Biochar petroleum coke products and methods

Abstract

Methods of producing a biochar petroleum coke product comprises blending a biochar with green petroleum coke, agglomerating the mixture with a binder to form a plurality of agglomerates, and calcining the plurality of agglomerates to form the biochar petroleum coke product. Biochar petroleum coke products comprise petroleum coke, at least 3 wt % biochar, less than 5 wt % sulfur, less than 0.5 wt % hydrogen, and less than 2 wt % ash.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to biochar petroleum coke products and methods of producing biochar petroleum coke blend products.BACKGROUND OF THE INVENTION

[0002] Biochar or other biomass derived carbon products, also known as biocoke and charcoal, can be used successfully in some metallurgical applications. In a recent review paper Non-Patent Literature 1, the use of biocokes in ferroalloy production is discussed. In this application, biocokes can offer some performance advantages over traditional materials like anthracite and petroleum coke as well as providing significant sustainability benefits. Biocokes are a renewable carbon source that can help decarbonize industrial processes. The benefits can be quantified in Life Cycle Assessments (LCA's) and a good example of this is provided in an LCA paper, Non-Patent Literature 2, on biocoke used in ferroalloy production. The Norwegian company Elkem is currently (2023) using on average ˜20% biocoke to replace fossil fuel carbons across its global operations discussed in Non-Patent Literature 3 and up to 95% at one of its plants in Paraguay. By 2031, Elkem hopes to replace 50% of their fossil fuel carbon sources with biocoke.

[0003] A substantial amount of work on biocarbon use is also being done by steel producers for both blast furnace production of steel and in electric arc furnace production. A few recent papers, Non-Patent Literature 4, 5 and 6, highlight some of the work being done in this area. For other large-scale metallurgical processes that use carbon, such as aluminum and refractory material production, biochar has not been used commercially to replace fossil fuel carbons.

[0004] An extensive amount of work has been done at the lab scale for aluminum anode applications as described in Non-Patent Literature 7 and 8. For this application, some significant property and performance problems are found with biocarbon use. The most serious of these are its low bulk density, high reactivity to CO2, low strength and elevated impurity levels for contaminants like silicon, sodium, potassium and phosphorus. These have a significant negative effect on the quality and performance of anodes used in the electrolytic production of aluminum. Calcined petroleum coke is currently used exclusively for this application due to its favourable combination of properties as described in Non-Patent Literature 9.

[0005] Another major metallurgical use for carbon materials like calcined petroleum coke (CPC) is titanium dioxide (TiO2) production. Biochar could be considered as a potential replacement or partial replacement, but it also has some fundamental problems like its low hardness and elevated levels of hydrogen and oxygen. The soft nature of biochar results in too much attrition during material conveying which generates fine particle size material which blows through the chlorination reactor resulting in excess carbon / char consumption. When fine particles blow through the reactor, they do not participate in the carbon-chlorination reaction which reduces TiO2 ore allowing the reaction with chlorine gas to form the desired product-TiCl4. The char also has a high hydrogen content (>1%) which results in excess chlorine consumption and the formation of corrosive, hydrochloric acid. One hundred percent (100%) biochar also has a very low bulk density (<0.5 g / cc), and this increases shipping costs and can give bed stability problems in a chlorination reactor.

[0006] The problem of the limited ability to use biochar or biocoke in large scale applications, such as aluminum and TiO2 production, is already well known. One research group in Canada, as described in Non-Patent Literature 10, claims that up to 3% biochar can be used to replace some of the CPC used to make anodes but this relatively small amount has attracted little interest from industry. Accordingly, producers are looking for ways to replace a larger volume of CPC (10% or higher) to have a material impact on decarbonization or expressed another way, reducing their CO2 footprint. All previous studies and work on the use of biochar for aluminum production, have focused on the simple physical process of blending biochar with CPC and then using the blend to replace 100% CPC. The problem with this approach is that the poor property profile of the biochar for these applications has a negative impact on the performance of the CPC / biochar blend.

[0007] For aluminum and TiO2 applications, no solutions exist today for overcoming some of the previously mentioned problems like poor hardness, high hydrogen contents, low bulk density, high CO2 reactivities and high impurity levels. The result is that no one making aluminum or TiO2 today, for example, is routinely using biochar or biocoke to replace a portion of the CPC feedstock. The industry has reached a consensus that this will not be possible due to the significant negative performance impact of using these materials mentioned above (biochar with low bulk density, high reactivity, and poor strength).

[0008] This invention seeks to provides a solution to the above by first mixing biochar with green petroleum coke (GPC) fines / powders / fine particles to form a mixture, pelletizing or agglomerating the mixture, and then calcining the pellets or agglomerates to produce a product that can be used successfully with a significantly higher level of biochar. This would allow industries and processes used by industries to reduce their carbon dioxide (CO2) footprint by replacing some CPC and other fossil derived carbon sources with renewable, biomass derived carbons. The benefit of this approach is that it produces an intimate, carbonized CPC product with a significant level of biochar (10% or higher) that can be used successfully in existing processes.

