Conditioning Circuit Analysis for Slimes Management in Quarries

Bourgeois, Florent; Baudet, G.; Bizi, Mohamed; Gaboriau, Hervé

doi:10.1205/026387603770866326

Cited by 5 publications

(3 citation statements)

References 11 publications

(9 reference statements)

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“…Estimates of water consumption within quarries vary widely: greater than 1 m 3 per tonne of gravel (Bourgeois et al 2003), 1.35-1.38 m 3 per tonne of gravel (Ecoinvent 2007) or 2 m 3 per tonne of sand or gravel (SimaPro 2007). Water consumption associated with use of electricity in the production of aggregates and cement is a product of the mass of raw materials used (see Table 1), the water consumed in coal-fired power plants (1.95 m 3 MWh -1 , Brown et al 2007), and the electrical energy used in the production of aggregate and cement.…”

Section: Embodied Watermentioning

confidence: 99%

Impact of fly ash content and fly ash transportation distance on embodied greenhouse gas emissions and water consumption in concrete

O'Brien

Ménaché

O’Moore

2009

Int J Life Cycle Assess

121

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Background, aim and scope Fly ash, a by-product of coalfired power stations, is substituted for Portland cement to improve the properties of concrete and reduce the embodied greenhouse gas (GHG) emissions. Much of the world's fly ash is currently disposed of as a waste product. While replacing some Portland cement with fly ash can reduce production costs and the embodied emissions of concrete, the relationship between fly ash content and embodied GHG emissions in concrete has not been quantified. The impact of fly ash content on embodied water is also unknown. Furthermore, it is not known whether a global trade in fly ash for use in concrete is feasible from a carbon balance perspective, or if transport over long distances would eliminate any CO 2 savings. This paper aims to quantify GHG emissions and water embodied in concrete ( f ′ c =32 MPa) as a function of fly ash content and to determine the critical fly ash transportation distance, beyond which use of fly ash in concrete increases embodied GHG emissions. Materials and methods This paper used previously published and reported data for GHG emissions and water usage in cement production, quarries, transportation and concrete batching to quantify the embodied GHG emissions (CO 2 -equivalent) and water in concrete and the critical transportation distance for fly ash. Results Fly ash content alone is not a good indicator of embodied emissions in concrete; increasing fly ash content only reduces embodied emissions when there is a corresponding reduction in the mass of Portland cement used. The total embodied GHG emissions in concrete (GHG concrete , kg CO 2 -equivalent m −3 ) can be determined from the mass of Portland cement used (mass cement , t m −3 ): GHG concrete =66+790.7 mass cement . This equation can be used to determine the reduction in Portland cement required to meet specific GHG emissions targets for concrete, if the Portland cement is replaced by fly ash sourced within 100 km of a concrete batching plant. Fly ash content has little effect on embodied water, which was 2.7-4.1 m 3 water per cubic metre of concrete. Discussion Fly ash can be transported more than 11,000 km by articulated truck, 47,000 km by rail and 54,000 km by sea and still result in a net reduction in GHG emissions if used to replace Portland cement in concrete. At least 70% of GHG emissions embodied in concrete were due to cement production, even for fly ash content as high as 40%. Aggregate production accounted for 17-25% of embodied GHG emissions. While transport of concrete from batching plant to site represented only 3-5% of GHG emissions, this distance is subject to wide variability and hence can be a source of variation in total embodied GHG emissions. Water used in quarrying aggregate is both the largest and the most variable quantity of water used in concrete production, and accounted for at least 89% of water consumption for all mix designs considered in this study. Conclusions While this study used values applicable to Brisbane, Australia, results are presented in a gener...

