Life Cycles of Byproduct Critical Minerals

Science Center Objects

Project objectives are to 1) assess the overall life cycle of selected byproduct critical elements tellurium (Te), indium (In), gallium (Ga), and germanium (Ge), 2) perform an assessment of critical element resources and examine the processes and conditions controlling the concentration of byproduct critical elements by deposit type, and 3) improve understanding of the surficial geochemistry of these critical elements.

Science Issue and Relevance

Ensuring the supply of critical elements that are produced exclusively as the byproducts of other commodities present unique challenges. Unlike most mineral commodities, meeting the future societal demands for these "byproduct critical elements" cannot be addressed by the discovery of new deposits. Instead, the supply for critical elements, such as tellurium (Te), indium (In), gallium (Ga), and germanium (Ge), is dependent on the recovery of a different primary mineral commodity. Further, the United States is largely or completely reliant on imports for these elements, highlighting the importance of stable raw materials supplies for domestic high technology industries.

These elements play key roles in electronics and renewable energy, but the factors that contribute to their accumulation as accessory minerals in ore deposits are poorly understood. Moreover, the recovery of these byproduct commodities at mining, ore-processing, smelting, and refining facilities can be highly inefficient (reaching less than 5 percent of the amount in the ore). Additionally, these inefficiencies are not well constrained, because of uncertainties in how these elements partition in various product and waste streams at these operations. In addition, the processes that control their source, transport, and fate in the surficial environment are also poorly known.

Results from careful examination of critical element behavior during ore formation, extraction processes, and in surficial environments also will refine their life cycle models. This holistic approach to understanding byproduct critical element behavior is key for optimizing critical element resources and environmental health.

Methodology to Address the Issue

Our project will examine the resource life cycle of byproduct critical elements, focusing on Te, In, Ga, and Ge. Global life cycle assessments serve as an important tool in identifying partitioning during natural and anthropogenic processes and the relative importance of these processes, including releases to the surficial environment. The challenge of improving recovery of critical elements from existing metallurgical processes begins with uncertainties in the factors that lead to enrichment of these elements in ore deposits and continues with uncertainties in how these elements partition in ore and during ore-processing and refining. The process of extracting and utilizing critical elements for industrial or commercial uses may present new risks for environmental impact if these typically trace elements reach environmentally significant concentrations at one or more points along the process path. The environmental and human health risks of many of these elements are not well studied due to their low average crustal abundance. The project is divided into four tasks to better understand byproduct critical elements.

  • Life Cycles of Material Flow
  • Geologic Processes and Resource Assessment
  • Resource Recovery
  • Environmental Behavior

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