Continuous crystallization method of zirconium oxychloride

Abstract

A continuous crystallization method of zirconium oxychloride comprises the following steps: simultaneously adding a zirconium oxychloride concentrated solution and a zirconium oxychloride crystallization mother solution into a 1 # crystallization tank, and controlling the flow of the crystallization mother solution, so that the temperature of the 1 # crystallization tank is stabilized at a first preset temperature; after the reaction in the 1 # crystallizing tank is stable, the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother solution are continuously fed, so that the liquid level of the 1 # crystallizing tank is kept constant, and meanwhile, overflow liquid of the 1 # crystallizing tank continuously enters the 2 # crystallizing tank from an overflow port; the temperature of the 2 # crystallizing tank is stabilized at a second preset temperature by controlling the flow rate of circulating water in the cooling circulating system, overflow liquid of the 1 # crystallizing tank continuously enters the 2 # crystallizing tank, and meanwhile, materials produced in the 2 # crystallizing tank continuously enter the centrifugal machine through a discharging opening, so that the liquid level of the 2 # crystallizing tank is kept constant; and part of crystallization mother liquor produced by the centrifugal machine is returned to the 1 # crystallization tank to participate in the reaction. Intermediate reaction equipment is greatly reduced by adopting a production mode of continuous crystallization of zirconium oxychloride, and the crystallization time of materials in each pot can be greatly shortened by continuous feeding and discharging, so that the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of zirconium oxychloride, and in particular to a continuous crystallization method of zirconium oxychloride. Background Art

[0002] Zirconium oxychloride is an important basic raw material for metallurgy and chemical industry. Metal zirconium can be used as core material control material for nuclear power and nuclear military applications. With the development of national nuclear power technology, the demand for zirconium materials for nuclear power will increase greatly. In addition, zirconium oxychloride can also be used to prepare dozens of zirconium compounds such as zirconium oxide, zirconium carbonate, zirconium sulfate, zirconium nitrate, etc., which are widely used in structural ceramics, electronic appliances, solid fuel cells, high-end coatings, papermaking and other fields.

[0003] At present, the method for preparing zirconium oxychloride in the zirconium oxyoxide industry mainly adopts the "one acid one alkali" method, which decomposes zircon sand to obtain a composite salt of zirconium and silicon, then washes and acid-leaches to remove impurities to obtain a zirconium oxychloride aqueous solution, and then concentrates and crystallizes the solution and centrifuges to obtain the finished zirconium oxychloride. The process flow is as follows: alkali calcination ➪ water washing ➪ acidification ➪ water dissolution ➪ concentration ➪ crystallization ➪ acid washing centrifugation ➪ zirconium oxychloride. In the "one acid one alkali" method, secondary crystallization mainly adopts an intermittent production method, generally using a 5000-10000 liter enamel reactor, and water circulation cooling and cooling. The secondary crystallization process is as follows: the zirconium oxychloride concentrate is pumped into the enamel reactor, stirring and circulating water are turned on, the temperature of the zirconium oxychloride concentrate is reduced from 90°C to 30°C, and the zirconium oxychloride is crystallized from the concentrate. The crystallization process of zirconium oxychloride is controlled by controlling the flow rate of circulating water.

[0004] The existing zirconium oxychloride secondary crystallization process adopts an intermittent production method, which has the disadvantages of poor product consistency, multiple equipments and complicated operation. Especially in today's increasingly stringent safety and environmental protection requirements, the intermittent production method is not conducive to the safety and environmental protection risk control in the production process. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a continuous crystallization method of zirconium oxychloride. The crystallization method realizes the primary crystallization cooling of zirconium oxychloride by using the crystallization mother liquor produced in the zirconium oxychloride crystallization process, and then realizes the cooling crystallization process of concentrated zirconium oxychloride solution by water circulation cooling, and the quality of zirconium oxychloride product reaches the standard.

[0006] A method for continuous crystallization of zirconium oxychloride comprises the following steps: Step S11, adding the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother liquor into the 1# crystallization tank at the same time, and controlling the flow rate of the crystallization mother liquor so that the temperature of the 1# crystallization tank is stabilized at a first preset temperature; Step S12, after the reaction in the 1# crystallizer is stabilized, the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother solution are continuously fed to keep the liquid level of the 1# crystallizer constant, and at the same time, the overflow liquid of the 1# crystallizer continuously enters the 2# crystallizer from the overflow port; Step S13, by controlling the flow rate of circulating water in the cooling circulation system, the temperature of the 2# crystallizer is stabilized at the second preset temperature, and the overflow liquid of the 1# crystallizer continuously enters the 2# crystallizer, and the material produced in the 2# crystallizer continuously enters the centrifuge through the discharge port, so that the liquid level of the 2# crystallizer is kept constant; Step S14, returning part of the crystallization mother liquor produced by the centrifuge to the 1# crystallization tank to participate in the reaction.

