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Massive chemical reactions are not expected when injecting CO2 in siliceous sandstone reservoirs, but their performance can be challenged by small-scale reactions and other processes affecting their transport properties. We have conducted a core flooding test with a quartzarenite plug of Lower Cretaceous age representative of the secondary reservoir of the Hontomín test site. The sample, confined at high pressure, was successively injected with DIW and CO2-saturated DIW for 49 days while monitoring geophysical, chemical, and hydrodynamic parameters. The plug experienced little change, without evidence of secondary carbonation. However, permeability increased by a factor of 4 (0.022–0.085 mD), and the VP/VS ratio, whose change is related with microcracking, rose from ?1.68 to ?1.8. Porosity also increased (7.33–8.1%) from the beginning to the end of the experiment. Fluid/rock reactions were modeled with PHREEQC-2, and they are dominated by the dissolution of Mg-calcite. Mass balances show that ?4% of the initial carbonate was consumed. The results suggest that mineral dissolution and microcracking may have acted in a synergistic way at the beginning of the acidic flooding. However, dissolution processes concentrated in pore throats can better explain the permeability enhancement observed over longer periods of time.

Massive chemical reactions are not expected when injecting CO2 in siliceous sandstone reservoirs, but their performance can be challenged by small-scale reactions and other processes affecting their transport properties. We have conducted a core flooding test with a quartzarenite plug of Lower Cretaceous age representative of the secondary reservoir of the Hontomín test site. The sample, confined at high pressure, was successively injected with DIW and CO2-saturated DIW for 49 days while monitoring geophysical, chemical, and hydrodynamic parameters. The plug experienced little change, without evidence of secondary carbonation. However, permeability increased by a factor of 4 (0.022–0.085 mD), and the VP/VS ratio, whose change is related with microcracking, rose from ?1.68 to ?1.8. Porosity also increased (7.33–8.1%) from the beginning to the end of the experiment. Fluid/rock reactions were modeled with PHREEQC-2, and they are dominated by the dissolution of Mg-calcite. Mass balances show that ?4% of the initial carbonate was consumed. The results suggest that mineral dissolution and microcracking may have acted in a synergistic way at the beginning of the acidic flooding. However, dissolution processes concentrated in pore throats can better explain the permeability enhancement observed over longer periods of time.

The dimension stone industry is one of the leading economic activities of Galicia and it is also an important industry in many other parts in the world. During the sawing and preparation of dimension stone, a large amount of granite sawdust is generated. In the O Porriño area alone, located in the southern part of Galicia, c.?300 000 tonnes are produced every year. According to current EU Directives, granite sawdust is considered to be waste and its disposal must conform to the environmental standards that result from their implementation. The pertinent Spanish laws have established the need to lay down a suitable strategy for the characterization and assessment of sawdust products for the purpose of their satisfactory integration into the dimension stone productive chain. This paper presents the results of a comprehensive characterization study of the granite sawdust of O Porriño (Pontevedra, NW Spain), including a description of its physicochemical, mineralogical and geotechnical properties. On the basis of the results of this characterization, we raise the question of the suitability of this material for use in earthworks as well as in the construction of layers for landfill sealing and/or waterproofing. Our findings show that the properties of granite sawdust are suitable for such purposes, and other possible uses are being studied in continuing research.

The dimension stone industry is one of the leading economic activities of Galicia and it is also an important industry in many other parts in the world. During the sawing and preparation of dimension stone, a large amount of granite sawdust is generated. In the O Porriño area alone, located in the southern part of Galicia, c.?300 000 tonnes are produced every year. According to current EU Directives, granite sawdust is considered to be waste and its disposal must conform to the environmental standards that result from their implementation. The pertinent Spanish laws have established the need to lay down a suitable strategy for the characterization and assessment of sawdust products for the purpose of their satisfactory integration into the dimension stone productive chain. This paper presents the results of a comprehensive characterization study of the granite sawdust of O Porriño (Pontevedra, NW Spain), including a description of its physicochemical, mineralogical and geotechnical properties. On the basis of the results of this characterization, we raise the question of the suitability of this material for use in earthworks as well as in the construction of layers for landfill sealing and/or waterproofing. Our findings show that the properties of granite sawdust are suitable for such purposes, and other possible uses are being studied in continuing research.

The environmental impact was investigated of high-pH water and the mobility of toxic metals, in particular Cr, in relation to the growth of the dimension stone industry in Galicia, Spain. Physicochemical, mineralogical and geomechanical characterisation of the fines was carried out and the effects were studied of the production cycle, including the use of steel grit and hydrated lime, the typical lithotype (Rosa Porrino) subjected to sawing and the hydrogeochemistry of the waters used in industrial processing. The results indicated that granite fines do not constitute a significant hazard to the quality of natural waters., The environmental impact was investigated of high-pH water and the mobility of toxic metals, in particular Cr, in relation to the growth of the dimension stone industry in Galicia, Spain. Physicochemical, mineralogical and geomechanical characterisation of the fines was carried out and the effects were studied of the production cycle, including the use of steel grit and hydrated lime, the typical lithotype (Rosa Porrino) subjected to sawing and the hydrogeochemistry of the waters used in industrial processing. The results indicated that granite fines do not constitute a significant hazard to the quality of natural waters.

A large amount of granite sawdust is generated during the sawing and preparation of dimension stone, with about 300 000 tpa produced in the O Porrino area in Galicia. Under current EU directives, granite sawdust is considered to be waste and its disposal must conform with environmental standards. The relevant Spanish laws have established the requirement for a strategy to characterise and assess sawdust products in order to integrate them into the dimension stone production cycle. Samples of granite sawdust produced using gang saws or diamond-edged disc saws were characterised in relation to their physicochemical, mineralogical and geotechnical properties and compaction and consolidation tests were also carried out. The low permeability of the sawdust suggests that it may be used as a liner or cover material for municipal waste landfills. It may also be employed to stabilise oily waste material, where the surface reactivity of the sawdust as expressed by the zeta potential may play an important role. It is also being considered as a passive treatment for acid mine drainage, on the basis of its moderate neutralisation potential., A large amount of granite sawdust is generated during the sawing and preparation of dimension stone, with about 300 000 tpa produced in the O Porrino area in Galicia. Under current EU directives, granite sawdust is considered to be waste and its disposal must conform with environmental standards. The relevant Spanish laws have established the requirement for a strategy to characterise and assess sawdust products in order to integrate them into the dimension stone production cycle. Samples of granite sawdust produced using gang saws or diamond-edged disc saws were characterised in relation to their physicochemical, mineralogical and geotechnical properties and compaction and consolidation tests were also carried out. The low permeability of the sawdust suggests that it may be used as a liner or cover material for municipal waste landfills. It may also be employed to stabilise oily waste material, where the surface reactivity of the sawdust as expressed by the zeta potential may play an important role. It is also being considered as a passive treatment for acid mine drainage, on the basis of its moderate neutralisation potential.