JPS6214053A - Method and apparatus for measuring concentration of gold in gold cyanide plating liquid - Google Patents

Abstract

PURPOSE:To enable the implementation of the measurement of univalent gold and/or trivalent gold existing in a gold cyanide plating liquid handily and at a high accuracy, by using the potential difference titration with a silver nitrate solution as titration agent for the measurement of the concentration of gold. CONSTITUTION:A sample liquid introduced from a gold cyanide plating liquid tank 2 through a sampling mechanism 1 is introduced into a pH adjusting mechanism 4 to be adjusted to a fixed capacity and a pump 7 is operated by a signal from a control section 3 to feed a fixed capacity of a buffer liquid from a tank 6 so that the pH of the sample will be controlled to 4-5. The sample liquid filled into the mechanism 4 is injected into a titration cell 9 with the switching of the passage by a signal from a controller 3 and then, a titration pump 15 is signal from a controller 3 and then, a titration pump 15 is operated by a signal from an automatic titration computing section 18 to drop a silver nitrate aqueous solution in a titration tank 14 into the cell 9 thereby performing a potential difference of the sample liquid. At the same time, the computing section 18 automatically cumulates the capacity of the titration agent being dropped. Thus, the titrating reaction is measured as changes in potential with a potential difference titrator 10 thereby enabling the measurement according to the potential difference titration method.

Description

[Detailed Description of the Invention] LL1NP1L1 Kibatsuen relates to a method for measuring gold saturation in a cyanide gold plating solution and its continuous measuring device. The present invention relates to a method of separating 111 degrees by valence or measuring the entire gold concentration, and a continuous measuring device thereof.

Conventional technology and Akira's understanding - Gold plating films are used as contact materials and connection materials, as well as
i! ! It is well known that it is widely used as personal accessories.

The gold plating solution that provides this gold plating film usually uses potassium cyanide as the gold ion source, but the monovalent gold (Au(I)) in this plating solution is generally removed by using an insoluble anode as an anode. Therefore, as the gold plating progresses, 1
A decrease of 1 degree occurs. Also, in the process of gold plating, 1 part A
Although u(I) is oxidized to become trivalent gold (Au (III)), the action of this Au ([[[) causes the disadvantage that the current efficiency in the gold plating solution decreases.

Therefore, in order to maintain the stability of gold plating quality in a timely manner, Au (
It is necessary to perform the concentration w4 adjustment in 1) and introduce KAu (CN)z, but for this purpose it is necessary to measure the concentration of monovalent and mvalent gold present in the cyanide plating solution.

Conventionally, the method of measuring gold concentration in gold plating solution is as follows:
Examples include mFIi analysis, atomic absorption spectrometry, and stimulated plasma emission spectrometry. Of these, the fffffi analysis method has the drawback of being complicated and time-consuming to operate, while measurement methods based on so-called physical measurement principles, such as atomic absorption spectrometry and induced plasma emission spectrometry (ICP), are generally Due to the high sensitivity, a dilution operation is required, which tends to cause WA7:, and the apparatus is expensive. Furthermore, no matter which method is used, it is difficult to perform automatic measurement in-line with the plating solution bath at the plating work site.
It is not possible to make a differential quantitative measurement of DI>.

In this case, methods that can separately and quantitatively measure Au(I) and AIJ(III) include ion chromatography using a special separation column; None of the conventional methods can be called a practical measurement method because they have the disadvantage of being difficult to measure.

The present invention has been made in view of the above circumstances, and is based on Au(1) and/or Au present in the cyanide gold plating solution.
Practical gold concentration in cyanide gold plating solution that can easily perform 11 degree measurement (II) with high accuracy even at plating work sites, and can be automatically analyzed in-line with the plating bath if necessary. It is an object of the present invention to provide a measuring method and an inexpensive continuous measuring device that can continuously measure gold 11 degrees in a cyanide gold plating solution over a long period of time using the method of the present invention.

