A method for controlling the morphology of lithium slag and its application

Abstract

This invention provides a method and application for controlling the morphology of lithium slag. The method includes: preparing caustic alkali solutions of different concentrations, adding a certain mass of lithium slag and a morphology modifier to a reaction vessel for reaction, and obtaining lithium slag with an elongated columnar morphology. Based on the resource utilization of lithium slag, this invention adds lithium slag with different morphologies to PVC materials, compares the effects of different morphologies on the performance of PVC composite materials, and screens out lithium slag morphologies that are more advantageous for improving the performance of PVC materials.

Description

Technical Field

[0001] This invention belongs to the field of secondary utilization technology of waste resources, specifically relating to a method for controlling the morphology of lithium slag and its application. Background Technology

[0002] With the global green and low-carbon transformation and the rapid development of new energy vehicles, the strategic importance of lithium resources is becoming increasingly prominent. Currently, the main method for obtaining lithium resources is through ore extraction. Spodumene, lepidolite, lepidolite, and petalite are the main raw materials for ore-based lithium extraction. The extraction process generates a large amount of lithium extraction slag, as well as a significant amount of tailings during mineral processing. Currently, the utilization of ore extraction slag is far less than the generation of slag. Most of the slag is still disposed of through open-air dumping and landfilling, which pollutes the soil and water resources. Exploring ways to utilize lithium slag can further reduce pollution and industrial production costs, which is of great significance for environmental protection and the economy.

[0003] Thermoplastic polymers (PVC, PP, HDPE, etc.) have a wide range of applications, with demand in multiple industries including construction (doors and windows, pipes, cables), electronics, and automobiles. Their material performance advantages include weather resistance, acid and alkali resistance, and flame retardancy. The properties of thermoplastic materials can be optimized according to actual needs. Currently, most modifications to thermoplastic materials involve adding various functional additives or adding costly inorganic fillers (titanium dioxide, talc, or calcium silicate) to improve the performance of thermoplastic composites. Research on using lithium slag as a filler to modify thermoplastic materials mainly focuses on the dosage and modification methods.

[0004] Patent CN101987897A discloses a thermoplastic composite material prepared by mixing thermoplastic resin (HDPE), lepidolite, and processing aids, which has good antistatic properties but poor tensile strength (17~28 Ma).

[0005] Patent CN117384453A discloses a high-strength and weather-resistant composite material and its preparation process. It uses tailings slag, steel grit, etc. as fillers and mixes them with PVC, silane coupling agent, and processing aids to prepare a composite PVC material with high strength and weather resistance. However, the amount of processing aid is large, ranging from 4.25% to 13.25% of the mixture mass, and the amount of tailings added is 10.5% to 24%. Moreover, the tailings slag needs to be used in combination with steel slag. It can be seen that the slag used alone may need further treatment to increase its compatibility with polymer materials, such as morphology control and modification treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a method and application for controlling the morphology of lithium slag. This method dissolves lithium slag with a caustic alkali solution and adjusts the morphology of the recrystallized lithium slag with a morphology control agent. It can be controlled according to the needs of lithium slag, improve the utilization rate of lithium slag, and has strong practicality and good comprehensive benefits.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for controlling the morphology of lithium slag includes the following steps: (1) Prepare a caustic alkali solution of a certain concentration; (2) Soak the lithium slag in water, dry and crush it to a certain particle size; (3) Mix the crushed lithium slag from step (2) with the caustic alkali solution from step (1) and add a morphology modifier to obtain a mixture; (4) The mixture obtained in step (3) is subjected to hydrothermal reaction. After the reaction is completed, solid and liquid are separated to obtain lithium slag with a long columnar morphology.

[0008] Furthermore, in step (1), the caustic alkali is one or a mixture of sodium hydroxide and potassium hydroxide, and the alkali concentration is 2.5~4 mol / L.

[0009] Furthermore, the lithium slag mentioned in step (2) is a mixture of lithium extraction slag from spodumene, lepidolite, ferromagnetic mica, and spodumene, as well as tailings.

[0010] Furthermore, the particle size of the crushed lithium slag in step (2) is ≤74μm.

[0011] Furthermore, in step (3), the mass-to-volume ratio of lithium slag to caustic alkali solution is 10g:100ml.

[0012] Furthermore, the morphology modifier added in step (3) is one of NaCl, NaNO3, Na2SO4, CaO, or Ca(OH)2.

[0013] Furthermore, the mass ratio of the morphology modifier added in step (3) to the lithium slag is 3~6:10.

[0014] Furthermore, the conditions for the hydrothermal reaction in step (4) are 200~240℃, 250~400rpm, and 2~6h.

[0015] Furthermore, in the lithium slag with an elongated columnar morphology obtained by the method described above, the aspect ratio of the elongated columnar morphology of the lithium slag is 2-20:1, preferably 20:1.

[0016] Furthermore, the application of the elongated columnar lithium slag in the preparation of PVC composite materials: the elongated columnar lithium slag is incorporated into PVC materials to prepare lithium slag / PVC composite materials.

