Evonik Industries AG
Gujarat Multi Gas Base Chemicals Pvt. Ltd.
Industrias Quimicas del Ebro, S.A. (IQE Group)
Madhu Silica Pvt. Ltd.
Oriental Silicas Corporation
PPG Industries, Inc.
PQ Corporation
Quechen Silicon Chemical Co., Ltd.
Solvay S.A.
Tosoh Silica Corporation
W.R. Grace & Co.