Method for synergistically recovering scattered metal and preparing geopolymer through lithium slag
The method of preparing geological polymers by microwave activation and staged leaching combined with silicon-aluminum auxiliary materials has solved the problems of high energy consumption and environmental pollution in lithium slag treatment, and achieved efficient recycling of dilute metals and high-performance preparation of geological polymers.
Patent Information
- Application Number
- CN202510618288.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-08-08
AI Technical Summary
The existing lithium slag treatment methods have high energy consumption, high cost and serious environmental pollution, low recovery rate of rare metals, and difficult to utilize lithium slag resources.
The lithium slag is pretreated by microwave activation, and dilute sulfuric acid and oxidizer are used to leach dilute metals in stages, and geological polymers are prepared by combining silicon-aluminum auxiliary materials and alkali exciters.
It reduces production costs and improves the recovery rate of rare metals. The prepared geological polymers have good environmental compatibility and mechanical properties, and are suitable for fields such as construction and roads.
Smart Images
Figure CN120442938A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solid waste resource utilization, and in particular to a method for collaboratively recovering rare metals from lithium slag and preparing geopolymers. Background Art
[0002] With the rapid development of new energy vehicles and the energy storage industry, demand for lithium resources is growing. Extracting lithium from lepidolite, a key method of extracting lithium, produces a large amount of lithium slag. Lithium slag contains rare metals such as lithium, rubidium, and cesium, as well as valuable components such as silicon and aluminum. If not properly handled, it not only wastes resources but also pollutes the environment.
[0003] Currently, traditional lithium slag treatment methods primarily utilize a crushing-pickling process to recover dispersed metals. This process presents the following challenges: First, the crushing process consumes a lot of energy and is inefficient; second, the pickling process requires a large amount of acid, which is costly and can easily cause environmental pollution; and third, the dissociation of dispersed metals from the lithium slag is ineffective, resulting in a low recovery rate. Furthermore, as a solid waste, the treatment and disposal of lithium slag faces significant pressure, making efficient resource utilization of lithium slag an urgent issue. Summary of the Invention
[0004] In view of this, the embodiments of the present invention hope to provide a method for collaboratively recovering rare metals and preparing geopolymers from lithium slag to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial option.
[0005] The purpose of the present invention can be achieved by the following technical measures: a method for collaboratively recovering rare metals and preparing geopolymers from lithium slag, comprising the following steps:
[0006] (1) Microwave activation pretreatment: The lithium slag from lithium mica is directly fed into a microwave reactor and irradiated at a frequency of 2.45 GHz ± 0.5 GHz and a power of 5-30 kW for 10-60 minutes;
[0007] (2) Leaching of scattered metals: mixing the lithium slag treated in step (1) with a sulfuric acid solution, controlling the leaching agent concentration to 0.1-1.0 mol / L, the temperature to 20-60°C, and the liquid-to-solid ratio to 2:1-6:1, and leaching lithium, rubidium, and cesium in stages;
[0008] (3) Preparation of geopolymer: The leaching residue from step (2) is mixed with a silicon-aluminum auxiliary material, an alkali activator is added, and the mixture is stirred and formed and then cured at room temperature for 3-28 days to obtain a geopolymer material.
[0009] The purpose of the present invention can also be achieved by the following technical measures:
[0010] In the step (1), the microwave frequency is preferably 2.45 GHz, the power is 10-20 kW, and the treatment time is 20-40 minutes.
[0011] The purpose of the present invention can also be achieved by the following technical measures:
[0012] In step (2), the leaching agent is dilute sulfuric acid with a concentration of 0.3-0.8 mol / L, and the staged leaching includes:
[0013] In the first stage, the pH is controlled at 1.5-2.5 and the leaching time is 30-90 minutes;
[0014] In the second stage, the oxidant H2O2 is added at a concentration of 0.5-2.0wt% to increase the leaching rate of rubidium and cesium.
[0015] The purpose of the present invention can also be achieved by the following technical measures:
[0016] In the step (3), the siliceous aluminum auxiliary material is at least one of fly ash, metakaolin or slag, and the mixing mass ratio is lithium slag: auxiliary material = 1:1-3:1.
[0017] The purpose of the present invention can also be achieved by the following technical measures:
[0018] The alkali activator is a composite solution of water glass and NaOH, the water glass modulus is 1.2-1.8, and the addition amount is 8-15% of the total mass of the solid phase.
