JP2007130524A - Apparatus and method for treating cyanogen-containing waste liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for treating a cyanogen-containing waste liquid which enhances treatment efficiency of the cyanogen-containing waste liquid by a hydrothermal hydrolysis decomposition reaction, prevents the blocking of a tube member by a deposit and further can suppress the abrasion of a valve seat as much as possible, and a method for treating it. <P>SOLUTION: The apparatus for treating the cyanogen-containing waste liquid comprises a reaction tube part for carrying out hydrothermal hydrolysis decomposition of cyanogen, an introduction tube part for introducing the cyanogen-containing waste liquid into the reaction tube part and a tubular part 3 having a derivation part for deriving a cyanogen-decomposed waste liquid decomposing cyanogen by the hydrothermal hydrolysis decomposition from the reaction tube part, wherein the tubular part 3 is configured roughly in the same diameter such that a sliding member A is transferred while sliding on the inner peripheral face of the tubular part 3 to enable the removal of the deposit generated in the tubular part 3 with an insertion part for inserting the sliding member A into the tubular part 3 disposed on one end of the tubular part 3 and a recovery part for recovering the sliding member A with the deposit on the other end of the tubular part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing apparatus and a processing method for processing a cyan-containing waste liquid. More specifically, the present invention relates to a processing apparatus and a processing method for hydrolyzing a cyan-containing waste liquid under high temperature and pressure.

  For example, a plating compound waste solution, a plating jig cleaning waste solution, an etching waste solution, and the like contain a cyanide compound in the form of a metal cyanide salt or a metal cyanide complex. Since cyanide is toxic to the human body, it must be detoxified. As a typical treatment method for detoxifying a cyanide compound, there is an alkali chlorine method.

  The alkali chlorine method is a method in which a strong oxidizing agent is added to a cyan-containing waste liquid, and cyanide is oxidatively decomposed in an alkaline solution to render it harmless. For example, in order to detoxify sodium cyanide contained in a cyan-containing waste liquid, sodium hypochlorite is used as an oxidizing agent (see, for example, Non-Patent Document 1).

The oxidative decomposition reaction of sodium cyanide using sodium hypochlorite is performed by a two-stage reaction according to the following formulas (1) and (2).
(Primary decomposition reaction)
NaCN + NaClO → NaCNO + NaCl (1)
(Secondary decomposition reaction)
_{2NaCNO + 3NaClO + H 2 O →} N 2 + 3NaCl + 2NaHCO 3 ··· (2)

  The alkali chlorine method has the advantage of not requiring special equipment because an oxidant can be added at room temperature and normal pressure, but (1) the running cost is increased by using an oxidant. (2 ) It is difficult to reduce the cyan-containing waste liquid containing an iron cyano complex to a regulated value of 1 mg / L or less. (3) To reduce the cyan-containing waste liquid of high concentration (for example, 1000 mg / L) to 1 mg / L or less. However, it was not easy.

A thermal hydrolysis method has been studied for the disadvantages of the alkali chlorine method. The thermal hydrolysis method is a method of detoxifying a cyanide-containing waste liquid by hydrolyzing it under high temperature and pressure. For example, when sodium cyanide contained in a cyanide-containing waste liquid is hydrolyzed under high temperature and high pressure, it is decomposed into sodium formate and ammonia as shown in formula (3) (see, for example, Non-Patent Document 2).
NaCN + 2H ₂ O → HCOONa + NH ₃ (3)

  This thermal hydrolysis method has several advantages over the alkali chlorine method, such as (1) no chemicals for cyanide decomposition, (2) less sludge generation of by-products, ( 3) The running cost is low, (4) the decomposition rate of cyan is high, (5) it is easy to treat cyan metal complexes that are difficult to decompose, and the like. As described above, the thermal hydrolysis method is an excellent method in principle, and if the equipment cost can be suppressed, it should be a central processing technique of the high concentration cyanide-containing waste liquid processing method.

"Pollution Prevention Technology and Regulations, Water Quality", pp. 261-262, Japan Environmental Management Association for Industry, May 20, 1995 "Metal recovery from plating waste liquid" Environmental Management Vol. 30, no. 12 (1994)

  The thermal hydrolysis method for cyan-containing waste liquid is performed in a batch mode or a continuous mode. The batch method is a method in which a hydrolysis reaction is performed by introducing a cyan-containing waste liquid into a pressurized reaction vessel equipped with a heating means such as a steam jacket, and bringing this into a high temperature and high pressure state. In this method, metal, impurities, and the like may be precipitated with the thermal hydrolysis reaction of the cyan-containing waste liquid, and these precipitates are extracted from the lower valve of the pressurized reaction vessel together with the treatment liquid.

