Method for recovering and utilizing valuable elements in metallurgical slag

Abstract

The application discloses a method for recycling and utilizing valuable elements in metallurgical slag, and belongs to the technical field of metallurgical slag disposal. The recycling method comprises the following steps: crushing, screening and magnetic separation of the metallurgical slag, separation of iron products, and disposal of the mixed product precursor in sequence, such as pre-oxidation, one-time alkali leaching, ultrasonic acid pickling, two-time alkali leaching, acid leaching, organic solvent leaching, pH adjustment and aluminum thermal reduction, so that silicon-titanium compounds and various valuable elements such as magnesium, calcium and aluminum can be obtained. The recycling method not only improves the recovery rate and utilization rate of the metallurgical slag, but also extracts single elements or two elements at each step, which can reduce the time cost and improve the electrochemical performance of the silicon product, greatly increase the added value of industrial production, realize the "closed-loop recycling and disposal" of the metallurgical slag, and help to promote the industrialization process of high-value utilization of the metallurgical slag.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgical slag disposal, and particularly relates to a method for recovering and utilizing valuable elements in metallurgical slag. BACKGROUND

[0002] Metallurgical slag is a byproduct of the metallurgical industry, which is a fusible substance composed of gangue, ash, a dissolving agent and impurities that cannot enter pig iron, and contains a large amount of silicon, calcium, magnesium, aluminum and the like. Long-term stacking can easily cause resource waste and environmental pollution. Therefore, safe disposal and efficient recovery of metallurgical slag are the key to the high economic development of the metallurgical industry.

[0003] At present, the common methods for disposing metallurgical slag in the related art can be divided into two kinds: the first kind is to directly grind the metallurgical slag and then use it to prepare various grades of concrete; and the second kind is to extract target metal elements from the metallurgical slag, such as the prior art disclosed in the publication No. CN114269955A, which discloses a method for leaching valuable elements from metallurgical residues, which uses the technical measures of multiple acid leaching and alkali leaching to leach target metal elements copper and lead from metallurgical residues that have undergone a copper leaching process and contain copper, iron, lead, silicon and optional arsenic, antimony and bismuth.

[0004] However, the two technical measures in the related art have the following problems: the first kind of technical measure has a single product and low added value, and the efficient and comprehensive utilization of metallurgical slag is extremely limited; the second kind of technical measure needs to introduce an acid solution for long-time leaching, which consumes a long time, and multiple exogenous reagents are added in the whole separation and disposal, which interferes with the purity of the product and has a high cost, greatly limiting the industrial application. SUMMARY

[0005] The application discloses a method for recovering and utilizing valuable elements in metallurgical slag, aiming to solve the technical problems of low added value, serious pollution, high energy consumption and limited comprehensive utilization level of metallurgical slag resources in the prior art for disposing metallurgical slag.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0007] The first aspect of the application provides a method for recovering valuable elements in metallurgical slag. The recovery method of the application comprises:

[0008] The metallurgical slag is sequentially subjected to crushing, screening and magnetic separation to separate out an iron product and a mixed product precursor;

[0009] The mixed product precursor is subjected to oxidative pretreatment to obtain a first mixed product;

[0010] The first mixed product is subjected to a first alkali leaching and filtration to obtain a first silicon-aluminum-containing solution and a second mixed product;

[0011] After the second mixed product is ultrasonic acid pickling, a second alkali leaching is carried out and filtration is performed to obtain a second silicon-aluminum containing solution and a third mixed product;

[0012] The third mixed product is subjected to acid leaching and filtration to obtain a calcium product and a fourth mixed product solution;

[0013] The fourth mixed product solution is mixed with an organic solvent and filtration is performed to obtain a first aluminum product and a fifth mixed product solution;

[0014] The pH value of the fifth mixed product solution is adjusted to 5-6 and filtration is performed to obtain a titanium product and a magnesium containing solution;

[0015] The magnesium containing solution is spray dried to obtain a magnesium product;

[0016] After the first silicon-aluminum containing solution is mixed with the second silicon-aluminum containing solution, a precipitant and an activator are added, and when the pH value of the mixed solution is 8-10, filtration is performed to obtain a second aluminum product; and when the pH value of the mixed solution is 5-7, filtration is performed to obtain a silicon-aluminum product;

[0017] After the silicon-aluminum product is mixed with the titanium product, calcination is performed in an oxygen atmosphere to obtain a silicon-titanium product;

[0018] The second aluminum product is sequentially subjected to calcination and electrolysis to obtain aluminum;

[0019] The aluminum, the silicon-titanium product and a protective agent are mixed and subjected to aluminothermic reduction to obtain a silicon-titanium compound, wherein the protective agent includes aluminum chloride obtained by disposing the first aluminum product.

[0020] In combination with the first aspect, preferably, the oxidation pretreatment is performed using hydrogen peroxide.

[0021] In combination with the first aspect, preferably, the first alkali leaching and the second alkali leaching are the same and include:

[0022] The first mixed product / second mixed product after acid pickling is mixed with an alkali solution at 1:8-15 g / mL, and an immersion reaction is performed in a constant temperature water bath at 70-90°C for 40-90 min;

[0023] The alkali solution is at least one of a hydroxide solution of alkali metals and alkaline earth metals, ammonia water, an alcohol solution of alkali metals, sodium sulfite, sodium carbonate, potassium carbonate and sodium phosphate.

