Search

The paper comprises new analytical data on the nature and occurrence of gold in solid pyrobitumen, closely associated with the main gold-bearing sulfide arsenic ores of the Bakyrchik gold deposit (Kazakhstan), related to post-collisional magmatic-hydrothermal origin. Gold mineralization of the deposit occurs mainly in the form of an “invisible” type of gold in the structures of arsenian pyrite and arsenopyrite, and the form of gold-organic compounds of pyrobitumen in carbonaceous-terrigenous sequences of Carboniferous formation. Microscopic and electron microscopic analysis, Raman and FT-Infrared analysis, mineralogical and three-step sequential extraction analysis (NH2OH·HCl, H2O2, HNO3 + HCl) has been carried out using 9 ore samples (from 3 different types of ores) for a comprehensive study of pyrobitumen and sulfide arsenic ores focusing mainly on organic matter. The sequentially extracted precious metal content of pyrobitumen reaches up to 7 ppm gold and other metals like Ag 4 ppm, Pt 31 ppb, and Pd 26 ppb, forming metal–organic compounds, while arsenic sulfide minerals incorporate 11 ppm gold, 39 ppm Ag, 0.49 ppm Pt. The enrichment of gold associating with organic matter and sulfide ore minerals was confirmed in this study. Organic matter was active in the migration of gold and the capture of gold by pyrobitumen. Moreover, the reductive organic matter agent released gold, most likely for the sulfide arsenic ore minerals. Pyrobitumen was a decisive factor in the concentration, transportation, and preservation of gold in the deposit.

The transition to a more circular economy is essential to develop a sustainable, low carbon, resource efficient, and competitive economy in the EU. In this context Critical Raw Materials (CRM) are defined as those which are of particularly great importance to the EU economy and at the same time there is a high risk of supply disruptions. First and foremost, improving the circular use of CRM is a key strategy in improving the security of supply and not surprisingly is an objective of various policy documents. This report delivers on action #39 of the Circular Economy Action Plan: "Sharing of best practice for the recovery of critical raw materials from mining waste and landfills". It builds on discussions held during two 2018 workshops and gathers together six examples of existing practices for the recovery of critical, precious, and other materials from extractive waste and landfills, highlighting technological innovation and contributions that have been made to a more comprehensive knowledge-base on raw materials. The report also provides various estimates of potential recovery of certain materials compared to their current demand. Lessons learnt from the practices include awareness that it is very unlikely that recovery processes can target one or just a few specific materials of great interest and disregard other elements or bulk matrixes. Especially in case of very low concentrations, most of the mineral resources and other bulk materials in which they are embedded must be valorised in order to increase economic viability and minimise waste disposal. As recovery processes can be very energy intensive, environmental and land use related aspects are also particularly relevant even though environmental gains may also occur and, moreover, land space can be liberated and reused for new purposes and services. Finally, availability of data and information on secondary materials as well as a harmonized legislative framework within the EU appear to be crucial for the large-scale deployment of recovery practices., JRC.D.3-Land Resources

This document provides the results of laboratory investigations on ore samples wich represent the study sites of the CHPM2030 project, completed with samples from other ore types. The results are evaluated with a relevancy to the CHPM technology. The methodology for rock stress and strength measurements is also described. These measurements will be carried out in the frame of WP2 and will complete the EGS relevant properties of different ore body types determined in the recent study.

This document provides the results of laboratory investigations on ore samples wich represent the study sites of the CHPM2030 project, completed with samples from other ore types. The results are evaluated with a relevancy to the CHPM technology. The methodology for rock stress and strength measurements is also described. These measurements will be carried out in the frame of WP2 and will complete the EGS relevant properties of different ore body types determined in the recent study., H2020