Full length articleValorization of apatite mining flotation residues by the manufacture of artificial aggregates
Graphical abstract
Introduction
As a political interpretation of an increasing global concern about climate change, a series of reports have been submitted as soon as 1987 by the Brundtland Commission, until Agenda 2030 in which the latest 17 Sustainable Development Goals (SDGs) have been defined (Brundtland et al., 1987; United Nations, 2015). Because of their historical and actual large-scale impacts on ecosystems, human health, socio-economic systems, and because of their capital-intensive nature (Pimentel et al., 2016; Sonesson et al., 2016), the mining industries initiated the Mining, Minerals and Sustainable Development Project in 2002 (Starke, 2002). Ten years later, Buxton (2012) outlined that even if technical advances have been realized in water management and waste toxicity mitigation, the mining companies were insufficiently proactive concerning the challenges of integrated approaches for both land use and mineral production and consumption (Franks et al., 2011). However, they are the largest waste producers, discharging 65 billion tons annually in 2010, with fine particle processing waste representing 14 billion tons per year (Jones and Boger, 2012). A circular economy approach can help to address waste management issues subsequent to global decreasing ore grades and increasing amounts of tailings (Mudd, 2010), considering wastes as potential resources for other processes, while promoting inter-enterprise partnerships (Balanay and Halog, 2016; Preston, 2012). The need for the diversification of research projects in this field is justified by the observation that the misunderstanding of the mineralogical properties and of the behaviour of mining residues is a major factor in the lack of industrial-scale beneficiation (Lottermoser, 2011; Kinnunen and Kaksonen, 2019). Wastes from mining and metallurgical processes have been yet valorized as backfill, components for the manufacture of tiles, bricks or ceramics, glass or rock wool, soil amendments or cement and geopolymer components (Lottermoser, 2011; Pappu et al., 2007; Clifton et al., 1980; Safiuddin et al., 2010). Given the mineralogical composition and the aggregate size of these wastes (below 75 µm and with a median size between 10 and 20 µm), their reuse as filler (Choudhary et al., 2018; Modarres and Rahmanzadeh, 2014; Mistry and Roy, 2016; Kandhal, 1993) or as a clinker substitute for cement production components could be interesting (Snellings et al., 2012; Part et al., 2015; Rana et al., 2015; Paris et al., 2016). Recovery can also be induced by the transformation of fine waste particles into aggregates suitable for civil engineering, as it has been successfully performed with a large number of different wastes, mainly fly ash, vegetal husks, municipal solid waste incineration ash (MSWI ash), coal wastes, cement kiln dust and different types of sludge (Colangelo and Cioffi, 2013a; Baykal and Döven, 2000; Ferone et al., 2013; Vasugi and Ramamurthy, 2014).
Granulation is a size enlargement process which allows the formation of granular materials from fine powders, using liquid dispersion in fluidised beds, tumbling drums, discs or high shear granulators (Litster and Ennis, 2004). Several granulation methods exist to strengthen the physical structure of the aggregates, as cold-bonding pelletization with addition of lime and cement (Arslan and Baykal, 2006; Colangelo et al., 2015; Gesoğlu et al., 2007; Güneyisi et al., 2015), alkaline activators (Bui et al., 2012; Yliniemi et al., 2016) or foaming agents (Hwang and Tran, 2015). The main challenge in granulation process is to maximize the strength of the inter-particle bonds, formed by capillary pressure, viscous forces or surface tensions. Different growth regimes can qualify agglomeration processes within a granulation device but controlling factors for the performance of the aggregates are:
- •
Binder and precursor properties as viscosity, size, specific surface and surface tension;
- •
The proportions between all the materials introduced in the mix and the distribution method chosen;
- •
Speed and intensity of the agitation for consolidation control.
