Addition Of Red Mud Research Articles

Durability of Red Mud Based Geopolymer Paste in Acid Solutions

The present investigation is on the effect of red mud on the mechanical properties and durability of the geopolymer paste in sulphuric and acetic acid solution. Red mud and fly ash were used to form the geopolymer paste along with the alkalies. The variation of red mud in the paste composition was from 0% to 90%. Cylindrical shaped specimens of 1 inch diameter and 1 inch height were prepared. The specimens were immersed in 5% sulphuric acid and 5% acetic acid for 1, 7, 14, 28, 56 and 84 days and tested for weight loss, visual deformation, strength loss and colour of the solvent, based on the procedure specified by ASTM C 267 – 01. SEM/EDX Tests were performed on the geopolymer specimens. Test results show that initially, the strength of the geopolymer increased upon the addition of red mud. The strength was maximum when the percentage of red mud was 30%. The maximum strength obtained was 38 MPa for the paste containing 30% red mud using 10M alkali solution as against 31.69 MPa, when only fly ash was used. Geopolymer paste containing 30% and 50% red mud showed better resistance to acid attack. The strength loss was minimum for the samples containing 30% red mud in both inorganic and organic acid i.e. sulphuric and acetic acid.

Effects of red mud on properties of self-compacting mortar

Red mud is a waste material derived from alumina refineries through the Bayer process. In this paper, the red mud is used to replace fly ash at various replacement ratios in the production of self-compacting mortars. Two series of mix proportions (series I and II) are designed to investigate the fresh and hardened properties of self-compacting mortars (SCM). In series I, the replacement ratios of red mud range from 0% to 50% by weight; in series II fly ash is replaced by red mud at 0%, 25%, 50%, 75% and 100% by weight. The results show that the fluidity is reduced as red mud is used to replace fly ash; meanwhile, a trend towards mitigation of bleeding is observed due to red mud porosity. An increase in red mud content also brings a slight decrease of hardened density, an increase of water absorption and permeable voids. In the case of mechanical properties, red mud is effective in enhancement of the compressive and flexural strength; the compressive and flexural strength of SCM mixture samples prepared with red mud at 50% of replacement ratio are higher than those of other samples. As for the drying shrinkage and autogenous strains, all drying shrinkage values are increased as red mud is used to replace fly ash; however, a decrease of autogenous strains is observed with an addition of red mud, and the trend is more pronounced when the replacement ratio is 50%.

Effect of red mud addition on tetracycline and copper resistance genes and microbial community during the full scale swine manure composting

Swine manure has been considered as the reservoir of antibiotic resistance genes (ARGs). Composting is one of the most suitable technologies for treating livestock manures, and red mud was proved to have a positive effect on nitrogen conservation during composting. This study investigated the abundance of eight tetracycline and three copper resistance genes, the bacterial community during the full scale swine manure composting with or without addition of red mud. The results showed that ARGs in swine manure could be effectively removed through composting (reduced by 2.4log copies/g TS), especially during the thermophilic phase (reduced by 1.5log copies/g TS), which the main contributor might be temperature. Additionally, evolution of bacterial community could also have a great influence on ARGs. Although addition of red mud could enhance nitrogen conservation, it obviously hindered removal of ARGs (reduced by 1.7log copies/g TS) and affected shaping of bacterial community during composting.

Effects of red mud addition on cadmium accumulation in cole (Brassica campestris L.) under high fertilization conditions

Purpose Applications of mineral and organic fertilizer increased soil cadmium (Cd) and could enhance Cd concentrations in edible crops, respectively. Although red mud (RMD) effectively decreased metal bioavailability in soil, the influence of RMD addition on vegetable growth and metal accumulation under high fertilization conditions has rarely been addressed. The aim of this study was to investigate the effects of raw RMD addition on cole growth, quality, and nutrition and Cd accumulation under high fertilization conditions.

