A device and method for quickly detecting active calcium oxide in lime

Abstract

The invention discloses a device for rapidly detecting active calcium oxide in lime, comprising a container, a high-precision alkaline pH electrode, a temperature sensor, a stirrer, a data acquisition and processing device, and a host computer, wherein the high-precision alkaline pH electrode and the temperature sensor are electrically connected to the host computer via the data acquisition and processing device. A method for rapidly detecting active calcium oxide in lime is also disclosed. The invention can effectively avoid the influence of raw calcium carbonate and overburned calcium oxide, and can accurately calculate the content of active calcium oxide in lime by directly detecting the pH value of an alkaline solution generated by the reaction of active calcium oxide with water, and has a wide range of applications, is simple to operate, accurate and efficient, and is applicable to limes of various activity levels.

Description

Technical Field

[0001] The invention relates to a device and a method for quickly detecting active calcium oxide in lime. Background Art

[0002] Lime is a widely used chemical raw material, widely used in iron and steel metallurgy, alkali making, papermaking, medicine, agriculture, environmental protection, calcium carbide and other fields. The calcium oxide in lime is divided into two parts, one part is active calcium oxide, which can react with water to form calcium hydroxide. The other part is overburned inactive calcium oxide, which is not easy to react with water under certain conditions. The content of active calcium oxide is directly related to the performance of lime, and it is also one of the important indicators for testing the quality of lime. However, the existing detection methods are not only cumbersome to operate, but also have large errors in the detection data, and cannot accurately characterize the content of active calcium oxide.

[0003] Publication No. CN113979652A discloses a device and method for quickly judging the activity of quicklime at a sintering site: two cans of tap water are filled in a standard container and poured into a reaction container, and then a can of quicklime is filled in a standard container and slowly poured into the water, so that a hydration reaction occurs and bubbles are generated. The activity of the quicklime can be quickly judged by observing the reaction of the bubbles. This method can only judge the activity of the lime by observing the hydration reaction phenomenon and the experience of the tester, which has a large error and cannot be quantified.

[0004] Patent No. CN102798694B discloses a method and device for automatically testing lime activity by titration: using the acid-base titration method, the crushed and screened 1-5 mm sample is added to water for digestion, and titrated with 4 mol / l hydrochloric acid. The number of milliliters of hydrochloric acid consumed is the activity of the tested lime. The detection method disclosed in this patent only uses the number of milliliters of hydrochloric acid consumed to represent the activity of lime, and cannot effectively characterize the active calcium oxide content. This method will screen out lime below 1 mm, so it cannot reflect the activity of all calcium oxide. Moreover, although the inactivated calcium oxide does not react with water, it is easy to react with acid to cause detection errors.

[0005] Patent No. CN103869042B discloses a detection device and control method for intelligent lime activity by acid-base neutralization titration: lime is digested with water to produce calcium hydroxide, the pH of the digestate is detected by a pH meter, and then the equipment is titrated with 3.5-4.5 mol / l hydrochloric acid, and the titration results of 5min and 10min are recorded. The detection method disclosed in this patent still belongs to the acid-base titration method, and the activity of lime is expressed by the number of milliliters of hydrochloric acid consumed, which cannot characterize the active calcium oxide content in the lime. It is still necessary to screen out lime below 1mm, so it also cannot reflect the activity of calcium oxide in all limes. Moreover, although the inactivated calcium oxide does not react with water, it is easy to react with acid to cause detection errors. Summary of the invention

[0006] The purpose of the present invention is to provide a device and method for quickly detecting active calcium oxide in lime, which makes full use of the principle that active calcium oxide in lime is digested with water to generate calcium hydroxide slightly soluble in water, reacts active calcium oxide in lime with water and completely dissolves it in excess water to form a calcium hydroxide solution, and the pH value of the solution changes with the content of active calcium oxide in lime. The pH value and temperature of the solution are accurately detected by the high-precision alkaline pH electrode and temperature sensor of the detection device, and then the content of active calcium oxide in lime is calculated by the built-in program according to the negative logarithm pKw of the ion product constant of the solution pH value and the corresponding temperature.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The invention discloses a device for rapidly detecting active calcium oxide in lime, comprising a container, a high-precision alkaline pH electrode, a temperature sensor, a stirrer, a data acquisition and processing device and a host computer. The high-precision alkaline pH electrode and the temperature sensor are electrically connected to the host computer via the data acquisition and processing device.

