JPS5927608B2 - Method for absorbing and removing SO↓2 gas using goethite and active iron oxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for absorbing and removing harmful S02 gas generated during combustion of coal or heavy oil in thermal power plants, smelters, etc. by chemical reaction and adsorption.

Since many inventions regarding the above have already been made and patented, here we will discuss similar inventions (Japanese Patent Publication No. 43-11648,
The purpose of this application is to clearly highlight the features of the present invention in comparison with Japanese Patent Publication No. 46-20688 and Japanese Patent Publication No. 48-2117).

The activated iron oxide used as an absorbent is made as follows.

Add 1/2 ferrous sulfate to the Erlenmeyer flask No. 11 shown in Figure 1.
Dissolve 4 mol (69.51 g) in 500 ml of water and adjust the pH to 4.
, Humidify with a hot plate as shown in the figure below 6.
Blow in air while keeping the temperature between 0 and 70°C.

(As shown in the figure, use a water pump to suck in outside air and introduce it into the solution.

) The resulting precipitate is left overnight, filtered, washed with water, and vacuum dried to yield αFed・(αD.

The reaction formula at this time is 2 FeSO4・7H20+H20+
202-〉Fe2O3・H20+2H2SO4+12
It is H20.

This is goethite, which is naturally produced as goethite and limonite.

When viewed under an electron microscope, the artificial material and the natural material have completely different appearances, with the artificial material having a needle-like shape and the natural material having a block-like shape.

It is difficult to obtain natural products with uniform properties due to the impurities they contain, and therefore they are not suitable for comparative tests.

Therefore, industrially produced precipitate Fe2O3・H20 = 2
If you collect FeO・(OH) and add iron scraps and water,
Since it can be made continuously, this price is determined from scrap iron.

If this αFe2O3・H20 differential heat analysis is performed, it will be 326℃.
There is an endothermic peak at which water of crystallization is released.

Furthermore, when examined by X-ray diffraction, Fe2O3/H2O crystals collapse at around 300℃, and there is no clear crystallinity until hematite crystals are formed at around 600℃, during which time SO□ gas is well absorbed and reacts. to produce Fe2(SO4)3.

That is, it is extremely activated between 300 and 600°C.

The method for producing this activated iron oxide is shown in FIG.

In the figure, 2 is kept at 325°C in an electric furnace.

4 is a sample αFeO.(OH) prepared using the apparatus shown in FIG.

3 is the test tube containing the sample, with the middle part narrowed as shown in the figure.

1 is a thick rubber tube connected to a vacuum pump.

After reducing the pressure with a vacuum pump and heating at 325°C for 1 hour, the power was cut off and the mixture was allowed to cool.

After cooling, take it out of the oven and burn off the thin part with a burner.

Thus, the activated iron oxide is sealed and stored in an ambour under reduced pressure.

If you cut off the tip of this ambour and expose it to the air, the active iron oxide will heat up and turn red, making it impossible to hold it in your hand.

Therefore, it is difficult to perform X-ray diffraction or chemical analysis of this material while preserving its properties.

The interesting substance was presented at the Hokkaido Branch Conference of the Japan Mining Association on November 29, 1971.

The strong exothermic oxidation in the air at room temperature is thought to be due to the extremely large surface area of this material, which causes catalytic oxidation with oxygen in the air.

In addition, its color is black and it looks similar to Fe2O3/FeO, and the active particulate Fe2O3/FeO is oxidized by air.
It may have changed to 20g of Fe, but no conclusion can be drawn at this stage.

Since it is not possible to conduct an absorption test while keeping such an active substance pure, it was used after being slowly oxidized under reduced pressure.

At this time, it was difficult to make completely identical products, so we compared absorption tests between goethite and active iron oxide, but some discrepancies were found.

It is shown in Table 1.

As is clear from the above table, active iron oxide shows better performance than goethite in the mixing range used for desulfurization, that is, between room temperature and 350°C.

The method of this absorption test is shown in FIG. The test conditions were: sample 3.0g, SO2 gas concentration approximately 1.0%, air flow rate 1/min.
00-120m1. The thickness of the sample layer was 110 mm, and the inner diameter of the sample tube was 10 mm.

In Table 1, I entered 450°C and 1500°C in the goethite column, but at 450°C it should be active iron oxide.
This test is an absorption test of goethite when the temperature is gradually increased.