As a result of extensive research into the above measurement method and measurement 8i setting, the inventors found that (1) Au in a cyanide gold plating solution.
(I), Au (III)G;j each 1 gold cyanide ion ((Au (CN)2)'') 2 gold cyanide
Gold ions exist in the form <(Au (cN)u)-),
When encountered with 9+ ions, each) associates to form a precipitate, and ((Au (CN), )-) and ((Au (CN)
)p)-) 1i containing M1 ions
rlII! When potentiometric titration is performed using an aqueous silver solution as a titrant, Au(I) and A') and Au(I
II) The equivalence points of each of the above precipitation reactions are different because the solubility products of A9+ and A9+ products are different; Chemical gold plating solution with organic acid 11! F with i liquid
) It was found that this becomes noticeable when using one adjusted to F+4 to 5, and (3) it becomes more obvious when a silver ion selective ffi electrode or 11 electrode is used as the sensing electrode for potentiometric titration. did.

To explain this point in more detail, when an aqueous potassium cyanide solution is titrated potentiometrically with an aqueous solution of A 7 N O, a titration curve as shown in Figure 3 is obtained. When used, a titration curve as shown in FIG. 4 is obtained, thus A 9 NO.

By using as a titrant, Au <1), Au (
III) can be quantified individually, but when gold cyanide ions and gold cyanide ions coexist, a clear two-stage quantification is possible as shown in Figure 5. A titration curve of the curve is obtained.

Here, the titration volume A corresponds to AU(I), and B corresponds to the total Au [Au(I)+Au(Ill)]. Therefore, in a normal gold plating solution, Au(I) and Au(III) However, even if Au (Ill) and Au (Ill) coexist in this way, the ALI (I), Au (1), and total ALI of 11 degrees cannot be clearly defined. The potentiometric titration method using an aqueous solution of A 7 N O as a titrant can be used to measure gold cyanide plating solution gold IIr! It has been found that this method is very effective for measuring 1. Note that when using an AlN0° solution as a titrant, the presence of CI- ions, CN- ions, etc. similarly creates poorly soluble salts and interferes with the titration, but ordinary gold plating solutions do not contain these ions. Not included. Furthermore, even if it is contained, there is a difference between the solubility product of the product of gold cyanide and silver and the solubility product of these sparingly soluble salts, so it can be quantified separately.

Furthermore, as a result of studying the practical application of a continuous measurement device using the method of the present invention, it was found that when a cyanide gold plating solution is sampled and subjected to PJI adjustment, a precipitate is produced as a reaction product. However, in order to prevent precipitation products from adhering to the sensitive membrane of the sensing electrode used for potential difference measurement and to maintain the sensitive surface active, polishing with a polishing element is performed.
! The present inventors have discovered that the gold cyanide plating solution can be accurately quantified over a long period of time and the long-term stability of 1ilff can be guaranteed by using J method, leading to the present invention.

Therefore, the present invention uses a silver nitrate aqueous solution as a titrant to measure monovalent gold concentration, monovalent gold m degree, or total unit concentration in a cyanide gold plating solution, and the titration between the titrant and the cyanide gold plating solution. The present invention provides a method for measuring gold concentration in a cyanide gold plating solution, which is characterized in that the gold concentration is measured by potentiometric titration. In addition, the present invention includes a sampling mechanism for sampling the cyanide gold plating solution, a 11 adjustment mechanism for adjusting the sample of the cyanide gold plating solution by P+1, and a titration unit for performing potentiometric titration of the state-adjusted sample, The present invention also provides an apparatus for measuring gold concentration in a gold cyanide plating solution, characterized in that the titration section is provided with a detection electrode and a polishing element for polishing the sensitive film of the electrode.

According to the present invention, potentiometric titration using a silver nitrate solution as a titrant is used to measure the gold concentration in a cyanide gold plating solution. # 12 in a short time without any complicated operations!
Not only does it have the effect of easily and reliably measuring the gold concentration in cyanide gold plating solution with high accuracy, but it also enables in-line automatic measurement with the plating bath at the plating work site, and furthermore, titration. By using a silver nitrate aqueous solution as the agent, the 11- and trivalent gold concentrations in the gold cyanide plating solution, as well as the total gold concentration, can be measured separately and quantitatively. Further, since the apparatus according to the present invention polishes the sensitive film of the detection electrode, analysis of the gold cyanide plating solution can be performed stably over a long period of time.

