JPH07328433A - Material for absorbing mercury in gas and its production - Google Patents

Abstract

PURPOSE:To provide a material for absorbing mercury in gas with absorption efficiency enhanced by using an inexpensive lead concentrate and capable of maintaining the high absorption efficiency for a long period. CONSTITUTION:A lead concentrate is dipped in water and agitated, then sulfuric acid is added to activate the surface, acetic acid is added and agitated, then lead oxide is added, and hydrogen sulfide is blown into the liq. with the temp. adjusted to deposit PbS on the surface of the concentrate. The PbS pulp is adhered to pumice with the grain size controlled to form a mercury absorbent, and a material for absorbing mercuty in gas maitaining high mercury absorption efficiency for a long period as shown in the figure is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorbent material suitable for removing mercury in a gas and a method for producing the same, and more specifically, it produces an absorbent material which is stable for a long period of time using an inexpensive lead concentrate. The purpose is to

[0002]

2. Description of the Related Art Studies for removing heavy metals, particularly mercury, in a gas by adhering an active metal or compound to a porous material have been conducted for a long time.

As one example, in JP-A-48-13259 (the title of the invention: "Method for purifying gas containing mercury compound and elemental mercury"), selenium as an active ingredient,
Disclosed is a method for purifying a gaseous mercury-containing gas, characterized in that a mercury-containing gas is blown into and passed through a bulk purification substance containing selenium sulfide or another selenium compound or a mixture thereof. .

Further, the applicant of the present invention also previously issued Japanese Patent Publication No. 54-847.
No. 5 (Title of invention; "Method of removing mercury in acidic exhaust gas")
In the above, the acidic exhaust gas accompanied by gaseous or mist-like mercury is applied to ZnS, C
At least one selected from the group consisting of dS and PbS
Disclosed is a method for removing mercury in an acidic exhaust gas, which is characterized in that it is led to a packed layer of an absorbent composed of one carrying a metal sulfide of a kind and passed through.

As one type of mercury absorbing material that can be used for these removal methods, the applicant of the present invention discloses in Japanese Patent Publication No. Sho 63-2654 (invention name: "mercury absorbing material in exhaust gas"), zinc blende, At least one mineral acid-treated concentrate of galena, pyrrhotite, or chalcopyrite is added with an oxide and an acid of a metal as a main component of the mineral, and hydrogen sulfide is further added to form a precipitate formed into a porous material. By providing a mercury absorbing material in exhaust gas which is supported on a carrier, it has contributed not a little to the actual operation.

[0006]

However, in the subsequent tests, it was found that the above-mentioned absorbent exhibits a high absorption efficiency at the beginning of use, but the absorption efficiency decreases in a relatively short period of time when gas is passed for a long time. .

Since the above-mentioned absorbent material uses inexpensive concentrate, it has been desired to develop an absorbent material that is stabilized for a long period of time by further improving this material.

[0008]

The inventors of the present invention have made extensive studies in order to solve these problems, and as a result, PbS chemically synthesized on the surface of these lead concentrates in an organic acid using lead concentrates. It has been found that a long-term stabilized mercury-absorbing material can be produced at low cost by uniformly impregnating the obtained PbS with the obtained PbS pulp supported on a porous substance.

That is, one aspect of the present invention is to add a mineral acid to an aqueous liquid in which lead concentrate is added and stirred to activate the surface of the concentrate.
Next, after adding an organic acid, hydrogen sulfide is blown into the liquid in which PbO is added and dissolved to generate PbS on the surface of the lead concentrate,
Another aspect of the present invention is a mercury absorbing material in a gas, characterized in that the obtained pulp is supported on a porous carrier. First step of activating the ore surface, adding an organic acid to the above liquid and stirring, then adding / dissolving PbO and blowing hydrogen sulfide to produce PbS on the surface of the lead concentrate to obtain PbS pulp. The present invention relates to a method for producing a mercury absorbing material in a gas, which comprises a second step and a third step of adhering the pulp to a porous substance to form a gas absorbing material.

[0010]

The PbS pulp used in the method of the present invention uses inexpensive lead concentrate as a starting material, and this concentrate (fine particles) is
Since the mineral surface is covered or oxidized by various beneficiation reagents, it cannot be used as an absorbent for demercury removal as it is. The target is the mineral acid-treated concentrate.

In the first step, while adding and stirring the lead concentrate in an aqueous liquid, sulfuric acid is added as a mineral acid to wash and activate the surface of the concentrate, and then the supernatant liquid is removed.
Supply new water.

In the second step, acetic acid is added as an organic acid and the mixture is stirred, then lead oxide (PbO) is added and the mixture is similarly stirred. In these liquids, hydrogen sulfide was added to PbO100.
It was blown at a rate of about 30 ml / min with respect to g, and PbS was chemically synthesized on the surface of the lead concentrate particles and uniformly attached. Hydrogen sulfide was continuously blown in until the Pb ²⁺ ions in the liquid disappeared, and after the reaction was completed, the pulp water was washed by decantation until the pH became neutral, and then the PbS pulp was taken out of the reaction vessel.

