A method for desilication in an acidic system

Abstract

The present invention provides a method for desilication in an acidic system. The method includes: (1) mixing a silicate solution and an acidic solution to be desilicated, and reacting to obtain a post-reaction solution; (2) sequentially cooling and performing solid-liquid separation on the post-reaction solution to obtain a desilicated acidic solution. The method can deeply remove silicon in the acidic solution, and the silicon content in the desilicated acidic solution is less than 100 ppm; the method has simple operation, low cost, does not generate harmful substances during the treatment process, is green and environmentally friendly, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic chemical production, and more particularly to the technical field of purifying silicon impurities in an acidic system, and more particularly to a method for desiliconizing an acidic system. Background Art

[0002] In the production processes of inorganic chemicals such as wet-process crude phosphoric acid, titanium dioxide, and zirconium oxychloride, there are certain requirements for the impurity content of the products, especially for the content of silicon element. Since the phosphate rock used in wet-process crude phosphoric acid has a relatively low grade, the initially prepared crude phosphoric acid contains a certain amount of silicon and other impurities, so it must be purified and refined before entering subsequent industrial-grade or food-grade phosphate products. The silicon element in titanium dioxide will have a certain impact on the conversion rate of rutile and reduce the product quality. The presence of impurity silicon in zirconium oxychloride will reduce the purity of the product, thereby limiting the application range of the product.

[0003] CN104003438B discloses a method for desiliconizing a zirconium oxychloride acidolysis solution. The method uses the silicon-containing crude zirconium solution after acidolysis of the transformation material in the production of zirconium oxide by the alkali fusion method as the raw material, and a polyacrylamide-based flocculant is compounded with polyethylene glycol and added to the acidolysis zirconium solution for flocculation to achieve deep desiliconization of silicic acid in the acidolysis zirconium solution.

[0004] CN103739010B discloses a method for deep desiliconization in an acid system using silica sol, including: 1) reacting an aqueous solution of soluble silicate with an acid to obtain silica sol; 2) adding the silica sol to the acidic silicon-containing liquid to be treated for reaction to obtain a liquid to be flocculated; 3) adding a flocculant to the liquid to be flocculated for flocculation, and then performing solid-liquid separation to obtain a desiliconized solution. This method uses soluble silicate as the raw material, prepares a solution with a certain concentration, adjusts the pH with an acid, and cures to prepare silica sol. This method can achieve deep desiliconization of silicon in the acidity system, and the silicon content can be reduced to less than 0.001%.

[0005] In the implementation processes of the above methods, organic amine reagents are all used, a certain flocculation process is required, and the wastewater generated later needs to be harmlessly treated. At the same time, the operation process is relatively cumbersome.

[0006] Therefore, it is necessary to develop a method for removing silicon in an acidic liquid that is efficient, economical, produces less waste after treatment, and has little impact on the environment. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for desilication in an acidic system, especially a method for deep desilication in an acidic system. By adding a silicate solution to the acidic system solution to be desilicated for reaction, silicon in the acidic solution can be deeply removed. The silicon content in the desilicated solution is less than 100 ppm. The method is simple to operate, low in cost, and does not produce any harmful substances during the treatment process, which is a green and environmentally friendly treatment method.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for desilication in an acidic system, and the method includes:

[0010] (1) Mix a silicate solution and an acidic solution to be desilicated, react to obtain a reacted solution;

[0011] (2) The reacted solution is successively cooled and subjected to solid-liquid separation to obtain a desilicated acidic solution.

[0012] In the present invention, the silicate solution and the solution to be desilicated are mixed. Through the chemical reaction between the silicate and hydrogen ions therein, reactive silicic acid is generated, and the silicic acid plays the role of a seed crystal here, inducing the precipitation of impurity silicon in the liquid phase, and then achieving the purpose of desilication. The desilication method in the present invention only induces precipitation, is simple to operate, produces waste liquid, and has low cost, and is suitable for large-scale industrial production processes.

[0013] Preferably, the source of the silicate solution in step (1) includes: mixing silicate and water, dissolving to obtain a silicate solution.

[0014] In the present invention, the silicate is dissolved by itself. The silicate has high activity. Combining the two steps of dissolution and induced precipitation ensures the combination of highly active silicate ions and hydrogen ions to form silicic acid, thereby inducing the precipitation of impurity silicon. There is no need to add organic amine reagents and there is no flocculation process, realizing a green desilication process.

