Tungsten Mine Waste Geopolymeric Binder: Preliminary Hydration Products Investigations (original) (raw)
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Alkali Activated Geopolymeric Binder Using Tungsten Mine Waste: Preliminary Investigation
ABSTRACT This paper reports preliminary results of a PhD research project related to the development of an alkaliactivated geopolymeric binder using mineral waste mud from the Portuguese tungsten mine Panasqueira which is still operating. Mineralogical analysis indicates that the waste mud is compose mainly of muscovite and quartz with a high content of iron and alkali metals. Results of the dehydroxylation process are presented by x-ray diffraction and infrared emission spectroscopy patterns of quenched waste powder and also from compressive strength of alkali-activated mortar specimens, showing a significant potential as a geopolymeric source precursor. Considerations about Portuguese industrial waste production are made showing a high level ratio of CO2 emissions mostly from cement industry, a nation-wide lack of fly ash and blast furnace slag to be used as cementitious by-products and huge amounts of quarrying and mining wastes and also the need to preserve it`s large and protected natural areas leading to the use of alumino-silicate minerals as the only reasonable alternative to the development of alkali-activated friendly environmental binders. Materials raw cost comparisons between Portland cement based concretes and alkali-activated geopolymeric based concretes are also made showing that Portland cement based ones are by far the most economic ones but not for very long due to the expected increase in Portland cement cost under the recent implementation of CO2 emissions trading scheme (ETS).
Alkali activated geopolymeric binder using tungesten mine waste: preliminary investigation
2005
This paper reports preliminary results of a PhD research project related to the development of an alkaliactivated geopolymeric binder using mineral waste mud from the Portuguese tungsten mine Panasqueira which is still operating. Mineralogical analysis indicates that the waste mud is compose mainly of muscovite and quartz with a high content of iron and alkali metals. Results of the dehydroxylation process are presented by x-ray diffraction and infrared emission spectroscopy patterns of quenched waste powder and also from compressive strength of alkali-activated mortar specimens, showing a significant potential as a geopolymeric source precursor. Considerations about Portuguese industrial waste production are made showing a high level ratio of CO 2 emissions mostly from cement industry, a nation-wide lack of fly ash and blast furnace slag to be used as cementitious by-products and huge amounts of quarrying and mining wastes and also the need to preserve it`s large and protected natural areas leading to the use of alumino-silicate minerals as the only reasonable alternative to the development of alkali-activated friendly environmental binders. Materials raw cost comparisons between Portland cement based concretes and alkali-activated geopolymeric based concretes are also made showing that Portland cement based ones are by far the most economic ones but not for very long due to the expected increase in Portland cement cost under the recent implementation of CO 2 emissions trading scheme (ETS).
Investigations of tungsten mine waste geopolymeric binder: Strength and microstructure
Construction and Building Materials, 2008
This paper reports some results of a research project related to the development of a new binder using mineral waste mud from the Portuguese mine. Some aspects related to the effect of aggregates in the microstructure and mechanical behaviour of tungsten mine waste geopolymeric binder are reported in the present study. Test results showed that the aggregate type influences strength development.
Investigations on Mix Design of Tungsten Mine Waste Geopolymeric Binder
Construction and Building Materials, 2008
Strength data show that the parameters, which lead to optimum strength for 7 days curing, remain the same for long curing ages. However, when calcium hydroxide percentages above 10% are used, strength decrease after 14th curing day is noticed. In order to explain this behaviour several hypotheses are discussed. The use of an activator with a sodium hydroxide concentration of 24 M leads to a compressive strength of almost 70 MPa. The strength performance is typical of a very reactive binder, being suggested that it is due to the calcium hydroxide and also to the nucleation centers provided by the iron oxide of the mine waste mud. Results allow foreseeing that even higher strength performance could be achieved if lower water/sodium molar ratios were used.