[0009] Combining GPC fine particles with biochar, agglomerating and then calcining overcomes many of the problems of trying to add biochar as a separate component to CPC blends. When combined with green petroleum coke fine particles, agglomerated and calcined, there is a strong interaction between the GPC fine particles and the biochar during the carbonization / calcining step that occurs. This results in a synergistic benefit and gives a product that is significantly harder and denser than simply mixing biochar with CPC.

[0010] In a couple of previous patents, Patent Literature 11 and 12, a method is described for the production of calcined petroleum coke pellets from the agglomeration and subsequent calcination of green petroleum coke fines. The method described in the present application not only builds and improves upon some of the core principals described in these patents but also expands the scope considerably by introducing a very different starting raw material in the form of biochar.

[0011] What this invention offers is a way for end users to successfully incorporate some level of biochar / biomass / biocoke as a partial replacement of traditional fossil-based carbon feedstock material. Another benefit is a reduction in net CO2 emissions since biomass feedstocks are considered a 100% renewable source. Accordingly, there is an urgent need to develop new and accessible technologies that improve biochar petroleum coke products and production methods. The solution to the problems of the biochar petroleum coke products and their production methods are described herein.REFERENCE OF INTEREST

[0012] The following references discussed above are incorporated in their entirety by reference herein.

[0013] Non-Patent Literature 1—Gerrit Ralf Surup, Anna Trubetskaya and Merete Tangstad, “Charcoal as an Alternative Reductant in Ferroalloy Production: A Review”, Processes, 8, 1432.

[0014] Non-Patent Literature 2—Gerrit Ralf Surup, Hamideh Kaffash, Yan Ma, Anna Trubetskaya, Johan Berg Pettersen, and Merete Tangstad, “Life Cycle Based Climate Emissions of Charcoal Conditioning Routes for the Use in the Ferro-Alloy Production”, Energies, 2022, 15, 3933.

[0015] Non-Patent Literature 3—2023 Elkem Annual Report, “Navigating challenges and positioning for sustainable growth”, 2023, pages 1-326.

[0016] Non-Patent Literature 4—Han Dang, et al, “Theoretical and experimental investigation on the effect of biomass injection on the utilization factor of pulverized coal and the raceway state in blast furnace”. Fuel, 375, 2024.

[0017] Non-Patent Literature 5—Alex M. A. Campos et al, “Potential Use of Biocoal in Metallurgical Coke Production”, 4th EMCR-International Conference on Energy and Material Efficiency and CO2 Reduction in the Steel Industry, Jun. 7-9, 2022, Sao Paulo, SP, Brazil.

[0018] Non-Patent Literature 6—Thomas Echterhof, “Review on the Use of Alternative Carbon Sources in EAF Steelmaking”, Metals, 2021, 11, 222.

[0019] Non-Patent Literature 7—Jesse Franklin White, Luis Miguel López Renau, and Björn Glaser, “A Review of Biocarbon Substitutes in Electrodes and Refractories for the Metallurgical Industries”, Journal of Sustainable Metallurgy, 2024.

[0020] Non-Patent Literature 8—Samuel Senanu and Asbjorn Solheim, “Biocarbon Use in the Aluminum Industry”, Light Metals, 2021, 649-656.

[0021] Non-Patent Literature 9—L. Edwards, “The History and Future Challenges of Calcined Petroleum Coke Production and Use in Aluminum Smelting”, JOM, Vol. 67, No. 2, 2015

[0022] Non-Patent Literature 10—Belkacem Amara et al, “Partial Replacement of Coke with Biocoke: Effect of Biocoke Production Temperature on Anode Quality”, Light Metals, 2023, 1089-1094.

[0023] Patent Literature 11—U.S. Pat. No. 8,491,677 B2 Pelletization and Calcination of Green Coke, Inventor: Leslie Edwards, Applicant: Rain CII Carbon LLC, Jul. 13, 2013.

[0024] Patent Literature 12—U.S. Pat. No. 8,864,854 B2, Pelletization and Calcination of Green Coke Using an Organic Binder, Inventor: Leslie Edwards, Applicant: Rain CII Carbon LLC, Oct. 21, 2014.SUMMARY OF THE INVENTION

[0025] It is therefore an object of the invention to provide biochar petroleum coke products and methods.

[0026] In one embodiment, the invention is directed to a method of producing a biochar petroleum coke product comprising mixing a biochar with green petroleum coke, wherein the green petroleum coke has an average particle size of from about 0.01 mm to about 5 mm and a volatile content from about 3 to about 30 wt %, to form a mixture with the addition of a suitable binder and then agglomerating the mixture by either pelletizing, briquetting or some other method to form a plurality of agglomerates or pellets or briquettes; and calcining the plurality of agglomerates or pellets or briquettes at a temperature of at least 1000° C. to form the biochar petroleum coke product, wherein the biochar petroleum coke product comprises at least 3 wt % to at least 50 wt % biochar.