The present invention will be explained in more detail below.

Gold m degree (Au (I) in the gold cyanide plating solution of the present invention
), Au (Ill), and total AU> are measured by potentiometric titration using an aqueous silver nitrate solution as a titrant.
Any neutral type may be used, and according to the present invention, the gold 1
Ira can be accurately analyzed. Note that commercially available potentiometric titrators and meters are fully usable. Titration is carried out according to a conventional method, and the titrant, silver nitrate turbidity, is appropriately selected depending on the gold 11 degree in the cyanide gold plating solution (sample) for measurement, the sensitivity and accuracy of the potentiometric titration device, etc. In addition,
The gold cyanide plating solution can be used in its original form or diluted with water to an appropriate ratio.

In the present invention, potentiometric titration is performed on a cyanide gold plating solution (sample) using an organic 111! ! It is preferable to perform this after adjusting the PF to 14 to 5 with one buffer solution. In this case, organic acid Il
As the li solution, 1, such as potassium hydrogen phthalate aqueous solution, etc.
4 to 5 are preferred. It should be noted that if a mineral acid is used instead of the above-mentioned organic acid when carrying out the 1')11 adjustment, there is a risk that cyan gas will be generated. Rimple adjustment is carried out so that the - of the sample becomes 4 to 5 as described above. For example, when a 0.5N potassium hydrogen phthalate aqueous solution is used as the silinic acid loose solution according to the present invention, It is preferable to add 10 times the volume to the sample pile.

In addition, when performing this potentiometric titration, detection is performed to obtain the inflection point at the equivalence point during potentiometric titration of the precipitation reaction that occurs between m-valent and m-valent gold and A-ion in the gold cyanide plating solution. As the electrode, it is preferable to use a silver ion-selective N electrode or a silver rod electrode, and the reference electrode contains an anion that forms a poorly soluble salt with A7~ ions such as CI- ions in the externally eluted internal solution of the N electrode. It is preferable to use a double-junction type electrode that does not contain, for example, KNO.

The apparatus of the present invention also includes a sampling mechanism for sampling the cyanide gold plating solution, an adjustment mechanism for adjusting the sample, and a titration section for performing potentiometric titration of the adjusted sample. Here, the sampling mechanism automatically samples the gold plating liquid from a single gold plating liquid tank, or selects the gold plating liquid to be analyzed when there are multiple gold plating liquid tanks, and transfers this gold plating liquid to the location. Quantitative automatic sampling, also 1 (key 11)
mm is ko (F) s > 7”) Lt d specified 11 (
7) @lit 1!111 It automatically injects WIJ liquid and automatically adjusts the sample state to 4 to 5. It is equipped with a v1 sin device with a built-in computer, which allows automatic sampling and self-11JP) l Adjustment III 6
1 is preferable. In addition, the titration section includes a titration cell,
It consists of an injection mechanism for injecting a predetermined amount of the -Ir14-prepared sample into this titration cell, and a potentiometric titrator.
Equipped with a meter. In this case, in the present invention, the sensing electrode is provided with a polishing element for polishing the sensitive film. In addition, injection of the sample, titration, Fi4r
Electrode polishing by the lJ element is preferably self-assisted υ1-, and these controls can be performed by the control device. Furthermore, the monovalent and mvalent gold concentrations of the cyanogen gold plating solution,
It is preferable to provide an automatic titration concentration calculation mechanism for automatically calculating the total gold concentration, and this 111m mechanism can also be built into the control device. Furthermore, when disposing a discharge mechanism for discharging the sample from the titration cell after the titration is completed, the discharge mechanism is composed of a sample discharge pipe with a hard material slide valve having a wide hole, and the Inn of this slide valve is The operation allows the rimple after the titration to be discharged from the titration cell. Note that it is preferable to automatically control the sample discharge and the opening and closing of the slide valve. Hereinafter, the present invention will be described in detail with reference to the drawings.

