Method for testing the content of alumina in ilmenite sand

Abstract

A kind of method for testing the content of alumina in ilmenite sand, comprising the following steps in sequence: (1) adding sodium hydroxide, ilmenite sand sample into nickel crucible, cooling after sample fusion; (2) adding distilled water to leach the fused block, then adding ethanol to obtain leaching solution; then diluting the leaching solution with water, filtering to obtain filtrate; (3) transferring the filtrate into a triangular flask, then adding EDTA solution, adding potassium sodium tartrate solution, shaking uniformly; boiling, cooling; (4) adding hexamethylenetetramine solution into the triangular flask, then adding dimethyl phenol orange indicator; adding 1+1 hydrochloric acid solution, adjusting to yellow solution, excess 2-3 drops; adding zinc acetate standard solution, until the solution is purple red, not reading; (5) adding sodium fluoride, boiling after cooling; adjusting according to the color of solution, then titrating with zinc acetate standard solution. The present application can accurately measure the content of alumina in ilmenite sand, and the operation is relatively simple, fast, and the test cost is relatively low.

Description

Technical Field

[0001] This invention relates to the field of mineral analysis technology, specifically to a method for testing the alumina content in ilmenite sand. Background Technology

[0002] The titanium slag used in the chloride process for producing titanium dioxide requires a high titanium dioxide content and the lowest possible levels of impurities such as calcium, magnesium, and aluminum. To meet the production requirements for raw materials, ilmenite needs further impurity removal. Through physical and chemical processes, titanium dioxide and iron in the ilmenite are melted and separated, resulting in a high-titanium dioxide concentrate, which is then used in the chloride process for titanium dioxide production.

[0003] The main components of ilmenite are TiO2, FeO, and Fe2O3, with impurities including SiO2, CaO, MgO, Al2O3, and V2O5. To obtain high-quality titanium slag, ilmenite needs to be smelted under high-temperature, strongly reducing conditions to allow the iron oxides to fully react with carbon, forming titanium slag and metallic iron in a molten state. The process involves mixing ilmenite with a solid reducing agent such as coking coal (or petroleum coke, anthracite), and then adding it to an electric furnace for reduction smelting. When smelting titanium slag in an electric furnace, the slag should be kept as low in viscosity as possible. One factor affecting the viscosity of titanium slag is the Al2O3 content. As the Al2O3 content increases, the slag's fluidity significantly deteriorates, and power consumption increases substantially, providing conditions for raising the slag's melting point and the formation of low-valence titanium compounds with high melting points and high viscosity. Low viscosity of titanium slag is of great practical significance for reducing energy consumption and improving operation; therefore, controlling the Al2O3 content in ilmenite is one of the key focuses in ilmenite screening. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for testing the alumina content in ilmenite sand. This method can accurately measure the alumina content in ilmenite sand, and is relatively simple, fast, and low in cost. The technical solution adopted is as follows:

[0005] A method for testing the alumina content in ilmenite sand, characterized by comprising the following steps in sequence:

[0006] (1) Add 5 grams of sodium hydroxide to the nickel crucible, then weigh 0.48-0.52 grams (usually accurate to 0.1 mg) of ilmenite sand sample and add it to the nickel crucible, and cover it; then put the nickel crucible into a high-temperature furnace and keep it at 770-790℃ for 10-12 minutes, and then take the nickel crucible out of the high-temperature furnace to cool it;

[0007] (2) Place the nickel crucible and the material inside it into a beaker, add distilled water to the beaker to leach the molten metal in the nickel crucible, then add 2 ml of ethanol to obtain the leachate; then transfer the leachate to a 100 ml volumetric flask, dilute it with water to the 100 ml mark and shake well; then filter the material in the volumetric flask with medium-speed qualitative filter paper to obtain the filtrate.

[0008] (3) Transfer 10 ml of the filtrate obtained in step (2) into an Erlenmeyer flask, then add 10 ml of EDTA solution to the Erlenmeyer flask, and then add 10 ml of potassium sodium tartrate solution to the Erlenmeyer flask and shake well; then place the Erlenmeyer flask on an electric stove and boil for 3-5 minutes, cool it and add water to 100 ml (that is, add water until the liquid level in the Erlenmeyer flask is at the 100 ml mark).