[0017] Compared with the prior art, the advantages of the present invention are as follows: (1) The morphology of lithium slag is controlled by the present invention, which can broaden the applicable environment of lithium slag. It can not only effectively alleviate the pollution problem caused by the large-scale stockpiling of lithium slag, but also realize the resource utilization of lithium slag extracted from lepidolite to obtain high-value-added lithium slag / PVC composite material, providing more directions for the resource utilization of lithium slag extracted from lepidolite.

[0018] (2) By controlling the morphology, lithium slag morphology that is more conducive to the modification of PVC materials is selected, which is conducive to the addition of lithium slag as filler in PVC materials at a higher proportion, and further reduces the pollution caused by accumulation to the environment.

[0019] (3) The process flow is short and easy to realize industrial production. The main process flow of this method is to mix lithium slag with caustic alkali solution and morphology control agent for hydrothermal reaction. The process is simple and has less requirement for process conditions, which is conducive to industrial production. Attached Figure Description

[0020] Figure 1 These are microscopic morphology diagrams of lithium slag after regulation in this invention; (a) regulated lithium slag 1; (b) regulated lithium slag 2; (c) regulated lithium slag 3; (d) regulated lithium slag 4. Detailed Implementation

[0021] Application of elongated columnar lithium slag in the preparation of PVC composite materials: Elongated columnar lithium slag is incorporated into PVC materials to prepare lithium slag / PVC composite materials. Specifically, this involves mixing elongated columnar lithium slag, polyvinyl chloride, aluminate coupling agent, processing aid MC100, calcium-zinc composite stabilizer, and lubricant PE wax in a mass ratio of 10:50:0.11:1.4:1.2:2.1, and then extruding and granulating the mixture using a twin-screw extruder to prepare the lithium slag / PVC composite material.

[0022] The method for preparing the elongated columnar lithium slag includes the following steps: (1) Prepare a caustic alkali solution of a certain concentration.

[0023] (2) Soak the untreated lithium slag in water, dry and crush it to a certain particle size.

[0024] (3) Mix the crushed lithium slag from step (2) with the caustic alkali solution from step (1) and add a morphology modifier to obtain a mixture.

[0025] (4) The mixture obtained in step (3) is subjected to hydrothermal reaction. After the reaction is completed, solid and liquid are separated to obtain lithium slag with a long columnar morphology.

[0026] Furthermore, in step (1), the caustic alkali is one or a mixture of sodium hydroxide and potassium hydroxide, and the alkali concentration is 2.5~4 mol / L.

[0027] Furthermore, the lithium slag mentioned in step (2) is a mixture of lithium extraction slag from spodumene, lepidolite, lithium mica, or lepidolite and tailings.

[0028] Furthermore, the particle size of the crushed lithium slag in step (2) is ≤74μm.

[0029] Furthermore, in step (3), the mass-to-volume ratio of lithium slag to caustic alkali solution is 10g:100ml.

[0030] Furthermore, (3) the added morphology modifier is one of sodium salts (NaCl, NaNO3, Na2SO4) or one of CaO or Ca(OH)2.

[0031] Furthermore, the mass ratio of the morphology modifier added in step (3) to the lithium slag is 3~6:10.

[0032] Furthermore, the conditions for the hydrothermal reaction in step (4) are 200~240℃, 250~400rpm, and 2~6h.

[0033] The present invention will be further described in detail below through specific embodiments, but this does not limit the present invention. Various changes and substitutions made by those skilled in the art based on the present invention, as long as they do not depart from the spirit of the present invention, should fall within the scope of the appended claims.

[0034] Example 1 (1) Dissolve 10g of sodium hydroxide in 100ml of water to prepare a 2.5mol / L sodium hydroxide solution.

[0035] (2) Soak the lithium slag in water, dry it and crush it. Take 10g of lithium slag crushed to a particle size ≤74um and 3.55g of morphology modifier (Na2SO4) and add it to the sodium hydroxide solution in (1). Place it in a reaction vessel and set the reaction conditions to 230℃, 300rpm and 5h.

[0036] (3) After the reaction is complete, solid-liquid separation is performed. The filter residue is washed twice with water at a ratio of 1g:10ml, and solid-liquid separation is performed again. After drying and grinding, controlled lithium ore slag 1 is obtained. The morphological characteristics of controlled lithium ore slag 1 are long columnar with an aspect ratio of about 20:1.

[0037] (4) Take the controlled lithium slag 1, polyvinyl chloride, aluminate coupling agent, processing aid MC100, calcium-zinc composite stabilizer, and lubricant PE wax from (3) in a mass ratio of 10:50:0.11:1.4:1.2:2.1. Add them to a high-speed mixer for premixing, and then granulate them by extrusion using a twin-screw extruder to prepare a composite material of lithium slag and PVC.

[0038] Example 2 (1) Dissolve 15% sodium hydroxide in 100ml of water to prepare a 3.75mol / L sodium hydroxide solution.

[0039] (2) Soak the lithium slag in water, dry it and crush it. Take 10g of lithium slag crushed to a particle size ≤74um and 3.55g of morphology modifier (Na2SO4) and add it to the sodium hydroxide solution in (1). Place it in a reaction vessel and set the reaction conditions to 230℃, 300rpm and 5h.