  Most of the ammonia produced by the hydrolysis reaction is present in a dissolved state in the treatment waste liquid. Therefore, the waste treatment liquid containing ammonia is aerated to release the dissolved ammonia as ammonia gas. The ammonia gas is neutralized by blowing it into an acidic liquid such as sulfuric acid. Ammonia gas that could not be absorbed by the acidic liquid is processed through a subsequent scrubber.

  By the way, the above batch system has several problems. For example, since the pressurized reaction vessel is heated via a steam jacket or the like, it takes time to heat and cool the cyan-containing waste liquid introduced into the pressurized reaction vessel, and heat recovery cannot be performed smoothly. . In addition to the expensive pressurized reaction vessel, the batch system also requires a dedicated equipment such as a large boiler for supplying a large amount of high-temperature steam to the steam jacket, and there is a problem that the equipment cost is high. Furthermore, in the batch method, generally, wait for all the reactions to finish and the temperature of the pressurized reaction vessel to drop to a certain extent, and then collect the precipitates after removing the treatment waste liquid. However, there is also a problem that processing efficiency is poor.

  On the other hand, in the continuous method, for example, a cyan-containing waste liquid is introduced into a slender vertical reaction tower having a heating means such as a steam nozzle in a high-pressure state, and the cyan-containing waste liquid is slowly moved (for example, 2 hours residence time), and a hydrolysis reaction is performed by heating high temperature steam (for example, about 170 ° C.). Precipitates such as metals produced during the reaction are once extracted from a valve at the bottom of the reaction tower into a drain pot and sent to a separation tank. Ammonia produced by the hydrolysis reaction is stripped by a gas-liquid separation device installed in the reaction tower or in the subsequent stage, and then burned and decomposed by combustion in air, or passed through an acidic liquid tank and scrubber. Sum processing is performed.

  In the above-mentioned continuous method, it is necessary to complete the thermal hydrolysis reaction while moving the cyan-containing waste liquid, so that a reaction tower having a sufficiently high height and a recovery device for continuously taking out precipitates are required. In general, in the continuous method, the cyan-containing waste liquid is preheated before introducing the cyan-containing waste liquid into the reaction tower. If the temperature control of this preheating cannot be properly performed, precipitation from the cyan-containing waste liquid is performed. Objects may adhere to and accumulate on the inner wall of the pipe, causing blockage of the pipe. For this reason, in the continuous method, it is necessary to periodically clean the inside of the pipe.

  However, the piping usually does not have a cleaning mechanism for removing such deposits. For this reason, the operator has always been required to monitor the timing of cleaning, and to disassemble and assemble the pipe each time. This is a heavy burden on the operator and the cost for cleaning is high. Furthermore, in the continuous system, the treatment waste liquid containing deposits of metal and the like has a long time to move in contact with the inner wall of the metal pipe and the inside of the valve, so that the valve seat is likely to wear out. there were.

  The present invention has been made in view of the above problems, and improves the treatment efficiency by thermal hydrolysis reaction of cyanide-containing waste liquid, prevents clogging of piping members due to precipitates, and further prevents wear of valve seats. It is an object of the present invention to provide a cyan-containing waste liquid treatment apparatus and a treatment method that can be suppressed as much as possible.

  The characteristic configuration of the cyan-containing waste liquid treatment apparatus according to the present invention includes a reaction tube portion that thermally hydrolyzes cyan, an introduction tube portion that introduces cyan-containing waste liquid into the reaction tube portion, and cyan is decomposed by a thermal hydrolysis reaction. A cyan-containing waste liquid treatment apparatus having a tubular portion having a discharge pipe portion for leading the cyan decomposition waste liquid from the reaction tube portion, wherein the sliding member moves while sliding on the inner peripheral surface of the tubular portion. The tubular portion is configured to have substantially the same diameter so that precipitates generated in the tubular portion can be removed, and the sliding member is fed into the tubular portion at one end of the tubular portion. An infeed portion is provided, and a recovery portion for recovering the sliding member together with the precipitate is provided at the other end of the tubular portion.

In the cyan-containing waste liquid treatment apparatus of this configuration, cyan is thermally hydrolyzed by heating the cyan-containing waste liquid in the reaction tube section. During this thermal hydrolysis reaction, metals and impurities contained in the cyan-containing waste liquid are deposited, and these are deposited in the tubular portion.
In the cyan-containing waste liquid treatment apparatus of this configuration, a feeding part for feeding the sliding member into the tubular part and a collecting part for collecting the sliding member from the tubular part are provided in the tubular part, and the feeding part; Since the tubular portion extending to the recovery portion is configured to have substantially the same diameter, the sliding member moves while sliding on the inner peripheral surface of the tubular portion, and precipitates such as metal and impurities are removed from the tubular portion. Can be removed. In this way, it is possible to prevent obstruction of the tubular portion due to deposit accumulation.

