Process Flowsheet Research Articles

Формальное определение элементов технологической схемы обогащения на основе анализа свойств перерабатываемого сырья.

A variant of a formal solution to the problem of determining methods and apparatus for the synthesis of mineral processing flowsheets is offered in the article. The solution is based on a comparative analysis of the processed raw materials properties and the separation equipment characteristics. The dependence of properties and characteristics on the particle size of the processed mass flow is taken into account. Solutions for the cases of simple and complex ore concentration are considered. The necessary information from the field of mineral processing is presented. The urgency of improving the efficiency of natural and industrial complexes engaged in the extraction and processing of mineral resources in the Arctic zone of the Russian Federation is emphasized.

Multi-Aspect Comparison of Ethyl Acetate Production Pathways: Reactive Distillation Process Integration and Intensification via Mechanical and Chemical Approach

This paper provides a multi-aspect comparison of selected methods of ethyl acetate production and shows the possibility of further reactive distillation process integration and sophisticated intensification including process stream regeneration. The production pathways were selected with respect to their practical applicability and sufficient experimental and feasibility studies already published. A total of four case studies were designed and compared: conventional process set-up (ethyl acetate is produced in a chemical reactor) is designed as a base case study; reactive distillation with a separation unit is derived from the conventional process set-up. The mechanical and chemical approach to reactive distillation process intensification and integration were assumed: reactive distillation column with a stripper and reactive distillation column with an auxiliary chemical reaction (ethylene oxide hydration). Process models were compiled in the Aspen Plus software. Complex process flowsheets of selected case studies including separation and regeneration were designed and optimized. Three different points of view were applied to evaluate the selected process benefits and drawbacks. Process energy, economy, and safety were assessed. As a result, a reactive distillation column with an auxiliary chemical reaction has been proven to be the most suitable pathway for ethyl acetate production assuming all three evaluated aspects.

Conceptual design of chemical devices

AbstractChemical devices are chemical products that transform a feed stream into an outlet stream with the desired attributes by performing reaction, fluid flow, heating, cooling, and/or separations. They resemble small chemical plants and can be described by device flowsheets, similar to the process flowsheets of chemical plants. This article proposes a generic design framework for chemical devices. It shares some steps with Douglas' hierarchical design procedure for chemical processes but has its own distinguishing features such as capturing of consumer preferences, formulation of an engineering statement, and the use of unconventional processing techniques in device manufacturing. Two examples, domestic dehumidifier and air purifier, are discussed to illustrate the design framework. A new dehumidifier design was found using this framework.

Developed Process Circuit Flowsheet of Al Amar Ore for Production of Nanocrystalline Ferrite and Improving Gold Recovery.

Al Amar gold ore is rich in sulfides of base metals and is commercially applied for the production of copper concentrate via floatation and gold bullion by cyanidation of tailing. The current process flowsheet suffers from low gold recovery (∼60%) and loss of metals in the hazardous stockpiled residue. This work addresses these drawbacks by a newly experimental redesign of the process circuit. The innovative flowsheet comprises a sequence of operations, including acid leaching of the roasted ore, gold recovery from the leach residue, and preparation of a valuable zinc–copper–lead ferrite from the filtrate by coprecipitation followed by heat treatment. The ore is roasted at 650 °C and then leached in 20% HCl, where most of Zn, Cu, Pb, and Fe contents are dissolved, while pristine gold remains in the residue. Most of the gold (∼93%) can be recovered by cyanidation of the acid leach residue. Stoichiometric ratios of dissolved Zn, Cu, Pb, and Fe in the acid leach solution can be kept at 0.6:0.3:0.1:2.0, respectively, only by adding a small amount of ferric chloride. These metals are coprecipitated at varying pH values from 8 to 10, and the produced powders are annealed at temperatures from 600 to 1100 °C. X-ray diffraction (XRD) charts reveal sharp peaks of the targeted Zn0.6Cu0.3Pb0.1Fe2O4 phase at 600 °C, while a highly crystalline single phase is obtained at 1100 °C, independently of precipitation pH. The crystalline size of the produced powders increases with annealing temperatures (from 18–27 nm at 600 °C to 85–105 nm at 1100 °C). The finest size is found at pH 12. Scanning electron microscopy (SEM) investigation shows uniform cubic microstructures of samples annealed at 1100 °C. The produced ferrite powders exhibit soft magnetic characteristics. Saturation magnetization, Ms, substantially increases with pH. Coercivity, Hc, increases with increasing annealing temperatures, from 600 to 800 °C, and decreases above 800 °C. Preliminary cost–benefit analysis revealed that the profit margin of the proposed process flowsheet is promising. The wastewater is almost free of heavy metals. Our advances in high gold recovery and preparation of valuable magnetic nanocrystalline ferrite provide exciting opportunities to enhance and maximize Al Amar ore production for practical applications.

