KONTROLIRANJE PARAMETARA PROCESA MLJEVENJA KORIŠTENJEM CENTRALNO KOMPOZITNOGA PLANA ZA SMANJENJE MULJA U OPLEMENJIVANJU FOSFATNE RUDE

Ultrafine particles resulting from the grinding operations of phosphate ore cause problems of air pollution, and of the beneficiation plants particularly, flotation cells and filtration units. Particles of less than 38 μm are one of the undesirable consequences of the phosphate ore beneficiation stage, where fine or ultrafine powder accounts for 10–30 percent of phosphate quantities and is regarded as a loss. Furthermore, maintaining additional amounts of phosphate by reducing these particles will provide several benefits, including minimizing the environmental implications of slime disposal and enhancing the economic impact of the phosphate ore beneficiation process. This paper aims to maximize the useful phosphate particles and reduce the slime instead of doing even more work with traditional techniques. This goal might be attained by increasing the percent of particles of the desired size of the phosphate (Target) during the grinding process by determining the optimal operational conditions, that will reduce the amount of slime. The central composite design (CCD) is used to identify the number of experiments to be evaluated and to create a predictive model to be used for determining the optimal operation parameters. As a result of the optimization process, a maximum Target of 87.6% was obtained at grinding conditions t (5.1 min), v (42.6%), s (81.2%), and c (50.7%). Where t, v, s, and c stand for grinding time, occupied volume of ball, rotational speed percent from critical speed (%) and solid concentration by volume (%) respectively.Vrlo sitne čestice koje nastaju u procesu mljevenja fosfatne rude uzrokuju probleme onečišćenja zraka, a posebno probleme u samome radu oplemenjivačkih postrojenja, flotacijskih ćelija i filtracijskih jedinica. Čestice manje od 38 μm jedna su od nepoželjnih posljedica faze oplemenjivanja fosfatne rude, gdje sitni ili vrlo sitni prah čini 10 – 30 posto količina usitnjene fosfatne rude i smatra se gubitkom. Nadalje, održavanje dodatnih količina korisnoga fosfatnog proizvoda smanjenjem tih čestica pružit će nekoliko prednosti, uključujući minimiziranje utjecaja odlaganja mulja na okoliš i povećanje ekonomskoga učinka procesa oplemenjivanja fosfatne rude. Cilj je ovoga istraživanja povećati udio korisnih čestica fosfata i smanjiti udio mulja, umjesto ulaganja dodatnoga napora u postojećim postupcima. Taj se cilj može postići povećanjem udjela fosfatnih čestica željene veličine (u izlazu) tijekom procesa mljevenja, određivanjem optimalnih radnih uvjeta koji će smanjiti količinu jalovinskoga mulja. Centralno kompozitni plan (Central Composite Design – CCD) koristi se za utvrđivanje broja pokusa koji se trebaju evaluirati te za izradu modela predviđanja koji će se koristiti za određivanje optimalnih vrijednosti radnih parametara. Kao rezultat procesa optimizacije maksimalni udio čestica željene veličine u izlazu od 87,6 % dobiven je pri uvjetima mljevenja: t = 5,1 min, v = 42,6 %, s = 81,2 % i c = 50,7 %, gdje t, v, s i c predstavljaju vrijeme mljevenja, volumen koji kugle zauzimaju u mlinu, postotak brzine rotacije u kritičnoj brzini (%) i volumnu koncentraciju krutih čestica (%)

Environmental risk assessment and chemical contamination with heavy metals in the sediments of three drains, south of Manzala lake (Egypt)

ABSTRACT. Six heavy metals (Fe, Cd, Co, Cr, Ni, and Pb) were measured in all 15 sediment samples collected from three drains south of Manzala Lake (Egypt). The possible environmental risks of heavy metals in the sediment of the three drains were investigated using soil indices and risk assessment. Results showed that heavy metal contamination was found at the studied sites along the three drains, and pollution levels varied depending on metals and sites. The mean concentration (mgkg-1) ranked in the order of Fe (3950) ˃ Cd (22.36) ˃ Cr (21.15) ˃ Co (19.01) ˃ Pb (14.16) ˃ Ni (10.40) for Faraskour drain, Fe (5068) ˃ Cd (30.29) ˃ Co (18.97) ˃ Cr (16.90) ˃ Ni (15.03) ˃ Pb (12.16) for Al-Etaiwy drain and Fe (56.12) ˃ Cd (19.60) ˃ Co (17.15) ˃ Ni (14.88) ˃ Cr (10.10) ˃ Pb (10.03) for Ramsis drain. The mean ranges of enrichment factor for Cd, Co, Pb, Ni and Cr were 167.5-3858, 6.11-51.78, 4.38-31.20, 1.07-11.84 and 0.61-7.43, respectively. The average degree of contamination revealed that the majority of the sites had reached very high levels of pollution, with the exception of site 1, which had reached a moderate level of contamination. The ecological risk of heavy metals can be ranked as follows: Cd > Co > Pb > Ni > Cr, and the potential ecological risk index (PERI) were 931.0, 1173 and 818.5 in the Faraskour, Al-Etaiwy and Ramsis drains, respectively. To decrease pollution in these drains, it was determined that more effective restrictions on Cd and Co were needed. In general, the mean levels of Cr, Ni, and Pb in sediments from the three drains are within the European Union (EU) and Canadian Soil Quality Guidelines (CSQGD), Cd higher than EU and CSQGD, and Co higher than EU but lower than CSQGD.   KEY WORDS: Heavy metals, Pollution indices, Environmental risk assessment, Drains, Nile Delta   Bull. Chem. Soc. Ethiop. 2022, 36(2), 315-327.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i2.6                                                       &nbsp

