KR20040087946A - A Dry Separation Method - Google Patents

Abstract

PURPOSE: A dry separation method and apparatus are provided to continuously separate even the wet subject into each component at a low cost and to be eco-friendly. CONSTITUTION: The dry separation method comprises the steps of: inputting a separation subject to a gas-solid fluidized bed(2) for fluidizing powders and separating the separation subject continuously using an apparent density of the gas-solid fluidized bed, wherein the powders have a water repellency. A contact angle of the powders to a water is at least 10 degrees. The powders have a water repellency in itself or have a water repellent coat. The water repellent coat is selected from the group consisting of a carbon fluoride fiber and a silane based.

Description

Dry Separation Method

The present invention relates to a dry separation method capable of performing gravity separation of an object to be separated into various components without using a liquid.

Industrial products, mineral resources, industrial waste, etc., each made from a variety of raw materials, include a variety of other components. Therefore, it is necessary to separate these components from each other for the purification of mineral resources and the recycling of resources.

To date, wet separation methods and dry separation methods have been known mainly as separation methods.

For example, as a dry separation method, a fluidized bed is formed by blowing air into powder as a medium to a fluidized bed, coal powder is introduced into a gas-solid fluidized bed, and coal powder is fluidized by using a difference in density generated in the fluidized bed. Dry separation methods of coal are known (JPA2000-61398), which include separating into coal powder having a density less than the apparent density of and coal powder having a density greater than the apparent density of the fluidized bed.

Prior Art: JPA2000-61398

However, the dry separation method has problems such as high device cost and low efficiency. The wet separation method has problems such as environmental pollution caused by waste liquid treatment, the method cannot be used where there is little water resource, and a drying step is required after waste liquid treatment or separation.

In addition, the separation object often contains impurities other than the target component. However, the method of continuously recovering a target component while removing impurities is not known until now.

In addition, when the separation object is dry, separation is sufficient, but when the separation object is wet, there is a problem that separation is difficult. This is because when the wet objects are introduced into the gas-solid fluidized bed, the moisture on the wet objects moves to the powder surface, causing the powder to agglomerate with each other. As a result of this, fluidization of the fluidized bed becomes unstable. In addition, there is another problem that the powder adheres to the surface of the separated object.

Accordingly, the present invention is to provide a dry separation method and apparatus which is capable of continuously separating the separation object into each component at low cost, even when the separation object is wet.

The inventors noted that the gas-solid fluidized bed which fluidizes the powder has properties similar to liquids in density, viscosity and the like. In particular, as a result of examining the behavior of objects having various densities under fluidization conditions, the present invention has been achieved.

The present invention will be described with reference to the accompanying drawings.

1 is a schematic view showing an embodiment of an apparatus for separating an object to be separated.

2 is a schematic view showing an embodiment for recovering a component from a separation object.

3 is a schematic view showing another embodiment for recovering a component from a separation object.

4 is a schematic diagram illustrating an embodiment of a separation system according to the present invention.

5 is a graph showing the density distribution of an object at various V _SS values.

6 is a graph showing the flotation-settling state of silica and feldspar by varying breathability.

7 is a graph showing the height in the fluidized bed of each separation object.

8 is a graph showing the height in the fluidized bed of each separation object.

9 is a graph showing the height in the fluidized bed of silica and feldspar.

10 is a graph showing the relationship between the contact angle of powder and time.

11 is a graph showing the relationship between the pressure loss and the tower speed when the relative humidity of air in each powder is changed in the range of 50 to 80%.

Fig. 12 is a graph showing the results obtained when the relative humidity of air in each powder is changed in the range of 50 to 80%.

Fig. 13 is a graph showing the results obtained when the relative humidity of air in each powder is changed in the range of 50 to 80%.

FIG. 14 shows the flotation-settling state of wet coal in a fluidized bed using three powders with different wettability.

<Description of the code>

1 lighter than the apparent density of the fluidized bed

2 gas-solid fluidized beds

3 objects heavier than the apparent density of the fluidized bed

4 separation tank

5 gas dispersion plate

6 collection means

7, 7a, 7b means of transport

8 shroud

9 induction plate

10 gas chamber

11 baskets

12 outlet

13 perforated plate

14 propeller

15 gas

16 orifice flow meter

17 pressure sensor

18 data logger

19 personal computers

20 blower

21 motor valve

22 electrical signal

According to a first aspect of the present invention, a separation object is introduced into a gas-solid fluidized bed for fluidizing powder, and the separation object is continuously separated into each component by using the apparent density of the gas-solid fluidized bed. The powder is provided with a dry separation method, having water repellency.

In a preferred embodiment of the first aspect of the invention, the continuous separation is performed by changing the apparent density.

