DE2152407A1 - Method and device for separating particles by means of a cyclone - Google Patents

Description

PATENT ADVOCATE

6 Frc ■: - '., - cir 70

Slug;":.,;:.!. ; .. · - Td. Ol / 079

October 12, 1: 371 Gzte / pn

UNIOiT CARBIDE CORPORATION, 270 Park Avenue, New York,

N.Y. 10017 / U.S.A.

Method and apparatus for separating particles by means of a cyclone

The invention relates to a method and a cyclone zur.i Separating or classifying broken and / or ground material in a liquid medium into individual mixtures (Dispersions) of fine and coarse particles, the density (concentration, solids content) of the dispersion with the fine particles can be changed without changing the density of the source liquid * In addition measures are provided to ensure a constant feed rate of the liquid to the cyclone.

Tests have shown that cyclones are used effectively |

can be made to different types of crushed or ground material in two / ei fractions of different Separate or classify particle size. The centripetal and centrifugal forces occurring in a cyclone are used to separate the particles of the material, forcing the larger or coarser particles, move to the outer periphery of the cyclone while forcing the smaller or finer particles, to move in the axial area of the cyclone. The fine and coarse particles can be selected from the axial range or the Circumferential area can be discharged, whereby one obtains a separation of the applied material according to the particle size.

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The "Particle Size Separation" refers to the physical size of a particle that - if it is subjected to centripetal forces and centrifugal forces in is exposed to a cyclone - by equal forces either to the axial area or the circumferential area of the Cyclone is transported. This differentiation according to the particle size is important if the axially discharged material, the so-called overflow or overflow, all in one subsequent process or the like * should be used, where the particle size in the overflow is decisive. That Materia discharged at the circumference], the so-called undercurrent or the underflow, contains the particles whose size is equal to or larger than the particle separation size.

The dimension of the separation according to particle size depends on numerous variable parameters, such as the feed density (Concentration), the inlet pressure, the particle size in the task and the specific capacity of the cyclone used.

It has been shown that with an increase in the feed density, the separation size increases and the solids content in percent by weight of the overflow and the underflow increases. This is primarily due to the fact that with the increased density of the fed material, the buoyancy force inside the cyclone increases, as a result of which heavier coarse particles are moved into the axial area, where they are carried away in the overflow. Those particles that are too coarse are moved into the circumferential area and carried away as an undercurrent. The disadvantage of increasing the feed density is that the separation increases according to the particle size, which leads to a particle distribution which is not as desirable as that obtained with a lower feed density.

The inlet pressure affects the performance of the cyclone and the particle breakdown size), so that when the inlet pressure increases

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BATH

the efficiency of the cyclone is greatly improved and the toilet failure size is increased. The particles are large in the task influences the solids content of the overflow and the underflow, so that by increasing the particle size of the task, the density of the overflow decreases, v / eil the coarser or larger particles are reduced as a result of the greater centrifugal forces in the overflow, while the density of the undercurrence is increased.

Two alternative methods of increasing the density of the material released in the overflow today are to: to increase the feed density or a thickener |

to add to the overflow. The former method leads to insufficient classification in the cyclone, while the latter method requires a large capital outlay on the equipment required to thicken the overflow requires; in some cases, the material being classified cannot be thickened effectively.

The present invention provides an apparatus and a method for separating or classifying a liquid particle dispersion into two components of different particle size by using a cyclone created, whereby the density of the overflow containing the finer particles can be increased without the I

Change the density of the abandoned material or add a thickener. In addition, measures are created to ensure a relatively constant feed to the cyclone.

The invention relates to a method and an apparatus for separating particles of a crushed or ground Material, wherein the material centripetal forces and centrifugal forces within a substantially closed cylindrical area is exposed and then the dispersions from the axial area and the

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Circumferential area and ore zone in different directions. Hin part of a · the discharged dispersion is then zurückge'führ in the zone b to the density of the discharged from üeiii axial Boreich dispersion to about 25 to about 40 weight percent regulate solids, v obei this dispersion contains / the fraction of fine particles. For example, a classifying alloy can be used which is equipped with a return connection between the overflow delivery line and the feed line; then some of the overflow could be split back into the task. The recirculated part of the material discharged as overflow contains particles whose average size is smaller or which are less coarse than the feed material, so that the total mixture of the two results in an average particle size which is even smaller than that of the particles in the originally fed material . Thus, for certain specified operating conditions, the dispersion with the particles of smaller average size after being fed into the cyclone will result in an overflow discharge, the density of which is higher than that which can be obtained without recirculating a fraction of the overflow that is obtained with the original feed material is mixed. This is due to the fact that there are now more particles that are smaller than the "particle separation size", so that more particles are released into the overflow. The density (concentration) of the overflow is increased in this way without the classification efficiency of the cyclone being adversely affected.

In a reverse process to reduce the density After the overflow, part of the underflow can be circulated back into the feed material. The average Particle size in the underflow is larger than the average particle size in the task,

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ORIGINAL

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and a III see of the two leads to a submission material, that contains more particles that are larger than the "particle separation size". This leads to a decrease in "density" the overflow and an increase in the density of the underflow. So the density of the overflow can be increased or reduced v / ground by part of the as overflow or of the material discharged as an undercurrent is returned.