The precursors, i.e. the materials composing the mix as wastes in the form of powder or sludge, dry or liquid binders, must have hydraulic or pozzolanic properties in order to create a solid matrix between the fine powder particles, by forming cementitious phases as calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H). Several factors that determine the reactivity of materials are:
- (1)
The amount of amorphous phases and selectively soluble SiO₂ and Al₂O₃ content, which is correlated to higher aggregates strength (Yliniemi et al., 2016; Snellings et al., 2012; Fernández-Jiménez and Palomo, 2003);
- (2)
Presence of a large number of nucleation sites thanks to material fineness and high specific surface (Toutanji et al., 2004; Bertos et al., 2004; Morone et al., 2014);
- (3)
C content must be limited below 6% to decrease water requirement and avoid mixture segregation and discoloration (Pedersen et al., 2008);
- (4)
Free MgO and free CaO contents must be examined to avoid volume expansion (Wang et al., 2010).
However, a large number of wastes required the addition of binders as lime, cement, fly ash, alkaline binders, geopolymers, or superplastifiers (Terzić et al., 2015; Yliniemi et al., 2017). Portland cement, well known as the main cohesive agent for concrete production can also be used as a preliminary binder for comprehension purposes in terms of mechanical consolidation, before substitution by other environmental-friendly binders. It consists in a mix of alite , belite , tricalcite aluminates , tetracalcic aluminoferrites , and gypsum. After hydration, the main cohesive products are C-S-H, as well as aluminium and calcium hydroxides (Kosmatka et al., 2004).
Limiting factors for the addition of binders are the cost, and the environmental impact and management implied by their introduction. The interesting properties to define the quality of the aggregates mainly refer to aggregate size repartition, size and shape of the aggregates, bulk density, porosity and chemical content of organic matter and iron oxide (Canadian Standards Association, 2014). Some studies have shown that cold-bonded aggregates are suitable for use in concrete (Baykal and Döven, 2000; Tang et al., 2017; Ferone et al., 2013; Colangelo et al., 2015), exhibiting sufficient crushing strength values and good adhesion with the matrix of concrete or mortar specimens.
The work described here explores the possibilities of recycling 5.5 Mt/year of a flotation residue from an apatite ore, forecasted to be exploited for phosphate valorization in Sept-Îles (QC, Canada), during a period of time of 31 years (Roche-Itée, 2012). These processing wastes are currently intended to be disposed as tailings. However, this study focuses on the development of a cold-bonding granulation process to change the mining residues into valuable aggregates for civil engineering, this method being chosen because it is a cost and energy-effective solution for processing large amounts of materials. The regional context differs from the other tailings valorization projects currently undergone in Québec province, because it is located in a remote area, but in a key region for the transportation of goods, particularly from natural resources industries.
However, these waste differ from the alkaline materials (mostly ashes and slags) that are commonly studied for reuse purposes, or submitted to granulation process, both by their chemical composition and by their conditioning state (Gomes et al., 2016). In fact, preliminary flotation implies the use of surfactants that could affect the mineral surfaces and their ability to form interparticle bonds. When similar solid waste are used, there are combined with alkali activators to form geopolymers, which cost and long-term environmental impacts are not yet proven to be beneficial (Singh and Singh, 2019; Bouguermouh et al., 2018), or solidified and stabilised with higher binder proportions (Mesci et al., 2009). It is also current that the ore tailings are transformed into ceramics, but this implies sintering and completely modifies the mineralogy of the initial waste (Mymrin et al., 2020; Kinnunen et al., 2018; Matinde et al., 2018).
After characterization of the initial mining residues, the development of the granulation method for this apatite processing waste is detailed, emphasizing the influence of the experimental parameters on the consolidation of the aggregates. The second part of the results focuses on granulation with Portland cement, and on the variation of the humidity content for granulation. An experimental design using Box-Behnken Design (BBD) methodology is adopted to study in detail the differences on granulation behaviour around a critical humidity content. The last part of the work relates how the exploitation of the BBD results leads to the improvement of the aggregates quality.
