A method for quickly and accurately characterizing the chemical reaction activity of milk of lime

Abstract

The scheme discloses a method for quickly and accurately characterizing the chemical reaction activity of milk of lime, and steps are as follows: A: pouring appropriate amount of water into a detection cup and a sample cup, opening a stop valve to make the liquid on both sides communicate, and making the liquid surface reach the upper edge of a communicating pipe and be flush with both sides; B: closing the stop valve and recording the initial conductivity value of the detection cup; C: using a sampling dropper to suck a little milk of lime to be measured and quickly dropping the milk of lime into the sample cup; meanwhile, opening the stop valve and a timer; D: recording the instantaneous conductivity of the liquid phase in the detection cup every other timing unit; E: continuously recording until the conductivity value tends to be stable, and the conductivity meter reading recording is ended after no obvious increase and decrease occurs; F: inputting data into a table to generate a diffusion conductivity-time curve, and characterizing and evaluating the activity of the milk of lime sample through the curve coverage area.

Description

Technical Field

[0001] This invention relates to the field of chemical detection, specifically a method for rapidly and accurately characterizing the chemical reactivity of lime slurry. Background Technology

[0002] Lime milk generally refers to a strongly alkaline suspension formed by dispersing calcium hydroxide in an aqueous phase. Due to its simple preparation, high base density, large acid-base neutralization specific volume, and excellent safety and environmental protection performance, it is widely used in many fields such as inorganic chemical material synthesis, waste treatment, emergency response to hazardous chemicals, soil remediation, restoration of cultural relics and historical sites, and medical and health care.

[0003] In numerous practical applications, it has been found that certain properties of lime slurry have a decisive impact on the effectiveness of downstream applications. For example, in wet desulfurization, the desulfurization efficiency of lime slurry obtained from different sources, manufacturers, or production processes varies significantly. Similarly, when different batches of lime slurry are carbonated to produce light calcium carbonate under the same process conditions, not only do reaction times often differ significantly, but the particle size, morphology, and dispersibility of the products also frequently exhibit unexpected "anomalies." The repeated occurrence of these anomalies in production applications indicates that it is difficult to explain or judge the performance of lime slurry using conventional physicochemical parameters such as purity, concentration, and alkalinity. A new physical parameter or concept is urgently needed to explain all of this.

[0004] As applied research deepened, the concept of lime slurry activity gradually took shape, and the aforementioned anomalous phenomena were well explained: high lime slurry activity leads to faster chemical reaction rates; for instantaneous reactions, more materials effectively participate in the reaction, resulting in shorter reaction times and improved raw material utilization. For the crystallization process of products such as calcium carbonate, reaction time and ion interface diffusion rates directly affect the microscopic morphology and spatial distribution of the products, thus influencing some macroscopic properties. Subsequently, based on this understanding of activity, several methods for determining lime slurry activity were developed.

[0005] Chinese patent document CN102928478A, published on December 12, 2013, discloses a "rapid method for determining the activity of lime slurry." This method uses a conductivity meter, placing the conductivity electrode and temperature sensor in a 600-800 ml beaker containing the lime slurry sample. 200-400 ml of deionized water is added to the beaker, and 2-5 ml of the lime slurry sample is quickly added using a small pipette or disposable sampling tube. The measurement temperature is controlled between 20-30℃, with a temperature error of ±1℃ for each measurement. A stopwatch is used to time the measurement, and a reading is taken at any point within a 10-30 second interval, recording the conductivity value. This type of technical solution (referred to as the direct conductivity measurement method) characterizes the activity of lime slurry using conductivity values. Its greatest advantage is its simplicity, ease of use, and speed.

[0006] With the development of practical applications in production, the inherent defects of the direct conductivity measurement method have gradually become apparent:

[0007] 1) Low test accuracy and poor practical guidance. Conductivity can only reflect the quantity or concentration of conductive ions released by a certain amount of lime slurry, and cannot fully reflect the activity of lime slurry. Industry professionals, including the inventor, generally believe that the evaluation of lime slurry activity should include at least four dimensions: dispersibility, solubility, ion capacity, and diffusion rate.