There should be no goethite present above 326°C.

From the above results, SO2 gas absorption by goethite is mainly due to surface adhesion, and absorption by active iron oxide involves both adhesion and chemical reaction.

Next, when compared with the three patents mentioned above and shown as a list, the second
It will look like the table.

In the table above, special public service number 46-20688, special public service number 48-2117
Both of the present invention and the present invention start from γFed(OH), but as described in the detailed description, the manufacturing method is different and the present invention is simpler.

Furthermore, since the pH at the time of precipitation is different, the properties are different.

In particular, the absorbent of the present invention cannot be identified yet, but Fe2O3.
Possibly FeO.

[Brief explanation of drawings]

FIG. 1 shows an apparatus for manufacturing goethite αFed (OH). 1 is an Erlenmeyer flask with contents 11. 2 is ferrous sulfate F
It is an aqueous solution of eSO4.7H20, and 3 is a 300W hot plate. 4 is a generated game site. Figure 2 shows an apparatus for producing live iron oxide from goethite. 4 is goethite, 2 is an electric furnace, 3 is a test tube whose middle part is heated to make it thin, and 1 is a thick rubber tube connected to a vacuum pump. Figure 3 shows an apparatus for conducting SO2 gas absorption tests. 1 is a glass tube with a content of about 50 Tnl, and 2 is a H2SO3 solution. 3 is a balloon that stores SO□ gas and has a content of approximately 11.257. 4 is a glass bottle with a content of approximately 207 cm, and the gas in the balloon is released and added by the inflow and outflow of tap water. 5 is a glass tube with a stopcock. 6 is a pinch cock that tightens the rubber tube. 7 is a sample tube, 8 is a sample, 9 is a glass filter, 10
is a nichrome wire electric furnace. 11 is a 500m1 Erlenmeyer flask, 12 is KMn 04
13 is a 300 ml Erlenmeyer flask, 14 is an aqueous solution of KMnO4, and 15 is a crawler flowmeter. Without washing, fill 4 with tap water and expel the air in 3.
Next, open the pinch bottle connected to H2SO3, and then let the water in 4 flow out to the bottom left. At this time, air passes through the H2SO3 water and generates SO2, which is stored in the balloon. Once the balloon is fully inflated, stop draining the water and close the pinch cap (as shown in the diagram). Next, connect the rubber tube to the sample tube and pour tap water at 100 to 1
If 20ml of SO2 gas flows into 4 at a time, the amount of SO2 gas in the balloon will be 1.
It passes through the sample at a flow rate of 00 to 120 ml/min. The amount of S02 gas generated and stored in the balloon is determined as follows. SO2 in H2SO3 water is approximately 6 to 7%, which produces SO2 through the reaction of H2SO3→H20+SO2, but the remainder is not neutral water but remains H2SO4 oxidized by air. First, add H2O2 to H2S03 water and oxidize it to H2SO.
4 and 1/1 ON NaOH to determine the titration LJI degree. In addition, after blowing air and generating S02, the residual liquid was completely converted to H2SO4 with H2O2, and then 1/10 N
Titrate with NaOH to determine the concentration, and the difference occurs in SO
The amount is 2. In this way, the concentration of sulfite water is determined, and SO
. Determines how much gas is produced. Then, determine the amount necessary to generate 112 ml, put it in 1, and pass air through it.Since the content of the balloon is 11.25 ml, a concentration of about 1% gas will be stored in the balloon. The sample is preheated to a predetermined temperature in an electric furnace. Then, the S02 gas in the balloon is passed through. The S02 gas passing through the sample enters the KMnO4 solution at 12. Since S02 is a reducing gas, when it becomes equivalent to the KMr+04 solution, the reddish-purple color of the solution changes to colorless and transparent. This reaction is so sensitive that it can be clearly seen. 14 KM
The nO4 solution is a preliminary one to prevent S02 gas from reaching the flow meter and leaking outside.

Claims (1)

[Claims] 1 Goethite (αFed(OH) or αFe2O3
-H2O) to 300 to 400°C to remove crystallization water and contains activated iron oxide (Fe203, which is in an amorphous state without forming hematite crystals) containing S02. A method of absorbing and removing SO□ gas by contacting it with gas.