Continuous water treatment device

Abstract

The invention belongs to the technical field of water treatment, particularly relates to a continuous water treatment device, and solves the problems of relatively low lithium adsorption efficiency and relatively low salt leaching efficiency. The continuous water treatment device comprises at least two belt filters for continuously treating brine for at least two times, and the two adjacent belt filters are respectively an upstream belt filter for performing primary treatment on the brine and respectively conveying effluent of an adsorption section, effluent of a salt leaching section and effluent of a desorption section to a downstream belt filter through a conveying assembly; and the downstream belt filter receives the adsorbent discharged from the tail end of the filter cloth of the upstream belt filter through the head end of the filter cloth of the downstream belt filter, and performs secondary treatment on the adsorption section effluent from the upstream belt filter by using the adsorbent from the upstream belt filter, the salt leaching section effluent and the desorption section effluent. The effects of efficient adsorption and recovery of lithium and high fresh water salt leaching efficiency are achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a continuous water treatment device. BACKGROUND

[0002] The method of using a vacuum belt filter (hereinafter referred to as a belt filter) combined with an adsorbent to treat brine is currently an effective method for extracting lithium from brine. For example, a Chinese invention patent with the publication number CN111825152B discloses a belt filter and its application in lithium extraction from brine by adsorption method. The belt filter includes a rack, a filter cloth reciprocally rotating on the rack, a solid-liquid separation zone, a salt washing zone, and a desorption zone arranged in sequence along the direction of the filter cloth. A mixing adsorption mechanism is arranged above the solid-liquid separation zone to deliver an adsorbent-brine mixture to the solid-liquid separation zone. A salt washing liquid delivery mechanism is arranged above the salt washing zone to deliver a salt washing liquid to the salt washing zone. A desorption liquid delivery mechanism is arranged above the desorption zone to deliver a desorption liquid to the desorption zone. A lithium elution liquid collection port is arranged below the desorption zone.

[0003] In the solid-liquid separation zone, the mixing adsorption mechanism pre-mixes the adsorbent and the raw brine to allow the adsorbent to fully adsorb lithium ions in the brine. Then, the adsorbent-brine mixture is delivered to the filter cloth in the solid-liquid separation zone to separate the adsorbent from the brine. The adsorbent remains on the filter cloth, and the brine filters through the filter cloth. In the salt washing zone, the salt washing liquid delivery mechanism delivers a salt washing liquid to the adsorbent on the filter cloth to elute ions other than lithium from the adsorbent (i.e., the salt washing section effluent). In the desorption zone, the desorption liquid delivery mechanism delivers a desorption liquid to the adsorbent on the filter cloth to elute lithium ions from the adsorbent. The lithium elution liquid that filters through the filter cloth is collected through the lithium elution liquid collection port (i.e., the desorption section effluent).

[0004] Although the lithium recovery rate of the belt filter can reach more than 70%, and the lithium concentration in the lithium elution liquid can reach 0.5 g / L, the brine that filters through the filter cloth in the solid-liquid separation zone (i.e., the adsorption section effluent) still contains a considerable amount of lithium that has not been fully collected. In the prior art, the adsorption section effluent is sprayed again onto the adsorbent in the solid-liquid separation zone to perform secondary adsorption using the adsorbent. However, at this time, the adsorption capacity of the adsorbent has reached saturation, and the secondary adsorption efficiency for lithium is very limited.

[0005] In addition, when there are multiple belt filters in the same plant, each belt filter basically operates independently. A large amount of fresh water is required for the salt washing zone and the desorption zone of each belt filter. The salt washing section effluent is usually returned to the salt field or salt lake, like the adsorption section effluent, without being reused. This results in a low fresh water salt washing efficiency. SUMMARY

[0006] The present application aims to provide a continuous water treatment device to improve lithium recovery efficiency and fresh water salt washing efficiency.

[0007] In order to achieve the above-mentioned object, the technical scheme of the present application is as follows: The continuous water treatment device comprises at least two belt filters for performing at least two treatments on brine, and two adjacent belt filters are respectively: An upstream belt filter, which is used for performing the first treatment on the brine and conveying the effluent from the adsorption section, the effluent from the salt washing section and the effluent from the desorption section to a downstream belt filter through a conveying assembly; The downstream belt filter receives the adsorbent unloaded from the tail end of the filter cloth of the upstream belt filter at the head end of the filter cloth thereof, and performs the second treatment on the effluent from the adsorption section from the upstream belt filter by using the adsorbent, the effluent from the salt washing section and the effluent from the desorption section from the upstream belt filter.

[0008] The present application connects at least two belt filters in series to perform at least two continuous treatments on the brine, wherein the upstream belt filter not only sends the desorbed adsorbent to the downstream belt filter after completing the first treatment (i.e. the whole process of adsorption, salt washing and desorption) on the brine, but also performs the second treatment on the effluent from the adsorption section by using the downstream belt filter. Specifically, the downstream belt filter first sprays the effluent from the adsorption section from the upstream belt filter onto the adsorbent for secondary contact adsorption; then sprays the effluent from the salt washing section from the upstream belt filter onto the adsorbent for salt washing operation; finally sprays the effluent from the desorption section from the upstream belt filter onto the adsorbent for desorption operation; thus, at least two continuous treatments on the brine are realized.

[0009] Since the adsorbent on the downstream belt filter has completed desorption on the upstream belt filter, the effective adsorption capacity is sufficient, and lithium in the effluent from the adsorption section can be fully recovered (lithium adsorption rate is more than 97%); compared with using fresh water as the salt washing liquid, using the effluent from the salt washing section of the upstream belt filter as the salt washing liquid of the downstream belt filter not only saves the amount of fresh water, but also carries away more impurity ions (i.e. salt ions adsorbed on the adsorbent except lithium), reduces the loss of lithium in the salt washing process (lithium loss rate is less than 3%); similarly, directly using the effluent from the desorption section of the upstream belt filter as the desorption liquid of the downstream belt filter not only greatly reduces the amount of desorption liquid (i.e. fresh water), but also ensures the lithium desorption efficiency and improves the lithium concentration of the lithium eluent.

