Adriatic Metals PLC (ASX:ADT, LON:ADT1) has produced a copper concentrate grading 25.1% copper and containing 9,550 g/t silver and 20.9 g/t gold in early results from Phase 2 metallurgical test work on ore from the company’s Rupice deposit in Bosnia & Herzegovina
The metallurgical work also produced saleable lead, zinc and barite concentrates from the latest multistage Locked Cycle Test (LCT1) carried out at the laboratories of Wardell Armstrong International (WAI) under the guidance of Adriatic’s metallurgical consultant.
Managing Director and CEO, Paul Cronin, said that Following the completion of the successful preliminary metallurgical test work in September 2019, Adriatic engaged WAI to initiate a second programme of metallurgical tests intended to 1) verify the sequential concentrate production following the successful separation of copper, and 2) confirm the metallurgical recoveries from feed with varying grade and metal assemblage.
WAI undertook a metallurgical investigation on a representative sample characterising the higher-grade zones of the Rupice deposit, which were assumed to be mined first in the recent Scoping Study completed in November 2019.
A detailed froth flotation study focussed on the production of separate copper, lead and zinc concentrates as well as a barite product. Variables investigated included primary grind size, reagent type, reagent dosage, pH profile and residence time.
“We are delighted with the early results of this second metallurgical test work programme,” Mr Cronin said.
“The quality of the copper concentrate produced will have a very positive effect on the aggregate revenues generated from concentrate sales if confirmed in the feasibility study, increasing potential copper, silver and gold payability significantly.
“Although this programme of test work has only just begun, and I am hopeful of further progress that can be incorporated into our feasibility work recently commenced by Ausenco.”
The test work confirms that it is possible to produce a copper concentrate containing significant quantities of payable gold and silver (20.9ppm Au and 9,550ppm Ag).
Mr Cronin said that as a result, based on advice from our concentrate marketing consultant, it is now expected that the copper concentrate will be in excess of 95% payable as compared to the previous assumption that the copper/lead concentrate would be only 30% payable.
Saleable lead and zinc concentrates were also produced containing significant levels of payable gold, silver and copper.
Mr Cronin said lead levels in the zinc concentrate were also noted to be low meaning that the zinc concentrate remains saleable. The zinc recovery in the zinc concentrate was slightly lower than attained with the average grade sample due to the higher zinc concentrate grade produced.
Mr Cronin said optimisation work is expected to improve that recovery to 80-85% as obtained in the previous average grade test work. Levels of some deleterious elements are generally lower than in the average grade concentrates produced in the previous test work and whilst these may still incur minor smelter penalties, these are not expected to be material. A number of deleterious elements, such as Antimony, are concentrating to a sufficient grade that in certain smelters they would either attract no penalty or be payable.