Goethite, preparation method and application thereof

Abstract

The present application relates to the technical field of goethite, and provides a goethite, a preparation method and application, the preparation method comprises the following steps: S1, coarse crushing of limonite, sieving, to obtain a coarse crushing sample; S2, fine crushing and grading sieving, to obtain a plurality of batches of fine sieving samples; S3, heating and heat preservation of the fine sieving samples; S4, magnetic separation of the fine sieving samples, and weakly magnetic hematite and strongly magnetic substances are extracted together; S5, repeating steps S3 and S4 until the content of the remaining magnetic substances is within a set threshold; S6, cooling the fine sieving samples to below the Neel temperature of goethite, and then performing magnetic separation again to separate goethite. The present application has the advantages of large processing capacity, high processing efficiency, continuous production, and significantly reduced difficulty in obtaining goethite. In addition, compared with the traditional hydrothermal synthesis method, the present application removes the use of chemical products, effectively reducing the environmental problems in the production process of goethite.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of goethite, and in particular to a goethite, a preparation method and an application. BACKGROUND

[0002] Goethite is an iron-containing inorganic compound and has a wide range of applications in industry, such as being used as a pigment, for desulfurization, and for adsorbing impurities to treat wastewater. Recent studies have shown that goethite can be used as an efficient catalyst in the hydrogen production industry. With the increasing importance of hydrogen energy as a clean energy source in various industrial sectors, and the increasing application of goethite as a functional material in a wide range of scenarios, the demand for goethite will reach a new height.

[0003] Currently, goethite is generally synthesized by a wet method, and the preparation process takes a long time and produces liquid waste that is difficult to dispose of. In nature, goethite exists in the form of perfect crystals in large quantities, and limonite is a type of iron ore that contains a large amount of goethite. In industry, limonite is mainly used for steel smelting, and iron elements are extracted through a blast furnace ironmaking process. However, due to the thermal decomposition of the crystal water in limonite, the limonite undergoes thermal cracking, which affects the permeability of the column and disrupts the operation of the blast furnace, so the proportion of limonite in the blast furnace is low. In recent years, some enterprises have reduced the content of crystal water in the limonite through external heat treatment, which has increased the amount of limonite used in the blast furnace. However, the additional energy consumption has also increased the cost,

[0004] Therefore, there is an urgent need for corresponding technical innovation to extract goethite from limonite in an economical and efficient manner and to utilize it in a high-value manner. SUMMARY

[0005] The present application overcomes the shortcomings of the prior art and provides a goethite, a preparation method and an application. The method provided by the present application has a large processing capacity and can be continuously produced, significantly reducing the difficulty of obtaining goethite and improving production efficiency.

[0006] The present application adopts the following technical solutions:

[0007] In one aspect, the present application provides a preparation method of goethite, comprising:

[0008] S1, coarsely crushing limonite and sieving to obtain a coarsely crushed sample;

[0009] S2, finely crushing the coarsely crushed sample of step S1 and classifying and sieving with sieves of different mesh sizes to obtain multiple batches of finely sieved samples;

[0010] S3, heating the multiple batches of finely sieved samples obtained in step S2 respectively and maintaining the temperature for a certain time;

[0011] S4, using a magnetic field with a certain intensity to perform magnetic separation on the plurality of batches of the fine-screened sample treated in step S3, and extracting weakly magnetic hematite together with strongly magnetic substances, and the remaining fine-screened sample enters step S5;

[0012] S5, repeating step S3 and step S4 until the content of the remaining magnetic substance is within a set threshold;

[0013] S6, cooling the fine-screened sample treated in step S5 to below the goethite Neel temperature, and performing magnetic separation again to separate goethite.

[0014] According to any possible implementation manner described above, further provided is an implementation manner, in step S1, after coarse crushing, the particle size of the coarse-crushed sample is less than 1 mm, and the mesh number of the sieve hole is 50 meshes.

[0015] According to any possible implementation manner described above, further provided is an implementation manner, in step S1, the oversize sample and the undersize sample prepared after coarse crushing and sieving are respectively subjected to fine crushing, and are respectively classified and sieved by sieves with different sieve holes.

