Method for preventing pollution and poisoning in lithium extraction process of aluminum adsorbent

Abstract

The invention relates to the technical field of extraction of lithium from brine, and discloses a method for preventing pollution and poisoning in the lithium extraction process of an aluminum adsorbent, lithium-containing brine containing high-sulfate, high-borate and high-concentration organic matters is used as a raw material, inorganic acid is used for adjusting the lithium-containing brine into a meta-acidic system, and then the lithium-containing brine is adsorbed to be saturated through the aluminum adsorbent; after leaching with a lithium salt-containing solution, desorbing the saturated adsorption column by using pure water, disinfecting the obtained desorbed effluent to obtain qualified liquid, and carrying out the steps of residual chlorine removal and the like to enter a subsequent production process. According to the method, the problems that the aluminum adsorbent is easily polluted by impurity ions in the brine, poisoned and blocked by floccules in the lithium extraction process can be solved, the performance of the aluminum adsorbent can be fully exerted, the process is continuous and stable, the efficiency is high, the cost is low, and the economic and environment-friendly benefits of the process of extracting the lithium from the brine are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium extraction from brine, and in particular to a method for preventing pollution and poisoning in a lithium extraction process using an aluminum-based adsorbent. Background Art

[0002] Lithium metal is a strategic energy metal for mankind in the 21st century. With the explosive growth of new energy electric vehicles in recent years, basic lithium salt products such as lithium carbonate and lithium hydroxide are in short supply in the medium and long term. Lithium mainly exists in nature in the form of solid ore and liquid ore. Among them, brine lithium resources from salt lakes, geothermal and oil fields account for about 70%. The cost of lithium extraction is lower than that of solid raw materials such as spodumene and lepidolite. Therefore, lithium extraction from brine has become the main source of the global lithium market.

[0003] The adsorption method is highly selective in separating and extracting lithium from salt lakes, is green and environmentally friendly, and has a high lithium yield. It can directly and efficiently extract lithium from the stock solution, is stable and efficient, and has become the preferred solution for direct lithium extraction from salt lakes, geothermal and oilfield water, or for recovering lithium from industrial tail liquids. At present, the adsorbents that can be used for lithium extraction include manganese, titanium and aluminum adsorbents. Among them, aluminum adsorbents use solvent water as a desorbent, and the dissolution rate of lithium extraction is very low, and it has entered the stage of industrial application. However, since aluminum adsorbents are easily contaminated and poisoned by various impurities such as high-valent, large-sized anions and organic matter in brine or industrial tail liquid, they have long been limited to heating the adsorption stock solution and desorption water in order to alleviate the pollution and poisoning problems of the adsorbent by increasing the adsorption-desorption rate of lithium. Practice has proved that this method does not have targeted characteristics, so the effect is not good.

[0004] The invention patent with the U.S. patent publication number US10266915B2 discloses a composition for recovering lithium from brine and a method for using the composition, by doping the adsorbent powder with high electron density metal ions such as Fe 3+ Mg 2+ 、Zn 2+ etc., significantly improving the cycle stability and working capacity of LiAl-LDH. However, although the doping and modification of aluminum-based adsorbents greatly improves the cycle stability of the adsorbents, it is not enough to ensure that the improved adsorbents can adapt to a wide range of adsorption stock solution water quality conditions. When the above-mentioned high-valent, large-sized anions and organic matter exist in large quantities in the adsorption stock solution, complex adsorption stock solution pretreatment, adsorbent regeneration and other processes are still required.

[0005] The invention patent with Chinese patent publication number CN114196840B discloses a method for extracting lithium from high sodium lithium-containing brine, that is, 2+ , Ca 2+ or Fe 2+The high-concentration solution of divalent cations such as Mg-SO4, Fe-SO4, Mg-B4O5(OH)4 is passed through the adsorption column after the lithium ion is adsorbed, and the strong interaction between divalent cations and high-valent and large-sized anions is used to convert SO4 into Mg-SO4, Fe-SO4, Mg-B4O5(OH)4 ion pairs. 2- , borate, organic acid radicals and other anions are "forced" to be eluted from the interlayer of LiAl-LDH. However, in the actual industrial production of lithium extraction from brine, if the above effect is achieved, a huge amount of divalent salts such as MgCl2, CaCl2 or FeCl2 purchased from outside are required; the regeneration process produces a large amount of sodium, potassium, SO4 2- The regenerated tail liquid containing impurities such as polyborates and organic acid radicals is also difficult to be reused through regeneration. The long-term use of these divalent salts will cause great damage to resources and the ecological environment. Even high-concentration magnesium chloride brine requires the construction of large salt fields to obtain it. This type of lithium resource is generally limited to chloride-type or magnesium sulfate-type hydrochemical types; due to the low efficiency of the salt field concentration process and severe lithium loss, it is actually not conducive to the adsorption method as a direct lithium extraction technology to play its advantages. Therefore, this type of method is extremely costly and difficult to industrialize.

