JP2016179020A - Metal mercury treatment method - Google Patents

Abstract

The present invention provides a mercury recovery method that can easily and surely reduce the mercury elution concentration below a reference value in order to landfill metallic mercury. A metal mercury processing method for generating mercury sulfide from metallic mercury and sulfur using a planetary ball mill that revolves and revolves, wherein the metallic ball and sulfur are put into a metal container provided in the planetary ball mill. A first step of operating the planetary ball mill for a predetermined time to form a sulfur layer on the inner wall surface of the metal container; and after completion of the first step, metal mercury is introduced into the metal container in which the sulfur layer is formed The problem can be solved by a metal mercury treatment method comprising the second step of generating mercury sulfide by operating the planetary ball mill for a predetermined time. [Selection] Figure 1

Description

  The present invention relates to a method for treating metallic mercury using a planetary ball mill.

  Traditionally, some of the metallic mercury used in the country has been reused, and surplus metallic mercury has been exported. However, the Minamata Convention on Mercury, adopted in October 2013, demanded stricter restrictions on mercury export and environmentally appropriate storage, but environmentally safe processing technology for metallic mercury was established. Not.

  As an environmentally safe processing technique for metallic mercury, for example, Patent Document 1 discloses a method for stabilizing liquid mercury including a step of reacting liquid mercury and elemental sulfur by a milling process in a stoichiometric condition. Has been.

Special table 2013-503729 gazette

  However, in the method described in Patent Document 1, as described in Paragraphs [0048] to [0050] of Patent Document 1, a mixture of liquid mercury and elemental sulfur is prepared and milled to obtain a black sulfide that is mercury sulfide. It is described that cinnabar sand is obtained as a reaction product. However, assuming that the mercury sulfide obtained at this stage is not yet in a stable state, mercury sulfide is added to a mixture containing aggregate, elemental sulfur and sulfur polymer as described in paragraph [0056] of Patent Document 1. A process for obtaining sulfur polymer cement is required. For this reason, in order to stabilize liquid mercury, it is necessary to mix and prepare liquid mercury with elemental sulfur and mill to obtain mercury sulfide, and to mix sulfur sulfide with aggregates to obtain sulfur polymer cement. Therefore, there is a problem that the manufacturing process is not simple.

  Mercury sulfide obtained by preparing and milling a mixture of liquid mercury and elemental sulfur adheres to and adheres to a hardened solid substance on the inner wall surface of a container provided in the ball mill when milling is performed with a ball mill. Thus, there is a problem that mercury sulfide cannot be recovered from the inner wall surface of the container unless it is pulverized by applying a strong impact to the solid using only a hammer. In addition, there is also a problem that mercury sulfide that cannot be recovered while remaining in close contact with the inner wall of the container remains in the container.

  Furthermore, Patent Document 1 has no description about the landfill reference value, and there is a problem that it is unclear whether the final product can be landfilled.

  Accordingly, the present invention provides a method capable of recovering mercury sulfide very easily and reducing the mercury elution concentration below the reference value (0.005 mg / L) for landfill treatment of metallic mercury. Let it be an issue.

  The metal mercury treatment method according to claim 1 is a metal mercury treatment method for generating mercury sulfide C from metal mercury M and sulfur S using a planetary ball mill 1 that revolves and revolves. A first step in which a metal ball 4 and sulfur S are introduced into a provided metal container 3 and the planetary ball mill 1 is operated for a predetermined time to form a sulfur layer L on the inner wall surface of the metal container 3; After the process is completed, a second process is performed in which metal mercury M is put into the metal container 3 in which the sulfur layer L is formed, and the planetary ball mill 1 is operated for a predetermined time to generate mercury sulfide C.

