JP6199154B2 - Radioactive substance removal equipment - Google Patents

Description

The present invention relates to a dividing removed by devices of radioactive material to remove radioactive substances such as cesium from soil.

  Conventionally, as a method for removing pollutants from the soil, a step of stirring and mixing the contaminated soil and the cleaning liquid, a step of classifying the coarse particles from the mixture of the contaminated soil and the cleaning liquid, and further cleaning and classifying the coarse particles with the cleaning liquid The process of separating contaminants together with the cleaning liquid using a device, the process of precipitating the remaining fine particles obtained by classifying coarse particles in a sedimentation device, the process of solid-liquid separation, the process of recovering the cleaning liquid and separating or treating or disposing of the contaminants Contaminated soil cleaning methods (for example, Patent Document 1), soil mixed with non-volatile contaminants is mixed with water to clean the soil, and the soil particles obtained are classified to contaminate the soil. Separating coarse particles with few substances, solid-liquid separation of muddy water containing a high concentration of pollutants, separating soil fine particles containing a large amount of pollutants, and mixing a mixture of soil and water contaminated with non-volatile pollutants , Washing tank A method for removing non-volatile pollutants in soil that is peptized by aeration, mechanical agitation, and / or pump circulation (for example, Patent Document 2), and contaminated soil is thawed while being supplied with a cleaning agent and return water. The soil is sorted while receiving return water and makeup water, and a part of the sorted soil is reused as washing soil, and the rest of the soil is supplied with return water. From the contaminated soil cleaning and purification system (for example, Patent Document 3) in which the soil is classified into washed soil and soil and pollutants, and the soil is agglomerated and pollutants are classified. The excavation step for excavating the contaminated soil, the contaminated soil obtained from the excavation step was separated from the soil while polishing the contaminated soil with water by means of a conveying means equipped with an airtight container having a stirring function. A transporting process for transporting to a class plant, a classifying process for sorting fine-grained soil from a contaminated soil transported by the transporting process by a classifying plant for wet classification, and a soil from which fine-grained soil is sorted in the classifying process A method for treating contaminated soil (for example, Patent Document 4), which includes a reuse step of reusing as a construction material, has been proposed.

  In Patent Document 1, the contaminated soil and the cleaning liquid are stirred and mixed, and the coarse particles are classified from the mixture. The coarse particles are further washed with the cleaning liquid to separate the contaminants together with the cleaning liquid. In the case of a radioactive substance such as the above, there is a problem that contaminants cannot be effectively removed only by stirring and mixing with a cleaning liquid.

  Further, in Patent Document 2, a mixture of soil and water mixed with non-volatile pollutants is peptized by aeration, mechanical stirring and / or pump circulation in a washing tank, but the pollutants are radioactive substances such as cesium. In this case, there is a problem that the pollutants cannot be effectively removed simply by aeration and mechanical stirring of a mixture of soil and water.

  In Patent Document 3, a cleaning agent and return water are supplied to the contaminated soil for selective cleaning. However, when the contaminant is a radioactive substance such as cesium, the contaminant is effective only by supplying the cleaning agent and the return water. There is a problem that it cannot be removed.

  Further, in Patent Document 4, it is possible to polish the fine-grained soil containing a lot of heavy metals fixed to the coarse grains in the contaminated soil by effectively using the transport time, but the pollutant is a radioactive substance such as cesium. In this case, there is a problem that contaminants cannot be effectively removed only by polishing with water.

JP 2001-149913 A JP 2004-261895 A JP 2008-43879 A JP 2007-175585 A

  Therefore, in view of the above-described problems, an object of the present invention is to provide a radioactive substance removal method and a removal apparatus that can efficiently remove radioactive substances in soil.

The invention according to claim 1 is an apparatus for removing a radioactive substance that separates contaminated soil containing a radioactive substance into a radioactive substance and treated soil, the removing apparatus that removes the contaminated soil, and cleaning water and surface activity on the removed contaminated soil. A stirring device that stirs while supplying compressed air to the mixture in which the agent is mixed, and a classification device that classifies the contaminated soil mixture after stirring into coarse and fine particles , and the stirring device is based on the tip side. A screw conveyor main body obliquely arranged above the end side, the screw conveyor main body being provided in the body main body and the body main body, and rotating to drive the mixture in the body main body from the base end side A screw that is pumped to the side, an inlet for the mixture provided on the base end side of the trunk body, an outlet for the mixture provided on the distal end side of the trunk body, and the mixture in the trunk body Compression An air nozzle for supplying a gas, characterized in that it comprises a vibrating means for vibrating said mixture in said cylinder body.