[0007] Preferably, in step S11, the temperature of the zirconium oxychloride concentrated solution is 75-95°C, and the temperature of the crystallization mother solution is 10-30°C; The acidity of the zirconium oxychloride concentrate is 5-7N, the zirconium content is 160-220 g / L, the acidity of the crystallization mother liquor is 5-7N, the zirconium content is 20-60 g / L; The flow ratio of zirconium oxychloride concentrated solution to crystallization mother liquor is 1:0.2-2.

[0008] Preferably, in step S11, the first preset temperature is 40-60°C.

[0009] Preferably, in step S13, the second preset temperature is 10-30°C.

[0010] Preferably, in step S13, the temperature of the circulating water is 5-10°C.

[0011] Compared with the prior art, the present invention has the following beneficial effects: First, reduce costs and simplify operations: by adopting the production method of continuous crystallization of zirconium oxychloride, a large number of enamel reactors, acid mist absorption systems, temperature control systems, and discharging system equipment are reduced, thereby reducing investment and equipment maintenance costs; the present invention enables automatic control of the cooling and crystallization process of zirconium oxychloride concentrate, thereby simplifying operations; Second, improve production efficiency and improve product quality consistency: the intermittent production process of secondary crystallization of zirconium oxychloride takes 16 hours for each pot of material. The present invention can reduce the crystallization time of each pot of material to 6-8 hours by continuously feeding and discharging materials, thereby greatly improving production efficiency; the continuous crystallization production method of the present invention makes the material crystallization process unaffected by the monomer equipment, and the process control parameters are consistent, thereby reducing product quality fluctuations and improving product quality consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The present invention provides a schematic flow chart of the continuous crystallization method of zirconium oxychloride. DETAILED DESCRIPTION

[0013] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0014] See also Figure 1 An embodiment of the present invention provides a method for continuous crystallization of zirconium oxychloride, comprising the following steps: Step S11, adding the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother liquor into the 1# crystallization tank at the same time, and controlling the flow rate of the crystallization mother liquor so that the temperature of the 1# crystallization tank is stabilized at a first preset temperature; In this step, the temperature of the zirconium oxychloride concentrated solution is 75-95°C, and the temperature of the crystallization mother solution is 10-30°C; The acidity of the zirconium oxychloride concentrate is 5-7N, the zirconium content is 160-220 g / L, the acidity of the crystallization mother liquor is 5-7N, the zirconium content is 20-60 g / L; The flow ratio of zirconium oxychloride concentrated solution to crystallization mother liquor is 1:0.2-2.

[0015] The first preset temperature is 40-60° C. by continuously feeding the zirconium oxychloride concentrated solution and the crystallization mother liquor.

[0016] Step S12, after the reaction in the 1# crystallizer is stabilized, the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother solution are continuously fed to keep the liquid level of the 1# crystallizer constant, and at the same time, the overflow liquid of the 1# crystallizer continuously enters the 2# crystallizer from the overflow port; Step S13, by controlling the flow rate of circulating water in the cooling circulation system, the temperature of the 2# crystallizer is stabilized at the second preset temperature, and the overflow liquid of the 1# crystallizer continuously enters the 2# crystallizer, and the material produced in the 2# crystallizer continuously enters the centrifuge through the discharge port, so that the liquid level of the 2# crystallizer is kept constant; In this step, the second preset temperature is 10-30°C, and the temperature of the circulating water is 5-10°C.

[0017] Step S14, returning part of the crystallization mother liquor produced by the centrifuge to the 1# crystallization tank to participate in the reaction.

[0018] It should be noted that the present invention adopts a production method of continuous crystallization of zirconium oxychloride, which greatly reduces the enamel reactor, acid mist absorption system, temperature control system, and discharge system equipment, thereby reducing investment and equipment maintenance costs; and the present invention can reduce the crystallization time of each pot of material to 6-8 hours through continuous feeding and discharging, greatly improving production efficiency; the continuous crystallization production method makes the material crystallization process unaffected by the single equipment, and the process control parameters are consistent, thereby reducing product quality fluctuations and improving product quality consistency. Example

