JPS583968B2 - aluminum gun - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying an aluminum-containing liquid by removing organic substances and other impurities from the aluminum-containing waste liquid.

Examples of aluminum-containing waste liquids include metal surface treatment waste water and soil liquid recovered from acid treatment of tap water sludge.

There are two types of metal surface treatment wastewater: acidic wastewater and alkaline wastewater. Acidic wastewater includes high-concentration renewal wastewater and cleaning wastewater, which has a low concentration but a large amount of drainage. Alkaline wastewater also includes high-concentration renewal wastewater and high-concentration renewal wastewater. There is cleaning wastewater with low concentration.

When attempting to recover these wastewaters, problems arise from coexisting contaminants such as suspended solids, oil, grease, iron ions, and other organic substances, which must be removed.

In addition, aluminum hydroxide is contained in clean water sludge, and when dewatering this sludge, the aluminum hydroxide in the sludge is eluted with sulfuric acid in advance to improve dewatering properties, and the eluted aluminum hydroxide is There is an example of reusing the collected soil as recovered soil, but this recovered soil contains a considerable amount of colored organic matter and iron ions, giving it a reddish-brown color.
Removal of this colored organic matter is necessary for reuse.

The object of the present invention is to purify aluminum-containing waste liquids by effectively removing impurities in various aluminum-containing waste liquids, thereby making them convenient for reuse.

In the present invention, after substantially removing free acid or alkali in aluminum-containing waste liquid, an aluminum precipitant is added to convert some aluminum in the liquid into precipitate, and the precipitate is removed. It is characterized by separation and removal, and at this time, if iron ions are present in the liquid, most of the ferric ions are precipitated by aeration and separated and removed together with the aluminum precipitate.

Methods for removing free acid or alkali in the liquid in the present invention include chemical neutralization, ion exchange membrane method, ion exchange resin method, etc. After removing acid or alkali in this way, aluminum is added. As the precipitating agent, an alkaline agent is used when the liquid is acidic, and an acidic agent is used when the liquid is alkaline.

In addition, in producing aluminum precipitate, from the viewpoint of purifying the aluminum-containing liquid, it is necessary to hydrolyze and precipitate only a portion of the aluminum salts contained in large amounts in the liquid. , Impurities such as suspended solids, ferric ions, and organic chromaticity in the liquid are adsorbed to the resulting precipitate to recover most of the aluminum salt.

Furthermore, methods for separating and removing precipitates that have adsorbed impurities in the liquid include sedimentation, flotation, filtration, and centrifugation.
In addition, membrane separation methods using ultrafiltration membranes, microporous membranes, or media made of metal hydroxides, oxides, organic compounds, etc. formed on porous, water-permeable supports can also be effectively utilized. be able to.

Next, embodiments of the present invention will be described based on the drawings.

In FIG. 1, an acidic aluminum-containing waste liquid 1 containing sulfuric acid is introduced into an anion exchange membrane electrodialyzer A, where sulfuric acid 2 is separated and discharged from the system, thus substantially removing free acid. The resulting liquid 3 is sent to cell B equipped with an ultrafiltration membrane at a pressure of 1 to 5 kgf/cm2, but midway through, a caustic soda solution 4 is injected to convert some of the aluminum in the liquid into hydroxide. The liquid is converted to adsorb impurities in the liquid, and if necessary, a coagulation aid such as a polymer electrolyte is further added to generate aggregates.

The precipitate-containing slurry 5 concentrated in the cell B equipped with the ultrafiltration membrane and the purified liquid 6 that has passed through the membrane are each discharged to the outside of the system.

The second illustrated example is an embodiment related to the purification of recovered sand sludge through acid treatment of clean water sludge, in which free acid is substantially removed by injecting caustic soda solution 4 into the collected sand sludge 7. In addition, some aluminum in the liquid is hydrolyzed to generate a precipitate, and then when the liquid contains iron ions or easily decomposable organic substances, it is introduced into the aeration device C and the air 8 etc. Aerating with oxidizing gas for a required period of time oxidizes ferrous ions in the liquid to generate ferric precipitates, and also decomposes organic matter to partially form aluminum hydroxide precipitates and impurities in the liquid. While adsorbing ferric precipitates and the like, the liquid 9 is added with a coagulation aid 10 if necessary, and is fed under pressure to a cell D equipped with a porous water-permeable support at a pressure of 1 to 5 kpf/cm2.

In Cell D, precipitates in the liquid adhere to the surface of a porous water-permeable support with a size of about 0.1 to several microns, forming a kind of filtration membrane. remove impurities,
The concentrated liquid 5 and the membrane-permeated purified liquid 6 are each discharged to the outside of the system.

Note that when the aluminum-containing waste liquid contains alkali, a cation exchange membrane electrodialysis device may be used in place of the anion exchange membrane electrodialysis device A in the first illustrated example, and in each illustrated example, a cation exchange membrane electrodialysis device may be used. It is preferable to use an acid agent instead of the caustic soda solution 4. In addition, the aluminum-containing purified liquid 6 finally obtained in the above embodiment may be further concentrated using a reverse osmosis membrane.

As described above, according to the present invention, impurities in the aluminum-containing waste liquid can be extremely effectively removed and purified, the waste liquid can be reused, and the subsequent concentration treatment of the purified liquid can be efficiently carried out. be able to.

Next, examples of the present invention will be shown.

Electrical conductivity 14300 μV/cm, pH 1.45/25°C,
Suspended solids 1.4 g/l, A [as 1820 m9/l
, chromaticity 2400 degrees, total Fe410m9/l, Mn47■
A 10% caustic soda solution was added to the aluminum-containing waste solution containing /l to adjust the pH to 2.5, and the mixture was aerated for 1.5 hours to precipitate Al(OH)3 and Fe(OH)3. A pressure of 1. When the liquid was passed through at 5 kgf/am2, the conductivity was 11,500 μv/cm, and the pH was 2.55.
/25℃, suspended solids 28-30~/l, Al1710
mg/l, chromaticity 120 degrees, 210 mg/l as No. IFe
A membrane permeate containing 35 mg/l and Mn was obtained.

In this case, the amount of water permeated through the membrane is 27001/m2・d at a pressure of 1.5 kgf/cm2, and the removal rate of suspended solids is 9
It was 8%.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are system explanatory diagrams showing embodiments of the present invention, respectively. 1...Acidic aluminum-containing waste liquid, 4...
... Caustic soda solution, 6 ... Purified liquid, 7 ...
...Recovered soil liquid, A... Anion exchange membrane electrodialysis device, B... Cell equipped with ultrafiltration membrane, C...
...Aeration device, D...Cell equipped with a porous water-permeable support.

Claims (1)

[Claims] 1 After substantially removing free acid or alkali in the aluminum-containing waste liquid, add an aluminum precipitation agent to limit the formation of aluminum hydroxide in the liquid to a portion and separate and remove the precipitate. A method for purifying aluminum-containing waste liquid, characterized by: