JPS6214045A - Method and apparatus for analyzing chromate treating liquid composition - Google Patents

Abstract

PURPOSE:To simplify the analysis of chromate treating liquid composition element, by a method wherein after the total Cr in the treating liquid is determined, Cr<6+> is settled from the treating liquid separately to determine Cr<3+> from the residual solution and then, the value of Cr<3+> is subtracted from the total Cr value to obtain Cr<6+>. CONSTITUTION:When a chromate treatment of a Zn plated steel plate is carried out by a chromate treating liquid, the composition elements are analyzed. Here, first, a raw chromate treating liquid undergoes an X ray fluorescence analysis to determined the total amount of Cr. Separately, BaCl2 or the like is added to the raw chromate treating liquid and made to react with only Cr<6+> to be settled as BaCrO4 while Cr<3+> and Zn<2+> left as intact without being settled. The balance of the solution undergoes X ray fluorescence analysis to determine the amount of Cr<3+> and Zn<2+>. Then, the amount of Cr<6+> is determined by subtracting the amount of Cr<3+> from the total amount of Cr. Thus, the addition of a simple chemical pretreatment to the X ray fluorescence analysis eliminates the need for any costly apparatus to enable the determination of Cr at a high accuracy by patterns while permitting automatic analysis online.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention aims at determining the total C concentration in a chromate treatment solution containing CrB+ ions as a main component, the Cr3÷ and Cr6+ ion concentration, and the compositional element concentration in the chromate treatment solution. The present invention relates to an analysis method and apparatus using fluorescent X-ray analysis.

<Prior art and its problems> Normally, when manufacturing Zn-plated steel sheets, etc., one step is taken to prevent the occurrence of white rust and improve corrosion resistance, and to improve the adhesion with paint when painting. Chromate treatment is applied as ground treatment.

This chromate treatment involves passing a plated steel plate through a chromate treatment solution and applying chromium chromate (CR203, C'03, XL12) to the surface of the plating bath.
0 or Cr(Kano)3 ・Cr(O)I) ・CrO
4) By forming an amorphous chromate film called
As mentioned above, it improves corrosion resistance and secondary adhesion.

However, this chromate treatment process has the following problems. In other words, plating elements are removed from the plating bath into the chromate treatment solution while passing the plated steel sheet through the plate.
For example, in the case of a Zn-plated steel sheet, Zn2+ ions are eluted and act as a reducing agent for C6+ ions.

Therefore, during operation, Zn2+ ions, which are plating elements, gradually increase in the chromate treatment solution, and accordingly, Cr6+ ions decrease and Cr3+ ions increase.

As the concentrations of plating elements and Cr3+ ions increase in this way, the reaction to form a chromate film becomes insufficient, and a good chromate film is not formed, resulting in a significant deterioration of the surface properties.

From the above, it is necessary to constantly analyze and monitor the concentrations of Cr3'' ions, CrB+ ions, plating elements, etc. in the chromate treatment solution, and to manage the concentrations of these ions so that they are always below the specified amount.

The conventional method for managing this chromate treatment solution was for workers to collect samples and chemically analyze them, but this method requires a long time to analyze, so analysis can only be done several times a day. Therefore, it is difficult to control the production of a high-quality chromate film with stable quality, and it is not suitable for long-term unattended operation.

For this reason, it has been desired above all to develop a method that can analyze online, and in recent years, Cr has been analyzed using spectrophotometry.
A method for analyzing 3÷ and Cr6+ ion concentration has been disclosed (JP-A-53-95695 and JP-A-54-128).
No. 783).

In this method, the chromate treatment solution sucked in by a pump is first sent to a filter to remove precipitates and suspended substances in the sample, and after being brought to a constant temperature in a thermostatic chamber, air bubbles are removed in a degassing tank. It flows into a sample cell made of optical glass. Illuminate the sample cell with white light from a tungsten lamp, and
The light absorbed and attenuated by Cr6÷ions is divided into three optical paths by a half mirror, one of which is Cr3'', CrB+
The absorbance at a wavelength around 540 nm, where ions are absorbed, is measured to determine the content concentration of both Cr"" and Cry ions.For the other light, the absorbance at a wavelength around 630 nm, where only Cr3+ ions are absorbed, is determined. Calculate C'3÷ion concentration.Then, the Cr6+ ion concentration is calculated from the previously determined Cr3'' and Crl3+ both ion content concentrations.
It is calculated by subtracting + ion concentration,
This has the disadvantage that it is difficult to simultaneously analyze the concentration of plating elements such as Zn2+ ions.

<Objective of the Invention> The present invention solves this problem, and provides a method for automatically and easily quantifying the Cr3+ ion concentration and CSf+ ion concentration in the chromate treatment solution, as well as the concentration of constituent elements such as plating elements in the chromate treatment solution. The purpose of the present invention is to provide a method for analyzing the composition of a chromate treatment solution and an apparatus therefor.

