Method for solidifying thallium and resource utilization of spodumene ore waste residue and building raw materials

Abstract

The present invention provides a method for solid thallium treatment and resource utilization of lepidolite ore waste residue and a building raw material. The method comprises the following steps: Mixing: fully mixing lepidolite waste, industrial materials containing components of calcium oxide, aluminum oxide and silicon dioxide, and functional auxiliary materials in proportion to form a mixture, so that the content of calcium oxide in the mixture is not less than 30%, the content of silicon dioxide is not less than 25%, and the content of aluminum oxide is not less than 6%; Sintering: putting the powder obtained by grinding into a rotary kiln for calcination, and controlling the powder to stay in the high-temperature zone where it reaches the molten state for not less than 10 min during calcination; Quick cooling: discharging the molten slurry from the rotary kiln and cooling it by air cooling or water cooling; Secondary grinding: grinding the cooling product obtained by quick cooling to a fineness of 380-450 kg / m2. The technical solution of the present invention forms an inert ceramic material by combining silicate components and components of functional auxiliary materials with thallium in a high-temperature molten state, avoiding the existence of thallium in an ionic state, and can effectively solve the problem of thallium dissolution in lepidolite slag.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment of lepidolite ore, and specifically relates to a method for solid thallium treatment and resource utilization of lepidolite ore waste residue and a building raw material obtained by this method. Background Art

[0002] Lithium is one of the key materials in the contemporary green energy field and is widely used in batteries, energy storage, materials and many other fields. Thallium often occurs in association with lithium ore. Especially for lepidolite ore, the dissolution rate of thallium in the waste residue after lithium extraction is very high. Thallium and its compounds are highly toxic substances.

[0003] The lepidolite slag produced after preparing lithium salts from lepidolite ore contains a high concentration of thallium. At present, only the method of stacking can be adopted, and special strict anti-seepage and anti-leakage measures must be taken for the lithium slag storage. This not only brings a serious economic burden to lithium mining enterprises, but also poses a great environmental protection risk. Moreover, as the cumulative amount of waste residue increases, lithium mining enterprises must solve the problem of harmless treatment of lepidolite slag and realize resource utilization.

[0004] Some patents have presented technologies for treating thallium in solid waste. Patent CN202210964379.2, a method for stabilizing thallium-containing sludge, is as follows: (1) Add an oxidant to the thallium-containing sludge and stir until oxidation is complete; (2) Add a solidifying agent to the mixture obtained in the previous step, adjust the pH to 10 - 14 with alkali, and carry out a fixing reaction at a temperature of 120 - 140 °C. After the reaction is completed, the solid-liquid separation of the material is carried out to obtain the fixed liquid and the solidified product; the solidifying agent is one or a combination of two of K3PO4 and Na2SiO3. This method has a complex process and high treatment costs, and is not suitable for large-scale treatment of thallium-containing solid waste. Patent CN201910532842.4 discloses a deep thallium pollution solidifying agent, its preparation method and application, which is to mix silicon-aluminum minerals, calcium-magnesium auxiliary agents and fluxes evenly, and obtain an active aluminosilicate material after roasting; add water and an oxidant to the active aluminosilicate material, mix evenly, and dry and crush the obtained slurry to obtain a deep thallium pollution solidifying agent. This solidifying agent can stably combine with thallium and its compounds to form insoluble substances, achieving the effect of efficiently, permanently and stably solidifying the thallium pollution source. However, the composition and preparation method of this solidifying agent are complex and the cost is relatively high. Patent CN107486464A discloses a method for disposing of thallium-containing solid waste, which uses polyacrylate emulsion, ethylene vinyl acetate copolymer emulsion and cement to prepare a thermosetting encapsulating material; the solidifying material and the thallium-containing solid waste are mixed and cured to complete the disposal of the thallium-containing solid waste. This method uses the film-forming property of the organic matter emulsion to wrap thallium, but the formed film has an aging problem. After several years, the long-chain structure breaks, and the wrapping function will weaken or even be lost, and the thallium-containing solid waste after treatment still needs to be stored in a heap. Patent CN116891952A discloses a method for solidifying thallium by roasting lepidolite, and the steps are as follows: 1) Crush and screen the thallium-fixing agent to obtain fine powders of the thallium-fixing agent; 2) Mix the fine powders of the thallium-fixing agent and the lepidolite mixture evenly by pressing bricks to obtain bricks of the roasted mixture; 3) High-temperature roast the bricks of the roasted mixture in a tunnel kiln, and carry out mechanical crushing and ball milling after roasting to obtain fine powders of the roasted and crushed material; 4) Add water to the roasted and crushed fine powder clinker and stir and mix fully for leaching, and carry out solid-liquid separation with a belt filter to obtain a qualified lithium-containing solution and leaching residue. This method fixes thallium by adding a small amount of thallium-fixing agent and roasting it together with lepidolite during the roasting process of lepidolite, so that all thallium is fixed in the slag during the leaching process and thallium cannot enter the solution, solving the problem of thallium polluting water resources from the source. The thallium-fixing agent is a mixture of potassium ferrate, polyferric sulfate, sodium phosphate and sodium silicate in a certain proportion, the high-temperature roasting temperature is 750 - 1200 °C, and the roasting time is 0.5 - 4.0 h. However, this method only solves the problem of thallium dissolution polluting water resources, and the generated waste residue still needs to be stored in a heap, without realizing the reduction of solid waste, and has a high roasting temperature, long time and high treatment costs.

