CN103940944A - Method for detecting content of calcium oxide in limestone by using DBC (Dibromochloro)-arsenazo indicator - Google Patents
Method for detecting content of calcium oxide in limestone by using DBC (Dibromochloro)-arsenazo indicator Download PDFInfo
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Abstract
The invention provides a method for detecting the content of calcium oxide in limestone by using a DBC (Dibromochloro)-arsenazo indicator. The method comprises the following steps: step 1, preparing a sample solution to be detected; step 2, taking the sample solution to be detected in the step 1 and adding triethanolamine; adjusting the pH value of an obtained solution to be more than or equal to 12 by using a strong base; step 3, adding the DBC-arsenazo indicator into the solution obtained by the step 2, wherein the DBC-arsenazo indicator is prepared by uniformly grinding DBC-arsenazo and sodium chloride; step 4, titrating the solution obtained by the step 3 by using standard EDTA (Ethylene Diamine Tetraacetic Acid) solution until the color of the solution becomes red from blue, namely reaching the final point; then calculating to obtain the content of the calcium oxide. At the titrating final point of the method, the color becomes red from blue, so as to be good for observing by an analyzer; the analysis result has good accuracy and repeatability. Furthermore, the method is simple and convenient to operate and is time-saving; conventional interference elements can coexist in high concentrations.
Description
Technical field
The invention belongs to metallurgical auxiliary raw material chemical analysis technology field, be specifically related to a kind of method that detects content of calcium oxide in limestone with DBC arsenazo indicator.
Background technology
DBC-arsenazo, full name is that (7-naphthalenedisulfonic acid, is abbreviated as DBC-ASA to 3-(2-arsenophenyl azo)-6-, once for rare earth developer for the bromo-4-chlorobenzene of 2,6-bis-azo-4,5-dihydroxy-2.
Lime is the base stock of steel and iron industry, and it has shortening the heat, improves the advantages such as Molten Steel Cleanliness as slag former, is also applied to the sintering process of liquid steel refining and Iron Ore Powder, has good effect, is the main raw and auxiliary material of steel-making and sintering process.
The analysis method comparison of lime (stone) is many, and routine inspection mostly is under the condition of solution PH >=12, with the agent of giving instruction of calcon-carboxylic acid or eriochrome black T, with the titration of EDETATE SODIUM standard solution.
No matter with the agent of giving instruction of calcon-carboxylic acid or eriochrome black T, titration end-point is all to become blueness from redness.Due to differing of interference element in lime (stone), for example, in the time of MnO >=0.10%, just need to pass through complicated separating step, could eliminate the not sharp difficult problem of endpoint observation.In addition, also some analyst, due to physiological reason, becomes blue variable color process to redness insensitive, thereby affects the consistance of titration end-point judgement, causes analysis result repeatability undesirable.
Summary of the invention
For the deficiencies in the prior art, the object of the present invention is to provide a kind of method that detects content of calcium oxide in limestone with DBC-arsenazo indicator.The method provides another End point indication pattern, and exists easy and simple to handlely, saves time, and conventional interference element coexists compared with advantages of higher, and analysis result repeatability is good.
To achieve these goals, technical scheme of the present invention is as follows:
A method that detects content of calcium oxide in limestone with DBC-arsenazo indicator, comprises the steps:
Step 1, the preparation of testing sample solution;
Step 2, divides and gets the testing sample solution that step 1 obtains, and then triethanolamine is added wherein, and uses highly basic regulator solution PH to being more than or equal to 12;
Step 3, adds DBC-arsenazo indicator in the solution that step 2 obtains, and wherein, described DBC-arsenazo indicator is ground and evenly made by DBC-arsenazo and sodium chloride;
Step 4, the solution obtaining by EDTA standard solution titration step three, until the color of solution becomes redness from blueness, reaches home, then by calculating the content of calcium oxide.
Principle of the present invention is: utilize the DBC-arsenazo can be under the alkali condition of PH>=12, same to Ca
2+form blue complex, and this blue complex stability factor is lower than Ca
2+the feature that-EDTA complex compound can be replaced by EDTA, is used as CaO content in EDTA complexometric titration lime (stone) by DBC-arsenazo.
