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By А. V. Aksenov, S. G. Rybkin, А. Y. Senchenko

For gold plants in Russia, it is very complicated and costly to use cyanide leaching for efficient processing of gold refractory ores, where gold is closely associated with sulphide minerals and the significant amount of natural carbonaceous matter present. Oxidative roasting of gold refractory concentrates is a well-known method, making it possible to obtain a high recovery rate of precious metals to a target product. The use of oxidative roasting is limited in general by the expense of capturing and neutralising the harmful components of roasted gas, mainly sulphur (SO2, SO3) and arsenic (As2O3) oxides. This paper addresses testing and development of an optimised technology to process gold refractory gravity and flotation concentrates by means of oxidative roasting which stabilises arsenic as calcium arsenate. The process involves roasting of a gravity or flotation refractory ore concentrate in a mixture with lime and calcium chloride, with a supply of oxygen, and at 600-700°С. During the roasting a carbonaceous matter of the concentrate burns out and sulphide components transform into harmless calcium sulphate (CaSO4) and calcium arsenate (Ca3(AsO4)2), and iron passes into the form of hematite (Fe2O3). After disintegration, the roasting cinder is concentrated on a table to obtain a high-grade gravity concentrate and gravity tailings. The high-grade gravity concentrate is subject to smelting in a mixture with fluxing agents, which results in alloyed gold and slag. The gravity tailings are ground and reported to cyanide leaching. In the case of a flotation concentrate, the roast cinder is ground to minus 30 μm and subject to sorption cyanide leaching. High gold recovery (90-95%) of the target product and environmental safety are typical of the improved technology under consideration. Two national patents were granted for the methods developed to treat refractory concentrates bearing precious metals. Keywords: Gold concentrates, oxidative roasting, cinder, cyanide leaching, smelting, alloyed gold

Jan 1, 2020

By M. R. MacIver, M. Pawlik, H. Alizadeh

Treatment of tailings is an integral component of mineral processing. Tailings with a high clay content are a challenge for the mineral processing industry; e.g. the clay slimes produced from production of phosphate in the mid-western United States and the fine tailings produced from oil sands production in western Canada. Dispersants are a commonly used process aid, but their impact on the structure and settling properties of high clay content tailings is not well understood. The paper describes the changes in composition and bitumen release that occur when mature fine tailings (MFT) are treated with a polymeric dispersant (lignosulfonate.) Synchrotron-source computed tomography (CT) was used to obtain high-resolution 3D images of samples prepared at varying dosages of dispersant. The CT method permits a powerful visualisation of the internal structure and composition of the samples. These insights will enhance our understanding of the structural characteristics of mineral tailings relevant to solid-liquid separation by flocculation and thickening. Keywords: Dewatering, dispersion, dispersants, chemical treatment, computed tomography

Jan 1, 2020

By X. Chen, G. Wang, D. Wan

Computational fluid dynamics have been applied for detailed modelling of particle-bubble collisions. The most accurate approach in the previous work is using the point particle method to treat particles and bubbles. Nevertheless, the sizes of particles and bubbles are generally bigger than the Kolmogorov scale in the high turbulence of the flotation environment, which makes the point particle method inappropriate. This paper describes particle-resolved direct numerical simulation on the collisions between particles (denoted as heavy particles) and bubbles (denoted as light particles) in a homogeneous isotropic turbulent flow field, and a comparison with the point particle method.. A largescale stochastic forcing scheme was implemented within the mesoscopic multiple-relaxation-time LBM approach to maintain turbulence intensity at targetted levels. Both kinematic and dynamic collision kernels were evaluated to study the correlation of total collision events and turbulent kinetic energy (TKE) dissipation rate. The results show that collisions between particles increase with the TKE dissipation rate as radial relative velocities between particles increase with it. In the particle-resolved simulations, the dynamic collision kernels were found to not match with the kinematic collision kernels as in the point particle method. Quantitatively, they were approximately 4 to 10 times smaller than the corresponding dynamic collision kernels. Therefore, it is not reasonable to estimate the kinematic collision kernel in particle-resolved simulations as its rationales are not valid. However, the collision behaviour can still be accounted for by means of the dynamic collision kernel since it is obtained from the direct statistical analysis of the collision events. Keywords: Lattice Boltzmann Method; particle-resolved simulation; multiphase flow; collisions