In another preferred embodiment of the first aspect of the invention, the contact angle of the powder with respect to water is at least 10 °.

In another preferred embodiment of the first aspect of the invention, the powder itself is water repellent or has a water repellent coating.

In another preferred embodiment of the first aspect of the invention, the water repellent coating is at least one member selected from the group consisting of fluorocarbon fibers and silane based agents.

In another preferred embodiment of the first aspect of the invention, the fluidization of the powder is carried out by blowing to the bottom of the gas-solid fluidized bed.

In another preferred embodiment of the first aspect of the invention, the blowing is carried out under conditions of breathability of 5.0 (cm 3 / s) / cm 2 or less.

In another preferred embodiment of the first aspect of the invention, the blowing is carried out at a ratio of u ₀ / u _mf in which u ₀ is the tower speed and u _mf is the minimum fluidization velocity of the powder. .

In another preferred embodiment of the first aspect of the invention, the blowing is carried out at a value of the u ₀ / u _mf ratio which causes the plurality of powders to be uniformly mixed when the plurality of powders are fluidized.

In another preferred embodiment of the first aspect of the invention, the apparent density of the solid-gas fluidized bed is set between the maximum density and the minimum density of the components in the separation object.

In another preferred embodiment of the first aspect of the invention, the powder is unibiz (unibeads®), glass beads, zircon sand, polystyrene particles, still shots and powders having a density substantially equal thereto.

In another preferred embodiment of the first aspect of the invention, the separation object comprises waste, ore, crops, plastics, metals.

In another preferred embodiment of the first aspect of the invention, the average particle diameter of the powder is 100-500 μm.

The principle of the present invention is explained as follows. In other words, the powder is fluidized using a powder fluidization medium, ie, a gas-solid fluidized bed, similar to the specific gravity screening of a liquid system, thereby separating the separation object mainly according to its density. In addition to this, it is also one of the characteristics to use powder which has water repellency as said powder. The use of water repellent powders makes it easy to separate wet objects that are difficult to separate from one another. Therefore, the present invention has an advantage in that it can provide a stable fluidized bed. As used herein, the term "gas-solid fluidized bed" means having fluid-like properties by fluidizing the powder.

First, the concept of separation by gas-solid fluidized bed is explained as follows. In the case of suspended fluidization by supplying gas to the powder, the fluidized bed of powder exhibits a liquid-like behavior.

Therefore, the apparent density ρfb of the fluidized bed is represented by the following formula.

In the above formula, W _p is the powder weight of the fluidizing medium, V _f is the volume at the fluidization, ε _f is the porosity at the fluidization, and ρ p is the powder density of the fluidizing medium.

When the separation object having a density ρs is included in the fluidized bed having the apparent density ρfb, the separation target component (ρs <ρfb) having a density lower than the apparent density is suspended above the fluidized bed and has a density higher than the apparent density ( ρs> ρfb) settles under the fluidized bed. In addition, a component to be separated (ρs = ρfb) having the same density as the apparent density is suspended in the middle of the fluidized bed. By using this fact, specific gravity screening of the separation object is performed.

In this way, each component in the separation object can be separated. Therefore, it becomes possible to easily recycle each separated component.

In the present invention, the separation object is not particularly limited based on the separation principle. As the separation object, various mineral resources, industrial products, shredder dust, and the like can be mentioned. As a mineral resource, mentioned minerals, such as a silica, a lead, etc .; And coal mined in coal mines. In shredder dust, shredder dust from household dust, automobiles, household appliances, etc. can be mentioned. As mentioned above, any separation object can be used, but if the separation object is contaminated, it is preferable to perform separation after washing. This is because according to the separation method of the present invention, since the separation objects are mainly separated by their specific gravity difference, the specific gravity may be changed if the separation objects are contaminated.

In addition, since it is possible to efficiently separate the wet object, there is no problem even if the separation object is wet.

Next, the water repellency of the powder will be explained. The degree of water repellency of the powder is not particularly limited as long as the aggregation of each powder and the adhesion of the separated object and the powder can be suppressed. Also, the degree of water repellency differs depending on the degree of wetness of the object to be separated.

The powder is not particularly limited as long as the powder has water repellency, but a contact angle of 10 ° or more is preferable, for example. When higher water repellency is required, a contact angle of 50 ° or more is preferred, and a contact angle of 90 ° or more is more preferred. The contact angle gets lower over time. Therefore, it should be noted that the contact angle does not go to 0 ° at least during separation. This is because when the contact angle reaches 0 °, the powder is not recognized as having water repellency, and thus, the desired water repellent effect cannot be obtained.

