Effect Of Red Mud Addition Research Articles

Synergistic catalytic mechanism of red mud in the co-gasification of spirit-based distillers’ grains and sewage sludge

Experiments of co-gasification of spirit-based distillers’ grains (SDG) and sewage sludge (SS) were carried out with red mud (RM) by using a self-designed fixed-bed gasifier. The effects of RM addition, gasification reaction temperature, SS and SDG blending ratio and other factors on the gasification reaction characteristics and synergism were investigated. The results are as follow: RM had catalytic effect on SS and SDG co-gasification, which can enhance the gasification reaction and H2 yield; increasing the temperature can enhance the gasification reaction and reduce the syngas H2/CO; with the increase of SDG, the H2 yield gradually grew; with the rise of SS, the gasification reaction gradually augmented. The catalytic mechanism was mainly due to the redox cycle of Fe2O3 in RM, which can promote the water transfer reaction. At the same time, the eutectic mixture of K, Na, Ca, Fe and other metal elements at high temperatures was the main reason for the synergistic effect.

Effect of Red Mud Addition on Electrical and Magnetic Properties of Hemp-Derived-Biochar-Containing Epoxy Composites

Waste stream valorization is a difficult task where the economic and environmental issues must be balanced. The use of complex metal-rich waste such as red mud is challenging due to the wide variety of metal oxides present such as iron, aluminum, and titanium. The simple separation of each metal is not economically feasible, so alternative routes must be implemented. In this study, we investigated the use of red mud mixed with hemp waste to produce biochar with high conductivity and good magnetic properties induced by the reduction of the metal oxides present in the red mud through carbothermal processes occurring during the co-pyrolysis. The resulting biochar enriched with thermally-reduced red mud is used for the preparation of epoxy-based composites that are tested for electric and magnetic properties. The electric properties are investigated under DC (direct current) regime with or without pressure applied and under AC (alternating current) in a frequency range from 0.5 up to 16 GHz. The magnetic measurements show the effective tailoring of hemp-derived biochar with magnetic structures during the co-pyrolytic process.

Investigation of The Effects of Red Mud Addition on The Properties of Ceramic Wall Tile Body

Endüstriyel atıkların depolanması ve bertaraf edilmesi çevresel etki açısından en önemli problemlerden birisidir. Bu atıkların yeniden kullanılması hem çevrenin korunması açısından hem de alternatif hammadde potansiyellerinden dolayı diğer sanayi dallarının ilgisini çekmektedir. Özellikle de seramik sektöründe giderek artan hammadde maliyetleri ve azalan hammadde kaynakları bu atıkların değerlendirilmesinin önemini artırmaktadır. Bu çalışmada, Konya Seydişehir Alüminyum tesislerinin atığı olan kırmızı çamur alternatif bir hammadde kaynağı olarak kullanılmıştır. Yapılan çalışmada seramik duvar karosu reçetelerinde maksimum % 30 oranında kaolin yerine kırmızı çamur ve kalsit yerinede mermer tozu kullanılmıştır. Numuneler 1130 ° C de 60 dakika süre ile laboratuar koşullarında pişirilmiştir. Numunelerin pişme küçülmesi, su emme ve eğme dayanımları gibi teknolojik özelliklerinin yanı sıra sinterleme ve mikroyapı analizleri de araştırılmıştır. Yapılan testler sonucunda kırmızı çamur ilaveli bünyelerin pişme ve ham mukavemet değerleri artmıştır. Ayrıca herhangi bir pigment ilavesi olmadan sadece kırmızı çamur ilavesi ile kırmızı renkli bünyeler elde edilmiştir.

