JPS62278236A - Method and apparatus for recovering mercury from mercury-containing waste - Google Patents

Abstract

PURPOSE:To simply and easily recover high-purity mercury with substantially no discharge of a mercury-contg. gas to the outside of the system by cooling the mercury vapor-contg. gas to form the mercury mists, then subjecting the mists to a membrane sepn. CONSTITUTION:The waste contg. the mercury and/or a compd. to form the mercury vapor when heated, is heated in a heating furnace, etc., (not shown) to evaporate the mercury. The gas contg. the mercury vapor formed in such a manner is introduced into a mercury separator 2 provided with a suction fan 4 from a gas introducing pipe 1. The above-mentioned gas is cooled to form the mercury mists. The above-mentioned cooling is preferably executed by bringing the gas into contact with a packing material such as porous ceramics which does not react with the mercury. The mercury mists formed in such a manner are separated and recovered from the gas by a separating membrane 3 at <=350 deg.C, more preferably <=200 deg.C. The separating membrane 3 is preferably made of ceramics such as Al2O3, TiN, Si3N4 or SiC which is further coated with Fe, Ni, Co, Mn, etc., and has <=50mu pore size and 30-80% voids.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is based on mercury? or waste containing mercury compounds that generate mercury vapor when heated? The gas is heated to produce a gas containing mercury vapor, the gas is cooled to form a mercury vapor mist, and then the gas is separated into water by membrane separation.
The present invention relates to a method and apparatus for separating and recovering .

[Conventional technology and its problems]

Until now, there was no appropriate treatment method for waste containing mercury and/or mercury compounds, and it was either (1) piled up in the open, (2) solidified with concrete, or (3) landfilled as non-combustible garbage. None of these methods are drastic, and environmental pollution due to the leaching of mercury or mercury compounds has become a problem.Especially, when buried as non-combustible waste, mercury becomes organic and becomes more harmful. There is no desire to establish an effective treatment method for waste containing mercury and/or mercury compounds.

Also, mercury vapor like fluorescent lights and mercury lamps? After crushing the used equipment containing it in a sealed container, it is heated to gasify the water, and the gas is cooled to release mercury. Method of recovery (Unexamined Japanese Patent Publication No. 55-
F61038 Publication, Japanese Unexamined Patent Application Publication No. 56-659st)
, a method in which all waste containing mercury and/or mercury compounds is heated with microwaves to generate mercury vapor, and the mercury vapor is cooled or amalgamated and recovered (Japanese Patent Application No. 59-F80411, Patent Application No. (Sho 59-250594)
etc. have also been proposed.

These methods of recovering vaporized mercury by heating using a cooling method or an amalgam method have the following drawbacks.

1) Cooling method ■ Cooling is done with high-temperature gas containing mercury (using phase change), so cooling capacity needs to be increased and equipment becomes larger.

(2) Since all of the condensable components are liquefied, the purity of the recovered mercury is poor, and further purification equipment is required to purify the crude mercury by distillation or the like.

■ After the gas is sucked from the combustion section to the cooling section and the mercury is recovered, the gas is discharged into the atmosphere, but since the gas still contains a small amount of mercury, gas cleaning equipment is not installed. It is necessary to add more.

2) Amalgam method After amalgam formation, gasification by heating is required again, which complicates the equipment and requires larger equipment.

In addition, a method in which a divalent mercury salt is supported on a porous material such as activated carbon, activated alumina, silica gel, bentonite, or acid clay is passed through a gas containing mercury vapor to completely adsorb and remove mercury (Japanese Patent Publication No. 15057/1982). This publication also discloses a method for recovering mercury from gas using chemicals such as nitric acid, sulfuric acid, sulfide, and sodium hyposulfite. There are also known methods of removing trace amounts of mercury contained in the gas by using activated carbon or molecular sieves, but in these methods,
There have been problems such as waste plate adherents that fully support or adsorb mercury, chemicals that have reacted with mercury, etc. are not secondary wastes, and a means for further processing these secondary wastes is required.

[Purpose of the invention]

The present invention completely heats waste containing mercury or a mercury compound that generates mercury vapor when heated, and collects mercury mist or mercury vapor from the generated gas containing mercury vapor by membrane separation, thereby removing mercury from the system. Contains gas? High purity mercury with almost no emissions? It is an object of the present invention to provide a method for recovering and an apparatus for the same.

