CN110632134B - Method for rapidly detecting content of chloride ions on surface of hot-rolled pickled steel plate - Google Patents
Method for rapidly detecting content of chloride ions on surface of hot-rolled pickled steel plate Download PDFInfo
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- CN110632134B CN110632134B CN201810653586.XA CN201810653586A CN110632134B CN 110632134 B CN110632134 B CN 110632134B CN 201810653586 A CN201810653586 A CN 201810653586A CN 110632134 B CN110632134 B CN 110632134B
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Abstract
The invention relates to a rapid detection method for the content of chloride ions on the surface of a hot-rolled pickled steel plateThe method adopts a sample of ultrapure deionized water to fully dissolve chloride ions remained on the surface of a steel plate, and then utilizes an electrochemical measurement means to quickly measure the concentration of the chloride ions in water, so that the chloride ions on the surface of the hot-rolled pickled steel plate can be quickly calculated, and the pickling solution for the field production of metallurgical enterprises does not contain F‑、Br‑、SO3 2‑Therefore, the concentration of the chloride ions can be accurately measured by adopting an electrochemical measurement method, the operation measurement time in the whole process can be controlled within 1.5 hours, and the method has high precision and convenience and very high practicability.
Description
Technical Field
The invention relates to a detection method, in particular to a method for rapidly detecting the content of chloride ions on the surface of a hot-rolled steel plate after acid pickling in a metallurgical enterprise.
Background
In metallurgical enterprises, hot-rolled steel coils are generally conveyed to a pickling line for processing operation, wherein the so-called pickling is to place the hot-rolled steel coils with rich oxide scales on the surface in various chemical acids for reaction, the oxide scales are corroded at a high speed by the reaction with the acids in the process, and the iron matrix is exposed and then enters a subsequent cold-rolling mill for processing or is directly sold to customers as a material of the hot-rolled pickled steel coils. In this process, the carbon steel product is usually freed of hot rolled surface scale using hydrochloric acid (HCl), which has a better surface condition since the iron matrix is now directly present, but which is also very susceptible to oxidation corrosion. During the production of the acid washing process, a rinsing water tank with three or four sections is arranged at the rear end of a chemical acid washing device, hydrochloric acid on the surface is fully washed away by industrial purified water, then the process enters a drying process and an oiling machine set, a layer of anti-rust oil is coated on the surface of the strip steel, and finally oxidation and corrosion of a hot-rolled acid-washed plate coil are avoided by a series of means.
With the recent rapid development of automobile materials and household electrical appliances, the requirements of customers on the surface quality of cold-rolled steel sheets are higher and higher, and the surfaces of hot-rolled and pickled coils cannot have any oxidation color or rust spots. However, since the hot rolled steel sheet inevitably has a large amount of chloride ions in the hydrochloric acid pickling process, the chloride ions always remain on the surface of the steel sheet although the steel sheet is subsequently cleaned with industrial purified water. It is known that chloride ions are elements with strong corrosivity, a trace amount of residues can corrode a steel plate, the chloride ions can promote oxygen absorption corrosion of metal, further oxidation products are formed, yellow spot defects are generated, and quality defects of a steel strip are caused. In the production process of a common site, the chlorine ion residue on the surface of the strip steel is mainly controlled by continuously discharging and supplementing new rinsing water, the rinsing water on the site is monitored by a method for chemically measuring the chlorine ions regularly (such as twice a week), so that a direct measurement means for the chlorine ions on the surface of the strip steel is always lacked, and the chlorine ion content of the rinsing water can only be measured regularly and indirectly, so that the labor is wasted, the chlorine ion concentration fluctuation during the twice measurement and under a large number of sudden conditions cannot be monitored, and a large number of unqualified hot-rolled pickled steel coils flow into the hands of customers to form unqualified surface quality products.