[0009] (4) Add 10 ml of hexamethylenetetramine solution to the Erlenmeyer flask, and then add 5 drops of xylenol orange indicator to the Erlenmeyer flask. At this time, the solution in the Erlenmeyer flask will be purple-red. Then, adjust the solution in the Erlenmeyer flask to be yellow with 1+1 hydrochloric acid solution. After the solution in the Erlenmeyer flask is yellow, add 2-3 drops in excess (2-3 drops in excess will make the solution acidic). Then add zinc acetate standard solution to the Erlenmeyer flask until the solution in the Erlenmeyer flask is purple-red. Do not record the reading.

[0010] (5) Add 3 grams of sodium fluoride to the Erlenmeyer flask, boil for 3 minutes and then cool. Based on the color of the solution, choose one of the following methods for subsequent operations:

[0011] (a) If the solution in the Erlenmeyer flask is yellow, first adjust the solution in the Erlenmeyer flask to purple-red with 1+1 ammonia solution; then adjust the solution in the Erlenmeyer flask to yellow with 1+1 hydrochloric acid solution, and add 2-3 drops in excess; finally titrate with zinc acetate standard solution until the solution in the Erlenmeyer flask turns purple-red as the endpoint, and record the reading.

[0012] (b) If the solution in the Erlenmeyer flask is purple-red, adjust it to yellow with 1+1 hydrochloric acid solution, adding 2-3 drops in excess; finally, titrate with zinc acetate standard solution until the solution in the Erlenmeyer flask is purple-red, and record the reading.

[0013] In step (1) above, the capacity of the nickel crucible is 30-50 ml.

[0014] In step (1), after sodium hydroxide is added to the nickel crucible, it needs to be heated on an electric furnace to remove moisture before adding the ilmenite sand sample to the nickel crucible.

[0015] In step (2) above, distilled water is used to dissolve the molten metal. Hotter distilled water is usually added for better dissolution; if the water is not hot enough, the beaker needs to be heated. The volume of distilled water added in step (2) is usually no more than 80 ml.

[0016] In step (2) above, a beaker with a capacity of 250ml can be used.

[0017] Preferably, the concentration of the potassium sodium tartrate solution used in step (3) above is 20%wt.

[0018] Preferably, the concentration of the hexamethylenetetramine solution used in step (4) above is 20% wt.

[0019] In step (5) above, the 1+1 ammonia solution is prepared by mixing commercially available concentrated ammonia (concentration of 25%) and water in a volume ratio of 1:1.

[0020] In steps (4) and (5) above, the 1+1 hydrochloric acid solution is prepared by mixing concentrated hydrochloric acid (concentration of 37%) and water in a volume ratio of 1:1.

[0021] In this invention, due to the high titanium dioxide content in the ilmenite sand sample, the advantage of using the alkaline fusion method is that after water leaching and dilution, the sodium hydroxide concentration of the leaching solution is maintained between 1.0-1.3 mol / L, which precipitates and filters out a large amount of titanium, zirconium, iron, and other elements, reducing their impact on aluminum titration. If the alkalinity is too high, some iron, zirconium, titanium, and other elements may enter the filtrate; while if the alkalinity is too low, some aluminum may be adsorbed. The leaching solution usually contains green high-valence manganese; adding ethanol can reduce the high-valence manganese in the leaching solution, generating manganese dioxide precipitate which is then separated.

[0022] Currently, most methods for determining alumina in titanium ore involve dissolving the alumina in a corundum crucible and sodium peroxide, followed by EDTA complexometric titration. This method results in significant wear and tear on the corundum crucible, and when dissolving the ore with sodium peroxide, solid lumps adhere to the inner wall of the crucible, making them difficult to remove. To reduce sample loss and ensure rapid and accurate analysis results, a nickel crucible is used as the sample processing vessel in step (1) above, along with sodium hydroxide as the solvent. Furthermore, under pH conditions of 5-6, iron, titanium, manganese, lead, etc., can form complexes with EDTA, interfering with the determination of alumina. Therefore, this invention uses NaOH to melt the sample, which can remove the interference from iron and titanium. Dissolving with sodium hydroxide followed by direct filtration is simple and rapid.

