Treatment method for tail brine of reverse flotation-cold crystallization process

Abstract

The invention provides a treatment method for tail brine of a reverse flotation-cold crystallization process. The treatment method comprises the following steps: carrying out first brine blending on the tail brine of the reverse flotation-cold crystallization process and first old brine to obtain mineralization brine, and carrying out second brine blending on the mineralization brine and second old brine to obtain brine blending completion liquid and brine blending carnallite; decomposing and crystallizing the halogen-mixed carnallite to obtain potassium chloride; the volume ratio of the mineralizing brine to the second old brine is 1: (1.1-1.25). Compared with direct brine mixing, formation of sylvite can be effectively reduced through two times of brine mixing, low-sodium carnallite obtained after two times of brine mixing can directly participate in decomposition and crystallization of a crystallizer, a potassium chloride product is obtained, potassium waste in the middle link is further reduced, the tail brine treatment efficiency is improved, the treatment cost is reduced, the potassium chloride recovery rate is increased, and the method is suitable for industrial production. The treatment method for the tail brine of the reverse flotation-cold crystallization process is low in cost and short in period, recycling of the tail brine of the flotation process can be achieved, and potassium resources are fully recycled.

Description

Technical Field

[0001] The invention relates to the technical field of potassium salts, and in particular to a method for treating tail brine in a reverse flotation-cold crystallization process. Background Art

[0002] At present, the production of industrial potassium chloride in salt lakes mainly uses two processes: positive flotation and reverse flotation. Among them, the reverse flotation-cold crystallization process has the largest potassium chloride production capacity. In actual production, since carnallite is an asymmetric double salt, after adding a certain amount of fresh water and decomposition mother liquor, it will decompose to obtain high-grade potassium chloride. The fresh water decomposed in the thickener will be discharged to the tail salt pond with the decomposition mother liquor along with the overflow. Since there is still a certain amount of potassium chloride in the tail salt water, it has recovery value. In the prior art, the method for processing potassium chloride in the tail salt water is to discharge the tail salt water into the tail salt pond for precipitation and drying, and use solar energy to evaporate and concentrate the tail salt water, so that potassium chloride is precipitated in the form of solid phase minerals.

[0003] However, in the process of spreading and drying the concentrated tail brine, before forming carnallites, the potassium chloride in the tail brine will first coprecipitate with sodium chloride to form sylvite, causing the loss of potassium chloride. Sylvite is hard in texture and slow in dissolving speed. The existing production process needs to consume a lot of energy to extract the potassium chloride therein, which is costly and causes waste of potassium resources. In addition, since carnallites can only be obtained after the sylvite is precipitated, the existing treatment method has a long drying cycle and low efficiency. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for treating tail brine in a reverse flotation-cold crystallization process, so as to solve the problems of high treatment cost, long treatment cycle and low potassium chloride recovery rate of tail brine in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a method for treating tail brine of a reverse flotation-cold crystallization process, comprising the following steps: step S1, subjecting the tail brine of the reverse flotation-cold crystallization process to a first brine mixing with a first old brine to obtain ore-forming brine and a first brine mixing sediment; step S2, subjecting the ore-forming brine to a second old brine mixing with a second brine to a second brine mixing to obtain a brine mixing finished liquid and brine mixing carnallites; step S3, decomposing and crystallizing the brine mixing carnallites to obtain potassium chloride; wherein the volume ratio of the ore-forming brine to the second old brine is 1:(1.1-1.25).

[0006] Furthermore, the volume ratio of the mineralizing brine to the second old brine is 1:(1.15-1.22).

[0007] Furthermore, the volume ratio of the tail brine of the reverse flotation-cold crystallization process to the first old brine is 1:(1.12-1.22).

[0008] Furthermore, the density of the mineralizing brine is 1.270-1.275 g / L.

[0009] Furthermore, the halogenated carnallites are low-sodium carnallites, and the weight percentage of sodium is 3.5-9%.

[0010] Furthermore, the treatment method also includes: step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; preferably, the deposited carnallite is produced as a raw material for a positive flotation process; preferably, the clarified finished liquid is discharged to a carnallite pool for mineralization.

[0011] Furthermore, in terms of mass concentration, in the tail brine, KCl ≤ 2.5 g / L, NaCl ≤ 2 g / L, MgCl 2 ≤5g / L.