Optimisation of post-combustion carbon dioxide capture by use of a fixed site carrier membrane

This study presents a superstructure based mathematical model for the optimisation of the CO2 capture process from flue gas by use of a fixed site carrier membrane. The goal is to determine the optimum process flow sheet that gives the minimum total cost whilst achieving 90 % recovery and 95 % purity of CO2. The model is applied to a case study of a coal-fired power plant to assess the merits of the optimisation and the feasibility of implementing the membrane at a large scale. The membrane properties used in the simulation are obtained from the literature. This work involves the use of an accurate expression for CO2 permeance of CO2 in a poly-amine fixed site carrier membrane in relation to CO2 partial pressure. This allows pressure to be a variable in the optimisation problem. The use of water vapour as sweep is also explored and compared to the vacuum-driven only process. The application of the model results in a decrease in membrane area requirement of 46 % and a decrease of 13.6 % in the cost of CO2 avoided compared to a pre-determined two stage cascade process operating at uniform pressure. The results show that the use of water vapour as sweep in conjunction with vacuum pumps on the other membrane stages is more economical compared to the use of vacuum pumps only.

Nonlinear model predictive control of ultra-high-purity air separation units using transient wave propagation model

Model reduction techniques can be used to reduce the computational burden associated with nonlinear model predictive control (NMPC). In our recent work, we introduced the transient nonlinear wave propagation model (TWPM) for reduced dynamic modeling of multi-component distillation columns with variable holdup, and demonstrated its suitability for optimization and control of single-section distillation columns and simple air separation units [Caspari et al., J. Process Control, 2020]. We show here that the TWPM is well-suited for reduced modeling of multi-sectional ultra-high-purity distillation columns and enables real-time capable NMPC of complex process flowsheets with tight operational constraints. To demonstrate its performance and accuracy, we apply the TWPM for NMPC of an ultra-high-purity nitrogen air separation unit. We perform an in-silico closed-loop case study comprising a series of load changes. Our approach reduces CPU time by 84%, enabling NMPC in real time.

Simulation and optimization of Camelina oil fatty acids reaction to produce fatty acid methyl esters in a reactive distillation reactor

Reactive distillation (RD) is a chemical unit operation in which chemical reaction and product separation occurs simultaneously in one unit resulted in reduce the number of downstream steps, energy savings, and greenhouse gases. In the current work, process flow sheets for industrial routes for conversion of camelina oil fatty acids to fatty acid methyl esters (biodiesel) in presence of acid catalyst is modelled in Aspen HYSYS for the purpose to scale up the esters production. The effect of the operating and design parameters is optimized in addition to design the production plant. The simulation results showed that optimum ester yield is obtained for linoleic acid and palmatic components using 6:1 alcohol to oil ratio, reaction temperature 60°C and feeding the oil and the alcohol at stage number 3 and 5 respectively.

