Chemical Milling Research Articles

Synthesis of cotton-like FeCoNi-Nd(OH)3 nanoparticles via reactive mechanical milling: Investigating chemical properties for cellular signaling applications

In this study, FeCoNi alloy nanoparticles were combined with Nd(OH)3 nanostructures to create unique cotton-like nanoparticles (C-NPs). These C-NPs were synthesized through an accessible, two-step reactive chemical milling process. The nanoparticles originated from a blend of metal chlorides (FeCl2, CoCl2, and NiCl2) and sodium (Na), used as a precursor in the reaction, within a SPEX milling apparatus. The Fe, Co, and Ni were maintained at equal weight percentages (1:1:1). Subsequently, NdCl3 and Na were utilized to facilitate the attachment of Nd(OH)3 nanostructures onto the FeCoNi nanoparticles through a solid-state reaction in the same SPEX milling setup. The Nd content was varied to investigate its effect on the integration of Nd(OH)3 onto the surface of CoNiFe nanoparticles. Electron microscopy revealed the formation of cotton-like nanoparticles, and the distribution of elements was identified using secondary ion mass spectrometry. The CoNiFe alloy and Nd(OH)3 phases were verified by X-ray diffraction analysis. These nanoparticles were internalized into cells via endocytosis, as observed in transmission electron microscopy images after incubation with the BT20 cell line (triple-negative breast cancer), likely due to interactions between –OH groups and the cell membrane. Following this, the cells containing C-NPs underwent photoluminescence studies, revealing two distinct emission peaks at 400 nm, and 486 nm. X-ray photoelectron spectroscopy indicated the presence of various heterostructures within the FeCoNi-Nd(OH)3 complex, which may be responsible for these emission properties.

Electrochemical removal of ethylene glycol monobutyl ether in aviation industry wastewater using a porous Ti4O7/Ti electrode

Titanium alloy chemical milling wastewater contains a significant amount of ethylene glycol monobutyl ether (EGBE), which is toxic and difficult to be degraded by microorganisms, and the emission will lead to severe environmental pollution. To solve this problem, the electrocatalytic oxidation method was employed to remove EGBE in the wastewater, in which a porous Ti4O7/Ti electrode were prepared and employed as the anode, while stainless steel acted as the cathode. The effects of current density, interelectrode distance, and stirring mode on the COD removal rate were also investigated. Results show that the COD of the wastewater significantly decreases from 12410 to 15 mg L−1 after 16 h of electrolysis at 10 mA cm−2 and electrode spacing of 1.0 cm as well as aeration stirring at 100 mL min−1. Moreover, pilot-plant scale testing reveals that the COD decreasing from 11980 to 183 mg L−1 after 24 h of electrolysis. Consequently, the utilization of porous Ti4O7/Ti electrode as anode in the electrocatalytic oxidation method presents significant potential in removal of EGBE in aviation industry wastewater.

Preparation and slow-release properties of nanocellulose composite hydrogels

Nanocellulose (CNF) was obtained from carrots using a combination of chemical treatment, mechanical milling, and ultrasonic treatment. Ultrafast preparation of maleic anhydride esterified nanocellulose was achieved by a hydrated hydrogen ion-driven dissociation, chemical cross-linking strategy based on a “one-pot” reaction method. Esterification modification with maleic anhydride reduced the crystallinity of nanocellulose and enhanced its thermal stability. High-strength drug-carrying hydrogels (MACNF/SA) with different drug loading capacities were prepared using cefixime (CFX) as a drug model and maleic anhydride esterified nanocellulose (MACNF) and sodium alginate (SA) as the main raw materials. The compressive strength of MACNF/SA hydrogels made from MACNF reached a maximum of 80.3 kPa when the mass ratio of CNF to MA was 2.5:12. Rheological property tests showed that the MACNF/SA hydrogels were pseudoplastic fluids with shear thinning. The drug release from the drug-carrying hydrogels followed non-Fickian diffusion.

