Arizona-based TriStar Gold has initiated a study for optimisation of its process facility for its Brazilian Castelo de Sonhos gold project.

The company is embarking on the study after receiving permits for fauna capture and a transportation license.

TriStar has initiated metallurgical testing on Esperanca South, which is projected to produce 150,000 ounces per year in phase one of operations. TriStar will evaluate the impact of changing leach feed grind size on plant throughput, leach residence time, and recovery rates.

TriStar will also undertake engineering studies to optimise preliminary designs contained in the October prefeasibility study.

Previous test work on eight samples averaged a recovery of 98% using 105-micron grind size, with additional test work using 150 microns averaged 96% recovery across four samples. TriStar will now test grind size between 105 microns and up to 250 microns, and their impact on recovery.

Brazilian authorities have also expanded the Environmental Impact Assessment to include two adjacent concessions, TriStar said.

TriStar said it is committed to preserving the local population's rights to clean water and a clean environment for future generations, and plans to advance the UN's Sustainable Development Goals in the state of Para, which hosts the mine.