A method for preparing a lithium-rich liquid ore from calcium chloride-type deep brine

Abstract

The present invention discloses a method for preparing lithium-rich liquid ore from calcium chloride type deep brine, belonging to the technical field of brine development and utilization. The preparation of lithium-rich liquid ore from calcium chloride type deep brine comprises the following steps: preliminarily concentrating the calcium chloride type deep brine, adding a solution containing sodium sulfate, stirring evenly, and then evaporating and concentrating under natural conditions to obtain the lithium-rich liquid ore. By removing calcium when the brine is not yet saturated, then naturally evaporating and concentrating until the lithium ions reach a certain concentration and then performing lithium extraction operations, the present invention not only greatly reduces the calcium-lithium ratio, but also improves the salt field (evaporation) recovery rate of lithium. At the same time, it can also improve the salt field recovery rate of potassium and the quality of potassium salt ore.

Description

Technical Field

[0001] The present invention relates to the technical field of development and utilization of brine, and particularly to a method for preparing lithium-rich liquid ore from calcium chloride type deep brine. Background Art

[0002] At present, there are few studies on extracting lithium from unsaturated calcium chloride type deep brine. Existing technologies all first concentrate the brine to varying degrees and then extract lithium, without performing calcium removal or impurity removal operations in the early stage of concentration. And there has always been a difficult problem: when extracting lithium from low-concentration brine with a small concentration multiple, although the salt field (evaporation) recovery rate of lithium is relatively high, the amount of brine to be treated is large and the utilization of potassium is difficult; when extracting lithium from high-concentration brine after potassium precipitation, the loss of lithium in the form of mother liquor entrainment by the salt precipitated during the evaporation process is very large, and the calcium content in the concentrated brine is still high. The workload of calcium removal in the later lithium extraction process with a high content of calcium ions is large, the cost is high, and the lithium loss is large. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing lithium-rich liquid ore from calcium chloride type deep brine to solve the problems existing in the above-mentioned prior art. By removing calcium when the brine is not yet saturated and then naturally evaporating and concentrating until the lithium ion reaches a certain concentration and then performing lithium extraction operations, the calcium-lithium ratio is greatly reduced, the salt field (evaporation) recovery rate of lithium is improved, and the quality of potassium salt ore can also be improved.

[0004] To achieve the above purpose, the present invention provides the following scheme: A method for preparing lithium-rich liquid ore from calcium chloride type deep brine, comprising the following steps:

[0005] Preliminarily concentrate the calcium chloride type deep brine to obtain concentrated brine, add a solution containing sodium sulfate to the concentrated brine, stir evenly, and then evaporate and concentrate under natural conditions to obtain lithium-rich liquid ore.

[0006] In the lithium-rich liquid ore, Ca / Li is 0.25 - 0.50, Mg / Li is 20 - 30, and Li + concentration > 0.15 wt.%.

[0007] Furthermore, the calcium chloride type deep brine is low-mineralization and unsaturated lithium extraction raw brine at a depth of 2000 - 3000 m underground in the Qaidam Basin.

[0008] Further, in the calcium chloride type deep brine, Ca / Li is 50 - 250, Mg / Li is 20 - 30, and Li + concentration > 0.002 wt.%.

[0009] Further, the preliminary concentration is carried out until the brine density is 1.15 - 1.18 g / mL.

[0010] Furthermore, the concentrated brine is brine that is not yet saturated.

[0011] Adding a solution containing sodium sulfate to unsaturated brine can cause most of the calcium ions to precipitate first in the form of gypsum and then sodium chloride. The separation of gypsum is + When the concentration is very low, it can reduce its effect on Li + The amount of entrainment loss.

[0012] Furthermore, the solution containing sodium sulfate includes sodium sulfate subtype brine or thenardite solution; the preparation of the thenardite solution specifically includes: adding industrial thenardite into water at a temperature of 25 to 40° C., stirring and dissolving, to obtain the thenardite solution.

[0013] Furthermore, the mass ratio of the industrial sodium sulfate to water is 1:(2.5-6), and the amount of water added is calculated according to the solubility of sodium sulfate at different temperatures.

[0014] Furthermore, the effective content of Na2SO4 in the industrial sodium sulfate is ≥99.0%.

[0015] Furthermore, the Ca in the calcium chloride type deep brine 2+ The amount of substance minus the SO4 in calcium chloride deep brine 2- The amount of substance in a solution containing sodium sulfate is equal to the amount of substance Na2SO4 in a solution containing sodium sulfate.