[0008] 2) The resistance to interference from impurity ions is weak, and the test values ​​are prone to inaccuracy or distortion. In industrial production, chemical reagents (producing conductive ions or groups) are often added during calcination or lime slaking to improve dispersion or increase conversion rate. Impurity ions directly contribute to the conductivity of lime slurry, but have no definite effect on the activity of lime slurry. Therefore, the conductivity method cannot meet the needs of blind testing.

[0009] The aforementioned deficiencies result in the limited theoretical predictive and practical guidance for determining the activity of lime slurry using existing technical methods, particularly regarding its application in related technologies and key chemical reaction processes. For example, in the production practice of synthesizing calcium carbonate via carbonation, highly active lime slurry selected based on conductivity values ​​using direct conductivity measurement exhibits "abnormal phenomena" under the same process conditions: long carbonation reaction time, low reaction rate, small specific surface area of ​​calcium carbonate, low sedimentation volume, and wide particle size distribution, which do not meet the expected carbonation results of highly active lime slurry. Summary of the Invention

[0010] Based on the above problems, this invention provides a method for rapidly and accurately characterizing the chemical reactivity of lime slurry, which solves the technical problems of low accuracy, poor anti-interference ability, lack of scientific theoretical support, and weak guidance for related technical application fields and major chemical reaction processes in production application scenarios under existing technical conditions.

[0011] To achieve the objective of this invention, the following technical solution is adopted: a method for rapidly and accurately characterizing the chemical reactivity of lime slurry.

[0012] The following equipment and materials were used:

[0013] Sample cup;

[0014] Test cup;

[0015] A connecting tube, which laterally connects the sample cup and the detection cup, serves as a liquid bridge;

[0016] water;

[0017] dropper;

[0018] A shut-off valve is installed on the connecting pipe;

[0019] Conductivity measuring instrument;

[0020] Timer;

[0021] The steps are as follows:

[0022] A: Pour an appropriate amount of water into the test cup and sample cup, open the shut-off valve to connect the liquids on both sides, until the liquid level is above the upper edge of the connecting tube and flush with both sides.

[0023] B: Close the shut-off valve and record the initial conductivity value σ0 of the detection cup;

[0024] C: Use a sampling dropper to take a small amount of the lime milk to be tested and quickly add it to the sample cup; at the same time, open the shut-off valve and the timer.

[0025] D: Record the instantaneous conductivity σ of the liquid phase in the test cup every time a timing unit is completed. i ;

[0026] E: Continue recording until the conductivity value stabilizes and does not increase or decrease significantly (±0.1μS / cm), then the conductivity meter reading recording ends;

[0027] F: Input the data into a table to generate a diffusion conductivity-time curve, and characterize and evaluate the activity of the lime milk sample by the curve coverage area.

[0028] Preferably, the sample cup and the test cup are of the same model and specifications.

[0029] Preferably, the connecting tube is a horizontally extending straight tube with a smooth inner wall, a length of 10-20 cm, and both ends extending into the center of the sample cup and the detection cup, respectively.

[0030] Preferably, the shut-off valve is located in the middle of the connecting pipe.

[0031] As a preferred option, the shut-off valve is a quick-opening shut-off valve.

[0032] Preferably, deionized water is used in step A.

[0033] Preferably, the electrodes of the conductivity meter are in close contact with the opening of the detection cup end of the connecting tube.

[0034] Preferably, before starting step B, the sample cup, the test cup, and the connecting tube are all placed in a water bath and kept at a constant temperature of 25℃±0.5℃.

[0035] Preferably, in step C, an ultrasonic device is used to enhance the dispersion, dissolution, and dissociation processes of lime slurry in the sample cup.

[0036] Preferably, in step C, the amount of lime milk to be tested added is the amount used to achieve a subsaturated state of calcium hydroxide in the sample cup.

[0037] Preferably, the timing unit in step D is between 15 and 45 seconds.

[0038] Preferably, in step F, the activity of the lime slurry sample is characterized and evaluated by the area covered by the diffusion conductivity-time curve.