The embodiment of the powder having water repellency is not particularly limited. For example, the powder itself having water repellency can be used. When the powder itself does not have water repellency or does not have the desired water repellency, the powder may be coated with a specific material having water repellency. Such a coating is not particularly limited. For example, as a film which has water repellency, 1 or more types chosen from the group which consists of a fluorocarbon fiber and a silane type agent are mentioned.

The thickness of the coating is not particularly limited as long as the coating has a thickness sufficient to satisfy the water repellency of the powder. The sufficient particle diameter of the powder containing a film is 100-500 micrometers.

In the present invention, the continuous separation of each component can be performed, for example, by changing the apparent density of the gas-solid fluidized bed, arranging two or more gas-solid fluidized beds in series, and the like.

The apparent density in the gas-solid fluidized bed changes the value of the u ₀ / u _mf ratio described below, or changes the powder used in the gas-solid fluidized bed, changes the particle size of the powder, or the mixed powder. Can be changed by changing the mixing ratio.

Since the change in the apparent density also depends on the type of separation object, the apparent density does not necessarily decrease when the value of the u ₀ / u _mf ratio is increased. On the other hand, when the density of the powder used for the gas-solid fluidized bed is high, the apparent density of the gas-solid fluidized bed also tends to generally increase. In addition, when the particle size of the powder increases, the apparent density also tends to increase. Thus, in view of these facts, it is possible to continuously separate each component by changing the apparent density.

In a preferred embodiment of the dry separation process according to the invention, fluidization of the powder can be carried out by blowing to the bottom of the gas-solid fluidized bed, thereby increasing the number of separable components. However, the present invention is not intended to be limited only to blowing to the bottom of the gas-fluidized bed. For example, a component having a relatively low specific gravity can be separated even by blowing from the transverse direction. When a component having a low specific gravity is clearly present, the component can be separated with high efficiency even by the lateral blowing because the transverse scattering distance of the component is large. Therefore, the components having low specific gravity can be first removed by lateral blowing, and then each component remaining in the separation object can be removed.

When a component having a low specific gravity is present as impurities other than the target component in the object to be separated, impurities can be removed by the same process as described above.

In the present invention, since the stabilization of the flotation-settling is achieved by controlling the air permeability, blowing is performed under the condition of the air permeability of 5.0 (cm 3 / s) / cm 2 or less. Breathability is determined according to the separation object and is not particularly limited. The breathability is 5.0 (cm 3 / s) / cm 2 or less, preferably 3.0 (cm 3 / s) / cm 2 or less, more preferably 1.0 (cm 3 / s) / cm 2 or less.

In the present invention, u ₀ / u _mf (where u ₀ is the column speed and u _mf is the minimum fluidization rate of the powder of the powder) is one factor controlling the separation. This is because two components having very close density differences can be easily removed by adjusting the tower speed, or components having a large density difference can be separated in a short time by increasing the tower speed.

In general, if the tower speed is set above the minimum fluidization rate but approximate the minimum fluidization rate, the density distribution of the components in the separation objects suspended in the gas-solid fluidized bed will be narrowed, but further increase of the tower speed will cause the suspended fluid in the gas-solid fluidized bed. The density distribution of components in the separation object is widened.

Therefore, the present invention has the advantage of being able to separate two kinds of components (two kinds of substances) having a small density difference which were difficult to separate in the prior art. In order to finely control the tower speed, mention may be made of the use of low breathable powders underneath the gas-solid fluidized bed which disperses the air.

In the case of roughly separating the components, the components can basically be divided into three types: flotation components, mesofloating components, and sedimentation components. However, in many cases, components having difficulty in separation due to low density differences are often separated, so that the density distribution of the suspended solids component is narrowed as much as possible to make u ₀ / u _mf values so that the components float or settle, resulting in higher separation accuracy and higher separation. Separation can be carried out with high recovery.

For example, since it is the range in which a stable gas-solid fluidized bed can be formed, the u ₀ / u _mf value can be made in the range of 1-4. However, the u ₀ / u _mf value is not limited to this range, and the u ₀ / u _mf value may be 4 or more when rapidly separating components having a large density difference.

When fluidizing a single powder, when separating components having a small density difference, it is preferable that the u ₀ / u _mf value is as close to 1 as possible depending on the powder used. The u ₀ / u _mf value may be 1 to 1.5, preferably 1 to 1.2, more preferably 1 to 1.1.

In the case where a plurality of powders are fluidized, it is preferable to perform blowing at a value of u ₀ / u _mf ratio in order to uniformly mix the plurality of powders. In the case where a plurality of powders are not uniformly mixed, the apparent density becomes smaller on the upper side of the gas-solid fluidized bed, but the apparent density becomes higher on the lower side of the gas-solid fluidized bed, so that the density of the component located in the middle portion in the gas-solid fluidized bed. The distribution tends to be large.