The invention according to claim 2 is characterized in that the vibration means is provided on an outer periphery of the trunk body .

According to a third aspect of the present invention , there is provided a liquid supply port for supplying water into the trunk body .

According to a fourth aspect of the present invention, the base end side of the trunk body is slidably connected to a base, and angle adjusting means for adjusting an inclination angle of the screw conveyor body is provided .

The invention according to claim 5 is characterized in that the angle adjusting means is expansion / contraction driving means having end portions pivoted to the trunk body and the base .

According to the configuration of claim 1, cesium is separated from the coarse particles by the separation action by the surfactant and the separation action by stirring while supplying compressed air, and the fine particles to which cesium is attached are separated. The coarse particles can be separated, and the separated cesium moves to the fine particles. Thereafter, the coarse particles and fine particles are separated to obtain the coarse particles having a low cesium concentration.

Moreover, according to the structure of Claim 1 , the separation effect | action of a cesium improves by giving a vibration further to the stirring which supplies compressed air.

  Moreover, according to the structure of Claim 1, since a mixture is conveyed with stirring with a screw, the continuous process of a mixture is attained.

  Moreover, according to the structure of Claim 2, a vibration in the outer periphery of a trunk | drum main body can give a vibration to the mixture in a trunk | drum main body.

Moreover, according to the structure of Claim 3 , water can be supplied to the mixture in a trunk | drum main body.

Moreover, according to the structure of Claim 4 and 5 , since the angle | corner of a trunk | drum main body can be adjusted, when a rotational speed is constant, if an angle becomes large, the stirring force added to a mixture with a screw can be enlarged. .

BRIEF DESCRIPTION OF THE DRAWINGS It is whole explanatory drawing of the removal apparatus which shows Example 1 of this invention. It is a flowchart figure of a removal method same as the above. It is explanatory drawing of the removal method same as the above. It is sectional drawing of the stirring processing apparatus used for the preliminary experiment same as the above. It is a flowchart figure of a preliminary experiment same as the above. It is a flowchart figure of this experiment same as the above. It is a band graph of the contaminated soil A of this experiment as above. It is a strip graph of the contaminated soil B of this experiment as above. It is a graph which shows the change of the amount of cesium of the contaminated soil A of this experiment same as the above. It is a graph which shows the change of the amount of cesium of the contaminated soil A of this experiment same as the above. It is explanatory drawing explaining the effect of the scrub by stirring same as the above. It is explanatory drawing explaining the effect of surface active material same as the above. It is a front view of an agitation processing apparatus same as the above .

  Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below do not limit the contents of the present invention described in the claims. In addition, all of the configurations described below are not necessarily essential requirements of the present invention. In each embodiment, by adopting a radioactive substance removal method and removal apparatus different from the conventional ones, an unprecedented radioactive substance removal method and removal apparatus are obtained, and the radioactive substance removal method and removal apparatus are respectively described. To do.

  Hereinafter, a method and apparatus for removing a radioactive substance according to the present invention will be described with reference to the accompanying drawings. FIGS. 1-12 shows Example 1 of this invention, and as shown in the figure, in the decontamination operation | work of the contaminated soil containing a radioactive substance, first, removal process S1 which removes the contaminated soil 1 which is a pollutant is performed. Do. This removal step S1 is performed by stripping topsoil, rivers, sea dredging, etc., and removing pollutants from slopes, gutters, roof outer walls, agricultural land, etc. Sludge is also included. In addition, in FIG. 1, the dredger 2 is illustrated as a removal apparatus which removes the contaminated soil 1. FIG. Moreover, a backhoe etc. are illustrated as an apparatus for removing and removing topsoil.

  Hereinafter, the process of the contaminated soil 1 containing radioactive substances, such as cesium, is demonstrated.

  When the contaminated soil 1 removed in the removal step S1 has a relatively high water content obtained by dredging or the like, it is transferred to the mud tank 4 as it is, and when the water content ratio is relatively low, it is transferred to the fluidizing tank 3. It is transferred, fluidized by adding water, and then transferred to the mud tank 4.

  In the pretreatment step S2 performed before the next agitation step S3, water and a surfactant are added to the contaminated soil 1 to adjust the water content ratio to 100 to 500%, for example, about 300%, and for a predetermined period of 2 to 12 hours. , Preferably soaked for more than 12 hours. During the soaking period, the water content ratio is maintained in a substantially constant range (100 to 500%). The water content ratio is a value obtained by dividing the weight of moisture by the weight of solid content and multiplying by 100, and the unit is%.