Therefore, the method can accurately and rapidly measure the content of the chloride ions on the surface of the pickled strip steel, and is one of the main problems to be solved in the production of modern hot-rolled pickled plate coil products. The technical data and contents in the relevant field are inquired, and the following technical schemes are mainly found:
a method for measuring the content of chloride ions on the surface of a steel plate or a steel strip after cold rolling (CN 201110179982.1, saddle steel company, Ltd.) provides a method capable of measuring the chloride ions on the surface of the steel strip, which is mainly characterized in that the produced steel strip is placed in a dilute nitric acid solution for soaking, then washed by distilled water for multiple times, reacted by a silver nitrate solution with a certain concentration, finally the solution to be measured is heated, evaporated and concentrated to a certain amount, the ultraviolet spectrophotometer is used for measuring, and the concentration of the chloride ions on the surface of the steel strip can be obtained by comparing the ultraviolet measurement result of the standard concentration of the chloride ions.
A method for measuring the content of chloride ions in a flattening solution for rolling steel plates (CN200710043084.7, Shanghai Bao steel industry detection company) provides a method for detecting the chloride ions in the flattening solution, which is mainly characterized in that the flattening solution is roasted in a muffle furnace at high temperature, residues are washed by distilled water to dissolve the chloride ions, potassium chromate and silver nitrate solution are titrated, and the concentration of the chloride ions in the original flattening solution is calculated and obtained.
The influence of surface pollutants on the atmospheric corrosion resistance of a cold-rolled low-carbon steel plate (corrosion and protection, 5 months 2002) provides another technical method for measuring the chloride ions on the surface of the strip steel, the surface of the strip steel is continuously washed by dilute sodium carbonate solution, the obtained washing solution is evaporated and distilled to obtain concentrated liquid, a capillary electrophoresis apparatus is used for measuring the concentration of the chloride ions in the solution, and finally the concentration of the chloride ions on the surface of the strip steel is calculated.
In summary, it can be known that the prior art method has a higher and faster implementation method for detecting chloride ions in a solution, but the detection process of chloride ions on the surface of strip steel has no faster measurement method, so that the invention establishes a method for testing the content of chloride ions in residual liquid on the surface of a steel plate by using a test method with simple treatment method, strong reproducibility and low cost, and the method has important significance.
Disclosure of Invention
The invention aims to provide a method for rapidly detecting the content of chloride ions on the surface of a hot-rolled pickled steel plate, which comprises the following steps:
(1) the concentration of each of the components was 1X 10 -7mol/L、1×10-6mol/L、1×10-5100mL of standard KCl solution with mol/L, controlling the temperature between 20 and 35 ℃, and adding AgCl/Ag2Immersing S electrode and potassium sulfate type reference electrode in the above standard solution, and measuring with standard electrochemical analyzer to obtain different chloride ion concentration potential values a1(mV)、a2(mV)、a3(mV)；
(2) Cutting and processing the hot-rolled pickled steel plate to be measured into N blocks with the same area of S (m)2) And arranging the steel sheets at regular intervals, and immersingVolume of V (m)3) In deionized water; controlling the temperature of the deionized water at 20-35 ℃, standing for more than 20min, preferably 20-40 min, preferably N is an integer more than or equal to 3, more preferably N is more than or equal to 3 and less than or equal to 25, and the area S is 0.05-0.15m2And V is 0.05m3Above, preferably 0.05m3≤V≤0.6m3The concentration of chloride ions in the deionized water is less than 1 x 10-3mg/L；
(3) Taking out the steel plate, and stirring the deionized water soaked in the steel block for at least 1min, wherein the preferable stirring time is 1-5 min; the stirring is performed to ensure that the ions in the deionized water are uniformly distributed;
(4) transferring 50mL of sample solution to be tested in the deionized water obtained in the step (3) by using a pipette, placing the sample solution into a 100mL clean glass container, controlling the temperature of the solution to be tested to be between 20 and 35 ℃, and under the action of a magnetic stirrer, carrying out AgCl/Ag treatment on the solution used in the step (1) 2Cleaning an S electrode and a potassium sulfate type reference electrode, immersing the S electrode and the potassium sulfate type reference electrode into deionized diluent to be detected, and measuring the concentration potential a (mV) of chloride ions by using a standard electrochemical analyzer;
(5) the concentration of chloride ions C (g/L) in the deionized dilution of step (4) was calculated according to the following formula:
(6) The chloride ion concentration w (g/m) of the surface of the hot-rolled pickled steel sheet can be calculated according to the following formula2)：
Preferably, steps (1) to (4) are carried out at the same temperature.