[0019] Start stirring in No. 1 crystallization tank, open the feed valve of zirconium oxychloride concentrate (set flow rate to 1m³ / h, concentrated zirconium liquid temperature to 95℃, acidity to 5.5-6N, zirconium content to 160-170g / L), and the feed valve of crystallization mother liquor (set flow rate to 1.2m³ / h, mother liquor temperature to 15℃, acidity to 5.5-6N, zirconium content to 15-20g / L), open the overflow port 1 valve when the liquid level of No. 1 crystallization tank approaches the overflow port, start stirring in No. 2 crystallization tank, start the cooling circulation system (circulating water temperature is controlled at 5-10℃), open the discharge valve of the discharge port when the liquid level of No. 2 crystallization tank rises to the overflow port, and the crystallized material enters the acid washing centrifugation process. Example

[0020] Start stirring in No. 1 crystallization tank, open the feed valve of zirconium oxychloride concentrate (set flow rate to 0.8m³ / h, concentrated zirconium liquid temperature to 85℃, acidity to 6.0-6.5N, zirconium content to 180-200g / L), and the feed valve of crystallization mother liquor (set flow rate to 1.0m³ / h, mother liquor temperature to 15℃, acidity to 5.8-6.2N, zirconium content to 15-20g / L), open the overflow port 1 valve when the liquid level of No. 1 crystallization tank approaches the overflow port, start stirring in No. 2 crystallization tank, start the cooling circulation system (circulating water temperature is controlled at 5-10℃), open the discharge valve of the discharge port when the liquid level of No. 2 crystallization tank rises to the overflow port, and the crystallized material enters the acid washing centrifugation process. Example

[0021] Start stirring in No. 1 crystallization tank, open the feed valve of zirconium oxychloride concentrate (set flow rate to 1.5m³ / h, concentrated zirconium liquid temperature to 80℃, acidity to 6.5-7N, zirconium content to 200-210g / L), and the feed valve of crystallization mother liquor (set flow rate to 1.4m³ / h, mother liquor temperature to 15℃, acidity to 5.8-6.2N, zirconium content to 15-20g / L), open the overflow port 1 valve when the liquid level of No. 1 crystallization tank approaches the overflow port, start stirring in No. 2 crystallization tank, start the cooling circulation system (circulating water temperature is controlled at 5-10℃), open the discharge valve of the discharge port when the liquid level of No. 2 crystallization tank rises to the overflow port, and the crystallized material enters the pickling centrifugal process.

[0022] The products produced in Examples 1, 2 and 3 were subjected to comparative tests, and the results are as follows:

[0023] It can be seen from the above table that after the implementation of continuous crystallization, all indicators of zirconium oxychloride products can meet the control requirements.

[0024] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for continuous crystallization of zirconium oxychloride, characterized in that: The following steps are involved: Step S11, adding the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother liquor into the 1# crystallization tank at the same time, and controlling the flow rate of the crystallization mother liquor so that the temperature of the 1# crystallization tank is stabilized at a first preset temperature; Step S12, after the reaction in the 1# crystallizer is stabilized, the zirconium oxychloride concentrated solution and the zirconium oxychloride crystallization mother solution are continuously fed to keep the liquid level of the 1# crystallizer constant, and at the same time, the overflow liquid of the 1# crystallizer continuously enters the 2# crystallizer from the overflow port; Step S13, by controlling the flow rate of circulating water in the cooling circulation system, the temperature of the 2# crystallizer is stabilized at the second preset temperature, and the overflow liquid of the 1# crystallizer continuously enters the 2# crystallizer, and the material produced in the 2# crystallizer continuously enters the centrifuge through the discharge port, so that the liquid level of the 2# crystallizer is kept constant; Step S14, returning part of the crystallization mother liquor produced by the centrifuge to the 1# crystallization tank to participate in the reaction.

2. A method for continuous crystallization of zirconium oxychloride according to claim 1, characterized in that: In step S11, the temperature of the zirconium oxychloride concentrated solution is 75-95°C, and the temperature of the crystallization mother solution is 10-30°C; The acidity of the zirconium oxychloride concentrate is 5-7N, the zirconium content is 160-220 g / L, the acidity of the crystallization mother liquor is 5-7N, the zirconium content is 20-60 g / L; The flow ratio of zirconium oxychloride concentrated solution to crystallization mother liquor is 1:0.2-2.

3. A method for continuous crystallization of zirconium oxychloride according to claim 1, characterized in that: In step S11, the first preset temperature is 40-60°C.

4. A method for continuous crystallization of zirconium oxychloride according to claim 1, characterized in that: In step S13, the second preset temperature is 10-30°C.

5. A method for continuous crystallization of zirconium oxychloride according to claim 1, characterized in that: In step S13, the temperature of the circulating water is 5-10°C.

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