[Structure of the invention]

The present invention is directed to: ■ Waste containing mercury and/or compounds that generate mercury vapor upon heating? A method of recovering mercury by evaporating it by heating, which is characterized by cooling a gas containing mercury vapor, turning it into mercury mist, and then separating it through a membrane.Contains mercury or a compound that generates mercury vapor when heated. Mercury from waste? How to collect. and (1) An apparatus for recovering waste containing mercury and/or a compound that generates mercury vapor upon heating to completely evaporate the mercury, at least a heating section for heating the waste and a separation membrane. 1. An apparatus for recovering mercury from waste containing mercury or a compound that produces mercury vapor when heated, comprising a mercury separator and a gas suction section.

It is.

Waste containing mercury includes used appliances such as mercury batteries, dry batteries, thermometers, thermometers, pressure gauges, fluorescent lamps, mercury lamps, mercury switches, IT meters, rectifiers, used mercury catalysts, inorganic chemicals, etc. or waste containing mercury compounds, salt water mud, drainage sludge, mercury-containing sludge such as earth and sand, activated carbon,
There are waste products such as chelate resins and other used mercury adsorbents, and mercury batteries and alkaline batteries in particular contain a large amount of mercury, and the present invention is particularly suitable for recovering all mercury from these waste batteries.

Next, the present invention will be explained in detail based on the drawings.

FIG. 1 shows an embodiment of an apparatus for heating waste material, such as dry cell batteries, containing mercury or a compound that produces mercury vapor when heated, and recovering mercury from the produced gas containing mercury vapor. .

Although not shown, mercury or mercury vapor by heating?
Mercury vapor generated by heating the waste in a total heating furnace, including the generated compounds? The contained gas is sucked in by a suction fan 4 located behind the mercury separation membrane of the mercury separator 2 and guided to the mercury separator 2 through the conduit 1.

Although the heating temperature in the heating furnace varies depending on the type of waste, it is preferably heated to a temperature in the range of 100°C to 700°C, particularly 350°C to 550°C. For example, it is preferable to heat at a relatively low temperature when mercury is contained as a single mercury, and at a relatively high temperature when mercury is amalgamated or strongly bound to an adsorbent. The most preferred temperature is 400-550°C. this is.

This is because mercury exists as mercury at temperatures above 400°C and may become oxidized mercury at temperatures below 400°C), and mercury in the form of compounds is also decomposed to produce mercury.

Further, as the heating means in the heating furnace, it is preferable to use microwave heating or induction heating because the heating temperature can be easily controlled.

Mercury vapor led to mercury separator 2? The contained gas is cooled through the entire wall of the separator or, if present, by the packing 16 in the separator 2, and most of the mercury vapor contained becomes a mist or liquid, and the mercury vapor contained in the separator is cooled. The mercury condenses on the vessel wall or the filling, and is separated from the gas by further condensation growth.On the other hand, the mercury that is not separated and exists in the form of mist is collected by the mercury separation membrane 3, and the mercury is collected on the vessel wall or the filling. The mercury separated above falls to the bottom of the mercury separator 2 and is cooled to room temperature or lower through a conduit in a cooler 7 which is cooled by a cooling medium 8 to lower the vapor pressure. The mercury is then collected in a mercury collection container. Further, even if mercury exists in vapor form, it is completely separated because it is cooled by the mercury separation membrane and condensed on the separation membrane.

The temperature of the mercury separator may be maintained at a temperature that can turn most of the mercury vapor into mist or liquid, and is 350°C or lower, preferably 200°C or lower, and more preferably 80°C to 150°C.
The temperature can be appropriately selected depending on the mercury recovery rate, purity, properties of the mercury separation membrane, suction fan capacity, heating temperature in the heating furnace, recovery efficiency (economic efficiency), etc.

In addition, a part of the gas in the mercury separator 2 is sucked by the pump 5 installed on the downstream side of the cooler 7 and circulated to the heating furnace, thereby lowering the vapor pressure of mercury in the cooler 7. It is preferable to condense mercury vapor to improve the recovery efficiency of mercury and to improve the separation efficiency of mercury condensed on the wall or packing of the mercury separator.

The mercury separation membrane used in the present invention has a wide surface area,
Any material may be used as long as it can efficiently separate mist or liquid mercury and has stable separation ability over a long period of time.

The mercury separation membrane preferably has a pore diameter of 50 μm or less, preferably 30 μm or less, more preferably 15 μm or less.

In addition, the porosity depends on the mechanical strength of the material, but when using ceramics as the material, the porosity is 20 to 80.
%, usually about 40 to 70% is preferred.

Since mercury has a contact angle of 90', theoretically liquid mercury will not pass through the membrane under atmospheric pressure if the pore size is 15 μm or less, but even if it is larger than this, it will be sufficiently captured. .