Synthesis of Inorganic Cobalt-Containing Spinel-Type Pigments by Self-Propagating Synthesis

Cobalt-containing ultramarine spinel-type pigments are fabricated in the ZnO–MgO–CoO–Al(OH)3–Al system by self-propagating high-temperature synthesis (SHS). the initial components are oxides of cobalt (Co3O4) and zinc (ZnO), aluminum hydroxide (Al(OH)3), and magnesium nitrate hexahydrate (Mg(NO3)2 · 6H2O). An aluminum powder of the ASD-4 brand is used as the reducer metal. The synthesis is performed using samples 40 mm in diameter. The combustion wave propagation velocity is 1–2 mm/s, and the maximal synthesis temperature is 1180°C. Parallel processes of oxidation of aluminum and aluminothermic reactions are leading reactions that provide the synthesis of spinel-based ceramic pigments in the layer-by-layer combustion. These processes result in charge self-heating to the synthesis temperature of spinels, which are also formed with heat liberation. The rapid destruction of Al(OH)3 upon heating leads to the formation of active submicron γ-Al2O3 participating in the subsequent synthesis of finely dispersed spinel structure. Endotherms associated with the decomposition of Al(OH)3 lead to cooling of combusting sample, which complicates the SHS implementation are requires an additional heat supply. Gases liberated during thermal decomposition loosen the charge in the heating zone and decrease the maximal combustion temperature, which makes it possible to perform the synthesis in the solid phase without product fusion and acquire it in the finely dispersed state. Microstructural investigations into the samples by means of scanning electron microscopy confirmed the finely dispersed structure of pigments. IR spectroscopic and X-ray phase analyses revealed a spinel structure. Particle-size-distribution histograms for the initial Al(OH)3 and after its heating, as well as for synthesized spinels, are presented in the work. It is shown that the content of particles 903 nm in diameter is maximal in pigment. Thus, the fabrication of spinel-type pigments in the finely dispersed state by solid-phase synthesis immediately in the combustion wave considerably simplifies the process flowsheet of their production due to the absence of a grinding state.

Economic and Socio-Environmental Benefits of Dry Beneficiation of Magnetite Ores

In our previous studies, we demonstrated the performance of novel superfine crusher and pneumatic planar magnetic separator as energy-efficient technologies for dry processing of magnetite ores. The present study investigates the economic and socio-environmental benefits of applying these technologies in conceptual dry magnetite ore processing flowsheet. The outcome of the study is compared with that of a conceptual wet processing flowsheet for the same ore. The cost estimations used are based on the Brook Hunt C1 methodology whilst revenue estimations are based on the Platts Iron Ore Index specification. The demonstrated economic and socio-environmental benefits show that dry processing flowsheet offers significant energy and cost savings and improved revenue generation compared with the wet process flowsheet. These findings are vital to the magnetite industry, particularly in water- and energy-scarce regions as a benchmark for future studies aimed at deepening and expanding the knowledge base of dry beneficiation of magnetite ores.

Domestic developments of equipment and technologies of steel in-linne degassing in the process of continuous casting

Apart from traditional methods of steel ladle treatment, degassing in the process of continuous casting (in-line degassing) is a perspective one. In the world a line of process flowsheets have been elaborated, but in practice the only one process has been implemented, which was developed by Professor G.A. Sokolov based on theoretical elaborations. The experience of its application in the BOF shop No. 2 of NLMK confirmed the efficiency of degassing in the process of continuous casting and expediency of further work on perfection of the technology and facilities structure for in-line degassing. Accounting the experience gained at AKHK “VNIIMETMASH”, a modified variant of in-line degassing facility was elaborated based on technological specifications of CNIIchermet. It was noted, that thanks to additional bunker-accumulator, fixed at the vacuum chamber, a possibility appeared to change steel ladles without disruption of continuous casting series. It enables to increase the share of degassed steel. At the designing of BOF shop of “Zaporozhstal” steel-works, planned for construction, specialists of AKHK “VNIIMETMASH”, CNIIchermet and YUMZ elaborated a design of two-position facility of increased efficiency for steel in-line degassing. Detailed description of the facility design presented as well as description of its basic units, elaborated at the level in invention. Taking into account that the facility height with the accumulator will make it difficult to place it in the existing shops, a modified in-line degassed elaborated without accumulator, which makes it possible continuous degassing of several heats. Such a degasser can be applied at both continuous casting of steel and casting of large ingots from several heats. The backlog, created by domestic scientists and specialists enables to solve technical problems, arising at elaboration and running of modern facilities of in-line degassing.