[0023] In step (3) above, adding sodium potassium tartrate serves two purposes: firstly, it can mask elements such as titanium and iron in the sample; secondly, the presence of sodium tartrate can accelerate the reaction of Al. 3+--The complexation reaction of EDTA, when tartrate ions are present in the solution, can prevent the formation of aluminum hydroxide precipitate and inhibit the formation of aluminum hydroxyl compounds, thus promoting complete complexation between aluminum and EDTA. Potassium sodium tartrate has complexing properties and can form soluble complexes with metal ions such as titanium, copper, iron, and lead. Incomplete titanium complexation can lead to a higher aluminum complexation level. Boiling for 3-5 minutes allows for quantitative complexation between aluminum and EDTA (the boiling process promotes the conversion of aluminum hydroxyl complexes to EDTA complexes), while titanium partially complexes with potassium sodium tartrate and partially with EDTA.

[0024] In step (4) above, the addition of hexamethylenetetrammonium solution can serve as a buffer solution to balance and control the pH range of 5-6 required for xylenol orange as an indicator; on the other hand, it can also separate elements such as calcium, magnesium and manganese, further reducing their influence on the titration of aluminum ions.

[0025] In step (5) above, zinc acetate displacement titration is used (this method is suitable for samples with high iron and low aluminum content). Interfering ions such as iron, titanium, and zirconium in the ilmenite sample are separated during sample decomposition. Potassium tartrate is then added to mask these ions, and sodium fluoride is used for displacement titration of the alumina alone. Ilmenite samples also contain phosphate and sulfate ions. If lead salt displacement titration is used, precipitation will occur, but this problem can be avoided by using zinc acetate.

[0026] In this invention, after aluminum ions form a complex with EDTA, excess EDTA and a fixed amount of aluminum ions are titrated with a standard zinc acetate solution. After reaching the equivalence point, in the presence of fluoride ions, the complex of aluminum ions and EDTA is selectively dissociated, releasing an equivalent amount of EDTA. This is then titrated with a standard zinc acetate solution to accurately determine the aluminum ion content.

[0027] The alumina content testing method of the present invention is more suitable for ilmenite sand with high iron and low aluminum content. Furthermore, the ilmenite sand sample processing is simple and fast, highly operable, and can reduce the amount of acid used, thereby reducing environmental pollution. Detailed Implementation

[0028] Example 1

[0029] In this embodiment, a commercially available ilmenite sand standard sample was tested, and the alumina (Al2O3) content of the commercially available ilmenite sand standard sample was 1.30%.

[0030] The method for testing the alumina content in ilmenite sand includes the following steps:

[0031] (1) Add 5 grams of sodium hydroxide to the nickel crucible, then weigh 0.5000 grams of ilmenite sand sample and add it to the nickel crucible, and cover it with a lid; then put the nickel crucible into a high-temperature furnace and keep it at 780°C for 10 minutes, and then take the nickel crucible out of the high-temperature furnace to cool it.

[0032] In this step (1), the capacity of the nickel crucible is 30 ml;

[0033] In this step (1), after sodium hydroxide is added to the nickel crucible, it needs to be heated on an electric furnace to remove moisture before adding the ilmenite sand sample to the nickel crucible.

[0034] (2) Place the nickel crucible and the material inside it into a beaker (the beaker has a capacity of 250 ml), add 60 ml of distilled water to the beaker to leach the molten metal in the nickel crucible, and then add 2 ml of ethanol to obtain the leachate; then transfer the leachate to a 100 ml volumetric flask, dilute it with water to the 100 ml mark and shake well; then filter the material in the volumetric flask with medium-speed qualitative filter paper to obtain the filtrate;

[0035] In step (2), add hot distilled water to better dissolve the melt; if the water is not hot, the beaker needs to be heated.