[Embodiment 1] Figures 1 and 2 show an embodiment of the device of the present invention. In the figure, 1 is a sampling mechanism, and this sampling mechanism 1 is composed of a standard pump and a three-way solenoid valve. , these fixed tooth pumps and three-way solenoid valves are arranged according to the number of gold plating liquids ff12. The pump is turned on and off by the control device 3 that has a built-in computer, and the υIII device 1tF3 operates a three-way solenoid valve connected to the gold plating liquid tank 2 containing the gold plating liquid to be analyzed to overcome the steep road.
vIA, the predetermined gold plating solution Mj2 is pumped by the operation of the pump.
The gold plating solution inside is sampled, and the gold plating solution is sent to the PHW4 adjusting mechanism 4. This S″lW4
The adjustment mechanism 4 includes an adjustment section 5 containing a metering tube of a fixed capacity, a buffer tank 6 containing an organic acid buffer solution with a pH of 4 to 5, and a buffer tank 6 containing an organic acid buffer solution with a pH of 4 to 5. Introducing liquid-liquid PH adjustment type input part 5! 1 If the liquid pump 7 and the sample liquid introduced through the sampling mechanism 1 are drained (
The sample liquid is introduced into the needle tube of the adjustment mta structure 4 to adjust the sample liquid to a constant volume, and further, the buffer pump 7 is operated in response to a signal from the control unit 3 to supply a constant volume of buffer from the buffer tank 6. Adjust sample states to 4-5.

8 is a titration unit, which includes a titration cell 9, a potentiometric titration device 10,
A sample discharge pipe 12 connected to the titration cell 9 and interposed with a slide valve 11 made of a wide-hole hard material, a drain tank 13 in which the discharged sample is stored, and a titrant tank 14 in which an aqueous silver nitrate solution is stored. , this Vlii1! A titrant pump 15 that introduces the aqueous silver solution into the titration cell 9, a cleaning liquid tank 16 that contains a washing RP solution, a cleaning liquid pump 17 that sends this cleaning liquid to the titration cell 9, and controls the potentiometric titration and calculates the results of the titration B1. and an automatic titration calculation section 18 that calculates. Further, the potentiometric titration apparatus 1o is equipped with a detection electrode, a comparison '/11 pole, and a scale meter, and a polishing element is disposed on the detection N pole as shown in FIG. ing. That is, 19 in FIG. 2 is a support tube;
0 is a detection electrode attached to a support tube 19. A magnetic stirrer 21 is disposed inside the support tube 19, and a polishing II element 22 is attached to the sensitive film of the detection electrode 20 by the action of the magnetic stirrer 21. contact, and the polishing element 22 rotates under the action of the magnetic stirrer 21, thereby polishing the sensitive film of the detection type 1f120. Note that 23 is a lead wire.

The sample liquid filled in the measuring tube of the r+1Itl cell 4 is injected into the titration cell 9 by being pushed out by the titration liquid pump 7 after the flow path is switched by a signal from the control device 3. .

After the sample liquid is injected into the titration cell 9 in this way, the titrant pump 15 is operated by a signal from the automatic titration calculation unit 18, and the nitrate silver aqueous solution (titrant) in the titrant tank 14 is pumped. The sample liquid is dropped into the titration cell 9, and potentiometric titration of the sample liquid is performed. At the same time, automatic titration calculation section 1
8 automatically accumulates the volume of the titrant added. The titration reaction caused by the above titration is detected by the electrode 20, and the ?
I! The potential change is measured by the potentiometric titrator Pf10 connected to wA20, and measurement is performed according to the potentiometric titration method. The equivalence point due to the titration reaction is determined after potentiometric titration [
10 to the automatic titration WAn section 18 as an electrical signal, the automatic titration calculation section 18 automatically calculates the potential change (for example, #FJ according to the known end point detection method), and The titrant concentration and the desired gold concentration are automatically calculated to obtain the desired measured value. In addition,
Although not shown, a printer is connected to the automatic titration calculation unit 18 for automatic printing of measured values and other recording purposes, and the results are printed on the printer.

