Method for determining calcium fluoride, silicon dioxide, phosphorus and sulfur in calcite-containing fluorite ball

Abstract

The invention discloses a method for determining calcium fluoride, silicon dioxide, phosphorus and sulfur in a calcite-containing fluorite ball, which is an analysis method for determining the contents of calcium fluoride (CaF2), silicon dioxide (SiO2), phosphorus (P) and sulfur (S) in the calcite-containing fluorite ball by applying an X-ray fluorescence spectrometry based on a glass fuse piece. The method can realize simultaneous detection of multiple elements, is good in precision and accuracy, greatly improves the detection speed, effectively reduces errors caused by factors such as methods and personnel, and reduces harm to the environment to a certain extent.

Description

Technical Field

[0001] The invention belongs to the technical field of steel enterprise production, and specifically relates to a method for determining the contents of calcium fluoride, silicon dioxide, phosphorus and sulfur in fluorite balls containing calcite, and in particular to a method for determining the contents of calcium fluoride, silicon dioxide, phosphorus and sulfur in fluorite balls containing calcite by using a melting furnace molten sheet and an X-ray fluorescence spectrometry. Background Art

[0002] The main evaluation indicators of fluorite balls containing calcite are calcium fluoride, silicon dioxide, phosphorus and sulfur. Currently, chemical methods are used for determination: the content of calcium fluoride is determined by EDTA titration, namely GB / T 5195.1-2017 "Determination of calcium fluoride content in fluorite - EDTA titration method and distillation-potentiometric titration method"; the silicon molybdenum blue colorimetry or weight method is used to select an appropriate method for determination according to the silicon dioxide content, namely GB / T5195.8-2006 "Determination of silicon dioxide in fluorite"; the phosphorus content is determined by phosphomolybdenum blue phosphorus colorimetry, namely GB / T 5195.6-2017 "Determination of phosphorus content in fluorite - spectrophotometric method"; the sulfur content is determined by a tube furnace, namely GB / T 5195.5-2017 "Determination of total sulfur content in fluorite - tube furnace combustion-potassium iodate titration method".

[0003] The analysis of four elements requires five methods and four chemical inspectors. Moreover, these methods are cumbersome and have long analytical procedures. They require sample dissolution before determination, which places high demands on the skills of the operators. The EDTA titration method for calcium fluoride has a certain degree of human error in the determination of the color of the titration end point, which makes the determination accuracy poor. In addition, calcium fluoride is calculated by titrating the calcium content, and the conversion coefficient is large, which makes the repeatability of the determination results poor. The mass percentage of silicon dioxide is between 0.10% and 2.00%, and the silicon molybdenum blue spectrophotometry method is used. The mass percentage of silicon dioxide is between 0.10% and 2.00%. The content of silicon dioxide in the locally washed and processed fluorite balls is between 1.50% and 40.00%, and is determined by weight method. The mass percentage of silicon dioxide in the locally washed and processed fluorite balls is higher than 2.00% and lower than 2.00%, so sometimes both methods are needed to analyze the accurate content, resulting in a waste of personnel, time, medicines and other resources; the mass percentage of phosphorus in the locally washed and processed fluorite balls can reach 0.9%, while the upper limit of detection by the national standard method of chemical method is 0.5%; the sulfur element is determined using a tubular furnace, which is prone to uneven heating, difficult temperature adjustment, and short heating tube life.

[0004] In short, the traditional chemical method has a long operation cycle and requires the use of chemicals such as hydrochloric acid, acetic acid, hydrofluoric acid, potassium permanganate, and perchloric acid. Long-term use can easily cause potential harm to the human body and the environment. Therefore, it is necessary to invent an accurate and efficient detection method for the local calcite-containing fluorite balls. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a method more suitable for determining the content of calcium fluoride, silicon dioxide, phosphorus and sulfur in fluorite balls containing calcite produced locally. The method can directly determine the content of calcium fluoride, silicon dioxide, phosphorus and sulfur, eliminate the influence of calcium carbonate in calcite on calcium fluoride, and ensure that the platinum dish is not corroded. The operation time is short, the efficiency is high, and the precision and accuracy are good.