[0039] The method designed in this scheme for rapidly and accurately characterizing the chemical reactivity of lime slurry is based on the following theoretical basis: Lime slurry generally participates in physicochemical reactions in the liquid phase as a reactant in relevant applications. There are two main factors affecting its reaction rate and effect: one is quantity, i.e., the effective number of calcium hydroxide particles per unit volume of liquid phase (or the number of dissociated OH groups). － The quantity of calcium hydroxide particles is considered; secondly, the quality, specifically the specific surface area and interfacial activity of the calcium hydroxide particles. Direct conductivity measurement can effectively reflect the conductive ions (including Ca²⁺) per unit volume of lime slurry. 2+ OH － Mg 2+ Na + Cl － and H3O + While the static diffusion rate can characterize the reactivity of water-soluble ions in the liquid phase, it cannot measure their migration rate or reactivity. However, it cannot reflect the overall reactivity of lime slurry. Therefore, this method combines the static diffusion rate with direct conductivity measurement. By measuring the rate of change in conductivity during the static diffusion process of lime slurry, the chemical reactivity of lime slurry is characterized, solving a problem that existing technologies struggle to overcome. The advantages of this method are: clear and sufficient theoretical basis; high accuracy in characterizing lime slurry activity and strong resistance to interference (interference factors such as measurement temperature, lime slurry concentration, impurity content, and additives are suppressed or weakened); more importantly, the lime slurry activity characterized by this method has a stronger correlation with downstream applications and is more practically instructive.

[0040] Specifically, this scheme employs a dual-cup detection method, with one cup serving as the sample cup and the other as the detection cup. The two cups are horizontally connected by a connecting tube, acting as a diffusion bridge to ensure the liquid levels are level and minimize measurement discrepancies caused by level differences. A shut-off valve is installed on the connecting tube for quick on / off operation. Deionized water is used to eliminate background noise from the conductivity meter's readings.

[0041] Quickly drop a small amount of lime slurry into the sample cup. If each beaker contains 500 ml of water, the recommended amount of lime slurry is 2-3 ml. Before dropping, measure the initial conductivity of the sample cup using a conductivity meter. After dropping, the conductive ions in the lime slurry begin to diffuse within the sample cup. At this point, open the shut-off valve. Under extremely weak hydraulic pressure, the lime slurry (containing calcium hydroxide microparticles and dissociated ions) in the sample cup undergoes static migration and diffusion towards the sample cup through the liquid bridge, generating different conductivity values. These values ​​are captured and recorded by the conductivity meter to form the current conductivity. The increase in current conductivity compared to the initial value represents the quantity and activity of conductive ions brought about by the diffusion of lime slurry. The shorter the time and the more conductive ions, the better the chemical reactivity of the lime slurry being tested.

[0042] The recording ends when the diffusion effect of the lime slurry to be tested nears its end, and the conductivity value stabilizes without significant increase or decrease (±0.1 μS / cm). Alternatively, the recording can be simply stopped after 600 seconds from the start of the timing.

[0043] Plotting the above data in a graph, with time on the horizontal axis and conductivity on the vertical axis, yields a diffusion conductivity-time curve (area method) for the lime slurry sample. Figure 2 As shown.

[0044] The formula for calculating the chemical reactivity of lime slurry using the area method is as follows:

[0045]

[0046] yi = σi - σ0, (i = 1, 2...)

[0047] In the formula,

[0048] R—reactivity of lime milk, measured in μS·s / cm;

[0049] σ i —Instantaneous conductivity of lime slurry during static diffusion, in μS / cm;

[0050] σ0—Initial conductivity (or background conductivity) of lime slurry before static diffusion, in μS / cm;

[0051] x — the time interval for recording the conductivity of lime slurry during static diffusion, measured in seconds.

[0052] The smaller the time unit, the smoother the curve in the graph, and the more accurate the coverage area calculated based on the integral method. However, the workload of observation and recording will also increase exponentially. To balance the accuracy of the test and the operability of the observation and recording, a time unit of 30 seconds is preferred, that is, the conductivity value is recorded every 30 seconds.

[0053] It is recommended that the number of values ​​taken satisfy i≥15. With a selected time unit, increasing the number of records means extending the observation time, resulting in a more complete conductivity-time curve that better reflects the overall static diffusion process, and making the testing and evaluation of lime slurry reactivity more objective.

[0054] Based on this, it is also possible to use, for example Figure 3 The simplified calculation method shown is as follows.

[0055] The formula for calculating the chemical reactivity of lime slurry using the approximate area method is as follows:

[0056]

[0057] In the formula,

[0058] R—reactivity of lime milk, measured in μS·s / cm;

[0059] σ max —The peak conductivity of static diffusion of lime slurry (usually the endpoint), in μS / cm;

[0060] σ0—Initial conductivity (or background conductivity) of lime slurry before static diffusion, in μS / cm;

[0061] t — Total static diffusion time of lime slurry, in seconds.