Jan 1, 2020

By D. V. J. W. Groenewald, T. M. Louw, L. Auret, S. M. Bradshaw, A. V. Cherkaev

Unexpected equipment failures lead to financial losses due to production disruption. Time-based maintenance, based on checks over regular time periods, has been employed to minimise disruption. However, the improvements it can offer are limited as it may lead to unnecessary service of healthy equipment or missed failures occurring between service intervals. Condition-based maintenance (CBM) provides a further improvement to equipment reliability by detecting faults and predicting remaining useful life (RUL) based on equipment health monitoring. Its application in the mineral processing industry is hindered due to the high cost of health monitoring equipment. In this study, two stochastic process models, the adaptive auto-regressive model and the gamma process, are compared in their ability to forecast the degradation state and to provide RUL prediction. The gamma process model was found to be effective in both tasks. Due to its simplicity and minimum hyperparameters requirements, it is proposed to use the gamma process as a baseline for comparison with other models. Keywords: Condition-based maintenance, remaining useful life, slurry pump, adaptive autoregressive mode, gamma process

Jan 1, 2020

By M. Pawlik, N. Ghaffari Touran

The interactions between apatite and hematite were studied through zeta potential and stability experiments, for this paper. The zeta potential measurements were conducted in both background electrolyte and mineral supernatants. The difference in electrokinetic properties of minerals in the presence and absence of supernatant was explained in terms of the dissolution of minerals and the subsequent readsorption of dissolved species at the mineral-water interface. The stability measurements in individual and mixed mineral systems were also performed to identify the extent of interaction between apatite and hematite upon their direct contact. The results from stability measurements in individual and mixed mineral systems indicate that there is an interaction between apatite and hematite. Based on the results, the implications for the apatite-hematite separation process were discussed. Keywords: Apatite, hematite, dissolved ions, stability, zeta potential

Jan 1, 2020

By M. A. Reuter, N. J. Bartie

Metals make modern societies function, and increasingly, various high purity precious and special metals endow sustainability-driving technologies with specific functionalities. These metals become heavily intertwined within products, complicating end-of-life treatment. To counteract the resulting downcycling and potential depletion of scarce resources, maximising both the quantities and qualities of materials recovered during primary extraction and recycling, processes should be a priority in the pursuit of sustainable circular economy. Adopting a process simulation approach; a digital twin for the life cycle of cadmium-telluride solar photovoltaic (CdTe PV) modules was created. The system comprises an integrated metallurgical production system that produces, among others, cadmium, tellurium, selenium, zinc, copper, and lead, all of which are required to manufacture PV modules. System-wide resource efficiency and environmental impacts are assessed using exergy analysis and life cycle assessment, respectively. Simulation of this large and complex product life cycle at a high level of detail allows for the evaluation of potential system-wide effects of various production, recycling and residue exchange scenarios aimed at maximising the sustainability of the entire system. It diminishes the need to make arbitrary choices about allocation methods for the distribution of environmental impacts in multipleoutput production systems. Furthermore, it demonstrates the key importance of metallurgy in achieving circular economy. Keywords: Circular economy, sustainability, simulation, metallurgy, CdTe photovoltaics, life cycle assessment

Jan 1, 2020

By H. Matsuoka, M. Kawata, K. Mitsuhashi, C. Tokoro, T. Kato

Copper sulfide minerals generally have high floatability, but their floatability decreases when surfaces are oxidised under some conditions. Sodium hydrosulfide, NaHS, is known both as an activator and as a depressant for copper minerals. NaHS at low concentrations activates copper oxides by sulfurising surfaces, but at high concentrations depresses copper sulfides by interfering with the adsorption of collectors. In this paper, we applied NaHS to activate oxidised chalcocite and bornite and focused on the conditions of NaHS treatments such as dosages and pH, and the effect of these conditions on the floatability of those minerals. The pure minerals treated with NaHS were analysed using zeta potential analyser and X-ray photoelectron spectroscopy. Analyses indicated that the reactions of NaHS and the products on the mineral surfaces after the reactions (i.e. oxidation, pH change) depended on whether NaHS reacted with copper or iron, and the reactions between NaHS and iron depend on NaHS concentration and pH. Flotation tests using a small column cell were performed with a single pure mineral, and using a Denver-type flotation machine with a copper sulfide ore. The results of each flotation test were utilised to clarify the floatability. The relation between flotation behaviours and analysis results were also discussed. Keywords: Chalcocite, bornite, NaHS activation, flotation, floatability