[0024] In combination with the first aspect, preferably, the ultrasonic acid pickling includes:

[0025] After the second mixed product is mixed with a first acid solution at 1:8-15 g / mL, ultrasonic acid pickling is performed for 1 h;

[0026] The first acid solution is one or a combination of hypochlorous acid, nitrous acid, sulfurous acid, acetic acid, ranelic acid, benzoic acid, phenol, fluorosilicic acid, and hydrogen sulfide.

[0027] In combination with the first aspect, preferably, the acid liquid leaching includes:

[0028] The third mixed product is mixed with the second acid solution at a ratio of 1-3:7-13 g / mL, and leaching is performed under ultrasonic stirring for 1-3 h at an ultrasonic temperature of 50-90°C and a stirring speed of 200-400 r / min.

[0029] The second acid solution is one or a combination of sulfuric acid, hydrofluoric acid, hydrochloric acid, sulfurous acid, boric acid, and phosphoric acid.

[0030] In combination with the first aspect, preferably, the fourth mixed product solution is mixed with the organic solvent at a volume ratio of 1-2:10-15.

[0031] The organic solvent is one or a combination of methanol, ethanol, isopropyl alcohol, acetonitrile, ethylene glycol monobutyl ether, and propylene oxide.

[0032] In combination with the first aspect, preferably, the precipitating agent is one or more of sodium bicarbonate, sodium percarbonate, anhydrous sodium carbonate, carbon dioxide, citric acid, hydrochloric acid, nitric acid, malic acid, tartaric acid, ascorbic acid, oxalic acid, trifluoromethanesulfonic acid, and dextroquinic acid.

[0033] The activating agent is one or more of sodium dodecyl sulfate, cetyltrimethylammonium bromide, octadecyl dimethyl benzyl quaternary ammonium chloride, ethylenediamine phosphate, propylenediamine phosphate, sodium fluorosilicate, ammonium sulfate, ammonium chloride, ferrous sulfate, acrylamide, ammonium hydroxide, copper sulfate, sodium tetraphenylborate, sodium sulfite, sodium chloride, and lead nitrate.

[0034] In combination with the first aspect, preferably, the recovery method further includes:

[0035] The recovery standard of the iron product is that the content of iron element is ≥70%, and if the recovery standard is not reached, the mixed product precursor is subjected to crushing, screening, and magnetic separation operations until the recovery standard is reached.

[0036] The recovery standard of the calcium product is that the content of calcium element is ≥40%, and if the recovery standard is not reached, the calcium product is added to the third mixed product until the recovery standard is reached.

[0037] The recovery standard of the first aluminum product is that the content of aluminum element is ≥70%, and if the recovery standard is not reached, the calcium product is added to the fourth mixed product solution until the recovery standard is reached.

[0038] The recovery standard of the titanium product is that the content of titanium element is greater than or equal to 70%, if the recovery standard is not reached, the titanium product is added into the fifth mixed product solution until the recovery standard is reached;

[0039] The recovery standard of the magnesium product is that the content of magnesium element is greater than or equal to 60%, if the recovery standard is not reached, the magnesium product is added into the fifth mixed product solution until the recovery standard is reached;

[0040] The recovery standard of the second aluminum product is that the content of aluminum element is greater than or equal to 80%, if the recovery standard is not reached, the second aluminum product is added into the mixed solution until the recovery standard is reached;

[0041] The recovery standard of the silicon-aluminum product is that the content of silicon element is greater than or equal to 80% and the content of aluminum element is greater than or equal to 10%.

[0042] The second aspect of the present application provides an application of the silicon-titanium compound recovered by the method of the first aspect in preparing a silicon-carbon composite negative material.

[0043] The third aspect of the present application provides a preparation method of a titanium-doped silicon-carbon composite negative material, the preparation method comprising:

[0044] The silicon-titanium compound recovered by the method of any one of claims 1-8 is mixed with a carbon material and heat treated in an inert gas atmosphere, and the titanium-doped silicon-carbon composite negative material is obtained.

[0045] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present application at least include:

[0046] The recovery method provided by the first aspect of the present application combines the technical means of pre-oxidation, first alkali leaching, ultrasonic acid pickling, second alkali leaching, acid leaching, organic solvent leaching, pH regulation separation, and aluminum thermal reduction, etc. in sequence for the metallurgical mixed product precursor without iron. On the one hand, the valuable elements such as calcium, magnesium, titanium, aluminum, silicon, etc. contained in the metallurgical mixed product precursor can be separated out step by step, greatly enriching the types of recovered products and improving the recovery rate of metallurgical waste slag, thereby realizing high value-added utilization of metallurgical waste slag. On the other hand, the leaching time of the acid solution can be effectively reduced, the time cost can be reduced, and the equipment corrosion can be reduced, which is conducive to industrial application. Thirdly, the separated valuable elements can be directly used as an external reagent for separating the next level of product, which not only improves the added value of the product and reduces the recovery cost, but also improves the electrochemical performance of the target silicon product, thereby realizing the "closed loop recovery and disposal" of metallurgical waste slag, and helping to promote the industrialization process of high value-added utilization of metallurgical waste slag.