[0027] In another embodiment, the invention is directed to a calcined biochar petroleum coke product comprising petroleum coke, at least 3 wt % biochar, less than 5 wt % sulfur, less than 0.5 wt % hydrogen, and less than 3 wt % ash, wherein the biochar petroleum coke product has a tapped bulk density from about 0.5 to about 1.0 g / cm3.

[0028] These and additional objects and advantages of the invention will be more fully apparent in view of the following detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 depicts GPC / Biochar pellets after agglomeration.

[0030] FIG. 2 shows GPC / biochar briquettes after agglomeration.

[0031] FIGS. 3A and 3B show biochar (3A) and a typical closed pore structure of the biochar material (3B).DETAILED DESCRIPTION

[0032] Specific embodiments of the invention are described herein. The invention can, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to illustrate more specific features of certain embodiments of the invention to those skilled in the art.

[0033] The terminology as set forth herein is for description of the embodiments only and should not be construed as limiting the disclosure as a whole. All references to singular characteristics or limitations of the present disclosure shall include the corresponding plural characteristic or limitation, and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made. Unless otherwise specified, “a,”“an,”“the,” and “at least one” are used interchangeably. Furthermore, as used in the description and the appended claims, the singular forms “a,”“an,” and “the” are inclusive of their plural forms, unless the context clearly indicates otherwise.

[0034] To the extent that the term “includes” or “including” is used in the description or the claims, it is intended to be inclusive of additional elements or steps, in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B), it is intended to mean “A or B or both.” When the “only A or B but not both” is intended, then the term “only A or B but not both” is employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. When the term “and” as well as “or” are used together, as in “A and / or B” this indicates A or B as well as A and B.

[0035] All ranges and parameters, including but not limited to percentages, concentrations, temperatures, parts, ratios and other numerical parameters disclosed herein are understood to encompass any and all sub-ranges subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 1 to 6.1, or 2.3 to 9.4), and to each integer (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10) contained within the range.

[0036] Any combination of method or process steps as used herein can be performed in any order, unless otherwise specified or clearly implied to the contrary by the context in which the referenced combination is made.

[0037] All percentages are percentages by weight (wt %) unless otherwise indicated.

[0038] As indicated above, the present invention provides biochar petroleum coke products and methods of producing a biochar petroleum coke product.

[0039] In one embodiment, the invention is directed to a method of producing a biochar petroleum coke product comprising mixing a biochar with green petroleum coke to form a mixture; agglomerating via pelletizing or briquetting the mixture with a binder to form a plurality of agglomerates in the form of pellets or briquettes; and calcining the plurality of agglomerates (pellets or briquettes) at a temperature of at least about 1000° C., preferably at least about 1100° C., and up to 1300° C., to form the biochar petroleum coke product. The biochar petroleum coke of the method has an average particle size of from about 0.01 mm to about 40 mm, preferably about 0.01 mm to about 10 mm for pellets and 10-40 mm for briquettes and a volatile content from about 3 to about 20 wt %. The biochar petroleum coke product produced by the method comprises at least 3 wt %, at least 5 wt %, at least 10 wt %, at least 20 wt %, at least 30 wt %, at least 40 wt %, or at least 50 wt % biochar.

[0040] Biochar is a carbon-rich material that is produced from biomass via a thermochemical conversion process. Biochar is also referred to as biomass charcoal or biocoke. Biomass can be sourced from naturally grown trees and other plant species, or it can be waste from organic material such as agricultural waste, wood, paper mill waste, food waste, yard trimming and clippings, animal waste, and sewage. In other words, biomass is the feedstock for the production of biochar. In some cases, it may be advantageous to grow and harvest particular tree or plant species that are fast growing and have ash levels and other properties that make biochars derived from these sources better suited to specific metallurgical applications.

[0041] The biomass is subjected to a thermochemical conversion to remove moisture and volatile matter and convert the biomass to a solid material or residue, namely biochar. A thermochemical conversion employs methods such as pyrolysis, torrefaction, gasification and combustion.

[0042] Typically, pyrolysis is the thermochemical conversion method used to convert biomass to biochar. Pyrolysis is a heat driven reaction where the biomass is heated to temperatures of about 300° C. to about 900° C. or more for a period of time in an oxygen deficient atmosphere. The higher the final temperature, the lower the volatile matter content and the higher the carbon content of the resulting biochar. The biomass undergoes chemical and physical changes and releases volatile matter with a wide range of compositions during heating. Pyrolysis requires little to no oxygen; therefore, the biomass is not combusted during the heat treatment step and emissions from the process are collected and either condensed to recover bio-oils or combusted in a post-pyrolysis step to destroy all volatile organic compounds (VOCs). Pyrolysis can take place in a kiln or pyrolysis reactor.

[0043] Raw or untreated biochar is generally produced by subjecting biomass to either a uniform or varying pyrolysis temperature (e.g., 300° C. to 550° C. to 750° C. or more) for a prescribed period of time in a reduced oxygen environment. This process may occur either quickly, with a high reactor temperature and short residence times; slowly with lower reactor temperatures and longer residence times; or anywhere in between. That is, the parameters of pyrolysis, including the desired temperature, the time the biomass is heated to reach the desired temperature, and the time the biomass is held at the desired temperature, will vary depending on the biomass starting material or feedstock and the desired properties of the biochar. Typically, the biomass is heated to between 300° C. and 900° C. over a period of minutes to hours. Shorter heat treatment times are typical of flash pyrolysis processes. The final product can be held at the desired finishing temperature for a set time to achieve a target volatile matter content in the final biochar product.

