Unfired lightweight aggregate of spodumene lithium extraction slag and preparation method of unfired lightweight aggregate

Abstract

The invention belongs to the technical field of solid waste recycling and environment-friendly materials, and relates to an unfired lightweight aggregate of spodumene lithium extraction slag and a preparation method of the unfired lightweight aggregate. Raw materials of the unfired lightweight aggregate comprise spodumene lithium extraction slag, gypsum slag and a binder. The spodumene lithium extraction slag and the gypsum slag are matched and synergistically used for preparing the unfired lightweight aggregate, so that the activity is improved, the curing stability is enhanced, the preparation cost is reduced, and a new path of double-slag synergistic recycling is realized.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and environmental protection materials technology, and relates to a non-burning lightweight aggregate of lithium spodumene lithium extraction slag and its preparation method. Background Technology

[0002] Lithium spodumene slag (containing 0.05%-0.1% beryllium) is a major hazardous solid waste in the lithium battery industry. Traditional disposal methods (landfill or high-temperature sintering) suffer from excessive beryllium leaching (>0.02mg / L) and high energy consumption (sintering temperature >1100℃). Furthermore, lithium slag contains large amounts of silicon, aluminum, calcium, and other elements; landfilling results in significant resource waste. Therefore, how to harmlessly and recycle lithium slag is of great importance to the healthy development of the lithium battery industry. Gypsum slag is difficult and costly to dispose of. Its diverse sources and complex composition, containing heavy metals and other impurities, along with its high water content, make transportation and storage difficult and easily pollute the environment. Landfilling requires significant land and carries high risks, while resource utilization requires advanced technology and is costly. Pre-treatment and transportation also increase costs.

[0003] Artificial lightweight aggregates, due to their light weight, high strength, and excellent thermal insulation properties, have been widely used in building aggregates, thermal insulation materials, ecological greening, and toilet backfilling. Utilizing lithium slag, a byproduct generated in large quantities during lithium extraction, to prepare non-fired lightweight aggregates not only achieves resource reuse but also significantly reduces production energy consumption. However, current processes generally require the addition of large amounts of cement or quicklime, and face challenges such as insufficient activity and unsatisfactory long-term solidification stability of heavy metals, especially beryllium. CN115676535A uses a calcination + acid leaching method to treat spodumene slag, and uses the calcined spodumene residue to mix with gravel, cement, concrete additives, and fillers to prepare gravel-type cement concrete. Research shows that the pozzolanic activity of the residue can participate in cement hydration to generate CSH and CAH systems, thereby significantly improving the compressive strength of concrete while reducing cement usage. It utilizes the pozzolanic-active residue as aggregate to replace part of the gravel and enhance strength; however, it relies on a large amount of cement for cementing, and the preparation of non-fired lightweight aggregates still depends on cement as the main cementing system. CN115893888A proposes a method for preparing high-strength, early-strength cementitious materials using a synergistic ratio of lithium slag and red mud (10-40 parts lithium slag, 5-30 parts red mud, and 5-15 parts activator). The red mud neutralizes residual acid in the lithium slag and generates hydrated sulfate crystals during coagulation, promoting micro-expansion and improving hardened volume stability and crack resistance. This method eliminates the need for an external cement system, achieving high strength and early strength solely through alkali activation and synergistic red mud application. However, the formulation and activation system of red mud are complex, and the long-term solidification mechanism of heavy metal elements remains unclear.

[0004] While the above-mentioned solutions have achieved the resource utilization of lithium slag, they still have obvious shortcomings: on the one hand, they rely too much on cement or activators, which leads to increased costs; on the other hand, the solidification effect of heavy metal elements is limited, and the long-term stability is questionable.

[0005] Therefore, how to realize the resource utilization of lithium spodumene extraction slag, improve its activity, enhance its solidification stability, and reduce its cost are technical problems that urgently need to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a non-fired lightweight aggregate from spodumene lithium extraction slag and its preparation method. This invention uses a combination of spodumene lithium extraction slag and gypsum slag for synergistic preparation of non-fired lightweight aggregate, improving activity, enhancing solidification stability, and reducing preparation costs, thus realizing a new path for the synergistic resource utilization of the two slags.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a non-fired lightweight aggregate of lithium-based slag, wherein the raw materials of the non-fired lightweight aggregate include lithium spodumene extraction slag, gypsum slag and binder.

