More than four decades later and primary smelting is still done with Outotec Flash Smelting Technology. This is complimented by two Delta electric furnaces for slag cleaning. The matte is converted through the use of three Peirce-Smith converters and one Converter Slag Cleaning Vessel (CSCV) for cobalt recovery enhancement. Norilsk Nickel relinquished its 6% shareholding making the government of Botswana the 100% shareholder of BCL.
The primary scope of the project Outotec was involved in focused on modernization of the nickel Flash Smelting Furnace (FSF). Contracting was structured in the form of two primary agreements.
- Part 1 included design, engineering as well as fabrication and supply
- Part 2 was established as a service level agreement for technical support during the installation, operation and maintenance period limited to 36 months.
The scope of Outotec's work included basic design, detail design of the new FSF, delivery of new advanced cooling elements with Outotec Sentinel Cooling Water Monitoring System and integrating them to the furnace. The delivery scope of refractory material and steel structures were shared between Outotec and BCL. The equipment was delivered to the BCL site in April 2015.
The service level agreement included a general audit on BCL operations and maintenance, expert supervision oversight during installation and commissioning, preventive maintenance planning, equipment maintenance support and spare parts availability plan. A key component of the service level agreement is access to an emergency support protocol that includes 24 hr call line and 48 hr on-site response.
Work at the site
The modernization was done as a full shutdown of the smelter from July 15 to November 12, 2015, and required the complete demolition of the FSF down to grillage beams. This included the settler, uptake and reaction shafts as well as all cooling water headers and circuits.
During this period BCL conducted maintenance, repairs and upgrades of several of the components upstream and downstream of the FSF. This included an additional new cooling tower system, major repairs to the boiler and heat exchangers, an air and steam drying plant and a rebuild of the primary slag cleaning furnace. A combined team of Outotec technical experts from Finland and South Africa took charge of the on-site installation, commissioning and start-up of the Outotec contractual supply components.
On-site continuity for the full duration of the shutdown was provided by the Project Coordinator Chris van Heerden. This enabled optimized coordination for liaison on logistics and resource movements.