[0044] The objective of this invention is not to define the pyrolysis technology or process conditions since a wide range exists today. Different biomass feedstocks will require different pyrolysis conditions to achieve the desired final properties in the biochar. A critical property is the final volatile matter content. When the level is high (>12-15%), the biochar can be hazardous to transport and store due to a self-ignition and combustion risk. Again, the times and temperatures may be adjusted based on the biomass feedstock and the properties desired for the resulting biochar.

[0045] The resulting biochar is porous with varying particle sizes, porosity and volatile matter levels. The porosity and particle size of the biochar is dependent on the feedstock material and the specific pyrolysis process used to produce the biochar. Typically, the biochar has a particle size of 0.03 mm to 25 mm. It can be larger, dependent on the mechanical process used to produce the biomass prior to pyrolysis (wood chip size for example).

[0046] The porosity of the biochar may be adjusted to some extent based on the feedstock material of the biomass and the pyrolysis process used to create the biochar.

[0047] An alternative to porosity measurements is to use bulk density testing. Samples crushed to specific particle sizes are measured for their bulk density which is a simple and indirect measurement of porosity for a given material. The benefit of this method is that it allows a quick comparison of biochar products to other materials currently used including CPC, metallurgical coke, calcined anthracite etc. The biochar may have a tapped bulk density from about 0.2 to about 1.0 g / cm3, preferably from about 0.2 to about 0.6 g / cm3.

[0048] In this invention, the biochar is mixed with green petroleum coke and a suitable binder (which can include water) to form a mixture prior to agglomeration. The green petroleum coke may be green sponge, needle or shot coke, preferably green petroleum coke having sulfur levels below 8 wt %. The target sulfur level will depend on the end use application for the petroleum biochar product. Biochar materials typically have a sulfur level below 0.1% so the final product sulfur level depends on the sulfur level of the green petroleum coke.

[0049] The concentration of green petroleum coke particles in the total mixture of biochar and green petroleum coke particles may be at least about 30 wt %. Higher levels of petroleum coke will generally result in a higher strength, higher performance product for many applications but at the expense of a lower biochar content and lower CO2 reduction potential. In general, the biochar content should be maximized but experience has shown that properties deteriorate rapidly once the level exceeds 50%.

[0050] The particle size for the green petroleum coke is preferably 3 mm or less. The green petroleum coke may have an average particle size of about 0.001 mm to about 5 mm, preferably from about 0.01 mm to 3 mm and more preferably from about 0.01 mm to about 2 mm. For some applications where high uniformity and consistency are required, it may be preferable to mill both the green petroleum coke and the biochar materials to a fine particle size (<0.01 mm) prior to agglomeration.

[0051] In this case, the milled GPC and milled biochar are mixed together. The mixture is combined with a binder and then agglomerated, pelletized or briquetted to form an agglomerated, pelletized or briquetted biochar green petroleum coke product.

[0052] In one embodiment, the biochar petroleum coke product may have an ash content below 5% and more preferably below 1.5%. For most applications, a lower ash content is preferable and for some applications like anodes for aluminum production, it is critical to keep ash levels as low as possible to avoid unwanted impurities.

[0053] The amount of green petroleum coke in the total mixture of biochar petroleum coke product depends on its volatile matter (VM) content. The green petroleum coke particles may have a VM level of between 4 wt % and 20 wt %, preferably between 5 wt % and 18 wt %, more preferably between 6 wt % and 15 wt %. Comparing the carbon content of the coke particles with the carbon content of a pitch-based product, a person skilled in the art would understand that a VM level between 4 wt % and 20 wt % is comparable to a coking value of 80-96% ALCAN as determined by ASTM Test method D4715.

[0054] In another embodiment, a binder may be included in the mixture of biochar and green petroleum coke particles to provide sufficient strength for handling of the material prior to calcination. The binder may be organic or inorganic dependent on the final use for the biochar petroleum coke product. For applications sensitive to ash and impurity levels, organic based binders are preferable. The binder may be water soluble. The binder may comprise any suitable water-soluble natural or synthetic polymer, such as starch, sugar, lignosulphonate, humins, polyvinyl acetate (PVA), carboxymethylcellulose (CMC), carboxymethylcellulose (CMC) reacted with citric acid, methylcellulose or hemicellulose, or derivatives thereof.

[0055] Other suitable binders include water insoluble binders, such as coal tar pitches and petroleum pitches. These water insoluble binders are not miscible with water. Therefore, the green coke / biochar mixture needs to be dried first before the binder is added. Mixing and agglomeration will also typically require elevated temperatures depending on the softening point of the pitches.

