CN102565041B - Determination method of sodium oxide content in regenerated sand of sodium silicate sand - Google Patents
Determination method of sodium oxide content in regenerated sand of sodium silicate sand Download PDFInfo
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- CN102565041B CN102565041B CN201110000331.1A CN201110000331A CN102565041B CN 102565041 B CN102565041 B CN 102565041B CN 201110000331 A CN201110000331 A CN 201110000331A CN 102565041 B CN102565041 B CN 102565041B
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Abstract
The invention provides a determination method of sodium oxide content in regenerated sand of sodium silicate sand. The method comprises the steps that: water and a sulfuric acid standard solution are added to scrap-iron-removed regenerated sand; the mixture is continuously heated and stirred for 28-40min under a temperature maintained at 80-90 DEG C; the mixture is cooled to room temperature, and is filtered, such that filter residue and filtrate are obtained; the filter residue is washed by using water, until recovered washing liquid is neutral; the washing liquid is combined with the test solution obtained by filtering; a bromcresol green-methyl red indicating agent is added into the test solution, and the test solution is titrated by using a sodium hydroxide standard solution, until the test solution turns from red to green; the volume of the consumed sodium hydroxide standard solution is recorded; and the sodium oxide content in the regenerated sand is calculated. With the method provided by the invention, the sodium oxide content in the regenerated sand of the sodium silicate sand can be accurately determined, such that an accurate data about whether the regenerated sand can be reused can be provided.
Description
Technical field
The present invention relates to a kind of assay method of sodium oxide content, relate in particular to the assay method of sodium oxide content in a kind of reclaimed sand of sodium silicate sand.
Background technology
The effect of molding sand in foundry production is very important, and the casting wasted product causing because of the poor quality of molding sand accounts for 30～50% of the total waste product of foundry goods.Molding sand is different by cementing agent used, can be divided into clay-bonded sand, sodium silicate sand, cement bonded sand, resin sand etc.Wherein the most frequently used is to using the sodium silicate sand that sodium silicate forms as cementing agent.When using sand mold to carry out Foundry Production, 1 ton of foundry goods of every production will produce 6～15 tons with the old sand of crossing.For avoiding the waste of old sand, after generally old sand can being reclaimed or live again, reuse.Using the molding sand of sodium silicate as cementing agent, because the sclerous reaction at casting process sodium silicate is irreversible, can not simply old sand be reclaimed and be used, and the failed adhensive membrane of sand grain surface need to be removed, to after regenerating used, reuse, this old sand through the basic recovery of regeneration processing roughing sand performance is called reclaimed sand.
When using reclaimed sand again to carry out Foundry Production, Na in reclaimed sand
2the content of O, can appreciable impact the carrying out smoothly and casting quality of Foundry Production, if remaining Na in reclaimed sand
2o too high levels, just has a large amount of Na
2water in O and sodium silicate reacts, and causes mulling process to cause continuous formation and the cohesion of silica sol because sodium silicate dewaters, and finally causes the aggravation of molding sand fragility, loses intensity, hinders the carrying out of casting work.Excessive Na in addition
2the existence of O also can cause the problems such as softening appears in molding sand under the heating of potting syrup, distortion, bulging.Therefore determine Na in reclaimed sand
2the content of O is old sand to be reused for to the important step of Foundry Production.
Prior art is by reclaimed sand being put into after water ebuillition of heated, cooling, and repeatedly washing, makes the Na in reclaimed sand
2o is dissolved in water, by standard acid titration, measures the content of sodium oxide molybdena in reclaimed sand.But facts have proved, said method can not make the sodium oxide molybdena in reclaimed sand be dissolved in water completely, and the liquid material that is dissolved with sodium oxide molybdena presents dark-brown, has a strong impact on the judgement of titration end-point, makes detected sodium oxide content error large, poor reproducibility.Therefore how to measure more accurately Na in reclaimed sand
2the content of O, to determine whether reclaimed sand can be reused for foundry production and become and have problem to be solved.
Summary of the invention
The invention provides the assay method of sodium oxide content in a kind of reclaimed sand of sodium silicate sand, can the reclaimed sand of Accurate Determining sodium silicate sand in sodium oxide content, for can reclaimed sand re-use, provide data accurately.