[0062] In summary, the beneficial effects of this scheme are: the measuring device is simple, the results are accurate, the operation is simple and quick, and it has high anti-interference and reproducibility. It can more objectively evaluate the reactivity of lime slurry and has a greater guiding role for downstream related fields and application scenarios. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the detection device of the present invention.

[0064] Figure 2 This is a diffusion conductivity-time curve (area method) of a lime milk sample.

[0065] Figure 3 This is a diffusion conductivity-time curve (approximate area method) of a lime milk sample.

[0066] The components include: 1. Sample cup, 2. Detection cup, 3. Connecting tube, 4. Dropper, 5. Stop valve, 6. Conductivity meter, and 7. Electrode. Detailed Implementation

[0067] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0068] High-quality limestone near the inventor's location was selected and calcined under different conditions to produce quicklime with different theoretical activities. After digestion, refining, and aging for 24 hours, eight lime milk samples, Lime1-8, with a mass concentration of 13±0.5%, were obtained. The experimental arrangement is shown in Table 1.

[0069] Table 1: Relevant data of experimental arrangement and lime milk samples to be tested

[0070] Sample number Firing temperature ℃ Digestion process additive <![CDATA[BET(m 2 / g)]]> <![CDATA[Ca(OH)2% <!-- 4 -->]]> Lime 1 950 room temperature digestion none 27.10 95.03 Lime 2 1050 room temperature digestion none 30.05 94.71 Lime 3 1100 room temperature digestion none 26.29 95.12 Lime 4 1050 room temperature digestion GLU 1.0% 31.56 94.78 Lime 5 1050 High-temperature digestion none 32.58 94.91 Lime 6 1050 High-temperature digestion NaCl 1.0% 22.17 94.70 Lime 7 1050 High-temperature digestion GLU 1.0% 36.11 94.66 Lime 8 1050 High-temperature digestion TEA 1.0% 38.23 94.82

[0071] Note: ①BET(m 2 / g) refers to the specific surface area data of calcium hydroxide powder after lime milk is filtered, dried and pulverized;

[0072] ②The purity data of Ca(OH)2% is obtained by titrating calcium hydroxide with hydrochloric acid after filtering, drying and grinding lime milk.

[0073] Example 1

[0074] like Figure 1 As shown, the main equipment and materials used in Example 1 include:

[0075] The sample cup 1 is located on the left, and the test cup 2 is located on the right. In this example, sample cup 1 and test cup 2 are of the same specification and model. The connecting tube 3 is a horizontally placed straight glass tube with a smooth inner wall, about 15 cm in length, with both ends extending to near the center of sample cup 1 and test cup 2, respectively. The dropper 4 is used to accurately draw up the lime slurry to be tested. The shut-off valve 5 is located in the middle of the connecting tube 3 and has a quick-opening structure for rapid opening and closing. The conductivity meter 6 has its electrode 7 submerged below the liquid surface of test cup 2 and close to the opening of the connecting tube 3 on the side of test cup 2.

[0076] The steps for this example are as follows:

[0077] 1. Pour 500ml of tap water into both the test cup and the sample cup. Open the shut-off valve on the connecting tube to connect the liquids on both sides until the liquid levels are level and just cover the upper edge of the connecting tube opening.

[0078] 2. Close the shut-off valve and place the testing device (excluding the conductivity meter) into a water bath and keep it at a constant temperature of 25℃±0.5℃.

[0079] 3. Use a dropper to draw 2 ml of the lime milk to be tested and quickly add it into the sample cup. At the same time, open the shut-off valve and press the stopwatch to record the initial conductivity value σ0 of the test cup.

[0080] 4. Under extremely weak hydraulic pressure, the lime milk (containing calcium hydroxide microparticles and dissociated ions) in the left sample cup undergoes static migration and diffusion to the right detection cup through the liquid bridge. The instantaneous conductivity σ of the liquid phase in the detection cup is recorded every 30 seconds. i .

[0081] 5. After approximately 600 seconds, the conductivity value tends to stabilize, without significant increase or decrease (±0.1 μS / cm). The test is then completed. The data is entered into a table to generate a diffusion conductivity-time curve, and the reactivity of the lime slurry sample is calculated and characterized by the curve coverage area. The calculation is performed according to the formula below, and the results are shown in Table 2.

