JP4012963B2 - Specific gravity separation method for particles - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、鉱業、各種産業分野の製造工程およびリサイクル工程等の各種産業分野に関し、特に懸濁液中の粒子の比重分離法に関し、特に沈降速度差を利用した粒子の比重分離における等速沈降比の拡大方法に関する。
【０００２】
【従来の技術】
比重の異なる２種以上の粒子に対し、水中での沈降速度差を利用して分離する装置（ジグ、テーブル、サイクロン等およびその改良装置）が産業分野の各所で利用されている。水中における粒子の沈降速度は、粒子の比重と粒径（投影断面積）の両方に依存することから、比重が大きく粒径が小さい粒子と、比重が小さく粒径が大きい粒子では、同じ速度で沈降するものが存在する。同速度で沈降する異比重粒子の粒径比を等速沈降比と呼ぶ。
【０００３】
沈降速度差を利用する全ての分離装置では、比重の大きな粒子（「高比重粒子」又は「重粒子」ともいう。）を下方に比重の小さな粒子（「低比重粒子」又は「軽粒子」ともいう。）を上方に集め分離を達成させるため、事前に等速沈降比内に粒度調整しなければ、軽粒子が下方に、あるいは重粒子が上方に混入して精度良く分離することができない。数ｍｍ〜数ｃｍ程度の粒子を分離する際には、比較的容易に粒度調整が可能であるが、数１００μｍ以下、特に５０μｍ以下の粒子を等速沈降比内に粒度調整することは、工業的には極めて困難である。
【０００４】
従来の微粒子用比重分離機は、遠心場を付与して粒子の沈降速度（移動速度）を増大させる仕組みが備わっているものが多い。しかし、遠心力は全ての粒子に同様に付与されるため、分離に要する時間の短縮はできるが、等速沈降比を変化させることはできない。したがって、従来技術では、特に多分散系（粒度幅の広い）微粒子の高精度な比重分離は不可能であった。
【０００５】
【発明が解決しようとする課題】
本発明は、沈降速度差を利用する比重分離方法において、比重分離前の粒度調整を不要、あるいはその負担を軽減するとともに、微粒子を比重分離する際の分離精度向上を可能にする異比重粒子の等速沈降比拡大法を実現する。
【０００６】
【課題を解決するための手段】
本発明は上記課題を解決するために、粒子の比重の大小による沈降速度差を利用し、高比重粒子と低比重粒子を比重分離する粒子の比重分離方法において、
粒子の沈降方向に振動を与え、粒子の比重、振動の周波数、振幅に応じて低比重粒子の沈降遅延を高比重粒子よりも大きくして、同速度で沈降する異比重粒子の粒径比である等速沈降比を拡大することを特徴とする粒子の比重分離方法を提供する。
【０００７】
本発明は上記課題を解決するために、粒子の比重の大小による沈降速度差を利用し、高比重粒子と低比重粒子を比重分離する粒子の比重分離方法において、粒子の沈降方向に振動を与え、レイノルズ数を０．１より大きくするとともに、粒子の比重、振動の周波数、振幅に応じて低比重粒子の沈降遅延を高比重粒子よりも大きくして、同速度で沈降する異比重粒子の粒径比である等速沈降比を拡大することを特徴とする粒子の比重分離方法を提供する。
【０００８】
上記異比重粒子を、拡大した等速沈降比の粒径の範囲に予め粒径を揃えることを特徴とする。
【０００９】
【発明の実施の形態】
本発明の実施の形態を実施例に基づいて図面を参照して以下説明する。まず、本発明の原理について説明する。種々の粒径を持つ高比重粒子と低比重粒子を水中に放つと、図１に示すように同じ粒径であれば高比重粒子が速く沈降し、同じ比重であれば粒径が大きい粒子が速く沈降する。これらの中には、異なる粒径を持つ高比重粒子と低比重粒子で同じ沈降速度を有するものが存在する。同一速度で沈降する高比重粒子の粒径Ａと、低比重粒子の粒径Ｂの比、Ｂ／Ａを等速沈降比と呼ぶ。