[0009] This invention uses a mixture of spodumene lithium extraction slag and gypsum slag, eliminating the need for additional activators and curing agents in the raw materials. By leveraging the complementary components of the gypsum slag and spodumene lithium extraction slag, the hydration reaction is promoted, producing ettringite, CSH, and CASH. This achieves a beryllium solidification effect similar to that of non-fired lightweight aggregates with added activators and curing agents, enhancing activity, improving solidification stability, and reducing preparation costs. It realizes a new path for the synergistic resource utilization of two slags, resulting in non-fired lightweight aggregates with high compressive strength, low water absorption, low bulk density, and low beryllium leaching rate.

[0010] It should be noted that the spodumene lithium extraction slag in this invention is a major hazardous solid waste in the lithium battery industry, while gypsum slag comes from wastewater treatment neutralization waste or desulfurization process waste, etc. This invention does not impose specific limitations on more specific sources, and those skilled in the art can make adaptive selections and adjustments according to actual needs.

[0011] It is understandable that the specific components of the lithium spodumene extraction slag and gypsum slag in this invention are all conventional technical solutions, with only minor adjustments depending on the source of different raw materials.

[0012] Specifically, the composition of the lithium spodumene extraction slag, by mass fraction, includes: 45%~55% SiO2, 15%~25% Al2O3, 5%~15% SO3, 10%~25% CaO, 0.5~3% Na2O, 3%~8% K2O, 2%~4% Fe2O3, and the corresponding beryllium that needs to be solidified.

[0013] The gypsum slag comprises, by mass fraction, 35%~40% SO3, 25%~35% CaO, 1%~10% SiO2, 0.5%~5% Al2O3, 0.1%~0.5% Na2O, 0.1%~0.5% K2O, and 0.5%~2% Fe2O3.

[0014] Preferably, based on the total mass of the spodumene lithium extraction slag, the gypsum slag, and the binder as 100%, the mass percentage of the spodumene lithium extraction slag is 40% to 60%, for example, 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, or 60%.

[0015] Preferably, based on the total mass of the spodumene lithium extraction slag, the gypsum slag, and the binder as 100%, the mass percentage of the gypsum slag is 15% to 40%, for example, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, or 40%.

[0016] In the raw materials of the non-fired lightweight aggregate of the present invention, the total mass of the spodumene lithium extraction slag, the gypsum slag and the binder is taken as 100%. The mass ratio of the spodumene lithium extraction slag is controlled to be 40%~60% and / or the mass ratio of the gypsum slag is controlled to be 15%~40%. This better achieves the mutual matching of the two components, thereby obtaining a non-fired lightweight aggregate with higher compressive strength, lower water absorption, lower bulk density and lower beryllium concentration, realizing the effective resource recycling of solid waste.

[0017] Preferably, based on the total mass of the spodumene lithium extraction slag, the gypsum slag, and the binder as 100%, the mass percentage of the binder is 5% to 25%, for example, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, or 30%, etc.

[0018] Preferably, the gypsum residue has a purity >70%, a moisture content <25%, and a pH value >7.

[0019] For example, the purity of the gypsum residue can be 75%, 80%, 85%, 90%, 95%, or 99%, etc.; the moisture content of the gypsum residue can be 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, or 24%, etc.; and the pH value of the gypsum residue can be 7, 7.5, 8, 8.5, 9, 9.5, or 10, etc.

[0020] Preferably, the total moisture content of the raw materials for the non-fired lightweight aggregate is 10% to 30%, such as 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, or 30%.

[0021] Preferably, the adhesive comprises cement.

[0022] Preferably, the concentration of beryllium in the non-burning lightweight aggregate of the lithium-based slag after toxic leaching is <0.001 mg / L.