In the presence of an organic acid, lead oxide slowly dissolves and slowly reacts with hydrogen sulfide to form a chemically synthesized uniform PbS layer on the surface of lead concentrate particles. For other acids, P
Although bS is partially synthesized on the surface of lead concentrate particles, most of it is produced as PbS particles, and PbS cannot be uniformly impregnated on the surface of lead concentrate particles, and mercury is stably absorbed for a long period of time. Not a material.

In this embodiment, acetic acid was used as the organic acid, but this is preferable because it is a low cost material, and other organic acids such as formic acid, oxalic acid and benzoic acid may be used. Similar effects are obtained.

In the third step, the PbS pulp is attached to a porous material such as pumice stone. For example, about 250g of Pb per liter of pumice on the surface of pumice with a pelletizer.
S is applied uniformly.

The mercury absorbent in the gas thus obtained has a higher initial performance than the absorbent disclosed in Japanese Patent Publication No. 63-2654, which is shown in the conventional example, and the initial performance is tripled or more. It was found that the mercury absorber is stable for a long period of time.

[0017]

Example 1 1.5 kg of lead concentrate manufactured by A mine was put in a container having a capacity of 3 liters, and water was added to the container to adjust the total volume to 2 liters. The liquid temperature was controlled to about 45 ° C while stirring. Then, 10 ml of sulfuric acid was added little by little as a mineral acid, and the mixture was stirred for 1.5 hours to activate the surface of the lead concentrate, followed by sedimentation for about 7 hours.

Then, after removing the supernatant, water was added again to adjust the total volume to 2 liters (first step).

10 ml of acetic acid as an organic acid was added to the pulp liquid of the first step and stirred, and then lead oxide (PbO) was added to 1 ml.
00 g was added, and the liquid temperature was controlled to about 45 ° C. Hydrogen sulfide (H ₂ S) was added to the solution in an amount of 100 g of PbO.
Bubbling was carried out at a rate of 30 ml / min for about 7 hours, and after confirming that the Pb ²⁺ ions in the liquid had disappeared and the reaction had ended, the blowing of hydrogen sulfide was stopped. Next, PbS was allowed to settle, the supernatant was removed, and the operation of adding water and stirring was repeated several times (decantation), and the solution was washed with water until the pH of the solution became 6 or more in the neutral range. After that, P that settled at the bottom of the container
The bS pulp was transferred to another container (second step).

Next, the PbS pulp was attached using a pelletizer at a ratio of about 250 g to 1 liter of pumice having a particle size adjusted to 5 to 15 mm to obtain a mercury absorbent in a desired gas.

The absorbent obtained by the above process, and the absorbent obtained by depositing a substance from the zinc sulfide concentrate described in Japanese Patent Publication No. 63-2654 as a comparative absorbent on pumice in the same proportion as above. Using a column, fill each of the 200 ml columns with 3
A gas containing mercury was passed through at a rate of 1 / min.
It was devised so that the mercury concentration in the gas at the entrance could be changed, and the gas at each entrance and exit was sucked in at the same time.
By absorbing the liquid and analyzing the mercury in the absorbing liquid,
The mercury absorption performance of the absorber under each condition was investigated. The results are shown in Table 1.

[0022]

[Table 1]

As described above, the initial mercury absorption performance is stable at 99% even if the mercury concentration in the inlet gas changes.
It was found that there was a removal rate of at least%.

[0024]

Example 2 The long-term stability of the mercury absorption performance of the absorbent according to the present invention and the comparative absorbent manufactured in the same manner as in Example 1 was examined. Under the same gas passing conditions as in Example 1, the concentration of mercury at the inlet was made constant, gas was continuously passed through the column, and the mercury concentration at the outlet gas was sucked and absorbed at regular intervals, and the absorption was performed. The mercury concentration of the liquid was analyzed and the removal rate was calculated.
The time-series graph is shown in FIG.

[0025]

As described in detail above, it has been found that the absorbent obtained by the production method of the present invention has higher initial performance than the comparative absorbent and retains its high mercury absorption efficiency for a long period of time. .

[Brief description of drawings]

FIG. 1 is a graph showing the results of examining the durability of mercury absorption efficiency using the absorbent material of the present invention and the comparative absorbent material, respectively.

Claims (2)

[Claims] 1. A mineral acid is added to an aqueous liquid in which lead concentrate is added and stirred to activate the surface of the concentrate, and then an organic acid is added and then hydrogen sulfide is blown into the liquid in which PbO is added and dissolved. A mercury absorbing material in a gas, characterized in that PbS is produced on the surface of lead concentrate particles, and the obtained pulp is supported on a porous carrier. 2. A first step of activating the surface of a concentrate by adding a mineral acid to an aqueous liquid in which lead concentrate is added and stirred, wherein an organic acid is added to the liquid and stirred, and then PbO is added. It is characterized by comprising a second step of dissolving and blowing hydrogen sulfide to produce PbS on the surface of the lead concentrate to obtain PbS pulp, and a third step of supporting the PbS pulp on a porous material to form a gas absorbent. Method for producing mercury absorbing material in gas.