Evolution of structural characteristics and compressive strength in red mud–metakaolin based geopolymer systems

The structure and mechanical performance of red mud–metakaolin based geopolymers with varying red mud contents (0–40wt% red mud in red mud–metakaolin raw material mixture) were investigated by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM) and compressive strength measurements to understand structure–performance relationships in this system. Systematic addition of red mud into geopolymer system resulted in constant loss of intensity and increased broadening of the main features in XRD and FTIR spectra. The compressive strength was at maximum (51.5MPa) for metakaolin based geopolymer while increasing red mud incorporation in this system resulted in a nearly monotonous decreasing trend in the compressive strength. Iron species originating from red mud were found to be the main factor controlling the evolution of structural characteristics and mechanical performance. The main role of iron species in the system was to prevent dissolution of raw materials in the geopolymer matrix to a great extent. This was supported by diffraction, spectroscopy and microscopy results and was correlated with the decreasing trend in compressive strength with increasing red mud content.

EFFECTS OF ADDITION OF RED MUD ON EMISSION OF GREENHOUSE GASES AND AMMONIA FROM FULL-SCALE SWINE MANURE WINDROW COMPOSTING

It is of great concern to reduce greenhouse gases (GHG) and ammonia (NH3) emissions from animal manure composting in China. The purpose of this study was to investigate effects of adding red mud on emissions of GHG (methane (CH4), nitrous oxide (N2O)) and NH3 in full-scale swine manure windrow composting. Two full-scale swine manure windrow composting experiments were carried out to compare emission of GHG and NH3 with and without addition of red mud. Results showed that the addition of modified red mud reduced N2O emissions by 4.03%, however, it did not help reduce CH4 emissions (51.65% higher than that of the control test). Ammonia emission from both the experimental and the control tests were similar. The addition of modified red mud was useful to conserve nitrogen and phosphorus because the contents of total nitrogen and total phosphorus in the compost of the experiment test were higher than the control test. It was also found that turning was useful to reduce CH4 emissions, i.e. 51.72% reduction of CH4 emission after turning compared to before turning. However, turning resulted in an increased N2O emission flux by 23.15 times in the experiment test and 15.31 times in the control test, respectively.

Leaching of copper and nickel in soil-water systems contaminated by bauxite residue (red mud) from Ajka, Hungary: the importance of soil organic matter.

Red mud is a highly alkaline (pH >12) waste product from bauxite ore processing. The red mud spill at Ajka, Hungary, in 2010 released 1 million m3 of caustic red mud into the surrounding area with devastating results. Aerobic and anaerobic batch experiments and solid phase extraction techniques were used to assess the impact of red mud addition on the mobility of Cu and Ni in soils from near the Ajka spill site. Red mud addition increases aqueous dissolved organic carbon (DOC) concentrations due to soil alkalisation, and this led to increased mobility of Cu and Ni complexed to organic matter. With Ajka soils, more Cu was mobilised by contact with red mud than Ni, despite a higher overall Ni concentration in the solid phase. This is most probably because Cu has a higher affinity to form complexes with organic matter than Ni. In aerobic experiments, contact with the atmosphere reduced soil pH via carbonation reactions, and this reduced organic matter dissolution and thereby lowered Cu/Ni mobility. These data show that the mixing of red mud into organic rich soils is an area of concern, as there is a potential to mobilise Cu and Ni as organically bound complexes, via soil alkalisation. This could be especially problematic in locations where anaerobic conditions can prevail, such as wetland areas contaminated by the spill.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-015-4282-4) contains supplementary material, which is available to authorized users.

