A method for treating crystallization mother liquor with the remaining acid from the acid decomposition of scheelite

Abstract

The present invention belongs to the technical field of tungsten smelting, and particularly relates to a method for treating a crystallization mother liquor by utilizing residual acid from the acid decomposition of scheelite. The method comprises the following steps: introducing the crystallization mother liquor generated by preparing APT into an acid reactor in which the scheelite has been acid-decomposed for a process time; treating the crystallization mother liquor by utilizing the residual acid from the acid decomposition of the scheelite; and treating the crystallization mother liquor by utilizing the residual acid from the acid decomposition of the scheelite. The generated fine tungstic acid is wrapped and mixed with the crude tungstic acid generated by the acid decomposition of the scheelite. The generated fine tungstic acid is not easy to penetrate a filter cloth during plate and frame filtration, and does not clog filter cloth pores. The acid concentration of the filtrate after filtration is less than 10 wt%, and the tungsten content is less than 0.9 g / L. The present invention also has almost no effect on the filtration effect of the feed liquid in the acid reactor, and the filtration time is substantially the same as the filtration time without the addition of the crystallization mother liquor.

Description

Technical Field

[0001] The present invention belongs to the technical field of tungsten smelting, and specifically relates to a method for treating crystallization mother liquor with the residual acid from the acid decomposition of scheelite. Background Art

[0002] Scheelite has a relatively high calcium content, generally exceeding 20 wt%, and it is very easy to "reverse calcium" in the alkaline process, resulting in a high tungsten loss and waste of tungsten resources. As Figure 1 shown, most of the current scheelite is decomposed by the acid process to form tungstic acid first, and then alkali dissolution - ion exchange - crystallization to produce APT - tungsten oxide. However, there are two problems in producing tungstic acid by this method. One is the problem of how to treat the residual acid (acid concentration higher than 20 wt%), and the other is the problem of cooling and filtering after the decomposition of scheelite is completed (generally, natural cooling with the lid open easily causes acid mist overflow, which is not environmentally permitted). When preparing APT in tungsten smelting, a certain amount of crystallization mother liquor will inevitably be generated (generally 1.2 m 3 of crystallization mother liquor per ton of APT), and the tungsten concentration is 20 - 30 g / L. Generally, the method for treating such crystallization mother liquor is to first add liquid alkali for cooking to remove ammonia nitrogen, and then add hydrochloric acid to form tungstic acid. However, there are three problems with the tungstic acid prepared by this method. One is that the tungstic acid particles are extremely fine and easily pass through and block the filter holes, resulting in slow filtration and a certain amount of tungsten loss. The second is that the preparation of such tungstic acid requires the consumption of acid, increasing the cost. The last one is that the problem of residual acid treatment is faced again. Summary of the Invention

[0003] To solve the problems existing in the prior art, the main object of the present invention is to propose a method for treating crystallization mother liquor with the residual acid from the acid decomposition of scheelite.

[0004] To solve the above technical problems, according to one aspect of the present invention, the following technical solutions are provided:

[0005] A method for treating crystallization mother liquor with the residual acid from the acid decomposition of scheelite, comprising the following steps:

[0006] S1. The scheelite is acid - decomposed in an acid reaction kettle for the process duration;

[0007] S2. The crystallization mother liquor generated during the preparation of APT is quickly introduced into the acid reaction kettle;

[0008] S3. The acid reaction kettle is sealed, stirring is started, and after stirring, filtration is carried out to complete the treatment of the crystallization mother liquor.

[0009] As a preferred embodiment of the method for treating crystallization mother liquor with the residual acid from the acid decomposition of scheelite according to the present invention, wherein: in the step S1, hydrochloric acid with a concentration of 32 wt% is added during acid decomposition.

[0010] As a preferred embodiment of the method for treating crystallization mother liquor by utilizing residual acid from acid decomposition of scheelite according to the present invention, in step S1, the acid decomposition process lasts for 2 to 2.5 hours.

[0011] As a preferred embodiment of the method for treating crystallization mother liquor using residual acid from acid decomposition of scheelite according to the present invention, in step S2, the volume ratio of the crystallization mother liquor produced by preparing APT to the acid added during the acid decomposition in step S1 is 1:1.

[0012] As a preferred embodiment of the method for treating crystallization mother liquor by using acid decomposition of residual acid from scheelite according to the present invention, the stirring time in step S3 is 10 to 60 minutes.

