Slow-release wrapping material for thallium solidification, preparation method and application

Abstract

The invention discloses a sustained-release wrapping material for thallium immobilization, a preparation method and application, the wrapping material uses a mixture composed of an aluminosilicate carrier and an organic sulfur chelating agent loaded on the carrier as a core-spun material, and hydroxide and / or carbonate as a coating material to wrap the core-spun material. The preparation method comprises the following steps: firstly, adding the organic sulfur chelating agent into the aluminosilicate carrier, adding water, uniformly stirring, then adding the binder, and carrying out primary granulation and drying to obtain the core-spun material; and mixing the hydroxide and / or carbonate with the core-spun material, adding water to prepare slurry, and performing secondary granulation and drying. The slow-release wrapping material can efficiently act on the lepidolite tailings for a long time, so that the leaching toxicity of thallium in the lepidolite tailings is always maintained at a relatively low level, and the slow-release wrapping material has the characteristics of high stabilization rate, stable performance, long-term effectiveness, easiness in storage and easiness in use. The slow-release wrapping material is wide in application range, is not only suitable for thallium-containing lepidolite tailings, but also suitable for thallium-containing sludge, thallium-containing wastewater and the like, and is short in production process flow, simple to use and operate and wide in application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of thallium fixation, and in particular relates to a sustained-release packaging material for thallium fixation, a preparation method and application thereof. Background Art

[0002] Thallium is a common and highly toxic element. With the development of industry, a large amount of thallium enters the environment through smelting, chemical industry and other means. Among them, lithium clay, lithium porcelain stone and lithium mica are often accompanied by trace amounts of thallium. During the high-temperature calcination process of thallium-containing lithium ore, lithium, thallium and other elements in the ore are activated, and some activated thallium elements still remain in the tailings. At this stage, the disposal method is still mainly based on tailings pond storage. During the storage process, thallium-containing tailings can easily enter the surface water through rainwater leaching or flushing water. Heavy metal thallium has strong biological toxicity, mobility, and valence state diversity. It can easily enter the body of animals and plants through enrichment, causing harm to the ecological environment and human health.

[0003] The prior art has adopted relevant technologies to treat the solidification of thallium in the tailings after lithium extraction from lithium ore.

[0004] For example, the invention with publication number CN117534357A adopts a high-temperature curing method, that is, by mixing lithium mica waste slag with high-calcium, high-silicon, high-aluminum and other materials, grinding, high-temperature roasting, cooling, and finally grinding into an inert ceramic material, the purpose of reducing the dissolution problem of thallium in lithium mica slag is achieved.

[0005] Another example is the invention with publication number CN110203995A, which adopts the method of oxidative alkaline precipitation, that is, by adding water and an oxidant to the active aluminum silicate material prepared by calcination, mixing, drying and crushing, a thallium pollution deep curing agent is obtained. The curing agent can form insoluble substances with thallium and thallium compounds, thereby achieving the effect of efficiently, permanently and stably curing the thallium of the pollution source.

[0006] Another example is the invention with publication number CN117945580A, which adopts the method of sulfidation precipitation, that is, chlorine gas is used to oxidize Tl + , precipitated with sulfide thallium removal agent, and finally precipitated again with potassium ferrate and manganese chloride.

[0007] However, the above existing technologies still have some drawbacks in practical application. For example, the high temperature curing method will cause high energy consumption of high temperature roasting. The oxidation alkaline precipitation method has complicated preparation steps, which is not conducive to large-scale industrial promotion. The sulfide precipitation method may produce hydrogen sulfide during the use of sulfide reagents, causing secondary pollution.

[0008] The most important point is that the existing technologies all achieve the purpose of fixing thallium by a quick method. However, in the actual process, since the thallium-containing tailings are constantly affected by external environmental factors during the storage process, some thallium elements will be leached again. The existing thallium fixing method can temporarily fix the leached thallium, but it cannot achieve the purpose of long-term and lasting consolidation for the subsequent gradually leached thallium.