[0009] Furthermore, the accuracy of the temperature sensor is 0.1°C.

[0010] Furthermore, the accuracy of the high-precision alkaline pH electrode is 0.001.

[0011] A method for rapidly detecting active calcium oxide in lime, comprising:

[0012] (1) Sample weighing and sample preparation

[0013] Mix the sample thoroughly and evenly, weigh the sample, grind it to make it pass through a standard sieve with an aperture of 0.074mm, mix it thoroughly and evenly, put it into a sample bottle, and store it in a drying dish for later use; boil the deionized water to expel CO2 and then cool it for later use. The deionized water used in the test is all deionized water that has been deionized without CO2;

[0014] (5) Digestion and dissolution of activated calcium oxide

[0015] Weigh the lime sample and add it into the deionized water without CO2 in the container, stir it at a temperature of 20℃ to 50℃ to make the active calcium oxide completely digested and dissolved in the water;

[0016] (6) Detection

[0017] After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted into the solution, and the data acquisition and processing equipment calculated the pH value of the solution based on the collected solution pH and temperature;

[0018] (7) Calculation and display

[0019] The host computer receives the solution pH value and temperature data from the data acquisition and processing equipment every 1 minute, and then the program's built-in calculation model calculates the negative logarithm pK of the ion product constant of water under the corresponding temperature conditions. w , and then according to the solution pH and pK w The active calcium oxide content of the lime is calculated by the calculation model of the active calcium oxide content of the lime and displayed on the output interface; if the active calcium oxide content of the lime changes within 0.5 for three consecutive times, the detection is judged to be completed, and the average of these three readings is taken as the active calcium oxide content of the lime and output on the display interface.

[0020] Furthermore, the calculation model is:

[0021] K w =(0.005T 4 -0.03T 3 +9T 2 +77T+1247)×10 -18

[0022] pK w =-lg(K w )

[0023] Where: K w — ionic product of aqueous solution;

[0024] T—solution temperature;

[0025] pK w —The negative logarithm of the ion product constant of the aqueous solution;

[0026] w (活性CaO) =7000×10 pH-pKw %

[0027] Where: w (活性CaO) —Active calcium oxide content in lime, %;

[0028] pH—pH value of solution;

[0029] p Kw —The negative logarithm of the ionic product constant of an aqueous solution.

[0030] Compared with the prior art, the beneficial technical effects of the present invention are:

[0031] The invention can effectively avoid the influence of raw calcium carbonate and overburned calcium oxide, and can accurately calculate the content of active calcium oxide in lime by directly detecting the pH value of the alkaline solution generated by the reaction of active calcium oxide and water. The invention has a wide application range, is simple to operate, accurate and efficient, and is applicable to limes of various activity degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] Figure 1 It is a rapid detection device for active calcium oxide content in lime;

[0034] Explanation of the accompanying drawings: 1. container; 2. high-precision alkaline pH electrode; 3. temperature sensor; 4. data acquisition and processing equipment; 5. host computer; 6. agitator. DETAILED DESCRIPTION

[0035] The lime active calcium oxide rapid detection device of the present invention is composed of a high-precision alkaline pH electrode (accuracy 0.001), a temperature sensor (accuracy 0.1°C), a stirrer, a data acquisition and processing device, and a host computer. The built-in program of the host computer includes the negative logarithm pK of the ion product constant corresponding to the temperature of the solution. w The calculation model and the calculation model of the content of active calcium oxide in lime are:

[0036] K w =(0.005T 4 -0.03T 3 +9T 2 +77T+1247)×10 -18 (1)

[0037] pK w =-lg(K w ) (2)

[0038] Where: K w —Ionic product of aqueous solution

[0039] T—Solution temperature

[0040] pK w —Negative logarithm of the ionic product constant of the aqueous solution

[0041] w (活性CaO) =7000×10 pH-pKw % (3)

