Process Flowsheet Research Articles

Production of Cf-252 and other transplutonium isotopes at Oak Ridge National Laboratory

Abstract In 1957 Glenn T. Seaborg conceived and advocated for the construction of the High Flux Isotope Reactor (HFIR) and the Transuranium Processing Plant (since then renamed the Radiochemical Engineering Development Center, or REDC) at Oak Ridge National Laboratory. Heavily shielded hot cells, glove boxes, and laboratories allow recovery of transuranium elements produced in substantial quantities. Seaborg’s vision of HFIR and REDC producing milligram quantities of berkelium, californium, and einsteinium has been fulfilled beginning in 1966 through May 2019 with 78 production campaigns yielding a cumulative totals of 1.2 g of 249Bk, 10.2 g of 252Cf, 39 mg of 253Es, and 15 pg of 257Fm. Notably, 252Cf is a neutron source used in many industrial applications including oil exploration; process control systems for the cement industry, coal analysis, and power production; sources to start nuclear reactors and perform nondestructive materials analyses; homeland security and national defense detection devices; and medical research. Isotopes made available through transplutonium production at HFIR/REDC have enabled scientists to study the nuclear properties and reactions, chemical properties, optical properties, and solid-state properties of transplutonium elements. Long-lived isotopes have served as targets in heavy ion accelerators to produce heavier elements leading to the discovery of 104Rf, 105Db, 106Sg, 113Nh, 114Fl, 115Mc, 116Lv, 117Ts, and 118Og. This paper reviews the evolution of the processing flowsheets to produce, separate, and purify transplutonium isotopes, which have evolved over 50 years of operation at HFIR and REDC, and summarizes directions of future work to improve the efficiency of the production operations.

Status and perspective of CO2 absorption process

Absorption is considered as the most mature method for CO2 capture from the flue gas. This paper introduces the current state of CO2 absorption technology. In addition, we discuss the barriers associated with the absorption technology for CO2 capture and present future perspectives through recommendations for future research and development. Four activities to improve the CO2 absorption process are considered in this study, i.e., utilization of alternative solvents, utilization of alternative process modifications and process intensification, optimization of process flowsheet, and energy integration with other sections of the power plant. Two research priorities on the absorber and desorber equipment and CO2 solvents in the future research work are illustrated.

Optimal Flowsheet Design for Levulinic Acid Production from Lignocellulosic Biomass: a Superstructure-based Approach

Levulinic acid is one of the twelve sugar-based building blocks selected by the US Department of Energy as the most promising biobased chemicals. The highest potential is due to the market projection of its products, such as additive for fuels (methyl tetrahydrofuran and levulinate esters), biodegradable herbicide (delta-amino acid levulinic), resins and plasticizer (diphenolic acid). The levulinic acid can be produced from lignocellulosic biomass, the most abundant and renewable feedstock, that do not compete with food production and address sustainability for biorefineries. However, this transformation is not economically feasible yet. The search for feasibility resulted in a significant number of process alternatives, which makes the flowsheet design a complex and challenging task. The present study addresses this issue by defining a superstructure that gathers some of the most promising processes described in the literature. The alternatives were modeled and combined in a mixed-integer linear programming problem that maximize the economic objective function. The optimized process flowsheet resulted in the dilute acid pretreatment of the biomass, followed by direct conversion of cellulose into levulinic acid by HCl catalysis, the solid-liquid separation of humins, flash separation of HCl, and liquid-liquid extraction and distillation of the products. This process configuration resulted in a net present value of 818 million US$, and an internal rate of return of 36%.

Simultaneous structural and operating optimization of process flowsheets combining process simulators and metaheuristic techniques: The case of solar-grade silicon process

This paper presents a new optimization approach for the simultaneous structural optimization of process flowsheets with the operating conditions through combining process simulators with metaheuristic techniques. The proposed approach allows optimization of a superstructure in process simulators and reduce the computation time. A superstructure for different configurations for producing solar-grade silicon is considered, which includes three different configurations for solar-grade silicon production (Siemens Process, Intensified FBR Union Carbide Process, and Hybrid Process). The operating conditions with major impact in the performance of each of the proposed configuration were considered as decision variables. The improved multi-objective differential evolution (I-MODE) algorithm was selected as search method from others metaheuristic techniques because its efficiency to solve multi-objective problems in a short central process unit (CPU) time. The optimization algorithm consists in linking the process simulator software Aspen PlusTM with the metaheuristic technique. The results offered attractive options for the considered objective functions in the addressed case study.

