Process and equipment for purifying potassium fluotitanate

Abstract

The invention belongs to the technical field of titanium alloy processing raw materials, and discloses a process and equipment for purifying potassium fluotitanate. The purification equipment comprises primary cleaning equipment, recrystallization equipment and acid treatment equipment; the primary cleaning equipment comprises a primary cleaning tank and a first filter, a material inlet of the primary cleaning tank is connected to the K2TiF6 storage tank through a pipeline, a material outlet of the primary cleaning tank is connected to the first filter through a pipeline, a liquid phase outlet of the first filter is connected to the acid treatment equipment, and a solid phase outlet of the first filter is connected to the recrystallization equipment; the recrystallization equipment comprises a stirring heater, a second filter, a cooling crystallization tank and a third filter which are connected in sequence; the acid treatment equipment comprises an acid storage tank, a neutralization tank, a fourth filter and a distillation tower which are connected in sequence. According to the purification process and equipment disclosed by the invention, residual acid can be removed, the purity of the product is improved, harmful substances can be effectively recovered and treated, the pollution to the environment is reduced, and the economic effect of enterprises is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy processing raw materials, and specifically relates to a purification process and equipment for potassium fluorotitanate. Background Art

[0002] In the titanium metal processing process, pickling is a common treatment method for removing the titanium oxide layer. Generally, a mixed acid of HF and HNO3 is used as the titanium metal pickling solution. However, during the pickling process, titanium ions will continue to dissolve into the titanium metal pickling solution. When the titanium metal pickling solution is used to a certain extent, a large amount of titanium ions accumulate in the solution, resulting in an increase in the viscosity of the solution, and the corrosion removal performance of the solution of the titanium oxide layer deteriorates. When the mass concentration of titanium ions in the solution reaches 50g / L, the ability of the pickling solution to remove the titanium oxide layer on the surface of the titanium metal drops sharply, the surface quality of the titanium metal decreases, and the solution reaches a scrap state at the solubility limit. The scrapped pickling solution contains a large amount of acid and titanium metal ions. By adding potassium salt to separate and recover Ti ions in the form of potassium fluorotitanate precipitation, it is an environmentally friendly and efficient titanium recovery and pickling solution regeneration method. The recovered potassium fluorotitanate often contains various impurities, the most important of which are acidic impurities such as hydrofluoric acid and nitric acid entrained during the precipitation process. How to further purify the recovered potassium fluorotitanate product is a technical problem that technicians in this field need to solve.

[0003] At present, the purification of potassium fluorotitanate mainly adopts the simple recrystallization method: ① Dissolution: Heat the potassium fluorotitanate raw material containing impurities to a high temperature in an appropriate solvent to completely dissolve it. ② Filtration: Filter the dissolved solution while hot to remove insoluble impurities. ③ Cooling crystallization: Slowly cool the filtrate to room temperature or lower temperature to precipitate potassium fluorotitanate crystals. ④ Crystal collection, washing and drying: Collect the precipitated potassium fluorotitanate crystals by filtration or centrifugation, wash the crystals with ice water, remove the attached mother liquor and impurities, and dry them. However, the simple recrystallization method still has the following disadvantages and shortcomings:

[0004] ① Insufficient residual acid treatment: The simple recrystallization method may not be able to effectively remove residual acids in potassium fluorotitanate, such as hydrofluoric acid and nitric acid, which will affect the purity and application performance of the product.

[0005] ② The economic effect is poor. The by-products produced during the purification process are not effectively recovered and utilized, resulting in waste of resources and environmental pollution. Summary of the invention

[0006] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a purification device for potassium fluorotitanate.

[0007] Another object of the present invention is to provide a purification process for potassium fluorotitanate.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A purification device for potassium fluorotitanate (K2TiF6), comprising a preliminary cleaning device, a recrystallization device and an acid treatment device; the preliminary cleaning device comprises a preliminary cleaning tank and a first filter, the material inlet of the preliminary cleaning tank is connected to a K2TiF6 storage tank through a pipeline, the material outlet of the preliminary cleaning tank is connected to the first filter through a pipeline, the liquid phase outlet of the first filter is connected to the acid treatment device, and the solid phase outlet of the first filter is connected to the recrystallization device; the recrystallization device comprises a stirring heater, a second filter, a cooling crystallization tank and a third filter connected in sequence, the stirring heater is connected to the solid phase outlet of the first filter; the acid treatment device comprises an acid storage tank, a neutralization tank, a fourth filter and a distillation tower connected in sequence, and the acid storage tank is connected to the liquid phase outlet of the first filter.

