KEY POINTS
• Jameson cells are saving Valterra about R203 million a year.
• The technology has reduced concentrate transport by 3,000 truckloads.
• Smelting power use and CO2 emissions have also fallen significantly.
Valterra Platinum is recording substantial operational gains from the use of Jameson flotation cells at its Mogalakwena PGM mine, with the technology generating about R203 million in annual cost savings. The savings do not include additional revenue that could arise from improved metal recovery.
Valterra Platinum executive head of processing operations Agit Singh said the technology had delivered significant benefits across the company’s processing chain, including lower concentrate volumes, reduced energy consumption and fewer truck movements.
The deployment has effectively removed the equivalent of 3,000 truckloads from the road, while cutting smelting electricity consumption by 70.5 MWh and reducing carbon dioxide emissions from smelting by about 70,000 tonnes.
The biggest gains have so far come from Mogalakwena’s north concentrator, where Valterra replaced about 44 conventional flotation cells with only four Jameson cells.
The results have encouraged the company to advance a study into introducing the same technology at Mogalakwena’s south concentrator.
Singh said the south concentrator could potentially achieve similar reductions in the amount of material moving through the processing and smelting system.
A major advantage of the technology is its ability to reduce concentrate mass without sacrificing grade or recovery. In some cases, Valterra has also seen indications of improved recovery.
That is particularly important at Mogalakwena, where Platreef ore contains significant amounts of clay and other unwanted material that can interfere with the recovery of PGMs.
The flotation process depends on PGM particles attaching themselves to bubbles before being lifted to the surface as concentrate. The challenge is ensuring that unwanted material does not attach to those bubbles at the same time.
Jameson cells improve bubble-particle contact and allow the process to use larger quantities of depressant to suppress unwanted material without significantly depressing the PGMs. The result is a cleaner concentrate with less gangue, reducing the volume of material that ultimately has to be smelted.
Valterra operates seven concentrators across its portfolio, processing ore from Mogalakwena, Amandelbult, Mototolo, Unki in Zimbabwe and the Modikwa joint venture.
Its downstream processing network includes the Polokwane and Waterval smelters, with Mortimer also expected to return to operation next year to process accumulated converter slag.
Polokwane’s 68 MW furnace is the company’s flagship PGM smelter and handles between 80% and 90% Mogalakwena concentrate.
Mogalakwena’s relatively high base-metal content is considered an advantage during smelting because the base metals help collect PGMs and improve their recovery into the desired metal stream.
Valterra says its smelting operations achieve efficiencies above 98% on the first pass and about 99% overall.
The company also uses its different ore sources to manage challenges such as chrome content. UG2 ore can contain significant chrome, which can complicate the smelting process. Valterra therefore blends material from operations such as Mogalakwena and Unki to dilute chrome levels before the concentrate enters the furnaces.
Converter technology separates PGMs and base metals
Valterra says another major advantage lies in its converter technology, which allows PGMs and base metals to be separated more efficiently downstream.
The company has 180 MW of smelting capacity, around 32,000 tonnes of base-metal or nickel capacity and PGM processing capacity of about 3.5 million ounces.
Unlike the conventional Peirce-Smith conversion route used elsewhere in the industry, Valterra cools the matte produced from its furnaces before crushing it and feeding it pneumatically into a top-submerged-lance converter.
After conversion, the material is slowly cooled over about seven days. During this process, PGMs associate with base metals, allowing the resulting material to be processed through a magnetic concentrator.
The approach enables Valterra to separate the PGM-bearing fraction from the nickel-copper matte before both streams reach the base-metal refinery.
Singh said this reduces the risk that constraints in base-metal refining capacity could restrict PGM production.
Mogalakwena accounts for about one million ounces of Valterra’s annual production of between 2.1 million and 2.3 million ounces. Although it contributes almost half of the company’s PGM production, its material accounts for nearly 80% of base-metal refinery capacity usage.
That makes downstream base-metal capacity an important consideration for future growth in Platreef processing.
Sulphur remains a major processing challenge
Valterra also sees sulphur management as an increasingly important issue as the industry processes more Platreef ore.
Platreef contains significant base-metal sulphides, meaning increased treatment could result in substantially higher sulphur dioxide emissions unless appropriate abatement systems are installed.
Valterra says investment in sulphur abatement has already reduced its SO2 emissions by 98%, from about 150,000 tonnes a day to between four and five tonnes a day, according to Singh.
The company said sustainability considerations remain an important part of decisions around its downstream processing assets.
Merensky ore can also contain significant sulphur, meaning additional abatement investment could become necessary if larger volumes are processed. In-house rebuild teams protect smelting reliability
Valterra has also developed its own specialist teams to rebuild and maintain its furnaces.
Singh said the company has taken direct responsibility for furnace rebuilds rather than relying entirely on external contractors.
The operation includes dedicated factories, warehouses and specialist teams capable of handling different types of furnace rebuilds.
The strategy is designed to reduce unplanned outages, furnace runouts and other disruptions that could affect processing continuity.
Valterra’s downstream assets include the 8.5 MW Unki facility, the 38 MW Mortimer operation and the Waterval complex, which includes two 34 MW furnaces and a 23 MW furnace.
The company said it continues to invest in these assets while focusing on sustainability, reliability and efficient energy consumption.
The company believes its extensive processing infrastructure gives it flexibility to handle different ore types while improving the value extracted from its PGM resources.
Its approach involves controlling concentrate quality before it reaches the smelters, optimising ore blends, maintaining furnace reliability and separating PGM and base-metal streams as early as possible in the downstream process.
Valterra also plans to unveil a broader chrome strategy in February as it continues to optimise its chrome-related operations.
Singh said the company wants to ensure its processing and smelting assets are used to generate maximum value rather than simply maintaining capacity for its own sake.
The strategy is expected to remain focused on improving efficiency, reducing unwanted material, controlling emissions and extracting greater value from the company’s integrated PGM processing chain.