[0009] Based on this, there is an urgent need for a slow-release thallium-fixing material that can act on thallium-containing lithium ore tailings for a long time and efficiently, so as to ensure that the thallium leaching toxicity in the thallium-containing lithium ore tailings is always maintained at a low level. Summary of the invention

[0010] Purpose of the invention: The technical problem to be solved by the present invention is to provide a solid thallium sustained-release packaging material, preparation method and application which can act on thallium-containing lithium ore tailings for a long time and efficiently, thereby ensuring that the thallium leaching toxicity in the thallium-containing lithium ore tailings is always maintained at a low level.

[0011] Technical solution: The invention discloses a sustained-release wrapping material for fixing thallium. The wrapping material uses a mixture of an aluminosilicate carrier and an organic sulfur chelating agent loaded on the carrier as a core material, and uses hydroxide and / or carbonate as a coating material coated on the core material; the mass ratio of the coating material to the core material is (1:3) to (3:1).

[0012] The present invention uses a mixture of an aluminosilicate carrier and an organic sulfur chelating agent loaded on the carrier as a core material, and uses a hydroxide and / or carbonate coated on the surface of the core material as a coating. On the one hand, with the aid of the hydroxide and / or carbonate coating formed by the aluminosilicate carrier, it can be slowly dissolved under external environmental conditions, and after dissolution, it can form an insoluble thallium hydroxide precipitate with trivalent thallium, and the thallium ions are not easy to dissolve back under natural conditions, so as to achieve the slow dissolution of the outer coating and solidify thallium; at the same time, with the aid of the organic sulfur chelating agent in the core layer of the aluminosilicate carrier, it can be slowly released under the coating of the outer alkaline material, and can simultaneously chelate with monovalent thallium and trivalent thallium to form an insoluble precipitate, and with the aid of the precipitation generated by the adsorption of the zeolite with a large specific surface area and a porous structure in the core, the thallium ions are not easy to dissolve back under natural conditions, and the long-term solidification of thallium in the natural environment can be achieved, so as to finally achieve the slow release and solidification of thallium in the inner and outer double layers.

[0013] On the other hand, with the aid of the hydroxide and / or carbonate coating formed by the aluminosilicate carrier, the pH value can be slowly released to adjust the pH value, thereby placing the thallium-containing lithium ore tailings in a weakly alkaline condition. Based on the weakly alkaline condition, the thallium in the thallium-containing lithium ore tailings is not released as much as possible or is slowly released, and the slowly released thallium reacts with the slowly released inner and outer double-layer organic sulfur chelating agent and the hydroxide and / or carbonate to form a precipitate, thereby ultimately achieving the purpose of long-term thallium fixation.

[0014] Furthermore, the mass ratio of the organic sulfur chelating agent to the aluminosilicate carrier of the sustained-release packaging material can be (0.05-0.25):1.

[0015] Furthermore, the organic sulfur chelating agent of the sustained-release packaging material may include at least one of sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, trisodium trithiol-s-triazine, and potassium piperazine-N,N'-bisdithiocarboxylate.

[0016] Furthermore, the aluminosilicate carrier of the sustained-release packaging material may be zeolite and / or sepiolite.

[0017] Furthermore, the hydroxide of the sustained-release packaging material may include at least one of magnesium hydroxide, calcium hydroxide or barium hydroxide; and the carbonate may include at least one of calcium carbonate, magnesium carbonate or barium carbonate.

[0018] The method for preparing the above-mentioned sustained-release packaging material of the present invention comprises the following steps:

[0019] (1) adding an organic sulfur chelating agent to an aluminosilicate carrier, adding water and stirring evenly, and then adding a binder, granulating and drying once to obtain a core material;

[0020] (2) After the hydroxide and / or carbonate is mixed with the core material, water is added to make a slurry, and then secondary granulation and drying are performed.

[0021] Furthermore, in step (1) of preparing the sustained-release packaging material of the present invention, the binder may include at least one of bentonite, kaolin, montmorillonite or illite, and the amount added is 1.0-5.0% of the total mass of the organic chelating agent and the aluminosilicate material.

[0022] Furthermore, in step (1) of preparing the sustained-release packaging material of the present invention, the amount of water added is 5-15% of the total mass of the organic chelating agent and the aluminosilicate material.