[0006] The invention patent with Chinese patent publication number CN116121557A discloses a method for extracting lithium from sodium sulfate or sodium carbonate salt lakes using aluminum adsorbents, wherein the raw materials are filtered using nanofiltration membranes to remove CO3 2- 、SO4 2- , borate, organic matter and other impurity ions are removed in large quantities, and the resulting nanofiltration fresh water is used for adsorption and lithium extraction. Although this method can avoid the pollution and poisoning problems of aluminum-based adsorbents to a certain extent, it only transfers the pressure to nanofiltration. The nanofiltration membrane is also very susceptible to the precipitation of various impurities such as calcium sulfate, magnesium borate, and organic matter in the raw materials, which causes fouling and clogging, greatly shortening its service life and making it difficult to control costs; at the same time, due to the high salinity of the brine stock solution, the investment in nanofiltration membrane equipment is large, the energy consumption is high, and the yield is low. Therefore, this type of method has a long pretreatment process and significantly reduces the overall efficiency.

[0007] Many cases in this field show that the current cost of improving the cyclic stability of aluminum-based adsorbents is high, the effect is not ideal, and it is difficult to achieve industrial application. Therefore, how to prevent aluminum-based adsorbents from being contaminated, poisoned and inactivated when processing raw materials containing high sulfur, high boron and high concentrations of organic matter, and at the same time prevent the system from generating a large amount of flocs that pollute and block the adsorption column and pipeline, is a key issue related to whether the adsorption lithium extraction process can be successfully applied to the efficient extraction of lithium resources from brine and achieve industrial application. Summary of the invention

[0008] Based on the above technical problems, the purpose of the present invention is to provide a method for preventing pollution and poisoning in the process of lithium extraction using aluminum-based adsorbents. The method is simple, efficient, economical and environmentally friendly. During the process of lithium extraction using aluminum-based adsorbents, activation and regeneration of the adsorbent and elimination of fouling can be achieved simultaneously, thereby achieving continuous and stable operation of lithium extraction by adsorption and post-treatment processes.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for preventing pollution and poisoning in a lithium extraction process of an aluminum-based adsorbent, specifically comprising the following steps:

[0011] Step 1, acid adjustment: using lithium-containing brine as raw material, adding inorganic acid to the raw material to adjust the pH;

[0012] Step 2, adsorption: the acid-adjusted raw material is loaded into the adsorption stock solution tank, and then pumped into the adsorption system filled with aluminum adsorbent until adsorption saturation is achieved. The adsorption effluent obtained is the adsorption tail liquid;

[0013] Step 3, elution: using a lithium salt solution as elution water to wash away brine impurities in the saturated adsorption column to obtain an eluent, and the obtained eluent is recycled to the adsorption raw material tank;

[0014] Step 4, desorption: using pure water as desorption inlet water to elute the adsorption column after elution to obtain desorption effluent water;

[0015] Step 5, top water: use 0.4-0.6 BV volume of adsorption tail liquid in step 2 to reversely replace the adsorption column after desorption, push out the pure water remaining in the adsorption column, and obtain reverse top water. The obtained reverse top water is used as desorption inlet water for the desorption process;

[0016] Step 6, disinfection: disinfect the desorbed water obtained in step 4, and use the desorbed water with a volume fraction of 15% to 40% after disinfection as elution water for the elution process, and the remaining desorbed water is the qualified liquid.

[0017] By adopting the above technical scheme, the present application provides a method for preventing pollution and poisoning in the lithium extraction process of aluminum-based adsorbents. The process is short and the method is simple. It reduces energy consumption costs while improving lithium extraction efficiency. It also has little impact on resources and the environment, making it easy to realize industrial applications.

[0018] Furthermore, the lithium-containing brine described in step 1 also contains one or more mixed components of sulfate, borate or organic matter.

[0019] Furthermore, the inorganic acid in step 1 is hydrochloric acid, sulfuric acid or nitric acid, and the inorganic acid is added to the raw material to adjust the pH to 4.5-7.0.

[0020] The above technical solution is used to treat aluminum-based adsorbents that are susceptible to carbonate, sulfate, polyborates (such as B3O3(OH)4 - 、B4O5(OH)4 2- etc.), organic acid radical (R n- ) and other high-price or large-size anion pollution, and even showed a "poisoning phenomenon" in which the adsorption rate and desorption rate continued to decrease and the adsorbent gradually became inactive. The main reason may be that these anions are on the surface of the adsorbent and in the OH in the same layer of the adsorbent LiAl-LDH interlayer. - Form weak interactions such as hydrogen bonds, and their binding energy is significantly higher than that of Cl - Br - Plasma, or large-sized anions that enter the interlayer are difficult to be eluted by water molecules due to the steric hindrance effect. Therefore, inorganic acid is added to the system, and the hydrogen ions in it mainly play two roles: on the one hand, it combines with these high-valent and large-sized acid radical ions to reduce the valence of these anions or form neutral molecules, thereby weakening the electrostatic attraction between these anions and the adsorbent (positively charged); on the other hand, it forms new hydrogen bonds between oxygen-containing acid radicals and nitrogen-containing anions, and plays a role in destroying the hydrogen bonds between the hydroxides in the same layer of these anions in the LiAl-LDH interlayer, and plays a role in bridging the oxygen-containing acid radicals and nitrogen-containing anions in the solution. The effect of the superposition of these two types of effects is that, during the adsorption-desorption process, on the one hand, the above-mentioned pollutants in the solution are not easy to enter the adsorbent interlayer, and on the other hand, the above-mentioned pollutants that have entered the adsorbent interlayer are easy to be eluted. Therefore, the method of adjusting the acidity of the system has a very good effect, and only a small amount of industrial acid is consumed to achieve synchronous online activation and regeneration of the adsorbent.