Lignin extraction in chemical pulp mills: The role of flexible operation

Lignin extracted from black liquor in chemical pulp mills can potentially replace fossil carbon feedstocks in fuels and materials, thereby increasing the economic and environmental added values of woody biomass. However, since lignin extraction reduces the electricity generation of the mill, the added value depends on the characteristics of the electricity market in which the mill operates. In this study, a model mill is exposed to two different electricity price profiles: the low and steady prices of south-central Sweden in Year 2019; and the high and volatile prices of the same region in Year 2022. For the model mill, investments in lignin extraction designed to increase pulp production are economically viable and have low levels of sensitivity to electricity price levels and price volatility. The viability of lignin extraction without increased pulp production depends on the relationship between the electricity and lignin prices. With stable electricity prices, or steady mill operation, a rule-of-thumb holds that for lignin extraction to be viable, the lignin price (€/t) must be 1.8-times the average electricity price (€/MWh) plus 40 €/t for the supply of chemicals. With volatile electricity prices and flexible operation of the recovery boiler, the mill can shift the loss in electricity sales to low-price hours, thereby saving 15–70 % of the operational costs of lignin extraction, as compared to steady operation. This effect can be further enhanced by increasing the capacity of the lignin extraction process or extending the size of the black liquor storage tank. The proposed flexibility measures allow the market-integrated pulp mill to export lignin to replace fossil carbon supplies in other sectors, while supporting the electricity system during hours with high demand and low supply.

Deep autoencoder as an interpretable tool for Raman spectroscopy investigation of chemical and extracellular vesicle mixtures.

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool that provides valuable insight into the molecular contents of chemical and biological samples. However, interpreting Raman spectra from complex or dynamic datasets remains challenging, particularly for highly heterogeneous biological samples like extracellular vesicles (EVs). To overcome this, we developed a tunable and interpretable deep autoencoder for the analysis of several challenging Raman spectroscopy applications, including synthetic datasets, chemical mixtures, a chemical milling reaction, and mixtures of EVs. We compared the results with classical methods (PCA and UMAP) to demonstrate the superior performance of the proposed technique. Our method can handle small datasets, provide a high degree of generalization such that it can fill unknown gaps within spectral datasets, and even quantify relative ratios of cell line-derived EVs to fetal bovine serum-derived EVs within mixtures. This simple yet robust approach will greatly improve the analysis capabilities for many other Raman spectroscopy applications.

Machinability improvement in micro milling AlN after laser chemical milling

Processing microchannels inside laminated aluminum nitride high-temperature co-fired ceramics (AlN HTCC) packaging, a typical difficult-to-cut ceramic, can effectively solve the heat-dissipation problem of integrated chips used in smart skin. In order to improve the processing efficiency and quality of AlN, the machinability of AlN after laser chemical milling (LCM) was studied through the milling force, machined surface quality, surface defects, formation mechanism, and tool wear. This study established a milling force model that can predict the milling forces of AlN and analyses the reasons for the improvements in the milling force based on experimental data and predicted data. The results from the model and experiments demonstrated that the milling force of the laser chemical milling assisted micro milling (LCAMM) decreased by 85%–90% and 85%–95%, respectively, due to the amount of removal of a single edge was more uniform and the actual inclination angle increased during the cutting process in LCAMM. Moreover, the machined surface quality improved by 65%–76% after LCM because of less tool wear, fewer downward-propagating cracks generated during each feed, and the surface removal mode transformed from intergranular fracture to transgranular fracture, which effectively reducing tool wear and improving tool life. Finally, when feed per tooth and depth of cut were 0.4 μm/z and 5 μm, the optimal machined surface quality was obtained, with a roughness of 64.6 nm Therefore, milling after LCM can improve the machinability of AlN and providing a feasibility for the high-quality and efficient machining of microchannels.

An Electromechanical Impedance-Based Imaging Algorithm for Damage Identification of Chemical Milling Stiffened Panel

The multiple intersecting stiffeners on the chemical milling stiffened panel (CMSP) limit the application of active health monitoring methods on it. An imaging algorithm based on electromechanical impedance (EMI) and probability-weighting is proposed to achieve quantitative evaluation and localization of the damage on CMSP. The proposed algorithm compensates for the difference in sensor performance with coefficients and there is no need to determine the key parameters of the algorithm through prior experiments. In the paper, the applicability of ultrasonic guided wave (GW) and EMI on CMSP was first studied through the finite element method. Based on EMI and the mean absolute percentage deviation (MAPD), the selected damage indicator (DI), a probability-weighted damage imaging algorithm are proposed and experimentally verified. The results indicate that due to the reflection and attenuation effects of stiffeners on GW, the signal characteristics of damage scattering waves are contaminated, making it difficult to quantitatively characterize the damage from GW signals through DIs. MAPD is positively correlated with the damage degree and has consistency in characterizing the signal of different PZTs under the same working condition. The feasibility and accuracy of the proposed algorithm are verified through experiments which show a strong engineering application capability.