[0082]

[0083] y i =σ i -σ0, (i = 1, 2...)

[0084] In the formula,

[0085] R—reactivity of lime slurry, measured in μS·s / cm²

[0086] σ i —Instantaneous conductivity of lime slurry during static diffusion, in μS / cm

[0087] σ0—Initial conductivity (or background conductivity) of lime slurry before static diffusion, in μS / cm

[0088] x — the time interval for recording the conductivity of lime slurry during static diffusion, measured in seconds.

[0089] Example 2

[0090] 1. Pour 500ml of deionized water into both the test cup and the sample cup. Open the shut-off valve on the connecting tube to connect the liquids on both sides until the liquid levels are level and just cover the upper edge of the connecting tube opening.

[0091] 2. Close the shut-off valve and place the testing device (excluding the conductivity meter) into a water bath and keep it at a constant temperature of 25℃±0.5℃.

[0092] 3. Use a dropper to draw 3 ml of the lime milk to be tested and quickly add it into the sample cup. At the same time, open the shut-off valve and press the stopwatch to record the initial conductivity value σ0 of the test cup.

[0093] 4. Under extremely weak hydraulic pressure, the lime milk (containing calcium hydroxide microparticles and dissociated ions) in the left sample cup undergoes static migration and diffusion to the right detection cup through the liquid bridge. The instantaneous conductivity σ of the liquid phase in the detection cup is recorded every 30 seconds. i .

[0094] 5. After approximately 600 seconds, the conductivity value tends to stabilize without significant increase or decrease (±0.1 μS / cm), and the test is completed. The data is entered into a table to generate a diffusion conductivity-time curve, and the reactivity of the lime slurry sample is calculated and characterized by the curve coverage area. The calculation method is the same as in Example 1, and the results are shown in Table 2.

[0095] Same as Example 1.

[0096] Example 3

[0097] 1. Pour 500ml of deionized water into both the test cup and the sample cup. Open the shut-off valve on the connecting tube to connect the liquids on both sides until the liquid levels are level and just cover the upper edge of the connecting tube opening.

[0098] 2. Close the shut-off valve and place the testing device (excluding the conductivity meter) into a water bath with ultrasonic function, and keep the temperature constant to 25℃±0.5℃.

[0099] 3. Use a dropper to draw 3 ml of the lime slurry to be tested and quickly add it into the sample cup. Under the action of ultrasound, accelerate the dissolution and diffusion of the lime slurry in the sample cup. At the same time, open the shut-off valve, press the stopwatch, and record the initial conductivity value σ0 of the test cup.

[0100] 4. Under extremely weak hydraulic pressure, the lime milk (containing calcium hydroxide microparticles and dissociated ions) in the left sample cup undergoes static migration and diffusion to the right detection cup through the liquid bridge. The instantaneous conductivity σ of the liquid phase in the detection cup is recorded every 30 seconds. i .

[0101] 5. After approximately 600 seconds, the conductivity value tends to stabilize without significant increase or decrease (±0.1 μS / cm), and the test is completed. The data is entered into a table to generate a diffusion conductivity-time curve, and the reactivity of the lime slurry sample is calculated and characterized by the curve coverage area. The calculation method is the same as in Example 1, and the results are shown in Table 2.

[0102] Same as Example 1.

[0103] Example 4

[0104] 1. Pour 500ml of deionized water into both the test cup and the sample cup. Open the shut-off valve on the connecting tube to connect the liquids on both sides until the liquid levels are level and just cover the upper edge of the connecting tube opening.

[0105] 2. Close the shut-off valve and place the testing device (excluding the conductivity meter) into a water bath with ultrasonic function, and keep the temperature constant to 25℃±0.5℃.

[0106] 3. Use a dropper to draw 2 ml of the lime slurry to be tested and quickly add it into the sample cup. Under the action of ultrasound, accelerate the dissolution and diffusion of the lime slurry in the sample cup. At the same time, open the shut-off valve, press the stopwatch, and record the initial conductivity value σ0 of the test cup.

[0107] 4. Under extremely weak hydraulic pressure, the lime milk (containing calcium hydroxide microparticles and dissociated ions) in the left sample cup undergoes static migration and diffusion to the right detection cup through the liquid bridge. The instantaneous conductivity σ of the liquid phase in the detection cup is recorded every 30 seconds. i .

