CN105259302A - Method for directly measuring content of trivalent vanadium in vanadium slag - Google Patents

Abstract

The invention belongs to a chemical analysis method and particularly relates to an analysis method for directly measuring the content of trivalent vanadium in vanadium slag. The method for directly measuring the content of trivalent vanadium in vanadium slag comprises the following steps that A, a sample X/g to be measured is taken and placed into a reaction container; B, hydrochloric acid and fluoride salt are added to dissolve the sample, titanium chloride is added to serve as a masking agent, carbon dioxide serves as protection gas, and heating is carried out until the solution is boiled slightly; C, after the sample is completely dissolved, sodium sulfite is added, reaction continues to be carried out for 5-10 min, heating is stopped, and cooling is carried out to the temperature of 60 DEG C-70 DEG C; D, sulfuric acid is added into the cooled solution to adjust acidity, ammonium thiocyanate is dripped to serve as an indicator, ammonium ferric sulfate standard liquid serves as a volumetric solution, titration is carried out until the reaction solution becomes dark red, and titration is stopped so that the ammonium ferric sulfate solution can be consumed to calculate the content of trivalent vanadium in vanadium slag. The method for measuring trivalent vanadium in vanadium slag is simple and high in accuracy.

Description

Method for direct determination of trivalent vanadium content in vanadium slag

technical field

The invention belongs to chemical analysis methods, in particular to an analysis method for directly measuring the content of trivalent vanadium in vanadium slag.

Background technique

Vanadium slag is a process ore made of vanadium-containing raw materials through smelting to fully enrich vanadium. It is the main raw material for vanadium extraction (V ₂ O ₅ ) and has great economic value. Understanding the valence state and content of vanadium slag is of great significance to determine the production process conditions of vanadium in the vanadium extraction process and improve the production conversion rate. Aiming at the research on the valence state of vanadium in vanadium slag, there have been many domestic studies, among which "X-ray photoelectric spectroscopy analysis of the valence state of vanadium in vanadium slag clinker" and "Valence state analysis of vanadium in vanadium slag" are qualitative analysis "Valence State Analysis of Vanadium in Sodium Vanadium Slag" is a quantitative analysis, the method is to measure tetravalent vanadium and pentavalent vanadium content by ferrous ammonium sulfate titration method, subtract pentavalent vanadium and tetravalent vanadium content from total vanadium to get The method of trivalent vanadium content is relatively complicated and cumbersome, and trivalent vanadium is measured indirectly, and the accuracy is not high.

Also for example, the application number is "201210572028.3", and the title of the invention is "method for measuring vanadium content", which discloses a method comprising the following steps: digesting a vanadium-containing sample with hydrochloric acid to obtain a vanadium-containing solution; Vanadium content in vanadium-containing solutions. This patent uses ICP to measure and analyze the content of vanadium in the vanadium-containing liquid, and the detection cost and detection equipment are relatively expensive, and there are still large experimental errors.

The application number is "201310030450.0", and the title of the invention is "Method for Determination of Tetravalent Vanadium Content in Vanadium Oxide", which discloses a measurement procedure as follows: (1) Determination of the total vanadium content in the vanadium oxide sample; (2) Using alkali Dissolve the same vanadium oxide sample by dissolution method, filter and separate the insoluble matter, and obtain the filtrate and insoluble trivalent vanadium precipitate; (3) add sulfuric acid to the filtrate, drop the vanadium indicator, and titrate the pentavalent vanadium with ferrous ammonium sulfate standard solution vanadium content; (4) Add sulfuric acid and nitric acid to the trivalent vanadium precipitation and heat to dissolve, then add ferrous ammonium sulfate to reduce vanadium to a low-valence state, then add dropwise potassium permanganate to oxidize vanadium to pentavalent; then add Urea, reduce excess potassium permanganate with sodium nitrite solution, and titrate the trivalent vanadium content with ferrous ammonium sulfate standard solution after adding vanadium indicator dropwise; (5) subtract trivalent vanadium and pentavalent vanadium from the total vanadium content The content is the tetravalent vanadium content. This patented method is also an indirect determination method of trivalent vanadium, the determination process is complicated and the accuracy is not high.