[0010] Furthermore, the preliminary cleaning tank has an agitator and a pH meter inside, which are used to mix potassium fluorotitanate and the solvent to ensure that the materials are fully mixed, and add NaOH to adjust the pH.

[0011] Furthermore, a material conveying pump is provided between the K2TiF6 storage tank and the preliminary cleaning tank, and between the preliminary cleaning tank and the first filter.

[0012] The first filter is used for filtering and preliminarily separating potassium fluorotitanate and residual acid.

[0013] The stirring heater of the recrystallization equipment is used to stir and heat to dissolve the crude potassium fluorotitanate product in water, and then filter the dissolved solution while hot through the second filter to remove undissolved impurities, and then cool the filtrate to below 10° C. in a cooling crystallization tank to promote the precipitation of potassium fluorotitanate crystals, and rinse with ice water, and finally filter again through the third filter, and obtain the potassium fluorotitanate fine product after drying.

[0014] Furthermore, a material conveying pump is provided between the stirring heater and the second filter and between the second filter and the cooling crystallization tank.

[0015] Furthermore, the neutralization tank of the acid treatment equipment has an agitator and a pH meter inside, which is used to react the waste acid (hydrofluoric acid and nitric acid) in the preliminary cleaning process with sodium hydroxide (NaOH) to neutralize the acid solution, and then pass it into the fourth filter to filter the sodium fluoride (NaF) produced after neutralization, and then put the remaining filtrate into a distillation tower, distill the filtrate, recover the solvent, and the remaining precipitate is sodium nitrate (NaNO3).

[0016] Furthermore, a material delivery pump is provided between the acid storage tank and the neutralization tank, and between the neutralization tank and the fourth filter.

[0017] The connection diagram of the potassium fluorotitanate purification equipment and the connection diagram of the acid treatment equipment of the present invention are respectively as follows: Figure 1 and Figure 2 shown.

[0018] A purification process for potassium fluorotitanate comprises the following steps:

[0019] (1) Preliminary cleaning:

[0020] Potassium fluorotitanate is added to a preliminary cleaning tank containing a solvent and mixed thoroughly, a small amount of NaOH is added to adjust the pH to a weak acidity, filtered by a first filter, and then the solid phase is repeatedly washed with an appropriate amount of solvent to obtain a crude potassium fluorotitanate product;

[0021] (2) Recrystallization:

[0022] At 60-100° C., the crude potassium fluorotitanate product is dissolved in an appropriate amount of water in a stirring heater, filtered through a second filter while hot, and then the filtrate is cooled to below 10° C. in a cooling crystallization tank to precipitate a large amount of potassium fluorotitanate crystals, which are rinsed with a small amount of cold water (water below 10° C.), filtered through a third filter, and dried to obtain a refined potassium fluorotitanate product;

[0023] (3) Acid treatment:

[0024] The filtrate produced by the first filter in step (1) is collected in an acid storage tank and then pumped into a neutralization tank for neutralization with NaOH to adjust the pH to neutral. At this time, a large amount of precipitate is precipitated, which is NaF. The filtrate is filtered by a fourth filter and the solid phase is dried to obtain a NaF product. The filtrate is distilled in a distillation tower to recover the solvent, and the remaining precipitate is NaNO3.

[0025] The purification process flow chart of potassium fluorotitanate of the present invention is as follows Figure 3 shown.

[0026] Furthermore, the potassium fluorotitanate in step (1) is derived from the potassium fluorotitanate precipitate recovered after a precipitation reaction between hydrofluoric acid-nitric acid type titanium metal pickling waste liquid and potassium salt.

[0027] Furthermore, the solvent in step (1) is ethanol.

[0028] Furthermore, in step (1), adjusting the pH to a weak acid state refers to adjusting the pH to 4 to 6.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The working principle of the present invention is based on chemical reaction and physical separation process. In the preliminary cleaning stage, potassium fluorotitanate and residual acid are initially separated by using a suitable solvent and adjusting pH and filtering; in the recrystallization stage, high-purity potassium fluorotitanate crystals are obtained by controlling temperature and filtering according to the principle of dissolution and cooling crystallization; in the acid treatment stage, the solvent is recovered and the by-products sodium fluoride (NaF) and sodium nitrate (NaNO3) are separated and recovered by neutralization and distillation, taking advantage of the difference in the solubility properties of fluoride salts and nitrates in the solvent. The process and equipment of the present invention can achieve the following effects:

[0031] ① Removing residual acid can significantly improve the purity of the product, thereby improving its performance in the production of titanic acid, metallic titanium and alloys.

