Abstract: The invention relates to a method for the removal of metals from their aqueous solution with lime precipitation, in conditions where a precipitate of metal hydroxide and gypsum is formed, which settles well and is easy to filter. The metals are precipitated from their aqueous solutions at a high pH value and the slurry is recirculated several times in the precipitation space, whereby the gypsum is precipitated as separate crystals instead of a solid layer. The method is particularly suitable for neutralization of the aqueous solution from the pickling of refined steel. Using this method enables the removal of metals and fluoride from the water in question.

Abstract: The invention relates to a flotation mechanism (4) comprising a directional element (25) and vertical vanes (26) located in a flotation cell (2). The directional element is symmetrical and is fixed at the center to the lower section of the hollow shaft of the mechanism. According to the corresponding method, due to the directional element (25), which is cylindrically inclined downwards from the outer edge the flotation mechanism directs the gas-slurry suspension that is formed in a downward slanting direction towards the side wall of the cell. The mineral suspension rises upwards from the side wall towards the center of the cell, from where the flow is diverted to the edges of the cell and the froth generated is removed from the cell. Using this flotation mechanism enables a powerful agitation, extending throughout the entire mixing zone (I).

Abstract: The invention relates to a method of clarifying and/or thickening a solution containing solids i.e. a slurry, and the apparatus for accomplishing this. Using the method and apparatus of the present invention, the slurry to be fed into the clarification or thickening apparatus is distributed evenly into the slurry already in the tank. It is characteristic of the clarification tank now developed that the displacement capacity of the raking system in the tank is the same from the edges of the tank up to the centre. The displacement capacity is measured as being the same as the underflow discharge capacity from the centre of the tank. The displacement capacity can be determined to be the same using rake displacement plates of different heights, according to the distance of the displacement plates from the rake shaft and the number of plates rotating on the same ring-like cross-section.

Abstract: The invention relates to a method of clarifying and/or thickening a solution containing solids i.e. a slurry, and the apparatus for accomplishing this. Using the method and apparatus of the present invention, the flocculant to be fed into the clarification and thickening equipment is mixed evenly and with a small shear force into the slurry in the feedwell of the apparatus. The feedwell is equipped with a mixing device. The slurry is taken onwards from the feedwell evenly into the clarification tank inside the underflow layer, which enables the separation of a clear overflow solution.

Abstract: The invention relates to a method for the stabilization of the production capacity of an extraction plant extracting metals in a process, where the metal content of the feed solution varies. For the stabilization of capacity, the extraction cells and their piping are constructed and situated in such a way, that the extraction stages can be connected in different combinations, either in parallel or in a series. The method is especially suitable for the copper extraction process.

Abstract: The invention relates to a mixing apparatus and a method for mixing gas in a closed mixing reactor, which uses gas as a process chemical with a high efficiency and where the content of pulverous solids in the solution is great. The aim is to obtain a flow in the reactor which sucks gas from above the surface of the liquid using rotating mixing devices in the centre of the reactor, and to mix said gas throughout the reactor capacity. The mixing apparatus of the invention comprises at least two mixers located at different heights, and on the same shaft. The upper mixer is equipped with a central plate attached to the shaft, with essentially vertical inner blades rising upwards and downwards and outer vanes directed outwards from the central plate, which are inclined from the horizontal. The lower mixer is equipped with a central plate attached to the shaft with vertical blades located on the outer edge.

Abstract: The invention relates to a method for extracting copper in liquid-liquid solvent extraction from aqueous solutions with a high sulphate content, by raising the viscosity of the extraction solution and by dispersing the aqueous solution into drops, achieving a dense drop aggregation. The viscosity of the extraction solution may be raised either by increasing the content of the actual extractant, the extraction reagent, in the extraction solution or by using a diluting agent with a higher viscosity than that of the diluting agent normally used. By raising the viscosity of the extraction solution the mixing durability of the extraction dispersion can be increased and resulting of that the amount of residual drops is decreased. Other advantages are that the extraction solution flow of the extraction process decreases in relation to the flow of the aqueous solution acting as the copper source and that the size of the extraction equipment needed is reduced.

