Patent Description:
For the purpose of retaining the formability of coal-containing formed products and imparting a strength to the formed products, there have conventionally been used binders of bitumen and the like such as tar, tar residue, asphalt, coal tar pitch and pitches (petroleum pitch) made by distilling asphalt or making asphalt heavy.

For example, PTL1 proposes a coke for a blast furnace, containing much bony coal blended therein, which is a coal-containing formed product using a road tar as a binder.

Further PTL2 proposes a coke for a blast furnace, which is a coal-containing formed product using a petroleum pitch and a distilled tar as binders.

<CIT> describes water absorbent particulate polymers and their uses. Friable aggregates may be made by bonding substantially dry polymer particles with an aqueous liquid and drying the aggregates. These aggregates can be broken down to the individual polymer particles upon mixing with an aqueous medium and thus can have the flow properties of relatively coarse particles and the performance properties of relatively fine particles. They may be soluble and used as flocculants or viscosifiers or binders for, for instance, iron ore pelletisation. Alternatively they may be swellable and insoluble, for instance for converting a sticky particulate mass (such as coal fines filter cake) to a crumbly solid. When pellets are formed by compression moulding from a crumbly solid made by mixing water absorbent polymer particles with a sticky mass of inorganic particles (such as a coal fines filter cake) improved properties are obtained when the absorbent polymer particles are introduced in the form of a dispersion in water-immiscible liquid.

<CIT> discloses use of radiation-induced polymers as friction reducing agents.

<CIT> describes a method for agglomerating mineral ore concentrate comprising the commongling of mineral ore concentrate with a binding amount of a water soluble, high molecular weight polymer. The selected polymer is applied to the mineral ore concentrate either (<NUM>) as a dispersion in a non-aqueous medium or (<NUM>) as a dry powder. The most preferred polymers are water soluble poly(acrylamide) based polymers.

When using the above binder, however, there have been a problems in which the processing cost becomes high, etc., since in order to retain the formability of a formed product and impart a strength to the formed product, it is necessary to raise the concentration of the binder to be added with respect to the total amount of the formed product.

Further when coal and the like and the above binder are kneaded, since they cannot be homogeneously kneaded due to a high viscosity of the binder at ordinary temperature, they must be kneaded at a high temperature state using steam. Therefore, there have been a problem in which a dedicated facility capable of heating at a high temperature is required so that the capital spending increases, and the like.

The present invention has been achieved in consideration of the above situation, and an object thereof is to provide a method for producing a coal-containing formed product which exhibits a sufficient strength at a low addition concentration and can be used at ordinary temperature.

The present invention is based on the finding that a binder for a coal-containing formed product, which contains a macromolecular polymer having an intrinsic viscosity of <NUM> dl/g or higher, exhibits a sufficient strength at a low addition concentration and can be used at ordinary temperature.

That is, the present invention provides a method for producing a coal-containing formed product according to claim <NUM> and use of the binder as defined in claim <NUM>. Further beneficial embodiments of the present invention are described in dependent claims <NUM> to <NUM>.

The present invention can provide a method for producing a coal-containing formed product which exhibits a sufficient strength at a low addition concentration and can be used at ordinary temperature. Further, when the production method according to the present invention is, since a coal-containing formed product can be produced at ordinary temperature, thereby needing no special apparatus, the capital spending can also be reduced.

Hereinafter, the binder for a coal-containing formed product used in the present invention will be described in detail.

Here, in the present description, "(meth)acryl" means "acryl" and/or "methacryl.

The binder for a coal-containing formed product used in the present invention comprises a macromolecular polymer having an intrinsic viscosity of <NUM> dl/g or higher. The binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration and can be used at ordinary temperature can be provided by containing the macromolecular polymer having an intrinsic viscosity of <NUM> dl/g or higher.

The binder for a coal-containing formed product may contain, in addition to the macromolecular polymer having an intrinsic viscosity of <NUM> dl/g or higher, components used in conventional binders, for example, binders of bitumen and the like such as tar, tar residue, asphalt, coal tar pitch and pitches (petroleum pitch) made by distilling asphalt or making asphalt heavy. However, the content of the macromolecular polymer in the binder for a coal-containing formed product is preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, and still more preferably <NUM>% by mass or higher from the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration, and preferably <NUM>% by mass or lower, more preferably <NUM>% by mass or lower, and still more preferably <NUM>% by mass or lower from the viewpoint of ease of handleability.

The content of the macromolecular polymer in active substances of the binder for a coal-containing formed product is preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, still more preferably <NUM>% by mass or higher, and especially preferably <NUM>% by mass from the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration. Here, the active substances mean components excluding a solvent such as water, and components other than the macromolecular polymer (having an intrinsic viscosity of <NUM> dl/g or higher) according to the present invention from the binder.