[0010] The lithium eluent obtained by using the continuous water treatment device of the present application has a recovery rate of up to 94%, a lithium concentration of up to 0.75 g / L, and a salt-lithium ratio of less than 10:1, which can greatly reduce the cost investment of the subsequent membrane concentration section.

[0011] In the above-mentioned continuous water treatment device, each belt filter is provided with an adsorption assembly, a salt washing assembly and a desorption assembly arranged in sequence along the running direction of the filter cloth; The conveying assembly comprises: An adsorption section conveying unit is arranged between the adsorption assembly of the upstream belt filter and the adsorption assembly of the downstream belt filter, and is used for conveying the adsorption section effluent water; A salt washing section conveying unit is arranged between the salt washing assembly of the upstream belt filter and the salt washing assembly of the downstream belt filter, and is used for conveying the salt washing section effluent water; A desorption section conveying unit is arranged between the desorption assembly of the upstream belt filter and the desorption assembly of the downstream belt filter, and is used for conveying the desorption section effluent water.

[0012] As a further preferred, in the continuous water treatment device, the adsorption section conveying unit comprises an adsorption section effluent water collecting tank, which is used for collecting the adsorption section effluent water from the upstream belt filter; The adsorption assembly of the downstream belt filter comprises a brine distribution pipe for spraying the adsorption section effluent water to the adsorbent, and the brine distribution pipe is communicated with the adsorption section effluent water collecting tank.

[0013] The number and type of the adsorption section effluent water collecting tank are not limited, the original adsorption section effluent water from the upstream belt filter contains air and possibly a small amount of adsorbent, and the air (such as using a gas-liquid separation tank) and the adsorbent (such as using a magnetic separator, a precision filter, a ceramic membrane, etc.) can be separated before the adsorption section effluent water is sprayed through the brine distribution pipe to the downstream belt filter.

[0014] Obviously, the brine distribution pipe is arranged on each belt filter, for the first belt filter in the production line, the brine distribution pipe sprays the suspension of the adsorbent and the brine to be treated; and for the belt filter behind, the brine distribution pipe sprays the adsorption section effluent water from the upstream belt filter.

[0015] As a further preferred, in the continuous water treatment device, the salt washing section conveying unit comprises an upstream salt washing section effluent water collecting tank, which is used for collecting the upstream salt washing section effluent water from the upstream belt filter; The salt washing assembly of the downstream belt filter comprises a first salt washing liquid distribution pipe for spraying the upstream salt washing section effluent water to the adsorbent, and the first salt washing liquid distribution pipe is communicated with the upstream salt washing section effluent water collecting tank.

[0016] Similarly, the type and number of the upstream salt washing section effluent water collecting tank are not limited, and the original upstream salt washing section effluent water can be directly sprayed, or can be sprayed after the air and the adsorbent are separated.

[0017] Similarly, each belt filter is equipped with a salt washing liquid distribution pipe, for the first belt filter in the production line, the salt washing liquid distribution pipe generally sprays fresh water; and for the belt filter behind, the salt washing liquid distribution pipe sprays the upstream salt washing section effluent water from the upstream belt filter.

[0018] When only one salt washing unit is installed on the upstream and downstream belt filters, the effluent from the upstream salt washing section flows only to the downstream belt filter. However, when multiple salt washing units are installed on the upstream belt filter (or the upstream and downstream belt filters), the situation is slightly different.

[0019] That is: in the above-mentioned continuous water treatment device, the salt washing component includes at least a primary salt washing unit and a secondary salt washing unit, the primary salt washing units of the upstream belt filter and the downstream belt filter are connected in series, and the secondary salt washing units are connected in series, and the primary salt washing units and the secondary salt washing units are connected in series in sequence along the opposite direction of the filter cloth running direction, and the salt washing liquid is input from the primary salt washing unit of the upstream belt filter and flows out from the secondary salt washing unit of the downstream belt filter.

[0020] The specific circulation order is: the first-level salt washing unit with filter in the upstream belt—the first-level salt washing unit with filter in the downstream belt—the second-level salt washing unit with filter in the upstream belt—the second-level salt washing unit with filter in the downstream belt—····—external discharge.

[0021] That is, the salt washing section conveying unit further includes a downstream salt washing section effluent collecting tank, which is used to collect the effluent from the downstream salt washing section of the downstream belt filter; The salt washing component of the upstream belt filter includes a second salt washing liquid application pipe for spraying the downstream salt washing section effluent to the adsorbent, and the second salt washing liquid application pipe is connected to the downstream salt washing section effluent collection tank.

[0022] At this time, the effluent flow between the upstream and downstream belt filter salt washing sections adopts a multi-stage countercurrent method. Each salt washing section is divided into a primary salt washing unit and a secondary salt washing unit in the direction from downstream to upstream. The primary salt washing unit of the upstream belt filter arranges the filtered effluent from the salt washing section in the primary salt washing unit of the downstream belt filter for further washing, and pumps the washed effluent to the second salt washing unit of the upstream belt filter for reuse. The washed effluent is then sent to the second salt washing unit of the downstream belt filter, thereby increasing the number of countercurrent gradients for salt washing until the salinity of the effluent from the salt washing section is close to that of the brine before being discharged. In theory, the salinity of the effluent from the salt washing section can approach the brine value, but it is limited by the range of the salt washing section and the suction capacity of the belt filter. In actual operation, the core constraint is to maintain a high salinity in the effluent from the salt washing section.

[0023] When a three-stage salt washing unit is set in each belt filter of the present invention, the TDS of the effluent from the salt washing section can reach up to 180 g / L, indicating that it carries away more salt and has a higher salt washing efficiency. At the same time, since the salinity of its effluent is closer to that of brine, the lithium concentration of the effluent from the salt washing section is also closer to that of the brine effluent, which can achieve less water for salt washing and smaller lithium loss.

[0024] As preferred, in the continuous water treatment device, the desorption section conveying unit comprises a desorption section effluent collecting tank for collecting desorption section effluent from the upstream belt filter. The desorption assembly comprises a desorption liquid distribution pipe for spraying desorption section effluent to the adsorbent, which is in communication with the desorption section effluent collecting tank.