In this case, this potentiometric titration is considered to be a complex formation reaction between /l ions and gold cyanide, and as the titration progresses, precipitation occurs, and in the case of a continuous automatic vJ apparatus for such precipitate-forming titration, the sensitivity of the electrode 20 gradually increases. The membrane is covered with precipitates and the potential fluctuates or becomes unstable, but with the above device,
The polished Jl element 22 is brought into close contact with the sensitive membrane, and the titration is carried out while polishing the surface of the sensitive membrane, so the potential is stabilized, the inconvenience of potential fluctuations is avoided, and stable measurements can be made over a long period of time.
Changes in electrode potential can be suppressed to within 5 mV even during long-term operation for 6 months.

After the above-mentioned potentiometric titration, the operation of the titrant pump 15 is stopped, and then the wide-pore hardwood IR slide valve 11 is opened by the (F4) from υll1lPII3.
The titrated sample liquid is discharged as a sample! At the same time, the cleaning liquid pump 17 is operated, and the cleaning liquid in the cleaning liquid tank 16 is introduced into the titration cell 9 for cleaning. In this case, if a normal magnetic valve or the like is used as the valve port for discharging the sample liquid, there is a risk of problems such as clogging due to sediment in the sample liquid, but in the above vtW1, the inner diameter is 10! Since a ground slide valve having a wide hole diameter of IIm or more and made of a hard material such as ceramic is used, clogging due to such deposits can be reliably prevented. Using a pinch valve is also effective in preventing clogging.

As mentioned above, sampling, PHy4 adjustment, electrode polishing, drainage, and cleaning are performed in order, and one measurement is completed.
Such measurements are controlled by IJJ till IAIt 3, and by continuously repeating them, automatic continuous analysis of gold i11 degrees in the gold plating solution is performed.

The above continuous gold concentration measuring device has the function of making it possible to completely analyze the gold plating line in-line by adding sampling mechanisms according to the number of plating tanks, and facilitating the maintenance and management of the gold plating solution. .

Note that the above device is merely an explanation of an example, and the above
The configuration of the i-position may be modified in various ways without departing from the gist of the present invention.

Next, examples of the method of the present invention will be shown, but the method of the present invention is not limited to the following examples.

(Example 2) Add 0.5N potassium hydrogen phthalate aqueous solution to 201! In addition, the PF was adjusted to 14-5. This time, gold
It can be seen that both the m value and the measured value and the difference between repetitions are small, and the values and accuracy are sufficient to withstand plating work.

(Example 5) Practical gold cyanide plating solution 101 with unknown concentrations for both m value and m value! 0.5N potassium hydrogen phthalate aqueous solution
0011 was added, and the pH was adjusted to 4 to 5.

Thereafter, potentiometric titration was carried out in the same manner as in Examples 1 to 3, and the results shown in FIG. 6 and Table 2 were obtained.

In the case of an actual plating solution, all monovalent gold is initially introduced, and as plating progresses, trivalent gold gradually increases. 1/1 sample! If the extraction is different, trivalent gold becomes 1
5% Pi for 11i gold! If 0 occurs, it indicates that fractional titration is possible. In this way, the measuring method of the present invention makes it possible to separately measure monovalent and trivalent components in a gold plating solution.

[Example 6] Actually used cyanide gold plating solution for 4 seconds (however, one of these
One species contains cobalt with a concentration on the order of PPM, and the other contains nickel with a concentration on the order of 1 degree %)51
! Add 0.5N potassium hydrogen phthalate aqueous solution to 501! In addition, the number was adjusted to 14-5. Thereafter, potentiometric titration was carried out in the same manner as in Examples 1 to 4, and for comparison, the above-mentioned four types of cyanide gold plating solutions were analyzed by weight, and the results shown in Table 3 were obtained.

From the results in Table 3, both! ¥! Compared to m analysis, the difference is within ±5% and is not affected by other coexisting substances such as cobalt and nickel. Therefore, the method of measuring gold concentration in a cyanide gold plating solution of the present invention was recognized to be an extremely practical method.

