Device for preparing aluminum hydroxide and co-producing ammonium chloride from bauxite

Abstract

The utility model provides a device for preparing aluminum hydroxide and co-producing ammonium chloride from bauxite. The device comprises an acidolysis tank, primary filtering equipment, a precipitation tank, secondary filtering equipment, a flash tower and a drying tower which are arranged in sequence, wherein a filtrate outlet of the first-stage filtering equipment is connected to the precipitation tank, and a filtrate outlet of the second-stage filtering equipment is connected to the flash tower; a filter cake outlet of the secondary filtering equipment is connected to the fluidized bed, the fluidized bed is provided with an aluminum hydroxide product outlet, and the drying tower is provided with an ammonium chloride outlet. According to the utility model, after bauxite is subjected to acidolysis by hydrochloric acid, insoluble slag is filtered and separated, ammonia is introduced into filtrate to control the pH value to be 3.7-5.0, aluminum hydroxide is precipitated and then filtered, separated and dried to obtain an aluminum hydroxide product, and the filtrate is concentrated and dried to obtain ammonium chloride, so that the recycling of hydrochloric acid and bauxite resources is realized.

Description

Technical Field

[0001] The utility model belongs to the field of comprehensive utilization of bauxite and relates to a device for preparing aluminum hydroxide and co-producing ammonium chloride from bauxite. Background Art

[0002] Bauxite tailings have similar chemical compositions to clay raw materials and are a resource with research value. Bauxite is a general term for a variety of hydrous aluminum oxide ores with very different geological sources. Its scientific name is bauxite and bauxite. Its composition is extremely complex, mainly composed of aluminum hydroxide (gibbsite, boehmite, diaspore) and hydrous aluminum silicate. In my country, the refractory industry generally calls it bauxite, and the aluminum smelting industry generally calls it bauxite.

[0003] The process of bauxite beneficiation usually includes washing, flotation, magnetic separation and chemical beneficiation, and carries out desiliconization, desulfurization, deironization, detitaniumization and other impurities removal. With the increase of bauxite beneficiation processing volume, the stockpile of tailings is also increasing. The mineral composition of bauxite beneficiation tailings is mainly diaspore, kaolinite, illite, pyrophyllite, chlorite, potassium feldspar, quartz, anatase, rutile, limonite, hematite, muscovite, etc.; according to the different origins, the types and contents of each mineral are different, but their chemical composition is relatively close, mainly containing 35% to 60% Al2O3, 10% to 35% SiO2, 1% to 15% Fe2O3, 2% to 6% TiO2, and impurities such as alkali metals and alkaline earth metal oxides (CaO, MgO, K2O, Na2O, etc.) with a total content of basically less than 5%. The impurity composition and content fluctuate greatly depending on the resources.

[0004] my country's use of bauxite is mainly focused on making ceramics and building materials, and there are few applications for the extraction of ions in bauxite and the preparation of high-value chemical products. The resource utilization of bauxite tailings is a technically difficult topic. It is necessary to overcome the technical difficulties such as different mineral components of bauxite tailings caused by different regions, fluctuations in composition, fluctuations in particle size, and difficulty in separating harmful components, so as to obtain better economic benefits, and to achieve zero discharge of bauxite tailings as much as possible. Therefore, comprehensive and systematic development of bauxite tailings is very necessary. Summary of the invention

[0005] The utility model provides a device for preparing aluminum hydroxide and ammonium chloride from wet bauxite, wherein the insoluble residue is separated by filtering after the bauxite is hydrolyzed with hydrochloric acid, and the filtrate is passed through ammonia to control the pH value at 3.7-5.0 to precipitate aluminum hydroxide, and then filtered, separated and dried to obtain an aluminum hydroxide product. The filtrate is concentrated and dried to obtain ammonium chloride.

[0006] The technical solution of the utility model is to provide a device for preparing aluminum hydroxide and co-producing ammonium chloride from bauxite, comprising an acid hydrolysis tank, a primary filtering device, a precipitation tank, a secondary filtering device, a flash tower and a drying tower which are arranged in sequence; wherein the filtrate outlet of the primary filtering device is connected to the precipitation tank, the filtrate outlet of the secondary filtering device is connected to the flash tower; and the filter cake outlet of the secondary filtering device is connected to a fluidized bed, the fluidized bed is provided with an aluminum hydroxide product outlet, and the drying tower is provided with an ammonium chloride outlet.

