RU2633584C1 - Method for coke production and coke - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for coke production involves dry distillation of a mixture containing ashless coal; oxidized ash-free coal obtained by oxidation treatment of ash-free coal; and crude petroleum coke, in which relative to 100 parts by weight of total ash-free coal the oxidized ashless coal and crude petroleum coke, the content of ash coal is from 5 to 40 parts by weight, and the total content of ash coal and oxidized ash coal is from 30 to 70 parts by weight.

EFFECT: method makes it possible to obtain high-purity coke with less cost.

8 cl, 2 dwg, 1 tbl

Description

FIELD OF THE INVENTION

[0001]

The present invention relates to a method for producing coke and to coke. In particular, the present invention relates to a method for producing coke, suitable as a reducing material for non-ferrous metallurgy, and to coke.

State of the art

[0002]

Traditionally, coke is used as a reducing material in the cleaning of non-ferrous metals such as aluminum and titanium. In particular, calcined coke (the so-called “calcined coke”) obtained by heating crude petroleum coke is inexpensive and therefore used for many purposes.

[0003]

Crude petroleum coke as a raw material for calcined coke is a by-product resulting from the processing of crude oil. Accordingly, the quality of calcined coke depends on crude oil. For example, impurities (such as sulfur, nickel, vanadium, sodium, and the like) contained in calcined coke come from crude oil, which is the raw material for calcined coke. These impurities become a source of pollution and therefore, in the case of using calcined coke in the cleaning process, the impurity content (in particular, the sulfur content, as indicated below) should be as low as possible. However, since the content of impurities in the newly produced crude oil is large, it is difficult to obtain coke with a low content of impurities.

[0004]

As for the carbon material with a low content of impurities, studies have been conducted on the use of ashless coal, essentially free of ash, as the coke raw material. For example, Patent Document 1 describes a method for producing ashless coal used as fuel, coke, chemical raw materials, etc.

[0005]

However, ashless coal has a high thermal fluidity and tends to melt at 200-300 ° C, regardless of the type of coal raw material. In addition, ashless coal has the property of expanding when heated to approximately 400 ° C. Thus, when ashless coal is subjected to molding, followed by dry distillation when heated to high temperatures, ashless coal melts, and the shape of the molded product cannot be maintained, which leads to a problem of thermoplasticity. In addition, expandability is a problem, for example, as follows: ashless coal can expand as a result of the formation of foam during high-temperature heating with transfusion from a dry distillation unit or with sticking to a dry distillation unit, which makes it unloading impossible, or coke can be obtained in the form of a spongy porous body with a significant decrease in specific bulk density. Thus, due to a problem with thermoplasticity or expandability, ashless coke can hardly be used as coke raw material.

[0006]

To solve this problem, the inventors of the present invention have proposed a method for refining ashless coal (patent document 2). In particular, a method for producing a carbon raw material is disclosed, comprising: the step of heating the suspension, which comprises heat treating the suspension containing coal and an aromatic solvent; the separation stage, which consists in separating the suspension, heat-treated at the stage of heating the suspension, into a liquid component containing coal dissolved in it, and a solid component consisting of ash and insoluble coal; the ashless coal production step of obtaining ashless coal by removing the aromatic solvent from the liquid component, and the ashless coal heating step of heat treating the ashless coal obtained in the ashless coal production step to obtain carbon raw material, wherein the content of volatile substances carbon raw material obtained at the stage of heating ashless coal, measured by the method described in JIS M 8812, is from 24% of the mass. up to 35% of the mass.

[0007]

According to this method, by including the step of heating the suspension, the step of separating, the step of producing ashless coal and the step of heating the ashless coal to bring the volatile matter content to a predetermined range, a low ash carbon material having excellent sinterability can be obtained.

Prior art literature

Patent documents

[0008]

Patent Document 1: JP-A-2001-26791

Patent Document 2: JP-A-2009-144130

SUMMARY OF THE INVENTION

The tasks solved by the invention

[0009]

The method of Patent Document 2 provides an excellent effect of improving sintering ability, but since refining ashless coal is time consuming, production efficiency is not necessarily high and refined ashless coal is relatively expensive.

[0010]

The present invention has been accomplished by focusing on the circumstances described above, and the aim of the present invention is to provide a process for producing high-purity coke at a lower cost than ever before and to propose a high-purity coke.

Means for solving problems

[0011]

The method of producing coke in the present invention, which ensures the achievement of the goal, includes the implementation of dry distillation of a mixture containing: ashless coal; oxidized ashless coal obtained by oxidizing treatment of ashless coal; and crude petroleum coke, in which, relative to 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke, the ashless coal content is from 5 to 40 mass parts, and the total content of ashless coal and oxidized ashless coal is from 30 to 70 mass parts.

[0012]

Preferred embodiments of the present invention include a case where the mixture is molded and then dry distilled, a case where the percentage of oxygen increase of the oxidized ashless coal is from 2 to 10%, a case where the oxidation treatment is air oxidation, and a case when the oxidative treatment is carried out at a temperature of 150 ° C or higher, and below the ignition temperature.

[0013]

In addition to this, preferred embodiments include the case where the dry distillation is carried out in a chamber furnace, and the case where the dry distillation is carried out in a rotary kiln.

One aspect of the present invention includes coke obtained by dry distillation of a mixture comprising: ashless coal; oxidized ashless coal obtained by oxidizing treatment of ashless coal; and crude petroleum coke, in which, relative to 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke, the ashless coal content is from 5 to 40 mass parts, and the total content of ashless coal and oxidized ashless coal is from 30 to 70 mass parts.

Advantage of the invention

[0014]

According to the production method of the present invention, high-purity coke can be obtained at low cost using crude petroleum coke. In addition, high purity coke can be provided in the present invention.

