I own some SQM so I was quite keen to find more on this story. So far all I have is a Motley Fool article by Rich Smith
His bottom line.
....Now what
What does this mean for investors? Some of the changes to constitutional law being proposed include greater protections of private land and water rights for citizens (which could threaten investors in the mining sector, which makes up about 10% of Chile's economy). Changes to Chilean labor law have also been proposed, and if those increase the cost of labor, this could have far-reaching effects across the country.
All that being said (and despite today's drastic stock market reaction to the electoral news), change is not imminent. Once installed, representatives to the new body might spend as much as a year debating and amending Chile's constitution, after which the whole result will be subject to a nationwide vote. And if rejected, the new constitution will never take effect, with the current one remaining in place.
Personally, I have a lot bigger stake in Argentinian lithium producers who would likely benefit from problems at SQM. But, if the author is right it might be a good time to add to SQM. Will keep digging.