Aluminium Smelter Plant Research Articles

Recycling of hazardous and industrial solid waste as raw materials for preparing novel high-temperature-resistant sulfoaluminate-magnesia aluminum spinel cement

Secondary aluminum dross from aluminum smelter plants is a hazardous waste with no effective method for realizing its disposal and utilization safely. This research evaluated the potential of preparing novel high-temperature-resistant sulfoaluminate-magnesia aluminum spinel (SAC-MA) cement using secondary aluminum dross, carbide slag, magnesite tailings and desulfurization gypsum as the raw materials for the replacement of natural resources. Furthermore, the leaching toxicity of unroasted and preroasted secondary aluminum dross was analyzed. The mineral phase and microstructure of clinkers and hydration products were also considered and their effect on the mechanical properties and microstructure of the high-temperature-resistant SAC-MA samples was researched. The experimental results showed that roasting detoxification was effective in realizing the safe disposal of secondary aluminum dross and magnesia aluminum spinel, dicalcium silicate and Fe→Al substitutional ye'elimite formed in the SAC-MA clinker after the sintering using hazardous and industrial solid waste. Improved high temperature resistance of SAC was also observed. High temperature induced the decomposition of ettringite and led to its structural relaxation. Surprisingly, the existence of magnesia aluminum spinel made the structure of ettringite smaller and decreased the decomposition degree of ettringite, as well as improving the high temperature resistance of SAC. Changes in the main skeletal structures of ettringite and AH3 gel were not noticeable, which still had good stability at 200 °C for the SAC-MA sample. However, ettringite gradually became amorphous at 200 °C for the SAC sample. These results strongly indicated that using hazardous waste, including secondary aluminum dross, as raw materials for preparing SAC-MA was far superior to SAC with regards to high temperature resistance. This study contributed a novel example of converting hazardous and industrial solid waste into high value-added materials and may open a new approach for synthesizing high temperature-resistant SAC-MA cement from low-cost feedstocks.

300,000 TPY Aluminium Smelter Upgrading Project at PT. Indonesia Asahan Aluminium (Persero) in North Sumatera

Growing demand of aluminium in domestic and international markets, forcing aluminium producers to modify their smelter to increase the production as well as to reduce the electricity consumption, though to build a new aluminium smelter plant is one of solution to meet this demand. This article is described modification one of the aluminium smelter plant in North Sumatera Province, Indonesia as a parts of aluminium smelter upgrading project to reach production up to 300,000 TPY.

Nitrogen management can boost rice (Oryza sativa L.) production near aluminium smelter: A field study

Nitrogen (N) management is a key to sustain rice yield under submerged condition. Time and amount of N application boost rice production under adverse environmental situation. To test this hypothesis a field experiment was conducted at different villages in and around Hindustan Aluminium Company Ltd. (HINDALCO), Hirakud, Sambalpur, Odisha in the year 2015 and 2016. The rice ecosystems were selected on the basis of distance from the smelter plant. Different treatments were framed to test the hypothesis as T1-Farmers practice (60:30:30 kg N: P2 O5:K2O ha-1); T2- 75% recommended dose of fertilizer (RDF) of nitrogen(N) ; T3 -100% RDF of N; T4 -125% RDF of N; T5 -150% RDF of N. It was conducted in a randomized block design with four replications in the farmer's field. The test crop was rice cv.Tejaswinee. Growth parameters like plant height (cm), panicle length (cm) and number of effective tillers per hill were found to be highest in the plots where 125% RDF of N was applied. However the chlorophyll content(mg g-1 fresh)was estimated highest with 150 % RDF of N applied plots. The grain and straw yield (q ha-1) of rice were also observed highest with treatments receiving125% RDF of N.The rice ecosystems which are nearer to aluminium smelter plant were supposed to be affected with less yield as compared to far distance rice ecosystems. The grain quality parameterof rice like protein content (%) was also affected at smelter sites as compared to far distances. However with increasing the N level to 125 % RDF protein content was increased.

Effect of Calcination Condition on Thermal Activation of Ibere Clay and Dissolution of Alumina

Bauxite deposits for production of alumina are lacking in Nigeria and there is an aluminium smelter plant in the country which requires alumina for its operation. Development of alternative alumina resource using clays that are abundant in the country is the focus of this paper. The thermal activation of Ibere clay from southeastern Nigeria for optimal leaching of alumina was investigated. The clay assayed 28.52% Al2O3 and 51.6% SiO2, comprising mainly kaolinite mineral and quartz or free silica. The alumina locked up in the clay structure was rendered acid-soluble by thermal activation which transformed the clay from its crystalline nature to an amorphous, anhydrous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500°C, 600°C, 700°C, 800°C, and 900°C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000°C (holding for 60 minutes) were used in the control experiments. The result of leaching the clay calcines in 1 M hydrochloric acid solution at room temperature, showed that the clay calcines produced at 600°C (holding for 60 minutes) responded most to leaching. Samples calcined for 60 minutes also responded better than those held for 30 or 90 minutes. Based on activation energy studies, it was observed that calcines produced at 600°C (for 60 minutes) had both the highest leaching response (50.27% after 1 hour at leaching temperature of 100°C) and the lowest activation energy of 24.26 kJ/mol. It is concluded therefore that Ibere kaolinite clay should be best calcined for alumina dissolution by heating up to 600°C and holding for 60 minutes at that temperature. The clay deposit has potential for use as alternative resource for alumina production in Nigeria where bauxite is scarce.