Effect of red mud addition on oil well cement at high temperatures

Red mud is a byproduct of the aluminium industry and is typically considered hazardous waste owing to its high alkali content and resulting environmental pollution. In this work, Bayer process red mud was used to partially replace oil well cement and its influence on the compressive strength of hardened cement pastes was explored under hydrothermal conditions. X-ray diffraction, scanning electron microscopy, nitrogen adsorption and thermal analysis were used to determine the phase composition, microscopic morphology, pore size distribution and bound water content, respectively, of hardened cement pastes to investigate the reasons underlying the observed strength change. The results obtained revealed that red mud can exert pozzolanic activity at addition levels of up to 5%, promote the cement hydration reaction and the production of calcium silicate hydrate (C–S–H), and ultimately increase the strength of hardened cement pastes. Higher red mud contents decreased the degree of cement hydration, which resulted in an increased volume of macropores (d > 50 nm), a decreased volume of mesopores (d = 4·5–50 nm) and a remarkably decreased strength.

Effects of Red Mud Addition in Soil Fertilized with Cowdung Manure on Growth Performance and Metal Accumulations in Brassica juncea Cultivars Kranti and Pusa Bold

ABSTRACTRed mud (RM) with organic manure may offer suitable substratum to support plant growth. The present study was conducted to evaluate the effects of 0, 5, 10 and 15% (w/w) RM additions in soil fertilized with cowdung manure (soil: manure: 2:1 w/w) on available metal contents, growth performance and metal accumulation in Brassica juncea cultivars Kranti and Pusa Bold. Increasing RM concentrations in manure-amended soil caused a significant increase in total metal contents but their phytoavailable contents decreased. A significant increase in plant growth performance and seed yield was observed up to 10% RM treatment compared to the control (without RM and manure). Maximum increase in seed yield (140.5%) of Pusa Bold and Kranti (120.3%) was found under 10% RM treatment. Metal contents in seeds were within the FAO/WHO safe limits. The study suggests utilization of 10% (w/w) RM in soil fertilized with cowdung manure for cultivation of Kranti and Pusa Bold. Based on plant performance, the study encourages the cultivation of Pusa Bold.

Mechanical properties and micro-mechanism of loess roadbed filling using by-product red mud as a partial alternative

Abstract The disposal of red mud waste has induced critical environmental issue worldwide. While adding red mud waste as a partial alternative in loess subgrade projects can effectively reduce the red mud waste accumulation and engineering cost. Therefore, the feasibility study of red mud waste as loess subgrade filling is in urgent demand. In this study, the mechanical characteristics and micro-mechanism of red mud-treated loess with a small amount of cement additive (RMCL) were analyzed systematically. In order to study the effect of red mud addition on RMCL, tests on the compaction characteristics, strength properties, dynamic behaviors of RMCL were carried. The action mechanism of red mud was also revealed through a series of X-ray diffraction (XRD), light microscope (LM) and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) test. The results show that the red mud content CR has a significant effect on the unconfined compressive strength (UCS) of RMCL. An appropriate amount of red mud waste can effectively improve the mechanical properties of loess subgrade filling. The optimal CR is approximately 15%–20% for loess roadbed filling in this study. In addition, the UCS of RMCL increases with the increasing curing time, but first increases and then decreases with the increase of CR. Considering the effect of CR and curing time, an empirical Gauss 2D model is strongly proposed to predict the UCS value. A good linear relationship is also observed between the UCS value and the resistivity for RMCL. Moreover, the dynamic elastic modulus of RMCL is four times higher than that of untreated loess. Both dynamic stress and confining pressure have significant effect on the dynamic characteristics of RMCL. Based on the microanalysis of XRD, LM, SEM, and EDS, red mud can promote the generation of more cementitious hydrate such as C-S-H/C-A-S-H and Aft due to its strong alkalinity and hydrolysis. These hydrates, red mud fine particles, and aggregates can adhere to the surface of loess particles or fill inter-granular pores to obtain a more compact and stable soil structure, leading to a significant improvement of mechanical properties. The study provides an effective way to recycle red mud waste as a substitutable filler in loess roadbed, exhibiting environmental and economic benefits.