  The metal mercury treatment method according to claim 1 uses a self-revolving planetary ball mill 1, and simultaneously puts metal mercury M and powdered sulfur S into a metal container 3 of the planetary ball mill 1, When mercury sulfide C is generated by operating 1, the hardened solid matter adheres and adheres firmly to the inner wall surface of the metal container 3, and the metal container 3 is not subjected to a strong impact using only a hammer. There is a problem that the mercury sulfide C cannot be recovered from the inner wall surface of the metal, and there is a problem that the strongly fixed mercury sulfide C remains in the metal container 3. Since the mercury sulfide C is produced in a smooth and powdery form without the mercury sulfide C adhering to the inner wall surface, there is an effect that the mercury sulfide C can be recovered very easily from the inside of the metal container 3 with a spoon.

  Further, the mercury elution concentration of the metal mercury M can be easily and reliably lowered to less than the landfill reference value.

It is a flowchart of the metal mercury processing method of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the 1st process of the metal mercury processing method which concerns on this invention with sectional drawing of a metal container, (a) is a figure of the state which put the metal ball | bowl and sulfur in the metal container, (b) is a planetary ball mill. It is the figure which acted and formed the sulfur layer. FIG. 3 is an explanatory view showing a second step of the metal mercury treatment method according to the present invention by a cross-sectional view of a metal container, (a) is a view showing a state in which metal mercury is put into the metal container, and (b) is an operation of the planetary ball mill. (C) is the figure in the metal container after recovering mercury sulfide from the inside of the metal container. 1 is a schematic plan view showing a self-revolving planetary ball mill used in a metal mercury treatment method according to an embodiment of the present invention. It is a figure which shows the physical property of the used metal mercury. It is explanatory drawing of the form of the mercury sulfide shown by sectional drawing of a metal container at the time of throwing metal mercury and sulfur simultaneously, (a) is a case where mixing molar ratio (S / Hg) is 1.05, (b ) Is when the mixing molar ratio (S / Hg) is 1.5. It is a graph which shows the experimental result of Example 1 in this invention. It is a graph which shows the experimental result of Example 2 in this invention. It is a graph which shows the experimental result of Example 3 in this invention. It is a graph which shows the experimental result of Example 4 in this invention. It is a graph which shows the experimental result of Example 5 in this invention. It is a graph which shows the experimental result of Example 6 in this invention. It is a graph which shows the experimental result of Example 7 in this invention. It is a graph which shows the experimental result of Example 8 in this invention.

  The metallic mercury treatment method according to the present invention is a metallic mercury treatment method for producing mercury sulfide C from metallic mercury M and sulfur S using a planetary ball mill 1 that rotates and revolves as shown in the flowchart of FIG. A metal ball 4 and sulfur S are put into a metal container 3 provided in the planetary ball mill 1, and the planetary ball mill 1 is operated for a predetermined time to form a sulfur layer L on the inner wall surface of the metal container 3. After one step 10 and the first step, metal mercury M is charged into the metal container 3 in which the sulfur layer L is formed, and the planetary ball mill 1 is operated for a predetermined time to generate mercury sulfide C. And two steps 20.

  As shown in FIG. 4, the planetary ball mill 1 includes a plate-like rotary table 2, a metal container 3 having a cylindrical appearance, and a plurality of spherical metal balls 4. The turntable 2 has a circular flat plate shape and is rotated around its center by a motor. There are two metal containers 3 above the rotary table 2 at locations off the center of the rotary table 2 (two locations in FIG. 4, but in general the number increases or decreases depending on the size of the rotary table 2. ) Are provided and each rotates. A sealing lid 3 a is provided at the upper end opening of the metal container 3. Then, the rotary table 2 and the metal container 3 rotate in opposite directions (for example, if the rotary table 2 is clockwise, the metal container 3 is counterclockwise). The plurality of metal balls 4 are put into the metal container 3 and roll inside the metal container 3 by rotational force or centrifugal force while the planetary ball mill 1 is in operation.