The type of powder is not particularly limited depending on the type of separation object to be separated, but the powder is a group consisting of unibiz (registered trademark), glass beads, zircon sand, polystyrene particles, still shots, and powders having almost the same density as these. It may be one or more selected from.

Although the average particle diameter of the powder to be used is not specifically limited, It is preferable that it is 100-500 micrometers in that fluidization of powder is performed at a relatively small tower speed, and aggregation of powder is suppressed.

As mentioned above, each component separated from the separation object can be raised or settled and finally recovered by an appropriate method.

An embodiment of a dry separation apparatus according to the present invention will be described with reference to the accompanying drawings. 1 shows the suspended-settling state of an object in a gas-solid fluidized bed, where (1) is an object lighter than the apparent density of the fluidized bed, (2) is a gas-solid fluidized bed, and (3) is the apparent density of the fluidized bed. The heavier object (4) is the separation tank and (5) is the gas-dispersion plate. As can be seen from the figure, the object can be separated by the apparent density of the gas-solid fluidized bed in the fluidized state of the powder.

An example of a separation procedure is demonstrated. First, a fluidizing medium such as glass beads, unibiz®, zircon sand, polystyrene particles, and the like is introduced into a separation tank 4, and through the gas-dispersion plate 5 from the bottom surface of the separation tank 4. The gas or the powder is fluidized by uniformly supplying gas into the separation tank 4 to form the fluidized bed 2. When the object to be separated is introduced from the upper surface opening of the separation tank 4, the component to be separated having a greater density than the powder used is settled. 2 shows an example of an apparatus for recovering components separated from an object to be separated. 2A is a schematic view of the device, FIG. 2B is a side view of the device, and FIG. 2C is a front view of the device.

In Fig. 2A, 6 is a collecting means, 7 is a conveying means, 8 is a protective plate, 9 is a guide plate, and 10 is a gas chamber. The collecting means 6 is rotated at a slow speed in the direction indicated by the arrow c of FIG. 2C to recover the heavy component 3 that settles from the separation object and discharge it out of the separation tank 4. That is, the heavy component 3 of the object to be separated is guided to the collecting means 6 through the guide plate 9 and collected in the basket 11 installed in the collecting means 6. The heavy component 3 in the basket 11 moves to the upper part of the separation tank through the rotation of the collecting means and moves to the outlet 12 by the weight of the heavy component itself.

On the other hand, the conveying means 7 is moved in the direction indicated by the arrow d of FIG. 2C while rotating at a slow speed, so as to recover the light component 1 supported in the separating object and discharge it out of the separating tank 4. . In this case, the guard plate 8 easily guides the light component 1 from the object to be separated into the conveying means. Although light component 1 can be collect | recovered without providing the protection plate 8, in order to collect | recover light component 1 efficiently with high recovery rate, it is preferable to provide the protection plate 8 also. The light component 1 thus induced is discharged out of the separation tank 4 by a conveying means 7 such as a conveyor.

In Fig. 2, reference numeral 5 denotes a gas-dispersion plate made of a porous material such as a wire mesh. In this case, the wire mesh needs to have a fine mesh so that the object to be separated does not pass. In addition, the gas for forming the fluidized bed is not limited to air, and may include other gases.

The guard plate and the guide plate are not limited to the embodiment shown in FIG. 2, respectively, but may be appropriately modified as long as they have the action of easily inducing light or heavy components to the conveying or collecting means. For example, a plurality of porous plates can be provided to prevent the flotation component and the settling component from mixing during recovery. It is also possible to install propellers for flotation components instead of guard plates, but propellers can be installed at the bottom of the gas-solid fluidized bed instead of conveying means to efficiently guide the settling components to the collecting means.

Another example of a recovery method is shown in FIG. 3, which represents an apparatus for recovering components separated from shredder dust. In FIG. 3, the conveying means 7b moves in the direction of the arrow while rotating at a low speed, during which the heavy component settling out of the shredder dust is recovered and discharged out of the separation tank 4.

On the other hand, the conveying means 7a moves in the direction of the arrow while rotating at a low speed, during which the light component supported by the shredder dust is recovered and discharged out of the separation tank 4.

3, reference numeral 13 denotes a porous plate made of a porous material such as a wire mesh. In this case, the wire mesh needs to have a fine mesh so that the object to be separated does not pass. Gas-dispersion plates are also the same. In addition, the gas for forming the fluidized bed is not limited to air, and may include other gases.

If it is possible for the porous plate 13 to guide the flotation component and the settling component to be separated to a conveying means such as a conveyor, it is not limited to the structure shown in FIG. 3 and can be modified as appropriate. For example, a plurality of porous plates may be provided to prevent the flotation component and the settling component from mixing during recovery. 3, a propeller 14 for the flotation component is provided. In addition, a propeller may be installed at the bottom of the gas-solid fluidized bed to efficiently guide the settling components to the conveyor.

