JPS58114728A - Mercury removing agent and its production - Google Patents

Abstract

PURPOSE:To produce a removing agent for a trace of Hg vapor in gases at a low cost by passing gaseous H2S through an Se-contg. soln. dispersed therein with S powder to coat the surfaces of the S powder with SeS and depositing said powder on the surfaces of inorg. carriers. CONSTITUTION:Powder of S is dispersed at <=200g/lconcn. in an H2SeO3 soln. prepd. by dissolving SeO2 in water or a soln. prepd. by neutralizing an Na2SeO3 soln. dissolved in an NaOH soln. with H2SO4. Gaseous H2S is passed at a proper velocity through said liquid to allow SeS to deposited on the surfaces of the S powder with said powder as nuclei. The composite material of SeS and S is filtered and separated from the liquid and is sprinkled and deposited at 200kg/m<2> ratio on the surfaces of inorg. carriers such as pumice, whereby a mercury removing agent is prepd. The mercury removing agent which removes an extremely trace of Hg vapor contained in gases with good efficiency is produced at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mercury removal agent that efficiently removes trace amounts of mercury vapor contained in gas at extremely low cost, and a method for producing the same.

Conventionally, the substances used as removers for mercury in exhaust gas are those that create intermetallic compounds such as steel, silver, and selenium because they have excellent reactivity with mercury.

Hot concentrated sulfuric acid, mercuric chloride solution, active sulfur, active selenium-containing solution, lead sulfide, nickel sulfide, cadmium sulfide,
Many substances are known, including sulfides such as selenium sulfide and other activated carbons.

These substances are used to remove mercury from smelting gas by supporting them on S* carriers that do not react with mercury and using them in a packed tower format, or by dissolving them in the liquid as they are. Alternatively, it is used in a washing tower format by making it cloudy.

However, all of these materials have technical or economic disadvantages. Namely.

Steel is suitable for removing mercury from the gas emitted from caustic soda electrolysis, but its surface oxidation is severe in smelting gas, and its ability to remove mercury rapidly declines. Silver is like smelting gas! is extremely expensive and impractical. Furthermore, using selenium powder as it is is too expensive and economically unsuitable. On the other hand, hot forging sulfuric acid can corrode equipment,
Is there a problem with absorption capacity and a solution containing 2@mercury ions? I[.

For example, mercuric chloride 1111111! The Nyoru method has a large temperature dependence, and there are problems in that the absorption capacity decreases rapidly with gases at temperatures higher than room temperature, and the absorbent itself contains mercury.In addition, active sulfur and active selenium are There is a problem in terms of the lifespan to maintain the activity.Furthermore, the rII carbon #i adsorbs the S false gas in the smelting gas,
Decrease mercury adsorption capacity (on the other hand, sulfides can be used as mercury removers even if they are not specially embroidered, such as lead ore or J41f).
Some mercury removers, such as , and III ore, can be used in their original form as mercury removers, and even if their performance is poor, they are not as good as other mercury removers. In particular, the strong reactivity of selenium sulfide with mercury has already been reported:
erW.

From Nordjand@r K, Latastria
j and ff1qi 切-r-jng Chemis
try Vow, 19m 44*mprig, 19
27. Gill-521 points out that paper coated with selenium sulfide turns black when it comes into contact with mercury leakage. This Akira II! Black discoloration is based on the reaction between selenium sulfide and mercury, and is a function of the concentration of mercury vapor, contact time, etc. Therefore, the black discoloration of paper coated with selenium sulfide is determined by measuring the black discoloration. It is stated that the device can function as a quantitative mercury detector. Therefore, it is already known that selenium chloride can be used as a mercury removing substance.

