Binder and manufacturing method

Abstract

1. A binder for extruded, pelletized, briquette, or agglomerated materials, the binder comprising 80% to 90% by weight of pyrolysis oil resulting from the pyrolysis of biomass, and 10% to 20% by weight of a thermoplastic.

Description

[Technical Field]

[0001] The present invention relates to a binder for producing briquettes, pellets or any other agglomerated material. The present invention also relates to a method for producing said binder and a method for producing briquettes using said binder. [Background technology]

[0002] Steel can currently be produced on an industrial scale through two main production routes. The most used production route today is the production of pig iron in a blast furnace, a process that relies on two main raw materials: sintered iron ore, which is reduced, and coke as a reducing agent. Both of these raw materials require sinter and coke plants, respectively, to be produced, and both of these plants have high CO2 emissions and are therefore polluting more globally.

[0003] In order to reduce its environmental footprint, the steel industry is looking for solutions to produce iron and / or carbon-containing materials without the need for sintering and coking processes.

[0004] To do so, new low temperature based manufacturing processes are being considered, such as extrusion, briquetting or pelletizing, all of which require the use of binders.

[0005] Patent JP2018-165301A describes a method for forming charcoal briquettes using a binder formed by mixing waste plastic and woody biomass with a solvent made from coal tar.

[0006] However, this type of binder is based on fossil carbon and contains toxic compounds such as BTX, a mixture of benzene, toluene, and xylene, and polycyclic aromatic hydrocarbons (PAHs), which are contaminants that have been determined to be highly toxic, mutagenic, carcinogenic, teratogenic, and immunotoxic to various life forms. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-165301 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, there is a need for binders that contain carbon and have a reduced environmental footprint. There is also a need for materials for use in the steel industry that have a reduced carbon footprint. [Means for solving the problem]

[0009] This problem is solved by a binder according to the invention which comprises 80% to 90% by weight of pyrolysis oil resulting from the pyrolysis of biomass and 10% to 20% by weight of a thermoplastic.

[0010] The binder of the invention may also have the following optional characteristics, considered separately or according to all possible technical combinations: The thermoplastic is selected from polyethylene, polystyrene, polycarbonate or a styrene derivative. - The thermoplastic is expanded polystyrene by the bead method. - The biomass is lignocellulosic biomass.

[0011] The present invention also relates to a method for producing a binder, which comprises mixing and heating a pyrolysis oil resulting from the pyrolysis of biomass with a thermoplastic at a temperature of 150°C to 220°C to produce a binder in proportions such that the binder consists of 80% to 90% by weight of the pyrolysis oil and 10% to 20% by weight of the thermoplastic.

[0012] The manufacturing method of the invention may also have the following optional features, considered separately or according to all possible technical combinations: - Biomass pyrolysis is carried out at temperatures between 450°C and 700°C. - the method further comprises the steps of pyrolyzing biomass to produce biochar and pyrolysis oil, removing water from the pyrolysis oil so that the final content of water in the dehydrated pyrolysis oil is less than 5% by weight, and mixing the dehydrated pyrolysis oil with a thermoplastic to produce a binder in proportions such that the binder comprises 80-90% by weight of the dehydrated pyrolysis oil and 10-20% by weight of the thermoplastic; the water removal step is selected from a decantation step, a fractional condensation step and a fractional crystallization step; - After the water removal process, the dehydrated pyrolysis oil is subjected to a decarbonization process before being mixed with thermoplastics; - the thermoplastics are densified before mixing, - The hot binder is cast into a mold to produce a binder ingot.

[0013] The present invention also relates to a method for producing briquettes, comprising the steps of mixing at least one material with a binder in any of the following combinations, and subjecting the mixture to a compaction step to form briquettes:

[0014] The method for producing briquettes of the invention may also have the following optional features, considered separately or according to all possible technical combinations: - at least one material is selected from coking coal, biochar, iron ore or steelmaking by-products, - The material is biochar, - The material is roll mill sludge.