Key process mineralogy parameters for rare earth fluorcarbonate-bearing carbonatite deposits: The example of Songwe Hill, Malawi

Rare earth element (REE)-bearing carbonatite deposits commonly contain a wide range of different REE- and REE-bearing minerals associated with various gangue matrices. In order to select the most-suitable mineral processing technique for these deposits, it is essential to identify and quantify the minerals of interest, including their liberation, associations and grain size distribution, along with whole rock compositions. These data are also vital for ore feed optimisation and metallurgical troubleshooting during and after designing a mineral processing flowsheet. This paper summarises the key mineralogical parameters needed before conducting metallurgical beneficiation tests, using the Songwe Hill carbonatite deposit as an example. This REE ore deposit consists of poorly-liberated synchysite-(Ce), which hosts the light rare earth elements including Nd plus some heavy rare earths and well-liberated apatite, which hosts 50% of Gd, 63% of Dy and 71% of Y (heavy rare earth elements) in the deposit. For all REE heavier than Gd, apatite is the most important REE host, however, for the two REE where data are available in both synchysite-(Ce) and apatite (Dy and Y), synchysite-(Ce) still accommodates >25% of the whole-rock HREE content. Both of these ore minerals are associated with ankerite, calcite, and to a lesser extent with iron oxides/carbonates, K-feldspar, strontianite and baryte. According to the quantitative mineralogical data, the possibility of using gravity separation, magnetic separation, froth flotation and leaching to process Songwe Hill carbonatite ore is discussed and a potential beneficiation flowsheet is presented.

Role of oxygen in tubular photobioreactors: Model-Based design and operating conditions to minimize productivity losses

Tubular photobioreactors (PBRs) guarantee high microalgal productivities but suffer from oxygen accumulation. It is known that the tube length must be limited to prevent build-up of high oxygen levels, but the combined effect of other variables (light intensity and biomass concentration) was not fully addressed. In this work, a mathematical model is developed to understand the influence of oxygen on biomass productivity in a continuous tubular PBR. Material balances are applied to investigate the behavior of a single tube reactor and of a complete process flowsheet of a commercial plant. Biomass concentration at the inlet resulted the key variable to minimize oxygen inhibition, confirming the solid retention time (SRT) as the main operating variable. However, an optimized length of the tube can minimize the effect of biomass concentration. Finally, it was observed that measuring the O2 concentration alone is not a reliable index of the overall productivity in a PBR.

Comparison of activity coefficient models for the estimation of uranyl nitrate and nitric acid distribution coefficients in phosphoric solvent

The modelling of solvent extraction system is important for the process flow sheet design and optimization. The estimation of aqueous phase activity coefficients constitutes the major part of the thermodynamic modelling of solvent extraction system. Hence the selection of suitable activity coefficient models for the accurate description of aqueous electrolyte system encountered in the nuclear fuel reprocessing system is an important task which decides the accuracy and complexity of the modelling. In this work the accuracy of extended UNIQUAC (eUNIQUAC) activity coefficient model for the estimation of uranyl nitrate and nitric acid distribution coefficient in 1.1 M Tri Butyl Phosphate (TBP) and 1.1 M Tri iso Amyl Phosphate (TiAP) have been compared with the eNRTL, Pitzer and SIT activity coefficient models. eUNIQUAC model gave lowest RMSD (%) for the estimation of uranyl nitrate and nitric acid extraction in TiAP and TBP respectively.

A Novel Pneumatic Planar Magnetic Separator for Magnetite Beneficiation: A Focus on Flowsheet Configuration

In our previous studies, we investigated the performance of a novel pneumatic planar magnetic separator (PMS) for the dry beneficiation of a selected magnetite ore. In the present study, we have extended the studies on the PMS with the focus on investigating how various PMS processing flowsheet configurations influence its performance. The outcomes were subsequently compared with those of a Davis tube recovery (DTR) tester. The study demonstrated that the use of PMS in the dry beneficiation of magnetite ores is feasible, and operating the PMS in different flowsheet configurations positively influences the magnetite concentrate grade and purity. Finally, the study showed that the PMS performance compares well with that of DTR and can potentially replace DTR in operations that are carried out in arid regions.

