Binder Pitch Research Articles

Impact of the Replacement of Pitch Binder by the Environmentally Friendly Binder System Based on Lactose and Tannin on the Properties of Carbon‐Bonded Alumina Filters

Carbon‐bonded alumina filters have been established in the steel industry for decades to increase the quality of cast steel components. The carbon bonding of the filter materials is commonly achieved by using pitches or resins. However, the pyrolysis of both substances results in the release of carcinogenic substances such as free phenols or benzo[a]pyrene. An alternative binder system is provided by lactose and tannin, which is considered to be more environmentally friendly, but they tend to result in insufficient mechanical filter properties.To ensure higher environmental sustainability and good mechanical properties, the effect of the stepwise replacement of the pitch‐binder CarboresP by lactose and tannin is investigated in the present study. Additionally, the impact of semiconductive additives (P‐doped n–Si and SiC) and the filter manufacturing method on the filter properties is analyzed. Based on the most promising filter composition, different lactose/tannin (L/T) ratios (5:1, 4:1, 3:1) are applied and the resulting properties evaluated. The results suggested that the pitch binder can be completely replaced by lactose and tannin by using SiC as additive and adjusting the filter manufacturing process. The variation of the L/T ratio shows no significant impact on the filter prope.

Improvement of tensile strength and anti-oxidation property of graphite electrode for electric arc furnace through heterogenization of binder pitch

Improvement of tensile strength and anti-oxidation property of graphite electrode for electric arc furnace through heterogenization of binder pitch

Multiscale enhancement of carbon/carbon composite performance by self-assembly of sulfonated graphene with silane-treated carbon fibers

The application prospects of carbon/carbon composites are greatly limited by interfacial cracks and pores caused by binder pitch displacement and cracking during high-temperature carbonization. In this study, silane coupling agent was coated on the surface of oxygen plasma-treated carbon fibers (CFs) and subsequently electrostatically self-assembled with sulfonated graphene (SG) to improve the interfacial bonding between filler and CTP. The results indicate that the tensile strength of carbon fiber treated with silane coupling agent increased by 19 % compared to untreated CF. This increase in strength may be related to the layer of silane coupling agent that repaired the grooves and imperfections on the CF surface. The addition of SG not only improves the distribution characteristics of the fibers, allowing the silane-treated CF to play a greater role in the matrix, but also creates a three-dimensional hydrogen-bonded cross-linking between the SG and the coal tar pitch (CTP) on the surface of the fibers. This inhibits CTP displacement and pyrolysis, achieving a tight bonding of the fiber to the matrix. The composites' structural integrity and mechanical properties were significantly improved due to the synergistic effect of silane-treated CF and SG. The compressive strength was 216.98 MPa, with a flexural strength of 54.78 MPa, 250 % higher than the untreated carbon fiber-reinforced composites. Additionally, the porosity decreased by 31.5 %, and the antioxidant properties increased. The study presents a potential solution to improve the performance of carbon/carbon composites by using the silane-treated CF-SG multiscale reinforced phase.

Effect of Sulfur on Wood Tar Biopitch as a Sustainable Replacement for Coal Tar Pitch Binders.

Coal tar pitch (CTP) is a residue formed from the distillation of coal tar and is widely used as a carbonizable and graphitizable binder for many industrial applications. However, CTP is fossil-derived and has recently been classified as a "sunset" status material under REACH due to its toxicity, which makes finding a sustainable alternative vital. In this work, bio-oil was synthesized from the pyrolysis of fresh eucalyptus sawdust, from which wood tar biopitch (WTB) was subsequently produced by a second distillation process. Chemical characterization revealed the presence of higher amounts of aromatic compounds and PAHs in the industrially used CTP relative to the WTB. Sulfur is widely used as a graphitization promoter for CTP but has not yet been used for biopitch alternatives. Hence, graphite/WTB and graphite/CTP composites were fabricated with varying amounts of sulfur and were subsequently carbonized and graphitized at 850 and 2500 °C, respectively. The use of WTB as a binder led to less porous composites after carbonization/graphitization with higher levels of shrinkage than those based on CTP, whereas the carbon yield was very similar for both systems. The incorporation of sulfur was found to promote more compact structures with higher levels of graphitization, leading to improved electrical and mechanical properties, particularly for the composites based on CTP due to the higher levels of graphitization achieved relative to the WTB. The electrical and mechanical performance found for the WTB-based composites, combined with the much lower toxicity, evidences the promise of WTB as a sustainable alternative to traditional CTP binders.