[0025] Similarly, the type and number of the desorption section effluent collecting tank are not limited, and the original desorption section effluent can be directly sprayed, or sprayed after separation of air and adsorbent.

[0026] Similarly, each belt filter is equipped with a desorption liquid distribution pipe. For the first belt filter in the production line, the desorption liquid distribution pipe generally sprays fresh water; and the belt filters behind spray desorption section effluent from the upstream belt filter.

[0027] As preferred, in the continuous water treatment device, all belt filters are at different horizontal heights; thus, it is beneficial to fully utilize the vertical space, and each belt filter can be arranged in any direction according to the terrain, with strong maneuverability.

[0028] As further preferred, in the continuous water treatment device, the projections of all belt filters in the vertical direction coincide or overlap (i.e., partially overlap), and the running directions of two adjacent belt filters above and below are opposite. At this time, all belt filters are arranged in a stacked manner, which is beneficial to further improve the space utilization.

[0029] As preferred, in the continuous water treatment device, the tail end of the filter cloth of the upstream belt filter is retracted in the horizontal direction compared to the head end of the filter cloth of the downstream belt filter, so that the adsorbent falls directly from the upstream belt filter to the downstream belt filter.

[0030] The tail end of the upstream belt filter is retracted to ensure that the adsorbent of the upstream belt filter can accurately fall directly onto the filter cloth of the downstream belt filter without the need for other conveying equipment.

[0031] There are many ways to retract the tail end of the filter cloth of the upstream belt filter, such as: The length of the upstream belt filter is shorter than that of the downstream belt filter to achieve the retraction of the tail end of the filter cloth of the upstream belt filter. Alternatively, the lengths of the upstream belt filter and the downstream belt filter are the same or different, and the two are arranged in a staggered manner to achieve the retraction of the tail end of the filter cloth of the upstream belt filter; the retraction length is between 1-3m.

[0032] The lengths of the two belt filters can be equal or different, but at least the upstream end of the upstream belt filter is retracted.

[0033] Generally, in order to make the filter cake of the adsorbent on the filter cloth, the brine, washing liquid, desorption liquid and the like to be treated are separated from the adsorbent as soon as possible, and the lower side of the filter cloth is provided with a negative pressure suction filter mechanism (such as a vacuum box). However, if the adsorbent falling from the upstream belt filter is immediately attracted by the negative pressure of the vacuum box, the adsorbent will be shaped before being evenly distributed, and the filter cake with uneven height (non-equal height distribution) will be formed on the filter cloth of the downstream belt filter, which is not conducive to the normal operation of the water treatment process.

[0034] In order to avoid the above problems, in the above continuous water treatment device, each belt filter includes a non-vacuum zone and a vacuum zone arranged in sequence along the running direction of the filter cloth, the non-vacuum zone is used to receive the mixture of the adsorbent and the brine (for the first belt filter on the production line) or the adsorbent (for the downstream belt filter), and the vacuum zone is used for negative pressure suction filtering.

[0035] As a further preferred, the length of the non-vacuum zone is between 1-2m. The non-vacuum zone is mainly used for cloth distribution, so the non-vacuum zone of the downstream belt filter is directly arranged below the tail end of the filter cloth of the upstream belt filter, and the length of 1-2m can ensure that the adsorbent falls into it accurately.

[0036] As a further preferred, the vacuum zones of at least two belt filters are formed by the same negative pressure suction filter mechanism. In this way, the vacuum system can be designed integrally, the total installed power of the system can be reduced, the equipment control system and pipeline can be reduced, and the equipment maintenance cost can be reduced.

[0037] As a preferred, in the above continuous water treatment device, between the uppermost belt filter and the lowermost belt filter among all the belt filters, a recycling mechanism for recycling the adsorbent to the uppermost layer is arranged; the number of the belt filter groups is an even number so that the head end of the filter cloth of the uppermost belt filter and the tail end of the filter cloth of the lowermost belt filter are located on the same side.

[0038] The application also provides a recycling mechanism arranged between the head and tail of the conveying path of the adsorbent, which can recycle the adsorbent at the end of the conveying path to the head of the conveying path, realize the recycling of the adsorbent, and enable the whole system to run continuously and autonomously. Moreover, the number of the belt filter groups is preferably an even number, so that the head and tail of the conveying path are located on the same side, which is beneficial to shorten the recycling distance of the recycling mechanism.

[0039] In the above continuous water treatment device, the recycling mechanism includes at least one group of elevators arranged along the width direction of the filter cloth of the belt filter, and the elevators are C-shaped and arranged semi-enclosingly around the periphery of each belt filter.

[0040] The elevator is in C type, which is partially surrounded in the periphery of the belt filter, partially overlaps in the vertical direction, improves the space utilization rate on the basis of recycling and returning, and can be arranged in multiple groups side by side to ensure complete recycling.

[0041] Compared with the prior art, the beneficial effects of the present application are reflected in: (1) The present application connects at least two belt filters in series to continuously process the brine at least twice. Since the adsorbent on the downstream belt filter has completed desorption on the upstream belt filter, the effective adsorption capacity is sufficient to fully recover lithium in the effluent of the adsorption section (lithium adsorption rate is more than 97%); compared with using fresh water as the salt washing liquid, using the effluent of the salt washing section of the upstream belt filter as the salt washing liquid of the downstream belt filter not only saves the amount of fresh water, but also removes more impurity ions (i.e. salt ions adsorbed on the adsorbent except lithium), reducing the loss of lithium during the salt washing process (lithium loss rate is less than 3%); similarly, directly using the effluent from the desorption section of the upstream belt filter as the desorption liquid of the downstream belt filter not only greatly reduces the amount of desorption liquid (i.e. fresh water), but also ensures the lithium desorption efficiency and improves the lithium concentration of the lithium eluent. The lithium eluent obtained by using the continuous water treatment device of the present application has a recovery rate of up to 94%, a lithium concentration of up to 0.75 g / L, and a salt-lithium ratio of less than 10:1, which can greatly reduce the cost investment of the subsequent membrane concentration section.