[0023] In a second aspect, the present invention provides a method for preparing non-fired lightweight aggregate of lithium-based slag as described in the first aspect, the method comprising the following steps:

[0024] (1) Mix spodumene lithium extraction slag, gypsum slag and binder to obtain a mixture;

[0025] (2) The mixture is granulated to obtain raw material pellets;

[0026] (3) Curing the raw material balls to obtain the non-burning lightweight aggregate of the lithium-based slag.

[0027] The preparation method of the present invention does not require complicated processing. It can obtain high-performance lithium-based slag non-fired lightweight aggregate through simple mixing, granulation and curing.

[0028] Preferably, the mixing method in step (1) includes: first mixing spodumene lithium extraction slag and gypsum slag, and then adding a binder for a second mixing.

[0029] Preferably, the first mixing method includes ball milling, and the second mixing method includes stirring.

[0030] Optionally, the rotational speed of the ball mill is 500 r / min to 1500 r / min, such as 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min or 1500 r / min.

[0031] Preferably, the ball milling time is 60 min to 90 min, for example, 60 min, 70 min, 80 min or 90 min.

[0032] Preferably, the stirring time is 30 min to 60 min, for example, 30 min, 40 min, 50 min or 60 min.

[0033] Preferably, the granulation method in step (2) includes roller pressing granulation or disc granulation.

[0034] Preferably, the loading pressure of the roller granulation is 1kN~5kN, such as 1kN, 2kN, 3kN, 4kN or 5kN.

[0035] Preferably, the rotation speed of the roller granulation is 150 rpm to 250 rpm, such as 150 rpm, 180 rpm, 200 rpm, 230 rpm or 250 rpm.

[0036] Preferably, the rotational speed of the disc granulator is 25 r / min to 35 r / min, for example, 25 r / min, 30 r / min or 35 r / min.

[0037] Preferably, the diameter of the raw material ball in step (2) is 5mm to 25mm, such as 5mm, 10mm, 15mm, 20mm or 25mm.

[0038] Preferably, the curing method in step (3) includes steam curing, and the temperature of the steam curing is 60℃~100℃, such as 60℃, 70℃, 80℃, 90℃ or 100℃.

[0039] Preferably, the humidity of the steam curing is 90% to 99%, such as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

[0040] Preferably, the steam curing time is 6h to 12h, such as 6h, 7h, 8h, 9h, 10h, 11h or 12h.

[0041] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] This invention uses a mixture of spodumene lithium extraction slag and gypsum slag, eliminating the need for additional activators and curing agents in the raw materials. By leveraging the complementary components of the gypsum slag and spodumene lithium extraction slag, the hydration reaction is promoted, producing ettringite, CSH, and CASH. This achieves a beryllium solidification effect similar to that of non-fired lightweight aggregates with added activators and curing agents, enhancing activity, improving solidification stability, and reducing preparation costs. It realizes a new path for the synergistic resource utilization of two slags, resulting in non-fired lightweight aggregates with high compressive strength, low water absorption, low bulk density, and low beryllium leaching rate. Attached Figure Description

[0044] Figure 1This is a schematic diagram of the preparation process of non-fired lightweight aggregate from lithium-based slag in Example 2. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0047] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0048] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0049] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0050] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0051] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0052] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0053] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0054] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0055] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0056] In one specific embodiment, the present invention provides corresponding component tables for spodumene lithium extraction slag and gypsum slag, the specific components of which are shown in Table 1.

[0057] Table 1

[0058]

[0059] Note: After the corresponding lithium extraction spodumene residue was subjected to toxic leaching using the sulfuric acid and nitric acid method, the beryllium content was found to be 3.27 mg / L by ICP-MS analysis, which far exceeds the national standard (GB 5085.3-2007) of 0.02 mg / L.

[0060] The following examples and comparative examples all use the raw materials provided in Table 1 above to prepare non-burning lightweight aggregates of lithium-based slag.