Surrogate based optimization of a process of polycrystalline silicon production

A hybrid polycrystalline silicon production route is optimized following a two-step procedure. First, surrogate models for the main units are developed following different techniques which depend on the available information. Secondly, the optimization of the entire process flowsheet allows determining the optimal tradeoff between yield and energy consumption. A base production capacity of 2000 t/y of polycrystalline silicon is considered, with an equipment cost of 9.97 M$. Three scenarios are evaluated: maximum silicon production, minimum operating costs and maximum total profit. The maximization of the total profit is the most promising scenario, obtaining a selling price of 8.93 $/kgPoly, below the commercial price, 10 $/kgPoly. The revenue obtained is 10 M$/y, with an operating cost of 6.48 M$/y. Furthermore, a plant scale-up study was performed. If the production capacity is increased by a factor of 10, it results in a reduction of 1.03 $/kgSiPoly.

Separation and recovery of vanadium and aluminum from oxalic acid leachate of shale by solvent extraction with Aliquat 336

The solvent extraction of vanadium has been widely studied in inorganic acid systems; but less in organic acid systems. In this study, the separation and recovery of vanadium and aluminum from oxalic acid leachate of shale by solvent extraction with Aliquat 336 was investigated. The results indicated that 99.06% of vanadium was extracted and only 7.95% of aluminum was co-extracted in a counter-current extraction comprising five stages under the optimal conditions; the separation factor (β) of vanadium and aluminum was 1221. 99.32% of vanadium stripped by 8 mol/L HCl in a counter-current stripping comprising four stages, and V2O5 with a purity of 98.4% was obtained by ammonium precipitation method from the stripped vanadium solution. The speciation and extraction mechanism of vanadium were revealed. Vanadium mainly existed as a complex anion, VO(C2O4)22−, and aluminum mainly existed in the forms of Al(C2O4)2− and Al(C2O4)33− in the oxalic acid leachate of shale. The extraction mechanism of vanadium by Aliquat 336 was an anionic exchange mechanism, and the structure of the extractable complex for vanadium could be determined as [(R4N)2·VO(C2O4)2]. A process flowsheet for the separation and recovery of vanadium and aluminum from the oxalic acid leachate of shale using solvent extraction was developed, which has the advantages of rapid extraction speed and without adjusting the initial pH of solution.

A Biocascade Approach Towards the Recovery of High-Value Natural Products from Biowaste: State-of-Art and Future Trends

In a circular economy, products are made from renewable resources and the waste streams generated during production are either reused, recycled or recovered. The Biocascade methodology considers bio-waste as a resource that can be exploited to produce high-value products such as pharmaceuticals, food ingredients and nutrients; and low-value products such as feed, energy or soil conditioners. The Biocascade principle ensures optimal biomass exploitation by following a hierarchy from high-to-low value, where the waste from one process is the starting material for the next. Biowaste from plant origin is a very suitable resource for applying the Biocascade methodology, both in terms of worldwide production and of variety of components. In this review, the biowaste from sour cherry wine, ornamental kalanchoe plants and red clover feed production, have been examined for processing using a Biocascade approach. Starting from the biowaste characterization, the most relevant components have been identified highlighting their potential uses. The extraction methodology is then discussed in terms of solvent used, operating conditions and yield. Based on the information retrieved from literature, different process flowsheets have been proposed to maximize the use of the biowaste following the Biocascade perspective and targeting zero-waste generation.