The stirring equipment in step (3) should be kept clean to avoid the introduction of chloride ions.
The method adopts a sample of ultrapure deionized water to fully dissolve chloride ions remained on the surface of the steel plate, and then utilizes an electrochemical measurement means to quickly measure the concentration of the chloride ions in the water, so as to calculate and obtain the chloride ions on the surface of the hot-rolled pickled steel plate-、Br-、SO3 2-Therefore, the concentration of the chloride ions can be accurately measured by adopting an electrochemical measurement method, the operation measurement time in the whole process can be controlled within 1.5 hours, and the method has very high precision and convenience and very high practicability.
Detailed Description
The technical solution of the present invention is further described with reference to specific embodiments.
AgCl/Ag in the examples2The S electrode and the potassium sulfate type reference electrode were purchased from Shanghai Reye, respectively.
Example 1
The concentration of the preparation standard is 1 × 10-7mol/l、1×10-6mol/l、1×10-5A 100ml KCl solution of mol/l, and AgCl/Ag at a temperature of 25 ℃ under control2Immersing S electrode and potassium sulfate type reference electrode in the above standard solution, and measuring with standard electrochemical analyzer to obtain different chloride ion concentration potential values a1＝139mV、a2＝91.5mV、a3＝52.5mV；
Taking steel plate produced on site in rinsing process section of pickling line, cutting into 5 pieces of steel plate with uniform size of 20cm × 30cm, placing in pure deionized water at 25 deg.C for 20min, and immersing the steel plate in the deionized water with volume of 0.313m3Then, the steel plate was taken out, and the remaining deionized water was sufficiently stirred for 3 min. Taking 50ml of deionized water to be tested by a pipette, placing the liquid in a 100ml clean glass container, controlling the temperature of the liquid at 25 ℃, and adding AgCl/Ag under the action of a magnetic stirrer2S electrode and potassium sulfate type reference electrode are immersed in the strip to be measuredIn the diluent of the seed solution, the potential value a of the chloride ion concentration in the solution to be measured is measured to be 97.9mV, and then the following steps are carried out:
the chloride ion concentration in the deionized diluent was calculated to be 2.6X 10 -5g/L, and calculating according to the following formula to obtain the chloride ion concentration of the surface of the hot-rolled pickled steel plate:
at this time, the concentration of chloride ions on the surface of the steel sheet was 0.0136g/m2The whole measurement process takes about 45 min.
Example 2
The concentration of the preparation standard is 1 × 10-7mol/l、1×10-6mol/l、1×10-5A 100ml KCl solution of mol/l, and AgCl/Ag at a temperature of 25 ℃ under control2Immersing S electrode and potassium sulfate type reference electrode in the above standard solution, and measuring with standard electrochemical analyzer to obtain different chloride ion concentration potential values a1＝139mV、a2＝91.5mV、a3＝52.5mV；
Taking steel plate produced on site in rinsing process section of pickling line, cutting into 15 pieces of steel plate with uniform size of 40cm × 40cm, placing in pure deionized water at 25 deg.C for 20min, and immersing the steel plate in the deionized water with volume of 0.32m3Then, the steel plate was taken out, and the remaining deionized water was sufficiently stirred for 3 min. Taking 50ml of deionized water to be tested by a pipette, placing the liquid in a 100ml clean glass container, controlling the temperature of the liquid at 25 ℃, and adding AgCl/Ag under the action of a magnetic stirrer2And (2) immersing the S electrode and the potassium sulfate type reference electrode into the deionized liquid diluent to be measured, measuring to obtain a chloride ion concentration potential value a of 87.8mV in the liquid to be measured, and then measuring according to the following steps:
The chloride ion concentration in the deionized diluent was calculated to be 4.42X 10-5g/L, and calculating according to the following formula to obtain the chloride ion concentration of the surface of the hot-rolled pickled steel plate:
at this time, the concentration of chloride ions on the surface of the steel sheet was 2.94X 10-3g/m2The whole measurement process takes about 60 min.
