JPH01171687A - Treatment of lead-containing waste water - Google Patents

Abstract

PURPOSE:To reduce the content of Pb in waste water effectively by introducing waste water contg. Pb and water-soluble flux into a precipitation tank and adsorbing Pb particles and water-soluble flux in the liquid to active carbon by passing the supernatant water of the waste water through an active carbon filter. CONSTITUTION:Supernatant liquid of a precipitation tank 22 is fed to a relay tank 23 connected to a water washing liquid tank 27. The supernatant liquid of the waste washing water tank 27 is also fed to the relay tank 23. Pb particles having >=ca. 5mum particle size are removed before Pb-contg. waste water passes the relay tank 23, and the water freed of such Pb particles is fed to an active carbon filter 24. Water-soluble flux consists of org. substances such as glutamic acid, or salts thereof, etc., which are adsorbed to the active carbon filter 24. Metal particles of Pb, Sn, etc. having >=ca. 1mum particle size are removed also by the filtration effect of the active carbon filter. Pb particles and gel of intermediates having ca. 1mum particle size are removed by a precision filter 25, and finer particles and ionic components are removed by a chelate resin filter 26.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating lead-containing wastewater generated in the manufacturing process of electronic components.

Figure Takasue 11 For electronic parts, external leads and external electrodes are soldered to ensure good soldering properties. This solder plating is formed by dipping the part to be plated, such as an external lead, into molten solder, but if the part to be plated is oxidized or contaminated with oil, the solder will not adhere well (soldering will be difficult). Sexuality varies (
Therefore, flux is applied to the area to be plated before plating.

Electronic components that have been soldered are cleaned to remove residual flux.

Conventionally, organic solvents have been used as cleaning liquids, but organic solvents are complicated to handle because their atmospheric concentration must be controlled and they are flammable.

Therefore, water-soluble flux is used to remove residual flux after soldering.

FIG. 2 shows an example of the solder plating process. In the figure, 1 is the second flux coating process, 2 is the first μ solder dipping process, 3 is the second flux coating process, 4 is the second soldering process, and 5, 6, 7, and 8 are the 3rd soldering process, respectively. 0th to 3rd washing steps, 9 is a draining step, and 10 is a drying step.

The electronic components are first supplied to the first flux application process 1, where flux is applied to the part to be plated, and in the first Uda Disop process 2, it is broken into molten solder.

The open area is dipped and soldered. In the second flux application step 3, flux is applied again to the part to be plated, and in the second solder dispersion step 4, the solder is sufficiently applied to the parts where the solder has not been sufficiently adhered, and a plating finish is performed.

During the 0th to 3rd water washing steps 5 to 8, the remaining flux is applied to the electronic components. The water washing steps are provided according to the moving speed of the electronic component, and the number T is set so that even if the washing time in each washing step is short, sufficient washing can be achieved in the end. The sewage generated in each washing process 5-8 is stored in sewage tanks 11-14 provided for each washing process. The electronic components that have been washed with water are drained by air blowing or the like in a draining step 9, and then dried with warm air in a drying step 10.

By the way, the wastewater generated in the washing steps 5 to 8 is wastewater containing a water-soluble flux component and lead, and is filtered and diluted so as to satisfy the standard value of lead, and then treated as wastewater.

Figure 3 shows an example of the treatment process for wastewater containing lead.
In the figure Il~! 4 is a sewage tank! 5 is the water supply reception department;
I6 is a softener, 17a to +7c are valves, 18 is an industrial waste storage tank, 19 is a well water pump, 20 is a reserve tank, and 21 is a filtration device.

- The water taken in from the E water receiving part 15 is softened by +6
The water is then branched and supplied to the 0th to 3rd sewage tanks 11-14 through valves 17a and 17b, respectively. Since the sewage in the 0th stage sewage tank 11 has a high interstitial content of 16 degrees, precipitation is repeated, and the solids and high lr 5 degrees wastewater are stored in the industrial waste storage tank +8. 1st to 3rd sewage tank 1
The supernatant liquids of Nos. 2 to 14 are each supplied to a preliminary tank 20, and well water pumped up by the water pump 19 is supplied to this preliminary tank 20 via a valve 17c, and furthermore, the supernatant liquid of this preliminary tank 20 is filtered. It is supplied to the device 21.

Each valve +7a, +7b is controlled so that the concentration of 6 tanks - 14.20 becomes the specified value, but in the 0th sewage tank 1
No. 1 has a lead concentration of about 5 ppm, so it is drained outside and disposed of as industrial waste. On the other hand, 0.21) l) II with 15 degrees of lead in the 1st to 3rd sewage tanks 12 to 14 tap water
Since it can be suppressed to a certain extent, it is further diluted with well water in the preliminary tank 20 and filtered into the filtration device 2! The solid content of lead is removed and the lead concentration is reduced to less than Lll, making drainage possible.