Pinch Analysis Applied to Atmospheric Distillation Column

To increase the efficiency of industrial processes, mainly in petroleum refineries, the strategies to energy optimization are being developed. Thus, there is a need to know the energy consumption analysis in term of loss level and to define the procedure to recovery that. The analyses involve the flow rate study, based on energy balances that define the best strategy to use the energy, with the installation of heat exchanger networks. With the use of this procedure, we can reduce the operational costs, associated with a reduction of the level energy consumption. The study developed here was related to refinery atmospheric distillation column, using pinch technology, based on energy conservation law. The pre-flash, atmospheric distillation column and heat exchangers networks were evaluated in this study. The dates used in this study were collected from Angolan refinery, during 30 days and the results were used to mass and energy balances. Previously, the flow sheet process and established the relations between the operational parameters in industrial equipment were evaluated. The results from energy balances were used to integration study, supported by the pinch analysis using spreadsheet software, and the dates showed as composite, great composite and cascade curves. For this, were used the heat exchanger battery based on pinch analysis, to make the new networks of energy integration. After the assessment of each network with 4 to 12 heat exchangers, it was optimized to know that one with better energy consumption. The new network proposed is evaluated in term of reduction of energy consumption, minor number of heat exchangers and networks optimization. As a result of this methodology, we can see the reduction of energy consumption of 785,4 KW (utility) and 1277,1 KW (cold), respectively. On other hand, the optimization strategy adopted here allowed increase the temperature to 301ºC.

A flexible design framework for process systems under demand‐side management

AbstractDemand response (DR) has been an appealing strategy for both residential and commercial/industrial customers of electricity due to the increasing penetration of renewable energy resources into the power grid and the deregulation of the energy markets. For industrial DR participants, the management of energy consumption along with the satisfaction of production expectations is generally referred to as demand‐side management. Recent research in this area has focused mostly on process scheduling and capacity planning, especially for energy‐intensive processes. This article presents a new direction through an optimization‐based process design paradigm that allows for the potential reconfiguration of the process flow sheet in real time. Based on a case study of pump network design, a network superstructure is first defined, followed by a two‐stage stochastic optimization model. The method of progressive hedging is used to solve the resulting mixed‐integer stochastic programming problem. The results demonstrate that, under various scenarios, the reconfigurable design offers significant benefits compared to a fixed network structure in terms of total design cost and expected operating cost.

Multi-Scale Analysis of Integrated C1 (CH4 and CO2) Utilization Catalytic Processes: Impacts of Catalysts Characteristics up to Industrial-Scale Process Flowsheeting, Part I: Experimental Analysis of Catalytic Low-Pressure CO2 to Methanol Conversion

A multi-aspect analysis of low-pressure catalytic hydrogenation of CO2 for methanol production is reported in the first part (part I) of this paper. This includes an extensive review of distinguished low-pressure catalytic CO2-hydrogenation systems. Specifically, the results of the conducted systematic experimental investigation on the impacts of synthesis and micro-scale characteristics of the selected Cu/ZnO/Al2O3 model-catalysts on their activity and stability are discussed. The performance of the investigated Cu/ZnO/Al2O3 catalysts, synthesized via different methods, were tested under a targeted range of operating conditions in this research. Specifically, the performances of these tested Cu/ZnO/Al2O3 catalysts with regard to the impacts of the main operating parameters, namely H2/CO2 ratio (at stoichiometric -3-, average -6- and high -9- ratios), temperature (in the range of 160–260 °C) and the lower and upper values of physically achievable gas hourly space velocity (GHSV) (corresponding to 200 h−1 and 684 h−1, respectively), were analyzed. It was found that the catalyst prepared by the hydrolysis co-precipitation method, with a homogenously distributed copper content over its entire surface, provides a promising methanol yield of 21% at a reaction temperature of 200 °C, lowest tested GHSV, highest tested H2/CO2 ratio (9) and operating pressure (10 bar). This is in line with other promising results so far reported for this catalytic system even in pilot-plant scale, highlighting its potential for large-scale methanol production. To analyze the findings in more details, the thermal-reaction performance of the system, specifically with regard to the impact of GHSV on the CO2-conversion and methanol selectivity, and yield were experimentally investigated. Moreover, the stability of the selected catalysts, as another crucial factor for potential industrial operation of this system, was tested under continual long-term operation for 150 h, the reaction-reductive shifting-atmospheres and also even after introducing oxygen to the catalyst surface followed by hydrogen reduction-reaction tests. Only the latter state was found to affect the stable performance of the screened catalysts in this research. In addition, the reported experimental reactor performances have been analyzed in the light of equilibrium-based calculated achievable performance of this reaction system. In the performed multi-scale analysis in this research, the requirements for establishing a selective-stable catalytic performance based on the catalyst- and reactor-scale analyses have been identified. This will be combined with the techno–economic performance analysis of the industrial-scale novel integrated process, utilizing the selected catalyst in this research, in the form of an add-on catalytic system under 10 bar pressure and H2/CO2 ratio (3), for efficiently reducing the overall CO2-emission from oxidative coupling of methane reactors, as reported in the second part (part II) of this paper.

