OCI Resources has filed documents with the Securities & Exchange Commission for an initial public offering of stock worth $115 million. The company operates a trona mine and soda ash processing facility in Green River, Wyo. OCI Resources is an affiliate of the South Korean firm OCI. Last month OCI Partners, an unrelated firm that makes nitrogen fertilizers, filed for a $480 million public offering. Separately, Trinseo, the styrenic polymers maker also known as Styron, withdrew its $400 million public offering. The company, owned by the private equity firm Bain Capital, originally filed with the SEC two years ago.