【００１０】
沈降速度差を利用した比重分離法は、原則として低比重粒子を上方で、高比重粒子を下方で回収する。図の点線を分離の境界と考えると、高比重粒子のうち粒径Ａより大きな物は、粒径Ａの粒子より沈降速度が速いためすべて下方で回収され、逆に軽比重粒子のうち粒径Ｂより小さな物は、粒径Ｂの粒子より沈降速度が遅いのですべて上方で回収される。
【００１１】
しかし、高比重粒子のうち粒径Ａより小さな径をもつ粒子ａは、低比重粒子とともに上方で回収されてしまい、同様に低比重粒子のうち粒径Ｂより大きな径をもつ粒子ｂは、高比重粒子とともに下方で回収されてしまうので、分離精度の低下を招く。
【００１２】
したがって、比重分離によって高比重粒子と低比重粒子に精度良く分離するためには、予め粒子群を粒径Ａ〜Ｂの範囲内に粒度調整しておかなければなければならい。言い換えれば、比重分離に供する粒子群の最大径と最小径の比を等速沈降比内に収めなければならない。すなわち、等速沈降比は、比重分離における適用粒度幅を意味する。
【００１３】
ところで、等速沈降比は、流体である水の流れの状態によってそれぞれ以下のような数式１及び数式２で表すことが一般化されている。
【００１４】
【数１】
【数２】
この数式１、２に従って考えると、比重４の粒子と比重２の粒子を水中で分離するとき、粒径１ｃｍの粒子は流れの状態がニュートン域となるので、等速沈降比は３となり、例えば粒径１〜３ｃｍの範囲に事前に粒度調整すればよく、これは容易に行うことが可能である。しかし、粒径２０μｍの粒子ではストークス域となり、等速沈降比は１．７３となる。
【００１７】
すなわち、この場合には例えば粒径２０〜３５μｍの範囲に粒度調整しければならず、工業的にこの範囲に粒度調整することは困難である。事実上５０μｍ以下の微粒子を高精度に分離することが不可能であった。このように微粒子の比重分離においては、等速沈降比を少しでも拡大することが分離精度の向上につながる。
【００１８】
一方、水中を沈降する１種の粒子に対し、鉛直方向に水を振動させると、図２に示すように、粒子の沈降速度の遅延が起きることは一般に知られている。本発明では、比重の異なる２種の粒子を同一の振動場に置いた際、粒径の大きな粒子の方が大きな流体抵抗を受け、粒径の小さな粒子に比べ沈降速度遅延の度合いが大となることを応用した方法である。その結果、静止流体中で等速度沈降する比重大・粒径小の粒子（重粒子）と比重小・粒径大の粒子（軽粒子）は、振動流体中では軽粒子の方が沈降速度の遅延が大きくなり、等速沈降比の拡大が起きる。
【００１９】
一方、流れの状態は、レイノルズ数によりニュートン域（レイノルズ数５００以上）、アレン域（レイノルズ数２〜５００）、ストークス域（レイノルズ数２以下）に分類される。従来の研究では、粒子が終末速度で沈降する際、粒子近傍の流体の流れがニュートン域に属するような、粒径数ｍｍ〜数ｃｍの粒子を対象とした沈降遅延しか検討されていない。さらに、レイノルズ数が小さくストークス域に属するような微粒子の沈降に対しては、沈降遅延がほとんど起きないとされてきた。
【００２０】
しかし、アレン域はもちろんのこと、微粒子に対して粒子沈降時のレイノルズ数が０．１を越えるような振動場におくといわゆるストークス域であるにもかかわらず、厳密にはストークスの式から僅かに逸脱するために沈降の遅延が起こる。
【００２１】
例えば、レイノルズ数が概ね０．２以上となるような振動（粒子の粒径、比重によるが、例えば、周波数５００Ｈｚ以上、振幅１００μｍ以上の正弦波あるいは方形波など。周波数を倍にすれば、振幅を半減させても概ね同様な振動場を与えることができる。）を水に与えると、いわゆるストークス域であるにもかかわらず、厳密にはストークスの式から僅かに逸脱するために沈降の遅延が起こる。