Brief Description of the Drawings

[0015]

[Fig. 1] Fig. 1 is a flow chart for explaining one example of a method for producing ashless coal.

[Fig. 2] Fig. 2 is a flowchart for explaining one example of a method for producing coke in the present invention.

The method of carrying out the invention

[0016]

The inventors of the present invention conducted many intensive studies to produce high purity coke at low cost using crude petroleum coke as carbon raw material and found the following.

[0017]

Ashless coal impurities are very low, and mixing ashless coal with crude petroleum coke is useful to reduce coke impurities. However, as indicated in traditional methods, ashless coal has problems with thermoplasticity or extensibility.

[0018]

Studies by the inventors of the present invention have shown that when ashless coal is oxidized, the thermoplasticity and extensibility of ashless coal can be improved. However, oxidized ashless coal is in the form of a fine powder and exhibits low sintering properties, and the dry distillation of a mixture of oxidized ashless coal and crude petroleum coke causes the problem that the resulting coke becomes powdery and easily precipitates from a dry distillation unit and, in addition, specific gravity of coke is reduced. Intensive studies were carried out to solve this problem, and as a result, it was found that when a mixture of ashless coal, oxidized ashless coal and crude petroleum coke was prepared, ashless coal acts as a binder for the bonding of oxidized ashless coal and crude petroleum coke, and such a problem, like coke powder, can be reduced.

[0019]

It was further found that when a mixture containing ashless coal, oxidized ashless coal and crude petroleum coke, each in the predetermined amounts described below, is used, melting or expansion of the resulting coke can be prevented, and high-purity coke can be obtained at low cost.

[0020]

The method of producing coke in the present invention is described below with reference to the flowcharts illustrated in FIG. 1 and FIG. 2.

[0021]

First, ashless coal used in the present invention is described.

[0022]

Ashless coal means coal having an ash content of 5% by weight. or less, preferably 3% of the mass. or less. Ashless coal is preferably coal in which the ash concentration of residues of inorganic substances (for example, silicic acid, alumina, iron oxide, lime, magnesium oxide, alkali metal or the like) when heated at 815 ° C. resulting in an ashing substance is very low . In particular, the ash concentration is more preferably 5000 ppm or less (by weight), even more preferably 2000 ppm or less. In addition, ashless coal is completely water free and exhibits higher thermal fluidity than raw coal.

[0023]

<Method for producing ashless coal>

Ashless coal can be obtained by various traditional methods of preparation and, for example, can be obtained by removing the solvent from the coal extract. For example, ashless coal can be obtained by carrying out the following steps S1-S3 (see FIG. 1), but the ashless coal production method described below (S1-S3) can be appropriately modified, and various processing steps can be added if necessary.

[0024]

For example, when ashless coal is produced, provided that each of the steps described above is not degraded, other steps, for example, a coal grinding step consisting in finely grinding the coal feed, a removal step consisting in removing undesirable material such as waste, or the drying step, which consists in drying the ashless coal obtained, can be performed between the respective steps mentioned above, either before or after each step.

[0025]

<Stage of heating the suspension: S1>

The step (S1) of heating the suspension is a treatment comprising mixing coal and an aromatic solvent to obtain a suspension, and heat treating the suspension to extract the coal component with an aromatic solvent.

The type of coal used as raw material (hereinafter, sometimes referred to as “coal raw material” in this document) has no particular restrictions. For example, various known types of coal can be used, such as bituminous coal, semi-bituminous coal, brown coal, and lignite. From the point of view of profitability, it is more preferable to use low-grade coal, such as semi-bituminous coal, brown coal and lignite, instead of expensive high-grade coal, such as bituminous coal.

[0026]

An aromatic solvent is not particularly limited as long as it is a solvent having the property of dissolving coal. Examples of aromatic solvents include monocyclic aromatic compounds such as benzene, toluene and xylene, and bicyclic aromatic compounds such as naphthalene, methylnaphthalene, dimethylnaphthalene and trimethylnaphthalene. In addition, examples of bicyclic aromatic compounds include naphthalenes with an aliphatic side chain, biphenyl and long-chain aliphatic alkylbenzene. In the present invention, a bicyclic aromatic compound, which is a non-hydrogen donating solvent, is preferred.

[0027]

The non-hydrogen transferring solvent is a by-product of the distillation of coal, which is a solvent predominantly purified from the carbonization product of coal and mainly consisting of a bicyclic aromatic compound. The reason that the non-hydrogen-giving solvent is preferred is that the non-hydrogen-giving solvent is stable even in the heated state and exhibits excellent affinity for coal and therefore the proportion of the carbon component in the solvent (hereinafter, sometimes referred to as “ extraction percentage ") is high and, moreover, the solvent can be easily recovered by distillation or other methods, while the recovered solvent can be cyclically used Use This Criterion.

[0028]

If the boiling point of the aromatic solvent is too low, the pressure required during the extraction with heating or in the separation step (S2) described below will be high, and evaporation losses in the aromatic solvent extraction step increase, which reduces the aromatic extraction coefficient solvent. In addition, this causes a decrease in the percentage of extraction during extraction with heating. On the other hand, if the boiling point of the aromatic solvent is too high, the separation of the aromatic solvent from the liquid component or solid component in the separation step (S2) is difficult, and the solvent recovery coefficient is reduced. The boiling point of the aromatic solvent is preferably from 180 ° C to 330 ° C.

[0029]

The concentration of coal with respect to the aromatic solvent is not particularly limited. Although it can vary depending on the type of coal feed, if the concentration of coal relative to the aromatic solvent is low, the ratio of the carbon component extracted by the aromatic solvent to the amount of aromatic solvent will be small, and this is not cost-effective. On the other hand, an increased coal concentration is preferable, but if the coal concentration becomes excessively high, the viscosity of the suspension will be increased, and transportation of the suspension or separation of the liquid component and the solid component in the separation step (S2) may become difficult. The concentration of coal based on the dry weight of coal is preferably 10% of the mass. or more, more preferably 20% of the mass. or more, and preferably 50% of the mass. or less, more preferably 35% of the mass. or less.