Thermo-economic analysis of reverse water-gas shift process with different temperatures for green methanol production as a hydrogen carrier

The development of renewable energy makes it possible to produce abundant hydrogen as the energy carrier. For reducing the hydrogen storage and transportation cost, methanol synthesis via reverse water gas shift (RWGS) reaction can provide significant environmental benefits through a carbon capture and utilization pathway. There have been researches in the past to determine the most effective catalysts and related technologies in process development. However, a remaining question has been whether it should be run at a temperature above 900 °C where problematic by-products and coke might be an issue, or below 500 °C where it is not kinetically favored, but heavy catalyst use could compensate.This paper investigated the tradeoff between running the RWGS process at the higher or the lower temperature range as part of a methanol (MeOH) production plant. The plant had a basis of 80 kmol/hour of methanol product. A process flowsheet for each route was developed and optimized using ASPEN Plus as well as heat integration methods. The carbon footprint was then calculated to assess the environmental performances of both processes. Finally, an economic analysis was conducted to assess the overall feasibility for implementing either process.It was found that while running the process at a lower temperature of 450 °C requires a lower energy consumption, however it comes with a higher cost due to the heavy reliance on the catalytic reaction. The higher temperature reaction running at 940 °C performed similarly to the lower temperature reaction but with a better environmental performance and lower cost of production. Moreover, using a higher production capacity for the plant proved a higher promise of eliminating economic issues due to economies of scale.

Energy recovery modeling of pressure-retarded osmosis systems with membrane modules compatible with high salinity draw streams

A general framework for pressure-retarded osmosis (PRO) process simulation and optimization has been developed to generate performance frontiers (i.e. Pareto curves with respect to specific energy recovery vs. membrane power density) for a given process flowsheet – providing a basis for unequivocal comparisons to be made between the operability of various candidate membrane modules. This work confines itself to pairings between high-salinity oil-produced water (draw) and seawater (feed), which possess a high potential for osmotic energy recovery. It has been shown that the poor mass transfer behavior of a potential PRO membrane may significantly offset gains that could be realized from a high burst pressure compatible with the treatment of high-salinity draw streams. By applying suitable cost parameters to process optimization results and estimating resultant payback periods, it has been shown that the conventional PRO success criterion, which is based on a power density threshold of 5 W/m2, is not sufficient to guarantee the feasibility of the membrane material in plant-scale operation – in the absence of additional optimization of the PRO process flowsheet.

A comprehensive framework for synthesis and design of heat-integrated batch plants: Consideration of intermittently-available streams

Significant opportunities for energy savings in batch plants exist through Heat Integration of intermittently-available material transfer streams between processing and storage units. Such opportunities may, however, be limited by the structure of the process flowsheet and the scheduling in place. This work presents results obtained when the design, scheduling and Heat Integration of multipurpose batch plants are carried out simultaneously. A rigorous stream-task-oriented scheduling formulation is presented, which enables explicit description of the movements of the intermittently-available streams. This thorough treatment of streams opens up more degrees of freedom than realised in previous stream Heat Integration formulations. On such a basis, design and Heat Integration constraints are added, to result in a mixed integer nonlinear programming formulation. The optimisation objective is to maximise annual net profit, which is a trade-off between production throughput, capital costs, and operational costs arising from hot and cold utility consumption. When applied to a literature example, results show higher annual net profit and reduction in utility costs by as much as 15%, compared to when each of the design, scheduling and Heat Integration steps are carried out in sequence.