【００２２】
ニュートン域同様、重粒子に比べ軽粒子の方がこの遅延が大きくなるため、等速沈降比の拡大が起きる。等速沈降比拡大の度合いは、周波数、振幅の増大に伴う粒子近傍の流体のレイノルズ数増大とともに大きくなる。
【００２３】
本発明は、粒子の比重の大小による沈降速度差を利用し、高比重粒子と低比重粒子を比重分離する粒子の比重分離方法において、粒子の沈降方向に振動を与え、粒子の比重、振動の周波数、振幅に応じて低比重粒子の沈降遅延を重粒子よりも大きくして、同速度で沈降する異比重粒子の粒径比である等速沈降比を拡大することを特徴とする粒子の比重分離方法である。
【００２４】
この場合、粒子の沈降方向に振動を与え、レイノルズ数を少なくとも０．１より大きくする。このようにすると、予め等速沈降比の異比重粒子の異なる粒径の範囲を、広い範囲に揃え、広い範囲の粒径の粒子を比重分離の対象とすることができる。
【００２５】
要するに、本発明によれば、粒子の比重分離方法において、粒子の沈降方向に振動を与えることで、等速沈降比が拡大させて、粒子の比重分離を可能とする高比重粒子と低比重粒子の粒径比が大きくなるとともに、流れの状態がストークス領域となる微細な粒子領域の比重分離を可能とする、即ち粒子の比重分離方法において比重選別可能な対象粒径領域を広げることができる。
【００２６】
（実験）
これら等速沈降比拡大の検証は図３に示す実験装置により実施した。図３において、この実験装置１は、加振装置２と、加振装置２により加振されるガラスセル３と、測定処理装置４とを有する。
【００２７】
加振装置２は、徐振装置５と、徐振装置５の上に設けた加振機６とから成り、この加振機６により振動板７を介してガラスセル３内の水を上下方向に加振するものである。加振機６は、アンプ８を介してファンクションジェネレータ９に接続されている。
【００２８】
測定処理装置４は、ガラスセル３内に収容されている粒子の混合された水を拡大して検知し検知画像を撮影する顕微鏡１０（光学顕微鏡を利用する。）を備えた高速度カメラ１１と、高速度カメラ制御部１２と、高速度カメラ１１による画像信号を入力して粒子の挙動を測定するコンピュータ１３とから成る。さらに、高速度カメラ制御部１２は、モニター１４及びオシロスコープ１５に接続されている。
【００２９】
実験に際しては、ガラスセル３内に斜線部（半断面図で示す）のように水を満たし、ガラスセル３の上端の粒子投入部１６から、試料粒子の懸濁液を静かに投入する。ファンクションジェネレータ９により任意の周波数、振幅、波形の波を発生させ、これをアンプで増幅した後、その信号が加振機６に入力される。この信号に従って振動板７が上下に振動し、ガラスセル３内に満たされた水に振動場を生成させる。
【００３０】
水の振動場中を沈降する粒子の運動を、顕微鏡１０を介して高速度カメラ１１で撮影し、この撮影信号によって得られた撮像信号を制御用コンピュータ１３に入力して、粒子の沈降軌跡および沈降速度を測定する。
【００３１】
（実験例）
図４（ａ）（ｂ）に実験例の結果を示す。この実験例は、密度、粒度の異なる２種のガラスビーズ（懸濁液濃度０．１％）を、静止水中および周波数５００Ｈｚ、振幅１００μｍの正弦波振動した水中に投入した際の沈降軌跡を示したものである。
【００３２】
図４（ａ）（ｂ）に示す実験結果では、比重４．２と比重２．６の粒子では静止水中におけるストークス域の等速沈降比が１．４１であり、比重４．２、粒径２９．２μｍの重粒子に対しては、比重２．６、粒径４１．３μｍの軽粒子が等速で沈降する。
