A process for separation of a feed gas comprising oxygen, nitrogen, and argon, the process comprising: compressing a feed gas via a compression system of a separation system having a first column and a second column, the first column being a high pressure column operating at a pressure that is higher than the second column, the second column being a low pressure column operating at a pressure that is lower than the first column; feeding the compressed feed gas to a first heat exchanger to cool the compressed feed gas; feeding at least a first portion of the compressed and cooled feed gas to the HP column to produce a first HP nitrogen-enriched vapor and a first HP oxygen-enriched stream; condensing at least a portion of the first HP nitrogen-enriched vapor via a first reboiler-condenser to form an HP condensate wherein a first portion of the HP condensate is recyclable to the HP column and a second portion of the HP condensate is feedable to the LP column; feeding the HP oxygen-enriched stream to the LP column; outputting a first nitrogen-rich vapor stream, a first nitrogen-enriched waste stream (156, 256), a first LP oxygen-rich liquid steam, and a first argon-enriched vapor stream from the LP column, the first LP oxygen-rich liquid having an oxygen content of at least 98 mol% oxygen; feeding the first argon-enriched vapor stream to an argon column to form a first argon-rich vapor stream that is feedable to a second reboiler-condenser and an argon-depleted liquid stream that is feedable to the LP column; at least partially condensing the first argon-rich vapor stream output from the argon column via the second reboiler-condenser; mixing the first nitrogen-enriched waste stream output from the LP column with the first LP oxygen-rich liquid stream output from the LP column for forming a mixed nitrogen-oxygen fluid stream (184, 284, 384) to feed to the second reboiler-condenser to provide at least a portion of a refrigeration duty of the second reboiler-condenser for the at least partially condensing of the first argon-rich vapor stream. compressing a feed gas via a compression system of a separation system having a first column and a second column, the first column being a high pressure column operating at a pressure that is higher than the second column, the second column being a low pressure column operating at a pressure that is lower than the first column; feeding the compressed feed gas to a first heat exchanger to cool the compressed feed gas; feeding at least a first portion of the compressed and cooled feed gas to the HP column to produce a first HP nitrogen-enriched vapor and a first HP oxygen-enriched stream; condensing at least a portion of the first HP nitrogen-enriched vapor via a first reboiler-condenser to form an HP condensate wherein a first portion of the HP condensate is recyclable to the HP column and a second portion of the HP condensate is feedable to the LP column; feeding the HP oxygen-enriched stream to the LP column; outputting a first nitrogen-rich vapor stream, a first nitrogen-enriched waste stream (156, 256), a first LP oxygen-rich liquid steam, and a first argon-enriched vapor stream from the LP column, the first LP oxygen-rich liquid having an oxygen content of at least 98 mol% oxygen; feeding the first argon-enriched vapor stream to an argon column to form a first argon-rich vapor stream that is feedable to a second reboiler-condenser and an argon-depleted liquid stream that is feedable to the LP column; at least partially condensing the first argon-rich vapor stream output from the argon column via the second reboiler-condenser; mixing the first nitrogen-enriched waste stream output from the LP column with the first LP oxygen-rich liquid stream output from the LP column for forming a mixed nitrogen-oxygen fluid stream (184, 284, 384) to feed to the second reboiler-condenser to provide at least a portion of a refrigeration duty of the second reboiler-condenser for the at least partially condensing of the first argon-rich vapor stream.