Abstract: In a method according to the invention, a dispersion coming from a mixer part is conducted from downwards to the liquid part of the settler, into the middle part of the feed end, wherefrom it is set to be distributed to inside the settler part, in a closed channel-like space located in the immediate vicinity of the settler along the whole width of the settler and the flow therefrom mainly above the channel-like part towards the rear end of the settler. The method according to the invention is realized by means of an apparatus where an uptake shaft extending from the dispersion mixing tank to the settler opens into the feed end of the settler, from where there are further directed distribution channels towards the settler side edges. The distribution channels are placed in the bottom part of the settler.

Abstract: The invention relates to a method for adjusting the boundary surface between the two mutually separable solutions in liquid—liquid extraction at the discharge end of the separation part and for preventing the aeration of the solutions when discharging them from the separation part, so that the overflow height of the settled, lighter organic solution is maintained constant. In order to adjust the boundary surface in between the mutually separable solutions, the overflow height of the heavier aqueous solution is adjusted by conducting the settled aqueous solution from down upwards through tubular elements, in which case the height of these overflow pipes can be adjusted. The aeration of the solutions when discharging them from the separation part is prevented by conducting the solutions into transfer pipes through covered, shaft-like weir boxes that are deeper than the discharge end.

Abstract: The method and apparatus according to the invention relate to conducting the dispersion of two phases, created in the mixing unit (1) of liquid—liquid extraction, from the mixing unit to the separation part (2), in which case the flow direction of the dispersion discharged from the mixing unit asymmetrically with respect to the separation part is turned to be symmetrical with respect to the separation part. In the last mixer (4) of the mixing unit, the orientation of the dispersion is turned to be parallel to the lengthwise axis of the separation part, by means of flow-turning members (9), the dispersion flow is discharged from the mixing unit at the height of the mixer bottom (10) and conducted to an uptake shaft (11) parallel to the lengthwise axis of the separation part, where the dispersion flow is turned upwards and made to be discharged symmetrically into the separation part.

Abstract: The invention relates to a method for settling the dispersion formed in the mixing unit of liquid-liquid extraction, for controlling solution flows and for creating pure solutions in the separation part. According to the method, the flow speed of the organic solution phase is adjusted to be clearly higher than the flow speed of the aqueous solution phase, in which case in order to prevent border flow turbulence caused by the speed difference of the solution phases, the water drop dispersion layer left in between the separating solutions is adjusted to extend as far as the discharge end of the separation part.

Abstract: The invention relates to a method for recirculating the heavier solution from the separation part of liquid--liquid extraction to the mixing unit of the same extraction step, so that part of the recirculated solution is returned to the mixing unit from the overflow of the discharge end of the separation part. An essential feature of the invention is that the major part of the heavier solution recirculated into the mixing unit is obtained from the separation part proper, along the whole width thereof. The invention also relates to an apparatus based on said method, in which apparatus, in the bottom part of the settler (6) there is located a heavier solution collecting channel (13) extending over the whole width of the settler and being provided with suction pipes (15) which are oriented in an inclined fashion towards the solution to be collected from the channel.

Abstract: The invention relates to a method for extracting metals from large solution flows in liquid--liquid solvent extraction and to an apparatus for realizing the same. By employing the method and apparatus of the invention, it is possible to choose which phase is maintained continuous at the dispersion stage, while the other phase remains as drops, to prevent the aeration of the organic phase and to pump the phases further at a low circumferential speed in order to prevent emulsification. Another object of the invention is to make the dispersion removed from the settler unit spread in the settler unit over the whole transversal area thereof. The method and apparatus of the invention are particularly well suited to large copper extraction plants.