  In this way, the contaminated soil 1, water and a surfactant are mixed to form a contaminated soil mixture having a predetermined water content ratio, soaked in the surfactant, and then the process proceeds to the stirring step S3. The agitation processing device 5 used in the agitation step S3 performs the agitation process by agitating while supplying compressed air to the contaminated soil mixture. At this time, vibration may be applied to the contaminated soil mixture.

  In addition, the water content ratio of the mixture in the pretreatment step S2 is lower than the water content ratio of 500 to 1500% at the time of the agitation treatment, and water is added in the agitation treatment device 5, whereby the water content ratio in the agitation step S3 is a predetermined value 500 It may be ˜1500%.

  As described above, in the stirring step S3, cesium is separated from the coarse particles of the contaminated soil by the electrical separation action by the surfactant and the mechanical separation action by the stirring and blowing of compressed air, or the cesium adhered to the coarse grains. The separated fine particles are separated, and the separated fine particles containing cesium or cesium are transferred to fine particles such as small silty / clayy particles and sand (fine sand) with a particle size of less than a predetermined size. be able to. In other words, cesium or fine particles adhering to the cesium adhering to the coarse particles are separated from the foreign particles, gravel, and coarse particles such as sand (coarse sand) having a particle size smaller than a predetermined particle size, and the separated particles are separated. By moving and agglomerating cesium or fine particles to which cesium is adhered to fine particles, the volume of cesium in the coarse particles can be reduced. Note that the fine particles have smaller particles than the coarse particles.

  Next, in the classification step S4 for classifying the coarse and fine particles of the contaminated soil mixture, the classification device 6 separates foreign matters, gravel, sand and the like from the contaminated soil mixture, and the remaining fine particles Minutes and moisture are transferred to the agitation tank 7.

  Examples of the classification device 6 include a vibration sieve that classifies by applying vibration to the sieve, a cyclone, and the like.

  The coarse particle 1A such as gravel or coarse sand obtained by removing foreign matters from the coarse particle is reused as a civil engineering material. On the other hand, in the agitation tank 7, a flocculant is added to the fine particles and moisture and stirred to precipitate the fine particles, and cesium is fixed to the fine particles. The precipitated fine water is recovered and the supernatant water can be discharged or reused. A vertical rotating shaft 8 is provided in the stirring tank 7, a plurality of stirring blades 9 are provided on the rotating shaft 8, and the rotating shaft 8 is driven to rotate, whereby the plurality of stirring blades 9 are separated into fine particles and Stir moisture.

  By collecting the supernatant water in this manner, the fine granule having a reduced water content is dehydrated by the dehydrating means 10 to obtain dewatered residual water 11 and dehydrated soil 12 as treated soil. The dewatered sewage 11 can be discharged or reused. On the other hand, the dehydrated soil 12 contains cesium in the contaminated soil in a concentrated state, and the volume of the soil is reduced.

  As the dehydrating means 10, a filter press 13 as a press processing means can be used. As shown in the schematic diagram of FIG. 1, the filter press 13 includes a plurality of filter plates 23 each having a plurality of filter cloths arranged between a fixed frame 21 and a fastening plate 22, and these filter plates 23. A filter chamber is formed between them. Then, there is a type in which the clamping plate 22 is moved by a hydraulic cylinder 24 to press the mud in the filter chamber for filtration and dewatering.

  Further, as the surfactant, any of a cationic surfactant, an anionic surfactant, an amphoteric surfactant or a nonionic surfactant may be used, and in particular, a cationic surfactant. Agents are preferred. Moreover, you may mix and use 2 or more types of surfactant except mixing a cationic surfactant and an anionic surfactant. Examples of the cationic surfactant include a quaternary ammonium salt type and an amine salt type, and a quaternary ammonium salt type is particularly preferable. Furthermore, among quaternary ammonium salt types, benzyltrimethylammonium chloride is particularly suitable.

  Examples of the anionic surfactant include a sulfonate type, a sulfate ester type, a phosphate ester salt type, and a carboxylate type.

  Examples of the amphoteric surfactant include betaine type, imidazoline type and amino acid type.

  Examples of the nonionic surfactant include ether type, ester type, fatty acid ester type, alkylamine type and higher alcohol type.

  The surfactant may be diluted with water as necessary. The concentration of the surfactant is preferably 0.1 to 15% by mass, for example.