[0023] Furthermore, in the step of preparing the sustained-release packaging material of the present invention, the average particle size of the primary granulation is 2 to 4 mm, and the average particle size of the secondary granulation is 3 to 6 mm.

[0024] The slow-release wrapping material of the present invention is used to fix thallium in lepidolite tailings, comprising the following steps: adding the slow-release wrapping material to the lepidolite tailings at a mass ratio of (1-20):1000 and mixing evenly.

[0025] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the slow-release wrapping material uses a mixture of an aluminosilicate carrier and an organic sulfur chelating agent loaded on the carrier as the core material, hydroxide and / or carbonate as the coating material, and is prepared into slow-release particles through granulation and drying, which can act on the lithium mica tailings for a long time and efficiently, thereby ensuring that the thallium leaching toxicity in the lithium mica tailings is always maintained at a low level, and has the characteristics of high stabilization rate, stable performance, long-term effectiveness, easy storage and easy use. And the slow-release wrapping material has a wide range of applications, not only suitable for lithium mica tailings containing thallium, but also suitable for thallium-containing sludge, thallium-containing wastewater, etc., with a short production process, simple operation, and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The thallium leaching toxicity concentration diagram after the application of the packaging materials prepared in Examples 1 to 6;

[0027] Figure 2 The pH value diagram of the toxic leachate after the wrapping materials prepared in Examples 1 to 6 are used;

[0028] Figure 3 The thallium leaching toxicity concentration diagram of the packaging material of Example 1 under different curing times and different mass ratio conditions;

[0029] Figure 4 The figure is a graph of thallium leaching toxicity concentration of the packaging material of Example 1 under different moisture contents. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below in conjunction with embodiments.

[0031] It should be noted that the raw materials used in the present invention can all be purchased from commercial sources.

[0032] Example 1

[0033] The sustained-release packaging material of Example 1 is prepared by the following steps:

[0034] (1) adding water to potassium piperazine-N,N'-bisdithiocarboxylate to prepare a solution with a mass fraction of 40%; under stirring, according to the mass ratio of potassium piperazine-N,N'-bisdithiocarboxylate to zeolite being 0.1:1, adding the potassium piperazine-N,N'-bisdithiocarboxylate solution to the zeolite, and continuing stirring for 10 minutes.

[0035] (2) Adding bentonite, a binder accounting for 3% of the total mass (by dry weight) of potassium piperazine-N,N'-bis(dithiocarboxylate) and zeolite to step (1), continuing stirring for 10 minutes to start primary granulation, and drying at 60-110°C through a 4 mm sieve to obtain a coating core.

[0036] (3) Add the coating core to calcium hydroxide at a mass ratio of 1:1, add water accounting for 20% of the total mass of the coating core and calcium hydroxide, stir for 20 minutes to start secondary granulation, pass through a 5 mm sieve and dry at 60-110° C. to obtain a sustained-release coating material.

[0037] Example 2

[0038] This Example 2 is substantially the same as Example 1, except that the organic sulfur chelating agent is sodium dimethyldithiocarbamate.

[0039] Example 3

[0040] This Example 3 is substantially the same as Example 1, except that the organic sulfur chelating agent is sodium diethyldithiocarbamate.

[0041] Example 4

[0042] This Example 4 is substantially the same as Example 1, except that the organic sulfur chelating agent is trisodium trimercapto-s-triazine.

[0043] Example 5

[0044] This Example 5 is basically the same as Example 1, except that the mass ratio of the coating core to calcium hydroxide is 0.5:1.

[0045] Example 6

[0046] This Example 6 is basically the same as Example 1, except that the mass ratio of the coating core to calcium hydroxide is 1.5:1.

[0047] Comparative Example 1

[0048] This comparative example is basically the same as Example 1, except that only the core material is prepared, which specifically includes the following steps:

[0049] (1) adding water to potassium piperazine-N,N'-bisdithiocarboxylate to prepare a solution with a mass fraction of 40%; under stirring, according to the mass ratio of potassium piperazine-N,N'-bisdithiocarboxylate to zeolite being 0.1:1, adding the potassium piperazine-N,N'-bisdithiocarboxylate solution to the zeolite, and continuing stirring for 10 minutes.