According to literature review, scholars at home and abroad believe that vanadium in vanadium slag mainly exists in trivalent, forming vanadium-containing spinel, and the content of pentavalent vanadium and tetravalent vanadium is very small. The inventor believes that the content of trivalent vanadium in vanadium slag can be directly measured. Improve the accuracy and analysis rate of trivalent vanadium determination.

Vanadium slag contains a large amount of manganese, silicon, calcium, magnesium, iron and other elements, which form different phases after roasting. To solve the problem of trivalent vanadium determination, first solve the problem of sample decomposition, try to open the vanadium-containing phase as much as possible when decomposing the sample; secondly, eliminate the interference of high-valent manganese, high-valent iron, and high-valent vanadium, and ensure that the tetravalent vanadium in the vanadium slag Vanadium is not reduced, and high-valent manganese, high-valent iron, high-valent vanadium, etc. have strong reactivity with trivalent vanadium, and cannot coexist in a certain acidic medium, and will oxidize trivalent vanadium to tetravalent vanadium, which will interfere with the determination of trivalent vanadium , it is necessary to select a suitable reducing agent that can preferentially reduce high-valent substances and ensure that tetravalent vanadium is not reduced; finally, because trivalent vanadium has strong reducing properties, it is necessary to ensure that trivalent vanadium is not oxidized during the entire analysis process.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method with simple method and high accuracy, which can directly measure trivalent vanadium in vanadium slag.

A method for directly measuring trivalent vanadium content in vanadium slag of the present invention comprises the following steps:

A. Take X/g of the sample to be tested with a particle size ≤ 0.125mm in the reaction vessel;

B. Add hydrochloric acid and fluoride salt to the reaction vessel to dissolve the sample to be tested, add titanium trichloride as a masking agent, add sodium bicarbonate to generate carbon dioxide protective gas, cover the reaction vessel to isolate the air, and heat until the solution boils slightly;

Among them, based on 0.1-0.2g of the sample to be tested, the amount of hydrochloric acid added is 20-40mL, and the amount of fluoride salt added is 0.5g-1.0g;

C. After the sample to be tested is completely dissolved, add sodium sulfite, continue to react for 5-10 minutes in a slightly boiling state, stop heating, and cool to 60-70°C;

D. Add sulfuric acid to the cooled solution in step C to adjust the acidity of the solution to 6-8mol·L ^-1 , then add ammonium thiocyanate dropwise as an indicator, and use ferric sulfate with a molar concentration of c/mol·L ^-1 The ammonium standard solution is a titration solution, and titration is performed until the reaction solution becomes dark red, and the titration is stopped, and the volume V/mL of the ferric ammonium sulfate solution consumed is recorded, and the content of trivalent vanadium in the vanadium slag is determined according to formula I:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1000</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 50.94</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

Among them, V ₀ ——the volume of ammonium ferric sulfate standard solution consumed by the blank experiment, the unit is mL;

50.94——The relative atomic mass of vanadium, in g/mol.

The method for directly measuring the content of trivalent vanadium in the above-mentioned vanadium slag, the hydrochloric acid used in the step B is hydrochloric acid (1+1), that is, the volume ratio of concentrated hydrochloric acid and water is 1:1, and its molar concentration is 6mol L ^-1 .

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein the concentration of titanium trichloride in step B is 5-15 wt%.

Further, as a more preferred technical solution, in the above-mentioned method for directly measuring the content of trivalent vanadium in vanadium slag, the concentration of titanium trichloride in step B is preferably 10 wt%.