[0016] Furthermore, the method for preparing lithium-rich liquid ore from calcium chloride-type deep brine also includes solid-liquid separation during the evaporation and concentration process.

[0017] When the amount of precipitated salt is relatively large during evaporation and concentration, solid-liquid separation can be carried out. The number of solid-liquid separations is determined according to the amount of precipitated salt and the concentration degree of brine. As the lithium ion concentration in the brine increases, the separation time interval is shortened. The amount of precipitated salt in each separation should not be more than 1 / 4 of the brine.

[0018] As the brine concentrates, Ca 2+ The total amount is constantly decreasing, and the precipitation reaction is ongoing throughout the entire process of brine concentration.

[0019] The magnesium content in calcium chloride deep brine is low and the calcium content is high. A large amount of calcium tends to increase the viscosity of the brine in the later stage of evaporation and concentration, resulting in a large amount of entrainment loss of the brine. High calcium brine tends to crystallize CaCl2·6H2O in the later stage. This salt crystallizes at low temperature (<10.0℃) and dissolves at high temperature. The brine concentrates very slowly, making it difficult to enrich lithium. After removing calcium in the early stage and then concentrating, a lithium-rich liquid ore with low calcium, low magnesium and high lithium is obtained, which improves the comprehensive utilization efficiency of deep brine.

[0020] The present invention discloses the following technical effects:

[0021] (1) The method for preparing lithium-rich liquid ore of the present invention can avoid the problems of high brine viscosity and large entrainment loss of brine caused by high calcium concentration in the later stage of concentration, and can also improve the salt field recovery rate of potassium and the quality of potassium salt ore.

[0022] (2) When a solution containing sodium sulfate is added to the calcium chloride-type deep brine (raw brine) before it is saturated in the present invention, most of the calcium ions can be precipitated in the form of gypsum first and then sodium chloride is precipitated. The separation of gypsum is carried out when the Li + concentration is very low, which can reduce its entrainment loss to Li + .

[0023] (3) In the prior art, calcium removal is generally carried out when Ca 2+ ≥ 4.0 wt.%, while in the present invention, calcium removal can be carried out when Ca 2+ ≥ 1.02 wt.%, avoiding the problems of high brine viscosity and large entrainment loss of brine caused by high calcium concentration in the later stage of concentration.

[0024] (4) Using the same brine for lithium enrichment, the enrichment degree of lithium in the brine after calcium removal can reach more than 0.167 wt.%; when not removing calcium, when the Li + concentration is 0.078 wt.%, the brine density has reached 1.441 g / mL, the brine viscosity is large, and it is very difficult to continue concentration.

[0025] (5) When the brine after calcium removal in the present invention is enriched to a Li + concentration of 0.167 wt.%, the salt field yield of lithium is 64.32%; when the brine without calcium removal is enriched to a Li + concentration of 0.078 wt.%, the salt field yield of lithium is 65.84%. In comparison, when concentrated to the same lithium concentration, the yield of the brine after calcium removal has an obvious advantage (see Tables 2 and 3 for data).

[0026] (6) The calcium content in the calcium chloride-type deep brine used in the present invention is much higher than the magnesium content. In the later stage of evaporation, when the calcium concentration in the brine is high (without calcium removal), antarcticite will crystallize at night and dissolve during the day with the change of day and night temperature difference, showing a solid-liquid mixed state, which is difficult for solid-liquid separation and the concentration is very slow. After calcium removal, the calcium and magnesium contents in the brine are low, the brine viscosity is relatively low in the later stage of evaporation, and the concentration speed is fast and the cycle is short. Detailed Embodiments

[0027] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention.

[0028] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0030] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are merely exemplary.

[0031] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0032] The calcium chloride type deep brine used in the following examples of the present invention is a low salinity and unsaturated lithium extraction raw material brine at a depth of 2000 - 3000 m underground in the Qaidam Basin. In the brine, the Ca / Li is 50 - 250, the Mg / Li is 20 - 30, and the Li + concentration > 0.002 wt.%.

[0033] The mirabilite used in the following examples of the present invention is industrial mirabilite, and the effective content of Na2SO4 in the mirabilite ≥ 99.0%.

