FI105212B - Flotation equipment and method for cleaning ink and inks - Google Patents

Abstract

The invention relates to flotation apparatus and a method of deinking furnish free from ink and colour pigment particles, said apparatus comprising at least one flotation cell with a piping connected thereto for feeding a furnish flow into said cell to the end of separating the clean furnish from froth. An essential property of the invention is therein that the piping (2) is provided with a restriction (3) incorporating an air feed means (4) for efficient mixing of air bubbles in the furnish and that said cell (1) has a separation space (6) combined with a discharge space (7) for the discharge of the clean furnish flow and a means (8) for removing the froth in the fresh state from the separation space (6).

Description

105212

FLOTATING EQUIPMENT AND METHOD FOR PRINTING INK AND INK

The present invention relates to a flotation apparatus according to the preamble of claim 1 and to a method for deinking ink and inks.

The utilization rates of recycled paper in papermaking processes are increasing both in terms of volume and as a proportion in different product groups. This places ever increasing demands on the quality and treatment technology of recycled paper. In particular, de-inking and flotation removal of ink, inks and other impurities have been the subject of research to achieve a more selective chemical separation.

In device technology, advances have led to the application of pressurized methods, mainly vortex cleaners. The development of non-pressurized equipment has been in place. However, the requirements for developing exactly non-pressurized equipment are high. Better control of physical quantities would provide a significant advantage in managing increasingly complex separation chemistry. With the trend toward ever higher scrap paper grades, for example in increasingly demanding paper grades, selectivity for impurities and fillers, as well as fiber and filler yields, will be key issues in process control and economy. In this sense, the present flotation plants represent a waste of filler and fiber material and a growing waste problem that is not much facilitated by incineration of abandoned material. Also, their controllability becomes more and more difficult as the filler volume is increasingly hampered by non-selective ink removal.

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The inventive features of a non-pressurized flotation apparatus operating in relation to atmospheric pressure relate, in particular, to air supply, separation mode of the main fiber stream and ink foam stream, fresh foam removal and countercurrent circulation from one cell to another. The structural factors of the apparatus enhance the selectivity and the flow dynamics yielding the yield. The features of the apparatus and method of the invention are set forth in the claims.

Prior art solutions, the most common of which are rotor-based methods for mineralogical applications for this purpose, have not sought to precisely regulate the amount of air, but only its adequacy. This has resulted in unfavorable fiber suspension-to-air ratio and de-selectivity as well as high reject due to excess air.

Prior art in the art is described in AT-342 528, in which air is introduced into the center, at the narrowest point by an air intake duct. DE 3144 386.0 and DE 3120 202.0 disclose the air supply through air supply pipes placed at the point of contraction or before or after the point of contraction and how the air supply and contractions can be mounted in one of the circulating conduits from the cell.

In the above publications, the mass flow in the cell is arranged by rotation of the vessel to rotate horizontally around the cell. In the embodiment of 6B 2 130 920, the circulation and air supply pipe are mounted in a cell where the mass rotates] *: ·. around a vertical axis.

The mechanical de-foaming method as disclosed in DE 3120 202 C2 does not remove the foam when fresh, since the foam has time to re-mix with the pulp and quench before the pulp that is being introduced reaches the discharge roll.

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Compared to the publication, the invention discloses a method in which the movement of air bubbles continues upward, differing from the mass flow, so-called. where the fresh foam that has come to the surface is immediately scraped off is much more selective. It is also easier to adjust the surface, since it can be kept constant in the cell regardless of the mass flow. Another way is to use the space provided by the separation space to build the scraper height to be adjustable to the liquid level.

The disadvantages of the solutions used in the past are that they are not aimed at bubble size and air volume control, but only at air volume adequacy. This provides a defective air-fiber suspension at the time of contact air supply, increasing the likelihood of air bubble collision and rendering the bubble size unfavorable.