In the step 1 of said method, the preparation of testing sample solution can be the conventional any method in this area, such as directly being put into hydrochloric acid, testing sample dissolves under hot conditions, but (for example all dissolve in order to ensure sample, in sample, may there is the components such as silicate that can not be acid-soluble) so that the degree of accuracy of CaO assay is higher, the preferred following methods of preparation of testing sample solution: first, testing sample is placed in to the crucible that fills in advance mixed flux, cooling after melting 10-20min under 950-1000 DEG C of condition; Then, cooled crucible is placed in to container, and adds deionized water and hydrochloric acid in container, the frit under 70-80 DEG C of condition in heating leaching crucible, the leaching solution obtaining is cooled to constant volume after room temperature, shakes up, thereby obtains testing sample solution; Wherein said mixed flux is ground and is made by natrium carbonicum calcinatum and boric acid, and preferably, the mass ratio of natrium carbonicum calcinatum and boric acid is 2:1.
In said method, as a kind of preferred implementation, in described step 2, described highly basic is potassium hydroxide solution, and more preferably the mass percent concentration of potassium hydroxide solution is 20%.
In said method, described triethanolamine is for sheltering the interference ions, and its addition is this area conventional amount used.
In said method, as a kind of preferred implementation, in described step 3, in described DBC-arsenazo indicator, the mass ratio of DBC-arsenazo and sodium chloride is 0.5-5:99, more preferably, in described DBC-arsenazo indicator, the mass ratio of DBC-arsenazo and sodium chloride is 1:99.
In said method, as a kind of preferred implementation, in described step 3, the addition of described DBC-arsenazo indicator is that 0.2-0.3g(is viewed as suitable with solution colour fit analysis person after adding indicator)
In said method, as a kind of preferred implementation, in described step 4, the concentration of described EDTA standard solution is 0.01-0.02mol/L, and more preferably, the concentration of described EDTA standard solution is 0.01mol/L.
In said method, as a kind of preferred implementation, also comprise blank, described blank refers to that the sampling amount of testing sample is that 0.0000g(is blank sample), it is operated to step 4 according to described step 1 equally, thereby obtain the volume of EDTA standard solution that blank sample consumes.The computing formula of described calcium oxide content is as follows:
In formula,
V: the EDTA standard solution volume that testing sample consumes, L;
V
0: the EDTA standard solution volume that blank consumes, L;
ω %: the percentage composition of calcium oxide;
M: point sample to be tested quality of getting in described step 2, g;
The unit of EDTA concentration of standard solution is mol/L.
Than prior art, the present invention has following beneficial effect: titration end-point becomes redness from blueness, is more conducive to analyst and observes, and analysis result accuracy, repeatability are good.In addition, easy and simple to handle, save time, conventional interference element can coexist with higher concentration.
Embodiment
For making the object, technical solutions and advantages of the present invention clearer, below embodiment of the present invention is described further in detail.The content below the relating to content that is weight percentage.
The mensuration of embodiment 1 content of calcium oxide in limestone
Step 1, takes 0.5000g testing sample, is placed in the platinum crucible that fills in advance 3.0g mixed flux (2 parts of natrium carbonicum calcinatums and 1 part of boric acid are ground and make), add a cover, be placed in 980 DEG C of high temperature furnaces, melting 15 minutes, take out platinum crucible, rotate while hot, be cooled to room temperature;
Step 2, cooled platinum crucible is placed in to 300ml beaker, add 100ml deionized water, 15ml concentrated hydrochloric acid (hydrochloric acid that massfraction is 37%), the frit in 75 DEG C of left and right heating leaching platinum crucibles, takes out platinum crucible after leaching, cooling leaching solution is to room temperature, then leaching solution is settled to 250ml by water, shakes up, and this is storing solution (being testing sample solution);
Step 3, divide and get 25.00ml storing solution, be placed in 250ml conical flask, add 25ml deionized water, add 5ml triethanolamine solution (mass percent concentration of triethanolamine is 20%), add 10ml potassium hydroxide solution (mass percent concentration of potassium hydroxide is 20%), now solution PH is 12 again;
Step 4, in the solution obtaining to step 3, add 0.25g left and right DBC arsenazo indicator (grind and evenly make by 1 part of commercially available DBC-arsenazo and 99 parts of sodium chloride), then the EDTA standard solution titration that is 0.01mol/L by concentration makes it to become redness from blueness containing the solution of DBC arsenazo indicator, be terminal, the EDTA standard solution volume that the EDTA standard solution volume that record consumes and the blank with biconditional operation consume;
Step 5, is used following computing formula to obtain result:
V in formula: sample consumes EDTA standard solution volume, L;
V
0: blank EDTA standard solution volume, the L of consuming;
M: divide the quality of materialsing, this law operation, divides the quality of materialsing to be fixed as 0.0500g;
ω %: the percentage composition of calcium oxide.