Effects of Red Mud Addition in the Microstructure, Durability and Mechanical Performance of Cement Mortars

Recently, there has been a great effort to incorporate industrial waste into cement-based materials to reach a more sustainable cement industry. In this regard, the Bayer process of obtaining alumina from bauxite generates huge amounts of waste called red mud. Few research articles have pointed out the possibility that red mud has pozzolanic activity. In view of that, the objective of this research is to analyse the short-term effects in the pore structure, mechanical performance and durability of mortars which incorporate up to 20% of red mud as a clinker replacement. As a reference, ordinary Portland cement and fly ash Portland cement mortars were also studied. The microstructure was characterised through mercury intrusion porosimetry and non-destructive impedance spectroscopy, which has not previously been used for studying the pore network evolution of red mud cement-based materials. The possible pozzolanic activity of red mud has been checked using differential scanning calorimetry. The non-steady state chloride migration coefficient and the mechanical properties were studied too. According to the results obtained, the addition of red mud entailed a greater microstructure refinement of the mortar, did not worsen the resistance against chloride ingress and reduced the compressive strength compared to control binders.

The effects of red mud on clay compounds

Recent study focused on the mixing properties of the clay and red mud compounds and the effects of red mud addition on clays with and without earth alkali carbonate content. Raw materials were added to compounds in natural form. Raw materials were applied as received in order to examine how mixing is possible in natural form without drying and grinding the red mud into powder. Highest amount of red mud content (50 wt%) was determined by mixing experiment. Compounds were prepared in pan mill and samples were extruded and analysed. Results indicated that red mud behaved in different way in carbonate and carbonate free clay but it is applicable for manufacturing of heavy clay products. It also revealed that the adequate mixing of red mud into the clay body is one of the most important question of the industrial application.

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.

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.

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.

Effect of red mud addition on the corrosion parameters of reinforced concrete evaluated by electrochemical methods

Red mud, the main waste generated in aluminum and alumina production from bauxite ore by the Bayer process, is considered "hazardous" due to its high pH. The high pH also provides greater protection of rebars, which is reflected in the low corrosion potential and high electrical resistivity (filler effect) of concrete. The corrosion potential was monitored by electrochemical measurements and the electrical resistivity was evaluated using sensors embedded in concrete test specimens. The results showed that the addition of red mud is beneficial to concrete, reducing its corrosion potential and increasing its electrical resistivity. Red mud proved to be a promising additive for concrete to inhibit the corrosion process.

Effect of red mud addition on the fractionation and bio-accessibility of Pb, Zn and As in combined contaminated soil

Using soil incubation experiments, the effect of red mud addition on the fractionation and bioaccessibility of Pb, Zn and As in combined contaminated soil was studied. The results showed that red mud addition could significantly decrease the concentration of HOAc-extractable Pb and Zn in soil. Compared with the control, 5% red mud addition could significantly reduce the concentrations of HOAc-extractable Pb and Zn in soil after 1, 2 and 3 months of incubation [62.5, 65.3 and 73.5% decrease (Pb), 56.7, 65.8 and 67.4% decrease (Zn)]. Whereas adding red mud could remarkably increase the concentrations of specific absorbed As and residual As in soil. The result of a simple bioavailability extraction test (SBET) indicated that all treatments with red mud addition markedly reduced the concentration of bioaccessible Zn but increased the concentration of bioaccessible As in soil, while having little effect on the concentration of bioaccessible Pb in soil. After 3 months incubation, all treatments including 1, 2 and 5% red mud addition reduced the concentration of bioaccessible Zn by 53.1–56.7% compared with the control, but increased the concentration of bioaccessible As by 1.81–6.25 times. The results suggested that red mud is an additive with potential for the remediation soil contaminated soil by combinations of heavy metals, although it should be added based on the different heavy metals in the soil. Combined use of red mud and hyperaccumulators to remediate heavy metal contaminated soil needs further study.