[0030]

If the temperature of the heat treatment (extraction with heating) of the suspension is too low, the bonds between the molecules that make up the coal cannot be sufficiently weakened, and if low-grade coal is used as coal raw material, the temperature of the solidification of ash-free coal obtained on the below-described step (S3) of producing ashless coal cannot be increased. On the other hand, at too high a heat treatment temperature, the coal pyrolysis reaction will be very active, which will cause the recombination of the formed pyrolytic radicals, resulting in a decrease in the extraction rate. The heating temperature of the suspension is preferably 350 ° C or more, more preferably 380 ° C or more, and preferably 420 ° C or less.

[0031]

The heating time (extraction time) is not particularly limited, but if the extraction time is too long, the pyrolysis reaction proceeds excessively, which allows the radical polymerization reaction to progress, and the percentage of extraction is reduced. For example, at the above heating temperature, the heating time is preferably 120 minutes or less, more preferably 60 minutes or less, even more preferably 30 minutes or less, and preferably 10 minutes or more.

[0032]

After extraction with heating, the extract is preferably cooled to 370 ° C. or less in order to suppress the pyrolysis reaction. The lower temperature limit during cooling is preferably 300 ° C. or more. When cooled to less than 300 ° C, the solvent capacity of the aromatic solvent is reduced, and the previously extracted carbon component is re-precipitated, which leads to a decrease in the yield of ashless coal.

[0033]

The extraction with heating is preferably carried out in a non-oxidizing atmosphere. In particular, the extraction with heating is preferably carried out in the presence of an inert gas such as nitrogen. This is due to the fact that contact with oxygen during extraction with heating is risky due to the danger of ignition, and moreover, the cost increases when using oxygen.

[0034]

The pressure during the extraction with heating may vary depending on the temperature during the extraction with heating or on the vapor pressure of the aromatic solvent used, but if the pressure is lower than the vapor pressure of the aromatic solvent, the aromatic solvent evaporates and does not retain in the liquid phase, and the extraction does not can be achieved. On the other hand, if the pressure is too high, the cost of equipment and operating costs increase, and this is not cost-effective. The preferred pressure is usually from 1.0 to 2.0 MPa.

[0035]

<Stage separation: S2>

The separation step (S2) is the step of separating the suspension subjected to a heat treatment in the step (S1) of heating the suspension into a liquid component and a solid component. A liquid component is a solution containing a carbon component extracted with an aromatic solvent. The solid component is a suspension containing ash, insoluble in an aromatic solvent, and insoluble coal.

[0036]

The method for separating the suspension into a liquid component and a solid component in the separation step (S2) is not particularly limited, and conventional separation methods such as a filtration method, a centrifugal separation method and a gravity precipitation method can be used. In the present invention, it is preferable to use a gravity deposition method that allows continuous processing of the fluid and is inexpensive and suitable for processing large volumes. In the case of using the gravitational precipitation method, a liquid component (sometimes referred to as a “liquid supernatant”), which is a solution containing a carbon component extracted with an aromatic solvent, can be obtained from the upper part of the gravitational precipitation tank, and a solid component (in hereinafter, sometimes referred to as a “solid phase concentrate”), which is a suspension containing insoluble ash and coal in a solvent, can be obtained from It gravitational settling portion of the tank.

[0037]

Subsequently, as described below, the aromatic solvent is separated and recovered from the liquid supernatant by a distillation method and the like, and as a result ashless coal having a very low ash concentration can be obtained (ashless coal production step (S3)).

[0038]

<Ashless Coal Production Step: S3>

The ashless coal production step (S3) is a step of separating the aromatic solvent from the liquid supernatant to produce an ashless coal having a very low ash concentration.

[0039]

The method for separating the aromatic solvent from the liquid supernatant is not particularly limited, and a conventional distillation method, an evaporation method (for example, a spray drying method), etc. can be used. The aromatic solvent recovered by separation can be used repeatedly. By separating and extracting the aromatic solvent, ashless coal can be obtained from the liquid supernatant. The obtained ashless coal can be used as a raw material mixture in the present invention, and can also be used as a raw material of oxidized ashless coal.

[0040]

<Other stages>

If necessary, a coal by-product in which the ash is concentrated can be obtained by separating the aromatic solvent from the solid phase concentrate (step for producing the coal by-product). As a method for separating an aromatic solvent from a solid phase concentrate, a conventional distillation or evaporation method can be used, similar to the above-described step (S3) for producing ashless coal, which consists in producing ashless coal from a liquid component.

[0041]

<Method for producing coke>

The method for producing coke in the present invention is described below with reference to FIG. Upon receipt of coke, provided that each of the stages is not degraded, other stages, for example, a grinding stage, which consists in fine grinding of various raw materials and the like, a removal stage, which consists in removing undesirable material, such as waste, or the stage of implementation of various treatments of the obtained coke can be performed between the respective stages either before or after each stage.

[0042]

<Oxidation step: C1>

The oxidation stage is the stage of the oxidation treatment of ashless coal to produce oxidized ashless coal. By applying oxidative treatment to ashless coal, ashless coal is refined and thermoplasticity or extensibility can be improved.

[0043]

The method of oxidizing ashless coal is not particularly limited. It is desirable to carry out oxidation in an oxidizing atmosphere such as oxygen, ozone, nitrogen dioxide and air, and air oxidation using oxygen in air as an oxidizing agent is preferred.