The following examples are intended to illustrate the invention and are not intended to limit the invention.

<Example 1>

First, the relationship between the mixing ratio and the apparent density of the mixed powders was investigated using a separation system as shown in FIG. An air-dispersion plate was installed at the bottom of the separation tank by sandwiching a cloth between two porous stainless steel plates having a hole diameter of 0.2 cm, a pitch of 0.3 cm, and a porosity of 40.3%. The powder was poured into the separation tank at a height of 40 cm and fluidized by supplying air through a blower, and the tower speed was finely adjusted by opening and closing the motor valve. Since a large tank (width 60 cm × depth 45 cm × powder height 40 cm) was used as the separation tank, the air chamber under the gas-distribution plate was divided into six parts, and the cross-sectional area also increased as the device was enlarged. The tower speed was controlled with good precision at.

In FIG. 4, 4 is a separation tank, 15 is a gas, 16 is an orifice flow meter, 17 is a pressure sensor, 18 is a data logger, 19 is a personal computer, 20 is a blower And 21 are motor valves and 22 are electrical signals.

The pressure of the orifice flowmeter 16 and the pressure difference between the fluidized bed bottom and the atmosphere are read by the pressure sensor 17 as a voltage value, and the tower speed u is obtained by using the relationship between the voltage-to-air speed and voltage-pressure loss obtained in advance. ₀ and pressure loss ΔP were obtained. As used herein, the term "pressure loss ΔP" means the pressure the gas receives from the powder when the gas fluidizes the powder. For example, when gas is supplied from the bottom, a pressure corresponding to the weight of the powder is applied to the gas, which is called the pressure loss ΔP. When the tower speed exceeds a certain value, the powder starts to flow and the pressure loss is constant. In other words, when the pressure loss is constant, the fluidization state of the powder is indicated.

In the process of gradually decreasing u ₀ , ΔP was measured and the u ₀ value when ΔP began to decrease from a constant value was taken as the minimum fluidization rate u _mf .

In practice, two powders of steel shot (SS) and glass beads (GB) mixed at various volumetric volume ratios V _SS in the tank were injected and fluidized at a height of about 40 cm, and the relationship between the tower speed u ₀ and the minimum fluidization speed u _mf The test was performed by making u ₀ / u _mf 1.7. In addition, the air permeability was set to 0.3 (cm 3 / s) / cm 2. In addition, the minimum fluidization rate was calculated by the relationship of the tower speed-pressure loss obtained in the process of reducing u ₀ so that segregation was not caused from the u ₀ value at which the bicomponent powders were completely mixed. The properties of the powder used are shown in Table 1 below.

Powder Size (μm) Actual density (kg / ㎥) Apparent density (kg / ㎥) Steel shot 45-106 7600 4300 Glass beads 180-250 2500 1500

5 shows the results of the experiment. FIG. 5 shows the suspended-settling state of spheres of each density in a gas-dispersion plate with low breathability (0.3 (cm 3 / s) / cm 2) in the tank. In the case of small amounts of steel shots (0.35), light spheres settled, and in the case of large amounts of steel shots (0.45), heavy spheres settled. Since the density of the spheres at the suspended-settling boundary represents the apparent density of the fluidized bed, the apparent density increased as the proportion of steel shots having a heavier density than the glass beads increased. Regarding the mixing ratio of the powders, V _SS = 0.35 indicates SS: GB = 35: 6, V _SS = 0.40 indicates SS: GB = 40: 60, and V _SS = 0.45 indicates SS: GB = 45.55.

As can be seen from the results of FIG. 5, the apparent density increased as the proportion of heavy powder in the mixed powder increased.

<Example 2>

Next, a separation test using ore, in particular silica and leadstones, as separation objects was carried out using the same system as in Example 1. Quartzite has a peak at 2300 to 2550 kg / m 3, while leadstone is distributed in a narrow range of 2650 to 2750 kg / m 3 and has a peak at 2700 kg / m 3. They had equivalent volume diameters in the range of 10 to 50 mm, where the silica was 30.5 ± 8.6 mm and the feldspar was 30.3 ± 8.1 mm.

6 shows suspended-sedimentation in layers of silica and feldspar under various conditions. FIG. 6A is the case where the condition is breathable = 8.13 (cm 3 / s) / cm 2, V _SS = 0.40, and FIG. 6B is the case when the condition is breathable = 0.30 (cm 3 / s) / cm 2, V _SS = 0.35, and FIG. 6C Is a case where the condition is breathable = 0.30 (cm 3 / s) / cm 2, V _SS = 0.40, and FIG. 6D is a case where the condition is breathable = 0.30 (cm 3 / s) / cm 2, V _SS = 0.45.