Effect of red mud filler on mechanical and buckling characteristics of coir fibre-reinforced polymer composite

Red mud produced as by-product in Bayer’s process for alumina production is posing severe environmental challenge in its disposal. Present work describes using this environmental pollutant as filler in combination with coir fibre using polyester resin for composite production. Tensile properties, flexural properties, compressive properties, hardness and density of coir polymer composites with and without red mud filler were evaluated experimentally. Subsequently, buckling analysis of the prepared composite was also done experimentally and using finite element method at different grid size and for different number of elements to establish the grid independence of obtained results. It has been observed that compressive strength, hardness and density of the prepared composite improved with addition of red mud as filler. This may be attributed to metallic oxides present in chemical composition of red mud. Addition of the filler had a negative effect on tensile and buckling properties as the load cannot be transferred effectively from fibre to resin. Interestingly, it has been observed that composite plates with 20 % fibre gave optimum combination of various properties. The main aim of this work was to study the effect of red mud filler on the mechanical properties and buckling strength of the prepared composites leading to development of a novel low-cost, light-weight composite material using an environmental pollutant which can be used for light-weight structural application.

Efeito da adição de lama vermelha nas propriedades eletroquímicas e de adsorção de um latossolo vermelho

Esse estudo teve como objetivo caracterizar o resíduo gerado na produção de alumina a partir do refino de bauxita (lama vermelha) e analisar o seu efeito nas propriedades eletroquímicas e de adsorção de um solo tropical (Latossolo Vermelho). A lama vermelha (LM) é um resíduo extremamente alcalino (pH em torno de 12) e rico em óxido/hidróxidos de ferro. Para estudar o efeito da lama vermelha e do carbonato de cálcio (CaCO3) - comumente utilizado como corretivo de pH - no solo, essas substâncias foram adicionadas em diferentes proporções em amostras de Latossolo Vermelho por 60 dias. Verificou-se que a adição de LM e de CaCO3 no solo elevaram opHeo ponto de carga zero (PCZ) do meio. No entanto, o valor de pH H2O do solo com LM superou ao do respectivo PCZ, possibilitando a ocorrência de dispersão das partículas do solo. Por outro lado, essa adição favoreceu a capacidade de troca catiônica do solo, como pôde ser observado nos testes de remoção de Pb2+ em solução. Verificou-se que a adição mínima de 0,5% de CaCO3 e de 10% de LM no solo aumenta a capacidade de retenção de Pb2+ de 37% para 100%. Essa mesma eficiência foi observada nos testes realizados somente com LM. Mesmo quando submetido a uma lixiviação ácida (solução pH 4,9) os solos incubados com 1% de CaCO3 e 1% de LM liberaram, respectivamente, 7,5% e 11% de Pb2+ adsorvido. Essa pequena taxa de lixiviação de Pb2+ se deve ao aumento do pH do meio, que favorece a adsorção de Pb2+ pelos oxi-hidróxidos de Al e Fe presentes no solo e na lama vermelha. Conclui-se, portanto, que a adição da lama vermelha pode alterar as condições eletroquímicas do solo, tornando as partículas argilosas e coloidais mais dispersas. No entanto, por elevar o pH do sistema e apresentar óxidos e hidróxidos de Fe e Al, esse material pode aumentar a retenção de metais pesados, como o Pb2+, no solo.

The Effects of Ageing Temperature and Time on Mechanical Properties of A356 Aluminium cast Alloy with Red Mud Addition and Treated By T6 Heat Treatment

An investigation was carried out to study the effect of addition of different percentage (5%, 10%, 15% and 20%) of red mud with A356 cast alloy subject to T6 Heat treatment. A356 Alloys of appropriate composition were cast into sand moulds by stir casting techniques with the addition of different percentage of red mud. The metal matrix composites were subjected to homogenization for 24hours at 500o and solution treatment for 12hours at 540 o C after natural ageing at room temperature for 24hours, artificial ageing was carried out at different temperature (100o,200 o,300 o and 400oC) and different timing (2,4,6,and 8hours). Tensile, Hardness and wear properties were determined by standard tests. During artificial ageing, the ultimate tensile strength and hardness were found to increase with ageing temperature; the maximum being attained at peak aged condition. After peak ageing temperature the ultimate tensile strength and hardness found to be decreased. The ageing time is having less significant effect on ultimate strength. The rate of ultimate strength is higher at initial ageing temperature then started reducing gradually the decrease in ultimate strength might represents over ageing time. The wear properties found to be increase with hardness and ageing temperature and with respect to ageing time the peak age timing which gives highest hardness was found to decrease with increase of the red mud content. The wear rate found to be decreases when the hardness increases. The addition of Red mud resulted in an increase in hardness and tensile strength. The effect of artificial aging on the microstructure is also studied by scanning electron microscopy.