  Further, the flocculant is an inorganic flocculant using volcanic ash, which is a natural material, as its raw material. In particular, as the volcanic ash, it is preferable to use “Shirasu” which is a volcanic eruption covering the southern Kyushu. Then, by burning the shirasu particles as the main raw material in a baking furnace, a much larger amount of positive charge is charged compared to a general flocculant.

  When the aggregating agent is put in a solution containing colloidal particles, the negative charge of the colloidal particles and the positive charge of the aggregating agent are ionically bonded, and the colloidal particles are condensed. Since the aggregating agent is charged with a larger number of positive charges than a general aggregating agent, it has an ionic bond with a plurality of negative charges in the colloidal particles.

  Moreover, since the colloidal particles which condense also increase, a big floc is formed. Furthermore, since there are still many positive charges that do not contribute to ionic bonding, the negative charges charged in the colloidal particles are attracted to the aggregating agent, causing a bias in the charge, and the opposite side is charged with a positive charge. An electrical dipole is formed. Since the colloidal particles that have become electric dipoles and other colloidal particles perform ion-dipole bonding without interposing an aggregating agent, the floc is further increased.

  As described above, the aggregating agent exhibits a high aggregating effect with a small addition amount compared to a general aggregating agent, and does not need to be used in combination with a polymer aggregating agent. it can. Even neutral colloidal particles that are not negatively charged can be condensed because they form an electric dipole due to the strong positive charge of the aggregating agent.

  In addition, since the raw material of the flocculant is a natural material, there is no influence on the human body or the natural world. Moreover, the combined use with the polymer flocculant like the conventional flocculant becomes unnecessary. Furthermore, since it boasts an overwhelming agglomeration speed (10 to 20 seconds), the scale of facilities such as reaction stirrers and sedimentation tanks can be reduced to about 1/5 or less of the conventional scale. Moreover, since the viscosity of the aggregated sludge is extremely low, the dehydration process is easy.

  The flocculant has a wide application pH range, and in many cases, it can be applied even at pH = 5 to 10. A flocculant that can be applied to wastewater with pH ≦ 4 (strongly acidic) or pH ≧ 11 (strongly alkaline) can be prepared by order. Moreover, since the coagulant consumes little alkalinity with the coagulation reaction, it is not necessary to add an alkali assistant. On the other hand, conventional flocculants such as sulfuric acid bands and PACs are acidified as the reaction progresses, so that it is necessary to add an alkali aid in addition to the polymer flocculant.

Preliminary Experiments FIGS. 4 and 5 are drawings relating to a preliminary experiment. As shown in FIG. 4, a pot-type mixer 25 is used for the agitation processing apparatus 5, and this mixer 25 has a rotating drum whose rotation center is inclined. 26 and has an opening 27 at the top of the rotating drum 26. In addition, the air dose at the time of collecting the contaminated soil used in the preliminary experiment was 1.5 μSv / h.

  Sample 28 used in Example 2 was a contaminated soil mixture in which 2 kg of contaminated soil containing cesium, 20 liters of water, and 0.5% by weight of a surfactant were mixed. The sample 28 is put into the rotating cylinder 26, the rotating cylinder 26 is rotated, the tip of the compression nozzle 29 and the tip of the vibrating bar 30 are inserted into the sample 28, and the compressed air is introduced into the sample 28 from the tip of the compression nozzle 29. And the vibration rod 30 is driven to vibrate. The tip of the vibrating bar 30 is held so as not to contact the inner surface of the rotary drum 26. In this manner, with the supply of compressed air and vibration to the sample 28, the stirring treatment was performed for 2 hours.

  As described above, in Experimental Example 2, the stirring process was performed under the conditions of “stirring” by rotation of the rotating drum 26, mixing of “surfactant”, supplying “compressed air”, and applying “vibration” by the vibrating rod 30. .

  Further, as shown in Table 1 above, in Experimental Example 7, the stirring treatment was performed without applying the “vibration” of Experimental Example 2. In Experimental Example 3, only “stirring”, in Experimental Example 4, “stirring”, supply of “compressed air”, in Experimental Example 5, “stirring”, mixing of “surfactant”, in Experimental Example 6, “stirring” And “vibration” conditions.

  In addition, Experimental Example 1 is an original sample composed of 2 kg of contaminated soil containing cesium and 20 liters of water, and is not subjected to stirring treatment. The surfactant used in this preliminary experiment and in this experiment described later uses a quaternary ammonium salt type as the cationic surfactant, and as described above, the flocculant contains shirasu ( Volcanic ash) was applied, and a product manufactured by a special firing technique using this property was used.

