JPH0331646B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing high-purity stannous oxide in which contamination with tin oxide, tin hydroxide, etc. is eliminated as much as possible. [Prior Art] Stannous oxide is widely used as a tin ion supply material in tinning or soldering baths.
The stannous oxide used as the tin ion supplying material for these plating baths needs to be of high purity because it is necessary to quickly respond to variations in the bath composition of the plating bath. That is, impurities such as tin compounds other than stannous oxide, such as stannic oxide or tin hydrogen compounds, have a slower dissolution rate in acidic plating solutions than stannous oxide, and therefore impurities such as tin oxide and tin hydrogen compounds have a slower dissolution rate in acidic plating solutions than stannous oxide. It can be said that tin cannot meet the above requirements. Conventionally, stannous oxide has been produced by adding an alkaline aqueous solution to an acidic aqueous solution of a stannous salt and reacting it, and boiling the resulting slurry, or by boiling stannous hydroxide in an inert gas atmosphere. A common method is to calcinate at a temperature of around 30°F. However, these methods require a heating step, which inevitably leads to high costs, and the resulting stannous oxide tends to solidify, has an uneven shape, is difficult to handle, and is not very pure. The problem is that it is not. In addition, in order to improve the problems of the above method, stannous oxide is produced by simultaneously adding an acidic aqueous solution of a stannous salt and an aqueous alkali carbonate solution to a stirred aqueous solution at a predetermined temperature and pH range. A method for obtaining it is disclosed in JP-A-62-52130. However, this method only works at a given temperature and PH.
When adding an acidic aqueous solution of a stannous salt and an aqueous alkali carbonate solution to a specified aqueous solution, the addition must be done while adjusting the temperature and pH of the aqueous solution so that they do not fluctuate, which is a problem that requires extremely complicated work. It has the following. [Means and effects for solving the problems] The present inventors have solved the above-mentioned conventional problems,
As a result of intensive research into a method for obtaining stannous oxide directly from an acidic aqueous solution of stannous salt in a simple process, we found that a chlorine compound was added to an acidic aqueous solution of stannous salt at a temperature of 10 to 100°C. It was discovered that highly pure stannous oxide could be obtained through the extremely simple process of adjusting the pH of the liquid to 9 to 11 with an alkaline aqueous solution, and based on this, the present invention was completed. It is something. That is, the feature of the method for producing high-purity stannous oxide of the present invention is that an acidic aqueous solution of a stannous salt is prepared as it is or diluted with water, and then heated at a temperature of 10 to 100 ml.
The purpose is to maintain the temperature at 100℃, add a chlorine compound while stirring, and then add an alkaline aqueous solution to reach a pH of 9 to 11, and then age the produced stannous oxide while maintaining this temperature and pH. In order to achieve higher purity if necessary, the stannous oxide obtained above is further dissolved in water, and this is heated at a temperature of 10 to
The purpose is to maintain the temperature at 100°C, add a chlorine compound while stirring, and age the produced stannous oxide while maintaining the temperature. As the acidic aqueous solution of the stannous salt in the present invention, hydrofluoric acid, hydrochloric acid, sulfuric acid, boric acid, other acids, and any mixed acids thereof can be used as appropriate. Therefore, a major feature of the present invention is that, for example, tin plating stripping waves or various tin plating and solder plating waste liquids can be used, and the recovery and production of stannous oxide from these waste liquids can be achieved simultaneously. It is. The concentration of these acidic aqueous solutions of stannous salts is not particularly limited. Therefore, this acidic aqueous solution may be used as is for treatment, or it may be diluted with an appropriate amount of water. The reason for diluting with water is mainly to reduce the amount of aqueous alkaline solution added later. Next, a chlorine compound is added to this acidic aqueous solution. Addition of chlorine compounds generates Sn ₃ O ₂ in the middle.
This is to promote the dehydrogenation reaction of (OH) ₂ .
Therefore, all chlorine compounds having a dehydrogenating effect on Sn ₃ O ₂ (OH) ₂ can be used. Specific examples include ammonium chloride, sodium chloride, potassium chloride, zinc chloride, etc., but ammonium chloride is most preferred from the viewpoint of preventing a decrease in the purity of the produced stannous oxide since the cation decomposes and gasifies. The amount of this chlorine compound added is
Although it is preferable to change it appropriately depending on the amount of Sn, it is usually added in an amount of about 2.5 to 7.5% of the amount of Sn. Now, the dehydrogenation reaction of Sn ₃ O ₂ (OH) ₂ when ammonium chloride is used as the chlorine compound is as follows. Sn ₃ O ₂ (OH) ₂ +NH ₄ Cl + NaOH → 3SnO + NaCl + 2H ₂ O + NH ₃ ↑ Before adding the chlorine compound, the temperature of the acidic aqueous solution is raised to 10 to 100°C. temperature
When the temperature is lower than 10°C, the reaction rate decreases, whereas when it exceeds 100°C, 5SnO.2H ₂ O tends to be generated, which is not desirable. A chlorine compound is added to an acidic aqueous solution whose temperature is 10 to 100°C, preferably 70 to 90°C, and an alkaline aqueous solution such as caustic soda is added to the liquid while stirring.
The pH is adjusted to be in the range of 9 to 11, preferably 9.5 to 10.5. This pH adjustment is to precipitate the stannous salt and to prevent the formation of white 5SnO.2H ₂ O. That is, if the pH is less than 9, 5SnO.2H ₂ O is likely to be produced, whereas if the pH exceeds 11, tin ions are formed and the produced stannous oxide is redissolved. From this, stannous oxide is produced, and as it is, about 2
Aged in liquid for ~3 hours. With this maturation,
The crystal shape of the produced stannous oxide becomes closer to a spherical shape. After that, the produced stannous oxide is separated from the liquid,
By drying, the desired high purity stannous oxide can be obtained. Although the obtained stannous oxide has a much higher purity than that obtained by conventional methods, it may be subjected to a high purification process according to the present invention in order to further improve the purity. This is done by dissolving the obtained stannous oxide in water, maintaining it at a temperature of 10 to 100 °C, preferably 70 to 90 °C, adding a chlorine compound while stirring, and maintaining the temperature for about 2 Consisting of aging for ~6 hours. This promotes the dehydrogenation of Sn ₃ O ₂ (OH) ₂ , which is an intermediate impurity when producing stannous oxide, and converts Sn ₃ O ₂
(OH) ₂ is reacted to SnO, further improving the purity of SnO. [Example] A solution obtained by diluting a fluoric acid solution of a stannous salt (fluorine concentration 70 g/, tin concentration 200 g/) four times with water and a sulfuric acid solution of a stannous salt (sulfuric acid concentration 20 g/, tin concentration 50
g/) 1 was placed in a glass container, 10 g of ammonium chloride was added thereto, and while stirring while maintaining the temperature at 90° C., a 40% aqueous solution of caustic soda was further added until the pH reached 10. After the addition was completed, the temperature was maintained at 90° C. for 3 hours to ripen. The obtained precipitate was filtered and then dried at 100°C, and the composition, bulk density, and angle of repose of the obtained crystals were measured by X-ray diffraction, and chemical analysis was also carried out. Furthermore, dissolve this crystal in 1 water and add 20g of ammonium chloride while stirring while maintaining the temperature at 70℃.
and aged for 5 hours. The obtained precipitate was filtered, dried at 100° C. for 2 hours, and measured in the same manner as above. For comparison, similar measurements were also performed on crystals produced, aged, and dried by adding only caustic soda without adding ammonium chloride. The results are shown in Table 1.