MgO–C refractories based on refractory recyclates and environmentally friendly binders

This study focused on the development of an environmentally friendly binder system based on lignin and collagen for uniaxial pressed MgO–C refractories as an alternative to commonly used resin or pitch binders. Additionally, recycled MgO–C refractories from steel plants were partially utilized as raw material, investigating their influence on the resulting physical and mechanical properties. The binder system showed reliable binding properties, although the recyclate-containing MgO–C exhibited higher porosity, slightly lower density, and lower strength compared to the reference batches without recyclates. However, antioxidants significantly improved the properties of the recyclate-containing MgO–C samples. Scanning electron microscopy analysis with energy-dispersive X-ray spectroscopy revealed the formation of whiskers, as well as oxidation and nitridation of aluminum particles. This research highlights the potential of environmentally friendly binders and the utilization of recycled materials in MgO–C refractories to mitigate their environmental impact and enhances the environmental performance of carbon containing refractory materials.

Design of Continuous Kneading System for Active Anode Material Fabrication Using Retrofitted Assembly of Co-Rotating Screw Extruder

As the demand for artificial graphite for lithium-ion battery (LIB) anode materials is on the rise, technologies for optimizing the manufacturing processes and reducing the production costs of artificial graphite are crucial. At the same time, globally, regulations on the generation of harmful volatile substances during the artificial graphite production process are also becoming increasingly stringent. In this study, we focused on a continuous kneading process that minimizes the emission of volatile substances during the manufacturing of artificial graphite. To this end, a carbonized material was first prepared from a mixture of needle coke and binder pitch and processed at 3200 °C using two types of co-rotating twin-screw extruder-based continuous kneading equipment to ultimately obtain artificial graphite. The physical properties of the carbonized as well as graphitized materials were analyzed, which revealed the superior performance of the LIB anode material, namely a discharge capacity of greater than or equal to 350 mAh/g, and an initial efficiency of 91% or higher. Thus, a continuous kneading manufacturing process that emits less harmful volatile substances and provides artificial graphite with sufficient battery performance was demonstrated.

Control of the properties of a binder pitch to enhance the density and strength of graphite blocks

Control of the properties of a binder pitch to enhance the density and strength of graphite blocks

Preparation and characterization of carbon block with coal tar pitch and phenolic resin as mixed binder

Here we present a method to prepare carbon block with excellent mechanical strength by using coal tar pitch and thermoplastic phenolic resin as a mixed binder and hexamethylene tetramine as a crosslinker. The effect of phenolic resin content in the mixed binder on properties of carbon blocks was investigated. In addition, the viscosity and fluidity of the mixed binder before and after crosslinking, and the evolution of size and pore structure of the carbon block during carbonization were systematically explored. The results revealed that the mixed binder had both low viscosity in the mixing stage and low fluidity in the carbonization stage. The low viscosity was favorable for its mixing with the pitch coke. Compared to carbon blocks with coal tar pitch binder, those with mixed binder had higher volume shrinkage during carbonization, especially the strong shrinkage at 700 °C which led to the large pore closure. The density, flexural, and compressive strength of the carbon block obtained by the mixed binder reached 1.56 g·cm−3, 34.4 MPa, and 131.3 MPa, while those of carbon blocks with the single binder were only 1.35 g·cm−3, 17.2 MPa, and 33.7 MPa.

Improvement of capacitor performance by pitch-based binder for a new alternative to polymer binders

