JPS5818323B2 - Ryuu Sanchi Yuunosuiginji Yokiyohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing trace amounts of mercury dissolved in sulfuric acid.

Generally, sulfuric acid, which is produced as a by-product in the smelting of sulfide ores, contains several to tens of μm of dissolved mercury.

There is a strong demand for the removal of mercury from these sulfuric acids also from the standpoint of preventing pollution.

Many methods have already been proposed for removing mercury from the sulfuric acid.

For example, the sulfidation method separates mercury contained in sulfuric acid as mercury sulfide, which is poorly soluble in sulfuric acid, by adding sulfide, or the iodization method, which separates mercury in sulfuric acid as mercury iodide, which is poorly soluble in sulfuric acid, by adding iodide. mercury in sulfuric acid is adsorbed and separated by adding activated carbon that is impregnated with concentrated sulfuric acid and then heated in a steam atmosphere.

However, each of these methods has its own drawbacks.
It has not produced satisfactory results.

In other words, the sulfurization method has a limit to the concentration of sulfuric acid that can be used, and the sulfurization reaction does not proceed sufficiently with concentrated sulfuric acid of 97% or higher, so mercury removal is incomplete. Since a temperature of 0.degree. C. or lower is required, and the treatment must be performed under reduced pressure to reduce the amount of residual mercury to 0.5 or less, industrially, the treatment operations and equipment are complicated.

Furthermore, the adsorption method does not have a very high mercury adsorption capacity, so the amount of mercury removed and the regeneration of activated carbon are insufficient.

In addition, as a method other than the above method, metals having a higher ionization tendency than mercury, such as Al, may be used.

There is a method of substituting or amalgamating mercury in sulfuric acid with Mg, Fe, Se, Cu, etc., and separating it by filtration, but this method has the disadvantage that a large amount of the added metal remains as sulfate, and it is not suitable for industrial use. It has not been implemented.

An object of the present invention is to provide a method for removing mercury from sulfuric acid, which eliminates the drawbacks of the above-mentioned conventional methods and reduces the mercury content to below the regulatory value through extremely simple processing operations.

Therefore, this purpose was achieved according to the invention by adding an aqueous solution of copper (n) sulfate to sulfuric acid containing mercury, and then adding bromine or a compound that generates bromine in sulfuric acid under stirring to produce mercury bromide and copper bromide. This can be easily achieved by producing mercury bromide and separating the copper bromide that precipitates by adsorbing the mercury bromide.

Furthermore, in the present invention, copper powder is added to sulfuric acid containing mercury, most of the mercury is amalgamated and separated, and then bromine or a compound that generates bromine in sulfuric acid is added and treated in the same manner as above. Can be done.

Although the concentration of the aqueous copper sulfate solution added in the present invention is not particularly limited, it is preferably a saturated solution in consideration of the concentration of sulfuric acid.

The amount of copper ions added is 10 times or more, preferably 20 times or more, the weight of mercury in sulfuric acid.

In the present invention, when the copper sulfate aqueous solution is added to mercury-containing sulfuric acid and then bromine or a compound that generates bromine in sulfuric acid, such as hydrobromic acid or potassium bromide, is added under stirring, copper ions are converted into bromine and bromine. The reaction produces copper bromide, which is hardly soluble in sulfuric acid and has excellent precipitability, but at the same time, bromine reacts with mercury to produce mercury bromide, and copper bromide precipitates while adsorbing mercury bromide. Therefore, mercury and copper in sulfuric acid can be easily removed by separating this precipitate from house to house.

In this case, the amount of bromine used is at least 1.5 times equivalent, preferably 2 times equivalent, relative to the amount of dissolved copper, and if it is less than 1.5 times equivalent, all of the dissolved copper cannot be precipitated.

In addition, since bromine easily reacts with mercury in sulfuric acid, it is necessary to add bromine in an amount twice the amount of mercury.

The bromide reaction of copper is extremely fast and is sufficient at room temperature, but temperatures above 30°C are not preferred because the solubility of copper bromide increases.

Further, a reaction time of 10 to 15 minutes is sufficient, and the bromination efficiency is further improved by stirring.

Copper bromide is mainly in the form of CuBr, which, as mentioned above, has excellent precipitability and is poorly soluble in sulfuric acid.

In the present invention, as shown in the drawings, by adding copper powder to sulfuric acid, most of the mercury is first separated as copper amalgam, and then the copper amalgam is added to the sulfuric acid, which is mixed with bromine or sulfuric acid in the same manner as above. It is also possible to add a bromine-generating compound to precipitate excess copper powder remaining as dissolved copper in the sulfuric acid as copper bromide.

At this time, as described above, bromine reacts with remaining mercury to produce mercury bromide, and the copper bromide is precipitated in the form of adsorbing this mercury bromide.

Therefore, mercury and dissolved copper can be easily removed by separating this precipitate from door to door.

This method of adding copper powder is effective in reducing the amount of bromine added, especially when the mercury concentration is high.