In addition, Japanese Patent Publication No. 55-39364 describes the n#1 method for purification of gaseous mercury-containing gas [mercury contained in a lump of a refining substance in which selenium sulfide, selenium dioxide, or a mixture thereof is supported on an inert a1 body. How to pass gas
(hereinafter referred to as known invention) is disclosed. In this case, an inert carrier is impregnated with a selenium sulfide solution or a selenium dioxide solution to support selenium sulfide, selenium dioxide, or a mixture thereof. However, the above-mentioned publication states that since selenium dioxide itself has a low ability to remove mercury, it is necessary to convert it into highly active elemental selenium by dipping it with 801 gas before use.
``In general, the reaction between selenium sulfide and mercury is expressed by the following formula (1). Compared to , only 8 is utilized.

In the case of selenium sulfide, both 8 units and 8 units are shown to be effective in removing mercury.

In this respect, selenium sulfide is significantly superior to other sulfides in its ability to remove mercury.

As described above, @Selenium chloride has excellent mercury removal ability, but the reason why it was not used industrially as a mercury removal substance until iA is considered to be as follows.

11) Selenium sulfide is extremely expensive.

That is, since selenium sulfide is made from expensive selenium, it is extremely expensive compared to other sulfides, such as lead sulfide and zinc sulfide, which exist naturally as ores. For example, lead sulfide is far inferior to selenium sulfide in its ability to remove mercury, but because it is inexpensive, it is used industrially as a mercury removal material. On the other hand, selenium sulfide is expensive.

Not put into practical use. As described above, selenium sulfide is already expensive as a raw material, and there are also problems in conventional manufacturing methods. That is, there are wet methods and dry methods for producing selenium sulfide, but each method has its own problems.

First, in the wet method, selenium sulfide particles are precipitated by passing hydrogen sulfide into a selenite solution, but the precipitated selenium sulfide particles become cloudy with S, and the filterability of the filtration hoe is poor, and very fine selenium sulfide particles It cannot be completely filtered, resulting in a loss. In addition, the filtered selenium sulfide particles become carmeloid-like when dried, and in order to be used as a mercury remover, the specific surface area must be increased, so a crushing process is required.

Next, in the dry method, selenium sulfide is produced by mixing sulfur and selenium to the desired chemical composition and melting the mixture in a furnace, but the reaction product is highly viscous and cannot be extracted continuously from the furnace. However, when the reaction product is cooled, it becomes rubbery and cannot be crushed. For this reason, it was necessary to maintain the temperature at 80 to 85 C for 30 minutes to ripen it.

As mentioned above, selenium chloride is known to have excellent mercury removal ability, but the reason why it is not used industrially as a mercury removal agent is because of its economic efficiency and production method. be.

The present invention solves the above-mentioned drawbacks of the prior art and provides a mercury removal agent and a method for producing the same that can efficiently remove trace amounts of water contained in gas at an extremely low cost. (1) A mercury removal agent comprising selenium sulfide/sulfur composite particles, which are composed of sulfur powder as a core and selenium sulfide coating the surface of the sulfur powder, supported on the surface of an inorganic carrier by aiK.

(2) 200f of S liquid containing selenium neutralized sulfur powder
/ is dispersed at the following concentration, and hydrogen sulfide gas is passed through this to cause selenium sulfide to precipitate on the surface of the sulfur powder with the sulfur powder as a nucleus to form selenium sulfide/sulfur composite particles, and the sulfurized selenium sulfide obtained by filtering. 1. A method for producing a mercury remover, which comprises supporting a mercury sulfur composite particle on the surface of an inorganic carrier.

It is in.

As described above, the mercury remover of the present invention has valorized selenium/sulfur composite particles consisting of sulfur powder as a core and valorized selenium coated on the surface of the sulfur powder, and selenium sulfide/sulfide composite particles on the surface. It is composed of an inorganic carrier and is characterized by a double structure. Regarding its production method, please refer to selenium dioxide (Bed)
Add 200f/ of sulfur powder to a solution prepared by neutralizing selenite solution (@) in water or sodium selenite solution dissolved in caseinoda solution Ill with sulfuric acid.
By passing this [H, 8 gas at an appropriate speed, selenium sulfide is precipitated on the surface of the sulfur powder using the sulfur powder as a core, and selenium sulfide/sulfur composite particles are formed. Unlike the very fine selenium sulfide particles used in the conventional method mentioned above, the sulfur composite particles have good filterability, so there is no filtration loss.The sulfur powder used as the core has good dispersibility, and the amount added is 200 tons. / is below.The amount of sulfur powder added is 200
tlt? If you cross it.

