Recycling of mine wastes as raw materials for the construction sector: Solutions based on materials circularity and sustainable resource governance

The mining industry in general, and the phosphate industry in specific is an important mainstream in terms of waste rocks as it generates huge amounts of waste rocks and tailings during their activities. As a matter of example, the phosphate mining in Morocco produces amounts up to 150 million tons or even more of waste rocks and tailings each year. Non-polluting mine wastes (Tailings and waste rock) must be regarded as an opportunity to create new value. The reuse of these wastes, depending on their chemical, mineralogical and geotechnical properties, as alternative raw material in construction and building materials field constitutes a promising environmental solution. The main objective of our studies in Morocco was to investigate the feasibility of using non-polluting mine wastes to produce materials especially for the construction sector, such as using phosphate mine wastes as cementing materials, as additives in mortars or concrete, or as raw materials for bricks, ceramics and geopolymers or aggregates for roads construction and B25 concrete. The phosphate waste rock has to be classified in the category of natural aggregates that are similar to conventional materials. Laboratory and pilot scale investigations demonstrated that recycling mine wastes from may be feasible. The presentation will be focused mainly will be focused mainly on the valorization of phosphate waste rock an alternative aggregate in the construction sector. In addition, Jerada coal mine wastes recycling investigate the use of an integrated and circular approach based on coal recovery and waste rock recycling as alternative clays and aggregates (gravel and sand) in the construction sector. Froth flotation was used to recover coal particles using diesel as a collector and Methyl Isobutyl Carbinol as a frother. The tailings of coal flotation process (CFT) were used to manufacture fired bricks at a pilot scale. Then, gravel and sand obtained after a CMWR screening were tested as alternative materials for concrete production. The choice of the construction sector is based on its capacity to absorb huge quantity of materials

Analysis on the situation of subjective well-being and its influencing factors in patients with ankylosing spondylitis

BACKGROUND: To examine the subjective well-being (SWB) in patients with ankylosing spondylitis (AS) compared with the healthy controls, and to explore the associations between SWB and demographic characteristics, disease-specific variables in AS patients. METHODS: SWB was assessed with General Well-Being Schedule (GWBS) in 200 AS patients and 210 healthy controls. Comparisons among subgroups were performed to investigate how certain aspects operate as favorable or adverse factors in influencing SWB in the patients with AS. RESULTS: Both men and women with AS reported significantly impaired SWB on all scales of the GWBS except for the Control (O) scale. The results revealed that better sleep, lower disease activity and more family care predicted higher SWB. In AS patients, positive attitude towards therapy prospect was significantly associated with higher SWB. Therapy prospect refers to the hope of patients about the disease treatment. CONCLUSIONS: Compared with general population, SWB might be affected by the onset of AS. There are significant associations between SWB and sleep quality, BASDAI, APGAR, therapy prospect

Laboratory Evaluation of the Use of Alkaline Phosphate Wastes for the Control of Acidic Mine Drainage

Pyrrhotite tailings at the abandoned Kettara mine site in Morocco are producing acid mine drainage (AMD). We investigated the use of alkaline phosphate waste (APW) rock from a nearby operating open-pit phosphate mine to control the AMD. The neutralizing potential of the APW, using the Paktunc method, was estimated between 500 and 680 kg CaCO3/t. In laboratory column tests, the addition of 15 wt% APW to the coarse Kettara tailings produced leachates with significantly lower acidities and metal concentrations than unamended controls. The high calcium concentration in the flushed solutions indicates that calcite was responsible for the neutralization. Dolomite dissolution seems to be negligible and fluorapatite was stable under the testing conditions. It was also observed that when the treated solution comes in contact with unweathered Kettara coarse tailings, the pH becomes acidic, although the metal concentrations remain low

A comparative study on the practical use of low sulfide base-metal tailings as aggregates for rendering and masonry mortars

International audienceThe reuse of some industrial by-products in the construction industry saves natural resources and energy, while at the same time reduces environmental problems related to their surface disposal. Mine tailings are currently among the largest industrial by-products in the world, and yet, only limited studies have been conducted to evaluate their reuse potential. Moreover, abandoned base-metal tailings are increasingly used in some developing countries for the manufacture of mortars without any control, engineering basis or environmental concern. In this study, an experimental program using mechanical tests, mineralogical investigations and leaching tests is presented to assess the use of low sulfide base-metal tailings, with varying properties, as fine aggregates for rendering and masonry mortars. An authentic case study illustrating their use in Moroccan construction is additionally presented. Overall, it was observed that the main properties affecting the performances of these tailings-based mortars are the residual Pb–Zn concentrations and the fine content of each tailing. The Pb–Zn fraction, when using the appropriate substitution level, may serve as an active set retardant improving mortars setting time. The leaching of metals was also successfully stabilized in mortars