The metal mercury treatment method will be described with reference to FIGS. In the first step 10, step 11 (FIG. 2A) in which a plurality of metal balls 4 and powdered sulfur S are put into the metal container 3 is performed, and step 12 for operating the planetary ball mill 1 for a predetermined time is performed. To do. As a result, a sulfur layer L formed of sulfur S is formed on the inner surface of the metal container 3 (FIG. 2B). Note that the sulfur layer L is formed by the metal balls 4 rolling on the inner surface of the metal container 3 by the rotational force or centrifugal force obtained by the rotation of the turntable 2 and the metal container 3, and the metal balls 4 colliding with each other. Sulfur S is crushed by the collision between the ball 4 and the inner surface of the metal container 3, and is formed by centrifugal force against the sulfur S.

  Further, in the second step 20, after the first step 10 is completed, a step 21 (FIG. 3A) in which the metal mercury M is put into the metal container 3 in which the sulfur layer L is formed is performed, and the planetary ball mill Step 22 is performed to operate 1 for a predetermined time. As a result, the metal mercury M is converted into mercury sulfide C (FIG. 3B). The chemical formula at this time is represented by Hg + S = HgS. And the mercury elution density | concentration of the produced | generated mercury sulfide C (HgS) can be reduced to less than a landfill reference value. Then, the generated mercury sulfide C is taken out from the metal container 3 (step 23). Since the produced mercury sulfide C is rustle and powdery, it does not adhere to the inner surface of the metal container 3 and can therefore be easily removed from the metal container 3 with a spoon. Mercury sulfide C hardly remains in the metal container 3 after the mercury sulfide C is taken out (FIG. 3C).

  Next, the effect of the metal mercury treatment method according to the present invention was confirmed by a plurality of experiments. In these experiments, a self-revolving planetary ball mill (Pulverisete 7) 1 manufactured by Fritsch was used. The metal container 3 was made of stainless steel and had a capacity of 47 ml. The metal balls 4 were also made of stainless steel.

  Next, the physical properties of the used metal mercury will be described. FIG. 5 shows the results of the metal mercury ring No. 13 dissolution test and the pH dependence test. In the Notification No. 13 dissolution test, the mercury elution concentration was 0.14 mg / L at pH 6.5, which was approximately 28 times higher than the mercury reclamation standard value of 0.005 mg / L. Further, from the pH dependence test, it was easy to elute on the neutral side, and the concentration was 0.1 to 0.2 mg / L. This was about 2.8 times the solubility at pH 4 and about 3.6 times at pH 12.

  Further, “processing time (minutes)” described in the drawings in the following examples means the processing time in the second step 20. Incidentally, the processing time of each first step 10 was 30 minutes. Further, in each of the following examples, the mercury sulfide C after the completion of the second step 20 is in the form of a free-flowing powder so that it is not fixed in the metal container 3, and therefore can be easily taken out from the metal container 3. I was able to.

First, as a comparative example, using a planetary ball mill 1 that revolves and revolves, metal mercury M, sulfur S, and metal balls 4 are introduced into a metal container 3, and the planetary ball mill 1 is operated for a predetermined time. The conditions were as follows: metal ball diameter 10 mm, revolution number 200 rpm, rotation / revolution number 1.8, amount of treated mercury 20 g per batch, number of balls 12 and mixing molar ratio (S / Hg) 1.05. FIG. 6A shows the case of 60 minutes, and FIG. 6B shows the case where the mixing molar ratio (S / Hg) is 1.5 and the processing time is 60 minutes.

As a result, when the mixing molar ratio (S / Hg) is reduced, the mercury sulfide is thin and strongly fixed in the metal container 3 as shown in FIG. It took a great deal of time to clean. Further, when the mixing molar ratio (S / Hg) is increased, mercury sulfide becomes a large solid as shown in FIG. 6 (b), and the solid is firmly adhered and fixed to the metal container 3. It was crushed and peeled off with an impact only. However, the solid substance firmly fixed to the inner wall surface of the metal container 3 remained without being removed.