Development and experimental evaluation of surface enhancement methods for laser powder directed energy deposition microchannels

ABSTRACT This research evaluates Laser Powder Directed Energy Deposition (LP-DED) for producing fine feature internal microchannels. This study is focused on enhancing and characterising the surfaces of microchannels produced using techniques such as abrasive flow machining, chemical milling, chemical mechanical polishing, electrochemical machining, and thermal energy method to modify internal surfaces of microchannels made from NASA HR-1 Fe-Ni-Cr alloy. Flow testing for discharge coefficient measurement is conducted on processed microchannel samples, followed by characterisation through optical microscopy, Scanning Electron Microscopy (SEM), and Computed Tomography. Findings reveal variations in surfaces due to powder adherence, melt pool undulations, and polishing mechanisms. The study emphasises the significance of removing material equivalent to the mean powder diameter to reduce surface roughness and impact the discharge coefficient. The research proposes a ratio for planarising roughness and waviness peak height and density, offering insights for tailored surface adjustments in specific applications requiring reduced flow resistance. Highlights Internal microchannels with thin-walls were fabricated using the laser powder directed energy deposition process. Various surface enhancements and polishing processes were developed to modify the surface texture of the LP-DED channels. Flow testing was conducted to determine the discharge coefficient. Post-test characterisation was completed to obtain cross sectional area, perimeter, surface texture, and general surface condition to analyse results. Ratio of roughness and waviness peak and density (Spk/Spd and Wp/WPc) is proposed as a relevant surface characterisation parameter. Tailored surface modifications for specific end-use applications.

Process design for flexible T-profile-rolling of tailored thickness stringers with different cross sections

A new process, called flexible T-profile-rolling, is being developed to produce T-profiles with variable thickness distribution in longitudinal direction by flexible rolling. These tailored thicknesses allow for load-adapted and weight-optimised design of stringer profiles for aircrafts. The new process can replace the chemical milling currently used in the production of stringers and enables a more environmentally friendly and resource-saving production of the thickness changes. In order to achieve uniform thicknesses in the web and flange of the T-profile, a new rolling stand with rolls inclined against the T-profile and varying roll radii was developed. However, the varying roll radii cause different longitudinal strains in the profile cross-section due to the varied contact areas between the roll and the rolling stock, resulting in unwanted profile bowing. This bowing depends on the profile dimensions, as the adjacent roll radii vary over the profile cross-sections.This paper demonstrates the effects of profile dimensions on deflection through numerical investigations with different web heights, flange widths and thickness reductions. A straightening method is presented to obtain straight profiles as a function of the profile dimensions. The results show that this process can produce almost straight T-profiles with variable thicknesses for different cross section dimensions.

Fabrication of high aspect ratio grooves on aluminium nitride by laser and chemical milling enhanced micro milling

Aluminium nitride (AlN) ceramic is a typically difficult-to-machine material used in electronic packaging. Laser and chemical milling enhanced micro milling (LCMEM), a high-quality and efficient processing method for AlN, is proposed in this study. Rough machining is completed by repeated alternating laser ablation and chemical removal; the final finish is achieved by micro milling (MM). To achieve precise laser and chemical milling parameters based on the target structure, a laser and chemical milling (LCM) prediction model is established and verified; this can be used to predict the morphology of the grooves after LCM. The change trend of the grooves after LCM with the laser parameters is investigated. It was found that LCMEM can improve the surface quality by 60 %, and an optimal finishing surface with a surface roughness Ra value of 54 nm can be obtained when the feed per tooth is 0.4 µm/z. Lastly, this study uses LCMEM to produce a high aspect ratio groove with aspect ratio of 2.5 and depth of 1250 µm. Compared with conventional MM, LCMEM reduces the allowance of MM by 71.95 %, improves the groove accuracy, and reduces tool wear.