[0021] Furthermore, the TDS of the elution water in step 3 is controlled within the range of 5.5 to 30 g / L, and the flow rate of the elution water is 4.0 to 6.7 BV / h, wherein TDS is the total dissolved solid content and BV is the adsorbent filling volume.

[0022] By adopting the above technical solution, by setting the range of TDS in the elution water, it is possible to control the adsorbent working capacity sacrificed due to elution, and by controlling the water inlet flow rate, the elution effect on the pollutants can be guaranteed.

[0023] Furthermore, the adsorption tail liquid described in step 5 adopts a reverse replacement method from bottom to top.

[0024] By adopting the above technical solution, the adsorption tail liquid described in step 5 contains only a small amount of lithium or no lithium, and only a small amount of adsorption tail liquid is used to reversely replace the adsorption column after desorption, and the pure water remaining in the adsorption column is pushed out to obtain reverse top water, and the obtained reverse top water can also be used as desorption inlet water for the desorption process. By repeatedly using the reverse top water, it is beneficial to further improve resource utilization.

[0025] Furthermore, the disinfection treatment described in step 6 is performed using an ozone generator, wherein the ozone concentration is 0.1 to 10 mg / L and the pH is adjusted to 4.5 to 7.0.

[0026] Furthermore, the disinfection treatment described in step 6 adopts the addition of hypochlorous acid or hypochlorite for disinfection, the concentration of oxidizing chlorine is 0.02-5.0 mg / L, and the pH is adjusted to 4.5-7.0.

[0027] By adopting the above technical scheme, the adsorption system, the adsorption qualified liquid, and the elution liquid are prone to produce flocs, which leads to the blockage of the adsorbent bed, the filter cap of the water distributor and the pipeline. After analysis and research, it is found that the key factors for the formation of flocs are microorganisms such as bacteria and fungi. Due to the presence of more organic matter such as carbon sources and nitrogen sources in brine, as well as the presence of elements such as iron, aluminum, silicon, magnesium, and zinc, it is conducive to the rapid reproduction of microorganisms in a low salinity and normal temperature environment. Under specific conditions, the corpses and metabolites of microorganisms are combined with trace elements such as iron and aluminum and organic matter to form a considerable amount of colloids or flocs. To this end, the qualified liquid, elution liquid and other fluids in the system can be converted into a weak oxidizing atmosphere to inhibit the reproduction of microorganisms, thereby avoiding the pollution and blockage of the adsorption system and the back-end membrane system due to the large-scale generation of colloids and flocs, resulting in the inability to continue and stabilize production. After the above disinfection treatment, it is beneficial for the adsorption system to give full play to its lithium extraction efficiency.

[0028] Furthermore, step 6 also includes removing residual chlorine from the qualified liquid using sodium bisulfite or sodium sulfite, and the end point of removing residual chlorine is that the residual chlorine content is less than 0.1 mg / L.

[0029] By adopting the above technical scheme, the qualified liquid is freed of residual chlorine by using sodium bisulfite or sodium sulfite, that is, the qualified liquid is reduced before the membrane treatment process at the rear end of the adsorption, so as to facilitate the subsequent production process.

[0030] In summary, the present invention has the following beneficial effects:

[0031] (1) The method of the present invention can prevent the aluminum adsorbent from being contaminated and poisoned during the lithium extraction process by adding only a small amount of inorganic acid and a very small amount of oxidant to the system. It can also control and eliminate the precipitation of flocs. On the one hand, it significantly improves the lithium extraction rate of the aluminum adsorbent and greatly improves the stability of the lithium extraction process of the aluminum adsorbent. On the other hand, because it can realize the simultaneous activation, regeneration and disinfection of the adsorption process, it has low cost and significant effect. The method of the present invention provides favorable conditions for maintaining the stable working capacity of the aluminum adsorbent, stabilizing the output of the adsorption system and realizing industrial application.

[0032] (2) The method of the present invention can ensure that the adsorbent operates at a higher lithium extraction rate without heating the adsorption solution and desorption water. Compared with conventional methods that require heating, it does not require high heat source costs (only raising the desorption water temperature by 20°C consumes 30 to 40 GJ / ton of lithium carbonate heat energy).

[0033] (3) The method of the present invention does not require adding a regeneration step to the adsorption process, nor does it require consuming a huge amount of divalent metal salts or using a large amount of highly concentrated toxic magnesium chloride brine, which significantly reduces the regeneration cost and avoids the damage caused by a large amount of regeneration waste liquid to salt lakes, geothermal energy, oil field resources and the environment.

