Tungsten Mining Waste Mud Research Articles

Rheology, Mechanical Properties and Porosity of Ternary Alkali-Activated Binders Based on Mining Mud Waste with Waste Glass and Metakaolin

Alkali-activated materials have the potential to replace Portland cement in certain applications. To better understand these binders’ properties, it is relevant to study their rheological behaviour at early ages, like in the case of Portland cement paste. There are already many studies on the rheological behaviour of these materials in the available literature, using fly ash, metakaolin, and ground granulated blast furnace slag as precursors. However, this study discusses the rheological behaviour, mechanical properties, and porosity of ternary alkali-activated binders based on mining mud waste, waste glass, and metakaolin. The precursor consisted of a volume mix of 70% of tungsten mining waste mud, 15% glass waste, and 15% of metakaolin. The activator was a combination of sodium hydroxide and sodium silicate solution. Five activator/precursor (A/P) ratios (0.37, 0.38, 0.39, 0.40, and 0.4) were studied. The result showed that the activator/precursor ratio affects the rheology of paste and their rheological behaviour fit the Bingham model. The relative yield stress (g) and plastic viscosity (h) increased inversely with the A/P ratio, while the workability increased proportionally. Furthermore, some empirical models are proposed to describe the characteristic of yield stress: plastic viscosity and spread diameter versus the A/P ratio and time with a correlation between the rheological parameters and the spread diameter. The increase in A/P ratio has also followed a decrease in compressive strength in all tested samples for all the ages. As expected, an increase of the porosity accompanied the increase of the A/P ratio.

Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties

The valorization and reusing of mining waste has been widely studied in recent years. Research has demonstrated that there is great potential for reusing mining waste for construction applications. This work experimentally investigated the strength development, pore structure, and microstructure of a binary alkali-activated binder. This is based on tungsten mining waste mud (TMWM) and electric-arc-furnace slag (EAF-Slag) using different proportions of TMWM (10, 20, 30, 40, and 50 vt.%). The precursors were activated using sodium silicate (Na2SiO3) and potassium hydroxide (KOH 8M) as alkaline activator solution with solid:liquid weight ratio = 3. Pastes were used to assess the compressive strength of the blended binder and their microstructure. The reaction products were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infra-red (FT-IR) spectroscopy, while the porosity and the pores size properties were examined by mercury intrusion porosimetry (MIP). The results show that the partial replacement of TMWM with EAF-Slag exhibited better mechanical properties than the 100TM-AAB. A maximum strength value of 20.1 MPa was obtained in the binary-AAB sample prepared with 50 vt.% TMWM and EAF-Slag. The pastes that contained a higher dosage of EAF-Slag became more compact with lower porosity and finer pore-size distribution. In addition, the results obtained by SEM-EDS confirmed the formation of different types of reaction products in the 100TM-AAB, 100FS-AAB, and the binary-AABs mixtures such as N-A-S-H, C-A-S-H and (N, C)-A-S-H gels frameworks in the system as the major elements detected are Si, Al, Ca, and Na.

Development of Porous Tungsten Mud Waste-based Alkali-activated Foams with Low Thermal Conductivity

Aim of this study was to produce alkali-activated foams with low thermal conductivity. Different precursors’ maximum particles sizes of 150μm, 300μm, and 500μm using a blend of 70% tungsten mining waste mud (TWM), 20% grounded waste glass (WG) and 10 % metakaolin (MK) with sodium silicate (SS) and sodium hydroxide (SH) as original material. Aluminium powder (Al) was used as a blowing agent and added first to the dry mix by changing content from 0.1g to 0.5g. Precursors and activators were mixed together to produce a homogeneous mixture, which was placed into a mould (100x200x60 mm3), and cured in the oven at 60∘C for 24 hours. The effect on foaming properties of different precursors maximum particles sizes were studied. The AAFs exhibited 28 day compressive strengths ranging from 2.28 to 16.1 MPa with the different densities from 913 to 1647 kg/m3 achieved through alteration of the foaming content. The thermal conductivity of AAFs was in the range 0.21– 0.33 W/m*K. Open celled hardened of the AAFs with 0.5g Al shows a high porosity of 58% with the mix made with 500μm. Therefore, tungsten mining waste-based alkali-activated foams shows a promise as thermal insulation material in some situations.