[0012] Furthermore, independently, in terms of mass concentration, in the first brine and the second brine, KCl is 0.07-0.20 g / L, NaCl is 0.1-0.3 g / L, MgCl 2 It is 33~36.5g / L.

[0013] Furthermore, in terms of mass concentration, in the mineralizing brine, KCl is 3.50-4.50 g / L, NaCl is 2.00-3.50 g / L, and MgCl 2 is 23.50-24.50 g / L; and / or in terms of mass concentration, in the first brine sediment, KCl is 2.20-2.40 g / L, NaCl is 79.50-80.50 g / L, MgCl 2 is 4.00-5.00 g / L; preferably, in terms of mass concentration, in the mineralizing brine, KCl is 3.68 g / L, NaCl is 2.85 g / L, and MgCl 2 is 24.13 g / L; and / or in terms of mass concentration, in the first brine sediment, KCl is 2.30 g / L, NaCl is 79.81 g / L, MgCl 2 It is 4.40g / L.

[0014] Furthermore, in terms of mass concentration, in the brine solution, KCl is 0.85-0.95 g / L, NaCl is 0.65-1.20 g / L, and MgCl 2 is 29.50-30.50 g / L; and / or by mass concentration, in the halogenated carnallite, KCl is 15.00-16.00 g / L, NaCl is 8.00-9.00 g / L, MgCl 2 is 28.00-29.00 g / L; preferably, in terms of mass concentration, in the brine solution, KCl is 0.92 g / L, NaCl is 1.15 g / L, MgCl2 is 30.16 g / L; and / or by mass concentration, in the halogenated carnallite, KCl is 15.54 g / L, NaCl is 8.35 g / L, MgCl 2 It is 28.27g / L.

[0015] The technical scheme of the present invention is applied, compared with direct brine conversion, twice brine conversion can effectively reduce the formation of sylvite, and the low-sodium carnallite after twice brine conversion can directly participate in the decomposition and crystallization of the crystallizer to obtain a potassium chloride product, further reducing the potassium waste in the intermediate link, and is conducive to improving the tail salt water treatment efficiency, reducing the processing cost, and improving the potassium chloride recovery rate, compared with the hot melt method to process sylvite, the energy consumption is lower and the production cost is relatively low, and compared with the flotation method to produce potassium chloride, it is more cost-effective. The processing method of the reverse flotation-cold crystallization process tail salt water of the present invention is low in cost and short in cycle, and the flotation process tail salt water recycling can be realized, and potassium resources are fully recovered. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 A process flow chart of treating tail brine in a reverse flotation-cold crystallization process according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] As described in the background of the present invention, the prior art has the problems of high cost of processing tail brine, long processing cycle and low potassium chloride recovery rate. In order to solve the above problems, in a typical embodiment of the present invention, a method for processing tail brine of reverse flotation-cold crystallization process is provided, comprising the following steps: step S1, the tail brine of reverse flotation-cold crystallization process is subjected to a first brine mixing with a first old brine to obtain ore-forming brine and a first brine mixing sediment; step S2, the ore-forming brine is subjected to a second brine mixing with a second old brine to obtain a brine mixing completed liquid and brine mixing carnallites; step S3, the brine mixing carnallites are decomposed and crystallized to obtain potassium chloride; wherein the volume ratio of the ore-forming brine to the second old brine is 1:(1.1-1.25).

[0020] The inventor unexpectedly found during the research process that if a one-step brine exchange is directly carried out, it will not only lead to the formation of sylvite, but also cause a high NaCl content in carnallites. When NaCl is high, a flotation process is required to process the NaCl in carnallites, which will also cause a waste of resources. Specifically, the present invention first exchanges the tail brine of the reverse flotation-cold crystallization process with the first old brine for the first brine exchange (also referred to as a one-time brine exchange), and in this process, the components of the tail brine can be extracted and reduced in magnesium and sodium, wherein the source of the tail brine of the reverse flotation-cold crystallization process mainly includes the overflow mother liquor of the refined potassium thickener. The purpose of the first brine exchange is to reduce the sodium content in the tail brine without losing potassium therein, so as to ensure the amount of carnallites produced by the second brine exchange, thereby modulating the tail brine into a mineralizing brine that meets the needs of the second brine exchange, and the sediment after the brine exchange is discharged to the tail salt ore pile for later use.