【００３３】
すなわち、粒径４１．３μｍ以上の軽粒子は、粒径２９．２μｍの重粒子より早く沈降するため、これらの混合粒子群を比重分離すると、これらはともに重粒子側（下方）に回収され静止水中では分離できない。
【００３４】
図４（ｂ）は、軽粒子として比重２．６、粒径４４．７μｍの粒子を用いた実験例であるが、この実験例の結果では、静止水中の沈降速度は１９１０μｍ／ｓとなり、重粒子の沈降速度１６４０μｍ／ｓよりも速く分離できないことを示している。
【００３５】
ここに振動場を与えると、粒子近傍の流体のレイノルズ数が大きくなり、ストークスの式から逸脱して沈降速度の遅延が起きる。このとき、粒径の大きな軽粒子の方がより大きな流体抵抗を受けるために、遅延の度合いも大きくなる。図の結果では、重粒子の沈降速度１４２０μｍ／ｓに対し、軽粒子は１２８０μｍ／ｓとなり、沈降速度の逆転が起きている。すなわち、静止水中では分離できない４４．７μｍの軽粒子が分離可能となることを示している。
【００３６】
この実験条件下で軽粒子が１４２０μｍ／ｓとなる粒径は４７．３μｍ程度と試算され、等速沈降比が１．４１から１．６２に拡大したことを意味する。この等速沈降比拡大は、振動の周波数が高く振幅が大きいほど、また分離対象の粒子の比重差が大きいほど顕著となる。また、水の変わりに他の粘性流体を用いても、その粘度に応じて静止流体中の沈降速度は異なるが、振動による等速沈降比の拡大は同様にして起きる。
【００３７】
以上、本発明の実施の形態を実施例に基づいて説明したが、本発明は特にこのような実施例に限定されることなく、特許請求の範囲記載の技術的事項の範囲内でいろいろな実施例があることは言うまでもない。
【００３８】
【発明の効果】
以上の構成である本発明によれば、従来型比重分離装置において、粒子の沈降方向に振動場を与えれば、粒子の比重、振動の周波数、振幅に応じて軽粒子の沈降遅延が重粒子よりも大きくなり、等速沈降比が拡大して、事前の粒度調整の負担を不要あるいは軽減することが可能である。
【００３９】
特に、これまで比重分離することが困難であった５０μｍ以下の多分散微粒子に対しては、事前に十分な粒度調整が行えなくとも、振動場による等速沈降比の拡大により分離精度を向上させることが可能となる。
【図面の簡単な説明】
【図１】比重分離による等速沈降比の概念を説明する図である。
【図２】振動水による等速沈降比の拡大の概念を説明する図である。
【図３】本発明を実証する実験装置を説明する図である。
【図４】本発明の実験結果の一例を説明する図である。
【符号の説明】
１ 実験装置
２ 加振装置
４ 測定処理装置
６ 加振機
１０ 顕微鏡
１１ 高速度カメラ
１６ 粒子投入部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to various industrial fields such as mining, manufacturing processes and recycling processes in various industrial fields, and more particularly to a specific gravity separation method of particles in suspension, and in particular, constant velocity sedimentation in specific gravity separation of particles using a difference in sedimentation speed. It relates to a method of expanding the ratio.