Supercapacitors have gathered attention as one of the necessary energy storage devices. However, the use of polymer binder materials in the preparation of activated carbon-based electrodes hinders ion storage due to blocking the pore structure of activated carbons, and consequently causes reducing the electrochemical performance of EDLCs. We herein demonstrate the employment of pitch as an effective binder material for supercapacitors. The electrode using pitch binder shows a slight to decreased in specific surface area, managing to completely improve the electrochemical performance compared that PVDF binder. Such a fast and strong electrochemical performance ability of pitch-based electrodes are further investigated and verified by experimental and mechanism investigations. Benefitting from the synergistic effect exerts by a pitch in terms of EDLC, using pitch-based electrodes manifests excellent cycling and rate performances. Notably, the obtained pitch-based electrode with a high SSA of 1823 m2/g (PVDF electrode: 1,154 m2/g) delivers outstanding conductivity with 15.431 S/cm compared that a PVDF-based electrode has 6.118 S/cm. More importantly, a pitch-based binder electrode showed a remarkable capacitance of 410.6 mF/cm2 at 1 mA/cm2, as well as a favorable capacitance of 404.0 mF/cm2 after 10,000 cycles with a low-capacity decay of 1.6%. This report paves a practical route toward newly benign binder material design for high-performance EDLCs.

Utilization of steel plant waste and by-products in reactive coke making

Coke is used in the blast furnace as a fuel. To produce the coke, metallurgical coals are blended in the coal blend. But the reserves of the coking coals are limited in India. Hence, there is a need to use the non-coking coals in the blast furnace. However, there is a limitation for use of non-coking coals in the coal blend for coke making. So, an attempt was made in this study to increase the amount of non-coking coals in the coal blends. In the present work, briquetting technique was used for producing briquettes having non-coking coal up to 40%, and rest is slightly coking coal along with reactive materials and binders. Those samples were compressed in a hydraulic press to form briquettes which were then carbonized. The strength and reactivity tests of those coal briquettes were carried out to determine the optimum addition proportion of reactive materials and binders. It was found that 10% of reactive material was optimum for briquette making. The use of coal tar pitch and petroleum pitch binders were also studied, and their optimum values were obtained as 3%. It was also found that coal briquettes comprising of LD (Linz-Donawitz) slag and iron oxide exhibited higher reactivity as compared to other reactive materials.

High-temperature mechanical behavior of compact carbon-bonded alumina based on a pitch-free lactose-tannin binder system

Compact cylinders and prismatic bars of carbon-bonded alumina based on an environment-friendly lactose-tannin binder system with lactose to tannin mass ratios of 5:1, 4:1 and 3:1, completely free of the conventional but harmful pitch binder, were prepared by slip casting and uniaxial pressing, respectively. The specimens were characterized by their physical properties (density, porosity), residual carbon content as well as microstructural analysis. In addition, the rheological behavior of the slurries was studied in order to prepare the compacts by slip casting. Mechanical tests at room temperature and, in particular, at high temperatures up to 1400 °C under bending, compression and creep loading, were performed. The results showed a brittle-to-ductile transition at temperatures between 1100 °C and 1300 °C. The bending strength of the bars was significantly lower compared to previously reported pitch-based ones. Early hardening of the powder before pressing could greatly decrease the bending strength. During heating at 1500 °C, cracks occurred unexpectedly on bars to be tested, and some dark grey droplets were observed as well after cooling down. A possible reason is a synergetic interaction between structural change of the carbonaceous matrix and overheating triggered by the electromagnetic field of the inductive heating.

Fabrication of Binder Pitches Allowing for Low-Temperature Formation and High Coking Values and Examination of Mechanical Properties of Artificial Graphite Blocks Made of Binder Pitches.