[0032] ② The acid treatment step in the purification process can effectively recover and treat harmful substances such as hydrofluoric acid and nitric acid, reduce pollution to the environment, and meet the requirements of sustainable development.

[0033] ③Through the purification process, not only can the value of the product be improved, but also valuable by-products such as sodium fluoride (NaF) and sodium nitrate (NaNO3) can be recovered in the acid treatment step, thereby improving the economic effect of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a connection diagram of the purification equipment of potassium fluorotitanate of the present invention;

[0035] Figure 2 It is a connection diagram of the acid treatment equipment of the present invention;

[0036] Figure 3 The figure is a flow chart of the purification process of potassium fluorotitanate of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0038] Example 1

[0039] like Figures 1-2 As shown, a potassium fluorotitanate purification device includes a preliminary cleaning device, a recrystallization device and an acid treatment device.

[0040] The preliminary cleaning equipment includes a preliminary cleaning tank and a first filter, the material inlet of the preliminary cleaning tank is connected to the K2TiF6 storage tank through a pipeline, the material outlet of the preliminary cleaning tank is connected to the first filter through a pipeline, the liquid phase outlet of the first filter is connected to the acid treatment equipment, and the solid phase outlet of the first filter is connected to the recrystallization equipment. There is an agitator and a pH meter inside the preliminary cleaning tank. It is used to mix potassium fluorotitanate with the solvent to ensure that the materials are fully mixed, and NaOH is added to adjust the pH. A material delivery pump is provided between the K2TiF6 storage tank and the preliminary cleaning tank, and between the preliminary cleaning tank and the first filter. The first filter is used to filter and preliminarily separate potassium fluorotitanate and residual acid.

[0041] The recrystallization equipment includes a stirring heater, a second filter, a cooling crystallization tank and a third filter connected in sequence, and the stirring heater is connected to the solid phase outlet of the first filter. The stirring heater of the recrystallization equipment is used to stir and heat to dissolve the crude potassium fluorotitanate product in water, and then filter the dissolved solution while hot through the second filter to remove undissolved impurities, and then cool the filtrate to below 10°C in the cooling crystallization tank to promote the precipitation of potassium fluorotitanate crystals, and rinse with 4°C cold water, and finally filter again through the third filter, dry, and obtain a potassium fluorotitanate fine product. A material delivery pump is provided between the stirring heater and the second filter and between the second filter and the cooling crystallization tank.

[0042] The acid treatment equipment comprises an acid storage tank, a neutralization tank, a fourth filter and a distillation tower connected in sequence, and the acid storage tank is connected to the liquid phase outlet of the first filter. The neutralization tank of the acid treatment equipment has an agitator and a pH meter inside. It is used to react the waste acid (hydrofluoric acid and nitric acid) in the preliminary cleaning process with sodium hydroxide (NaOH) to neutralize the acid solution, and then pass through the fourth filter, filter the sodium fluoride (NaF) produced after neutralization to obtain the NaF product after drying, and then put the remaining filtrate into the distillation tower, distill the filtrate, recover the solvent, and the remaining precipitation is sodium nitrate (NaNO3). Material delivery pumps are provided between the acid storage tank and the neutralization tank and between the neutralization tank and the fourth filter.

[0043] like Figure 3 As shown, the process flow of purifying potassium fluorotitanate using the above purification equipment is as follows:

[0044] (1) Preliminary cleaning:

[0045] The potassium fluorotitanate precipitate recovered from the precipitation reaction of hydrofluoric acid-nitric acid type titanium metal pickling waste liquid and potassium salt is added to a preliminary cleaning tank containing solvent ethanol and mixed thoroughly, a small amount of NaOH is added, the pH is adjusted to weak acidity (pH = 4 to 6), and the potassium fluorotitanate and residual acid are preliminarily separated by filtering through a first filter, and then the solid phase is repeatedly washed with an appropriate amount of solvent to obtain a crude potassium fluorotitanate product.

[0046] (2) Recrystallization:

[0047] At 60-100°C, the crude potassium fluorotitanate product is dissolved in an appropriate amount of water in a stirring heater, filtered through a second filter while hot, and then the filtrate is cooled to below 10°C in a cooling crystallization tank to precipitate a large amount of potassium fluorotitanate crystals, which are rinsed with 4°C cold water, filtered through a third filter, and dried to obtain a refined potassium fluorotitanate product.

