JPH069972A - High concentration coal-water slurry additive - Google Patents

Abstract

(57) [Summary] [Structure] The polymerization molar ratio of sulfonated styrene and maleic acid is 4/1 to 50/1, and the weight average molecular weight is 3,000.
An additive for a high-concentration coal-water slurry containing as an essential component a sulfonated styrene-maleic acid copolymer of 50,000 to 50,000 or a salt thereof. [Effects] By using the additive of the present invention, a coal-water slurry having a high coal concentration and maintaining stable and self-fluidity for a long period of time can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an additive for a coal-water slurry, and more particularly, to obtain a high-concentration coal-water slurry which can be pumped and used as it is, for example, as a boiler fuel in power plants. Of additives.

[0002]

2. Description of the Related Art In recent years, the utilization of coal has been re-recognized due to depletion of petroleum resources and soaring prices, and various utilization methods have been studied. However, coal is solid and cannot be pumped as it is.
Therefore, attention is paid to an aqueous slurry of pulverized coal that can be pumped and can be directly burned as a fuel for a boiler in a power plant or the like. However, when coal and water slurries are produced without using chemicals, the viscosity of the slurries increases, so that it is not possible to produce water slurries with a high coal concentration. If the coal concentration is low, the transportation efficiency is lowered, and further, a dehydration step is required before combustion, which is expensive. Therefore, research has been conducted on a thinning agent that lowers the viscosity of a high-concentration coal-water slurry.

Conventionally, as these thickeners, a naphthalenesulfonic acid formalin condensate salt (Japanese Patent Laid-Open No. 216-216) has been used.
36), copolymers of acrylic acid or methacrylic acid with other vinyl monomers (JP-A-56-57890), polystyrene sulfonates and copolymers of other vinyl monomers (JP-A-57-145187). ), A copolymer containing a vinyl monomer having an alkylene oxide chain (JP-A-62-121789), and ligninsulfonic acid (JP-A-58-45287).

Further, JP-A-58-42694 and JP-A-61-212296 describe salts of sulfonated styrene-maleic acid copolymers, which are salts of sulfonated styrene and maleic acid. The polymerization molar ratio is 3/1 or less.

Although all of the above-mentioned thickeners have corresponding effects, they are still insufficient in terms of high concentration and long-term stability of the slurry.

[0006]

The present invention has been made by paying attention to such conventional problems. That is,
The present invention has a polymerization molar ratio of sulfonated styrene and maleic acid of 4/1 to 50/1 and a weight average molecular weight of 3,000.
It is an additive for high-concentration coal-water slurries containing a sulfonated styrene-maleic acid copolymer or a salt thereof of 50,000 to 50,000 as an essential component.

The sulfonated styrene-maleic acid copolymer or a salt thereof used in the present invention has a polymerization molar ratio of sulfonated styrene and maleic acid in the range of 4/1 to 50/1 and a weight average molecular weight of 3. Those in the range of 1,000 to 50,000 are effective. Outside this range, the dispersibility and stability of the coal-water slurry deteriorate. Also,
The sulfonation rate is 60 to 100% with respect to the styrene skeleton
Is preferred. If the sulfonation rate is less than 60%,
Hydrophilicity is insufficient and the dispersibility of the coal-water slurry deteriorates.

The sulfonated styrene-maleic acid copolymer or salt thereof of the present invention can be obtained by sulfonation of a styrene- (anhydrous) maleic acid copolymer with a sulfonating agent. Alternatively, it can be obtained by previously copolymerizing sulfonated styrene sulfonic acid and maleic acid.

When styrene- (anhydrous) maleic acid copolymer is sulfonated, sulfuric acid, fuming sulfuric acid, sulfuric anhydride, and chlorosulfonic acid can be used as the sulfonating agent. By using these, sulfonation is carried out under normal conditions, then neutralization is carried out, and, if necessary, an inorganic salt is removed, whereby the intended product can be obtained.

The counterion of the acid which constitutes the salt of the copolymer includes alkali metals such as Li, K and Na, and Ca and Mg.
Alkaline earth metals such as NH ₃ and amines are used, but K, Na and NH ₃ are preferable.

The coal used in the coal-water slurry may be any coal, such as anthracite, bituminous coal, sub-bituminous coal, lignite or clean coals thereof. Here, clean coal is obtained by removing inorganic substances such as ash and sulfur from the coal.
As a cleaning method, for example, a heavy liquid separation method,
Oil aggregation method (Oil Agglomeration method),
There are floating coal preparation methods, etc., but other clean coal methods can also be used.