[0034] Example 1

[0035] A method for preparing lithium-rich liquid ore from calcium chloride type deep brine:

[0036] (1) Take 200.00 kg of calcium chloride type deep brine (raw brine, the mass percentage concentration ratio of Ca / Li is 206.0, the mass percentage concentration ratio of Mg / Li is 29.5, and Li +with a concentration of 0.0027 wt.%, concentrated to 93.42 kg under natural conditions (brine density 1.162 g / mL, salinity 245.75 g / L, Ca 2+ content is 1.02 wt.%) to obtain concentrated brine (brine before calcium removal).

[0037] (2) Preparation of sodium sulfate solution: Add 3.79 kg of sodium sulfate to 18.97 kg of water (at a temperature of 30.0 °C), stir and dissolve to obtain a sodium sulfate solution.

[0038] (3) Add the sodium sulfate solution to the concentrated brine, stir evenly, and then evaporate and concentrate under natural conditions. When the amount of precipitated salt is relatively large (the amount of precipitated salt during each separation should not be more than 1 / 4 of the brine volume), perform solid-liquid separation 3 times in total to obtain 2.09 kg of lithium-rich liquid ore, precipitate 21.01 kg of salt, and the water loss and loss are 199.66 kg.

[0039] Example 2

[0040] A method for preparing lithium-rich liquid ore from calcium chloride-type deep brine:

[0041] (1) Take 200.00 kg of calcium chloride-type deep brine (raw brine, the mass percentage concentration ratio of Ca / Li is 206.0, the mass percentage concentration ratio of Mg / Li is 29.5, Li + with a concentration of 0.0027 wt.%, concentrated to 93.42 kg under natural conditions (brine density 1.162 g / mL, salinity 245.75 g / L, Ca 2+ content is 1.02 wt%) to obtain concentrated brine (brine before calcium removal).

[0042] (2) Preparation of sodium sulfate solution: Add 3.79 kg of sodium sulfate to 18.97 kg of water (at a temperature of 30.0 °C), stir and dissolve to obtain a sodium sulfate solution.

[0043] (3) Add the sodium sulfate solution to the concentrated brine, stir evenly, and then evaporate and concentrate under natural conditions. When the amount of precipitated salt is relatively large (the amount of precipitated salt during each separation should not be more than 1 / 4 of the brine volume), perform solid-liquid separation 3 times in total to obtain 2.11 kg of lithium-rich liquid ore, precipitate 21.47 kg of salt, and the water loss and loss are 199.18 kg.

[0044] Example 3

[0045] A method for preparing lithium-rich liquid ore from calcium chloride-type deep brine:

[0046] (1) Take 634.00 kg of calcium chloride-type deep brine (raw brine, the mass percentage concentration ratio of Ca / Li is 206.0, the mass percentage concentration ratio of Mg / Li is 29.5, and the Li + concentration is 0.0027 wt.%). Concentrate it to 296.15 kg under natural conditions (brine density 1.162 g / mL, salinity 245.75 g / L, and Ca 2+ content is 1.02 wt.%) to obtain concentrated brine (brine before calcium removal).

[0047] (2) Preparation of sodium sulfate solution: Add 12.02 kg of sodium sulfate to 60.12 kg of water (temperature 30.0 °C), stir and dissolve to obtain a sodium sulfate solution.

[0048] (3) Add the sodium sulfate solution to the concentrated brine, stir evenly, and then evaporate and concentrate under natural conditions. When the amount of precipitated salt is relatively large during this period (the amount of precipitated salt during each separation should not be more than 1 / 4 of the brine volume), perform solid-liquid separation 3 times in total to obtain 6.67 kg of lithium-rich liquid ore, precipitate 67.62 kg of salt, and the water loss and loss are 631.85 kg.

[0049] The test material tables of Examples 1 to 3 are shown in Table 1.

[0050] Table 1 Test material table

[0051] Group Example 1 Example 2 Example 3 Original brine volume 200.00 200.00 634.00 Brine volume before calcium removal 93.42 93.42 296.15 Industrial mirabilite 3.79 3.79 12.02 Water addition volume 18.97 18.97 60.12 Lithium-rich brine volume 2.09 2.11 6.67 Precipitated salt volume 21.01 21.47 67.62 Water loss and loss 199.66 199.18 631.85

[0052] Note: The unit of the dosage of substances in the table is kg.