Alkali Activated Geopolymeric Binder Using Tungsten Mine Waste
This paper reports preliminary results of a PhD research project related to the development of an alkali-activated geopolymeric binder using mineral waste mud from the Portuguese tungsten mine Panasqueira which is still operating. Mineralogical analysis indicates that the waste mud is compose mainly of muscovite and quartz with a high content of iron and alkali metals. Results of the dehydroxylation process are presented by x-ray diffraction and infrared emission spectroscopy patterns of quenched waste powder and also from compressive strength of alkali-activated mortar specimens. Considerations about Portuguese industrial waste production are made showing a high level ratio of CO2 emissions mostly from cement industry, a nationwide lack of fly ash and blast furnace slag to be used as cementitious by-products and huge amounts of quarrying and mining wastes and also the need to preserve it`s large and protected natural areas leading to the use of alumino-silicate minerals as the only reasonable alternative to the development of alkali-activated friendly environmental binders. Materials raw cost comparisons between Portland cement based concretes and alkali-activated geopolymeric based concretes are also made showing that Portland cement based ones are by far the most economic ones but not for very long due to the expected increase in Portland cement cost under the recent implementation of CO2 emissions trading scheme (ETS). 1-Introduction Current estimates of world cement manufacture are 1700 Mt (millions tonnes)/year accounting for 5% of global CO2 emissions [1]. With a production of 185 Mt of Portland cement and considering global Western Europe CO2 emission in the year 2000 of 3500 Mt, European cement industry accounts for 4,6% of CO2 global emissions [2,3]. Portland cement CO2 emissions, results from calcination of limestone (CaCO3) and from combustion of fossil fuels, including the fuels required to generate the electricity power plant. To make Portland cement clinker limestone is heated with a source of silica in a kiln at temperatures well over 1350ยบ C according to the reaction [1]: 3CaCO3 + SiO2 => Ca3 SiO5 + 3CO2 The production of one tonne of cement generates 0,55 tonnes of chemical CO2 and requires an additional 0,39 tonnes of CO2 in fuel emissions, accounting for a total of 0,94 tonnes of CO2. Nowadays cement industry uses a variety of additives either fly ash (PFC) or blast furnace slag (BFC). Cement replacement with additives are responsible for less CO2 emissions than plain Portland cement, Gielen reports CO2 process and energy related emission of 0,67 tonnes for PFC (25% replacement) and 0,35 tonnes for BFC (65% replacement) [3]. A clear example comes from Lafarge, the world's largest cement manufacturer, since 1990 cement production have cut net emissions by 11,8%, from 0,767 to 0,685 tonnes of CO2 per tonne of cement [4].
Construction and Building Materials, 35, 117-124., 2012
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 24 h of immersion in water was found out, of specific partially alkali-activated materials, despite of its initial high compressive strength after 35 days curing, at different temperatures.
Construction and Building Materials, 2023
The substantial target of this work is to manufacture sustainable geopolymers by recycling low cost industrial wastes (granulated slag, GS; rockwool, RW; and silica fume, SF). To reveal the mineral and chemical compositions of these industrial solid wastes, they were investigated using X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). The granulated slag, rockwool and silica fume were blended with the convenient quantity of alkaline reactor to formulate a hydrated pattern of geopolymers. The phase configuration, physico-mechanical effects [compressive strength (CS), porosity and bulk density] and the microstructural form of the geopolymers were studied via the X-ray diffraction, hydraulic mechanical testing device, helium pycnometer, and Field emission Scanning electron microscope (FE-SEM), respectively. The results declared that the partial substitution of RW by various ratios of SF in presence of GS affect successfully on the physico-mechanical properties of hardened geopolymers. Implication of 2 % SF boosts the physico-mechanical features of the 50GS-48RW hardened geopolymers at all curing ages especially at the age of 28 days. Therefore, the geopolymer 50GS-48RW-2SF displayed the best physico-mechanical characteristics especially the CS at 28-days (39.12 MPa) owing to the formation of diverse hydration products like CSHS, CAHS and NASHs. These results were confirmed via FE-SEM/EDX images that exhibited compact and dense microstructure rod-like crystals of CSHs and three dimensional framework structures of NASHs.
Analysis of the properties of waste-based geopolymeric binders after curing in water
Tungsten mud from a local mine exploration may be recycled to produce geopolymeric binders after an alkaline activation. This procedure allows using these binders in several applications in construction and hydraulic works avoiding the landfilling of those wastes with several economic and environmental benefits. Preliminary tests were carried out to study the effect of different dry curing temperatures, curing water periods and mixes of mud and alkaline solutions on the structural stability and pH variation in water of waste-based geopolymeric binders. The properties (bulk density, specific surface area, chemical composition, microporosity, durability and mechanical compressive strength) of a mix with ratios R(P/S) = 5 and R(S/H) = 4 were analyzed after curing in water. The durability was also studied in solutions with 5% of acetic acid and sulfuric acid, revealing good resistance of the binders to acid attack. This study also demonstrates that mining waste mud can be used to produce geopolymeric binders for wastewater treatment processes. INTRODUCTION Geopolymeric binders (or just geopolymers) may be obtained through a complex chemical reaction in an alkaline environment (condensation and polymerization) of alumino-silicate materials, called precursors (e.g., waste sludge, fly ash, slag and calcined clays). Due to its chemical composition, a particularly waste mud of the Panasqueira mine, located in Portugal, one of the most important and largest tungsten mines in the world, presents very good reactivity with alkaline activators after a thermal calcination process and under certain mixing conditions [1] to produce waste-based geopolymeric binders (WGB). They have potential for use in wastewater treatment processes, due to its suitable mechanical strength [2], good durability, capacity for resistance to acids and sulfates [3], and appropriate porosity, void ratio and specific surface. Therefore, the objective of this investigation was to analyze several properties of WGB when in contact with water and acide solutions in order to evaluate the suitability of the binders to be used in wastewater treatment processes for the treatment of urban, stormwater and industrial effluents.