The assay method of sodium oxide content in the reclaimed sand of sodium silicate sand provided by the invention, comprises the following steps:
1) with magnet, the iron filings that mix in reclaimed sand are removed;
2) in the reclaimed sand that is G to the quality of removing iron filings, adding water and volume is V
2, concentration is
sulfuric acid standard solution after add thermal agitation; Control temperature within the scope of 75 ℃～90 ℃, continuous heating stirs 28～40min, is cooled to room temperature, obtains after filtration filter residue and filtrate; The addition of above-mentioned sulfuric acid standard solution is controlled as making sodium oxide molybdena stripping in reclaimed sand and by under the prerequisite of complete reaction and excessive;
3) filter residue step 2 being obtained washes with water, until cleansing solution is neutral, the filtrate that merges described cleansing solution and step 2 obtains test solution to be measured;
4) in the test solution to be measured obtaining to step 3, adding bromcresol green-methyl red mixed indicator, is C by concentration
1standard solution of sodium hydroxide be titrated to test solution and from redness, become green and be terminal, record the volume of the standard solution of sodium hydroxide that titration process consumes, be designated as V
1;
5) calculate as follows the percentage composition of sodium oxide molybdena:
In formula: the quality of G-reclaimed sand, unit is g; c
1-Concentration of Sodium Hydroxide Solution Standard, unit is mol/L; V
1the volume of the standard solution of sodium hydroxide consuming during-titration, unit is mL; c
2pH in-sulfuric acid standard solution, unit is mol/L; V
2the volume of-sulfuric acid standard solution, unit is mL; The molal weight of 61.98-sodium oxide molybdena, unit is g/mol.
The present invention has adopted back titration method to measure sodium oxide content in reclaimed sand,, sodium oxide molybdena stripping by under the prerequisite that adding, sulfuric acid neutralized completely in guaranteeing reclaimed sand, control excess sulfuric acid, again with alkali lye (NaOH) back titration, by obtaining sodium oxide content in reclaimed sand to being neutralized the Accurate Measurement of sulfuric acid.The control of terminal is more prone to grasp, and is more conducive to improve the accuracy of measurement result than prior art.So it is one of key of the present invention that control institute adds sulfuric acid standard solution excessive.In concrete operations, can first to sodium oxide content in reclaimed sand, do Preliminary Determination, determine on this basis the suitable addition of sulfuric acid standard solution, this operation is very simple for those skilled in the art.
In an embodiment of the present invention, for reducing to greatest extent the systematic error of buret or due to the accidental error of the too small substitution of reading, preferably control volume for the standard solution of sodium hydroxide of the sulfuric acid standard solution of overtitration at 20～35mL.
According to the regeneration technology of the reclaimed sand of sodium silicate sand, in the reclaimed sand of general sodium silicate sand, the mass percent of sodium oxide molybdena is below 1.0%, so, can be in above-mentioned general reclaimed sand on the content range basis of sodium oxide molybdena, according to the weight of reclaimed sand, and for concentration and the volume of the standard solution of sodium hydroxide of titration, determine the volume of the excess sulfuric acid standard solution that adds.
Further preferred working concentration is that the excess sulfuric acid standard solution that the standard solution of sodium hydroxide of 0.2mol/L left and right is 0.5mol/L left and right to concentration carries out titration.
For guaranteeing the accurate of measurement result, sulfuric acid standard solution used and standard solution of sodium hydroxide should be demarcated once for every two months, or demarcate before each use, its preparation and calibration process are pressed the preparation > > regulation of GB/T601 < < chemical reagent standard titration solution and are carried out.
According to assay method of the present invention, reclaimed sand is implemented to add in water and sulfuric acid standard solution system, is beneficial to stripping and the reaction of sodium oxide molybdena, in one embodiment of the invention, can control heating-up temperature within the scope of 80 ℃～90 ℃, continuous heating stirs 28～40min.Favourable operation is that heating, whipping process control stirring rate is ascending gradually, when preventing that liquid from spattering outward, sand is all stirred.Above-mentionedly add thermal agitation and can use suitable stirrer, for example, can use magnetic force heating stirrer to complete.