  The sample was classified after stirring treatment except for Experimental Example 1. In Experimental Example 1, classification was performed as it was. In this case, the particle size was classified into 2 mm or more, 75 μm to 2 mm, and less than 75 μm with a sieve. In addition, when the particle diameter is 2 mm or more, the sieve mesh does not pass 2 mm (pebbles), and the particle size of 75 μm to 2 mm is when the sieve mesh passes 2 mm and the sieve mesh is 75 μm. Those that do not pass (sand) and less than 75 μm pass through those having a sieve mesh of 75 μm. Moreover, after classifying to less than 75 μm, adding a flocculant to the classified sample and allowing to stand, the solid content is agglomerated and precipitated, and the solid content (silt clay) mainly composed of silt and clay is removed by removing the water. ).

  Table 2 above shows the results of measuring the amount of cesium of classified gravel, sand, and silt clay. Here, the Cs ratio is a value obtained by ordering the measured amount of cesium by the total amount of cesium. Gravel having a particle size of 2 mm or more and sand having a particle size of 75 μm to 2 mm are reduced in the amount of cesium by stirring treatment. The amount of cesium increased in silt clay with a diameter of less than 75 μm. In the bar graph in Table 2, Experimental Example 1 is on the left side, and Experimental Examples 2, 3, 4, 5, 6, and 7 are arranged on the right side in that order, and Experimental Example 7 is located on the right side.

  Further, from comparison between Experimental Example 2 and Experimental Example 7, it can be seen that the removal of cesium is improved by applying “vibration”. Further, from Experimental Example 4 and Experimental Example 5, no effect was observed when one of “compressed air” and “surfactant” was combined with “stirring”, and the release of cesium by the surfactant is It is thought that it is promoted by the turbulent flow generated by the injection.

  Tables 3 to 5 below show Cs ratios and the like of those classified into three.

  Tables 3 to 5 show the Cs ratio, the Cs removal rate relative to the original material, the reduction rate, and the Cs concentration for Experimental Examples 1, 3, 7, and 2.

  The Cs removal rate for the original material is expressed by the following equation.

  Cs removal rate relative to the original material = (1- (Cs ratio after processing / Cs ratio of original sample)) × 100

  Further, the decrease value is obtained by subtracting the upper value from the lower value in the Cs removal rate for the original sample. For example, in Table 3, the value of Experimental Example 7 is changed from the value of Experimental Example 7 to 75%. By subtracting, the drop value becomes 7%.

  As described above, in Experimental Example 3 with only “stirring”, the Cs removal rate with respect to the original sample is 68% for particles of 2 mm or more, but the Cs removal rate is 28% for particles of 75 μm to 2 mm. A sufficient effect was not obtained, and in Examples 2 and 7 using a surfactant, a high cesium removal rate was obtained.

  In Table 5, the increase in the Cs increase rate relative to the original sample suggests that the particles having a size of 75 μm or more have been transferred to particles having a free Cs of less than 75 μm.

  From these facts, Experimental Example 7 under the conditions of “stirring”, “surfactant” and “compressed air” is excellent in Cs removal effect, and further, “stirring”, “surfactant”, “compressed air” and “vibration” are the conditions. It was found that Experimental Example 2 in which Cs removal effect is more excellent than that.

FIG. 6 shows a flow related to this experiment. In this experiment, as in the preliminary experiment, a pot-type mixer 25 is used as the agitation processing apparatus, compressed air is supplied to the compression nozzle 29, and no vibration is applied. In addition, a stirring process by rotating the rotary drum 26 was performed for 2 hours. In addition, the interval dyeing amount at the time of collecting the contaminated soil A used in this experiment was 1.5 μSv / h, and the air dose at the time of collecting the contaminated soil B was 1.9 μSv / h.

  Before performing the agitation process, first, 2 kg of contaminated soil is put into the rotating drum 26, and a plurality of bolts (not shown) are mixed in the contaminated soil in the rotating drum 26 as an abrasive, and the same rotation as in the preliminary experiment. Rubbing was carried out for 2 hours at a speed. After the scrubbing, the abrasive was recovered.

  Thereafter, 20 liters of water was added to the contaminated soil, and 0.5 wt% (110 g) of a surfactant was mixed with the contaminated soil and water to form a contaminated soil mixture. After mixing, the rotating drum was stopped. The soaking was carried out for 15 hours in the form. Rubbing and soaking are pretreatments.

  After leaving still for 15 hours, the stirring process was performed on the same conditions as the said Example 7. That is, the stirring process was performed using “stirring”, “surfactant”, and “compressed air”.

