FI121456B - A method for mixing gas with slurry during foaming and apparatus for doing so - Google Patents

Abstract

The invention relates to a method and apparatus for mixing gas into slurry during flotation and for guiding the slurry dispersion upwards in the reactor in a controlled manner. The method utilises the combined effect of a powerful mixer and devices placed inside the reactor. The method and apparatus are especially suitable for the flotation of metal-bearing ores that are difficult to process.

Description

METHOD FOR MIXING GAS INTO THE SLUDGE WITH FLAMMING AND THE APPARATUS FOR THIS

FIELD OF THE INVENTION

The invention relates to a method and apparatus for mixing gas in slurry during foaming and controlling the slurry dispersion in a reactor in a controlled manner. The method utilizes the interaction of a powerful agitator and means placed inside the reactor. The method and apparatus are particularly suited for flotation of difficult-to-handle metallic ores.

BACKGROUND OF THE INVENTION

U.S. Patent Nos. 5,240,327 and 5,078,505 disclose a method and apparatus for mixing gas and solids in a liquid to provide a toroidal double ring cycle. The desired circulation is achieved in a reactor equipped with a strong down-mixer, solution-specific flow disadvantages, and a suction pattern controller. Flow disadvantages are wider and are located farther from the reactor cylindrical surface than standard drawbacks. In addition, the reactor is equipped with at least 20 suction pattern guides. If there are two controls, the lower one is fixed and the upper one can be moved vertically. The suction pattern guides are positioned horizontally. According to Figure 2, the upper guide is narrower so that its inner edge is at the same distance from the lower rotor axis. With the aid of a stirrer, flow problems, and a suction pattern guide, a rather strong downward slurry flow towards the reactor wall is provided in the reactor, which partially turns upward and partially circulates through the bottom back to the mixer. The suction pattern controller controls the amount and direction of upward flow. Preferably, the flow rises from the center upwards and returns along the edges downwards. When the reactor is used, for example, as a flotation cell, the mineral particles trapped in the air bubbles rise up and escape into the chips in an overflow.

US-A-4,548,765 discloses a mixer having dispersing fins located above and below the circular plate attached to the axis of the mixer as well as directional fins located outside the circular plate. The focus of the blades is below the circular plate s. The agitator is intended to mix gas, liquid and solid with each other to form a good dispersion, whereby the progress of chemical reactions proceeds as desired.

U.S. Patent No. 7,070,174, in turn, describes a mixing apparatus consisting of two mixers mounted on a mixer shaft. The agitator is intended for a closed reactor, for example a vertical autoclave. The purpose of the mixing apparatus is to disperse the gas in the slurry which is fed into the reactor above the slurry surface.

In the apparatus of US Patent No. 7,070,174, the top mixer consists of a center plate mounted on the shaft, inner fins attached to the center plate and outer fins attached to the outer edge of the central plate. The inner edge of the inner wings above the center plate is formed outwardly tapering in a circular arc, and below the center plate the inner edge 20 is straight. The outer edge of the inner wing is vertical throughout. The outer flaps are attached directly to the center plate at the same position as the inner flaps. The outer flaps are rectangular and have a tilt angle of 30 to 60 degrees to the center plate. The center of the top mixer blades is above the center plate.

25

The agitator apparatus also includes a bottom agitator consisting of a circular center plate and wings attached to its periphery. The outer edges and the inner edges of the fins above the center plate are vertical, but the part below the center plate of the inner edge is formed outwardly tapering in the form of a circular arc 30. The upper blades of the mixer are intended to create a vortex that absorbs gas from the liquid surface and disperse the gas into small bubbles. Since the top mixer cannot disperse 3 efficient slurry mixing in addition to dispersion, the mixing apparatus is provided with a lower mixer which is intended to provide a good mixing of the slurry itself and further disperse the gas bubbles and mix them into the slurry. The down mixer takes up significantly more power than the top mixer. The mixing apparatus 5 is always intended to consist of at least two mixers as described above.

PURPOSE OF THE INVENTION

The methods and apparatus described in the prior art are intended mainly for 10 standard mixing solutions where the power required from the mixer is not very high. The mixing apparatus described in U.S. Patent 7,070,174 provides efficient mixing, but always requires two mixers per shaft.

The object of the process of the present invention is to provide a more efficient gas dispersion in the slurry and a controlled mixing pattern of the resulting dispersion, whereby the mineral particles trapped in the gas bubbles are made to rise to the surface of the slurry and exit the slurry cycle. The flotation apparatus is comprised of a reactor and an adjustable circumferential cone, a flow defect, and a rotor mixer with high agitation power.

