GRES Named To Undertake Updated Studies For Brazilian Mine
Big River Gold Ltd (ASX: BRV) continues to make good progress in advancing the Borborema Gold Project (BGP) in Brazil.
Recent developments include the appointment of GR Engineering Services (GRES) based in Perth, Western Australia, to complete the revalidation of the Borborema DFS and generate an Engineering Cost Estimate update (ECE) for the 2Mtpa plant and equipment changes recommended in the recently completed Process Plant Option Study.
This will include updating the specifications and vendor pricing for the Process and Non process infrastructure. GRES is expected to complete the work by August.
This revalidated technical information and updated cost estimate will be used as the basis for project financing discussions in the third quarter 2021 prior to commencement of Front End and Detailed engineering and planning for construction. Overall, the accuracy of the ECE will be ±20-25% with key equipment at a higher level of accuracy.
The GRES scope includes:
- Update of process design criteria, mass and in-plant water balances.
- Update of the vendor equipment specifications including pricing updates to allow for future plant expansion duty for some major equipment to optimise the future expansion capital expenditure.
- Construction quantity re-estimates including update of construction rates.
- Development of the scope for the plant site geotechnical investigation to support the Front End Engineering Design (FEED).
- Engineering and cost updates for all non-process infrastructure.
- Development of the Project power supply to accommodate 2 Mtpa and possible future upgrades and expansion planning to optimise the future capital expenditure.
The work will be performed in Perth with assistance from GRES’s wholly owned subsidiary Hanlon Engineering, an Arizona-based multi-discipline engineering and project delivery company, who can provide site-based engineering support from the USA if travel from Australia is impractical.
It is envisaged that the ECE update will precede the FEED scope of works for the Project and commencement of the detailed engineering, procurement and construction management phases of the project which will be issued as separate request(s) for tender.
Another recent important development was the granting of the Declaration of Public Utility for the 69kv Power Line from Currais Novos to site. This makes our power line a public utility in terms of the benefits it provides to the community and therefore guarantees the Project’s access to land along its construction path and facilitates compensation negotiations with land owners.
The company has contracted an in-country consultant (GRID Energia) to oversee the design, procurement and installation of the 35 Kilometre 69kV transmission line from Currais Novos switchyard to the Borborema plant site.
Proposals have been received from three experienced contractors and the consultant is in the process of making a recommendation for the company to initially proceed with the design phase of the project which includes the survey of transmission line route. The design phase is expected to be completed in 4 months after award.
The current DFS plant design of 2Mtpa is underpinned by the sewage water offtake contract supplying 70m3/hr that was finalised with the Currais Novos Water Authority (CAERN). Big River is actively looking to secure additional supplies from several sources which is also addressed in the scope of work for the current study being undertaken by SRK (Brazil) on site-wide, water balance modelling.
In the meantime, access to the recently refurbished greywater collection system at the Caça e Pesca treated effluent pumping station in Currais Novos was obtained.
Initial flow rates have been surveyed and overall, have produced lower than expected volumes, albeit at an early stage. These measurements are considered unreliable and plans to clear blockages and enhance the channels and pipes into the pumping station collection points have been prepared. Action on this will commence on Monday 31 May and take at least two weeks to start seeing the impact.
The site water retention dyke is to be built to enhance the surface water collection on site. Prior to commencement of geotechnical drilling to confirm the dyke design, environmental survey and clearance work around the drill sites had to be undertaken by authorised personnel. This includes teams from the plant suppression (clearance) and animal relocation teams – namely FLORESTAL and INPLANTAR respectively.
Mine schedule
Additional studies assessing the implications of a possible expansion to a 4Mtpa mining rate are also being undertaken. In particular where such an expansion might influence pit design and accelerate the need to move the road or regional power transmission lines.
The sequencing presented for Stage 1 of the mining project will be reviewed based on the 2Mtpa throughput and will consider the implications of a possible ramp up in the second or third year to 4 Mtpa for the life of mine.
The 230kV regional transmission line located to the north of the current Stage 1 pit will need to be re- located to allow mine expansion to 4Mtpa and the timing is to be clarified. The company has contracted the in-country consultant GRID Energia to commence the necessary application with the power authorities to move the transmission line by about 10 km to be clear of the mine and infrastructure.