The present invention provides the following methods for analyzing at least Cr3+ ion and Cr6+ ion concentrations in a chromate treatment solution using fluorescent X-ray spectrometry:
+ ions and plating elements are not precipitated, Cr6+ ions are precipitated and separated, and the composition of the residue after separating the precipitate is analyzed to determine the concentration of at least C3+ ions; (b) Analyzing the chromate treatment solution stock solution; At least all C
(c) A method for analyzing the composition of a chromate treatment solution characterized by subtracting the C3+ ion concentration obtained in (a) from the total Cr concentration obtained in (b) to obtain the Cr6+ ion concentration. This is what we provide.

The present invention also includes a reaction tank in which the chromate treatment solution is subjected to chemical pretreatment to precipitate Cr (i+ ions and chelate Cr3÷ ions and plating elements), and a reaction tank in which CrB+ ions are extracted from the pretreated chromate treatment solution. a separator that separates a precipitate based on Cr6 ÷ ions; a dropper that separately injects samples of the pretreatment chromate treatment solution and the chromate treatment solution stock solution from which the precipitate based on Cr6÷ions has been separated by the separator; The present invention is characterized by comprising a sheet material onto which the sample is dripped by a device, a dryer for drying the solvent of the sample dripped onto the sheet material, and a fluorescent X-ray analyzer for the dried sheet material. The present invention provides an apparatus for analyzing the composition of a chromate treatment solution.

The present invention will be explained in more detail below.

Recently, Zn plating, Sn plating, Zn-Ni plating, 7
．． In order to quantify the concentration of each component in various plating solutions such as n-Fe plating and various chemical conversion treatment solutions, an instillation fluorescent X-ray analysis method (Japanese Patent Application No. 58-30742) has been developed. The present invention applies and improves this instillation fluorescent X-ray analysis method, making it possible to analyze Cr by form. Drip fluorescence X-ray analysis is a method in which a certain amount of a solution sample is dripped onto a thin porous sheet material (for example, filter paper) to impregnate it, the sheet material is dried to remove the solvent, and then the sheet material is It is placed in a vacuum and performs fluorescent X-ray analysis, and is used to analyze Zn, Sn, and Ni in various plating solutions and various chemical conversion treatment solutions as mentioned above.

It is used to analyze various compositional components such as Fe, Cr, S, Cfl, and Na. If this device can be used to analyze each form of C, the above-mentioned problems can be solved, and moreover,
Since there is no need to purchase a spectrophotometric analyzer solely for measuring r3'' and Cr8+ ion concentrations, its added value will further increase.

However, due to its principle, the fluorescent X-ray analysis method cannot analyze Cr according to its form, and has the problem that the content of Cr3'' and Cr6 decalytic ions, that is, the total Cr4 degree is quantified.

Therefore, in order to separately quantify Cr3+ ion and Cr8÷ ion, it is necessary to completely separate both ions by some method and analyze only one of them by instillation. Therefore, we investigated various chemical pretreatment methods for its separation.

As a result, Cr6+ ions in the chromate treatment solution were
If the pH is adjusted so that 0A2- ions are present in the solution and Ba2+ ions are added, Cr6+ ions will precipitate as BaCrO4, so only Cr3+ ions will remain in the solution.A separation method using a chemical reaction. By using the instillation X-ray fluorescence analysis method described above, C
We have found that it is possible to analyze the morphology of r.

The important thing here is that the type and amount of reagents used must be appropriately adjusted according to the chemical reaction.

Further, the plating element may be a single metal or an alloy, and its type is not limited.

In order for the CrB+ ions in the chromate treatment solution to exist in the solution as CrO42- ions, the pH must be adjusted to around 6 or higher, and the buffer solution 1 for this purpose is a fluorescent Xll5A that is easy to adjust the pH. Ammonium acetate, sodium acetate, citric acid, phosphoric acid, or boric acid solutions, etc., which do not contain elements that may interfere with analysis, are recommended.

However, in this PL, most of the galvanizing elements (Zn2+, Fe3+ ions, etc.) eluted from the plated steel sheet in the chromate treatment solution precipitate as hydroxides, making it impossible to analyze the plating elements. In this precipitate, C
3+ ions are adsorbed, and Cr3+ ions are Cr(O
Since it precipitates as old 3, Cr3+ ion and CrB+
Complete separation of ions is not possible.

Therefore, in order to have all of the plating elements and C3+ ions present in the solution without precipitating them, we devised a method to generate a chelate of these ions. ) The chelate reaction with the glazing element is fast, and Cr
It has been found that 3+ ions form a chelate, but CrB+ ions do not form a chelate, which is an advantage.