Since the effect of the additive of the present invention does not depend on the particle size of the target coal, the particle size of the coal in the water slurry is also arbitrary, but the pulverized coal used in the present thermal power plants is Since the passing amount through a 200-mesh screen is 70% or more, this particle size is an approximate guide.

When the coal-water slurry is prepared by the wet method, the additive of the present invention may be added all at once from the beginning, or may be added dividedly during the preparation. Alternatively, it may be added after the preparation of the coal-water slurry. In addition, a method in which coal and water are put in a crusher to produce a low-concentration slurry, which is then added to a dehydrated and concentrated product and mixed is also useful. However, the idea of the present invention is not related to these specific preparation methods, and it is sufficient if the additive is finally dissolved or dispersed substantially uniformly in the slurry, so any slurry production method should be adopted. You can

The additive may be used in an amount of 0.03 to 2% by weight with respect to the coal-water slurry. If it is less than 0.03% by weight, its effect is small and if it exceeds 2% by weight, the amount of the additive is changed. There is no matching effect.

The fluidity limit of the coal-water slurry varies depending on the type and particle size of the coal, but generally the fluidity is lost at a coal concentration of about 50% by weight unless an additive is used.
However, when the additive of the present invention is used, the viscosity is remarkably lowered, so that the additive has fluidity even when the coal concentration is 60% by weight or more.

Further, there is no change with time in the slurry,
If the additive is not used, settling starts from several hours after standing, but if the additive of the present invention is used, a stable coal-water slurry can be obtained for one month or more. Furthermore, the viscosity hardly increases with time.

The additive of the present invention has a practical constituent raw material and can be produced extremely economically, so that it makes a coal-water slurry practical.

[0018]

[Examples] The effects of the additive of the present invention are shown below by Examples and Comparative Examples, but the present invention is not limited thereto.

Using the additives shown in Table 1 and the coal shown in Table 2, a coal-water slurry was produced by the method shown below.
The coal used was coarsely crushed in advance with a dry mill to a particle size of 3 mm or less.

[Coal-Water Slurry Production Method] A predetermined amount of coarsely crushed coal (particle size of about 3 mm or less), water and additives are put into a ball mill so that the ratio is as shown in Table 3, and 200 mesh sieve is used. The coal was crushed until the passage amount of 80% was 80%.

The produced slurry was evaluated by the following test methods. The evaluation results are shown in Table 3. (1) Slurry viscosity: measured at 25 ° C. using a Haake rotary viscometer at a shear rate of 100 sec ⁻¹ . (2) Life of slurry: 250 ml of manufactured slurry
The mixture was placed in a wide-mouthed bottle having a capacity of 1 month, and allowed to stand for 1 month. Then, the slurry was discharged from the bottle by gravity dropping and passed through a sieve having an opening of 1 mm. At this time, the weight remaining in the bottle and the weight of the slurry on the sieve were measured as the amount of aggregation, and the aggregation rate (%) with respect to the total weight of the slurry was determined. Further, the viscosity of the slurry after standing for 1 month was also measured. The smaller the agglomeration rate and the closer the viscosity is to that immediately after production, the better the slurry has the longer life.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

As is clear from Table 3, the slurry containing the additive of the present invention has a low viscosity immediately after the production, and the viscosity hardly rises even after standing for 1 month, and is good.

On the contrary, in the case of Comparative Example, the slurry viscosity was high immediately after the production and the physical properties of the slurry were deteriorated even after standing for 1 month.

[0027]

EFFECTS OF THE INVENTION By using the additive of the present invention, coal having a high coal concentration and maintaining stable and self-fluidity for a long period of time can be used.
A water slurry is obtained.

Claims (2)

[Claims] 1. A polymerization molar ratio of sulfonated styrene and maleic acid is 4/1 to 50/1 and a weight average molecular weight is 3,0.
An additive for high-concentration coal-water slurries, which contains a sulfonated styrene-maleic acid copolymer or a salt thereof having an amount of 00 to 50,000 as an essential component. 2. The high-concentration coal-water slurry according to claim 1, wherein the sulfonation ratio of the sulfonated styrene-maleic acid copolymer or a salt thereof is 60 to 100% with respect to the styrene skeleton. Additives.