[0044]

The percentage increase in oxygen of oxidized ashless coal is not particularly limited, but if the percentage increase in oxygen is too low, the effect of the refinement of ashless coal is not sufficient, and problems associated with thermoplasticity or expandability sometimes occur during dry distillation. On the other hand, if the percentage increase in oxygen is too high, the yield decreases and, as a result, production becomes unprofitable. Accordingly, the percentage increase in oxygen is 2% or more, preferably 3% or more, and is preferably 10% or less, more preferably 5% or less.

[0045]

In the present invention, if a percentage of an increase in oxygen of ashless coal is set, an ashless coal having a lower percentage of increase in oxygen than a predetermined value is not considered as oxidized ashless coal in the present invention, even if the ashless coal is oxidized. In addition, in the case where ashless coal having a lower percentage increase in oxygen than a predetermined value is used as carbon raw material, ashless coal is considered as ashless coal in the present invention.

[0046]

The percentage increase in oxygen as used in the present invention is the value obtained by measuring the percentage of oxygen in ashless coal before and after the oxidation treatment in accordance with JIS M8813 (method for calculating the percentage of oxygen) and performing the calculation (percentage of oxygen of oxidized ashless coal minus the percentage of oxygen ashless coal).

[0047]

The temperature maintained during oxidation (hereinafter referred to as the oxidation temperature) can be properly adjusted so that the desired percentage increase in oxygen can be obtained. If the oxidation temperature is low, ashless coal may not be sufficiently oxidized, and the refinement effect described above may not be fully implemented. In addition, if the oxidation temperature is low, a long time is required to achieve the desired percentage increase in oxygen, and production efficiency is reduced. On the other hand, if the oxidation temperature is too high, the oxidation rate increases excessively, and the oxidation state of ashless coal is difficult to control. The oxidation temperature is preferably 150 ° C or more, more preferably 200 ° C or more, and is preferably below the ignition temperature of ashless coal, more preferably 350 ° C or less.

[0048]

The oxidation time (holding time at a predetermined temperature) can be appropriately adjusted to obtain the desired percentage increase in oxygen. If the oxidation time is short, ashless coal may not be sufficiently oxidized. On the other hand, if the oxidation time is long, ashless coal may be excessively oxidized, and the yield is reduced, which leads to an increase in cost. For example, the oxidation time in the temperature range described above is preferably 0.5 hours or more, more preferably 1 hour or more, and is preferably 6 hours or less, more preferably 3 hours or less. After oxidation, ashless coal may be allowed to cool to room temperature.

[0049]

The particle diameter (hereinafter referred to as particle diameter refers to the diameter of the circle) of ashless coal subjected to oxidation treatment is not particularly limited. If the particle diameter of ashless coal is too large, the inside of ashless coal may not be sufficiently oxidized, which leaves the risk of melting, etc. during dry distillation. On the other hand, if the particle diameter of ashless coal is too small, the technological properties deteriorate. The average particle diameter of ashless coal is preferably 3 mm or less, more preferably 1 mm or less, and is preferably 0.2 mm or more, more preferably 0.3 mm or more. From the point of view of accelerating oxidation, the maximum particle diameter is also preferably 3 mm or less, more preferably 1 mm or less, even more preferably 0.5 mm or less.

[0050]

<Stage mixing carbon raw material: C2>

The carbon raw material mixing step is a step of mixing ashless coal, oxidized ashless coal and crude petroleum coke to form a mixture (hereinafter referred to as “mixed carbon raw material”).

[0051]

Crude petroleum coke is a solid obtained as a by-product in the refining process, together with light oil in equipment (coking unit) for producing light oil by heating the distillation residue at high temperature (for example, at 500 ° C or more) for the course of pyrolysis. In the present invention, various known crude petroleum coke available on the market can be used as crude petroleum coke. Crude petroleum coke having a volatiles content of 5 to 20% by mass and a sulfur content of 2 to 5% by mass is preferred.

[0052]

In the present invention, the mixing ratio of ashless coal in the mixed carbon raw material and the mixing ratio between ashless coal and oxidized ashless coal need to be adjusted appropriately in accordance with the properties of ashless coal (oxidized / non-oxidized, oxidation state) to obtain highly pure coke.

[0053]

(I) Ashless coal content: 5 to 40 parts by weight

If the mixing ratio of ashless coal is too low, the function of the binder is not manifested sufficiently, and the coke becomes powdered. On the other hand, if the mixing ratio of ashless coal is too large, the thermoplasticization or expansion due to ashless coal becomes redundant and, for example, coke can be obtained as a sponge-like porous body with a reduced specific bulk density, or coke can adhere to the inner wall installation of dry distillation, which makes its unloading impossible.

[0054]

In the present invention, the ashless coal content is 5 mass parts or more, preferably 10 mass parts or more, and is 40 mass parts or less, preferably 25 mass parts or less, per 100 mass parts of all ashless coal, oxidized ashless coal and crude oil coke.

[0055]

(II) The total content of ashless coal and oxidized ashless coal: from 30 to 70 mass parts

As described above, the total ashless coal content is 40 parts by mass or less, but due to the oxidized ashless coal content, the amount of crude petroleum coke used can be lower and the impurity content in the coke can be lower. Ashless coal and oxidized ashless coal are more expensive than crude petroleum coke and, therefore, when their total content increases, the cost of producing a unit of coke increases. On the other hand, if the total content of ashless coal and oxidized ashless coal is too low, the effect of reducing impurities is not achieved to a large extent. For this reason, the total content of ashless coal and oxidized ashless coal is 30 mass parts or more, preferably 35 mass parts or more, more preferably 40 mass parts or more, and is 70 mass parts or less, preferably 65 mass parts or less, more preferably 60 mass parts or less, per 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke.