The present study focused on the development of a binder pitch to allow for low-temperature forming processes when fabricating coke-based artificial graphite blocks while increasing the density of the resultant blocks. To this end, high-softening-point (200 °C) pitches were fabricated. The pitch and byproducts obtained from the pitch synthesis were then used as binders to fabricate blocks with high mechanical strength and low porosity. Pitches were fabricated using pyrolyzed fuel oil (PFO), a petroleum residue. A high-softening-point (200 °C) pitch synthesized at 420 °C for 3 h was used as a binder pitch, and conventional pitch (124 °C) was synthesized at 400 °C for 1 h and then used. Pitch byproducts were extracted according to the boiling point of naphthalene (two rings) and anthracene (three rings) with varying numbers of aromatic rings by distillation. The largest amount of pitch byproduct was obtained in the temperature range from 220 to 340 °C, and the content of naphthalene in the byproduct was the highest over the entire temperature range. The fabricated pitches at 420 °C and byproducts were mixed to form modified pitches. It was found that their softening point and coking value (CV) decreased with the increasing content of the pitch byproduct. Low-boiling point components of the byproducts were removed from the modified pitches at the kneading process temperature (200 °C), and the mass-loss rate observed in the carbonization process temperature range (200–900 °C) was comparable to that of the high-softening-point pitch. The kneading rate of the pitch and byproduct was determined and selected based on the mass-loss rate described above, and blocks were then fabricated using a hot press. Subsequently, the fabricated blocks were subjected to heat treatment for carbonization (900 °C) and graphitization (2700 °C). After the heat treatment, the true density and apparent density of the blocks were measured, and the porosity of the blocks was calculated based on these values. The porosity of the graphite block fabricated using the pitch with a softening point of 120 °C was 21.84%, while the porosity of the graphite block fabricated using the modified pitch was 14.9%. For mechanical strength analysis, their compressive strength was measured. The compressive strength of the graphite block made of the conventional pitch (CP) was measured to be 47.59 MPa, while the compressive strength of the graphite block made of pitch mixed with a byproduct distilled at 220–340 °C was 58.79 MPa. This result suggested that a decrease in the porosity resulted in increased mechanical strength. The application of the modified pitches developed in the present study temporarily decreased the softening point of the high-softening-point pitch due to the effect of the added byproducts, allowing for a low-temperature forming process. It was also possible to fabricate artificial graphite blocks with low porosity due to the high CV of the high-softening-point pitch. As a result, blocks with high mechanical strength could be obtained.

Improvement in the properties of quasi carbon composites by Tailor-made approach

Carbon/carbon composites are class of advanced engineering materials that are known for remarkable properties at elevated temperature, possibly used for aircraft brake pad, rocket nozzle and nuclear reactor wall material. Present work deals with new approach to produce quasi carbon composite entirely from the inexpensive pitch material in a single step process, which eliminates the reimpregnation step to achieve desired density. Pitch is an inexpensive product of petroleum industries and it is suitable to produce carbon materials with varieties of structures. Work involves modification of pitch by acid treatment that can improve softening point, char yield, isotropicity and aromaticity of the pitch. Binder pitch was modified by 35 % v/v HNO3 acid and it showed the softening point of 154 °C. Heat treatment was used to eliminate lighter compounds and structural changes were observed. Softening point of modified pitch was measured by standard ring-ball method. Modified pitch was characterized by elemental analysis to know the aromaticity. Modified pitch was used to make quasi carbon composite pellets by Hot-Press method. Density and porosity of quasi carbon composites were measured by standard Mettler-Toledo density meter and kerosene porosity method respectively. Microstructure, isotropicity and thermal stability were also analysed by scanning electron microscope, optical microscope and TGA respectively. Results showed that acid treated pitch has significantly improved density, microstructure and thermal stability of quasi carbon composites by tailor-made approach. This approach can be ultimately used to fabricate fiber reinforced carbon/carbon composites with improved properties.

Manufacture of carbon-bonded alumina based on a lactose-tannin binder system via slip casting

Binders play an important role in the manufacture of carbon-bonded alumina (Al2O3-C) refractory materials. To diminish the currently used coal tar pitch binder Carbores® P, which could release hazardous polycyclic aromatic hydrocarbons during operations, environmental-friendly lactose and tannin are applied as the main binders in this study. Compact cylinders of fine-grained Al2O3-C based on the lactose-tannin (16 wt%) binder system with significantly reduced pitch content (4 wt%) are successfully prepared via slip casting for the first time. The lactose to tannin mass ratio is systematically varied from 5:1 to 1:5 in the raw material formulation. The specimens based on the new binder system are less dense, more porous and contain less residual carbon than the pitch-based reference. Mechanical tests show that the specimens with lactose-tannin ratio of 5:1, 4:1 and 3:1 have considerable cold crushing strengths, although the splitting tensile strengths are low. In contrast to the well-established pressing route, the slip casting route for compact Al2O3-C is more comparable to the replica route for Al2O3-C foam filter due to the pressureless shaping process.