In step 3, the washing of filter residue is required fully, with cleansing solution, reaching neutrality is as the criterion, from washing completely and being beneficial to follow-up titration operation, consider, preferably, in step 3, filter residue water is carried out to 5 above washings, the volume of each washing filter residue institute water and the weight ratio of reclaimed sand are 1:3-5, and unit is ml/g.The filtrate of collected cleansing solution and step 2 is merged as test solution to be determined.
Further; in order to make the change color of titration end-point obvious; the present invention uses the narrower mixed indicator of color change interval: methyl red and bromcresol green mixed indicator; collocation method is as follows: solution I; take 0.1g bromcresol green; after dissolving with a small amount of 95% (v/v) ethanol, then use 95% (v/v) ethanol to be settled to 100mL; Solution II, takes 0.2g methyl red, after the dissolving with a small amount of 95% (v/v) ethanol, then uses 95% (v/v) ethanol to be settled to 100mL; Get 3 parts of solution I and 1 part of solution II, mix.
The beneficial effect of the assay method of sodium oxide content in reclaimed sand provided by the invention:
(1) add after water and excessive sour standard solution, adding the reclaimed sand of processing sodium silicate under the condition of thermal agitation, both can effectively avoid reclaimed sand because of the inhomogeneous bumping that occurs that is heated, can impel again fully contacting of reclaimed sand surface and standard sulfuric acid solution, promote fully carrying out of acid-base reaction, thereby remaining sodium oxide molybdena is dissolved and react more complete, the accuracy of testing result is high, favorable reproducibility.
(2) use chemical back titration, measure the content of sodium oxide molybdena in the reclaimed sand of sodium silicate sand by the sulfuric acid standard solution with standard solution of sodium hydroxide overtitration, detection scheme rationally and science.
(3) method of sodium oxide content in the reclaimed sand that prior art provides, in the filtrate that separated filter residue obtains after reclaimed sand adds water boil, directly with acidometric titration, detect sodium oxide content in reclaimed sand, to make indicator with methyl red, its titration end-point can be covered by the color of filtrate, terminal colour is changed not obvious, directly affect measurement result and accuracy.This method is selected compound indicator, makes terminal be easy to observe and grasp, thereby guarantees the accuracy of testing result.
(4) in following examples, use recovery of standard addition method can find out the checking of the inventive method, in the reclaimed sand that the inventive method is measured, the content accuracy of sodium oxide molybdena is high, favorable reproducibility, can provide data accurately for can judgement reclaimed sand re-use.
Embodiment
Below in conjunction with the drawings and specific embodiments, further illustrate the technical scheme of the embodiment of the present invention.
Embodiment 1
One, use method of the present invention to measure sodium oxide content in the reclaimed sand of sodium silicate sand, described reclaimed sand is processed and is obtained through regeneration for casting the old sand of generation as the molding sand of cementing agent for usining sodium silicate, according to experience or Preliminary Determination, in known reclaimed sand, the content of sodium oxide molybdena is below 1%.Take out 6 equal portions, to wherein 1 part measure according to the following steps:
1) with magnet, the iron filings that mix in reclaimed sand are removed;
2) reclaimed sand that is 10g by the quality of removing iron filings is placed in beaker, and adding water and volume is 10ml, after the sulfuric acid standard solution that concentration is 0.5872mol/L, adds thermal agitation on magnetic stirring apparatus; At heating whipping process, control stirring rate ascending gradually, when preventing that liquid from spattering outward, sand is all stirred; And when fluid temperature rises to 75 ℃ in beaker, start timing, control temperature within the scope of 75 ℃～90 ℃, continuous heating stirs 40min to be stopped, and is cooled to room temperature, obtains after filtration filter residue and filtrate;
3) the filter residue water obtaining of step 2 is carried out to 6 times and wash above and collect cleansing solution, until the cleansing solution reclaiming is neutral, the filtrate that merges all cleansing solutions and step 2 obtains for carrying out the test solution of titration; The volume of washing filter residue institute water and the weight ratio of reclaimed sand are 1:3(ml/g at every turn).