[0015] Preferably, the silicate in the silicate solution in step (1) includes sodium silicate and / or potassium silicate.

[0016] Preferably, the mass content of the silicate solution in terms of H2SiO3 is 1-35 wt%, for example, it can be 1 wt%, 2 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt% or 35 wt%, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0017] Preferably, the silicon concentration in the acid solution to be desilicated in step (1) is 0.5 - 5 g / L. For example, it can be 0.5 g / L, 1 g / L, 1.5 g / L, 3 g / L, 5 g / L, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0018] Preferably, the acid in the acid solution to be desilicated in step (1) includes any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid. Among them, typical but non - restrictive combinations are combinations of sulfuric acid and hydrochloric acid, hydrochloric acid and hydrochloric acid, sulfuric acid and hydrochloric acid, sulfuric acid and phosphoric acid, nitric acid and phosphoric acid, sulfuric acid and nitric acid.

[0019] Preferably, the concentration of the acid in the acid solution to be desilicated in step (1) is 1 - 5 mol / L. For example, it can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0020] Preferably, the volume ratio of the silicate solution to the acid solution to be desilicated in step (1) is 0.01 - 1.5:1. For example, it can be 0.01:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.5:1, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0021] The present invention preferably has the volume ratio of the silicate solution to the acid solution to be desilicated within the above range, which has a better silicon removal effect.

[0022] Preferably, the temperature of the reaction in step (1) is 20°C - 200°C. For example, it can be 20°C, 40°C, 60°C, 80°C, 100°C, 150°C, 200°C, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0023] The reaction of the present invention preferably occurs within a specific range (60 - 200°C), which has a better silicon impurity removal effect.

[0024] Preferably, the reaction time is 0.1 - 20 h. For example, it can be 10 min, 30 min, 60 min, 120 min, 180 min, 240 min, 720 min, 900 min, 1200 min, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0025] The present invention has no special limitation on the cooling method, and any cooling method well-known to those skilled in the art can be used, such as air cooling and / or natural cooling, etc.

[0026] Preferably, the cooling method in step (2) includes any one or a combination of at least two of natural cooling, air cooling or water cooling. Typical but non-limiting combinations are the combination of natural cooling and air cooling, the combination of water cooling and air cooling, and the combination of natural cooling and water cooling.

[0027] Preferably, the cooling time in step (2) is 0.1 - 20 h. For example, it can be 10 min, 30 min, 60 min, 120 min, 180 min, 240 min, 720 min, 900 min or 1200 min, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0028] As a preferred technical solution of the present invention, the method includes the following steps:

[0029] (1) Mix silicate and water, dissolve to obtain a silicate solution with a mass content of 1 - 35 wt% calculated as H2SiO3; mix the silicate solution and the acid solution to be desilicated with a silicon concentration of 0.5 - 5 g / L at a volume ratio of 0.01 - 1:1, and react at 20°C - 200°C for 0.1 - 20 h to obtain a reaction solution;

[0030] (2) Cool the reaction solution for 0.1 - 20 h to room temperature and then perform solid-liquid separation to obtain a desilicated acid solution.

[0031] The present invention has no special limitation on the solid-liquid separation in the above process. Any device and method for solid-liquid separation well-known to those skilled in the art can be used, and it can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, etc., or a combination of different methods.

[0032] The room temperature referred to in the present invention means the temperature without heating or cooling. Depending on the weather and geographical environment, the temperature range is about -10 - 40°C, generally about 25°C.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] (1) The acid system desilication method provided by the present invention can achieve the effect of deep desilication. Under relatively good conditions, the silicon content in the desilicated acid solution is ≤100 ppm;

[0035] (2) In the acid system desilication method provided by the present invention, there is no need to add organic amine reagents, and there is no flocculation process, which is a green and environment-friendly desilication method;

[0036] (3) The method for desilication in an acidic system provided by the present invention is simple to operate, low in cost, and no harmful substances will be generated during the treatment process. Description of the Drawings

[0037] Figure 1 It is a flow chart of the method for desilication in an acidic system provided in Embodiment 1 of the present invention. Detailed Embodiments

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

[0039] The present invention will be further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0040] As a specific embodiment of the present invention, a method for desilication in an acidic system is provided. The method includes the following steps:

[0041] (1) Mix silicate and water, dissolve to obtain a silicate solution with a mass content of 1-35 wt% calculated as H2SiO3; mix the silicate solution and the acidic solution to be desilicated with a silicon concentration of 0.5-5 g / L at a volume ratio of 0.01-1:1, and react at 20°C-200°C for 0.1-20 h to obtain a reacted solution;

[0042] (2) The reacted solution is successively cooled for 0.1-20 h to room temperature and subjected to solid-liquid separation to obtain a desilicated acidic solution.