[0042] (2) In the present application, multiple belt filters are arranged vertically and connected end to end, which can make full use of the vertical space. Compared with laying all the belt filters flat, not only the occupied space area is greatly reduced, but also each belt filter can be arranged in any direction according to the terrain, with strong mobility; when all the belt filters are arranged in the same vertical plane (the running directions of adjacent belt filters are opposite), it is beneficial to further improve the space utilization rate, and the number of belt filters is preferably an even number, so that the first and last ends of the adsorbent conveying path are located on the same side, which is beneficial to the recycling and reuse of the recycling mechanism.

[0043] (3) In the present application, the tail end of the filter cloth of the upstream belt filter is recessed in the horizontal direction compared with the head end of the filter cloth of the downstream belt filter, so that the adsorbent on the upstream belt filter can directly fall onto the downstream belt filter without the need to set other conveying equipment; at the same time, the area where the adsorbent falls is the non-vacuum area of the downstream belt filter, so that the adsorbent can spread out fully in the non-vacuum area, and the adsorbent bed with uniform thickness can be formed in the vacuum area.

[0044] (4) In the present application, the water flow between the salt washing sections of the upstream belt filter and the downstream belt filter adopts a multi-stage countercurrent mode, each salt washing section is divided into a first salt washing unit and a second salt washing unit from downstream to upstream, the first salt washing unit of the upstream belt filter arranges the filtered salt washing section water for re-washing in the first salt washing unit of the downstream belt filter, and the water after washing is pumped to the second salt washing unit of the upstream belt filter for re-use, and the water after washing is sent to the second salt washing unit of the downstream belt filter, so as to increase the countercurrent gradient times of salt washing, until the salinity of the water after the final salt washing section is close to the salinity of the brine, and then discharged. In the present application, when three salt washing units are arranged in each belt filter, the TDS of the water after the salt washing section can reach 180 g / L at most, which indicates that more salt is taken away, the salt washing efficiency is higher, and at the same time, since the salinity of the water after the salt washing section is closer to the brine, the lithium concentration of the water after the salt washing section is also closer to the lithium concentration of the water after the brine, so that less salt washing water and less lithium loss can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a schematic diagram of the overall structure of a continuous water treatment device of the present application; Figure 2 is a schematic diagram of the overall structure of a continuous water treatment device of the present application; Figure 3 is a schematic diagram of the overall structure of a continuous water treatment device of the present application; Figure 4 is a schematic diagram of the overall structure of a continuous water treatment device of the present application; Figure 5 is a schematic diagram of the overall structure of a continuous water treatment device of the present application; Figure 6 is a schematic diagram of the overall structure of a continuous water treatment device of the present application.

[0046] In the figure, the belt filter 1, the upstream belt filter 2, the conveying assembly 3, the adsorption section 4, the salt washing section 5, the desorption section 6, the downstream belt filter 7, the filter cloth 8, the adsorption assembly 9, the salt washing assembly 10, the desorption assembly 11, the adsorption section water collection tank 12, the brine distribution pipe 13, the upstream salt washing section water collection tank 14, the first salt washing liquid distribution pipe 15, the first salt washing unit 16, the second salt washing unit 17, the desorption section water collection tank 18, the desorption liquid distribution pipe 19, the non-vacuum area 20, the vacuum area 21, the recovery mechanism 22, the elevator 23, the rack 24, the recovery conveying belt 25, the recovery section 26, the re-use section 27, the lifting section 28, the material blocking piece 29, the material accumulation groove 30, the material collecting hopper 31, the side blocking 32, the machine base 33, the filter cloth tail end 34, the C-shaped blocking 35, and the third salt washing unit 36. DETAILED DESCRIPTION

[0047] The following is a specific embodiment of the present application and further describes the technical solutions of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0048] The specific embodiments are as follows Figures 1-6 As shown in the drawings, the continuous water treatment device comprises at least two belt filters 1 for continuously implementing at least two treatments on the brine; the present application does not limit the number of belt filters 1, and the number can be set according to the actual production situation by those skilled in the art.

[0049] Similarly, the present application does not have special requirements for the combination mode of each belt filter 1, and each belt filter can be arranged in a flat manner in the factory building or arranged at different heights; compared with arranging all belt filters 1 in a flat manner, arranging them in an up-down manner not only greatly reduces the space area occupied, but also each belt filter 1 can be arranged in any direction according to the terrain, and has strong maneuverability.

[0050] Obviously, a more space-saving arrangement is to arrange all belt filters in an up-down manner in the same vertical plane and connect them in a head-to-tail manner, at which time the running directions of the adjacent two belt filters are opposite, and all belt filters form a conveying path of the adsorbent.

[0051] For the convenience of description, two belt filters 1 arranged in an up-down manner are taken as an example for description in this embodiment. From Figure 1 As can be seen, in the adjacent two belt filters 1, the belt filter 1 in the upper layer is the upstream belt filter 2, and the belt filter 1 in the lower layer is the downstream belt filter 7, and the downstream belt filter 7 receives the adsorbent falling from the tail end 34 of the filter cloth of the upstream belt filter 2 with the head end of the filter cloth.

[0052] In order to ensure that the adsorbent of the upstream belt filter 2 can accurately and directly fall into the filter cloth 8 of the downstream belt filter 7, the tail end 34 of the filter cloth of the upstream belt filter 2 is retracted in the horizontal direction compared with the head end of the filter cloth of the downstream belt filter 7, and the adsorbent can directly fall from the upstream belt filter 2 to the downstream belt filter 7 without the need to set other conveying equipment. In this embodiment, the length of the upstream belt filter 2 is shorter than the length of the downstream belt filter 7 to realize the retraction of the tail end 34 of the filter cloth.

[0053] As shown in Figure 1 , 2 , 4, each belt filter 1 comprises a machine base 33 and a filter cloth 8 circulating on the machine base 33. The working area of the filter cloth 8 comprises a non-vacuum area 20 and a vacuum area 21 arranged in sequence along the running direction of the filter cloth 8, and the non-vacuum area 20 is mainly used for cloth distribution. The non-vacuum area 20 of the downstream belt filter is directly arranged below the tail end 34 of the filter cloth of the upstream belt filter 2 for receiving the adsorbent from the upstream belt filter (for the belt filter in the uppermost layer, the non-vacuum area is used for receiving the mixture of the adsorbent and the brine); the length of the non-vacuum area 20 is between 1-2m, which can ensure that the adsorbent falls accurately into it.