[0016] According to any possible implementation manner described above, further provided is an implementation manner, in step S2, the particle size of the fine-crushed sample is not less than 300 meshes, and from 300 meshes to 1000 meshes, every 50 meshes is a batch, and is respectively subjected to sieving.

[0017] According to any possible implementation manner described above, further provided is an implementation manner, in step S3, the heating temperature is 150-180 ℃, and the holding time is 20-40 min.

[0018] According to any possible implementation manner described above, further provided is an implementation manner, in step S4, the intensity of the magnetic field is not less than 15000 Gauss.

[0019] According to any possible implementation manner described above, further provided is an implementation manner, in step S5, the number of repetitions is 8-15 times.

[0020] According to any possible implementation manner described above, further provided is an implementation manner, in step S6, the fine-screened sample is cooled to room temperature, and the intensity of the magnetic field for the magnetic separation is not less than 15000 Gauss.

[0021] According to any possible implementation manner described above, further provided is an implementation manner, the goethite treated in step S6 has a purity of more than 99.6%.

[0022] In another aspect, the present application also provides a goethite prepared by the method for preparing goethite described above.

[0023] In another aspect, the application also provides a use of the goethite as described above.

[0024] The goethite with a particle size of 300-700 mesh is used as a functional material for adsorbing impurities.

[0025] The product with a particle size higher than 700 mesh is further ground to a nanoscale and used as a hydrogen production catalyst.

[0026] In addition, the sample separated in step S4 is mainly hematite, and also contains a small amount of magnetic substances such as MgO and a very small amount of impurities. The sample is mixed with appropriate coke powder, cold-pressed into a block with a height of 5 mm and a diameter of 5 mm, and arranged on a sintering trolley together with a sintering batch, so that the permeability of the sintering layer can be improved. At the same time, the grade of the sinter is improved, the silicon content of the sinter is reduced, and the amount of high-alumina sintering ore powder in the sintering mixture is also increased.

[0027] The application has the following beneficial effects:

[0028] The traditional hydrothermal synthesis method for preparing goethite needs to take at least 24 hours, while the method of the application needs less than 1.5 hours to obtain goethite of the same scale, and the production efficiency is obviously improved. At the same time, the method provided by the application has a large processing capacity and can be continuously produced, which significantly reduces the difficulty of obtaining goethite. In addition, compared with the traditional hydrothermal synthesis method, the method provided by the application eliminates the use of chemical products, effectively reducing the environmental problems in the production process of goethite. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure shows the distribution of hematite and goethite in limonite.

[0030] Figure 2 The figure shows the process flow chart of the preparation method of the goethite according to an embodiment of the application. DETAILED DESCRIPTION

[0031] The technical features or combinations of technical features described in the following embodiments should not be considered in isolation, and they can be combined with each other to achieve better technical effects.

[0032] The applicant found in the research that in limonite, goethite and hematite have obvious boundaries, as shown in Figure 1 which can be effectively separated by sufficient external force. In addition, the hardness of hematite (5.5-6.5) is greater than that of goethite (5-5.5). Therefore, coarse crushing can obtain goethite particles with relatively lower particle size, and screening can improve the content of goethite in the raw material. Subsequent fine crushing can further reduce the particle size and separate hematite and goethite that are still in a combined state, in preparation for subsequent processing.

[0033] Besides goethite and hematite, the two main mineral phases, limonite also contains small amounts of SiO2, Al2O3, MgO, and other substances. To obtain high-purity goethite, it is necessary to separate the substances based on their different properties. This invention selects the magnetic differences between the substances for the separation and purification of goethite.

[0034] Goethite and hematite possess weak magnetism, which changes with temperature. When the temperature exceeds the Nillet temperature (~120°C) of goethite, it transforms into a paramagnetic substance. At this point, goethite exhibits extremely low magnetism, showing a significant difference from hematite. Simultaneously, using a magnetic separator with a magnetic field strength exceeding 15,000 Gauss to perform magnetic separation on the sample can remove a large amount of hematite, MgO, and other magnetically separated materials, while a very small amount of goethite will also be adsorbed. Repeated magnetic separation yields a sample primarily composed of goethite, containing small amounts of SiO2, Al2O3, and other non-magnetic materials. After the sample cools to room temperature, the magnetism of the goethite recovers, allowing for further magnetic separation to obtain high-purity goethite.

