JPS59120286A - Treatment of waste water containing fluorine component - Google Patents

Abstract

PURPOSE:To easily treat the titled waste water at a low cost, by adjusting the pH of the waste water containing a fluorine component by the addition of gypsum dihydrate in a specified amount to it to form calcium fluoride, separating the formed calcium fluoride by filtration, and then bringing the resulting waste water into contact with calcium fluoride crystals. CONSTITUTION:Waste water 2 containing a fluorine component together with gypsum dihydrate 3 in an amount above 10 times the quivalent amount of said contained fluorine is sent to a reaction tank 1, and its pH is adjusted to 4-5.5 by the addition of an aid 4 such as hydrochloric acid to form calcium fluoride. Slurry 9 discharged from the reaction tank 1 is filtered by a filtering machine 6 to remove calcium fluoride 7 by filtration. A filtrate 10 is sent to a column 11 packed with leaching substance such as calcium fluoride crystals 5 or fluoric acid, to precipitately remove F ion in the filtrate 10 as calcium fluoride. The resulting treated water 8 is drained. The concentration of fluorine in said treated water 8 is below 10mg/l.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater containing fluorine components.

Wastewater containing fluorine-based components is generated from the aluminum industry, ceramic industry, fertilizer industry, plating industry, semiconductor industry, waste gas wet cleaning wastewater from waste incineration plants (so-called smoke washing wastewater), etc. 5 Wastewater from these facilities. The fluorine pond contains silicon, etc., and the fluorine form KU F- (*KS
Living: 6″ etc. □ is also thinking) L.

Treatment methods for wastewater containing such fluorine-based components include calcium coagulation method using Ca salts such as CaC42 and Ca (OH)2, iron and aluminum coagulation method, and coagulation sedimentation method such as phosphoric acid ano and tite methods. In addition to methods, there are also physicochemical treatment methods such as adsorption methods, ion exchange methods, electrolytic methods, and reverse osmosis methods.

However, the calcium coagulation method (d) has an insufficient removal rate of fluorine and high Ca salts such as Cc'Cl2r Ca'' (0r()2).
Cost increases and □ waste sludge increases.

Furthermore, although the phosphoric acid apatite method has a high removal rate, the cost of using phosphoric acid is high. In addition, all of the physicochemical treatment methods have the disadvantage that they require dust removal by concentrating and removing fluorine, and finally reprocessing of the concentrated fluorine.

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for the logical separation of wastewater containing fluorine-based components that is simple in process and extremely low in treatment cost. It is.

That is, in the present invention, gypsum trihydrate is added to wastewater containing fluorine components in an equivalent ratio of 1'0 times or more to the amount of fluorine contained, and the pH is adjusted to 40-40.
5.5 to produce poorly soluble calcium fluoride; a step of filtering the wastewater that produced calcium fluoride; and a step of removing the wastewater that produced calcium fluoride or calcium fluoride by furnace. The method is characterized by comprising a step of bringing calcium fluoride crystals or a so-acid leading material into contact with the liquid. ' □ In addition, the process of producing poorly soluble fluoride and the process of omitting the contact between fluoride and calcium fluoride are carried out in the same reaction. To the removed filtrate! 1. Contacting calcium fluoride crystals, etc.
A further embodiment is to filter the filtrate by contacting it with calcium fluoride crystals or the like.

The present invention will now be described with full reference to the v4 implementation. No. 191 provides an example of a method for treating wastewater containing fluorine components. In this treatment method, fluorine-containing component-containing wastewater 2 is placed in a reaction tank 1, gypsum trihydrate 3. and an acid 4 such as hydrochloric acid, and furthermore, calcium fluoride crystals such as fluorite or an acid-leached product thereof (hereinafter referred to as calcium fluoride crystals 5) are supplied at the start of operation.

Dihydrate ff3 is CaC72, CaCO3, Ca(Of
Calcium fluoride (CaF2), which reacts with fluorine and is refractory to calcium fluoride (CaF2)
Generate all. At this time, the amount of gypsum trihydrate 3 added is 10 times or more than the actual amount of fluorine contained in the waste water 2, preferably 10 times to 50 times. The reason for this is that if the amount is less than 10 times, hardly soluble calcium fluoride is hardly produced, and if the amount added is too large, the effect will be saturated.

Acid 4 has a pH of 4.0 to 5.5 within the reaction tank 1, preferably P
Added to maintain H4.5±0.5. The reason for maintaining this range is that when the pH is less than 4.0, fluorine is difficult to form into I (F or I (F2' and dissociate as F-))
This is because if it exceeds 1 (5, s), OH- interferes with the dissociation of F-, making it difficult to form calcium fluoride.

On the other hand, calcium fluoride crystals 5 are supplied to deposit calcium fluoride on this surface.

That is, in the present invention, gypsum trihydrate 3 is added. By this,
Slightly soluble calcium fluoride (solubility: 4.9 x 1.0) (r) is produced by the reaction of Ca2+ and F-. Ca2 + h supersaturated F- coexists.Therefore, these ions are brought into contact with calcium fluoride crystals 5,
Calcium fluoride is deposited on its surface. In the case of Jin,
Leaching the surface of calcium fluoride crystals with sulfuric acid, hydrochloric acid, etc. is particularly effective because a new active surface is formed in the amount of crystallized milk. In this case, about 30 minutes is sufficient for the residence time in the reaction tank 1.

Next, the slurry containing calcium fluoride produced in the reaction tank 1 is filtered by a filter 6. A portion 7 of the furnace-separated calcium fluoride is circulated to the reaction tank 1, and the remaining portion 7' is recovered. In addition, the treated water 8 from which calcium fluoride was removed by furnace was
Exhausted from the system.

According to this treatment method, resolvable calcium fluoride is generated in the industrial water gypsum 3 and calcium fluoride is completely precipitated on the surface of the calcium fluoride crystals 50, so that the fluorine concentration in the treated water 8 can be lowered. can.

Next, the pond treatment method of the present invention shown in FIG. 2 will be explained. In this treatment method, wastewater 2 containing fluorine components is placed in a reaction tank 1, and Sansui □ gypsum 3 is added at an equivalent ratio of 10 to the amount of fluorine contained in the wastewater.
Add more than twice the amount and then add acid 4 to pi-14,,O~
5.5 to produce poorly soluble calcium fluoride.Then, the slurry 9 discharged from the reaction tank 1 is filtered by a filter 6, and the calcium fluoride z is removed by a furnace. Calcium fluoride 7
Pe, 16, which has been removed by furnace, enters the packed tower 1: ◎The packed tower 11 is filled with calcium fluoride crystals 5 or its acid-leached product, and the p liquid comes into contact with it. L in the p solution: 6F1 is precipitated and removed as calcium fluoride. The treated water hVc from which mainly calcium heptafluoride has been removed has very little fluoride, which can be discharged out of the system.

□Next, the pond treatment method of the present invention shown in FIG. 3 will be explained. This treatment method (bow 5, put fluorine component-containing wastewater 2 in reaction tank 1, add industrial water gypsum 3 to the equivalent ratio of fluorine content in the wastewater to 1)
Add 0 times the above and then add 4 acids to adjust the pH to 4.0 to 55.
and produces soluble calcium fluoride. Next, the slurry 9 discharged from the reaction tank J is filtered by a filter 6, and the calcium fluoride 7 is removed by the furnace. Calcium fluoride 7%
(J removed furnace liquid io enters the addition tank 12 ◎Addition tank 1
In No. 2, calcium befluoride crystals 5 or acid leading products thereof are added, and when the P solution comes into contact with the calcium befluoride crystals, F- in the F solution is precipitated as calcium fluoride. Then, the rice oki liquid is put into a filter 13 to recover calcium fluoride 7 separately.

Furthermore, the treated water 8 from which the calcium fluoride 7 has been removed by furnace contains extremely little fluorine, which is discharged out of the system.

Next, experimental examples and examples of the present invention will be explained.

As raw water for the example, M L fc synthesis solution (F-=20 m9/l, S
iF b'-=20''9/l-.

Total F amount = 40 mg//l) was tested, gypsum was added at an equivalent ratio of 1.5, 10, 30.50 to fluorine in the raw water, and HCl or NILOH was added to pHt 3.5, 4.0.
, 4.5, 5.0, 5.5.

60 to precipitate calcium fluoride, which was then filtered and the fluorine concentration remaining in the filtrate was measured. The results are shown in Table 1. The amount of raw water was 1 t, and the reaction time was 30 minutes. Table 1 (Residual fluorine concentration mtit) Table 1 (Residual fluorine concentration, mtit)
4.0 to 5.5, the residual fluorine concentration is 1. Om9/ is below, indicating that the defluorination effect is excellent75).

Example 1 The raw water used is smoke washing wastewater A from a garbage incineration plant (pH 7.8).

A fluorine treatment experiment was conducted using the apparatus shown in FIG. 1 using a fluorine concentration of 38 rrv't.

In this case, as experiment A1, 1 part of industrial water gypsum is added to the raw water xoooom.
．． 72g (equivalent ratio x 10) was added, and at the same time fluorite (100
Add 61 of Metsuyunoyasu), HC4K and PHf
The mixture was stirred and mixed for 30 minutes while adjusting the 4.5 K it4. After that, constant pressure filtration (-4,00+n+n
, Hg.