  In the cyan-containing waste liquid treatment apparatus of the present invention, a heat-exchanging part for heating the cyan-containing waste liquid provided in the introduction pipe part, and a temperature-falling for cooling the cyan decomposition waste liquid provided in the lead-out pipe part It is also possible to provide a heat exchange system having a heat exchange part, and a heat medium circulation means for circulating the heat medium between the temperature raising heat exchange part and the temperature lowering heat exchange part.

  In the case of the cyan-containing waste liquid treatment apparatus of this configuration, the heating medium circulating means of the heat exchange system connects the temperature raising heat exchanging section provided in the introduction pipe section and the temperature lowering heat exchange section provided in the outlet pipe section. Since the heat medium is circulated between them, the cyan-containing waste liquid and the cyan decomposition waste liquid substantially exchange heat through the heat medium. Therefore, since the cyan-containing waste liquid introduced into the reaction tube portion can be preheated by the waste heat of the cyan thermal hydrolysis treatment, the thermal efficiency is improved and the operating cost of the apparatus can be reduced.

  In the cyan-containing waste liquid treatment apparatus of the present invention, a plurality of the heat exchange systems can be provided.

  With the cyan-containing waste liquid treatment apparatus of this configuration, by providing a plurality of heat exchange systems, the temperature difference between the cyan-containing waste liquid moving through the introduction pipe section and the heat medium is reduced, and temperature management is performed more appropriately. be able to. This reduces the temperature difference between the cyan-containing waste liquid that moves in the center of the introduction pipe section and the cyan-containing waste liquid that moves in the vicinity of the inner wall of the introduction pipe section that is heated by the heat medium, and contains cyan on the inner wall of the introduction pipe section. The deposits from the waste liquid are less likely to adhere. Therefore, heat recovery can be performed while preventing the introduction pipe portion from being blocked. In addition, since the precipitates are difficult to adhere to the inner wall of the introduction pipe part, the variation in heat conduction of the introduction pipe part is reduced, and abnormal heating and local heating of the introduction pipe part can be prevented.

  In the cyan-containing waste liquid treatment apparatus of the present invention, the reaction tube portion can be configured as a double tube having an inner tube portion through which the cyan-containing waste liquid is conducted and an outer tube portion through which a heat medium is conducted.

  In the cyan-containing waste liquid treatment apparatus of this configuration, the reaction tube portion is constituted by a double tube comprising an inner tube portion and an outer tube portion, and a heat medium as a heating means is passed through the outer tube portion. Thus, the thermal hydrolysis reaction of the cyan-containing waste liquid can proceed efficiently.

  The characteristic means of the method for treating cyan-containing waste liquid according to the present invention includes a reaction tube portion for thermally hydrolyzing cyan, an introduction tube portion for introducing the cyan-containing waste liquid into the reaction tube portion, and cyan is decomposed by a thermal hydrolysis reaction. A cyan-containing waste liquid is supplied to a tubular part having a substantially the same diameter across the introduction pipe part and the lead-out pipe part. A supply step, a treatment step of heating the reaction tube portion to thermally hydrolyze cyan, a discharge step of discharging the cyan decomposition waste liquid from which cyan was decomposed by a thermal hydrolysis reaction from the tubular portion, and After the discharging step, the sliding member is fed into the tubular part and moved while sliding the inner peripheral surface of the tubular part to remove precipitates generated in the tubular part. And a process.

  In the treatment method of the cyan-containing waste liquid of this configuration, the deposits deposited on the inner peripheral surface of the tubular portion during the treatment step of thermally hydrolyzing the cyan-containing waste liquid can be removed by a removal step using a sliding member. it can. Thereby, obstruction | occlusion of the tubular part by deposit of a deposit can be prevented beforehand.

(Cyanide waste liquid treatment equipment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of a cyan-containing waste liquid treatment apparatus 100. The cyan-containing waste liquid stored in the waste liquid tank 1 is pumped from the waste liquid tank 1 to the tubular part 3 by the pump 2, and cyan thermal hydrolysis reaction is performed in the tubular part 3.