[0006] To solve the above problems, the method of the present invention comprises the following steps:

[0007] (1) The fluorite balls containing calcite are crushed and ground step by step to a suitable particle size using a jaw crusher, a hammer crusher, a vibration mill, etc., and then sieved until the particle size is less than 0.063 mm. The sample is required to be uniform and representative and dried in a drying oven at 105±5℃ for 2h in advance, placed in a desiccator, and cooled to room temperature as the sample to be tested;

[0008] (2) Weigh 0.6000g of the sample to be tested, accurate to 0.0001g. Place it in a 100mL beaker, add 10mL of calcium-containing acetic acid solution, heat to boil to drive out carbon dioxide, cool to room temperature, cover with blood, heat at about 90℃ for 3min, remove, and keep warm for 2min;

[0009] (3) Filter with medium-speed quantitative filter paper. Transfer all insoluble matter to the filter paper, wash the beaker with water 3 to 5 times, and wash the residue with water 7 to 8 times;

[0010] (4) Place the filter paper and the residue in a porcelain crucible, place it in a high-temperature muffle furnace at a temperature below 300°C, slowly raise the temperature to 850°C to burn carbon, take out the magnetic crucible, and cool it;

[0011] (5) Add 6.0000 g of a mixed solvent of lithium tetraborate and lithium metaborate in a mass ratio of 67:33, accurate to 0.0005 g, stir evenly, and transfer all of it to a platinum dish mold;

[0012] (6) Add 30% ammonium iodide solution to the sample surface as a release agent;

[0013] (7) Placing the platinum dish mold in a melting furnace for melting, taking out the glass melt after standing, swinging, and rotating for melting, shaking, cooling, and analyzing the formed glass melt. The surface is smooth and uniform without scratches, bubbles, and cracks. After cooling, the glass melt is coded and placed in a dryer to obtain a molten glass sheet as a sample to be tested; wherein: the melting temperature is 1000°C, the pre-melting time is 120s; the melting swing is 770s; and the glass melt is allowed to stand for 10s;

[0014] (8) Setting the relevant optimal parameters of the X-ray fluorescence spectrometer, analyzing the sample to be tested using the X-ray-fluorescence spectrometer, and obtaining the elemental analysis value according to the standard curve;

[0015] The preferred measuring instrument is MXF-2400 (Shimadzu Corporation, Japan); voltage 40KV; current 70mA;

[0016] PHA was determined to be CaF2: 20-130;

[0017] PHA is determined to be SiO2: 30-120;

[0018] PHA was determined as P: 40-85;

[0019] PHA is determined as S:40-100.

[0020] The analysis time was 40 s.

[0021] CaF2 analysis line: Ca Ka;

[0022] SiO2 analysis spectrum: Si Ka;

[0023] P analysis line: P Ka;

[0024] S analysis line: S Ka;

[0025] CaF2 spectroscopic crystal: LiF;

[0026] SiO2 spectroscopic crystal: PET;

[0027] P spectroscopic crystal: Ge;

[0028] S Spectroscopic crystal: NaCl.

[0029] In some implementations, it is required that there are no bubbles, unmelted small particles or other impurities inside the glass melt. After cooling, the glass melt is numbered with a marker or labeled (not on the surface to be tested) and placed in a dryer for testing.

[0030] In some embodiments, the correlation coefficient of the standard curve in step (8) is above 0.999.

[0031] In some embodiments, in step (8), the standard curve for obtaining the CaF2 content is Xi=0.305437li+1.333120; the standard curve for obtaining the SiO2 content is Xi=0.858987li-0.031237; the standard curve for obtaining the P content is Xi=0.128531li-0.031237; the standard curve for obtaining the S content is Xi=0.040434li-0.025948; wherein in each formula, li represents the component content; Xi represents the fluorescence intensity of the component.

[0032] In some embodiments, the measurement range of the standard curve is: CaF2: 65.00% to 95.00%; SiO2: 0.500% to 20.00%; P: 0.050% to 2.00%; S: 0.050% to 1.80%.

[0033] In some embodiments, the calcium-containing acetic acid solution in step (2) is prepared as follows: weigh 2.00 g of calcium carbonate into a 500 mL beaker, add 50 mL of (1+9) acetic acid ((1+9) acetic acid: prepared with glacial acetic acid with p=1.05 g / mL), transfer to a 1000 mL volumetric flask, dilute to the mark with acetic acid, and mix well.

[0034] In some embodiments, if the mass percentage of an element is ≥ 1.00%, the result is rounded to two decimal places and reported; if the mass percentage of an element is < 1.00%, the result is rounded to three decimal places and reported.