Application of Miniaturized Brazilian Disc Tests for the Determination of High-Temperature Strength of Ceramic Filter Materials

Open-cell ceramic foams are used for the filtration of molten metals with the aim of improving the final quality of cast products. Among the various filter materials that have been developed and studied, carbon-bonded alumina (Al2O3-C) have drawn the most attention due to their superior properties. However, to decrease the hazardous effects of coal tar pitch binder Carbores® P, environmentally friendly Al2O3-C based Tannin and Lactose binder systems have recently received much attention. A systematic characterization and assessment of their properties are required to replace the currently used binders. Considering the service temperature of these filter materials, a test method performed at elevated temperatures is needed. Due to the thermal and mechanical loads applied on these filters, the fracture strength of the bulk material is a key indicator of their structural integrity. The Brazilian Disc Test (BDT) is a method of determining fracture mechanical properties of brittle materials with indirect tensile stresses, formed perpendicular to the loading direction. Due to the porous structure of the materials under investigation, the contact points between the specimen and the loading device are susceptible to major deformation and damage. The aim of this study is on the one hand to define the geometry at the contact points in such a way that valid fracture toughness values can be determined even for small specimen dimensions. For this purpose, the deformations on the surface of the specimens are determined at room temperature using digital image correlation during the test. On the other hand, the optimized test geometry is used to perform high-temperature tests to evaluate their strength and fracture toughness. This evaluation is performed with accompanying finite element analyses using cohesive zone models. The required parameters of these models are identified using methods of nonlinear optimization.

Study of the Molecular-Weight Distribution of Binder Pitches for Carbon Blocks

The present study aimed to identify the required characteristics of binder pitches in the filler-binder mixing process to effectively manufacture graphite blocks. To this end, a binder pitch was separated into pitch fractions of varying molecular-weight segments. The role and effectiveness of each pitch fraction were then analyzed with respect to their molecular-weight distribution. As a result, the optimal molecular-weight distribution was determined. More specifically, a coal-tar pitch was separated into solvent-soluble and solvent-insoluble fractions. The molecular-weight distribution was determined according to this classification, and the characteristics of each pitch fraction were examined. The pitch separation process was conducted using three solvents: hexane, toluene, and quinoline. The resulting pitch was separated into the following pitch fractions: hexane-soluble (HS), hexane-insoluble-toluene-soluble (HI-TS), toluene-insoluble-quinoline-soluble (TI-QS), and quinoline-insoluble (QI). Fourier transform infrared (FT-IR) spectrum, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF), and softening point of each pitch fraction were measured. Also, pitch samples were refabricated while varying the mixing ratio of these pitch fractions, and carbon blocks were then prepared using them. The compressive strength and porosity of these blocks were measured and compared. The P154_B pitch with a high content of TI-QS was used to fabricate a green block. Due to the high viscosity of the binder used, the fluidity was not sufficiently high, and thus, the green block made of this pitch had relatively low strength. The other blocks had similar levels of strength. After the carbonization process, the carbon block with a high content of HS (P352_B-C) and the carbon block with the HS content removed (P073_B-C) showed lower compressive strength than their respective green-block counterparts (P352_B and P073_B). However, their strength was higher compared to those of the other carbon blocks. In the case of carbon block P073_B-C, the HS content was completely removed, and thus, the content of TI-QS (β-resin) was relatively high. Accordingly, this carbon block ended up with large amounts of components that had high coking values (CVs), and this contributed to limiting the formation of pores. Therefore, the compressive strength of this carbon block was high. In the case of the carbon block with a high content of HS (P352_B-C), a suitable level of viscosity was achieved because the HS components ensured high fluidity. As a result, blocks with higher density and compressive strength could be fabricated. The major findings of the present study confirm that producing carbon blocks with high mechanical properties requires binder pitches with a balanced combination of suitable viscosity to ensure sufficiently high fluidity and a proper level of CV to effectively suppress the formation of pores in the mixing and molding process.

Physical Property Evolution of the Anode Mixture during the Baking Process.