  Examples of the cyan-containing waste liquid to be processed in the cyan-containing waste liquid processing apparatus 100 and the processing method of the present invention include plating waste liquid, plating jig cleaning waste liquid, etching waste liquid, and steel waste liquid. In these cyan-containing waste liquids, cyan is present in the form of a metal cyanide salt, a metal cyanide complex, free cyanide and the like. As the waste liquid tank 1 for storing such cyan-containing waste liquid, for example, a stainless steel tank can be used.

  The pump 2 is a pump capable of pumping cyan-containing waste liquid to the tubular portion 3 at a high pressure. Examples of the pump 2 include a reciprocating pump and a gear pump.

  A water tank 4 is connected to the pump 2 in parallel with the waste liquid tank 1. Industrial water or the like is stored in the water tank 4, and this water is used for cleaning the inside of the pump 2 and generating a driving force for the sliding member A described later. However, instead of installing this water tank 4, a nozzle capable of supplying industrial water or the like at high water pressure is directly provided on the suction side of the pump 2 or directly on a charging device 12 which is an example of a feeding portion of a sliding member A described later. It is also possible to connect.

  Valves 5 and 6 are respectively provided between the waste liquid tank 1 or the water tank 4 and the pump 2 to adjust the supply amount of the cyan-containing waste liquid from the waste liquid tank 1 and the supply amount of water from the water tank 4. it can. In addition, a valve 7 is provided between the pump 2 and the tubular portion 3 for adjusting the discharge amount of the cyan-containing waste liquid or water. For these valves 5, 6, 7, for example, electric valves can be used.

  The cyan-containing waste liquid discharged by the pump 2 is supplied to the tubular portion 3 through the valve 7. 2 to 4 are detailed views showing a specific configuration of the tubular portion 3. FIG. 2 is a front view of the tubular portion 3. FIG. 3A is a side view of the tubular portion 3. FIG. 3B is an enlarged view of a main part of the front surface of the tubular portion 3. FIG. 4 is a top view of the tubular portion 3.

  The tubular portion 3 has an introduction tube portion 3a, a reaction tube portion 3b, and a lead-out tube portion 3c. Further, the lead-out pipe section 3c can be provided with a spare pipe section 3d on the rear side as required. As can be seen from FIGS. 2 and 3, the tubular portion 3 used in the present embodiment has a zigzag structure folded at a plurality of locations, and a section from one folded portion to the next folded portion is defined as one section. From the upstream side, the first section to the third section are the introduction pipe section 3a, the fourth section to the eighth section are the reaction pipe section 3b, the ninth section to the eleventh section are the outlet pipe section 3c, and the twelfth section is a reserve. A tube portion 3d is configured. The tubular portion 3 constitutes the same diameter tube portion having substantially the same inner diameter over the entire length. That is, the inner diameter of the tubular portion 3 is set to an optimum size that allows a sliding member A described later to move while maintaining a substantially contact state with the inner peripheral surface of the tubular portion 3. Therefore, substantially the same inner diameter means that the difference in inner diameter of each portion in the tubular portion 3 is small enough to allow the sliding member A to move while sliding on the inner peripheral surface of the tubular portion 3, and is not necessarily strict. Need not have the same diameter. The reason for this configuration is to reliably remove deposits from the cyan-containing waste liquid that accumulates on the inner peripheral surface of the tubular portion 3 that will be described in detail later.

  As can be seen from FIG. 2, the tubular portion 3 is directed from the upstream side (the first section side) to the downstream side (the twelfth section side) with respect to the horizontal plane (the installation surface of the cyan-containing waste liquid treatment apparatus 100). It is inclined. By providing such an inclination, the cyan-containing waste liquid flowing inside the tubular portion 3 can move smoothly from the upstream side toward the downstream side, and smooth continuous processing becomes possible. Further, the deposit removed from the inner peripheral surface of the tubular portion 3 by the sliding member A is also smoothly discharged from the discharge port 21 on the downstream side. The inclination angle can be arbitrarily set, for example, 1 to 50 degrees with respect to the horizontal plane. Increasing the inclination angle facilitates movement of the cyan-containing waste liquid and precipitates, but may be set as appropriate in consideration of the installation space such as the installation location and the ceiling height.

  Next, each pipe part which comprises the tubular part 3 is demonstrated concretely. The introduction pipe part 3a has a function of warming the cyan-containing waste liquid. For this reason, the heat-up part 8 for temperature rising is provided in the introduction pipe part 3a. Further, the outlet pipe portion 3c has a function of cooling the processing waste liquid after the reaction. For this reason, the temperature-decreasing heat exchanging part 9 is provided in the outlet pipe part 3c.

  Here, as shown in FIG. 1, the temperature raising heat exchanging portion 8 and the temperature lowering heat exchanging portion 9 are connected to each other, and a common heat medium (for example, Silicone oil or the like) circulates inside the heat exchanger 8 for raising temperature and the heat exchanger 9 for lowering temperature. Thus, the heat exchanger 8 for raising temperature, the heat exchanger 9 for lowering temperature, and the circulation pump 10 constitute a heat exchange system, and this heat exchange system is substantially a cyan-containing waste liquid via a heat medium. And heat exchange with cyanide waste liquid. Thereby, since the preheating of the cyan-containing waste liquid introduced into the reaction tube portion 3b can be performed by the waste heat of the thermal hydrolysis treatment of cyan, the thermal efficiency is improved and the operating cost of the apparatus can be reduced.

It is also possible to provide a plurality of the heat exchange systems. The number of heat exchange systems is not particularly limited. Incidentally, in the embodiment shown in FIG. 1, three heat exchange systems are provided. The corresponding heat exchanging parts (heating heat exchanging parts 8a, 8b, 8c and cooling heat exchanging parts 9a, 9b, 9c) are connected to each other, and a common heat medium is connected to each circulation pump 10 (circulation pump 10a). 10b, 10c). Table 1 below shows an example of the inlet temperature and the outlet temperature of the heat medium circulating through the temperature raising heat exchange unit 8 and the temperature lowering heat exchange unit 9 of each heat exchange system at this time.

  By providing a plurality of heat exchange systems in this way, the heating temperature and cooling temperature of the cyan-containing waste liquid can be finely controlled along the tubular portion 3. Specifically, the cyan-containing waste liquid that moves through the central portion of the introduction pipe section 3a by reducing the temperature difference between the cyan-containing waste liquid that moves through the introduction pipe section 3a and the heat medium and performing temperature management more appropriately. And the cyan-containing waste liquid moving in the vicinity of the inner wall of the introduction pipe portion 3a heated by the heat medium are reduced, and deposits from the cyan-containing waste liquid are less likely to adhere to the inner wall of the introduction pipe portion 3a. In this way, heat recovery can be performed while preventing the introduction pipe portion 3a from being blocked. In addition, since the precipitate is less likely to adhere to the inner wall of the introduction pipe portion 3a, variation in heat conduction of the introduction pipe portion 3a is reduced, and abnormal heating and local heating of the introduction pipe portion 3a can be prevented.

  In the heat exchange system of FIG. 1, a pair of corresponding heat-up units 8a, 8b, 8c for temperature increase and heat-exchange units 9a, 9b, 9c for temperature decrease are connected to each other, and the circulation pumps 10a, 10b, Although the heat medium is circulated by 10c, it is also possible to connect all the heat exchange units in series and circulate the common heat medium by the circulation pump 10 as shown in FIG. With this configuration, the number of circulation pumps 10 can be reduced. Thereby, the installation cost of the cyan containing waste liquid processing apparatus 100 can be held down.

The reaction tube part 3b has a function of advancing the chemical reaction of the cyan-containing waste liquid. This chemical reaction is a thermal hydrolysis reaction that decomposes the cyan-containing waste liquid into formic acid (formate) and ammonia, and the reaction itself is the same as in the formula (3) described in the prior art. The thermal hydrolysis reaction is performed under high temperature and pressure. Specifically, the inside of the tubular portion 3 including the reaction tube portion 3b is maintained at about 10 to 15 atm during the thermal hydrolysis reaction. Moreover, the reaction tube part 3b is comprised so that temperature rising is possible by a suitable heating means. In the embodiment shown in FIGS. 1 and 2, the reaction tube portion 3b is composed of a double pipe, conducts the cyan-containing waste liquid in the inner tube portion 3b _1, the heating medium X as heating means in the outer tube portion 3b ₂ Is to be conducted. The heat medium X is heated by a heater 32 in a separately provided heat medium container 31 and introduced into the heat medium inlet 13a of the outer tube portion 3b ₂ by the heat medium circulation pump 33, and the heat of the outer tube portion 3b ₂ is heated. It is discharged from the medium discharge port 13 b and returned to the heat medium container 31. At this time, the temperature of the heat medium X at the heat medium inlet 13a is about 230 ° C., and the temperature at the heat medium outlet 13b is about 180 ° C. In order to achieve the above temperature, the heat medium X is a medium having good high-temperature stability such as chemically synthesized oil or silicone oil.

  Like this embodiment, the reaction tube part 3b which employ | adopted the double tube can advance the thermal hydrolysis reaction of a cyan containing waste liquid efficiently, although it is a comparatively simple structure. At this time, the heat medium X passing through the double pipe can also be circulated.