Synthesis and properties of new materials produced by alkaline activation of glass cullet and red mud

This study presents data regarding the synthesis of binding materials through the alkaline activation of waste glass (bottle glass cullet) with NaOH solution. As addition was used red mud, a residue resulted in bauxite processing, due to its high alkalinity and aluminum content. This paper presents the influence of processing parameters (composition of solid component, curing time and temperature) on the compressive strength and hydrolytic stability of this type of alkali activated cements. The effect of red mud addition on the hardening processes, reaction products and material's microstructure was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TG & DTA). The main reaction products are sodium silicate or/and sodium silicate aluminates hydrates with amorphous to crystalline morphologies. The amount of reaction products increases with the increase of the initial curing time at 60°C and consequently it was achieved an increase of the compressive strength values. As a negative side effect the hydrolytic stability of these materials is affected by the increase of the initial curing time at 60°C. Despite the fact that addition of aluminum to sodium silicate hydrates improve their hydrolytic stability, the expected positive influence of red mud addition to the studied binding systems was not observed. This can be due to the low amount of supplementary aluminum brought in the activator solution by the red mud as well as the high amount of iron phases present also in this waste.

Effect of Redmud Particulates on Mechanical Properties of BFRP Composites

This article reports the effective usage of redmud (RM), an industrial waste, as a novel filler in polymer matrix. The composite has been fabricated with redmud as secondary reinforcement in banana fiber reinforced polyester (BFRP) using compression molding technique. The mechanical properties such as tensile, flexural and impact strength have been studied for different fiber weight percentage, weight percentage of red mud and chemical treatment of fiber. It is observed that the addition of 10 wt percent of redmud improves the impact and flexural properties for both NaOH, silane treated and untreated banana fiber but there is a decreased trend for tensile strength. It is also found that banana fiber particulate composites have superior mechanical properties than the banana/polyester. Addition of redmud to the banana fiber decreases the moisture absorption of the composites. The studies of the scanning electron microscopy (SEM) have been done to know the fracture mechanism.

Mobilisation of arsenic from bauxite residue (red mud) affected soils: Effect of pH and redox conditions

The tailings dam breach at the Ajka alumina plant, western Hungary in 2010 introduced ∼1millionm3 of red mud suspension into the surrounding area. Red mud (fine fraction bauxite residue) has a characteristically alkaline pH and contains several potentially toxic elements, including arsenic. Aerobic and anaerobic batch experiments were prepared using soils from near Ajka in order to investigate the effects of red mud addition on soil biogeochemistry and arsenic mobility in soil–water experiments representative of land affected by the red mud spill. XAS analysis showed that As was present in the red mud as As(V) in the form of arsenate. The remobilisation of red mud associated arsenate was highly pH dependent and the addition of phosphate to red mud suspensions greatly enhanced As release to solution. In aerobic batch experiments, where red mud was mixed with soils, As release to solution was highly dependent on pH. Carbonation of these alkaline solutions by dissolution of atmospheric CO2 reduced pH, which resulted in a decrease of aqueous As concentrations over time. However, this did not result in complete removal of aqueous As in any of the experiments. Carbonation did not occur in anaerobic experiments and pH remained high. Aqueous As concentrations initially increased in all the anaerobic red mud amended experiments, and then remained relatively constant as the systems became more reducing, both XANES and HPLC–ICP-MS showed that no As reduction processes occurred and that only As(V) species were present. These experiments show that there is the potential for increased As mobility in soil–water systems affected by red mud addition under both aerobic and anaerobic conditions.