In addition, Ba2+ is present in a solution containing CrO42- ions.
Reagents for producing a precipitate of ions xH and Ba(:r04) include barium chloride, barium carbonate, barium hydroxide, barium nitrate, and the like.

Furthermore, the amount of reagents used is based on the sampling amount of chromate treatment solution, plating element, Cr3+ ion and Cr6+
It was found that once the analysis concentration range of ions was determined, a sufficient chemical reaction could proceed with the addition of a certain amount of each reagent. This is a major advantage in that it is easy to operate and easy to automate.

By the chemical pretreatment detailed above, it is possible to leave the plating elements and Cr3+ ions in the solution and precipitate only the Cr6+ ions, and a certain amount of the solution is dripped onto a thin porous sheet to impregnate it. By performing fluorescent X-ray analysis after drying, the concentrations of plating elements, Cr3+ ions, and other constituent elements can be determined.

The total Cr concentration is analyzed using the usual method of directly injecting a certain amount of the chromate treatment solution and performing fluorescent X-ray analysis without performing this pretreatment in parallel with this pretreatment. By subtracting the above-mentioned Cr3+ ion concentration from the analysis value, the CrG+ ion concentration can be determined.

Analysis of other constituent elements in the chromate treatment solution, such as plating elements, can be performed from samples of either the pretreated solution or the solution without surface treatment.

Next, an apparatus for analyzing the composition of a chromate treatment liquid according to the present invention will be explained based on the configuration diagram shown in FIG.

FIG. 1 shows a preferred embodiment of the present invention, and with reference to this figure, an example in which the method of the present invention was applied to the analysis of a chromate solution used to chromate a Zn-plated steel plate will be explained. .

In this figure, a Zn-plated steel sheet 2 that has been plated in a Zn plating tank 1 is transported in the six directions of arrows and is chromate-treated in a chromate-treatment tank 3.

The chromate treatment liquid is injected from the chromate treatment tank 3 into the sample collection cup 4, a certain amount of it is injected into the dropper 5, and the filter paper is supplied one by one onto the sheet material holder 7 from the sheet material supply device 6. Drop onto a porous sheet material such as. The sheet material is sent to a dryer 8 and dried. Here, the solvent is removed by evaporation, and only the solutes such as various constituent elements contained in the solution remain attached to the sheet material.

This sheet material is fed into the fluorescent X-ray analyzer 9, placed in a vacuum, and irradiated with primary X-rays, and the fluorescent X-rays of the solute attached to the sheet material are detected, and the fluorescent X-rays contained in the chromate treatment solution are detected. The concentration of synthetic components containing light elements is analyzed. At this time, regardless of the form of Cr, all Cr
The concentration is analyzed.

On the other hand, a certain amount of the chromate treatment solution is collected in the reaction M110, and a buffer solution, such as ammonium acetate, stored in a tank 11 is injected into this tank 10 to adjust p++ to 6-7.

Next, the chelating agent stored in tank 12 is added to reaction tank 1.
0 to generate chelates of Zn2+ ions and Cr3+ ions.

After that, a precipitant such as barium chloride for Cr6+ ions stored in the tank 13 is injected and stirred.
Precipitate Cr8+ ions.

The solution sample in which CrB+ ions have been precipitated as described above is completely separated into the precipitate and the solution by the separator 14, and a certain amount of the solution is dropped onto a porous sheet material such as filter paper as before. After drying, Zn2+ was analyzed using a fluorescent X-ray analyzer 9.
Analyze the concentration of ions and Cr3+ ions.

In this way, from the total Cri degree obtained earlier, Cr3
By subtracting the + ion concentration, the C'6+ ion concentration is determined, and the morphology of Cr is analyzed.

The BaC:r04 precipitate deposited in the separator 14 is washed with a cleaning solution (for example, 11Cfi) led from the tank 16 after the measurement is completed.
) After dissolving and washing the precipitate, H2O led from tank 17
1, allowing continuous use.

In addition, the constituent elements in the chromate treatment solution other than the above-mentioned Cr'', Cr3+, and Zn2+, which is the plating metal, may be present in the chromate treatment solution as it is or in the '+'A of the chromate treatment solution that has been subjected to pretreatment such as precipitating Cr6+.
It can be determined from either droplet optical X-ray analysis.

In addition, in the online system, for example, the above-mentioned fluorescent
When attempting to automatically adjust the concentration of the chromate treatment solution etc. based on the results of line analysis, a device 15 for automatically controlling the solution concentration in the chromate treatment tank 3 is provided, and the output signal of the analyzer 9 is applied to this device 15. By adding chemicals, etc. according to the analysis results, and automatically managing the composition of the chromate treatment liquid, the chromate treatment tank 3
supply to.

<Example> Although the present invention is applicable to the analysis of a chromate treatment solution for chromate treatment of a Zn-plated steel plate in which Zn plating is applied to a steel plate, the present invention is not limited to this example. There isn't.