[0056]

The content of oxidized ashless coal is not particularly limited, but if the content of oxidized ashless coal is too low, this causes a problem, for example, in that the coke expands to form a sponge-like structure or melts and adheres to the plant. Thus, the content of oxidized ashless coal is preferably 5 mass parts or more, more preferably 10 mass parts or more, even more preferably 30 mass parts or more, per 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke. On the other hand, the upper limit of the content of oxidized ashless coal can be properly reduced to the above-described range of the total contents of ashless coal and oxidized ashless coal (from 30 to 70 mass parts), but is preferably 50 mass parts or less, more preferably 40 mass parts or less.

[0057]

The average particle diameter of ashless coal is not particularly limited, but if the average particle diameter of ashless coal is too large, inhomogeneity may form in the mixture state, preventing ashless coal from fully exhibiting a binding effect, etc. On the other hand, if the average particle diameter is too small, the technological properties may be degraded. The average particle diameter of ashless coal is preferably 10 mm or less, more preferably 0.5 mm or less, and is preferably 0.1 mm or more, more preferably 0.2 mm or more. If the maximum particle diameter of ashless coal is too large, inhomogeneity may occur in the mixture state in the molded product, and therefore it is preferably 1.0 mm or less, more preferably 0.5 mm or less.

[0058]

In addition, the average particle diameter of ashless coal is preferably smaller than the average particle diameter of oxidized ashless coal, since the voids between the materials of the carbonaceous feed are filled and the bonding effect is more pronounced.

[0059]

The mixture in the present invention may be sufficient if it contains ashless coal, oxidized ashless coal and crude petroleum coke, and the mixture may contain other material (s) (for example, a known additive, such as a binder and oil pitch), provided that it is not worsens the present invention, but if another material (s) is present in the mixture, the content of coke impurities may increase due to this other material (s). Thus, all ashless coal, oxidized ashless coal and crude petroleum coke in the mixture preferably contains 90% of the mass. or more, more preferably 100% of the mass. The content of 100% of the mass. indicates that the mixture consists of ashless coal, oxidized coal and crude petroleum coke, and the rest is impurities.

[0060]

The method of mixing ashless coal, oxidized ashless coal and crude petroleum coke is not particularly limited, and a conventional method can be used to ensure uniform mixing. Examples thereof include the use of a mixer, kneading machine, single shaft mixer and twin screw mixer.

[0061]

<Forming step: C3>

The molding step is a step of imparting, if necessary, the mixture obtained in the step (C2) of mixing the carbon raw material to the desired shape to obtain a molded product. By obtaining the molded product from the mixture, the bonding between the respective materials of the carbon feed can be more strongly formed due to the bonding effect of ashless coal, and the conversion of coke to powder or a decrease in specific bulk density can be suppressed.

[0062]

For example, in the case of dry distillation of the mixture in a chamber furnace, the load is applied in the vertical direction, decreasing the distance between the corresponding materials of the carbon raw material, and the corresponding carbon materials are bonded using the bonding effect of ashless coal, which can prevent the conversion of coke to powder, and the specific gravity can be promoted. Such an effect may be more pronounced upon receipt of the molded product.

[0063]

On the other hand, in the case of dry distillation of the mixture using a horizontal furnace in which a sufficient load is not applied in the vertical direction, such as a rotary kiln, the binding effect is not fully expressed. As a result, the binding between the respective materials of the carbon feed is weak, and the coke can be powdery, which leads to a decrease in the specific bulk density of coke. Therefore, the mixture is preferably molded into the desired shape before dry distillation.

[0064]

A method of manufacturing a molded product from a mixture is not particularly limited, and examples thereof include, for example, a method using a two-roll molding machine operating with smooth rolls or a two-roll molding machine having an almond-shaped pocket, a method using a single-shaft molding machine of type molding or molding a roller type machine, or an extrusion molding machine, and mold pressing, and any of these methods may be applied. Among the foregoing, it is preferable to produce a briquette-like molded product or sheet molded product using a twin-roll type briquetting machine, rolling compaction, and the like.

[0065]

The molding of the mixture may be cold molding, which is carried out at about room temperature, but hot molding with heating is preferred. When the mixture is molded under pressure at high temperature, ashless coal is plastically deformed to fill voids between the particles of oxidized ashless coal and crude petroleum coke, whereby a more highly densified molded product can be obtained. In turn, coke having a higher specific bulk density can be obtained by dry distillation of a highly densified molded product. On the other hand, if the molding temperature is too high, ashless coal can soften and expand, which does not allow to achieve a high specific bulk density. The hot forming temperature (temperature of a device such as a mold or roll) is preferably 100 ° C or more, more preferably 200 ° C or more, and is preferably 450 ° C or less, more preferably 300 ° C or less. The molding pressure is not particularly limited, and standard conditions may be used. For example, the molding pressure is from about 0.5 to 3 t / cm ² .

[0066]

<Stage dry distillation: C4>

The dry distillation step is a dry distillation step of the mixture obtained in the step (C2) of mixing the carbon raw material or the molded product obtained in the step of (C3) molding, whereby coke is obtained. The shape of the dry distillation furnace is not particularly limited, and dry distillation can be carried out periodically using a chamber furnace, or dry distillation can be carried out continuously using a vertical shaft furnace. In addition, a horizontal rotary kiln, such as a rotary kiln, can also be used.

[0067]

Regarding dry distillation conditions, standard conditions can also be applied, and the dry distillation temperature can be set appropriately and is not particularly limited, but can be preferably 650 ° C or more, more preferably 700 ° C or more, and preferably 1200 ° C or less, more preferably 1050 ° C or less. The dry distillation time at the dry distillation temperature is also not particularly limited, and the desired dry distillation time can be set in accordance with the configuration of the apparatus or the like, and can preferably be 5 minutes or more, more preferably 10 minutes or more, and preferably 24 hours or less, more preferably 12 hours or less.