[0002]
[Prior art]
Devices for separating two or more kinds of particles having different specific gravities by utilizing the difference in sedimentation speed in water (jigs, tables, cyclones, etc., and improvement devices thereof) are used in various industrial fields. Since the sedimentation rate of particles in water depends on both the specific gravity and particle size (projected cross-sectional area) of particles, particles with a large specific gravity and a small particle size and particles with a small specific gravity and a large particle size have the same speed. There is something that settles. The particle size ratio of the different specific gravity particles that settle at the same speed is called the constant velocity sedimentation ratio.
[0003]
In all separation devices that use the difference in sedimentation speed, particles with a large specific gravity (also referred to as “high specific gravity particles” or “heavy particles”) are moved downward to particles with a small specific gravity (“low specific gravity particles” or “light particles”). If the particle size is not adjusted within the uniform sedimentation ratio in advance, the light particles cannot be separated accurately by mixing the light particles downward or the heavy particles upward. When separating particles of several millimeters to several centimeters, the particle size can be adjusted relatively easily. However, it is industrially possible to adjust the particle size of particles of several hundred μm or less, particularly 50 μm or less within a constant velocity sedimentation ratio. It is extremely difficult.
[0004]
Many conventional specific gravity separators for fine particles are provided with a mechanism for increasing the sedimentation speed (movement speed) of particles by applying a centrifugal field. However, since centrifugal force is similarly applied to all particles, the time required for separation can be shortened, but the constant velocity sedimentation ratio cannot be changed. Therefore, in the prior art, it is impossible to separate the specific gravity of polydisperse (wide particle size) fine particles with high accuracy.
[0005]
[Problems to be solved by the invention]
In the specific gravity separation method using the sedimentation speed difference, the present invention eliminates the need for particle size adjustment before specific gravity separation, or reduces the burden thereof, and enables the improvement of separation accuracy when separating fine particles with specific gravity. Realize constant velocity sedimentation ratio expansion method.
[0006]
[Means for Solving the Problems]
In order to solve the above problem, the present invention uses a difference in sedimentation speed due to the specific gravity of the particles, and in a specific gravity separation method for particles that separates high specific gravity particles and low specific gravity particles.
The particle size ratio of particles with different specific gravity that settles at the same speed by giving vibration in the sedimentation direction of the particles, and setting the sedimentation delay of the low specific gravity particles larger than that of the high specific gravity particles according to the specific gravity of the particles, frequency and amplitude of vibration. A specific gravity separation method for particles, which is characterized by enlarging a certain constant velocity sedimentation ratio.
[0007]
In order to solve the above-mentioned problems, the present invention uses a difference in sedimentation speed depending on the specific gravity of the particles, and in the specific gravity separation method for separating specific gravity of high specific gravity particles and low specific gravity particles, it gives vibration in the sedimentation direction of the particles. In addition, the Reynolds number is made larger than 0.1, and the settling delay of the low specific gravity particles is made larger than that of the high specific gravity particles according to the specific gravity, vibration frequency, and amplitude of the particles, so that particles of different specific gravity particles settled at the same speed. Provided is a particle specific gravity separation method characterized by expanding a constant velocity sedimentation ratio which is a diameter ratio.
[0008]
The different specific gravity particles are preliminarily arranged in a particle size range of an enlarged constant velocity sedimentation ratio.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings based on examples. First, the principle of the present invention will be described. When high specific gravity particles and low specific gravity particles having various particle sizes are released into water, as shown in FIG. 1, if the same particle size, the high specific gravity particles settle quickly, and if the same specific gravity, particles having a large particle size Settling fast. Among these, high specific gravity particles and low specific gravity particles having different particle diameters have the same settling velocity. The ratio of the particle size A of the high specific gravity particles that settle at the same speed and the particle size B of the low specific gravity particles, B / A, is called constant velocity sedimentation ratio.
[0010]
In the specific gravity separation method using the difference in settling velocity, in principle, low specific gravity particles are recovered at the upper side and high specific gravity particles are recovered at the lower side. Considering the dotted line in the figure as the boundary of separation, among the high specific gravity particles, those larger than the particle size A have a faster sedimentation speed than the particles of the particle size A, and are all recovered below. Anything smaller than B is recovered at the top because the sedimentation rate is slower than that of particles of particle size B.
