Froth flotation arrangement and a froth flotation method
A froth flotation arrangement and method for treating mineral ore particles suspended in slurry includes a flotation cell for separating the slurry into an underflow and an overflow and a primary line including at least three flotation cells connected in series, wherein each subsequent flotation cell is arranged to receive the underflow from the previous flotation cell, the flotation cell includes a tank and an impeller within the tank, and the flotation cell includes a gas supply within the tank, the tank includes a volume of at least 200 m3, the flotation cell including a froth collection launder capable to receive the overflow the froth collection launder including a froth overflow lip, the flotation cell having an available froth surface area (A froth), the flotation cell having a pulp area (A pulp), where the pulp area (A pulp) is calculated as an average from the cross sectional areas of the tank at the height (h 1 ) of the impeller. 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 (h 1 ) of the impeller (h/D) is less than 1.5.
1. A froth flotation arrangement for treating mineral ore particles suspended in slurry, comprising flotation cells for separating the slurry into an underflow and an overflow, wherein the arrangement comprises:
a primary line comprising at least three of said flotation cells connected in series, wherein each subsequent flotation cell of the at least three flotation cells is arranged to receive the underflow from the previous flotation cell,
wherein a third or subsequent flotation cell in the series of the at least three flotation cells comprises a tank having a volume of at least 200 m3, an impeller within the tank, a gas supply within the tank, and at least two froth collection launders capable of receiving the overflow, a froth collection launder of the at least two froth collection launders comprising a froth overflow lip,
wherein the third or subsequent flotation cell has:
an available froth surface area (A froth );
a pulp area (A pulp ), where the pulp area (A pulp ) is calculated as an average from the cross sectional areas of the tank at the height (h 1 ) of the impeller; and
a ratio between the available froth surface area and the pulp area (A froth /A pulp ) less than 0.45,
a ratio between a height (h) from a bottom of the tank to the froth overflow lip and the diameter (D) of the tank at the height (h 1 ) of the impeller (h/D) is less than 1.5, 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.
2. The froth flotation arrangement according to claim 1 , wherein 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 (h/D) is less than 1.1.
3. The froth flotation arrangement according to claim 1 , wherein the ratio between the available froth surface area and the pulp area (A froth /A pulp ) is from 0.1 to 0.45.
4. The froth flotation arrangement according to claim 1 , wherein the periphery shape of the froth collection launder shape corresponds the tank periphery shape.
5. The froth flotation arrangement according to claim 1 , wherein the froth collection launder comprises an Internal peripheral launder or the tank comprises an internal peripheral froth blocker.
6. The froth flotation arrangement according to claim 5 , wherein the ratio between the area of the internal peripheral launder and the pulp area (A int launder /A pulp ), or the ratio between the area of the internal peripheral froth blocker and the pulp area (A int blocker /A pulp ), is more than 0.1, preferably more than 0.1 and less than 0.5.
7. The froth flotation arrangement according to claim 1 , wherein the tank is circular in cross section at the overflow lip height (h 2 ) of the tank.
8. The froth flotation arrangement according to claim 1 , wherein the average froth transport distance (dtr) is more than 5 cm.
9. The froth flotation arrangement according to claim 1 , wherein the tank comprises at least three separate froth collection launders.
10. The froth flotation arrangement according to claim 9 , wherein the number of overflow lips in the froth collection launders is five.
11. The froth flotation arrangement according to claim 1 , wherein the froth collection launders are positioned in radial direction (r) of the tank.
12. The froth flotation arrangement according to claim 1 , wherein a ratio between the average transport distance (dtr) and a froth collection launder average width (w) in radial direction (r)(dtr/w) is 0.1-0.6.
13. The froth flotation arrangement according to claim 1 , wherein the gas supply comprises a pipe delivering gas to the bottom part of the tank at least partly under the impeller, or a conduit formed to an agitator comprising the impeller.
14. The froth flotation arrangement according to claim 1 , wherein the flotation cell comprises an agitator comprising an impeller and a stator.
15. 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 (A froth ) 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 (h 1 ) 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 (A pulp ), wherein the pump area (A pulp ) is calculated as an average from the cross sectional areas of the tank at the height of the impeller (h 1 ), and a ratio between the available froth surface area and the pulp area (A froth /A pulp ) 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.
16. The froth flotation method according to claim 15 , wherein the ratio between a height (h) from a bottom of the tank to the froth overflow lip of a froth collection launder and the diameter (D) of the tank (h/D) is less than 1.1.
17. The froth flotation method according to 15 , wherein the slurry comprise copper (Cu).
18. The froth flotation method according to claim 17 , wherein the slurry fed to the third flotation cell or a subsequent flotation cell in the series comprises copper (Cu) less than 0.2 weight %.