[0056] Further, the binder can have inorganic species such as calcium lignosulfonate, sodium silicate, or a combination thereof. Another binder option is the use of bio-oils or bio-pitches collected when the biomass is pyrolyzed to form biochar. This has the benefit of recovering more value from the biomass. For applications where ash and impurity levels are less critical, for example when the product is used to replace metallurgical coke in a steel blast furnace, clay binders like bentonite can be used. Such binders have the advantage of being very low cost binders and with a calcination step, they will sinter to provide a high strength product.

[0057] When water soluble binders are used, the binder is the combination of the active organic binder (like PVA as an example) and the water itself. The water and active binder form a miscible liquid phase that helps the agglomeration process through a process of lubrication and binding. The binder may be utilized in an amount greater than 0 up to 40 wt % of the green coke, biochar mix and binder mix, and preferably between 0 and 25 wt %, and even more preferably between 0 and 15 wt % of the water and binder mix.

[0058] In a further embodiment, the mixing and agglomerating of the green petroleum coke and biochar particles with water and a binder is done at temperatures below 70° C., more preferably below 50° C., and most preferably at room temperature, meaning 20-22° C. An advantage of this embodiment is that it occurs at low processing temperatures and avoids the need for high temperature reactors. Compared to using pitch based binders, the lower temperatures with water based binders reduces the process complexity and also significantly lowers the occupational health and safety risks when using pitch based binders at higher temperatures.

[0059] The agglomerates may be formed by extruding, pelletizing and / or hydraulic pressurization including briquetting. The step of mixing and agglomerating may occur in any type of mixing apparatus that is capable of mixing and agglomerating at room temperature or higher temperatures when pitch-based binders are used. Pellet mills, disk pelletizers, pin mixers or pin agglomerators and other pelletizing equipment may be used for making agglomerates in a pellet form. For briquetting, the green coke, biochar and binder are typically premixed first and then fed to the briquetting machine. The pelletizers or agglomerators can be used to make spherical pellets of biochar green petroleum coke fine particles. The moisture content of the mixture of biochar and green petroleum coke fine particles is measured first and then the fine particles are fed to the pelletizer. A binder including water is then added to the pelletizer and mixed with the mixture of biochar and green petroleum coke fine particles to impart sufficient strength to the spherical pellets formed inside the pelletizer. One object of the invention is to make dense, low porosity calcined biochar petroleum coke pellets and one of the most important steps in this process is to make dense pellets prior to calcination.

[0060] After the step of agglomerating, the mixture is at least partially dried. Preferably the dried agglomerates contain less than 2 wt % of water, preferably less than 1 wt %. The drying step increases the strength of the pellets / briquettes to allow handling without breakage prior to the calcination step.

[0061] After the mixture of green petroleum coke and biochar has been pelletized, agglomerated or briquetted and dried, the agglomerates or pellets are calcined in a coke calcining kiln or furnace. Any coke calcining furnace or kiln can be used including a shaft calciner, rotary kiln calciner, or a rotary hearth calciner.

[0062] Some of the goals of calcining biochar green petroleum coke agglomerates are to:

[0063] 1. Remove volatile matter (VM);

[0064] 2. Make the structure denser to avoid shrinkage of coke during later use;

[0065] 3. Increase the hardness of the pellets so they do not break down readily; and

[0066] 4. Transform the structure into an electrically conductive form of carbon for later use.

[0067] Good electrical conductivity is important for some applications like aluminum production but not for others like TiO2 production, ferroalloy production, etc.

[0068] Rotary kilns are large diameter, sloped refractory lined steel-shelled cylinders which rotate during operation. Biochar and green petroleum coke agglomerates are fed continuously in one end and calcined biochar petroleum coke product is discharged from the other end at 1200-1300° C.

[0069] Shaft calciners have multiple vertical refractory shafts surrounded by flue walls. The biochar green petroleum coke agglomerates are fed into the top and travel down through the shafts and exit through a water cooled jacket at the bottom. The different calcination technologies that can be used to calcine the petroleum coke / biochar agglomerates are well described in Non-Patent literature 10 and Non-Patent literature 13.

[0070] The invention of this application therefore may utilize a combination of pelletization, agglomeration or briquetting technologies in combination with screening and milling / grinding technologies. A combination of this technology can also significantly improve the ability to use a wider range of biochar and green petroleum coke raw materials to make calcined biochar petroleum coke and significantly improve calcined biochar petroleum coke quality by making more dense agglomerates, pellets or briquettes.

[0071] After calcination, the biochar petroleum coke agglomerates or pellets may have a crush strength of about 10 lbs. to about 75 lbs., or preferably greater than (>) 20 lbs. The agglomerates may have a hardness of about 25 to about 60 on the Hardgrove Grindability Index scale or HGI, or more preferably about 30 to about 50 HGI.

[0072] Further, the calcined biochar petroleum coke pellets produced during the calcination step can then be used in any application including, but not limited to, anodes for aluminum production, steel production via the blast furnace process, titanium dioxide production, carbon raiser applications in metallurgical foundries, graphite electrode manufacture, ferroalloy production, electric arc furnace production of steel, etc. Basically, any existing application which uses calcined petroleum coke, calcined anthracite or metallurgical coke or other solid carbon feedstocks could benefit from the calcined biochar petroleum coke product.