[0011]
However, among the high specific gravity particles, the particles a having a diameter smaller than the particle size A are recovered together with the low specific gravity particles, and similarly, among the low specific gravity particles, the particles b having a diameter larger than the particle size B are high. Since the particles are collected together with the specific gravity particles, the separation accuracy is lowered.
[0012]
Therefore, in order to separate into high specific gravity particles and low specific gravity particles with high accuracy by specific gravity separation, it is necessary to adjust the particle size within the range of particle sizes A to B in advance. In other words, the ratio between the maximum diameter and the minimum diameter of the particle group subjected to specific gravity separation must fall within the constant velocity sedimentation ratio. That is, the constant velocity sedimentation ratio means an applied particle size width in specific gravity separation.
[0013]
By the way, it is generalized that the constant velocity sedimentation ratio is expressed by the following formulas 1 and 2 depending on the state of the flow of water as a fluid.
[0014]
[Expression 1]
[Expression 2]
When considering according to these formulas 1 and 2, when separating particles of specific gravity 4 and particles of specific gravity 2 in water, the flow rate of particles with a particle size of 1 cm is in the Newton region, so the constant velocity settling ratio is 3, The particle size may be adjusted in advance in the range of 1 to 3 cm, and this can be easily performed. However, a particle having a particle diameter of 20 μm has a Stokes region and a constant velocity sedimentation ratio of 1.73.
[0017]
That is, in this case, for example, the particle size must be adjusted in the range of 20 to 35 μm, and it is difficult to adjust the particle size in this range industrially. In fact, it was impossible to separate fine particles of 50 μm or less with high accuracy. Thus, in the specific gravity separation of fine particles, increasing the constant velocity sedimentation ratio as much as possible leads to an improvement in separation accuracy.
[0018]
On the other hand, it is generally known that when water is vibrated in the vertical direction with respect to one type of particle that settles in water, as shown in FIG. In the present invention, when two kinds of particles having different specific gravities are placed in the same vibration field, the particles having a larger particle size receive larger fluid resistance, and the degree of settling velocity delay is larger than that of the particles having a smaller particle size. This is an applied method. As a result, particles with a specific criticality / small particle size (heavy particles) and particles with a small specific gravity / large particle size (light particles) that settle at a constant velocity in a static fluid have a lower sedimentation velocity in the vibrating fluid. The delay increases and the constant velocity sedimentation ratio increases.
[0019]
On the other hand, the flow state is classified into a Newton region (Reynolds number of 500 or more), an Allen region (Reynolds number of 2 to 500), and a Stokes region (Reynolds number of 2 or less) according to the Reynolds number. In the conventional research, only sedimentation delay for particles having a particle diameter of several millimeters to several centimeters, in which the fluid flow in the vicinity of the particles belongs to the Newton region when the particles settle at the terminal velocity, has been examined. Furthermore, it has been assumed that the sedimentation delay hardly occurs for the sedimentation of fine particles having a small Reynolds number and belonging to the Stokes region.
[0020]
However, not only in the Allen region, but in a vibration field in which the Reynolds number at the time of particle settling exceeds 0.1 for a fine particle, although it is a so-called Stokes region, strictly speaking, it is slightly from the Stokes equation. Slowing of sedimentation occurs due to deviation from
[0021]
For example, vibration that causes the Reynolds number to be approximately 0.2 or more (depending on the particle size and specific gravity of the particle, for example, a sine wave or a square wave having a frequency of 500 Hz or more and an amplitude of 100 μm or more. If the frequency is doubled, the amplitude Can be given approximately the same vibration field even if it is halved.) When water is applied to the water, the settling delay is caused by a slight deviation from the Stokes equation, despite the so-called Stokes region. Occur.
