Optimization and dust emissions analysis of the air jigging technology applied to the recycling of construction and demolition waste

Analysis of the Aggregate Production Process with Different Geometric Properties in the Light Fraction Separator

This article presents an analysis of separation results in a specially designed and activated light fraction separator used to remove impurities from mineral aggregates. Laboratory tests conducted on a quarter-technical scale involved performing experiments to ascertain the scope for adjusting the variable settings of the separator operating parameters. These include the frequency and amplitude of pulsation, the height of the heavy-product reception threshold, the size of water flow and variations in the grain size and shape of the feed. During the experiments, the degrees of chalcedonite and dolomite grain purification were studied within the range of grain size for the feed: (2.0-4.0 mm for small grains, 8.0-16.0 for coarse grains and 2.0-16.0 mm for a wide range of grain sizes). The effects of the separator were assessed based on the amount of organic impurities in each heavy product. In all experiments, very good results were obtained, because the percentage of impurities in the product after separation was below 1% in accordance with the assumed technological standard assumption. Regarding the obtained content of light impurities with the separator set to optimal operating parameters, the percentage of light impurities in the product content was reduced to below 0.1%, which meets the guidelines described according to applicable standards. Multi-variant analysis allowed the optimal operating ranges of the separator to be determined, producing refined aggregate in terms of grain size and shape. The final results were also linked to the performance of the device, and its model dependencies were also determined.

Production of High-Quality Coarse Recycled Aggregates through a Two-Stage Jigging Process

The use of recycled aggregates (RA) to replace natural aggregates (NA) in new concrete production has been pointed out as one of the main strategies to close the loop of construction materials. However, producing RA with properties similar to those of NA has been challenging, since current recycling methods struggle to remove contaminants like ceramics and mortar, whose presence impairs RA properties. In this study, a processing route consisting of a two-stage separation in hydraulic jig was tested, aiming to produce RA from a representative sample of Brazilian construction and demolition waste. All material streams generated in the tests were characterized in terms of composition, size distribution, density, shape index, and water absorption. The results indicated the possibility to produce a high-quality RA, containing more than 99.5% mass of concrete, with adequate properties to replace NA in new concrete production. Also, a conventional RA with suitable properties for downcycling uses (for example, base and sub-base material) could be obtained as a co-product. Finally, the results showed it was possible to recover more than 75% of the original concrete in Construction and Demolition Waste CDW, avoiding its disposal as waste.

Environmental performance of construction and demolition waste management strategies for valorization of recycled coarse aggregate

This study reports on a Life Cycle Assessment (LCA) comparison between two different Construction and Demolition Waste (CDW) management strategies to produce Recycled Coarse Aggregate (RCA): the current recycling strategy (RCA-C) versus air jig strategy (RCA-PR). Additionally, RCAs are compared to natural aggregate production. Air jig is proposed as a recycling strategy for CDW sustainable reuse and recycling. In contrast to RCA-C, air jig allows better CDW segregation, providing recycled materials with better quality. The results point out that recycling strategies differ in segregation efficiency, the quality of recycled material produced, and environmental performance. Both recycling strategies provided environmental benefits when compared to natural aggregate. RCA-PR presents better environmental performance due to the larger number of by-products generated as a result of using air jig and it is able to reduce the environmental impacts related to its management based on the benefits of its by-products. The results suggest that the production and transport of RCA are viable from an environmental point of view in larger urban centers. This study provides a better understanding of CDW management, enhancing knowledge on the environmental performance of the current practice and a future proposal recycling strategy. Moreover, it opens up a new perspective on the multifunctionality associated with recycling strategies of CDW and understanding about air jig environmental impacts.

Construction and Demolition Waste Recycling through Conventional Jig, Air Jig, and Sensor-Based Sorting: A Comparison

The paper presents a comparison of the concentration methods conventional jig, air jig, and sensor-based sorting to treat construction and demolition waste. All tests were made with concrete, brick, and gypsum particles and the tests aim to separate these materials into different size ranges, depending on the method. The equipment tested, conventional jig, air jig, and sensor-based sorting present good results to concentrate construction and demolition waste particles, with different concentrations and mass recoveries. The results show particularly good mass recoveries and particle concentration for conventional jig, especially for concrete and gypsum particles. Sensor-based sorting should preferably use concentration circuits for best results.

Jigging: A Review of Fundamentals and Future Directions

For centuries, jigging has been a workhorse of the mineral processing industry. Recently, it has also found its way into the recycling industry, and the increasing concerns related to water usage has led to a renewed interest in dry jigging. However, the current scenario of increasing ore complexity and the advent of smart sensor technologies, such as sensor-based sorting (SBS), has established increasingly challenging levels for traditional concentration methods, such as jigging. Against this background, the current review attempts to summarize and refresh the key aspects and concepts about jigging available in the literature. The configuration, operational features, applications, types, and theoretical models of jigging are comprehensively reviewed. Three promising paths for future research are presented: (1) using and adapting concepts from granular physics in fundamental studies about the stratification phenomena in jigs; (2) implementing advanced control functions by using machine vision and multivariate data analysis and; (3) further studies to unlock the potential of dry jigs. Pursuing these and other innovations are becoming increasingly essential to keep the role of jigging as a valuable tool in future industry.