[0061] Example 1

[0062] This embodiment provides a non-fired lightweight aggregate of lithium-based slag. The raw materials of the non-fired lightweight aggregate do not contain activators and curing agents, and include lithium spodumene slag, gypsum slag, and ordinary 425 silicate cement as a binder. The mass ratio of lithium spodumene slag, gypsum slag and ordinary 425 silicate cement is 55:35:10.

[0063] The preparation method of the non-fired lightweight aggregate of the lithium-based slag is as follows:

[0064] Weigh out the corresponding amounts of spodumene lithium extraction slag, gypsum slag, binder, and ordinary 425 silicate cement according to the raw material formula.

[0065] (1) Lithium spodumene slag and gypsum slag are mixed in proportion and ball-milled at 1200 r / min for 60 min to obtain composite slag material. Cement is added to the composite slag material and mixed and stirred for 60 min to obtain a mixture material.

[0066] (2) Place the mixture in a disc granulator and add water accounting for 30% of the total mass of the mixture. By controlling the rotation speed of the disc granulator to 20 r / min and the tilt angle to 50°, raw material balls with a diameter distribution of 5 mm to 35 mm are prepared.

[0067] (3) Place the obtained raw material balls into a curing box and steam-cur them at 80°C and 95% humidity for 12 hours to obtain the lithium-based slag non-fired lightweight aggregate finished product.

[0068] Example 2

[0069] This embodiment provides a non-fired lightweight aggregate of lithium-based slag. The raw materials of the non-fired lightweight aggregate do not contain activators and curing agents, and include lithium spodumene slag, gypsum slag, and ordinary 425 silicate cement as a binder. The mass ratio of lithium spodumene slag, gypsum slag, and ordinary 425 silicate cement is 45:40:15.

[0070] The preparation method of the non-fired lightweight aggregate of the lithium-based slag is as follows: Figure 1 As shown:

[0071] Weigh out the corresponding amounts of spodumene lithium extraction slag, gypsum slag, binder, and ordinary 425 silicate cement according to the raw material formula.

[0072] (1) Lithium spodumene slag and gypsum slag are mixed in proportion and ball-milled at 1000 r / min for 40 min to obtain composite slag material. Cement is added to the composite slag material and mixed and stirred for 35 min to obtain a mixture material.

[0073] (2) Place the mixture in a disc granulator and add water accounting for 30% of the total mass of the mixture. By controlling the rotation speed of the disc granulator to 30 r / min and the tilt angle to 50°, raw material balls with a diameter distribution of 5 mm to 35 mm are prepared.

[0074] (3) Place the obtained raw material balls into a curing box and steam-cur them at 80°C and 95% humidity for 10 hours to obtain the lithium-based slag non-fired lightweight aggregate finished product.

[0075] Example 3

[0076] This embodiment provides a non-fired lightweight aggregate of lithium-based slag. The raw materials of the non-fired lightweight aggregate do not contain activators and curing agents, and include lithium spodumene slag, gypsum slag, and ordinary 425 silicate cement as a binder. The mass ratio of lithium spodumene slag, gypsum slag, and ordinary 425 silicate cement is 40:35:25.

[0077] The preparation method of the non-fired lightweight aggregate of the lithium-based slag is as follows:

[0078] Weigh out the corresponding amounts of spodumene lithium extraction slag, gypsum slag, binder, and ordinary 425 silicate cement according to the raw material formula.

[0079] (1) Lithium spodumene slag and gypsum slag are mixed in proportion and ball-milled at 1000 r / min for 45 min to obtain composite slag material. Cement is added to the composite slag material and mixed and stirred for 25 min to obtain a mixture material.

[0080] (2) Place the mixture in a disc granulator and add water accounting for 30% of the total mass of the mixture. By controlling the rotation speed of the disc granulator to 25 r / min and the tilt angle to 60°, raw material balls with a diameter distribution of 5 mm to 35 mm are prepared.

[0081] (3) Place the obtained raw material balls into a curing box and steam-cur them at 80°C and 95% humidity for 12 hours to obtain the lithium-based slag non-fired lightweight aggregate finished product.

[0082] Example 4

[0083] The difference between this embodiment and Embodiment 1 is that the mass ratio of spodumene slag, gypsum slag, and ordinary 425 silicate in this embodiment is 60:15:25.

