Investigations on Mix Design of Tungsten Mine Waste Geopolymeric Binder (original) (raw)
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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.
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).
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).
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.
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].
This paper reports results of a research project related to the development of geopolymeric binder using mineral waste mud from the Portuguese tungsten mine Panasqueira. 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) geopolymeric binder mixtures was evaluated. Acid resistance was performed by submitting samples to solutions of sulphuric acid, nitric acid and chloridric acid, results of weight loss are reported. Abrasion resistance was assessed by the mass loss of cubic specimens when submitted to 1000 rotations with the Los Angeles apparatus test machine. This study indicates that TMWM geopolymeric binders possess higher acid and abrasion resistance than OPC based concrete mixtures.