The above-mentioned method for directly measuring the content of trivalent vanadium in vanadium slag, wherein the fluoride salt is at least one of sodium fluoride or potassium fluoride.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein sodium bicarbonate needs to be added after adding sodium sulfite in step C to generate carbon dioxide protective gas.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein the titration temperature in step D is controlled at 60-70°C.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein the molar concentration c of ferric ammonium sulfate in step D is 0.01-0.03 mol·L ^-1 .

Further, as a more preferred technical solution, in the above-mentioned method for directly measuring the content of trivalent vanadium in vanadium slag, the molar concentration c of ferric ammonium sulfate in step D is preferably 0.02 mol·L ^-1 .

The method for directly measuring the content of trivalent vanadium in the above-mentioned vanadium slag, wherein the sulfuric acid used in the step D is sulfuric acid (1+1), that is, 1 volume of 98wt% concentrated sulfuric acid is prepared by adding 1 volume of water, and its concentration is 9 ~9.5 mol·L ^-1 , preferably 9.2 mol·L ^-1 .

Compared with the prior art, the method for directly measuring the trivalent vanadium content in the vanadium slag of the invention has the advantages of high measurement accuracy, good precision, simple measurement method and wide application prospects. Because the vanadium slag contains a large amount of elements such as manganese, silicon, calcium, magnesium, iron, etc., these elements form different phases after roasting, the method of the present invention eliminates high-valent manganese, high-valent iron, And the interference of high-valent vanadium, and ensure that the tetravalent vanadium in the vanadium slag is not reduced, reducing the interference on the determination of trivalent vanadium, and finally ensuring that the trivalent vanadium is not oxidized during the entire analysis process, reducing the measurement error of trivalent vanadium.

detailed description

A method for directly measuring trivalent vanadium content in vanadium slag of the present invention comprises the following steps:

A. Take X/g of the sample to be tested with a particle size of ≤0.125mm in the reaction container; the sample for analysis should be sampled and prepared according to YB/T008, and the sample should pass through a sieve of 0.125mm;

B. Add hydrochloric acid and fluoride salt to the reaction vessel to dissolve the sample to be tested, add titanium trichloride as a masking agent, add sodium bicarbonate to generate carbon dioxide protective gas, cover the reaction vessel to isolate the air, and heat until the solution boils slightly;

Among them, based on 0.1-0.2g of the sample to be tested, the amount of hydrochloric acid added is 20-40mL, and the amount of fluoride salt added is 0.5g-1.0g;

C. After the sample to be tested is completely dissolved, add sodium sulfite, continue to react for 5-10 minutes in a slightly boiling state, stop heating, and cool to 60-70°C;

D. Add sulfuric acid to the cooled solution in step C to adjust the acidity of the solution to 6-8mol·L ^-1 , then add ammonium thiocyanate dropwise as an indicator, and use ferric sulfate with a molar concentration of c/mol·L ^-1 The ammonium standard solution is a titration solution, and titration is performed until the reaction solution becomes dark red, and the titration is stopped, and the volume V/mL of the ferric ammonium sulfate solution consumed is recorded, and the content of trivalent vanadium in the vanadium slag is determined according to formula I:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1000</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 50.94</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

Among them, V ₀ ——the volume of ammonium ferric sulfate standard solution consumed by the blank experiment, the unit is mL;

50.94——The relative atomic mass of vanadium, in g/mol.

The above-mentioned method for directly measuring the content of trivalent vanadium in vanadium slag, the hydrochloric acid used in the step B is hydrochloric acid (1+1), that is, the concentrated hydrochloric acid and water volume ratio is 1:1, and its molar concentration is 6mol L ^-1 , the addition of hydrochloric acid is to dissolve the metal oxides and carbonates in the vanadium slag.

The method for directly measuring the content of trivalent vanadium in vanadium slag as described above, wherein the fluoride salt is at least one of sodium fluoride or potassium fluoride, sodium fluoride or potassium fluoride is a cosolvent, and adding it is used for dissolving Silica and silicate in the sample.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein the concentration of titanium trichloride in step B is 5-15 wt%.

