Method for increasing granularity of sodium perchlorate crystal

Abstract

The invention relates to a method for increasing the granularity of sodium perchlorate crystals, and belongs to the technical field of industrial crystallization. The invention mainly solves the technical problems of small particle size and easy hardening in the existing sodium perchlorate production process. According to the technical scheme, the method for increasing the particle size of the sodium perchlorate crystal comprises the following steps: 1) preparing a sodium perchlorate concentrated solution: dissolving a sodium perchlorate crude product in water, and concentrating the sodium perchlorate solution; 2) determining the addition amount of the seed crystal: calculating the addition amount of the seed crystal according to a formula Ms = (Ls / Lf) 3Mf; and 3) cooling crystallization: filtering the sodium perchlorate concentrated solution in the step 1) into a cooling storage tank, after the temperature of the sodium perchlorate concentrated solution is reduced to 73-95 DEG C, putting the sodium perchlorate concentrated solution into a DTB crystallizer, then adding a seed crystal, and after the temperature is reduced to 25-40 DEG C, centrifuging the solution. The method has the advantages of simplicity in operation, large and uniform crystal granularity, difficulty in hardening of products and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial crystallization and relates to a method for increasing the particle size of sodium perchlorate crystals. BACKGROUND

[0002] Sodium perchlorate, with the chemical formula NaClO4, is a white crystalline powder with hygroscopicity. It decomposes at 482°C, is easily soluble in water, and is soluble in ethanol and acetone, but insoluble in diethyl ether. As a strong oxidizing agent, sodium perchlorate exhibits its unique value in multiple fields. First, it is an important raw material for the production of perchloric acid and other perchlorate salts, and is widely used in the chemical synthesis and pharmaceutical industries. Second, in the explosives industry, sodium perchlorate is a key component in the manufacture of explosives such as gelatin dynamite, and its strong oxidizing property helps to enhance the explosive power of explosives. In addition, sodium perchlorate can also be used as an analytical reagent and an oxidizing agent, and plays an important role in chemical analysis, material synthesis, etc.

[0003] However, the existing sodium perchlorate products are mostly naturally precipitated in powder form, which is easy to harden and thus affects the subsequent use of the product. When crushing the hardened product, there is a risk of explosion. Therefore, it is of great significance to seek an efficient crystallization method to obtain large-grained sodium perchlorate. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a method for increasing the particle size of sodium perchlorate crystals, which solves the technical problems of small crystal particle size and easy hardening in the existing sodium perchlorate production process.

[0005] The present application is achieved by the following technical solutions.

[0006] A method for increasing the particle size of sodium perchlorate crystals, comprising the following steps.

[0007] 1) Preparation of sodium perchlorate concentrated solution: Dissolve sodium perchlorate crude product in water, and concentrate the sodium perchlorate solution at high temperature to achieve a density of 1.66-1.78 g / cm 3 at high temperature.

[0008] 2) Determining the addition amount of crystal seeds: Calculate the addition amount of crystal seeds according to the formula Ms=(Ls / Lf) 3 Mf, where Ms represents the mass of the crystal seeds; Ls represents the particle size of the crystal seeds; Lf represents the particle size of the target crystal; and Mf represents the mass of the target crystal.

[0009] 3) cooling crystallization: the sodium perchlorate concentrated solution in step 1) is filtered into a cooling storage tank, and when the temperature thereof is lowered to 73-95℃, it is placed into a DTB crystallizer, then the corresponding amount of crystal seeds calculated in step 2) is added, and the temperature is continuously lowered and the stirring is continuously carried out at a speed of 80-180r / min, and when the temperature is lowered to 25-40℃, the solution is centrifuged, and sodium perchlorate crystals with large and uniform particle size are obtained.

[0010] The present application is characterized in that when the temperature of the sodium perchlorate solution is lowered to the metastable zone, a proper amount of sodium perchlorate crystal seeds is added, so that the subsequent crystals grow on the added crystal seeds during the continuous temperature lowering process, and thus the number of crystals does not increase, but only the particle size increases; and during the crystallization process, the temperature of the solution does not rise, and thus the crystallization time is not increased, and the crystallization efficiency is greatly improved. Compared with the prior art, the present application has the advantages of simple operation, large and uniform crystal particle size, and high crystallization efficiency. DETAILED DESCRIPTION

[0011] The present application will be further described in detail below in combination with examples. Example 1

[0012] The method for increasing the particle size of sodium perchlorate crystals in the present example comprises the following steps:

[0013] 1) Preparation of sodium perchlorate concentrated solution: sodium perchlorate crude product is dissolved in water, filtered, and the sodium perchlorate solution is concentrated at high temperature, so that the density thereof reaches 1.78g / cm 3 at 130℃, and at this time, the mass of the concentrated solution is 9.56kg.