[0047] The test results of the embodiments show that the application can make the recovery rate of silicon reach up to 92.6%, the recovery rate of aluminum reach up to 88.9%, the recovery rate of calcium reach up to 94.2%, and the recovery rate of titanium reach up to 75%; and can obviously improve the electrochemical performance of the prepared silicon-carbon composite negative electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0049] Figure 1 The flow chart of the method for recovering valuable elements in metallurgical waste slag provided by the embodiments of the application;

[0050] Figure 2 The SEM image of the metallurgical waste slag provided by the embodiments of the application;

[0051] Figure 3 The SEM image of the second mixed product D provided by the embodiments of the application;

[0052] Figure 4 The SEM image of BFSi provided by the embodiments of the application;

[0053] Figure 5 The first three circle charge-discharge curves of BFSi@PAN provided by the embodiments of the application;

[0054] Figure 6 The cycle performance test results of BFSi@PAN provided by the embodiments of the application

[0055] Figure 7 The first three circle charge-discharge curves of P-Si@PAN provided by the embodiments of the application;

[0056] Figure 8 The cycle performance test results of P-Si@PAN provided by the embodiments of the application. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the application will be described clearly and completely in the following with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0058] In the following description of the present embodiments, the terms "comprise", "contain", "have" and "include" and the like are open-ended terms, i.e., meaning "including but not limited to".

[0059] In the following description of the present embodiments, the term "and / or" is used to describe the relationship between associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the cases of A alone, B alone and A and B at the same time. Wherein A, B can be singular or plural. The character " / " generally represents that the associated objects before and after are in an "or" relationship.

[0060] In the following description of the present embodiments, the term "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of the items, including any combination of single item or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can represent a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c can be single or multiple.

[0061] The terms used in the present embodiments are merely for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the present embodiments and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0062] Those skilled in the art should understand that in the following description of the present embodiments, the order of the serial numbers does not mean the order of execution, and some or all steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the present embodiments.

[0063] Those skilled in the art should understand that the numerical ranges in the present embodiments should be understood as also specifically disclosing each intermediate value between the upper limit and the lower limit of the range. Each smaller range within any stated value or stated range of values and any other stated value or stated range of values between the stated values or stated ranges of values is also included within the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0064] Technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless otherwise specifically indicated. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe in full the methods and / or materials which are described herein. In case of conflict between any document incorporated by reference and the present specification, the present specification shall control.

[0065] In a first aspect, the embodiments of the present application provide a method for recovering valuable elements from metallurgical slag. Figure 1 As shown in the accompanying drawings, the recovery method of the embodiments of the present application preferably comprises:

[0066] The metallurgical slag is sequentially subjected to crushing, screening and magnetic separation to separate out an iron product A and a mixed product precursor B;

[0067] The mixed product precursor B is subjected to oxidative pretreatment to obtain a first mixed product C;

[0068] The first mixed product C is subjected to first alkaline leaching and filtration to obtain a first silicon-aluminum-containing solution E and a second mixed product D;

[0069] After the second mixed product D is subjected to ultrasonic acid pickling, the second mixed product D is subjected to second alkaline leaching and filtration to obtain a second silicon-aluminum-containing solution G and a third mixed product F;

[0070] The third mixed product F is subjected to acid leaching and filtration to obtain a calcium product H and a fourth mixed product solution I;

[0071] The fourth mixed product solution I is mixed with an organic solvent and filtered to obtain a first aluminum product J and a fifth mixed product solution K;

[0072] The pH value of the fifth mixed product solution K is adjusted to 5-6 and filtered to obtain a titanium product M and a magnesium-containing solution L;

[0073] The magnesium-containing solution L0 is spray dried to obtain a magnesium product L;

[0074] After the first silicon-aluminum-containing solution E and the second silicon-aluminum-containing solution G are mixed, a precipitant and an activator are added, and when the pH value of the mixed solution is 8-10, the mixed solution is filtered to obtain a second aluminum product O0, and when the pH value of the mixed solution is 5-7, the mixed solution is filtered to obtain a silicon-aluminum product N;

[0075] After the silicon-aluminum product N and the titanium product M are mixed, the mixture is calcined in an oxygen atmosphere to obtain a silicon-titanium product P;

[0076] The second aluminum product O0 is sequentially subjected to calcination and electrolysis to obtain aluminum O;

[0077] The aluminum O, the silicon-titanium product P and a protective agent are mixed and subjected to aluminothermic reduction to obtain a silicon-titanium composite Q, wherein the protective agent comprises the aluminum chloride obtained by processing the first aluminum product J.

[0078] It should be noted that the crushing, screening and magnetic separation settings in the embodiments of the present application can be operated according to technical elements known in the art, and the embodiments of the present application do not make special limitations thereon. For example, the crushing can be performed using a device such as a blender with a rated power of 3.2 KW for 60 min, so as to ensure the sufficiency and uniformity of the crushing. The screening particle size can be 400 mesh, or 300, 450, 500, 550 mesh, etc., so as to facilitate the separation of the iron product by magnetic separation.

[0079] It should be noted that the roasting, electrolysis and spray drying in the embodiments of the present application are all operated according to technical elements known in the art, and the embodiments of the present application do not make special limitations thereon. For example, the temperature of the spray drying is set to 200-300 DEG C; the temperature of the roasting is set to 500-700 DEG C.

[0080] The recycling method provided by the embodiments of the present application combines the technical means of pre-oxidation, first alkali leaching, pickling, second alkali leaching, ultrasonic acid leaching, organic solvent leaching, pH regulation separation and aluminothermic reduction in sequence for the metallurgical mixed product precursor containing no iron. On the one hand, the valuable elements such as calcium, magnesium, titanium, aluminum and silicon contained in the metallurgical mixed product precursor can be separated step by step, which greatly enriches the types of the recycling products and improves the recycling rate of the metallurgical waste slag, so as to realize the high value-added utilization of the metallurgical waste slag. On the other hand, the leaching time of the acid solution can be reduced, the time cost can be reduced and the equipment corrosion can be reduced, which is beneficial to the industrial application. Thirdly, the separated valuable elements can be directly used as the external reagent for separating the next level product, which not only improves the product added value and reduces the recycling cost, but also improves the electrochemical performance of the target silicon product, so as to realize the "closed loop recycling and disposal" of the metallurgical waste slag, and help to promote the industrialization process of the high value-added utilization of the metallurgical waste slag.