[0013] As a preferred embodiment of the method for treating crystallization mother liquor by utilizing residual acid from scheelite decomposition with acid, in the step S3, the stirring frequency is 50 Hz.

[0014] As a preferred embodiment of the method for treating crystallization mother liquor by using residual acid from acid decomposition of scheelite according to the present invention, in step S3, the acid concentration of the filtrate after filtration is less than 10 wt%.

[0015] As a preferred embodiment of the method for treating crystallization mother liquor by using residual acid from scheelite decomposition with acid, in the step S3, the tungsten content of the filtrate after filtration is less than 0.9 g / L.

[0016] The beneficial effects of the present invention are as follows:

[0017] The present invention provides a method for treating a crystallization mother liquor by utilizing residual acid from the acid decomposition of scheelite. The method comprises the following steps: introducing the crystallization mother liquor generated by preparing APT into an acid reactor in which the acid decomposition of scheelite has reached the process time; utilizing the residual acid from the acid decomposition of scheelite to treat the crystallization mother liquor; and utilizing the residual acid from the acid decomposition of scheelite to treat the crystallization mother liquor. The generated fine tungstic acid is coated and mixed with the crude tungstic acid generated by the acid decomposition of scheelite. The fine tungstic acid is not easy to penetrate the filter cloth during plate and frame filtration and will not clog the filter cloth pores. The acid concentration of the filtrate after filtration is less than 10 wt%, and the tungsten content is less than 0.9 g / L. The present invention also has little effect on the filtration effect of the feed liquid in the acid reactor, and the filtration time is substantially the same as that without the addition of the crystallization mother liquor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0019] Figure 1This is a schematic diagram of the existing scheelite production process flow.

[0020] Figure 2 The figure is a flow chart of the method for treating crystallization mother liquor by using residual acid from scheelite decomposition with acid. DETAILED DESCRIPTION

[0021] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] The present invention proposes a method for treating crystallization mother liquor by using residual acid from scheelite decomposition, which has the following advantages:

[0023] (1) The residual acid concentration of the scheelite acid decomposition of the present invention is reduced from more than 20wt% to less than 10wt% after the crystallization mother liquor is consumed, which largely solves the problem of residual acid treatment;

[0024] (2) The temperature of the feed liquid in the acid decomposition kettle of the scheelite of the present invention slowly decreases as the crystallization mother liquor is added. When the addition of the crystallization mother liquor is completed, the feed liquid temperature is between 60 and 70°C, which meets the filtration temperature allowed by the filter cloth. The reaction is sealed throughout the process without acid mist overflow, which meets environmental protection requirements.

[0025] (3) The present invention utilizes the residual acid from the acid decomposition of scheelite to treat the crystallization mother liquor to generate fine tungstic acid, which is wrapped and mixed with the crude tungstic acid generated from the acid decomposition of scheelite. It is not easy to penetrate the filter cloth during plate and frame filtration and will not clog the filter cloth pores. The acid concentration of the filtrate after filtration is less than 10wt%, and the tungsten content is less than 0.9g / L. Moreover, the present invention has almost no effect on the filtration effect of the feed liquid in the acid reactor, and the filtration time is basically the same as the filtration time without adding the crystallization mother liquor.

[0026] (4) The present invention only consumes the residual acid from the acid decomposition of scheelite, and does not require the consumption of new acid solution, thereby reducing production costs.

[0027] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0028] like Figure 1 As shown, a method for treating crystallization mother liquor by using acid decomposition of residual acid from scheelite comprises the following steps:

[0029] S1, the time it takes for the scheelite to undergo acid decomposition in the acid reactor;

[0030] S2, quickly introducing the crystallization mother liquor produced by the preparation of APT into the acid reactor;

[0031] S3. Seal the acid reaction kettle, start stirring, and filter after stirring to process the crystallization mother liquor.

[0032] Preferably, in step S1, hydrochloric acid with a concentration of 32 wt% is added during acid decomposition.

[0033] Preferably, in step S1, the duration of the acid decomposition process is 2 - 2.5 h.

[0034] Preferably, in step S2, the volume ratio of the crystallization mother liquor generated during the preparation of APT to the acid added during acid decomposition in step S1 is 1:1.

[0035] Preferably, in step S3, the stirring time is 10 - 60 min.

[0036] Preferably, in step S3, the stirring frequency is 50 Hz.

[0037] Preferably, in step S3, the acid concentration of the filtrate after filtration < 10 wt%, and the tungsten content of the filtrate after filtration < 0.9 g / L.

