Many people believe that gold processing technology in Tanzania remains stagnant and outdated. However, significant advancements have been made in the Artisanal and Small-Scale Gold Mining (ASGM) sector, particularly in regions like Geita, Shinyanga, Mara, and Chunya. These developments have improved gold recovery and positively impacted the livelihoods of miners and their communities.
Phase 1: Alluvial Washing and Mercury Amalgamation
In the years following independence and into the 1990s, Tanzanian miners primarily relied on alluvial washing. This method, which involved washing river sediments to extract gold, was inexpensive but labor-intensive and yielded low recovery rates.
To improve yields, miners began using mercury amalgamation in the 1990s and early 2000s. This process, where mercury binds with gold, provided better recovery rates but posed serious environmental and health risks. Despite these drawbacks, it remained popular due to its efficiency compared to alluvial washing.
Phase 2: VAT Leaching
A significant advancement occurred in the mid-2000s with the introduction of VAT leaching, a technique adopted from Zimbabwe. In VAT leaching, crushed ore is treated with a cyanide solution in large tanks to dissolve the gold. This method offered significantly higher recovery rates and became popular as more professionals entered the sector, drawn by rising gold prices and increased access to capital. This influx of investment facilitated the widespread adoption of VAT leaching, making it a more profitable and efficient method than previous techniques.
Phase 3: CIP and CIL Processes
Today, Tanzania’s most advanced gold recovery methods are the Carbon-in-Pulp (CIP) and Carbon-in-Leach (CIL) processes. These processes involve leaching gold in a cyanide solution and then using activated carbon to extract the gold. CIP and CIL have been particularly effective for low-grade, high-tonnage ores that were previously uneconomical to treat with the VAT leaching processes. These modern methods have increased recovery rates and reduced environmental impact compared to mercury amalgamation, significantly boosting profitability in the ASGM sector.
Future Challenges and Opportunities
Despite these advancements, the transition to modern methods has not been without challenges. Some miners who continue to use outdated techniques struggle to compete, and some have gone bankrupt. Adopting advanced processes like CIP and CIL requires significant capital and technical expertise. As the sector continues to evolve, ongoing research, investment, and optimization will be crucial to maintaining profitability and sustainability in the long term.
In conclusion, while Tanzanian gold processing technology has made considerable progress, continued investment and innovation are essential to realize the sector’s potential fully.
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