Bulk Utilization of Red Mud in Geopolymer Based Products

Red mud is the main by-product of the production of alumina according to the Bayer process. It is a highly alkaline, brick-red suspension. It is characterized by a diversity of chemical and mineralogical composition. The main elements in red mud are Fe, Al, Si, Ti, Na, Ca, and they account for about 90% of the mass of the mud. In addition to these, a large number of other components can be found in minor quantities. Most elements are present in the form of oxides and hydroxides in various minerals. The demand for aluminum is constantly growing, the amount of discharged red mud is continually increasing. The annual amount of red mud produced globally, is already estimated at 200 million tons, and further growth is expected. High production rates and only minimal and sporadic utilization of red mud have resulted in the accumulation of large quantities of disposed red mud, so that the global red mud stockpile is estimated at more than 5 billion tons. In addition to financial costs, the disposal of red mud also poses certain risks to the environment. For this reason, the safe disposal of red mud is one of the main concerns of all alumina producers. Reducing the amount of red mud that is disposed of, and consequently reducing the risks and costs, requires constant efforts to find procedures for its valorization. The possibilities of valorization of red mud are diverse. It has been shown that red mud can be successfully used in many areas, such as construction, metallurgy, chemical industry, environmental protection, agriculture, etc. Analyzing the patents related to the use of red mud, it can be observed that 12% of the patents refer to the wastewater and waste treatment. The heterogeneous composition of red mud indicates the possibility of its application as a composite sorbent. The application of red mud as a low-cost sorbent has been extensively investigated, and favorable results have been obtained in the sorption of metals and metalloids, radionuclides, phosphates, nitrates, fluorides, dyes and phenols, etc. In order to increase the sorption capacity of red mud and obtain a more environmentally friendly sorbent, various treatment techniques are applied. These treatment techniques can modify the physical and chemical properties, which can lead to a change in alkalinity, specific surface area and porosity, a change in the number of active sorption sites, and its surface charge can also be changed. Modifications of red mud to remove various types of pollutants have shown promising results. Many studies have shown that red mud can be used as an efficient and low-cost sorbent for removing heavy metal cations from solutions, such as Pb2+, Cu2+, Zn2+ , Cd2+, Ni2+, Co2+, Sr2+, Cs2+, as well as for the treatment of waste water and leachate from landfills and mines. During the removal of heavy metals from solutions using red mud, various mass transfer phenomena occur: physical and chemical adsorption, surface precipitation, co-precipitation, ion exchange, precipitation, complexation, hydration, dissolution, etc. Despite the numerous possibilities of application and the benefits that arise from it, we still do not have a significant utilization of red mud.

Proposal for resources, utilization and processes of red mud in India — A review

Environmental assessment, management and utilization of red mud in China

Chapter 19 - Methods for Utilization of Red Mud and Its Management

Red mud is a solid waste generated at aluminum production. Currently in Brazil this sub-product does not receive appropriate destination and is stored in deforested areas. Annually, approximately 11 million tons of red mud are generated just in Brazil and represent a great imminent risk of pollution and contamination. The large amount of red mud generated by aluminum industry has motivated researchers to develop methods for using this residue. Studies show the possibility of using red mud compound ceramic materials, however, there is a lack of research in other areas, such as applied to pavements. On the other hand, more than 50% of Brazilian highways are in poor condition, especially in the north, where high temperatures favor permanent deformation in pavement. In this scenario, this paper compares permanent deformation results of asphalt mixtures composed by 7% filler, varying the type of filler (red mus and stone powder). For this, red mud characterization tests were performed. The results showed that red mud can improve the resistence of asphalt mixtures.

Bayer red mud is a strong alkaline solid waste discharged during alumina production. Due to large emissions and strong alkalinity, red mud is now mostly dammed or buried, which not only occupies huge land but also contaminates the surrounding ecosystem, causing the risk of collapse and landslide. In addition to its overall utilization in building materials, agriculture, the environment, and the chemical industry, red mud also contains valuable metals such as sodium, aluminum, iron, titanium, and scandium and is considered to be an important secondary resource. In this paper, the physicochemical properties and hazards of red mud are first introduced, and then, the overall utilization of red mud is summarized. Then, the latest research progress on the separation and extraction of valuable metals from red mud is reviewed in detail and a new comprehensive utilization method is recommended and evaluated. This paper also provides suggestions for the future development direction of the comprehensive utilization technology of red mud.