[0015] The present invention also relates to a raw material comprising a binder according to the present invention and at least one material selected from coking coal, biochar, iron ore or steelmaking by-products. DETAILED DESCRIPTION OF THE INVENTION

[0016] Other features and advantages of the present invention will become apparent from the following description of the invention, which is given by way of example and is in no way limiting.

[0017] The binder according to the present invention comprises 80% to 90% by weight of pyrolysis oil resulting from the pyrolysis of biomass and 10% to 20% by weight of a thermoplastic.

[0018] The pyrolysis process is the thermal decomposition of materials at high temperatures in an inert atmosphere. Pyrolysis of biomass produces biochar or biocoal, pyrolysis gas (or syngas), and pyrolysis oil, also called biocrude or biooil. The thermal conversion of biomass, carried out under oxygen-free conditions, removes volatile organic compounds and cellulose components from the feedstock, allowing for the production of solid biofuels with characteristics similar to those of fossil coal.

[0019] In the method according to the present invention, the pyrolysis process is preferentially carried out at temperatures between 450°C and 700°C to maximize the yield of biochar and pyrolysis oil. For example, pyrolysis can be carried out using a heated screw, where the biomass is loaded into a fuel container and extracted from the container by a feed screw to the pyrolysis screw, where it is heated to temperatures between 450°C and 700°C. The biochar thus formed is extracted at the end of the screw and stored in a container. The pyrolysis gas is collected through a pipe to a gas cooler, e.g., a condenser, which separates the crude pyrolysis oil from the gas. Microwave-assisted pyrolysis (MAP) can also be used.

[0020] Biomass is a renewable organic material derived from plants and animals. Biomass sources include, in particular, wood and wood processing waste, such as firewood, wood pellets, and wood chips, sawdust and waste from boards and furniture, and black liquor from pulp and paper mills, agricultural crops and waste materials, such as corn, soybeans, sugarcane, switchgrass, woody plants, and algae, and crop and food processing residues, but also municipal solid waste, such as paper, cotton, and wool products, as well as food, garden, and wood waste, animal manure, and biological materials in human sewage. In the sense of the present invention, biomass can also include plastic residues, such as recycled waste plastics, for example, solid waste-derived fuel (SRF).

[0021] In a preferred embodiment, the biomass is lignocellulosic biomass.

[0022] To form the binder, the pyrolysis oil is mixed with a thermoplastic in proportions such that the binder contains 80% to 90% by weight of pyrolysis oil and 10% to 20% by weight of thermoplastic, and the mixing is carried out at a temperature of 150°C to 220°C.

[0023] The thermoplastic is preferably selected from polyethylene, polystyrene, polycarbonate or styrene derivatives, more preferably expanded polystyrene. Polystyrene may be used in its different forms (expanded polystyrene EPS, high-density polystyrene), and recycled polystyrene may also be used. The amount of thermoplastic containing pyrolysis oil determines the thermoplastic properties of the binder. More than 20% by weight of thermoplastic produces a bio-binder that hardens at room temperature, which can be brittle, while less than 10% by weight of waste thermoplastic produces a bio-binder that is more malleable at room temperature, which is difficult to store and handle.

[0024] In a preferred method for producing a binder according to the present invention, after pyrolysis of biomass, the pyrolysis oil is subjected to a water removal step before being mixed with a thermoplastic. Most of the water formed is chemically generated during the pyrolysis process and does not originate from the biomass material. This water removal step limits the acidity and corrosion risk of the produced binder and makes it possible to increase the efficiency of the binder production process. In fact, the presence of water can slow down production and increase energy needs.

[0025] This water removal step can be carried out using different techniques, inter alia, decantation, fractional condensation or fractional crystallization.

[0026] In a preferred embodiment, low-density thermoplastics, such as expanded polystyrene (EPS), are subjected to a pretreatment process before being mixed with pyrolysis oil, which is a densification process, such as a chemical densification process as described in patent WO 1998 / 023672. In a preferred embodiment, the solvent used in the densification process is d-limonene, which allows reducing the volume of the thermoplastic to be mixed with the pyrolysis oil to reach a suitable binder composition.