The sulfur powder in the fII solution increases its streaking property, and the coating of the sulfur powder of selenium mide on *tm becomes uneven, which is undesirable. In order for the d-period composite particles to exhibit the stated q# value without causing any damage, the range is preferably -100 mesh to +350 mesh. The lower limit of the amount of sulfur in the liquid #1 in which 1 sulfur powder is added is 5 sulfur powder. If the amount of selenium is less than 5, the surface of the sulfur powder will not be uniformly coated with valenced selenium, making it impossible to obtain the desired valenced selenium/sulfur composite particles.

The selenium sulfide/sulfur composite particles thus produced are filtered out and then sprinkled on the surface of an inorganic carrier to obtain the mercury removing agent of the present invention.

As mentioned above, the mercury removal ability of the present invention obtained in this way has a double structure consisting of valorized selenium/sulfur composite particles and an inorganic carrier supporting DM particles, but the central feature is The particles are selenium sulfide/sulfur composite particles, and these composite particles have the following characteristics.+1) Since the composite particles have sulfur powder as their core, unlike fine selenium sulfide particles produced by conventional methods, they cannot be filtered. good performance and no filtration loss.

121 Since the composite particles have a structure in which the surface of the sulfur powder as a core is coated with selenium sulfide, the amount of expensive selenium sulfide used can be reduced to 1-.

(31) The composite particles can be simply filtered and then sprinkled on an inorganic carrier and supported, so there is no need for a drying step or pulverization as in conventional methods.

(4) By adjusting the particle size of the sulfur powder serving as the core, the particle size of the composite particles can be adjusted.

(5) The composite particles are lightweight because they have a core of light sulfur powder.

(6) Sulfur and selenium have great acid compatibility.

The adhesion between the sulfur powder as the core of the composite particle and the selenium sulfide as the target material is strong.

The mercury removing agent of the present invention is of the type that forms a packed layer and allows mercury-containing gas to pass through the filled layer to remove mercury from the gas. It has linear characteristics due to its double structure.

+11 The use of expensive selenium sulfide is extremely rational, and the amount of selenium sulfide used is small.

Very cost-effective.

(2) Due to the double structure, the specific surface area is increased, and the mercury complement ability per unit amount of silane is greater than that of the mercury removing agent of the known invention, in which the carrier surface is simply coated with selenium sulfide.

(31 Because the amount of selenium carried per unit volume is large.

The mercury removal agent of the above-mentioned known invention has a larger complement angle and a longer life.

14) Since the selenium sulfide/sulfur composite particles having a lightweight sulfur core are supported on an inorganic carrier surface of 1iK, the weight of the packed tower is reduced.

15) Used waste can be easily disposed of. That is, the composite particles that have reacted with mercury on the surface of the carrier are easily peeled off and separated into layers using, for example, a wet trommel, and then treated by a known method to recover expensive mercury and selenium, and to prevent secondary pollution caused by mercury. Although it can be suppressed.

In the case of the above-mentioned known invention, the peeled portion of the surface of the carrier @-
jet is not easy.

Next, we will discuss the treatment of used waste agents.

The waste agent that complements the mercury in the gas is produced by the selenium sulfide layer of selenium sulfide/sulfur composite particles supported on an inorganic carrier, such as pumice, reacting with the mercury in the gas and converting into mercury sulfide and mercury selenide. Yes, therefore.

The composite particles are composed of unreacted selenium sulfide, elemental sulfur as a nucleus, and reaction products mercury sulfide and mercury selenide. As described above, since the waste agent contains expensive selenium and water fIi, it is necessary to collect them advantageously, reuse the selenium, and separate and recover the water 11i11 so as not to cause secondary pollution! There is.