[0081] It should be noted that the pre-oxidation of the mixed product precursor in the embodiments of the present application can effectively improve the activity of the silicon and aluminum elements in the metallurgical waste slag, so that they are more easily leached, thereby improving the recycling rate of the metallurgical waste slag. Each step is single-element or two-element leaching, without introducing other impurities, thereby solving the problem of difficult impurity removal in the acid leaching process, and the extraction rate of silicon and aluminum reaches 80-95%. At the same time, the combination of the first alkali leaching and the second alkali leaching after pickling can further enrich and purify the silicon element, providing a basis for the high value-added utilization of silicon. In addition, the recycled aluminum element is directly used as a reducing agent in the aluminothermic reduction disposal, which greatly reduces the cost and realizes the "closed loop recycling and disposal" of the metallurgical waste slag.

[0082] The embodiment of the present application preferably uses hydrogen peroxide to perform the oxidation pretreatment.

[0083] It should be noted that when the embodiment of the present application uses hydrogen peroxide as an oxidizing agent to perform the related oxidation pretreatment, the mass ratio of the mixed product precursor to hydrogen peroxide is preferably 1-3:10-15. When hydrogen peroxide is used as an oxidizing agent to perform the pre-oxidation treatment, the introduction of impurities can be avoided while the recovery rate of valuable elements is improved.

[0084] In specific embodiments, the first alkaline leaching and the second alkaline leaching are the same and include:

[0085] The first mixed product / second mixed product of the acid pickling is mixed with an alkaline solution at a ratio of 1:8-15 g / mL, and the leaching reaction is performed in a constant temperature water bath at 70-90°C for 40-90 min.

[0086] The embodiment of the present application can effectively promote the leaching reaction by controlling the mixing ratio, temperature and time of the first mixed product / second mixed product of the acid pickling and the alkaline solution, so as to improve the leaching rate of silicon.

[0087] The alkaline solution is preferably at least one of 40% vv of alkali metal and alkaline earth metal hydroxide solution, 23 wt% of ammonia, 40% vv of alkali metal alcohol solution, 97 wt% of sodium sulfite, 98 wt% of sodium carbonate, 99 wt% of potassium carbonate and 95 wt% of sodium phosphate.

[0088] In specific embodiments, the ultrasonic acid pickling preferably includes:

[0089] After mixing the second mixed product with the first acid solution at a ratio of 1:8-15 g / mL, the ultrasonic acid pickling is performed for 1 h.

[0090] The embodiment of the present application can effectively remove impurities that interfere with the leaching of silicon by ultrasonic acid pickling of the second mixed product, so as to achieve a higher leaching rate of silicon.

[0091] The first acid solution is preferably one or a combination of 11 wt% of hypochlorous acid, 98 wt% of nitrous acid, 98 wt% of sulfurous acid, 10 wt% of acetic acid, 98 wt% of ranelic acid, 98 wt% of benzoic acid, 94 wt% of phenol, 32 wt% of fluorosilicic acid and 98 wt% of hydrogen sulfide.

[0092] In specific embodiments, the acid leaching preferably includes:

[0093] After mixing the third mixed product with the second acid solution at a ratio of 1-3:7-13 g / mL, the leaching reaction is performed under ultrasonic stirring for 1-3 h, the ultrasonic temperature is 50-90°C, and the stirring speed is 200-400 r / min.

[0094] The embodiment of the present application can make calcium fully precipitate and improve the purity of the precipitated calcium by controlling the mixing ratio of the third mixed product and the second acid solution, the ultrasonic temperature, and the stirring speed and the like.

[0095] The second acid solution is preferably one or a combination of 90wt% sulfuric acid, 40wt% hydrofluoric acid, 37wt% hydrochloric acid, 10wt% sulfurous acid, 98wt% boric acid, and 98wt% phosphoric acid.

[0096] In specific embodiments, the fourth mixed product solution and the organic solvent are preferably mixed at a volume ratio of 1-2:10-15.

[0097] The fourth mixed product solution is mixed with the organic solvent, so that the aluminum-containing substance can be selectively precipitated.

[0098] The organic solvent is preferably one or a combination of methanol, ethanol, isopropanol, acetonitrile, ethylene glycol monobutyl ether, and propylene oxide.

[0099] In specific embodiments, the precipitant is preferably one or more of sodium bicarbonate, sodium percarbonate, anhydrous sodium carbonate, carbon dioxide, citric acid, hydrochloric acid, nitric acid, malic acid, tartaric acid, ascorbic acid, oxalic acid, trifluoromethanesulfonic acid, and dextroquinic acid.

[0100] In specific embodiments, the activator is preferably one or more of sodium dodecyl sulfate, cetyltrimethylammonium bromide, octadecyl dimethyl benzyl quaternary ammonium chloride, ethylenediamine phosphate, propylenediamine phosphate, sodium fluorosilicate, ammonium sulfate, ammonium chloride, ferrous sulfate, acrylamide, ammonium hydroxide, copper sulfate, sodium tetraphenylborate, sodium sulfite, sodium chloride, and lead nitrate.