  The results of experiments for soil A and soil B are shown in FIGS. In the figure, the upper part corresponds to the soil (contaminated soil before treatment), the middle part corresponds to the treated soil without pretreatment, and the lower part corresponds to the treated soil with pretreatment. The distribution of the particle size range is shown. For example, in the upper part of FIG. 7, from the left side, 16.9% of gravel with a particle size of 2 mm or more, 58.8% of coarse sand with a particle size of 425 μm to less than 2 mm, and 9 of fine sand with a particle size of 75 μm to less than 425 μm. 0.0% and the remaining silt clay is 15.3%.

  In this experiment, the boundary between fine particles and coarse particles (branch point) is 425 μm or more, that is, the fine particles are those that pass through 425 μm, but the boundary may be less than 425 μm, for example, As in the preliminary experiment, the boundary may be 75 μm or more (425 μm> boundary> = 75 μm).

  As is apparent from the figure, the composition of fine sand and silt clay in the contaminated soil tends to increase due to scrubbing in the stirring treatment. Furthermore, the tendency for the composition of fine sand and silt clay to become large becomes remarkable by performing pre-processing.

  9 and 10 show changes in cesium concentration in the contaminated soil A and the contaminated soil B. FIG. FIG. 9 shows the upper, middle, and lower band graphs of FIG. 7 on the left side, center, and right side, and the corresponding graph is shown below the band graph. The weight ratio is taken on the shaft.

  In the contaminated soil A shown in FIG. 9, the soil before stirring treatment had a Cs concentration exceeding 3000 Bq / kg for each particle size, and the contamination concentrations of coarse sand and silt clay were relatively high. After the stirring treatment, the Cs concentrations of gravel and coarse sand decreased to 2100 Bq / kg and 1920 Bq / kg, respectively, and further, the Cs concentration was lowered by pretreatment. In the present application, the reusable Cs concentration criterion is 3000 Bq / kg or less.

  Contaminated soil B has a larger amount of Cs than contaminated soil A. As shown in FIG. 10, in contaminated soil B, the Cs concentration exceeded 30000 Bq / kg for each particle size before the stirring treatment. By performing pretreatment after the stirring treatment, the Cs concentration was reduced to a contamination level of 1070 Bq / kg for gravel and 2360 Bq / kg for coarse sand.

The following was found from the above experiment.
(1) Effect of agitation treatment on contaminated soil A By washing and classifying contaminated soil A with a cesium concentration of 13000 Bq / kg, 54.4 wt% of soil particles (reki, coarse sand) is reduced to a cesium concentration of 3000 Bq / kg or less. be able to. In addition, the pretreatment reduces the contamination concentration, and approximately 65% of the soil particles (reki, coarse sand, fine sand) can be reduced to a cesium concentration of 3000 Bq / kg or less (see Table 6 below). Can be used as

(2) Contamination effect of contaminated soil B Contaminated soil B with a cesium concentration of 34000Bq / kg is pretreated and then washed and classified to reduce the contaminated concentration. Coarse sand) can be reduced to 3000 Bq / kg or less (see Table 7 below), and it is expected to be used as recycled material.
(3) Efficacy of pretreatment Although the Cs concentration is reduced by pretreatment, the volume of reki and coarse sand is reduced, so the balance between the cesium concentration and the volume of the washed soil is taken into account. It is necessary to consider the implementation of pretreatment.

  Here, the effect of rubbing by stirring will be described with reference to FIG. As shown in the figure, the fine particles adhering to the coarse particles are separated by the contact between the soil particles and the particles during the stirring, and the adhering fine particles adsorb more cesium than the coarse particles. Therefore, cesium can be separated together with fine particles.

  In addition, as shown in FIG. 12, the surface of the cesium is charged negatively (-) by the surfactant, and positive cesium is liberated, and the liberated cesium is adsorbed on the fine particles.

  In these cases, bubbles are generated by the compressed air, and the turbulent flow generated by the bubbles promotes the scrubbing and Cs releasing effect.

Thus, in this embodiment, in the method of removing radioactive materials fractionating contaminated soil 1 containing radioactive material and radioactive materials and processing soil, and removing process S1 to remove the contaminated soil 1, the contaminated soil 1 has been removed Mixing washing water and surfactant, stirring step S3 for stirring while supplying compressed air to the mixture, and classification step S4 for classifying the contaminated soil mixture after stirring into coarse and fine particles, Since coarse particles are obtained as treated soil, cesium is separated from the coarse particles by the separation action by the surfactant and the separation action by stirring while supplying compressed air, and the fine particles to which cesium is adhered. Can be separated from the coarse particles, and the separated cesium moves to the fine particles. Thereafter, the coarse particles and fine particles are separated to obtain the coarse particles having a low cesium concentration.