In this way, through filtration and dilution, it is possible to drain water while satisfying lead regulations, but in order to keep the lead concentration low,
A large amount of water, such as tap water, was required.

In addition, even if the lead 1O content is low, the amount of lead discharged is cumulative and there is a concern that it may affect the environment over a long period of time.

Furthermore, since the zero-level sewage must be treated as industrial waste, there is also the problem of increased treatment costs.

The present invention has been proposed in view of the above-mentioned problems, and leads lead-containing wastewater containing lead and water-soluble flux to a settling tank, and passes the precipitate into an activated carbon filter. The above-mentioned problems have been improved by treating lead-containing wastewater by passing the supernatant liquid from the tank and removing the lead particles and water-soluble flux remaining in the wastewater by adsorption to activated carbon.

IL inhibition An embodiment of the present invention will be described below with reference to FIG.

In the figure, the same reference numerals as in FIG. 3 indicate the same parts, and the explanation will be omitted. In the figure, 22 is a settling tank, 23 is a relay tank, 24 is an activated carbon filter, 25 is a precision filter, 2B is a chelate resin filter, and 27 is a half [fl
This shows a cleaning waste tank that stores waste water generated when cleaning waste and equipment. Further, +7d and 17e indicate valves.

The clean water taken in from the clean water receiving part 15 is softened A I
Ei, through the valve 17a, the O to third sewage tanks H to 1
4 respectively. The supernatant liquids from tanks 6-14 are supplied to a precipitation tank 22, where large-diameter lead is precipitated and can be recovered as solid matter. The lead concentration in the wastewater of No. 0 pollution tank 11 is 0.3
ppm, the lead concentration in the first to third sewage tanks 12 to 14 is around 0.2 ppm, and about 30% are particles with a particle size of 5 μm or less, and 1 to 3.
About 65% of the particles are 5 μm in size, and about 5% are fine particles of 1 μm or less and ionic particles. The supernatant liquid of the settling tank 22 is supplied to a relay tank 23, and a washing waste liquid tank 27 is connected to this relay tank 23, and the supernatant liquid is also supplied thereto.

Up to the relay tank 23, lead having a particle size larger than about 5 μm is removed and supplied to the activated carbon filter 24.

Water-soluble flux is mainly composed of organic substances such as glutamic acid and glutamate salts, and also contains urea and tin.
The activated carbon filter 24 adsorbs these A-mechanical needles, and at the same time can remove metal particles such as lead and soot having a diameter larger than about 1 μm through a filtering action.

Further, a precision filter 25 removes lead particles and gel-like intermediates of about 1 μm, and a chelate resin filter 26 removes fine particles and ionic components.

In this way, lead and water-soluble flux components are precipitated and adsorbed.
When diluted, the lead concentration is 0.0 from the chelate resin filter 26.
Wastewater with a concentration of 6 ppm or less can be obtained. This drainage is barrel 17
d, by opening and closing operation of 17e, discharge or
Although it is recycled to the sewage tank It-14, by repeating the process of circulating for a predetermined time and then discharging a predetermined amount, the lead concentration can be reduced to 0.04 pp1 or less.

According to the present invention, the effects shown in Table 1 were confirmed.

Table 1 As shown, according to the present invention, not only can the lead concentration be reduced to two-thirds of the conventional level, but also the absolute lead emission can be reduced as the reflux time becomes longer. However, if the temperature is refluxed for 24 hours, the reduction can be reduced to 1/6 of the conventional level.
It can be reduced to 15.

Incidentally, in the present invention, a more remarkable effect can be obtained if the above steps are connected in multiple stages as one unit.

As described above, according to the present invention, the intercalated wastewater containing lead and water-soluble flux is introduced into the settling tank, and the supernatant liquid is passed through the activated carbon filter, thereby removing the lead particles remaining in the wastewater. Since the water-soluble flux is adsorbed, lead-containing I in the waste liquid to be drained is reduced, and the waste liquid can be recycled.

As a result, the amount of water used can be reduced, and lead emissions can also be reduced, greatly reducing the impact on the environment.

Furthermore, solid materials as industrial waste can also be treated centrally, reducing processing costs.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a method according to the present invention, FIG. 2 is a process diagram illustrating a solder plating process, and FIG. 3 is a diagram illustrating an example of a conventional method for treating lead 3 wastewater. 22... Sedimentation tank, 24... Activated carbon filter. Sumi] Illustration 2

Claims (1)

[Claims] Lead-containing wastewater containing lead and water-soluble flux is led to a sedimentation tank, and the supernatant liquid of the sedimentation tank is passed through an activated carbon filter to remove lead particles and water-soluble flags remaining in the wastewater by adsorption to the activated carbon. A method for treating lead-containing wastewater, characterized by: