Method for preparing high-purity basic aluminum chloride based on boiling pyrolysis method

Abstract

The invention relates to the technical field of inorganic compound preparation, in particular to a method for preparing high-purity basic aluminum chloride based on a boiling pyrolysis method. In the preparation process of the basic aluminum chloride, a specific chloride is added to change the melting temperature of a system, so that the aluminum chloride is subjected to a melting reaction to generate a basic aluminum chloride suspension. Then, by means of variable-temperature treatment, the basic aluminum chloride in the turbid liquid is subjected to a dehydration reaction, decomposition of the basic aluminum chloride at the high temperature is effectively avoided, efficient solid-liquid separation is achieved, and the purity of the basic aluminum chloride is accurately controlled. According to the preparation method provided by the invention, the operation process is simple and convenient, the generation amount of acid gas in the preparation process can be remarkably reduced, the influence on the environment is reduced, and the production safety and environmental protection property are also improved.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic compound preparation, and in particular to a method for preparing high-purity basic aluminum chloride based on a boiling pyrolysis method. Background Art

[0002] With the acceleration of urbanization, people are increasingly in need of efficient, economical and adaptable water purifiers. Among them, basic aluminum chloride water purifier stands out among many water purifiers due to its excellent flocculation performance and wide applicability, becoming the preferred material in the water treatment industry. Although the boiling pyrolysis method using aluminum chloride as raw material can obtain solid products, the operating conditions are harsh, the equipment requirements are high, and the preparation process will produce a large amount of polluting gases, which will affect the environment.

[0003] At present, the boiling pyrolysis method of basic aluminum chloride is to select high-purity crystalline aluminum chloride, heat and decompose it in a boiling furnace, release hydrogen chloride gas and water vapor to generate powdered clinker. Then add an appropriate amount of water and stir to solidify to form a resinous product, and finally dry it to obtain a solid product of basic aluminum chloride. The reaction involved in this preparation method is relatively violent, and high requirements are placed on the accuracy and safety of the operation. It is necessary to prepare equipment such as a boiling furnace, and the equipment needs to take good anti-corrosion measures to prevent corrosive gases such as hydrogen chloride from being generated during the pyrolysis process from damaging the equipment. In addition, due to the violent reaction of the boiling pyrolysis method, impurities may be difficult to remove, and it is difficult to control the purity of the product. Therefore, the industry needs a relatively safe operation, stable product performance, low equipment requirements, and a relatively more economical technical method for preparing basic aluminum chloride. Summary of the invention

[0004] In order to solve the problems existing in the existing basic aluminum chloride preparation technology pointed out in the background technology, the present invention aims to provide a method for preparing basic aluminum chloride based on boiling pyrolysis method.

[0005] The preparation method of basic aluminum chloride of the present invention comprises the following steps:

[0006] (1) The chloride additive and aluminum chloride hexahydrate are thoroughly mixed and ground to obtain a mixture.

[0007] The chloride additive is a mixture of one or more of sodium chloride, potassium chloride, magnesium chloride and zinc chloride, and the amount of the chloride additive added is 5-25% of the mass of AlCl3 in aluminum chloride hexahydrate.

[0008] The particle size of the mixture is ≤75μm.

[0009] (2) placing the mixture in a crucible, heating it to 150°C to 180°C, and keeping it warm for 1 hour to allow it to fully melt and form a brown-yellow liquid;

[0010] (3) Heat the solution after fully melting the mixture to 250 - 400 °C and keep it warm for 1 - 2 h to form a brownish - black suspension;

[0011] (4) Cool the suspension to 150 - 180 °C to allow the basic aluminum chloride to hydrolyze. After keeping it warm for 3 - 5 hours, let the basic aluminum chloride settle naturally;

[0012] (5) Separate the basic aluminum chloride from the solution in step (4) and cool it. After cooling, wash the basic aluminum chloride with deionized water and dry it under vacuum at 80 °C to produce black basic aluminum chloride.

[0013] The preparation method of basic aluminum chloride provided by the present invention. First, heat the chloride raw material containing aluminum chloride to make it melt and turn into a liquid state. On the one hand, the liquid state can significantly accelerate the reaction rate between aluminum chloride and water. On the other hand, it can also be well - mixed with the solid basic aluminum chloride directly formed by the reaction. When the temperature rises above 200 °C, aluminum chloride reacts with water and oxygen to form a basic aluminum chloride suspension. To prevent the decomposition of basic aluminum chloride during long - term heat preservation in a high - temperature environment, after the reaction ends, the temperature needs to be quickly lowered below 200 °C to promote the polycondensation of basic aluminum chloride to form a polymer. Subsequently, separate the generated polymer, wash it with deionized water, and finally dry it to obtain a high - purity basic aluminum chloride product.

