Legal Question in Real Estate Law in California

As to your first question, you propose two possible answers, but they don't cover all the possibilities. I'd say neither of the choices given is correct. The right to reprocess tailings on government land may belong to the government, and not to the original mining company or to whomever comes along. Further, the right to reprocess tailings must be distinguished from a possible obligation to reclaim the mine site. The answer probably depends upon what law was in effect when the mining took place. There have been many changes since the mid-19th Century. I think your starting point has to be a sit-down discussion with the officials at the local Bureau of Land Management office or other federal agency with management duties over the site.