Niobium Material Flow Cycle

Figure 1 of "Embedded critical material flow: The case of niobium, the United States, and China". Prior to a stage-by-stage analysis, it is necessary to define each stage of the cycle including which material forms will be considered in each stage (Fig. 1). The primary stage in our study encompasses all wrought and unwrought niobium forms prior to fabrication processes, including raw material niobium such as mineral concentrates, and refined products such as niobium oxides (Nb₂O₅), ferroniobium, and other intermediate niobium forms. The fabrication stage includes all niobium-containing materials subjected to the processes in the “Fabrication” box in Fig. 1 prior to manufacturing, including all articles of steel. Lastly, the manufacturing stage includes all finished goods produced by the various niobium-consuming industries, including but not limited to automotive passenger vehicles and parts, tubing and piping, pressure vessels and parts, and other containers.