Jan 1, 2020

By Tian Yingzhong, Guo XIN, Wei Peihe

The intention is to solve a series of problems in the flotation and desiliconisation of complex bauxite; aiming to achieve monomer dissociation of target minerals based on process mineralogy. According to the mineral surface, there are differences in physical and chemical properties and the molecular design theory of flotation agents. Designing the polar and non-polar groups of the bauxite flotation collector to make the reagent group easily combine with the mineral to form a cyclic chelate, will enhance the collection performance, and strengthen the drug selection performance. Developing a new type of positive flotation collector for bauxite with small dosage, strong selectivity and low foam volume. Keywords: Process mineralogy, monomer dissociation, molecular design, new positive flotation collector

Jan 1, 2020

By Z. Tshentu, M. Ngayek, P. Moleko-Boyce

This paper is focused on the development of iridium(IV)-specific quaternary diammonium cations containing electron-donating substituents in the benzyl group of methyl and electron-withdrawing substituents such as triflouromethyl and nitro groups. Quaternary diammonium cations used were tetra- 4-methylbenzyl-1,10-diammonium decane chloride (QuatDMDAMeBnz), tetrabenzyl-1,10- diammoniumdecane chloride (QuatDMDABnz), tetra-3-trifluoromethylbenzyl-1,10- diammoniumdecane chloride (QuatDMDACF3Bnz) and tetra-4-nitrobenzyl-1,10-diammoniumdecane chloride (QuatDMDANO2Bnz). Polyvinylbenzylchloride (PVBC) nanofibres were used as support material, and the functionalised nanofibres were used for separation of Ir(IV) from Rh(III). The sorbent materials were characterised by FTIR and elemental analysis. The efficiency of the quaternary diammonium cations was investigated in a column study under dynamic flow adsorption conditions. Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibres functionalised with diammonium cations showed [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- on the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (3.08 mg/g) < F-QuatDMDABnz (3.39 mg/g) < FQuatDMDACF3Bnz (5.46 mg/g) < F-QuatDMDANO2Bnz (7.10 mg/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibres increased with an increase in the electron-withdrawing nature of the substituent on the quaternising group. The charge delocalising ability of the 4-nitrobenzyl group resulted in the best interaction of the decamethylene diammonium cation with [IrCl6]2-. Keywords: Iridium(IV), rhodium(III), quaternary diammonium, polymer nanofibres, separation

Jan 1, 2020

By S. T. L. Harrison, M. Smart, C. J. Edward

Biooxidation, a biohydrometallurgical process, utilizes a mixed microbial consortium to mediate the dissolution of refractory gold-bearing ores to enhance gold recovery during cyanidation. Recognition of water as a critical resource has prompted improved water management strategies within mining and minerals processing. Bioremediated wastewater from the cyanidation tailings provides a potential water source to supplement the water required for the biooxidation circuit, reducing freshwater extraction. Gold biomining operations have typically been reluctant to recycle this wastewater due to the potential inhibitory effects of cyanide and thiocyanate (SCN-) on the microbial population. Historical process upsets suggest that the microorganisms are sensitive to SCN- concentrations as low as 1 mg/L. However, effective bioremediation processes resulting in effluents with low or negligible SCN- concentrations may allow gold biomining plants the opportunity to recycle available water. Microbial activity as well as alteration in community structure were monitored as a function of increasing SCN- concentration over the range of 0 mg/L to 5 mg/L to investigate the response of the biooxidation community to potential SCN- spikes resulting from upsets in the remediation process. Appropriate microbial growth and ferrous iron oxidation activity with a nominal shift in community structure were observed at SCN- concentrations up to 1 mg/L. Thiocyanate concentrations above 1 mg/L resulted in the complete inhibition of ferrous iron oxidation activity. This was attributed to Leptospirillum ferriphilum’s sensitivity to SCN-. Exposure to a SCN- concentration of 5 mg/L resulted in a lower cell concentration and a significant increase in growth lag time, and the absence of L. ferriphilum from the microbial population. At. caldus and Ap. cupricumulans were still present at 5 mg/L SCN-, although Ap. cupricumulans was unable to oxidise ferrous iron at this SCN- concentration. It was concluded that recycling bioremediated cyanidation tailings wastewater within the biooxidation circuit is feasible; however, to retain process performance, SCN- concentrations should not exceed 1 mg/L. Keywords: Biooxidation, thiocyanate, water recycling, community structure