[0021] Then the prepared mineralizing brine is mixed with the second old brine for the second brine (also known as secondary brine mixing), and the mixing ratio of the mineralizing brine to the second old brine is 1:(1.1-1.25). In this process, the mineralizing brine and the old brine will undergo a common ion replacement reaction to obtain a brine mixing finished liquid and low-sodium brine mixed carnallites. The mixed carnallites are transported to a crystallizer for decomposition and crystallization, thereby realizing the recovery of potassium chloride in the tail brine, avoiding the formation of sylvite, and being beneficial to improving the tail brine treatment efficiency and reducing the treatment cost.

[0022] The ingredients of the first halite and the second halite may be the same or different.

[0023] Compared with direct brine addition, the two-time brine addition scheme of the present invention can effectively reduce the formation of sylvite, and the low-sodium carnallite after the two-time brine addition can directly participate in the decomposition and crystallization of the crystallizer, further reducing the potassium waste in the intermediate links, which is beneficial to improving the tail brine treatment efficiency, reducing the treatment cost, and improving the potassium chloride recovery rate.

[0024] The processing method of the tail brine of the reverse flotation-cold crystallization process of the present invention is low in cost. Compared with the hot melt method for treating sylvite and the positive flotation method for producing potassium chloride, the twice brine mixing process has lower energy consumption and more economical cost; since low-sodium carnallite is directly generated, the formation of sylvite is avoided, so the processing steps are reduced and the tail brine processing cycle is shortened; and by controlling the brine mixing process, the formation of sylvite is reduced, thereby improving the recovery rate of potassium resources and reducing resource waste. The processing method of the tail brine of the reverse flotation-cold crystallization process of the present invention is low in cost and short in cycle, can realize the recycling of the tail brine of the flotation process, fully recover potassium resources, and can also be promoted and applied to the recycling of overflow in the production of potassium chloride.

[0025] In a preferred embodiment, the volume ratio of the mineralizing brine to the second old brine is 1:(1.15-1.22). When the volume ratio of the second brine is within the above range, the potassium chloride (KCl), sodium chloride (NaCl), and magnesium chloride (MgCl) in the brine can be more accurately controlled. 2 ) concentration to promote the formation of carnallite and further effectively reduce the generation of sylvite, so that potassium chloride can be further fully recovered, the tail brine treatment efficiency can be improved, and the treatment cost can be reduced.

[0026] In order to better adjust the tail brine into a mineralizing brine that meets the needs of the second brine addition, and further reduce the loss of potassium while reducing the sodium content in the tail brine, in a preferred embodiment, the volume ratio of the tail brine in the reverse flotation-cold crystallization process to the first old brine is 1: (1.12-1.22), which is conducive to further increasing the amount of carnallite added with brine and improving the recovery rate of potassium chloride. The above volume ratio is more conducive to reducing the sodium content without significantly reducing the concentration of potassium, thereby generating the first brine addition sediment in the first brine addition step. This part of the sediment is rich in sodium salts and does not take away a large amount of potassium, which can directly improve the production efficiency and economic benefits of potassium chloride.

[0027] Moreover, the above volume ratio can also optimize the chemical composition of the mineralizing brine, making it more suitable for the second brine with the second old brine, and the generated low-sodium carnallite can be directly put into the crystallizer for decomposition and crystallization without additional pretreatment steps, so as to simplify the production process, shorten the processing cycle, and reduce the consumption of solar energy or artificial energy to further reduce production costs. In addition, by optimizing the brine ratio of the tail brine to the first old brine, the potassium resources in the tail brine can be more effectively recovered, and the total recovery rate of potassium can be improved, which not only helps to reduce the waste of potassium resources, but also increases the economic value of extracting potassium salts from the tail brine, making the entire treatment process more environmentally friendly and efficient.

[0028] Based on similar reasons, the density of the mineralization brine is controlled. In a preferred embodiment, the density of the mineralization brine is 1.270-1.275 g / L. The appropriate density can also make the crystallization process of carnallite more stable, reduce the problem of incomplete crystallization or low crystallization efficiency caused by improper density, and further improve the purity and yield of carnallite in the second brine addition process, thereby improving the production quality and efficiency of potassium chloride and reducing unit cost.

