JPS6142800B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently separating and recovering effective components in metal surface treatment waste liquid by ion exchange membrane dialysis.

The ion exchange membrane dialysis method is used as a method to effectively separate and recover acids and metal salts dissolved in various metal surface treatment waste solutions using sulfuric acid or hydrochloric acid, such as steel pickling waste solutions and aluminum anodizing waste solutions.

However, in addition to dissolved substances, this type of metal surface treatment waste liquid contains insoluble metals, metal oxides, fine suspended solids such as dust, surfactants, and oils such as rolling oil and cutting oil. It contains a small amount of inclusions, and if this is directly introduced into the dialysis tank as a dialysis stock solution, the fine suspended solids in the waste liquid will settle in the dialysis tank, and surfactants and oil will adhere to the ion exchange membrane. This is undesirable because it lowers the separation efficiency of the solution, and to avoid this, the dialysis tank must be dismantled and cleaned and the ion exchange membrane itself must be replaced more frequently. In particular, the ion exchange membranes that are installed in large numbers in dialysis equipment are usually 0.12~
Since it is extremely thin, about 0.18 mm, and easily damaged, removing it and cleaning it requires extreme care, which is extremely time-consuming and troublesome work.

Conventionally, in order to avoid such inconveniences, attempts have been made to pass the waste liquid through a cloth before introducing it into the dialysis tank, but insoluble inclusions in the waste liquid are extremely fine solids, oil, surfactants, etc. Therefore, in order to remove solid inclusions, it is necessary to select a cloth material with a fine density, which increases excessive resistance and is prone to clogging, and the use of oil-based surfactants. At present, it is difficult to easily separate these insoluble inclusions, and separation of these insoluble inclusions requires a great deal of expense.

The present inventor conducted intensive research to solve the above-mentioned problems when separating and recovering acids and metal salts dissolved in metal surface treatment waste liquid by ion exchange membrane dialysis method. When the treated waste liquid is passed through the polystyrene fiber layer before being introduced into the tank, fine insoluble metals, metal oxide particles, surfactants, oil, etc. in the raw solution are effectively collected in the fiber layer. Therefore, it has been found that the recovery efficiency of the active ingredient in the subsequent dialysis recovery process can be maintained at a high level over a long period of time.

In addition, when passing the treated waste liquid through the polystyrene fiber layer, it is important to treat the fiber layer with a nonionic surfactant in advance.

Next, the results of an overexperiment conducted by the present inventor will be explained.

Height 10cm x length 10cm x width 2cm with openings on top and bottom
Four types of cotton, polystyrene fiber cotton, polypropylene fiber cotton, polyester fiber cotton, and glass fiber cotton, were filled into a rectangular cylindrical filtration device, and sulfuric acid alumite waste liquid (300 g of free sulfuric acid/
, aluminum sulfate 72g/, solid inclusions
25ppm nonionic surfactant 250ppm, oil 8ppm
) flows in at a flow rate of 3 cm/min and is discharged from the upper opening, passing continuously through the filtration device to filter out solid inclusions, surfactants, and oil contained in the waste liquid. The filtrated stock solution was transferred to a filter press Selemion dialysis device T-O type (strong basic anion exchange membrane dialysis device manufactured by Asahi Glass Co., Ltd.).
Sulfuric acid was recovered using 19 ion exchange membranes (effective membrane area: 3971 cm ² ).

Figures 1 to 3 show the relationship between the elapsed time of the waste liquid and the concentration of inclusions, surfactants, and oil in the liquid, and Figure 4 shows the relationship between the elapsed time of the waste liquid and the concentrations of inclusions, surfactants, and oil in the liquid, and Figure 4 shows the continuous dialysis of each of the above liquids as the dialysis stock solution. This figure shows the relationship between the elapsed time and the recovery rate of sulfuric acid when it is introduced into the apparatus and ion dialysis is performed. In each figure, curve 1 shows the characteristics when polystyrene fiber cotton, curve 2 shows the properties when polyester fiber cotton is used, curve 3 shows the properties when polypropylene fiber cotton is used, and curve 4 shows the characteristics when glass fiber cotton is used as the material.

As can be seen from Figures 1 to 3, when polystyrene fiber cotton is used as the material, it has a higher overcapacity for solid inclusions, surfactants, and oil in the waste liquid than when other fiber cottons are used. It is also clear that the long-lasting effect is excellent.

Furthermore, as shown in Figure 4, when sulfuric acid recovery is performed by ion dialysis using the superstock solution of the present invention, the recovery of sulfuric acid can be sustained for a long period of time with extremely high dialysis efficiency compared to other cases. It can be seen that the frequency of maintenance and overhaul of the dialysis cell can be significantly reduced.

Although this experimental example describes the case where an aluminum plate is alumite-treated, it has been confirmed that similar effects can be obtained with pickling process waste liquid in steel and etching process waste liquid of other metal plates.

In the present invention, the polystyrene fiber used to over-treat the waste fluid before introduction into the dialysis machine may be either cotton-like or mat-like. The key is to keep it.

In this case, polyoxyethylene surfactants, especially polyoxyethylene alkyl ethers or polyoxyethylene alkyl aenol ethers, are recommended as nonionic surfactants.

Next, examples of the present invention will be described.