The material of the mercury separation membrane is preferably an inorganic material, particularly a ceramic material. 81C for ceramics,
az, on, Tin, 813N4, etc. are used, and after molding into a desired shape using a relatively large crystal grain size, for example, 60 μm, it is fired by a conventional method to obtain a pore size within the pre-air range. It is possible to obtain a material having porosity.

Alternatively, a material made by laminating two types of ceramics can also be used. That is, in this case, by laminating a thin ceramic with a small pore size to a ceramic with a large pore size, a membrane with high mechanical strength, low pressure loss, and high efficiency in separating mercury 2 can be created. Obtainable.

Are there any metals that do not produce mercury and amalgam on the surface of ceramics, such as iron, nickel, cobalt, and manganese? Separation membrane with greater strength due to coating? So in this case thin ceramics can be obtained?
This means that it can be used. Also, the pore size can be improved by coating the metal? This is preferable because it can be made smaller.

Any metal coating method may be used as long as the ceramic can be coated, but thermal spraying, vapor deposition, or coating is usually used.

The structure of the mercury separation membrane is plate-like or pleated (wavy).
, cylindrical or tubular, any shape can be used.

Next, a detailed explanation of the present invention will be explained with reference to the drawings of an embodiment.

Figure 1 shows how a dry battery is heated and separated from a gas containing mercury vapor. An example of a recovery device? show.

A gas containing mercury vapor (main components being air and water vapor) produced by heating a waste dry battery in a heating furnace (not shown) is led through a conduit 1 to a mercury separator 2 having an inclined bottom.

A mercury separation membrane 3 is installed in the mercury separator 2, and mercury vapor from the heating furnace? The contained gas is sucked by the suction fan 4, and gases other than mercury, ie, air, water vapor, etc., are sent to the rear of the suction fan 4.

On the other hand, most of the mercury vapor becomes mist or liquid in the mercury separator 2, is separated from the gas in the mercury separation membrane 3, condenses and grows, and is circulated together with the gas by the suction fan 5 in a 6ft conduit.
, and then led to the cooler 7.

After being circulated through a cooler and cooled by a cooling medium 8, it is collected in a mercury collection container 9. On the other hand, mercury vapor contained in the gas circulated by the suction fan 5 is also cooled and condensed in the cooler, promoting recovery of mercury.

The gas sucked by the suction fan 5 is sent to the heating furnace and used as recycled gas to improve heating efficiency.

The temperature of the mercury separator should be the temperature at which most of the mercury vapor becomes mist or liquid, preferably 350°C or less, preferably 2
The temperature may be 00°C or lower, most preferably 80°C to 150°C.

Mercury recovery rate, purity, mercury content [membrane properties, suction fan capacity,
It can be determined as appropriate depending on the upstream gas level, economic efficiency, etc.

Any mercury separation membrane may be used as long as it can efficiently separate mercury from other gases (air, water vapor, etc.) and has durability, cleanability, and mechanical strength.

However, ceramic is preferred from the viewpoint of heat resistance, durability, cleanability, mechanical strength, etc.

The mercury separator may have any shape as long as it has a mercury separation function. Usually a square or cylindrical shape is used, with a slanted bottom and a mercury collector underneath. It is preferable to install

The performance of the mercury separator can be improved by filling the lower part of the mercury separation membrane 3 with a filler.

It is preferable that the filling has a large porosity so as not to cause drifting flow, a small specific gravity, a large mechanical strength, and from which #M and liquefied mercury can easily be desorbed. The shape may be of any shape, such as a Raschig ring, ledge/grinod, Berle saddle, or interlock saddle type.

The filling can be any material that does not form amalgam with mercury. Usually, it is preferable to use ceramic or ceramic coated with one or more metals selected from iron, nickel, cobalt, and manganese.

Mercury vapor condenses on the filling, grows and falls downward. As a filler, organic resins such as fluororesin, iron,
Metals such as nickel are also used, but the former has poor heat resistance and thermal conductivity, and the latter is heavy.

The condenser 7 is for removing trace amounts of mercury vapor from the recycled gas, and is unnecessary if the mercury concentration is negligible.

FIG. 2 shows a block diagram of the entire apparatus for recovering mercury from used dry batteries.

The used waste dry batteries are fed into the pre-processing device 10 via a raw material receiving tank (not shown), and in the pre-processing device 10, the metal exterior is removed to a crushing and sorting machine, where they are subjected to magnetic separation, repulsion, electrostatic separation, etc. Depending on the separation method, it is roughly divided into a metal part, an electrode part containing mercury, and an electrolyte part.