[0029] In a preferred embodiment, the halogenated carnallites are low-sodium carnallites, and the weight percentage of sodium is 3.5-9%. The content of impurity ions in the above-mentioned low-sodium carnallites is less, the quality of carnallites is higher, and the recovery of potassium chloride is more sufficient. Low sodium content means that during the decomposition and crystallization stage of carnallites, the precipitation of sodium salts is reduced, and its decomposition and crystallization process in the crystallizer can be faster and more efficient, thereby significantly shortening the treatment cycle of tail brine, which plays an important role in improving overall production efficiency. Moreover, the use of low-sodium carnallites is also conducive to improving the recovery rate of potassium resources. During the decomposition and crystallization process, due to the reduced interference of sodium, the precipitation of potassium chloride is purer, and the quality of the recovered potassium salt is higher, which not only increases the utilization efficiency of potassium resources, but also improves the market value of the product.

[0030] Because tiny low-sodium carnallite that cannot be settled floats in the brine-added liquid, in a preferred embodiment, the treatment method also includes: step S4, sedimenting the brine-added liquid to obtain sedimented carnallite and clarified liquid; preferably, the sedimented carnallite is produced as a raw material for a positive flotation process; preferably, the clarified liquid is discharged to a carnallite pool for mineralization, so as to utilize existing production conditions to further realize the full recovery and utilization of tail brine.

[0031] In order to further improve the effect of the first brine addition, in a preferred embodiment, in terms of mass concentration, in the tail brine, KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L. The above composition is basically consistent with the composition of the tail brine of most reverse flotation-cold crystallization processes, and is therefore more conducive to the promotion and application of the method of the present invention.

[0032] Based on similar reasons, in a preferred embodiment, the first and second old halides respectively and independently, by mass concentration, contain 0.07-0.20 g / L KCl, 0.1-0.3 g / L NaCl, and 0.1-0.3 g / L MgCl 2 It is 33~36.5g / L.

[0033] Controlling the KCl concentration within a specific range is also beneficial to retaining an appropriate amount of potassium during the brine addition process, so that the mineralized brine has a more suitable potassium concentration, providing favorable conditions for the subsequent formation of carnallite and the full recovery of potassium chloride. Controlling the NaCl concentration within a specific range can minimize the sodium content while ensuring the necessary salinity of the brine, which is beneficial to the formation of low-sodium carnallite, thereby reducing the formation of sylvite, simplifying the processing process, reducing energy consumption and costs, and improving the purity and recovery efficiency of potassium. MgCl 2 Concentration within an appropriate range can promote the stable formation of carnallite, improve crystallization efficiency, reduce impurities in brine, optimize the crystallization environment of carnallite, and make the crystallization of potassium chloride purer and more efficient.

[0034] Therefore, in a preferred embodiment, in terms of mass concentration, in the mineralization brine, KCl is 3.50-4.50 g / L, NaCl is 2.00-3.50 g / L, MgCl 2 is 23.50-24.50 g / L; and / or in terms of mass concentration, in the first brine sediment, KCl is 2.20-2.40 g / L, NaCl is 79.50-80.50 g / L, MgCl 2 is 4.00-5.00 g / L; preferably, in terms of mass concentration, in the mineralizing brine, KCl is 3.68 g / L, NaCl is 2.85 g / L, and MgCl 2 is 24.13 g / L; and / or in terms of mass concentration, in the first brine sediment, KCl is 2.30 g / L, NaCl is 79.81 g / L, MgCl 2 The above-mentioned mineralization brine and the first brine sediment are obtained faster than natural beach drying, and can skip the sylvite stage and directly generate carnallite, which is more conducive to reducing costs, improving efficiency and increasing potassium recovery in subsequent processes. Conventional sun drying will produce sylvite, and the above-mentioned brine cannot be used, resulting in the loss of KCl in the process of sylvite generation, and the sediment cannot be effectively used as tailings.