[0101] In specific embodiments, the recovery method of the present application further comprises:

[0102] The recovery standard of the iron product is that the content of iron element is ≥70%, and if the recovery standard is not reached, the mixed product precursor B is crushed, screened, and magnetically selected until the recovery standard is reached.

[0103] The recovery standard of the calcium product H is that the content of calcium element is ≥40%, and if the recovery standard is not reached, the calcium product H is added to the third mixed product F until the recovery standard is reached.

[0104] The recovery standard of the first aluminum product J is that the content of aluminum element is ≥70%, and if the recovery standard is not reached, the calcium product H is added to the fourth mixed product solution I until the recovery standard is reached.

[0105] The recovery standard of the titanium product M is that the content of titanium element is greater than or equal to 70%, if the recovery standard is not reached, the titanium product M is added into the fifth mixed product solution K until the recovery standard is reached;

[0106] The recovery standard of the magnesium product L0 is that the content of magnesium element is greater than or equal to 60%, if the recovery standard is not reached, the magnesium product L0 is added into the fifth mixed product solution K until the recovery standard is reached;

[0107] The recovery standard of the second aluminum product O0 is that the content of aluminum element is greater than or equal to 80%, if the recovery standard is not reached, the second aluminum product O0 is added into the mixed solution until the recovery standard is reached;

[0108] The recovery standard of the silicon-aluminum product N is that the content of silicon element is greater than or equal to 80% and the content of aluminum element is greater than or equal to 10%.

[0109] The embodiments of the present application control the recovery standards of various valuable elements,

[0110] It should be noted that the valuable element products recovered in each stage of the embodiments of the present application can be directly used after simple processing, for example:

[0111] The calcium product H can be heat treated in an oxygen atmosphere to produce various calcium product powders for use in building materials;

[0112] The first aluminum product J can be used to produce aluminum chloride in one step, which can be used as a flocculant and water purification material in addition to being used as a protective agent for aluminum thermal reduction;

[0113] The magnesium product L can be used in building materials, fertilizers, and industrial printing materials;

[0114] The second aluminum product O0 can be heat treated in an oxygen atmosphere to produce aluminum oxide powder, and the elemental aluminum O can be prepared by electrolysis for use in the aluminum thermal reduction of silicon dioxide;

[0115] The titanium product M and the silicon-aluminum product N can be mixed and then heat treated in an oxygen atmosphere to produce a composite powder of silicon dioxide and titanium dioxide for use as raw materials for the preparation of new energy, new energy vehicles, and new materials.

[0116] In a second aspect, the embodiments of the present application also provide the use of the silicon-titanium composite recovered by the method of the first aspect for preparing a silicon-carbon composite negative electrode material. The recovery method of the first aspect can effectively reduce the introduction of impurities and directly utilize the separated product as a protective external agent for the next target product to modify the product performance. Therefore, after the silicon-titanium composite recovered by the embodiments of the present application is used for preparing a silicon-carbon composite negative electrode material, the production cost of the silicon-carbon composite negative electrode material can be effectively reduced, and the electrochemical performance of the negative electrode material can be significantly improved.

[0117] In a third aspect, the embodiments of the present application further provide a preparation method of the titanium-doped silicon-carbon composite negative electrode material, which specifically comprises:

[0118] The silicon-titanium composite recovered by the method described above is mixed with the carbon material and heat-treated in an inert gas atmosphere to obtain the titanium-doped silicon-carbon composite negative electrode material.

[0119] The titanium element can be uniformly doped into the silicon material based on the method described above, so that the negative electrode material prepared by the method of the embodiments of the present application has excellent electrochemical performance. Meanwhile, the method is simple and easy to implement, and has low cost, which is helpful to promote the application of the titanium-doped silicon-carbon composite negative electrode material.

[0120] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0121] Embodiment 1

[0122] The embodiment 1 provides a method for recovering valuable elements in metallurgical slag, which specifically comprises:

[0123] S101: 200g of metallurgical slag is placed in a blender with a rated power of 3.2KW for crushing and grinding for 60min, and the obtained crushed product is sieved through a 400-mesh sieve, and the iron product A and the mixed product precursor B are separated by magnetic separation; the iron product A can be directly prepared into iron powder, and the mixed product precursor B is subjected to the next stage of recovery.

[0124] The chemical composition of the metallurgical slag is shown in Table 1.

[0125] Table 1-Chemical composition of metallurgical slag

[0126]

[0127] S102: The mixed product precursor B is mixed with 30wt% hydrogen peroxide at a solid-liquid ratio of 1:10g / mL for pre-oxidation, and then placed in a vacuum drying oven for drying for 12h, and the dried product is placed in a blender with a rated power of 3.2KW for crushing and grinding for 60min, and the obtained crushed product is sieved through a 400-mesh sieve to obtain a first mixed product C.

[0128] The chemical composition of the first mixed product C is shown in Table 2.

[0129] Table 2-Chemical composition of the first mixed product C

[0130]

[0131] S103: Mix 20g of the first mixed product C with 40% vv of sodium hydroxide solution at a solid-liquid ratio of 1:10 g / mL, and after the first alkaline leaching for 50 min at a temperature of 85℃ and a stirring speed of 300 r / min, filter out the first silica-alumina solution E and the second mixed product D.

[0132] S104: The second mixed product D is mixed with a 10% vv dilute sulfuric acid solution at a solid-liquid ratio of 1:20 g / mL, and ultrasonically acid-washed for 1 h under a stirring speed of 300 r / min.