The binder for a coal-containing formed product contains an aqueous solution containing the macromolecular polymer or an emulsion containing the macromolecular polymer and it is preferable that the binder contains an emulsion containing the macromolecular polymer. By containing the emulsion which is relatively low in viscosity and liquid, kneading with components constituting the coal-containing formed product becomes easy and the time taken until the effect is exhibited can also be shortened.

When the binder for a formed product contains the emulsion, the binder may contain, in addition to the emulsion, as required, for example, other components such as a stabilizer and a conventional binder in the range of not impairing the object of the present invention. When the binder for a formed product contains the emulsion, the content of the emulsion in the binder for a formed product is preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, still more preferably <NUM>% by mass or higher, and especially preferably <NUM>% by mass.

Further when the binder for a formed product contains the emulsion, the content of the active substances in the emulsion is preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, and still more preferably <NUM>% by mass or higher, and preferably <NUM>% by mass or lower, more preferably <NUM>% by mass or lower, and still more preferably <NUM>% by mass or lower.

When the binder for a formed product contains the aqueous solution, the binder may contain, in addition to the aqueous solution, as required, for example, other components such as a stabilizer and a conventional binder in the range of not impairing the object of the present invention. When the binder for a formed product contains the aqueous solution, the content of the aqueous solution in the binder for a formed product is preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, still more preferably <NUM>% by mass or higher, and especially preferably <NUM>% by mass.

Further, when the binder for a formed product contains the aqueous solution, the content of the active substances in the aqueous solution is preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, and still more preferably <NUM>% by mass or higher, and preferably <NUM>% by mass or lower, more preferably <NUM>% by mass or lower, and still more preferably <NUM>% by mass or lower.

The macromolecular polymer contained in the binder for a coal-containing formed product has an intrinsic viscosity of <NUM> dl/g or higher. From the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration, it is preferable that the macromolecular polymer be an anionic polymer or a cationic polymer.

The anionic polymer is not especially limited as long as it has an intrinsic viscosity of <NUM> dl/g or higher.

Examples of the anionic polymer include polymers of (meth)acrylic acid or salts thereof, polymers of partial hydrolyzates of acrylamide, copolymers of (meth)acrylic acid or a salt thereof with acrylamide, polymers of partially sulfomethylated acrylamide, copolymers of a (<NUM>-acrylamide)-<NUM>-methylpropanesulfonic acid salt with acrylamide, and terpolymers of (meth)acrylic acid or a salt thereof, acrylamide and a (<NUM>-acrylamide)-<NUM>-methylpropanesulfonic acid salt. These may be used singly or in combinations of two or more. Among these, from the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration and can be used at ordinary temperature, preferable are polymers of sodium (meth)acrylate, and copolymers of sodium (meth)acrylate with acrylamide; more preferable are polymers of sodium acrylate, and copolymers of sodium acrylate with acrylamide; and still more preferable are copolymers of sodium acrylate with acrylamide.

The cationic polymer is not especially limited as long as it has an intrinsic viscosity of <NUM> dl/g or higher.

Examples of the cationic polymer include polymers of a dimethylaminoethyl (meth)acrylate methyl chloride quaternary salt, polymers of diallylmethylammonium chloride, polymers of alkylamine epichlorohydrin condensates, copolymers of an alkylamine epichlorohydrin condensate with acrylamide, and copolymers of (meth)acrylic acid <NUM>-trimethylaminioethyl chloride with acrylamide. These may be used singly or in combinations of two or more. Among these, from the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration and can be used at ordinary temperature, preferable are copolymers of (meth)acrylic acid <NUM>-trimethylaminioethyl chloride with acrylamide; and more preferable is a copolymer of acrylic acid <NUM>-trimethylaminioethyl chloride with acrylamide.

The macromolecular polymer contained in the binder for a coal-containing formed product according to the present invention has an intrinsic viscosity of <NUM> dl/g or higher.

The intrinsic viscosity is represented by [η], and is defined in terms of a value calculated by using the following Huggins formula. <MAT> where ηSP represents a specific viscosity (= ηrel - <NUM>); k' represents Huggins constant; C represents a concentration of a macromolecular polymer sample solution; and ηrel represents a relative viscosity.