The Hall-Héroult process uses prebaked carbon anodes as electrodes. The anode’s quality plays a crucial role in the efficiency of the aluminium production process. During the baking process, the anode undergoes complex physicochemical transformations. Thus, the production of high-quality anodes depends, among others, on the efficient control of their baking process. This paper aims to investigate the evolution of some physical properties of the anode paste mixture during the baking process. These properties include the mass loss fraction, real and apparent densities, the ratio of apparent volume, the permeability, and porosities. For this purpose, experiments consisting of thermogravimetric analysis, dilatometry, air permeability, and helium-pycnometric measurements were carried out. The anode permeability at high temperatures was linked to the air permeability through a permeability correlator due to experimental limitations. Moreover, the real density at high temperatures was estimated by combining real densities of the coal tar pitch and coke aggregates. Different porosities, such as the open porosity and the closed porosity related to the pitch binder, were estimated by taking the permeability at high temperatures into account. In this context, the effect of the permeability correlator, which was introduced to link the permeability at high temperatures to the air permeability, was investigated through a sensitivity analysis. These results allow an estimation of the shrinking index, a new variable introduced to reflect the baking level of the anode mixture, which is linked to the volatile that is released in both open and closed pores. Afterwards, the pore pressure inside closed pores in the coal tar pitch was estimated. The obtained results highlight some new insights related to the baking process of the anode mixture. Moreover, they pave the way for better modeling of the thermo-chemo-mechanical behavior of anodes at high temperatures.

Properties of graphite blocks consisting of ordered graphite flakes with bimodal particle size distribution

AbstractPetroleum pitch‐based graphite blocks (GBs) attract considerable attention owing to their low cost, high yield, and possible application as heat sink components. However, no studies have systematically investigated the particle size distribution of GBs, their structures, and the relationship between the structures and thermal properties resulting from graphitization. Hence, herein, we present a novel method for fabricating petroleum pitch‐based GBs using natural graphite flakes (GFs) of sizes ranging between 50 and 500 μm and a bimodal particle size distribution. Furthermore, the effects of the mean GF particle size, pitch binder content, and microstructure of the GBs with low GF contents on compression molding with elevated hot‐pressing temperatures after graphitization are investigated. To investigate the effect of packing density with a GF size of 500 μm, we mix a small‐sized GF (50 μm) and low pitch binder content by kneading. In particular, specimens in the in‐plane direction with a bimodal particle size distribution of GFs and 10 wt% pitch binder yield optimum density and thermal conductivity values of 1.74 g m−3 and 384 Wm−1 K−1, respectively, after high‐temperature graphitization at 2600°C. These findings provide insights for developing high‐performance GBs for use in heat sink components with high thermal conductivity.

Effect of Process Parameter on Coal Tar Distillate Products

Coal tar pitch is broadly classified into two kinds based on their properties: Binder Pitch for aluminum and Graphite Industry Impregnated Pitch with less than 0.5% QI (Quinoline Insoluble) used in the graphite industry. To maximize value realization through downstream processing of coal tar, proposal was made to explore the feasibility of conversion of different qualities of coal tars from different steel plants to coal tar pitch (CTP) of different varieties (binder as well as zero QI impregnated for both Al & graphite industries), through first level of fractional distillation. In this study, four qualities of coal tar samples three from plant 1 (TP-1, TP-2, and TP-3) and one from plant 2 (TP-4) were collected and sent to laboratory for necessary evaluation, conversion and subsequent characterization studies. Zero QI impregnated pitch from coal tar (TP-1, TP-2, and TP-3) can also be made using solvent extraction or sedimentation process, which may not be cost-effective. Depending on the required specifications for binder & impregnated grade pitches, process parameters during vacuum distillation, were optimized through this collaborative work. On conversion of coal tar sample into coal tar pitches, QI content depends on distillation temperature, vacuum and soaking time.

Furnace Linings With Environmentally Friendly Materials

The monolithic lining solution for ferroalloys furnaces has developed from the use of hot ramming pastes with coal tar pitch binder, to cold ramming pastes with less harmful components, or non-harmful components. New materials demand improved installation procedures, but they also improve work environment. A good installation is then easier to obtain and control. Recommended changes in installation of new and health friendly materials are given together with measurements of baked properties. We have shown that coal tar pitch containing materials are robust against different heating rates and temperature plateaus, in the previous Infacon. Heating and curing of environmentally friendly materials, are often much more demanding. Measured temperatures inside a monolithic lining during baking are shown together with simulated temperatures done with COMSOL. Properties of new and old materials together with temperatures, and different heating rates are given. These show which changes that should be done in procedures when old and harmful materials are changed into health friendly materials. Temperature measurements and simulations also show when critical areas of the lining are baked, and metal production can start.