As the ore used in the experiment, stones having a specific average density were selected from silica and leadstone, respectively. The stones were introduced into each of six gas chambers in the tank, and the height of the tank was measured 1 minute after the injection, and this process was repeated 10 times. From the results thus obtained, the ratio of the number of stones present at each height was plotted. In the case of highly breathable gas-dispersed plates, two ores existed at approximately equal ratios at each height, so that no stable suspended-settling was obtained. On the other hand, in the case of V _SS = 0.35, both ores settle because the apparent density of the fluidized bed is too small, whereas in the case of V _SS = 0.45, the ore was supported both because the apparent density was too large. In the case of V _SS = 0.40, the ore was substantially completely separated because the silica was buoyed and the sediment was settled.

As can be seen from the above results, when the air permeability is low compared to 8.13 (cm 3 / s) / cm 2, the suspension-sedimentation is considerably stable and can be separated more accurately.

<Example 3>

Next, separation of the target components was attempted while continuously removing impurities. An acrylic cylinder with an inner diameter of 25.4 cm, a height of 52 cm, and a thickness of 0.5 cm was prepared as a separation tank. An air-dispersion plate was installed at the bottom of the tank by sandwiching a cloth between two porous stainless steel plates having a hole diameter of 0.2 cm, a pitch of 0.3 cm, and a porosity of 40.3%. The test was carried out in the same manner as in Example 1 except that the breathability was adjusted to 0.3 (cm 3 / s) / cm 2 and the powder was introduced into the tank at a height of 10 cm.

Silica and leadstone were used as the separation object. As impurities, wood chips, coal, engineering plastics and scrap metal were used.

Glass beads (particle diameter: 180-250 μm) and still shots (particle size: 45-106 μm) were used as the powder.

First, only glass beads were introduced at a height of 10 cm and fluidized under three conditions of u ₀ / u _mf = 1.1, 1.5 and 2.0. The experimental process and the result were as follows. In the case of glass beads only, 6 types of separation objects were put into the tank one by one, and the height in the tank was measured 1 minute after all the states were put.

The results are shown in FIG. As shown in FIG. 7, at u ₀ / u _mf = 1.1 and 1.5, wood chips, coal, engineering plastics, and the like were supported and the rest were settled. At u ₀ / u _mf = 2.0, the engineering plastics also settled because the apparent density of the fluidized bed decreased with increasing blowing speed. From these results, it was found that in the case of u ₀ / u _mf = 1.1 and 1.5, wood chips, coal and engineering plastics can be separated from six objects.

Indeed, impurities such as wood chips, coal and engineering plastics were continuously separated and removed by varying u ₀ / u _mf values using the separation device of FIG. 2. In addition, silica, feldspar and scrap iron were once removed from the separation tank using the separation device shown in FIG. 2 as sediment.

Next, only steel shots were put into the tank at a height of 10 cm and fluidized under three conditions of u ₀ / u _mf = 1.1, 1.5, and 2.0, to remove another impurity scrap metal.

Precipitated silica, feldspar and scrap iron were introduced into the fluidized bed and the height in the bed was measured one minute after all the states were added.

The results are shown in FIG. As shown in FIG. 8, only scrap iron precipitated in any u ₀ / u _mf . The settled scrap was separated and recovered by a separator. Floating silica and leadstones were also recovered in the same way and led to the next separation tank.

Finally, an attempt was made to separate the silica and the lead. The mixed powder of glass beads and still shots was used to feed the supported silica and feldspar into the fluidized bed, and the height in the bed 1 minute after the respective states mentioned below was measured. Specifically, glass beads and still shots were mixed at a volume ratio of 60:40 and charged to a height of 10 cm, followed by fluidization under three conditions: u ₀ / u _mf = 1.1, 2.0 and 3.0.

The results are shown in FIG. As shown in FIG. 9, in the case of u ₀ / u _mf = 3.0, silica was supported and feldspar precipitated. On the other hand, the reason why the same result is not obtained at other u ₀ / u _mf values is considered to be due to the fact that the glass beads do not mix well with the steel shot or the fluidization is too small when u ₀ / u _mf is small.

Respective silica and precipitated feldspar were recovered in the same manner as described above using the apparatus shown in FIG. 2, respectively.

The continuous use of the three fluidized beds mentioned above can remove impurities such as wood chips, coal, engineering plastics and scrap metal from the six objects and then separate the silica and leadstones.

<Example 4>

Next, the separation effect was examined by using the powder which has water repellency according to the method as described in the Example mentioned above.

The particle size and apparent density of the three powders used in this test are shown in Table 2.