[0007] Furthermore, the acidolysis tank is provided with an acid adding pipeline and a bauxite feeding port; the discharge port of the acidolysis tank is connected to the primary filtering equipment through an acidolysis pump and a pipeline.

[0008] Furthermore, the sedimentation tank is provided with an ammonia water addition port; the discharge port of the sedimentation tank is connected to the secondary filtering equipment through a sedimentation pump and a pipeline.

[0009] Furthermore, a buffer tank and a buffer pump are provided between the filtrate outlet of the secondary filtration equipment and the flash tower.

[0010] Buffer tanks and buffer pumps are also provided between the fluidized beds.

[0011] Furthermore, the flash tower is connected to the drying tower through a flash slurry delivery pump and a pipeline.

[0012] Furthermore, the drying tower is also provided with a hot air intake pipe, which is connected to the air intake of the drying tower through an intake pump.

[0013] Furthermore, both the primary filtration device and the secondary filtration device are filter presses.

[0014] Furthermore, the filter cake discharge port of the primary filtering device is connected to the sand and gravel yard through a first conveyor belt; the filter cake discharge ports of the secondary filtering devices are connected to the fluidized bed through a second conveyor belt.

[0015] The utility model has the following beneficial effects:

[0016] The utility model provides a device for preparing aluminum hydroxide and ammonium chloride from bauxite. By setting an acid hydrolysis tank, a precipitation tank, a flash tower, a vibrating fluidized bed, a powder spray drying tower, and a primary filter press and a secondary filter press, the recycling of hydrochloric acid and bauxite resources is realized, and a high-quality aluminum hydroxide product is obtained by chemical precipitation. Ammonium chloride is obtained by concentrating and spraying the ammonia-containing mother liquor. Therefore, the comprehensive utilization of elements such as aluminum, nitrogen, and chlorine can be realized, atomic economy is achieved, economic benefits are improved, and the problem that hydrochloric acid cannot be digested is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the utility model system. DETAILED DESCRIPTION

[0018] The embodiments of the present invention will be described in detail below in conjunction with examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0019] like Figure 1 As shown, a device for preparing aluminum hydroxide and ammonium chloride from bauxite includes an acid hydrolysis tank 1, a primary filtering device 4, a precipitation tank 5, a secondary filtering device 8, a flash tower 11 and a drying tower 15 which are arranged in sequence; wherein the filtrate outlet of the primary filtering device 4 is connected to the precipitation tank 5, and the filtrate outlet of the secondary filtering device 8 is connected to the flash tower 11; and the filter cake outlet of the secondary filtering device is connected to a fluidized bed 14, the fluidized bed 14 is provided with an aluminum hydroxide product outlet, and the drying tower 15 is provided with an ammonium chloride outlet.

[0020] In the preferred embodiment, the acidolysis tank 1 is provided with an acid adding pipeline and a bauxite feeding port; the discharge port of the acidolysis tank 1 is connected to the primary filtering device 4 through the acidolysis pump 3 and the pipeline. The bauxite and the acid solution react in the acidolysis tank, and the added acid solution can be hydrochloric acid. The slurry after the reaction is transported to the primary filtering device 4 for filtration, and the insoluble slag can be used as sand and gravel aggregate for concrete.

[0021] In the preferred embodiment, the precipitation tank 5 is provided with an ammonia water addition port; the discharge port of the precipitation tank 5 is connected to the secondary filtering device 8 through a precipitation pump 6 and a pipeline. Ammonia water is added to the filtrate after acid hydrolysis filtration to adjust the pH, and the chloride ions in the liquid will gradually generate aluminum hydroxide colloidal precipitation, which is transported to the secondary filtering device 8 for filtration, and the filter cake is aluminum hydroxide.

[0022] In the preferred embodiment, a buffer tank 9 and a buffer pump 10 are provided between the filtrate outlet of the secondary filtration device 8 and the flash tower 11, for receiving the filtrate generated by the secondary filtration device and inputting it into the flash tower for flash evaporation and concentration after buffering.

