.png)
In the face of softening global prices for traditional minerals like lithium, Sinomine-owned Bikita Minerals has engineered a remarkable buffer against market volatility. The key to its resilience lies not in a new mine, but in a sophisticated, multi-stage metallurgical strategy focused on reprocessing historical waste dumps to extract a critical and high-value mineral: cesium.
By Rudairo Mapuranga
This innovative approach was detailed in a comprehensive technical presentation by Thomas Mupfumi, Senior Metallurgist at Bikita Minerals, during a recent Association of Mine Managers of Zimbabwe (AMMZ) visit. His explanation revealed a plant flowsheet of exceptional complexity and ingenuity, designed to economically liberate cesium from a previously discarded feedstock.
The story begins not with the new plant, but with the old. For decades, Bikita Minerals’ primary cash cow was petalite, a lithium-bearing mineral. The extraction process relied on Dense Media Separation (DMS), which leverages the differences in specific gravity (SG) between minerals.
“As our geologists indicated, our ore bodies were an assortment of minerals,” explained Mupfumi. “The key minerals of value are the spodumene [lithium], the petalite [lithium], and then there’s pollucite [cesium].”
In the DMS circuit, the target mineral, petalite, is a “light” fraction with a lower SG, reporting to the float product. The sink product—the heavier material—contained other valuable minerals like spodumene (SG ~2.7-3.2), lepidolite (lithium mica, SG ~2.8-3.0), and most importantly, pollucite (cesium, SG ~2.7-2.9). For years, this sink stream, deemed uneconomical to process further at the time, was stockpiled in vast dumps.
“Time immemorial, the major cash cow for Bikita Minerals is the petalite,” Mupfumi stated. “So you realise that we have got huge stockpiles of waste material that was left over after recovering petalite.”
This “waste” material became the foundation for a new business model. The new investors at Bikita (Sinomine) conducted extensive metallurgical feasibility studies on these dumps, recognizing their latent, marginal value. The challenge was metallurgical: how to separate and concentrate these minerals, particularly the low-grade pollucite, into a high-value, marketable product.
A Novel Three-Stage Concentration Circuit
The solution is a bespoke cesium flotation plant that Mupfumi described as “a novel processing setup… because there’s no other plant in the world which can recover very, very low grade pollucite and enrich it to the extent that this flotation plant is enriching.”
The feed for this novel circuit is not raw ore, but a pre-concentrated stream. The historical dump material is first retreated through the existing DMS plant. This “recycle” stage serves to marginally increase the content of pollucite and spodumene in the sink stream, creating a more suitable feed for the flotation circuit.
The heart of the operation is the flotation plant itself, a complex and sequential process designed to separate minerals based on their surface chemistry. Mupfumi detailed a three-stage recovery process:
Stage 1: Lepidolite (Mica) Recovery: The first stage is a bulk flotation process designed to recover micaceous minerals. “At the first stage of recovery, lepidolite is indicated on the flotation diagram,” Mupfumi noted. In this step, reagents are added to make the mica minerals hydrophobic (water-repelling). Air is bubbled through the pulp, and the hydrophobic mica particles attach to the bubbles and are skimmed off as a froth product. This step removes a significant portion of the lepidolite, simplifying the feed for subsequent stages. The tailings from this cell, now enriched in spodumene and pollucite, proceed to the next stage.
Stage 2: Spodumene Recovery: The circuit then switches to target spodumene. Through a different reagent scheme, the spodumene is made hydrophobic and is recovered in the froth phase. “Spodumene is now reporting in the froth phase,” Mupfumi said. This spodumene concentrate represents a second revenue stream, adding lithium production from the historical waste. Critically, the valuable pollucite remains in the tailings stream of this stage. “The tailings stream now, that’s where you’re going to imagine our increased enrichment of your pollucite.”
Stage 3: Pollucite (Cesium) Recovery: The final stage is the most technically fascinating, described by Mupfumi as “entirely a waste flotation process.” The tailings from the spodumene circuit, now highly enriched in pollucite, are fed to the cesium recovery circuit. Here, the goal is to remove the remaining gangue (waste) minerals to leave a pure pollucite concentrate.
