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The purpose of this paper is to propose a sorting platform to increase the quality of recycled aggregates through the supplementary use of mineral processing techniques and additional sorting. The difficulty of liberation is discussed, and the methodology currently used in mineral processing is proposed. Jigs, hydrocyclones and sensor-based sorting are considered to have good performance in the sorting of adequately recycled aggregates. The new perspectives on sorting and liberation for recycling aggregates are discussed. The new process is presented based on the current process in recycling platforms, with supplementary sorting of the recycled concrete. The gain in density and the reduction in water absorption are studied. The relation between the water content and the density of aggregates is analysed for three quality levels of recycled aggregates. The gain in density and the reduction in water absorption were linked to the aggregate replacement rates. The reduction in transport and discharge costs due to the increased aggregate quality was linked to the aggregate replacement rate and distance to quarry. In our study, replacing a lower-quality aggregate with another of medium quality leads to an expected density gain of approximately 4%. Conversely, if replaced by superior quality aggregate, the expected gain will be 8.4%. As a consequence, a 34% reduction in water absorption could also be obtained. The cost reduction is exponential with the substitution rate of recycled materials. There is a decrease in transport costs if the quality of recycled aggregates increases. Conversely, if the reduction in transport costs when the quality of recycled aggregates increases is considered, the distance between the demolition site and quarry is not important.

This paper proposes an economic analysis of three different types of processing in CDW (construction and demolition waste) recycling platforms, according to the sophistication of the processing technologies (current advanced, advanced and advanced sorting). The methodology that is adopted is in the economic evaluation concept of projects and is classified with a scoping study phase. In these contexts, three levels of CDW processing capabilities for recycling platforms are analyzed (100, 300 and 600 thousand tons per year). This article considers databases obtained from similar projects that have been published in the specialized literature; the data sources are primarily from the European continent. The paper shows that current advanced process has better economic performance, in terms of IRR, related to the other two processes. The IRR associated with advanced and advanced sorting processes could be raised by, (i) higher price of secondary primary material, and/or (ii) higher capacity of platforms, and/or (iii) higher sharing of secondary primary material in the total production. The first two points depend on the market conditions (prices and total quantity of CDW available) and (potential) fiscal or incentive policies. The last one depends on technological progress.; Cet article propose une analyse de trois différents types de procédés de recyclage des déchets issus de la construction et la démolition de bâtiments. Trois dimensionnements (100, 300 et 600t/an) de plateformes de recyclage sont étudiés.

This work deals with the separation of concrete, brick and gypsum particles from a CDW recycled aggregate mixture. Construction and Demolition Waste materials can be handled as an ore treatment problem. Efficient sorting processes of low quality CDW recycled aggregate could allow the reuse of concrete, brick and gypsum particles. The processes also improve the remaining mixed aggregates for recycling in unbound sub-base materials, by increasing their self-cementing properties and by reducing the sulfate content through the removal of gypsum. All tests were carried out in the size range between 4 and 20 mm using a laboratory air jig. The aim of the work is to concentrate a high amount of gypsum (light material) and concrete (heavy material) particles. Three working parameters are relevant for the jigging processes control such as the sorting duration, the frequency and the expansion ratio. Each of them are studied. It was found that a quadratic model of the number of jig cycles, a product of the frequency and time, accurately predict well the sorting results, if the expansion is large enough. An optimal point seems achieved at about 320 jigging cycles. Concentrates with concrete contents higher than 90% and gypsum contents significantly lower than 1% were possible to be reached and can be an alternative in aggregates for the concrete market. Indeed, gypsum reduction in concrete concentrates was about 25 times. This level of reduction could be satisfactory in sorting real demolition products. On the other hand, contents of over 70% of gypsum concentrates were obtained, increasing the reuse and recycling abilities.