[0019] The purpose of the present invention can also be achieved by the following technical measures:
[0020] The curing conditions of step (3) are: relative humidity ≥ 80%, temperature 20-30° C., and curing time 7-14 days.
[0021] The purpose of the present invention can also be achieved by the following technical measures:
[0022] The leaching solution in step (2) is separated and recovered with lithium, rubidium and cesium by solvent extraction, and the extractant is a mixed system of t-BAMBP and sulfonated kerosene.
[0023] The purpose of the present invention can also be achieved by the following technical measures:
[0024] Its 28-day compressive strength is ≥40MPa, and the heavy metal leaching concentration complies with the GB5085.3-2007 standard.
[0025] The purpose of the present invention can also be achieved by the following technical measures:
[0026] During the staged leaching process, the leachates from the first stage and the second stage are subjected to solid-liquid separation respectively by centrifugal filtration, and the moisture content of the filter residue is ≤24%.
[0027] The purpose of the present invention can also be achieved by the following technical measures:
[0028] During the second stage of leaching, the stirring rate is controlled to be 200-500 rpm, and the leaching temperature is increased by 5-10° C. compared with the first stage to promote the reaction efficiency of the oxidant and the mineral particles.
[0029] The embodiment of the present invention adopts the above technical solution, which has the following advantages:
[0030] 1. Processing costs are reduced by 40%. Compared with traditional processes, microwave activation pretreatment reduces the investment and energy consumption of crushing equipment, and staged leaching reduces the amount of acid used, thereby reducing production costs.
[0031] 2. The recovery rate of rare metals is high. The recovery rates of lithium, rubidium and cesium are all ≥90%, which improves the utilization rate of resources.
[0032] 3. The prepared geopolymer has excellent performance, with a 28-day compressive strength of 40-50MPa, which meets the GB / T17671-2021 standard. At the same time, the heavy metal leaching concentration meets the GB 5085.3-2007 standard. It has good environmental compatibility and mechanical properties and is suitable for construction, roads and other fields.
[0033] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0035] Figure 1 The present invention is a flow chart of a specific embodiment of the method for collaboratively recovering rare metals and preparing geopolymers from lithium slag. DETAILED DESCRIPTION
[0036] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.
[0037] It should be noted that the terms "first," "second," "symmetrical," "array," etc. are used only to distinguish descriptions from positional descriptions and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, limitations on features such as "first" and "symmetrical" may explicitly or implicitly include one or more of these features; similarly, when the number of certain features is not limited in the form of words such as "two" or "three," it should be noted that these features also explicitly or implicitly include one or more of the number of features.
[0038] In the present invention, unless otherwise expressly specified or limited, terms such as "installation," "connection," and "fixation" should be understood broadly; for example, they may refer to fixed connection, detachable connection, or integral molding; they may refer to mechanical connection, direct connection, welding, or indirect connection through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on the specification and drawings in conjunction with specific circumstances.
[0039] The embodiments of the present invention are described in detail below.
[0040] like Figure 1 As shown, the method of the present invention for collaboratively recovering rare metals from lithium slag and preparing geopolymers comprises the following steps:
[0041] (1) Microwave activation pretreatment: The lithium slag from lithium mica is directly fed into a microwave reactor and irradiated at a frequency of 2.45 GHz ± 0.5 GHz and a power of 5-30 kW for 10-60 minutes;
[0042] (2) Leaching of scattered metals: mixing the lithium slag treated in step (1) with a sulfuric acid solution, controlling the leaching agent concentration to 0.1-1.0 mol / L, the temperature to 20-60°C, and the liquid-to-solid ratio to 2:1-6:1, and leaching lithium, rubidium, and cesium in stages;
[0043] (3) Preparation of geopolymer: The leaching residue from step (2) is mixed with a silicon-aluminum auxiliary material, an alkali activator is added, and the mixture is stirred and formed and then cured at room temperature for 3-28 days to obtain a geopolymer material.
[0044] In step (1), the microwave frequency is preferably 2.45 GHz, the power is 10-20 kW, and the treatment time is 20-40 minutes. In step (2), the leaching agent is dilute sulfuric acid with a concentration of 0.3-0.8 mol / L. The staged leaching includes:
[0045] In the first stage, the pH is controlled at 1.5-2.5 and the leaching time is 30-90 minutes;
[0046] In the second stage, the oxidant H2O2 is added at a concentration of 0.5-2.0wt% to increase the leaching rate of rubidium and cesium.
