A purification process and equipment for potassium fluorotitanate

Abstract

The present invention belongs to the technical field of titanium alloy processing raw materials, and discloses a purification process and equipment for potassium fluorotitanate. The purification equipment includes preliminary cleaning, recrystallization 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; the acid treatment equipment includes an acid storage tank, a neutralization tank, a fourth filter and a distillation tower connected in sequence. The purification process and equipment of the present invention can remove residual acid, improve the purity of the product, and can effectively recover and treat harmful substances, reduce pollution to the environment and improve the economic benefits of the enterprise.

Description

Technical Field

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

[0002] During titanium processing, pickling is a common treatment method for removing titanium oxide layers. A mixed acid of HF and HNO3 is generally used as the titanium pickling solution. However, during the pickling process, titanium ions continuously dissolve into the titanium pickling solution. After the titanium pickling solution has been used to a certain extent, a large amount of titanium ions accumulate in the solution, causing the solution viscosity to increase and the solution's ability to corrode and remove the titanium oxide layer to deteriorate. When the mass concentration of titanium ions in the solution reaches 50 g / L, the pickling solution's ability to remove the titanium oxide layer on the titanium metal surface decreases sharply, the titanium metal surface quality deteriorates, and the solution reaches its solubility limit and becomes scrapped. The scrapped pickling solution contains a large amount of acid and titanium ions. Adding potassium salt to separate and recover the Ti ions in the form of potassium fluorotitanate precipitate is an environmentally friendly and efficient method for titanium recovery and pickling solution regeneration. 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. Further purification of the recovered potassium fluorotitanate product is a technical problem that needs to be solved by those skilled in the art.

[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, and wash the crystals with ice water to remove the attached mother liquor and impurities, and then dry them. However, the simple recrystallization method still has the following shortcomings and deficiencies:

[0004] ① Insufficient treatment of residual acid: The simple recrystallization method may not be able to effectively remove the residual acid 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 via a pipeline, the material outlet of the preliminary cleaning tank is connected to the first filter via 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 is provided with an agitator and a pH meter for mixing potassium fluorotitanate and the solvent to ensure that the materials are fully mixed, and adding 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 the 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 delivery 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 is equipped with an agitator and a pH meter. It is used to react the waste acid (hydrofluoric acid and nitric acid) from the initial cleaning process with sodium hydroxide (NaOH) to neutralize the acid solution. The acid solution is then passed through a fourth filter to filter out the sodium fluoride (NaF) produced after neutralization. The remaining filtrate is then placed in a distillation tower for distillation, solvent recovery, 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 acidic state, filtered 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;

[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 then 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, NaF, is precipitated. The filtrate is filtered using a fourth filter and the solid phase is dried to obtain the NaF product. The filtrate is distilled into 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 acidic state refers to adjusting the pH to 4-6.

[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 initial cleaning stage, potassium fluorotitanate and residual acid are initially separated by using a suitable solvent, adjusting the pH and filtering. In the recrystallization stage, high-purity potassium fluorotitanate crystals are obtained by controlling the temperature and filtering according to the principle of dissolution and cooling crystallization. In the acid treatment stage, the solvent is recovered and the byproducts 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] ③ Through the purification process, not only can the value of the product be increased, 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 benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0035] Figure 2 This 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 will be further described in detail below with reference to 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, and 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 product of potassium fluorotitanate 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 pure product of potassium fluorotitanate. 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, wherein 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. The acid treatment equipment is used to react the spent acid (hydrofluoric acid and nitric acid) in the preliminary cleaning process with sodium hydroxide (NaOH) to neutralize the acid solution, which is then passed through the fourth filter. The sodium fluoride (NaF) produced after filtration and neutralization is dried to obtain a NaF product. The remaining filtrate is then placed in a distillation tower, the filtrate is distilled, the solvent is recovered, and the remaining precipitation is sodium nitrate (NaNO3). A material delivery pump is 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 for 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 with potassium salt is added to a preliminary cleaning tank containing solvent ethanol and fully mixed. A small amount of NaOH is added to adjust the pH to weak acidity (pH = 4 to 6). The potassium fluorotitanate and residual acid are preliminarily separated by filtration 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 then rinsed with 4°C cold water, filtered through a third filter, and dried to obtain the 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, NaF, is precipitated; the NaF produced after neutralization is filtered and separated by a fourth filter, and the NaF product is obtained after drying; the remaining filtrate is distilled in a distillation tower to recover the solvent, and the remaining precipitate is sodium nitrate (NaNO3).

[0050] The above embodiments are preferred implementations of the present invention, but the implementations 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 considered as equivalent replacement methods and are included in the scope of protection 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 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 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 is provided with an agitator and a pH meter.

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 delivery pump is provided between the stirring heater and the second filter and between the second filter and the cooling crystallization tank.

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

7. A process for purifying potassium fluorotitanate using the potassium fluorotitanate purification equipment according to claim 1, characterized in that: The steps include: (1) Preliminary cleaning: Potassium fluorotitanate is added to a preliminary washing tank containing ethanol and mixed thoroughly, a small amount of NaOH is added to adjust the pH to weak acidity, filtered through a first filter, and then the solid phase is repeatedly washed with an appropriate amount of ethanol 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 then 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, NaF, is precipitated. The filtrate is filtered using a fourth filter and the solid phase is dried to obtain the NaF product. The filtrate is distilled into a distillation tower to recover the solvent, and the remaining precipitate is NaNO3.

8. A process for purifying potassium fluorotitanate according to claim 7, characterized in that: 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.

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

Images