[0027] In a preferred embodiment, the hot binder resulting from the mixing is cast in a mold to form an ingot at room temperature, which allows for easier handling and storage of the binder.

[0028] The binder according to the present invention can be used to produce extruded, pelletized, briquette, or agglomerated materials. In the method for producing briquettes according to the present invention, at least one material is mixed with the binder as described above, and the mixture is subjected to a compression process to form briquettes. The at least one material can be selected from coking coal, biochar, iron ore, or steelmaking by-products.

[0029] Other manufacturing techniques, such as extrusion, pelletizing, or agglomeration, can be used to manufacture the feedstock using the binder according to the present invention and at least one material selected from coking coal, biochar, iron ore, or steelmaking by-products. The steelmaking by-products are preferably roll mill sludge. The steelmaking by-products may also be iron fines.

[0030] In a preferred embodiment, biochar resulting from the pyrolysis of biomass is mixed with a binder according to the present invention comprising pyrolysis oil from the same pyrolysis process and subjected to a briquetting process to produce biochar briquettes, which can then be fed as a carbon source into, for example, a blast furnace, or an electric arc furnace, a smelting furnace, or a direct reduction furnace.

[0031] In another embodiment, a binder is mixed with the oxidized iron ore and biochar and subjected to a pelletizing process to form iron-biochar composite pellets, which can then be subjected to a direct reduction process to reduce the iron oxide. [Example]

[0032] [Example 1] Six binders B1-B6 were prepared using different base materials for blending with thermoplastics.

[0033] Binders B1 to B4 are binders according to the invention and comprise 85% by weight of pyrolysis oil resulting from the pyrolysis of wheat straw, beechwood, sawdust and pine wood at 450°C for 45 minutes at a heating rate of approximately 10°C / min in the pyrolysis screw apparatus described above, and 15% by weight of expanded polystyrene (EPS).

[0034] B5 is a binder composed of 85% by weight of coal tar + 15% by weight of EPS, and B6 is a binder composed of 85% by weight of coal tar sludge + 15% by weight of EPS. B5 and B6 are prior art.

[0035] The manufacturing process for the six binders was the same: different ratios of oil / coal tar were mixed with EPS at a temperature of 250°C for 2 hours. The chemical compositions of the six binders were then analyzed, and the results are shown in Table 1.

[0036] [Table 1]

[0037] The binders according to the invention (B1 to B4) contain less sulfur, less BTX and less HAP and therefore they are less harmful to the environment.

[0038] [Example 2] A set of biochar briquettes was prepared using biochar as a filler and a binder according to the present invention. Beech wood was used as the biomass. The resulting pyrolysis oil was mixed with 15% EPS by weight to form a binder according to the present invention. The biochar was crushed so that at least 70% of the biochar particles had a final particle size analysis of less than 2 mm. The crushed biochar was then mixed at a temperature of approximately 150°C in a ratio of 80% biochar and 20% binder by weight. The mixture was then roll-pressed in a roll press at approximately 700 bar hydraulic pressure to ensure a linear pressure of 3 tonnes / cm width of the wheel along a wheel with a width of 160 mm.

[0039] Compared to coal briquetting, where approximately 10% by weight of binder is typically added, a larger amount of binder is required. This is due to the higher porosity of biochar relative to coal. The cold compressive strength of each briquette was then measured. Twenty measurements were performed on individual briquettes pressed in an Adamel hydraulic press operating in the range of 0 to 2000 N.

[0040] All measurements were between 1000 and 2000 N, which is sufficient to consider using briquettes as a replacement for coke in blast furnaces.

[0041] Therefore, the binder according to the present invention can be used to produce biochar briquettes with a reduced environmental footprint that are suitable for use in blast furnaces.