The parts other than metal are sent by a feeder to a raw material supply section in the pretreatment device, where an alkaline substance is added and mixed. Alkaline substance? This is to decompose and liberate the mercury present as a compound added.

The waste to which alkaline substances have been added and mixed is fed from the raw material supply section to the heating furnace 11 through a feeder, and here the microwave from the microwave generator 12 passes through the microwave conduit 13 to the waste in the heating furnace 11. It is irradiated and heated. Here, the water contained in the waste, the carbonaceous material, and a part of the added alkaline material selectively absorb microwaves, and the raw material is heated efficiently.

The heating is performed while introducing recycled gas from the suction fan 5 from the downstream side of the water chain collector 9 and while stirring with a stirring blade or the like, thereby promoting vaporization of mercury in the raw material.

The heating temperature is 100°C to 700°C, usually preferably 350°C.
The optimum temperature range varies from ℃ to 550℃ depending on the tj of the raw materials. For example, when mercury is contained as a single mercury, the temperature is relatively low, and when mercury is amalgamated, strongly bound to an adsorbent, or exists as a mercury compound, the temperature is relatively high.

mercury? The containing gas is introduced into the mercury separator 2 after being adjusted to an appropriate temperature, and gases other than mercury (air, water vapor, etc.) are introduced into the mercury separator 2.

A trace amount of ammonia) is sucked in by a suction fan 4, and after being washed away by a gas scrubbing tower 14, it is discharged from a chimney 15.

On the other hand, the mercury separated in the mercury separator 2 is collected in a mercury recovery container 9.
It is absorbed by the suction fan 5 in the wake of.

The mercury is collected in a mercury collection container 9.

The gas from the suction fan 5 of the mercury recovery container 9 is sent to the heating furnace 11 as a recycled gas, and is used to improve the heating efficiency in the heating furnace.

3 and 4 show a mercury separation function with a mercury separation membrane of a different form than that shown in FIG. 1. Figure 3 shows an inverted U
An example with a cylindrical mercury separation membrane in the shape of a letter is shown, and FIG. 4 shows a row with a pipe-shaped mercury separation membrane.

Further, Table 1 shows an example of the configuration of a mercury separation membrane.

Table 1 Separation membrane structure 1j [Example] The following batteries were selected from among commonly used dry batteries and tested.

Table 2 Types of dry cell batteries and numbers used The samples shown in Table 2 were removed from their metal packaging, placed in a heating furnace of about 16 liters, and then heated with calcium hydroxide (Ca(OH)z) 5
．． After adding and stirring thoroughly, air was supplied for 100-7 minutes, irradiated with microwaves, heated at about 500°C for 20 minutes, and the generated gas was cooled to 100°C and 200°C, and the ceramic membrane was heated. The generated gas was introduced into the installed mercury separator and sucked out behind the ceramic membrane. Meanwhile, in another direction of the mercury separator (
A mercury recovery container is installed at the bottom of the separator to collect part of the generated gas.
I aspirated it. Mercury concentration in the exhaust gas behind the mercury recovery container and ceramic membrane kDi.

The results are shown in Table 3.

Table 3 Amount of mercury in condensed components and amount of mercury in exhaust gas The mercury separation membrane used in the practical example is as follows.

A disc-shaped ceramic made of silicon carbide with an average pore diameter of 16μ.
A material with a porosity of 40 mm and a thickness of 8 gm was used.

〔Effect of the invention〕

According to the present invention, mercury can be easily recovered with high purity from waste containing mercury and/or mercury compounds using a miniaturized and simplified device.

[Brief explanation of the drawing]

Figure 1 shows mercury vapor separated by heating a dry battery? An example of an apparatus for recovering mercury from gas containing it? show. FIG. 2 shows a schematic block diagram of an embodiment of the entire apparatus for recovering mercury from used dry batteries. Are the mercury separation membranes in FIGS. 3 and 4 different from the mercury separation membrane shown in FIG. 1? A schematic diagram of a biased mercury separator is shown. 1... Gas introduction pipe from the heating furnace, 2... Mercury separator, 3... Mercury separation membrane, 4, 5... Suction fan, 6...
... Conduit, 7... α compressor, 8... Cooling medium, 9...
・Mercury recovery container, 10... Pretreatment device, 11... Heating furnace, 12... Microwave generator, 13... Waveguide, 14... Cleaning tower Patent applicant Ebara General Corporation Research Institute: Ebara Corporation

Claims (1)

