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The subject of this paper was the study of antimicrobial capacity of silver loaded on the low temperature activated alumina products and evaluation of these products as decontaminants in the water and waste waters decontamination treatments. The low temperature activated alumina products have been characterized as valuable adsorbents in previous papers. So, by reason the next step to investigate these silver loaded products and finding their performaces as antimicrobial agents was an alluring prospect. For this purpose, a common bacterian inoculus was choosen for experiments, and a penmisive method to measure the rate of inhibition was adopted. Experimental data have shown the dependence of the inhibition rate on the following parameters concerning the adsorbent properties: the thermal treatments, particle size dimension of adsorbent (low temperature activated alumina products), concentration of siver adsorbed on particle surface and density of bioreactive centers, representing the number of particles on unit volume of the liquid containing the bacterial cells. Also, the experiments lay out that the aluminum hydroxide calcined at 300 and 400ºC exibits the largest silver adsorbed concentration and the highest inhibition rate (close to 100 %). Little dependence of inhibition rate on pH, in the interval 5.0 � 8.0, was observed. For application of depolluting agent in diferent technological processes, it is necesary to measure the minimum inhibitory concentration in therms of g of silver loaded on the low temperature activated alumina /L.

Aluminum hydroxide is a key product for the industrial production of alumiana and aluminium, ceramics insulator and refractories, desiccants, absorbents, flame retardants, filers for plastics and rubbers, catalysts, and various construction materials. The production of these arrays of useful material products is grounded on the multiple thermal decomposition pathways of Al(OH)3, which involve major crystallographic dislocations and many microstructure reconfigurations on variable lines of phase transitions, from the raw material up to large varieties of precursors and commercial grade products. A wide range of literature on this subject is available, and recent reviews cover suitable information about preparation and characterization of different activated alumina products with specific properties and applications. In our previous papers, there was studied the mechanisms of aluminum hydroxide phase transitions, during low temperature calcination, namely, at 260ºC, 300ºC, 400ºC and 600 ºC, under chosen particularly conditions, for promoting the nucleation of the amorphous phases. Collected data suggest that raw aluminum hydroxide; dried, milled and classified is a precursor for the new low temperature activated alumina transition phases, carrying distinctive characteristics and properties, due to products enrichment in amorphous phases. Accordingly, as effects of the main driving factors (temperature and rate of heating, and initial particle size dimension) on the aluminum hydroxide as new precursor, notable changes were observed in products mineral composition, morphology and specific surface area, pore size, pore distribution, and the particle size distribution. Beside, some other secondary effects have to be apprehended. For example, the main phase transition process dinamic factors control over some physical and technical properties of the new products, like: absolute density, brightness, oil absorption capacity and water absorption capacity. The purpose of this work was to continue the characterization of low temperature activation alumina products, and also, to measure the adsorption capacity and to reveal adsorption kinetics mechanisms. Thus, the first step of survey was silver adsorption maximum capacity measurements for all sample prepared by heating the precursor alumina hydroxide, milled and classified as 5 different dimension size fractions to 260, 300, 400 and 600ºC. Hereinafter, four samples, carefully selected as representative for the entire lot of samples, were used for the study of kinetics mechanism and data fitting to the adequate kinetic equations. Confident data validate the pseudo second order kinetic model for the entire activation process, independently of samples heating temperature and particles dimension.

In this paper, the thermal decomposition of crystalline Al(OH)3 was studied over the temperature range of 260–400 °C for particles with a size between 10 and 150 µm. The weight losses and thermal effects occurring in each of the dehydration process were assessed using thermogravimetry (TG) and differential scanning calorimetry (DSC) thermal analysis. X-ray diffraction (XRD) patterns, refined by the Rietveld method, were used for mineral phase identification, phase composition analysis, and crystallinity degree determination. Moreover, the particle size distributions and their corresponding D10, D50, and D90 numeric values were determined with a laser analyzer. We observed a strong relationship between the calcination temperature, the initial gibbsite grade particle size, and the crystallinity of the resulting powders. Hence, for all endothermic effects identified by DSC, the associated temperature values significantly decreased insofar as the particle dimensions decreased. When the gibbsite was calcined at a low temperature, we identified small amounts of boehmite phase along with amorphous new phases and unconverted gibbsite, while the powders calcined at 400 °C gradually yielded a mixture of boehmite and crystalized γ-Al2O3. The crystallinity % of all phase transition products declined with the increase in particle size or temperature for all the samples.