[0042] Where: w (活性CaO) —Active calcium oxide content in lime, %

[0043] pH—pH value of the solution

[0044] p Kw —Negative logarithm of the ionic product constant of the aqueous solution

[0045] The specific operations are as follows:

[0046] (1) Sample weighing and sample preparation. Mix the sample thoroughly, weigh 10g of the sample, grind it so that it passes through a standard sieve with an aperture of 0.074mm, mix it thoroughly, put it into a sample bottle, and store it in a drying dish for later use. Boil the deionized water to remove CO2 and then cool it for later use. The deionized water used in the test is all deionized water that has been deionized without CO2.

[0047] (2) Digestion and dissolution of active calcium oxide. Weigh 0.2±0.001g of lime sample and add it to 500ml of deionized water without CO2. Stir at a temperature of 20℃ to 50℃ to allow all active calcium oxide to be digested and dissolved in the water.

[0048] (3) Detection

[0049] After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted into the solution, and the data acquisition and processing equipment calculated the pH value of the solution based on the collected solution pH and temperature.

[0050] (4) Calculation and display. The host computer receives the solution pH value and temperature data from the data acquisition and processing equipment every 1 minute, and then uses the built-in calculation model of the program to calculate the negative logarithm pK of the ion product constant of water under the corresponding temperature conditions. w , and then according to the solution pH and pK w The active calcium oxide content of lime is calculated by the calculation model of lime active calcium oxide content and displayed on the output interface. If the active calcium oxide content of three consecutive limes changes within the range of 0.5, the test is judged to be over, and the average of these three readings is taken as the active calcium oxide content of lime and output on the display interface.

[0051] The beneficial effects of the present invention are that the influence of raw calcium carbonate and overburned calcium oxide can be effectively avoided, and the content of active calcium oxide in lime can be accurately calculated by directly detecting the pH value of the alkaline solution generated by the reaction of active calcium oxide and water. The present invention has a wide range of applications, is simple to operate, accurate and efficient, and is applicable to limes of various activity levels.

[0052] The present invention has been verified by a large number of experiments in the laboratory, and the specific implementation method is as follows:

[0053] (1) Raw materials used in the implementation of the present invention

[0054] The raw material is high-activity lime prepared by calcining limestone at high temperature, with CaO content ≥90wt%, MgO ≤2wt%, and SiO2 ≤4wt%.

[0055] (2) Apparatus used in the implementation of the present invention

[0056] High-precision electronic balance, 1000ml beaker, 500ml volumetric flask, cantilevered power-boosting mixer, lime active calcium oxide rapid detection device, etc.

[0057] (3) The chemical formula used in calculating the active calcium oxide content of the present invention is:

[0058] CaO+H2O=Ca(OH)2

[0059] Example 1

[0060] (1) Use the quartering method or a divider to reduce the sample to about 10 g. Grind it so that it all passes through a square sieve with a pore size of 0.074 mm. Mix it thoroughly and put it into a sample bottle. Store it in a desiccator for later use.

[0061] (2) Boil deionized water for 20 minutes to remove CO2 and then cool for later use.

[0062] (3) Add 500 ml of deionized water without CO2 to a 1000 ml beaker at 20 °C and start stirring at 500 r / min.

[0063] (4) Weigh 0.2 g of quicklime sample and add it to 500 ml of deionized water free of CO2;

[0064] (5) After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted. The test was completed after 5 minutes, showing that the active calcium oxide content was 91.89%.

[0065] Example 2

[0066] (1) Use the quartering method or a divider to reduce the sample to about 10 g. Grind it so that it all passes through a square sieve with a pore size of 0.074 mm. Mix it thoroughly and put it into a sample bottle. Store it in a desiccator for later use.

[0067] (2) Boil deionized water for 20 minutes to remove CO2 and then cool for later use.

[0068] (3) Add 500 ml of deionized water without CO2 to a 1000 ml beaker at 30 °C and start stirring at 500 r / min.

[0069] (4) Weigh 0.2 g of quicklime sample and add it to 500 ml of deionized water free of CO2;

[0070] (5) After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted. The test was completed after 3 minutes, showing that the active calcium oxide content was 92.31%.