  As the heating means of the reaction tube portion 3b, another configuration different from that of the heat medium X can be adopted. For example, it is possible to apply a heater trace on the outer surface of the reaction tube portion 3b and adjust the temperature of the reaction tube portion 3b so that the optimum reaction temperature can be maintained by a control method such as feedback control or PID control. The reaction tube portion 3b in this case does not need to use a double tube as described above as long as it has a certain heat resistance.

  When the cyan-containing waste liquid is hydrolyzed as described above, cyan is decomposed into formic acid (formate) and ammonia. At this time, various precipitates are generated as by-products. In particular, when the concentration of the cyan-containing waste liquid before thermal hydrolysis is high, metal ions contained in the waste liquid are deposited as metal oxides or simple metals.

More specifically, in a cyanide-containing waste liquid such as a plating waste liquid, a plating jig cleaning waste liquid, an etching waste liquid, a steel waste liquid, or a treatment liquid thereof, triiron tetroxide (Fe ₃ O ₄ ), cuprous oxide ( Precipitates are generated as metal oxides such as Cu ₂ O) and nickel oxide (NiO) or as simple metals such as gold (Ag) and platinum (Pt). Such precipitates are generated as nucleation and nucleation progress while the waste liquid is moving through the tubular portion 3 and float in the waste liquid and exist in a slurry state, or the inner peripheral surface of the tubular portion 3. It is thought that nuclei adhere to and grow on the layers and are sequentially deposited. Among these, the deposit deposited on the inner peripheral surface of the latter tubular portion 3 is problematic because it may block the tubular portion 3. As deposition of the deposit proceeds, the flow path of the tubular portion 3 is narrowed, and the flow resistance of the cyan-containing waste liquid increases. Finally, the tubular portion 3 is completely blocked by the deposit. Therefore, in the present invention, deposits deposited on the inner peripheral surface of the tubular portion 3 are removed by the method described below.

(Cyanide-containing waste liquid treatment method)
In the cyan-containing waste liquid treatment method of the present invention, the cyan-containing waste liquid is supplied to the tubular portion 3 (supplying step), where the waste liquid is thermally hydrolyzed (processing step) and then deposited on the inner peripheral surface of the tubular portion 3. The deposit is removed. In this cyan-containing waste liquid treatment method, a sliding member that slides on the inner peripheral surface of the tubular portion 3 from the upstream side to the downstream side of the tubular portion 3 to remove precipitates generated on the inner peripheral surface of the tube. A is used. Some examples of the sliding member A are shown in FIGS. The sliding member A shown in FIG. 5 is a so-called “pig”. The pig is a shell-shaped member made of any material such as resin, rubber, metal, etc., and a spike as shown in FIG. 5 (b) or a wire as shown in FIG. 5 (c) is formed on the surface of the pig. Some have improved the removal effect of precipitates. Needless to say, it is possible to use a member other than the pig as the sliding member A.

  FIGS. 6 to 10 are schematic views showing how the precipitates in the tubular portion 3 are removed by the sliding member A over time. FIG. 6 shows a state in which the cyan-containing waste liquid is pumped from the waste liquid tank 1 to the tubular portion 3 by the pump 2, FIG. 7 shows a state in which the sliding member A is set in the charging device 12, and FIG. FIG. 9 shows a state in which the sliding member A is driven by pumping water to the rear of the charging device 12 by the pump 2, and FIG. 9 shows that the sliding member A is deposited on the inner wall of the tubular portion 3 (particularly, the reaction tube portion 3b). 10 is discharged from the discharge port 21 provided on the downstream side of the tubular portion 3 together with the precipitate removed by the sliding member A and the waste liquid after treatment, and is returned to the recovery tank 14. It is in a state of being collected.

