Gold in Process Determination
METS role included the calculation of gold present in the leaching heaps. We applied the material balance philosophy based on operational data including gold in feed, gold in residue and gold in process. This required a site visit to be conducted for observation of the process and for data gathering. Data gathered went back to the commencement of the project in June 1997 to the current data and included tonnages, ore grades and gold shipment and outturn results. Utilising the material balance philosophy the gold in process was calculated on a month by month basis from project commencement. The report was submitted to the project sponsors and since then METS has been invited back to the site on an annual basis to carry out the project audit and gold in process determination calculations.
This process has been ongoing now for a number of years and METS’ input has been used in the project annual audit undertaken by the independent auditors of the project.
Project Brief
Outcome
METS performed a Gold in Process determination for the Quartzite Heap Leach Project.
Background
Quartzite Ltd (part of the GeoProMining Group) Gold Mine, is situated in the Bolnisi region of Georgia. The mine site is located within the Madneuli Copper Mine, in the hills between Upper Bolnisi village and Kazreti. This is approximately 80 km South West of Tbilisi, the capital of Georgia. The company recovers gold and silver from stockpiles that are a gold bearing, secondary siliceous ore known as “quartzite”. The process incorporates heap leach technology at a throughput rate of around 3,000,000 tons per annum.
The main advantage of the mentioned method of extraction is its minimal negative influence on the environment during the full cycle of extraction.
Project Objectives
Quartzite Ltd’s auditors required precise determination of the gold present in the leaching heaps, at the end of December each year. This value is to represent the gold content of the heaps that is obtainable using the current operational process
Challenges
The process to reconcile the process flows is based on the well-accepted metallurgical balance method. This balance calculates the valuable metal retained in a process by subtracting the metal leaving the process, as tailings, residue or product, from that being fed into the process. It is determined by calculating the gold produced in the bullion, the gold remaining in the tailings and the gold remaining in the circuit. From this data the recovery can be determined. In a heap leach operation, such as the one Quartzite Ltd operates, this is not so straight forward as the tailings are not a defined stream and any Gold in Circuit (GIC) survey would be unrepresentative. The gold in the production heaps must therefore be determined by examining the data available from the operation. This involves reconciling the feed grade data and the gold production from the heap.
Our Approach
METS applied the material balance philosophy based on operational data including gold in feed, gold in residue and gold in process. This required a site visit to be conducted for observation of the process and for data gathering. Data gathered went back to the commencement of the project in June 1997 to the current data and included tonnages, ore grades, gold shipment and outturn results. Utilising the material balance philosophy, the gold in process was calculated on a month by month basis from project commencement. The report was submitted to the project sponsors.