Observable dynamic models of reagent effects for model based froth flotation control

This article demonstrates the feasibility of including simple reagent addition models in an existing observable dynamic model of a froth flotation circuit. The existing model has full state observability and parameter identifiability using measurements that are commonly available on flotation circuits. This article qualitatively evaluates the possible impact of varying frother dosage on the model parameters. A Sobol sensitivity analysis indicates that the air recovery model parameters are most influential in the determination of grade and recovery. The model is expanded with two different reagent effect models. Both expansions include mass balance models of the frother concentration in each cell. The first model expands an empirical parameter in the air recovery model, related to the froth height at which peak air recovery (PAR) is achieved, as a linear function of frother concentration. The second model adds a linear frother concentration term to the existing air recovery model to modify the steady-state air recovery directly. Observability analyses of the expanded models show that all states and the important time-varying model parameters are observable (and identifiable) from the available on-line measurements. Most importantly, the frother concentrations are shown to be observable without concentration measurements. Simulations of the model expansions show that the second model can qualitatively predict the impact of increased frother dosage on air recovery, grade, and recovery, while the first model can only predict the correct effect under certain conditions.https://www.journals.elsevier.com/ifac-papersonlineElectrical, Electronic and Computer Engineerin

Dextrin nanocomposites as matrices for solid dosage forms

Safe application of water-insoluble acaricides requires fast release from solid dosage systems into aquatic environments. Dextrin is a water-soluble form of partially hydrolyzed starch, which may be used as matrix material for these systems if retrogradation can be inhibited by the inclusion of nanofillers. Several glycerol-plasticized thermoplastic dextrin-based nanocomposites were prepared with a twin-screw extrusion-compounding process. The nanofillers included a layered double hydroxide (LDH), cellulose nanofibers (CNF), and stearic acid. The time-dependent retrogradation of the compounds was monitored by X-ray diffraction (XRD) and dynamic mechanical thermal analysis (DMA). XRD showed that composite samples that included stearic acid in the formulation led to the formation of an amylose-lipid complex and a stable crystallinity during aging. The most promising nanocomposite included both stearic acid and CNF. It was selected as the carrier material for the water-insoluble acaricide Amitraz. Fast release rates were observed for composites containing 5, 10, and 20% (w/w) of the pesticide. A significant reduction in the particle size of the released Amitraz powder was observed, which is ascribed to the high-temperature compounding procedure.PAMSA and the Department of Science and Innovationhttps://pubs.acs.org/journal/aamickhj2021Chemical EngineeringConsumer ScienceFood Scienc