[0035] A small portion of impurities, due to their inherent state, are difficult to completely separate from goethite and hematite. During particle size reduction, mechanical crushing can separate these impurities as much as possible. Furthermore, for the same particle size, particles containing less non-magnetic material are more easily separated by magnetic separation. Therefore, granulation followed by graded magnetic separation is necessary. Additionally, due to the limitations of the magnetic field in the magnetic separator, the material attracted by the magnet is primarily goethite. Downstream departments can set appropriate application scenarios based on different goethite purities.

[0036] like Figure 2 As shown in the figure, an embodiment of the present invention provides a method for preparing goethite, comprising:

[0037] S1. The limonite is coarsely crushed and sieved to obtain a coarsely crushed sample;

[0038] Due to the differences in natural morphology and hardness between limonite and hematite, hematite produces coarser particles when crushed; therefore, sieving can increase the proportion of goethite in the undersize sample by about 10%.

[0039] S2. The coarsely crushed sample described in step S1 is further crushed and graded by sieves with different mesh sizes to obtain multiple batches of finely sieved samples.

[0040] Preferably, the samples obtained after coarse crushing and sieving are subjected to fine crushing and sieving, and then graded and sieved using sieves with different mesh sizes.

[0041] With the increase of the screening mesh number, the proportion of goethite in the corresponding batch sample also increases, which can improve the subsequent magnetic separation efficiency; in addition, goethite samples of different particle sizes can be applied in corresponding application scenarios, and the appropriate particle size of goethite for the corresponding scene can be obtained in advance through grading screening;

[0042] S3, heating the plurality of batches of fine screening samples obtained in step S2 respectively, and keeping the temperature for a certain time;

[0043] At this temperature, goethite is converted into paramagnetic substance, and its magnetic property is close to non-magnetic, so that most of the goethite can be separated from the substances with stronger magnetic property through magnetic separation;

[0044] S4, using a magnetic field with a certain intensity to perform magnetic separation on the plurality of batches of fine screening samples processed in step S3, and extracting the substances with weaker magnetic property (i.e. hematite) together with the substances with strong magnetic property, and the remaining fine screening samples enter step S5;

[0045] At this magnetic field intensity, the substances with weaker magnetic property (i.e. hematite) can be extracted together with the substances with strong magnetic property; although a small amount of goethite is directly attracted by the magnetic field of the magnetic separator, or is not separated from hematite completely in the crushing stage and is removed together with hematite, but the total loss of goethite is less than 5%, which does not have too much impact on the yield;

[0046] S5, repeating step S3 and step S4 until the content of the remaining magnetic substance is within a set threshold;

[0047] S6, cooling the fine screening sample processed in step S5 to below the Neel temperature of goethite, and performing magnetic separation again to separate goethite.

[0048] Since the temperature drops below the Neel temperature of goethite, its magnetic property rapidly increases. Therefore, the sample that has passed the magnetic separation is cooled in the air, so that the magnetic property of goethite completely recovers to the original level. Subsequently, a magnetic separator with a magnetic field intensity exceeding 15000 Gauss is used again to perform magnetic separation, so as to separate goethite from other non-magnetic substances.

[0049] In one specific embodiment, in step S1, after coarse crushing, the particle size of the coarse crushing sample is <1mm, and the mesh number of the screening sieve is 50 meshes.

[0050] As any possible implementation manner described above, further provided is an implementation manner, in step S2, the particle size of the fine crushing sample is not less than 300 meshes, and from 300 meshes to 1000 meshes, every 50 meshes is a batch, and the screening is performed respectively.

[0051] According to any possible implementation manner described above, further provided is an implementation manner, in step S3, the heating temperature is 150-180 DEG C, and the holding time is 20-40 min.

[0052] According to any possible implementation manner described above, further provided is an implementation manner, in step S4, the magnetic field strength is not less than 15000 Gauss.

[0053] According to any possible implementation manner described above, further provided is an implementation manner, in step S5, the number of repetitions is 8-15 times.

