A method for quickly determining the conversion rate of titanium dioxide products produced by the sulfuric acid process

Abstract

The present invention provides a method for rapidly determining the conversion rate of titanium dioxide products produced by a sulfuric acid process, which comprises at least the following steps: S1. taking a sample of the titanium dioxide product produced by a sulfuric acid process, adding a universal indicator, and causing the sample to develop color; S2. substituting the color development result shown in step S1 into a corresponding relationship table between the color development and conversion rate of titanium dioxide products produced by a sulfuric acid process as shown in Table 1, and determining the conversion rate of the sample of the product produced by a sulfuric acid process; compared with the prior art, the present invention adopts an indicator method to rapidly and accurately detect the conversion rate of the product produced by a sulfuric acid process, and can promptly and quickly understand the qualified status of the conversion rate of the product produced by a sulfuric acid process. Production personnel can understand the conversion rate index at the first time, make judgments on the production process conditions, and take corresponding countermeasures, and can promptly and effectively adjust the process control, thereby improving the calcination quality of the product produced by a sulfuric acid process, and at the same time being conducive to energy saving and consumption reduction.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium dioxide detection, and particularly relates to a method for rapidly determining the conversion rate of titanium dioxide products produced by a sulfuric acid process. Background Art

[0002] TiO2 exists in three crystalline forms in nature: rutile, anatase, and brookite. Rutile TiO2 is widely used due to its superior properties such as higher refractive index and dielectric constant and lower thermal conductivity. In the process of producing rutile titanium dioxide by the sulfuric acid method, the acquisition of high-quality rutile titanium dioxide products is closely related to its rutile conversion rate (hereinafter referred to as "conversion rate"). A high conversion rate of kiln products can not only improve the oil phase whiteness and tinting power of the kiln products, reduce oil absorption, but also obtain particles with excellent pigment properties. In the existing technology, the determination of the conversion rate of kiln products is generally carried out using an X-ray diffraction spectrometer. The X-ray diffraction spectrometer (XRD) is based on the intensity ratio method, that is, the maximum diffraction peak intensity of rutile and anatase is measured by an X-ray diffractometer, and the diffraction peak intensity of the anatase is converted into the anatase content relative to the rutile content. The rutile content is determined by the difference. Although the test data is highly accurate, the instrument cost is high and the test takes a long time, which is not suitable for rapid testing in the production process. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for quickly determining the conversion rate of titanium dioxide produced by the sulfuric acid process in order to solve the shortcomings of the prior art.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] A method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process comprises at least the following steps:

[0006] S1. Take titanium dioxide kiln product samples, add a universal indicator, so that the kiln product samples color;

[0007] S2. Substitute the color development results shown in step S1 into the corresponding relationship table of titanium dioxide kiln color and conversion rate shown in Table 1 to determine the conversion rate of the kiln product sample;

[0008] Table 1 The corresponding relationship between the color development and conversion rate of titanium dioxide products

[0009]

[0010] Preferably, when there are multiple colors in the color development area, the conversion rate of the kiln product sample is determined by the color that occupies >50% of the area of ​​the color development area. If the area occupied by the multiple colors does not reach >50%, resampling is carried out for measurement. If the situation that the area occupied by the multiple colors does not reach >50% occurs for more than two consecutive times, the sample conversion rate is directly judged to be unqualified.

[0011] Preferably, the mass of the titanium dioxide sample falling from the kiln in step S1 is 5 to 7 g, and the amount of the universal indicator used is 0.5 to 1 mL.

[0012] Preferably, the universal indicator is prepared by adding water to thymol blue, methyl red, bromothymol blue, phenolphthalein, sodium hydroxide, neutral ethanol, and water.

[0013] Preferably, the neutral ethanol is prepared by adding 1% phenolphthalein indicator to ethanol and titrating with 0.1 mol / L NaOH solution until it turns light red.

[0014] Preferably, the universal indicator contains thymol blue at a concentration of 0.025 g / L, methyl red at a concentration of 0.065 g / L, bromothymol blue at a concentration of 0.400 g / L, phenolphthalein at a concentration of 0.25 g / L, and neutral ethanol at a content of 400 mL / L.