SUMMARY OF THE INVENTION

The essential features of the invention will be apparent from the appended claims.

25

The invention relates to a mixing apparatus for mixing gas with slurry in a flotation process, wherein the apparatus consists of a reactor, a foam trough, a rotor mixer located inside the reactor, flow defects and circumferential cones. In the mixing apparatus, the circumferential cones are disposed in the reactor 30 between the flow impediments and the reactor wall and are positioned from the edges of the reactor towards the center in an upward position at an angle of 20-40 °. The rotor mixer is provided with inner and outer fins attached to a circular plate 4 arranged in a height direction symmetrically with respect to the plane formed by the circular plate.

It is typical of the apparatus according to the invention that the number of circumferential cones is two, whereby the distance of the lower, fixed cone outer edge from the reactor wall is of the order of 0.02 to 0.03 times the diameter of the reactor and of 0.06 to 0.08 times the radial width. diameter of the reactor.

According to one embodiment of the invention, the distance of the upper, adjustable cone outer edge from the reactor wall is in the range of 0.002 to 0.003 times the reactor diameter.

According to an alternative of the invention, a flow deflector is provided with a baffle plate parallel to the circumferential cone at a height of 1.5 to 1.7 times the diameter of the mixer. The length of the baffle plate in the direction of the radius of the reactor is in the order of 0.11 to 0.14 times the diameter of the reactor.

It is typical of the apparatus according to the invention that the number of inner and outer blades in the rotor mixer 20 is 5 to 8. In the rotor mixer, the inner edge of the inner blade, which includes both the top and bottom of the circular plate, is curved in the direction of the blender axis so that the top and bottom of the blade are horizontal from the outside to 35-50% of the total width of the blade. The outer blades of the rotor mixer are at an angle of 50 to 70 °, preferably 60 ° to the plane formed by the circular plate.

According to one embodiment of the apparatus according to the invention, the inner blades of the rotor mixer and the outer blades are aligned, i.e. the arm connecting the outer blade 30 to the circumferential plate is attached to the circumferential plate at the same position as the inner blade.

5

According to another embodiment of the apparatus according to the invention, the inner blades of the rotor mixer and the outer blades of the rotor mixer are displaced relative to one another in a circular plate. The inner wings and outer wings are in phase displacement with respect to each other between 0 and 36 °. According to one embodiment of the apparatus 5, the phase shift between the inner and outer blades is adjustable.

The invention also relates to a flotation method for mixing gas with slurry in an apparatus consisting of a reactor, a foam trough, a rotor mixer located inside the reactor, flow hazards, and annular cones. Using a rotor mixer and flow disadvantages, a slurry dispersion of the gas and slurry fed into the reactor is formed, which is subjected to a vigorous rotation underneath the mixer and first rises above the mixer and then rotates the slurry dispersion towards the center at 20 to 40 ° increments; at the top of the reactor, the slurry dispersion is made to spread across the reactor cross-section and exit partially in an overflow to the foam trough and partially return through the reactor walls back to the mixer.

According to an alternative to the flotation method according to the invention, the upward slope dispersion direction towards the center is enhanced by a baffle plate arranged in the direction of the flow and disposed in a flow direction.

LIST OF FIGURES

Figure 1 is a side elevational view of a mixing apparatus according to the invention,

Figure 2 is a cross-section of the mixing apparatus,

Figure 3 is an enlarged view of Figure 1, Section A,

Fig. 4 shows a side view of a mixer suitable for a mixing apparatus, Fig. 5 shows a top view of a mixer according to Fig. 4 and shows an alternate positioning of the blades of a mixer according to the invention;

DETAILED DESCRIPTION OF THE INVENTION The mixing method and mixing apparatus according to the invention are directed to flotation methods which are supplied with gas, usually air. It is typical of the method that a strong vertical rotation pattern is formed in the reactor, which is achieved by a specially designed agitator and vertical circumferential cones. The shuffling reactor could be referred to as the VFIB (Vertical Flow Intensity Balanced) reactor. The reactor is preferably a vertical cylinder having a fill height (effective height) of 0.8 to 1.4 times the cylinder diameter. Instead of the vertical flow problems normally placed on the reactor wall, vertical plates placed closer to the mixer are used, which can also act as a stator. It is typical of the process that an effective, reactor-wide, controlled mixing is achieved by using only one mixer having a peripheral velocity of up to 5 to 7 m / s, since the mixer according to the invention has a high power rating of 4-10. 1 2 3 4 5 6 7 8 9 10 11