[0054] The vacuum zone 21 is used for negative pressure filtration. In this embodiment, the vacuum zones 21 of the at least two belt filters 1 are driven by the same negative pressure filtration mechanism (such as a vacuum box) to form.

[0055] The machine base 33 is further provided with an adsorption assembly 9, a salt washing assembly 10 and a desorption assembly 11 arranged in sequence along the running direction of the filter cloth 8; these assemblies are generally arranged in the vacuum zone (as described above, the adsorption assembly 9 of the uppermost belt filter is an exception, which is generally arranged in the non-vacuum zone to form a uniform thickness of the adsorbent bed, and the brine distribution pipe of the adsorption assembly 9 distributes the mixture of the adsorbent and the brine. In the downstream belt filter 7, the adsorbent from the upstream belt filter 6 forms a uniform thickness of the adsorbent bed in the non-vacuum zone, and then the adsorption assembly 9 sprays the adsorption section effluent to the adsorbent bed, so the adsorption assembly 9 is generally arranged in the vacuum zone), wherein the adsorption assembly 9 is used to spray the brine to the adsorbent on the filter cloth (for the uppermost belt filter, the adsorption assembly can also be used to distribute the mixture of the brine and the adsorbent to the filter cloth), the salt washing assembly 10 is used to spray the salt washing liquid to the adsorbent on the filter cloth, and the desorption assembly 11 is used to spray the desorption liquid to the adsorbent on the filter cloth. This is a prior art, and this embodiment will not be described in detail.

[0056] Since the functions of the adsorption assembly 9, the salt washing assembly 10 and the desorption assembly 11 are all spraying, and only the water bodies sprayed are different, the structures are generally the same, such as the same distribution pipe (correspondingly, the brine distribution pipe 13, the first salt washing liquid distribution pipe 15 and the desorption liquid distribution pipe) can be used. All the distribution pipes are arranged along the running direction of the filter cloth 8, and each distribution pipe is arranged above the filter cloth 8. Each distribution pipe is provided with a plurality of distribution ports arranged along the width direction of the filter cloth 8, the distribution ports are uniformly distributed along the axial direction of the distribution pipe, and the extension direction is perpendicular to the conveying surface of the filter cloth 8 to ensure uniform distribution.

[0057] The mixed suspension of the brine to be treated and the adsorbent is input to the non-vacuum zone 20 of the upstream belt filter 2, the adsorbent forms an adsorbent bed in the non-vacuum zone, and the brine is filtered through the filter cloth to become part of the adsorption section effluent; the vacuum zone 21 realizes corresponding adsorption, salt washing and desorption treatment under the negative pressure of the negative pressure filtration mechanism, the filter cloth 8 of the upstream belt filter 2 retains the adsorbent, and each section effluent is transported to the downstream belt filter 7 through the conveying assembly 3.

[0058] Between each adsorption section 4, the adsorption section effluent of the upstream is transported to the downstream adsorption section 4 by the adsorption section conveying unit. The adsorption section effluent (including the brine filtered in the vacuum zone and the brine subjected to negative pressure filtration in the adsorption section) is input to the adsorption section of the downstream belt filter 7 through the brine distribution pipe 13 via the adsorption section effluent collection tank 12 and the corresponding connecting pipeline, which is beneficial to improve the adsorption rate of lithium.

[0059] The water from the upstream salt washing section is transported to the downstream salt washing section by the salt washing section transport unit.

[0060] When only one salt washing unit is arranged on the upstream belt filter or the downstream belt filter, the water from the upstream salt washing section is only flowed to the downstream belt filter through the salt washing section transport unit. At this time, the salt washing section transport unit comprises an upstream salt washing section water collecting tank 14 for collecting the water from the upstream salt washing section of the upstream belt filter 2; the salt washing assembly 10 of the downstream belt filter 7 comprises a first salt washing liquid distribution pipe 15 for spraying the salt washing section water to the adsorbent, which is connected with the upstream salt washing section water collecting tank 14 through a connecting pipe.

[0061] However, when multiple salt washing units are arranged on the upstream belt filter (or the upstream belt filter and the downstream belt filter), the situation is slightly different. At this time, the salt washing section transport unit further comprises a downstream salt washing section water collecting tank for collecting the water from the downstream salt washing section of the downstream belt filter; The salt washing assembly of the upstream belt filter comprises a second salt washing liquid distribution pipe for spraying the downstream salt washing section water to the adsorbent, which is connected with the downstream salt washing section water collecting tank.

[0062] At this time, the salt washing is carried out between the salt washing section 5 of the upstream belt filter 2 and the downstream belt filter 7 in a multi-stage countercurrent manner. This embodiment is described by taking an example that each salt washing assembly 10 comprises three salt washing units. The three salt washing units are arranged in the reverse direction of the filter cloth running direction, which are respectively a first salt washing unit 16, a second salt washing unit 17 and a third salt washing unit 36. The first salt washing units 16 are connected in series, the second salt washing units 17 are connected in series, and the third salt washing units 36 are connected in series. The first salt washing units 16 and the second salt washing units 17 are connected in series in the reverse direction of the filter cloth 8 running direction, and the second salt washing units 17 and the third salt washing units 36 are connected in series in the reverse direction of the filter cloth 8 running direction.

[0063] The salt washing liquid is input from the first salt washing unit 16 of the upstream belt filter 2. The first salt washing unit 16 of the upstream belt filter 2 arranges the filtered salt washing section water to be washed again in the first salt washing unit 16 of the downstream belt filter 7, and the water after washing is pumped to the second salt washing unit 17 of the upstream belt filter 2 for reuse. Similarly, the multi-stage countercurrent is carried out to increase the countercurrent gradient times of the salt washing, until the salinity of the salt washing section water approaches the salinity of the brine and is discharged. Theoretically, the salinity of the salt washing section water can approach the value of the brine, but it is limited by the salt washing section range and the suction capacity of the belt filter. In actual operation, the core constraint condition is to maintain the high salinity of the salt washing section water.