[0047] In step (3), the siliceous aluminum auxiliary material is at least one of fly ash, metakaolin or slag, and the mixing mass ratio is lithium slag: auxiliary material = 1:1-3:1. The alkaline activator is a composite solution of water glass and NaOH, the water glass modulus is 1.2-1.8, and the addition amount is 8-15% of the total mass of the solid phase. The curing conditions of step (3) are: relative humidity ≥80%, temperature 20-30°C, and curing time 7-14 days. The leachate of step (2) is separated and recovered by solvent extraction method for lithium, rubidium and cesium, and the extractant is a mixed system of t-BAMBP and sulfonated kerosene.
[0048] Its 28-day compressive strength is ≥40MPa, and the heavy metal leaching concentration complies with the GB5085.3-2007 standard. During the staged leaching process, the leachates of the first stage and the second stage are respectively subjected to solid-liquid separation by centrifugal filtration, and the moisture content of the filter residue is ≤24%. During the second stage leaching, the stirring rate is controlled to be 200-500rpm, and the leaching temperature is increased by 5-10°C compared with the first stage to promote the reaction efficiency of the oxidant and the mineral particles.
[0049] The following are several specific embodiments of the present invention:
[0050] Example 1
[0051] (1) Microwave activation pretreatment: 100 kg of lithium slag extracted from lithium mica is evenly spread on a special microwave reactor tray. The tray is made of high-temperature resistant and microwave-permeable ceramic material to avoid the tray's absorption loss of microwave energy. Turn on the microwave reactor, set the microwave frequency to 2.45 GHz, the power to 10 kW, and the treatment time to 20 minutes. During the treatment process, the temperature change of the lithium slag is monitored in real time by the infrared temperature measuring device built into the reactor to ensure that the temperature does not exceed 300 ° C, to prevent the lithium slag from over-sintering and affecting subsequent leaching. After the microwave treatment is completed, the lithium slag is cooled to room temperature. At this time, the surface color of the lithium slag becomes slightly darker and the structure becomes loose and porous, creating favorable conditions for the subsequent leaching of scattered metals.
[0052] (2) Leaching of scattered metals: The cooled lithium slag was transferred to a 500L stainless steel reactor, and 300L of dilute sulfuric acid with a concentration of 0.3mol / L was added. The liquid-solid ratio was controlled to 3:1. The agitator was turned on and the speed was set to 200rpm to fully mix the lithium slag with the sulfuric acid. The temperature of the reactor was adjusted to 25°C, and the amount of acid added was adjusted by the pH automatic control system to maintain the pH at 1.5 in the first stage. The leaching time was 30 minutes. In this stage, the lithium element in the lithium slag first reacted with the sulfuric acid to generate water-soluble lithium sulfate that entered the solution. After the first stage, 0.5wt% (relative to the mass of the lithium slag) of H2O2 was added to the reactor. At this time, the hydroxyl radicals generated by the decomposition of H2O2 could destroy the lattice structure of rubidium and cesium minerals and improve the leaching rate of rubidium and cesium. The stirring leaching was continued for 60 minutes. After the second stage, the leachate was subjected to solid-liquid separation by a plate and frame filter press to obtain leachate and filter residue. The leachate was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the results showed that the recovery rates of lithium, rubidium, and cesium were 92%, 91%, and 90%, respectively.
[0053] (3) Preparation of geopolymer: The above leaching residue was mixed with 100 kg of fly ash (in accordance with GB / T1596-2017 standard, with a specific surface area of 320 m 2 / kg) was added to a forced mixer and dry mixed for 3 minutes to fully mix it. A composite solution of water glass (modulus 1.2) and NaOH was weighed as an alkali activator according to 8% of the total mass of the solid phase. The alkali activator was slowly added to the mixer, and an appropriate amount of water was added to adjust the fluidity of the mixture. The mixture was wet mixed for 5 minutes until the material was uniform. The stirred mixture was poured into a triple mold with a size of 40mm×40mm×160mm, vibrated on a vibration table for 30 seconds to eliminate internal bubbles, and then covered with a plastic film on the mold surface to prevent water evaporation. The mold was placed in a constant temperature and humidity curing box with a relative humidity of 85% and a temperature of 25°C for 7 days. After the curing was completed, the mold was demoulded and the geopolymer test block was subjected to performance testing. The 28-day compressive strength was 42MPa. The test block was subjected to heavy metal leaching detection according to GB5085.3-2007 standard. The results showed that the heavy metal leaching concentration was lower than the standard limit, indicating that the geopolymer has good environmental safety.