Since this waste agent acts as a carrier, if the reaction product and carrier are separated in advance, the throughput can be reduced to a very high level.
As a result of repeated experimental studies, the researchers found that removing the reaction product using a wet trommel is effective because selenium and mercury can be separated and recovered advantageously. A specific example will be described below.

That is, the water-removal agent of the present invention, in which pumice was supported with selenium sulfide/sulfur composite particles with elemental sulfur cores at a ratio of 200 ky/-, was packed into a packed tower, and mercury was removed through mercury-containing smelting gas. I did it.

This waste agent, including the carrier pumice, had an average of 6 - parts of water. 1 kg of this waste was placed in a 4th wire mesh trommel (200 mO x 300 mL) in a 10 t aquarium.
)'C and washed with water while rotating at 50 revolutions per minute.

The relationship between the water washing time, the peeling of reaction products (adhesives), and the amount of mercury is shown in FIGS. 1 and 2, respectively. Also, for comparison, Fig. 1 and Fig. 2 show
*The results of discarding a mercury remover in which pumice is supported with selenium sulfide alone according to the known invention are also shown (Figures 1 and 2L)! As shown in Figure 11, more than 98% of the pumice deposits on the waste mercury remover of the present invention were peeled off and separated by washing with water for about 30 minutes using the wet trommel, and the mercury separation rate was 99.7%. almost perfect,
In pumice which is a carrier! ! It was 260 ppm in 4-ro water.

On the other hand, in the case of the waste agent of the known invention in which pumice is supported with selenium sulfide alone, the adhering particles are fine and the g! Because of the adhesion in the crevices, both the removal rate of pumice deposits and the mercury fraction are inferior to those of the waste agent of the present invention by X%.

In this way, the deposits peeled off from the waste carrier of the mercury remover of the present invention contain water @ 13-16%, selenium 12-151%,
G, has a composition of 69 to 71% sulfur, and is equivalent to 3 (14!! degrees) of the total by weight.These peeled products are further processed by a known method to remove expensive mercury and sulfur. Separate and recover selenium. Since there is still a trace amount of mercury remaining in the stone, it can be used repeatedly as a carrier for selenium sulfide, and it can also be used as part of a solvent in smelting processes. 1 il of water does not become a source of secondary pollution.

As described above, the present invention uses a sulfur powder with good dispersibility as a core, has good filterability, and has a sulfuric acid powder.
By forming selenium sulfide/sulfur composite particles, which are used in extremely small amounts, and supporting them on the surface of an inorganic carrier to form a double structure, we provide a low-cost mercury removal agent with an extremely high mercury complement ability, and a method for producing the same. to do,
It is extremely useful for removing mercury from gas.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

J! A sodium selenite solution obtained by oxidizing and roasting the electrolyzed slime at 700'C and washing the generated roasting gas with a caustic soda solution is neutralized with sulfuric acid, and from this neutralized liquid selenium manufacturing process. I took some out. 6 fPB of the extracted liquid
The concentration of e/l is 11C@dead, and the liquid volume is 5GGccK -
Disperse 200 mesh of industrial sulfur 30), and in that state, 5QC H38 gas at a temperature of 10°C or lower.
Blow at the rate of C/11111.

The blowing of titwca gas was stopped for 30 minutes, and the generated precipitate was filtered to obtain selenium sulfide/sulfur composite particles.

The composite particles were sprinkled as they were on pumice stone to be supported, thereby producing the mercury removing agent of this example.

In order to compare the mercury complement ability of the mercury removing agent of this example and the mercury removing agent in which pumice was similarly supported with selenium sulfide alone, the following experiment was conducted.