[0071] Example 3

[0072] (1) Use the quartering method or a divider to reduce the sample to about 10 g. Grind it so that it all passes through a square sieve with a pore size of 0.074 mm. Mix it thoroughly and put it into a sample bottle. Store it in a desiccator for later use.

[0073] (2) Boil deionized water for 20 minutes to remove CO2 and then cool for later use.

[0074] (3) Add 500 ml of deionized water without CO2 to a 1000 ml beaker at 40 °C and start stirring at 500 r / min.

[0075] (4) Weigh 0.2 g of quicklime sample and add it to 500 ml of deionized water free of CO2;

[0076] (5) After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted. The test was completed after 5 minutes, showing that the active calcium oxide content was 91.64%.

[0077] Example 4

[0078] (1) Use the quartering method or a divider to reduce the sample to about 10 g. Grind it so that it all passes through a square sieve with a pore size of 0.074 mm. Mix it thoroughly and put it into a sample bottle. Store it in a desiccator for later use.

[0079] (2) Boil deionized water for 20 minutes to remove CO2 and then cool for later use.

[0080] (3) Add 500 ml of deionized water without CO2 to a 1000 ml beaker, the water temperature is 50 °C, and stirring is started at a speed of 500 r / min;

[0081] (4) Weigh 0.2 g of quicklime sample and add it to 500 ml of deionized water free of CO2;

[0082] (5) After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted. The test was completed after 4 minutes, showing that the active calcium oxide content was 92.14%.

[0083] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for quickly detecting active calcium oxide in lime, characterized in that: The invention comprises a device for rapidly detecting active calcium oxide in lime, the device comprising a container, a high-precision alkaline pH electrode, a temperature sensor, a stirrer, a data acquisition and processing device and a host computer, wherein the high-precision alkaline pH electrode and the temperature sensor are electrically connected to the host computer via the data acquisition and processing device; The methods specifically include: (1) Sample weighing and sample preparation Mix the sample thoroughly and evenly, weigh the sample, grind it to make it pass through a standard sieve with an aperture of 0.074mm, mix it thoroughly and evenly, put it into a sample bottle, and store it in a drying dish for later use; boil the deionized water to expel CO2 and then cool it for later use. The deionized water used in the test is all deionized water that has been deionized without CO2; (2) Digestion and dissolution of activated calcium oxide Weigh the lime sample and add it into the deionized water without CO2 in the container, stir it at a temperature of 20℃~50℃ to make the active calcium oxide completely digested and dissolved in the water; (3) Detection After stirring for 20 minutes, a high-precision alkaline pH electrode and a temperature sensor were inserted into the solution, and the data acquisition and processing equipment calculated the pH value of the solution based on the collected solution pH and temperature; (4) Calculation and display The host computer receives the solution pH value and temperature data from the data acquisition and processing equipment every 1 minute, and then the program's built-in calculation model calculates the negative logarithm pK of the ion product constant of water under the corresponding temperature conditions. w , and then according to the solution pH and pK w The active calcium oxide content of the lime is calculated by the calculation model of the active calcium oxide content of the lime and displayed on the output interface; if the active calcium oxide content of three consecutive limes changes within the range of 0.5, the detection is judged to be over, and the average of these three readings is taken as the active calcium oxide content of the lime and output on the display interface; The calculation model is: K w =(0.005T 4 -0.03T 3 +9T 2 +77T+1247)×10 -18 pK w =-lg(K w ) Where: K w — ionic product of aqueous solution; T — solution temperature; pK w — negative logarithm of the ionic product constant of an aqueous solution; w (活性CaO) =7000×10 pH-pKw % Where: w (活性CaO) —Active calcium oxide content in lime, %; pH—pH value of solution; p Kw — The negative logarithm of the ionic product constant of an aqueous solution.

2. The method for rapid detection of lime active calcium oxide according to claim 1, characterized in that: The accuracy of the temperature sensor is 0.1°C.

3. The method for rapid detection of lime active calcium oxide according to claim 1, characterized in that: The accuracy of the high-precision alkaline pH electrode is 0.001.

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