Jan 1, 2020

By S. C. Maji, U. S. Chattopadyay, S. Chaudhuri, T. Gouri Charan

India is devoid of coking coal resources, which is a vital raw material for coke making. As a result it has to import about 80% coking coal for steel making. Indian National Steel Policy, 2017 has envisaged crude steel production around 300 million tonnes Mt) by the year 2030-31 and forecasts coking coal demand of 161 Mtpa (million tonnes per annum). One way of improving the indigenous resources is to study the performance of existing washeries and to improve the clean coal recovery by adopting suitable technology. A study was carried out, mainly to focus on the fine coal circuit of an existing coking coal washery, to generate the desired quality of clean coal. The operating coking coal washery being studied is presently feeding coal from nine different sources with varying feed ash contents. The coal fines varied in ash content ranging from 19.5% - 43.6%. For treating the coal fines, the washery has operated a spiral for the past few years. Performance studies were carried out, and it was found that the spiral is not efficient in recovering the cleans. Detailed investigations were carried out on the coal fines using flotation techniques, and it was found that to achieve a low ash clean coal, the froth flotation is a much better beneficiation option than a spiral, The studies showed that the recovery of clean coal through a spiral is 67.7% at ash content of 27.0%, while flotation tests showed a recovery of 68.1% at 16.5% ash content. Keywords: Coking coal washery, near gravity material, spiral washer, froth flotation

Jan 1, 2020

By Y. Fu, C. Aldrich

This study investigates the use of dense convolutional neural networks to estimate bubble size distributions in flotation froths. 20 videographically captured images of froths from an industrial platinum flotation plant in South Africa were labelled semantically with an image annotation tool, LabelMe (https://github.com/wkentaro/labelme). As a result, pixels in the images could be categorized into three classes, namely ‘bubbles’ (class 0), ‘bubble boundaries’ (class 1) and ‘background’ (class 2). A U-net architecture with a ResNet34 backbone was trained to segment the images via classification of the pixels in the images. 5 of the 20 images were used to validate the performance of the neural network. Explicit inclusion of the bubble boundaries as a class proved to be significantly more effective than training the network with two classes only (i.e. bubbles and background). However, the thickness of the boundary layer regions were critical. If too thin, it was difficult to distinguish between some contiguous bubbles and if too thick, some fine bubbles may not be identified. The results were promising, although there is still significant scope for improvement, among other by making use of more images for training and validation. Keywords: Flotation Froths, Convolutional Neural Networks, Deep Learning, Bubble size Analysis

Jan 1, 2020

By D White, L. Lorenzen

Sampling and metallurgical testwork during various phases of engineering studies is of paramount importance for a robust processing plant design. When developing a process flowsheet, risks in achieving desirable financial outcomes are minimised by ensuring that appropriate sampling and adequate metallurgical testwork support the engineering and cost estimation at each phase of project development. The quality and type of samples used for metallurgical testwork are just as important as the metallurgical testwork itself. The key characteristic required of any sample is that it represents some defined portion of a mineral deposit. Representivity should consider the spatial orientation, lithology, alteration, degree of oxidation, mineralogy, and competency of the ore such as hardness and abrasiveness. Statistically representative sampling procedures and an appropriate metallurgical testwork program should be designed to bring metallurgical understanding up to feasibility study standard and to give a basis for process plant design. The authors have observed that the quality of sampling and quantity of metallurgical testwork carried out during the various phases of engineering studies are often insufficient to truly support a robust plant design. Some designs are based on benchmarks of apparently similar ore bodies or rely on buoyant metal prices supporting cash flows until rectifications can be implemented. The paper will discuss important aspects of sampling and testwork required for engineering studies in designing process plants. Keywords: Sampling, metallurgical testwork, studies, design

Jan 1, 2020

By Y. Qin, L. Han, P. Gao, Y. Han, Y. Lia

In the present study, an innovative comminution technology of high-voltage pulse discharge was proposed for galena to weaken the mechanical property. The results of pre-treatment experiments indicated that the optimal operating conditions of spherical gap spacing 25 mm, pulse numbers 120, and loading voltage 25 kV were obtained, where the relative grindability of pretreated products was improved significantly, although with the prolonging of grinding time, the superiority of high-voltage electric pulses was gradually weakened. The galena ores were subjected to a high-voltage pulse discharge, and then the crack generating along the boundary between galena and gangue was observed under an optical microscope, and the surface burning which appeared in the ores. The scanning electron microscope (SEM) results indicated that the pretreated products were in a state of melting and then condensation, accompanied by some pore formation. Pulsed discharge pre-treatment not only produced more micro-cracks and cracks in the sample but also extended the original crack. Keywords: High-voltage pulse discharge; galena; relative grindability; micro-crack