Leukaemia cutis from CD56 positive, Myeloperoxidase negative acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a clonal expansion of myeloid blasts in peripheral blood, bone marrow or other tissues. Cutaneous manifestations of leukemia are either specific or non-pecific. Specific lesions result from direct infiltration of skin by leukemic cells.  We present a case of myeloid leukemia cutis manifested by erythematous asymptomatic nodules and plaques distributed on the chest, abdomen and back. The clinical impression and the histopathological features of the cutaneous infiltrate were suggestive of haematolymphoid malignancy, more towards lymphoma.  However, the immunohistochemical features were against the diagnosis of lymphoma and were highly suspicious for myeloid leukaemia, which were concomitantly confirmed by bone marrow biopsy and blood picture.  Any poorly differentiated malignant skin infiltrate of confirmed haematopoeitic lineage, myeloid differentiation should be considered and excluded by appropriate panel.  CD56+ AML is a rare type of AML that has special features like the great liability for extramedullary involvement including skin, monocytic characteristic of leukaemia cells and absence of myeloperoxidase expression. </p

N-acetylcysteine protects against cuprizone-induced demyelination: histological and immunohistochemical study

Myelination is a sequential process that is tightly controlled by a number of intrinsic and extrinsic factors. Any CNS disease in which the neuronal myelin sheath is damaged is referred to as demyelinating disease. The present work was designed to study the histopathological, ultrastructural and immunohistochemical changes in rat brain, mainly corpus callosum (CC), following oral administration of cuprizone (CPZ), and the role of N-acetylcysteine (NAC) in reducing these changes. Demyelination was induced by CPZ administration for short (4Ws) and long (8Ws) periods.  NAC was given concomitantly and sequentially for similar periods. Spontaneous recovery after cessation of CPZ followed by no medication was also investigated. At the end of each experimental period, both cerebral hemispheres were extracted and prepared for light and electron microscopic examination and immuno-histochemical study.  The obtained results showed a direct proportion between the duration of CPZ administration and the severity of demyelination. The co-administration of CPZ and NAC, had a fair protective impact that was stronger than the sequential administration of the two drugs. Incomplete spontaneous remyelination was observed after cessation of CPZ, being more evident in short than in long period group, indicating that when CPZ administration is prolonged, remyelination is delayed. In the light of the above results, it could be concluded that NAC has neuroprotective effects and has the potential to be a novel therapeutic approach for the treatment of demyelinating diseases such as multiple sclerosis; however, treatment should begin as soon as the disease manifests

Low-cost hardware in the loop for intelligent neural predictive control of hybrid electric vehicle

The design and investigation of an intelligent controller for hardware-in-the-loop (HIL) implementation of hybrid electric vehicles (HEVs) are proposed in this article. The proposed intelligent controller is adopted based on the enhancement of a model predictive controller (MPC) by an artificial neural network (ANN) approach. The MPC-based ANN (NNMPC) is proposed to control the speed of HEVs for a simulation system model and experimental HIL test systems. The HIL is established to assess the performance of the NNMPC to control the velocity of HEVs in an experimental environment. The real-time environment of HIL is implemented through a low-cost approach such as the integration of an Arduino Mega 2560 and a host Lenovo PC with a Core i7 @ 3.4 GHz processor. The NNMPC is compared with a proportional–integral (PI) controller, a classical MPC, and two different settings of the ANN methodology to verify the efficiency of the proposed intelligent NNMPC. The obtained results show a distinct behavior of the proposed NNMPC to control the speed of HEVs with good performance based on the distinct transient response, minimum error steady state, and system robustness against parameter perturbation

Low-cost hardware in the loop for intelligent neural predictive control of hybrid electric vehicle