[0040] (3) After the reaction is complete, solid-liquid separation is performed. The filter residue is washed twice with water at a ratio of 1g:10ml, and solid-liquid separation is performed again. After drying and grinding, the controlled lithium ore residue 2 is obtained. The morphological characteristics of controlled lithium ore residue 2 are long columnar with an aspect ratio of about 10:1.

[0041] (4) Take the controlled lithium slag 2, polyvinyl chloride, aluminate coupling agent, processing aid MC100, calcium-zinc composite stabilizer, and lubricant PE wax from (3) in a mass ratio of 10:50:0.11:1.4:1.2:2.1. Add them to a high-speed mixer for premixing, and then granulate them by extrusion using a twin-screw extruder to prepare a composite material of lithium slag and PVC.

[0042] Example 3 (1) Dissolve 20g of sodium hydroxide in 100ml of water to prepare a 5mol / L sodium hydroxide solution.

[0043] (2) Soak the lithium slag in water, dry it and crush it. Take 10g of lithium slag crushed to a particle size ≤74um and 3.55g of morphology modifier (Na2SO4) and add it to the sodium hydroxide solution in (1). Place it in a reaction vessel and set the reaction conditions to 230℃, 300rpm and 5h.

[0044] (3) After the reaction is completed, solid-liquid separation is carried out. The filter residue is washed twice with water at a ratio of 1g:10ml, and solid-liquid separation is carried out again. After drying and grinding, the controlled lithium ore residue 3 is obtained. The morphological characteristics of controlled lithium ore residue 3 are long columnar with an aspect ratio of about 10:3~4.

[0045] (4) Take the lithium slag 3, polyvinyl chloride, aluminate coupling agent, processing aid MC100, calcium-zinc composite stabilizer, and lubricant PE wax from (3) in a mass ratio of 10:50:0.11:1.4:1.2:2.1. Add them to a high-speed mixer for premixing, and then granulate them by extrusion using a twin-screw extruder to prepare a composite material of lithium slag and PVC.

[0046] Comparative Example 1 (1) Dissolve 20g of sodium hydroxide in 100ml of water to prepare a 5mol / L sodium hydroxide solution.

[0047] (2) Soak the lithium slag in water, dry it and crush it. Take 10g of lithium slag crushed to a particle size ≤74um and 5g of morphology modifier (CaO) and add it to the sodium hydroxide solution in (1). Place it in a reactor and set the reaction conditions to 230℃, 300rpm and 5h.

[0048] (3) After the reaction is completed, solid-liquid separation is carried out. The filter residue is washed twice with water at a ratio of 1g:10ml, and solid-liquid separation is carried out again. After drying and grinding, the controlled lithium ore residue 4 is obtained. The morphological characteristics of the controlled lithium ore residue 4 are octahedral with an aspect ratio of about 1~1.5:1.

[0049] (4) Take the lithium slag 4, polyvinyl chloride, aluminate coupling agent, processing aid MC100, calcium-zinc composite stabilizer, and lubricant PE wax from (3) in a mass ratio of 10:50:0.11:1.4:1.2:2.1. Add them to a high-speed mixer for premixing, and then granulate them by extrusion using a twin-screw extruder to prepare a composite material of lithium slag and PVC.

[0050] Comparative Example 2 Polyvinyl chloride (PVC), processing aid MC100, calcium-zinc composite stabilizer, and lubricant PE wax were mixed in a mass ratio of 50:1.4:1.2:2.1. The mixture was premixed in a high-speed mixer, and then extruded and granulated using a twin-screw extruder to produce pure PVC material.

[0051] Mechanical properties were tested on materials prepared by combining lithium slag with PVC under different morphologies.

[0052] The test results show that when the controlled lithium slag has a long columnar morphology and a larger aspect ratio, the improvement effect on the mechanical properties of PVC composite materials is more obvious. When the aspect ratio of lithium slag gradually decreases, the reinforcing effect on PVC composite materials gradually weakens.

[0053] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are provided below for detailed description. Unless otherwise specified, the methods of the present invention are conventional methods in the art.

Claims

1. The application of a long columnar lithium slag in the preparation of PVC composite materials, characterized in that: Lithium slag / PVC composite material is prepared by incorporating long columnar lithium slag into PVC material; the aspect ratio of the long columnar lithium slag is 20:

1. The method for preparing the elongated columnar lithium slag includes the following steps: (1) Dissolve 10g of sodium hydroxide in 100mL of water to prepare a 2.5mol / L sodium hydroxide solution; (2) Soak the lithium slag in water, dry it and crush it. Take 10g of lithium slag crushed to a particle size ≤74um and 3.55g of morphology modifier Na2SO4 and add it to the sodium hydroxide solution in step (1). Place it in a reaction vessel and set the reaction conditions to 230℃, 300rpm and 5h. (3) After the reaction is complete, solid-liquid separation is carried out. The filter residue is washed twice with water at a ratio of 1g:10mL, and solid-liquid separation is carried out again. After drying and grinding, lithium slag with a long columnar morphology is obtained.

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