[0053] During large-scale production in the salt field, before the calcium chloride-type deep brine is near saturation, add sodium sulfate subtype brine in proportion, and then evaporate and concentrate under natural conditions. When the amount of precipitated salt is relatively large during this period, perform solid-liquid separation, and the same effect as in Examples 1 to 3 can be achieved, and lithium-rich brine can be collected at different stages of Li + content. After calcium removal, the recovery rate of lithium extraction in the later stage can be improved, and at the same time, the process flow can be shortened and the cost can be reduced.

[0054] The summary tables of the calcium removal test results of Examples 1 to 3 are shown in Tables 2 to 3.

[0055] Table 2 Summary table of calcium removal test results

[0056]

[0057] Table 3 Summary table of calcium removal test results

[0058]

[0059] Comparative Example 1

[0060] Same as Example 1, with the only difference being that no mirabilite solution was added to the concentrated brine, and the concentrated brine was directly continued to be placed for evaporation and concentration under natural conditions. During this period, when the amount of precipitated salt was relatively large (the amount of precipitated salt should not be more than 1 / 4 of the brine volume each time of separation), solid-liquid separation was carried out 3 times in total.

[0061] Calcium removal was not carried out. After evaporation until the precipitation of potassium salts ended, the density of the brine was 1.441 g / mL. At this time, since the viscosity of the brine was relatively large, the phenomena of low-temperature crystallization and dissolution upon heating occurred, and solid-liquid separation was difficult, so evaporation was stopped.

[0062] The summary table of the test results of Comparative Example 1 is shown in Tables 4 - 5.

[0063] Table 4 Summary Table of Test Results without Calcium Removal

[0064]

[0065] Table 5 Summary Table of Test Results without Calcium Removal

[0066]

[0067] From the results in Tables 2 - 3 and Tables 4 - 5, it can be seen that when concentrated to a Li + concentration of about 0.042 wt.%, the Li 3-3 recovery rates of the two brines (21YX-L + , 21YD-L1) were both about 80%, with little difference. For the brine (21YD-L3) without prior calcium removal treatment, when concentrated to a Li + concentration of 0.078 wt.%, the density of the brine was 1.441 g / mL, and the viscosity of the brine was already very large. The Li + recovery rate was 65.84%. For the brine (21YX-L 3-4 ) after calcium removal, when concentrated to a Li + concentration of 0.167 wt.%, the density of the brine was 1.231 g / mL, and the Li + recovery rate was 64.32%. When the recovery rates of both were about 65% with little difference, the Li + concentration in the concentrated brine after calcium removal was 0.167 wt.%, Ca / Li = 0.26, and the Li + concentration in the brine without calcium removal was 0.078 wt.%, Ca / Li = 160.0. In comparison, after concentration of the brine with calcium removal, the enrichment effect, recovery rate, and Ca / Li of Li + were significantly better than those of the concentrated brine without calcium removal, and the recovery rate was also higher in the subsequent lithium extraction process.

Claims

1. A method for preparing a lithium-rich liquid ore from calcium chloride-type deep brine, characterized in that, It includes the following steps: After preliminarily concentrating the calcium chloride type deep brine, add a solution containing sodium sulfate, stir evenly, and then evaporate and concentrate under natural conditions to obtain a lithium-rich liquid ore; The Ca / Li in the calcium chloride type deep brine is 50 to 250, the Mg / Li is 20 to 30, and the Li + concentration > 0.002 wt.%; The preliminary concentration is carried out until the density of the brine is 1.15 - 1.18 g / mL; The solution containing sodium sulfate includes sodium sulfate subtype brine or mirabilite solution; the preparation of the mirabilite solution specifically includes: adding industrial mirabilite into water at a temperature of 25 - 30 °C, stirring and dissolving to obtain the mirabilite solution.

2. The method for preparing lithium-rich liquid ore from calcium chloride-type deep brine according to claim 1, characterized in that, The mass ratio of the industrial mirabilite to water is 1:(2.5 - 6).

3. The method for preparing lithium-rich liquid ore from calcium chloride-type deep brine according to claim 1, wherein The effective content of Na2SO4 in the industrial mirabilite is ≥99.0%.

4. The method for preparing lithium-rich liquid ore from calcium chloride-type deep brine according to claim 1, characterized in that, The amount of substance of Ca in the deep calcium chloride brine 2+ minus the amount of substance of SO4 in the deep calcium chloride brine 2- is equal to the amount of substance of Na2SO4 in the solution containing sodium sulfate.

5. The method for preparing lithium-rich liquid ore from calcium chloride type deep brine according to claim 1, characterized in that, It also includes solid-liquid separation during the evaporation and concentration process.

Images