Active identification and rapid detection method for composite effective calcium component in engineering material

Abstract

The invention provides an active identification and rapid detection method for a composite effective calcium component in an engineering material, and relates to the technical field of lime detection. The rapid detection method mainly comprises the following steps: drying, heating and scattering to-be-detected composite effective calcium, respectively adding multiple groups of treated to-be-detected composite effective calcium with the same mass into multiple groups of diluted hydrochloric acid solutions with the same mass, concentration and volume to prepare mixed solutions, and measuring the temperature, pH value and conductivity of the multiple groups of mixed solutions, and calculating the mass of calcium oxide, calcium hydroxide and calcium carbonate in the to-be-detected composite effective calcium, and taking the average value of multiple groups of experimental results as a final result. According to the method, different chemical properties and physical properties of the components in the composite effective calcium are utilized, the mass of the components is calculated by measuring the PH value, the temperature and the conductivity of the solution, the dosage of CaO, Ca (OH) 2 and CaCO3 in the composite effective calcium to be measured can be effectively measured, operation is easy, and the result is accurate and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of lime detection, and in particular to a method for actively identifying and quickly detecting composite effective calcium components in engineering materials. Background Art

[0002] In the field of engineering construction, composite effective calcium is an important material component, and its quality directly affects the performance and quality of the project. For example, in highway construction, the performance of lime-stabilized soil base is closely related to the content of calcium oxide in the composite effective calcium. Insufficient calcium oxide content will lead to insufficient base strength, while excessive calcium oxide content may cause problems such as base expansion; in bridge construction, accurate measurement of the quality of each component in the composite effective calcium is crucial for the lime pile to react stably underground and achieve the expected reinforcement effect. Therefore, it is of great significance to accurately identify and detect the content of each component in the composite effective calcium.

[0003] At present, there are many methods for testing composite effective calcium components, and traditional methods include thermogravimetric analysis, acid-base titration, X-ray diffraction, and elemental analysis. In thermogravimetric analysis, the temperature range in which calcium hydroxide decomposes into calcium oxide and water may overlap with the temperature range in which calcium carbonate decomposes into calcium oxide and carbon dioxide, which affects the accuracy of the measurement; the acid-base titration method analyzes and judges the reaction process based on the change in the color of the indicator, which is affected by human subjectivity and has large errors; the X-ray diffraction method is not sensitive to low-content component detection, and the data processing and analysis are complex. It requires operators to have extremely high professional knowledge and has high requirements for equipment and experimental conditions. In production practice, the final data value of its determination will always have certain errors due to various conditions; the elemental analysis method is greatly interfered by impurity elements, and the sample pretreatment requirements are high. Therefore, there is an urgent need for a method that can be fast, accurate, simple, and suitable for active identification and rapid detection of composite effective calcium components in engineering materials to ensure that the quality of composite effective calcium used in engineering construction meets the requirements and ensure the quality and safety of transportation facilities. Summary of the invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a method for actively identifying and quickly detecting composite effective calcium components in engineering materials, which can effectively detect the specific dosage of each component in the composite effective calcium and improve the accuracy and universality of detection.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A method for actively identifying and quickly detecting composite effective calcium components in engineering materials, the determination method comprising the following steps:

[0007] S1, take the composite effective calcium and heat and dry it;

[0008] S2, breaking up the dried composite effective calcium to obtain pretreated composite effective calcium;

[0009] S3, taking n groups of pretreated composite effective calcium of the same mass, adding them into n groups of dilute hydrochloric acid solutions of the same mass, concentration and volume, respectively, and stirring them uniformly to obtain n groups of mixed solutions, wherein n is a natural integer greater than 0;

[0010] S4, using a thermometer, a conductivity meter and a pH meter to test and record the temperature, conductivity and pH value of the n groups of mixed solutions;

[0011] S5. Calculate the mass proportion of calcium oxide, calcium hydroxide and calcium carbonate in the composite effective calcium according to the temperature, pH value and conductivity of the mixed solution.

[0012] Preferably, the specific method of heating and drying in step S1 is to put the composite effective calcium into a drying device, use hot air to air-dry the composite effective calcium, control the hot air temperature at 200-220° C., and continue drying for 10 minutes.

[0013] Preferably, the specific method of the breaking up treatment in step S2 is to add the dried composite effective calcium into a stirrer, set the stirring speed to 500 rpm, pass the stirred composite effective calcium through a 5 mm filter, and continue to stir the composite effective calcium that has not passed through the filter until all the composite effective calcium can pass through the filter.