4) in the test solution obtaining to step 3, add 8～10 bromocresol green-methyl red indicators, with the standard solution of sodium hydroxide that concentration is 0.1969mol/L, be titrated to test solution and from redness, become green and be terminal, the volume of the standard solution of sodium hydroxide consuming during titration is 24.25ml;
5) result is calculated
By the volume of the standard solution of sodium hydroxide of above-mentioned use and sulfuric acid standard solution and the following formula of concentration substitution, calculate the percentage composition of sodium oxide molybdena:
In formula: the quality of G-reclaimed sand (g); c
1-Concentration of Sodium Hydroxide Solution Standard (mol/L) V
1the volume of the standard solution of sodium hydroxide consuming during-titration (mL); c
2pH in-sulfuric acid standard solution (mol/L); The volume of 10-sulfuric acid standard solution (mL); The molal weight of 61.98-sodium oxide molybdena (g/mol).
Two, accuracy in detection checking
By measuring the accuracy of the method validation detection method of the present invention of recovery of standard addition.Get above-mentioned remaining 5 parts of reclaimed sands (label 1-5), every part of 10g, the standard oxidation sodium sample to adding 20mg in every part of reclaimed sand of removing after iron filings, is used method of the present invention to carry out the mensuration of recovery of standard addition, and its measurement result is as shown in table 1.
Table 1
Accuracy test result
By mark-on recovery test data, can find out, in the reclaimed sand that use the inventive method records, the accuracy of sodium oxide content is high, reproducible, for judging whether reclaimed sand can be reused for foundry production data are accurately provided.
Embodiment 2
One, use method of the present invention to measure sodium oxide content in the reclaimed sand of sodium silicate sand, described reclaimed sand is processed and is obtained through regeneration for casting the old sand of generation as the molding sand of cementing agent for usining sodium silicate, according to experience or Preliminary Determination, in known reclaimed sand, the content of sodium oxide molybdena is below 1%, take out 6 equal portions, to wherein 1 part measure according to the following steps:
1) with magnet, the iron filings that mix in reclaimed sand are removed;
2) reclaimed sand that is 10g by the quality of removing iron filings is placed in beaker, and adding water and volume is 10ml, after the sulfuric acid standard solution that concentration is 0.5024mol/L, adds thermal agitation on magnetic stirring apparatus; At heating whipping process, control stirring rate ascending gradually, when preventing that liquid from spattering outward, sand is all stirred; And when fluid temperature rises to 80 ℃ in beaker, start timing, control temperature within the scope of 80 ℃～90 ℃, continuous heating stirs 30min to be stopped, and is cooled to room temperature, obtains after filtration filter residue and filtrate;
3) the filter residue water obtaining of step 2 is carried out to 5 times and wash above and collect filtrate, until the cleansing solution reclaiming is neutral, the filtrate that merges all cleansing solutions and step 2 obtains for carrying out the test solution of titration; The volume of washing filter residue institute water and the weight ratio of reclaimed sand are 1:4(ml/g at every turn).
4) in the test solution obtaining to step 3, add 8～10 bromocresol green-methyl red indicators, with the standard solution of sodium hydroxide that concentration is 0.2028mol/L, be titrated to test solution and from redness, become green and be terminal, the volume of the standard solution of sodium hydroxide consuming during titration is 19.84ml;
5) result is calculated
By the volume of the standard solution of sodium hydroxide of above-mentioned use and sulfuric acid standard solution and the following formula of concentration substitution, calculate the percentage composition of sodium oxide molybdena:
In formula: the quality of G-reclaimed sand (g); c
1-Concentration of Sodium Hydroxide Solution Standard (mol/L) V
1the volume of the standard solution of sodium hydroxide consuming during-titration (mL); c
2pH in-sulfuric acid standard solution (mol/L); The volume of 10-sulfuric acid standard solution (mL); The molal weight of 61.98-sodium oxide molybdena (g/mol).