[0034] (4) The method of the present invention does not require the use of nanofiltration membranes or other steps to pre-treat the adsorption raw materials. On the one hand, it avoids the high investment cost and energy consumption cost of nanofiltration membranes, and on the other hand, it ensures the high yield characteristics of adsorption lithium extraction as a direct lithium extraction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a diagram showing the adsorption performance of aluminum-based adsorbents in treating high-sulfate intercrystalline brine at different acidities.

[0036] Figure 2 This is the operating effect diagram of the adsorption performance of aluminum-based adsorbents fed with high sulfate intercrystalline brine without acid adjustment.

[0037] Figure 3 This is the operating effect diagram of the adsorption performance of aluminum-based adsorbents in treating ultra-high sulfate desodium brine (including acid adjustment).

[0038] Figure 4 This is an operating effect diagram of the adsorption performance of aluminum-based adsorbents in treating ultra-high sulfate-de-sodium brine (containing magnesium chloride regeneration).

[0039] Figure 5 This is a diagram showing the adsorption performance of aluminum-based adsorbents in treating high-boron, high-organic brine (including acid adjustment).

[0040] Figure 6 This is the operating effect diagram of the adsorption performance of aluminum-based adsorbents in treating high-boron, high-organic brine (including acid adjustment & chlorination disinfection).

[0041] Figure 7 This is the operating effect diagram of the adsorption performance of aluminum-based adsorbents in treating high-boron, high-organic brine (acid adjusted & unsterilized).

[0042] Figure 8 This is an operating effect diagram of the adsorption performance of magnetic aluminum-based adsorbent particles in treating high-sulfate intergranular brine (including ozone disinfection). DETAILED DESCRIPTION

[0043] The present invention is further described in detail below with reference to the embodiments, but the protection scope is not limited thereto.

[0044] Example 1

[0045] This example is used to illustrate the adsorption effect of aluminum-based adsorbents after acid adjustment when treating high-sodium and high-sulfate salt lake brine.

[0046] The raw material is the intercrystalline brine of a high sulfate salt lake, which contains 0.48g / L lithium, 105g / L sodium, 8.9g / L potassium, 14.7g / L magnesium, 0.19g / L calcium, 0.59g / L boron, 45.8g / L sulfate, 181g / L chloride, 50mg / L TOC, and pH 6.96. The SO4 / Cl (w / w, mass ratio, the same below) of the intercrystalline brine is 0.253, B / Li is 1.23, and SO4 / Li is as high as 95.4. 30 columns are used for continuous ion exchange treatment, in which 15.0L of aluminum adsorbent (LiAl-LDH) particles are loaded.

[0047] 31% concentrated hydrochloric acid was used to adjust the acidity of the raw material, and the pH of the raw material was adjusted to 6.0. RO water (pH=7.0) was used for desorption, and the desorbed water with a volume fraction of 20.8% (TDS about 5.8g / L) was eluted at a flow rate of 5.28BV / h to wash the saturated adsorption column; 0.40BV volume of adsorption tail liquid was used to reversely replace the desorbed adsorption column, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was reused as desorption inlet water in the desorption process; adsorption-desorption was carried out at 17-18°C and operated for 12 cycles. The average lithium concentration of the obtained qualified solution was 0.580g / L, the average desorption rate of the adsorbent was 91.9%, and the average working capacity was 1.502g / L, and the desorption was not sufficient.

[0048] The pH of the raw material was then adjusted to 5.0, and the pH of the RO water used for desorption was adjusted to 5.1, and the pH of the elution water was adjusted to 4.8. The desorption effluent with a volume fraction of 20.9% was used as the elution water (TDS about 6.0g / L) to elute the saturated adsorption column at the same elution flow rate; the adsorption column after desorption was reversely replaced with 0.42BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was reused as desorption inlet water in the desorption process; adsorption-desorption was carried out at 17-18°C and operated for 33 cycles. The desorption rate was close to 100%, the working capacity was stabilized to about 2.5g / L, and the adsorption-desorption basically reached a dynamic equilibrium.

[0049] The desorbed water was kept in the qualified liquid buffer tank and the leaching water buffer tank for an average of more than 8 hours. During operation, a small amount of white floccules were found in the qualified liquid buffer tank, the leaching liquid buffer tank, and the top water discharge pipeline.

[0050] Sampling analysis under two conditions, the operating results are shown in Figure 1 The operating data show that under the conditions of SO4 / Cl up to 0.253 and SO4 / Li up to 95.4 in the raw materials, the adsorption-desorption dynamic equilibrium of the adsorbent can be achieved by adjusting the acid to pH 4.5-5.0. Among them, the unit consumption of 31% industrial hydrochloric acid is 0.75L / m 3 Raw brine or 440L / ton lithium carbonate, with lower cost.

[0051] Comparative Example 1

[0052] This comparative example is used to compare the adsorption effect of aluminum-based adsorbents without acid adjustment when treating high-sodium and high-sulfate salt lake brine.

[0053] The same intercrystalline brine was treated with a continuous ion exchange device equipped with the same adsorbent as in Example 1, and the pH of the raw material was 6.96.