[0050] (2) Adding bentonite, a binder accounting for 3% of the total mass (by dry weight) of potassium piperazine-N,N'-bis(dithiocarboxylate) and zeolite to step (1), continuing stirring for 10 minutes to start primary granulation, and drying at 60-110°C through a 4 mm sieve to obtain a coating core.

[0051] Application 1: Thallium-fixing with the wrapping material of Examples 1 to 6

[0052] The slow-release package material prepared by Example 1 to Example 6 is added to the lepidolite tailings at a mass ratio of 10:1000, mixed evenly, and watered for curing so that the water content in the lepidolite tailings is 20%, and the curing time is 1 day. Wherein, the lepidolite tailings for effect verification come from a lithium carbonate factory in Yichun, and according to the standard of "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method" (HJ / T299-2007), a toxicity leaching test of thallium Tl is carried out using a turnover oscillator, wherein the thallium leaching toxicity is 68.4 μg / L, and the acid leaching solution pH is 6.84.

[0053] The solid thallium data of the package materials of Example 1 to Example 6 were tested, and the results obtained were as follows: Figure 1 and Figure 2 As shown. As can be seen from the figure, after adding the sustained-release wrapping materials of Examples 1 to 6, the leaching toxicity of thallium is 1.03μg / L, 21.32μg / L, 19.92μg / L, 17.15μg / L, 3.67μg / L, and 0.84μg / L, respectively; the corresponding pH values ​​are 8.74, 8.64, 8.69, 8.37, 9.54, and 8.51, respectively. It can be seen that the sustained-release wrapping material of the present invention can slowly release and adjust the pH value, thereby making the thallium-containing lithium ore tailings in a weakly alkaline condition, and the sustained-release wrapping material can effectively solidify the leached thallium.

[0054] Application 2: Thallium fixation of the wrapping material of Example 1 under different curing times and different mass ratios

[0055] The sustained-release packaging material prepared in Example 1 of the present invention was added to the lithium mica tailings in different mass ratios, and the thallium leaching toxicity concentration was measured for different curing times, as shown in Tables 1 and Figure 3 shown.

[0056] Table 1 Leaching toxicity concentrations of different amounts of packaging materials of the embodiments added at different curing times

[0057]

[0058]

[0059] Through Table 1 and Figure 3 It can be seen that the sustained-release packaging material prepared by the present invention can still maintain a relatively good thallium fixing effect after being placed for 180 days, and the leaching toxicity concentration of thallium shows a stable trend.

[0060] Application 3: Solidification of thallium under different moisture content conditions of the wrapping material of Example 1

[0061] The sustained-release wrapping material prepared in Example 1 was added to the lithium mica tailings at a mass ratio of 10:1000, and water was added to control the moisture content of the lithium mica tailings to 15%, 20%, 25%, and 30%, respectively. After curing for 1 day, samples were taken for leaching toxicity experiments to determine the thallium leaching toxicity concentration. Figure 4 As shown, the leaching toxicity of thallium is 3.07 μg / L, 1.03 μg / L, 0.95 μg / L, and 0.89 μg / L, respectively. It can be seen that the present invention can maintain a better thallium fixation performance when the water content in the lepidolite tailings is between 15% and 30%.

[0062] Application 4: Thallium-solidifying materials of Example 1 and Comparative Example 1 at different curing times

[0063] The sustained-release packaging material prepared in Example 1 of the present invention and the solid thallium material prepared in Comparative Example 1 were added to the lithium mica tailings at a mass ratio of 10:1000, and the thallium leaching toxicity concentration was measured after curing for different time periods, as shown in Table 2 below.

[0064] Table 2 Leaching toxicity concentration of thallium-solidified materials of Example 1 and Comparative Example 1 at different curing times

[0065]

[0066] It can be seen from the thallium leaching toxicity concentrations of Comparative Example 1 and Example 1 in Table 2 that the wrapping material prepared by the present invention, under the joint action of the core material and the coating material, can enable the wrapping material to achieve sustained release and long-term stable solidification of thallium. Second, the core material alone is used to solidify thallium. Although it can effectively solidify thallium at the beginning, the thallium leaching toxicity shows an increasing pattern over a long period of time. It can be seen that the core material alone cannot achieve the effect of long-term sustained release and stable solidification of thallium.