[0054] According to any possible implementation manner described above, further provided is an implementation manner, in step S6, the fine-screened sample is cooled to room temperature, and the magnetic field strength for the re-magnetic separation is not less than 15000 Gauss.

[0055] According to any possible implementation manner described above, further provided is an implementation manner, the goethite after the processing of step S6 has a purity of more than 99.6%.

[0056] In another aspect, the application further provides a goethite prepared by the above method.

[0057] In another aspect, the application further provides an application of the above goethite.

[0058] The goethite with a particle size of 300-700 mesh is used as a functional material for adsorbing impurities.

[0059] The product with a particle size of more than 700 mesh is further ground to nanoscale and used as a hydrogen production catalyst.

[0060] In addition, the sample separated in step S4 mainly contains hematite, a small amount of magnetic substances such as MgO, and a very small amount of impurities. The sample is mixed with appropriate coke powder, cold-pressed into a block with a height of 5 mm and a diameter of 5 mm, and arranged on a sintering trolley together with sintering ingredients, so that the permeability of the sintering material layer can be improved. At the same time, the grade of the sinter is improved, the silicon content of the sinter is reduced, and the amount of high-aluminum sintering ore powder in the sintering mixture is also increased.

[0061] The traditional hydrothermal synthesis method for preparing goethite needs to spend at least 24 hours, while the method provided by the application needs less than 1.5 hours to obtain goethite of the same scale, and the production efficiency is obviously improved. At the same time, the method provided by the application has a large processing capacity and can be continuously produced, which significantly reduces the difficulty of obtaining goethite. In addition, compared with the traditional hydrothermal synthesis method, the method provided by the application eliminates the use of chemical products, effectively reducing the environmental problems in the process of producing goethite.

[0062] Although several embodiments of the present application have been given in the above, those skilled in the art should understand that the embodiments herein can be changed without departing from the spirit of the present application. The above embodiments are only exemplary and should not be taken as limiting the scope of the present application.

Claims

1. A method for the preparation of goethite, characterized in that, The preparation method includes: S1. The limonite is coarsely crushed and sieved to obtain a coarsely crushed sample; the particle size of the coarsely crushed sample is <1mm. S2. The coarsely crushed sample from step S1 is further crushed to obtain a finely crushed sample, which is then graded and sieved using sieves with different mesh sizes to obtain multiple batches of finely sieved samples. The particle size of the finely crushed sample is not less than 300 mesh, starting from 300 mesh and going up to 1000 mesh, with each batch consisting of 50 meshes, and then sieved separately. S3. The multiple batches of finely sieved samples obtained in step S2 are heated separately and kept at a certain temperature for a certain time; the heating temperature is 150-180℃ and the holding time is 20-40 min. S4. Use a magnetic field with an intensity of not less than 15,000 Gauss to perform magnetic separation on multiple batches of the finely sieved samples after step S3, extracting the weakly magnetic hematite and the strongly magnetic material together, and the remaining finely sieved samples enter step S5. S5. Repeat steps S3 and S4 until the remaining magnetic material content falls within the set threshold. S6. After being processed in step S5, the finely sieved sample is cooled to below the Nillet temperature of goethite and then subjected to magnetic separation again to separate the goethite.

2. The method for preparing goethite according to claim 1, characterized by, In step S1, after coarse crushing, the sieve mesh size is 50 mesh.

3. The method of preparing goethite according to claim 1, wherein In step S5, the number of repetitions is 8-15 times.

4. The method for preparing goethite according to claim 1, wherein In step S6, the finely sieved sample is cooled to room temperature, and the magnetic field strength for the second magnetic separation is not less than 15,000 Gauss.

5. The method of preparing goethite according to claim 1, wherein After processing in step S6, the goethite has a purity exceeding 99.6%.

6. A goethite characterized in that, The goethite is obtained by the goethite preparation method according to any one of claims 1-5.

7. The application of goethite as described in claim 6, characterized in that, The goethite product with a particle size of 300-700 mesh is used as a functional material for adsorbing impurities. Products with a particle size greater than 700 mesh are further ground to the nanoscale and used as hydrogen production catalysts.

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