[0133] S105: The second mixed product D, which was acid-washed, was mixed with a 40% vv sodium hydroxide solution at a solid-liquid ratio of 1:10 g / mL. After a second alkaline leaching for 50 min at a temperature of 85℃ and a stirring speed of 300 r / min, the second silica-alumina solution G and the third mixed product F were filtered out.

[0134] S106: The third mixed product F was mixed with a 70% vv concentrated sulfuric acid solution at a solid-liquid ratio of 1:10 g / mL. After leaching with acid solution for 1 h under ultrasonic temperature of 90℃ and stirring speed of 300 r / min, calcium product H and the fourth mixed product solution I were filtered out.

[0135] Among them, calcium product H can be heat-treated in an oxygen atmosphere to prepare calcium product powder.

[0136] S107: After mixing the fourth mixed product solution I with a 95% vv ethanol solution at a mass ratio of 13:1, filter out the first aluminum product J and the fifth mixed product solution K.

[0137] The first aluminum product J can be reacted with barium chloride solution to prepare aluminum chloride, which is used as a protective agent in the aluminum aluminothermic reduction in step S113.

[0138] S108: After adjusting the pH of the fifth mixed product solution K to 5, filter out the titanium product M and the magnesium-containing solution L0.

[0139] S109: Spray dry the magnesium-containing solution L0 at 280℃ to obtain magnesium product L.

[0140] S110: Mix the first silica-alumina solution E with the second silica-alumina solution G, and add 30% vv of hydrochloric acid solution. Then, add hexadecyltrimethylammonium bromide at a flow rate of 0.05 mL / min. During this process, the real-time pH of the solution is monitored by a pH meter. When the pH of the mixed solution is 8, the solid product is collected by centrifugation, which is the second aluminum product O. When the pH of the solution is 6, the solid product is collected by centrifugation, which is the silica-alumina product N.

[0141] S111: After mixing the silicon-aluminum product N and the titanium product M, calcination in an oxygen atmosphere is performed to obtain a silicon-titanium product P (a mixed powder of silicon dioxide and titanium dioxide);

[0142] S112: The second aluminum product O0 is sequentially subjected to calcination and electrolysis to obtain aluminum O;

[0143] S113: The aluminum O and the silicon-titanium product P are mixed with a protective agent at a mass ratio of 1.5:2:10 and subjected to aluminothermic reduction to obtain a silicon-titanium composite Q.

[0144] According to calculations, the recovery rate of silicon is 92.6%, the recovery rate of aluminum is 88.9%, the recovery rate of calcium is 94.2%, and the recovery rate of titanium is 75% when the metallurgical slag is used as a raw material to perform the recycling treatment described above in Example 1.

[0145] To verify the technical effect of Example 1, Comparative Examples 1-4 are provided for detailed illustration.

[0146] Comparative Example 1

[0147] This comparative example 1 provides a method for recycling valuable elements in metallurgical slag, which is different from Example 1 in that:

[0148] The pre-oxidation process of the mixed product precursor B in Example 1 is omitted, i.e.:

[0149] After the mixed product precursor B is directly placed in a wall-breaking machine with a rated power of 3.2KW for 60 minutes of crushing and grinding, the resulting crushed product is sieved through a 400-mesh sieve to obtain a first mixed product C.

[0150] The remaining steps and parameters are exactly the same as in Example 1.

[0151] Comparative Example 2

[0152] This comparative example 2 provides a method for recycling valuable elements in metallurgical slag, which is different from Example 1 in that:

[0153] The mixed product precursor B of Example 1 is pre-oxidized in an oxygen atmosphere, i.e.:

[0154] After the mixed product precursor B is pre-oxidized in an oxygen atmosphere, it is placed in a wall-breaking machine with a rated power of 3.2KW for 60 minutes of crushing and grinding, and the resulting crushed product is sieved through a 400-mesh sieve to obtain a first mixed product C.

[0155] The remaining steps and parameters are exactly the same as in Example 1.

[0156] Comparative Example 3

[0157] This comparative example 3 provides a method for recycling valuable elements in metallurgical slag, which is different from Example 1 in that:

[0158] The related treatment of ultrasonic pickling and second alkaline leaching in Example 1 was omitted, and the time of first alkaline leaching was set to 100 min.

[0159] The remaining steps and parameters were exactly the same as in Example 1.

[0160] Comparative Example 4

[0161] This comparative example 4 provides a method for recovering valuable elements in metallurgical slag, which is different from Example 1 in that:

[0162] The ultrasonic pickling of 10% vv dilute sulfuric acid solution in Example 1 was replaced by acid leaching of 70% vv concentrated sulfuric acid solution.

[0163] The remaining steps and parameters were exactly the same as in Example 1.

[0164] The recovery rates of each element in Example 1 and Comparative Examples 1-4 are shown in Table 3.