[0014] The operation of the present invention is relatively mild and the process is simple, which can be achieved by controlling the temperature and time. The obtained product has stable performance, and the quality of the product can be controlled at each step. For example: some impurities can be removed in the sedimentation step, and the washing with deionized water can further purify the product. This process has low requirements for equipment, does not generate a large amount of acidic gases during the reaction process, has low cost, and is easy to produce and apply. Brief Description of the Drawings

[0015] Figure 1 is the morphology of the basic aluminum chloride prepared in Example 1 of the present invention;

[0016] Figure 2 is the SEM image of the basic aluminum chloride prepared in Example 1 of the present invention;

[0017] Figure 3 is the infrared spectrum of the basic aluminum chloride prepared in Example 1 of the present invention. Detailed Description of the Invention

[0018] The method for controlling temperature and sedimentation to purify chloride molten salt will be described in detail below with specific chloride molten salt combination examples. All operations in the following examples are completed in a glove box, and the protective gas is high - purity nitrogen.

[0019] Example 1

[0020] 1) Weigh 10 g of sodium chloride and 90 g of aluminum chloride hexahydrate, mix the two chlorides and grind them evenly. The particle size of the mixture is ≤ 75 μm.

[0021] 2) Pour the mixture into a crucible, place it in a heating furnace, raise the temperature to 170 °C, and keep it at a constant temperature for 1 hour to melt the white solid into a brownish-yellow liquid.

[0022] 3) After the solid is melted, raise the temperature to 350 °C and keep it at a constant temperature for 2 hours to form black solids in the liquid.

[0023] 4) Cool the liquid to 140 °C and keep it at a constant temperature for 3 hours to allow the black solids to settle.

[0024] 5) After the black solids have completely settled, filter out the basic aluminum chloride with a nickel mesh and wash it with deionized water. After washing, dry it in an 80 °C drying oven.

[0025] 6) Test its Al content and basicity according to the national standard GB 15892-1995.

[0026] 7) Measure the sample on a Vector33 Fourier transform infrared spectrometer with a scanning range of 4000 - 400 m -1 .

[0027] Example 2

[0028] 1) Weigh 20 g of sodium chloride and 80 g of aluminum chloride hexahydrate, mix the two chlorides and grind them evenly. The particle size of the mixture is ≤ 75 μm.

[0029] 2) Pour the mixture into a crucible, place it in a heating furnace, raise the temperature to 170 °C, and keep it at a constant temperature for 1 hour to melt the white solid into a brownish-yellow liquid.

[0030] 3) After the solid is melted, raise the temperature to 350 °C and keep it at a constant temperature for 2 hours to form black solids in the liquid.

[0031] 4) Cool the liquid to 140 °C and keep it at a constant temperature for 3 hours to allow the black solids to settle.

[0032] 5) After the black solids have completely settled, filter out the basic aluminum chloride with a nickel mesh and wash it with deionized water. After washing, dry it in an 80 °C drying oven.

[0033] 6) Test its Al content and basicity according to the national standard GB 15892-1995.

[0034] Example 3

[0035] 1) Weigh 5 g of sodium chloride and 95 g of aluminum chloride hexahydrate, mix the two chlorides and grind them evenly. The particle size of the mixture is ≤ 75 μm.

[0036] 2) Pour the mixture into a crucible, place it in a heating furnace, heat it up to 170 °C, and keep it at a constant temperature for 1 hour to melt the white solid into a brownish-yellow liquid.

[0037] 3) After the solid melts, heat it up to 350 °C and keep it at a constant temperature for 2 hours to form black solids in the liquid.

[0038] 4) Cool the liquid to 140 °C and keep it at a constant temperature for 3 hours to allow the black solids to settle.

[0039] 5) After the black solids have completely settled, filter out the basic aluminum chloride with a nickel mesh and wash it with deionized water. After washing, dry it in an 80 °C drying oven.

[0040] 6) Test its Al content and basicity according to the national standard GB 15892-1995.

[0041] Example 4

[0042] 1) Weigh 10 g of magnesium chloride and 90 g of aluminum chloride hexahydrate, mix the two chlorides and grind them evenly, with the particle size of the mixture ≤ 75 μm.

[0043] 2) Pour the mixture into a crucible, place it in a heating furnace, heat it up to 170 °C, and keep it at a constant temperature for 1 hour to melt the white solid into a brownish-yellow liquid.

[0044] 3) After the solid melts, heat it up to 350 °C and keep it at a constant temperature for 2 hours to form black solids in the liquid.

[0045] 4) Cool the liquid to 140 °C and keep it at a constant temperature for 3 hours to allow the black solids to settle.

[0046] 5) After the black solids have completely settled, filter out the basic aluminum chloride with a nickel mesh and wash it with deionized water. After washing, dry it in an 80 °C drying oven.

[0047] 6) Test its Al content and basicity according to the national standard GB 15892-1995.

[0048] Example 5

[0049] 1) Weigh 10 g of sodium chloride and 90 g of aluminum chloride hexahydrate, mix the two chlorides and grind them evenly, with the particle size of the mixture ≤ 75 μm.

[0050] 2) Pour the mixture into a crucible, place it in a heating furnace, heat it up to 170 °C, and keep it at a constant temperature for 1 hour to melt the white solid into a brownish-yellow liquid.

[0051] 3) After the solid melts, heat it up to 250 °C and keep it at a constant temperature for 2 hours to form black solids in the liquid.

