Methods of enhancing fine particle dewatering
First Claim
1. A process for dewatering a slurry of hydrophobic coal particulate material comprising:
- i) forming a layer of hydrophobes on the surface of said hydrophobic coal particulate material and initially increasing the hydrophobicity of said hydrophobic coal particulate material by adding hydrocarbon oil to said slurry, wherein the hydrophobicity of said coal particulate material is increased;
ii) adding a nonionic surfactant of hydrophile-lipophile balance (HLB) number less than 15 dissolved in at least one organic solvent;
iii) allowing said nonionic surfactant to adsorb on less hydrophobic parts of the surface of said hydrophobic coal particulate material to further increase hydrophobicity of said hydrophobic coal particulate material having increased hydrophobicity from the addition of said hydrocarbon oil; and
iv) effecting separation of water from said slurry of hydrophobic coal particulate material by subjecting said slurry to a mechanical method of dewatering.
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Abstract
A new method of improving the process of dewatering fine particulate materials is disclosed. In this method, an aqueous slurry of fine particles is treated with appropriate hydrophobizing reagents so that the particulate material becomes moderately hydrophobic with its water contact angle considerably below 90°. A low hydrophile-lipophile balance (HLB) number surfactant is then added to the slurry, so that the surfactant molecules adsorb on the moderately hydrophobic surface primarily by hydrophobic attraction and, thereby, increase its contact angle close to or above 90°. By virtue of the greatly enhanced hydrophobicity, the water molecules adhering to the surface are destabilized and removed more readily by a mechanical dewatering process. Any nonionic surfactant with its HLB number below about 15 may be used for the hydrophobicity enhancement. The surfactants may be used in conjunction with appropriate solvents such as light hydrocarbon oils and short-chain alcohols. The moisture reduction can be further improved by using appropriate electrolytes in conjunction with the low HLB surfactants, spraying surface tension lowering reagents onto the filter cake, subjecting the cake to a suitable vibratory means, and by using combinations thereof.
47 Citations
17 Claims
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1. A process for dewatering a slurry of hydrophobic coal particulate material comprising:
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i) forming a layer of hydrophobes on the surface of said hydrophobic coal particulate material and initially increasing the hydrophobicity of said hydrophobic coal particulate material by adding hydrocarbon oil to said slurry, wherein the hydrophobicity of said coal particulate material is increased; ii) adding a nonionic surfactant of hydrophile-lipophile balance (HLB) number less than 15 dissolved in at least one organic solvent; iii) allowing said nonionic surfactant to adsorb on less hydrophobic parts of the surface of said hydrophobic coal particulate material to further increase hydrophobicity of said hydrophobic coal particulate material having increased hydrophobicity from the addition of said hydrocarbon oil; and iv) effecting separation of water from said slurry of hydrophobic coal particulate material by subjecting said slurry to a mechanical method of dewatering. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A process for dewatering a slurry of hydrophobic coal particulate material comprising:
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forming a layer of hydrophobes on the surface of said hydrophobic coal particulate material and initially increasing the hydrophobicity of said hydrophobic coal particulate material by adding hydrocarbon oil to said slurry, wherein said hydrophobic coal particulate material exhibits a contact angle and the contact angle of said hydrophobic coal particulate material is below 45°
;dissolving a nonionic surfactant of hydrophile-lipophile balance (HLB) number less than 15 in at least one organic solvent; adding said dissolved nonionic surfactant and said at least one organic solvent to said slurry; and allowing said nonionic surfactant to adsorb on less hydrophobic parts of the surface of said hydrophobic coal particulate material, to further increase the hydrophobicity of said material having increased hydrophobicity from the addition of said hydrocarbon oil, wherein said contact angle of said hydrophobic coal particulate material is above 45°
; andeffecting separation of water from said slurry of hydrophobic coal particulate material by subjecting said slurry to a mechanical method of dewatering. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A process for dewatering a slurry of superficially oxidized coal particles, comprising:
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i) initially regenerating the hydrophobic surface of said oxidized coal particles, ii) forming a layer of hydrophobes on the surface of said hydrophobic coal particulate material and increasing the hydrophobicity of said coal particles by adding hydrocarbon oil to said slurry, ii) adding a non-ionic surfactant of hydrophile-lipophile balance (HLB) number less than 15 dissolved in at least on organic solvent; iii) allowing said non-ionic surfactant to adsorb on less hydrophobic parts of the surface of said coal particles, to further increase the hydrophobicity of said coal particles having increased hydrophobicity from the addition of said hydrocarbon oil; and iv) effecting separation of water from said slurry of hydrophobic particulate material by subjecting said slurry to a mechanical method of dewatering. - View Dependent Claims (17)
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Specification