When the method and apparatus according to the invention are used for foaming, separate coaching is not required in principle, since the mixing solution of the invention 3 has proven to be so effective that both training 4 and foaming can be performed simultaneously. In the process according to the invention 5, the agitation extends uniformly throughout 6 below the circumferential cones of the entire reactor. The flotation cell is generally 7 equipped with a stator surrounding the rotor, which consists of 8 vertical plates. This arrangement provides a relatively strong primary pumping jet of almost 9 radial and slightly rising, which is however clearly attenuated by the stator. The system works quite well in 11 lying trough cells, especially if they have multiple rotor / stator mechanisms in the same trough. When the size of the cell is in the range of 50 - 500 m3, the structure must be symmetrical and then, for example, 7 vertical cylinders is a good solution. The vertical cylinder is a good solution in terms of flow and makes changes in the scale easier to calculate and control.

Providing sufficient and effective mixing and dispersion in large flotation cells sometimes presents difficulties. The traditional rotor-stator design does not always provide a mixing pattern that allows the air to mix with the slurry and further the mineral particles trapped in the air bubbles to rise above the liquid surface so that they do not have time to flocculate with each other and thus remain in the 10 slurry. When the mineral particles remain in rotation in the slurry, their surface may also oxidize, which is an undesirable phenomenon.

The method and apparatus of the present invention now provide a powerful slurry circulation both above and below the mixer. It is typical of the process of the invention that air is introduced into the reactor through the hollow shaft of the rotor mixer, which is dispersed in the slurry by means of the inner blades of the mixer, and then the slurry dispersed by the outer blades of the mixer. First, the agitator creates a strong oblique downward flow of the slurry dispersion 20, which partially turns down the reactor walls to return to the agitator. The second portion of the flow turns upward and rises along the walls of the reactor, where it is guided by circumferential cones rising from the edges of the reactor towards the center to continue toward the center of the reactor and continue to rise upwards in the center of the reactor. The direction of the slurry flow obliquely to the center and upwards can be further enhanced by the use of baffles parallel to the circumferential cones. At the top of the reactor, the flow again spreads calmly across the reactor across the cross section. Some of the sludge is discharged to the foam chute and some circulates back along the reactor walls to the mixer. 30 Circular cones and baffles provide a bottom-up and out-sludge flow, the so-called sludge flow. "Mushroom" flow, which is the preferred form of flow for flotation.

8

Due to the strong upstream circulation, all the material in the flotation reactor which does not escape in the overflow is reintroduced into the dispersant treatment of the mixer. This promotes foaming of the ore that is difficult to handle. For example, highly flocculating ore does not have the time to flocculate again and thus weakens the flotation result. Vigorous mixing underneath the agitators results in the air being dispersed in the ore slurry, the chemicals adhering to the solids surfaces, and possibly flocculation decomposition.

10

Figure 1 shows a typical flotation reactor 1 for use in flotation, the upper part of which is circulated by an external foam trough 2. The reactor cross-section without a foam trough is shown in figure 2. The slurry to be treated is normally fed into the reactor from the lower part of the reactor. The reactor, or flotation cell, is provided with flow defects of the type described in U.S. Patent 5,078,505, which are wider than the standard drawbacks and are distant from the reactor walls. The radial length (width) of the flow defaults is in the range of 0.11-0.14 times the reactor diameter and 0 08 to 0.1 times the diameter of 20 reactors. Depending on the size of the reactor, the number of flow problems is 6 to 10. In addition, the reactor is provided with two circumferential cones 4 and 5 which are placed between the reactor wall and the flow downstream of the mixer 6. The air supplied to the reactor is introduced, for example, through the hollow shaft 7 of the mixer. The diameter of the rotor mixer is preferably in the order of 35 to 25 45% of the diameter of the reactor and is placed in the reactor from the bottom to a height of 0.7 to 1 times the diameter of the mixer.