[0064] The specific circulation order is: the first-level salt washing unit 16 of the upstream belt filter 2 - the first-level salt washing unit 16 of the downstream belt filter 7 - the second-level salt washing unit 17 of the upstream belt filter 2 - the second-level salt washing unit 17 of the downstream belt filter 7 - the third-level salt washing unit 36 ​​of the upstream belt filter 2 - the third-level salt washing unit 36 ​​of the downstream belt filter 7 -... - discharge.

[0065] In the present invention, when a three-stage salt washing unit is provided in each belt filter 1, the TDS of the effluent from the salt washing section can reach up to 180 g / L, indicating that it carries away more salt and has a higher salt washing efficiency. At the same time, since the salinity of the effluent is closer to that of brine, the lithium concentration of the effluent from the salt washing section is also closer to that of the effluent from brine, thereby achieving less water for salt washing and smaller lithium loss.

[0066] Between each desorption section 6, the effluent from the upstream desorption section is transported to the downstream desorption section by a desorption section transport unit. The desorption section transport unit includes a desorption section effluent collection tank 18, which is used to collect the effluent from the upstream belt filter 2. The desorption assembly 11 includes a desorption liquid application pipe 19 for spraying the desorption section effluent onto the adsorbent. The desorption liquid application pipe 19 is connected to the desorption section effluent collection tank 18 via a connecting pipe. The desorption section effluent from the upstream belt filter 2 is applied to the adsorbent in the desorption section 6 of the downstream belt filter 7 via the desorption section effluent collection tank 18 and the corresponding connecting pipe through the desorption liquid application pipe 19, achieving secondary desorption, which is beneficial for improving the lithium recovery rate.

[0067] In this embodiment, there is no limit on the number and type of the adsorption section effluent collection tank, the salt washing section effluent collection tank, and the desorption section effluent collection tank. The original adsorption section effluent, the salt washing section effluent, and the desorption section effluent flowing out of the upstream belt filter contain air and may also contain a small amount of adsorbent. Before spraying the adsorption section effluent, the salt washing section effluent, and the desorption section effluent onto the downstream belt filter, the air (for example, by using a gas-liquid separation tank, etc.) and the adsorbent (for example, by using a magnetic separator, a precision filter, a ceramic membrane, etc.) can be separated out before spraying, or they can be sprayed directly. The present invention has no restrictions on this.

[0068] As can be seen from the figure, the filter cloth tail end 34 of the belt filter 1 is provided with a scraper assembly and a punching assembly (not specifically shown in the figure). The scraper assembly and the punching assembly can remove the adsorbent attached to the filter cloth, improve the recovery rate of the adsorbent, and are also beneficial to the regeneration of the filter belt or filter medium of the belt filter 1; a C-shaped enclosure 35 is provided in the downstream direction of the filter cloth tail end 34 of the belt filter 1. The length direction of the C-shaped enclosure 35 is vertical, and the opening faces the belt filter 1, which can block the cleaning liquid flushed out by the punching assembly.

[0069] Further, the present application also provides a recycling mechanism 22 for the adsorbent, which is arranged between the uppermost belt filter 1 and the lowermost belt filter 1, and can return the adsorbent at the end of the conveying path to the beginning of the conveying path, so as to realize recycling of the adsorbent, and enable the whole system to run continuously and autonomously. In order to be reasonable in layout, the number of the belt filters 1 is preferably an even number, so that the beginning and the end of the conveying path are located on the same side, which is beneficial to shortening the recycling distance of the recycling mechanism 22.

[0070] In the embodiment, the recycling mechanism 22 comprises at least one group of elevators 23 arranged along the width direction of the filter cloth 8 of the belt filter 1. The elevator 23 is in a C shape, and is arranged semi-surroundingly on the periphery of each belt filter 1, and partially overlaps in the vertical direction, so as to improve the space utilization rate on the basis of recycling and returning.

[0071] As shown in Figs. Figure 1 , 2 , 3, 6, the elevator 23 comprises a rack 24 and a recycling conveyor belt 25 which circulates on the rack 24. The recycling conveyor belt 25 comprises a recycling section 26, a recycling section 27 and a lifting section 28 connecting the recycling section 26 and the recycling section 27. The recycling section 26 is located at the lower side, and the front end extends below the filter cloth tail end 34 of the lowermost downstream belt filter 7. The recycling section 27 is located above the uppermost upstream belt filter 2.

[0072] The lifting section 28 is vertically arranged, and the surface of the recycling conveyor belt 25 is provided with a plurality of material blocking pieces 29 (only part of which is shown in the figure) arranged in sequence along the running direction of the recycling conveyor belt 25. Since the adsorbent is located on the inner side of the C-shaped recycling conveyor belt 25, i.e. on the lower side when conveyed to the recycling section 27, in order to ensure the lifting effect of the lifting section 28, the material blocking piece 29 is arranged at an angle of 30-60° with the recycling conveyor belt 25 to form a material accumulation groove 30 therebetween. The material accumulation groove 30 opens upward when passing through the lifting section 28, and opens obliquely downward when passing through the recycling section 27, so as to pour the adsorbent into the material collecting hopper 31 and guide the adsorbent to the corresponding position. The material collecting hopper 31 has a large opening at the upper side and a small opening at the lower side. The large opening is connected below the recycling section 27, and the front side is almost close to the lifting section 28, and the gap therebetween is slightly larger than the height of the material blocking piece 29, so as to collect the adsorbent returned by the recycling section 27. The small opening at the lower end can pour the adsorbent to the beginning of the conveying path, so as to realize recycling of the adsorbent.

[0073] As an optimization, in order to avoid the adsorbent on the filter cloth 8 from leaking to both sides, two side blocks 32 are also arranged oppositely on the rack 24. The side blocks 32 are in sliding connection with the side portions of the recycling conveyor belt 25, and are higher than the conveying surface of the recycling conveyor belt 25.