Multi-Scale Analysis of Integrated C1 (CH4 and CO2) Utilization Catalytic Processes: Impacts of Catalysts Characteristics up to Industrial-Scale Process Flowsheeting, Part II: Techno-Economic Analysis of Integrated C1 Utilization Process Scenarios

In the second part of this paper (Part II), the potentials and characteristics of an industrial-scale Oxidative Coupling of Methane (OCM) process integrated with CO2-hydrogenation, ethane dehydrogenation, and methane reforming processes are highlighted. This novel process concept comprises a direct conversion of methane to ethane and ethylene and further conversion of the resulted carbon dioxide and remaining unreacted methane, respectively, to methanol and syngas. In this context, the selected experimental results of the catalytic CO2-hydrogenation to methanol reported in the first part of this paper (Part I), were utilized to represent its industrial-scale performance. The experimental results of the mini plant-scale operation of an OCM reactor and CO2 removal units along with the experimental and industrial data available for representing the operation and performance of all process-units in the integrated process structures were utilized to perform a comparative techno-economic environmental analysis using Aspen-Plus simulation and an Aspen Economic Process Analyzer. The experimental procedure and the results of testing the sequence of OCM and CO2-hydrogenation reactors are particularly discussed in this context. It was observed that in the sequential operation of these reactors, ethylene will be also hydrogenated to ethane over the investigated catalysts. Therefore, the parallel-operation of these reactors was found to be a promising alternative in such an integrated process. The main assumptions and the conceptual conclusions made in this analysis are reviewed and discussed in this paper in the light of the practical limitations encountered in the experimentations. In the context of a multi-scale analysis, the contributions of the design and operating parameters in the scale of catalyst and reactor as well as in the process-scale represented by analyzing the type and operating conditions of the downstream-units and the process-flowsheets on the economic and environmental performance of the integrated process structures were studied. Moreover, the economic impacts of extra ethylene and methanol produced respectively via the integrated ethane dehydrogenation and CO2-hydrogenation sections were analyzed in detail. The required capital investment was found to be even smaller than the yearly operating cost of the plant. The environmental impacts and sustainability of the integrated OCM process were found to be enhanced by securing a minimum direct CO2-emission and energy-efficient conversion of CO2 and the unreacted CH4, respectively, to methanol and syngas. Besides producing such value-added by-products, efficient operation of downstream process-units was secured by minimizing the energy usage and ethylene losses. Under the considered conditions in this analysis, the specifications of the finally selected integrated OCM process structure, providing the fastest return of investments (less than 8 years), are highlighted.

Use of zeolite rocks for ceramic bricks based on brick clays and clay loams with high drying sensitivity

The possibility of using natural raw materials with the structural porosity of the rock-forming mineral (zeolite rocks) to obtain ceramic bricks was investigated. It was determined that the effectiveness of zeolite additives is determined by their dispersion, content in the mass, type of clay raw materials, as well as the temperature conditions of processing of ceramic materials. The addition of zeolite rock in the amount of 10–30% to mixtures with highly drying-sensitive clay or clay with high natural humidity acts as a moisture extractor and non-plastic additive. This additives reduces the index of drying sensitivity by a factor of 3.5–4 without impairing the material cohesiveness. It has favourable effects on the crack resistance of green products during drying and enables automated, reject-free loading of the dry products into a kiln. The improvement of the drying properties of clay raw materials is achieved by transferring part of the free water introduced from the flooded clay into a bound state by entering it into the channel-frame space of zeolite minerals. The established effect of zeolite rocks allowed to develop a method for controlling the moulding and drying properties of clays with high natural humidity and (or) with high sensitivity to drying, as well as process flow sheet for ceramic bricks from clay-zeolite compositions by the plastic method.