Fluoride Concentration in Ground Water Around an Aluminium Smelter Plant (A Case Study) in Angul–Talcher Industrial Belt, Odisha, India

Fluoride is the naturally-occurring stable form of the gaseous element fluorine (F). Fluoride is among the top 15 most abundant components on the Earth’s crust [21] and is naturally found in very small amounts in most aquifers in India [23]. An aquifer is an underground unit of saturated earth materials that can provide usable quantities of ground water to a well [5]. This paper gives the result of fluoride measurement in ground water around a major Aluminium smelter plant in India. The concentration of different water quality parameters like pH, electrical conductivity, total alkalinity, bicarbonate, chloride, nitrate, sulfate, total hardness, total dissolved salts, calcium and magnesium are estimated along with fluoride in ground water. Over 216 water samples are taken for analysis for a period of 12 months. The paper also reports the result of correlation coefficient between different water quality parameters.

Conversion of byproduct carbon obtained from spent pot liner treatment plant of aluminum industries to blast furnace tap hole mass[

The paper describes a method for converting carbon powder obtained as byproduct while decontaminating pot liner by acid treatment route, into blast furnace tap hole mass. Producing an useful industrial product from waste helps in paying back the cost incurred during decontamination process of pot liner and thus improves the overall economics of the process. Blast furnace tap hole mass is a prepared muddy material used to close the tap hole of iron making blast furnace. At iron melting temperature the material carbonizes and becomes hard in order to hold the metallostatic pressure inside blast furnace hearth. Since iron gets oxidized at high temperature this tap hole compound is prepared predominantly from carbonaceous material. Further these carbonaceous materials used needs to be semicrystalline in nature in order to withstand high temperature of the furnace. With rising cost of such carbonaceous material used in tap hole compound, it will be advantageous if a source of cheap carbon material matching the properties of carbon material already in use in the tap hole recipe , could be found in order to bring down cost of production of commercial taphole recipe. The aim of this research was to find such a carbonaceous material from an industrial waste which is difficult to dispose because of its toxic contaminants. Such a material chosen for this work is called SPENT POT LINER of aluminum smelter plant. At present majority of the aluminum smelter plants round the world use Hall-Heraoult's electrolysis process for extracting aluminum metal from molten cryolite. The electrolysis cell used for this purpose constitute large carbon blocks as cathode laid at the bottom and side wall of the cell. These carbon electrodes are known as pot and basically made of anthracite, graphite and binder/electrode pitch. Various manufactures uses 20-30% (1) graphite in their recipe in order to meet electrical properties needed for the pot liner. While graphite is a superior electrical conductor than anthracite (which has similar structure to graphite), 100% graphite is never used in the manufacture of pot as it is soft and can not withstand turbulent molten cryolite contained in the cell. Anthracite on the other hand provides required mechanical property to the finished pot liner. The prefabricated pot liner produces carbon matrix with short range order. Thus prepared pot ultimately contain both crystalline (graphite) and amorphous carbon. During service molten cryolite slowly gets reduced and the sodium fluoride crystal deposits within the fine crevices of pot liner creating defect spots . As time passes, these crystals grow and exert pressure within these crevices resulting in the propagation of crack. As a consequence, with time the pot liner looses its electrical property and ultimately being discarded. These rejected waste pot are called spent pot liners (in short SPL). Spent pot are not only contaminated by fluoride but also by other toxic elements such as cyanides (formed at high temperature reaction with atmospheric nitrogen), alkalis and aluminum. Table-1 below shows typical range of the contaminants in such discarded pot along with concentration of these toxic elements in SPL carbon powder after decontamination with oxidizing acids. In practice suitability of a specific component in a commercial recipe is tested by evaluating some gross property of the modified recipe against the production recipe of the compound. For example, in development of foundry chemicals (like mould coating, tundish cover , hot tops etc) which basically a combination of various components in a formulation , various substitutes are being tried with above procedure of gross evaluation of certain properties of the compound in order to determine its suitability. Similarly in present case of developing suitable substitute of carbonaceous material in commercial tap hole compound recipe, following properties are important in order to determine its suitability. Apparent porosity. This property determines the ease with which gas generated in the tap hole compound during carbonization can escape easily without breaking or decreasing strength of the carbonized tap hole mass. This value is generally maintained in the range 25-35%. a) Bulk density. This is maintained in the range 1.3-1.6 gm/cc in all commercial recipe in order to match with standard pushing length required by the equipment to fill the tap hole.