That is, in the experiment, the target mercury removing agent was packed at a height of 53 in a reaction column with a column diameter of about 20 mm, and gas compositions of N, 81%, 0.9%, SO, 10 pieces of gas were passed through hot water at a rate of 3 t/H1 to adjust the humidity, and then passed through once. Reaction tower population gas water smBt#i average 2.5
q; 1/N-, and the mercury concentration in the reaction tower outlet gas is 0.1 m
The achievements continued until reaching 9/Nn1K. here.

The mercury concentration of the outlet gas is set to 0. The reason for setting l Iv/N- is that the mercury in sulfuric acid was set to be 0.5 ppm or less. Incidentally, the degree of mercury S in the gas was analyzed by collecting a certain amount of the sample gas in KMnO4 solution flK&, and analyzing it by 7 frameless atomic absorption spectrometry.

The experimental results are shown in FIG. 3 by 111141 for the mercury removal agent in which pumice is supported on selenium sulfide alone, and by the curve 11 for the mercury removal agent of this example.

In the above, if the value α obtained by dividing the amount of mercury reaction until the mercury d1 degree of the gas at the outlet of one reaction column reaches 0.1 Da/N- by the amount of selenium sulfide packed in the column is the actual mercury complement capacity, then ,
In the case of water #1 # remover carrying only selenium sulfide (track I)
II) and the water fl of this example! In the case of a remover (one song), α is as shown in the following table.

As shown in the above table, the water 1IjA scavenging ability of selenium sulfide in the mercury layer made of the mercury remover of this example was significantly improved compared to the case of the mercury remover carrying only selenium sulfide. It was also confirmed that the formation of composite particles with sulfur powder as the core produced a 1-curve effect.

Furthermore, as another comparative example, the experimental results when lead sulfide and a physical mixture of sulfur and selenium sulfide were photofilled are also shown in Figure 3 as curves 历 and ■, respectively. It turned out that the revenue was low.

Comparative Example 1 Neutralized selenite powder #g from Example 1 [without dispersing the above sulfur powder (when Has gas was blown in, fine particles of selenium sulfide produced were suspended in the filtrate). The selenium Ill in this filtrate is a trace in the actual aS, but it was 2t/l in one comparative example.Also, the S turbidity and some selenium sulfide particles are extremely fine with a size of less than 1 micron. Therefore, it takes a long time to filter K to recover all of them, which is not practical.

Comparative Example 2 In place of the sulfur powder in the neutralized sodium selenite solution of Example 1, lead sulfide and reduced zinc were formed, which had poor dispersibility in the solution, and lf/L of selenium was added to the filtrate. remained uncollected.

[Brief explanation of drawings]

Figure 1 shows the water washing time and reaction product (deposition) peeling wheel using a wet trommel for the waste of the mercury remover of the present invention and the waste of the mercury remover in which selenium sulfide alone is supported on a carrier (@stone) K. Figure 2 is a graph showing the relationship between the water washing time and mercury separation rate using a wet trommel for the two types of mercury removers shown in Figure 1. Curve 1 is a graph showing the relationship between the reaction time and the degree of mercury in the reaction tower outlet gas when a mercury-containing gas is passed through a reaction tower filled with a mercury removal agent supported on pumice. In the case of single selenium sulfide, one box shows the mercury removal agent of the present invention, one box shows the case of lead sulfide, and *aya shows the case of a physical mixture of sulfur and selenium sulfide. Poetry painter Yoshinao Shirakawa Agent of Mitsubishi Metals Co., Ltd.

Claims (1)

[Scope of Claims] [1] A water-removing agent comprising selenium sulfide/sulfide composite particles comprising sulfur powder as a backing and selenium sulfide with aa sulfide on the surface of the i-sulfur powder, supported on the surface of an inorganic carrier. (2) Disperse 200 f/ of sulfur i powder in a solution containing selenium at the following 11 degrees, and pass hydrogen sulfide gas through it to precipitate selenium sulfide on the surface of the sulfur powder using the sulfur powder as a core. A method for producing a mercury removal agent, which comprises forming sulfur composite particles and supporting the selenium sulfide/sulfur composite particles obtained by filtration on the surface of an inorganic carrier.