[0068]

The atmosphere of dry distillation can be an atmosphere of non-oxidizing gas in order to prevent the deterioration of coke due to oxidation. Various known gases may be used as the non-oxidizing gas, and the gas may, for example, be an inert gas such as nitrogen, helium and argon, or a reducing gas such as hydrogen.

[0069]

During dry distillation, not only crude petroleum coke is converted to calcined coke (calcined coke), but also ashless coal acts as a binder between oxidized ashless coal and calcined coke, firmly binding oxidized ashless coal to calcined coke, thereby increasing the strength of coke.

[0070]

If the mixture is subjected to dry distillation, the corresponding materials of the carbon feed are bonded to each other, and an amorphous agglomerate-like coke is obtained. In addition, when molding the mixture, coke is obtained having substantially the same shape as the molded product before dry distillation. In the coke of the present invention, the ashless coal mixing ratio is appropriately controlled, whereby coke sticking inside the dry distillation unit can be prevented, which makes it impossible to unload it, and can also be prevented from powdering.

[0071]

Thus obtained coke has a higher purity and higher specific bulk density than that of the well-known coke. In particular, the content of minerals that become impurities is preferably 1% of the mass. or less, more preferably 0.5% of the mass. or less. The specific bulk density is preferably 0.53 g / cm ³ or more, more preferably 0.6 g / cm ³ or more, even more preferably 0.7 g / cm ³ or more, and most preferably 0.8 g / cm ³ or more. The sulfur content is preferably 2% of the mass. or less.

[0072]

In addition, the mixture does not have the above-described problem associated with thermoplasticity or expandability during dry distillation and, in turn, the obtained coke has an excellent appearance and can be discharged from the dry distillation unit.

[0073]

As described above, coke obtained by dry distillation of a mixture containing ashless coal, oxidized ashless coal obtained by oxidative treatment of ashless coal, and crude petroleum coke, in which, relative to 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke, the ashless coal content is from 5 to 40 mass parts, and the total ashless coal and oxidized ashless coal content is from 30 to 70 mass parts, is a coke with a high purity and high bulk density and improved success thermoplasticity and extensibility described above, which may present a problem in case of using the ashless coal.

Examples

[0074]

The present invention is described in more detail below with reference to examples, but the present invention, of course, is not limited to the following examples and can be carried out with the appropriate changes, provided that they are in accordance with the above and below the essence of the invention, and all of them not fall outside the scope of the present invention.

[0075]

(Getting ashless coal)

(Stage of heating the suspension: S1)

An aromatic solvent (1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.)) was mixed with 5 kg of coal raw material (bituminous coal) in an amount (20 kg) four times the amount of coal raw material to prepare a suspension. In this suspension, a nitrogen pressure of up to 1.2 MPa was created and subjected to heat treatment (extraction with heating) in an autoclave having an internal volume of 30 L at 370 ° C for 1 h.

[0076]

(Separation step: S2)

The resulting suspension was separated into a liquid supernatant and a solid phase concentrate in a gravitational deposition tank maintained at the same temperature and pressure.

[0077]

(Ashless coal production step: S3)

The resulting liquid supernatant was then filtered (stainless steel mesh filter with a hole size of 1 μm) to obtain an ashless coal solution. The aromatic solvent was separated and recovered from an ashless coal solution using a distillation method to produce ashless coal. The ashless coal obtained was finely ground so that it passed through a sieve with a hole size of 3 mm, thus obtaining ashless coal.

[0078]

(Sulfur measurement)

In this ashless coal, the sulfur concentration was measured using the method described in JIS M 8122. As a result, the sulfur content of ashless coal was 0.5% of the mass.

[0079]

(Getting coke)

[0080]

(Oxidation step: C1)

Part of ashless coal was finely ground so that it passed through a sieve with a hole size of 0.5 mm. Finely ground ashless coal was heated in an air atmosphere to a predetermined temperature, shown in table 1, and kept at this temperature for a predetermined time, thereby carrying out oxidative treatment (in table 1 - “Oxidation conditions”). After the oxidizing treatment, ashless coal was allowed to cool to room temperature, thereby producing oxidized ashless coal.

Moreover, in ashless coal and oxidized ashless coal, the oxygen concentration was measured before and after the oxidation treatment in accordance with JIS M 8813 and the percentage of oxygen increase in the oxidized ashless coal was calculated. The results are presented in table 1 (in table 1 - "Percentage of oxygen increase").

[0081]

(Crude Petroleum Coke)

Commercially available crude petroleum coke (volatiles: 9.5% by mass, sulfur content: 3.1% by mass) was finely ground to pass through a sieve with a hole size of 10 mm.

[0082]

(Stage mixing carbon raw material: C2)

Ashless coal (in the table - “A”), oxidized ashless coal (in the table - “B”), and crude petroleum coke (in the table - “C”) were mixed in the given ratio shown in table 1 (in table 1 - “ The ratio of mixing raw materials ”) to obtain a mixture.

[0083]

Here, in No. 16, ashless coal subjected to oxidative treatment was considered as ashless coal, since the percentage of oxygen increase was less than 2% (1.50%). Accordingly, although the mixing ratio for No. 16 was A: B: C = 50 (20% by weight of ashless coal not oxidized, plus 30% by weight of ashless coal having a percentage increase in oxygen of 1.5%): 0:50 , in order to show the elements of the mixing ratio for No. 16, for convenience, the mixing ratio (“20”) of ashless coal not subjected to oxidative treatment is shown in the table column for A, and the mixing ratio (“30”) of ashless coal having percentage increase in oxygen 1.5% despite oxidative brabotku shown in the column for B.