Modeling Aluminum Smelter Plants Using Sliced Inverse Regression With a View Towards Load Flexibility

This paper describes the application of sliced inverse regression to model the electrochemical process of aluminum smelter plants. Real data measurements obtained during several years in a Spanish industrial environment are used to illustrate the main dependencies between parameters. Nonlinear relations between the output variables and relevant linear combinations of input variables are deduced. An exploratory statistical analysis is also presented, checking for correlations and possible linear dependencies. The developed model is used to analyze the range of electrical power demand variations as a consequence of modifications in chemical and electrical parameters. An example is described maintaining constant the aluminum production. The results can be considered for future load flexibility programs, which might include aluminum smelter plants as a flexible industrial customer.

Speciation of aluminium fluoride complexes and Al3+ in soils from the vicinity of an aluminium smelter plant by hyphenated High Performance Ion Chromatography Flame Atomic Absorption Spectrometry technique

Abstract The paper presents a new tool for the determination of inorganic speciation forms of aluminium: AlFn(3 − n)+, and Al3+ by means of the HPIC-FAAS. The proposed method has been successfully used for speciation analysis (qualitative and quantitative) of inorganic aluminium forms AlFn(3 − n)+ in soil samples. In order to isolate the most environmentally available fraction, 5 g of the sample was collected and extracted in deionised water (water soluble fraction) for 1 h using a magnetic stirrer. The determinations in a hyphenated technique system were performed for a number of prepared water extracts. Concentration determinations of particular aluminium forms were performed based on model studies and real samples. The separation of Al species with nominal charge of + 1, + 2, and + 3 required a run time of less than 4 min during a single analysis. Based on the analysis of water extracts of soil, it was obtained that aluminium forms elute in the following order: 1PA (first signal) — AlF2+ and/or AlF4−; 2PA (second signal) — AlF2+ and/or AlF30; 3PA (third signal) — Al3+. In order to confirm the occurrence of these forms a simulation using the Mineql program was conducted. The details of speciation analysis of aluminium fluoride forms by means of an HPIC-FAAS instrument equipped are presented. Interpretation of the speciation analysis of the water soluble fraction of soil samples is proposed, based on the separation during chromatographic run and calculated data by Mineql.

The cost and cost‐effectiveness of malaria vector control by residual insecticide house‐spraying in southern Mozambique: a rural and urban analysis

To compare two separately funded, but operationally similar, residual household-spraying (RHS) initiatives; one rural and one peri-urban in southern Mozambique. The rural programme is a regional project involving the participation and co-ordination of organizations across three countries in southern Africa and is focussed on control in an area in Mozambique of 7552 km2. The second programme focuses on spraying a peri-urban community within a 10-km radius around MOZAL, an aluminium smelter plant of area 410 km2. An ingredients approach was used to derive unit costs for both the rural and peri-urban spraying programmes using detail retrospective cost data and effectiveness indicators. The economic cost per person covered per year using Carbamates for indoor residual spraying (IRS) in the rural area, excluding the costs of project management and monitoring and surveillance was $3.48 and in the peri-urban area, $2.16. The financial costs per person covered in the rural area and peri-urban area per year were $3.86 and $2.41, respectively. The economic costs per person covered were respectively increased by 39% and 31% when project management and monitoring and surveillance were included. The main driving forces behind the costs of delivering RHS are twofold: the population covered and insecticide used. Computed economic and financial costs are presented for all four insecticide families available for use in RHS. The results from both these initiatives, especially the rural area, should be interpreted as conservative cost estimates as they exclude the additional health gains that the newly introduced programmes have had on malaria rates in the neighbouring areas of South Africa and Swaziland. Both these initiatives show that introducing an IRS programme can deliver a reduction in malaria-related suffering providing financial support, political will, collaborative management and training and community involvement are in place.

P4F117 - Monitoring of fluoride content in the environment around an aluminium smelter plant

The effects of fluoride emissions, from an aluminium reduction plant in Greece, on the concentration of fluoride in soils and natural vegetation and also the relation between injury and fluoide content of plants were investigated.Fluoride emissions from the factory caused toxicity to natural vegetation in the adjoining area. Some plant species accumulated high fluoride levels in the leaves and exhibited acute necrosis, chlorosis or both. Others did not show visible injury, in spite of their high fluoride accumulation. The intensity of symptoms changed a great deal from one individual plant to the other or even from leaves of the same plant.The average levels of fluoride in vegetation ranged from 621.2 to 257.2 ppm in severely damaged areas (zone I) and from 144.3 to 64.1 ppm in lightly damaged areas (zone III). The corresponding fluoride levels in the controls was 15.4−8.2 ppm. In soils total fluoride concentrations ranged from 823.5 to 297.6 respectively; the levels in controls ranged from 108.6 to 95.3 ppm.

Load representation for steady-state voltage stability studies

This paper presents new models for representation of different load types in steady-state voltage stability studies. The models are derived from the available measured characteristics of the power system loads. Special attention is paid to the induction motor load, with different mechanical loading as well as for special large loads such as aluminum smelter plants and are furnaces loads. Comparisons between results from the known models and the developed models are made and the necessity for using these developed models are put forward. It is also proved that erroneous results will be obtained using known available models of these loads.