[0022]
As with the Newton region, this delay is greater for light particles than for heavy particles, resulting in an increase in the constant velocity sedimentation ratio. The degree of expansion of the constant velocity sedimentation ratio increases as the Reynolds number of the fluid in the vicinity of the particles increases as the frequency and amplitude increase.
[0023]
The present invention uses a difference in sedimentation speed depending on the specific gravity of the particles, and in a specific gravity separation method for separating specific gravity of high specific gravity particles and low specific gravity particles. The specific gravity of particles is characterized in that the settling delay of low specific gravity particles is made larger than that of heavy particles according to frequency and amplitude, and the constant velocity settling ratio, which is the particle size ratio of different specific gravity particles that settle at the same speed, is expanded. Separation method.
[0024]
In this case, vibration is applied in the sedimentation direction of the particles so that the Reynolds number is at least greater than 0.1. In this way, the range of different particle diameters of the different specific gravity particles having the constant velocity sedimentation ratio can be set in a wide range, and particles having a wide range of particle diameters can be targeted for specific gravity separation.
[0025]
In short, according to the present invention, in the specific gravity separation method of particles, by giving vibration in the sedimentation direction of the particles, the constant velocity sedimentation ratio is expanded, and the high specific gravity particles and the low specific gravity particles that enable the specific gravity separation of the particles. The particle size ratio of the particles can be increased, and the specific particle size separation can be performed in the fine particle region in which the flow state becomes the Stokes region.
[0026]
(Experiment)
The verification of the expansion of the constant velocity sedimentation ratio was carried out using the experimental apparatus shown in FIG. In FIG. 3, the experimental device 1 includes a vibration device 2, a glass cell 3 that is vibrated by the vibration device 2, and a measurement processing device 4.
[0027]
The vibration device 2 includes a slow vibration device 5 and a vibration device 6 provided on the slow vibration device 5, and water in the glass cell 3 is vertically moved by the vibration device 6 via the vibration plate 7. Is to vibrate. The vibration exciter 6 is connected to a function generator 9 via an amplifier 8.
[0028]
The measurement processing device 4 includes a high-speed camera 11 including a microscope 10 (using an optical microscope) that magnifies and detects water mixed with particles contained in the glass cell 3 and captures a detection image. The high-speed camera control unit 12 and the computer 13 that inputs the image signal from the high-speed camera 11 and measures the behavior of the particles. Further, the high speed camera control unit 12 is connected to a monitor 14 and an oscilloscope 15.
[0029]
In the experiment, the glass cell 3 is filled with water as indicated by a hatched portion (shown in a half-sectional view), and a suspension of sample particles is gently introduced from the particle introduction unit 16 at the upper end of the glass cell 3. The function generator 9 generates a wave having an arbitrary frequency, amplitude, and waveform, and amplifies this with an amplifier, and then the signal is input to the vibrator 6. In accordance with this signal, the diaphragm 7 vibrates up and down, generating a vibration field in the water filled in the glass cell 3.
[0030]
The motion of the particles that settle in the vibration field of water is photographed by the high-speed camera 11 through the microscope 10, and the imaging signal obtained by this photographing signal is input to the control computer 13, and the sedimentation trajectory of the particles and Measure the sedimentation rate.
[0031]
(Experimental example)
The result of an experimental example is shown to Fig.4 (a) (b). This experimental example shows the sedimentation trajectory when two types of glass beads of different density and particle size (suspension concentration 0.1%) are thrown into still water and water with a frequency of 500 Hz and an amplitude of 100 μm and sine wave vibration. It is a thing.
[0032]
In the experimental results shown in FIGS. 4 (a) and 4 (b), particles having a specific gravity of 4.2 and a specific gravity of 2.6 have a constant velocity sedimentation ratio of 1.41 in the Stokes region in still water, a specific gravity of 4.2, a particle size of For heavy particles of 29.2 μm, light particles with a specific gravity of 2.6 and a particle size of 41.3 μm settle at a constant speed.