[0054] Direct feed without acid adjustment, use RO water (pH=7.0) for desorption, use the desorption effluent with a volume fraction of 38.7% as elution water (TDS about 5.6g / L) to elute the saturated adsorption column at a flow rate of 5.30BV / h; use 0.42BV of adsorption tail liquid to reversely replace the adsorption column after desorption, push out the pure water remaining in the adsorption column to obtain reverse top water, and reuse the reverse top water as desorption inlet water in the desorption process; the adsorption feed is 17-18℃, the desorption inlet water is heated to 35℃, and run for 20 cycles.

[0055] This conditional sampling analysis, the running effect is shown in Figure 2 When the SO4 / Cl ratio in the raw material was as high as 0.253 (SO4 / Li as high as 95.4) and the acid was not adjusted, the desorption rate dropped rapidly from 95% to 66%, and the adsorption rate dropped from 97% to 18%. Its working capacity dropped rapidly from 2.56 to 0.34 g / L, indicating that the adsorbent had been poisoned and basically lost its activity. Heating the desorption step to increase the desorption rate did not work.

[0056] Comparative Example 2

[0057] This comparative example is used to compare the adsorption effect of aluminum-based adsorbents regenerated with high-concentration magnesium chloride solution when treating high-sodium and high-sulfate salt lake brine.

[0058] The same intercrystalline brine was treated using the same continuous separation device equipped with the same adsorbent as in Example 1.

[0059] The raw material was fed directly without acid adjustment, and RO water (pH=7.0) was used for desorption. The desorption effluent with a volume fraction of 22.5% (TDS about 7.5g / L) was used as elution water to elute the regenerated adsorption column at a flow rate of 5.30BV / h; the elution water entered the regeneration liquid buffer tank, and 25% of bischofite (MgCl2˙6H2O) solution was added to it and mixed evenly as regeneration water, which passed through the saturated adsorption column at a flow rate of 6.70BV / h; the desorbed adsorption column was reversely replaced with 0.45BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was reused as desorption inlet water in the desorption process. Adsorption-regeneration-elution-desorption was carried out at 5-10℃ and operated for 39 cycles. The average lithium concentration of the obtained qualified solution was 0.747 g / L, the average desorption rate of the adsorbent was 91%, the average working capacity was 2.115 g / L, and the adsorption-desorption was close to dynamic equilibrium.

[0060] The data show that when the SO4 / Cl ratio in the raw material is as high as 0.253 (SO4 / Li as high as 95.4), the adsorption-desorption dynamic equilibrium of the adsorbent can be basically achieved by adding high-concentration magnesium chloride for regeneration. However, the unit consumption of industrial-grade magnesium chloride is 19.9 tons per ton of lithium carbonate, and the cost is difficult to control.

[0061] Example 2

[0062] This example is used to illustrate the adsorption effect of aluminum-based adsorbents for acid adjustment when treating ultra-high sulfate lake brine.

[0063] The sodium-removed brine of a salt field was used as the raw material, which contained 1.92g / L lithium, 48g / L sodium, 28.9g / L potassium, 48g / L magnesium, 0.047g / L calcium, 3.16g / L boron, 81g / L sulfate, 188g / L chloride, 210mg / L TOC, and pH 6.2. The SO4 / Cl ratio of the intercrystalline brine was as high as 0.432, B / Li was 1.65, and SO4 / Li was 42.3. 30 columns were used for continuous ion exchange treatment, in which 15.0L of aluminum adsorbent (LiAl-LDH) particles were installed as in Example 1.

[0064] 31% concentrated hydrochloric acid was used to adjust the acidity of the raw material, and the pH of the raw material was adjusted to 4.6, and the pH of the RO water used for desorption was adjusted to 5.0. The desorption effluent with a volume fraction of 22.4% (TDS of about 8.5g / L) was used as the elution water, and its pH was first adjusted to 4.8, and then the saturated adsorption column was eluted at a flow rate of 5.28BV / h; the adsorption column after desorption was reversely replaced with 0.48BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was used as desorption inlet water for the desorption process; adsorption-desorption was carried out at 11-12℃ and operated for 31 cycles. The average lithium concentration of the obtained qualified solution was 0.736g / L, the average desorption rate of the adsorbent was 99%, the average working capacity was 2.123g / L, and the adsorption-desorption basically reached a dynamic equilibrium.

[0065] The operating effect under this acid adjustment condition is shown in Figure 3 The data show that under the conditions of SO4 / Cl ratio of 0.432 and high TOC in the raw material, the adsorption-desorption dynamic equilibrium of the adsorbent can be achieved by adjusting the acid to pH 4.6-5.0. The unit consumption of 31% industrial hydrochloric acid is 7.7L / m 3 Original brine or 1.13m 3 / ton of lithium carbonate, with lower cost.

[0066] Comparative Example 3

[0067] This comparative example is used to compare the adsorption effect of aluminum-based adsorbents regenerated with high-concentration magnesium chloride solution when treating ultra-high sulfate salt lake brine.

