Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Patent
1994-12-01
1996-08-13
McCarthy, Neil
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
210732, 210778, 209 5, C02F 1114, C02F 154
Patent
active
055453325
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a process for dewatering fine-particle solids dispersions, in which internal hydroxy mixed ethers are used as auxiliaries.
BACKGROUND OF THE INVENTION
Large quantities of fine-particle solids of high water content accumulate in numerous branches of industry, for example in mining or in sewage treatment plants, and have to be dewatered before further processing or disposal as waste. For example, the dewatering of water-containing hard coal or coke is a central process in the preparation of coal-based fuels. It is often difficult to keep to the upper limits dictated by the market for the water content of these materials, for example because mined hard coal accumulates in very fine-particle form by virtue of the substantial mechanization of underground coal mining. At the present time, around 38% of mine-run coal consists of fine coal with particle diameters ranging from 0.5 to 10 mm; a further 14% consists of very fine coal with even smaller particle diameters.
RELATED ART
It is known that certain surfactants are suitable as auxiliaries for removing water from water-containing fine-particle solids suspensions, more particularly quartz sands or hard coals, so that the residual water content can be reduced. Surfactant-based dewatering aids of the type mentioned above, which have already been described include, for example, dialkyl sulfosuccinates [U.S. Pat. No. 2,266,954] and nonionic surfactants of the fatty alcohol polyglycol ether type [Erzmetall 30, 292 (1977)]. However, these surfactants are attended by the disadvantage that they foam to a considerable extent which gives rise to serious problems, particularly because the water is normally circulated in the preparation plants.
DE-A1-39 18 274 (Henkel) describes alkyl-terminated .beta.-hydroxyalkyl ethers, so-called hydroxy mixed ethers, which are obtained by ring-opening of .alpha.-olefin epoxides with fatty alcohol ethoxylates and are used as low-foaming auxiliaries in the dewatering of solids suspensions. Although good results are obtained with these auxiliaries in the dewatering of solids, they have the disadvantage of unsatisfactory low-temperature behavior. Crystal formation can occur at temperatures of only 15.degree. to 20.degree. C., particularly where the auxiliaries are stored outside, with the result that the pumpability and flow behavior of the products deteriorate and their intended use is thus seriously impaired.
Accordingly, the problem addressed by the present invention was to provide hydroxy mixed ethers which would show improved low-temperature behavior for the same performance properties.
BRIEF DESCRIPTION OF THE INVENTION
The present invention relates to a process for dewatering fine-particle solids suspensions, in which internal hydroxy mixed ethers corresponding to formula (I) ##STR2## in which R.sup.1 represents a linear hydroxy alkyl group containing from 2 to 16 carbon atoms with the hydroxyl group bonded to the carbon atom adjacent to the carbon atom with the ether linkage; and with the proviso that the sum of the total number of carbon atoms in R.sup.1 and R.sup.2 is 5 to 17, carbon atoms and
It has surprisingly been found that, by comparison with the known terminal hydroxy mixed ethers according to DE-A-39 18 274, the internal hydroxy mixed ethers to be used in accordance with the invention show distinctly better low-temperature behavior, more particularly lower solidification points, and equally good and, in some cases, even slightly improved performance properties.
DETAILED DESCRIPTION OF THE INVENTION
Internal hydroxy mixed ethers can be obtained similarly to terminal hydroxy mixed ethers by ring opening of internal olefin epoxides with fatty alcohol ethoxylates or glycols. Particulars of the synthesis can be found in DE-A1-37 23 323 (Henkel).
Internal hydroxy mixed ethers suitable for use in accordance with the present invention are ring opening products of internal olefin epoxides containing 6 to 18 carbon atoms with ethylene glycol, diethylene glycol and its hig
REFERENCES:
patent: 2266954 (1941-12-01), Bonnet et al.
patent: 4925587 (1990-05-01), Schenker et al.
patent: 5215669 (1993-06-01), Koester et al.
Daute Peter
Koester Rita
Stoll Gerhard
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
McCarthy Neil
Ortiz Daniel S.
Szoke Ernest G.
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