https://www.theguardian.com/world/2022/aug/10/metal-making-recipes-ancient-chinese-text-kaogong-ji
Quote"The Kaogong ji may have been written by an administrator to assure the emperor that everything was under control. It is part of a manual for how to run the empire," said Prof Mark Pollard, from the University of Oxford.
Which is very confusing, since the
Kaogong ji was compiled c.300 BC, or earlier, when there was no "empire". So it seems in fact to provide an insight into Warring States metal production.
Original
Antiquity article here (https://www.cambridge.org/core/journals/antiquity/article/six-recipes-of-zhou-a-new-perspective-on-jin-and-xi/4201C4F138E4826C62545723726F90C3).