Johnson Matthey Technology Review - Volume 63, Issue 1, 2019

This study was a small part of the EURARE project concerned with the processing of eudialyte concentrates from Greenland and Norra Kärr, Sweden. Eudialyte is a potential rare earth elements (REE) primary resource due to its good solubility in acid, low radioactivity and relatively high REE content. The main challenge is avoiding the formation of silica gel, which is non-filterable when using acid to extract REE. Some methods have been studied to address this issue and, based on previous research, this paper examined a complete hydrometallurgical treatment of eudialyte concentrate to the production of REE carbonate as a preliminary product. Dry digestion with concentrated hydrochloric acid (10 M) and subsequent water leaching of the treated eudialyte concentrate resulted in high REE extraction while avoiding gel formation. Experiments were performed at a small scale to obtain the optimal parameters. After the first two stages, 88.8% REE was leached under the optimal conditions (HCl:concentrate ratio 1.25:1, digestion time 40 min, water:concentrate ratio 2:1, leaching temperature 20–25°C and leaching time 30 min). After obtaining the pregnant leach solution, preliminary removal of impurities by a precipitation method was examined as well. When adjusting the pH to ~4.0 using calcium carbonate, zirconium, aluminium and iron were removed at 99.1%, 90.0% and 53.1%, respectively, with a REE loss of 2.1%. Finally, a pilot plant test was performed to demonstrate the feasibility and recovery performance under optimal parameters. The material balance in the upscaling test was also calculated to offer some references for future industrial application. A REE carbonate containing 30.0% total REE was finally produced, with an overall REE recovery yield of 85.5%.

This event, hosted by the Royal Society of Chemistry, was held at Burlington House, London, UK, on 23rd November 2017. There was a good attendance with 55 delegates from academia and industry, mainly from the UK. A brief overview of some of the presentations is described here to give a flavour of recent progress in this area.

The first session was called ‘Control of Pickering Emulsions’. Professor Bernard P. Binks (University of Hull, UK) reviewed the fundamentals of solid-stabilised emulsions with the use of inorganic silica particles, whereas Professor Steven P. Armes (University of Sheffield, UK) extended the topic with the use of polymer particles.

The publication and implementation of the China VI emission standards for diesel fuelled heavy-duty vehicles is one of the important measures to fulfil the ‘blue sky defence’ action plan in China. This paper, by interpreting the background and key technical contents of the China VI emission standards, analyses the basis of the technical requirements and their impact. Moreover, it demonstrates the main differences between the China VI and China V emission standards and the Euro VI regulations, hoping to give the relevant industry in-depth insights into the new standard.

Phosphate-based glasses are promising materials for a range of applications including biomedical, veterinary and optical. These glasses are distinguished by the presence of at least one terminal oxygen atom, which gives phosphate-based glasses unique properties of which the most interesting is their easily controllable degradation profiles. This article describes the main structural features and applications of phosphate-based glass materials focusing primarily on biomedical applications. The processes utilised for developing varying geometries such as fibres, solid and porous microspheres and coatings are also explored.

In recent years, the application of high-nitrogen containing azine energy materials has been one of the hot spots in the field of energy materials in China and elsewhere. This paper reviews domestic and foreign studies into high-nitrogen azine energetic materials. The synthetic methods, structural and theoretical analysis, physical and chemical properties, sensitivity properties, thermal properties and detonation properties of some typical pyrazine energetic compounds are summarised, including: 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) of diazines, 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (TAAT) of triazines, 3,6-dihydrazino-1,2,4,5-tetrazine (DHT), 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine (BTATz) and 3,3′-azobis(6-amino-1,2,4,5-tetrazine) (DAAT) of tetrazine and their respective applications and potential value are described. The results of published studies reviewed here show that the application of azine energetic compounds in propellants can effectively improve the burning rate and reduce the characteristic signal; the application of azine energetic compounds in mixed explosives can reduce the sensitivity and improve the detonation performance; the application of azine energetic compounds in gas generators can reduce the combustion temperature and increase the gas content. Therefore, this class of compounds has a broad application prospect in energetic materials.