JPS6023851B2 - Method for removing mercury from roasting gas containing sulfur dioxide gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing mercury-containing sulfide keys, such as iron sulfide,
The present invention relates to a method for removing mercury contained in sulfur dioxide gas, which is produced by storing sphalerite or the like in an oxidizing barrel, and which contains sulfur dioxide gas as a main component.

In addition to the metal sulfur as the main component, sulfide ores often contain large amounts of mercury, and sphalerite in particular contains several or even hundreds of mercury.

Therefore, when such mercury-containing sulfide ore is smelted, most of the mercury is mixed into the mercury gas as mercury vapor, so the gas is cooled and washed after dedusting using the Shigeru method to create a mist cotterel. Because the vapor pressure of mercury in the above gas is high even if the gas is purified through gas purification, a considerable amount of mercury remains in the purified sulfur dioxide gas obtained by the above gas purification. It is unavoidable that mercury will be mixed into the concentrated sulfuric acid or fuming sulfuric acid that is obtained. However, in view of the fact that various types of environmental pollution caused by mercury have become a major pollution problem in recent years, there is a strong demand for reducing the mercury concentration in concentrated sulfuric acid.

Conventionally, there are two methods for removing mercury mixed in concentrated sulfuric acid and reducing its concentration: one is to remove mercury from sulfur dioxide gas as a raw material, and the other is to remove mercury from concentrated sulfuric acid. Although various proposals have been made regarding these methods, they are not necessarily satisfactory in terms of mercury removal efficiency, and at present no economically advantageous removal method has been established.

For example, in order to remove the mercury contained in sulfur dioxide gas, it is necessary to install fairly large equipment such as acid circulation purification equipment to existing sulfuric acid production equipment, and the resulting change in the pressure balance within the system causes sulfuric acid There are disadvantages such as a large impact on manufacturing equipment. The present inventor has discovered that when air is brought into contact with the exhaust gas generated during the extraction stage of sulfide ore to generate sulfur dioxide gas under high temperature, the amount of mercury that is mixed into the exhaust gas becomes effective. The present inventors have discovered that the present invention can be removed in a straightforward manner. Note that "air" here includes not only normal air but also oxygen-enriched air. Therefore, an object of the present invention is to provide a method for effectively removing mercury from sulfite-containing gas accompanied by trace amounts of mercury, such as those generated by mining sulfide ores.

The present invention will be explained in detail below.

The present invention is characterized in that air is blown into the sulfurous acid gas-containing barrel light gas accompanied by a certain amount of mercury, such as sulfide ore combustion gas, at a high temperature during the discharge stage.

The mercury compounds contained in the sulfide ore are decomposed by tarakyo to produce Hg.

(evening), and the other mineral components in the ore mentioned above, Se,
Combined with CI etc., day is e, HgC12, day is H history 04
However, a part of the above Hgo (Hgo) is emitted as it is along with the fin oxidation gas from the barrel oxidation stage.In the present invention, as described above, the Hgo
At high temperatures of over 600 degrees Celsius,
When air is brought into contact with air by means such as blowing, the oxygen partial pressure in the gas system increases, promoting the oxidation of sulfur dioxide gas in the gas, producing sulfuric anhydride, and oxidizing the sulfuric anhydride and H
It is presumed that go reacts and finally becomes mercury sulfate.

When the concentration of sulfur dioxide gas (S02) in the oxidation gas is about 10%, the amount of air to be brought into contact with the oxidation gas is about 8 to 10%. 9
%. In particular, if the amount of air is set so that the concentration of S02 in the cod ant gas is 8%, mercury in the molten gas can be efficiently removed.

According to the present invention, S02 in the S02 gas when air is blown into and brought into contact with the S02 concentration 10% gas.
The relationship between concentration and changes in mercury amount is illustrated in the table below. Table note (1) Temperature of scum (exhaust gas)...10
50℃ (mercury concentration at the outlet of the 21 flame furnace... 10 N) Judging from the above table, if air is blown into and brought into contact with the high temperature cod grilling gas discharged from the cultivation furnace (this air and (The contact with the gas dilutes the S02 gas and lowers its S02 concentration.)
It is understood that the mercury content in the barrel race gas introduced into the sulfuric acid production system has been significantly reduced, and therefore the mercury content in the concentrated sulfuric acid produced from the gas has also been significantly reduced.

It should be noted that increasing the amount of air blown into contact with the above gas will reduce the S02 concentration in the burnout gas, so it is not a good idea for the production of sulfuric acid. Since there is no substantial difference in the mercury removal efficiency even if the S02 concentration is lower than about 8.0%, it is actually advantageous to blow in the amount of air as described above. Generally, the temperature of the smelting gas discharged from the sintering stage of sulfide ore reaches more than 600 qo, so when carrying out the present invention, it is preferable to blow air into the sulfide ore at the outlet of the keg kiln.

Since the mercury sulfate generated in the charring gas as described above can be easily collected using existing kerating gas purification equipment, according to the present invention, air blowing can be performed without installing special mercury removal equipment. It becomes possible to effectively remove mercury from the above-mentioned incineration gas by the simple operation of combusting.

Incidentally, the concentration of mercury according to the present invention is reduced to 1'10 or less compared to the control example, as shown in the examples below. Therefore, the present invention has great advantages in producing concentrated sulfuric acid or fuming sulfuric acid with extremely low mercury content. Next, the present invention will be specifically described by way of examples.

Example: Sphalerite having a texture of 20 to 3 mercury was heated to 1 in a fluidized light furnace.
The mercury concentration in the sulfuric acid production system is reduced by calcination at a temperature of 8,000 ℃, air is blown at the outlet of the sintering furnace, the molten gas is cooled, dust is removed and washed, and the mercury concentration in the gas is introduced into the sulfuric acid production system through a mist cotterel. When measured, it was 0.1 mp/N.

In addition, the mercury concentration in the gas at the outlet of the above-mentioned melting furnace is 1
It was 9/N of 0. Further, as a comparative example, the mercury concentration of the gas at the above time point was measured under the same procedure in the case where the air was not blown, and it was found to be 9/N of 1.5.

In addition, the mercury concentration of the concentrated sulfuric acid obtained from the sulfur dioxide gas obtained by removing mercury according to the present invention was 0.3 to 0.1, whereas the mercury concentration in the comparative example was 3 to 1. Ta.

Claims (1)

[Claims] 1. The above-mentioned method for removing mercury from torrefaction gas, which comprises blowing air at high temperature into the torrefaction gas containing sulfurous acid gas accompanied by a trace amount of mercury, such as sulfide ore torrefaction gas, in the discharge stage.