JPH10249362A - Treatment of manganese-containing waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of inexpensively and conveniently and surely removing manganese from a waste water containing the manganese dissolved as ion or the manganese suspended as compd. particles or both. SOLUTION: In this waste water treating method, a ferric ion source is added so that an iron ion may be 50-200g per 1m<3> manganese-containing waste water, and pH is adjusted to 5.0-9.0, thereafter, a generated precipitated matter is subjected to a magnetic separation in 9-25kOe magnetic field strength. There are ferric chloride, ferric sulfate, ferric nitrate and ferric hydroxide as the ferric ion source to be added. There is no hindrance even if ferrous chloride, ferrous sulfate, ferrous nitrate and ferrous hydroxide are added, but in this case, it is necessary to convert the ferrous ion to the ferric ion by oxidation and to adjust pH to a prescribed value after adding the iron ion source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for removing manganese from manganese-containing wastewater.

[0002]

2. Description of the Related Art Mine wastewater from mines and smelters and other factories often contain manganese, and the removal of manganese is important from the viewpoint of environmental protection and safety of living environment. From is extremely important. The emission standard for soluble manganese is 10 ppm.

Conventionally, methods for removing manganese from these wastewaters include a hydroxide method, a sulfide formation method, a ferrite formation / magnetic separation method, an ion exchange method / adsorption method, and an iron powder method. The appropriate method is selected according to the nature,
Has been applied.

[0004] However, in order to comply with the above emission standards, there is a case where the treatment is insufficient only by removing the soluble manganese. For example, wastewater from mines that process ore containing ore containing manganese minerals, or from mines that contain manganese minerals in gangue, include solid solution in very fine solid suspensions in addition to soluble manganese. May contain manganese. This is because naturally occurring manganese minerals contain a large amount of oxide minerals and are easily powdered.

[0005] In order to remove manganese by applying the hydroxide method / coprecipitation method to such wastewater, an iron salt as a coprecipitant, a neutralizing agent, and a coagulant are required in a large amount. Fine artifacts float and leak easily, often resulting in insufficient manganese removal. In such a case, manganese is eluted from the leaked manganese mineral, and the once removed soluble manganese is likely to exceed the emission standard again. In order to prevent this, a large sedimentation tank must be used to prevent the leakage of fine artifacts, or a corresponding filter must be used. It becomes difficult.

[0006] The sulfide generation method has a similar problem.
The ion exchange / adsorption method is not suitable for removing manganese contained as a solid suspension. When manganese is combined with iron oxides such as magnetite to form a solid suspension, it can be magnetically separated as it is.However, when dissolved manganese is also present, it is necessary to generate ferrite. Need large quantities.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide manganese dissolved as ions.
Alternatively, it is an object of the present invention to provide a method capable of inexpensively, simply and reliably removing manganese from wastewater containing manganese suspended as compound particles or both.

[0008]

According to the method of the present invention, in order to achieve the above-mentioned object, a ferric ion source is added so that iron ion is 50 to 200 g per 1 m ^{3 of} manganese-containing wastewater, This is a wastewater treatment method characterized in that the pH is adjusted to 5.0 to 9.0, and then the generated artifacts are magnetically separated at a magnetic field intensity of 9 to 25 kOe. As a ferric ion source to be added, ferric chloride, ferric sulfate, ferric nitrate,
Ferric hydroxide and the like. There is no problem with ferrous chloride, ferrous sulfate, ferrous nitrate, and ferrous hydroxide, but in this case, after adding the iron ion source, the ferrous ion is oxidized to ferric ion, and then It is necessary to adjust the pH to a predetermined value.

Further, when iron ions are contained in wastewater from the beginning, it can be used. However, if the iron ions contained are ferrous ions, they must be oxidized to ferric ions before the formation of artifacts.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, first, ferric ion is added. This is for co-precipitating dissolved manganese in iron hydroxide and for aggregating manganese present as a fine solid suspension.