[0035] The method of the invention is simple to operate, has a short process, can measure multiple elements simultaneously, and has a fast analysis speed; the linear range of the standard curve is wide, and the linearity reaches above 0.999; for samples containing calcite, the influence of calcium carbonate can be effectively eliminated, and the content of calcium fluoride can be accurately measured; the phosphorus content of fluorite balls is relatively high, and the method of the invention is more suitable for local fluorite balls, which makes up for the blank that the phosphorus content exceeds the detection upper limit of the national standard method in the chemical analysis method and cannot accurately produce data; the molten glass sheet-X-ray fluorescence spectrometry is used to accurately measure the sulfur content in combination with the existence valence state of sulfur in the fluorite balls; the method has the advantages of good precision of the measurement result, high accuracy, and the like. DETAILED DESCRIPTION

[0036] (I) Sample preparation

[0037] The fluorite balls containing calcite are crushed and ground step by step to a suitable particle size using a jaw crusher, a hammer crusher, a vibration mill and other equipment, and then sieved until the particle size is less than 0.063 mm. The sample is required to be uniform and representative and is pre-dried in a drying oven at 105±5℃ for 2h, placed in a desiccator, and cooled to room temperature.

[0038] (II) Sample pretreatment

[0039] (1) Weigh an appropriate amount of sample and place it in a 100-mL beaker. Add 10 mL of calcium-containing acetic acid solution (weigh 2.00 g of calcium carbonate in a 500-mL beaker, add 50 mL of (1+9) acetic acid, transfer to a 1000-mL volumetric flask, dilute to the mark with acetic acid, and mix well). Cover with blood on the surface, heat at about 90°C for 3 min, remove, and keep warm for 2 min.

[0040] Note: Alternatively, place the sample in a 250mL beaker, add 10mL of calcium-containing acetic acid solution, cover with a watch glass, and place at room temperature for 30 minutes, shaking or stirring every 5 minutes.

[0041] (2) Filter with medium-speed quantitative filter paper. Transfer all insoluble matter to the filter paper, wash the beaker with water 3 to 5 times, and wash the residue with water 7 to 8 times.

[0042] (3) Place the filter paper and the residue in a porcelain crucible, place it in a high-temperature muffle furnace at a temperature below 300°C, slowly raise the temperature to 850°C to burn the carbon, take out the magnetic crucible, and cool it.

[0043] (III) Molten glass samples

[0044] (1) Add 6.0000 g (accurate to 0.0005 g) of a 67:33 mixed solvent of lithium tetraborate and lithium metaborate into a porcelain crucible, stir evenly, and then transfer all of the mixture into a platinum dish.

[0045] (2) Add 30% ammonium iodide solution as a release agent to the surface of the sample.

[0046] (3) Place in a fully automatic melting furnace for melting. Melting temperature is 1000°C, pre-melting is 120 seconds, melting swing is 770 seconds, and standing is 10 seconds.

[0047] (4) After melting, take out the platinum dish and shake it well, and cool the molten glass piece. Make sure that the analysis surface is smooth and representative of the entire sample, and there are no bubbles or unmelted small particles inside the glass piece. After cooling, write a number with a marker or label it (not the surface to be tested) and put it in a desiccator for testing.

[0048] (IV) Standard curve

[0049] (1) Accurately weigh more than 10 standard samples, and add potassium dihydrogen phosphate standard reagent to some of the standard samples to prepare self-made standard samples (ensuring that the total sample volume is 0.6000g, accurate to 0.0001g).

[0050] (2) According to technical contents (ii) and (iii), melt the glass flakes, measure on an X-ray fluorescence spectrometer, and draw a standard curve. The standard curve range of each element is CaF2: 65.00% to 95.00%; SiO2: 0.500% to 20.00%; P:

[0051] 0.050%~2.00%; S: 0.050%~1.80%.

[0052] (V) Optimizing instrument parameters

[0053] (1) The preferred melting furnace equipment is melting temperature: 1000°C.

[0054] (2) The preferred melting furnace instrument is as follows: melting time: pre-melting 120 s, melting swing 770 s, and standing 10 s.

[0055] (3) The preferred measuring instrument is MXF-2400 (Shimadzu Corporation, Japan): voltage 40KV; current 70mA.

[0056] (4) PHA is determined as CaF2: 20-130; SiO2: 30-120; P: 40-85; S: 40-100.

[0057] (5) Analysis time: 40 seconds.