According to the prior art, the reject has been removed as an overcapacity or introduced into the mass flow outlet roller without the separation of the mass flow and the foam and their different flow motion. In this way, the foam goes out and mixes with the mass, increasing the reject and making it difficult to adjust the cell surface.

The basic idea of the invention is preferably a symmetrical tube injection with an air supply hole providing the right bubble size at its narrowest point. The size of the holes determines the size of the bubble. With the narrowest point, the contact between the mass and the air bubble is maximized. Due to the acceleration provided by the contraction to the mass-air mixture, the air bubbles do not collide with each other, but remain optimally sized for longer fiber lengths. As it expands, the mass is mixed so that the contact is not too long and the bubble lift is sufficient for the collector-ink particle micelles.

The air supply device according to the invention can be expanded by adding the supply holes several times the dimensions (tube diameter, length of the constriction and extension part, tube diameter at the air supply point).

By applying the invention to both the feed stream to the cell and the flow from one cell to the other (both downstream and upstream) by means of a manifold and by combining the method for rapid foam removal immediately after its creation, the air volume in each part of the flotation cell can be adjusted. Due to its quick removal, the foam has no time to degrade or mix into the pulp stock. A further advantage of the manifold is that its installation makes the mixing and flow directions of the supply and circulation currents desired and the amount of air distributed evenly throughout the cell.

The use of the chemicals used can be optimized by dividing their feed in terms of feed and circulation currents as in air supply.

The defoamer roll is constructed to be height-adjustable to the level of the cellular water. Another way is to regulate the cell water surface with currents. The possibility of both modes increases the control of the separation mode and the control of the process.

i.i In particularly difficult process control situations, the number of contacts can be further increased by applying the invention: Y: to the internal circulation of the cell. Here, selectivity and foam control are obtained by increasing the surface height and increasing the separation space.

The invention will be described below. more specifically ".Y. with reference to the accompanying drawings, in which:

Figure 1 shows an air supply / actuator according to the invention

Figure 2 illustrates preferred air supply aperture applications of the air supply apparatus of Figure 1

Figure 3 illustrates, in principle, a back view of an apparatus in accordance with an embodiment of the invention

The air supply device according to the invention is shown in Figure 1. The purpose of the device is to supply air to a pulverized waste paper chemical water to remove ink therefrom in a flotation cell.

The air is preferably supplied perpendicular to the mass flow at the narrowest point of the tube contraction (3). The air inlet (4) is preferably a circular hole having a diameter of about 0.3 to 1.0 mm. The upper limit of the opening diameter is set by the fiber length, which the collection fibers can have <1 mm.

By adjusting the pressure and the flow rate, the amount of foam generated in the flotation cell (1) can be influenced ... through chemical economy and flotation efficiency, and

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selectivity of ink removal. The air inlet (4) determines the size of the bubble. Its distribution is not affected much by the amount of air and pressure. At the narrowest point (3) of the contraction • · i.i: when positioned, the air supply does not in principle require any pressure,., * · As the device is self-suctioned due to vacuum.

: Y: In practice, the amount of air supplied is often controlled by pressure.

The reducer (3) and expansion cones (10) are preferably identical. The ratio of the diameter of the tube to the length of the cones to the width (diameter) of the narrowest point is preferably 5: 10; 1. Dimensions can be multiplied eg by double, \. triple or quadruple by adding air inlets: /; "(4) (angles 180 °, 120 ° or 90 °), as shown in Fig. 2.

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The cone extension (10) gives the pulp a high velocity to prevent air bubble collisions with one another and, on the other hand, effectively mixes the pulp.

By installing a feeder from one suspension cell to another transfer pipeline, the contact between the air and the pulp to be cleaned can be further improved and the amount of air adjusted as desired.

The basic operation diagram of the apparatus is shown in Figure 3. The apparatus consists of one or more cells (1), (11). The cells are in free contact with each other and their liquid surfaces are aligned. The flow rate of the pulp stock is laminar.