Multi-Scale Variability Analysis of Wheat Straw-Based Ethanol Biorefineries Identifies Bioprocess Designs Robust Against Process Input Variations

Bioprocesses based on (ligno-)cellulosic biomass are highly prone to batch-to-batch variations. Varying raw material compositions and enzyme activities hamper the prediction of process yields, economic feasibility and environmental impacts. Commonly, these performance indicators are averaged over several experiments to select suitable process designs. The variabilities in performance indicators resulting from variable process inputs are often neglected, causing a risk for faulty performance predictions and poor process design choices during scale-up. In this paper, a multi-scale variability analysis framework is presented that quantifies the effects of process input variations on performance indicators. Using the framework, a kinetic model describing simultaneous saccharification and ethanol fermentation was integrated with a flowsheet process model, techno-economic analysis and life cycle assessment in order to evaluate a wheat straw-based ethanol biorefinery. Hydrolytic activities reported in the literature for the enzyme cocktail Cellic® CTec2, ranging from 62 to 266 FPU·mL 1, were used as inputs to the multi-scale model to compare the variability in performance indicators under batch and multi-feed operation for simultaneous saccharification and fermentation. Bioprocess simulations were stopped at ethanol productivities ≤ 0.1 g·L-1·h-1. The resulting spreads in process times, hydrolysis yields, and fermentation yields were incorporated into flowsheet, techno-economic and life cycle scales. At median enzymatic activities the payback time was 7%, equal to 0.6 years, shorter under multi-feed conditions. All other performance indicators showed insignificant differences. However, batch operation is simpler to control and well-established in industry. Thus, an analysis at median conditions might favor batch conditions despite the disadvantage in payback time. Contrary to median conditions, analyzing the input variability favored multi-feed operation due to a lower variability in all performance indicators. Variabilities in performance indicators were at least 50% lower under multi-feed operation. Counteracting the variability in enzymatic activities by adjusting the amount of added enzyme instead resulted in higher uncertainties in environmental impacts. The results show that the robustness of performance indicators against input variations must be considered during process development. Based on the multi-scale variability analysis process designs can be selected which deliver more precise performance indicators at multiple system levels.

Process development for the recovery of rare earth elements and critical metals from an acid mine leachate

Acid mine leachate (AML) may be a significant source of rare earth and other critical elements needed for the manufacturing of advanced electronics and renewable energy technologies. A systematic study was performed on a natural leachate collected from a coal preparation plant that treated bituminous coal containing elevated amounts of pyrite. The leachate contained 1.96 ppm total REEs, 2.52 ppm Zn, 2.15 ppm Ni, 1.22 ppm Cu, 0.77 ppm Co, and 25 ppm Mn. Sequential precipitation using simple pH control generated a pre-concentrate containing 0.82% total REEs, 1.08% Zn, 0.91% Ni, 0.50% Cu, 0.34% Co, 7.1% Mn. The pre-concentrate was further treated by re-dissolution using a 10 M HNO3 solution, which resulted in a solution pH of 1.5. The addition of oxalic acid to selectively precipitate the REEs followed by roasting of the precipitate generated a product containing >98% rare earth oxides. More than 95% of the Cu and Zn were recovered from the residual liquid using Na2S at pH 2 and 3, respectively. The CuS and ZnS contents in the corresponding concentrates were 60% and 58%, respectively. The majority of the Co and Ni remained in the residual liquid. Based on these findings, a process flowsheet was developed to recover the REEs and critical metals from AML.