Assessment of Gravity Dressability of Gold Ore - GRG Test

Gravity methods are widely used for processing of gold ores. But many aspects of these processing techniques require improvement. In the study, methods of fire assay, gravimetric, chemical, mineralogical analyses of gold ores were used. In terms of sulfide sulfur content and degree of sulfur oxidation, the gold ore is assigned to the low-sulfide type of ore in the primary zone. Mineralogical analysis showed the ore-bearing rock is represented by phyllite. Gold in the ore occurs mainly in the form of free large and fine particles. The fine gold is closely associated with pyrite. GRG test was carried out for assessing gravity dressability of the gold ore. The total gold recovery is more than 41 %. The highest gold recoveries were achieved at the first stage at 100 % of -1.6 mm ore grain size, and at the third stage at 80 % of -0.071 mm ore grain size. This indicates that both relatively large gold and fine free gold particles are present in the ore. This is also confirmed by mineralogical analysis. The GRG test results showed that the gold ore can be effectively concentrated using centrifugal concentrators. The level of gold recovery by gravity at the multi-stage ore grinding is quite high. When developing the ore concentration process flow sheet, gravity separation in centrifugal concentrators should be included.

Issues of Improving Control and Increasing Efficiency of Production Blocks at an ISL Uranium Mine

The tasks of continuous optimizing production, looking for ways of increasing performance, cutting mining costs and expanding mineral resource base of a mining enterprise are becoming more relevant than ever in conditions of the current negative trends at the world market of uranium resources. Increasing enterprise competitiveness requires permanent improvement of approaches and methods for managing performance of production blocks of a mine and ensuring the necessary volumes of reserves prepared for production. In the study, a theoretical information analysis of the process flow sheet of commercial ISL uranium production was carried out. The regression relationships between the main indicators of the production process cycles were determined, and the task of controlling production blocks at the stages of acidification, active leaching, completing operation, and decommissioning was formalized. The statistical characteristics of a production block cells and the distribution of uranium reserves, obtained based on the data of ore body drilling-in, as well as the analysis of the dynamic pattern of uranium production and recovery by production block depending on time, the balance of production block productivity by pregnant and leaching solutions enabled calculating key geotechnological indicators that formed the basis for calculating regression relationships between the uranium recovery and the ratio of the leaching solution amount to the rock mass amount, as well as for estimating specific consumption of sulfuric acid and electricity depending on operation time. This approach allowed identifying the problem areas and promising ways for improving the control procedure and performance of ISL mine wellfield operation. The planned measures will allow re-estimating resource potential of a production block while simultaneously providing a reasonable forecast of the residual uranium reserves in the being exploited and drilled-in blocks, reducing costs at the main development stage, and, by providing timely decommissioning of the blocks, reducing power consumption, optimizing sulfuric acid consumption, and overall improving quality of projecting and planning the production indicators for achieving uranium production targets. The study results can be used for improving short- and medium-term planning of technical and economic indicators of main development and production based on the forecast of ore interval sizes in production blocks that contributes to strengthening resource base and increasing capitalization of a company.

Integrated Methodology for the Optimal Synthesis of Lignocellulosic Biomass-to-Liquid Fuel Production Processes: 1. Simulation-Based Superstructure Synthesis and Development

Thermochemical process routes are promising technological routes to convert lignocellulosic biomass into biofuels with similar properties as fossil fuels. In a previous work (Ind. Eng. Chem. Res. 2018 57, 9925–9942), we have studied five base case processes for biofuel production with fixed process structures. This work presents an integrated methodology to consider new process structures for the optimal synthesis of lignocellulosic biomass-to-liquid (BtL) fuel production processes. Given that the five base cases showed not only a significant difference of production costs among the process sections but also distinct biofuel product profiles in terms of gasoline and diesel productivity, the current methodology is developed in two parts: part 1 presents the superstructure synthesis through the step-by-step definition of unit operations’ possible interconnections to include all possible new process alternatives than base cases. The superstructure is developed based on the data collected from unit operations’ rigorous simulation of the base cases. Part 2 presents the superstructure algorithm setup and optimization for the optimal synthesis of BtL process flowsheets with specified product profiles of gasoline and diesel productivity. Rigorous simulation results for process units and process sections are used in the superstructure formulation and its algorithm development. Three case studies have shown that the integrated methodology can generate new production processes with specified product profiles while having lower total manufacturing costs than base cases.