· First, any remnant mica that escaped the first stage is scraped off.
· Second, dominant gangue minerals like feldspar and quartz are targeted and removed in the froth phase. “You are now targeting your feldspars, removing them as waste.”
· The final product, the premium pollucite concentrate, reports to the tailings stream of this flotation cell. “The product now is falling within the tailings stream of the flotation cell. That is where you are getting your cesium.”
Remarkable Metallurgical Performance: Turning 0.12% into Profit
The efficacy of this circuit is demonstrated by its stunning enrichment ratio. Mupfumi provided specific figures that highlight its world-class performance:
· Feed Grade: The material feeding the cesium plant averages a mere 0.12% Cesium Oxide (Cs₂O). This is an exceptionally low grade, making economic recovery seem improbable with conventional methods.
· Final Concentrate Grade: The novel flotation circuit upgrades this to a concentrate grading between 3% to 5% Cs₂O.
· Enrichment Ratio: This represents an enrichment ratio of approximately 25 to 40 times. “In terms of mineral processing, it’s a very high enrichment ratio,” Mupfumi emphasized.
This ability to economically process such a low-grade feed is the cornerstone of the operation’s profitability. Pollucite is the principal ore of cesium, a metal whose unique properties—it is the most electropositive and one of the least abundant stable elements—make it extremely valuable in specialized applications. These include:
· Oil and Gas Drilling Fluids: Cesium formate brines are used in high-pressure, high-temperature (HPHT) drilling operations due to their high density and environmental acceptability.
· Atomic Clocks: Cesium is the “pendulum” in atomic clocks, providing the definition of the second.
· Photoelectric Cells and IR Lamps: Used in night-vision devices and other optical applications.
· Medical and Research Applications: Used in radiation therapy and certain types of catalysis.
This niche demand and limited global supply ensure cesium commands a consistently high price, often orders of magnitude higher than lithium or tin, providing a robust shield against softer prices in other commodity markets.
A Strategic Vision for Inclusivity and Knowledge Transfer
The decision to host the AMMZ technical visit at Bikita Minerals and provide such a transparent technical briefing aligns with a broader strategic vision for the Zimbabwean mining sector, a vision passionately championed by industry leaders like Gift Mapakame, General Manager of Shamva Mine.
During the visit, Mapakame issued a powerful call for greater integration and knowledge exchange, specifically urging major Chinese-invested operations like Bikita to join the AMMZ. His words resonate deeply in the context of Bikita’s technical achievement.
“As an association, we have deliberately planned to interact and engage with the Chinese-invested operations that are in the country,” Mapakame stated. He identified a “major gap” in inclusivity, noting that while Chinese investment brings significant technology and skills, it often remains isolated from local institutions. “It’s coming with technology, it is coming with skills. All those things are just hanging out there and we are unable to actually harness those new establishments.”
Bikita Minerals’ presentation, in its technical depth and openness, can be seen as a direct response to this call. By showcasing their novel cesium flotation technology, they are not just explaining a process; they are demonstrating the very “proprietary knowledge” that Mapakame believes should be shared to elevate the entire national mining industry.
A Blueprint for Resilience
Bikita Minerals has provided a masterclass in modern mineral processing and strategic business planning. By applying advanced, proprietary metallurgical expertise to legacy waste streams, they have:
Unlocked a new, high-value revenue stream (cesium) that insulates them from volatility in lithium markets.
Maximized resource efficiency by extracting full value from historical operations, effectively making the mine’s waste a primary ore body.
Demonstrated world-class innovation in designing a flotation circuit capable of economic recovery from a feed grade most operations would consider barren.
Positioned Zimbabwe as a center of technical excellence for critical mineral processing.
The success of this circuit underscores a critical lesson for the global mining industry: profitability in the 21st century may depend less on discovering new giant ore deposits and more on innovatively and efficiently processing what has already been found. For Zimbabwe, the integration of this advanced technological knowledge into the broader fabric of its mining community, as advocated by leaders like Gift Mapakame, promises a more resilient, innovative, and prosperous future for the entire sector.