In this paper, we studied the scandium adsorption from aqueous solutions on the surface of low-temperature-activated alumina products (GDAH). The GDAH samples are industrially manufactured, coming from the Bayer production cycle of the Sierra Leone bauxite as aluminium hydroxide, and further, by drying, milling, classifying and thermally treating up to dehydroxilated alumina products at low temperature. All experiments related to hydroxide aluminium activation were conducted at temperature values of 260, 300 and 400 °C on samples having the following particle sizes

The purity, structural surface, particle dimensions, particle size distribution, and the associated reactivity of chemical and surface properties are the most important and most required properties of alumina hydrate special brands. The purpose of this paper concerns the common metallic impurities accumulation on the surface of alumina hydrate particles, during the sodium aluminates decomposition in liquid phase, during the entire aluminum hydroxide crystallization stage in the Bayer technology.

Aluminum hydroxide is an essential material for the industrial production of ceramics (especially insulators and refractories), desiccants, absorbents, flame retardants, filers for plastics and rubbers, catalysts, and various construction materials. The calcination process of Al(OH)3 first induces dehydration and, finally, results in α-Al2O3 formation. Nevertheless, this process contains various intermediary steps and has been proven to be complicated due to the development of numerous transitional alumina. Each step of the investigation is vital for the entire process because the final properties of materials based on aluminum trihydroxide are determined by their phase composition, morphology, porosity, etc. In this paper, five dried, milled, and size-classified aluminum hydroxide specimens were thermally treated at 260, 300, and 400 °C, then, they were studied in order to identify the effects of temperature on their properties, such as particle morphology, specific surface area, pore size, and pore distribution. The major oxide compounds identified in all samples were characteristic of bauxite—namely, Al2O3 * 3H2O, SiO2, Fe2O3, Na2O, and CaO. Particles with smaller sizes (&lt, 10 µm = 76.28%) presented the highest humidity content (~5 wt.%), while all samples registered a mass loss of ~25 wt.% on ignition at 400 °C. The identified particles had the shapes of hexagonal or quasi-hexagonal platelets and resulted in large spherulitic concretions. The obtained results suggest that ceramic powders calcined at 400 °C should be used for applications as adsorbents or catalysts due to their high specific area of about 200–240 m2/g and their small pore width (3–3.5 nm).

Electricity cost is one of the main determinants of the competitive structure of an aluminium smelter. Over the past few years, ALRO Group, the biggest industrial power consumer in Romania, has completed ambitious projects to reduce specific energy consumption. To reach the next level, in 2018, ALRO mandated Rio Tinto Aluminium Pechiney (RTAP) to supply AP12 Low Energy technology. To guarantee smooth technology transfer and achieve step-change performance the AP Technology™ standard “cell development cycle” approach was used. ALRO and RTAP worked together as a team to execute specific activities such as a measurement campaign, modelling, risk analysis, readiness assessment, on-site and remote support, data analytics, Go/No Go. This article presents this project, which achieved a significant reduction in specific energy consumption, along with some of the supporting activities and tools.

This work presents the BRAINE Project approaches and solutions to enable AI-empowered industrial applications to efficiently and securely operate at the network edge. First, two use cases are presented to highlight the motivations for secure edge computing in industrial plants, including low-latency applications and the need to locally handle production data in a secure way. Then, AI-based proactive and reactive approaches are discussed to provide comprehensive cyber security at the industrial edge. Finally, two specific hardware accelerated implementations for cyber security are presented. The first implementation focuses on data encryption at network interface cards, the second implementation provides deep packet inspection for reconnaissance detection in switching elements. Results that hardware accelerated solutions enable the effective deployment of security solutions guaranteeing wire-speed operations while freeing CPU resources for industrial applications.