Effect of chemical milling and anodizing on the high cycle fatigue behaviour of 2024-T3 aluminium alloy

Aluminium 2024-T3 alloy, widely employed in transport aircraft wing and fuselage skin structures, necessitates thickness reduction for weight optimization. Chemical milling is utilized for this purpose; however, it removes Cladding (as a standard corrosion protection layer), prompting subsequent anodizing and sealing to provide corrosion protection. Literature indicates that anodizing or chemical milling can significantly reduce fatigue life, and limited data have been available on the life of chemically milled anodized materials. In this study, constant amplitude stress-life (S-N) testing was performed on two sets of fatigue samples: Cladded Aluminium Alloy (CAA) 2024-T3 sheet specimens (1.6 mm thick) and chemically milled, anodized and sealed (CMAS-AA) Aluminum Alloy sheet specimens (1 mm thick). S-N curves were generated at R=0.1 and room temperature under stress control. SEM micrographs showed micropores in CMAS-AA and a standard plain surface in CAA, consistent with prior findings. Both types exhibited 3-5 times shorter fatigue life than electropolished samples, as reported in MIL Handbook HDBK-5J, highlighting the importance of corrosion protection techniques for structural integrity. Residual stresses were observed, with cladded samples displaying compressive and CMAS-AA exhibiting tensile stresses. Fractography revealed no abnormal fatigue fracture features, and computed plane stress fracture toughness values estimated using measured crack size from the failed specimens matched standard values of aluminium alloys.

Industrial Data-Driven Processing Framework Combining Process Knowledge for Improved Decision-Making—Part 2: Framework Application Considering Activity-Based Costing Concepts

Operating time series data collected and stored in historian must be managed to extract their full potential. Part 1 of this paper proposed a structured way (a sophisticated approach) to process industrial data; this first part explains in detail the data processing framework used as the basis for the costing analysis present in the second part of this series. The framework considers the analysis scope definition, data management steps, and operating regimes detection and identification. The added value of this proposed framework is demonstrated in Part 2 via the use of cost accounting for operational problem-solving (debottlenecking), i.e., its practicality is validated via its application alongside a cost analysis on the brownstock washing department of a kraft pulp mill. The traditional debottlenecking approach assumes a single operating condition considering that operating regimes allow for a much more sophisticated debottlenecking study of the washing department. With the use of operations-driven cost modeling (contingent on activity-based costing concepts) and processed time series data corresponding to steady-state operation, incremental profit can be assigned to each operating regime in order to identify the most cost-efficient one. The overall objective of this two-part series is to convert processed industrial steady-state data and cost information into knowledge that can be used to optimize the washing department of a chemical pulp mill. More specifically, different operating regimes are assessed, and the most suitable operating strategy is defined. The application of activity-based costing on a large amount of historically processed industrial data led to the improvement in the operation. The identified optimal way to operate (pulp throughput, pulp conductivity, defoamer and bleaching chemical quantity, etc.) led to a profit of CAD 49 M per year. Lastly, a contribution analysis of the regimes based on PCA highlighted how the process was operated when the preferred performances happened.

Microwave wood chip treatment use in chemical pulp manufacturing (technical-economic assessment)

The low permeability of many wood species causes problems in the chemical pulp industry. These include very long cooking times, high chemical consumption, large material losses, high energy consumption, and environmental pollution. New microwave (MW) wood modification technology can provide an increase in wood permeability for liquids and gases that solves many of these problems. MW wood pre-treatment can increase pulp mill throughput, reduce chemical and power consumption, increase pulp quality and yield, and improve environmental performance. Economic modelling of this new technology use in different chemical pulp mill conditions allowed to assess the effect of capital costs, electricity costs, labour costs and other cost components to specific total costs of MW chip processing. MW chip treatment costs for pulp mills with output 50,000 to 500,000 ait dry ton (ADT) per year at electricity cost range US$0.04 to US$0.24/kWh vary in the range from US$17.7 to US$60.8 per air dry ton of pulp. Electricity costs form the most significant part – 51- 69% of the total specific costs of MW chip processing at electricity costs US$0.08 to US$0.12/kWh. New technology applications in different Russian conditions can provide benefits up to 7 – 22 Mil US$ per year for pulp mills with output of more than 200,000 ADT/year. The ecological effect and high economic advantages of this MW technology provide a good opportunity for commercialisation.