The stock goes from one cell to another in a so-called. via the transmission channel (5). Pumping from the transfer channel also arranges the circulation of the stock from one cell to another upstream. The rotation current at the feed angle and point causes the stock to rotate in the cell in the desired direction of rotation.

The air is supplied by the nozzles to a circulating flow through the distribution manifold. The circulating current is pumped from one cell to another upstream (9).

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Immediately after birth, ink is removed mechanically by means of rollers: Y: (8) on the liquid surface of the cells.

By providing sufficient separation space (6) between the mechanical ink removal device and the horizontal mass flow, the apparatus provides different directions of flow between the ink particles adhering to the air bubbles and the pulp block and **. . thus selective separation. The air is supplied by the air supply device (4) of the invention, either to the feed stream or to the circulating stream (9). The mass-air suspension is obtained from the cell *. (1) with the supply current to circulate as desired. The mass flow enters the exhaust state (7). The separation space (6) and the foam • · 7 105212 fresh outlet (8) and the rise of the air perpendicular to the mass flow provide the selectivity of the equipment. The discharge spout is pumped into the pulp or it flows either to the circulating flow (9) or through the transfer channel (5), e.g. to the next cell (11). The air supply (4) can be arranged in the supply stream and / or in the circulating pump (9), which is pumped upstream by means of a manifold. The foam is removed with fresh rollers (8). The cells are in free communication with each other via an outlet (7) through a transport channel (5). Circulating currents are pumped out of the outlet spaces. The outlet (12) can be used to adjust the delay of the pulp block in the honeycomb.

The above-mentioned flotation apparatus and the method attached thereto allow for better air-fiber suspension contact and better separation in the ascending state, which further increases the productivity of the deinking equipment. By the method of the invention, the consistency can even be doubled from that known. At high filler distances, the distances between the fibers decrease beyond the critical limit, after which the ink no longer selectively separates even in the ascent state. The estimated operational consistency achieved with the factory-sized device of the invention «· 4« is thus in the range of 1.0 to 1.6%, most preferably 1.2 to 1.4%.

Laboratory tests have shown that the de-inking process in accordance with the invention is accelerated by 12 min ---> 5 min in the same final brightness compared to a rotor-fed air supply cell. .

Rejections decreased by 80-90%.

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Insufficient air-fiber suspension due to contact and inappropriate separation of bubbles, bubble size and, in part, foam: Due to this, the reject increases significantly in an attempt to increase the operational consistency of ·: · '· earlier solutions. It remains at 0.9-1.1%. In laboratory cells, the sensible range of the rotor simulator is 0.5-0.8%. The inventive laboratory apparatus achieves a consistency range of 1.0 to 1.2% and simultaneously reduces the rejection by 80 to 90%. Thus, with the plant-scale device according to the invention, a considerable yield gain can be achieved already at the same operating consistency. If the consistency can be further increased to a computationally achievable 1.2 - 1.4%, the yield of the apparatus according to the invention will be considerably higher.

The advantages of the invention are as follows: - The amount of air is adjustable. The air supply (4) is supplied perpendicular to the mass flow at the narrowest point of the condenser.

- The amount of foam can be adjusted by adjusting the air pressure and the flow rate.

- The correct bubble size will be optimized for the air inlet dimensions.

The air-fiber pulp contact is higher than in previous solutions. When fed to the narrowest (3) position .., the air contact surface with respect to the mass flow is greatest.

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: · - Introduced at the point of contraction, air bubbles do not collide 114 · * 'due to the acceleration of the mass. The expansion (10) after the point of introduction of the air gives the pulp-in-air suspension - ·. · A sufficient acceleration to allow the air bubbles //. ' don't immediately get bigger. At the same time, the acceleration stops Y mass entering the cell, which increases contact.

The separation space (6), the cell geometry and the location of the feed, circulation and exhaust streams provide a perpendicular flow of the pulp block and the air bubbles with respect to each other. The selectivity and yield thus obtained can be enhanced in the separation mode.

