Underwater mineral dressing methods and systems
Underwater mineral dressing units, systems and methods are provided. Material is milled in a water-immiscible liquid which is heavier than water and lighter than the product material. Gangue material is removed by the milling and floats on the water-immiscible liquid to be removed without further processing. Product containing material sinks and is further milled to remove additional gangue material, until the required level of extraction is achieved. Cascades of milling rolls in the water-immiscible liquid allow ever improving extraction of the product material. The rolls are arranged to regulate material flow through the system to remove floating gangue while directing sinking product material to further processing.
1. An underwater mineral dressing unit comprising:
a vertical vessel comprising at least one pair of a flow compartment and a milling compartment, wherein the flow compartment is positioned above and in fluid communication with a milling compartment; and
a water-immiscible liquid filling the vertical vessel and selected to have a density that is intermediate between lighter gangue material and heavier product material, to float the gangue material and to sink the product material,
wherein the milling compartment comprises grinding rolls configured to receive material from the flow compartment into a volume between the rolls and direct the floating gangue material back to the flow compartment via lateral volumes with respect to the rolls.
2. The underwater mineral dressing unit of claim 1 , comprising a plurality of successive pairs positioned one above the other and in fluid communication, each pair configured to sink the product material to a lower pair and float the gangue material to an upper pair.
3. The underwater mineral dressing unit of claim 1 , wherein the water-immiscible liquid comprises at least one halogenated organic compound.
4. The underwater mineral dressing unit of claim 1 , wherein the water-immiscible liquid exhibits a constant density in the vertical vessel.
5. The underwater mineral dressing unit of claim 1 , wherein the water-immiscible liquid exhibits a downwards increasing density in the vertical vessel.
6. The underwater mineral dressing unit of claim 4 , wherein density differences of the water-immiscible liquid are configured to correspond to a density gradient of the sank product material along the vertical vessel.
7. An underwater mineral dressing system comprising:
at least one underwater mineral dressing unit of claim 1 , further comprising a bottom compartment positioned below and in fluid communication with a bottom milling compartment of the at least one pair, the bottom compartment arranged to receive the sank product material from the bottom milling compartment;
a delivery unit arranged to deliver material to a top Flow compartment of the at least one pair;
a top discharger in fluid communication with the top flow compartment of the at least one pair and arranged to remove the floated gangue material therefrom; and
a bottom discharger in fluid communication with the bottom compartment and arranged to remove the sank product material therefrom.
8. The underwater mineral dressing system of claim 7 , wherein the underwater mineral dressing comprises a plurality of successive pairs positioned one above the other and in fluid communication, each pair configured to sink the product material to a lower pair and float the gangue material to an upper pair.
9. The underwater mineral dressing system of claim 7 , wherein the water-immiscible liquid exhibits a constant density along the vertical vessel.
10. The underwater mineral dressing system of claim 7 , wherein the water-immiscible liquid exhibits downwards increasing densities in the vertical vessel and wherein density differences of the water-immiscible liquid are configured to correspond to a density gradient of the sank product material along the vertical vessel.
11. The underwater mineral dressing system of claim 7 , comprising a plurality of successive underwater mineral dressing units, each unit arranged to deliver the sank product material to a following unit for further milling and separation.
12. The underwater mineral dressing system of claim 11 , wherein successive units employ water-immiscible liquids of increasing density.
13. A method of underwater mineral dressing comprising:
milling delivered material in a water-immiscible liquid selected to have a density that is intermediate between lighter gangue material and heavier product material in the delivered material, to float the gangue material and to sink the product material; and
configuring the milling to receive the delivered material at a central volume and direct the floating gangue material via lateral volumes.
14. The underwater mineral dressing method of claim 13 , wherein the milling is configured to reach a specified milling grade that provides a specified product purity and separation grade.
15. The underwater mineral dressing method of claim 13 , wherein the milling is carried out in a plurality of successive stages, wherein each successive stage is configured to receive sank product material from a previous stage and to float gangue material to the previous stage.
16. The underwater mineral dressing method of claim 13 , further comprising delivering the material, removing floated gangue material from top lateral volumes and removing sank product material from a bottom central volume.
17. The underwater mineral dressing method of claim 13 , further comprising selecting the water-immiscible liquid to exhibit a constant density.
18. The underwater mineral dressing method of claim 13 , further comprising selecting the water-immiscible liquid to exhibit a downwards increasing density.
19. The underwater mineral dressing method of claim 18 , further comprising configuring the vertical density differences of the water-immiscible liquid to correspond to a vertical density gradient of the sank product material.
20. The underwater mineral dressing method of claim 13 , further comprising carrying out the milling in successive units, each successive unit having a heavier water-immiscible liquid than a preceding unit.