[0023] In the preferred embodiment, the flash tower 11 is connected to the drying tower 15 through the flash slurry delivery pump 12 and the pipeline. The slurry after flash evaporation concentration is dried in the drying tower to obtain the ammonium chloride product.

[0024] In a preferred embodiment, the drying tower 15 is further provided with a hot air intake pipe, which is connected to the air intake port of the drying tower 15 through an air intake pump 16 .

[0025] In the preferred embodiment, both the primary filtering device 4 and the secondary filtering device 8 are filter presses. Through graded treatment and filter pressing at each stage, the obtained products are graded and utilized, which can improve the quality of aluminum hydroxide after the second stage filtration.

[0026] In a preferred embodiment, the filter cake discharge port of the primary filtering device 4 is connected to the sand and gravel yard through a first conveyor belt 7 ; the filter cake discharge ports of the secondary filtering device 8 are connected to the fluidized bed through a second conveyor belt 13 .

[0027] In the specific operation, bauxite and hydrochloric acid are added to the acidolysis tank for acidolysis reaction, and the slurry after the reaction enters the primary filtering equipment for filtration, and the filter residue is transported to the yard, and is subsequently used as sand and gravel aggregate in the preparation of concrete. The filtrate is a solution containing aluminum ions, and the pH is adjusted by adding ammonia water so that the chloride ions form aluminum hydroxide and precipitate, and the aluminum hydroxide with high purity is obtained by filtration and separation again, and the product is obtained by fluidized bed drying. The ammonia-containing mother liquor after the secondary filtration is flash evaporated and concentrated, and the drying tower is sprayed with powder to dry to obtain the ammonium chloride product. The use of the practical device can realize the comprehensive utilization of elements such as aluminum, nitrogen, and chlorine, improve economic benefits, and consume industrial by-product hydrochloric acid.

[0028] The above embodiments are only for illustrating the technical ideas and features of the utility model, and the contents are only preferred embodiments of the utility model, but the protection scope of the utility model is not limited thereto. Within the technical scope disclosed by the utility model, equivalent changes or improvements based on the technical solution and utility model concept of the utility model should be included in the protection scope of the utility model.

Claims

1. A device for preparing aluminum hydroxide and ammonium chloride from bauxite, characterized in that: The invention comprises an acid hydrolysis tank (1), a primary filtering device (4), a sedimentation tank (5), a secondary filtering device (8), a flash tower (11) and a drying tower (15) which are arranged in sequence; wherein the filtrate outlet of the primary filtering device (4) is connected to the sedimentation tank (5), the filtrate outlet of the secondary filtering device (8) is connected to the flash tower (11); and the filter cake outlet of the secondary filtering device is connected to a fluidized bed (14), the fluidized bed (14) is provided with an aluminum hydroxide product outlet, and the drying tower (15) is provided with an ammonium chloride outlet.

2. The device according to claim 1, characterized in that: The acid hydrolysis tank (1) is provided with an acid addition pipeline and a bauxite feeding port; the discharge port of the acid hydrolysis tank (1) is connected to the primary filtering device (4) via an acid hydrolysis pump (3) and a pipeline.

3. The device according to claim 1, characterized in that: The sedimentation tank (5) is provided with an ammonia water inlet; the discharge port of the sedimentation tank (5) is connected to the secondary filtering device (8) via a sedimentation pump (6) and a pipeline.

4. The device according to claim 1, characterized in that: A buffer tank (9) and a buffer pump (10) are also provided between the filtrate outlet of the secondary filtration device (8) and the flash tower.

5. The device according to claim 1, characterized in that: The flash tower (11) is connected to the drying tower (15) via a flash slurry delivery pump (12) and a pipeline.

6. The device according to claim 5, characterized in that: The drying tower (15) is also provided with a hot air intake pipe, which is connected to the air intake of the drying tower (15) through an air intake pump (16).

7. The device according to claim 1, characterized in that: The primary filtering device (4) and the secondary filtering device (8) are both filter presses.

8. The device according to claim 1, characterized in that: The filter cake discharge port of the primary filtering device (4) is connected to the sand and gravel yard via a first conveyor belt (7); and the filter cake discharge port of the secondary filtering device (8) is connected to the fluidized bed via a second conveyor belt (13).

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