The return measures of the classifying cyclone can also do this serve to ensure an adequate supply of the feed material on "

Maintain inlet of the cyclone. This is achieved by using a level sensor or the like in a collecting container connected to the feed line of the cyclone connected is. When the level of the material to be fed to the cyclone in the sump is at a predetermined height drops below which the material would not be sufficient to maintain the desired flow into the cyclone the level sensor provides a signal that can be used to determine the flow of the recirculated part of the overflow and / or to regulate the underflow. In this way, the recycle percentage can be increased to match the level of the material in the To increase the collection container, thereby increasing the continuity of the (|

desired feed flow is achieved; this flow is related to the efficient operation of the cyclone

Examples of materials that can be classified according to this invention are scheelite, molybdenum ores, copper ores and other non-metallic or non-ferrous ores. In principle, any material can be classified according to this invention, which has particles of different sizes in a liquid.

In the drawing is schematically a method for classifying or separating particles of a crushed or ground Material shown according to the egg 'finding.

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In the drawing is a cyclone 1 with an overflow discharge line 2, a task line 3 and an undertone output line 4 shown. The overflow discharge line 2 divides into a discharge line 5, the at 6 a flotation process, and a second discharge line 7, whose. Discharge amount through a valve 8 control and is adjustable to return part of the overflow to lead into a collecting container 9 via a line 10. The underflow from the line 4 is in a discharge line 19 and a discharge line 20 split; the delivery rate of the latter can be controlled and regulated by a valve 13, by a part of the underflow via a line 21 back to be drawn off / own in the collecting container 9. A liquid level sensor 11 is arranged so that it generates a signal to the valves 8 and / or 13 via the lines 22 and / or 23 to operate when the level of the liquid in the collecting container 9 falls below a predetermined height. A Density meter 12 is arranged in the path of the discharge line 5 to measure the density (concentration) there and display; it is connected to a power device (not shown) which generates a signal to either to actuate the valve 8 or the valve 13 via the line 24 or 25 if the density is greater than or less than becomes a predetermined range. Crushed or milled ™ material with unclassified particle sizes is used by the Feed point 15 brought via a line 14 into the collecting container 9, where it is with a liquid such as V / water is mixed by the supply device 16 via a line 17. The discharged from the collecting container 9 Material is fed to the feed line 3 via a pump 18.

During operation, unclassified material is brought into the collecting container, where it is mixed with a liquid, for example V / water, is mixed; then the mixture is pumped into the cyclone at a desired flow; this flow depends primarily

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on the efficiency of the cyclone used.

The unclassified niche then "becomes" centripetal forces and centrifugal forces within the cyclone, the clie particles of the mixture separate, with the finer ones or smaller particles migrate to the area of the central axis of the cyclone, while the coarser or collect larger particles at the periphery of the cyclone.

The fine particles, i.e. those that are equal to or smaller than the "particle separation size" are then released into the overflow, while the coarse Teilchon, or parts that are equal to or greater than t the "particle separation size", given into the undersurface

will »The" Partial Client Separation Size "is a function the on c.a poetry, and the task density is an inverse one Function of the cyclone efficiency.

The material released as overflow is over the Line 2 fed to a lotation process in order to there to be used accordingly. The density meter 12 measures the density (concentration) in the overflow, when a certain density range is required for a particular flotation process; when the measured If the density is outside this range, the densitometer generates a signal via a conventional power input " direction to open valve 8 or 13, depending on whether the density is below or above the required density range lies. If the measured density is less than the required density, the valve 8 is opened to to divert part of the overflow back into the collecting tank. This will make the average particle size decreased in the collection container; by maintaining constant pressure and flow at the inlet, the Overflow density increased. This return procedure makes increasing the input density of the abandoned material and adding a thickener Overflow, if their density is to be increased, superfluous. 209819/0611

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Venn the measured density in the Überstronmng ege bonen above a * before ^ range, is generated in a similar ßicnal V.'eise a Dichtemossor by the 12th to operate the valve 13 so that part of the Unterßtrönjuni-; is diverted back into the collecting container 9. This increases the average particle size in the waste container and decreases the density of the overflow while increasing the density of the underflow. An automatic system is thus created for maintaining an essentially constant overflow density,

In order to have a constant supply of material in the collecting container S to maintain a level sensor 11 is used, a signal to actuate the valves 8 and / or 13 to generate when the level in the sump falls below a loan, below which the sump pump 18 is no longer adequately supplied with the amount required to achieve the desired pressure and to maintain the flow at the feed point. The valves direct part of the overflow and / or underflow into the collecting container, so that a level v / ird maintained in the collecting container, which maintains a sufficient flow at the feed point. If the density of the overflow changes during the actuation of the valves 8 and / or 13 by the level sensor 11, then the signal generated by the densitometer helps either valve 3 or valve 13 to continue to close open to regulate the overflow density to the area that is desired at this point in time.

The level sensor or densitometer can be used independently if desired; when the densimeter is used, it may be advantageous to use only one of the valves to control part of the overflow or branch off the undercurrent back into the pick-up line.