[0165] Table 3 - Recovery rates of each element in Example 1 and Comparative Examples 1-2

[0166]

[0167] According to Table 3, the above-mentioned various treatment steps are combined to effectively improve the recovery rate of various valuable elements, indicating that there is a full synergistic effect between different treatment steps. Specifically:

[0168] Firstly, comparing Example 1 with Comparative Example 1 and Comparative Example 2, the recovery rates of the four valuable elements are all significantly improved, indicating that the pre-oxidation treatment before leaching can simultaneously improve the leaching effect of the four valuable elements. The reason may be that pre-oxidation can make some phases that are not easy to leach more easily leached, and some trace sulfides are converted into oxides that are beneficial to leaching. At the same time, comparing Comparative Example 1 with Comparative Example 2, liquid oxidation of H2O2 can more obviously improve the recovery rates of silicon, aluminum and calcium than air oxidation, the reason may be that ultrasonic assistance can make pre-oxidation more complete, and ultrasonic can make solid-liquid contact more fully through ultrasonic cavitation of liquid, so that the oxidation process is more complete. Liquid oxidation of H2O2 realizes pre-oxidation treatment at the same time, and also washes off impurities on the surface of mixed product precursor B that are not easy to oxidize, making the pre-oxidation treatment more complete and complete, thereby improving the recovery rates of the four valuable elements at the same time.

[0169] Secondly, comparing Example 1 with Comparative Example 3, the recovery rates of all four valuable elements were significantly improved, indicating that the combined leaching of the first alkaline leaching, acid washing, and second alkaline leaching can produce a sufficient synergistic effect. To understand the reasons for this effect, the embodiments of this application performed SEM characterization on the metallurgical waste slag and the second mixed product D from the first alkaline leaching. The results were as follows: Figures 2-3 As shown. Among them, Figure 2 SEM image of metallurgical waste slag; Figure 3 This is the SEM image of the second mixed product D.

[0170] according to Figures 2-3 It is known that the metallurgical waste slag does not exhibit agglomeration, while the second mixed product D shows obvious agglomeration, and the particle surface is covered with a significant substance, which restricts the leaching effect of various valuable elements. Therefore, the combination of the first alkaline leaching, acid washing, and second alkaline leaching scheme set in the embodiments of this application can remove the coating on the particle surface, thereby significantly improving the alkaline leaching effect.

[0171] Thirdly, comparing Example 1 with Comparative Example 4, the recovery rates of all four valuable elements were significantly improved, indicating that acid concentration has a certain impact on the pickling effect. This may be because high-concentration acid can allow some calcium elements to enter the solution, where more complex reactions occur, causing calcium to form a slag phase and re-enter the slag. From the perspectives of saving resources and environmental protection, we chose to use a low-concentration acid.

[0172] In summary, the embodiments of this application, through the combination of various processing steps, can generate sufficient synergistic effects among the processing steps, thereby significantly enhancing the separation effect of each step and greatly improving the recovery rate of the four valuable elements.

[0173] Example 2

[0174] This embodiment provides a method for preparing a titanium-doped silicon-carbon composite anode material, specifically including:

[0175] The silicon-titanium composite Q recovered in Example 1 was mixed with carbon material and placed in a tube furnace, and then heat-treated in an inert gas atmosphere to obtain the titanium-doped silicon-carbon composite anode material BFSi@PAN.

[0176] The structural characterization results of the silicon-titanium composite Q are as follows: Figure 4 As shown. Among them, Figure 4 This is a SEM image of the silicon-titanium composite Q.

[0177] according to Figure 4 It can be seen that the silicon-titanium composite Q prepared in Example 1 is in the form of irregular aggregates combined into silicon wafers, stacked layer by layer.

[0178] The electrochemical performance of the BFSi@PAN was verified by a CR2025 coin-type battery, specifically including:

[0179] The BFSi@PAN, conductive carbon black and PVDF were blended in a weight ratio of 7:1:2 in the solvent N-methyl-2-pyrrolidone to make a working electrode, and the working electrode, lithium metal sheet counter / reference electrode and multi-multiple electrolyte LX-025 were assembled into a coin battery model. After that, the battery model was tested by a new Wei battery test system in a constant current charge-discharge test in a voltage range of 0.01-1V, and the results were as follows Figures 5-6 As shown in the figure, wherein, Figure 5 is the first three cycles of charge-discharge curves of the BFSi@PAN; Figure 6 is the cycle performance test results of the BFSi@PAN.

[0180] According to Figure 5 , the initial discharge capacity of the BFSi@PAN is 1802.82mAh / g, the initial charge capacity is 1367.36mAh / g, and the coulombic efficiency is 75.85%. Among them, the long and flat platform below 0.1V is related to the lithium alloying process of silicon, forming an amorphous LixSi phase; the platform at 0.5V in the charge curve corresponds to the dealloying process of silicon.

[0181] According to Figure 6 , the initial charge capacity of the BFSi@PAN is 1367.36mAh / g, the coulombic efficiency reaches more than 98% from the fourth cycle, and the capacity decreases to 1035.64mAh / g after 100 cycles, with a capacity retention rate of 75.74%.

[0182] To further illustrate the electrochemical performance of the silicon-titanium composite Q, the commercial silicon was made into a silicon-carbon composite negative electrode material P-Si@PAN according to the method of Example 2, and the electrochemical performance of the P-Si@PAN was determined according to the CR2025 coin-type battery. Among them, the size of the commercial silicon is 400-500nm, and the shape is spherical.

[0183] The electrochemical performance of the P-Si@PAN was tested as Figures 7-8 . Among them, Figure 7 is the first three cycles of charge-discharge curves of the P-Si@PAN; Figure 8 is the cycle performance test results of the P-Si@PAN.

[0184] According to Figure 7 , the initial discharge capacity of the P-Si@PAN is 1469.66mAh / g, the initial charge capacity is 1069.11mAh / g, and the coulombic efficiency is 72.74%.

[0185] According to Figure 8It can be seen that the initial charge capacity of P-Si@PAN is 1069.11 mAh / g, the coulombic efficiency reaches more than 98% from the fifth cycle, and the capacity decreases to 815.13 mAh / g after 100 cycles, and the capacity retention rate is 76.24%.