Two, accuracy in detection checking
By measuring the accuracy of the method validation detection method of the present invention of recovery of standard addition.Get above-mentioned remaining 5 parts of reclaimed sands (label 1-5), every part of 10g, the standard oxidation sodium sample to adding 20mg in every part of reclaimed sand of removing after iron filings, is used method of the present invention to carry out the mensuration of recovery of standard addition, and its measurement result is as shown in table 2.
Table 2
Accuracy test result
By mark-on recovery test data, can find out, in the reclaimed sand sample that use the inventive method records, the accuracy of sodium oxide content is high, reproducible, for judging whether reclaimed sand can be reused for foundry production data are accurately provided.
Although the present invention discloses as above with embodiment; but it is not in order to limit the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; can change arbitrarily or be equal to replacement, therefore the scope that protection scope of the present invention should be defined with the application's claims is as the criterion.
Claims (5)
1. an assay method for sodium oxide content in the reclaimed sand of sodium silicate sand, is characterized in that, comprises the following steps:
1) with magnet, the iron filings that mix in reclaimed sand are removed;
2) in the reclaimed sand that is G to the quality of removing iron filings, adding water and volume is V
2, concentration is
sulfuric acid standard solution after add thermal agitation; Control temperature within the scope of 75 ℃～90 ℃, continuous heating stirs 28～40min, is cooled to room temperature, obtains after filtration filter residue and filtrate; The addition of above-mentioned sulfuric acid standard solution is controlled as making sodium oxide molybdena stripping in reclaimed sand and by under the prerequisite of complete reaction and excessive;
3) filter residue step 2 being obtained washes with water, until cleansing solution is neutral, the filtrate that merges described cleansing solution and step 2 obtains test solution to be measured;
4) in the test solution to be measured obtaining to step 3, adding bromcresol green-methyl red mixed indicator, is c by concentration
1standard solution of sodium hydroxide be titrated to test solution and from redness, become green and be terminal, record the volume of the standard solution of sodium hydroxide that titration process consumes, be designated as V
1;
5) calculate as follows the percentage composition of sodium oxide molybdena:
In formula: the quality of G-reclaimed sand, unit is g; c
1-Concentration of Sodium Hydroxide Solution Standard, unit is mol/L; V
1the volume of the standard solution of sodium hydroxide consuming during-titration, unit is mL; c
2pH in-sulfuric acid standard solution, unit is mol/L; V
2the volume of-sulfuric acid standard solution, unit is mL; The molal weight of 61.98-sodium oxide molybdena, unit is g/mol; Described bromcresol green-methyl red mixed indicator is prepared by the following method: solution I, take 0.1g bromcresol green, and after the dissolving with a small amount of 95% (v/v) ethanol, then use 95% (v/v) ethanol to be settled to 100mL; Solution II, takes 0.2g methyl red, after the dissolving with a small amount of 95% (v/v) ethanol, then uses 95% (v/v) ethanol to be settled to 100mL; Get 3 parts of solution I and 1 part of solution II, mix.
2. method according to claim 1, is characterized in that, controls the volume of the standard solution of sodium hydroxide that is used for titration between 20～35mL.
3. method according to claim 2, is characterized in that, the concentration of standard solution of sodium hydroxide is 0.15-0.25mol/L, and the concentration of sulfuric acid standard solution is 0.45-0.60mol/L.
4. according to the method described in claim 1-3 any one, it is characterized in that, in step 2, control temperature within the scope of 80 ℃～90 ℃, continuous heating stirs 28～40min.
5. according to the method described in claim 1-3 any one, it is characterized in that, in step 3, filter residue water is carried out to 5 above washings, wash the volume of filter residue institute water and the weight ratio of reclaimed sand is 1:3-5 at every turn, unit is ml/g.
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| CN111024684A (en) * | 2018-10-10 | 2020-04-17 | 中国石油化工股份有限公司 | SiO in white carbon black emulsion polymerized butadiene styrene rubber2Content determination method |
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| CN101113956A (en) * | 2006-07-24 | 2008-01-30 | 中国南车集团戚墅堰机车车辆厂 | Method for measuring natron sodium oxide content in used sand or reclaimed sand of sodium silicate sand |
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