Further, as a more preferred technical solution, in the above-mentioned method for directly measuring the content of trivalent vanadium in vanadium slag, the concentration of titanium trichloride in step B is preferably 10 wt%.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein sodium bicarbonate needs to be added after adding sodium sulfite in step C to generate carbon dioxide protective gas.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein the titration temperature in step D is controlled at 60-70°C.

The method for directly measuring the content of trivalent vanadium in vanadium slag described above, wherein the molar concentration c of ferric ammonium sulfate in step D is 0.01-0.03 mol·L ^-1 .

Further, as a more preferred technical solution, in the above-mentioned method for directly measuring the content of trivalent vanadium in vanadium slag, the molar concentration c of ferric ammonium sulfate in step D is preferably 0.02 mol·L ^-1 .

The method for directly measuring the content of trivalent vanadium in the above-mentioned vanadium slag, wherein the sulfuric acid used in the step D is sulfuric acid (1+1), that is, 1 volume of 98wt% concentrated sulfuric acid is prepared by adding 1 volume of water, and its concentration is 9 ~9.5 mol·L ^-1 , preferably 9.2 mol·L ^-1 .

In the step B of the present invention, excessive titanium trichloride is added to make the high-valent substances in the sample react with titanium trichloride first, so as to ensure that the trivalent vanadium is not oxidized; add sodium bicarbonate to react with hydrochloric acid to generate carbon dioxide gas or directly pass in carbon dioxide gas , isolate the air, and ensure that the trivalent vanadium is not oxidized by the air.

In step C of the present invention, sodium sulfite is added to oxidize excess titanium trichloride, and excess sodium sulfite decomposes in a slightly boiling state.

In the step D of the present invention, in order to improve the reaction rate during titration, the titration temperature is set to be 60 to 70° C., the ferric ammonium sulfate standard titration solution is used to titrate the trivalent vanadium in the solution, and finally the ferric ammonium sulfate standard titration solution is used to measure the trivalent vanadium in the solution content.

The method for determining the content of trivalent vanadium in vanadium slag according to the present invention will be described in detail below.

According to the present invention, the method for measuring trivalent vanadium content specifically comprises the following steps:

A. Weigh 0.1g ~ 0.2g of the sample to be tested in the conical flask;

B. Add 0.5g~1g sodium fluoride, 1g sodium bicarbonate, 20mL~40mL hydrochloric acid, 1.0mL~2.0mL titanium trichloride, pour a small amount of water, cover the porcelain crucible, and place the sample in a high temperature furnace to boil quickly , move the sample into a low-temperature heating plate to keep the sample slightly boiling;

C. After the sample is completely decomposed, add 2.0mL~4.0mL of sodium sulfite, add 0.5g of sodium bicarbonate, cover the porcelain crucible and keep boiling for 5min~10min to decompose the remaining sodium sulfite; remove it after the decomposition of sodium sulfite is complete, and let it cool slightly To 60 ℃ ~ 70 ℃;

D. Add 30mL-50mL sulfuric acid to adjust the acidity, add 50mL water, add ammonium thiocyanate indicator, and titrate with ferric ammonium sulfate standard titration solution until the solution is dark red as the end point.

In the trivalent vanadium content determination method of the present invention, the suitable sample size of the sample is 0.1g～0.2g; titanium trichloride is analytically pure or above, the mass concentration is 10%, and the addition amount is 1.0mL～2.0mL ; Sodium sulfite is analytically pure or above, with a mass concentration of 5%, and the addition amount is 2.0mL to 4.0mL. Hydrochloric acid and sulfuric acid are analytically pure and above, the concentration is (1+1) (volume ratio); ammonium thiocyanate is analytically pure and above, the mass concentration is 40%, and the addition is 5mL; ferric ammonium sulfate is analytically pure And above, the concentration is 0.01～0.03mol·L ^-1 ; the quality of water used in the analysis complies with GB/T6682-1992 grade 3 and above distilled water.

