The participation of power-intensive industrial chemical processes in short-term electricity markets (STMs) in addition to long-term markets (LTMs) is considered. STMs are highly volatile with dynamics of the order of seconds to minutes. It is thus imperative that production scheduling for chemical process participation in such markets (1) be carried out repeatedly to reflect ongoing changes in market conditions (2) account for process dynamics to guarantee feasibility, since frequent changes in production rate targets imply transient plant operation. To address these challenges, a novel production scheduling framework is formulated, consisting of a fixed-horizon scheduling problem for the LTM and a shrinking-horizon scheduling problem for response to STM changes. A case study illustrates that unused demand response (DR) potential from the LTM can be strategically deployed in STMs to improve grid operations and increase profit for the chemical process.