[0074] As a further explanation, the drawings provided by the present invention are mainly used for illustration, and some structures, such as the adsorption component 9, the salt washing component 10, the desorption component 11, the brine supply pipe 13, the first salt washing liquid supply pipe 15, the desorption liquid supply pipe 19, etc., do not fully show the structural details.

[0075] The specific working principle of the continuous water treatment device of this embodiment is: During operation, the brine supply pipe of the adsorption component 9 inputs the mixture of brine to be treated and adsorbent into the non-vacuum area 20 of the upstream belt filter 2, the adsorbent is retained on the filter cloth to form an adsorbent bed, and the brine is filtered through the filter cloth and collected by the adsorption section water collection tank 12, and transported to the adsorption section 4 of the downstream belt filter 7 through the brine supply pipe 13; as the filter cloth 8 runs, the adsorbent enters the vacuum area 21, and the negative pressure suction filtration mechanism performs negative pressure suction filtration treatment.

[0076] like Figure 5 As shown, in the adsorption section 4 of the upstream belt filter 2, the negative pressure suction filtration mechanism further separates the adsorbent and brine, and the brine is discharged from the bottom and collected by the adsorption section effluent collection tank 12, and is transported to the adsorption section 4 of the downstream belt filter 7 through the brine application pipe 13. In the salt washing section 5, the salt washing liquid application pipe of the upstream belt filter 2 sprays pure water onto the adsorbent, and the pure water washes the adsorbent and filters the filter cloth to become the salt washing section effluent. The salt washing section effluent flows along the path of the primary salt washing unit 16 of the upstream belt filter 2 - the primary salt washing unit 16 of the downstream belt filter 7 - the secondary salt washing unit 17 of the upstream belt filter 2 - the secondary salt washing unit 17 of the downstream belt filter 7 - the tertiary salt washing unit 36 ​​of the upstream belt filter 2 - the tertiary salt washing unit 36 ​​of the downstream belt filter 7, and is discharged from the tertiary salt washing unit 36 ​​of the downstream belt filter 7. After undergoing multi-stage countercurrent circulation treatment, other ions on the adsorbent are washed away. In the desorption section 6 of the upstream belt filter 2, the desorption component 11 sprays pure water onto the adsorbent for desorption. After solid-liquid separation, the effluent from the desorption section is collected in the desorption section effluent collection tank 18 and transported to the desorption section 6 of the downstream belt filter 7 through the desorption liquid supply pipe 19.

[0077] As for the adsorbent, it falls from the end of the upstream belt filter 2 to the non-vacuum area 20 of the downstream belt filter 7. After the adsorbent bed is formed, the effluent from the salt washing section and the desorption section of the upstream belt filter are used again to treat the effluent from the adsorption section of the upstream belt filter. After the treatment is completed, the adsorbent finally falls on the recovery section 26 of the recovery conveyor belt 25, and is lifted by the lifting section 28 to the reuse section 27. During this period, the cleaning component cleans the adsorbent, and the adsorbent in the reuse section 27 falls into the collecting hopper 31 and is re-injected into the upstream belt filter 2 from the lower end of the collecting hopper 31 to realize the recycling of the adsorbent.

[0078] To verify the advantages of the continuous water treatment device, in this embodiment, a certain Argentina brine was treated twice continuously by setting two layers of belt filters, each layer of belt filter with three stages of salt washing.

[0079] Table 1 Composition of a certain Argentina brine The effluent of the adsorption section, the effluent of the salt washing section and the effluent of the desorption section of the upstream belt filter and the downstream belt filter were collected respectively, and the lithium adsorption rate, the salt washing efficiency and the lithium recovery rate of the single-layer belt filter (i.e. only containing the upstream belt filter) and the double-layer belt filter (i.e. containing the upstream belt filter and the downstream belt filter) were compared, and the results are shown in Tables 2, 3 and 4.

[0080] Table 2 Comparison of lithium adsorption rate of single-layer belt filter and double-layer belt filter Lithium adsorption rate (%) = (brine lithium concentration - adsorption section effluent lithium concentration) / brine lithium concentration x 100%.

[0081] From Table 2, it can be seen that the Li + concentration of the effluent of the adsorption section of the double-layer belt filter is significantly reduced, indicating that the double-layer belt filter can adsorb more lithium (lithium adsorption rate reaches 97.2%).

[0082] Table 3 Comparison of salt washing efficiency of single-layer belt filter and double-layer belt filter From Table 3, it can be seen that since the double-layer belt filter can realize more countercurrent gradient in the salt washing section, under the same amount of fresh water, the TDS of the effluent of the salt washing section of the double-layer belt filter is higher, up to 180 g / L, indicating that it carries more salt and has higher salt washing efficiency. At the same time, since the salinity of the effluent of the salt washing section is closer to that of the brine, the lithium concentration of the effluent of the salt washing section is also closer to that of the effluent of the adsorption section. It can be seen that the double-layer belt filter can realize less fresh water consumption, higher salt washing efficiency and smaller lithium loss.

[0083] Table 4 Comparison of lithium recovery rate of single-layer belt filter and double-layer belt filter From Table 4, it can be seen that the double-layer belt filter uses the effluent of the desorption section of the upstream belt filter as the desorption liquid of the downstream belt filter (i.e. realizing countercurrent desorption), so that the lithium concentration of the effluent of the desorption section can reach 0.75 g / L, and the lithium recovery rate can reach 94%. The increase of the lithium concentration of the effluent of the desorption section can greatly reduce the consumption and investment of the subsequent membrane concentration section.

[0084] Comparative Example 1 The comparative example uses a single-layer filter to treat the same Argentinean brine as in Example 1, but two adsorptions are performed in the adsorption section: the effluent from the first adsorption is discharged from the gas-liquid separator into a buffer tank, and is sprayed again into the adsorption section of the single-layer filter by a transfer pump to complete the second adsorption after contacting the adsorbent. The lithium concentration of the effluent from the adsorption section of the first and second adsorptions is detected, respectively, and the results are shown in Table 5.