[0036] (3) Transfer 10 ml of the filtrate obtained in step (2) into an Erlenmeyer flask, then add 10 ml of EDTA solution to the Erlenmeyer flask, and then add 10 ml of potassium sodium tartrate solution (the concentration of potassium sodium tartrate solution is 20%wt) to the Erlenmeyer flask and shake well; then place the Erlenmeyer flask on an electric stove and boil for 3 minutes, cool it and add water to 100 ml (that is, add water until the liquid level in the Erlenmeyer flask is at the 100 ml mark).

[0037] (4) Add 10 ml of hexamethylenetetramine solution (concentration of hexamethylenetetramine solution is 20%wt) to the Erlenmeyer flask, and then add 5 drops of xylenol orange indicator to the Erlenmeyer flask. At this time, the solution in the Erlenmeyer flask is purple-red. Then adjust the solution in the Erlenmeyer flask to yellow with 1+1 hydrochloric acid solution. After the solution in the Erlenmeyer flask turns yellow, add 3 drops in excess. Then add zinc acetate standard solution to the Erlenmeyer flask until the solution in the Erlenmeyer flask turns purple-red. Do not record the reading.

[0038] (5) Add 3 grams of sodium fluoride to the Erlenmeyer flask, boil for 3 minutes and then cool. Based on the color of the solution, choose one of the following methods for subsequent operations:

[0039] (a) If the solution in the Erlenmeyer flask is yellow, first adjust it with 1+1 ammonia solution until the solution in the Erlenmeyer flask is purple-red; then adjust it with 1+1 hydrochloric acid solution until the solution in the Erlenmeyer flask is yellow, and add 3 drops in excess; finally titrate with zinc acetate standard solution until the solution in the Erlenmeyer flask is purple-red as the endpoint, and record the reading.

[0040] (b) If the solution in the Erlenmeyer flask is purple-red, adjust it to yellow with 1+1 hydrochloric acid solution, adding 3 drops in excess; finally, titrate with zinc acetate standard solution until the solution in the Erlenmeyer flask is purple-red, and record the reading.

[0041] In step (5) above, the 1+1 ammonia solution is prepared by mixing commercially available concentrated ammonia (concentration of 25%) and water in a volume ratio of 1:1.

[0042] In steps (4) and (5) above, the 1+1 hydrochloric acid solution is prepared by mixing concentrated hydrochloric acid (concentration of 37%) and water in a volume ratio of 1:1.

[0043] The above test was repeated four times, and the test results of the alumina (Al2O3) content are shown in Table 1 below:

[0044] Table 1

[0045] First test Second test Third test Fourth test <![CDATA[Al2O3 content (%)]]> 1.26 1.30 1.26 1.29

[0046] As can be seen from the test results in Table 1, the test results of the commercially available ilmenite sand standard sample, tested using the method of this embodiment, are consistent with the results of the standard sample. Therefore, the method for testing the alumina content in ilmenite sand of the present invention can accurately determine the alumina content in ilmenite sand.

[0047] Example 2

[0048] The applicant selected production samples ilmenite sand 1# and ilmenite sand 2#, and tested their alumina content according to the alumina content test method in ilmenite sand of Example 1 of the present invention.

[0049] Meanwhile, on October 22, 2022, the applicant sent the above-mentioned production samples, ilmenite sand No. 1 and ilmenite sand No. 2, to Foshan Ceramic Research Institute for elemental comparison analysis according to the non-ferrous metal industry standard "YS / T360.4-2011 Chemical Analysis Methods for Ilmenite Concentrate Part 4 Determination of Alumina Content by EDTA Titration".

[0050] According to Section 7.2 "Permissible Difference" of the nonferrous metals industry standard "YS / T360.4-2011 Chemical Analysis Methods for Ilmenite Concentrate Part 4: Determination of Alumina Content by EDTA Titration", the difference between analytical results between laboratories should not be greater than the permissible difference listed in Table 2.