The circumferential cones are shown in more detail in Figure 3. The distance of the lower circumferential cone 4 from the bottom is in the order of 1-1.2 times the diameter of the mixer. The circumferential cones are characterized in that they are mounted instead of the prior art horizontal plane from the edges of the reactor towards the center in an upright position so that their angle to the horizontal plane is in the order of 20 to 40 degrees. In the solution 9 according to the invention, the purpose of the circumferential cones is in particular to direct the upward slurry flow towards the center and to partially block the downward flow. This is accomplished by placing the circumferential cones quite close to the reactor wall. The circumferential gap of the lower solid cone 5, i.e. the distance of the outer edge of the cone from the reactor wall, is preferably in the range of 0.02 to 0.03 times the reactor diameter and the circumferential gap of the upper circumferential cone 5, adjustable by means of member 8, is only 0.002 to 0.003 times the reactor diameter. The width of the lower cone in the radial direction of the reactor is of the order of 0.06 to 0.08 times the diameter of the reactor. When the upper peripheral cone is in its lower position, it is almost closed in the lower cone and then forms a uniform surface that strongly directs the sludge flow to the center of the reactor. Only a smaller portion of the sludge flow returns to the mixer from the gap between the reactor wall and the peripheral cone. The lower circumferential cone may further be provided with projections 9 directed from the cone towards the center of the reactor, which dampen the upward flow along the flow disadvantages.

When the reactor is equipped with circumferential cones rising towards the center, the slurry flow is rotated smoothly and the mineral 20 particles adhered to the air bubbles are not released from the bubble. This is especially important when the material to be foamed is heavy and poorly airborne.

In some cases, it is advantageous to attenuate the upward flow generated by the circumferential cones by means of a baffle 10 attached to each flow interference 25, as shown in Figures 1 and 2. The baffles are mounted above the circumferential cones, typically from 1.5 to 1.7 times the agitator diameter. The baffle plate is rectangular and is at an angle to the horizontal plane of the baffle, i.e. it rises towards the center of the reactor at an angle of 20 to 40 degrees. The length of the baffle plate in the radial direction of the reactor is of the same order of magnitude as the flow defect, and the width is about half that.

10

In width, the baffle is fixed to the flow hub to be symmetrical on both sides.

An important part of the apparatus for flotation is the agitator 6 for intensive agitation 5, which is illustrated in more detail in Fig. 4. The agitator of the agitator of the invention is characterized in that the agitator hanging on the shaft 7 consists of a circular plate 11 symmetrically of the inner blades 12 and of the outer blades 14 secured to the circular plate by means of the shaft 13, the inventive mixer has an exceptionally high power ratio, Np = 4-10, which ensures a preferred peripheral speed of 5 to 7 m / s in large flotation units. ) also when it is desired to increase the mixing capacity per volume to 1.5 - 5.0 is kW / m3. Prior art mixers generally achieve a power rating of 2.4 to 3.0. As the tip speed of the outer blades of the mixer rises above the above limit, the wear of the mixing mechanism is greatly enhanced. The number of both inner and outer blades in the mixer according to the invention is 5 to 8. Since gas is introduced into the mixing process, the shaft 7 of the mixer 20 can be arranged hollow internally, whereby gas can be supplied therewith, if desired, below the circular plate. Of course, the gas can also be fed from the bottom of the reactor towards the circular plate through a separate feed pipe. The ratio of agitator diameter to agitation / foaming reactor is of the order of 0.35-0.40.

25

To increase the agitating power both above and below the agitator, the agitator is formed such that the fins are disposed symmetrically with respect to the circumferential plate so that an equal proportion of the fins are above and below the circumferential plate. In order to improve mixing efficiency, the inner edge 30 of the inner blade, which includes both the upper and lower part of the circular plate, is curved, preferably parabolic, in the direction of the mixer axis, with the upper blade 16 and lower 17 facing horizontally % of total wing width. The outer edge 18 of the inner flap is typically vertical and preferably extends beyond the periphery of the circular plate, for example, at a distance of about 0 to 2% of the diameter of the mixer. The inner fins 5 are mounted perpendicular to the circular plate and preferably extend the same distance above and below the plane formed by the circular plate. The inner blades have a height of 38 to 46% and a width of 14 to 20% of the overall diameter of the mixer. The inner blades are designed specifically to disperse the gas in the slurry, so they can also be called dispersing-10 blades.

The arms 13 are attached to the outer edge of the circular plate 11, and the outer blades 14 are attached to the outer end thereof. The outer blades are rectangular in shape and have a height of the order of 3 to 3.5 times their width. The width of the outer flap at the circumferential plate is of the order of 10 to 20%, preferably 15%, of the total diameter of the mixer. The blades are at an angle of 50 to 70 °, preferably 60 ° to the plane formed by the circular plate. The outer fins are also symmetrical with respect to the circular plate, i.e. extending substantially the same distance above and below the plane formed by the circular plate. The lengths of the arms 13 securing the outer fins to the circular plate are in the order of 3-4% of the total diameter of the mixer.