[0042] [Example 3] Using the same briquetting process as in Example 2, a first set of briquettes was prepared by mixing 90 wt. % coal with 10 wt. % binder according to the present invention having the same composition as the binder in Example 2.

[0043] Using the same briquetting process, a second set was prepared by mixing 90 wt. % coal with 10 wt. % petroleum pitch as a binder, i.e., prior art binder.

[0044] The cold crush strength of each briquette was then measured using the same machine as described in the previous examples.

[0045] The average compressive strength of the briquettes produced with the binder according to the present invention was 1890 N, which was higher than the average value of 650 N for the briquettes produced with the prior art binder.

[0046] Using the same amount of binder according to the invention as the prior art binder, briquettes could be prepared with higher compressive strength, which is an important characteristic of briquettes to ensure that they can be handled, transported, or stored without deterioration.

[0047] [Example 4] Iron briquettes were prepared using 8 wt. % of a binder according to the invention and 92 wt. % of an iron ore concentrate containing 65.8 wt. % iron.

[0048] The binder used contains 85% by weight of pyrolysis oil from beech wood together with 15% by weight of EPS.

[0049] The briquette properties were then analyzed, revealing that the iron content of the briquettes was 63.3 wt%. In comparison, sintered ore briquettes made from the same iron ore have an iron content of 56-58 wt%. The cold strength of the briquettes was high, better than 20 MPa, which ensured good handling and loading conditions without risk of briquette deterioration.

Claims

1. 1. A binder for extruded, pelletized, briquette, or agglomerated materials, the binder comprising 80% to 90% by weight of pyrolysis oil resulting from the pyrolysis of biomass, and 10% to 20% by weight of a thermoplastic.

2. 2. The binder of claim 1, wherein the thermoplastic is selected from polyethylene, polystyrene, polycarbonate, or a styrene derivative.

3. 3. The binder of claim 2, wherein the thermoplastic is expanded polystyrene.

4. The binder according to any one of claims 1 to 3, wherein the biomass is lignocellulosic biomass.

5. 1. A method for producing a binder, comprising mixing and heating pyrolysis oil resulting from the pyrolysis of biomass with a thermoplastic at a temperature of 150°C to 220°C to produce a binder in proportions such that the binder comprises 80% to 90% by weight of pyrolysis oil and 10% to 20% by weight of thermoplastic.

6. 6. The method of claim 5, wherein the pyrolysis of biomass is carried out at a temperature of from 450°C to 700°C.

7. A method for producing the binder according to claim 5 or 6, comprising the steps of: a. pyrolyzing biomass to produce biochar and pyrolysis oil; b. removing water from the dewatered pyrolysis oil so that the final content of water in the dewatered pyrolysis oil is less than 5% by weight; c) mixing the dehydrated pyrolysis oil with a thermoplastic to form a binder in proportions such that the binder comprises 80-90% by weight of the dehydrated pyrolysis oil and 10-20% by weight of the thermoplastic. A method comprising:

8. 8. The method of claim 7, wherein the water removal step is selected from a decantation step, a fractional condensation step, and a fractional crystallization step.

9. 9. The method according to claim 7 or 8, wherein after the water removal step, the dewatered pyrolysis oil is subjected to a decarbonization step before being mixed with a thermoplastic.

10. A method according to any one of claims 5 to 9, wherein the thermoplastic is densified before mixing.

11. The method of any one of claims 5 to 10, wherein the high temperature binder is cast in a mold to produce a binder ingot.

12. A method for producing briquettes, comprising the steps of mixing at least one material with a binder according to any one of claims 1 to 4 and subjecting the mixture to a compaction step to form briquettes.

13. 13. The method of claim 12, wherein the at least one material is selected from coking coal, biochar, iron ore, or steelmaking by-products.

14. The method of claim 13 , wherein the material is biochar.

15. The method of claim 13 wherein the material is roll mill sludge.

16. A raw material comprising the binder according to any one of claims 1 to 4 and at least one material selected from coking coal, biochar, iron ore, and steelmaking by-products.

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