[0005] Content of the invention patent

[0006] In view of the above problems, the present invention provides a method for the resource utilization of thallium-fixing in lepidolite ore waste residue and building raw materials obtained by this method. By means of calcination, the thallium dissolution in the waste residue is greatly reduced, and the product after calcination can be used as a building material after grinding, realizing the harmless treatment and resource utilization of lepidolite slag. The thallium-fixing method of the present invention is to mix lepidolite waste residue with high-calcium materials, high-silicon materials, high-aluminum materials and necessary auxiliary materials, grind them, roast them to a molten state at a high temperature of 1200-1500 °C, and the melt is rapidly air-cooled or water-cooled, and finally ground into a powdery product for use as a building material. The object of the present invention is achieved by the following method:

[0007] The present invention first provides a method for the resource utilization of thallium-fixing treatment of lepidolite ore waste residue, which includes the following steps:

[0008] Pretreatment: Select industrial materials containing calcium oxide, aluminum oxide and silicon dioxide components, and functional auxiliary materials as raw materials according to the components in the lepidolite waste. Measure the moisture content and the composition percentages of calcium oxide, silicon dioxide, aluminum oxide, magnesium oxide, iron oxide, etc. of the lepidolite waste residue and other raw materials, and dry each raw material;

[0009] Mixing: Mix the lepidolite waste, industrial materials containing calcium oxide, aluminum oxide and silicon dioxide components, and functional auxiliary materials in proportion to form a mixture, so that the calcium oxide content in the mixture is not less than 30%, preferably not less than 34%; the silicon dioxide content is not less than 25%, preferably not less than 28%; the aluminum oxide content is not less than 6%, preferably not less than 8%; the functional auxiliary materials include phosphates and silicates; Usually, in the original mixed materials, the proportion of lepidolite waste residue should not be less than 40% to efficiently consume this solid waste as much as possible;

[0010] Grinding: Grind the mixture into a powder with a fineness of 300-420 kg / m 2 of powder;

[0011] Sintering: Put the powder obtained by grinding into a rotary kiln for calcination. When calcining, control the powder to stay in the high-temperature zone where it reaches the molten state for not less than 10 min; preferably, the temperature of the high-temperature zone is 1200 °C - 1500 °C to ensure that the powder is calcined and melted into a liquid state. The calcination temperature depends on the properties of the lithium slag and other component properties used. If the temperature is lower than 1200 °C, it cannot be melted or the crystallization of products such as calcium silicate is insufficient. If the temperature is higher than 1500 °C, the energy consumption will be significantly increased and the economy is poor. The molten material stays in the high-temperature zone for not less than 10 min to fully generate hydraulic products such as calcium silicate and calcium aluminosilicate;.

[0012] Quenching: The molten slurry is discharged from the rotary kiln and immediately quenched. High-speed air quenching can be used, with the air speed not less than 10 m / s. The molten slurry can also fall into high-speed water flow for water quenching, with the water flow speed not less than 2 m / s, and the water flow rate should ensure that the melt can be submerged.

[0013] Secondary grinding: The cooled product obtained by quenching is ground to a fineness of 380 - 450 kg / m using a ball mill or a vertical mill. 2 A powder product is obtained. The hydration activity of the powder product obtained by the method of the present invention can reach the activity of S75 - S95 slag powder and can be used as a building material.

[0014] Preferably, the industrial materials include high-calcium materials and high-aluminum materials. The high-calcium materials include carbide slag and / or electric furnace phosphorous slag, and other industrial wastes with a high calcium oxide content can also be used, with the calcium oxide content not less than 40%. The high-aluminum materials include one or more of kaolin, clay, and bauxite, with the alumina content not less than 35%.