[0038] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0039] Example 1

[0040] A method for treating crystallization mother liquor with the remaining acid from scheelite acid decomposition includes the following steps:

[0041] S1. Take 1.8 t of scheelite (WO3 content is 56.4 wt%, water content is 7.5 wt%) and perform acid decomposition in an acid reaction kettle until the process duration is reached; 4 m of hydrochloric acid with a concentration of 32 wt% is added during acid decomposition 3 ;

[0042] S2. Add the crystallization mother liquor generated during the preparation of APT at the maximum flow rate (valve fully open), and finish adding it in 8.5 min; 3

[0043] S3. Seal the acid reaction kettle, start stirring, the stirring time is 10 min, the stirring frequency is 50 Hz, the temperature of the liquid in the acid reaction kettle after stirring is 68.6 °C, and then filter, and finish filtering in 30 min to process the crystallization mother liquor.

[0044] In this example, the acid concentration of the filtrate after filtration is 8.9 wt%, and the tungsten content of the filtrate after filtration is 0.89 g / L.

[0045] Example 2

[0046] A method for treating crystallization mother liquor with the remaining acid from scheelite acid decomposition includes the following steps:

[0047] ​S1. Take 1.8 t of scheelite (WO3 content is 56.4 wt%, water content is 7.5 wt%) and perform acid decomposition in an acid reaction kettle until the process duration is reached; when performing acid decomposition, add 4 m of hydrochloric acid with a concentration of 32 wt% 3 ;

[0048] S2. Add the crystallization mother liquor produced in the preparation of APT at half the flow rate (valve half open), and finish adding it in 17 min; 3

[0049] S3. Seal the acid reaction kettle, start stirring, the stirring time is 10 min, the stirring frequency is 50 Hz, after stirring, the temperature of the liquid in the acid reaction kettle is 66.7 °C, and then filter, and finish filtering in 29.5 min to achieve the treatment of the crystallization mother liquor.

[0050] In this example, the acid concentration of the filtrate after filtration is 9.0 wt%, and the tungsten content of the filtrate after filtration is 0.87 g / L.

[0051] Example 3

[0052] A method for treating crystallization mother liquor by using the residual acid from acid decomposition of scheelite includes the following steps:

[0053] S1. Take 1.8 t of scheelite (WO3 content is 55.4 wt%, water content is 7.4 wt%) and perform acid decomposition in an acid reaction kettle until the process duration is reached; when performing acid decomposition, add 4 m of hydrochloric acid with a concentration of 32 wt% 3 ;

[0054] S2. Add the crystallization mother liquor produced in the preparation of APT at the maximum flow rate (valve fully open), and finish adding it in 8.5 min; 3

[0055] S3. Seal the acid reaction kettle, start stirring, the stirring time is 10 min, the stirring frequency is 50 Hz, after stirring, the temperature of the liquid in the acid reaction kettle is 68.5 °C, and then filter, and finish filtering in 29.5 min to achieve the treatment of the crystallization mother liquor.

[0056] In this example, the acid concentration of the filtrate after filtration is 9.3 wt%, and the tungsten content of the filtrate after filtration is 0.81 g / L.

[0057] Example 4

[0058] A method for treating crystallization mother liquor by using the residual acid from acid decomposition of scheelite includes the following steps:

[0059] S1. Take 1.8 t of scheelite (WO3 content is 60.1 wt%, water content is 6.9 wt%) and perform acid decomposition in an acid reaction kettle until the process duration is reached; when performing acid decomposition, add 4 m of hydrochloric acid with a concentration of 32 wt% 3 ; ​​

[0060] S2. Add 4 m³ of the crystallization mother liquor generated from the preparation of APT at the maximum flow rate (valve fully open) and finish adding it in 8.5 minutes; 3

[0061] S3. Seal the acid reaction kettle, start stirring, with the stirring time being 10 minutes and the stirring frequency being 50 Hz. After stirring, the temperature of the liquid in the acid reaction kettle is 68.8 °C. Then filter and finish filtering in 30 minutes to achieve the treatment of the crystallization mother liquor.

[0062] In this example, the acid concentration of the filtrate after filtration is 8.1 wt%, and the tungsten content of the filtrate after filtration is 0.89 g / L.

[0063] Comparative Example 1

[0064] The difference from Example 1 is that in step S3, the stirring time is 7.5 minutes.

[0065] After stirring in this comparative example, the temperature of the liquid in the acid reaction kettle is 69.3 °C. Finish filtering in 30 minutes. The acid concentration of the filtrate after filtration is 9.1 wt%, and the tungsten content of the filtrate after filtration is 1.02 g / L.