[0085] Table 5 Comparison of lithium adsorption rates of the single-layer filter for the first and second adsorptions As can be seen from Table 5, the second adsorption can adsorb more lithium ions, but the lithium adsorption rate is still lower than that of the double-layer filter because the adsorption capacity of the adsorbent has tended to be saturated.

[0086] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or replace them with similar ways, without departing from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A continuous water treatment device, characterized in that: The invention comprises at least two belt filters (1) for continuously treating the brine at least twice, wherein the two adjacent belt filters (1) are respectively: An upstream belt filter (2) is used to perform a first treatment on the brine and transport the effluent from the adsorption section (4), the effluent from the salt washing section (5) and the effluent from the desorption section (6) to a downstream belt filter (7) via a transport assembly (3); The downstream belt filter (7) receives the adsorbent discharged from the tail end of the filter cloth (8) of the upstream belt filter (2) at the head end of its filter cloth (8), and uses the adsorbent from the upstream belt filter (2), the water from the salt washing section (5) and the water from the desorption section (6) to perform a second treatment on the water from the adsorption section (4) of the upstream belt filter (2).

2. The continuous water treatment device according to claim 1, characterized in that Each belt filter (1) is provided with an adsorption component (9), a salt washing component (10) and a desorption component (11) which are sequentially arranged along the running direction of the filter cloth (8); The conveying assembly (3) comprises: An adsorption section conveying unit, the adsorption section conveying unit being arranged between the adsorption component of the upstream belt filter (2) and the adsorption component of the downstream belt filter (7), and being used for conveying water effluent from the adsorption section (4); A salt washing section conveying unit, the salt washing section conveying unit being arranged between the salt washing component of the upstream belt filter (2) and the salt washing component of the downstream belt filter (7), and being used for conveying water discharged from the salt washing section (5); A desorption section conveying unit is provided between the desorption component of the upstream belt filter (2) and the desorption component of the downstream belt filter (7) and is used for conveying water effluent from the desorption section (6).

3. The continuous water treatment device according to claim 2, characterized in that The adsorption section conveying unit comprises an adsorption section effluent collecting tank (12), and the adsorption section effluent collecting tank (12) is used to collect effluent from the adsorption section (4) of the upstream belt filter (2); The adsorption assembly (9) of the downstream belt filter (7) includes a brine application pipe (13) for spraying the effluent of the adsorption section (4) onto the adsorbent, and the brine application pipe (13) is connected to the effluent collection tank (12) of the adsorption section.

4. The continuous water treatment device according to claim 2, characterized in that The salt washing section conveying unit comprises an upstream salt washing section effluent collecting tank (14), the upstream salt washing section effluent collecting tank (14) being used to collect effluent from the salt washing section (5) of the upstream belt filter (2); The salt washing assembly (10) of the downstream belt filter includes a first salt washing liquid application pipe (15) for spraying the effluent of the salt washing section (5) onto the adsorbent, and the first salt washing liquid application pipe (15) is connected to the effluent collection tank (14) of the upstream salt washing section.

5. The continuous water treatment device according to claim 4, characterized in that: The salt washing assembly (10) comprises at least a primary salt washing unit (16) and a secondary salt washing unit (17), wherein the primary salt washing units (16) of the upstream belt filter (2) and the downstream belt filter (7) are connected in series, and the secondary salt washing units (17) are connected in series, and the primary salt washing units (16) and the secondary salt washing units (17) are connected in series in sequence in the opposite direction of the filter cloth running direction, and the salt washing liquid is input from the primary salt washing unit (16) of the upstream belt filter (2) and flows out from the secondary salt washing unit (17) of the downstream belt filter (7).

6. The continuous water treatment device according to claim 2, characterized in that: The desorption section conveying unit comprises a desorption section effluent collecting tank (18), and the desorption section effluent collecting tank (18) is used to collect effluent from the desorption section (6) of the upstream belt filter (2); The desorption assembly (11) comprises a desorption liquid application pipe (19) for spraying the desorption section (6) effluent water to the adsorbent, and the desorption liquid application pipe (19) is connected to the desorption section effluent water collection tank (18).

7. The continuous water treatment device according to any one of claims 1 to 6, characterized in that: The projections of all the belt filters (1) in the vertical direction coincide or overlap, and the running directions of the two belt filters (1) adjacent to each other are opposite; The tail end of the filter cloth (8) of the upstream belt filter (2) is retracted in the horizontal direction compared to the head end of the filter cloth (8) of the downstream belt filter (7) so that the adsorbent falls directly from the upstream belt filter (2) to the downstream belt filter (7).

8. The continuous water treatment device according to claim 7, characterized in that: The length of the upstream belt filter (2) is shorter than that of the downstream belt filter (7) to achieve the indentation of the tail end of its filter cloth (8); Alternatively, the upstream belt filter (2) and the downstream belt filter (7) are of equal or different lengths and are staggered to achieve the retraction of the tail end of the filter cloth (8) of the upstream belt filter (2); The indent length is between 1-3m.

9. The continuous water treatment device according to claim 7, characterized in that: Each belt filter (1) comprises a non-vacuum zone (20) and a vacuum zone (21) sequentially arranged along the running direction of the filter cloth (8), wherein the non-vacuum zone (20) is used to receive a mixture of an adsorbent and brine or the adsorbent, and the vacuum zone (21) is used to perform negative pressure suction filtration; The length of the non-vacuum zone (20) is between 1 and 2 meters; The vacuum zones of at least two belt filters (1) are driven and formed by the same negative pressure suction filtration mechanism.

10. The continuous water treatment device according to claim 7, characterized in that: Among all the belt filters (1), a recovery mechanism (22) for returning the adsorbent to the uppermost layer is provided between the belt filter (1) at the uppermost layer and the belt filter (1) at the lowermost layer; The number of groups of the belt filter (1) is an even number so that the head end of the filter cloth (8) of the uppermost belt filter (1) and the tail end of the filter cloth (8) of the lowermost belt filter (1) are on the same side; The recovery mechanism (22) comprises at least one set of elevators (23) arranged along the width direction of the filter cloth (8) of the belt filter (1). The elevators (23) are C-shaped and are semi-enclosed on the periphery of each belt filter (1).

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