[0035] Based on similar reasons, in a preferred embodiment, in terms of mass concentration, in the brine solution, KCl is 0.85-0.95 g / L, NaCl is 0.65-1.20 g / L, and MgCl 2 is 29.50-30.50 g / L; and / or by mass concentration, in the halogenated carnallite, KCl is 15.00-16.00 g / L, NaCl is 8.00-9.00 g / L, MgCl 2 is 28.00-29.00 g / L; preferably, in terms of mass concentration, in the brine solution, KCl is 0.92 g / L, NaCl is 1.15 g / L, MgCl 2 is 30.16 g / L; and / or by mass concentration, in the halogenated carnallite, KCl is 15.54 g / L, NaCl is 8.35 g / L, MgCl 2 The brine-added finished liquid and brine-added carnallites of the above composition can directly generate low-sodium carnallites, which are directly involved in production without going through a flotation process, and are more conducive to the full recovery of potassium chloride in the tail brine.

[0036] Typically but not limiting, the volume ratio of the mineralizing brine to the second old brine is 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.20, 1:1.22, 1:1.25 or a range consisting of any two of them.

[0037] Typically but not limiting, the volume ratio of the tail brine to the first old brine in the reverse flotation-cold crystallization process is 1:1.12, 1:1.15, 1:1.16, 1:1.18, 1:1.20, 1:1.22 or a range consisting of any two of them.

[0038] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0039] Example 1

[0040] The process flow chart of the treatment of tail brine in the reverse flotation-cold crystallization process is as follows: Figure 1 shown.

[0041] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), and sent it to the brine mixing device with the first old brine for the first brine mixing. The volume ratio of the tailing brine and the first old brine in the reverse flotation-cold crystallization process is 1:1.2, and the mineralizing brine (density is 1.270g / L) and the first brine mixing sediment are obtained. The first brine mixing sediment is discharged to the tailing salt pile for later utilization.

[0042] Step S2, sending the prepared mineralizing brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the mineralizing brine to the second old brine is 1:1.2, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0043] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0044] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0045] Among them, the mass concentration of the main components in each feed liquid is as follows:

[0046] In the first brine, KCl is 0.15g / L, NaCl is 0.20g / L, MgCl 2 It is 35g / L.

[0047] In the second old brine, KCl is 0.15g / L, NaCl is 0.20g / L, MgCl 2 It is 35g / L.

[0048] In the mineralization brine, KCl is 3.68g / L, NaCl is 2.85g / L, MgCl 2 It is 24.13g / L.

[0049] In the first brine sediment, KCl is 2.30 g / L, NaCl is 79.81 g / L, MgCl 2 It is 4.40g / L.

[0050] In the brine solution, KCl is 0.92g / L, NaCl is 1.15g / L, MgCl 2 It is 30.16g / L.

[0051] In the halogenated carnallite, KCl is 15.54 g / L, NaCl is 8.35 g / L, MgCl 2 It is 28.27g / L.

[0052] Example 2

[0053] A method for treating tail brine in a reverse flotation-cold crystallization process.

[0054] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), and sent to the brine blending device with the first old brine for the first brine blending. The volume ratio of the tail brine of the reverse flotation-cold crystallization process to the first old brine was 1:1.2, and the ore-forming brine (KCl was 3.68g / L, NaCl was 3.22g / L, MgCl 2 23.88g / L) and the first brine sediment, the first brine sediment is discharged to the tailings pile for later utilization.

[0055] Step S2, sending the prepared mineralizing brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the mineralizing brine to the second old brine is 1:1.15, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0056] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0057] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0058] Example 3

[0059] A method for treating tail brine in a reverse flotation-cold crystallization process.

[0060] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2≤5g / L), and sent to the brine blending device with the first old brine for the first brine blending. The volume ratio of the tail brine of the reverse flotation-cold crystallization process to the first old brine was 1:1.2, and the ore-forming brine (KCl was 3.85g / L, NaCl was 3.05g / L, MgCl 2 23.71g / L) and the first brine sediment, the first brine sediment is discharged to the tailings pile for later utilization.

[0061] Step S2, sending the modulated ore-forming brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the ore-forming brine to the second old brine is 1:1.22, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0062] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0063] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0064] Example 4

[0065] A method for treating tail brine in a reverse flotation-cold crystallization process.

[0066] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), and sent it to the brine mixing device with the first old brine for the first brine mixing. The volume ratio of the tailing brine and the first old brine in the reverse flotation-cold crystallization process is 1:1.2, and the mineralizing brine and the first brine mixing sediment are obtained. The first brine mixing sediment is discharged to the tailing salt ore pile for later utilization.