[0068] The same desodiumated brine was treated using a continuous deionization device equipped with the same adsorbent as in Example 2.

[0069] The raw material was fed directly without acid adjustment, and RO water (pH=7.0) was used for desorption. The desorption effluent with a volume fraction of 23.5% (TDS about 8.5g / L) was used as elution water to elute the regenerated adsorption column at a flow rate of 4.86BV / h; the elution water entered the regeneration liquid buffer tank, and 25% of bischofite (MgCl2˙6H2O) solution was added to it and mixed evenly as regeneration water, which passed through the saturated adsorption column at a flow rate of 6.66BV / h; the desorbed adsorption column was reversely replaced with 0.51BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was reused as desorption inlet water in the desorption process. Adsorption-regeneration-elution-desorption was carried out at 11-12℃ and operated for 30 cycles. The average lithium concentration of the obtained qualified solution was 0.732 g / L, the average desorption rate of the adsorbent was 95%, the average working capacity was 2.151 g / L, and the adsorption-desorption was close to dynamic equilibrium.

[0070] The operating effect of the magnesium chloride solution under regeneration conditions is shown in Figure 4The data show that under the conditions of SO4 / Cl as high as 0.432 and high TOC in the raw material, by adding high-concentration magnesium chloride regeneration, the adsorption-desorption dynamic equilibrium of the adsorbent can be basically achieved, but the unit consumption of industrial-grade magnesium chloride is 16.5 tons / ton of lithium carbonate, which is too costly.

[0071] Example 3

[0072] This example is used to illustrate the adsorption effect of aluminum-based adsorbents for acid adjustment when treating high-boron, high-organic brine.

[0073] The raw material is a tail halogen extracted from a salt lake, which contains 0.746g / L lithium, 0.416g / L sodium, 0.088g / L potassium, 45.7g / L magnesium, 0.048g / L calcium, 3.16g / L boron, 10.52g / L sulfate, 126.7g / L chloride, 390mg / L TOC, and pH 6.9. The organic matter content of the tail halogen extracted from lithium is 390mg / L TOC, the B / Li mass ratio is 4.4, and SO4 / Li is 14.1. 30 columns are used for continuous ion exchange treatment, in which 15.0L of aluminum adsorbent (LiAl-LDH) particles are installed as in Example 1.

[0074] 31% concentrated hydrochloric acid was used to adjust the acidity of the raw material, and the pH of the raw material was adjusted to 4.9, and the pH of the RO water used for desorption was adjusted to 5.0. The desorption effluent with a volume fraction of 22.4% (TDS about 10.5g / L) was used as the elution water, and then the saturated adsorption column was eluted at a flow rate of 4.80BV / h; the adsorption column after desorption was reversely replaced with 0.50BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was used as desorption inlet water for the desorption process; adsorption-desorption was carried out at 1-6℃ and operated for 32 cycles. The average lithium concentration of the obtained qualified solution was 0.727g / L, the average adsorption rate of the adsorbent was 93%, the average desorption rate was 102%, the average working capacity was 1.940g / L, and the adsorption-desorption was close to reaching dynamic equilibrium.

[0075] The operating effect under this acid adjustment condition is shown in Figure 5 The data show that under the conditions of B / Li as high as 4.4 and high organic content (TOC=390mg / L) in the raw material, the adsorption-desorption process can be stably operated by adjusting the raw material acid to pH 4.9. The unit consumption of 31% industrial hydrochloric acid is 11.1L / m 3 Tail brine or 3.98m 3 / ton of lithium carbonate, the acid consumption cost is controllable.

[0076] Comparative Example 4

[0077] This comparative example is used to illustrate the adsorption effect of aluminum-based adsorbents when treating high-boron, high-organic brine with unadjusted acid raw materials.

[0078] The same lithium extraction tail brine in Example 3 was used as raw material and treated with the same continuous ion exchange device equipped with the same aluminum-based adsorbent. The lithium extraction tail brine was directly fed at pH 6.9, and no acid adjustment was performed in the adsorption, elution, desorption, and top water steps. The desorption effluent with a volume fraction of 22% was used as elution water, and then the saturated adsorption column was eluted at a flow rate of 4.20BV / h; the adsorption column after desorption was reversely replaced with 0.53BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, and the reverse top water was used as desorption inlet water for the desorption process; the adsorption-desorption was carried out at 1-6°C, and two cycles were run. The lithium content in the adsorption tail liquid was 0.372g / L, the adsorption rate was only 38%, the working capacity of the adsorbent was only 1.01g / L, and the lithium content in the tail liquid continued to increase, and the adsorption rate continued to decrease. This indicates that the adsorbent has been contaminated or poisoned.

[0079] After the continuous desorption device was cleaned and activated with pure water, a regeneration step was added before the elution step, and 293g / L MgCl2 solution was used for regeneration. After two cycles, the lithium content in the adsorption tail liquid reached 0.313g / L, the adsorption rate was only 47.8%, and the working capacity was only 1.06g / L, indicating that the use of high-concentration magnesium chloride solution for regeneration cannot solve the problem of adsorbent contamination or poisoning.

