A lithium purification method suitable for clay-type lithium ore

Abstract

A kind of lithium purification method suitable for clay type lithium ore, steps are as follows: the mineral powder of clay type lithium ore is preheated and dried;The mineral powder is preheated;The mineral powder is high-temperature calcination activation treatment;The mineral powder is heat preservation activation treatment;The mineral powder is cooled for the first time, the combustion-supporting air required in high-temperature calcination activation treatment process is preheated in the cooling process, realizes the first heat energy recycling;The mineral powder is cooled for the second time, hot water or steam is produced as byproduct in the cooling process, realizes the second heat energy recycling, and the discharge temperature of mineral powder is controlled within 80 DEG C;The mineral powder is sent into sulfuric acid solution and is leached;The mineral powder is pressure filtered, when the lithium concentration of filtered leaching liquor is greater than 8g / L, the leaching liquor can be sent into refining workshop, if the lithium concentration of filtered leaching liquor is less than 8g / L, the leaching liquor continues leaching treatment.The lithium purification method of the application solves the problems of low leaching rate, low lithium recovery rate, high energy consumption and serious equipment corrosion in prior art.

Description

Technical Field

[0001] This invention belongs to the field of lithium ore purification technology, and in particular relates to a lithium purification method suitable for clay-type lithium ore. Background Technology

[0002] Currently, natural lithium resources can be classified into three types based on their occurrence: brine type, hard rock type, and clay type. Among these, brine type lithium deposits and hard rock type lithium deposits are the most widely mined and utilized worldwide.

[0003] For lithium resources from salt lake brine, lithium is relatively easy to separate because it is directly present in the brine. However, the lithium abundance in these resources is low, resulting in high processing costs. Furthermore, due to the relatively mature processing techniques, the potential for further reducing the development cost of these lithium resources is limited.

[0004] Hard-rock lithium resources are characterized by high abundance and large reserves, with a dense lithium ore structure that introduces fewer impurities during lithium purification. However, hard-rock lithium resources have high requirements for vein quality, and the actual number of exploitable veins is limited, making them unsustainable lithium resources. Furthermore, vein mining inevitably leads to environmental damage and pollution problems.

[0005] Clay-type lithium resources were previously considered unprofitable due to their loose structure, high impurity leaching rate, and low recovery rate. However, clay-type lithium resources are characterized by short vein formation time and undemanding formation conditions. Furthermore, with the continuous optimization of lithium purification processes, clay-type lithium resources have the potential for large-scale development and utilization.

[0006] At present, the methods for purifying lithium from clay-type lithium resources can be broadly categorized into direct leaching, calcination with additives, and chlorination-sulfurization.

[0007] Direct leaching refers to the extraction process where a leaching agent is added directly to lithium ore that has not undergone high-temperature roasting. It can be further divided into water leaching and sulfuric acid leaching. Additive roasting involves roasting (or granulating roasting) a mixture of additives and the ore sample, followed by water leaching to obtain a lithium-containing solution. Commonly used additives include hydroxides, carbonates, sulfates, chlorides, and natural materials or industrial byproducts such as limestone and gypsum. Chlorination-sulfurization involves roasting the ore sample in a hydrochloric acid or sulfur dioxide atmosphere for a period of time to achieve sufficient chlorination or sulfidation, followed by water leaching to obtain a lithium-containing solution.

[0008] However, the water leaching method has the problem of low efficiency; although the sulfuric acid leaching method can obtain lithium-containing solutions with high aluminum content, the lithium loss rate during impurity removal is also high; the additive roasting method has the problems of high roasting temperature and high energy consumption; the chlorination and sulfidation method has the problem of severe equipment corrosion and also has a large environmental pressure. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides a lithium purification method suitable for clay-type lithium ore, improving the purification process of clay-type lithium ore and solving problems such as low leaching rate, low lithium recovery rate, high energy consumption, and severe equipment corrosion in the prior art. Using the lithium purification method of this invention, no additives are added during the calcination process, reducing the environmental burden of flue gas and leached slag treatment, while also reducing equipment corrosion. The calcination process involves lower temperatures, resulting in lower exhaust gas temperatures. The cooling process after calcination activation allows for heat recovery and utilization, further reducing energy consumption. The lithium leaching rate in the leachate obtained after the leaching process is >93%. This invention also features simple implementation, easy control of each step, large processing capacity, high lithium concentration in the leachate, low energy consumption, and good environmental performance.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a lithium purification method suitable for clay-type lithium ore, comprising the following steps:

[0011] Step 1: Preheat and dry the clay-type lithium ore powder;

[0012] Step 2: After the mineral powder has been preheated and dried, it is then preheated again.