[0084]

(Forming step: C3)

In relation to part of the mixtures (No. 7-12 and No. 15; in the table - “The presence or absence of molding” = completed), the molded product was obtained under the following conditions:

Forming Method: Rolling Seal

Roll temperature: 100 ° C

Roll Diameter: 162 mm

Roll width: 60 mm (pyramidal groove)

Width between rolls: 2 mm

Roll rotation speed: 15 rpm

Line pressure: 3 t / cm

[0085]

(Stage dry distillation: C4)

The mixture (No. 1-6, No. 13, No. 14 and No. 16-25) and the molded product (No. 7-12 and No. 15) were subjected to dry distillation treatment in a chamber furnace (No. 1-6 and No. 15 -25) or in a rotary kiln (No. 7-14).

[0086]

(Dry distillation treatment in a chamber furnace)

The mixture (No. 1-6 and No. 16-25) or the molded product (No. 15) was placed in a graphite crucible having an internal volume of 1000 ml to obtain a specific bulk density of 0.85 g / cm ³ , followed by heating to 1000 ° C at a rate of 3 ° C / min in a nitrogen atmosphere, and held at this temperature for 5 hours to effect dry distillation, thereby producing coke.

[0087]

(Dry distillation treatment in a rotary kiln)

A mixture (No. 13 and No. 14) or a molded product (No. 7-12) was introduced into a heated rotary kiln (diameter: 200 mm, total length: 4000 mm) at a feed rate of 1 kg / 1. Regarding the heating temperature of the rotary kiln, the temperature was brought to an inlet temperature of 400 ° C and an outlet temperature of 1000 ° C. It was held at the above temperature for 60 minutes in a nitrogen atmosphere to effect dry distillation, thereby producing coke.

[0088]

(Evaluation Method)

In the obtained coke, the specific bulk density, sulfur content, appearance, and the presence or absence of adhesion inside the unit were measured.

[0089]

(Specific bulk density) (in the table - “Specific bulk density after dry distillation (g / cm ³ )”)

A wooden cubic container, one side of which was 100 mm, was filled with coke, and the specific bulk density was determined based on the dry weight (W: g) of coke with which the container was filled. In this example, coke was considered “suitable” if the specific bulk density was 0.53 g / cm ³ or more.

[0090]

(Sulfur content) (in the table - “Sulfur content after dry distillation (%)”)

The coke sulfur concentration was measured in the same manner as for ashless coal. In this example, coke was considered suitable if the sulfur content was 2.0% or less.

[0091]

(Appearance, presence or absence of adhesion inside the unit) (in the table - “Characteristics of coke”)

The appearance of coke was observed visually and evaluated. In the case of dry distillation treatment in a chamber furnace (No. 1-6 and No. 15-25): coke, which was agglomerate-like, was considered “excellent” (in the table - “Pr”) coke, which was agglomerate-like, but with little expansion (specific bulk density: 0.53 g / cm ³ or more and less than 0.7 g / cm ³ ), considered "suitable" (in the table - "P"); coke, which was powdered, was considered "inappropriate" (in the table - "H"); and coke, which stuck and could not be unloaded (in the table, “H1”), or which expanded (in the table, “H2”), was also considered “inappropriate”. Appearance was ranked in order of preference Pr>P> (H, H1, H2).

[0092]

In the case of processing by dry distillation in a rotary kiln (No. 7-14): coke, which was layered and did not show expansion, cracking, crumbling or shedding, was considered “suitable” (in the table - “P”); coke, which was powdery or showed expansion, cracking, crumbling or shedding, was considered "inappropriate" (in the table - "H"); and coke, which was sticky and could not be unloaded, was also considered "inappropriate" (in the table - "H1"). Appearance was ranked in order of preference P> (H, H1).

[0093]

Table 1 No. Oxidation conditions Percentage Increase Mixing ratio of raw materials,
A / B / C
(% wt.) A + B The presence or absence of molding Dry distillation method The specific bulk density after dry distillation (g / cm ³ ) Content
sulfur after dry
distillation
(%) Characteristics of Coke one 200 ° C
1 hour 3% 4/48/48 52 no chamber furnace 0.45 1,6 N 2 200 ° C
1 hour 3% 5/47/48 52 no chamber furnace 0.75 1.7 Etc 3 200 ° C
1 hour 3% 10/40/50 fifty no chamber furnace 0.72 1.7 Etc four 200 ° C
1 hour 3% 20/30/50 fifty no chamber furnace 0.79 1.7 Etc 5 200 ° C
1 hour 3% 40/10/50 fifty no chamber furnace 0.63 1.7 P 6 200 ° C
1 hour 3% 42/10/48 52 no chamber furnace 0.49 1,5 H2 7 200 ° C
1 hour 3% 4/48/48 52 done rotary kiln 0.39 1,6 N 8 200 ° C
1 hour 3% 5/47/48 52 done rotary kiln 0.58 1,6 P 9 200 ° C
1 hour 3% 10/40/50 fifty done rotary kiln 0.74 1.7 P 10 200 ° C
1 hour 3% 20/30/50 fifty done rotary kiln 0.81 1,6 P eleven 200 ° C
1 hour 3% 40/10/50 fifty done rotary kiln 0.53 1,6 P 12 200 ° C
1 hour 3% 42/10/48 52 done rotary kiln - 1,5 H1 13 200 ° C
1 hour 3% 10/40/50 fifty no rotary kiln 0.40 1.7 N fourteen 200 ° C
1 hour 3% 20/30/50 fifty no rotary kiln - 1,6 H1 fifteen 200 ° C
1 hour 3% 20/30/50 fifty done chamber furnace 0.81 1,6 Etc 16 200 ° C, 0.3 h 1.50% 20/30 * / 50 fifty no chamber furnace 0.52 1.7 H2 17 200 ° C, 0.5 h 2% 20/30/50 fifty no chamber furnace 0.67 1.7 P eighteen 300 ° C, 0.5 h 6% 20/30/50 fifty no chamber furnace 0.77 1,6 Etc 19 300 ° C
1 hour 10% 20/30/50 fifty no chamber furnace 0.72 1,5 Etc twenty 200 ° C
1 hour 3% 20/20/60 40 no chamber furnace 0.79 1.8 Etc 21 200 ° C
1 hour 3% 10/10/70 thirty no chamber furnace 0.82 1.9 Etc 22 200 ° C
1 hour 3% 20/5/75 25 no chamber furnace 0.81 2.1 Etc 23 200 ° C
1 hour 3% 20/40/40 60 no chamber furnace 0.89 1.3 Etc 24 200 ° C
1 hour 3% 20/50/30 70 no chamber furnace 0.92 1,1 Etc 25 200 ° C
1 hour 3% 20/60/20 80 no chamber furnace 0.91 0.8 Etc