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In the separation chamber (6), the selectively separating foam must be removed fresh (8) as soon as it comes to the surface. Mechanical de-foaming combined with the separation space increases selectivity and yields are obtained.

• * * • · · 105212 9 - Upstream flow from cell to cell (9) combined with manifold and air supply fractions provide countercurrent washing improvement in final product purity and pulp stock to circulate in cell as desired.

The cell specific circulation current control (9) and the apertures of the transfer channels (5) of the discharge space (7) prevent the transfer of the released ink from one cell to another and thus enhance the ink separation capacity of the individual cell and the purity of the final product.

- The above physical, methodological features and their control capabilities allow for significant chemical savings which can be further enhanced by optimizing the supply of chemicals to feed and circulation streams.

- All the methodological features of the flotation equipment can be applied to existing equipment, giving them a yield and capacity gain and a cleaner product with less chemicals.

It is obvious to those skilled in the art that the invention is different

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Embodiments are not limited to the example exemplified above, but may vary within the scope of the following claims: i.

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Claims (13)

A floatation plant consisting of at least one cell (1) to which is connected a pipe system (2) for feeding a mass flow into the cell (1) for separating a pure mass flow and foam, characterized in that in the pipe system (2) a taper (3) at the narrowest point of which is provided an air supply (4) for efficient mixing of air bubbles in the pulp and the cell (1) comprises a separating space (6) in connection with which an outlet space (7) is provided. ) for removing the pure mass flow and means (8) for removing the foam from the separation space (6) immediately after its emergence. Installation according to claim 1, characterized in that the outlet space (7) is connected to a transfer channel (5) for feeding the mass flow into a second cell (11). Installation according to any of the preceding claims, characterized in that one or more cells (1), (11) are connected to a pipe system (9) for feeding a circulation flow of the pulp. • Plant according to any of the preceding claims, characterized in that at least tapered orifices (2) are provided in the taper (3). : V Installation according to any of the preceding claims, characterized in that the air inlet opening (4) is arranged for supplying air perpendicular to the mass flow. • · · Installation according to any of the preceding claims, characterized in that there is a substantially symmetrical taper (3) in the pipe system (2). 13 105212 7. A method of deinking and de-icing, in which the method of mass flow is measured into a cell (1) in a floatation system free of a pipe system (2), characterized in that a narrowing point (3) of the pipe system (2) is arranged. air supply (4) to form air bubbles and to mix them in the mass flow to remove the ink and the ink in the cell (1) where the ink and ink are dissipated by means of the air bubbles and separated from the mass flow by controlling the flow unequally the separation compartment (6) enters an outlet compartment (7) and the foam that arises on the surface is removed from the separation compartment (6) at the same time as it arises (8). Method according to claim 7, characterized in that an air supply (4) for mixing air into the pulp and an expansion air is provided in the narrowest point of the taper (3). A cone (10) thereafter by means of which a velocity sufficient to cause the air bubbles to be mixed in the pulp effectively and to guide them into the cell (1) of the flotation plant is obtained. % («• III <« Method according to Claim 7, characterized in that the mask · 1 · sap flow is controlled into one or more cells (11) through a transfer channel (5). • ♦ «• ·» • · · * · ♦ Method according to claim 7, characterized in that the mass flow through a pipe system (9) is measured back into one or more cells (1), (11) as a circulation flow. f • < Method according to Claim 7, characterized in that the taper (3) and the expansion cone (10) in the pipe system (2) are arranged to be substantially symmetrical. * · 14 105212 Method according to claim 7, characterized in that the air supply (4) is arranged perpendicular to the mass flow. 13. A method according to claim 7, characterized in that, by feeding the pulp flow, a negative pressure is produced in the air supply (4), the air supply being preferably self-suction. • · • · · · · · · · · · · · · · ··· »• M • · · • t» • · · · · · · ♦ • · ··· • · · • · · C t «< · «T 4 4 1 4 f 4 4 •« 4 4 4 4 4 ·