Powder Particle size (μm) Apparent density (kg / ㎥) A 250-300 1530 B 250-300 1530 C 210-420 1530

In order to investigate the wettability of the water adhered to these particles, 0.6 ml of water was added dropwise to the surface of the particles after taking the particles into a case having a length of 70 mm × 15 mm × 15 mm in depth, and a photograph was taken from the side. The contact angle of the powder was read from the photograph. The larger the contact angle, the higher the water repellency and the lower the wettability. The change of time and contact angle after dripping water is shown in FIG.

As a result, the water permeated the powder A at the moment of dropping water, and no water droplets were formed on the surface of the powder. That is, powder A has very high wettability. When water was dripped, water droplets formed on the surface of the powder B, and as a result, the contact angle decreased with time, and water permeated through the powder B. On the other hand, in the powder C, water droplets existed for a long time, and the contact angle was also high. As a result, the powder C had the highest water repellency, followed by the powder B, and finally the powder A had the lowest water repellency among them.

Then, the relationship between the pressure loss (pressure applied at the bottom of the powder layer) and the tower speed (the speed of air discharged from the bottom of the powder layer) was investigated using these powders A-C.

When the relative humidity of air was changed in the range of 50 to 80%, the obtained result is shown in FIG. In addition, the stability of fluidization was evaluated by the minimum fluidization rate, indicated by the dashed lines in the figure. The minimum fluidization rate means the tower speed at which the powder bed becomes a fixed bed in the absence of fluidization when the tower speed decreases. For powder A with low water repellency, the minimum fluidization rate was about the same as the fluidization rate at 50% and 60% relative humidity. On the other hand, the minimum fluidization rate increased with increasing relative humidity. This is because the powder agglomerates with each other as the relative humidity increases, so that the fluidization becomes unstable. In powders having higher water repellency than powder A, the minimum fluidization rate was increased at only 80% relative humidity. In addition, in powder C having high water repellency, the minimum fluidization rate was almost the same at any relative humidity. In other words, it has been found that fluidization is stabilized by using powder having high water repellency as the fluidizing medium and suppressing aggregation of the powder with increasing increase in humidity.

Example 5

The flotation-sedimentation of the separation objects having various densities was investigated. In order to investigate the effect of air humidity on fluidization and stability on the floating-sedimentation of an object using the powder AC used in Example 4, the floating-sedimentation of particles having various densities was investigated. The powder was fluidized at 1.1 times the minimum fluidization rate (u ₀ / u _mf = 1.1), and the particles having various densities (table tennis balls having a diameter of 3.75 cm containing a predetermined amount) were introduced into the fluidized bed, and 1 was added. After minutes the height in the layer was measured.

In the case where the relative humidity of air in each powder was changed in the range of 50 to 80%, the obtained result is shown in FIG. In addition, the suspended-sedimentation coefficient of the longitudinal axis is defined as 1.0 when the particle fully floats and 0 when the particle fully settles. In powder A having low water repellency, particles of 1400 kg / m 3 or less are supported at 50% and 60% relative humidity, and other particles having a higher density than the above settle. However, particles having a density of less than 1400 kg / m 3 settle and, in particular, the density range of the particles suspended in the layer without floating or sedimenting at 80% humidity results in an unstable floating-settling of the particles. . This is because the powders aggregate with each other as the relative humidity increases, so that the fluidization becomes unstable. At this time, the boundary density of the suspended-sediment of the particles represents the apparent density of the gas-solid fluidized bed. For example, the apparent density would be about 1410 kg / m 3 at 50% and 60% relative humidity. In addition, in the case where the objects are actually separated by specific gravity separation, as the density range of particles suspended in the layer becomes larger without floating-sedimentation, it will be difficult to separate between two objects having a small density difference. On the other hand, in powder B, there existed a tendency to distribute to the low density side only when relative humidity is 80%. In the powder C having high water repellency, the same behavior was obtained in either state of relative humidity. In other words, excellent results were obtained in which the formation of particles suspended in the layer was suppressed without the particles being suspended-settling. This is because the fluidization and suspension-precipitation of the particles are stabilized even when the relative humidity is high by using particles having high water repellency as the fluidizing medium.

As described above, it has been found that fluidization and suspension-sedimentation of particles are stabilized and conditions suitable for specific gravity separation are obtained even when the humidity is increased by using particles having high water repellency as the fluidizing medium.

<Example 6>

Next, the suspended-sedimentation of the dried ore with various densities under various humidity conditions (50, 60, 70 and 80%) was investigated in relation to the suspended-sedimentation of the dried ore. The size of the ore was about 3 cm at any density. Experimental conditions are the same conditions as in the above example. Each particle was fluidized at 1.1 times the minimum fluidization rate (u ₀ / u _mf = 1.1), and each ore was introduced into the fluidized bed and the height in the bed was measured 1 minute after the addition. In the case where the relative humidity of air in each powder was changed in the range of 50 to 80%, the obtained result is shown in FIG.