Influence of low-alkali red mud on the composition and structure of sintering batch consisting of heterogeneous iron-ore concentrates

The influence of low-alkali red mud on the composition and structure of pelletized sintering batch at OAO Severstal’ consisting of ferruginous-quartzite ore from the Olenegorsk and Yakovlevsk deposits and magmatic ore from the Kovdor deposit is analyzed. In pelletization, the addition of low-alkali red mud improves the granulation, with increase in the mean granule diameter. The distribution of the main meltforming elements among the batch fractions is established.

Influence of redmud on the mechanical, damping and chemical resistance properties of banana/polyester hybrid composites

A novel hybrid composite was developed with the addition of redmud as secondary reinforcing filler with banana fiber reinforced polyester composites (BFRPCs). The effect of varying parameters such as particle size (4, 6 and 13μm) and weight percentage (2, 4, 6, 8 and 10wt%) of redmud were analyzed on static mechanical, free vibration and chemical resistance properties of hybrid composites. The addition of redmud shown enhanced performance compared to the virgin BFRPCs in all the above said properties. The maximum increase of 50% in mechanical strength was observed for the BFRPCs with the addition of redmud having 4μm particle size and 8wt% of filler content compared to pure BFRPCs. The increased value of fundamental natural frequencies with associated modal damping characteristics of redmud filled BFRPCs were found using half-power band width method. All the fabricated composites performed well against various chemicals and it indicates that the resistance to the weight loss is due to the uniformly distributed redmud. To study the effect of redmud on interfacial bonding between the banana fiber and polyester matrix the Scanning Electron Microscope (SEM) image analysis was performed.

Properties of Clay Ceramic Incorporated with Red Mud

The red mud is a well known insoluble residue generated in the Bayer process to benefit bauxite ores. This residue is composed of ceramic related compounds such as iron oxide, sodium aluminum silicates, carbonates, calcium aluminates and titanium dioxide. The incorporation of industrial residues in clay ceramics has been extensively investigated, not only as an environmentally correct solution but also as an economic way to save raw materials. Therefore, the present work evaluated the properties of clay ceramics incorporated with up to 40 wt% of red mud. Clay bodies with different percentages of red mud were press-molded and fired at 750, 950 and 1050°C. The evaluated technological properties were linear shrinkage, water absorption and mechanical strength. Sensible changes in such properties were found with red mud addition. In particular, the ceramic fired at 1050°C displayed favorable water absorption with red mud incorporation.

Influence of red mud addition on rheological behavior and hardened properties of mortars

This experimental research evaluates the individual and combined influence of red mud particles (RM) and water/binder weight ratio (W/B) on the fresh–hardened properties and durability of cured mortars up to 360days. Samples containing up to 40wt% RM and 0.47–0.58 W/B were prepared keeping the workability constant. Samples with similar workability showed distinct rheological behavior along time. The yield stress was the best rheological parameter to represent such variations. The maximum values of exothermic peak reduced when the Portland cement was replaced by RM. Deeper negative changes in the apparent porosity, water absorption, compressive strength and carbonation extent were also observed changing the W/B ratio from 0.47 to 0.58 in the 20RM-containing mortars. In fact, the compressive strength of mortar 20RM+0.47W/B reduced 13% in comparison to RM-free mortar at 360days, while 20RM+0.58W/B reduced 46%. Although the extra voids created in the matrix by using 0.58W/B implied in a positive effect to the alkali–silica reaction, adjusting a dosage of water similar to the one of RM-free mortar makes RM an attractive alternative without compromise the materials’ properties studied in this work.