Microstructure and hydrogenation properties of RETMMg15 (RE= Nd, Gd; TM= Cu, Ni) alloys

In this study, five RETMMg15 (RE = Nd and/or Gd, TM = Ni and/or Cu) alloys have been successfully synthesized by induction melting of pure elements and characterized by XRD, BSE-SEM and EDXS. Their hydrogen storage properties have been studied from kinetic and thermodynamic points of view. The synthesized alloys NdNiMg15, NdCuMg15 and GdCuMg15 were composed of a RETMMg15 main phase with lesser proportions of α-Mg phase and other ternary phases. It has been found that substituting half of the RE (or TM) element by another RE (or TM) element leads to the formation of two solid solutions with composition: Nd0.5Gd0.5CuMg15 and NdCu0.5Ni0.5Mg15. Upon first hydrogenation, all alloys decomposed into binary or ternary hydrides. Next hydrogenation cycles allowed to store reversibly around 4.5 %wt. hydrogen. All alloys presented reduced MgH2 formation enthalpies as compared to pure Mg which is explained in term of “chemical milling”.

Integration of carbon capture in a pulp mill—effect of strategic development towards better biomass resource utilization

The pulp and paper industry has an important role in the industrial transition towards net zero or negative emissions, given its renewable biomass-based feedstock and energy supply. In particular, pulp and paper mills have large existing sources of biogenic CO2, with a high potential to contribute to carbon dioxide removal through carbon capture and storage (CCS). To effectively navigate anticipated changes in feedstock and energy markets, there is a need for a better understanding of how different technology pathways for the pulp and paper industry interact with one another, for instance, how enhanced valorization of biomass side streams may affect the potential for carbon capture. This paper aims to investigate the effect of combining carbon capture with lignin extraction in a chemical pulp mill. Pinch analysis is used to study how the targets for heat recovery, fuel usage and electricity generation, are affected by different mill and capture configurations. Based on these results, the effect on carbon flows is evaluated. The results show that when carbon capture technology is implemented and fuel use is minimized at the case-study mill, there is still enough heat available from the recovery boilers to supply the process needs without requiring usage of a utility boiler. However, when carbon capture is combined with lignin extraction, the heat production of the recovery boilers is no longer sufficient to cover the process demands, and additional heat from a utility boiler is required. However, this case implies that some of the carbon leaves the mill embedded in the extracted lignin product, which can be expected to have a higher value than captured carbon dioxide. When back-pressure electricity production was maximized for the different mill configurations, a very high fuel-to-electricity efficiency could be achieved, but since the CO2 emissions from the utility boiler were not assumed to be captured, this would lead to more carbon being emitted compared to the capture scenarios with minimized fuel use.

Fabrication of CaSiO3 LTCC high aspect ratio microstructure by laser chemical assisted micro-milling

As a new generation of chip-packaging materials, CaSiO3 LTCC substrates have the characteristics of high frequency, low thermal expansion coefficient, and low dielectric loss. These materials are widely used in radar communication and other industries. However, in the condition of high heat density, it is difficult to adapt calcium silicate with a low thermal conductivity to the heat dissipation requirements. To improve the heat dissipation performance, high-aspect-ratio heat-dissipation microchannels must be prepared on the surface of the CaSiO3 LTCC substrate. In this study, a new nanosecond laser and chemical milling-assisted micro-milling (NLCAM) method is proposed. The processing mechanism of the nanosecond laser ablation of CaSiO3 is explored and the influence of the laser parameters on the depth of the etching groove, top width, and hardness of the residual modified layer are studied by establishing a laser energy superposition model and test method. The improvement of milling force and milling surface quality by laser is studied. The results demonstrate that the laser power has the most significant effect on the ablation depth and width of the top of the CaSiO3; the excess heat diffuses outside the laser irradiation area, increasing the width of the top of the CaSiO3 beyond the designed width. With an increase in the scanning speed and scanning distance, the ablation depth exhibited a decreasing trend, corresponding to the laser energy model. Nanosecond laser chemical milling (NLCM) can reduce the hardness of the material by 72.0–77.2%. The maximum reduction in the average axial milling force was 56.8%, and the fluctuation of milling force is reduced. Compared to pure micro milling, the tool wear area of NLCAM was reduced by 89.3% and the average roughness Sa of the bottom surface of the microgroove was reduced to 0.392 μm, which confirms the high-quality and efficient machining of the CaSiO3 LTCC substrate.