This embodiment has adopted in said method his-and-hers watches 15 testing samples in 2 lime stone standard models and table 2 to measure, in table 1 and table 2, the result of each sample is the mean value of 3 replication results, as can be seen from Table 1 and Table 2, the inventive method accuracy is high, repeatability good.
The measurement result of calcium oxide content in table 1 lime stone standard model
The measurement result of calcium oxide content in table 2 testing sample (the result comparison of measuring with National Standard Method)
The choice experiment of titratable acidity in embodiment 2, detection method of the present invention
Using acidometer as conditioning equipment, being determined at pH value is 7.5,8.1,8.4,9.2,10.2,10.7,11.3,12.4,13.1 o'clock Ca
2+the complex compound forming with DBC-arsenazo, in the absorbance at 620nm wavelength place, can be determined Ca from absorbance
2+the complex compound forming with DBC-arsenazo o'clock has stable absorbance in PH>=10.
Therefore, in the present invention, titration experiments is chosen under the condition of PH >=12 and completes, and now in solution, can obtain stable observation color.
In embodiment 3, the inventive method, allow the concentration determination experiment of disturbing kation to coexist
The present embodiment is except step 3 is different from embodiment 1 step 3, other operation stepss are all same as embodiment 1, the testing sample adopting in the present embodiment is lime stone standard model GBW03107, the step 3 of the present embodiment is specially: get 65 250ml conical flasks, add in advance respectively the solution that contains different metal kation (disturbing kation) of 1mL variable concentrations gradient, and then add successively respectively 25ml sample storing solution, 25ml deionized water, 5ml triethanolamine solution (mass percent concentration of triethanolamine is 20%), 10ml potassium hydroxide solution (mass percent concentration of potassium hydroxide is 20%), now solution PH is 12, the metal cation solution replication of each concentration gradient 3 times.
The described cationic solution of different metal that contains is respectively: 1) contain Fe
2+aqueous solution, wherein Fe
2+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 2) contain Fe
3+aqueous solution, wherein Fe
3+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 3) contain Mg
2+aqueous solution, wherein Mg
2+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 4) contain Zn
2+aqueous solution, wherein Zn
2+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 5) contain Al
3+aqueous solution, wherein Al
3+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 6) contain Ba
2+aqueous solution, wherein Ba
2+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 7) contain Cu
2+aqueous solution, wherein Cu
2+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 8) contain Pb
2+aqueous solution, wherein Pb
2+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 9) contain Si
4+aqueous solution, wherein Si
4+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 10) contain V
5+aqueous solution, wherein V
5+5 concentration gradients are set, are followed successively by 5mg/mL, 8mg/mL, 9mg/mL, 10mg/mL, 11mg/mL; 11) contain Cr
3+aqueous solution, wherein Cr
3+5 concentration gradients are set, are followed successively by 0.5mg/mL, 1mg/mL, 1.5mg/mL, 2mg/mL, 2.5mg/mL; 12) contain Ni
3+aqueous solution, wherein Ni
3+5 concentration gradients are set, are followed successively by 0.5mg/mL, 1mg/mL, 1.5mg/mL, 2mg/mL, 2.5mg/mL; 13) contain Mn
2+aqueous solution, wherein Mn
2+5 concentration gradients are set, are followed successively by 0.2mg/mL, 0.5mg/mL, 0.8mg/mL, 1.0mg/mL, 1.2mg/mL.
By the setting of above experiment, to observe to add and disturb kation compared with not adding interference kation, the change color of titration end-point and mark liquid Expenditure Levels, determine the Fe that solution coexists below 10mg
2+, Fe
3+, Mg
2+, Zn
2+, Al
3+, Ba
2+, Cu
2+, Pb
2+, Si
4+or V
5+, or the following Cr of the 2mg that coexists
3+or Ni
3+, or the following Mn of the 1mg that coexists
2+time noiseless to titration end-point, and do not find Common Anions and NH by said method yet
4 +while existence in a large number, affect endpoint observation.