[0066] Comparative Example 2

[0067] The difference from Example 1 is that in step S3, the stirring frequency is 25 Hz.

[0068] After stirring in this comparative example, the temperature of the liquid in the acid reaction kettle is 68.9 °C. Finish filtering in 31 minutes. The acid concentration of the filtrate after filtration is 9.2 wt%, and the tungsten content of the filtrate after filtration is 1.01 g / L.

[0069] Comparative Example 3

[0070] The difference from Example 1 is that in step S2, 6 m³ of the crystallization mother liquor generated from the preparation of APT is added. 3

[0071] After stirring in this comparative example, the temperature of the liquid in the acid reaction kettle is 68.5 °C. Finish filtering in 33.5 minutes. The acid concentration of the filtrate after filtration is 7.2 wt%, and the tungsten content of the filtrate after filtration is 1.23 g / L.

[0072] Comparative Example 4

[0073] The difference from Example 1 is that in step S1, 4 m³ of hydrochloric acid with a concentration of 32 wt% is added to an empty acid reaction kettle. 3 .

[0074] Finish filtering in 48 minutes in this comparative example. The acid concentration of the filtrate after filtration is 24.9 wt%, and the tungsten content of the filtrate after filtration is 1.51 g / L. ​​

[0075] Comparative Example 5

[0076] The difference from Example 1 is that step S1 is to add 2m hydrochloric acid with a concentration of 32wt% to the empty acid reactor. 3 .

[0077] In this comparative example, the filtration was completed in 55 minutes. The acid concentration of the filtrate after filtration was 15.6 wt %, and the tungsten content of the filtrate after filtration was 1.54 g / L.

[0078] As can be seen from the above examples and comparative examples, the present invention introduces the crystallization mother liquor produced by preparing APT into an acid reactor where the acid decomposition of scheelite has reached the process time, and uses the residual acid from the acid decomposition of scheelite to treat the crystallization mother liquor. The resulting fine tungstic acid is coated and mixed with the crude tungstic acid produced by the acid decomposition of scheelite, and is not easy to penetrate the filter cloth during plate and frame filtration and does not clog the filter cloth pores. The acid concentration of the filtrate after filtration is less than 10wt%, and the tungsten content is less than 0.9g / L. In addition, the present invention has almost no effect on the filtration effect of the feed liquid in the acid reactor, and the filtration time is basically the same as the filtration time without the addition of the crystallization mother liquor.

[0079] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for treating crystallization mother liquor with the residual acid from acid decomposition of scheelite, characterized in that, The steps include: S1, the acid decomposition process time of scheelite in the acid reactor is 2~2.5h; S2. Rapidly introduce the crystallization mother liquor produced by the preparation of APT into the acid reactor; the volume ratio of the crystallization mother liquor produced by the preparation of APT to the acid added during the acid decomposition in step S1 is 1:1; the temperature of the feed liquid in the scheelite acid reactor slowly decreases as the crystallization mother liquor is added. When the crystallization mother liquor is added, the feed liquid temperature is 60-70° C., which meets the filter cloth's allowable filtration temperature. The reaction is sealed throughout the entire process without acid mist overflow, meeting environmental protection requirements; S3. The acid reactor is sealed, stirring is started, and the mixture is filtered after stirring to achieve treatment of the crystallization mother liquor. The crystallization mother liquor is treated with the residual acid from the acid decomposition of the scheelite. The generated fine tungstic acid is wrapped and mixed with the crude tungstic acid generated from the acid decomposition of the scheelite. It is not easy to penetrate the filter cloth during plate and frame filtration and will not clog the filter cloth pores. The filtration time is consistent with the filtration time without adding the crystallization mother liquor. The acid concentration of the filtrate after filtration is less than 10wt%, and the tungsten content of the filtrate after filtration is less than 0.9g / L.

2. The method for treating crystallization mother liquor with the residual acid from acid decomposition of scheelite according to claim 1, wherein In the step S1, hydrochloric acid with a concentration of 32 wt % is added during acid decomposition.

3. The method for treating the crystallization mother liquor with the residual acid from the acid decomposition of scheelite according to claim 1, wherein, In step S3, the stirring time is 10 to 60 minutes.

4. The method for treating the crystallization mother liquor by using the residual acid from the acid decomposition of scheelite according to claim 1, characterized in that, In step S3, the stirring frequency is 50 Hz.

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