[0015] Preferably, the preparation method of the universal indicator is: weigh 0.0250g of thymol blue, 0.0650g of methyl red, 0.4000g of bromothymol blue, and 0.2500g of phenolphthalein, mix them in 400mL of neutral ethanol, dilute with water to 1000mL, and adjust the solution pH to 7 with 0.1mol / LNaOH.

[0016] Preferably, the mass percentage of zinc in the zinc salt-treated product from the kiln in step S1 is 0.15-0.35% in terms of zinc oxide.

[0017] Preferably, the mass percentage of aluminum in the product from the aluminum salt treatment in step S1 is 0.15-0.35% in terms of alumina.

[0018] Preferably, in step S1, the titanium dioxide product falling from the kiln is added with the universal indicator at room temperature, and the color development result is observed immediately after color development.

[0019] Compared with the existing technology, the present invention adopts the indicator method to quickly and accurately detect the conversion rate of the kiln products, and can quickly and timely understand the qualified status of the conversion rate of the kiln products. The production personnel can understand the conversion rate index at the first time, make judgments on the production process conditions, and take corresponding response measures. They can adjust the process control quickly and effectively in time, improve the calcination quality of the kiln products, and at the same time are conducive to energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figures 1 to 9 This is a typical color diagram of zinc salt kiln products;

[0021] Figures 10-17 This is a typical color diagram of aluminum salt kiln products. DETAILED DESCRIPTION

[0022] A method for rapidly determining the conversion rate of titanium dioxide produced by a sulfuric acid process comprises the following steps:

[0023] S1. Take a sample of titanium dioxide from the kiln and add a universal indicator to make the sample color;

[0024] S2. Substitute the color development results shown in step S1 into the corresponding relationship table of titanium dioxide kiln color and conversion rate shown in Table 1 to determine the conversion rate of the kiln product sample;

[0025] Table 1 The corresponding relationship between the color development and conversion rate of titanium dioxide products

[0026]

[0027] In the prior art, the conversion rate of kiln products is generally detected by X-ray diffraction spectrometer, which is time-consuming and not suitable for rapid detection during the production process.

[0028] Salt treatment is an essential step in the production of titanium dioxide powder using the sulfuric acid method. Salt treatment is a step in which a small amount of chemical additives are added to titanic acid for modification before calcination. This step can give the product good hue, gloss, suitable particle size, dispersibility and other properties. In the prior art, the main salt treatment additives used in salt treatment are zinc salt treatment agents and aluminum salt treatment agents. The production requirement for titanium dioxide powder (i.e., titanium dioxide products discharged from the kiln) after zinc salt treatment and calcination is a pH of 6.0-9.0, and the production requirement for aluminum salt treatment products is a pH of 8.0-10.0.

[0029] Through experiments and production research, the applicant has discovered that the pH values ​​of titanium dioxide products from different conversion rates and different types of titanium dioxide products are well correlated. Using a universal indicator can effectively enhance the color of titanium dioxide products from the kiln. The higher the conversion rate and the higher the pH, the more bluish the color becomes. The color change relationship of the universal indicator at different pH values ​​is shown in Table 2.

[0030] Table 2

[0031] pH 4 5 6 7 8 9 10 color red orange yellow green green blue purple

[0032] Zinc salt-treated products are treated with a universal indicator, which displays red, orange, yellow, green, cyan, or blue. Verification based on a large number of samples shows that red or orange indicates a conversion rate of less than 90%, yellow indicates a conversion rate of 90% or higher and less than 95%, and green or cyan indicates a conversion rate of 95% or higher. Due to overburning during production, a small amount of zinc salt-treated products may appear blue, indicating a conversion rate of 99% or higher. Aluminum salt-treated products are also treated with a universal indicator, which displays red, orange, yellow, green, cyan, or blue. Red or orange indicates a conversion rate of less than 80%, yellow indicates a conversion rate of 80% or higher and less than 90%, green or cyan indicates a conversion rate of 90% or higher and less than 98%, and blue indicates a conversion rate of 98% or higher.