[0084] All other conditions remain the same as in Example 1.

[0085] Example 5

[0086] The difference between this embodiment and Embodiment 1 is that the mass ratio of spodumene slag, gypsum slag, and ordinary 425 silicate in this embodiment is 40:40:20.

[0087] All other conditions remain the same as in Example 1.

[0088] Example 6

[0089] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of spodumene slag, gypsum slag, and ordinary 425 silicate is 35:35:30.

[0090] All other conditions remain the same as in Example 1.

[0091] Example 7

[0092] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of spodumene slag, gypsum slag, and ordinary 425 silicate is 63:35:2.

[0093] All other conditions remain the same as in Example 1.

[0094] Example 8

[0095] The difference between this embodiment and Embodiment 1 is that the mass ratio of spodumene slag, gypsum slag, and ordinary 425 silicate in this embodiment is 55:10:35.

[0096] All other conditions remain the same as in Example 1.

[0097] Example 9

[0098] The difference between this embodiment and Embodiment 1 is that the mass ratio of spodumene slag, gypsum slag, and ordinary 425 silicate in this embodiment is 55:43:2.

[0099] All other conditions remain the same as in Example 1.

[0100] Comparative Example 1

[0101] This comparative example provides a non-fired lightweight aggregate based on lithium slag. The raw materials of the non-fired lightweight aggregate do not contain activators and curing agents, and include lithium spodumene-derived slag, gypsum slag, ordinary 425 silicate cement as binder, calcium oxide as activator, and dicalcium diphosphate as curing agent. The mass ratio of lithium spodumene-derived slag, gypsum slag, ordinary 425 silicate cement as binder, calcium oxide as activator, and dicalcium diphosphate as curing agent is 75:5:13:5:2.

[0102] The preparation method of the non-fired lightweight aggregate of the lithium-based slag is as follows:

[0103] Weigh out the corresponding amounts of spodumene lithium extraction slag, gypsum slag, ordinary 425 silicate cement as binder, calcium oxide as activator, and dicalcium phosphate as curing agent according to the raw material formula.

[0104] (1) Lithium spodumene slag and gypsum slag are mixed in proportion and ball-milled at 1200 r / min for 60 min to obtain composite slag material. Cement, activator and curing agent are added to the composite slag material and mixed and stirred for 60 min to obtain a mixture material.

[0105] (2) The mixture is placed in a disc granulator, and raw material balls with a diameter distribution of 5 mm to 35 mm are prepared by controlling the rotation speed of the disc granulator to 20 r / min and the tilt angle to 60°.

[0106] (3) Place the obtained raw material balls into a curing box and steam-cur them at 80°C and 95% humidity for 12 hours to obtain the lithium-based slag non-fired lightweight aggregate finished product.

[0107] Comparative Example 2

[0108] This comparative example provides a non-fired lightweight aggregate based on lithium slag. The raw materials of the non-fired lightweight aggregate do not contain activators and curing agents, and include spodumene lithium extraction slag, fly ash, ordinary 425 silicate cement as binder, calcium oxide as activator, and dicalcium phosphate as curing agent. The mass ratio of spodumene lithium extraction slag, gypsum slag, ordinary 425 silicate cement as binder, calcium oxide as activator, and dicalcium phosphate as curing agent is 60:25:8:5:2.

[0109] The preparation method of the non-fired lightweight aggregate of the lithium-based slag is as follows:

[0110] Weigh out the appropriate amounts of spodumene lithium extraction slag, fly ash, ordinary 425 silicate cement (binder), calcium oxide (activator), and dicalcium phosphate (curing agent) according to the raw material formula.

[0111] (1) Lithium spodumene slag and fly ash are mixed in proportion and ball-milled at 1000 r / min for 45 min to obtain composite slag material. Cement, activator and curing agent are added to the composite slag material and mixed and stirred for 25 min to obtain a mixture material.