The specific implementation of the present invention will be further described below in conjunction with the examples, and the present invention is not limited to the scope of the examples.

The mensuration of trivalent vanadium in the vanadium slag of embodiment 1

Weigh 5 samples, 0.15g each in a conical flask, weigh 0.1-0.2g of the sample to be tested in a conical flask, add 1g sodium fluoride, 1g sodium bicarbonate, 30mL hydrochloric acid, 1.0mL trichloride Titanium, pour a small amount of water, cover the porcelain crucible lid, place the sample in a high-temperature furnace to boil quickly, then move the sample to a low-temperature heating plate to keep the sample slightly boiling. After the sample is completely decomposed, add 2.0 mL of sodium sulfite and 0.5 g of sodium bicarbonate, cover the porcelain crucible and continue to boil for 5 minutes to decompose the remaining sodium sulfite. Take it off, cool to 60-70°C, add 50mL of water, 40mL of sulfuric acid, add 5mL of ammonium thiocyanate indicator, titrate with ferric ammonium sulfate standard titration solution until the solution is dark red as the end point, the preparation and calibration of ferric ammonium sulfate are according to 4.11 in YB/T4392.1-2014;

Blank experiment setup: take another Erlenmeyer flask, without adding the sample to be tested, directly add 1g sodium fluoride, 1g sodium bicarbonate, 30mL hydrochloric acid, 1.0mL titanium trichloride, pour a small amount of water, cover the porcelain crucible , put the mixed material in a high-temperature furnace to boil quickly, then move the sample into a low-temperature heating plate to keep the sample slightly boiling, then add 2.0 mL of sodium sulfite, add 0.5 g of sodium bicarbonate, cover the porcelain crucible and continue to keep boiling for 5 minutes to decompose Sodium sulfite remaining. Take it off, cool to 60-70°C, add 50mL of water, 40mL of sulfuric acid, add 5mL of ammonium thiocyanate indicator, titrate with ferric ammonium sulfate standard titration solution until the solution is dark red as the end point, the preparation and calibration of ferric ammonium sulfate are according to 4.11 in YB/T4392.1-2014;

The analysis result is calculated according to the following formula:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1000</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 50.94</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In the formula:

c——the molar concentration of the ammonium ferric sulfate standard solution, in moles per liter (mol/L);

V——The titration sample solution consumes the volume of ferric ammonium sulfate standard solution, in milliliters (mL);

V ₀ ——the volume of ferric ammonium sulfate standard solution consumed by the blank experiment, in milliliters (mL);

m - the amount of sample, in grams (g);

50.94——The relative atomic mass of vanadium, in grams per mole (g/mol).

The measurement result of table 1V ³⁺ content

RSD in Table 1 is the relative standard deviation.

The determination rate of recovery of trivalent vanadium in the vanadium slag of embodiment 2

Weigh 4 samples, each 0.15g in a conical flask, weigh 0.1-0.2g of the sample to be tested in a conical flask, add 1g sodium fluoride, 1g sodium bicarbonate, 30mL hydrochloric acid, 1.0mL trichloride Titanium, into a small amount of water, add trivalent vanadium standard solution (concentration of trivalent vanadium standard solution 4.48mg/mL) 3.0mL, 4.0mL, 5.0mL cover porcelain crucible lid, put the sample in a high-temperature furnace to boil quickly, and immediately The sample is moved into a low temperature heating plate to keep the sample slightly boiling. After the sample is completely decomposed, add 2.0 mL of sodium sulfite and 0.5 g of sodium bicarbonate, cover the porcelain crucible and keep boiling for 5 minutes to decompose the remaining sodium sulfite. Take it off, cool it to 60-70°C, add 50mL of water, add 40mL of sulfuric acid, add 5mL of ammonium thiocyanate indicator, and titrate with ferric ammonium sulfate standard titration solution until the solution is dark red as the end point. The blank experiment settings are the same as in Example 1. The preparation and calibration of ferric ammonium sulfate are carried out according to 4.11 in YB/T4392.1-2014, and the analysis results are calculated according to the following formula:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1000</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 50.94</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>$