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Ks is also i: H'j [xl ± oli _for individual cylinders in parallel or in a row behind, so that a greater capacity is achieved by material with different particle sizes About flow from a harvest cyclone s: ur on Gaber location of a second, related cyclone diverted v / ground to the Überströmdiel) to the latter · ζ \ ι control since its' ubcrströiadichte a function of the size distribution is its discontinued material, regardless of where this comes from.

example

A 25.4 cm (10 inch) cyclone was used to classify scheelite (calcium volframate) for use was required in a flotation process. the The feed density required for the flotation process was included

34 weight percent solids content, so that the flotation hold time of the process could be kept at about 9 minutes. The inlet pressure of the cyclone was at 0.35 atm (5 psig) is set to λ erect a task flow rate of 6,810 liters (1,800 gallons) per minute for the unsorted mixed with water scheelite

obtain; the scheelite was supplied by a common grinder. A measurement of the overflow was made, to determine their density; it was found to be 30 percent by weight of solid material and was thus lower than the density required for the flotation process. Some of the overflow, about 35%, became that Task of cyclone returned; a second density determination at the overflow outlet gave a density of

35 weight percent solids. By regulating the recirculated portion of the overflow to about 30 to 35 ^f / o, the density of the overflow was maintained at about 34 weight percent solids as required for the

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Flotationspi-ozosrj was required. The density of eggs over- flow VrurdG thus cvhöht and in eincia Area geluiifccn without; that the thieves are there containing mixture was increased and without the need to add a fatty substance to the overflow Yv \ 'ir.

The example on the label serves only to explain the Invention; Modifications of the invention are possible in a wide range.

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Claims (8)

Pa t ο η to η .--: ρ r ü eh ο 1. Process for separating particles in a liquid into separate dispersions with linen and sample particles, characterized by the process steps: a) supplying the liquid g containing the particles at a substantially constant flow from a supply point to an area of influence of centripetal forces and centrifugal forces within a substantially enclosed zone to cause the gi * above particle fraction to move to the peripheral area of the zone during the fine particle fraction moves into the axial area of the zone, b) removing part of the dispersion in the axial area of the zone in one direction, c) Release of the part of the dispersion at the peripheral area the zone in a direction different from the Λ Direction coincides in process step b), and d) branching off some of the discharged in at least one of method steps b) and c) Disperse back into the zone until the density (concentration) of the discharge from the axial area of the zone lies in a preselected area. 2. The method according to claim 1, characterized in that in process step d) the density of the dispensed Dispersion is between about 25 and about 40 weight percent solids. 209819 / 061Ί ■ - 12 - SAD ORfGfNAL 2157407 - j. .j ~ 3. Method n-ch -vnspruch 1, characterized in that after the;] procedural steps; d) the following procedural step inserted v / i vü; e) branching off a toilet dor box at least one of procedural steps b) and c) submitted Dispersion back into the utility when the level of fluid in the utility drops below a level that is necessary to ensure a substantially constant flow of the liquid into the closed Maintain zone. 4. The method according to claim I, characterized in that the material to be classified is made of scheelite, Molybdenum ores or copper ores. 5. The method according to claim 1, characterized in that the material to be classified is scheelite and the density of the delivery from the axial portion of the zone at approximately 34 weight percent solids lies. 6. Apparatus for separating particles in a liquid with a cyclone having an input supply line from a supply sump, an overflow discharge line and an underflow discharge line, characterized in that at least one return connection between the overflow discharge line or the underflow output line and the input supply line is established. 7. Apparatus according to claim 6, characterized by at least one valve actuated by a signal in at least one of the delivery lines, a density meter in the overflow discharge line which can generate a signal when the measured density of the 209819/061 1 - 13 - SAD ~ 13 ~ Über.st'roiirangsabr, 'r.ibe deviates from an adjustable predetermined range, and a device xv.r feeds this signal from the Diehteinesser to your valve in order to operate the valve, and thereby άοη part of the Abgabeströi.ning · of at least to regulate a discharge line back into the feed line if the measured density in the overflow discharge line deviates from a predetermined range. 8. The device according to claim 6, characterized by a liquid level sensor which can generate a signal, v / if the level of the liquid dispersion in the supply device at the entrance falls below a predetermined one Height drops, an at least signal-operated valve device in at least one of the delivery lines is arranged, and means for supplying the signal from the liquid level sensor to the valve means, to actuate the valve device and thereby the portion of the discharge flow of at least one Dispense line back to regulate the delivery line when the level of liquid dispersion in the supply device drops below a predetermined level at the entrance, which is essentially necessary, to maintain a constant inlet flow into the cyclone. 9, device according to claim 8, characterized by a density meter in the overflow discharge line, the can generate a signal when the measured density of the . Overflow delivery deviates from an adjustable predetermined range, a device for supplying the ■ Signal from the densitometer to the valve device to actuate the valve device and thereby the To regulate part of the discharge flow from at least one discharge line back into the feed line if the measured Density in the overflow delivery line deviates from the specified range. 209819/0611 BATH ORIGINAL Blank page