[0043] The following will be described in detail with specific examples, but the following examples are not regarded as limiting the present invention.

[0044] Example 1

[0045] This example provides a method for desilication in an acidic system. As Figure 1 shown, the method includes the following steps:

[0046] (1) Mix solid sodium silicate and water, dissolve to obtain a sodium silicate solution with a mass content of 5 wt% calculated as H2SiO3; mix the sodium silicate solution and the acidic solution to be desilicated with a silicon concentration of 2 g / L (sulfuric acid solution with a concentration of 2 mol / L) at a volume ratio of 0.5:1, and react at 80°C for 5 h to obtain a reacted solution;

[0047] (2) The reacted solution is successively cooled for 5 h to room temperature and filtered to obtain a desilicated acidic solution.

[0048] Example 2

[0049] This embodiment provides a method for desilication in an acidic system. The method comprises the following steps:

[0050] (1) Mix potassium silicate solid and water, dissolve to obtain a potassium silicate solution with a mass content of 15 wt% in terms of H2SiO3; mix the potassium silicate solution and an acidic solution to be desilicated with a silicon concentration of 1 g / L (a hydrochloric acid solution with a concentration of 2 mol / L) at a volume ratio of 0.05:1, and react at 150 °C for 10 h to obtain a post-reaction solution;

[0051] (2) Cool the post-reaction solution for 2 h to room temperature and then filter it to obtain a desilicated acidic solution.

[0052] Example 3

[0053] This embodiment provides a method for desilication in an acidic system. The method comprises the following steps:

[0054] (1) Mix potassium silicate solid and water, dissolve to obtain a potassium silicate solution with a mass content of 35 wt% in terms of H2SiO3; mix the potassium silicate solution and an acidic solution to be desilicated with a silicon concentration of 0.5 g / L (a nitric acid solution with a concentration of 3 mol / L) at a volume ratio of 0.01:1, and react at 200 °C for 20 h to obtain a post-reaction solution;

[0055] (2) Cool the post-reaction solution for 20 h to room temperature and then filter it to obtain a desilicated acidic solution.

[0056] Example 4

[0057] This embodiment provides a method for desilication in an acidic system. The difference between this method and that of Example 1 is only that: the reaction temperature is 40 °C.

[0058] Example 5

[0059] This embodiment provides a method for desilication in an acidic system. The difference between this method and that of Example 1 is only that: mix the sodium silicate solution and the acidic solution to be desilicated at a volume ratio of 0.005:1.

[0060] Example 6

[0061] This embodiment provides a method for desilication in an acidic system. The difference between this method and that of Example 1 is only that: mix the sodium silicate solution and the acidic solution to be desilicated at a volume ratio of 1.5:1.

[0062] Example 7

[0063] This embodiment provides a method for desilication in an acidic system. The difference between this method and that of Example 1 is only that: mix the sodium silicate solution and the acidic solution to be desilicated at a volume ratio of 2:1.

[0064] Example 8

[0065] This embodiment provides a method for desilication in an acidic system. The difference between this method and that of Embodiment 1 is only that: sodium silicate solid and water are mixed, dissolved, and used after standing for 5 h.

[0066] Comparative Example 1

[0067] This comparative example provides a method for desilication in an acidic system, and the method is carried out according to Example 1 in CN103739010B.

[0068] The method provided in this comparative example desilicates by flocculation. It is necessary to add polyacrylamide flocculants and reagents such as polyethylene glycol, and the wastewater generated later needs to be harmlessly treated, and the process is complex.

[0069] Comparative Example 2

[0070] This comparative example provides a method for desilication in an acidic system, and the method is carried out according to Example 1 in CN104003438B.

[0071] Although the method provided in this comparative example adds silicate to prepare silica sol, it is necessary to add a flocculant for flocculation to desilicate by flocculation, and the wastewater generated later needs to be harmlessly treated, and the process is complex.

[0072] Comparative Example 3

[0073] This comparative example provides a method for desilication in an acidic system. The difference between this method and that of Embodiment 1 is only that: in step (1), the sodium silicate solution is replaced by silicic acid.

[0074] Testing method: The inductively coupled plasma emission spectrometer method is used to detect the silicon content in the acidic solution after desilication.