Jan 1, 2020

By E. Saari, B. Musuku, K. Jansson

The quality of the concentrator plant process water is crucial for high performing mineral flotation circuits. Significant metal recovery and concentrate grade losses have been noticed particularly in more closed water loops. The recovery and quality losses have started to emerge mainly with decreased freshwater usage and because of changes in tailings management towards tailings thickening, paste, or dry stacking. These changes result in shorter, closed water loops with a rapid build-up of harmful components with negative impact on the beneficiation process. Consequently, water quality has a direct link to decreased product value and sales returns. Complete cleaning or water blending might not be the right way to achieve high recovery and high-quality products. Instead, the key is to understand what kind of water qualities are needed for the flotation of specific minerals. In this study harmful substances in various plant water streams were removed and/or modified by pilot-scale dissolved air flotation. Batch-scale mineral flotation tests with the untreated and treated water were then performed by using fresh ore samples and the plant’s own laboratory flotation procedure. The results indicate that because of dissolved air flotation, the mineral flotation recoveries were enhanced by 1‒3.3%. Keywords: Mineral recovery, metal recovery, mineral quality, process water, concentrator, beneficiation, mineral processing, flotation, process water treatment

Jan 1, 2020

By M. Bryson, J. Taguta

The Prieska deposit, mined between 1971 and 1991, is one of the world’s top thirty volcanogenic massive sulphide (VMS) base metal deposits. The Prieska Copper Mine in the Northern Cape Province was closed by Anglovaal when underground mining had extended to depths which did not allow for safe and economic extraction of the deposit at the time. The mine has a recorded historical production of over 1 Mt of zinc and 430 k tonnes of copper from 46.8 Mt of milled sulphide ore, achieving life-ofmine metal recoveries of 85% for copper and 84% for zinc into high quality concentrates (refer ORN ASX release 15 Nov 2019). Orion Minerals Ltd is currently investigating the feasibility of developing a new mine in the footprint of the historical Prieska Copper Mine, using the extensive remaining infrastructure, with the intent of extracting the unmined zinc-copper mineralisation from the Prieska deposit. This paper reports results on the flowsheet development philosophy on the hypogene ore, and challenges encountered in the process. This study initially failed to replicate historic copper and zinc recoveries employing the historic production flowsheet and reagent conditions unmodified on bench scale, as the copper and zinc were co-floating. Flowsheet modifications were therefore made to improve differential flotation and recovery, resulting in achieving comparable saleable products and recoveries from processing the hypogene ore on bench scale. Flotation variability test work on the hypogene ore focused on the use of the original flotation procedure and reagent suite using a sodium cyanide-zinc sulphate depressant system on the copper circuit, and it generated a saleable copper product of 20-26% Cu grade at 80-86% recovery. The zinc circuit generated a saleable zinc product grading at 48-55% Zn at 80-94% recoveries. Some zinc losses were due to the deportment of some zinc in sauconite. It is recommended that further test work may further improve the copper grades and recoveries. Keywords: Prieska, flotation, hypogene ore, flowsheet development, sulphide flotation, reagents

Jan 1, 2020

By C. van Buuren, R. F. Sandenbergh, P. J. Pieterse

Gold extraction from double refractory ores using conventional cyanidation has proved challenging due to the presence of carbon within the ore. Carbon particles may adsorb leached gold resulting in gold losses to tailings, i.e. preg-robbing the gold. Some of the preg-robbed gold may be recovered by the application of the HiTeCC process on CIL tailings. The process developed by Metso Outotec involves caustic conditioning of the tailings followed by high temperature desorption and simultaneous adsorption onto virgin activated carbon of the aurodicyanide. The aim of this paper was to develop a model for the HiTeCC process which could be used to support design and optimisation of the process, based on the adsorption characteristics of the preg-robbing and activated carbons. It was found that accurate experimental isotherms can be used to predict the behaviour of preg-robbing adsorbents. Comparing the sorption isotherms for preg-robbing ores and activated carbon indicated similar dependencies on temperature and ionic composition. Applying boundary layer diffusion models coupled with experimentally determined isotherms for preg-robbing ore and activated carbon, the HiTeCC process was successfully simulated at experimental and plant scale. Gold recovery of the HiTeCC process is most sensitive to the temperature of desorption and gold loading of the activated carbon, with increased temperature improving recovery. The gold loading of the activated carbon in the process should always be maintained lower than that of the normalised pregrobbing carbon gold loading to ensure favourable conditions for adsorption onto the activated carbon. Caustic conditioning stabilises adsorption and is therefore not necessary during the desorption stages of the process, but potentially improves recovery during adsorption. Keywords: Preg-robbing, refractory gold ores, HiTeCC, aurodicyanide