The design and investigation of an intelligent controller for hardware-in-the-loop (HIL) implementation of hybrid electric vehicles (HEVs) are proposed in this article. The proposed intelligent controller is adopted based on the enhancement of a model predictive controller (MPC) by an artificial neural network (ANN) approach. The MPC-based ANN (NNMPC) is proposed to control the speed of HEVs for a simulation system model and experimental HIL test systems. The HIL is established to assess the performance of the NNMPC to control the velocity of HEVs in an experimental environment. The real-time environment of HIL is implemented through a low-cost approach such as the integration of an Arduino Mega 2560 and a host Lenovo PC with a Core i7 @ 3.4 GHz processor. The NNMPC is compared with a proportional–integral (PI) controller, a classical MPC, and two different settings of the ANN methodology to verify the efficiency of the proposed intelligent NNMPC. The obtained results show a distinct behavior of the proposed NNMPC to control the speed of HEVs with good performance based on the distinct transient response, minimum error steady state, and system robustness against parameter perturbation

Assessment of Soil Salinity Problems in Agricultural Areas Through Spatial and Temporal Remote Sensing

This study is aimed at addressing the capability of using remote sensing data in detecting and tracking soil salinization variability using a series of experimental methodologies. In a controlled experiment, the spectral reflectance changes associated with salt crust formation on soil surfaces were tracked in order to detect the optimum moisture levels for salinity detection and recognize the influence of soil texture on salinity-induced spectral changes. In another experiment, lettuce plants were utilized to assess plant biophysical responses to moderate salinity levels with canopy-level reflectance data. An FR-ASD spectrometer was used to collect reflectance data in the 400-2500 nm spectral region. Finally, MODIS satellite data were employed to analyze the temporal profiles of selected high (8-11 dS/m), moderate (4-6 dS/m) and none (1-3 dS/m), salt affected sites in the Nile Delta, Egypt. The analyses of spectral data revealed that the use of remote sensing data to discriminate salinity levels in soils is highly affected by moisture content and texture. At low moisture contents, salts have high reflectance in the VIS-NIR spectral region but low reflectance in SWIR region. Spectral ambiguity with soil salinity was found across soil texture types.Significant relationships were found between plant chlorophyll content and the REP index (R2 =0.97), and dry biomass with SAVI values (R2 =0.94) under different salinity treatments. The spectral vegetation indices (VI's), SAVI and REP, and water indices (WI's) were found to be effective in discriminating between plants growing under moderate conditions of soil salinity and a non-saline condition. The combination between VI's and WI's was found to be useful in improving the ability to assess salinity stressed plants from non-stressed plants. Finally, MODIS results showed separability between canopy seasonal growth under high saline (HS) and non-saline (NS) conditions based on phenology. Canopies growing under HS conditions had lower VI and WI values in the green-up period. It may be concluded that using plant biophysical response to detect soil salinity could be useful in detecting early stages of salinity. Also using the combination between VI's and WI's using MODIS data is a useful to discern between high saline and none saline areas

Influence of long-term wastewater irrigation on soil quality and its spatial distribution

The main objective of this investigation was to evaluate soil quality and map spatial distribution of heavy metals under long-term irrigation with sewage wastewater. Physical and chemical indicators were designated to assess the soil quality in Elgabal Elasfar farm, Egypt. Thirty-three surface soil samples were collected from the study area (classified as Torriorthents and Quartzipsamments). Heavy metal concentrations in the irrigation wastewater were high compared with Nile fresh water. Copper concentrations were higher than the safe limits for irrigation. applying sewage wastewater in irrigation for long periods adversely affected soil EC, available heavy metals, and clay content while enhanced total N, available P and K, CEC, and TOM. The overall soil quality index (SQI) did not fluctuate much between the studied soils. The “moderate” SQ class were dominant, with the area of 94% of the total study area. But, excluding the available heavy metal concentrations from the SOI function, “high” SQ class in this case occupied 69% of the study area. The huge volumes of sewage wastewater that was applied for long-term increased the salinity and available heavy metals which, adversely affect the soil quality in this area. To preserve or improve soil quality in the study area management plans are needed to avoid the undesirable destructive effects of increasing both salinity and available heavy metals. Keywords: Soil quality assessment, Heavy metals, Wastewater irrigation, Long-term irrigation, Sewage wastewate

Multi-Objective Optimization of Drilling GFRP Composites Using ANN Enhanced by Particle Swarm Algorithm

This paper aims to optimize the quality characteristics of the drilling process in glass fiber-reinforced polymer (GFRP) composites. It focuses on optimizing the drilling parameters with drill point angles concerning delamination damage and energy consumption, simultaneously. The effects of drilling process parameters on machinability were analyzed by evaluating the machinability characteristics. The cutting power was modeled through drilling parameters (speed and feed), drill point angle, and laminate thickness. The response surface analysis and artificial neural networks enhanced by the particle swarm optimization algorithm were applied for modeling and evaluating the effect of process parameters on the machinability of the drilling process. The most influential parameters on machinability properties and delamination were determined by analysis of variance (ANOVA). A multi-response optimization was performed to optimize drilling process parameters for sustainable drilling quality characteristics. The obtained models were applied to predict drilling process characteristics, and exhibited an excellent harmony with the experiment results. The optimal drilling process factors were the highest spindle speed and the lowest feed, with a drill point angle of 118° for the laminate of 4.75 mm thickness