[0014] 2) Determination of the amount of crystal seeds to be added: the amount of crystal seeds to be added is calculated according to the formula Ms=(Ls / Lf) 3 Mf, wherein Ms represents the mass of the crystal seeds; Ls represents the particle size of the crystal seeds; L f represents the particle size of the target crystals; and Mf represents the mass of the target crystals; and this time, about Ms=(1 / 4) 3 ×4=0.063Kg of sodium perchlorate crystal seeds with a particle size of about 0.1mm needs to be added.

[0015] 3) Cooling crystallization: the sodium perchlorate concentrated solution in step 1) is filtered into a cooling storage tank, and when the temperature thereof is lowered to 95℃, it is placed into a DTB crystallizer, and when the temperature is lowered to 90℃, the corresponding amount of crystal seeds calculated in step 2) is added, and the temperature is continuously lowered and the stirring is continuously carried out at a speed of 80r / min, and when the temperature is lowered to 30℃, the solution is centrifuged, and sodium perchlorate crystals are obtained, the output is 4.04kg, and 90% of the crystal particle size is greater than 0.4mm. Example 2

[0016] The method for increasing the particle size of sodium perchlorate crystals in this embodiment includes the following steps:

[0017] 1) Preparation of concentrated sodium perchlorate solution: Crude sodium perchlorate was dissolved in water, filtered, and the solution was concentrated at high temperature to a concentration of 1.71 g / cm³ at 127°C. 3 The density is such that the mass of the concentrate is 9.07 kg.

[0018] 2) Determine the amount of seed crystals to add: according to the formula Ms=(Ls / Lf) 3 Mf calculates the amount of seed crystal to be added; approximately Ms = (1 / 4) is needed in this case. 3 ×3 = 0.047 kg of sodium perchlorate crystals with a particle size of approximately 0.1 mm.

[0019] 3) Cooling crystallization: Filter the sodium perchlorate concentrate from step 1) into a cooling storage tank. After the temperature drops to 90°C, place it in a DTB crystallizer. When the temperature drops to 85°C, add the corresponding amount of seed crystals calculated in step 2). Continue cooling and stirring at a speed of 120 r / min. After the temperature drops to 40°C, centrifuge to obtain sodium perchlorate crystals. The output is 3.18 kg, and 90% of the crystals have a particle size greater than 0.4 mm. Example 3

[0020] The method for increasing the particle size of sodium perchlorate crystals in this embodiment includes the following steps:

[0021] 1) Preparation of concentrated sodium perchlorate solution: Crude sodium perchlorate was dissolved in water, filtered, and the solution was concentrated at high temperature to achieve a concentration of 1.68 g / cm³ at 126°C. 3 The density is such that the mass of the concentrate is 10.90 kg.

[0022] 2) Determine the amount of seed crystals to add: according to the formula Ms=(Ls / Lf) 3 Mf calculates the amount of seed crystal to be added; approximately Ms = (1 / 4) is needed in this case. 3 ×3 = 0.047 kg of sodium perchlorate crystals with a particle size of approximately 0.1 mm.

[0023] 3) Cooling crystallization: Filter the sodium perchlorate concentrate from step 1) into a cooling storage tank. After the temperature drops to 80°C, place it in a DTB crystallizer. When the temperature drops to 74°C, add the corresponding amount of seed crystals calculated in step 2). Continue cooling and stirring at a speed of 180 r / min. After the temperature drops to 25°C, centrifuge to obtain sodium perchlorate crystals. The output is 2.89 kg, and 90% of the crystals have a particle size greater than 0.4 mm.

[0024] The invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, according to the disclosed technical content. Therefore, substitutions and modifications that fall within the scope of the claims or their equivalents should be covered by the claims.

Claims

1. A method of increasing the particle size of sodium perchlorate crystalline crystals, characterized by: The method comprises the following steps: 1) Preparation of sodium perchlorate concentrate: Dissolve sodium perchlorate crude product in water, concentrate the sodium perchlorate solution at high temperature, so that it reaches a density of 1.66-1.78 g / cm 3 at high temperature; 2) Determining the amount of seed to be added: According to the formula Ms = (Ls / Lf) 3 Mf calculates the amount of seed to be added, where Ms represents the mass of the seed; Ls represents the particle size of the seed; Lf represents the particle size of the target crystal; and Mf represents the mass of the target crystal. 3) cooling crystallization: the concentrated sodium perchlorate solution in step 1) is filtered into a cooling storage tank, and when the temperature of the solution is lowered to 73-95 DEG C, the solution is put into a DTB crystallizer, then the corresponding amount of crystal seeds calculated in step 2) is added, and the temperature is continuously lowered and the solution is continuously stirred at a stirring speed of 80-180 r / min; when the temperature is lowered to 25-40 DEG C, the solution is centrifuged, and sodium perchlorate crystals with large and uniform particle size are obtained.