[0033] Since the kiln products may have uneven conversion rates, multiple colors may coexist after adding the universal indicator, not just one color. When there are multiple colors in the color display area, the conversion rate of the kiln products is determined based on the main color displayed, that is, the conversion rate of the kiln products is determined based on the color that occupies more than 50% of the color display area. If the area occupied by the multiple colors does not reach more than 50%, resampling is required for measurement. If the situation of the multiple colors occupying less than 50% of the area occurs for more than two consecutive times, it indicates that the conversion rate of the sample is very uneven and the subsequent production process cannot be carried out. The sample conversion rate is directly judged as unqualified and the sample is reprocessed.

[0034] When determining the specific color of the color, you can use the seven-color standard color card.

[0035] Therefore, the applicant selected titanium dioxide products with different base materials and different conversion rate gradients and analyzed them to obtain the "Correspondence Table of Color and Conversion Rate of Titanium Dioxide Products" shown in Table 1. When the conversion rate of titanium dioxide products needs to be tested later, simply add a universal indicator to develop color and compare the color development results with Table 1 to quickly determine the conversion rate of the titanium dioxide products. Since the color of the universal indicator corresponds to the pH value, the corresponding pH of the product can also be determined. Furthermore, it has been verified that the results of rapid determination of the conversion rate of the products using the universal indicator are basically consistent with the XRD test results, indicating that the method for determining the conversion rate of titanium dioxide products produced by the sulfuric acid process is not only convenient but also reliable, and can be used as a method for rapid determination of the conversion rate of titanium dioxide products produced by the sulfuric acid process in production.

[0036] Preferably, in step S1, the mass of the titanium dioxide sample falling from the kiln is 5 to 7 g, and the amount of the universal indicator used is 3 to 5 drops, about 0.5 to 1 mL.

[0037] Preferably, the universal indicator is prepared by adding water to thymol blue, methyl red, bromothymol blue, phenolphthalein, sodium hydroxide, neutral ethanol, and water.

[0038] Preferably, the preparation method of neutral ethanol is: add 1% phenolphthalein indicator to ethanol, and titrate with 0.1 mol / L NaOH solution until it turns light red.

[0039] Preferably, the concentration of thymol blue in the universal indicator is 0.025 g / L, the concentration of methyl red is 0.065 g / L, the concentration of bromothymol blue is 0.400 g / L, the concentration of phenolphthalein is 0.25 g / L, and the content of neutral ethanol is 400 mL / L.

[0040] Further preferably, the preparation method of the universal indicator is: weigh 0.0250 g of thymol blue, 0.0650 g of methyl red, 0.4000 g of bromothymol blue, and 0.2500 g of phenolphthalein, mix them in 400 mL of neutral ethanol, dilute with water to 1000 mL, and adjust the solution to pH = 7 with 0.1 mol / L NaOH.

[0041] Preferably, in step S1, the mass percentage of zinc in the product treated with zinc salt is 0.15-0.35% in terms of zinc oxide; the mass percentage of aluminum in the product treated with aluminum salt is 0.15-0.35% in terms of aluminum oxide.

[0042] Preferably, in step S1, a universal indicator is added to the titanium dioxide product at room temperature, and the color development result is immediately observed. When measuring the sample, if the sample is taken from the calcining kiln head, the sample should be allowed to cool to room temperature before measurement. If the sample contains large particles, the sample can be ground in a mortar until the particles are uniform.

[0043] Example 1

[0044] Take titanium dioxide products with different base materials and different conversion rate gradients and measure their conversion rates using the following method:

[0045] 1) Take the zinc salt treatment and aluminum salt treatment products from the kiln respectively and set them aside;

[0046] 2) Take 6g of the kiln product sample and place it in a container. Add 4 drops of universal indicator to make the product develop color. Determine the conversion rate of the kiln product sample based on the corresponding relationship between the color development and conversion rate of the kiln products with different treatments in Table 1.