Section snippets
Mining residues
The material used for granulation is a waste resulting from extraction and processing of an apatite ore, initially hosted in mafic layers, and essentially comprised of apatite, Fe and Ti oxides (magnetite and ilmenite), olivine, plagioclase and clinopyroxene (Tollari et al., 2008). After crushing, the magnetic fraction and the phosphate concentrate are respectively separated from the mineral matrix using low-intensity magnetic separation, and a flotation process operated with corn starch and
Characterization of the mining residues
Table 2 presents physical and chemical contents measured on the flotation residues, chemical contents expressed in terms of oxide contents. Si, Fe and Al are the predominant elements, but the relative CaO, SiO₂ and Al₂O₃ contents show the residues are different from waste commonly used, such as silica fume, fly ash or slag, particularly due to low Cao content and an unusual high Fe₂O₃ content (Lothenbach et al., 2011). XRD analyses, presented in Figure C of Appendix C, showed that the main
Conclusions
Aggregate size and mineralogy of Arnaud flotation residues make them suitable for production of aggregates by a cold-bonding granulation process, even if few pozzolanic or hydraulic activities has been noticed. Aggregate size distribution is appropriate for use in civil engineering as coarse aggregates, with diameter ranging between 5 and 40 mm. Addition of cement strengthens and sustains inter-particle bonds within the newly-formed aggregates. Within 45 min or 120 min, it is possible to
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References (89)
- et al.
Utilization of fly ash by pelletization process; theory, application areas and research results
Resources, Conservation and Recycling
(2000) - et al.
Stabilization of flotation wastes resulting from the treatment of Pb/Zn ore based on geopolymers
Materials Letters
(2018) - et al.
Manufacture and performance of cold bonded lightweight aggregate using alkaline activators for high performance concrete
Construction and Building Materials
(2012) - et al.
Application of waste materials as fillers in bituminous mixes
Waste management
(2018) - et al.
Uses of waste materials and by-products in construction. Part I
Resource Recovery and Conservation
(1980) - et al.
Recycling of MSWI fly ash by means of cementitious double step cold bonding pelletization: Technological assessment for the production of lightweight artificial aggregates
Journal of hazardous materials
(2015) - et al.
Comparison of test methods to assess pozzolanic activity
Cement and Concrete Composites
(2010) - et al.
Recycling of high volumes of cement kiln dust in bricks industry
Journal of cleaner production
(2017) - et al.
Characterisation of fly ashes. Potential reactivity as alkaline cements☆
Fuel
(2003) - et al.
Sustainable development principles for the disposal of mining and mineral processing wastes
Resources policy
(2011)
Effects of fly ash properties on characteristics of cold-bonded fly ash lightweight aggregates
Construction and Building Materials
Alkaline residues and the environment: a review of impacts, management practices and opportunities
Journal of Cleaner Production
Production of lightweight aggregates from mining and industrial wastes
J Environ Manage
Utilization of cold bonded fly ash lightweight fine aggregates as a partial substitution of natural fine aggregate in self-compacting mortars
Construction and Building Materials
Production of lightweight aggregate from industrial waste and carbon dioxide
Waste management
Determination of the tensile strength of rock by a compression test of an irregular test piece
International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts
A study of the properties of foamed lightweight aggregate for self-consolidating concrete
Construction and Building Materials
Nucleation, growth and breakage phenomena in agitated wet granulation processes: a review
Powder technology
Balling and granulation kinetics revisited
International Journal of Mineral Processing
Recycling mine tailings in chemically bonded ceramics–a review
Journal of cleaner production
Towards circular economy in mining: Opportunities and bottlenecks for tailings valorization
Journal of Cleaner Production
Effects of lightweight fly ash aggregate properties on the behavior of lightweight concretes
Journal of hazardous materials
A microscopic study of granulation mechanisms and their effect on granule properties
Powder technology
Supplementary cementitious materials
Cement and Concrete Research
The transverse motion of solids in rotating cylinders—forms of motion and transition behavior
Powder technology
Effect of using fly ash as alternative filler in hot mix asphalt
Perspectives in Science
Application of coal waste powder as filler in hot mix asphalt
Construction and Building Materials
Valorization of steel slag by a combined carbonation and granulation treatment
Minerals Engineering
The environmental sustainability of mining in Australia: key mega-trends and looming constraints
