JPH0633376B2 - Stabilizer for coal slurries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used for improving the fluidity of a fluid fuel produced as a coal water slurry, and for producing a coal water slurry intended to improve storage stability. And a stabilizer for coal slurry for fuel.

[Conventional technology]

For the production of coal water slurry, a dispersant that disperses coal particles in addition to the raw materials coal and water, a dispersant that functions to disperse ash particles contained in coal, and further were produced. Research, development and practical use of many types of additives such as thickeners that increase the storage stability of slurries, antifoaming agents that suppress bubbles generated during production, and preservatives that prevent the decay of slurries. Confirmation is being made. In addition, in the production of coal water slurry, chemicals such as acids and alkalis are used to adjust the pH for the purpose of maintaining the function of dispersant and preventing corrosion of equipment.

As mentioned above, in the manufacture of coal water slurry, various substances are under development for their respective purposes, but the price,
The reality is that it is not yet satisfactory in terms of resource quantity or function.

[Problems to be solved by the invention]

By the way, today, there is a strong demand for the advent of an additive capable of improving the fluidity of a coal water slurry and improving the stability during storage.

Conventionally, as this kind of additive, a so-called thickener is used, and most of the polysaccharides and processed products thereof are used. As typical examples, guar gum, xanthan gum, carboxymethyl cellulose and the like are said to be effective.
For these substances, deterioration due to the action of rotting etc. does not become a problem for a short period of time after production, but over a long period of time, these problems cannot be ignored, and therefore the use of preservatives etc. becomes necessary. Come on.

Unlike the thickeners described above, as a new additive that has a thickening effect but does not worry about spoilage due to bacteria, etc.,
Among the clay, which is an inorganic compound, a method of using attaparadigite, a method of using electrostatic dust ash (EP ash), and the like are shown. Regarding these, attapulgite has a problem that resources are biased even in the world, and EP ash is difficult to control its properties.

〔Purpose〕

From the experience of the present inventors who have adjusted the coal water slurry using various types of coal, coal that has a strong influence of ash in the slurry state and affects its rheological characteristics, and the influence of ash is relatively weak, and coal particles It was found that there are roughly two types of coal that exhibit their own rheological properties. Typical coal brands are Pacific coal and Wampoo coal in the former, and Saxon bale and plateau coal in the latter.
From the experience of the present inventors, coal having a strong influence of ash such as Pacific coal can be controlled by using additives such as polycarboxylic acid and polyphosphoric acid that increase the fluidity of ash. On the other hand, in the case of coal such as Saxon Bale coal, which is less affected by ash, the fluidity of the slurry must be improved by increasing the viscosity in order to maintain its storage stability.

From a slurry having a strong influence of ash, such as Pacific coal in the test of the present inventors, an aqueous solution containing fine mineral matter obtained by an oil-addition granulation method is used to produce a coal having a small influence of ash, such as Saxon bale coal. The prepared water slurry was a highly stable slurry that gave a higher apparent clay in the low shear rate region than the coal water slurry prepared using city water. From various studies conducted to find the cause, it was found that one of the reasons is that clay particles dispersed in a colloidal form affect the rheology of the slurry if it is present in a certain amount or more. Based on this phenomenon, the present invention has been completed as a result of repeated studies on the identification of a substance capable of controlling the rheological properties of a coal water slurry and the adjustment method thereof. That is, the object of the present invention is to
To improve the fluidity of the coal water slurry, to provide a stabilizer for fuel coal slurry that can improve stability during storage, and another object of the present invention is to use saxon bale coal or It is an object of the present invention to provide a stabilizer for coal slurry for fuel, which can improve the fluidity necessary for this coal water slurry for coal such as plateau charcoal which is less affected by ash.

[Means for solving problems]

And, as a means for achieving the above object, the present invention is to use an aqueous suspension of a montmorillonite clay mineral as a stabilizer for coal slurry for fuel. That is,
The present invention relates to a stabilizer for a coal slurry for fuel, which is characterized by comprising a crushed product or a ground product of a natural or artificial montmorillonite-based clay mineral suspended in water and a suspension aqueous solution of the montmorillonite-based clay mineral. is there.

As the stabilizer for a coal slurry for fuel of the present invention, montmorillonite clay minerals such as montmorillonite and hectorite, which can be suspended in water as a colloid by dispersion, are effective. By the way, it is desirable that the particle size of the colloidal clay mineral is about 2 μm or less. The stabilizer for a coal slurry for fuel of the present invention is a clay clay (basic clay) to which a montmorillonite clay mineral is added, and a clay colloid of 2 μm or less swollen with a medium (water) is used to improve the clay characteristics of water. By adjusting it, the fluidity of the slurry is improved and a stable slurry is obtained.

In the present invention, it is composed of a suspension aqueous solution of the clay mineral described above, it is possible to use a concentrate obtained by separating the clay mineral from the suspension aqueous solution, in the case of this separation,
It is preferable to use a compound obtained by adding a compound of an alkaline earth metal, for example, a compound such as calcium or magnesium, separating the clay mineral in the presence of this compound, and concentrating it.
This is for substituting alkali metal ions such as sodium and potassium contained in clay minerals with alkaline earth metals such as calcium and magnesium, which results in the content of alkali metals not preferable as fuel. Can be reduced.