[0094]

As shown in table 1, in No. 2-5, No. 8-11, No. 15, No. 17-21, No. 23 and No. 24, satisfying the specified requirements of the present invention, the coke was of high purity with a sulfur content of 2.0 % or less, and its specific bulk density was also high. In addition, expansion and the like during the dry distillation treatment were largely suppressed and the coke performance was good. Moreover, in No. 5, where the mixing ratio of ashless coal was high, coke was slightly expanded. In No. 17, where the percentage increase in oxygen was lower than in other cases, the refinement of oxidized ashless coal was worse compared to other cases, and the coke was slightly expanded.

[0095]

No. 1 represents the case when the mixing ratio of ashless coal was low. In this case, since the content of ashless coal, which serves as a binder, was small, the coke became powdery during dry distillation treatment.

[0096]

No. 6 represents the case when the mixing ratio of ashless coal was high. In this case, since the ashless coal content was large, the expansion that occurred during dry distillation treatment not only led to the formation of sponge-like (porous) coke, but also significantly reduced the specific bulk density.

[0097]

No. 7 represents the case when the mixing ratio of ashless coal was low. In this case, since the ashless coal content was low, there was a transformation into a powder in a rotary kiln during dry distillation processing.

[0098]

No. 12 represents the case when the mixing ratio of ashless coal was high. In this case, not only ashless coal melted during dry distillation, but also the molded product was foamed and expanded, and as a result, the coke adhered to the inner wall of the rotary kiln and could not be unloaded.

[0099]

No. 13 represents a case where the mixture was not molded and the powder was directly subjected to dry distillation in a rotary kiln. In this case, since adequate pressure was not applied to the mixture during dry distillation, oxidized ashless coal and crude petroleum coke could not be sufficiently bound, and the coke remained in powder form.

[0100]

No. 14 represents the case where the mixture was not molded and the powder was directly subjected to dry distillation in a rotary kiln. In this case, the oxidized ashless coal and crude petroleum coke could not be sufficiently connected, similarly to case No. 13, and since the ashless coal content was increased and more than in case No. 13, the coke adhered to the inner wall of the rotary kiln due to the molten and expanded ashless coal and could not be unloaded.

[0101]

No. 16 represents the case when the oxidation time was short relative to the oxidation temperature and, in turn, the percentage increase in oxygen was low. In this case, since the content of ashless coal (all ashless coal and ashless coal, which was subjected to oxidative treatment, but had an oxygen increase percentage of less than 2.0%) was too large without the content of oxidized ashless coal, in which the percentage of oxygen increase in ashless coal was 2 , 0% or more, ashless coal foamed and expanded during dry distillation treatment, and the specific bulk density was reduced.

[0102]

No. 22 represents a case where the mixing ratio of crude petroleum coke was high. In this case, the sulfur content after dry distillation was large, and the purity of coke was low.

[0103]

No. 25 (comparative example) represents a case where the mixing ratio of crude petroleum coke was low. In this case, coke was obtained having a low sulfur content and a high specific bulk density, but since the mixing ratio of crude petroleum coke was low, coke was expensive.

[0104]

Although the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that many changes and modifications can be made therein without departing from the spirit and scope of the invention.

This application is based on Japanese Patent Application No. 2013-251219, filed December 4, 2013, the contents of which are incorporated herein by reference.

Industrial applicability

[0105]

In the present invention, coke, suitable, for example, as a reducing material for non-ferrous metallurgy, can be obtained at low cost.

Claims (20)

1. The method of producing coke, including the implementation of dry distillation of a mixture containing: ashless coal; oxidized ashless coal obtained by oxidizing treatment of ashless coal; and crude petroleum coke, in which, relative to 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke, ashless coal content is from 5 to 40 parts by weight, and the total content of ashless coal and oxidized ashless coal is from 30 to 70 mass parts. 2. The method of producing coke according to claim 1, in which the mixture is subjected to molding and then carry out dry distillation. 3. The method of producing coke according to claim 1 or 2, in which the percentage increase in oxygen of oxidized ashless coal is from 2 to 10%. 4. The method for producing coke according to claim 1, wherein the oxidative treatment is air oxidation. 5. The method of producing coke according to claim 1, in which the oxidative treatment is carried out at a temperature of 150 ° C or higher and less than the ignition temperature. 6. The method of producing coke according to claim 1, in which the dry distillation is carried out in a chamber furnace. 7. The method of producing coke according to claim 2, in which dry distillation is carried out in a rotary kiln. 8. Coke obtained by dry distillation of a mixture containing: ashless coal; oxidized ashless coal obtained by oxidizing treatment of ashless coal; and crude petroleum coke, in which, relative to 100 mass parts of all ashless coal, oxidized ashless coal and crude petroleum coke, ashless coal content is from 5 to 40 parts by weight, and the total content of ashless coal and oxidized ashless coal is from 30 to 70 mass parts.

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