[0108] 5. After approximately 600 seconds, the conductivity value tends to stabilize and does not increase or decrease significantly (±0.1 μS / cm). The test is then completed. The data is entered into a table to generate a diffusion conductivity-time curve. The reactivity of the lime slurry sample is then calculated and characterized by the conductivity increase rate. The calculation is performed according to the formula below, and the results are shown in Table 2.

[0109]

[0110] In the formula,

[0111] R—reactivity of lime slurry, measured in μS·s / cm²

[0112] σ max —The peak conductivity of lime slurry during static diffusion (typically the endpoint), measured in μS / cm.

[0113] σ0—Initial conductivity (or background conductivity) of lime slurry before static diffusion, in μS / cm

[0114] t — Total static diffusion time of lime slurry, in seconds.

[0115] Same as Example 1.

[0116] Comparative Example 1

[0117] 1. Close the shut-off valve and pour about 500ml of deionized water into the test cup on the right.

[0118] 2. Place the testing device (excluding the conductivity meter) in an ultrasonic water bath and keep it at a constant temperature of 25℃±0.5℃.

[0119] 3. Turn on the ultrasound, use a dropper to draw 2ml of the lime slurry to be tested, quickly add it to the test cup, and simultaneously start the stopwatch. Record the conductivity value σ of the test cup after 15 seconds. 15The reactivity of the lime slurry was measured in mS / cm (tested three times and the average value was calculated). The test data for the above experiment are shown in Table 2.

[0120] Comparative Example 2

[0121] 1. Close the shut-off valve and pour about 500ml of deionized water into the test cup on the right.

[0122] 2. Place the testing device (excluding the conductivity meter) in an ultrasonic water bath and keep it at a constant temperature of 25℃±0.5℃.

[0123] 3. Turn on the ultrasound, use a dropper to draw 2ml of the lime slurry to be tested, quickly add it to the test cup, and simultaneously start the stopwatch. Record the conductivity value σ of the test cup after 30 seconds. 20 The reactivity of the lime slurry was measured in mS / cm (tested three times and the average value was calculated). The test data for the above experiment are shown in Table 2.

[0124] Table 2: Experimental results of lime slurry reactivity tests in the examples and comparative examples

[0125]

[0126]

[0127] Note: ①Rmax: The lime slurry sample with the highest chemical reactivity;

[0128] ②Rmin: The lime milk sample with the lowest chemical reactivity.

[0129] Combining the data in Tables 1 and 2, it can be seen that both the static diffusion-conductivity curve method of this invention and the existing direct conductivity measurement method can quantitatively characterize and evaluate the activity of the eight lime slurry samples. However, based on the characterization results of Examples 1-4 and Comparative Examples 1-2, this method has higher activity resolution, test stability, and resistance to interference from impurity ions. Within the framework of this invention, consistent results can be obtained regardless of whether the integral curve area method or its simplified method, the approximate area method, is used: the chemical reactivity of the eight lime slurries is consistently ranked (Rmax and Rmin are accurately screened). In contrast, using existing methods, when testing lime slurry samples Lime 4 and Lime 5 with similar activities, discrepancies arise only due to different recording times. For lime slurry samples Lime 6-8 with added reducing agents, the test evaluation results lack consistency. This indicates that for "blind testing" samples where the source or composition of the lime slurry is unclear, existing methods are insufficient for accurate activity evaluation, while this method can handle such special cases.

[0130] To further illustrate the issue, the above-mentioned lime milk samples were carbonized under the same conditions, and the carbonation rate and the physicochemical properties of the precipitated calcium carbonate were tested. The results are shown in Tables 3 and 5.

[0131] The carbonization conditions are as follows:

[0132] Lime slurry concentration: 13.5 ± 0.5%

[0133] Initial carbonization temperature: 35℃±0.5℃

[0134] Lime slurry volume: 1000mL

[0135] CO2 gas flow rate: 2.0 L / min

[0136] Stirring speed: 120 r / min.