Macromolecular polymer sample solutions having different concentrations are prepared; the specific viscosity ηSP of the solution of each concentration is determined; the relation between ηSP/C and C is plotted; and a value of the intercept obtained by extrapolating the C to <NUM> is the intrinsic viscosity [η]. Here, used as a blank solution and a solvent for macromolecular polymer sample solutions are: for the anionic polymer, a <NUM> N sodium chloride aqueous solution; for the cationic polymer, a <NUM> N sodium nitrate aqueous solution; for a nonionic polymer, a <NUM> N sodium chloride aqueous solution; and for an amphoteric polymer, a <NUM> N sodium nitrate aqueous solution.

The specific viscosity ηSP is determined by a method shown in Examples described later.

In the present invention, the intrinsic viscosity of the macromolecular polymer is <NUM> dl/g or higher, preferably <NUM> dl/g or higher, and more preferably <NUM> dl/g or higher from the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration, and preferably <NUM> dl/g or lower, more preferably <NUM> dl/g or lower, and still more preferably <NUM> dl/g or lower from the viewpoint of ease of kneading with coal.

The coal-containing formed product produced according to the present invention contains at least coal. Components other than coal to be contained are not especially limited, but examples thereof include iron ore, metal oxides, vegetable waste (biomass) and slaked lime.

The content of the coal in the coal-containing formed product is preferably <NUM>% by mass or higher, and more preferably <NUM>% by mass or higher.

Further, it is preferable that the coal-containing formed product be obtained by forming a powder containing coal.

The coal contained in the formed product is not especially limited, but examples thereof include anthracite, semi-anthracite, bituminous coal, sub-bituminous coal and brown coal.

The content of the macromolecular polymer in the coal-containing formed product is, with respect to the total amount of components (excluding moisture contained in coal) constituting the coal-containing formed product, preferably <NUM>% by mass or higher, more preferably <NUM>% by mass or higher, and still more preferably <NUM>% by mass or higher from the viewpoint of providing the coal-containing formed product exhibiting a sufficient strength, and preferably <NUM>% by mass or lower, more preferably <NUM>% by mass or lower, and still more preferably <NUM>% by mass or lower from the viewpoint of reducing the processing cost.

When a conventional binder as a binder is used concurrently with the macromolecular polymer, the content of the conventional binder in the coal-containing formed product is, with respect to the total amount of components (excluding moisture contained in coal) constituting the coal-containing formed product, preferably <NUM>% by mass or lower, more preferably <NUM>% by mass or lower, and still more preferably <NUM>% by mass or lower.

A method for producing the coal-containing formed product according to claim <NUM> is not especially further limited, but it is preferable that the coal-containing formed product be produced by forming by compression forming. By forming by compression forming, the formed product excellent in the strength can be easily provided.

The pressure in the compression forming is, from the viewpoint of providing the coal-containing formed product excellent in the strength, preferably <NUM> t/cm<NUM> or higher, and more preferably <NUM> t/cm<NUM> or higher, and preferably <NUM> t/cm<NUM> or lower, and more preferably <NUM> t/cm<NUM> or lower.

The macromolecular polymer to be used in the binder for a coal-containing formed product is preferably an anionic polymer or a cationic polymer from the viewpoint of providing the binder for a coal-containing formed product which exhibits a sufficient strength at a low addition concentration.

Then, when the coal-containing formed product is produced, the macromolecular polymer is added to components constituting the coal-containing formed product as an aqueous solution or as an emulsion. Among these, from the viewpoint of ease of kneading with components constituting the coal-containing formed product and shortening the time taken until the effect is exhibited, it is preferable that the macromolecular polymer be added as an emulsion which is relatively low in the viscosity and liquid.

Further the macromolecular polymer, in consideration of ease of kneading with components constituting the coal-containing formed product, may be added by being sprayed in fine droplets by using a two-fluid nozzle or the like.

Then, the present invention will be described in more detail by way of Examples, but the present invention is not limited to these Examples in any way.

An emulsion having a macromolecular polymer concentration (active substance concentration) indicated in Table <NUM> was added to <NUM> of a coal whose moisture content at ordinary temperature was <NUM>% by mass so that the concentration of the active substance in the binder became <NUM>% by mass with respect to the total amount of components other than moisture in the coal and the active substance in the binder; and water was sprayed by a sprayer so that the total of the amount of the emulsion added and the water became <NUM>; and thereafter, the resultant was mixed for <NUM> by a spatula.

After the mixing, a pressure of about <NUM> t/cm<NUM> was applied on the obtained mixture by a uniaxial compression forming machine to thereby fabricate a cylindrical formed coal of about <NUM> in height and about <NUM> in diameter.

<NUM> of a coal whose moisture content at ordinary temperature was <NUM>% by mass was heated at a temperature of <NUM> for <NUM> to evaporate the moisture in the coal to dry the coal.