GIS-based environmental database for assessing the mine pollution : a case study of an abandoned mine site in Morocco

Morocco with important mining activities is increasingly concerned about impacts of mining on the environment. In Morocco, there are approximately 200 abandoned mine sites which vary from small scale underground mines to large scale open-pit mines. Some of these mines, with reactive tailings and waste rocks, are problematic. Indeed, Acid Mine Drainage (AMD) pollution from abandoned mines is responsible for soil and water contamination, land resources degradation, changes in landscapes, habitat destruction and human health hazards. In the current case study about the abandoned Kettara mine site, the impact of the old mining activity is assessed by the design and elaboration of an environmental database which will be supported by Geographic Information System (GIS) technology. This database includes multidisciplinary data related to geochemistry, hydrochemistry, hydrology, land cover, geology and climates. The current research demonstrated the efficiency of integrating multidisciplinary data and using GIS technologies when assessing the environmental impact of abandoned mines and forecasting how the pollution is occurred. The obtained results show that in addition to the soil, the surface water and groundwater of the Kettara mine are also contaminated by pollutants which were previously released from mine wastes by AMD action. The sulphate content and the Electrical Conductivity (EC) of the surface water and groundwater are high. The average values for surface water are: sulphate approximate to 7920 mg/L and EC approximate to 256851 mu S/cm. However, in groundwater they are: sulphate approximate to 2088 mg/L and EC approximate to 631 mu S/cm. These values exceed the guidelines for drinking water quality prescribed by the World Health Organization (WHO) 600 mg/L and 1500 mu S/cm for sulphate and EC respectively. The developed GIS based environmental database will serve as a reference study for other abandoned mine sites. Finally, it will be employed for the establishment of a web-based GIS Decision Support System which will assist decision makers in assessing and monitoring the occurred mine pollution

Etude géophysique et hydrogéologique du site minier abandonné de Kettara (région de Marrakech, Maroc): contribution au projet de réhabilitation

Abstract and keywords provided in French and EnglishLes rejets sulfurés de la mine abandonnée de Kettara, située à 30 km au Nord-Nord-Ouest de Marrakech, sont directement entreposés sur un substratum schisto-gréseux fracturé. D'une superficie d'environ 16 ha, ils constituent une réelle source de pollution pour l'écosystème local en particulier à cause du Drainage Minier Acide (DMA) vers les eaux de surface et de la nappe phréatique. Le projet de réhabilitation du site minier de Kettara prévoit dans l'un de ses axes de minimiser l'effet DMA par neutralisation à l'aide de dépôts stériles riches en carbonates issus de l'extraction des phosphates de la mine de Youssoufia voisine. Ces derniers seront utilisés à la fois comme amendement des rejets miniers acides et comme couverture évapo-transpirante (barrière capillaire). Notre étude a permis d'une part, de mieux appréhender la nature et la structure du parc à résidus et de son substratum et d'autre part, de caractériser l'impact de ces résidus sur la qualité des ressources en eau souterraine. Les résultats issus de cette étude vont contribuer à la réussite du projet de réhabilitation du site.The sulphurated mine waste of the abandoned Kettara pyrrhotite mine, located approximately 30 km north-northwest of Marrakech, Morocco, has been deposited on a fractured schistous substratum. Over an area of about 16 ha, this mine waste threatens the local ecosystem with pollution, particularly due to the infiltration of acid mine drainage (AMD) via surface waters towards the groundwater. As part of the rehabilitation project at the Kettara mine, it is proposed to minimize the effect of AMD by neutralization using fine sterile carbonate-rich deposits that are by-products of phosphate extraction in the neighbouring Youssoufia mine. These by-products are used both as amendement for the acidic mine waste and as a capillary barrier to allow evapotranspiration. On the one hand, our study has allowed a better understanding of the structure of the tailings pond and of the substratum, and on the other hand, it has made it possible to characterize the impact of the mine waste on groundwater quality. The results of this study will contribute to the success of the site rehabilitation project