Can determine Mn by above-mentioned experiment
2+because forming complex compound with DBC arsenazo, while existence in a large number, easily cause the not sharp result that affects of titration end-point variable color, but method End point indication color change of the present invention easily observes compared with GB, so can allow 2wt% with interior Mn
2+exist and noiseless to titration end-point; Cr
3+, N
i3+because itself has color, when content exceedes the Cr of 3.8wt%
3+or/and Ni
3+while existence, can affect endpoint observation, therefore adopt again the inventive method to carry out needing to be first isolated to remove interference before calcium oxide content mensuration; The inventive method can allow Fe
2+, Fe
3+, Mg
2+, Zn
2+, Al
3+, Ba
2+, Cu
2+, Pb
2+, Si
4+, V
5+in the total concentration of one or more interfering ions in 16.7wt%, exist and noiseless to titration end-point.
These are only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any amendment of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.
Claims (10)
1. a method that detects content of calcium oxide in limestone with DBC-arsenazo indicator, is characterized in that, comprises the steps:
Step 1, the preparation of testing sample solution;
Step 2, divides and gets the testing sample solution that step 1 obtains, and then triethanolamine is added wherein, and uses highly basic regulator solution PH to being more than or equal to 12;
Step 3, adds DBC-arsenazo indicator in the solution that step 2 obtains, and wherein, described DBC-arsenazo indicator is ground and evenly made by DBC-arsenazo and sodium chloride;
Step 4, the solution obtaining by EDTA standard solution titration step three, until the color of solution becomes redness from blueness, reaches home, then by calculating the content of calcium oxide.
2. method according to claim 1, is characterized in that, the preparation method of described testing sample solution is as follows: first, testing sample is placed in to the crucible that fills in advance mixed flux, and cooling after melting 10-20min under 950-1000 DEG C of condition; Then, cooled crucible is placed in to container, and adds deionized water and hydrochloric acid in container, the frit under 70-80 DEG C of condition in heating leaching crucible, the leaching solution obtaining is cooled to constant volume after room temperature, shakes up, thereby obtains testing sample solution; Wherein said mixed flux is ground and is made by natrium carbonicum calcinatum and boric acid.
3. method according to claim 2, is characterized in that, the mass ratio of described natrium carbonicum calcinatum and described boric acid is 2:1.
4. method according to claim 1, is characterized in that, in described step 2, described highly basic is potassium hydroxide solution, and preferably the mass percent concentration of potassium hydroxide solution is 20%.
5. method according to claim 1, is characterized in that, in described step 3, in described DBC-arsenazo indicator, the mass ratio of DBC-arsenazo and sodium chloride is 0.5-5:99.
6. method according to claim 5, is characterized in that, in described DBC-arsenazo indicator, the mass ratio of DBC-arsenazo and sodium chloride is 1:99.
7. method according to claim 1, is characterized in that, in described step 3, the addition of described DBC-arsenazo indicator is 0.2-0.3g.
8. method according to claim 1, is characterized in that, in described step 4, the concentration of described EDTA standard solution is 0.01-0.02mol/L, and preferably, the concentration of described EDTA standard solution is 0.01mol/L.
9. method according to claim 1, is characterized in that, also comprises blank, and described blank refers to that the sampling amount of testing sample is 0.0000g.
10. method according to claim 1, is characterized in that, the computing formula of described calcium oxide content is as follows:
In formula,
V: the EDTA standard solution volume that sample to be tested consumes, L;
V
0: the EDTA standard solution volume that blank consumes, L;
ω %: the percentage composition of calcium oxide;
M: point sample to be tested quality of getting in described step 2, g;
The unit of EDTA concentration of standard solution is mol/L.
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| CN104330521A (en) * | 2014-11-03 | 2015-02-04 | 武汉钢铁(集团)公司 | Method for determining content of calcium oxide in raw and auxiliary metallurgical materials |
| CN105136785A (en) * | 2015-07-29 | 2015-12-09 | 山东西王特钢有限公司 | Metallurgical lime calcium oxide content determination method |
| WO2024027327A1 (en) * | 2022-08-01 | 2024-02-08 | 北矿检测技术股份有限公司 | Rare earth oxide standard sample, and preparation process therefor |
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| CN105136785A (en) * | 2015-07-29 | 2015-12-09 | 山东西王特钢有限公司 | Metallurgical lime calcium oxide content determination method |
| WO2024027327A1 (en) * | 2022-08-01 | 2024-02-08 | 北矿检测技术股份有限公司 | Rare earth oxide standard sample, and preparation process therefor |
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Effective date of registration: 20200415 Address after: 435001 Huangshi Road, Hubei, Huangshi, No. 316 Patentee after: Daye Special Steel Co., Ltd Address before: 435001 Huangshi Road, Hubei, Huangshi, No. 316 Patentee before: DAYE SPECIAL STEEL Co.,Ltd. |