[0067] Step S2, sending the modulated ore-forming brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the ore-forming brine to the second old brine is 1:1.1, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0068] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0069] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0070] Example 5

[0071] A method for treating tail brine in a reverse flotation-cold crystallization process.

[0072] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), and sent it to the brine mixing device with the first old brine for the first brine mixing. The volume ratio of the tailing brine and the first old brine in the reverse flotation-cold crystallization process is 1:1.2, and the mineralizing brine and the first brine mixing sediment are obtained. The first brine mixing sediment is discharged to the tailing salt ore pile for later utilization.

[0073] Step S2, sending the prepared mineralizing brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the mineralizing brine to the second old brine is 1:1.25, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0074] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0075] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0076] Example 6

[0077] A method for treating tail brine in a reverse flotation-cold crystallization process.

[0078] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), and sent it to the brine mixing device with the first old brine for the first brine mixing. The volume ratio of the tailing brine and the first old brine in the reverse flotation-cold crystallization process is 1:1.12, and the mineralizing brine and the first brine mixing sediment are obtained. The first brine mixing sediment is discharged to the tailing salt ore pile for later utilization.

[0079] Step S2, sending the prepared mineralizing brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the mineralizing brine to the second old brine is 1:1.2, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0080] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0081] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0082] Example 7

[0083] A method for treating tail brine in a reverse flotation-cold crystallization process.

[0084] Step S1, using the overflow mother liquor of the potassium concentrate thickener as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), and sent it to the brine mixing device with the first old brine for the first brine mixing. The volume ratio of the tailing brine and the first old brine in the reverse flotation-cold crystallization process is 1:1.22, and the mineralizing brine and the first brine mixing sediment are obtained. The first brine mixing sediment is discharged to the tailing salt ore pile for later utilization.

[0085] Step S2, sending the prepared mineralizing brine and the second old brine into a brine mixing device for a second brine mixing, the brine mixing ratio of the mineralizing brine to the second old brine is 1:1.2, and obtaining a brine mixing finished liquid and a low-sodium brine-mixed carnallites.

[0086] Step S3, transporting the halogenated carnallites to a crystallizer for decomposition and crystallization to prepare potassium chloride.

[0087] Step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; producing the deposited carnallite as a raw material for a positive flotation process; and discharging the clarified finished liquid to a carnallite pool for mineralization.

[0088] Example 8

[0089] The difference from Example 1 is that in the first and second brine, KCl is 0.07 g / L, NaCl is 0.30 g / L, and MgCl 2 It is 33g / L.

[0090] Example 9

[0091] The difference from Example 1 is that in the first and second brine, KCl is 0.20 g / L, NaCl is 0.10 g / L, and MgCl 2 It is 36.5g / L.

[0092] Comparative Example 1

[0093] The overflow mother liquor of the refined potassium thickener is used as the tail brine of the reverse flotation-cold crystallization process (KCl≤2.5g / L, NaCl≤2g / L, MgCl 2 ≤5g / L), discharged into the tail salt pond for precipitation and drying, and the tail salt water is evaporated and concentrated by solar energy, so that potassium chloride is precipitated in the form of solid phase minerals (carnallite and part of sylvite are obtained).

[0094] Comparative Example 2

[0095] The difference from Example 1 is that, in step S2, the modulated ore-forming brine and the second old brine are sent to the brine mixing device for the second brine mixing, and the brine mixing ratio of the ore-forming brine to the second old brine is 1:1, to obtain the brine mixing finished liquid and brine-mixed carnallites.

[0096] Comparative Example 3

[0097] The difference from Example 1 is that, in step S2, the modulated ore-forming brine and the second old brine are sent to the brine mixing device for the second brine mixing, and the brine mixing ratio of the ore-forming brine to the second old brine is 1:1.3, and the brine mixing completed liquid and brine mixed carnallites are obtained. If the magnesium ion content is too high under the brine mixing ratio, water is added.