The Effect of the Activator/Precursor Ratio on the Rheological Properties of the Alkali-activated Mining Waste Mud Paste

To determine the properties of paste, mortar or concrete, it is necessary to understand its rheological behaviour first. This study discusses the effect of the activator/precursor ratio on the rheological properties of the alkali-activated paste. The pastes consisted of a mix of 70 % of tungsten mining waste mud, 15% waste glass and 15% of metakaolin. This mix was activated by combining sodium hydroxide and sodium silicate. Five activator/precursor (a/p) ratios were studied: 0.37, 0.38, 0.39, 0.40 and 0.41. The result obtained shows that the rheology of the pastes is affected by the activator/precursor ratio. The rheological behaviour of the paste fits the Bingham model. The yield stress (τ0) and plastic viscosity (μ) increase inversely with the activator/precursor ratio (e.g. a/p=0.37 gives τ0=84.19 and μ=0.4185; a/p=0.41 gives τ0=30.389 and μ=0.2937). The workability increases proportionally with the activator/precursor ratio (e.g. a/p=0.37 gives a slump=133 mm; a/p=0.41 gives a slump=158 mm). The compressive strength decreases when the activator/precursor ratio increases (e.g. at 28 days for a/p=0.37, the compressive strength was 19.6 MPa; for a/p=0.41, the compressive strength was 13 MPa). Finally, the ideal ratios were 0.38 and 0.39.

Strength Development and Pore Structure Characterisation of Binary Alkali-activated Binder Based on Tungsten Mining Waste

The mineralogical properties of tungsten mining waste mud (TMWM) make its valorisation and re-usage as an alumino-silicate source material to produce an alkali-activated binder without calcination is a challenge. Moreover, the dissolution of silicate and alumina species from TMWM is very slow. Despite the crystallinity of TMWM, this study demonstrates that its combination with other sources of the alumino-silicate source was the materials–such as red clay brick waste(RCBW),ground granulated blast furnace slag (GGBFS) and electric arc furnace slag (EAFS) – improved the compressive strength and the pore structure of the alkali-activated matrix.Thecombinedprecursors (90 vt.%TMWM+10 vt.%RCBW, 90 vt.%TMWM+10 vt.%GGBFS, and 90 vt.%TMWM+10 vt.%EAFS) were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3(66.6wt.%sodiumsilicatecombined with 33.33 wt.% of NaOH 10M). The results show that the compressive strength increased from11.23MPa at 28 days to reach 24.98MPawhentheTMWMwaspartially replacedby10vt.%RCBW. In addition,this study shows that the interconnected porosity decreased where the critical pore size was reduced from 21.28 µm to 0.55 µm for the tungsten mining waste-based alkali-activated binder and the binary alkali-activated binder based on TMWM and RCBW.
 Keywords: Mining Waste, Alkali-activated, Microstructure, MIP, Metakaolin

Preliminary Study of the Rheological and Mechanical Properties of Alkali-activated Concrete Based on Tungsten Mining Waste Mud