In the case of the comparative example in which the metallic mercury M and the sulfur S are simultaneously charged and the planetary ball mill 1 is operated, the trial was carried out 10 times, and the crushing and removing were performed while applying the impact only with the hammer 10 times The distribution of the recovery rate for each run was 13-46% by weight. As described above, the recovery rate is low in addition to the difficult recovery operation. The recovery rate in the present invention means the ratio of the weight of recovered mercury sulfide C when the total weight of the introduced metal mercury M and sulfur S is 100%. For example, when a total of 80 g of 20 g of metallic mercury and 60 g of sulfur is charged, the recovery rate is 100% if the weight of the recovered mercury sulfide is 80 g.

Next, the recovery rate of metallic mercury C was verified by the metallic mercury treatment method of the present invention. As a condition, using a planetary ball mill 1 that revolves and revolves, the diameter of the metal balls is 10 mm, the number of revolutions is 200 rpm, the number of revolutions / revolutions is 1.8, the amount of treated mercury is 20 g, and the number of metal balls is 12 The mixing molar ratio (S / Hg) was set to 3. FIG. 2B shows the state in the metal container 3 after the first step 10 in which the sulfur S and the metal balls 4 are introduced into the metal container 3 and the planetary ball mill 1 is operated for 30 minutes. FIG. 3B shows the state in the metal container 3 after the second step 11 in which the planetary ball mill 1 is operated for 90 minutes with M inserted, and then the state after the mercury sulfide C in the metal container 3 is taken out. As shown in FIG.

As shown in FIG. 2B, after the first step 10, the sulfur layer L is attached to the inner wall surface of the metal container 3. After the second step 11, as shown in FIG. 3 (b), the black mercury sulfide C free-flowing powder is generated on the bottom and side surfaces of the metal container 3, and is easily scooped out with a spoon. it can. As a result, as shown in FIG. 3C, almost no mercury sulfide C remains in the metal container 3, and the inner surface of the metal container 3 shines white in the original stainless steel color of the metal container 3. As a result of carrying out this test for 42 samples, the distribution of the recovery rate for each of 42 times was 94 to 99% by weight. This is generated by performing the steps of the first step 10 for introducing sulfur S and the second step 11 for adding metal mercury M, compared to the case where sulfur S and metal mercury M are simultaneously added. It was shown that the recovery rate of mercury sulfide C was greatly improved.

Next, the processing time according to the mixing molar ratio (S / Hg) and the change over time in the mercury elution concentration were examined. As conditions, the number of revolutions was 200 rpm, the number of rotations / revolutions was 1.8 and the amount of treated mercury in one batch was 20 g, and the diameter and number of metal balls were changed. The capacity of the metal container 3 was 47 ml.

FIG. 7 shows the results when the metal ball diameter is 15 mm and the number is 7 and the mixing molar ratio is 1.5, 2 or 3.

  From FIG. 7, it was confirmed that when the mixing molar ratio was 3, the mercury elution concentration could be reduced to less than the landfill reference value (0.005 mg / L) in a treatment time (second step 11) of 30 minutes. . Further, it was shown that when the mixing molar ratio was 1.5 and 2.0, the mercury elution concentration was lowered to less than the landfill reference value in the processing time of the second step 11 of 60 minutes.

FIG. 8 shows the results when the metal ball diameter is 15 mm, the number is 2 and the mixing molar ratio is 3, and the number is 4 and the mixing molar ratio is 1.5 and 3.

  From FIG. 8, when the mixing molar ratio was 3 and the number of the metal balls 4 was 4, it was confirmed that the mercury elution concentration was reduced to less than the landfill reference value in a treatment time of 30 minutes (second step). . In addition, when the mixing molar ratio is 3 and the number of metal balls 4 is 2, and when the mixing molar ratio is 1.5 and the number of metal balls 4 is 4, the mercury elution concentration is landfilled in a processing time of 60 minutes. It was shown that it can be reduced below the reference value.

Next, FIG. 9 shows an implementation result when the number of metal balls is 10 mm, the number of the metal balls is 12, and the mixing molar ratio is 1.05, 1.5, 2, or 3.

