Dr. Steve Chingwaru, a PhD graduate from Stellenbosch University, has made a groundbreaking discovery in the field of geometallurgy, potentially identifying the world’s largest unseen gold resource within Johannesburg’s mine dumps. Through his pioneering research, Chingwaru has shed light on the possibility of extracting gold valued at approximately R450 billion from the tailings of the Witwatersrand mines. These mine dumps, historically considered waste, hold over six billion tons of material with significant gold content, previously overlooked due to its low concentration and the technical challenges associated with its extraction.
Chingwaru’s journey into this untapped gold reserve began with his master’s research, which later evolved into a PhD study due to its groundbreaking findings. He meticulously calculated and characterized these hidden gold reserves, exploring innovative extraction methods that not only promise efficiency but also prioritize environmental sustainability. The concept of ‘invisible gold’, as Chingwaru explains, refers to extremely fine gold particles encapsulated within other minerals, making them difficult to detect and extract using conventional methods.
This discovery comes at a critical time when the depletion of high-grade gold deposits has pushed mining operations to extreme depths, some reaching as far as 4 kilometers underground. The shift towards reevaluating low-grade sources such as tailings for gold extraction has gained momentum, with Chingwaru’s research offering a beacon of hope for revitalizing these overlooked reserves.
While some major mining companies have begun reprocessing tailings to salvage residual gold, the common extraction methods, notably cyanide leaching, pose significant environmental risks and achieve a mere 30% gold recovery rate. Chingwaru’s research poses the critical question of the whereabouts of the remaining 70% of gold and explores safer, more effective means to access it.
A key focus of Chingwaru’s study is the environmental hazard posed by acid mine drainage (AMD), a byproduct of pyrite oxidation within the tailings. This process not only threatens groundwater quality in Johannesburg but also releases toxic elements, exacerbating pollution concerns. Chingwaru passionately advocates for the reprocessing of tailings dumps as a strategy to mitigate AMD by removing pyrite, the primary AMD catalyst, while simultaneously unlocking substantial economic value from these dormant gold reserves.
The implications of Chingwaru’s research extend beyond gold recovery. He highlights the potential for extracting valuable by-products such as copper, cobalt, and nickel during the reprocessing of pyrite. This approach not only promises to curb heavy metal pollution and AMD challenges associated with tailings but also opens new avenues for economic development and environmental preservation.
Dr. Chingwaru’s innovative work stands as a testament to the untapped potential lying within Johannesburg’s mine dumps, offering a sustainable path forward in the face of diminishing high-grade gold deposits. His research not only illuminates the vast economic opportunities inherent in these invisible gold reserves but also champions environmentally responsible mining practices, setting a new standard for the industry’s future.
Source: Mining Weekly