[0052] 4) Cool the liquid to 140 °C and keep it at a constant temperature for 3 hours to allow the black solid to settle.

[0053] 5) After the black solid has completely settled, filter out the basic aluminum chloride with a nickel mesh and wash it with deionized water. After washing, dry it in an 80 °C drying oven.

[0054] 6) Test its Al content and basicity according to the national standard as specified in GB 15892-1995.

[0055] Example 6

[0056] 1) Weigh 10 g of sodium chloride and 90 g of aluminum chloride hexahydrate, mix and grind the two chlorides evenly, and the particle size of the mixture is ≤75 μm.

[0057] 2) Pour the mixture into a crucible, place it in a heating furnace, heat it up to 250 °C, and keep it at a constant temperature for 1 hour to melt the white solid into a liquid.

[0058] 3) After the solid has melted, heat it up to 350 °C and keep it at a constant temperature for 2 hours to form a black solid in the liquid.

[0059] 4) Cool the liquid to 140 °C and keep it at a constant temperature for 3 hours to allow the black solid to settle.

[0060] 5) After the black solid has completely settled, filter out the basic aluminum chloride with a nickel mesh and wash it with deionized water. After washing, dry it in an 80 °C drying oven.

[0061] 6) Test its Al content and basicity according to the national standard as specified in GB 15892-1995.

[0062] Comparative Example 1

[0063] 1) Weigh 100.0 g of aluminum chloride hexahydrate (AlCl3·6H2O, purity ≥98%), and crush it to a particle size of 0.5 - 2 mm with a crusher.

[0064] 2) Evenly spread the raw materials into the hopper of the fluidized bed furnace. Heat it up to 240 °C and keep it at a constant temperature for 2 h to produce powdered clinker.

[0065] 3) Add the powdered clinker and deionized water to the reaction kettle at a mass ratio of 1:0.8, and control the water temperature at 50 °C.

[0066] 4) Stir and react in a closed reaction kettle at 2000 rpm for 2 hours, and maintain the temperature at 60 °C to form a resinous gel product.

[0067] 5) Let the gel stand and age in a constant temperature environment at 60 °C for 30 minutes to enhance the stability of the product.

[0068] 6) The solidified product is placed in a drying oven at 110 °C and dried for 20 minutes to obtain white or light yellow basic aluminum chloride.

[0069] 6) Test its Al content and basicity according to the national standard as specified in GB 15892-1995.

[0070] Table 1

[0071]

[0072] The preparation method of the present invention is a new method based on the boiling pyrolysis method. The highest reaction temperature is 250-400 °C. Relatively speaking, the requirement for the high-temperature resistance performance of the equipment is not so high, and the energy consumption is also relatively small, which helps to reduce the production cost. Moreover, the reaction process of this method of the invention is relatively stable, and the reaction conditions of each step are relatively easy to control, so that the chemical composition and structure of the generated basic aluminum chloride are more stable, thus ensuring the stability of the product performance.

[0073] The above are only the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. That is, all simple, equivalent changes and modifications made according to the claims and the content of the specification of the present invention application fall within the scope of the claims of the present invention patent. The content not described in detail in the present invention is all conventional technical content.

Claims

1. A method for preparing high-purity basic aluminum chloride by boiling pyrolysis method, characterized in that, The method steps are as follows: (1) Thoroughly mix and grind the chloride additive and aluminum chloride hexahydrate to obtain a mixture; (2) Place the mixture in a crucible, heat and keep it warm to fully melt it into a liquid; (3) Heat up the liquid after the mixture is fully melted to react and generate a suspension; (4) Cool down the suspension to cause the dehydration reaction of basic aluminum chloride, and after heat preservation, the basic aluminum chloride settles naturally; (5) Separate the basic aluminum chloride in step (4) from the solution and cool it; after cooling, wash the basic aluminum chloride with deionized water and perform vacuum drying treatment at 80°C.

2. The method for preparing high-purity basic aluminum chloride by boiling pyrolysis according to claim 1, characterized in that, In step (1), the chloride additive is one or a mixture of more of: sodium chloride, potassium chloride, magnesium chloride, zinc chloride; the addition amount of the chloride additive is 5-25% of the mass of AlCl3 in aluminum chloride hexahydrate.

3. The method for preparing high-purity basic aluminum chloride based on the boiling pyrolysis method according to claim 1, characterized in that, In step (1), the particle size of the mixture ≤ 75 μm.

4. The method for preparing high-purity basic aluminum chloride by boiling pyrolysis according to claim 1, characterized in that, In step (2), the heating temperature is: 130°C to 180°C, keep warm for 1 h, and a brownish-yellow liquid is generated after full melting.

5. The method for preparing high-purity basic aluminum chloride based on the boiling pyrolysis method according to claim 1, characterized in that, In step (3), heat up to 250-400°C and react for 1-2 h to produce a suspension that is brownish and close to black.

6. The method for preparing high-purity basic aluminum chloride based on the boiling pyrolysis method according to claim 1, wherein In step (4), cool down the suspension to 150-180°C, keep warm for 3-5 hours to make the basic aluminum chloride settle naturally, and generate black basic aluminum chloride.

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