[0098] The tail brine treatment period and KCl recovery rate of the above embodiments and comparative examples are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] As can be seen from the above, compared with the comparative example, each embodiment of the present invention adopts twice brine to effectively reduce the formation of sylvite, and the low sodium carnallite after twice brine can directly participate in the decomposition and crystallization of the crystallizer to obtain a potassium chloride product, further reducing the potassium waste in the intermediate link, which is conducive to improving the tail salt water treatment efficiency, reducing the processing cost, and improving the potassium chloride recovery rate, compared with the hot melt method to process sylvite, the energy consumption is lower and the production cost is relatively low, and it is more cost-effective to produce potassium chloride compared to flotation. The processing method of the reverse flotation-cold crystallization process tail salt water of the present invention is low in cost and short in cycle, and the flotation process tail salt water recycling can be realized, and potassium resources are fully recovered.

[0103] In addition, it can be seen that when each process parameter is within the preferred range of the present invention, the overall effect is better.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating tail brine in a reverse flotation-cold crystallization process, characterized in that: The following steps are involved: Step S1, performing a first brine mixing of the tail brine of the reverse flotation-cold crystallization process and the first old brine to obtain mineralizing brine and a first brine mixed sediment; Step S2, performing a second brine mixing operation on the ore-forming brine and the second old brine to obtain a brine mixing finished solution and brine mixing carnallites; Step S3, decomposing and crystallizing the halogenated carnallitite to obtain potassium chloride; Among them, the volume ratio of the mineralizing brine to the second old brine is 1:(1.1-1.25).

2. The processing method according to claim 1, characterized in that: The volume ratio of the mineralizing brine to the second old brine is 1:(1.15-1.22).

3. The processing method according to claim 1 or 2, characterized in that: The volume ratio of the tail brine of the reverse flotation-cold crystallization process to the first old brine is 1:(1.12-1.22).

4. The processing method according to any one of claims 1 to 3, characterized in that: The density of the mineralizing brine is 1.270-1.275 g / L.

5. The processing method according to any one of claims 1 to 4, characterized in that: The halogenated carnallites are low-sodium carnallites, and the weight percentage of sodium is 3.5-9%.

6. The processing method according to any one of claims 1 to 5, characterized in that: The treatment method further comprises: step S4, depositing the brine-added finished liquid to obtain deposited carnallite and clarified finished liquid; Preferably, the sedimentary carnallite is produced as a raw material for a positive flotation process; Preferably, the clarified finished liquid is discharged to a carnallite pool for mineralization.

7. The processing method according to any one of claims 1 to 6, characterized in that: In terms of mass concentration, in the tail brine, KCl≤2.5g / L, NaCl≤2g / L, and MgCl2≤5g / L.

8. The processing method according to any one of claims 1 to 7, characterized in that: Independently, in terms of mass concentration, in the first old brine and the second old brine, KCl is 0.07-0.20 g / L, NaCl is 0.1-0.3 g / L, and MgCl2 is 33-36.5 g / L.

9. The processing method according to any one of claims 1 to 8, characterized in that: In terms of mass concentration, the mineralization brine contains 3.50-4.50 g / L of KCl, 2.00-3.50 g / L of NaCl, and 23.50-24.50 g / L of MgCl2; and / or in terms of mass concentration, the first brine sediment contains 2.20-2.40 g / L of KCl, 79.50-80.50 g / L of NaCl, and 4.00-5.00 g / L of MgCl2; Preferably, measured by mass concentration, the KCl in the mineralizing brine is 3.68 g / L, the NaCl is 2.85 g / L, and the MgCl2 is 24.13 g / L; and / or measured by mass concentration, the KCl in the first brine sediment is 2.30 g / L, the NaCl is 79.81 g / L, and the MgCl2 is 4.40 g / L.

10. The processing method according to any one of claims 1 to 9, characterized in that: In terms of mass concentration, in the brine-added solution, KCl is 0.85-0.95 g / L, NaCl is 0.65-1.20 g / L, and MgCl2 is 29.50-30.50 g / L; and / or in terms of mass concentration, in the brine-added carnallite, KCl is 15.00-16.00 g / L, NaCl is 8.00-9.00 g / L, and MgCl2 is 28.00-29.00 g / L; Preferably, measured by mass concentration, the KCl content in the brine-added finished liquid is 0.92 g / L, the NaCl content is 1.15 g / L, and the MgCl2 content is 30.16 g / L; and / or measured by mass concentration, the KCl content in the brine-added carnallite content is 15.54 g / L, the NaCl content is 8.35 g / L, and the MgCl2 content is 28.27 g / L.

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