In the solution shown in Figure 5, the number of both inner and outer flaps is 6, but their number may vary between 5 and 8. The amount depends mainly on the size of the reactor in which the agitator is placed. In Figure 5, the flaps are disposed such that the inner and outer flaps are aligned, i.e. the arm connecting the outer flap to the circular plate is fixed at exactly the same position as the inner flap. 1

The solution of Fig. 6 also has a number of outer and inner fins of 6, but now the fins are fastened to the circular plate relative to each other. As shown in Figure 6, the blades are in a 30 degree phase displacement relative to one another. It is typical of the mixer solution according to the invention that the blades can be in phase displacement with respect to each other between 0 and 36 ° depending on the number of blades and the need for mixing. When the blades are in phase displacement relative to one another, there are twice the dispersion points of the materials to be mixed around the mixer compared to the blades being aligned. When the agitator of Fig. 6 is placed in a reactor larger than 50 m3 and dimensioned as described above, the peripheral velocity of the inner flaps also rises above 4 m / s, which is clearly within the dispersion range. The end result is a more uniform dispersion of the gas into the reactor solution or slurry. Phase displacement is maximal when the outer flaps are exactly between the inner flaps. Thus, depending on the number of blades, the maxi-phase shift is between 36 and 22.5 °. It is also typical for the mixer apparatus of the invention that the phase shift between the blades can be adjusted as required.

15

In the case of Fig. 6, where the number of inner and outer blades is 6, an effective solution for positioning the inner and outer blades is that the inner blades are preferably 20 ° up to 10 ° behind the outer blades with respect to the direction of rotation of the mixer. As the inner blade passes forward, the gas coming from below the 20 circular plates becomes radially elevated with the release blades of the inner blades and is immediately influenced by the outer blade that follows. The gas disperses very uniformly, for example, with a phase shift of, for example, 20 degrees, whereby the gas is dispersed in the wider space by the outer wings, and thus the dispersion efficiency is achieved, in particular by the upper parts of the circular plate. With a phase shift of the order of 5 degrees, very strong local dispersion is obtained as the gas and slurry are discharged outward and upward from the small gap formed by the inner and outer vanes. 1

The position of the inner and outer blades is particularly strong when the agitator is sized for a reactor with a capacity of more than 100 m3. In this case the absolute gas travel distances are already considerable, but the effect of the 13 trips can be reduced by increasing the number of blades of the mixer.

EXAMPLES

5

Example 1

Enrichment experiments were carried out on serpentine nickel ore in a VFIB flotation reactor of the invention having a diameter of 362 mm and an effective height of 437 mm. The mixer used for flotation was in accordance with the invention, 144 mm in diameter and 6.2 in power.

Most of the nickel ore to be treated was pentlandite and was ground to a fineness of 90% to 40 µm, whereby most of the nickel sulfides were released into their own sulfide particles. Because the sulfide particles are very sensitive to oxidation, a flotation test was started immediately after grinding. The ore was slurried in a sodium chloride solution of a concentration of about 2.5% to a slurry density of 150 g ore. Analysis of the ore was Ni 0.44%, Fe 4.2%, Mg 23.2% and S 0.71%, which showed that magnesium silicates were the main components of the ore.

20

In the flotation test, the agitator speed was 470 rpm and the air supply was 22.5 l / min. The flotation chemicals were added over 6 min prior to air supply. Air was supplied for five 5 min periods at 6 min intervals. The addition of the flotation reagents, that is, the printing and collecting chemicals, was performed when the air supply was not on. The result of flotation was that, when summing the yield of nickel concentrate formed during each of the five cycles, the cumulative nickel yield was 83%, the magnesium yield 34.7% and the sulfur yield 81.5%. The result is considered good, since 15-20% of nickel is distributed in silicates in the ore. 1

The flotation test was repeated except that the mixer described in U.S. Patent 4,548,765 was used as the mixer. The corresponding cumulative nickel yield was 57%. On closer inspection, it was found that the flocculation of 14 ores was the cause of the decrease in the nickel yield because this prior art mixer provided too low a mixing power. With this mixer, the mixing power was gradually reduced, and it was found that flocks in the top of the ore slurry were already present at 400 min * 1. The flocs encapsulate the sulfide particles, preventing them from adhering to the air bubbles and reducing the nickel yield. Indeed, flocculation is a typical property of iron-magnesium silicate-type nickel ores and is due to electrically charged silicates which encapsulate nickel-containing sulfide particles.