Also, in this way this embodiment, in 撹拌step S3, because applying vibration to the contaminated soil mixture, the agitation while supplying compressed air, by further applying vibration isolation effect of cesium is improved.

Further, in this embodiment Thus, prior to the 撹拌step S3, because for soaking by mixing a surfactant contaminated soil 1, by soaking with a surfactant goods to contaminated soil 1 prior to stirring treatment S3 By performing this, the separation action by the surfactant is improved.

Further, in this embodiment, since the coarse particles are reused , the coarse particles having a low cesium concentration can be reused as civil engineering materials.

Further, in this embodiment Thus, in the apparatus for removing radioactive material to separate contaminated soil 1 containing radioactive material and processing soil and radioactive substances, the removal device in the form dredger 2 to remove the contaminated soil to remove contaminants An agitation treatment device 5 as an agitation device for agitation while supplying compressed air to a mixture of washing water and a surfactant mixed in the soil 1, and a classification device for classifying the contaminated soil mixture after agitation into coarse and fine particles 6 has the same functions and effects as those of the first aspect.

Further, in the present embodiment in this manner, because provided with vibrating means for vibrating the mixed compound, the same operation and effect as the second aspect.

  Moreover, as an effect on the examples, the contaminated soil 1 is obtained by dripping and has a relatively high water content, so that fluidization is easy or unnecessary. In addition, since a pre-stirring step of scrubbing with agitation mixed with an abrasive is performed before the stirring treatment S2, fine particles containing cesium are mechanically scraped from the coarse particles. The pre-stirring means does not add water, and scrubs and rubs in a state where the water content ratio is lower than that in the stirring step S2, so that the effect of scraping off is high.

13 shows the removal device corresponding to the claims of the invention. In the figure, a modification of the agitation processing apparatus 5 is shown. In the agitation processing apparatus 5 of this example, a screw conveyor main body 32 is obliquely installed on a base 31, and the screw conveyor main body 32 is formed of a cylindrical body 33. The base end is connected to the base 31 by a pivot 34 so as to be swingable, and the distal end side of the trunk body 33 is connected to the base 31 by a telescopic drive means 35. Also, the tilt angle of the screw conveyor main body 32 can be adjusted by pivoting the end of the expansion / contraction driving means 35 to the base 31 and the trunk body 33 and driving the expansion / contraction driving means 35 as angle adjusting means to extend and contract. . As the expansion / contraction driving means 35, a fluid pressure driving cylinder such as a hydraulic cylinder can be used.

  A rotation drive shaft 36 is provided in the body main body 33, a screw 37 is provided on the rotation drive shaft 36, and both ends of the rotation drive shaft 36 are rotatably provided on the body main body 33 by bearings 38 and 38. Further, a driven wheel 39 is provided on the proximal end side of the rotation drive shaft 36, and the driven wheel 39 is rotationally driven, whereby the screw 37 is rotated and the mixture in the trunk body 33 is pumped from the proximal end side to the distal end side. The

A loading port 41 is provided at the upper part on the base end side of the trunk body 33, a discharge port 42 is provided at the lower end on the distal end side of the trunk body 33, and a feeding device 43 for feeding the mixture into the loading port 41 is provided. Further, a liquid supply port 44 is provided at the upper end on the distal end side of the trunk body 33, and an air nozzle 45 for compressed air is provided at the lower end on the proximal end side of the trunk body 33. In the case where vibration is applied to the mixture, vibration means 46 may be provided in the lower part of the outer periphery of the trunk body 33, and the mixture in the trunk body 33 may be vibrated by the vibration means 46 .

  Then, the contaminated soil mixture in the mud tank 4 is supplied to the charging device 43. Since water is supplied from the liquid supply port 44 to the trunk main body 33, a contaminated soil mixture having a lower water content is supplied to the charging device 43.

  A fixed amount of contaminated soil mixture is introduced into the inlet 41 from the charging device 43, and the mixture is transferred to the outlet 42 while being stirred by the screw 37 while being supplied with compressed air from the air nozzle 45 into the trunk body 33. And stirred. In this case, water is supplied from the liquid supply port 44 in accordance with the amount of the mixture charged in the charging device 43, and the mixture in the trunk body 33 is controlled to have a set water content ratio.