The amount of addition is appropriately adjusted according to the properties of the waste water. According to the studies by the inventors, it is appropriate that the amount of iron ions be 50 to 200 g per 1 m ^{3 of the} manganese-containing waste water.
If the amount is less than this, the precipitate of iron hydroxide becomes colloidal and magnetic adhesion becomes difficult, so that it is difficult to make the manganese concentration lower than the drainage standard.

On the other hand, when the amount increases, the reagent cost increases and the amount of magnetically deposited deposits increases. Next, the pH is adjusted with an alkaline agent such as slaked lime to cause precipitation of ferric hydroxide. The pH may be such that ferric hydroxide precipitates, but is preferably about 7 in order to discharge the treated water as it is.

[0013] The resulting artifact is discharged out of the system by magnetic separation.
That is, the ferric hydroxide is recovered as a magnetic substance. At this time, dissolved co-precipitated manganese and coagulated solid manganese compound are simultaneously recovered.

In the method of the present invention, since the obtained iron precipitate becomes ferrite, the precipitate is removed by magnetic separation.

[0015]

Next, the present invention will be further described with reference to examples.

(Examples 1 to 9) A manganese mineral was contained in gangue, and treatment was performed under the following conditions using soluble manganese and fine suspended solids (total manganese concentration: 14.7 ppm) in well water. Ferric chloride was used as a ferric salt, and iron was added so as to be 50 ppm to 200 ppm.
Next, slaked lime was added to adjust the pH to 7, and precipitation of iron hydroxide was caused to perform magnetic separation. Using a high gradient magnetic separation machine as a magnetic separation device, the magnetic field strength was changed from 9.9 kOe to 22 kOe.
e. Table 1 shows the manganese concentration of the treated water.

[0017] (Examples 10 to 13) Treated water was obtained in the same manner as in Example 5 except that the pH was changed as shown in Table 2. Table 2 shows the manganese concentration of the treated water.

[0018] (Comparative Examples 1 to 5) As Comparative Examples, the results when the same wastewater as in the example was treated with only ferric ion and a coagulant are shown. The processing conditions are as follows. Ferric chloride was used as a ferric salt, and iron was added so as to be 50 ppm to 200 ppm. After adjusting the pH to 7 with slaked lime to generate a residue, 2 ppm of an anionic organic polymer flocculant was added as a flocculant. After adding the drug and stirring, the mixture was allowed to stand for 1 hour, and then the supernatant was collected and analyzed for manganese. Table 3 shows the analysis results of the supernatant (treated water).

[0019] (Comparative Examples 6 to 9) Treated water was obtained in the same manner as in Example 5 in Table 3 except for the pH and the amount of ferric ion added. Table 4 shows the manganese concentration of the treated water.

[0020]

[0021]

According to the method of the present invention, the new wastewater standard can be satisfied with a very small amount of reagent compared to the comparative example. In addition, since the amount of the reagent is small, the amount of deposits (magnetism) obtained is also small, and post-treatment is easier than the deposits obtained by the coagulation precipitation method. Thus, the method according to the present invention is highly effective for manganese-containing wastewater.

Claims (5)

[Claims] 1. A ferric ion source is added to 1 m ^{3 of} manganese-containing waste water so that the iron ion content is 50 to 200 g, the pH is adjusted to 5.0 to 9.0, and then, the generated residue is added. A method for treating manganese-containing wastewater, wherein the manganese-containing wastewater is subjected to magnetic separation. 2. The method according to claim 1, wherein the ferric ion source is at least one of ferric chloride, ferric sulfate, ferric nitrate, and ferric hydroxide. Wherein iron ions to manganese containing wastewater 1 m ³ is added ferrous ion source so that 50 to 200 g, to oxidize the ferrous ion to the ferric ion, the pH 5.
A method for treating manganese-containing wastewater, comprising adjusting to 0 to 9.0 and then magnetically separating the generated artifact. 4. The method according to claim 3, wherein the ferrous ion source is at least one of ferrous chloride, ferrous sulfate, ferrous nitrate, and ferrous hydroxide. 5. The method according to claim 1, wherein the magnetic force is selected at a magnetic field intensity of 9 to 25 kOe.