[0058] The beneficial effects of the present invention are:

[0059] By adopting the above technical scheme, the present invention ensures the timeliness and accuracy of the analysis data, shortens the detection time limit, reduces the work intensity of employees, reduces the risk of employees suffering from occupational diseases, can analyze multiple elements at the same time, improves work efficiency, and compared with traditional chemical methods, can issue data in a timely and accurate manner to guide production. For the purchased calcite-containing fluorite ball materials, accurate and scientific data are issued to ensure objectivity and fairness during settlement. This technical method is easy to operate, uses fewer types of equipment, fewer types of reagents, fewer human factors, has stable data repeatability, good accuracy, can realize rapid determination of multiple elements, has good promotion value, and can be expanded to other similar varieties such as fluorite powder.

[0060] Example:

[0061] The present embodiment provides a method for accurately determining calcium fluoride, silicon dioxide, phosphorus and sulfur in fluorite balls containing calcite. Samples for daily analysis are selected for analysis. The main instrument used is the MXF-2400 of Shimadzu of Japan, and the melting furnace model is the TR-1000M of Haina Instruments. The results of chemical analysis of the sample are: CaF2: 81.82%; SiO2: 2.69%; P: 0.793%; S: 0.772%.

[0062] The specific operations are as follows:

[0063] 1) Use jaw crusher, hammer crusher, vibration mill and other equipment to crush and grind the 1# fluorite balls containing calcite to a suitable particle size, and then sieve until the particle size is less than 0.063mm. The sample is required to be uniform and representative and dried in a drying oven at 105±5℃ for 2h in advance, placed in a desiccator, and cooled to room temperature.

[0064] 2) Accurately weigh 0.6000g of 1# fluorite ball sample containing calcite to the nearest 0.0001g. Place it in a 100mL beaker, add 10mL of calcium-containing acetic acid solution, cover with blood, heat at about 90℃ for 3min, remove and keep warm for 2min.

[0065] 3) Filter with medium-speed quantitative filter paper. Transfer all insoluble matter to the filter paper, wash the beaker with water 3 to 5 times, and wash the residue with water 7 to 8 times.

[0066] 4) Place the filter paper and the residue in a porcelain crucible, place it in a high-temperature muffle furnace at below 300°C, and slowly heat it to 850°C.

[0067] Burn the carbon, take out the magnetic crucible and cool to room temperature.

[0068] 5) Add 6.0000 g of a mixed solvent of lithium tetraborate and lithium metaborate in a mass ratio of 67:33, accurate to 0.0005 g, stir evenly, and transfer all of it to a platinum dish mold.

[0069] 6) Add 21±1 drops of 30% ammonium iodide solution to the sample surface as a release agent.

[0070] 7) Place the platinum dish mold in a melting furnace for melting. After standing, shaking, and rotating to melt, take out the platinum dish, shake it evenly, and cool it. The resulting glass melt is smooth and uniform in surface analysis without scratches, bubbles, and cracks. After cooling, encode it and put it into a dryer to obtain a standard molten glass piece to be tested.

[0071] 8) The fully automatic melting furnace is the HNJC-L4E fully automatic glass melting furnace produced by Luoyang Haina Testing Instrument Co., Ltd. The parameters are shown in Table 1 below:

[0072] Table 1: Melting furnace equipment parameters

[0073]

[0074] 9) The melting temperature is set to 1000°C.

[0075] 10) The X-ray fluorescence spectrometer is preferably MXF-2400 produced by Shimadzu Corporation of Japan. The equipment parameters are shown in Table 2 below:

[0076] Table 2: X-ray fluorescence spectrometer operating parameters

[0077]

[0078]

[0079] 11) Use more than 10 fluorite certified standard substances and self-made standard substances to draw a standard curve, accurately weigh the standard sample and add a specific mass of high-purity potassium dihydrogen phosphate reference reagent (total mass is 0.6000g). Prepare a standard glass melt,

[0080] The intensity value is measured on the X-ray fluorescence spectrometer, and the standard curve is drawn with the percentage content of CaF2, SiO2, P, and S as the horizontal axis and the intensity value as the vertical axis. The content of each analyzed element in the standard curve should have an appropriate gradient. The standard curve is:

[0081] Xi=b*li+a (li: component content; Xi: fluorescence intensity of component; a, b: coefficients), the standard curve is shown in Table 3 below.

[0082] Table 3: Standard curve statistics

[0083] Component name Standard curve equation Correlation coefficient Measuring range (%) <![CDATA[CaF2]]> Xi=0.305437li+1.333120 1.0000 65.00～95.00 <![CDATA[SiO2]]> Xi=0.858987li-0.031237 0.9999 0.50～20.00 P Xi=0.128531li-0.031237 1.0000 0.050～2.00 S Xi=0.040434li-0.025948 0.9999 0.050～1.80

[0084] Note: Where, li: component content; Xi: fluorescence intensity of component;

[0085] 12) The fluorite standard sample QD19-272 was added with potassium dihydrogen phosphate to prepare a glass melt with a content close to that of the sample as a control sample and 1# fluorite ball containing calcite, and the glass melt was measured on an X-ray fluorescence spectrometer. The content of each element in the corresponding sample was calculated on the standard curve according to the intensity value of the sample.

[0086] 13) The results of CaF2, SiO2, P, and S are the measurement results of the sample.

[0087] 14) The analysis results were rounded according to GB / T 8170-2008 "Rule for rounding off numbers and expression and determination of limit values", and the element mass percentage results ≥1.00 were rounded to two decimal places, and the element mass percentage results <1.00 were rounded to three decimal places. The results are shown in Table 4 below:

[0088] Table 4: Statistical table of measurement results

[0089]

[0090] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining calcium fluoride, silicon dioxide, phosphorus and sulfur in fluorite balls containing calcite, comprising the following steps: (1) crushing and grinding fluorite balls containing calcite to a suitable particle size, drying them in a drying oven, placing them in a desiccator, and cooling them to room temperature to serve as the sample to be tested; (2) Weigh an appropriate amount of the sample to be tested, place it in a beaker, add a certain amount of calcium-containing acetic acid solution, cover the surface with blood, heat at low temperature, and stir evenly; (3) Filter through filter paper, transfer all insoluble matter to the filter paper, and wash the beaker and residue with water; (4) placing the filter paper and the residue in a porcelain crucible, ashing and burning in a high-temperature muffle furnace, taking out the porcelain crucible, and cooling; (5) Add a specific mass of mixed flux into the porcelain crucible, stir evenly, and transfer all of it into the platinum dish mold; (6) Adding a release agent dropwise into the platinum dish mold; (7) Placing the platinum dish mold in a fully automatic melting furnace for melting, pre-melting, shaking, rotating melting, standing, taking out, shaking, and cooling to form a glass melt as a sample to be tested; (8) Setting the relevant optimal parameters of the X-ray fluorescence spectrometer, analyzing the sample to be tested with the X-ray-fluorescence spectrometer, and obtaining the elemental analysis value according to the standard curve.

2. According to the determination method of claim 1, the amount of the sample to be tested accurately weighed in step (2) is 0.6000g (accurate to 0.0001g), the mass of the mixed flux added in step (5) is 6.000g (accurate to 0.0005g), and the mixed flux is lithium tetraborate (67%) + lithium metaborate (33%).

3. According to the determination method according to claim 1 or 2, the release agent in step (6) is an ammonium iodide solution, and optionally, the concentration of the ammonium iodide solution is 30%.

4. According to the determination method described in any one of claims 1 to 3, in step (7), the platinum dish mold is placed in a melting furnace at a melting temperature of 1000°C, the pre-melting time is 120 seconds, the melting swing time is 770 seconds, and after standing for 10 seconds, it is taken out, shaken, and cooled to form a glass melt.

5. According to the measuring method described in any one of claims 1 to 4, it is required that there are no bubbles, unmelted small particles and other impurities inside the glass melt. After cooling, write a number with a marker or label it (not the surface to be tested) and put it into a desiccator for testing.

6. The assay method according to any one of claims 1 to 5, wherein the correlation coefficient of the standard curve in step (8) is above 0.

999.

7. The determination method according to claim 6, in step (8), the standard curve for obtaining the CaF2 content is Xi=0.305437li+1.333120; the standard curve for obtaining the SiO2 content is Xi=0.858987li-0.031237; the standard curve for obtaining the P content is Xi=0.128531li-0.031237; the standard curve for obtaining the S content is Xi=0.040434li-0.025948; In each formula, li represents the content of the component; Xi represents the fluorescence intensity of the component.

8. The determination method according to claim 7, wherein the determination range of the standard curve is: CaF2: 65.00% to 95.00%; SiO2: 0.500% to 20.00%; P: 0.050% to 2.00%; S: 0.050% to 1.80%.

9. The determination method according to any one of claims 1 to 8, wherein the X-ray fluorescence spectrometer used in step (8) is MXF-2400 (Shimadzu Corporation, Japan), and the relevant parameters set are voltage 40KV; current 70mA; PHA is determined to be CaF2: 20-130; SiO2: 300-120; P：40-85； S: 40-100; analysis time is 40s.

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