[0047] The conversion rates of all samples in Example 1 were titrated according to the above method. At the same time, the conversion rates of the above samples were measured using an X-ray diffraction spectrometer. The measured conversion rates and the titrated conversion rates are listed in Tables 3 and 4 below. Figures 1 to 16 . Figures 1 to 9 Here are 9 typical color photos of zinc salt kiln products. Figures 10-17The following are photos of eight typical aluminum salt drop kiln products. X-ray diffraction (XRD) spectrometer uses the intensity ratio method, which measures the maximum diffraction peak intensities of rutile and anatase using an X-ray diffractometer. The anatase diffraction peak intensity is then converted to the anatase content relative to the rutile content. The rutile content is determined by the difference.

[0048] From Table 3, Table 4 and Figures 1 to 17 The results show that the results of quickly determining the conversion rate of kiln products using the universal indicator provided in this application are basically consistent with the XRD test results, with an accuracy rate of more than 95%. This shows that the method of this application for determining the conversion rate of kiln products is not only convenient, but also reliable, and can be used as a method for quickly determining the conversion rate of sulfuric acid process titanium dioxide kiln products for testing in production.

[0049] Table 3 Comparison of zinc salt base material indicator titration and XRD test results

[0050]

[0051] Table 4 Comparison of aluminum salt base material indicator titration and XRD test results

[0052]

[0053] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such changes and modifications as fall within the scope of the claims and their equivalents.

Claims

1. A method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process, characterized in that: At least the following steps are included: S1. Select different base materials, different conversion rate gradients of titanium dioxide kiln products, add a universal indicator, so that the titanium dioxide kiln products color, analysis is shown in Table 1 "Titanium dioxide kiln products color and conversion rate correspondence table"; S2. Take titanium dioxide kiln product samples, add a universal indicator, so that the kiln product samples color; S3. Substitute the color development results shown in step S2 into the corresponding relationship table of titanium dioxide kiln color and conversion rate shown in Table 1 to determine the conversion rate of the kiln product sample; Table 1 The corresponding relationship between the color development and conversion rate of titanium dioxide products When there are multiple colors in the color development area, the conversion rate of the kiln product sample is determined by the color that occupies more than 50% of the area of ​​the color development area. If the area occupied by the multiple colors does not reach more than 50%, re-sampling is carried out for measurement. If the situation that the area occupied by the multiple colors does not reach more than 50% occurs twice in a row, the sample conversion rate is directly judged as unqualified.

2. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 1, wherein: The mass of the titanium dioxide sample falling from the kiln in step S1 is 5 to 7 g, and the amount of the universal indicator used is 0.5 to 1 mL.

3. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 1, wherein: The universal indicator is prepared by adding thymol blue, methyl red, bromothymol blue, phenolphthalein, sodium hydroxide, neutral ethanol and water.

4. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 3, wherein: The preparation method of the neutral ethanol is as follows: 1% phenolphthalein indicator is added to ethanol, and the mixture is titrated with 0.1 mol / L NaOH solution until the mixture turns light red.

5. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 3, wherein: The universal indicator contains thymol blue at a concentration of 0.025 g / L, methyl red at a concentration of 0.065 g / L, bromothymol blue at a concentration of 0.400 g / L, phenolphthalein at a concentration of 0.25 g / L, and neutral ethanol at a content of 400 mL / L.

6. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 5, characterized in that: The universal indicator is prepared as follows: 0.0250 g of thymol blue, 0.0650 g of methyl red, 0.4000 g of bromothymol blue, and 0.2500 g of phenolphthalein are weighed, mixed in 400 mL of neutral ethanol, diluted with water to 1000 mL, and the pH of the solution is adjusted to 7 with 0.1 mol / L NaOH.

7. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 1, characterized in that: The zinc content of the product treated with zinc salt in step S1 is 0.15-0.35% by weight, calculated as zinc oxide.

8. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 1, wherein: The aluminum mass percentage of the product treated with aluminum salt in step S1 is 0.15-0.35% in terms of alumina.

9. The method for rapidly determining the conversion rate of titanium dioxide produced by the sulfuric acid process as claimed in claim 1, wherein: In step S1, the titanium dioxide product falling from the kiln is added with the universal indicator at room temperature, and the color development result is observed immediately after color development.

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