10

It is seen from the example that by raising the mixing power and making the mix uniformly distributed in the flotation cell, a satisfactory nickel yield is obtained. The mixer according to the invention had an average volume-per-blend power of 4.71 W / L before air supply and 3.50 W / L during air supply. The corresponding figures for the prior art mixer were 2.6 W / L and 1.4 W / L. An advantage of the mixing solution according to the invention is that the vertical mixing dimension provided by it is considerably larger than in the prior art mixer, the majority of the shaft power of which is directed downwards.

Claims (12)

A mixing apparatus for mixing gas in a slurry in a flotation process, the apparatus consisting of a reactor (1), 5 foam troughs (2), a rotor mixer (6) located inside the reactor, flow impedances (3) and circumferential cones (4,5). (4,5) are disposed in the reactor between the flow drawbacks (3) and the reactor wall and are set upwardly from the edges of the reactor towards the center at an angle ίο 20 - 40 ° and the rotor mixer (6) is provided with inner and outer fins 12,14), which are arranged vertically symmetrically with respect to the plane formed by the circular plate. An apparatus according to claim 1, characterized in that the number of circumferential cones is two, wherein the distance of the outer periphery of the lower, fixed cone (4) from the reactor wall is in the order of 0.02 to 0.03 times the diameter of the reactor. Apparatus according to claims 1 and 2, characterized in that the radial width of the lower circumferential cone (4) is in the order of 0.06 to 0.08 times the diameter of the reactor. Apparatus according to claims 1 and 2, characterized in that the distance between the upper edge of the upper adjustable cone (5) and the reactor wall is in the range of 0.002 to 0.003 times the diameter of the reactor. Apparatus according to Claim 1, characterized in that a guide plate (10) 30 extending parallel to the circumferential cones (10) is attached to the flow stops (3) above the circumferential cones (4,5) at a height of 1.5 to 1.7 times the diameter. Apparatus according to claims 1 and 5, characterized in that the length of the baffle plate (10) in the radial direction of the reactor is of the order of 0.11 to 0.14 times the diameter of the reactor. Apparatus according to claim 1, characterized in that the number of inner and outer blades (12,14) in the rotor mixer is 5 to 8. Apparatus according to Claim 1, characterized in that in the rotor mixer the inner edge (15) of the inner blade, which includes both the upper and lower part of the circular plate (11), is curved in the direction of the mixer shaft (7) the lower edge (17) being horizontal from the outer edge (18) inwardly, which is 35 to 50% of the total width of the wing. 15 Apparatus according to claim 1, characterized in that the outer blades (14) of the rotor mixer are at an angle of 50 to 70 °, preferably 60 °, with respect to the plane formed by the circular plate (11). Apparatus according to claim 1, characterized in that the inner flaps (12) and the outer flaps (14) are aligned, i.e. the shaft (13) connecting the outer flap to the circular plate is fixed to the circular plate at the same position as the inner flap. Apparatus according to claim 1, characterized in that the inner flaps (12) and the outer flaps (14) are fastened to the circular plate (11) relative to each other. Mixer according to Claim 11, characterized in that the inner flaps (12) and the outer flaps (14) are in a phase displacement 3 with respect to each other in the range of 0 ° to 36 °. The mixer according to claim 11, characterized in that the phase shift between the inner and outer blades is adjustable. 14. Foaming process for mixing gas with slurry in an apparatus consisting of a reactor (1), a foam trough (2), a rotor mixer (6), flow defects (3) and circumferential cones (4,5), characterized in that the rotor mixer (6) ) and by means of flow impedances (3), a slurry dispersion of the gas and slurry fed into the reactor is formed which, under the mixer, is subjected to a vigorous rotation and rising above the mixer and then the slurry dispersion is rotated from the edge towards the center at an angle of ); in the upper part of the reactor, the slurry dispersion is caused to spread over the entire reactor 15 cross section and exit partially overflow into the foam trough (2) and partially return back to the mixer along the reactor walls. Method according to Claim 14, characterized in that the upward slope of the slurry dispersion is oriented towards the center 20 by means of a baffle plate (10) attached to the flow defect (3). 1