The use of the above-mentioned copper powder is because copper forms an amalgam with mercury at room temperature in a shorter time than other amalgamating agents without forming colloidal precipitates with poor permeability. A small amount is sufficient; in this case, the excess copper powder is dissolved in sulfuric acid and exists in the form of dissolved copper, and as mentioned above, copper bromide, which is poorly soluble in sulfuric acid and is easily precipitated by bromine, is produced. This is because it is easy to obtain and can be recycled.

Regarding the particle size of the copper powder, since the substitution reaction or amalgamation between copper powder and mercury in sulfuric acid is a surface reaction, the larger the surface area of the copper powder, that is, the smaller the particle size, the more effective it is. Hereinafter, preferably 325 meshes or less are those with a mesh size of 50 or more, such as electrolytic copper grains obtained in a normal milling process.

The amount of copper powder added varies depending on the amount of mercury contained in the sulfuric acid, but if the concentration is relatively high, for example 24 ppm, 5
If it is added in an amount of 0 times or more, it is sufficient for amalgamation, but at a relatively low concentration, for example, 2 ppl [l], it is necessary to add 200 times or more.

Further, since this reaction easily proceeds at room temperature, there is no need for heating or cooling.

The stirring time is 30 minutes or more, preferably 45 minutes or more.

The reaction tank in which this amalgamation is carried out may have a simple structure equipped with a stirring device, and since the produced copper amalgam has good filterability, the filtration device may be a normal one, such as a glass filter or a cloth made of polypropylene, Teviron, etc. It is preferable to use

The present invention can be applied to sulfuric acid of various concentrations obtained by the normal sulfuric acid manufacturing process, and the mercury content can be reduced to O,'1 pp[Il
It is possible to do the following, and in that case,
There is no possibility of contaminating the sulfuric acid with residual additives.

In the present invention, the furnace-separated copper amalgam is reduced and volatilized to become reduced copper and mercury vapor, as shown in the drawing, the reduced copper can be reused as copper powder, and the mercury vapor is condensed to become mercury.

As described above, the present invention provides a method for removing mercury from sulfuric acid, which makes it possible to remove trace amounts of mercury dissolved in sulfuric acid of various concentrations through extremely simple processing operations, and to reduce the mercury concentration to below the regulatory value. This is extremely useful for pollution prevention.

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 it exceeds the gist thereof.

Example 1 Copper bromide solution containing 1.37 ppm of mercury was added with copper sulfate solution as Cu + 120 pIMll and 150 ppm to 98% concentrated sulfuric acid, and then 48% HBr was added with stirring to adsorb mercury bromide. A precipitate was formed, which was filtered through a glass filter.

Table 1 shows the analysis results of mercury and copper in sulfuric acid after door-to-door testing.

Example 2 Copper powder was added to 98% concentrated sulfuric acid containing 1.30 ppIII of mercury and stirred, most of the mercury was distributed as copper amalgam, and after the distribution, a predetermined amount of KBr was added and stirred to convert the dissolved steel into mercury bromide. It was precipitated as adsorbed copper bromide and passed through a glass filter.

Table 2 shows the analysis results for mercury and copper in sulfuric acid after door-to-door testing.

Example 3 Table 3 shows the analysis results obtained by using the same concentrated sulfuric acid as in Example 2, adding Br2 instead of K and Br0, and otherwise operating in the same manner as in Example 2.

Example 4 Copper powder 2g/l in 98% concentrated sulfuric acid containing 12.59p of mercury
After adding and furnace-separating the produced copper amalgam, 48%
HBr was added to the dissolved steel to precipitate the brominated steel adsorbing mercury bromide, which was then separated in a furnace.

Table 4 shows the analysis results for mercury and copper in the sulfuric acid after the door-to-door inspection.

Example 5 Copper powder 1.09% was added to 62% sulfuric acid containing 7.2Wm of mercury. ? /
1<g was added, the resulting copper amalgam was sent door to door, and after the door distribution, Br was added and stirred to form a precipitate of copper bromide that adsorbed mercury bromide from the dissolved steel. Table 5 shows the analysis results for mercury and copper in sulfuric acid.

[Brief explanation of the drawing]

The drawing is a system diagram of one embodiment of the present invention in which copper powder is added.

Claims (1)

[Claims] 1. Adding an aqueous solution of copper sulfate (1) to sulfuric acid containing mercury, and then adding bromine or a compound that generates bromine in sulfuric acid under stirring to produce mercury bromide and copper bromide, A method for removing mercury in sulfuric acid, which comprises separating the copper bromide which adsorbs and precipitates the mercury bromide in a furnace. 2 Copper amalgam produced by adding copper powder to sulfuric acid containing mercury is furnace-separated, and then bromine or a compound that generates bromine in sulfuric acid is added to the sulfuric acid after furnace-separation under stirring to remove mercury bromide and bromine. A method for removing mercury in sulfuric acid, which comprises producing copper bromide, adsorbing the mercury bromide, and separating the precipitated copper bromide in a furnace.