[0014] Preferably, the calculation method in step S5 comprises the following steps:

[0015] S5-1. Calculate the information of initial hydrochloric acid: calculate the mass of the solution, the mass of hydrochloric acid and the molar mass of hydrochloric acid according to the volume of the hydrochloric acid solution and the density of the hydrochloric acid solution;

[0016] S5-2. Calculate the hydrogen ion concentration [H + ];

[0017] S5-3. Analyze the stoichiometric relationship between each substance and hydrochloric acid reaction:

[0018] Let the mass of calcium oxide be xg, the mass of calcium hydroxide be yg, the mass of calcium carbonate be zg, and x+y+z=h, where h is the total mass of the mixture;

[0019] Calcium oxide (CaO) reacts with hydrochloric acid: CaO + 2HCl = CaCl2 + H2O, the molar mass of calcium oxide M (CaO) = 56 g / mol, then the amount of calcium oxide substance Amount of hydrochloric acid consumed Amount of substances producing calcium chloride

[0020] Calcium hydroxide (Ca(OH)2) reacts with hydrochloric acid: Ca(OH)2+2HCl=CaCl2+2H2O, the molar mass of calcium hydroxide M[Ca(OH)2]=74g / mol, then the amount of calcium hydroxide substance Amount of hydrochloric acid consumed Amount of substances producing calcium chloride

[0021] Calcium carbonate (CaCO3) reacts with hydrochloric acid: CaCO3+2HCl=CaCl2+H2O+CO2↑The molar mass of calcium carbonate M(CaCO3)=100g / mol, then the amount of calcium carbonate substance Amount of hydrochloric acid consumed Amount of substances producing calcium chloride

[0022] The total amount of substances that generate calcium chloride

[0023] The amount of hydrochloric acid remaining after the reaction According to [H+], we can get n 剩余 (HCl) = [H+] × V 反应后 ; Where n0(HCl) is the amount of hydrochloric acid before the reaction;

[0024] S5-4. Change in solution volume

[0025] The reaction produces water:

[0026] The amount of water produced by the reaction of calcium oxide quality

[0027] The amount of water produced by the reaction of calcium hydroxide quality

[0028] The amount of water produced by the reaction of calcium carbonate quality

[0029] The total mass of generated water

[0030] Assume the volume of the solution after the reaction is V 反应后 The change in solution volume is related to the generated substances and the density change before and after the reaction. Assuming that the density of the solution after the reaction is ρ 反应后 , according to the law of conservation of mass m+m 生成水 -m 逸出 (CO2) = ρ 反应后 V 反应后

[0031] (m 逸出 (CO2)) is the mass of carbon dioxide produced by the reaction of calcium carbonate,

[0032] S5-5. Calculate ion concentration relationship based on conductivity

[0033] Knowing the solution temperature and conductivity κ, consult the data to obtain the molar conductivity of calcium ions, molar conductivity of hydrogen ions, and molar conductivity of chloride ions.

[0034] according to

[0035] The amount of chloride ion substance n(Cl - ) = n0(HCl) (because of the conservation of chlorine atoms),

[0036] The amount of calcium ion substance

[0037] The amount of hydrogen ion substance

[0038] S5-6. Solving simultaneous equations

[0039] Simultaneous equations x+y+z=100,n 剩余 (HCl) = [H+] × V 反应后 (including the expression for volume change), and the conductivity equation The equations are solved by numerical calculation software (such as Matlab, etc.) to obtain the results.

[0040] The present invention provides a method for actively identifying and quickly detecting composite effective calcium components in engineering materials, which has the following advantages over the prior art:

[0041] (1) The method of the present invention only needs to measure the temperature, pH value and conductivity of the mixed solution, and list three equations to calculate the three unknowns of calcium oxide mass, calcium hydroxide mass and calcium carbonate mass through the total mass of the composite effective calcium, the pH value of the solution and the conductivity. Compared with the traditional thermogravimetric analysis, acid-base titration, X-ray diffraction and elemental analysis, the operation process is simpler and more direct, without complicated sample pretreatment and cumbersome experimental steps; and the method of the present invention can complete the determination of the effective components of the composite effective calcium in a relatively short time; and the operator does not need to have highly professional knowledge and rich experience, and can master it through general training, which reduces the impact of differences in personnel operation levels on the experimental results, and is easier to promote and apply in actual production and testing.

[0042] (2) Compared with traditional thermogravimetric analysis, acid-base titration, X-ray diffraction and elemental analysis, the method of the present invention has good applicability for composite effective calcium of different sources and qualities. Whether it is a high-purity composite effective calcium sample or an actual industrial composite effective calcium containing certain impurities, this method can effectively determine the content of calcium oxide, calcium hydroxide and calcium carbonate. Traditional methods such as X-ray diffraction are not sensitive to low-content components and may not be able to accurately measure composite effective calcium samples with complex components; elemental analysis is greatly interfered by impurities, and the measurement results of samples with high impurity content have large deviations.

