Search Results (5)

A study of 300 diamonds in the 2–4 mm size range revealed that X-ray transmission demonstrated a predictable relationship for detecting diamonds, with all diamonds being identified. In contrast, X-ray luminescence showed no consistent relationship between diamond characteristics and detection, and not all diamonds were identified using this method. When comparing the X-ray transmission response of diamonds to common gangue minerals found in dense media separation concentrates, X-ray transmission was found to incidentally detect small amounts of gangue particles. However, no such gangue detection occurred with X-ray luminescence, which responded only to diamonds. In pilot-scale tests, a belt-fed X-ray transmission sorter with a pressurized air ejection mechanism and a chute-fed X-ray luminescence sorter with a mechanical paddle ejection system were evaluated. The X-ray transmission sorter produced an average of 0.28 kg of concentrate per gram of diamonds separated, while the X-ray luminescence sorter generated 0.37 kg of concentrate per gram of diamonds separated. The X-ray transmission sorter achieved 99% diamond recovery, whereas the X-ray luminescence sorter achieved 91% diamond recovery. The higher concentrate mass obtained from the X-ray luminescence sorter is attributed to the ineffectiveness of the mechanical paddles, despite the superior contrast between gangue and diamonds in detection. Full article

In this work, a hydrometallurgical process for the recycling of diamond core drilling crowns by means of aqua regia leaching and subsequent alkali leaching was investigated. This investigation continues a previous study in which nitric acid was used for the acid leaching phase. In the current study, higher tungsten recovery was achieved, reaching 98.2%, which is an improvement of about 1.5%. Another advancement of this study was the high Co recovery (97.21%) and the high purity of the tungsten trioxide obtained, comparable to the previously proposed technological process. Furthermore, a novel laboratory method for testing recycled diamond drilling crowns based on infrared thermography was introduced. Although this innovative approach is not the most accurate, it is fast and cost-effective and provides valuable results before the actual field test is conducted as a final evaluation. In addition, the infrared thermography method offers the advantage of non-destructive testing, ensuring that the diamond drilling crowns can be assessed without compromising their structural integrity. Other instrumental methods used to characterize the products and intermediates were X-ray diffraction (XRD), scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS), and laser desorption ionization mass spectrometry (LDI-MS). The analytical method for the concentrations in all working solutions was ICP-AES. Full article

Airport terminals worldwide generate approximately 6 million tons of passenger waste annually. Increased awareness of climate change and global interventions for environmental sustainability requires a reassessment of airports’ current methods of waste management. This paper proposes a new design concept solution called circular airport retail waste management (CAWM) for airport terminal retail waste processing, which aims to reduce and ideally eliminate airport waste ending up in landfill or incineration. Given the need for novelty and challenging the status-quo, the double diamond design process was adopted as the research method. The research began by collating the current practices of retail waste processing in airports via a literature review and field observations. Secondly, a critical analysis of the current processes was conducted to identify the intervention points. Thirdly, a concept solution was developed based on the circular economy (CE) 9R framework. Finally, the CAWM concept was delivered to airport waste management personnel for review. CAWM offers a structured way of airport retail waste management practices, including the segregation of nonrecyclable and recyclable waste (i.e., different bin designs, color coding, harmonization of waste colors, improved instructions and signage, various bin locations, training, and installing more liquid disposal and donation stations). Airports can leverage CAWM for greater efficiency and cost-effectiveness regarding airport terminal waste processing, such that more waste can be diverted from incineration and landfill to recovery, which will subsequently help airports achieve net-zero targets. This research contributes to the extant CE literature, especially in the aviation industry context, where the academic discourse surrounding this subject and its peculiarities are limited. Full article

Separation of chalcopyrite from molybdenite is currently mainly carried out by flotation, but this process is costly because of the extensive use of inhibitors. This study briefly describes a 7.0T/100CGC low-temperature superconducting magnetic separator and discusses its separation principle as well as the effect of magnetic induction on chalcopyrite separation from molybdenite. A molybdenum (Mo) concentrate assaying 6.00% copper (Cu) and 19.01% Mo was magnetically sorted using a diamond-shaped steel rod medium mesh at a feed concentration of 20% and a pulp flow rate of 5 L/min from a Cu-Mo flotation concentrate with 88% of particles smaller than 23 μm using the separator. A Mo concentrate assaying 0.46% Cu and 16.28% Mo was finally obtained with a roughing (1.3 T)-cleaning (5 T) superconducting magnetic separation process. Similarly, the superconducting magnetic separator was performed to separate a Cu-Mo bulk flotation concentrate, and produced Cu concentrate assaying 19.64% Cu and 0.03% Mo from the bulk concentrate assaying 18.52% Cu and 0.39% Mo with a particle size of less than 0.074 mm. At a magnetic induction of 7 T, a pulp concentration of 20% and a feed velocity of 5 L/min, the grade and recovery of Cu in the magnetic product were 19.64% and 81.59%, respectively, whereas the grade and recovery of Mo in the non-magnetic product were 1.52% and 90.07%, respectively. Superconducting magnetic separation has potential applications for removing Cu from Mo concentrates, and separating Cu and Mo from Cu-Mo bulk flotation concentrates. Full article

The treatment of industrial polycrystalline diamond (PCD) blanks in aqua regia at atmospheric pressure between 333 K and 353 K was performed via the ultrasound-assisted leaching process to investigate whether the influence of ultrasound is beneficial. Cobalt content in the solution and in the blanks was monitored as well as the effects of leaching temperature, solid-to-liquid ratio, and PCD blank size. The use of intermittent and permanent ultrasound helped reduce the leaching time and thus energy consumption by up to 50%. In all trials with ultrasound, higher temperature only has a slight effect. Solid-to-liquid ratio does not have a positive or negative impact. A new process design was tested using an innovative experimental setup for ultrasound-assisted leaching aiming at maximum cobalt and diamond recovery from PCD and final reuse of fine PCD for cutting and polishing other hard materials in different important industrial applications. Full article