This paper is reporting the data concerning impurities occlusion in the dried, milled and classified aluminum hydroxide, the sources of contamination and the ways to control the purity of classified aluminum hydroxide as raw material for special aluminas. Mainly, all the micronic size particles, floating in the super-saturated Bayer liquors, are potential sources of occluded impurities in the aluminum hydroxide particles. There are several mechanisms for embedding the impurities in crystalline substances. Of these, most probable ones in the Bayer alumina process are: a) occlusion of the spent liquor drops containing impurities inside the polycrystalline aluminum hydroxide congregates; b) hetero-nucleation of aluminum hydroxide on the surface of particles or colloids containing one or more impurities (the foreign particles are seized inside a crystals or inside of a crystalline multi-particulate association); c) incorporation of available ions or molecule reactive fragments in the poor crystalline structures of aluminum hydroxide after nucleation, during different growth stages of all already aggregated particles, under certain super-saturations. d) building up bridges between the scanty aggregated particles or filling the inside hollows of these aggregates with new quickly crystallized material, including the particulate impurities, mainly, during large fluctuations of the super-saturation. Using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy EDS (Apollo SSD detector, EDAX), the contributions of each of these mechanisms can be investigated simply and assumed from the collected data. It was shown that well crystallized phases originating directly from bauxite (like the aluminum substituted goethite and substituted hematite, rutile or quartz), as well as the well as the crystallized new born phases during specific Bayer reactions (like cancrinite, are not promoting directly the impurities occlusion. Poor crystalline phases (like sodalite and katoite or other secondary phases and their micronic size fragments are really sustaining impurities occlusion through all the acknowledged mechanisms.

The purpose of this article is to better understand the behaviour of the residual stresses in aluminium alloy plates, to control and minimize them by adjusting the quenching and the stretching process parameters. Residual stresses have usually the same role in a material as ordinary mechanical stresses, but while the stresses due to external loads can be calculated with a high degree of accuracy, the same thing cannot be said about residual stresses. The evolution of the residual stresses in the aluminium plates and the influence of the quenching and stretching process conditions was investigated by the Hole-Drilling method. The experiments were performed only on the industrial equipment. Plates with the same chemical composition were quenched by water spray or by immersion in water with or without agitation of the cooling medium. Also the plates quenched by water spray were unidirectional, bidirectional and successive stretchered. The results show the influence of the quenching conditions and of the stretching rate on residual stresses and also the correlation between the stretch rate and the residual stresses was established. Thus, the residual stresses increase from 158 MPa for quenched by water spraying to 187 MPa for horizontal quenched by immersion with agitation of the quenching water. The decrease of the residual stresses slope is reduced by the increase of the stretch rate with over 4%. The increase of the stretch rate with over 4% determines a significant reduction of the residual stresses.

The suppliers of the heat treatment furnaces have created the possibility to control the distance from the top nozzles to the plate surface during the quenching by mechanical displacement of the spray nozzles. The influence of the distance between the plate and the top nozzles during the soft quenching process was studied by using ANSYS finite element soft. This distance determines the area of spray nozzles on the plates and influences the quenching process by different values of the heat transfer coefficients. The mathematical model of the soft quenching process by water spraying for a 6061 aluminium alloy plate of 10 mm thickness was presented and validated on industrial equipment. Different distances between the top nozzles and the plate were simulated. The achieved results confirmed the influence of the distance between the plates and the top nozzles, during the soft quenching process on the cooling rate and on the 6061 aluminium alloy plate material properties.

