figure 1 A-direction view.

[0042] Figure 3 This is a schematic diagram of the salt accumulation area of ​​the brine absorption cloth from bottom to top.

[0043] Figure 4 It is a structural principle diagram of another embodiment of the present invention.

[0044] In the figure: 1-support frame; 2-brine absorption cloth; 3-salt mining frame; 4-salt mining port; 5-brine pool; 6-brine surface; 21-bottom of brine absorption cloth; 7-lifting sprocket; 8-chain; 41-salt mining port 1; 42-salt mining port 2; 43-salt mining port 3; 44-salt mining port 4; 45-salt mining port 5; 9-wind salt mining system; 10-bag induced draft fan; 11-bag dust collector; 12-hopper; 13-drying induced draft fan; 14-drum dryer; 15-screw feeding device; 16-circular vibrating screen; 17-packaging machine. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0046] Example 1

[0047] Table 1 Composition of brine in Example 1

[0048]

[0049] According to the water-salt phase diagram analysis of the phase point, the horizontal salt formation areas distributed from bottom to top are:

[0050] Sodium chloride area, sylvite + sodium chloride area, magnesium sulfate + sodium chloride area, carnallite + magnesium sulfate area, magnesium chloride + magnesium sulfate area.

[0051] After obtaining the above mixed salts, they are generally purified by washing or flotation to obtain a single crystalline salt, such as potassium chloride by washing with sylvite salt water; magnesium sulfate monosalt is obtained by flotation of mixed salts in the magnesium sulfate + sodium chloride area, carnallite + magnesium sulfate area, and magnesium chloride + magnesium sulfate area; the remaining carnallite is washed with water to obtain potassium chloride monosalt; and the washing water is separately used in a pool for capillary evaporation to obtain bischofite monosalt.

[0052] Example 2

[0053] Table 2 Composition of brine in Example 2

[0054]

[0055] According to the water-salt phase diagram analysis of the phase point, the horizontal salt formation areas distributed from bottom to top are:

[0056] Sodium chloride area, sodium chloride + potassium carnallites area, potassium carnallites + hydroschistite area, lithium carnallites + potassium carnallites area, lithium carnallites + potassium carnallites + lithium chloride monohydrate area.

[0057] After obtaining the above mixed salts, generally, the next step of purification is carried out by washing with water and re-evaporation to obtain a single crystalline salt, such as: washing sodium chloride and potassium carnallites in the sodium chloride area and the sodium chloride + potassium carnallites area to obtain potassium chloride crystalline salt; washing the crystallization brine in the potassium carnallites + bischofite area to obtain potassium chloride crystalline salt, and the washing water is used to build a separate pool and then capillary evaporate to obtain bischofite crystalline salt; washing the crystallization brine in the lithium carnallites + potassium carnallites area and the lithium carnallites + potassium carnallites + lithium chloride monohydrate area to obtain lithium potassium mixed salt, and the washing water is used to build a pool and capillary evaporated bischofite, and the lithium potassium mixed salt can be separated into lithium chloride and potassium chloride single salt by temperature-variable evaporation crystallization.

[0058] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the embodiments made by those skilled in the art fall within the scope defined by the claims attached to the present invention.

Claims

1. A method for evaporating and crystallizing salt lake brine, characterized in that: The following steps are involved: The brine absorbing cloth is unfolded and straightened, and the angle with the horizontal plane is set to 80° to 90°, and then the lower end of the brine absorbing cloth is immersed in brine to perform evaporation and crystallization; after evaporation and crystallization, the lower end of the brine absorbing cloth is removed from the brine to collect the salt on the brine absorbing cloth; The pore size of the brine absorbing cloth is less than 2um, and the top of the brine absorbing cloth is located at a height of more than 7m above the brine.

2. The salt lake brine evaporation crystallization method according to claim 1, characterized in that: The pore size of the brine absorbing cloth is ≤1um, and the height of the brine absorbing cloth above the brine is ≥14m.

3. The salt lake brine evaporation crystallization method according to claim 1, characterized in that: The pore size of the brine absorbing cloth is ≤0.5um, and the height of the brine absorbing cloth above the brine is ≥28m.

4. The salt lake brine evaporation crystallization method according to claim 1, characterized in that: The angle between the halogen absorbing cloth and the horizontal plane is 90°.

5. A salt lake brine evaporation and crystallization device, comprising a support frame (1), the top end of a brine absorbing cloth (2) is fixed in the support frame (1), the lower side of the brine absorbing cloth (2) is fixed in a tensioning device and is stretched and stretched, the lower end of the brine absorbing cloth (2) is immersed in a brine pool (5), characterized in that: The angle between the brine absorption cloth and the horizontal plane is 80° to 90°, the pore size of the brine absorption cloth is <2um, and the height of the brine absorption cloth above the brine is >7m.

6. The salt lake brine evaporation crystallization device according to claim 5, characterized in that: The two sides of the brine absorption cloth (2) are respectively provided with corresponding salt mining frames (3), and the salt mining frames (3) are provided with multiple layers, and each layer of the salt mining frames can cover a salt mining area. Two salt mining ports (4) are respectively provided on both sides of each layer of the salt mining frame (3), and the salt mining ports are connected to the wind-powered salt mining system (9). The salt mining frames (3) are fixed on the translation devices on both sides of the brine absorption cloth (2).

7. The salt lake brine evaporation crystallization device according to claim 6, characterized in that: The wind-powered salt mining system (9) comprises a hopper (12), a spiral feeding device (15), and a drum dryer (14) which are connected in sequence, and the feed port of the hopper (12) is connected in sequence to a bag dust collector (11) and a bag induced draft fan (10).

8. The salt lake brine evaporation crystallization device according to claim 5, characterized in that: The tensioning device is installed in the lifting system.

9. The salt lake brine evaporation crystallization device according to any one of claims 5 to 8, characterized in that: High-strength fiber is added into the halogen-absorbing cloth as an anti-tension matrix.

Images