Molybdenum isotope fractionation in uranium oxides and during key processes of the nuclear fuel cycle: Towards a new nuclear forensic tool

The ability to identify the sources of nuclear materials using various analytical methods has become a major target of nuclear forensics science. However, despite the emergence of novel tools developed in recent years, it has become obvious that accurate identification of sources requires multiple tools. Here, we have developed a new isotope tool based on Mo isotopes that could be used in nuclear forensics. Molybdenum is a trace element that is found in significant levels in uranium ores (0.5–4800 ppm), uranium minerals (0.02–6000 ppm) and uranium ore concentrates (UOCs, from 0.7 to 1400 ppm). The Mo isotope composition, reported as δ98Mo was analyzed in these materials and shown to have a significant variability from −2.62 to +0.30‰ in uranium ores and from −3.50 to +0.46‰ in UOCs. In uranium ores, the largest Mo isotope fractionation is found in deposits of sedimentary origin while the few ores with a magmatic origin show limited Mo isotope fractionation. Thus, the Mo isotope ratios may ultimately be used to distinguish high temperature from low temperature uranium ores. The δ98Mo values in UOCs also show a significant range that not only originate from variations in ore compositions but can also be attributed to ore processing such as leaching, solvent extraction, resin extraction and UOC precipitation. Laboratory experiments based on existing protocols of uranium ore separation demonstrate the existence of sizeable Mo isotope fractionation associated with these processes. Experiments with solvent extraction and precipitation of ammonium diuranate and peruranate show that the refined uranium fraction is enriched in light Mo isotopes in both cases. In the case of a uranium ore (SOMAÏR, Niger) and associated UOC, the observed fractionation can possibly be assigned to the combined effect of solvent extraction and precipitation, although Mo isotope variability in ores and UOCs may make such a diagnostic difficult. Ultimately, these experiments can be used to reconstruct the Mo isotope composition of the ore, if there is sufficient knowledge about the ore processing flowsheet or to provide information about the type of uranium ore. Alternatively, it could be used to identify the process used for manufacturing a given UOC, if one can make an estimate about the composition of the ore, probably in conjunction with other tools. Our study demonstrates the potential of Mo isotopes as a useful tool in the field of nuclear forensics.

Separation of samarium from medium rare earth mixture using multi-stage counter-current extraction

A large number of bifunctional ionic liquid extractant with ammonium-based have been formulated to separate and extract rare earth (RE) ions with better extraction efficiencies and selectivities compared to conventional extractant. In this paper, a methodical study for the separation of samarium from a mixture of samarium, europium, and gadolinium using bifunctional ionic liquid, [A336][P204] was developed. The optimum condition for the extraction was explored in regard to the concentration and type of acid as well as the organic to the aqueous ratio of the mixture. The sum of extraction and scrubbing stages are then calculated using the counter-current theory. The target purity and recovery ratio was set to 99.9% and 90%, respectively. Multi-stage of counter-current extraction process for three, four, and five stages were developed to simulate the extraction process. As a result, extraction with 3.0 M HNO3 and 4:1 organic to aqueous ratio selected as the best condition based on the value of separation factor, β: 2.81. The number of stages calculated by the theory matches the stages done experimentally, which is four. The outcome of the extraction indicates a high recovery value (>90%) but with a poor purity ratio (<70%). For scrubbing stages, by theory 13 stages is required, however in the experimental work, 18 stages needed to achieve the purity of >99%. The counter-current simulation of the samarium extraction from the mixed RE solution showed that a complete separation with excellent purity and recovery is possible and a process flow sheet has been presented.

Comparison of adaptations to the engulfment model for the simulation of precipitation in confined impinging jet mixers

Micro mixing models are a key element for precipitation process simulation, as mixing can strongly influence the particle size distribution of the precipitate. Several adaptations to the asymmetrical engulfment model with different mixing zones and equation sets were developed to also enable the modelling of symmetrical mixers.We compare these models by analyzing the mixing mechanism, process flow sheet simulation and barium sulfate precipitation experiments. Our findings reveal different temporal evolutions of the mixing zone for the models without separate initialization. Abandoning separate initialization by integration of the initialization term into the model equations results in unphysical mechanism assumptions. By contrast, simulations using the model with the physically correct separate initialization do not predict the experimental results well. Consequently, the models without separate initialization are still the better choice for modelling fast precipitation in the setup chosen. Their empirical base should, however, be clearly indicated in future works.