The rheological properties of Portland cement (PC) concrete have been extensively studied and compared with those of alkali-activated concrete (AAC). This study discusses the effect of the liquid to solid ratio on the rheological and mechanical properties of AAM concrete, based on mining waste mud as the binder phase, and compares them with those of Portland cement concrete (PCC). The AAM concrete studied is a mix of coarse aggregate 6/15, two types of sand (finer and coarse sand), and a precursor. The precursor is a mix of 70% tungsten mining waste mud, 15% waste glass and 15% metakaolin. This mix was activated by a combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) and the PCC was a mix of the same aggregate but with cement as binder and water as a liquid. The activator/precursor ratio was studied 0.5, 0.52, 0.54, 0.56 and 0.58. The results obtained show a similar rheological behaviour between AAC and PCC, the workability affected by L/S increases with the increasing ratio L/S in AAC and for L/S=0.5 slump was 6 cm and was 16 cm for L/S =0.58. Regarding the mechanical properties, the results obtained in 7 days showed similar performance in AAC and PCC. The compressive strength also decreases with the increasing of L/S, in AAC with L/S=0.5 the compressive strength was 15.9 MPa and for L/S =0.58 was 10.5.
 Keywords: Tungsten mining waste, Rheology, Mechanical properties, Portland cement, alkali-activated concrete

Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

In this preliminary study, the effect of the pre-drying stage, water immersion, carbonation curing cycles, and/or drying stage on carbonation curing of magnesium oxide-rich powder (MRP) was investigated. In addition, a blend of tungsten mining waste mud (TMWM) with MRP was also evaluated. The MRP and TMWM used have maximum grain sizes of 125 μm. The cement pastes were produced with 0 and 50 of TMWM weight percentage. The specimens were compacted into cylindric moulds (∅ = 20 mm; h = 40 mm) under 30 MPa and, subsequently, submitted to five different processes of curing involving a pre-drying stage before carbonation, rapid water immersion cycles, additional drying periods, and different carbonation curing periods. The atmosphere of the pressurized carbonation curing chamber was controlled to provide a CO2 concentration of > 99%, the partial pressure of 1 bar and temperature of 60°C. The influence of the curing processes on the compressive strength of each mix was determined 12 hours after the carbonation curing period. This study demonstrates that the water content during the curing process plays an important role in the increase of the hardening process and on the compressive strength.
 Keywords: Carbonation curing, magnesium oxide, mining waste, curing processes, magnesium-based cement

Development of Alkali-activated Foamed Lightweight Mortar Tungsten Mining Waste Mud-based Incorporating Expanded Cork

In this study, an Alkali-activation of tungsten mining waste mud (TMWM) was combined with aluminium powder (Al) as a blowing agent (gas foaming method). The synthesis of inorganic alkali-activated foamed mortar (AA-FM) and alkali-activated lightweight foamed mortar (AALW-FM) was achieved by incorporating expanded granulated cork (EGC) and one type of river sand < 2 mm. Al powder was added first to the dry mix with the mass used varying from 0.1 g to 0.5 g. Precursors and activators were included to produce a homogeneous mixture, which was placed into a mould (100x100x60 mm3), and cured in the oven at 60° C for 24 hours. The influence of two main parameters (Al powder contents and cork particles) on the AA-FM and AALW-FM properties (compressive strength, density, expansion volume and pore size distribution) were investigated. The compressive strength of the foams in the case of highly porous structures of the AALW-FM and AA-FM achieved 4.1MPa and 13.2MPa respectively, for samples with a larger amount of Al powder (0.5g). Open celled hardened of the AALW-FM and AA-FM with 0.5g Al shows a high porosity of 40% and 81% respectively. Therefore, tungsten mining waste-based alkali-activated foams shows potential as a thermal insulation material in certain situations.
 Keywords: Tungsten mining waste, Alkali-activated, Foamed Materials

Effect of activators on hybrid alkaline binder based on tungsten mining waste and ground granulated blast furnace slag