From FIG. 9, when the mixing molar ratio was 3 and 2, it was confirmed that the second step 11 can reduce the mercury elution concentration to less than the landfill reference value in a treatment time of 30 minutes. Moreover, when the mixing molar ratio was 1.5, the mercury elution concentration could be reduced to less than the landfill reference value in a treatment time of 60 minutes. It was also confirmed that when the mixing molar ratio was 1.05, a treatment time of 90 minutes was required in order to reduce to the landfill reference value.

Next, in the case where the metal ball diameter is 10 mm, when the number is 3 and the mixing molar ratio is 3, the implementation results when the number is 6 and the mixing molar ratio is 1.5 and 3 are shown in FIG. This is shown in FIG.

From FIG. 10, when the mixing molar ratio was 3 and the number of balls was 6, it was confirmed that the second step 11 reduces the mercury elution concentration to less than the landfill reference value in a treatment time of 30 minutes. Further, when the mixing molar ratio is 3 and the number of metal balls 4 is 3, it can be confirmed that the mercury elution concentration is not stable in 90 minutes in order to reduce the mercury elution concentration to less than the landfill reference value, and the mixing molar ratio is 3 When the number of metal balls 4 was 6, it was confirmed that the mercury elution concentration was reduced to less than the landfill reference value in a processing time of 60 minutes.

From FIG. 7 to FIG. 10, when a metal ball diameter of 15 mm is used, even if the number of metal balls is changed to 2 to 7 and the mixing molar ratio (S / Hg) is changed to 1.5 to 3, If the processing time is required, the mercury elution concentration can be reduced below the landfill reference value. Further, when a metal ball diameter of 10 mm is used, if the number of metal balls 4 is 12, even if the mixing molar ratio is changed to 1.05 to 3, mercury can be used if the processing time is required. The elution concentration can be lowered below the landfill reference value. However, when a metal ball diameter of 10 mm is used, the mercury elution concentration is not stable when the number of metal balls 4 is 6 or less and the mixing molar ratio (S / Hg) is 3 or less.

Further, if the plurality of metal balls 4 are within a range in which the metal balls 4 can sufficiently roll within the metal container 3, the mixing molar ratio (S / Hg) increases as the diameter of the metal balls 4 increases and the number of the metal balls 4 increases. As the value increases, the processing time of the second step 11 can be shortened, and the mercury elution concentration can be lowered below the landfill reference value.

From these, the inner volume of the metal container 3 is determined, and so that the mercury elution concentration of the generated mercury sulfide C can be reduced to less than the landfill reference value, the diameter of the metal balls 4, the number of metal balls 4, and the mixing molar ratio (S / By setting Hg), it was shown that the metal mercury treatment method according to the present invention sufficiently functions and is effective for conversion of metal mercury to mercury sulfide.

Next, the treatment time in the second step 11 according to the diameter of the metal balls 4 and the number of the balls and the change with time in the mercury elution concentration were examined. As conditions, the number of revolutions was 200 rpm, the number of rotations / revolutions was 1.8 and the amount of treated mercury in one batch was 20 g, and the mixing molar ratio (S / Hg) was changed for testing. The capacity of the metal container 3 was 47 ml.

FIG. 11 shows the results when the diameter of the metal balls 4 is 15 mm, the mixing molar ratio is 3, and the number of metal balls 4 is 2, 4, and 7.

From FIG. 11, when the number of the metal balls 4 was 4 and 7, it was confirmed that the mercury elution concentration was reduced to less than the landfill reference value in a processing time of 30 minutes. Moreover, when the number of the metal balls 4 is two, it has been shown that the mercury elution concentration is reduced to less than the landfill reference value in a processing time of 60 minutes.

FIG. 12 shows the results when the metal ball diameter is 15 mm, the mixing molar ratio is 1.5, and the number of metal balls is 4 and 7.