[0015] Furthermore, in the mixing step, the component ratios of each raw material are as follows: lithium mica waste residue 40 - 55%; high-calcium materials 30 - 50%; high-aluminum materials 0 - 20%; functional auxiliary materials 0.1 - 0.6%.

[0016] Preferably, the industrial materials also include corrective materials, which include calcium oxide with a purity of more than 92% and / or alumina with a purity of more than 92%. When the cumulative chemical composition of the mixed raw materials prepared from the aforementioned lithium mica slag, high-calcium materials, and high-aluminum materials cannot meet the predetermined requirements or the preparation efficiency is relatively low, adjustment can be made by adding corrective materials. At this time, the component ratios of each raw material in the mixing step are as follows: lithium mica waste residue 40 - 55%; high-calcium materials 30 - 50%; high-aluminum materials 0 - 20%; corrective materials 0 - 10%; functional auxiliary materials 0.1 - 0.6%.

[0017] Furthermore, the functional auxiliary materials include phosphate, silicate, and diatomaceous earth, and the mass ratio of each component is: phosphate: silicate: diatomaceous earth = (1 - 3): (1 - 3): (1 - 4).

[0018] Preferably, the phosphate includes industrial pure sodium phosphate and potassium phosphate, the silicate includes powdered sodium silicate, and the mass ratio of each component in the functional auxiliary materials is: sodium phosphate: potassium phosphate: sodium silicate: diatomaceous earth = 1: (0 - 2): (1 - 3): (1 - 4). By adding the above-mentioned phosphate, silicate, and diatomaceous earth and other components, an inert ceramic material is formed by reacting with thallium and other mineral components at high temperature, thereby reducing the content of thallium ions in the final product.

[0019] Preferably, for the requirements of each chemical composition in the mixing step, it refers to referring to the main chemical components of the granulated blast furnace slag powder, and specifically setting the basic composition of each component as follows: the calcium oxide content is 38 ± 4%, the silicon dioxide content is 33 ± 5%, the aluminum oxide content is 10 ± 4%, and the rest are other components. Through the method of the present invention, the powder product after secondary grinding has hydration activity and can be sold as an admixture for building materials. At present, it has become the hydraulic building cementing material second only to cement and has high hydration activity. The hydration activity mainly comes from minerals such as calcium silicate, calcium aluminate, and calcium aluminosilicate formed by the high-temperature melting of calcium oxide, silicon dioxide, and aluminum oxide.

[0020] The present invention further provides a building raw material, which is prepared by using the powder product after secondary grinding by the aforementioned method as a raw material component. The soluble thallium content in the powder product is not higher than 6 μg / kg, and this component is mainly used as a hydraulic building gel material; preferably, the soluble thallium content is not higher than 5.8 μg / kg. As previously known, the powder product has hydration activity and can be sold as an admixture for building materials, replacing traditional materials such as cement, slag powder, and fly ash, and is used in mine cemented backfilling, ground road and bridge construction, and other industrial building structures.

[0021] For the solution provided by the present invention, it can also be calcined according to the chemical composition of cement clinker, and the hydration cementing activity is better. At this time, the dosage of lepidolite waste residue is reduced to less than 20%, but such a method is not conducive to the large consumption of waste residue.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) Through the technical solution of the present invention, under the high-temperature melting state, the silicate group components and the components of the functional auxiliary materials combine with thallium to form an inert ceramic material, avoiding the existence of thallium in an ionic state, and achieving the purpose of reducing the dissolution problem of thallium in the lepidolite slag.

[0024] (2) The technical solution of the present invention is proportioned according to the mineral component ratio of the slag powder to form minerals with hydration activity. After calcination and melting, it is rapidly cooled and ground with reference to the cement process or the granulated blast furnace slag powder process. The product can be used as a building material, and the harmless treatment, resource utilization, and reduction of the thallium-containing lepidolite waste residue are realized at relatively low cost. Specific Embodiments

[0025] The following will further illustrate the present invention with specific embodiments. The following embodiments are only used to illustrate the present invention and not to limit the present invention.

[0026] Example 1:

[0027] This example provides a method for solidifying thallium and resource utilization of lepidolite ore waste residue, which includes the following steps:

[0028] Step S0 - Pretreatment: Select industrial materials containing calcium oxide, aluminum oxide, and silicon dioxide components, as well as functional auxiliary materials including sodium phosphate, potassium phosphate, sodium silicate, and diatomaceous earth as raw materials according to the components in the lepidolite waste. Measure the moisture content and the composition percentages of calcium oxide, silicon dioxide, aluminum oxide, magnesium oxide, iron oxide, etc. in the lepidolite waste residue and other raw materials, and dry each raw material;

