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The mixing process greatly influences the mixing efficiency, as well as the quality and the price of the intermediate and/or the final product. Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. This type of premixing action is not investigated in detail in the open literature. In this article, the novel numerical approach called Discrete Element Method is used for modelling of granular flow in multiple static mixer applications (1-3 Komax or Ross mixing elements were utilized), while the Computational Fluid Dynamic Method was chosen for fluid flow modelling, using the Eulerian multiphase model. The main aim of this article is to predict the behavior of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by RSD (relative standard deviation) criterion, and the effects on the mixer type and the number of mixing elements on mixing process were studied. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA). Mathematical modelling is used for optimization of number of Ross and Komax segments in mixer in order to gain desirable mixing results.

The bread wheat bran is used as a raw material rich in dietary fiber in the production. Therefore, it is necessary to monitor the content of essential and toxic elements in the flour and bran. This paper investigates essential (Zn, Cu, Fe and Mn) and toxic (Pb, Cd, Hg and As) elements in products of milling wheat grown in the whole territory of Banat, the region in Serbia. Inductively coupled plasma mass spectrometry was used for analysis. The mean contents of the following elements Pb, Cd, Hg, As, Fe, Mn and Zn in wheat kernels were 0.143, 0.007, 0.017, 35.7643, 50.865 and 21.174 mg/kg, respectively. Cluster analysis (CA) and principal component analysis (PCA) was applied to discriminate and to group the different samples, according to element content. Quality results show that the first two principal components, accounting for 80.17% of the total variance, can be considered sufficient for data representation and the first two principal components of toxic elements and essential microelements. Cd (15.28%), Zn (17.91%), Cu (17.08), Fe (16.91%) and Mn (17.54%), have been found the most influential for the first factor coordinate calculation, while the contribution of Pb (27.93%) and Hg (61.86%) has been the most important variable for the second factor coordinate calculation.

Pužni transporteri se veoma intenzivno koriste u industriji za proizvodnju i preradu hrane, plastike, mineralnih sirovina, u poljoprivrednoj proizvodnji kao i u prerađivačkoj industriji za podizanje i/ili transport rasutih materijala na kratkim i srednjim rastojanjima. Uprkos njihovoj očiglednoj konstrukcionoj jednostavnosti, sam čin transporta je veoma složen za razumevanje i konstruktori se često oslanjaju na iskustvene podatke pri konstruisanju i izradi. Osobine pužnih transportera su određene radnim uslovima (kao što su: brzinu rotacije vratila puža, ugao pod kojim je nagnut pužni transporter, nivo zapreminskog punjenja puža, itd.). U ovom radu je opisano nekoliko horizontalnih puževa, konstantne dužine koraka, pri čemu su geometrije pužnih spirala neznatno izmenjene radi ispitivanja procesa mešanja tokom transporta, korišćenjem metode diskretnih elemenata (Discrete Element Method - DEM). Ispitivani su uticaji geometrijskih izmena na osobine pužnog transportera, različita konstrukciona rešenja pužne spirale su međusobno poređena, kao i efekti geometrijskih izmena na mešanje u toku transporta. Tokom transporta u pužnom transporteru, čestice padaju sa vrha pužne spirale na prvu sledeću slobodnu površinu pužne spirale i taj segment putanje čestice može da bude iskorišćen za dopunsko mešanje materijala tokom transporta. Putanja čestice se drastično povećava ugradnjom tri dodatne zavojne površine usmerene u istom pravcu kao i pužna spirala (1458,2 mm u poređenju sa 397,6 mm u slučaju pužnog transportera sa jednom spiralom). Skraćivanjem dodatnih zavojnica, koje su usmerene u istom smeru kao i pužna spirala, unekoliko se smanjuje putanja čestice, na dužinu od 1728,8 mm (usled prekidanja zavojnice na sredini pužnog transportera). Putanja čestice se produžava na 1764.4 mm, kada se ugrade dodatne zavojne površine koje su usmerene u suprotnom pravcu od pravca pužne spirale. Ugradnjom tri dodatna pravolinijske letve, dobijena je najduža putanja čestice: 2061,6 mm., Screw conveyors are used extensively in food, plastics, mineral processing, agriculture and processing industries for elevating and/or transporting bulk materials over short to medium distances. Despite their apparent simplicity in design, the transportation action is very complex for design and constructors have tended to rely heavily on empirical performance data. Screw conveyor performance is affected by its operating conditions (such as: the rotational speed of the screw, the inclination of the screw conveyor and its volumetric fill level). In this paper, horizontal, several single-pitch screw conveyors with some geometry variations in screw blade were investigated for mixing action during transport, using Discrete Element Method (DEM). The influence of geometry modifications on the performance of screw conveyor was examined, different screw designs were compared, and the effects of geometrical variations on mixing performances during transport were explored. During the transport, the particle tumbles down from the top of the helix to the next free surface and that segment of the path was used for auxiliary mixing action. The particle path is dramatically increased with the addition of three complementary helices oriented in the same direction as screw blades (1458.2 mm compared to 397.6 mm in case of single flight screw conveyor). Transport route enlarges to 1764.4 mm, when installing helices oriented in the opposite direction from screw blades. By addition of straight line blade to single flight screw conveyor, the longest particle path is being reached: 2061.6 mm.