[0080] Example 4

[0081] This example is used to illustrate the operating effect of an aluminum-based adsorbent that is acidified and chlorinated when treating high-boron, high-organic brine.

[0082] The raw materials used in the experiment for lithium extraction were the same as those in Example 3. A 30-column continuous ion exchange device was used for treatment, in which 33.0 L of aluminum-based adsorbent (LiAl-LDH) particles as in Example 1 were loaded.

[0083] 31% concentrated hydrochloric acid was used to adjust the acidity of the raw material, and the pH of the raw material was adjusted to 5.0. At the same time, the pH of the RO water used for desorption was adjusted to 5.0. The obtained desorption effluent (TDS about 11.1g / L) was first disinfected with sodium hypochlorite, and the concentration of sodium hypochlorite added was 5mg / L. After 10 minutes of reaction, the residual chlorine in the desorption effluent was tested to be 0.2mg / L. The desorption effluent with a volume fraction of 18.5% after disinfection was used as elution water, and then 1.2mg / L of sodium hypochlorite was added to it, and then the saturated adsorption column was eluted at a flow rate of 4.86BV / h; the adsorption column after desorption was reversely replaced with 0.49BV of adsorption tail liquid, and the pure water remaining in the adsorption column was pushed out to obtain reverse top water, which was reused as desorption inlet water in the desorption process; adsorption-desorption was carried out at 21-29℃ and operated for 169 cycles. The average lithium concentration of the qualified solution was 0.87g / L, the average adsorption rate of the adsorbent was 99.9%, the average desorption rate was 101%, the average working capacity was 3.132g / L, and the adsorption-desorption basically reached a dynamic balance. The desorption effluent after chlorination disinfection was taken and tested with a bacterial test piece. No colonies were generated after 48 hours of incubation.

[0084] The effect of the operation under the conditions of acid adjustment and chlorination disinfection is shown in Figure 6 . The data show that under the conditions of B / Li as high as 4.4 and extremely high organic content (TOC=390mg / L) in the raw material, by adjusting the raw material to pH 5.0 and disinfecting the desorption and elution steps, the adsorption-desorption process can be operated stably, and no obvious colloid or flocculent is generated in the adsorption system. Therefore, the pressure and flow of the adsorption system are stable, and the Mg / Li and B / Li of the obtained qualified liquid fluctuate little. On this basis, sodium bisulfite is used to remove the residual chlorine in the qualified liquid, and the NaHSO3 dosage is 0.7mg / L. After 5 minutes of reaction, the residual chlorine in the qualified liquid is tested to be 0.03mg / L, which meets the reverse osmosis influent water quality requirements.

[0085] Through the above measures, the unit consumption of 31% industrial hydrochloric acid is 11.0L / m 3 Tail brine or 3.94m 3 / ton of lithium carbonate, the acid consumption cost is controllable; the consumption of sodium hypochlorite is only 1.8kg / ton of lithium carbonate; the consumption of sodium sulfite is only 0.25kg / ton of lithium carbonate.

[0086] Comparative Example 5

[0087] This comparative example is used to illustrate the adsorption effect of aluminum-based adsorbents when treating high-boron, high-organic brine by acidifying the raw materials but not disinfecting them in the leaching and desorption steps.

[0088] The same lithium extraction tail brine from Example 4 was used as raw material and treated by the same continuous ion exchange device equipped with the same aluminum-based adsorbent.

[0089] First, the pH of the raw material is adjusted to 5.0, and the pH of the RO water used for desorption is adjusted to 5.0. Adsorption-desorption is carried out at 21-29°C. Because the desorption rate is relatively fast, the amount of RO water used for desorption can be controlled at a low level, and the eluted adsorption column is desorbed at a flow rate of 16.8-20.4BV / h. The TDS of the desorbed water is 14-28g / L, and it stays in the qualified liquid buffer tank and the elution water buffer tank for an average of more than 8 hours. The desorbed water with a volume fraction of 27.0% is used to elute the saturated adsorption column at a flow rate of 4.98BV / h; the adsorption column after desorption is reversely replaced with 0.55BV of adsorption tail liquid, and the pure water remaining in the adsorption column is pushed out to obtain reverse top water, which is reused as desorption inlet water in the desorption process. During operation, it was found that flocs were generated in the desorption discharge pipeline, qualified liquid buffer tank, eluent buffer tank, and eluent inlet and outlet pipelines, which blocked the filter screen at the adsorption column head, causing the pressure of the adsorption system to rise, the flow rate to fluctuate greatly, and the impurity content of the qualified liquid to fluctuate greatly. After cleaning the flocs and adjusting the acidity and flow rate of the desorption inlet water and eluent, the floc generation problem could not be effectively avoided.

[0090] The operation was continued for 79 cycles under this condition. The operation effect is shown in Figure 7 .

[0091] Example 5

[0092] This example is used to illustrate the adsorption effect of the magnetic doped aluminum-based adsorbent disinfected in the desorption and elution steps when treating high-sodium and high-sulfate salt lake brine.