[0073] In another embodiment, additional process steps can be added whereby all the biochar and green petroleum coke is dried first and then ground or milled to produce a fine particle size product. A wide range of industrial scale drying, crushing and milling / grinding equipment can be used to dry and then pulverize the biochar green petroleum coke to a finer particle size. There are several potential advantages to adding this drying and pulverizing step before pelletizing the biochar green petroleum coke fine particles including:

[0074] 1) The drying step will improve the efficiency of screening the green coke. There is a benefit to using GPC fines for mixing with biochar to make pellets and the screening will be more efficient and allow a smaller screen size compared to screening green coke with its typical moisture level of 6-9%.

[0075] 2) It ensures a more consistent particle size and controlled moisture level feed to the pelletizing equipment. This will ultimately lead to better control of pellet size, density and mechanical strength.

[0076] 3) It provides a well-controlled way to mix and blend together biochar green petroleum cokes with different properties. This could include cokes with different chemical, physical and structural properties and / or biochar with different chemical, physical and structural properties.

[0077] 4) It provides an excellent means for controlling the average volatile matter content of the pelletized product.

[0078] Further, if all the biochar and green coke is dried and pulverized first, cokes with a wide range of properties can be blended together and mixed with biochar to produce biochar green petroleum coke pellets which can then be calcined to produce a product having a consistent quality, good bulk and apparent density, and targeted chemical and thermal expansion properties. For example, a mixture of shot coke and sponge coke could be mixed with biochar and pelletized to produce a calcined biochar petroleum coke product with more desirable thermal expansion properties than a mixture containing 100% shot coke.

[0079] Although there have been hereinabove described specific agglomeration processes like pelletization and briquetting and calcination of biochar petroleum green coke in accordance with the present invention for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. That is, the present invention may suitably comprise, consist of, or consist essentially of the recited elements. Further, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims.

[0080] The following Examples demonstrate various embodiments of the invention.Examples

[0081] There are many different sources of biochar as described above. For many applications, it is preferable that the biochar source selected has a relatively low ash level and has been pyrolyzed to a high enough temperature to reduce the volatile matter (VM) content to less than 15%. Most biomass have a very high volatile matter and moisture content (typically >40% combined) which makes it unsuitable for use in metallurgical applications without some pyrolysis prior to use. At pyrolysis temperatures up to 500° C., moisture can be eliminated but VM contents can still be 25%. This presents a potential fire hazard when transporting the material, particularly in hot climates.

[0082] Table 1 shows the properties of several biochar materials generated through high temperature pyrolysis. The biochar labelled as Char Source A is compared to several other biochar sources tested by the inventors (labeled as Char B, Char C and Char D). Some of these have much higher VM and ash levels. Char Source A is produced from the pyrolysis of yellow pine which is a species widely used in home construction in the US but is also produced in other regions of the world.TABLE 1Biochar SourcesSiNaCaFeMnAlMgKPSampleVM %Ash %C %ppmppmppmppmppmppmppmppmppmBiochar A7.91.4788.1130280263010530508002004200Biochar B74.384.7128010067403405402901870489070Biochar C271.6174.9240103140480420704701380110Biochar D6.514.4578.81420034073501610350527018202500620Biochar E14.82.4322131053057940164Biochar F9.684.14332047874679876560Biochar G9.32.586.2967255354538649

[0083] Additional testing has been done on many of these biochars but for the purposes of this invention, results will be presented using Biochar A as a biochar source. This biochar has a hydrogen content of about 2% and a nitrogen content of about 0.5%. Another test called the Hardgrove Grindability Index or HGI was also carried out on the biochar to measure its grindability or hardness. The biochar is extremely soft with an HGI of 130-147. Any result above 100 indicates a relatively soft material and the test has an inverse relationship where a lower result indicates a harder material. By comparison, CPC used in aluminum anode production has an HGI in the range of 32-40 and for titanium dioxide production, the typical HGI range is 25-35. The typical hydrogen content for aluminum anode and titanium dioxide applications is less than 0.1%. Biochar A has a bulk density (1-2 mm size fraction of 0.2 g / cc) which is very low compared to the bulk densities of calcined petroleum coke materials used for aluminum anode, titanium dioxide and other applications referenced in this patent. These materials typically have bulk densities in the range of 0.65-1.0 g / cc. Therefore, Biochar A by itself is unsuitable for direct use in many applications due to its high ash and impurity levels, low hardness, low bulk density and high hydrogen levels.

[0084] The inventors began with experiments adding biochar to GPC to create a mixture for agglomeration. The inventors started conservatively by preparing blends with 10% and 20% biochar mixed with GPC fine particles. Each blend was thoroughly mixed in a high intensity mixer and then water and a water soluble binder were added and subject to an agglomeration process which produced spherical shaped pellets (FIG. 1). The pellets were dried and then calcined in a high temperature, lab-scale furnace to temperatures of around 1200° C. After some better-than-expected strength and HGI results, blends containing 30 wt %, 40 wt % and 50 wt % biochar were also prepared in the same manner.