From FIG. 12, when the number of the metal balls 4 is four, it has confirmed that the mercury elution density | concentration was reduced to less than a landfill reference value in the processing time of 30 minutes. When the number of metal balls 4 was seven, the mercury elution concentration could be reduced to less than the landfill reference value in a processing time of 60 minutes.

Next, FIG. 13 shows the results when the metal ball diameter is 10 mm, the mixing molar ratio is 3, and the number of metal balls 4 is 3, 6, and 12.

  From FIG. 13, when the number of metal balls 4 is 12, it can be confirmed that the mercury elution concentration is reduced to less than the landfill reference value in a processing time of about 30 minutes, and when the number of metal balls 4 is six. Was able to bring the mercury elution concentration below the landfill reference value in a treatment time of 60 minutes. When the number of metal balls 4 was 3, the mercury elution concentration could be made less than the landfill reference value in 30 minutes, but it became unstable after 60 minutes.

Next, FIG. 14 shows the results when the metal ball diameter is 10 mm, the mixing molar ratio is 1.5, and the number of balls is 6 and 12.

  From FIG. 14, when the number of metal balls 4 was 12, the mercury elution concentration could be reduced to less than the landfill reference value in a processing time of 60 minutes. In addition, when the number of metal balls 4 was 6, the mercury elution concentration could be once lowered to less than the landfill reference value in a processing time of about 30 minutes, but then became unstable.

  From FIG. 11 to FIG. 14, when the metal ball diameter is 15 mm, the processing time is 90 even when the mixing molar ratio (S / Hg) is 3 or 1.5 and the number of metal balls 4 is reduced from 7 to 4 or 2. In all cases, the mercury elution concentration could be reduced to less than the landfill reference value. However, in the case of a metal ball diameter of 10 mm, the mixing molar ratio (S / Hg) is 3 or 1.5, and as the number of balls is reduced from 12 to 6 or 3, the mercury elution concentration becomes unstable and the landfill standard Some cases were exceeded.

  From the above eight examples, it was confirmed that the method for treating metal mercury M of the present invention using the self-revolving planetary ball mill 1 was effective. In the implementation, since the type of the planetary ball mill 1 of revolution and revolution to be used is different and the inner volume of the metal container 3 is different, first, the inner volume of the metal container 3 is determined and the mercury of the generated mercury sulfide C is generated. What is necessary is just to set the metal ball 4 diameter, the number of metal balls 4, and a mixing molar ratio (S / Hg) so that an elution density | concentration can fall below landfill reference value.

Also, the first step of forming the sulfur layer L on the inner wall surface of the metal container 3 by putting the metal balls 4 and sulfur S into the metal container 3 provided in the planetary ball mill 1 and operating the planetary ball mill 1 for a predetermined time. 10 and after completion of the first step 10, a metal mercury M is charged into the metal container 3 in which the sulfur layer L is formed, and the planetary ball mill 1 is operated for a predetermined time to generate mercury sulfide C. By the metal mercury M treatment method of the present invention provided, mercury sulfide C can be taken out from the metal container 3 very easily, and the recovery rate of mercury sulfide C, which is a product of the metal mercury M and sulfur S, has been dramatically improved. It was possible to improve.

DESCRIPTION OF SYMBOLS 1 Planetary ball mill 2 Rotary table 3 Metal container 3a Sealing lid 4 Metal ball 10 1st process 11 2nd process M Metal mercury S Sulfur L Sulfur layer C Mercury sulfide

Claims (1)

A metal mercury treatment method for producing mercury sulfide from mercury metal and sulfur using a planetary ball mill that rotates and revolves,
A first step of throwing metal balls and sulfur into a metal container provided in the planetary ball mill, and operating the planetary ball mill for a predetermined time to form a sulfur layer on the inner wall surface of the metal container;
After the first step, the second step of charging the metal container in which the sulfur layer is formed with metal mercury and operating the planetary ball mill for a predetermined time to generate mercury sulfide, Metal mercury treatment method.

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