This article illustrates the effects of different combinations of alkaline activator solutions (sodium silicate “SS”, sodium hydroxide, potassium hydroxide and dissolved waste glass powder in sodium hydroxide) as well as their concentrations and the Solid/Liquid ratios on the compressive strength development, and the microstructure of hybrid alkaline binder. The current study used a combination of tungsten mining waste mud (TMWM) (90 vt.%) and ground granulated blast furnace slag (GGBFS) (10 vt.%) as precursors. The obtained hybrid alkaline binder specimens were submitted by compressive strength tests. It was found out that the alkaline activator (KOH when mixed with SS) improves the compressive strength of the hybrid alkaline binders compared to the alkaline activator (NaOH mixed with SS), which depends on the presence of alkali metal K+ and Na+ cations. Moreover, the samples prepared by the alkaline activator (dissolved waste glass powder in NaOH mixed with SS) giving the highest compressive strengthof about 32.8 MPa at 28 days. From the results of XRD, TGA-DTGA, FTIR analyses, and the obtained microstructures of the hybrid alkaline binders it indicates the existence of a different reaction product formed during the alkaline activation such as C-S-H, N-A-S-H, C-A-S-H, and K-A-S-H type cementitious gels. In addition to these conventional gels, there was a formation of a complex mixture of (C, M)-A-S-H cementitious gels were (M = K, Na). The pore structure of hybrid alkaline binder was evaluated through mercury intrusion porosimetry (MIP). The pore structure of specimens was characterised by the total porosity, average pore diameter, pore size distribution as well as characteristic pore sizes. The MIP results indicate that the type of alkaline activators, solid/liquid ratios and the alkaline activators’ concentration have a specific impact on all characteristics of the pore structure of all the hybrid alkaline binders. Finally, the cost impact on the compressive strength for different activators was also analysed.

Design of alkali-activated aluminium powder foamed materials for precursors with different particle sizes

Alkali-activated foams (AAFs) were produced using three different precursors with maximum particle sizes of (150, 300, and 500 µm), together with a blend of 70% tungsten mining waste mud (TWM), 20% waste glass (WG), and 10% metakaolin (MK). Aluminium powder (Al) was used as a foaming agent and added first to the dry powders with the mass used varying from 0.1 g to 0.5 g. The effect of using different precursor particle sizes on the AAFs compressive strength, volume expansion and pore size distribution was studied. The results obtained show that by reducing the particle size of the precursor, the foamed materials’ compressive strength increases.

Elastic modulus and stress-strain curve analysis of a tungsten mine waste alkali-activated concrete

In the paper the compressive strength, the elastic modulus and the stress-strain curve of an alkaliactivated concrete were studied. A tungsten mine waste mud (TMWM), aggregate (also from the tungsten mine), glass waste and metakaolin were used as raw materials. Sodium silicate and sodium hydroxide were used as activators. First, TMWM chemical composition was determined by scanning electron microscopyenergy dispersive spectroscopy (SEM-EDS). The maximum particle size was 18mm. Two cubes with side dimension of 15cm were prepared from the mixture. Samples were cured at 60°C for 24 hours. A concrete mixer, vibration table and an oven were used in the process. After the curing process, cubes were cut into seven prisms and one cube with the dimensions 15x7.4x7.4cm and 7.4cm respectively. After 28 days, the laboratory tests were performed. During the compressive strength tests, the displacements were also recorded which allowed drawing the stress-strain curve of the samples. The compressive strength ranged from 17.27 to 28.84MPa. The elastic modulus was calculated by four different standards: ASTM, LNEC and European standard. The elastic modulus ranged from 2.48 to 7.49GPa what showed that the material is more elastic than ordinary Portland cement concrete.

Effects of EAF-Slag on alkali-activation of tungsten mining waste: mechanical properties

The mechanical properties of alkali-activated binders based on blends of tungsten mining waste mud (TMWM) and electric arc furnace slag (EAF-S) were investigated. The synthesis of alkali-activated binders was conducted at 60°C for 24 h with different TMWM/EAF-Slag ratios (90:10, 80:20, 70:30, 60:40, and 50:50 vt.%). Using sodium hydroxide (SH) and sodium silicate (SS) solutions as alkaline activators with ratio solid/liquid 4 by unit of volume, and the sodium silicate to NaOH (SS:SH) ratio of 2:1. The X-ray Diffraction (XRD), mercury intrusion porosimetry (MIP) were determined. The different percentages of the precursors and the alkaline activators were optimised to produce paste samples. The compressive strength of samples with 10 vt.% EAF-Slag was close to 20.7 MPa after 90 curing days. The mechanical properties were further increased up to 30 MPa by increasing the percentage of EAF-Slag to 50 vt.%. This demonstrates a new potential for re-using waste material for various constructional applications.

