JYN Sim Baker, the woman who guided iron ore producer Midwest Corporation Ltd to its first export shipment later this month, has suddenly resigned as an executive director. Ms Baker, who had been with the company for about 18 months, also played a key role in the finalisation of a joint venture with steel giant Sinosteel Corporation over the Weld Range iron ore project in the Mid-West. While no formal explanation was forthcoming, WA Business News understands the reasons include commitments to her young family, a desire to seek another career path and the formalisation of the relationship between Midwest and Sinosteel. Midwest also announced the establishment of a joint venture board comprising representatives of Sinosteel and Midwest, responsible for the conduct of the joint venture, infrastructure requirements, exploration and government liaison.