Example 1 Waste liquid from sulfuric acid anodization treatment of aluminum plate (free sulfuric acid 300g/, aluminum sulfate 70g/insoluble solids 7ppm, nonionic surfactant 200ppm,
When recovering sulfuric acid in waste liquid using ion exchange membrane dialysis method using dialysis stock solution (oil content 2 ppm), a height 250 mm with openings at the top and bottom is used to collect the waste liquid before introducing it into the dialysis tank.
A cylindrical filter tank with an inner diameter of 70 mmφ is filled with polystyrene fiber cotton that has been treated with a nonionic surfactant (polyoxyethylene alkyl ether) 20 g/solution in advance.From the lower opening of the filter device, 3 cm/
The concentration of suspended solids in the stock solution at the outlet of the tank was only a trace, and the concentration of nonionic surfactant was 20 ppm. The oil content was 0.6 ppm, and the pressure loss was 0.02 Kg/cm ² .

After 30 days of continuous operation using this stock solution, we measured the concentrations of suspended solids, nonionic surfactants, and oil in the stock solution at the outlet of the filtration tank, and found that they were 0.5ppm, 23ppm, and 0.7ppm, respectively. No change,
Moreover, the pressure loss was 0.05Kg/cm ² .

In addition, the sulfuric acid recovery rate was determined when the stock solution was passed through a filter press Selemion dialysis device T-O type (strong basic anion exchange membrane dialysis device manufactured by Asahi Glass Co., Ltd., number of ion exchange membranes: 19, effective membrane area 3971 cm ² ). is 80
%, and it was possible to maintain almost the same recovery rate even after 120 days of continuous operation.

Example 2 Pickling waste liquid for pickling to remove rust from steel (8.5 wt% free sulfuric acid, 14.3 wt% ferrous sulfate, 28 ppm insoluble solids, 150 ppm nonionic surfactant, oil content)
When recovering sulfuric acid from the waste liquid by ion-exchange membrane dialysis using 3ppm) as the dialysis stock solution, the waste liquid before being introduced into the dialysis tank was introduced into the same filter tank as in Example 1, and the non-ionic interface was The inside of the filter device filled with polystyrene fiber cotton treated with an activator is 2.8cm/
When the solution was passed through the tank at a flow rate of 1 mm and continuously taken out from the upper opening, the concentration of suspended solids in the stock solution at the outlet of the overtank was only a trace, and the nonionic surfactant was
18ppm, oil content 0.5ppm, and pressure loss 0.03Kg/
It was warm in ^cm2 .

After 25 days of continuous operation using this waste liquid,
Suspended solids in the stock solution at the outlet of the filter tank
0.6ppm, nonionic surfactant 20ppm, oil content
There was almost no change at 0.6 ppm, and the pressure loss was 0.06 Kg/cm ² .

In addition, when the stock solution was passed through an ion exchange membrane dialysis device of the Selemion dialysis device T-O type similar to that in Example 1, the sulfuric acid recovery rate was 81%, and it remained almost the same even after 120 days of continuous operation. We were able to maintain a recovery rate of

Example 3 Metsuki factory pre-treatment etching waste liquid (free hydrochloric acid
7.0wt%, ferrous chloride 16.2wt%, insoluble solids
18ppm, nonionic surfactant 200ppm, oil content
6ppm) as the dialysis stock solution by ion exchange membrane dialysis to recover hydrochloric acid from the waste solution.
A cylindrical filter tank with a diameter of 250 mm and an inner diameter of 75 mm was filled with polystyrene fiber mats that had been treated in advance with a 1.5 wt% solution of a nonionic surfactant (polyoxyethylene alkyl phenol ether), and water was poured into the filter device. 3.1 from the upper opening after
When the waste liquid was introduced at a high flow rate of cm/min and taken out from the lower opening, the concentration of suspended solids in the stock liquid at the outlet of the filter tank was only a trace, and the nonionic surfactant was
18ppm, oil content 0.5ppm, and pressure loss is 0.02
It was Kg/ ^cm2 .

Using this waste liquid, we measured the concentrations of suspended solids, nonionic surfactants, and oil in the stock solution at the outlet of the afterfilter after 35 days of continuous operation, and found that they were 0.5 ppm, 20 ppm, and 0.6 ppm, respectively. figure,
Moreover, the pressure loss was 0.04 Kg/cm ² .

In addition, when the stock solution after filtration was passed through the same Selemion dialysis device T-O type as in Example 1, the recovery rate of hydrochloric acid was
The recovery rate was 85%, and almost the same recovery rate could be maintained even after 135 days of continuous operation.

[Brief explanation of the drawing]

Figures 1 to 3 show the relationship between the elapsed time of the waste liquid and the concentration of inclusions, surfactants, and oil in the liquid, and Figure 4 shows the relationship between the elapsed time of the waste liquid and the concentrations of inclusions, surfactants, and oil in the liquid, and Figure 4 shows the continuous dialysis of each of the above liquids as the dialysis stock solution. This figure shows the relationship between the elapsed time and the recovery rate of sulfuric acid when it is introduced into the apparatus and ion dialysis is performed. In each figure, curve 1 shows the characteristics when polystyrene fiber cotton, curve 2 shows the properties when polyester fiber cotton is used, curve 3 shows the properties when polypropylene fiber cotton is used, and curve 4 shows the characteristics when glass fiber cotton is used as the material.

Claims (1)

[Claims] 1. When separating and recovering active ingredients in metal surface treatment waste liquid containing sulfuric acid or hydrochloric acid or their salts by ion exchange membrane dialysis method, nonionic surfactant treatment is performed before introducing the treated waste liquid into the dialysis tank as a dialysis stock solution. A method for treating metal surface treatment waste liquid, characterized by passing it through a treated polystyrene fiber layer.