Jan 1, 2020

By F. Diot, S. K. Tripathy, L. O. Filippov, I. Filippova

Among different pre-treatment methods, a high voltage electric pulse was recently developed and is gaining popularity due to multi-benefits such as pre-weakening along the grain boundaries, as well as size reduction to improve the liberation characteristics. In this paper, the pre-treatment using high voltage electric pulse of lithium-bearing granite ore was studied to understand the morphology through texture, as well as the friability of the particles. To understand the phenomena, SELFRAG, a laboratory facility used for generating high voltage electric pulse and key operating variables were varied. The role of applied voltage (94.5-195.5 kV), number pulse (3-87), and the frequency of pulse (1.3-4.7 Hz) was varied to understand the liberation characteristics as well as energy consumption. Characterisation tools such as optical, and electron microscopy were used to describe the pre-weakening phenomena through textural features. Further, the energy required to break the particle to finer sizes as well as friability were determined and described. Keywords: Pre-treatment, high voltage electric pulse, lithium, liberation, grinding

Jan 1, 2020

By D. Minson, G. Lindner, S. Miskovic

Thickening is an essential process in the mining industry and currently one of the most costeffective technologies for recovering water from tailings streams. Improved performance of thickeners can lead to significant energy savings, and increased recovery of water close to the mill. Its performance is directly affected by the rheological properties of slurry at the raking zone. To further understand the dynamics of slurry inside thickeners, a multiphase particle-in-cell method (MP-PIC), is used to investigate its behaviour on a sliding channel. Parameters like particle-size distribution (PSD), rheological properties, and domain discretisation were benchmarked to study its influence on highly dense flows. The slurry concentration by weight of the samples ranged between 60 to 70% of solids by mass, under which conditions it is known to behave like a non-newtonian fluid. An experimental flume, 0.2 m wide and 2 m long, was used for validation under different angles and slurry composition. Visual analysis of the slurry height and shape, as well as velocity measurements, were compared with numerical data. The preliminary results show the ability of MP-PIC method to represent different types of highly dense flows, while still being computationally affordable and practical for industrial use. Keywords: High density thickener, CFD, MP-PIC, multiphase-flow

Jan 1, 2020

By X. H. Li, Q. Zhang, X. Fei

Bauxite residue known as red mud (RM) is a by-product produced in massive quantities during alumina production by the Bayer process with a utilisation rate of less than 5%. A large amount of RM accumulated and produced continuously has had a seriously adverse impact on the surrounding ecological environment. The application of RM in building materials is considered to be the most effective and thorough way to make RM harmless and recycle resources for the reason that adding RM to concrete as a mineral admixture could not only consume a lot of RM, but also save cement and other energy-consuming industrial products. In this paper, the adaptability to cement and aggregate of RM was studied. The results showed that the compressive strength and flexural strength of concrete using ordinary Portland cement, slag Portland cement or fly ash Portland cement as cementing material showed different trends with the increase of the amount of RM. The influence rules of RM on the compressive strength of Portland cement, slag Portland cement and fly ash Portland cement concrete were similar, whether for silicate aggregate or carbonate aggregate. RM has a negative correlation to the flexural strength of silicate aggregate-ordinary Portland cement concrete, but a positive correlation to silicate aggregate-slag Portland cement, silicate aggregate-fly ash Portland Cement. RM promoted the formation of calcium carbonate crystals and inhibited the formation of ettringite and calcium hydroxide crystals in the matrix while ordinary Portland cement, Portland cement and fly ash Portland cement were used as cementing materials. This study provided support for the use of RM in concrete, the reduction of solid waste storage, and the saving of high energy consumption cement as well. Keywords: Red mud, cement, aggregate, adaptability, mechanical properties, mineral composition

Jan 1, 2020