[0075] The results of the above embodiments are shown in Table 1.

[0076] Table 1

[0077] Silicon content in the acidic solution after desilication (ppm) Example 1 50 Example 2 100 Example 3 80 Example 4 90 Example 5 200 Example 6 20 Example 7 20 Example 8 60 Comparative Example 3 400

[0078] It can be seen from Table 1 as follows:

[0079] (1) From Embodiments 1 to 3, it can be seen that for the method for desilication in an acidic system provided by the present invention, even without using the flocculation method, the silicon can be desilicated to below 200 ppm, and can reach below 100 ppm under better conditions;

[0080] (2) It can be seen from the comprehensive implementation of Example 1 and Examples 5 to 7 that when the volume ratio of the sodium silicate solution to the acid solution to be desilicated is controlled within a specific range, the increase in the silicate content reduces the potential energy of silicic acid precipitation, which is more conducive to ensuring that the silicon content in the acid solution after desilication is reduced to a specific value. However, in Example 7, due to the large amount of sodium silicate solution added, problems such as system inhomogeneity are likely to occur;

[0081] (3) It can be seen from the comprehensive implementation of Example 1 and Example 4 that the reaction temperature in Example 1 is 80°C. Compared with Example 4 where the temperature is 40°C, the silicon content in the acid solution after desilication in Example 1 is only 50 ppm, while the silicon content in the acid solution after desilication in Example 4 is as high as 90 ppm. This shows that by preferably controlling the reaction temperature within a specific range, the present invention can further reduce the silicon content in the acid solution without flocculation;

[0082] (4) It can be seen from the comprehensive implementation of Example 1 and Comparative Example 3 that in Example 1, sodium silicate solution is added to form silicic acid. Compared with directly adding silicic acid in Comparative Example 3, the silicon content in the acid solution after desilication in Example 1 is only 50 ppm, while the silicon content in the acid solution after desilication in Comparative Example 3 is as high as 400 ppm. This shows that by choosing to add sodium silicate, the present invention has a better desilication effect.

[0083] In summary, the method for desilicating an acidic system provided by the present invention does not require the addition of a flocculant and an organic amine reagent, and can achieve the desilication of silicon to below 200 ppm, and can reach below 100 ppm under better conditions, realizing green and environmental protection desilication in the acidic system.

[0084] The present invention uses the above-mentioned examples to illustrate the detailed structural features of the present invention. However, the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for desilication in an acidic system, characterized in that, The method includes: (1) Mixing a silicate solution and an acid solution to be desilicated, reacting to obtain a reacted solution; (2) Sequentially cooling and performing solid-liquid separation on the reacted solution to obtain a desilicated acid solution; In step (1), the source of the silicate solution includes: mixing silicate and water, dissolving to obtain a silicate solution; the volume ratio of the silicate solution to the acid solution to be desilicated in step (1) is 0.01 - 1.5:1; the mass content of the silicate solution calculated as H2SiO3 is 1 - 35 wt%.

2. The method according to claim 1, wherein In step (1), the silicate in the silicate solution includes sodium silicate and / or potassium silicate.

3. The method according to claim 1, wherein In step (1), the silicon concentration in the acid solution to be desilicated is 0.5 - 5 g / L.

4. The method according to claim 1, wherein In step (1), the acid in the acid solution to be desilicated includes any one or a combination of at least two of sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid.

5. The method according to claim 1, wherein In step (1), the temperature of the reaction is 20°C - 200°C.

6. The method according to claim 1, characterized in that The reaction time is 0.1 - 20 h.

7. The method according to claim 1, characterized in that, In step (2), the cooling method includes any one or a combination of at least two of natural cooling, air cooling, or water cooling.

8. The method according to claim 1, characterized in that, In step (2), the cooling time is 0.1 - 20 h.

9. The method according to claim 1, characterized in that, The method includes the following steps: (1) Mixing silicate and water, dissolving to obtain a silicate solution with a mass content calculated as H2SiO3 of 1 - 35 wt%; mixing the silicate solution and an acid solution to be desilicated with a silicon concentration of 0.5 - 5 g / L at a volume ratio of 0.01 - 1:1, reacting at 20°C - 200°C for 0.1 - 20 h to obtain a reacted solution; (2) Sequentially cooling the reacted solution for 0.1 - 20 h to room temperature and performing solid-liquid separation to obtain a desilicated acid solution.

Images