[0186] Compared with the electrochemical performance of BFSi@PAN, it can be seen that the cycle performance of the silicon-titanium composite recovered in the application example has a certain decline compared with the commercial silicon, but the charge-discharge performance and coulombic efficiency are very obviously improved, and the reason may be that the doped elements in the silicon product recovered in the application example can change the surface activity of the composite material and provide more capacity, while effectively limiting the volume expansion of the silicon element, thereby improving the electrochemical performance.

[0187] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment focuses on the difference from other embodiments.

[0188] The above examples are only used to illustrate the technical solutions of the application, and are not limited to the application; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the application.

Claims

1. A method for recovering valuable elements from metallurgical waste slags, characterized in that, The method comprises the following steps: metallurgical slag is crushed, screened and magnetically separated in sequence to separate iron product and mixed product precursor; the mixed product precursor is mixed with 30wt% hydrogen peroxide at a solid-liquid ratio of 1:10 g / mL and subjected to oxidation pretreatment to obtain a first mixed product; the first mixed product is mixed with 40%vv sodium hydroxide solution at a solid-liquid ratio of 1:10 g / mL and subjected to first alkaline leaching and filtration to obtain a first silicon-aluminum containing solution and a second mixed product; the second mixed product is mixed with 10%vv dilute sulfuric acid solution at a solid-liquid ratio of 1:20 g / mL and subjected to ultrasonic acid pickling for 1h, and then the acid-pickled second mixed product is mixed with 40%vv sodium hydroxide solution at a solid-liquid ratio of 1:10 g / mL and subjected to second alkaline leaching and filtration to obtain a second silicon-aluminum containing solution and a third mixed product; the third mixed product is mixed with 70%vv concentrated sulfuric acid solution at a solid-liquid ratio of 1:10 g / mL and subjected to acid leaching and filtration to obtain a calcium product and a fourth mixed product solution; the fourth mixed product solution is mixed with an organic solvent and filtered to obtain a first aluminum product and a fifth mixed product solution; the pH value of the fifth mixed product solution is adjusted to 5-6 and filtered to obtain a titanium product and a magnesium containing solution; the magnesium containing solution is spray dried to obtain a magnesium product; the first silicon-aluminum containing solution is mixed with the second silicon-aluminum containing solution, 30%vv hydrochloric acid solution and cetyltrimethylammonium bromide are added, and when the pH value of the mixed solution is 8-10, filtration is performed to obtain a second aluminum product; and when the pH value of the mixed solution is 5-7, filtration is performed to obtain a silicon-aluminum product; the silicon-aluminum product and the titanium product are mixed and calcined in an oxygen atmosphere to obtain a silicon-titanium product; the second aluminum product is subjected to calcination and electrolysis in sequence to obtain aluminum; the aluminum, the silicon-titanium product and a protective agent are mixed and subjected to aluminothermic reduction to obtain a silicon-titanium compound, wherein the protective agent comprises aluminum chloride obtained by treating the first aluminum product.

2. The recycling method according to claim 1, characterized in that, The first alkaline leaching and the second alkaline leaching are the same and comprise: the leaching reaction is performed in a constant temperature water bath at 70-90°C for 40-90min.

3. The recycling method according to claim 1, characterized in that, the acid leaching comprises: ultrasonic stirring for 1-3h, ultrasonic temperature is 50-90°C, and stirring speed is 200-400r / min.

4. The recycling method of claim 1, wherein, the fourth mixed product solution and the organic solvent are mixed at a volume ratio of 1-2:10-15; the organic solvent is one or a combination of several of methanol, ethanol, isopropyl alcohol, acetonitrile, ethylene glycol monobutyl ether and propylene oxide.

5. The recycling method according to any one of claims 1 to 4, characterized in that, Further comprising: the recovery standard of the iron product is that the content of iron element is ≥70%, and if the recovery standard is not reached, the operations of crushing, screening and magnetic separation on the mixed product precursor are performed until the recovery standard is reached; the recovery standard of the calcium product is that the content of calcium element is ≥40%, and if the recovery standard is not reached, the calcium product is added to the third mixed product until the recovery standard is reached; The recovery standard of the first aluminum product is aluminum content ≥ 70%, if the recovery standard is not reached, the calcium product is added to the fourth mixed product solution until the recovery standard is reached; The recovery standard of the titanium product is titanium content ≥ 70%, if the recovery standard is not reached, the titanium product is added to the fifth mixed product solution until the recovery standard is reached; The recovery standard of the magnesium product is magnesium content ≥ 60%, if the recovery standard is not reached, the magnesium product is added to the fifth mixed product solution until the recovery standard is reached; The recovery standard of the second aluminum product is aluminum content ≥ 80%, if the recovery standard is not reached, the second aluminum product is added to the mixed solution until the recovery standard is reached; The recovery standard of the silicon aluminum product is silicon content ≥ 80% and aluminum content ≥ 10%.

6. The application of the silicon-titanium composite recovered by the method according to any one of claims 1-5 in the preparation of silicon-carbon composite negative electrode material.

7. A method for preparing a titanium-doped silicon-carbon composite negative electrode material, characterized by, Comprise: Mixing and heat treating the silicon-titanium composite recovered by the method according to any one of claims 1-5 with carbon material in an inert gas atmosphere, and the titanium-doped silicon-carbon composite negative electrode material is obtained.

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