Red clay brick and tungsten mining waste-based alkali-activated binder: Microstructural and mechanical properties

This paper illustrates the study on the synthesis of alkali-activated binders based on the combination of tungsten mining waste mud (TMWM) with red clay brick waste (RCBW) with the use of sodium hydroxide (SH) and sodium silicate (SS) solution as alkaline activators; with a solid/liquid weight ratio = 3, and the SS:SH weight ratio = 2:1. The synthesis of TMWM-RCBW alkali-activated binders was conducted at 60 ± 2 °C curing temperature for 24 h, by using different TMWM and RCBW volume proportions, namely (90:10, 80:20, 70:30, 60:40 and 50:50 vt.%). Mineralogical and microstructural characterisation was carried out by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), mercury intrusion porosimetry (MIP) and Fourier transform infrared spectroscopy (FT-IR). The FT-IR spectra and EDX analysis demonstrated that the higher dosage of RCBW content in the samples, the higher the formation of N–A–S–H and/or C–A–S–H and/or K–A–S–H and the combination (N,C)–A–S–H and/or (N,K) –A–S–H gels during the alkaline activation process. By SEM image analysis it was also verified that more gels are formed for more denser structure of the alkali-activated materials. The increase in the dosages of RCBW in the mixtures was also followed by an increase in compressive strength for all the tested ages. It developed from 25 to 59 MPa for samples with RCBW volume content dosage of 10% and 50% respectively. Also, the binder matrix becomes denser and compact by gradually increasing the RCBW dosage.

Study of an alkali-activated binder based on tungsten mining mud and brick powder waste

Blends of Tungsten mining waste mud (TMWM) and brick waste powder (BP) with different dosages were used as precursors for the study of a new binder obtained by alkali-activation. The synthesis was obtained at 60ºC curing during the first 24 hours and at 20°C during the remaining period. A combination of sodium hydroxide (SH) and sodium silicate (SS) solutions was used with SS/SH weight ratio equal 1.5. The solid precursors/liquid activators weight ratio equal to 4. And the modules SiO2/Na2O increase with the increasing of BP dosages 5.21 and 5.59 for dosages 10% and 50%, respectively. Mineralogical characterisation of raw materials was carried out by X–ray diffraction (XRD). The effect of the dosage of BP on the compressive strength and pore size distribution of the new binder was investigated from 24 hours up to 28 days. The pore size distribution was obtained mercury intrusion porosimetry (MIP). The increase in the dosages of BP, between 10 to 50%, was followed by an increase in compressive strength, from 25 to 59 MPa, for all the tested ages. The binder matrix become more dense and compact with the gradually increase of BP dosages, as found out by MIP.

Effect of immersion in water partially alkali-activated materials obtained of tungsten mine waste mud

Alkali-activated binders can be obtained using several sources of alumino-silicate materials, from calcinated clays, like kaolin, to industrial by-products, such as fly ash and, more recently, to calcinated waste mud from mining activities. The technology to obtain alkali-activated binders, also designated as geopolymers, is gaining increasing interest, since, in some cases, the properties of geopolymeric materials are superior to other existing cementitious systems. The research presented in this paper intends to deepen the knowledge regarding the properties of geopolymeric materials obtained using tungsten mining waste mud, particularly to study its behaviour after being immersed in water. However, in the current work, focus is given to follow compressive strength results in partially alkali-activated samples immersed in water, during different curing periods of time. Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy analysis (FTIR) were also utilised to investigate changes in the microstructure at different conditions of water immersion. A significant decrease in compressive strength occurring after 24h of immersion in water was found out, of specific partially alkali-activated materials, despite of its initial high compressive strength after 35days curing, at different temperatures.