[0029] Step S1 - Mixing: Mix the lepidolite waste, industrial materials containing calcium oxide, aluminum oxide, and silicon dioxide components, and functional auxiliary materials in the following proportions: 40 - 55% of lepidolite waste residue; 30 - 50% of high-calcium materials; 0 - 20% of high-aluminum materials; 0 - 10% of corrective materials; 0.1 - 0.6% of functional auxiliary materials to form a mixed material. Ensure that the calcium oxide content in the mixed material is not less than 34%; the silicon dioxide content is not less than 28%; the aluminum oxide content is not less than 8%;

[0030] Step S2 - Grinding: Grind the mixed material obtained in Step S1 into a powder with a fineness of 300 - 420 kg / m 2 using a ball mill or a vertical mill;

[0031] Step S3 - Sintering: Put the powder obtained by grinding in Step S2 into a rotary kiln for calcination. During calcination, control the powder to stay in the high-temperature zone of 1200°C - 1500°C for not less than 10 minutes;

[0032] Step S4 - Quenching: Unload the molten slurry sintered in Step S3 from the rotary kiln and immediately perform quenching treatment. High-speed air quenching can be used, with the wind speed not less than 10 m / s. The molten slurry can also fall into high-speed water flow for water quenching, with the water flow speed not less than 2 m / s, and the water flow rate needs to ensure that the molten body can be submerged;

[0033] Step S5 - Secondary Grinding: Grind the cooled product obtained by quenching in Step S4 into a powder with a fineness of 380 - 450 kg / m 2 to obtain a powder product. Usually, the soluble thallium content in this powder product is not higher than 6 μg / kg.

[0034] In a specific embodiment, the chemical compositions of the various raw materials measured by analysis are as follows:

[0035] The chemical composition of the lepidolite waste residue is:

[0036] Chemical composition CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[Na2O]]> <![CDATA[K2O]]> Others Percentage content 1.4 62.24 16.38 0.59 3.96 3.74 9.62

[0037] The chemical composition of carbide slag is:

[0038] Chemical composition CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> Loss on ignition and others Percentage content 71.32 1.42 1.33 0.17 25.76

[0039] The chemical composition of kaolin is:

[0040]

[0041] The chemical composition of bauxite is as follows:

[0042]

[0043] The chemical composition of industrial high-purity calcium oxide is as follows:

[0044]

[0045] Example 2

[0046] The principle of this example is the same as that of Example 1. Using the relevant raw materials provided in Example 1, the proportioning is as follows:

[0047] Leptite waste residue 50%

[0048] Calcium carbide slag 49.8%

[0049] Functional auxiliary materials 0.2%

[0050] The chemical composition of the obtained mixture is shown in Table 2-1:

[0051] Table 2-1 Chemical composition ratio of the mixture in Example 2

[0052] Chemical composition CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[Na2O]]> <![CDATA[K2O]]> Others Percentage content 36.62 31.83 8.85 0.58 1.98 1.87 18.37

[0053] Mix the above ingredients (dry basis), grind them, calcine at 1350 °C for 15 minutes, quench with water and cool rapidly, and then grind them for the second time to a fineness of 425 kg / m 2 Obtain a powder product. The hydration activity of the powder product is tested according to the test method of Standard GB / T 18046-2008 "Ground granulated blast-furnace slag for use in cement and concrete", and the soluble thallium content of the leptite ore waste residue and the calcined powder is determined according to the Standard HJ 748-2015 "Determination of thallium in water - Graphite furnace atomic absorption spectrometry". The determination results are shown in Table 2-2:

[0054] Table 2-2 Determination results of soluble thallium content of the powder product obtained in Example 2

[0055]

[0056] Example 3

[0057] The principle of this example is the same as that of Example 1. Using the relevant raw materials provided in Example 1, the proportioning is as follows:

[0058]

[0059] Proportion the ingredients according to the above ratio. The chemical composition of the mixture is shown in Table 3-1:

[0060] Table 3-1 Chemical Composition Ratio in the Blending of Example 3

[0061]

[0062]

[0063] Mix the above ingredients (dry basis), grind them, calcine at 1400 °C for 15 minutes, quench and cool rapidly with water, and then grind them for the second time to a fineness of 410 kg / m 2 Obtain a powder product. The hydration activity of this powder product is tested according to the test method of Standard GB / T 18046-2008 "Ground Granulated Blast-Furnace Slag for Use in Cement and Concrete", and the soluble thallium content in the lepidolite ore waste residue and the calcined powder is determined according to Standard HJ 748-2015 "Determination of Thallium in Water - Graphite Furnace Atomic Absorption Spectrophotometry". The determination results are shown in Table 3-2:

