Sintered iron ore used in steel production, just before being charged in a blast furnace. This sinter was produced by the Dwight-Lloyd process and screened. The A4 sheet of paper gives the scale.
<a href="//commons.wikimedia.org/wiki/User:Borvan53" title="User:Borvan53">Borvan53</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>