[0085] The crush strength of the pellets was measured after the calcination step. Results for the pellets with different levels of biochar added are shown in Table 2, 3 and 4.TABLE 2GPC / Biochar Green Pellet Properties with Different GPC Types for Aluminum Anode ApplicationsSampleSVNiCaNaPSiFeVMAshDescription%%%%%%%%HGI%%10% biochar3.930.0530.02050.03180.01260.00390.01500.01999214.390.39with sponge20% biochar3.470.04660.01820.05920.01210.00660.02760.02469914.260.55with sponge10% milled3.530.04350.0170.04410.01650.00460.01910.028211615.340.55biocharwith sponge10% biochar4.430.0850.02780.04510.00870.00470.05880.04186013.680.63with shot20% biochar3.920.07530.02480.07190.00890.00700.07230.04236913.590.9with shot10% milled4.670.08530.02820.04160.00740.00400.03840.0195115biocharwith shotTABLE 3Calcined Petcoke / Biochar Pellet Properties for Aluminum Anode ApplicationsVBDSampleSVNiCaNaPSiFeRDLCCO2D4292Description%%%%%%%%g / ccangstrom%HGIg / cc10% biochar3.40.0630.0240.0410.0120.0050.0250.0262.0712824490.833with sponge20% biochar3.00.0550.0210.0760.0100.0080.0460.0312.0802737580.794with sponge10% milled2.90.0540.0210.0530.0160.0050.0260.0362.0122233420.847biocharwith sponge10% biochar3.80.0970.0320.0480.0090.0050.0770.0462.0512730330.909with shot20% biochar3.30.0830.0370.0920.0080.0090.0980.0522.0632642380.833with shot10% milled3.60.1050.0340.0460.0060.0040.0500.0192.0492321290.806biocharwith shotTABLE 4Calcined Petcoke / Biochar Pellet Properties for TiO2 ApplicationsCrushStrengthSample DescriptionAsh %C %N %H %S %lbsHGI10% Biochar / Coke A0.5395.10.910.092.6465.53420% Biochar / Coke A0.6995.50.860.083.1261.03530% Biochar / Coke A0.9094.20.810.162.3460.04130% Biochar / Coke Extra Binder0.9694.50.810.162.4073.03140% Biochar / Coke A1.0695.30.720.151.9634.04540% Biochar / Coke A Extra Binder1.2195.30.720.082.0532.23050% Biochar / Coke A1.1594.20.850.081.7226.037Most of the batches in Table 2, 3 and 4 were prepared using a water-soluble organic binder level in an amount of 3-5 wt % in combination with about 10% to about 20%, preferably about 12% to about 15% water but higher amounts can be used to improve the green strength of the pellets after drying if needed. Adequate strength is required to allow handling of the pellets without breakage so they can be moved via conveyor belt and other material handling equipment into a kiln for the calcination step.All the calcined crush strengths were greater than 25 lbs. which is adequate for handling, conveying and shipping the product to the end user. The strengths decrease on average as the biochar percentage increases but this is expected. What was not expected was the crush strengths being sufficient for handling, conveying and shipping the product to the end user.

[0088] The VBD (vibrated bulk density) results in Table 3 along with the CO2 reactivities and real densities are all critically important properties for aluminum anode applications. Bulk densities >0.800 g / cc are important to ensure acceptable anode densities. The CO2 reactivities are heavily dependent on the biochar levels used in the blends but values below 30% are considered a minimum requirement to limit excess anode consumptions in the aluminum electrolysis process.

[0089] The HGI results are the most surprising and significantly better than what would be expected from a simple blend of biochar and CPC. The key to this good performance is a combination of making dense, high strength green pellets and then the positive interaction that occurs between the green coke volatile matter and biochar during calcination. During this step, devolatilization of the green coke and in situ carbonization of the VM results in a high strength petroleum coke-biochar matrix. Several other researchers and inventors have tried using the physical process of agglomeration to improve biochar usability with most work done via briquetting. What is key for this invention is the combination of using biochar, green petroleum coke, agglomeration and a final calcination step. The in-situ carbonization of the green petroleum coke VM occurs during this calcination step. Relatively high temperature calcination (>1100° C.) is also necessary to increase the bulk density and strength and drive hydrogen levels in the final petroleum coke biochar product to <0.1%.

[0090] With respect to HGIs, values below 40 are preferred for aluminum anode and TiO2 applications. For TiO2 applications, the lower the HGI value, the better the biochar petroleum coke product is in terms of process performance. Products used in this application are typically transferred via pneumatic conveying and soft, high HGI materials result in too much attrition and particle breakdown.

