Bitcoin (BTC-USD) miner CleanSpark (NASDAQ:CLSK) on Wednesday has agreed to buy 10K more Bitmain Antminer S19j Pro mining rigs for $28.0M, after credits and discounts.The servers, which were purchased from hardware broker Cryptech Solutions, are expected to be delivered to CleanSpark's (CLSK) facilities by late October or early November, it said.The company bought the 10K units for approximately $28.00 per terahash, a steep discount when compared with $96/Th as quoted on Bitmain's website."During the tail end of the bull market last year, we strategically focused on building infrastructure instead of following the then industry trend of pre-ordering equipment months in advance” in a move that prompted rig purchases at "significantly lower prices," said CleanSpark CEO Zach Bradford.CleanSpark (CLSK) now has over 40K operational bitcoin (BTC-USD) mining machines with a daily production of 14.9 BTC and a hashrate of 3.8 exahashes per second.Previously, (Sep. 2) CleanSpark mined 395 BTC in August.