The paper was made of Toyosawa paper 2), and the fluorine concentration in the P solution was measured. ◇ Also, as experiment 2, fluorite 6 was used instead of fluorite in experiment 1.
0j! I Q W, /V %H2SO4,,300
A similar experiment was carried out using the resulting cake, which was treated with m and l, then filtered and washed with water. As a result, the fluorine concentration in the liquid was 5.2 mg/l for B1 and 5.0 mg/l for B2.

Example 2 A continuous treatment experiment was carried out with the apparatus shown in FIG. 2, using waste incineration plant washing smoke return water A (pH 7.8v, fluorine concentration 381n?'t) as raw water. In this case, the amount of raw water treated is 51/
', the amount of industrial water gypsum added is 8.58 g/hour (equivalent ratio Xl0
).

Reaction tank pH 4,5±0.2. Residence time is 30 minutes, the filter is a Nutsche type constant pressure filtration (-400 mmHg, P paper is Toyo F Kamiya 2), and the packed tower is a calcium fluoride packed part 200.
m1. Calcium fluoride crystals were ground fluorite (14 mesh to 20 mesh) and set to 5V=25.

As a result of an 8-hour continuous experiment, the fluorine concentration at the inlet of the packed column was 7.6.
7n9/l, fluorine concentration at the same outlet (treated water) 5.3 r
It was ng/l.

Example raw water used was waste incineration factory smoke return water B (pH 7.6°, fluorine concentration 191+y/z). A patch treatment experiment was conducted using the apparatus shown in FIG.

Susuwachi raw water 1000m/! 8.65 g of industrial water gypsum (equivalent ratio xi, o) was added to
．． After reacting for 30 minutes while maintaining the temperature at 2-), the mixture was filtered in the same manner as in Example 1. Next, 800ml of this E liquid is a crushed product of 1K fluorite (
100 mesh pass) was added to 50 g' of the mixture, mixed for 30 minutes, and then filtered in the same manner as before.

When we analyzed the fluorine concentration of the p liquid before adding fluorite and the final treated water, we found that the former was 7.1 points.

The latter was 5.4 me/l.

In the present invention, gypsum is added, but similar effects can be obtained by using gypsum hemihydrate or gypsum anhydrite.

Furthermore, in the examples, experimental results were described for synthetic liquids and smoke washing wastewater, but it goes without saying that the present invention can also be applied to fluorine-containing wastewater from ponds.

As explained above, according to the present invention, fluorine in wastewater can be efficiently and highly treated, and moreover, the produced calcium fluoride can be efficiently reused in one yield.

[Brief explanation of the drawing]

FIGS. 1 to 3 are explanatory diagrams showing different methods of treating fluorine-containing component-containing wastewater according to the present invention. 1... Reactive species, 2... Fluorine component-containing wastewater, 3.
・Gypsum, 4... Acid, 5... Calcium fluoride crystals (or their acid leached products), 6... Distillation machine, 7゜7
'... Calcium fluoride, 8... Treated water, 9... Nura l Hano 0... r=, 1... Packed tower, 12... Addition tank, 13... P: iM Machine. Applicant's agent Patent attorney Takehiko Suzue No. 1 Kuwa No. 2

Claims (4)

[Claims] (1) Equivalence ratio of fluorine content in wastewater containing fluorine components: 1
A step of adding 0 times or more of gypsum trihydrate and maintaining the pH at 40 to 55 to produce IAIrm calcium fluoride;
The process comprises a step of filtering wastewater that has produced calcium fluoride, and a step of bringing calcium fluoride crystals or an acid-leached product thereof into contact with the wastewater that has produced calcium fluoride or a solution from which calcium fluoride has been removed by furnace. A method for treating wastewater containing fluorine components, characterized by: (2) The process of forming a difficult-to-produce calcium fluoride mixture and the process of bringing calcium fluoride crystals or an acid-leached product thereof into contact with the wastewater that produced calcium fluoride are carried out in the same reaction tank. Claim 1: A method for treating wastewater containing fluorine components. (3) After the step of producing poorly soluble calcium fluoride, a step of filtering the wastewater that produced calcium fluoride is carried out,
After that, the filtrate from which calcium fluoride has been removed by furnace is placed in a packed tower filled with calcium fluoride crystals or acid-leached products thereof and brought into contact with the fluorine-containing material according to claim 1. A method for treating wastewater containing system components. (4) After the step of producing poorly soluble calcium fluoride, a step is carried out in which the P solution from which calcium fluoride has been separately removed is placed in an addition tank and brought into contact with calcium fluoride crystals or their acidified products. 2. The method for treating fluorine-containing wastewater according to claim 1, further comprising the step of filtering the wastewater and removing calcium fluoride in a separate furnace.