A method for extracting rare element lithium from Bayer process sodium aluminate solution

Abstract

A method for enriching and extracting rare element lithium from sodium aluminate solution in an alumina plant. The method uses the excellent ion adsorption characteristics of layered aluminosilicate minerals to absorb and extract lithium dissolved in the Bayer mother liquor of the alumina plant based on the low dissolution loss of layered clay minerals in the sodium aluminate solution before seeding, and then uses organic acid to desorb the lithium-rich layered aluminosilicate minerals. The blank layered aluminosilicate minerals after desorption can be recycled for adsorption, and the lithium citrate solution can be directly used as a raw material for preparing lithium battery anodes. The method achieves high-efficiency, low-pollution, and low-cost extraction of lithium, and proposes a practical and feasible technical route for comprehensive resource utilization and improved economic benefits. The lithium production method proposed by the present invention is essentially different from the existing extraction method using spodumene and salt lake brine as raw materials. The source of lithium is the lithium resource associated with bauxite in the process of producing alumina by the Bayer process or sintering process, which is equivalent to a high-value-added product in alumina production.

Description

Technical Field

[0001] The invention relates to the field of resource and environmental technology, and in particular to a method for extracting rare element lithium from a Bayer process sodium aluminate solution. Background Art

[0002] Lithium is the core strategic metal for the construction of new energy. It is the metal with the most negative potential and the largest electrochemical equivalent. The battery composed of lithium has the highest specific energy, so it has a unique position in the field of new energy and the atomic energy industry. The demand for lithium batteries in China is strong, but the production of lithium carbonate in my country mainly adopts the solid ore extraction process, while the salt lake brine extraction process is limited by factors such as the difficulty of separating magnesium and lithium, and the development speed is relatively slow. The supply of lithium resources has become the biggest constraint on the development of China's lithium battery industry. Among the world's proven lithium resources, the South American Lithium Triangle (Bolivia, Argentina, Chile) accounts for 57%, followed by the United States with 10%, Australia with 8%, and China with only 6%.

[0003] my country's lithium resources are mainly salt lake brine and granite pegmatite, and sedimentary rocks are generally not used as target geological bodies for lithium search. However, the total amount of this type of mineral resources is huge, including bauxite, coal, and kaolin deposits, and has broad development prospects.

[0004] Li Suidang et al. invented a method for preparing a lithium adsorbing material, application number: CN201810379023.6. Based on the activity of lithium and its different characteristics in the solution, the N element is introduced into the functional group of the adsorption material, and nitrogen is used. The exchangeable sulfonic acid, phosphoric acid, and carboxylic acid functional groups can easily combine with lithium ions, so that lithium is exchanged on the material, while other monovalent ions are not exchanged, thereby achieving the purpose of enrichment and purification.

[0005] The "method for extracting lithium carbonate from sodium aluminate solution in an alumina plant, application number: CN201710883825.6" invented by Ma Haijun et al. is to add aluminum hydroxide seeds to the lithium-rich semen of the alumina plant to precipitate lithium. After lithium precipitation, high-lithium primary aluminum hydroxide (aluminum hydroxide) is separated from the semen, and the filter cake is countercurrently washed with hot water (generally, the filter cake is countercurrently washed 2 to 3 times with 1 to 3 times hot water) to obtain high-lithium primary aluminum hydroxide, and then the high-lithium primary aluminum hydroxide after hot water washing is leached by a hydrothermal method to transfer lithium back into the solution. After leaching, the slurry is separated again to obtain hydrated alumina and lithium-containing leachate, and the lithium-containing leachate is neutralized with inorganic acid and then a saturated sodium carbonate aqueous solution is added to crystallize the lithium carbonate.

[0006] "A method for reducing lithium content in alumina products, application number: CN201811609306.1" invented by Qi Lijuan et al. adds aluminum-containing compounds as adsorbents to the lithium-containing sodium aluminate solution to adsorb lithium in the sodium aluminate solution; controls the reaction temperature and stirring time of the solution to promote the precipitation of lithium in the solution; and obtains lithium-rich filter cake and filtrate through filtration; the filtrate enters the subsequent process of preparing alumina products.

[0007] my country's alumina production is large-scale, and the lithium resources associated with bauxite have not been reasonably utilized. The amount of Li2O carried away by metallurgical-grade alumina is as high as 15,000 to 20,000 tons each year. In addition, lithium-rich alumina will reduce current efficiency and increase energy consumption during aluminum electrolysis, leading to worsening of the electrolytic cell working conditions. Existing research on the comprehensive benefits of by-product lithium resources in alumina production systems is not reasonable enough, and the relevant technical defects are large. The lithium resources associated with bauxite have not yet been properly resolved. Summary of the invention

[0008] In order to better utilize the lithium resources produced as a byproduct of the alumina production system, the present invention provides a method for extracting rare element lithium from a sodium aluminate solution of the Bayer process, that is, using a dioctahedral layered aluminum silicate mineral with a 2:1 unit structure layer as a circulating adsorbent and citric acid as a desorbent, to achieve efficient extraction of lithium without changing the original Bayer process production process. The technical solution of the present invention is implemented in the following steps:

[0009] (1) Activating the layered aluminosilicate minerals (mechanical activation, thermal activation and chemical modification), and using the activated minerals as adsorbents for the scattered elements in the sodium aluminate solution;

[0010] (2) Adding activated aluminosilicate minerals (montmorillonite, chlorite, pyrophyllite, illite) to the sodium aluminate concentrate in the Bayer process to adsorb lithium, controlling the amount of mineral added to 1.5-15 g / L, the reaction temperature to 65-90 °C, and the reaction time to 0.5-6 h. After sufficient reaction, liquid-solid separation is performed, and the separated Bayer mother liquor continues to enter the seed separation process, and the filter cake is further processed to extract lithium;

[0011] (3) desorbing the hectorite-rich montmorillonite obtained in the previous step using an organic acid (citric acid);

[0012] (4) After desorption, the blank montmorillonite is returned to the adsorption process for recycling;

[0013] (5) The lithium citrate solution obtained in the desorption process is directly used as a raw material for preparing lithium battery anodes after impurity removal and conditioning.

[0014] Compared with the prior art, the characteristics and beneficial effects of the present invention are:

[0015] (1) Layered aluminosilicate minerals have low reactivity in the Bayer process mother liquor before seed separation, stable structure, and excellent ion adsorption properties. At the same time, aluminosilicate minerals will not have an adverse effect on the composition of the mother liquor, and can achieve efficient adsorption of lithium;

[0016] (2) The process steps are simple, and the lithium extraction rate is high, which can reach 90-95%. After lithium extraction, the mother liquor is purified, and the lithium content in the produced alumina product can be reduced to 0.05%, which can better meet the composition requirements of the aluminum electrolysis process;

[0017] (3) The desorption effect of citric acid is excellent, with a desorption rate of up to 88%. After desorption, the aluminosilicate minerals can be recycled and can maintain a high peak adsorption capacity. After five cycles of adsorption, the adsorption capacity is still 60~110 mmol / 100g. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the embodiments.

[0020] Example 1

[0021] Bayer process sodium aluminate solution concentration Na2O (N k ) = 160g / L, αk = 1.5, Li2O concentration 1g / L; liquid-to-solid ratio 200:1, temperature 90°C, add 1.5g of montmorillonite, stir for 360 minutes, filter to obtain rich hectorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium in the sodium aluminate solution is 92.80%.

[0022] After the hectorite is dried, it is desorbed with citric acid solution. The desorption conditions are: 25℃, concentration of 0.5 mol / L, liquid-solid ratio of 20:1, 1g of hectorite is added, and the reaction is carried out for 60 minutes. After that, liquid-solid separation is carried out, and the desorption rate is 83.25%. The blank montmorillonite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anode after impurity removal and conditioning.

[0023] Example 2

[0024] Bayer process sodium aluminate solution concentration Na2O (N k ) = 160g / L, αk = 1.5, Li2O concentration 1g / L; liquid-to-solid ratio 200:1, temperature 80°C, add 1.5g of montmorillonite, stir for 360 minutes, filter to obtain rich hectorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 94.50%.

[0025] After the hectorite is dried, it is desorbed with citric acid solution. The desorption conditions are: 25℃, concentration of 0.5 mol / L, liquid-solid ratio of 20:1, 1g of hectorite is added, and the reaction time is 60 minutes. The desorption rate reaches 84.63%. Then liquid-solid separation is carried out, and the blank montmorillonite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anode after impurity removal and conditioning.

[0026] Example 3

[0027] Bayer process sodium aluminate solution concentration Na2O (N k ) = 160g / L, αk = 1.5, Li2O concentration 1g / L; liquid-to-solid ratio 200:1, temperature 80°C, add 2g of montmorillonite, stir for 360 minutes, filter to obtain hectorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 91.09%.

[0028] After the hectorite is dried, it is desorbed with citric acid solution. The desorption conditions are: 25°C, concentration of 1 mol / L, liquid-to-solid ratio of 20:1, 1g of hectorite is added, and the reaction takes 60 minutes. The desorption rate reaches 85%, and then liquid-solid separation is performed. The blank montmorillonite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anodes after impurity removal and conditioning.

[0029] Example 4

[0030] Bayer process sodium aluminate solution concentration Na2O (N k ) = 160g / L, αk = 1.5, Li2O concentration 1g / L; liquid-to-solid ratio 400:1, temperature 80°C, add 1.5g of montmorillonite, stir for 360 minutes, filter to obtain rich hectorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 93.28%.

[0031] After the hectorite is dried, it is desorbed with citric acid solution. The desorption conditions are: 25℃, concentration of 1 mol / L, liquid-to-solid ratio of 1:1, 1g of hectorite is added, and the reaction takes 60 minutes. The desorption rate reaches 87.64%. Then liquid-solid separation is carried out, and the blank montmorillonite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anode after impurity removal and conditioning.

[0032] Example 5

[0033] Bayer process mother liquor concentration Na2O (N k) = 165g / L, αk = 1.45, Li2O concentration 1g / L; liquid-to-solid ratio 200:1, temperature 90°C, add 1.5g of chlorite, stir for 360 minutes, filter to obtain lithium-rich chlorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 85.80%.

[0034] After the lithium-rich chlorite is dried, it is desorbed using citric acid solution. The desorption conditions are: 25°C, concentration of 0.5 mol / L, liquid-to-solid ratio of 20:1, 1g of lithium-rich chlorite is added, and the reaction is carried out for 60 minutes. After that, liquid-solid separation is carried out, and the desorption rate reaches 89.64%. After that, liquid-solid separation is carried out, and the blank chlorite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anodes after impurity removal and conditioning.

[0035] Example 6

[0036] Bayer process mother liquor concentration Na2O (N k ) = 165g / L, αk = 1.45, Li2O concentration 1g / L; liquid-to-solid ratio 200:1, temperature 80°C, add 1.5g of chlorite, stir for 360 minutes, filter to obtain lithium-rich chlorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 90.50%.

[0037] After the lithium-rich chlorite is dried, it is desorbed using citric acid solution. The desorption conditions are: 25°C, concentration of 0.5 mol / L, liquid-to-solid ratio of 20:1, adding 1g of lithium-rich chlorite, reacting for 60 minutes, and the desorption rate reaches 82.63%. After that, liquid-solid separation is carried out, and the blank chlorite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anodes after impurity removal and conditioning.

[0038] Example 7

[0039] Bayer process mother liquor concentration Na2O (N k ) = 165g / L, αk = 1.45, Li2O concentration 1g / L; liquid-to-solid ratio 200:1, temperature 80°C, add 2g of chlorite, stir for 360 minutes, filter to obtain lithium-rich chlorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 92.43%.

[0040] After the lithium-rich chlorite is dried, it is desorbed using citric acid solution. The desorption conditions are: 25°C, concentration of 1 mol / L, liquid-to-solid ratio of 20:1, 1g of lithium-rich chlorite is added, and the reaction takes 60 minutes. The desorption rate reaches 88.34%. After that, liquid-solid separation is performed, and the blank chlorite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anodes after impurity removal and conditioning.

[0041] Example 8

[0042] Bayer process mother liquor concentration Na2O (N k ) = 165g / L, αk = 1.45, Li2O concentration 1g / L; liquid-to-solid ratio 400:1, temperature 80°C, add 1.5g of chlorite, stir for 360 minutes, filter to obtain lithium-rich chlorite, and return the filtrate to the Bayer process. After testing, the extraction rate of lithium metal in the sodium aluminate solution is 94.63%.

[0043] After the lithium-rich chlorite is dried, it is desorbed using citric acid solution. The desorption conditions are: 25°C, concentration of 1 mol / L, liquid-to-solid ratio of 1:1, 1g of lithium-rich chlorite is added, and the reaction takes 60 minutes. The desorption rate reaches 89.68%, and then liquid-solid separation is performed. The blank chlorite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anodes after impurity removal and conditioning.

[0044] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for extracting rare element lithium from a Bayer process sodium aluminate solution, which relates to the recycling of associated rare elements in bauxite, comprising the following steps: Chlorite is added to the sodium aluminate solution in the Bayer process to adsorb lithium. k ) = 165g / L, αk = 1.45, Li2O concentration 1g / L, liquid-solid ratio 400:1, 1.5g chlorite was added, the stirring time was 360min, the temperature was 80℃, liquid-solid separation was performed after sufficient reaction, and the separated sodium aluminate solution entered the seed separation process; after testing, the extraction rate of lithium metal in the separated sodium aluminate solution was 94.63%, and the lithium-rich chlorite filter cake was further processed to extract lithium; After the lithium-rich chlorite is dried, it is desorbed using citric acid solution. The desorption conditions are: 25°C, concentration of 1 mol / L, liquid-to-solid ratio of 1:1, 1g of lithium-rich chlorite is added, and the reaction takes 60 minutes. The desorption rate reaches 89.68%, and then liquid-solid separation is performed. The blank chlorite after desorption is returned to the adsorption process for recycling. The lithium citrate solution can be directly used in the preparation of lithium battery anodes after impurity removal and conditioning.

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