ИсслЕдованиЕ каталитическоЙ актИвностИ краснОгО шлАмА В реакцИИ рАспАдА монооксидА углеродА

The process of iron carburization using СО-contaning gas as a catalyst red mud is investigated. Determined the catalytic activity of red mud in the decomposition reaction of CO. The effect of red mud addition to iron ore materials to improve their recoverability and carburization

Effect of red mud addition on the rheological behaviour and on hardened state characteristics of cement mortars

This paper reports on the use of red mud (RM) in mortars, applying design of experiments. Portland cement was replaced up to 50 wt.% RM, adjusting the relative amount of water (34–38 wt.%) in order to get mortars with suitable workability as defined by rheometry and flow table measurements. Temperature of hydration, compressive strength and water absorption were also determined. RM decreases the workability and increases the torque, but causes lower impact than water variation. The effect on initial yield stress depends on water content. Mortars with similar spread on table show different behaviour along the rheology test. Values of spread on table follow a quadratic model and RM exhibited an interactive effect with water. RM did not change the hydration process, but above 20% the maximum temperature decreases. The reduction of compressive strength is not constant and depends on the water added. Its variation also follows a quadratic model.

The effects of clay amendment and composting on metal speciation in digested sludge

Sewage sludge usually contains significant heavy metals that may limit its land application. Heavy metals in municipal solid waste have been shown to be less mobile by amendment with bauxite refining residue (red mud) prior to the composting process. In the present research a sequential step extraction was employed to investigate metal speciation (into exchangeable, bound to carbonate, to Mn and Fe oxides, to organic matter and in residue phase) and the effect of red mud on metal speciation in compost of sewage sludge for Cr, Cu, Ni, Pb and Zn. The effect of red mud addition and composting process on metal distribution in sewage sludge compost is significant. Red mud addition generally reduces metal leachability and therefore the potential hazard of releasing metals from sludge compost through adsorption and complexation of the metals on to inorganic components to different extents for the different metals. Red mud cannot desorb, however, metals bound to organic matter in the sludge. The composting process breaks down organic matter in the sludge and may release the heavy metals. The addition of red mud prior to the sludge composting binds the released metals on to the red mud for those not strongly readsorbed by the remaining organics (Cu, Ni and Zn).

The effect of clay amendment on speciation of heavy metals in sewage sludge

When sewage sludge is used as a soil conditioner, heavy metal contamination can limit its application rates. The potential hazard of heavy metals is, however, dependent on the physico-chemical forms of the metals in the sludge and soil. Bauxite refining residue (red mud) has been used to reduce the mobility and availability of heavy metals in municipal solid waste compost. In the present research a sequential step extraction was employed to investigate metal speciation (into exchangeable, bound to carbonate, to Mn & Fe oxides, to organic matter and in residue phase) and the effect of red mud on metal speciation in sewage sludge for Cd, Cr, Cu, Ni, Pb and Zn. The effect of red mud addition on metal distribution in sewage sludge compost was significant. Red mud addition can effectively reduce the metal mobility and the potential hazard of releasing metals from sludge due to the further breakdown of organic matter. Drying of sludge makes heavy metals more available. Red mud addition will be desirable in such a case. Plant available metals (determined by DTPA extraction) are, however, not as effectively reduced except for Pb and Zn.

The effect of clay amendment on speciation of heavy metals in sewage sludge

When sewage sludge is used as a soil conditioner, heavy metal contamination can limit its application rates. The potential hazard of heavy metals is, however, dependent on the physico-chemical forms of the metals in the sludge and soil. Bauxite refining residue (red mud) has been used to reduce the mobility and availability of heavy metals in municipal solid waste compost. In the present research a sequential step extraction was employed to investigate metal speciation (mto exchangeable, bound to carbonate, to Mn & Fe oxides, to organic matter and m residue phase) and the effect of red mud on metal speciation in sewage sludge for Cd, Cr, Cu, Ni, Pb and Zn. The effect of red mud addition on metal distribution in sewage sludge compost was significant Red mud addition can effectively reduce the metal mobility and the potential hazard of releasing metals from sludge due to the further breakdown of organic matter. Drying of sludge makes heavy metals more available. Red mud addition will. be desirable in such a case. Plant available metals (determined by DTPAextraction) are, however, not as effectively reduced except for Pb and Zn.