[0091] The tapped bulk density of the calcined coke / biochar pellets after calcining show a decrease as shown in Table 5. The tapped bulk density for the starting biochar material is also shown in Table 5 and highlights just how low the bulk density of this material is.TABLE 5Tapped Bulk Density of Calcined Biochar BlendsTBD 1-2 mmTBD 2-4 mmg / ccg / cc100% Biochar0.170—10% Biochar / Coke A0.8830.95230% Biochar / Coke A0.8700.88540% Biochar / Coke A0.7460.75850% Biochar / Coke A0.6540.633

[0092] This decrease is due to the very low bulk density of biochar. As noted above, biochar has a closed, cell structure with a lot of porosity trapped within the structure, as shown in FIG. 2. Bulk density is a very important parameter for aluminum anode applications and several other applications. It also has a direct impact on shipping costs since lower bulk density materials require more stowage volume for a given weight. For TiO2 applications, bulk density is not such a critical quality parameter.

[0093] In summary, the biochar petroleum coke product, can be useful for large-scale production of aluminum anodes and TiO2. The products are also expected to have excellent potential for use in other metallurgical processes such as ferroalloy production, steel production via blast furnaces and electric arc furnaces (EAF)'s, carbon content adjustment of steel alloys and other applications where there is a desire to replace fossil fuel based carbons with biochars or biocarbons. This invention overcomes the inherent strength disadvantages of using the biochar in an unaltered form. Whilst the density decrease cannot be fully compensated for with this technology, the decrease is not as substantial as adding unprocessed biochar to a regular coke blend. Green petroleum coke is also widely available and unique in its ability to form an in situ binder during the calcination / carbonization step.

[0094] The specific embodiments and examples described herein are exemplary only and are not limited to the invention defined in the claims. Additionally, while the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, such descriptions are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative compositions and processes, or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.

Claims

1. A method of producing a biochar petroleum coke product, the method comprising the steps of:blending a biochar with green petroleum coke, wherein the green petroleum coke has an average particle size of from about 0.01 mm to about 5 mm and a volatile content from about 3 to about 20 wt % to form a mixture;agglomerating the mixture with a binder, which can include water, to form a plurality of agglomerates; andcalcining the plurality of agglomerates at a temperature of at least 1000° C. to form the biochar petroleum coke product, wherein the biochar petroleum coke product comprises at least 3 wt % to at least 50 wt % biochar.

2. The method of claim 1, wherein at least about 50%, or at least about 60%, or at least about 75%, or at least about 85% of the green petroleum coke has a particle size of less than 5 mm.

3. The method of claim 1, wherein the plurality of agglomerates has a particle size of from about 0.01 mm to about 10 mm for pellets and up to 40 mm for briquettes.

4. The method of claim 1, wherein the binder is an organic binder.

5. The method of claim 1, wherein the binder comprises at least one of ammonium or calcium lignosulfonate, sodium silicate, starch, polyvinyl alcohol, CMC, sugar, molasses, dextrin, clay, bentonite and other commonly available binders or a combination thereof.

6. The method of claim 1 wherein the binder is a pitch type binder including the common forms of coal tar pitch and petroleum pitch.

7. The method of claim 1, wherein the agglomerating step includes a pellet mill or press, extrusion, spherical pelletizing equipment like pin and disk pelletizers, and / or hydraulic pressurization including briquetting to form the agglomerates.

8. The method of claim 1, wherein the calcining step is conducted at a temperature of at least about 1000° C.

9. The method of claim 1, wherein the calcining step is conducted at a temperature to at least about 1100° C.

10. The method of claim 1, wherein the calcining step is conducted at a temperature to at least about 1200° C.

11. The method of claim 1, wherein the calcining step further comprises increasing the bulk density of the plurality of agglomerates by at least 10%.

12. A biochar petroleum coke product comprising:petroleum coke;at least 3 wt % biochar;less than 5 wt % sulfur;less than 0.5 wt % hydrogen; andless than 2 wt % ash,wherein the biochar petroleum coke product has a density from about 0.6 to about 1.0 g / cm3.

13. The biochar petroleum coke product of claim 12, comprising at least 5 wt % biochar.

14. The biochar petroleum coke product of claim 12, wherein the biochar petroleum coke product has a tapped bulk density from about 0.6 to about 1 g / cm3.

15. The biochar petroleum coke product of claim 12, comprising from about 40 wt % to about 95 wt % petroleum coke.

16. The biochar petroleum coke product of claim 12, wherein the petroleum coke comprises an average particle size of from about 0.01 mm to about 5 mm, or from about 0.01 mm to about 3 mm, or from about 0.01 mm to about 2 mm.

17. The biochar petroleum coke product of claim 12, where the starting green petroleum coke and biochar materials are milled to a fine particle size such as 90%-200 Tyler mesh or about 75 μm.

18. The biochar petroleum coke product of claim 12, wherein the biochar petroleum coke product has a crush strength from about 20 lbs. to about 100 lbs.

19. The biochar petroleum coke product of claim 12, wherein the biochar petroleum coke product has a hardness from about 25 to about 50 on a Hardgrove Grindability Index scale (HGI).

20. A method for the manufacturing of aluminum anodes formed from the biochar petroleum coke product of claim 12.

21. A method for the manufacturing of titanium dioxide from the biochar petroleum coke product of claim 12.

22. A method for the manufacturing of other metallurgical products including steel, ferro-alloys and other products from the biochar petroleum coke product of claim 12.

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