Method of agglomerating fine particles using a concentrated water in oil emulsion
A method of agglomerating fine particles such as ultrafine coal in a beneficiation process, uses a water in oil emulsion to significantly reduce the amount of oil needed compared with known oil in water emulsions. A solution of oil and emulsifying agent is provided to which water is progressively added forming a concentrated water in oil emulsion with stabilized water drops ( 1 ) packed inside the oil solution phase ( 2 ). Fine particles in a slurry are then added, causing the fine particles to collide and stick to the emulsion particles. An optional form of the invention coats tiny portions of the emulsion in a thin film of low viscosity oil ( 5 ) to achieve a higher level of selectivity.
1. A method of agglomerating fine particles including the steps of:
providing a solution of oil and emulsifying agent,
progressively dispersing water into said solution, and forming a concentrated water in oil emulsion with stabilized water drops packed inside the oil phase, the emulsion comprising a highly viscous, sticky oil-like medium and having a homogeneous appearance, and
adding the concentrated water in oil emulsion to a slurry of fine particles, wherein the sticky oil-like medium acts as a binding agent, causing the fine particles to collide and stick to the sticky oil-like medium, thereby agglomerating at least a portion of the fine particles from the slurry while keeping the stabilized water drops within the oil phase.
2. A method as claimed in claim 1 , further comprising the step of adding the concentrated water in oil emulsion to a larger volume of agitated water until the concentrated water in oil emulsion is dispersed into the larger volume.
3. A method as claimed in claim 2 , wherein the fine particles are liquid particles.
4. A method as claimed in claim 2 , wherein the concentrated water in oil emulsion is dispersed into smaller portions of concentrated water in oil emulsion surrounded by the larger volume of water.
5. A method as claimed in claim 4 , wherein the fine particles are liquid particles.
6. A method as claimed in claim 1 , wherein the fine particles are solid fine particles.
7. A method as claimed in claim 6 , wherein the fine particles are fine coal particles.
8. A method as claimed in claim 6 , wherein the fine particles are mineral particles.
9. A method as claimed in claim 1 , wherein the fine particles are liquid particles.
10. A method as claimed in claim 1 , wherein the concentrated water in oil emulsion has a water volume fraction greater than 0.75.
11. A method as claimed in claim 10 , wherein the water volume fraction is greater than 0.9.
12. A method as claimed in claim 1 , wherein tiny portions of the stabilised water drops packed inside the oil phase in the concentrated water in oil emulsion are coated with a new thin film of low viscosity oil, reducing the stickiness and increasing the hydrophobicity of the sticky oil-like medium.
13. A method as claimed in claim 1 , wherein a chemical collector or gas bubbles are attached to the surface of the fine particles to improve hydrophobicity.
14. A method as claimed in claim 1 , wherein gas bubbles are added to the oil solution to form a foam-like binding agent.
15. A method as claimed in claim 1 , wherein the agglomerated fine particles stuck to the sticky oil-like medium float to the surface of the water for easy removal.
16. A method as claimed in claim 1 , wherein the agglomerated fine particles stuck to the sticky oil-like medium are passed over a screen to dewater and/or deslime the agglomerates.
17. A method as claimed in claim 1 , wherein said slurry is an aqueous slurry.
18. The method of claim 1 , wherein the concentrated water in oil emulsion is hydrophobic and wherein the fine particles are hydrophobic.
19. A method of agglomerating fine particles including the steps of:
providing a solution of oil and emulsifying agent,
progressively dispersing water into said solution, and forming a concentrated water in oil emulsion with stabilized water drops packed inside the oil phase, the emulsion comprising a highly viscous, sticky oil-like medium and having a homogeneous appearance, and
adding a slurry of fine solid particles in a slurry to the concentrated water in oil emulsion, wherein the sticky oil-like medium acts as a binding agent, causing the fine particles to collide and stick to the sticky oil-like medium while keeping the stabilized water drops within the oil phase, thereby agglomerating at least a portion of the fine particles from the slurry and separating at least a portion of the fine particles from the slurry.
20. A method of agglomerating fine particles including the steps of:
providing a solution of oil and emulsifying agent,
progressively dispersing water into said solution, and forming a concentrated water in oil emulsion with stabilized water drops packed inside the oil phase, the emulsion comprising a highly viscous, sticky oil-like medium and having a homogeneous appearance, and
adding a slurry of fine particles to the concentrated water in oil emulsion, wherein the sticky oil-like medium acts as a binding agent, causing the fine particles to collide and stick to the sticky oil-like medium without releasing the stabilized water drops from within the oil phase, thereby agglomerating at least a portion of the fine particles from the slurry.