[0013] Step 3: After the mineral powder has been preheated, it is then subjected to high-temperature calcination activation treatment.

[0014] Step 4: After the mineral powder has completed the high-temperature calcination activation treatment, it is then subjected to a heat preservation activation treatment.

[0015] Step 5: After the mineral powder has completed the heat preservation and activation treatment, it is cooled for the first time. During the cooling process, the combustion air required in the high-temperature calcination and activation treatment process is preheated to achieve the first heat energy recovery and utilization.

[0016] Step Six: After the mineral powder has completed the first cooling, it is cooled a second time. Hot water or steam is produced as a byproduct during the cooling process, realizing the second heat energy recovery and utilization. The temperature of the mineral powder when it is discharged is controlled below 80℃.

[0017] Step 7: After the mineral powder has completed its second cooling, it is then sent to a sulfuric acid solution for leaching treatment.

[0018] Step 8: After the mineral powder has been leached, it is then filtered. The leaching solution can be sent to the refining workshop only when the lithium concentration of the leaching solution is >8g / L. If the lithium concentration of the leaching solution is <8g / L, the leaching solution is returned to Step 7 for further leaching.

[0019] In step one, the preheating and drying temperature is 120℃~200℃.

[0020] In step two, the preheating temperature is 200℃~400℃.

[0021] In step three, the calcination temperature is 400℃~800℃.

[0022] In step three, the calcination time is 1s to 10s.

[0023] In step four, the heat preservation and activation time is 1 min to 60 min.

[0024] In step seven, the concentration of the sulfuric acid solution is 1.5 mol to 3 mol.

[0025] In step seven, the leaching temperature is 50℃~95℃.

[0026] In step seven, the leaching time is 30 min to 90 min.

[0027] In step seven, the liquid-to-solid ratio of the sulfuric acid solution to the mineral powder is (8:1) to (5:1).

[0028] The beneficial effects of this invention are:

[0029] This invention provides a lithium purification method applicable to clay-type lithium ore, improving the purification process and solving problems such as low leaching rate, low lithium recovery rate, high energy consumption, and severe equipment corrosion in existing technologies. Using this lithium purification method, no additives are added during the calcination process, reducing the environmental burden of flue gas and leached slag treatment, while also minimizing equipment corrosion. The calcination process involves lower temperatures, resulting in lower exhaust gas temperatures. The cooling process after calcination activation allows for heat recovery and utilization, further reducing energy consumption. The lithium leaching rate in the leachate obtained after the leaching process is >93%. This invention also features simple implementation, easy control of each step, large processing capacity, high lithium concentration in the leachate, low energy consumption, and good environmental performance. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of a lithium purification method applicable to clay-type lithium ore according to the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] In this embodiment, the clay-type lithium ore powder is lithium chlorite, which is in the form of dry powder or wet powder. The moisture content of the wet powder is <20%, and the moisture content of the wet powder after drying is <1%. The particle size distribution of the ore powder is 50% to 80% of the particles smaller than 74 μm. The hot flue gas used for drying the ore powder is the hot flue gas emitted during preheating. The hot flue gas used for preheating the ore powder is the hot flue gas emitted during the high-temperature calcination and activation treatment process. The fuel used in the high-temperature calcination and activation treatment process is in the form of gas, liquid, or solid. The leaching temperature during the leaching process can be controlled by the by-product steam produced during the cooling process.

[0033] like Figure 1 As shown, a lithium purification method suitable for clay-type lithium ore includes the following steps:

[0034] Step 1: Preheat and dry the clay-type lithium ore powder, with the preheating and drying temperature controlled between 120℃ and 200℃;

[0035] Step 2: After the mineral powder has been preheated and dried, it is then preheated again, with the preheating temperature controlled between 200℃ and 400℃.