[Claims] 1. In a method of recovering mercury-containing waste by heating it to evaporate the mercury, mercury is separated from the gas by cooling the mercury vapor-containing gas, turning the mercury into a mist, and then performing membrane separation. A method for recovering mercury from waste containing mercury. 2. A method for recovering mercury from mercury-containing waste according to claim 1, which comprises membrane separation at a temperature of 350° C. or lower. 3. A method for recovering mercury from mercury-containing waste according to claim 1 or 2, which comprises membrane separation at a temperature of 200° C. or lower. 4. A method for recovering mercury from mercury-containing waste according to claim 1, 2 or 3, wherein the separation membrane used for membrane separation is made of ceramics. 5. The method for recovering mercury from mercury-containing waste according to claim 4, wherein the ceramic is aluminum oxide, titanium nitride, silicon nitride, or silicon carbide. 6. A method for recovering mercury from mercury-containing waste according to claim 4 or 5, wherein the ceramic separation membrane used as the separation membrane is coated with metal. 7. Mercury according to claim 6, wherein the metal coating the surface of the ceramic separation membrane is at least one metal selected from the group consisting of iron, nickel, cobalt, and manganese. A method for recovering mercury from waste containing mercury. 8. The pore diameter of the separation membrane is 50μ or less, and the porosity is 3.
Claims 1 to 7 which are 0 to 80%
A method for recovering mercury from the mercury-containing waste described in any one of paragraphs. 9. The porosity of the separation membrane is 30μ or less, more preferably 15
9. The method for separating mercury from mercury-containing waste according to claim 8, wherein the porosity is less than .mu. and has a porosity of 40 to 70%. 10. Claims 1 to 9, in which the heated gas containing mercury vapor is cooled by passing through a bed filled with fillers, and the mercury vapor contained in the gas is turned into a mist, and then subjected to membrane separation. A method for recovering mercury from the mercury-containing waste described in any one of paragraphs. 11. The method for recovering mercury from mercury-containing waste according to claim 10, wherein the filler is made of a substance that does not react with mercury. 12. The method for recovering mercury from mercury-containing waste according to claim 11, wherein the filler is made of porous ceramics. 13. Mercury from the mercury-containing waste according to any one of claims 1 to 12, wherein the mercury that has condensed and grown on the filling is passed through a cooler to cool it and then recover the mercury. How to recover. 14. The method for recovering mercury from mercury-containing waste according to claim 13, wherein the mercury is cooled to a temperature below room temperature in a cooler and then recovered. 15. An apparatus for heating mercury-containing waste to evaporate and recover the mercury, characterized by comprising at least a mercury-containing waste heating section, a mercury separator equipped with a separation membrane, and a gas suction section. A device that recovers mercury from waste containing mercury. 16. The apparatus for recovering mercury from mercury-containing waste according to claim 15, wherein the separation membrane is made of ceramics. 17. Ceramics are aluminum oxide, titanium nitride,
17. The apparatus for recovering mercury from mercury-containing waste according to claim 16, which is made of silicon nitride or silicon carbide. 18. An apparatus for recovering mercury from mercury-containing waste according to claim 16 or 17, wherein the ceramic separation membrane is coated with metal. 19. The device for recovering mercury from mercury-containing waste according to claim 18, wherein the metal coating the surface of the ceramic separation membrane is iron, nickel, cobalt, or manganese. 20. The pore diameter of the separation membrane is 50μ or less, and the porosity is 3
An apparatus for recovering mercury from waste containing mercury according to any one of claims 15 to 19, wherein the mercury content is 0 to 80%. 21. The pore size of the separation membrane is 30μ or less, more preferably 1
21. The device for recovering mercury from mercury-containing waste according to claim 20, which has a particle size of 5 μm or less and a porosity of 40 to 70%. 22. An apparatus for recovering mercury from mercury-containing waste according to any one of claims 15 to 21, wherein the lower surface of the mercury separator is inclined. 23. An apparatus for recovering mercury from waste containing mercury according to any one of claims 15 to 22, which comprises a mercury separator filled with a filler. 24. The device for recovering mercury from mercury-containing waste according to claim 23, wherein the filler filled in the mercury separator is a porous ceramic filler. 25. Claim 15, wherein a gas containing mercury vapor generated by heating waste containing mercury is passed through a packed bed in a mercury separator and then subjected to membrane separation. An apparatus for recovering mercury according to any one of items 24 to 24. 26. According to any one of claims 15 to 25, a cooler is added to the downstream side of the mercury separator in order to recover the mercury separated by the mercury separator after cooling it. Equipment for recovering mercury from waste containing mercury. 27. An apparatus for recovering mercury from mercury-containing waste as set forth in claim 26, wherein a gas circulation line for recirculating gas to the heater is provided on the downstream side of the cooler.