Methods of enhancing fine particle dewatering

• US 6,855,260 B1
• Filed: 06/07/1999
• Issued: 02/15/2005
• Est. Priority Date: 06/07/1999
• Status: Expired due to Term

• Current Assignee: Roe-Hoan Yoon
• Original Assignee: Roe-Hoan Yoon
• Inventors: Yoon, Roe-Hoan
• Primary Examiner(s): Hruskoci, Peter A.
• Application Number:
  US09/327,266
• Time in Patent Office: 2,080 Days
• Field of Search: 446/26, 209/5, 343/38, 343/48, 343/49, 210/725, 210/727, 210/728, 210/729, 210/732, 210/770, 210/772, 210/777, 210/771, 210/748, 210/778
• US Class Current: 210/727
• CPC Class Codes: B03D 1/08 Subsequent treatment of concentrated product froth dispersion B01D19/02
• CPC Class Codes: C02F 1/26 by extraction
• CPC Class Codes: C02F 11/147 using organic substances C02F11/148 takes precedence
• CPC Class Codes: C02F 2103/10 from quarries or from mining activities
• CPC Class Codes: C02F 2301/063 Underpressure, vacuum
• CPC Class Codes: C10L 5/04 Raw material of mineral origin to be used; Pretreatment thereof pretreatment of fuels of non-mineral origin C10L5/40
• CPC Class Codes: F26B 2200/18 Sludges, e.g. sewage, waste, industrial processes, cooling towers
• CPC Class Codes: F26B 5/005 by dipping them into or mixing them with a chemical liquid, e.g. organic; chemical, e.g. organic, dewatering aids F26B3/005 takes precedence; using chemical vapours or gases F26B21/14

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.

Claims

1. A process for dewatering a slurry of hydrophilic particulate material comprising:

initially hydrophobizing said material using a surfactant of HLB number grater than or equal to 15;

adding a nonionic surfactant of HLB number less than 15 dissolved in at least one organic solvent;

agitating said slurry to allow for said nonionic surfactant to adsorb on the surface of said initially hydrophobized material so that its hydrophobicity is further increased; and

subjecting the agitated slurry containing said material to a mechanical method of dewatering.

2. The process of claim 1 wherein said particulate material comprises particles of less than 2 mm in size.

3. The process of claim 1 wherein the said mechanical method of dewatering is selected from the group consisting of:

vacuum filtration, pressure filtration, centrifugal filtration, and centrifugation.

4. The process of claim 1 wherein said nonionic surfactant is selected from the group consisting of:

fatty acids, fatty esters, phoshate esters, hydrophobic polymers, ethers, glycol derivatives, sarcosine derivatives, silicon-based surfactants and polymers, sorbitan derivatives, sucrose and glucose esters and derivatives, lanolin-based derivatives, glycerol esters, ethoxylated fatty esters, ethoxylated amines and amides, ethoxylated linear alcohols, ethoxylated tryglycerides, ethoxylated vegetable oils, and ethoxylated fatty acids.

5. The process of claim 4 wherein said nonionic surfactant is blended with an oil of vegetable origin.

6. The process of claim 1 wherein said organic solvent includes a solvent selected from the group consisting of:

light hydrocarbon oils and short-chain alcohols.

7. The process of claim 6, wherein said light hydrocarbon oils are selected from diesel oil, kerosene, gasoline, petroleum distillate, turpentine, naphtanic oils, and oils of vegetable origin.

8. The process of claim 6, wherein said short-chain alcohols have carbon atom numbers less than eight.

9. A process for dewatering a slurry of hydrophilic particulate material comprising:

initially hydrophobizing said material using a surfactant;

adding a nonionic surfactant of HLB number less than 15 dissolved in at least one organic solvent;

agitating said slurry to allow for said nonionic surfactant to adsorb on the surface of said initially hydrophobized material so that its hydrophobicity is further increased; and

subjecting the agitated slurry containing said material to a mechanical method of dewatering, wherein said hydrophilic particulate material is a sulfide mineral and said surfactant that is used for the initial hydrophobization step is a thiol collector.