[0036] Step 3: After the mineral powder is preheated, it is then subjected to high-temperature calcination activation treatment. The calcination temperature is controlled at 400℃~800℃ and the calcination time is controlled at 1s~10s.

[0037] Step 4: After the mineral powder has completed the high-temperature calcination activation treatment, it is then subjected to heat preservation activation treatment. The heat preservation activation time is controlled between 1 min and 60 min.

[0038] Step 5: After the mineral powder has completed the heat preservation and activation treatment, it is cooled for the first time. During the cooling process, the combustion air required in the high-temperature calcination and activation treatment process is preheated to achieve the first heat energy recovery and utilization.

[0039] Step Six: After the mineral powder has completed the first cooling, it is cooled a second time. Hot water or steam is produced as a byproduct during the cooling process, realizing the second heat energy recovery and utilization. The temperature of the mineral powder when it is discharged is controlled below 80℃.

[0040] Step 7: After the mineral powder has completed its second cooling, it is then sent to a sulfuric acid solution for leaching. The concentration of the sulfuric acid solution is controlled at 1.5 mol to 3 mol, the leaching temperature is controlled at 50℃ to 95℃, the leaching time is controlled at 30 min to 90 min, and the liquid-solid ratio of the sulfuric acid solution to the mineral powder is (8:1) to (5:1).

[0041] Step 8: After the mineral powder has been leached, it is then filtered. The leaching solution can be sent to the refining workshop only when the lithium concentration of the leaching solution is >8g / L. If the lithium concentration of the leaching solution is <8g / L, the leaching solution is returned to Step 7 for further leaching.

[0042] Specifically, the liquid content in the filter residue from the filter press is <4%, and the leachate from the filter press, upon analysis, has low levels of other elemental impurities (calculated as elemental substances) and complies with the relevant provisions of GB51382-2019. Specifically, the aluminum content is <0.07%, magnesium content is <0.0021%, sodium content is <0.0021%, potassium content is <0.0177%, beryllium content is <0.00001%, boron content is <0.00006%, phosphorus content is <0.00006%, sulfur content is <0.00001%, titanium content is <0.00129%, and vanadium content is <0.0004%.

[0043] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. A method for purifying lithium from clay-type lithium ore, characterized in that... Includes the following steps: Step 1: Preheat and dry the clay-type lithium ore powder at a temperature of 120℃~200℃; Step 2: After the mineral powder has been preheated and dried, it is then preheated again at a temperature of 200℃~400℃. Step 3: After the mineral powder has been preheated, it is then subjected to high-temperature calcination activation treatment. The calcination temperature is 400℃~800℃ and the calcination time is 1s~10s. Step 4: After the mineral powder has completed the high-temperature calcination activation treatment, it is then subjected to a heat preservation activation treatment. Step 5: After the mineral powder has completed the heat preservation and activation treatment, it is cooled for the first time. During the cooling process, the combustion air required in the high-temperature calcination and activation treatment process is preheated to achieve the first heat energy recovery and utilization. Step Six: After the mineral powder has completed the first cooling, it is cooled a second time. Hot water or steam is produced as a byproduct during the cooling process, realizing the second heat energy recovery and utilization. The temperature of the mineral powder when it is discharged is controlled below 80℃. Step 7: After the mineral powder has completed its second cooling, it is then sent to a sulfuric acid solution for leaching treatment. Step 8: After the mineral powder has been leached, it is then filtered. The leaching solution can be sent to the refining workshop only when the lithium concentration of the leaching solution is >8g / L. If the lithium concentration of the leaching solution is <8g / L, the leaching solution is returned to Step 7 for further leaching.

2. The lithium purification method applicable to clay-type lithium ore according to claim 1, characterized in that: In step four, the heat preservation and activation time is 1 min to 60 min.

3. The lithium purification method applicable to clay-type lithium ore according to claim 1, characterized in that: In step seven, the leaching temperature is 50℃~95℃.

4. The lithium purification method applicable to clay-type lithium ore according to claim 1, characterized in that: In step seven, the leaching time is 30 min to 90 min.

5. A lithium purification method suitable for clay-type lithium ore according to claim 1, characterized in that: In step seven, the liquid-to-solid ratio of the sulfuric acid solution to the mineral powder is (8:1) to (5:1).

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