Desulfurization Behavior of Cerium–Iron Mixed Metal Oxide Sorbent in Hot Coal Gas

Ce–Fe mixed metal oxide sorbent C2F3B850 was prepared by using cerium oxide and red mud (an iron oxide waste from a steel company). The ability of C2F3B850 (CeO2/red mud = 0.85) was evaluated over a fixed-bed reactor in a simulated coal-derived gas. It was found that the main active components of sorbent C2F3B850 were cerium and iron oxides, the addition of red mud in CeO2-based sorbent could decrease sulfurization temperature, and 500 °C is the best temperature for sulfurization in the range of 500–700 °C. After eight successive sulfurization–regeneration cycles over C2F3B850, the regenerated sorbent still performed well with no apparent deterioration. The average breakthrough sulfur capacity corresponding to H2S concentrations below 50 ppmv is 9.97 (g S/100 g sorbent). Sorbent C2F3B850 during successive sulfurization–regeneration cycles was characterized by means of X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen adsorption–desorption techniques. The results reveal that the C2F3B850 so...

Mechanism of red mud combined with Fenton's reagent in sewage sludge conditioning

Red mud was evaluated as an alternative skeleton builder combined with Fenton's reagent in sewage sludge conditioning. The results show that red mud combined with Fenton's reagent showed good conditioning capability with the pH of the filtrate close to neutrality, indicating that red mud acted as a neutralizer as well as a skeleton builder when jointly used with Fenton's reagent. Through response surface methodology (RSM), the optimal dosages of Fe2+, H2O2 and red mud were proposed as 31.9, 33.7 and 275.1 mg/g DS (dry solids), respectively. The mechanism of the composite conditioner could be illuminated as follows: (1) extracellular polymeric substances (EPS), including loosely bound EPS and tightly bound EPS, were degraded into dissolved organics, e.g., proteins and polysaccharides; (2) bound water was released and converted into free water due to the degradation of EPS; and (3) morphology of the conditioned sludge exhibited a porous structure in contrast with the compact structure of raw sludge, and the addition of red mud formed new mineral phases and a rigid lattice structure in sludge, allowing the outflow of free water. Thus, sludge dewatering performance was effectively improved. The economic assessment for a wastewater treatment plant of 370,000 equivalent inhabitants confirms that using red mud conditioning, combined with Fenton's reagent, leads to a saving of approximately 411,000 USD/y or 50.8 USD/t DS comparing with using lime and ordinary Portland cement combined with Fenton's reagent, and approximately 612,000 USD/y or 75.5 USD/t DS comparing with the traditional treatment.

Aided phytostabilization using Miscanthus sinensis × giganteus on heavy metal-contaminated soils

A field experiment was carried out to evaluate the use of red mud, a by-product of the alumina industry, as a soil amendment on highly contaminated soils in the vicinity of a former Pb–Zn smelter in Copșa Mică (Romania). Changes in the distribution of Zn, Cd and Pb in various soil fractions, mobility of heavy metals in the soil, and their uptake and effects on growth and productivity of Miscanthus sinensis×giganteus were evaluated. Uptake of Zn, Cd and Pb was determined in different tissues of M. sinensis×giganteus cultivated in field plots situated at increasing distance from the pollution source and with different levels of contamination and metal availabilities. Soluble metal concentrations were determined in centrifugates, whereas potentially soluble fractions were analyzed by diffusive gradients in thin films. In terms of the biomass productivity there were significant differences among the plants obtained in plots with different characteristics and pollution levels. Bioconcentration factors were much lower than 1, indicating that M. sinensis×giganteus is an excluder of heavy metals, especially Pb. Amending soils with red mud reduced the exchangeable or phytoavailable fractions of Zn, Cd and Pb. Overall the results suggest that M. sinensis×giganteus is a valuable energy plant and can be successfully grown on heavily contaminated soils with Zn, Cd and Pb. Moreover, the addition of red mud to these soils can lead to a significant decrease in the concentration of heavy metals in the soil and in metal uptake by plant tissues.