  The sliding member A is introduced into the pipe by the introduction device 12 from the introduction port 11 provided at the upstream end of the tubular portion 3 (sliding member introduction step). The charging device 12 is connected to the drain side of the pump 2 through a valve 13 (FIG. 6). After all the valves 5, 6, 7, and 13 are closed and the pumping of the cyan-containing waste liquid is stopped, the sliding member A is set in the charging device 12 (FIG. 7). Next, the valves 6 and 13 are opened, the valves 5 and 7 are kept closed, and the partition valves 15 and 16 provided near the upstream end and the downstream end of the tubular portion 3 are opened, When the pump 2 is operated, high-pressure water is jetted from the water tank 4 to the rear part of the sliding member A by the pump 2. Then, the sliding member A advances the tubular portion 3 from the upstream side to the downstream side by the force of water pressure (FIG. 8). At this time, the sliding member A proceeds while scraping the deposits deposited on the inner peripheral surface of the tube (in particular, the inner wall of the reaction tube portion 3b) (removal step; FIG. 9). The precipitate scraped off by the sliding member A is discharged from a discharge port 21 provided on the downstream side of the tubular portion 3 together with the waste liquid after treatment, water for driving the sliding member A, and the sliding member A. Then, it is recovered in a recovery tank 14 for recovering the processing waste liquid (discharge step; FIG. 10). At this time, if the sliding member A is received by the mesh trap 18 provided in the collection tank 14, only the sliding member A can be easily taken out. Further, during the discharging process, the sliding member A is dropped into, for example, a sliding member collection container 50 (see FIG. 4) provided separately from the collection tank 14, and the sliding member A and the processing waste liquid are separated. It is also possible to recover in a completely separated state.

  Thus, when deposits are deposited to some extent on the inner peripheral surface of the tube of the tubular portion 3, they are removed and discharged by the sliding member A to prevent the tubular portion 3 from being blocked by deposits. Can do. And if such a removal process is performed regularly, while being able to prevent the abnormal heating, the local heating, etc. resulting from the dispersion | variation in the heat conduction by the deposit adhering to the inner wall of the tubular part 3, a tubular part, the valve seat of a valve | bulb The wear of the pump and the like can be reduced, and the life of the cyan-containing waste liquid treatment apparatus 100 can be extended.

  Of course, the removal step may be performed not at regular intervals but at any time as long as it is within a period in which the tubular portion 3 is not blocked. The removal of the precipitate performed at such an arbitrary time is particularly effective when the noble metal useful for the precipitate is contained. That is, taking into account the transaction status and market price of precious metals with customers, collecting precipitates at a timing that is advantageous to the self, and extracting precious metals contained therein can increase profits.

  In the above embodiment, water is used to propel the sliding member A. However, a gas such as compressed air can also be used. If gas is used as the fluid, the waste liquid after the treatment collected together with the sliding member A and the precipitate is not diluted with water, which is advantageous in the subsequent treatment (for example, heat treatment or drying treatment). There is.

  During normal operation of the cyan-containing waste liquid treatment apparatus 100, the partition valve 16 for discharging the sliding member A is closed, and the discharge valve 17 provided on the branch pipe 40 branched from the tubular portion 3 is opened. The treated waste liquid can also be collected in the collection tank 14. Further, in place of the discharge valve 17, it is also possible to adjust the flow rate of the waste liquid by providing one or more pumps (not shown) in the branch pipe 40 and appropriately adjusting the discharge amount of the pump. Thus, the reason why the pump can be used as an alternative to the discharge valve 17 is that the same effect as adjusting the flow rate by the valve 17 can be obtained by utilizing the operating resistance of the pump. In addition, if the pump is used as an alternative to the valve 17, regenerative energy can be taken out from the pump in the form of electric power, etc., so that the energy efficiency of the cyan-containing waste liquid treatment apparatus 100 as a whole is improved and effective for cost reduction. .

(Cyanide waste liquid treatment system)
The treatment waste liquid after removing the precipitate contains ammonia and formic acid (formate), which are decomposable organisms, although harmful cyanide is decomposed. For this reason, in order to further detoxify the treatment waste liquid, a conventionally known treatment waste liquid can be post-treated. This post-treatment is, for ammonia, a combustion treatment or aeration treatment as described in the background art, and formic acid (formate) is a volume reduction treatment using a dry spray device. And the water generated by these post-treatments can be reused as cleaning water for the plating jig or stored in the water tank 4 of the cyan-containing waste liquid treatment apparatus 100. As described above, the cyan-containing waste liquid treatment apparatus 100 of the present invention can be a semi-closed system that hardly discharges treated water to the outside, and takes into account recent environmental problems.

  Hereinafter, some examples of treating cyan-containing waste liquid using the cyan-containing waste liquid treatment apparatus 100 will be described. The tubular portion 3 of the cyan-containing waste liquid treatment apparatus 100 of the present embodiment is a metal tube having an inner diameter of about 40 mm and a total length of 120 m. The size of each part constituting the tubular part 3 is 30 m for the introduction pipe part 3 a, 50 m for the reaction pipe part 3 b, 30 m for the outlet pipe part 3 c, and 10 m for the spare pipe part 3 d. The tubular portion 3 is inclined about 2 degrees with respect to the horizontal plane.