[0093] The same continuous ion exchange device as in Example 1 was used to treat the same intercrystalline brine, wherein 15 L of magnetic aluminum adsorbent (Fe3O4@LiAl-LDH) particles doped with Fe3O4 nanoparticles were loaded, and the pH of the raw material was 6.96.

[0094] Feed directly without acid adjustment, desorb with RO water (pH=7.0), use 0.60BV volume of adsorption tail liquid to reversely replace the adsorption column after desorption, push out the pure water remaining in the adsorption column, obtain reverse top water, and use the reverse top water as desorption inlet water for desorption process; adsorption-desorption is carried out at 22-29℃, and runs for 38 cycles. The desorption inlet water is first disinfected with an ozone disinfector to make the ozone concentration reach 2mg / L; the desorption effluent with a volume fraction of 34.6% (TDS about 8.2g / L) is further disinfected with an ozone machine to make the ozone concentration reach 10mg / L, and then the saturated adsorption column is eluted at a flow rate of 6.60BV / h.

[0095] The average lithium concentration of the qualified solution was 0.874 g / L, the average adsorption rate of the adsorbent was 99.9%, the average desorption rate was 99.2%, the average working capacity was 1.814 g / L, and the adsorption-desorption basically reached a dynamic balance. The desorption effluent after ozone disinfection was taken and tested with a bacterial test piece. No colonies were generated after 48 hours of cultivation.

[0096] The effect of running under ozone disinfection but without acid adjustment is shown in Figure 8 The results show that under the conditions of SO4 / Li as high as 95.4 and TOC of about 50 mg / L in the raw material, the adsorbent particles doped with Fe3O4 nanoparticles can achieve long-term stable operation after ozone disinfection, and no obvious colloid or flocculent is generated in the adsorption system. Therefore, the pressure and flow of the adsorption system are stable, and the Mg / Li and B / Li of the obtained qualified liquid fluctuate little.

[0097] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for preventing pollution and poisoning during lithium extraction by aluminum-based adsorbents, characterized in that: include, Step 1, acid adjustment: using lithium-containing brine as raw material, adding inorganic acid to the raw material to adjust the pH; Step 2, adsorption: the acid-adjusted raw material is loaded into the adsorption stock solution tank, and then pumped into the adsorption system filled with aluminum adsorbent until adsorption saturation is achieved. The adsorption effluent obtained is the adsorption tail liquid; Step 3, elution: using a lithium salt solution as elution water to wash away brine impurities in the saturated adsorption column to obtain an eluent, and the obtained eluent is recycled to the adsorption raw material tank; Step 4, desorption: using pure water as desorption inlet water to elute the adsorption column after elution to obtain desorption effluent water; Step 5, top water: use 0.4-0.6 BV volume of adsorption tail liquid in step 2 to reversely replace the adsorption column after desorption, push out the pure water remaining in the adsorption column, and obtain reverse top water. The obtained reverse top water is used as desorption inlet water for the desorption process; Step 6, disinfection: disinfect the desorbed water obtained in step 4, and use the desorbed water with a volume fraction of 15% to 40% after disinfection as elution water for the elution process, and the remaining desorbed water is the qualified liquid.

2. The method for preventing pollution and poisoning during lithium extraction by aluminum-based adsorbent according to claim 1, characterized in that: The lithium-containing brine described in step 1 also contains one or more mixed components of sulfate, borate or organic matter.

3. The method for preventing pollution and poisoning during lithium extraction with aluminum-based adsorbents according to claim 1, characterized in that: The inorganic acid described in step 1 is hydrochloric acid, sulfuric acid or nitric acid, and the inorganic acid is added to the raw material to adjust the pH to 4.5-7.

0.

4. The method for preventing pollution and poisoning during lithium extraction with aluminum-based adsorbents according to claim 1, characterized in that: The TDS of the elution water in step 3 is controlled within the range of 5.5 to 30 g / L, and the flow rate of the elution water is 4.0 to 6.7 BV / h.

5. The method for preventing pollution and poisoning during lithium extraction with aluminum-based adsorbents according to claim 1, characterized in that: The adsorption tail liquid described in step 5 adopts a reverse replacement method from bottom to top.

6. The method for preventing pollution and poisoning during lithium extraction with aluminum-based adsorbents according to claim 1, characterized in that: The disinfection treatment described in step 6 is carried out using an ozone generator, wherein the ozone concentration is 0.1 to 10 mg / L and the pH is adjusted to 4.5 to 7.

0.

7. The method for preventing pollution and poisoning during lithium extraction with aluminum-based adsorbents according to claim 1, characterized in that: The disinfection treatment described in step 6 adopts the addition of hypochlorous acid or hypochlorite for disinfection, the concentration of oxidizing chlorine is 0.02-5.0 mg / L, and the pH is adjusted to 4.5-7.

0.

8. The method for preventing pollution and poisoning during lithium extraction with aluminum-based adsorbents according to claim 1, characterized in that: Step 6 also includes removing residual chlorine from the qualified liquid using sodium bisulfite or sodium sulfite, and the end point of removing residual chlorine is that the residual chlorine content is less than 0.1 mg / L.

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