The gold concentration measurement method in a cyanide gold plating solution according to the present invention is as follows:
Since this is a potentiometric titration method using silver nitrate as a titrant, it is possible to determine the gold concentration of 111Ii and the gold concentration of valence 2 separately. Furthermore, in am buffer I=tlvI4! !
When the distance is 1m, no cyan gas is generated.
In addition, the potentiometric titration curve shows a sharper change near the peak point, so that measurements can be carried out safely and accurately. When a gold cyanide plating solution is installed, the precipitation reaction between the gold cyanide ions and the titrant is not interfered with, and the potentiometric titration curve becomes sharper near the current point. Sufficient sensitivity, accuracy, and
It definitely exhibits the effect of having characteristics such as simplicity.

In addition, the continuous measurement device according to the present invention is an application of the above method, and therefore not only can the effects of the above method be exhibited, but also the electrode surface is polished. This method has the following effects: it prevents the accumulation of fouling of the rack due to precipitated products, ensures stable measurement over a long period of time for repeated and continuous measurements, and enables simpler automatic measurement.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a metallurgical degree measuring device according to the present invention;
Is Figure 2 used for the same device? The cross-sectional view of the I-pole portion and FIGS. 3 to 6 each show an example of a potentiometric titration curve obtained by *Embodiment of the method of the present invention. 1... Sampling mechanism, 2... Gold plating liquid tank, 3
... control tlIl device, 4... field adjustment mechanism, 5...
state adjustment department, 6...am liquid tank, 7...all liquid pump, 8...titration unit, 9...titration cell, 10...potentiometric titration device, 11...wide pore hardwood FlI slide valve, 12.
...Sample discharge pipe, 13...Drainage tank, 14...
・Titrant tank, 15...Titrant pump, 16...
Cleaning liquid tank, 17... Cleaning liquid pump, 18... Automatic titration calculation section, 19... Support tube, 20... Detection ff
i pole, 21...magnetic stirrer, 22...r
i4a! I element, 23...Lead wire Applicant: rR Kikai Kagaku Keiki Co., Ltd. Agent, Patent Attorney Takashi Kojima Figure 1 Figure 2 Figure 3 Potential of sensing electrode 100 500 mV Figure 4 Potential of sensing electrode 200 500 mV Detection Electrode potential 100 500mV Figure 6 Detection electrode potential

Claims (1)

[Claims] 1. When measuring the I-valent gold concentration, III-valent gold concentration, or total gold concentration in a cyanide gold plating solution, an aqueous silver nitrate solution is used as a titrant, and the titrant and the cyanide gold plating solution are mixed together. A method for measuring the gold concentration in a cyanide gold plating solution, comprising measuring the gold concentration as described above by potentiometric titration with a cyanide gold plating solution. 2. The method according to claim 1, wherein a gold cyanide plating solution adjusted to pH 4 to 5 with an organic acid buffer is subjected to potentiometric titration. 3. Claim 1 or 2 using a silver ion selective electrode or a silver electrode as a sensing electrode for potentiometric titration
The method described in section. 4. A sampling mechanism for sampling a gold cyanide plating solution, a pH adjustment mechanism for adjusting the pH of a sample of the gold cyanide plating solution, and a titration section for performing potentiometric titration of the pH-adjusted sample, An apparatus for measuring gold concentration in a cyanide gold plating solution, characterized in that a detection electrode and a polishing element for polishing a sensitive film of the electrode are provided. 5. The titration unit is provided with a sample discharge pipe having a wide-pore slide valve made of hard material, and the titrated sample is discharged by opening the valve. Device. 6. After detecting the completion of injection of the pH-adjusted sample liquid into the titration cell installed in the titration unit, start titration of the titrant, cumulatively calculate the volume of titrant consumed during titration, and perform titration. Claims 4 or 5 include an automatic titration concentration calculation mechanism that inputs the potential change from the part as a signal and calculates the equivalence point of the titration reaction and the sample concentration at the corresponding amount point. The device described.