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Section: Embodied Watermentioning

confidence: 99%

Impact of fly ash content and fly ash transportation distance on embodied greenhouse gas emissions and water consumption in concrete

O'Brien

Ménaché

O’Moore

2009

Int J Life Cycle Assess

121

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“…Commission 2006) Bourgeois et al (2003). presented figures of 1 H kg/kg,O'Brien et al (2009) presented 2 H kg/kg and Ecoinvent presented 2.5 H kg/kg for aggregates production; these values are significantly higher than all the others.…”

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confidence: 85%

“…WATER INVENTORY FIGURES FOR AGGREGATES PRODUCTIONFigure 4-4 summarizes the aggregates water inventory figures. The data comes from Europe, Switzerland and Australia, referencing Ecoinvent and GaBi methodologies (European Commission 2006; Ecoinvent 2014); global average data published by Cemex, Holcim and Lafarge(Cemex , 2015 Lafarge 2012a;Holcim , 2015; and data from unknown methodologies(Bourgeois et al 2003;O'Brien et al 2009).…”

mentioning

confidence: 99%

Concrete water footprint: a streamlined methodology

Vergara¹,

Lisbeth²

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Water is the most used substance in the world, followed by concrete. Water scarcity is nowadays more common due to concentrated population growth and climate change. Concrete demand is ~15 billion m 3 per year fulfilling the need for more and better housing and infrastructure for a growing and wealthier population. Since no other material could fulfil this demand, concrete needs to be produced in a sustainable way, minimizing environmental loads such as water consumption. The water footprint is a tool that measures water use over a products' life cycle and estimates its potential environmental impacts. Despite the growing concern on water, the existing water footprint methodologies are too complex and require large amounts of data. This study develops a streamlined water footprint methodology for concrete production, simple enough to be useful to the industry and robust enough to be environmentally meaningful. An extensive study on existing water footprint methodologies have been conducted. Then a streamlined methodology was proposed focused on the water flows that are more relevant in concrete production including water quantity and quality letting to meaningful results with less data. Typical water inventory includes the batch water (150-200 H kg/m 3), dust control (500-1500 H kg/day), truck washing (13-500 H kg/m 3), cement production (0.185-1.333 H kg/kg) and aggregates production (0.116-2.0 H kg/kg). Regarding water quality, the most critical flows-Zinc, Lead, Nitrate, Nitrogen oxides and Sulfur dioxide-were identified based on the contribution of these flows to the potential environmental impacts, the control or influence that the concrete producer has on the activities were these flows appear and the feasibility to measure these flows on site. Concrete water footprint varies due to mix design, technological routes, location and choice of impact assessment method. The results are of interest to the research community as well as to the stakeholders of the cement and concrete industries and a contribution to sustainable construction since study of water footprint is fundamental to improve water efficiency.

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Occurrence and fate of acrylamide in water-recycling systems and sludge in aggregate industries

Junqua¹,

Spinelli²,

Gonzalez³

2014

Environ Sci Pollut Res

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Acrylamide is a hazardous substance having irritant and toxic properties as well as carcinogen, mutagen, and impaired fertility possible effects. Acrylamide might be found in the environment as a consequence of the use of polyacrylamides (PAMs) widely added as a flocculant for water treatment. Acrylamide is a monomer used to produce polyacrylamide (PAM) polymers. This reaction of polymerization can be incomplete, and acrylamide molecules can be present as traces in the commercial polymer. Thus, the use of PAMs may generate a release of acrylamide in the environment. In aggregate industries, PAM is widely involved in recycling process and water reuse (aggregate washing). Indeed, these industries consume large quantities of water. Thus, European and French regulations have favored loops of recycling of water in order to reduce water withdrawals. The main goal of this article is to study the occurrence and fate of acrylamide in water-recycling process as well as in the sludge produced by the flocculation treatment process in aggregate production plants. Moreover, to strengthen the relevance of this article, the objective is also to demonstrate if the recycling system leads to an accumulation effect in waters and sludge and if free acrylamide could be released by sludge during their storage. To reach this objective, water sampled at different steps of recycling water process has been analyzed as well as different sludge corresponding to various storage times. The obtained results reveal no accumulation effect in the water of the water-recycling system nor in the sludge.

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Conditioning Circuit Analysis for Slimes Management in Quarries

Cited by 5 publications

References 11 publications

Impact of fly ash content and fly ash transportation distance on embodied greenhouse gas emissions and water consumption in concrete

Impact of fly ash content and fly ash transportation distance on embodied greenhouse gas emissions and water consumption in concrete

Concrete water footprint: a streamlined methodology

Occurrence and fate of acrylamide in water-recycling systems and sludge in aggregate industries

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