[0048] (3) Acid treatment:

[0049] The filtrate produced by the first filter in step (1) is collected in an acid storage tank, and then pumped into a neutralization tank to neutralize the waste acid (hydrofluoric acid and nitric acid) produced in the preliminary cleaning process with NaOH, and the pH is adjusted to neutral. At this time, a large amount of precipitate is precipitated, which is NaF; the fourth filter is used to filter and separate the NaF produced after neutralization, and the NaF product is obtained after drying; the remaining filtrate enters a distillation tower for distillation, the solvent is recovered, and the remaining precipitate is sodium nitrate (NaNO3).

[0050] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A purification device for potassium fluorotitanate, characterized in that: It includes preliminary cleaning equipment, recrystallization equipment and acid treatment equipment; the preliminary cleaning equipment includes a preliminary cleaning tank and a first filter, the material inlet of the preliminary cleaning tank is connected to the K2TiF6 storage tank through a pipeline, the material outlet of the preliminary cleaning tank is connected to the first filter through a pipeline, the liquid phase outlet of the first filter is connected to the acid treatment equipment, and the solid phase outlet of the first filter is connected to the recrystallization equipment; the recrystallization equipment includes a stirring heater, a second filter, a cooling crystallization tank and a third filter connected in sequence, and the stirring heater is connected to the solid phase outlet of the first filter; the acid treatment equipment includes an acid storage tank, a neutralization tank, a fourth filter and a distillation tower connected in sequence, and the acid storage tank is connected to the liquid phase outlet of the first filter.

2. A potassium fluorotitanate purification device according to claim 1, characterized in that: The preliminary cleaning tank has an agitator and a pH meter inside.

3. A potassium fluorotitanate purification device according to claim 1, characterized in that: A material conveying pump is provided between the K2TiF6 storage tank and the preliminary cleaning tank, and between the preliminary cleaning tank and the first filter.

4. A potassium fluorotitanate purification device according to claim 1, characterized in that: A material conveying pump is provided between the stirring heater and the second filter and between the second filter and the cooling crystallization tank.

5. A potassium fluorotitanate purification device according to claim 1, characterized in that: The neutralization tank of the acid treatment equipment is provided with an agitator and a pH meter.

6. A potassium fluorotitanate purification device according to claim 1, characterized in that: A material conveying pump is provided between the acid storage tank and the neutralization tank, and between the neutralization tank and the fourth filter.

7. A purification process for potassium fluorotitanate, characterized in that: The steps include: (1) Preliminary cleaning: Potassium fluorotitanate is added to a preliminary cleaning tank containing a solvent and mixed thoroughly, a small amount of NaOH is added to adjust the pH to a weak acidity, filtered by a first filter, and then the solid phase is repeatedly washed with an appropriate amount of solvent to obtain a crude potassium fluorotitanate product; (2) Recrystallization: At 60-100°C, the crude potassium fluorotitanate product is dissolved in an appropriate amount of water in a stirring heater, filtered through a second filter while hot, and then the filtrate is cooled to below 10°C in a cooling crystallization tank to precipitate a large amount of potassium fluorotitanate crystals, which are rinsed with a small amount of cold water, filtered through a third filter, and dried to obtain a refined potassium fluorotitanate product; (3) Acid treatment: The filtrate produced by the first filter in step (1) is collected in an acid storage tank and then pumped into a neutralization tank for neutralization with NaOH to adjust the pH to neutral. At this time, a large amount of precipitate is precipitated, which is NaF. The filtrate is filtered by a fourth filter and the solid phase is dried to obtain a NaF product. The filtrate is distilled in a distillation tower to recover the solvent, and the remaining precipitate is NaNO3.

8. A purification process for potassium fluorotitanate according to claim 7, characterized in that: The potassium fluorotitanate described in step (1) is derived from the potassium fluorotitanate precipitate recovered after a precipitation reaction between hydrofluoric acid-nitric acid type titanium metal pickling waste liquid and potassium salt.

9. A purification process for potassium fluorotitanate according to claim 7, characterized in that: The solvent in step (1) is ethanol.

10. A purification process for potassium fluorotitanate according to claim 7, characterized in that: Adjusting the pH to a weakly acidic state in step (1) refers to adjusting the pH to 4-6.

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