Froth flotation arrangement and a froth flotation method

A froth flotation method for treating mineral ore particles suspended in slurry, and in the method separating the slurry in flotation cells into an underflow and an overflow, the method comprising the steps of:

• connecting at least three of said flotation cells in series for creating a primary line, wherein each subsequent flotation cell of the at least three flotation cells receives the underflow from a previous flotation cell,
• feeding the slurry to a tank of a third or subsequent flotation cell in the series of the at least three flotation cells as underflow,
• introducing gas into the tank through a gas supply,
• mixing the slurry and the gas with an impeller within the tank,
• providing the tank with a volume of at least 200 m3,
• receiving the overflow in a froth collection launder of at least two froth collection launders provided in the third or subsequent flotation cell,
• receiving the overflow over a froth overflow lip provided in the froth collection launder,
• forming an available froth surface area (Afroth) in the third or subsequent flotation cell,
• providing the tank with a ratio between a height (h) from a bottom of the tank to the froth overflow lip of the froth collection launder and the diameter (D) of the tank at the height (h1) of the impeller of a pulp area (h/D) being less than 1.5, and
• wherein the third or subsequent flotation cell has pulp area (Apulp), wherein the pump area (Apulp) is calculated as an average from the cross sectional areas of the tank at the height of the impeller (h1), and a ratio between the available froth surface area and the pulp area (Afroth/Apulp) is less than 0.45, and
• wherein the at least two froth collection launders are annular shaped, positioned coaxially, and define an average froth transport distance (dtr) less than 100 cm.