In the formula:

c——the molar concentration of the ammonium ferric sulfate standard solution, in moles per liter (mol/L);

V——The titration sample solution consumes the volume of ferric ammonium sulfate standard solution, in milliliters (mL);

V ₀ ——the volume of ferric ammonium sulfate standard solution consumed by the blank experiment, in milliliters (mL);

m - the amount of sample, in grams (g);

50.94——The relative atomic mass of vanadium, in grams per mole (g/mol).

Table 2V ³⁺ amount recovery experimental design and its results

Amount of added V ³⁺ , mg 0.0 13.44 17.92 22.40 Measured V ³⁺ amount, mg 13.14 26.42 30.95 35.14 Recovered V ³⁺ amount, ug / 13.28 17.81 22.00 Recovery rate,% / 98.81 99.39 98.21

It can be seen from the above Examples 1-2 that the method for determining trivalent vanadium in vanadium slag according to the present invention has high accuracy and good precision, and has wide application prospects.

Claims (9)

1. directly measure the method for trivalent vanadium content in vanadium slag, it is characterized in that: comprise the following steps:

A, get the testing sample X/g of particle diameter≤0.125mm in reaction vessel;

B, add hydrochloric acid and fluoride salt dissolve testing sample in reaction vessel, adding titanium trichloride is screening agent, adds sodium bicarbonate to produce carbon-dioxide protecting gas, adds a cover isolated air to reaction vessel, is heated to that solution is micro-to boil;

Wherein, according to 0.1 ~ 0.2g testing sample meter, hydrochloric acid addition is 20 ~ 40mL, and fluoride salt addition is 0.5g ~ 1.0g;

C, after testing sample dissolves completely, add sodium sulphite, under slight boiling condition, continue reaction 5 ~ 10min, stop heating, be cooled to 60 ~ 70 DEG C;

D, add sulfuric acid by cooled for step C solution, adjustment solution acidity is 6 ~ 8molL ^-1, then to drip ammonium thiocyanate be indicator, take volumetric molar concentration as c/molL ^-1ferric ammonium sulfate titer be vs, carry out titration, until reaction solution becomes kermesinus, stop titration, record consume ferric ammonium sulfate liquor capacity V/mL, measure the content of trivalent vanadium in vanadium slag according to formula I:

$W_V\left(\%\right)=\frac{c(V-V_0)}{1000X}\&times;50.94\&times;100---\left(I\right)$

Wherein, V ₀---blank assay consumes ferric ammonium sulfate standard solution volume, and unit is mL;

50.94---the relative atomic mass of vanadium, unit is g/mol.

2. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: described fluoride salt is at least one in sodium fluoride or potassium fluoride.

3. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: in step B, concentration of hydrochloric acid is 6molL ^-1.

4. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: in step B, the concentration of titanium trichloride is 5 ~ 15wt%, be preferably 10wt%.

5. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: need after adding sodium sulphite in step C to add sodium bicarbonate to produce carbon-dioxide protecting gas.

6. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: in step D, titration temperature is 60 ~ 70 DEG C.

7. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: in step D, ferric ammonium sulfate volumetric molar concentration c is 0.01 ~ 0.03molL ^-1.

8. directly measure the method for trivalent vanadium content in vanadium slag according to claim 8, it is characterized in that: in step D, ferric ammonium sulfate volumetric molar concentration c is 0.02molL ^-1.

9. directly measure the method for trivalent vanadium content in vanadium slag according to claim 1, it is characterized in that: in step D, sulfuric acid concentration is 9 ~ 9.5molL ^-1, be preferably 9.2molL ^-1.