Durability and Environmental Performance of Alkali-Activated Tungsten Mine Waste Mud Mortars

Some authors argue that new binders are needed to replace ordinary portland cement (OPC) for enhanced environmental and durability performance. Alkali-activated binders have emerged as an alternative to OPC binders, which seem to have superior durability and environmental impact. This paper report results of a research project on the development of alkali-activated binders using waste mud from a tungsten mine. Abrasion and acid resistance of two ordinary portland cement (OPC) strength class concrete mixtures (C20/25 and C30/37) and several tungsten mine waste mud (TMWM) mixtures were evaluated. Acid resistance was performed by submitting samples to solutions of sulfuric acid, nitric acid, and hydrochloric acid, results of weight loss are reported. Abrasion resistance was assessed by the mass loss of cubic specimens when submitted to 1,000 rotations with the Los Angeles apparatus test machine. This study indicates that TMWM binders possess higher acid and abrasion resistance than OPC based concrete mixtures. The environmental assessment of the TMWM binders shows it can be considered an inert material which indicates that it could be used as a building material.

Influence of sodium carbonate addition on the thermal reactivity of tungsten mine waste mud based binders

This paper report results of a research project related to the development of an alkali-activated based binder using mineral waste mud from a tungsten mine. Some aspects related to the influence of time and temperature calcination of mine waste mud mixed with sodium carbonate on the compressive strength performance of alkali-activated mortars are reported. Results show that calcination of mine waste mud mixed with sodium carbonate does not lead to the dehydroxylation state. Although they possess early high strength, alkali-activated mortars based on mine waste mud calcined with sodium carbonate present a high amount of sodium efflorescences after water immersion that maybe due to an ineffective chemical combination.

RETRACTED: Properties of tungsten mine waste geopolymeric binder

Abstract Tungsten mine waste mud (TMWM) geopolymeric binder is a new cementitious material with a very high early age strength. It is obtained from dehydroxylated mine waste powder mix with minor quantities of calcium hydroxide and activated with NaOH and waterglass solutions. Tests on properties of TMWM binders such as workability, setting time, unrestrained shrinkage, water absorption and static modulus of elasticity were carried out and the results are reported in this paper. This is followed by comparisons with literature related data and a discussion about it. The results showed that current devices use to assess OPC fresh properties are not recommended to evaluate TMWM binders. It has also been found that traditional procedures used to evaluate unrestrained shrinkage may be responsible for misleading results when using those new binders. Water absorption data shows that TMWM has a very compacted structure. Results concerning the static modulus of elasticity are similar to the ones obtained by other authors. However the hypothesis related to modulus of elasticity decrease due to the use of high Al/Si alkali activated mixtures was not confirmed.

Adhesion characterization of tungsten mine waste geopolymeric binder. Influence of OPC concrete substrate surface treatment

Tungsten mine waste mud (TMWM) was investigated for its potential use as repair material of ordinary portland cement (OPC) concrete. Bond strength between OPC concrete substrate and three repair materials was analysed. TMWM geopolymeric binder and two commercial repair products were used as repair materials. Bond strength behaviour was assessed from slant shear tests. A total of 128 slant shear specimens were made in order to evaluate bond strength at 1, 3, 7 and 28 days curing. Four kinds of concrete substrate surface treatment were used, as cast against metallic formwork, as cast against wood formwork, saw cut and acid etching. This study indicates that TMWM geopolymeric binders possess very high bond strength even at early ages and that behaviour is not affected by low surface treatment roughness. Commercial repair products on the other hand show very low bond strength and are very dependent on surface treatment roughness. Scanning electron micrographs reveal that TMWM geopolymeric binders chemically bond to the concrete substrate, while cost comparisons show this geopolymeric repair solution is by far the most cost efficient.