[0033]
That is, since light particles having a particle size of 41.3 μm or more settle faster than heavy particles having a particle size of 29.2 μm, when these mixed particle groups are separated by specific gravity, they are both recovered and stationary on the heavy particle side (downward). It cannot be separated underwater.
[0034]
FIG. 4 (b) is an experimental example using particles having a specific gravity of 2.6 and a particle size of 44.7 μm as light particles. According to the results of this experimental example, the sedimentation speed in still water is 1910 μm / s, It indicates that the particles cannot be separated faster than the sedimentation rate of 1640 μm / s.
[0035]
When an oscillating field is applied here, the Reynolds number of the fluid in the vicinity of the particles increases, and the settling velocity is delayed by deviating from the Stokes equation. At this time, since the light particles having a larger particle size receive larger fluid resistance, the degree of delay also increases. In the results shown in the figure, the sedimentation speed of heavy particles is 1420 μm / s, whereas the light particles are 1280 μm / s, and the sedimentation speed is reversed. That is, it shows that 44.7 μm light particles that cannot be separated in still water can be separated.
[0036]
Under these experimental conditions, the particle size at which the light particles are 1420 μm / s was estimated to be about 47.3 μm, which means that the constant velocity sedimentation ratio was expanded from 1.41 to 1.62. The expansion of the constant velocity sedimentation ratio becomes more remarkable as the vibration frequency is higher and the amplitude is larger, and the specific gravity difference of the particles to be separated is larger. Even if another viscous fluid is used instead of water, the settling velocity in the static fluid varies depending on the viscosity, but the constant velocity settling ratio is increased in the same manner by vibration.
[0037]
The embodiments of the present invention have been described based on the examples. However, the present invention is not particularly limited to such examples, and various implementations are possible within the scope of the technical matters described in the claims. It goes without saying that there are examples.
[0038]
【The invention's effect】
According to the present invention having the above-described configuration, in a conventional specific gravity separator, if a vibration field is applied in the sedimentation direction of particles, the sedimentation delay of light particles is greater than that of heavy particles according to the specific gravity of the particles, the frequency of vibration, and the amplitude. As a result, the constant velocity sedimentation ratio is increased, and the burden of prior particle size adjustment can be eliminated or reduced.
[0039]
In particular, for polydisperse particles of 50 μm or less, which has been difficult to separate with specific gravity until now, the separation accuracy is improved by expanding the constant velocity sedimentation ratio by the vibration field, even if the particle size cannot be adjusted sufficiently in advance. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the concept of constant velocity sedimentation ratio by specific gravity separation.
FIG. 2 is a diagram for explaining the concept of expansion of a constant velocity sedimentation ratio by vibrating water.
FIG. 3 is a diagram for explaining an experimental apparatus for demonstrating the present invention.
FIG. 4 is a diagram illustrating an example of an experimental result of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Experimental apparatus 2 Excitation apparatus 4 Measurement processing apparatus 6 Exciter 10 Microscope 11 High speed camera 16 Particle injection part
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| JP4803426B2 (en) * | 2005-02-02 | 2011-10-26 | 独立行政法人産業技術総合研究所 | Particle separator |
| JP4817330B2 (en) | 2006-07-25 | 2011-11-16 | 独立行政法人産業技術総合研究所 | Particle separation method |
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| DE102008005063A1 (en) | 2007-07-13 | 2009-01-15 | National Institute Of Advanced Industrial Science And Technology | Particle e.g. jigs, separation apparatus for use in e.g. mining industry, has particle supply cylinders with valve for discharging particles in suspension towards centrifugation vessel filled beforehand with water |
| JP2016176802A (en) * | 2015-03-19 | 2016-10-06 | 株式会社クレハ | Methods for recovering metallic foreign matter and for inspecting metallic foreign matter of polymer |
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