[Table] As is clear from Table 1, the addition of ammonium chloride prevents the formation of tin hydroxide and promotes the formation of stannous oxide. In addition, compared to the stannous oxide produced in Experiment Nos. 3 and 4,
It can be seen that the purity is improved by redissolving and washing with ammonium chloride as in Experiment Nos. 5 and 6. It can also be seen that it is superior in terms of bulk density and angle of repose. Incidentally, when the impurities in Experiment No. 5 were quantified, they were as shown in Table 2. Note that all values shown in Table 2 are in %.

[Table] Next, the solubility of each product in Table 1 in dilute sulfuric acid was investigated. The dissolution experiment was carried out using dilute sulfuric acid at PH4 so that the concentration after dissolution was 20 g/Sn. The degree of turbidity of a dissolved aqueous solution is a measure of solubility,
This was determined by absorbance using an absorption photometer (manufactured by Hitachi). The results are shown in Table 3.

【table】

〔Effect of the invention〕

According to the present invention as described above, when producing stannous oxide from an acidic aqueous solution of a stannous salt, a chlorine compound is used and the process is performed at a relatively high pH.
Contamination with SnO intermediate products or tin hydroxide can be suppressed as much as possible, and stannous oxide, which is highly pure and extremely soluble in acids, can be produced at low cost without the need for complicated processes. Furthermore, it has the extremely useful effect that various plating waste liquids can be used as they are as acidic aqueous solutions of stannous salts.

Claims (1)

[Claims] 1. In a method for producing stannous oxide from an acidic aqueous solution of a stannous salt, the acidic aqueous solution is directly or diluted with water, maintained at a temperature of 10 to 100°C, and stirred. A method for producing high-purity stannous oxide, which comprises adding a chlorine compound and further adding an alkaline aqueous solution to adjust the pH to 9 to 11, and aging the produced stannous oxide while maintaining this temperature and pH. . 2. In a method for producing stannous oxide from an acidic aqueous solution of a stannous salt, the acidic aqueous solution is kept as is or diluted with water, maintained at a temperature of 10 to 100°C, and a chlorine compound is added while stirring, Furthermore, an alkaline aqueous solution is added to adjust the pH to 9 to 11, and the produced stannous oxide is aged while maintaining this temperature and pH. A method for producing high-purity stannous oxide, which comprises maintaining the temperature at 100°C, adding a chlorine compound while stirring, and aging the produced stannous oxide while maintaining the temperature.