[0054] Example 2
[0055] (1) Microwave activation pretreatment: 150 kg of lithium slag extracted from lepidolite was placed in a rotatable microwave reactor. The rotating device was used to make the lithium slag heated more evenly in the microwave field. The microwave frequency was set at 2.45 GHz, the power was 15 kW, and the treatment time was 30 minutes. During the microwave treatment, the mass loss of the lithium slag was recorded in real time. It was found that the mass loss rate was about 3%, which was mainly due to the volatilization of some adsorbed water and crystal water in the lithium slag. After the treatment, fine cracks appeared on the surface of the lithium slag particles, and the specific surface area increased significantly.
[0056] (2) Leaching of scattered metals: The microwave-treated lithium slag was transferred to a 1000L enameled reactor, and 600L of 0.5mol / L dilute sulfuric acid was added. The liquid-solid ratio was controlled to 4:1, and the stirring speed was increased to 250rpm. The reactor temperature was raised to 35°C, the pH was controlled to 2.0 in the first stage, and the leaching time was 60 minutes. After the end of this stage, a small amount of leachate was taken for rapid testing to confirm that the leaching of lithium elements had basically reached equilibrium. Then 1.0wt% H2O2 was added and the leaching was continued for 90 minutes. During the second stage of leaching, regular sampling and analysis showed that the leaching rate of rubidium and cesium was significantly accelerated within the first 30 minutes after the addition of H2O2. After the leaching was completed, the leachate was separated into solid and liquid using a centrifuge. The separated leachate was tested by ICP-MS, and the recovery rates of lithium, rubidium, and cesium were 93%, 92%, and 91%, respectively.
[0057] (3) Preparation of geopolymer: The leached residue was mixed with 200 kg of metakaolin (active alumina content ≥35%, active silica content ≥50%) and placed in a twin-shaft mixer and stirred evenly. A composite solution of water glass (modulus 1.5) and NaOH was prepared as an alkali activator according to 12% of the total mass of the solid phase. The alkali activator was added to the mixer, and an appropriate amount of water reducer (dosage of 0.5%) was added to improve the working performance of the mixture. The mixture was stirred for 8 minutes. The mixture was poured into a special mold and defoamed using a vacuum defoaming device. Then, a wet cloth was covered on the mold surface. The mold was placed in a curing room with a relative humidity of 90% and a temperature of 28°C for 14 days. The performance test of the geopolymer after curing showed that its 28-day compressive strength reached 45 MPa and it had good antifreeze performance. The strength loss rate after 50 freeze-thaw cycles was less than 5%, indicating that the geopolymer is suitable for engineering applications in cold regions.
[0058] Example 3
[0059] (1) Microwave activation pretreatment: 200 kg of lithium slag from lithium mica was placed in a large continuous microwave reactor equipped with an automatic feeding and discharging system, which can achieve continuous treatment of lithium slag. The microwave frequency was set at 2.45 GHz, the power was 20 kW, and the treatment time was 40 minutes. During the treatment process, the residence time of the lithium slag in the microwave reactor was precisely controlled at the set value by adjusting the feeding speed. The treated lithium slag was screened and the particle size was mainly distributed between 0.1 and 1 mm, which was conducive to the subsequent leaching reaction.
[0060] (2) Preparation method: Scattered metal leaching: The microwave-treated lithium slag was placed in a 2000L polypropylene reactor, and 1000L of dilute sulfuric acid with a concentration of 0.8mol / L was added, with a liquid-solid ratio of 5:1 and a stirring speed of 300rpm. The reactor temperature was raised to 50°C, and the pH was controlled to 2.5 in the first stage, and the leaching time was 90 minutes. During the first stage leaching process, the degree of reaction was judged by monitoring the change in the conductivity of the solution. After the first stage, 2.0wt% H2O2 was added and the leaching was continued for 120 minutes. After the leaching was completed, a belt filter press was used to separate the solid and liquid of the leaching solution. The obtained leaching solution was subjected to a series of operations such as extraction and back extraction to achieve the separation and recovery of lithium, rubidium and cesium, with recovery rates of 94%, 93% and 92% respectively.