[0064] Table 3-2 Determination Results of Soluble Thallium Content in the Powder Product Obtained in Example 3

[0065]

[0066] Example 4

[0067] The principle of this example is the same as that of Example 1. Use the relevant raw materials provided in Example 1, and the ingredient ratio is as follows:

[0068]

[0069] Weigh the ingredients according to the above ratio, and the chemical composition of the mixture is shown in Table 4-1:

[0070] Table 4-1 Chemical Composition Ratio in the Blending of Example 4

[0071] Chemical composition CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[Na2O]]> <![CDATA[K2O]]> Others Percentage content 34.83 34.88 9.47 0.38 2.18 2.06 16.2

[0072] Mix the above ingredients (dry basis), grind them, calcine at 1300 °C for 15 minutes, cool rapidly with natural wind, and then grind them for the second time to a fineness of 400 kg / m 2 Obtain a powder product. The hydration activity of this powder product is tested according to the test method of Standard GB / T 18046-2008 "Ground Granulated Blast-Furnace Slag for Use in Cement and Concrete", and the soluble thallium content in the lepidolite ore waste residue and the calcined powder is determined according to Standard HJ 748-2015 "Determination of Thallium in Water - Graphite Furnace Atomic Absorption Spectrophotometry". The determination results are shown in Table 4-2:

[0073] Table 4-2 Determination Results of Soluble Thallium Content in the Powder Product Obtained in Example 4

[0074]

[0075] Example 5:

[0076] This example provides a building raw material, which uses the powder product obtained by the methods of Examples 1 to 4 as a hydraulic building gel material.

[0077] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for the solid thallium treatment and resource utilization of lepidolite ore waste residue, characterized in that, It includes the following steps: Mixing materials: The lepidolite waste, industrial materials containing calcium oxide, aluminum oxide and silicon dioxide components, and functional auxiliary materials are fully mixed in proportion to form a mixed material. During mixing, the dosage of lepidolite waste residue is 40% - 55%. In the mixed material after mixing, the calcium oxide content is 38 ± 4%, the silicon dioxide content is 33 ± 5%, and the aluminum oxide content is 10 ± 4%. The functional auxiliary materials include phosphate, silicate and diatomite mixed in the ratio of (1 - 3):(1 - 3):(1 - 4). The industrial materials include high-calcium materials and high-aluminum materials. The high-calcium materials include carbide slag and / or electric furnace phosphorus slag, and their calcium oxide content is not less than 40%. The high-aluminum materials include one or more of kaolin, clay, bauxite, and their aluminum oxide content is not less than 35%. The phosphate includes industrial pure sodium phosphate and potassium phosphate. The silicate includes powdered sodium silicate. The mass ratio of each component in the functional auxiliary materials is: sodium phosphate: potassium phosphate: sodium silicate: diatomite = 1:(0 - 2):(1 - 3):(1 - 4); Grinding: grinding the mixture into a powder with a fineness of 300 - 420 kg / m 2 of powder material; Sintering: The powdered materials obtained by grinding are put into a rotary kiln for calcination. During calcination, the powdered materials are controlled to stay in the high-temperature zone where they reach the molten state for no less than 10 minutes. The temperature of the high-temperature zone is 1200°C - 1500°C; Rapid cooling: The molten slurry is discharged from the rotary kiln and rapidly cooled by high-speed air with a wind speed of not less than 10 m / s or by water cooling with a water flow rate of not less than 2 m / s; Secondary grinding: grinding the cooling product obtained by rapid cooling to a fineness of 380 - 450 kg / m 2 to obtain a powder product, wherein the powder product contains calcium silicate and calcium aluminosilicate.

2. The method for the solid thallium treatment and resource utilization of lepidolite ore waste residue according to claim 1, characterized in that, In the mixing material step, the proportion of each raw material component is: Lepidolite waste residue 40 - 55%; High-calcium materials 30 - 50%; High-aluminum materials 0 - 20%; Functional auxiliary materials 0.1 - 0.6%.

3. The method for the solid thallium treatment and resource utilization of lepidolite ore waste residue according to claim 2, characterized in that, The industrial materials also include corrective materials. The corrective materials include calcium oxide with a purity of more than 92% and / or aluminum oxide with a purity of more than 92%. In the mixing material step, the proportion of each raw material component is: Lepidolite waste residue 40 - 55%; High-calcium materials 30 - 50%; High-aluminum materials 0 - 20%; Corrective materials 0 - 10%; Functional auxiliary materials 0.1 - 0.6%.

4. A building raw material, which comprises a powder product obtained by the method according to any one of claims 1 to 3, and the soluble thallium content in the powder product is not higher than 6 μg / kg.

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