[0051] Table 2

[0052] Alumina content / % Permissible difference / % 0.50-1.00 0.10 ＞1.00-3.00 0.30 ＞3.00-5.00 0.40

[0053] The alumina (Al2O3) content test results of Foshan Ceramic Research Institute and the applicant are shown in Table 3 below:

[0054] Table 3

[0055] sample Test results from Foshan Ceramic Research Institute Test results of the test method of this invention <![CDATA[Ilmenite sand 1#Al2O3 content (%)]]> 1.91 1.79 <![CDATA[Ilmenite sand 2# Al2O3 content (%)]]> 2.58 2.30

[0056] As shown in Table 3, the difference in Al2O3 content between Foshan Ceramic Research Institute and the applicant's test results is 0.12% for ilmenite sand #1 and 0.28% for ilmenite sand #2. According to the non-ferrous metals industry standard YS / T360.4-2011 "Chemical Analysis Methods for Ilmenite Concentrate Part 4: Determination of Alumina Content by EDTA Titration," the allowable difference is 0.30%. Therefore, the test results of this invention's method are consistent with the results of the standard method.

Claims

1. A method of testing the content of alumina in ilmenite sand, characterized in that The steps include the following in sequence: (1) 5 grams of sodium hydroxide is added into a nickel crucible, then 0.48-0.52 grams of ilmenite sand sample is weighed and added into the nickel crucible, and the lid is covered; then the nickel crucible is placed into a high-temperature furnace and kept at 770-790 ℃ for 10-12 minutes, and then the nickel crucible is taken out of the high-temperature furnace and cooled; (2) the nickel crucible together with the materials in it is placed into a beaker, and distilled water is added into the beaker to leach the slag in the nickel crucible, then 2 ml of ethanol is added to obtain a leaching solution; then the leaching solution is transferred into a 100 ml volumetric flask, diluted with water to 100 ml, and shaken well; then the materials in the volumetric flask are filtered with a medium-speed qualitative filter paper to obtain a filtrate; (3) 10 ml of the filtrate obtained in step (2) is transferred into a triangular flask, then 10 ml of EDTA solution is added into the triangular flask, and then 10 ml of potassium sodium tartrate solution is added into the triangular flask and shaken well; then the triangular flask is placed on an electric furnace and boiled for 3-5 minutes, and then water is added to 100 ml after cooling; (4) 10 ml of hexamethylenetetramine solution is added into the triangular flask, and then 5 drops of dimethyl phenol orange indicator is added dropwise into the triangular flask, at this time the solution in the triangular flask is purple red; then 1+1 hydrochloric acid solution is used to adjust the solution in the triangular flask to yellow, and the solution in the triangular flask is yellow after 2-3 drops of excess; then zinc acetate standard solution is added dropwise into the triangular flask, and the solution in the triangular flask is purple red, and the reading is not recorded; (5) 3 grams of sodium fluoride is added into the triangular flask, boiled for 3 minutes, and then cooled, and the following operation is carried out according to the color of the solution in one of the following ways: (a) if the solution in the triangular flask is yellow, first adjust the solution in the triangular flask to purple red with 1+1 ammonia water solution; then adjust the solution in the triangular flask to yellow with 1+1 hydrochloric acid solution, and 2-3 drops of excess; finally, use zinc acetate standard solution to titrate the solution in the triangular flask to purple red as the end point, and record the reading; (b) if the solution in the triangular flask is purple red, adjust the solution in the triangular flask to yellow with 1+1 hydrochloric acid solution, and 2-3 drops of excess; finally, use zinc acetate standard solution to titrate the solution in the triangular flask to purple red as the end point, and record the reading.

2. The method of testing the alumina content of ilmenite sand according to claim 1, characterized in that: In step (1), the capacity of the nickel crucible is 30-50 ml.

3. The method of claim 1, wherein the method is characterized by: In step (1), the sodium hydroxide is heated on an electric furnace to remove water after being added into the nickel crucible, and then the ilmenite sand sample is added into the nickel crucible.

4. The method of claim 1, wherein: In step (2), the beaker has a capacity of 250 ml; the volume of the distilled water added is not more than 80 ml.

5. The method of claim 1, wherein the method is characterized by: In step (3), the concentration of the potassium sodium tartrate solution used is 20% wt.

6. The method of testing the alumina content of ilmenite sand according to claim 1, characterized in that: In step (4), the concentration of the hexamethylenetetramine solution used is 20% wt.