Chemical analysis, classical or instrumental using ICP and the XRF spectrometry, offers complete information on elemental composition and major chemical constituents of bauxite and bauxite residues resulted from the Bayer process. The XRD diffractometric analysis provides information on quantitative mineralogical composition of these materials and it enables the real identification of main chemical combinations, whose reactivity is essential in driving the process of obtaining alumina through the Bayer process. Mineralogical components identified in the bauxite samples were Gibbsite (30-40 %), Al – goethite (20-30 %) and hematite (less than 5 %). About 40 % of the Sierra Leone bauxite mineralogical phases were found in amorphous state, but all these amorphous phases are also originating from the above crystalline components, under the excessive wearing during bauxite deposit formation and its metamorphic transformations. The minor crystalline components from bauxite are: kaolin, quartz, zircon, ilmenite and anatase, but their concentration is below 2 % (close to the detection limit of the XRD analysis). The main mineralogical components identified in red mud are the Al-goethite (35 %) and the hematite (12 %). The minor crystalline components from red mud are: gibbsite, katoite, sodalite, calcite, rutile and anatase. Experimental data of this type of bauxite have shown that a compact mass of approximately 50-55 % of bauxite passes fully untransformed through all important stages of the Bayer process. This material of uniform size and composition can form a structure with low hydraulic resistance, easy filterable both on conventional or hyperbaric steam filters Химический анализ, классический или инструментальный с использованием индуктивно связанной плазмы (ИСП) и рентгенофлуоресцентного анализа (РФА), дает достаточную информацию по элементному анализу и основным химическим составляющим боксита и бокситовых осадков, образующихся в процессе Байера. Рентгеновская дифрактометрия информирует о количественном минералогическом составе этих материалов и обеспечивает реальную идентификацию основных химических комбинаций, реакционная способность которых служит движущей силой получения глинозема в процессе Байера. В пробах боксита были следующие минералогические компоненты: гиббсит (30-40 %), алюмогетит (20- 30 %) и глиноземистый гематит (менее 5 %). Около 40 % состава боксита из Сьерра-Леоне представлено аморфными материалами, однако эти аморфные фазы также образованы вышеупомянутыми кристаллическими компонентами при чрезмерном износе в процессе образования бокситового осадка и его метаморфических превращений. Второстепенными кристаллическими компонентами в боксите являются: каолин, кварц, циркон, ильменит и анатаз, но их концентрация менее 2 % (близко к пределу обнаружения рентгенодифракционным анализом, РДА). Основные минералогические компоненты, определенные в красном шламе, – алюмогетит (35 %) и глиноземистый гематит (12 %). Второстепенные кристаллические компоненты в красном шламе – гиббсит, катоит, содалит, кальцит, рутил и анатаз. Экспериментальные данные по этому типу бокситов показывают, что компактная масса в размере 50-55 % боксита проходит практически без превращений через все важные стадии процесса Байера. Этот материал однородного размера и состава может образовывать структуры с низким гидравлическим сопротивлением, легко фильтруемые на традиционных фильтрах или фильтрах с избыточным давлением пара

The homogenization treatment of 7075 aluminium alloy slabs is required for ensuring the technological properties for later processing. This usually has two stages. The soaking time in the second stage has an important influence. In order to evaluate the influence of this parameter, the homogenization, solution heat treatment, quenching and ageing treatment were simulated in the laboratory at various homogenization soaking time between 4 and 24 h. The evolution of the eutectic structures in the as-cast and homogenized 7075 aluminium alloy were investigated by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), differential scanning calorimetry (DSC) and tensile test. The results demonstrate that from many standpoints (mechanical properties, microstructure etc.) the complete dissolution of all soluble phases ends before the limit of 20 h that is considered as standard all over industry.

Today, in the electrolysis area of modern aluminium smelters, treatment of pot gas emissions has been drastically improved by the latest generation of dry scrubbing technologies, with efficiency rates close to 99.8%. As a consequence, stack emissions now only represent a very small amount of the total fluorides emitted over the entire smelter. Most of the HF is released to the atmosphere directly from the potroom, where in many smelters no specific treatment is provided to limit emissions related to pot maintenance activities (pot hoods opening, spent anodes removal, etc.). FIVES SOLIOS now proposes a solution to eliminate emissions coming from hot spent anodes stored in potroom thanks to an Anode Inert Tray (AIT) designed to confine anode butts. This paper presents the results of the industrial first of class AIT, developed conjointly between FIVES SOLIOS and FIVES ECL and which has been operated by ALRO for several months.

The evolution of plasticity of heat treatable alloys in W temper is important for an efficient stress releasing by stretching or compression (Tx51 and Tx52 tempers) but also for some special hardening operations that combine cold working and ageing practices. For the alloys that have a significant natural ageing, the environment temperature has an important influence. In order to evaluate the influence of this temperature, the mechanical properties and the microstructure were investigated at various temperatures between −10 and + 80 °C and ageing time between 0 and 80 h on plates in alloy EN AW 2024, using standard tensile tests, electronic microscopy and X Ray diffraction. The results demonstrate that from many standpoints (mechanical properties, plasticity, electrical conductivity, microstructure etc.) the ageing transformations end before the limit of 96 hours that is considered as standard.