[0067] In addition to the above embodiments, in the wrapping material of the present invention, the mass ratio of the core material to the coating material can also be (1:3) to (3:1). The aluminosilicate carrier in the core material can be zeolite and / or sepiolite; the mass ratio of the organic sulfur chelating agent to the aluminosilicate carrier can be (0.05 to 0.25):1.

[0068] The coating material may be hydroxide and / or carbonate, and the mass fraction of calcium hydroxide is 75-100%, and the mass fraction of calcium carbonate is 0-25%. The hydroxide may include at least one of magnesium hydroxide, calcium hydroxide or barium hydroxide; and the carbonate may include at least one of calcium carbonate, magnesium carbonate or barium carbonate.

[0069] That is, the packaging materials prepared by using the above raw materials can achieve the effects of sustained release and long-term thallium fixation claimed in the present invention.

[0070] In addition, when preparing the core material, the binder used in the present invention accounts for 1.0-5.0% of the total mass of the organic chelating agent and the aluminosilicate material, and the binder may include at least one of bentonite, kaolin, montmorillonite or illite. The average particle size of the primary granulation is 2-4 mm.

[0071] When preparing the above-mentioned coating material in the present invention, the amount of water added for pulping is 5-15% of the total mass of the organic chelating agent and the aluminosilicate material.

[0072] That is, the packaging materials prepared by adopting the above preparation process steps and the defined process parameter conditions can achieve the above-mentioned sustained release and long-term thallium fixation effects claimed in the present invention.

Claims

1. A sustained-release packaging material for fixing thallium, characterized in that: The coating material uses a mixture of an aluminosilicate carrier and an organic sulfur chelating agent loaded on the carrier as a core material, and uses hydroxide and / or carbonate as a coating material coated on the core material; the mass ratio of the coating material to the core material is (1:3) to (3:1).

2. The sustained-release packaging material for fixing thallium according to claim 1, characterized in that: The mass ratio of the organic sulfur chelating agent to the aluminosilicate carrier is (0.05-0.25):

1.

3. The sustained-release packaging material for fixing thallium according to claim 1 or 2, characterized in that: The organic sulfur chelating agent includes at least one of sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, trisodium trithiol-s-triazine, and potassium piperazine-N,N'-bisdithiocarboxylate.

4. The sustained-release packaging material for fixing thallium according to claim 1 or 2, characterized in that: The aluminosilicate carrier is zeolite and / or sepiolite.

5. The sustained-release packaging material for fixing thallium according to claim 1, characterized in that: The hydroxide includes at least one of magnesium hydroxide, calcium hydroxide or barium hydroxide; the carbonate includes at least one of calcium carbonate, magnesium carbonate or barium carbonate.

6. A method for preparing the sustained-release packaging material according to claim 1, characterized in that: The steps include: (1) adding an organic sulfur chelating agent to an aluminosilicate carrier, adding water and stirring evenly, and then adding a binder, granulating and drying once to obtain a core material; (2) After the hydroxide and / or carbonate is mixed with the core coating material, water is added to make a slurry, and the sustained-release coating material is obtained by secondary granulation and drying.

7. The method for preparing a sustained-release packaging material according to claim 6, characterized in that: In step (1), the binder includes at least one of bentonite, kaolin, montmorillonite or illite, and the amount added is 1.0-5.0% of the total mass of the organic chelating agent and the aluminosilicate material.

8. The method for preparing a sustained-release packaging material according to claim 6, characterized in that: In step (1), the amount of water added is 5-15% of the total mass of the organic chelating agent and the aluminosilicate material.

9. The method for preparing a sustained-release packaging material according to claim 6, characterized in that: The average particle size of the primary granulation is 2-4 mm, and the average particle size of the secondary granulation is 3-6 mm.

10. The sustained-release packaging material according to claim 1 is used to fix thallium in lepidolite tailings, characterized in that: The method comprises the following steps: adding the slow-release wrapping material into the lithium mica tailings according to a mass ratio of (1-20):1000, and mixing them evenly.

Images