FLSmidth vacuum disc filters are playing a vital role in preparing tailings slurry for a backfill application at the new Kamoa-Kakula copper mine in the Democratic Republic of Congo (DRC). The Kamoa-Kakula Copper Project is a joint venture between Ivanhoe Mines (39.6%), Zijin Mining Group (39.6%), Crystal River Global Limited (0.8%) and the Government of the Democratic Republic of Congo (20%).
According to Maria-Paula Lucero, Sales and Account manager at FLSmidth, the company supplied four 3.8 m diameter disc filters, each comprising 14 vacuum discs. They are installed in two modules, with two units in each. This provides a cost effective dewatering strategy resulting in a cake dry enough to be mixed with cement and other additives before being conveyed underground to be placed in mined-out workings as backfill.
“The efficacy of the vacuum filter in this application allows the mine to consistently achieve its targeted level of dewatering,” says Howard Areington, General Manager Projects and Account Sales at FLSmidth. “This, in turn, means that the amount of cement and additives can be optimised, keeping operating costs down.” Areington highlights that vacuum disc filters are the preferred technology for tailings dewatering in backfill applications, being the most cost effective form of vacuum filtration per square metre of footprint.
A range of ancillary equipment was provided as part of the scope of supply, according to Lucero. This included the liquid-ring vacuum pump with capacity to pump almost 15,700 m3/h at a pressure of 67 kPa, as well as filtrate receiver and a filtrate pump of 32 m3/h capacity. FLSmidth also supplied a 1,060 gallon snap air receiver, a 750 kPa air compressor, a plant air receiver and an air drier. The water used in the filter vacuum pump needs to be potable so it was important for the design to recycle as much as possible. It is therefore recirculated through a closed circuit, with a cooling tower added to dispel heat from the water before it is re-introduced to the system.
“With disc filters delivering a drier product with more water savings, FLSmidth has provided this technology to many projects around the world,” says Areington. “With FLSmidth’s global reputation in the field for vacuum filtration backfill applications, we have secured a significant portion of this market – also supplying some of the largest vacuum disc filters in use today.”
A considerable portion of the disc filter installation was locally manufactured in South Africa, he notes. It was shipped in components to site, and installed by a third-party engineering company under FLSmidth supervision. Despite the challenges presented by the COVID-19 pandemic, the units were manufactured and delivered within a timeframe in line with the customer’s expectations.