Resources Policy
Solid wastes generation in India and their recycling potential in building materials
Building and environment
A review of waste products utilized as supplements to Portland cement in concrete
Journal of Cleaner Production
An overview on the influence of various factors on the properties of geopolymer concrete derived from industrial by-products
Construction and Building Materials
A review of the interference of carbon containing fly ash with air entrainment in concrete
Progress in Energy and Combustion Science
Decision-support models for sustainable mining networks: Fundamentals and challenges
Journal of Cleaner Production
Sustainable use of marble slurry in concrete
Journal of Cleaner Production
Investigation of the layering mechanism of agglomerate growth during drum pelletization
Powder technology
16 - Concrete Aggregates
Geopolymerization of solid waste of non-ferrous metallurgy–a review
Journal of environmental management
Employing cold bonded pelletization to produce lightweight aggregates from incineration fine bottom ash
Journal of cleaner production
Artificial fly ash based aggregates properties influence on lightweight concrete performances
Ceramics international
Trace element concentrations in apatites from the Sept-Îles Intrusive Suite, Canada — Implications for the genesis of nelsonites
Chemical Geology
Effect of supplementary cementitious materials on the compressive strength and durability of short-term cured concrete
Cement and Concrete Research
Identification of design parameters influencing manufacture and properties of cold-bonded pond ash aggregate
Materials & Design (1980-2015)
Use of steel slag as a granular material: volume expansion prediction and usability criteria
Journal of Hazardous Materials
Cited by (6)
Preparation of artificial aggregates from concrete slurry waste and waste brick masonry powder: CO<inf>2</inf> uptake and performance evaluation
2023, Construction and Building MaterialsSelf-foaming high strength artificial lightweight aggregates derived from solid wastes: Expansion mechanism and environmental impact
2023, Construction and Building MaterialsCo-utilization of quarry tailings and fly ash for non-sintered ultra-lightweight aggregates (ULWAs) by autoclave technology
2022, Construction and Building MaterialsCitation Excerpt :Concerning the environmental loading and resource scarcity, using the quarry tailings as raw materials in preparing the lightweight aggregates (LWAs) could be one of the most effective ways to solve these two negative factors, which can not only resolve the accumulation of quarry tailings, but also release the pressure by natural aggregates shortage [14-18]. In last decades, LWAs have been receiving more and more attention for the excellent properties, such as low bulk density [19], high heat resistance [20], excellent durability [21], highlighted thermal and acoustic insulation properties [22], and etc. However, the sintering process for tradition LWAs fabrication has been gradually banned due to the restriction of carbon emission and eco-environmental protection [23-25].
Use of CO<inf>2</inf>-active BOFS binder in the production of artificial aggregates with waste concrete powder
2022, Resources, Conservation and RecyclingCitation Excerpt :Considering the lower quality requirements of materials in the production of artificial aggregates (AAs), powdered WCP can be transformed into granulated AAs using various pelletization techniques to minimize this challenging low-value waste in the construction industry (Qian et al., 2022; Ren et al., 2020b; Wu et al., 2021). Extensive efforts have been made to utilize various sources of powdered solid wastes for the production of AAs, including coal fly ash (Gesoğlu et al., 2012; Shivaprasad and Das, 2018), quarry dust (Thomas and Harilal, 2015, 2019), apatite mining flotation residues (Viry et al., 2021), municipal solid waste incineration fly ash and bottom ash (Colangelo et al., 2015; Tang et al., 2017), etc. The waste material-based AAs showed good compatibility with concrete in terms of physical, mechanical and durability performances (Tajra et al., 2019).
Resourceful utilization of quarry tailings in the preparation of non-sintered high-strength lightweight aggregates
2022, Construction and Building MaterialsCitation Excerpt :The type of CBLWAs characterized by the core-shell structure was prepared by using the excavated soil and expanded perlite as raw materials [20], whilst the 28-day of single particle crushing strength is only 23.0 N. Using sodium carbonate solution as alkali-activator also can prepare the lightweight aggregates with glass shell fly ash-clay [33], the compressive strength of aggregate (based on the cylinder test) with the loose bulk density of 1220 kg/cm3 is 4.2 MPa. Viry et al. [34] reused a type of mining residue sludge in artificial aggregates preparation. The final products are suitable for civil engineering utilization with cylinder compressive strength of 7.0 MPa.