[0043] (3) The present invention does not generate harmful waste during the experiment, which is more environmentally friendly than some traditional methods. The experimental reagents are mainly common reagents such as dilute hydrochloric acid, and the reaction products are relatively simple and easy to handle, with less pressure on the environment, which meets the requirements of modern green chemistry and environmental protection.

[0044] (4) Compared with traditional thermogravimetric analysis, acid-base titration, X-ray diffraction and elemental analysis, the method of the present invention fully takes into account factors that may affect the experimental results (such as temperature). During the experiment, the solution temperature is controlled and measured, and temperature-related factors are analyzed during the calculation process, making the measurement results more detailed and accurate. In traditional acid-base titration, temperature changes may affect chemical reaction rates and equilibrium constants, but this method does not effectively control and consider temperature, which is easy to introduce errors; this method effectively improves the accuracy of the results by controlling the temperature and reflecting the temperature effect in the calculation.

[0045] (5) Compared with traditional thermogravimetric analysis, acid-base titration, X-ray diffraction and elemental analysis, the method of the present invention further reduces the influence of accidental errors on the experimental results by taking the average value of multiple measurements (taking n groups of composite effective calcium of the same mass for experiment). Compared with a single measurement, multiple measurements can more accurately reflect the true component content of the sample and improve the reliability of the measurement. In the traditional elemental analysis method, the accuracy of the results is difficult to guarantee due to the large interference of impurity elements and the difficulty in eliminating accidental errors in a single measurement; while the method of the present invention effectively reduces the error by taking the average of multiple measurements, making the measurement results more stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A flow chart of the design method of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Example:

[0049] A method for active identification and rapid detection of composite effective calcium components in engineering materials:

[0050] Take 57g of calcium oxide, 53g of calcium hydroxide and 40g of calcium carbonate and put them into a blender, mix them evenly, and use a disperser to make the diameter of the solid particles not exceed 5mm. Add the mixed solids into 2000ml of 10% dilute hydrochloric acid and mix them evenly. Measure the solution temperature at 25 degrees Celsius. After the readings of the pH meter and conductivity meter are stable, record the readings as PH=1.12, κ=100.2mS / cm=10.02S / m.

[0051] 1. Calculate the information of initial hydrochloric acid

[0052] The volume of dilute hydrochloric acid solution is known to be V0 = 2000ml = 2L, and the density of hydrochloric acid solution is ρ = 1.05g / cm 3 , then the mass of the solution m=ρV0=1.05g / cm 3 ×2000cm 3 =2100g.

[0053] Mass of hydrochloric acid m(HCl) = m × 10% = 210 g

[0054] The molar mass of hydrochloric acid M(HCl) = 36.5 g / mol, so the amount of hydrochloric acid substance

[0055] 2. Calculate hydrogen ion concentration based on pH

[0056] Given that pH = 1.12, the hydrogen ion concentration [H + ]=10 -1.12 mol / L≈7.59×10 -2 mol / L.

[0057] 3. Analyze the stoichiometric relationship between each substance and hydrochloric acid reaction

[0058] Suppose the mass of calcium oxide is xg, the mass of calcium hydroxide is yg, the mass of calcium carbonate is zg, and x+y+z=150.

[0059] Calcium oxide (CaO) reacts with hydrochloric acid: CaO + 2HCl = CaCl2 + H2O, the molar mass of calcium oxide M (CaO) = 56 g / mol, then the amount of calcium oxide substance Amount of hydrochloric acid consumed Amount of substances producing calcium chloride

[0060] Calcium hydroxide (Ca(OH)2) reacts with hydrochloric acid: Ca(OH)2+2HCl=CaCl2+2H2O, the molar mass of calcium hydroxide M[Ca(OH)2]=74g / mol, then the amount of calcium hydroxide substance Amount of hydrochloric acid consumed Amount of substances producing calcium chloride

[0061] Calcium carbonate (CaCO3) reacts with hydrochloric acid: CaCO3+2HCl=CaCl2+H2O+CO2↑The molar mass of calcium carbonate M(CaCO3)=100g / mol, then the amount of calcium carbonate substance Amount of hydrochloric acid consumed Amount of substances producing calcium chloride

[0062] The total amount of substances that generate calcium chloride

[0063] The amount of hydrochloric acid remaining after the reaction According to [H + ] can get n 剩余 (HCl)=[H + ]×V 反应后

[0064] 4. Consider the change in solution volume

[0065] The reaction produces water:

[0066] The amount of water produced by the reaction of calcium oxide quality

[0067] The amount of water produced by the reaction of calcium hydroxide quality

[0068] The amount of water produced by the reaction of calcium carbonate quality

[0069] The total mass of generated water

[0070] Assume the volume of the solution after the reaction is V 反应后 The change in solution volume is related to the generated substances and the density change before and after the reaction. The density of the solution after the reaction is estimated by consulting the data. 反应后 =1.08g / cm 3 , according to the law of conservation of mass m+m 生成水 -m 逸出 (CO2) = ρ 反应后 V 反应后

[0071] (m 逸出 (CO2)) is the mass of carbon dioxide produced by the reaction of calcium carbonate,

[0072] 5. Calculate ion concentration relationship based on conductivity

[0073] It is known that the solution conductivity κ = 100.2mS / cm = 10.02S / m.