Use of QEMSCAN® to characterize oxidized REE ore from the Bear Lodge carbonatite, Wyoming, USA

• Automated mineralogical analysis (AMA) of a complex REE deposit has characterized variations in ore types due to hydrothermal and supergene processes. • The complexity of the deposit necessitated a mineralogical survey to establish a realistic database of minerals to reference for AMA. • Resulting modes from AMA reconcile well with independent chemical assay data. • When correctly conducted, AMA provides useful data in developing mineral processing flowsheets for metallurgy, even on complex deposits with multiple ore phases. The Bear Lodge REE deposit is located in northeastern Wyoming. The Eocene carbonatite dyke and stockwork system intrudes trachytic-phonolitic rocks that contain multiple diatremes. The original magmatic characteristics of the REE-enriched carbonatite complex are strongly overprinted by carbo-hydrothermal and later supergene fluids. These fluids redistributed the REEs and created high variability in the ore mineral assemblage, as well as compositional variability within individual REE mineral species. The REE ore minerals at Bear Lodge can be classified into four types: 1. fluorocarbonates (bastnaesite, parisite, synchysite), 2. phosphates (monazite, xenotime, florencite, rhabdophane, churchite), 3. cerianite, and 4. ancylite. These minerals vary greatly in abundance, grain size, and morphology. REE distribution is heterogeneous throughout the deposit. Variations within a given REE mineral in terms of Ce depletion, Th content, degree of heavier REE enrichment, etc., create difficulties in the initial definition of discrete mineral species (i.e., by X-ray spectra) and their resultant species identification protocols for use in automated mineralogy (QEMSCAN Ⓡ in this study). Prevalent submicron-scale supergene mineralization result in hybrid spectra from multiple phases. Iterative work in reconciling QEMSCAN Ⓡ data interpretation with bulk assay, XRD, SEM, and optical petrography data allows for refinement of the protocols to quantify for both ore and gangue minerals. Use of automated mineralogy in the development of complex deposits requires rigorous review of these identification criteria in order to achieve results that can be applied with confidence to resolve mineral processing issues.

Journey Making: Applying PSE Principles to Complex Curriculum Designs

Since the 1950s, Process Systems Engineering (PSE) concepts have traditionally been applied to the process industries, with great effect and with significant benefit. However, the same general approaches and principles in designing complex process designs can be applied to the design of higher education (HE) curricula. Curricula represent intended learning journeys, these being similar to the design of process flowsheets. In this paper, we set out the formal framework and concepts that underlie the challenges in design of curricula. The approaches use generic and fundamental concepts that can be applied by any discipline to curriculum design. We show how integration of discipline-specific concepts, across time and space, can be combined through design choices, to create learning journeys for students. These concepts are captured within a web-based design tool that permits wide choices for designers to build innovative curricula. The importance of visualization of curricula is discussed and illustrated, using a range of tools that permit insight into the nature of the designs. The framework and tool presented in this paper have been widely used across many disciplines, such as science, engineering, nursing, philosophy and pharmacy. As a special issue in memory of Professor Roger W.H. Sargent; we show these new developments in curriculum design are similar to the development of process flowsheets. Professor Sargent was not only an eminent research leader and pioneer, but an influential educator who gave rise to a new area in Chemical Engineering, influencing its many directions for more than 50 years.

Methanol production based on methane tri-reforming: Process modeling and optimization

In this research an process flowsheet is introduced for carbon dioxide conversion to methanol and a mathematical framework is prepared to analyze the operability of proposed plant. The main steps in the designed process are syngas production through methane tri-reframing, syngas purification, methanol synthesis in the isothermal reactor and syngas recycling. To develop a detail framework, the methane and syngas conversion sections are heterogeneously simulated based on the energy and mass conservation laws, and integrated with the considered equilibrium-based model for separation sections. To prove the correctness of developed model, the simulations results are compared with the experimental data at the same condition. Then, an optimization problem is formulated to determine the optimal operating condition of designed process considering methanol production capacity as objective. Since feeding policy is a key strategy to shift tri-reforming reactions toward the desired condition, the applied single-bed tri-reformer in the designed process is substituted by a multi-bed reactor and methanol production capacity is calculated. It concludes that applying the multi-bed reformer changes the tri-reforming reactions toward the hydrogen synthesis side and increases the methanol production rate from 200 to 265 ton day−1.