Identifying technological trajectories in the mining sector using patent citation networks

This paper uses patent citation networks to study technological change in the mining industry between 1970 and 2015. The analysis is undertaken at both the aggregate level by jointly considering all mining-related technological fields, and at the micro-level of patents in nine sub-fields, representing specific technological "sub-trajectories". Consistent with previous literature focused on other technological domains, we find that innovation patterns in the mining sector are "technology bounded", i.e. largely shaped by patenting activities carried out in a very limited range of mining technological fields, even though we detect a shift from exploration to environmental mining technologies (emergence of a new technological paradigm). In addition, we examine two aspects of technical change that have been largely disregarded in extant research: the geographical patterns of inventive activities and the role of key applicants in such patterns. We show that core mining patents and leading inventors involved originate almost exclusively from the US, so that trajectories appear to be heavily "geographically bounded", revealing that developing resource-abundant countries lag behind the technological frontier in mining. Moreover, only a few applicant firms are responsible for most inventive activities reflecting a highly concentrated oligopolistic structure, hence characterising trajectories as "applicant bounded". Similar results are observed at the level of sub-trajectories, although with some relevant exceptions, hence suggesting that a substantial heterogeneity exists within the industry and across mining-related technologies.