Thus, in the present embodiment , corresponding to claim 1, in the radioactive substance removing apparatus for separating the contaminated soil 1 containing the radioactive substance into the radioactive substance and the treated soil, the dredger 2 as a removing apparatus for removing the contaminated soil; , The stirrer 5 as a stirrer that stirs while supplying compressed air to the mixture of washed water and surfactant in the contaminated soil 1 that has been removed, and the contaminated soil mixture after the stirrer into coarse and fine particles A classifying device 6 for classifying, and the agitation processing device 5 includes a screw conveyor main body 32 that is obliquely arranged with the front end side being higher than the base end side. The screw conveyor main body 32 includes a body main body 33 and a body main body 33. A screw 37 that is rotationally driven to pressure-feed the mixture in the trunk body 33 from the proximal end side to the distal end side, an inlet 41 for the mixture provided on the proximal end side of the trunk body 33, and a trunk body 33. The mixing provided on the tip side of 33 A discharge port 42, an air nozzle 45 for supplying compressed air to the mixture in the trunk body 33, and a vibration means 46 for vibrating the mixture in the trunk body 33, so that the mixture is stirred by a screw 37. Therefore, the mixture can be continuously processed.

  Thus, in this embodiment, since the vibration means 46 is provided on the outer periphery of the trunk body 33 in accordance with the second aspect, the mixture in the trunk body 33 is vibrated by the vibration means 46 provided on the outer periphery of the trunk body 33. Can be given.

  Thus, in the present embodiment, corresponding to the third aspect, the liquid supply port 44 for supplying water into the trunk body 33 is provided, so that water can be supplied to the mixture in the trunk body 33.

  Thus, in the present embodiment, corresponding to claim 4, the base end side of the trunk body 33 is connected to the base 31 so as to be swingable, and the expansion and contraction is an angle adjusting means for adjusting the inclination angle of the screw conveyor body 32. The driving means 35 is provided, and in this embodiment, the angle adjusting means is the expansion / contraction driving means 35 pivotally attached to the trunk body 33 and the base 31 in correspondence with the fifth aspect. The angle of the body 33 can be adjusted. Therefore, when the rotational speed is constant, the stirring force applied to the mixture by the screw 37 can be increased as the angle increases.

Also, since provided with vibrating means 46 for vibrating the mixed compound, the agitation while supplying compressed air, by further applying vibration isolation effect of cesium is improved.

The present invention is not limited to this embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the embodiment, the agitation treatment may be performed after the foreign matter is separated from the removed contaminated soil. Moreover, radioactive materials may be used to remove a variety of radioactive substances is not limited to cesium.

1 Contaminated soil 1A Coarse grain 2 Dredger (removal device)
5 Stir processing device (stirring device)
6 Classification device (separation device)
12 Dehydrated soil (treated soil)
29 Compression nozzle
30 Vibrating bar
31 base
32 Screw conveyor body
33 trunk
35 Telescopic drive means (angle adjustment means)
37 screw
41 slot
42 outlet
44 Liquid supply port
45 Air nozzle
46 Vibration means

Claims (5)

In a radioactive substance removal apparatus for separating contaminated soil containing radioactive substances into radioactive substance and treated soil, the removal apparatus for removing the contaminated soil, and a mixture of washing water and a surfactant mixed in the removed contaminated soil, compressed air A stirring device that stirs while supplying water, and a classification device that classifies the contaminated soil mixture after stirring into coarse and fine particles ,
The stirring device includes a screw conveyor body that is obliquely arranged with the distal end side being higher than the proximal end side,
The screw conveyor body is
The trunk body,
A screw provided in the barrel main body, and rotationally driven to pump the mixture in the barrel main body from the proximal end side to the distal end side;
An inlet for the mixture provided on the base end side of the trunk body;
A discharge port of the mixture provided on the front end side of the trunk body;
An air nozzle for supplying the compressed air to the mixture in the trunk body;
An apparatus for removing a radioactive substance, comprising: vibration means for applying vibration to the mixture in the trunk body . 2. The radioactive substance removing apparatus according to claim 1, wherein the vibration means is provided on an outer periphery of the trunk body. The radioactive substance removing device according to claim 1, further comprising a liquid supply port for supplying water into the trunk body. The angle adjustment means which adjusts the inclination-angle of the said screw conveyor main body is connected with the base end side of the said trunk | drum main body so that rocking | fluctuation is possible, The any one of Claims 1-3 characterized by the above-mentioned. Radioactive material removal equipment. 5. The radioactive substance removing apparatus according to claim 4, wherein the angle adjusting means is an expansion / contraction driving means having end portions pivotally attached to the trunk body and the base.