As a result, it was found that stable fluidization is obtained when using a high water repellent powder, and excellent separation can be performed.

<Example 7>

Next, the powder AC used in the above example was used to investigate the separation of the ore as a wet object. Ore was introduced into the water, taken out and then introduced into the fluidized bed. Each particle was fluidized at 1.1 times the minimum fluidization rate (u ₀ / u _mf = 1.1) to inject ore into the fluidized bed and the height in the bed was measured 1 minute after the addition. This experiment was conducted under conditions of 50% and 80% relative humidity. The results are shown in FIG. In powder A, hardly sedimented when wet ore was thrown in. This is because when wet ore is introduced into the bed, the ore cannot sediment due to aggregation due to humidity or moisture and the particles present on the surface of the ore cannot fluidize. In powder B, a small amount of dense ore could settle. In powder C having a high water repellency, it was found that even when the wet object of the object was charged, the same flotation and sedimentation occurred as when the dry object was added without aggregation between the particles in the vicinity of the object surface.

<Example 8>

Next, the amount of particles attached to the wet ore was investigated. Each particle was fluidized at 1.1 times the minimum fluidization rate (u ₀ / u _mf = 1.1), and each wet ore was introduced into the fluidized bed to investigate the ratio of the ore surface adhered particle weight to the weight of the ore 30 seconds after the input. It was. In addition, the average amount of the weight ratio of the attached particles was investigated using ores having different densities (1275 kg / m 3, 1380 kg / m 3 and 1517 kg / m 3). The results are shown in Table 3.

Powder Adhesion Particle Weight Ratio (%) A 19.7 ± 1.2 B 9.9 ± 1.9 C 6.5 ± 1.0

For powder A having low water repellency, about 20% of the weight of the ore was attached to the ore surface. In powder B, about 10% of the ore weight was attached to the ore surface. Powder C having high water repellency has a low value of 6.5%. It has been found that the addition of a wet object using a high water repellent powder as the fluidizing medium greatly reduces particle adhesion to the surface of the object, although not complete.

The results are shown in FIG. FIG. 14 shows the suspended-settled state of wet coal in a fluidized bed using three powders with different wettability.

As can be seen from these results, powder C enables the most efficient separation when powder C is used at both 50% and 80% humidity.

The present invention exhibits an advantageous effect that the apparatus cost is low, the efficiency is high, the drying step after waste liquid treatment or separation is unnecessary, and there is little effect on the environment.

In addition, the present invention can be used in areas where there is little water resources because of the dry separation.

In addition, the present invention enables efficient separation of wet objects. The present invention can suppress aggregation of each particle caused by humidity or moisture, thereby forming a stable fluidized bed. In addition, the present invention can prevent the particles from adhering to the object to be separated or the surface of the separated object.

Claims (12)

The separation object is introduced into a gas-solid fluidized bed which fluidizes the powder, and the separation object is continuously separated into each component by using the apparent density of the gas-solid fluidized bed, wherein the powder has water repellency. . The dry separation method according to claim 1, wherein the contact angle of the powder with respect to water is 10 ° or more. The dry separation method according to claim 1 or 2, wherein the powder itself is water repellent or has a water repellent coating. The dry separation method according to claim 1 or 2, wherein the water repellent coating is at least one member selected from the group consisting of fluorocarbon fibers and silane-based agents. The dry separation method according to any one of claims 1 to 4, wherein the fluidization of the powder is carried out by blowing the lower part of the gas-solid fluidized bed. The dry separation method according to any one of claims 1 to 5, wherein the blowing is performed under conditions of breathability of 5.0 (cm 3 / s) / cm 2 or less. The blowing process according to any one of claims 1 to 6, wherein the blowing is carried out in a range of 1 to 4, wherein u ₀ / u _mf (where u ₀ is the tower speed and u _mf is the minimum fluidization velocity of the powder). Dry separation method. The dry separation method according to any one of claims 1 to 7, wherein when blowing a plurality of powders, the blowing is performed at a value of a u ₀ / u _mf ratio such that the plurality of powders are uniformly mixed. The dry separation method according to any one of claims 1 to 8, wherein the apparent density of the gas-solid fluidized bed is set between the maximum density and the minimum density of the components in the separation object. The powder according to claim 1, wherein the powder has a density almost equal to unibeads®, glass beads, zirconsand, polystyrene particles, steel shots and the like. Dry separation method selected from the group consisting of powders having. The dry separation method according to any one of claims 1 to 10, wherein the object to be separated comprises waste, ore, crops, plastics, and metals. The dry separation method according to any one of claims 1 to 11, wherein the average particle diameter of the powder is 100 to 500 µm.