Further, as shown in the examples, the stabilizer of the present invention has a sufficient effect at an addition amount of about 0.1% with respect to the amount of slurry, does not adversely affect the performance as a fuel, and is used for fuel coal slurry. It is suitable as a stabilizer.

Hereinafter, the present invention will be described in more detail with reference to examples.

(Example 1) Bentonite containing montmorillonite as a main component,
It is also marketed in Japan as a soil conditioner. This commercial bentonite is finely pulverized with a dry ball mill, and bentonite is collected so as to be an aqueous solution of about 10% based on air-dried bentonite. First, in order to facilitate the dispersion operation, this bentonite is adjusted to pH 8-9 with NaOH or the like. After making a paste with the adjusted aqueous solution, it was adjusted with NaOH, KOH or NH ₄ OH
The suspension was suspended in a dilute aqueous alkaline solution having a pH of 8 to 9 to precipitate quartz and other substances contained in bentonite, and a supernatant suspension was prepared. At this time, the particle size of the solid content in the suspension was 2μ or less and 63.3%. The clay mineral concentration in this suspension was determined by the remaining amount after ashing and burning at 800 ° C.

The above-mentioned suspension when preparing a coal water slurry with a coal concentration of 65%, which is produced by using pulverized coal of Saxon Bale coal from Australia and sodium salt of formalin condensate of naphthalene sulfonate (NSF ・ Na) which is an anionic additive. The result when a liquid is used together is shown. Fig. 1 shows a comparison of the rheological measurement examples of a coal water slurry prepared by adding a suspension adjusted to an ash concentration of 0.2% in the slurry and one without addition. is there. In FIG. 1, curve (1) shows the rheology of the added slurry, and curve (2) shows the rheology of the non-added slurry. From the comparison of both curves in Fig. 1, the effect of addition is to increase the viscosity of the slurry without increasing the hysteresis (size of the area in the graph) indicated by the difference between the up and down curves of the rheology curve. Is. This thickening effect has a good effect on the storage stability of the slurry. These prepared slurries were stored in a glass cylinder, and the results of comparing and comparing the coal particle deposition status by the rod penetration method are shown in Table 1. The addition of suspended clay particles stabilizes the storage of coal water slurries. It is clear that it contributes to.

(Example 2) A case in which the suspension supernatant of bentonite obtained by the operation of Example 1 is used by separating and concentrating the clay particles by a centrifugal separation operation and confirming its effect will be described. The purpose of this operation is to confirm the concentration operation for easy handling as a stabilizer, and further replace the alkali metal ions such as sodium and potassium contained in the clay particles with alkaline earth metals such as calcium and magnesium. However, it is expected to reduce the content of undesired alkali metals in the fuel additive.

Calcium hydroxide was added to the supernatant to a concentration of 10% to replace the alkali metal in the pentonite with an alkaline earth metal, and then separated by centrifugation to obtain a deposit as a water-containing paste. Example 1 using a thing
Table 2 shows the results of examining the storage stability of a water slurry of Saxon Pale charcoal prepared by the same operation. It is clear that the stability is improved compared to the additive-free slurry shown in Table 1. Almost the same results as those obtained with calcium were obtained for a magnesium salt which is an alkaline earth metal other than calcium or a mixture of calcium and magnesium.

(Example 3) The suspension supernatant of bentonite obtained by the operation of Example-1 was separated and concentrated by a centrifugation operation and then dried at 105 ° C for 4 hours to obtain a solid content. This solid content is 800 ℃
The weight loss after high temperature drying at 85% was between 85 and 90% of the original sample. As a guideline for the remaining amount at the time of high temperature drying, CW
After the production of M, the storage test of CWM added so that the concentration in water after production was as shown in Table 3 was conducted. The results are shown in Table 3 in comparison with the case of no addition, and it is clear that the storage stability of the slurry is effective even if the clay particles are taken out as a solid content and used.

From the above-mentioned Examples 1 to 3, it has been confirmed that the fine montmorillonite clay mineral particles prepared by the pulverization and suspension operations are effective substances effective for stabilizing the coal water slurry for fuel.

〔effect〕

The present invention, as described in detail above, by adding a suspension of a clay mineral obtained by suspending a crushed product or a ground product of a natural or artificial montmorillonite clay mineral in water to a coal slurry for fuel, The fluidity of the coal slurry is improved, and the stability during storage is improved, resulting in a remarkable effect.

[Brief description of drawings]

FIG. 1 is a diagram showing the results of rheology measurement when a montmorillonite clay mineral suspension was added to a coal water slurry (curve 1) and when it was not added (curve 2).

Claims (3)

[Claims] 1. A stabilizer for a coal slurry for a fuel, comprising a crushed or ground product of a natural or artificial montmorillonite-based clay mineral suspended in water and an aqueous suspension solution of the montmorillonite-based clay mineral. . 2. The stabilizer for a fuel coal slurry according to claim 1, which comprises a composition of a montmorillonite clay mineral separated and concentrated from a suspension aqueous solution of a montmorillonite clay mineral as a main component. 3. A natural or artificial montmorillonite clay mineral suspension aqueous solution is added with a compound of an alkaline earth metal to ion-exchange the alkaline metal in the clay mineral and then the suspension. The above-mentioned claim 1 or 2 which has a composition of an alkaline earth metal-substituted montmorillonite clay mineral separated and concentrated from an aqueous solution as a main component.
Item 6. A stabilizer for coal slurry for fuel according to the item.