Transportation is the main means of communication for trade, commerce, and many other purposes. In transportation, the roadway plays a crucial role as it is having more advantages compared to other forms of transportation. In India, the maximum length of the highway network is of bituminous pavements. Bituminous pavement is a general type of bitumen mixture with recommended changes if any. Generally, the bituminous pavement has some failures such as potholes, rutting, cracking, shoving, etc, the major cause of the cracking, shoving, rutting is the lack of adhesion in the bitumen and heavy load vehicles. To solve this issue, we are going to replace the filler material with Bauxite residue in the incremental method from 0% to 25%. This study investigated the strength of the marshall stability specimen. At present NHAI is taking an initiative to construct rigid pavements for highways. Most of the rigid pavements are constructed with cement concrete. It is not always possible to supply cement because of its limited production there is a necessity to go for alternatives. Bauxite residue, also known as red mud, is a byproduct of aluminum production during bauxite processing. In India, this waste is often improperly managed, with large quantities being stored in deforested areas. Each year, around 22 million tons of red mud are produced in India alone, contributing to a global total of approximately 119 million tons annually [1]. By using this red mud in bitumen pavement, we are expecting to improve the marshal stability of the pavement and reduce the cost of the construction. By using this material in rigid pavements, we are expecting to improve the strength, durability of pavement and reduce the cost of construction and environmental pollution. Keywords: Bauxite residue powder (red mud), bitumen pavements, marshal stability, rigid pavements, compressive strength, flexural strength.

Study on the utilization of red mud (bauxite waste) as a supplementary cementitious material: Pathway to attaining sustainable development goals

Performance evaluation of red mud as a construction material – A review

Utilization of red mud: Recovery of iron and aluminum by enhanced separation based on a new combined roasting process.

Bauxite residue is the waste generated during alumina production by Bayer's process. The amount of bauxite residue (40-50 wt%) generated depends on the quality of bauxite ore used for the processing. High alkalinity and high caustic content in bauxite residue causes environmental risk for fertile soil and ground water contamination. The caustic (NaOH) content in bauxite residue leads to human health risks, like dermal problems and irritation to eyes. Moreover, disposal of bauxite residue requires a large area; such problems can only be minimised by utilising bauxite residue effectively. For two decades, bauxite residue has been used as a binder in cement industries and filler/reinforcement for composite materials in the automobile industry. Valuable metals and oxides, like alumina (Al2O3), titanium oxide (TiO2) and iron oxide Fe2O3, were extracted from bauxite residue to reduce waste. Bauxite residue was utilised in construction and structure industries to make geopolymers. It was also used in the making of glass-ceramics and a coating material. Recently bauxite residue has been utilised to extract rare earth elements like scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd) and dysprosium (Dy). In this review article, the mineralogical characteristics of bauxite residue are summarised and current progresses on utilisation of bauxite residue in different fields of science and engineering are presented in detail.

This study investigates the feasibility of using bauxite residue (BR) as supplementary cementitious material (SCM) for the cement and concrete industry. It is shown from pastes of BR and calcium hydroxide, that BR is highly pozzolanic in nature. The early hydration of cement pastes with BR is accelerated while long-term strength is reduced probably due to the alkaline nature of BR. To be used as cement replacement material in concrete, attempts have been made to reduce the alkali content of BR, in particular to reduce the chance of alkali-aggregate reactions. Co-calcination of BR with kaolin or washing and cooking of BR with calcium hydroxide or calcium hydroxide and gypsum resulted in considerable reduction of alkali content; up to 75%. At the same time the reactivity of the BR was reduced but still being higher compared to fly ash already used in the cement industry.

Enhanced and environment-friendly chemical looping gasification of crop straw using red mud as a sinter-resistant oxygen carrier

An experimental investigation of utilizing waste Red Mud in soil grouting

Minerals engineering conferences