Abstract: An autoclave for pressure oxidation of a slurried material including at least one sulfide material, and a method. The autoclave includes a pressure vessel for receiving the slurried material. The pressure vessel includes compartments being arranged horizontally one after the another and separated by dividers. Each divider is provided with an upper edge or at least one opening that defines level of the slurried material in the compartment. An inlet is arranged for feeding oxygen-containing gas into the pressure vessel. An agitator arrangement is arranged for agitating the slurried material in at least one of the compartments, the agitator arrangement including at least an upper impeller and a lower impeller, the impellers arranged along a vertically aligned shaft. The upper impeller is arranged at a height above the mid-level of one of the compartments, and the upper impeller is an upward pumping axial or mixed flow impeller.

Abstract: A stirring impeller, an arrangement, and a use. The impeller comprises a hub disc comprising a shaft attachment structure arranged centrally in the hub for receiving a shaft centrally and perpendicularly from an upper side of the hub disc, a plurality of upper blades arranged on the upper side of the hub disc, and a plurality of lower blades arranged on a lower side of the hub disc. At least one of said plurality of upper blades is arranged to have jet angle of 5°-45°, and the lower blades have a jet angle that is different than said jet angle of least one of said plurality of upper blades.

Abstract: A mixing arrangement for mixing two solutions, a mixer settler unit and a use. The mixing arrangement includes a mixing device arranged in the mixing space for rotating therein, the mixing device comprising at least two helical bars supported around a shaft and rising upwards from the bottom section of the mixing space. The helical bars are fixed to the shaft with support spokes. The ratio of the diameter (D) of the mixing device to the average diameter (T) of the mixing space, that is D/T, is 0.47 at most.

Abstract: A reactor for gas-liquid mass transfer between a gas and a liquid or slurry includes a tank for receiving the liquid or slurry having a wall; a drive shaft; an upward pumping impeller; and an aerating apparatus disposed above the upward pumping impeller and extending between the drive shaft and the wall of the tank at a first distance (d1) from the drive shaft and at a second distance (d2) from the wall of the tank, the aerating apparatus encircling the drive shaft at least partially. The aerating apparatus has an outward inclined or curved inner surface for directing at least a part of the flow over the inner surface.

Abstract: A reactor for gas-liquid mass transfer between a gas and a liquid or slurry includes a tank for receiving the liquid or slurry having a wall; a drive shaft; an upward pumping impeller; and an aerating apparatus disposed above the upward pumping impeller and extending between the drive shaft and the wall of the tank at a first distance (d1) from the drive shaft and at a second distance (d2) from the wall of the tank, the aerating apparatus encircling the drive shaft at least partially. The aerating apparatus has an outward inclined or curved inner surface for directing at least a part of the flow over the inner surface.

Abstract: A mixing apparatus for mixing particles in a liquid and its use are disclosed. The mixing apparatus comprises a tank having a bottom and a substantially vertical side wall, an agitation means comprising a rotation shaft located vertically and centrally in the tank, and an impeller arranged at a height above the bottom at the end of the rotation shaft and the impeller being a downward pumping axial or mixed flow impeller. The bottom is equipped with a corrugated formation comprising alternate consecutive ridges and valleys, the ridges and valleys extending radially in relation to a center of the bottom, whereby the valleys concentrate and channel the mixing power near to the bottom to direct the flow of the liquid and to increase the velocity of the flow near to the bottom.

Abstract: A method and to an arrangement for recovery of precious metal. The method includes calculating a first electrical property of a slurry downstream of a retention screen in a first flow direction A either (i) based on a first difference between the first supplied current and the first received voltage, or (ii) based on a first difference between the first supplied voltage and the first received current, calculating a second electrical property of the slurry upstream of the retention screen either (i) based on a second difference between the second supplied current and the second received voltage, or (ii) based on a second difference between the second supplied voltage and the second received current, and calculating the adsorption particle content of the slurry upstream of the retention screen based on a difference between the first and the second electrical property.

Abstract: A method and to an arrangement for recovery of precious metal. The method includes calculating a first electrical property of a slurry downstream of a retention screen in a first flow direction A either (i) based on a first difference between the first supplied current and the first received voltage, or (ii) based on a first difference between the first supplied voltage and the first received current, calculating a second electrical property of the slurry upstream of the retention screen either (i) based on a second difference between the second supplied current and the second received voltage, or (ii) based on a second difference between the second supplied voltage and the second received current, and calculating the adsorption particle content of the slurry upstream of the retention screen based on a difference between the first and the second electrical property.

Abstract: A hydrofoil impeller wherein the tip edge is straight and has a right angle with a radius extending from the central axis to the tip edge. In the central hub and in each of the blades the number of holes in each group of first and second holes is at least five. The pattern in which the holes are arranged in each of the respective groups of holes is elliptical having a center and a major axis which is substantially parallel to the radius and placed at a distance therefrom. The leading edge is, in the direction of rotation, behind an imaginary radial line intersecting the central axis of the shaft and the center of the ellipse, the leading edge being at an angle of 50°±2° in relation to the radial line. The area of the blade is divided into four planar portions by three straight bends.

Abstract: The invention relates to a stirred tank reactor for gas-liquid mass transfer in a slurry. The reactor includes a reactor tank (1) having a first volume (V1), a drive shaft (2) that extends vertically in the reactor tank, a motor (3) for rotating the drive shaft (2), a main impeller (4) which is a downward pumping axial flow impeller attached to the drive shaft (2) to create a main flow pattern in the reactor tank, and a gas inlet (5) arranged to supply gas into the reactor tank (1) to be dispersed to the liquid.

Abstract: A hydrofoil impeller wherein the tip edge is straight and has a right angle with a radius extending from the central axis to the tip edge. In the central hub and in each of the blades the number of holes in each group of first and second holes is at least five. The pattern in which the holes are arranged in each of the respective groups of holes is elliptical having a center and a major axis which is substantially parallel to the radius and placed at a distance therefrom. The leading edge is, in the direction to rotation, behind an imaginary radial line intersecting the central axis of the shaft and the center of the ellipse, said leading edge being at an angle of 58°±2° in relation to the radial line. The area of the blade is divided into four planar portions by three straight bends.

Abstract: A mixing apparatus for mixing particles in a liquid and its use are disclosed. The mixing apparatus comprises a tank having a bottom and a substantially vertical side wall, an agitation means comprising a rotation shaft located vertically and centrally in the tank, and an impeller arranged at a height above the bottom at the end of the rotation shaft and the impeller being a downward pumping axial or mixed flow impeller. The bottom is equipped with a corrugated formation comprising alternate consecutive ridges and valleys, the ridges and valleys extending radially in relation to a center of the bottom, whereby the valleys concentrate and channel the mixing power near to the bottom to direct the flow of the liquid and to increase the velocity of the flow near to the bottom.

Abstract: The invention relates to a stirred tank reactor for gas-liquid mass transfer in a slurry. The reactor includes a reactor tank (1) having a first volume (V1), a drive shaft (2) that extends vertically in the reactor tank, a motor (3) for rotating the drive shaft (2), a main impeller (4) which is a downward pumping axial flow impeller attached to the drive shaft (2) to create a main flow pattern in the reactor tank, and a gas inlet (5) arranged to supply gas into the reactor tank (1) to be dispersed to the liquid.