Effects of etchant concentration and process temperature in chemical milling of 430 stainless steel with FeCl3

In modern manufacturing application, chemical milling is a typical nontraditional machining method to remove material from surface of workpiece. The most commonly used chemical solution which is called etchant is ferric chloride (FeCl3) in surface chemical milling of iron based alloy and various etchant concentrations can be used to corrode the desired section of material. In this study, immerse type chemical milling process is employed for stainless steel (430 type) with FeCl3 etchant. The effects of etchant concentration and process temperature (25 °C and 50 °C) have been examined experimentally. It was observed that the process temperature improved surface chemical milling performance. Moreover, chemically milled surface quality was investigated and average surface roughness values have been obtained.

Effect of graphene nanopaint on performance of solar air heater attached with inclined and winglet baffles.

Solar air heater is widely used for drying and industrial processing application. Different artificial roughened surfaces and coatings over the absorber plates are used to improve their performance of solar air heater by increasing absorption and heat transfer. In this proposed work, the graphene-based nanopaint is prepared by wet chemical and ball milling method and the prepared graphene nanopaint is characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The prepared graphene-based nanopaint is coated on the absorber plate by conventional coating method. The thermal performance of the solar air heater coated with traditional black paint and graphene nanopaint is evaluated and compared. The day's maximum energy gain by the graphene-coated solar air heater is 972.84 W, whereas traditional black paint is only 808.02 W. The average energy gain of graphene nanopaint is 655.85 W, which is 12.9% higher than the traditional black paint. The maximum thermal efficiency for solar air heater coated with graphene nanopaint is 81%. Also the average thermal efficiency of graphene-coated solar air heater is 72.5%, which has a 13.24% higher average thermal efficiency when compared to conventional black paint-coated solar air heater. The average top heat loss for solar air heater coated with graphene nanopaint is 8.48% lower than solar air heater with traditional black paint.

Comparison of Optical and Stylus Methods for Surface Texture Characterisation in Industrial Quality Assurance of Post-Processed Laser Metal Additive Ti-6Al-4V.

Additive manufacturing technologies enable lightweight, functionally integrated designs and development of biomimetic structures. They contribute to the reduction in material waste and decrease in overall process duration. A major challenge for the qualification for aerospace applications is the surface quality. Considering Ti-64 laser powder bed fusion (LPBF) parts, particle agglomerations and resulting re-entrant features are characteristic of the upper surface layer. Wet-chemical post-processing of the components ensures reproducible surface quality for improved fatigue behaviour and application of functional coatings. The 3D SurFin® and chemical milling treatments result in smoother surface finishes with characteristic properties. In order to characterise these surfaces, three methods for surface texture measurement (contact and non-contact) were applied, namely confocal microscopy, fringe projection and stylus profilometry. The aim of this work was to show their suitability for measurement of laser powder bed fusion as-built and post-processed surfaces and compare results across the evaluated surface conditions. A user-oriented rating of the methods, summarising advantages and disadvantages of the used instruments specifically and the methods in general, is provided. Confocal microscopy reaches the highest resolution amongst the methods, but measurements take a long time. The raw data exhibit large measurement artefacts for as-built and chemically milled conditions, requiring proper data post-processing. The stylus method can only capture 2D profiles and the measurement was restricted by particle agglomerations and craters. However, the method (process and instrument) is entirely standardised and handheld devices are inexpensive, making it accessible for a large group of users. The fringe projection method was the quickest and easiest regarding measurement and data post-processing. Due to large areal coverage, reproduction of location when performing repeat measurements is possible. The spatial resolution is lower than for confocal microscopy but is still considered sufficiently high to characterise the investigated surface conditions.

The chemical pulp mill as a flexible prosumer of electricity

Chemical pulp mills act as industrial-scale prosumers of energy, in that they demand heat and electricity for the production processes while supplying heat and electricity from the combustion of by-products. As such, they have potential relevance as providers of flexibility to the electricity system, supporting the integration of variable renewable electricity generation.In this study, a novel dispatch optimisation model is presented and applied to a generic mill, covering the production processes, boilers, and turbines, together with the associated storage of intermediate products. We analyse the trade in electricity between the mill and the central grid, the economic value of pulp mill flexibility, and the internal dynamics of the mill, when flexibility measures in different parts of the mill are combined.The results show that the suggested flexibility measures increase the amount of sold electricity during high-value hours and reduce the amount of sold electricity during low-value hours. In the present electricity market, the value of the electricity traded with the central grid is, thereby, increased by 1–8% compared to steady-state operation, without impacting the pulp production volume. The results reveal both synergies and conflicts between the different flexibility measures, underlining the importance of mill-wide optimisation.