[0061] (3) Geopolymer preparation: The leached residue was mixed with 300 kg of slag (specific surface area ≥ 450 m 2 / kg) was thoroughly mixed, and a composite solution of water glass (modulus 1.8) and NaOH was added at a dosage of 15% of the total solid phase mass. A small amount of accelerator (0.3%) was also added to accelerate the early strength development of the geopolymer. After uniform mixing, the mixture was poured into prefabricated component molds and cured using a combination of steam curing (60°C for 6 hours) and room temperature curing. Steam curing was first performed to rapidly stimulate the strength growth of the geopolymer, followed by room temperature curing for 28 days in an environment of 80% relative humidity and 30°C. Testing of the prepared geopolymer revealed a 28-day compressive strength of 50 MPa and a P8 impermeability rating, making it suitable for applications with high waterproofing requirements, such as underground projects.
[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various modifications and substitutions within the technical scope disclosed in the present invention, and such modifications and substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.
Claims
1. A method for collaboratively recovering rare metals and preparing geopolymers from lithium slag, characterized in that: The following steps are involved: (1) Microwave activation pretreatment: The lithium slag from lithium mica is directly fed into a microwave reactor and irradiated at a frequency of 2.45 GHz ± 0.5 GHz and a power of 5-30 kW for 10-60 minutes; (2) Leaching of scattered metals: mixing the lithium slag treated in step (1) with a sulfuric acid solution, controlling the leaching agent concentration to 0.1-1.0 mol / L, the temperature to 20-60°C, and the liquid-to-solid ratio to 2:1-6:1, and leaching lithium, rubidium, and cesium in stages; (3) Preparation of geopolymer: The leaching residue from step (2) is mixed with a silicon-aluminum auxiliary material, an alkali activator is added, and the mixture is stirred and formed and then cured at room temperature for 3-28 days to obtain a geopolymer material.
2. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 1, characterized in that: In the step (1), the microwave frequency is preferably 2.45 GHz, the power is 10-20 kW, and the treatment time is 20-40 minutes.
3. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 1, characterized in that: In step (2), the leaching agent is dilute sulfuric acid with a concentration of 0.3-0.8 mol / L, and the staged leaching includes: In the first stage, the pH is controlled at 1.5-2.5 and the leaching time is 30-90 minutes; In the second stage, the oxidant H2O2 is added at a concentration of 0.5-2.0wt% to increase the leaching rate of rubidium and cesium.
4. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 1, characterized in that: In the step (3), the siliceous aluminum auxiliary material is at least one of fly ash, metakaolin or slag, and the mixing mass ratio is lithium slag: auxiliary material = 1:1-3:
1.
5. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 1, characterized in that: The alkali activator is a composite solution of water glass and NaOH, the water glass modulus is 1.2-1.8, and the addition amount is 8-15% of the total mass of the solid phase.
6. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 1, characterized in that: The curing conditions of step (3) are: relative humidity ≥ 80%, temperature 20-30° C., and curing time 7-14 days.
7. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 1, characterized in that: The leachate in step (2) is used to separate and recover lithium, rubidium and cesium by solvent extraction, and the extractant is a mixture of 4-tert-butyl-2-(α-methylbenzyl)phenol (abbreviated as t-BAMBP) and sulfonated kerosene.
8. The geopolymer material prepared according to the method according to any one of claims 1 to 7, characterized in that: Its 28-day compressive strength is ≥40MPa, and the heavy metal leaching concentration complies with the GB5085.3-2007 standard.
9. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 3, characterized in that: During the staged leaching process, the leachates from the first stage and the second stage are subjected to solid-liquid separation respectively by centrifugal filtration, and the moisture content of the filter residue is ≤24%.
10. The method for collaboratively recovering rare metals and preparing geopolymers from lithium slag according to claim 3, characterized in that: During the second stage of leaching, the stirring rate is controlled to be 200-500 rpm, and the leaching temperature is increased by 5-10° C. compared with the first stage to promote the reaction efficiency of the oxidant and the mineral particles.