[0137] Table 3: Carbonation reaction process data and physicochemical indicators of the lime slurry to be tested

[0138]

[0139] As shown in Table 3, under the same conditions, lime slurries (Lime 1-8) with different reactivity exhibited significant differences in carbonation reaction time and calcium carbonate product indicators (BET, D50, and sedimentation volume). This indicates that monitoring the activity of lime slurry is essential and has practical guiding significance for the carbonation reaction of lime slurry.

[0140] Table 4: Predictive Analysis of Lime Slurry Carbonation Reaction Time by the Invention and Existing Technologies

[0141]

[0142] Note: The values ​​in parentheses after the numerical values ​​indicate the sorting order. Those with shorter carbonization times are sorted first, and for the activity R, those with larger values ​​are sorted first.

[0143] As can be seen from Table 4, compared with the existing technical solution (direct conductivity measurement method), the static diffusion-conductivity curve method proposed in this invention more closely matches the actual situation of the chemical reaction (lime milk carbonation reaction). That is, the higher the chemical reactivity R of lime milk, the faster the chemical reaction rate and the shorter the carbonation time. In contrast, the existing technical methods for evaluating the activity of lime milk are prone to significant deviations when predicting actual chemical reactions.

[0144] Table 5: Relationship between the lime slurry reactivity R and the lime slurry carbonation reaction rate V in the present invention

[0145]

[0146] To illustrate the practical significance of the method of this invention, Table 5 compares the chemical reactivity R of lime slurry characterized by this invention with the carbonation reaction rate V. The stability of the R / V ratio demonstrates whether there is a strong linear correlation between the chemical reactivity of lime slurry and the chemical reaction rate, and whether it has practical value in predicting and guiding downstream chemical reactions. As shown in Table 5, the R / V ratios of the eight lime slurry samples are all stable around 2419, with a relative deviation of no more than ±1.5%. This indicates that the chemical reactivity R of lime slurry characterized by this invention has a stable linear relationship with the actual chemical reaction, or in other words, an apparent calculated coefficient, which can be used to predict the rate of chemical reactions such as lime slurry carbonation.

[0147] In summary, the static diffusion-conductivity curve method of the present invention can not only more stably, accurately and scientifically characterize the chemical reactivity of lime slurry, greatly improving the accuracy of lime slurry selection in related production fields; it can also intuitively and effectively predict the speed and results of related chemical reactions such as lime slurry carbonation, which has significant practical guiding significance for related production processes.

Claims

1. A method for rapidly and accurately characterizing the chemical reactivity of lime slurry, characterized in that, The steps are as follows: A: Pour an appropriate amount of water into the test cup and sample cup, open the shut-off valve to connect the liquids on both sides, until the liquid level is above the upper edge of the connecting tube and flush with both sides. B: Close the shut-off valve and record the initial conductivity value σ0 of the detection cup; C: Use a sampling dropper to take a small amount of the lime slurry to be tested and quickly add it to the sample cup. The amount of lime slurry to be tested should be the amount needed to achieve a subsaturated state of calcium hydroxide in the sample cup. At the same time, open the shut-off valve and the timer. D: Record the instantaneous conductivity σ of the liquid phase in the test cup every time a timing unit is completed. i ; E: Continue recording until the conductivity value stabilizes and does not increase or decrease significantly, then the conductivity meter reading recording ends; F: Input the data into a table to generate a diffusion conductivity-time curve, and characterize and evaluate the activity of the lime milk sample by the curve coverage area.

2. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, The sample cup and the test cup are of the same model and specifications.

3. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, The connecting tube is a straight tube extending horizontally with a smooth inner wall, and a length of 10-20cm. Its two ends extend into the center of the sample cup and the detection cup, respectively.

4. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, The shut-off valve is a quick-opening shut-off valve.

5. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, Deionized water is used in step A.

6. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, Before starting step B, the sample cup, test cup, and connecting tube are all placed in a water bath and kept at a constant temperature of 25℃±0.5℃.

7. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, In step C, ultrasonic equipment is used to enhance the dispersion, dissolution, and dissociation processes of lime slurry in the sample cup.

8. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, The electrodes of the conductivity meter are in close contact with the opening at the end of the detection cup of the connecting tube.

9. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, The timing unit in step D is between 15 and 45 seconds.

10. The method for rapidly and accurately characterizing the chemical reactivity of lime slurry according to claim 1, characterized in that, In step F, the activity of the lime slurry sample is characterized and evaluated by the area covered by the diffusion conductivity-time curve.

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