In the test, two types of waste liquids containing cyan (waste liquid A and waste liquid B) were used, and a thermal hydrolysis reaction was performed using the cyan-containing waste liquid treatment apparatus 100. The deposit deposited on the inner peripheral surface of the tubular portion 3 was removed using a pig having a diameter of 40 mm. A water pressure of 4.5 kg / cm ² and a water amount of 20 L / min were applied to the pig, and the inside of the tubular portion 3 was propelled. At this time, the pig passed through the tubular portion 3 in about 4 to 15 minutes and was collected in the collection tank 14 together with the treatment liquid and the removed precipitates. The solid matter was taken out from the collection tank 14, dried at 105 ° C. for 2 hours, and weighed.

The components of each waste liquid used in the test are as follows.
Waste liquid A Fe: 90 mg / L
CN: 50 mg / L
Waste B Au: 1500mg / L
Cu: 4000 mg / L
CN: 5000 mg / L

Each test condition of an Example is as follows.

The test results of the examples are as follows.

  As described above, according to the cyan-containing waste liquid treatment method of the present invention, it is possible to decompose about 100% of cyan depending on conditions. In addition, since a considerable amount of precipitates can be recovered by pigs, as described above, if noble metals and base metals are taken out at any time by refining the precipitates, profits can be increased.

Schematic diagram showing the configuration of a cyan-containing waste liquid treatment system Front view of tubular section (A) Side view of tubular part, and (b) Main part enlarged view of front of tubular part Top view of tubular section Illustration showing various pigs Schematic diagram showing over time how precipitates in the tubular portion are removed by the sliding member Schematic diagram showing over time how precipitates in the tubular portion are removed by the sliding member Schematic diagram showing over time how precipitates in the tubular portion are removed by the sliding member Schematic diagram showing over time how precipitates in the tubular portion are removed by the sliding member Schematic diagram showing over time how precipitates in the tubular portion are removed by the sliding member Schematic diagram showing one embodiment of a cyan-containing waste liquid treatment apparatus in which heat exchange units are connected in series

Explanation of symbols

2 Pump 3 Tubular part 8 Heat exchange part for temperature increase 9 Heat exchange part for temperature drop 11 Inlet 14 Collection tank 21 Discharge port

Claims (5)

A reaction tube portion for thermally hydrolyzing cyan, an introduction tube portion for introducing cyan-containing waste liquid into the reaction tube portion, and a lead-out tube for deriving from the reaction tube portion a cyan decomposition waste liquid obtained by decomposing cyan by a thermal hydrolysis reaction A cyan-containing waste liquid treatment apparatus comprising a tubular portion having a portion,
The tubular portion is configured to have substantially the same diameter so that the sliding member moves while sliding on the inner peripheral surface of the tubular portion, and precipitates generated in the tubular portion can be removed.
A collecting portion for providing a feeding portion for feeding the sliding member into the tubular portion at one end of the tubular portion, and collecting the sliding member together with the precipitate at the other end of the tubular portion. A cyan-containing waste liquid treatment apparatus.   A temperature raising heat exchange part for heating the cyan-containing waste liquid provided in the introduction pipe part, a temperature reduction heat exchange part for cooling the cyan decomposition waste liquid provided in the outlet pipe part, and the temperature rise heat exchange The cyan-containing waste liquid treatment apparatus according to claim 1, further comprising a heat exchange system having a heat medium circulating means for circulating a heat medium between the heat exchanger and the temperature lowering heat exchange part.   The cyan-containing waste liquid treatment apparatus according to claim 2, wherein a plurality of the heat exchange systems are provided.   The said reaction tube part is comprised as a double tube | pipe which has an inner tube part which conducts the said cyan-containing waste liquid, and an outer tube part which conducts a heat medium. Cyan-containing waste liquid treatment equipment. A reaction tube portion for thermally hydrolyzing cyan, an introduction tube portion for introducing cyan-containing waste liquid into the reaction tube portion, and a lead-out tube for deriving from the reaction tube portion a cyan decomposition waste liquid obtained by decomposing cyan by a thermal hydrolysis reaction A supply step of supplying a cyan-containing waste liquid to a tubular portion configured to have substantially the same diameter across the introduction tube portion and the lead-out tube portion;
A treatment step of raising the temperature of the reaction tube and subjecting cyan to thermal hydrolysis;
A discharge step of discharging cyan decomposition waste liquid, in which cyanide is decomposed by a thermal hydrolysis reaction, from the tubular portion;
After the discharging step, the sliding member is fed into the tubular portion and moved while sliding the inner peripheral surface of the tubular portion to remove precipitates generated in the tubular portion. A method for treating a cyan-containing waste liquid comprising a removing step.

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