[0112] (2) The mixture is placed in a disc granulator, and raw material balls with a diameter distribution of 5 mm to 35 mm are prepared by controlling the rotation speed of the disc granulator to 25 r / min and the tilt angle to 60°.

[0113] (3) Place the obtained raw material balls into a curing box and steam-cur them at 80°C and 95% humidity for 12 hours to obtain the lithium-based slag non-fired lightweight aggregate finished product.

[0114] Performance testing

[0115] The non-fired lightweight aggregates of lithium-based slag prepared in the examples and comparative examples were tested for bulk density, compressive strength, and water absorption rate (1h water absorption rate) according to GB / T 17431.2-2010. The leaching rate of beryllium in the non-fired lightweight aggregates of lithium-based slag was leached using the sulfuric acid-nitric acid method according to GB 5085.3-2007 (the qualified standard is 0.02mg / L), and ICP-MS was used for detection. The test results are shown in Table 2.

[0116] Table 2

[0117]

[0118] From Table 2, we can obtain:

[0119] This invention achieves comparable or even superior results to existing methods that involve adding gypsum residue instead of fly ash, activators, and curing agents. The result is a non-fired lightweight aggregate with high compressive strength, low water absorption, low bulk density, and low beryllium leaching rate.

[0120] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A non-fired lightweight aggregate for lithium extraction from spodumene, characterized in that, The raw materials for the non-fired lightweight aggregate include lithium spodumene slag, gypsum slag, and binder.

2. The non-fired lightweight aggregate of spodumene lithium extraction slag according to claim 1, characterized in that, Based on the total mass of the spodumene lithium extraction slag, the gypsum slag, and the binder being 100%, the mass percentage of the spodumene lithium extraction slag is 40% to 60%. Preferably, based on the total mass of the spodumene lithium extraction slag, the gypsum slag, and the binder as 100%, the mass percentage of the gypsum slag is 15% to 40%. Preferably, the mass percentage of the binder is 5% to 25%, based on the total mass of the spodumene lithium extraction slag, the gypsum slag, and the binder as 100%.

3. The non-fired lightweight aggregate of spodumene lithium extraction slag according to claim 1, characterized in that, The gypsum residue has a purity >70%, a moisture content <25%, and a pH value >7.

4. The non-fired lightweight aggregate of spodumene lithium extraction slag according to claim 1 or 2, characterized in that, The total moisture content of the raw materials for the non-fired lightweight aggregate is 10% to 30%. Preferably, the adhesive comprises cement.

5. The non-fired lightweight aggregate of spodumene lithium extraction slag according to claim 1, characterized in that, The concentration of beryllium in the non-fired lightweight aggregate of the spodumene lithium extraction slag after toxic leaching is <0.001 mg / L.

6. A method for preparing non-fired lightweight aggregate from spodumene lithium extraction slag as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Mix spodumene lithium extraction slag, gypsum slag and binder to obtain a mixture; (2) The mixture is granulated to obtain raw material pellets; (3) Curing the raw material balls to obtain the non-fired lightweight aggregate of the lithium spodumene lithium extraction slag.

7. The preparation method according to claim 6, characterized in that, The mixing method in step (1) includes: first mixing spodumene lithium extraction slag and gypsum slag, and then adding a binder for a second mixing.

8. The preparation method according to claim 7, characterized in that, The first mixing method includes ball milling, and the second mixing method includes stirring; Preferably, the ball milling time is 60 min to 90 min; Preferably, the stirring time is 30 min to 60 min.

9. The preparation method according to claim 6, characterized in that, The granulation method described in step (2) includes roller pressing granulation or disc granulation; Preferably, the loading pressure of the roller granulation is 1kN~5kN, and the rotation speed of the roller granulation is 150rpm~250rpm; Preferably, the rotational speed of the disc granulator is 25 r / min to 35 r / min; Preferably, the diameter of the raw material ball in step (2) is 5mm to 25mm.

10. The preparation method according to claim 6, characterized in that, The curing method in step (3) includes steam curing, wherein the temperature of the steam curing is 60℃~100℃, the humidity of the steam curing is 90%~99%, and the steam curing time is 6h~12h.

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