Then, a macromolecular polymer indicated in Table <NUM> was added to water so that the macromolecular polymer concentration (active substance concentration) became the concentration indicated in Table <NUM>, and stirred for <NUM> by using a magnetic stirrer. An aqueous solution in which the macromolecular polymer was dissolved in water (macromolecular polymer sample solution) was thus obtained as the binder.

Then, <NUM> of the obtained aqueous solution was added to the coal (whose weight before drying was <NUM>) dried as described above so that the concentration of the active substance of the binder became <NUM>% by mass with respect to the total amount of components other than moisture in the coal and the active substance of the binder, and mixed for <NUM> by a spatula.

A tar heated to <NUM> was added, under a sealed condition, to <NUM> of a coal which was heated to <NUM> and whose moisture content was <NUM>% by mass so that the tar concentration became <NUM>% by mass with respect to the total amount of components other than moisture in the coal and the tar (binder), and mixed for <NUM> by a spatula.

A pressure of about <NUM> t/cm<NUM> was applied on the obtained mixture by a uniaxial compression forming machine to thereby fabricate a cylindrical formed coal of about <NUM> in height and about <NUM> in diameter.

Then, the obtained aqueous solution was added to the coal (whose weight before drying was <NUM>) dried as described above so that the concentration of the active substance of the binder became <NUM>% by mass with respect to the total amount of components other than moisture in the coal and the active substance of the binder, and mixed for <NUM> by a spatula.

The intrinsic viscosity of a macromolecular polymer used as the binder was determined as follows.

The intrinsic viscosity [η] of each macromolecular polymer was calculated from these values according to the determination method of the intrinsic viscosity based on the following Huggins formula. <MAT> where k' represents Huggins constant; and C represents the concentration of the macromolecular polymer sample solution [% by mass/volume] (= C [g/dL]).

The fluidity at ordinary temperature of the emulsions containing a macromolecular polymer, the macromolecular polymer aqueous solutions and the tar right before being added to coal was visually evaluated. The results are shown in Table <NUM>.

As seen in Examples <NUM>, <NUM>, <NUM> and <NUM>, when the form of the binders when being added to the coal was an emulsion, the binders had fluidity; and as seen in Examples <NUM>, <NUM> and <NUM>, when the form of the binders when being added to the coal was an aqueous solution, the binders all had no fluidity and were gelatinous. When a binder had fluidity, since it became easy for the binder to be kneaded with components constituting a coal-containing formed product, in Examples <NUM>, <NUM>, <NUM> and <NUM>, kneading with coal was easy. By contrast, in Examples <NUM>, <NUM> and <NUM>, the binder had no fluidity and was gelatinous and kneading with coal was not easy, but homogeneous kneading was possible.

Comparative Example <NUM> had no fluidity and homogeneous kneading with coal at ordinary temperature was difficult. In Comparative Examples <NUM> to <NUM>, since their intrinsic viscosity was low, the binders had fluidity, and kneading with coal was easy.

<NUM> pieces of a formed coal were fabricated under the condition of each of Examples and Comparative Examples, and weighed, and thereafter, the average weight of the <NUM> pieces thereof was determined and taken as an average weight before a drop test.

The <NUM> pieces thereof weighed were each dropped from a height of <NUM>, and the weight of the largest lump in broken formed coal in each piece thereof was measured. The drop test was carried out on the <NUM> pieces thereof fabricated under the condition of each of Examples and Comparative Examples. The average weight of the largest lumps in broken formed coal in the <NUM> pieces thereof fabricated under each condition was determined, and taken as an average weight after the drop test. Then, the residual ratio was calculated by using the following expression, and taken as an index of the strength of the formed coal.

The results are shown in Table <NUM>. A binder having a higher residual ratio has a better strength.

Abbreviations in Table <NUM> are as follows.

From the results in Table <NUM>, it is clear that the binders of Examples <NUM> to <NUM> exhibited a more sufficient strength at a low addition concentration than the binder of Comparative Example <NUM>. Further the binders of Examples <NUM> to <NUM> can be used at ordinary temperature, whereas the binder of Comparative Example <NUM> needs to be heated for use.

Then, by comparison of Examples <NUM> to <NUM> with Comparative Examples <NUM> to <NUM>, it is clear that the intrinsic viscosity being <NUM> dL/g or higher led to the exhibition of a sufficient strength.

Claim 1:
A method for producing a coal-containing formed product, comprising
adding a binder to components constituting the coal-containing formed product,
wherein the binder contains an aqueous solution containing a macromolecular polymer or an emulsion containing a macromolecular polymer,
wherein the macromolecular polymer has an intrinsic viscosity of <NUM> dl/g or higher as determined at <NUM> as described in the description.