Inject 5M ammonium acetate 251i from tank 11 into reaction tank 10, then 0.1 MEDTA from tank 12.
15- was injected into the reaction tank 10. Furthermore, after injecting the chromate treatment liquid from 5 companies into the reaction tank 10 from the chromate treatment WI3, the 60.58M [1a (:I12
15+d was injected into the reaction tank 10 and stirred to precipitate C'6+ ions.The solution sample in which the precipitate was formed as described above was injected into the separation vessel 14 to completely separate the precipitate and the solution. Then, a certain amount of the solution is applied to a porous sheet material such as filter paper on a holder 7 supplied from a sheet material supply device 6 using a dropper 5.
After drying using a dryer 8, the concentration of Cr3+ ions was analyzed using a fluorescent X-ray analyzer 9.

Figures 2 and 3 show Zn2+ obtained by the above method.
This is an example of a calibration curve for ions and Cr3÷ions. In this way, both showed good linearity.

Using this calibration curve, an actual chromate treatment solution was analyzed in the same manner as described above. The results (n=30) are shown in Figure 4.
It is shown in FIG.

Figure 4 shows the analysis results for Zn2+ ions, and Figure 5 shows the results for Cr3 ions.
+ ion analysis results, the horizontal axis is the chemical analysis value, the vertical axis is the analysis value by the final method, and the accuracy (Od) is 0.
．． 12.0.024.

Thus, it can be seen that there is no difference in analytical values between the method of the present invention and the chemical analysis method, and the analysis can be performed with good performance.

<Effects of the Invention> As detailed above, the present invention adds a simple chemical pretreatment device to the drip fluorescence It is possible to quantify CR by carving type without purchasing an analyzer.

In addition, with the powder method, all components of a solution sample can be automatically and quickly analyzed online, making it extremely easy to automatically control the composition of the chromate treatment solution, allowing economical process control and ensuring stable production with high quality. The effect is very large.

Furthermore, it has excellent functions and effects, such as the amount of sample to be analyzed is extremely small, which is several tens of μU.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an apparatus for analyzing the composition of a chromate treatment liquid according to the present invention. FIGS. 2 and 3 show Zn' produced by the method of the present invention, respectively.
FIG. 4 is a diagram showing calibration curves for + ions and (:r""-i' ions. FIGS. 4 and 5 are diagrams showing Zn2
It is a diagram showing the correlation between the analysis results of ÷ ions and C'3+ ions and the same analysis results by manual analysis (chemical analysis method). Explanation of symbols 1...Zn-plated steel plate, 2-Zn-plated steel plate, 3...
・Chromate treatment tank, 4・-sample collection cup, 5...
Dropper, 6... Sheet material feeder, 7... Sheet material holder, 8... Dryer, 9... Fluorescent X-ray analyzer, 1
0... Reaction tank, 11... Buffer tank, 12-...
Chelating agent tank, 13...Cr6+ precipitant tank,
14...Separator, 15...Concentration automatic control device, 16
...Cleaning liquid tank, 17...Water tank Patent attorney Yo Ishii -tsuFIG,
1 FIG, 2 zn2+ orange dose line (9/1) FIG, 3 Cr3+ branch dose line (g/I) FIG, 4

Claims (2)

[Claims] (1) When analyzing at least the Cr^3^+ ion and Cr^6^+ ion concentrations in the chromate treatment solution by X-ray fluorescence analysis, (a) Cr^ in the chromate treatment solution is determined by chemical pretreatment.
3^+ ions and plating elements are not precipitated, and Cr^6
^+ ions are precipitated and separated, and the composition of the residual solution after separating the precipitates is analyzed to determine at least the Cr^3^+ ion concentration; (b) the chromate treatment solution stock solution is analyzed to determine at least the total C
Determine the r concentration, and (c) calculate the C determined in (a) from the total Cr concentration determined in (b).
A method for analyzing the composition of a chromate treatment solution, characterized in that the concentration of Cr^6^+ ions is determined by subtracting the concentration of r^3^+ ions. (2) A reaction tank that performs chemical pretreatment to precipitate Cr^6^+ ions and chelate Cr^3^+ ions and plating elements in the chromate treatment solution, and a chromate treatment subjected to this pretreatment. Cr^6^ from liquid
A separator that separates precipitates based on + ions, and an infusion that separately injects samples of pretreatment chromate treatment solution and chromate treatment solution stock solution from which precipitates based on Cr^6^+ ions have been separated by this separator. a sheet material onto which the sample is dripped by the dropper, a dryer for drying the solvent of the sample dripped onto the sheet material, and a fluorescent X-ray analyzer for the dried sheet material. An analyzer for analyzing the composition of a chromate treatment solution.