SU1545947A3 - Coal-water suspension - Google Patents

Abstract

Coal water mixtures are provided which contain a poly(alkylene oxide) surfactant comprised of a hydrophilic portion derived from ethylene oxide and a hydrophobic portion derived from a higher alkylene oxide as a surfactant and a hydroxyalkyl ether of a polygalactomannan as a stabilizer. Particular examples of these surfactants and stabilizers include ethoxylated, propoxylated propylene glycol and hydroxypropyl guar, respectively. It has been found that coal water mixtures containing from 50 to 80% particulate coal exhibit excellent stability with respect to particle settling and bed compaction when this particular combination of surfactant and stabilizer is employed. Also provided is a process for preparing such coal water mixtures wherein a mixture of particulate coal, water, and the surfactant is formed to which the stabilizer is then added to form a stabilized homogeneous mixture. These coal water mixtures exhibit excellent stability when transported by a pipeline.

Description

The invention relates to water suspension suspensions and may find application in the power industry.

The aim of the invention is to improve the static stability of the slurry.

Example 1 (comparative). Initially, a coal-water slurry (BEAD) is prepared without the addition of formaldehyde or hydroxypropyl ether of polygalactomannan. The MAS is prepared by loading materials into a ball mill and mixing them until 83 wt.% Of the particles pass through a 200-mesh (70 micron) Tyler sieve. The ingredients are mixed in the following ratios, wt.%:

Bituminous coal70

Ethoxylated nonylphenol surfactant (CO 990 uchepal) 0.55

Hydrocarbon-based antifoam 0.30 Water 29.15 After reducing the particle size by grinding, the MAS is then divided into four equal samples and 0.05 wt.% Formaldehyde is added as a protective substance to each sample. Polygalactomannan hydroxypropyl ether is added to three of the samples (OaJactosol 416; Menkel Corp) in the amounts indicated in the table. one.

A rheometer is used to determine the initial apparent viscosity (shear stress divided by shear rate at a shear setting of 57.6). After determining the apparent viscosity, all four samples are placed in stationary storage under normal conditions for 8 weeks. After the expiration of this storage time, the amount of dense

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the residue accumulated at the bottom of the vessel by immersing a 6-inch metal ruler. The ruler passes through the suspension under gentle pressure with the hand until a solid precipitate is determined. When the level of solid precipitate is reached, the penetration depth is read from the ruler. The amount of sediment is determined as a percentage of the total weight of the sample: (h0 - h) h0 100 g, where hc is the total weight of the sample in the container; h is the depth of the non-settled and loose material.

Table 1

polygalactomannan propyl ether (galactosol 416) in the amounts indicated in Table. 2

After determining the apparent viscosity, all four samples are placed in stationary storage under normal conditions for 8 weeks. After this storage time has expired, the amount of dense residue accumulated at the bottom of the vessel is determined.

table 2

Example 2 WU was initially prepared without the addition of formaldehyde or polygalactomannan hydroxypropyl ether. The main VUS is prepared by loading materials into a ball mill and mixing until 83% by weight of the particles pass through a 200-mesh Tyler sieve. Ingredients are mixed in the following ratios, May.%:

Bituminous coal70

Eloxol copolymer of ethnlenoxide and propylene oxide (pluronic F98) 0.55

Colloid defoamer 6910.3 Water Up to 100 Antifoam is a mixture of mineral oil, amide and ether.

After reducing the particle size by grinding, the MAS is divided into 4 equal samples, and 0.0 G% by weight formaldehyde is added to each sample as a washer. Hydroxy is added to three of the samples.

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Example 3. The ingredients are mixed in the following ratios, wt.%:

Coal (cedar steam coal, crushed to 90% with a size of 200 mesh on a standard Tyler pass) 65.00 Water (deionized) 34.0

Surfactant (Pluronic F98) 0.40

Antifoam (colloid 691) 0.35 G of a rock with the polypalactomannan ether (galactosol 416) 0.10 Formaldehyde (37%) 0.15 surfactant (Pluronic F98) is a block copolymer of ethylene oxide and propylene oxide. The block copolymer has the following structural formula:

he (ch7sn7o) a (ch (sna)) s ()) ssn.

where a, b and c are full integers, with a and c jointly at least 100. The block copolymer used has a molecular weight of 130,000 and contains 80% by weight of ethylene oxide, in which the number of ethylene oxide units is 235,

The charcoal slurry is prepared as follows.

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The surfactant is thoroughly treated with water and the solution is placed on a rod mill. A defoamer and particulate coal are added to this solution. The mill is hermetically sealed and grinded for 2 hours to effect complete dispersion of the coal. In an aliquot of a VAS manufactured in this way, stabilizer additives are introduced in powder form using paddle mixers at a speed of 4-800 rpm. Stirring is continued for 30 minutes. After static aging for 16 g 24 h, the mixture is again stirred for 30 min by means of a paddle stirrer.

Viscosity at 100 s 2.07 Pa ss.

Viscosity viscosity

Brookfield, Pa. with

rpm:

79.2 56.3 33.0 23.5 18.1

After 4 weeks of static aging, it was found that there was no solid precipitate and there was only 1–2 wt.% Soft sediment at the bottom of the container. The composition in which the xanthan biopolymer replaced the hydrochloride ester of polygalactomannan had the same amount of residue but was not so fluid. When changing only the type of surface 45947

active substance, i.e. when replacing the surfactant with igépal CO 990 (non-nphenoxy-polyethylene-ethanol and ethanol), the static stability during storage is significantly deteriorated compared with the above composition. Thus, it is the combination of a block copolymer, ethylene oxide and propylene oxide and hydroxypropyl propyalactomannan that provides both good flowability and stability.

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Claims (1)

Invention Formula A coal-water suspension containing coal, a surfactant based on an oxyalkylated product, pengasifier and water, characterized in that, in order to improve static stability, the suspension contains a block copolymep of ethylene oxide and propylene oxide and, in addition, hydroxypropyl polygalactomannan ether and formaldehyde in the following ratio, wt.%: 0 five Coal Ethylene oxide and propylene oxide block copolymer Poly-galactomannan hydroxypropyl ether Formaldehyde Antifoam Water 65 or 70 0.4 or 0.55 0.05 - 0.1 0.05 or 0.15 0.3 or 0.35 Else