[0074] At 25℃, the molar conductivity of calcium ions is Molar conductivity of hydrogen ions Chloride ion molar conductivity

[0075] according to

[0076] The amount of chloride ion substance n(Cl - ) = n0(HCl) (because of the conservation of chlorine atoms),

[0077] The amount of calcium ion substance

[0078] The amount of hydrogen ion substance

[0079] 6. Solving simultaneous equations

[0080] Simultaneous equations x+y+z=150,n 剩余 (HCl)=[H + ]×V 反 After the reaction (including the expression for volume change), and the conductivity equation Solve the equations using numerical calculation software (such as Matlab, etc.) and obtain (the results may vary slightly due to factors such as calculation accuracy) x≈58.5g, y≈52.3g, z≈39.2g;

[0081] The other four groups of experiments calculated the mass of calcium oxide, calcium hydroxide and calcium carbonate using the above method. The five groups of experiments measured the average mass of calcium oxide, calcium hydroxide and calcium carbonate to be 58.4g, 52.0g and 39.6g respectively.

[0082] The mass error of calcium oxide is 2.5%, the error of calcium hydroxide is 2.0%, and the error of calcium carbonate is 1.0%, with high overall detection accuracy.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for actively identifying and quickly detecting composite effective calcium components in engineering materials, characterized in that: The determination method comprises the following steps: S1, take the composite effective calcium and heat and dry it; S2, breaking up the dried composite effective calcium to obtain pretreated composite effective calcium; S3, taking n groups of pretreated composite effective calcium of the same mass, adding them into n groups of dilute hydrochloric acid solutions of the same mass, concentration and volume, respectively, and stirring them uniformly to obtain n groups of mixed solutions, wherein n is a natural integer greater than 0; S4, using a thermometer, a conductivity meter and a pH meter to test and record the temperature, conductivity and pH value of the n groups of mixed solutions; S5. Calculate the mass proportion of calcium oxide, calcium hydroxide and calcium carbonate in the composite effective calcium according to the temperature, pH value and conductivity of the mixed solution.

2. The measuring method according to claim 1, characterized in that: The specific method of heating and drying in step S1 is to put the composite effective calcium into a drying device, use hot air to air-dry the composite effective calcium, control the hot air temperature at 200-220° C., and continue drying for 10 minutes.

3. The measuring method according to claim 1, characterized in that: The specific method of the breaking up treatment in step S2 is to add the dried composite effective calcium into the stirrer, set the stirring speed to 500rpm, pass the stirred composite effective calcium through a 5mm filter, and continue to stir the composite effective calcium that has not passed through the filter until all the composite effective calcium can pass through the filter.

4. The measuring method according to claim 1, characterized in that The calculation method in step S5 comprises the following steps: S5-1. Calculate the information of initial hydrochloric acid: calculate the mass of the solution, the mass of hydrochloric acid and the molar mass of hydrochloric acid according to the volume of the hydrochloric acid solution and the density of the hydrochloric acid solution; S5-2. Calculate the hydrogen ion concentration [H + ]; S5-3. Analyze the stoichiometric relationship between each substance and hydrochloric acid reaction: Let the mass of calcium oxide be xg, the mass of calcium hydroxide be yg, the mass of calcium carbonate be zg, and x+y+z=h, where h is the total mass of the mixture; The total amount of substances that generate calcium chloride The amount of hydrochloric acid remaining after the reaction According to [H + ] can get n 剩余 (HCl)=[H + ]×V 反应后 ; Where n0(HCl) is the amount of hydrochloric acid before the reaction; V 反应后 is the volume of the solution after the reaction; S5-4, solution volume change: The total mass of generated water Set the density of the solution after the reaction ρ 反应后 , according to the law of conservation of mass m+m 生成水 -m 逸出 (CO2) = ρ 反应后 V 反应后 (m 逸出 (CO2)) is the mass of carbon dioxide produced by the reaction of calcium carbonate, S5-5. Calculate ion concentration relationship based on conductivity Knowing the solution temperature and conductivity K, consult the data to obtain the molar conductivity of calcium ions, molar conductivity of hydrogen ions, and molar conductivity of chloride ions. according to The amount of chloride ion substance n(Cl - )=n0(HCl), The amount of calcium ion substance The amount of hydrogen ion substance S5-6. Solve the simultaneous equations: Simultaneous equations x+y+z=100, n 剩余 (HCl)=[H + ]×V 反应后 , and the conductivity equation The equations are solved by numerical calculation software to obtain the results.

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