The technical method and the operation of the invention have the characteristics of simplicity, convenience and quickness, can be completed without special improvement or requirement on field production and equipment, and simultaneously the measured chloride ion concentration has the characteristics of higher measurement precision and rapidness, thereby being very suitable for implementation in the production field of steel enterprises.
Claims (6)
1. A method for rapidly detecting the content of chloride ions on the surface of a hot-rolled pickled steel plate is characterized by comprising the following steps:
(1) the concentration of each of the components was 1X 10-7mol/L、1×10-6mol/L、1×10-5100mL of standard KCl solution of mol/L, controlling the temperature between 20 and 35 ℃, and adding AgCl/Ag2Immersing S electrode and potassium sulfate type reference electrode in the above standard solution, and measuring with standard electrochemical analyzer to obtain different chloride ion concentration potential values respectively as a1、a2、a3；
(2) Cutting and processing the hot-rolled pickled steel plate to be measured into N steel plates with the same size and the area of S, arranging the steel plates at certain intervals, and immersing the steel plates in deionized water with the volume of V; controlling the temperature of deionized water at 20-35 deg.C, standing for more than 20min, wherein N is an integer greater than or equal to 3, and the area S is 0.05-0.15m 2And V is 0.05m3The concentration of chloride ion in the deionized water is less than 1 × 10-3mg/L；
(3) Taking out the steel plate, and stirring the deionized water soaked in the steel block for at least 1 min;
(4) transferring 50mL of sample solution to be tested in the deionized water obtained in the step (3) by using a pipette, placing the sample solution into a 100mL clean glass container, controlling the temperature of the solution to be tested to be between 20 and 35 ℃, and under the action of a magnetic stirrer, carrying out AgCl/Ag treatment on the solution used in the step (1)2Cleaning an S electrode and a potassium sulfate type reference electrode, immersing the S electrode and the potassium sulfate type reference electrode into deionized diluent to be detected, and measuring the chloride ion concentration potential a by using a standard electrochemical analyzer;
(5) calculating the chloride ion concentration C in the deionized diluent of step (4) according to the following formula:
(6) The chloride ion concentration w of the surface of the hot-rolled pickled steel plate can be obtained by calculating according to the following formula:
wherein, a1、a2And a3In mV;
the unit of a is mV;
the unit of S is m2；
The unit of V is m3；
The unit of C is g/L;
of wThe unit is g/m2。
2. The detection method according to claim 1, characterized in that: the steps (1) to (4) are carried out at the same temperature.
3. The detection method according to claim 1, characterized in that: and (3) standing for 20-40 min in the step (2).
4. The detection method according to claim 1, characterized in that: in the step (2), N is more than or equal to 3 and less than or equal to 25.
5. The detection method according to claim 1, characterized in that: in step (2), 0.05m3≤V≤0.6m3。
6. The detection method according to claim 1, characterized in that: in the step (3), the stirring time is 1-5 min.
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| CN108663473A (en) * | 2017-03-28 | 2018-10-16 | 上海梅山钢铁股份有限公司 | A kind of assay method of surface of steel plate chloride ion content |
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| CN1211731A (en) * | 1998-09-11 | 1999-03-24 | 大庆石油管理局地质录井公司 | Automatic continuous detection instrument for well drilling liquid chlorine ion |
| CN1351257A (en) * | 2001-11-27 | 2002-05-29 | 中国科学院广州化学研究所 | Method for measuring content of Cl element and its burner |
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