Jim Coleman
Chief Executive Officer (CEO)
Jim has a 20-year track record in corporate management of operations for large successful companies including Riversdale Mining, The Griffin Group, The Electricity Trust of South Australia, Utah Development Company, Rio Tinto and BHP. Jim also owned and managed a highly successful mining consulting business employing 40 people and managing operations concurrently throughout Australia and in five countries including Australian Government aid funded projects in SE Asia.
Jim brings 50 years experience in open cut and underground mining to Cokal, specialising in mine management, project development and operation using a variety of equipment including extensive application of in-pit crushing and conveying systems. His forte is in strategic mine planning to optimise economic returns, and he has the ability to integrate project development in many countries including Australia, Mozambique, Thailand, The Philippines, India and throughout SE Asia.

Masruri Yahya
General Manager Mines
Masruri Yahya joined Cokal from PT. Sriwijaya Bara Priharum where he was Operational and Technical Director. He has 31 years mining experience with 17 years high level management and 14 years’ experience in all aspects of mining including Mine Engineering, Mine Operations, Safety, Health and Environment (SHE) and Permitting. his distinguished and varied career includes Chief Operating Office for PT Darma Henwa Tbk, experience in USA and Indonesia with PT. BHP Coal Indonesia / PT Arutmin Indonesia, including the Senakin Mine, and as a Director at PT. Saka Technology Indonesia.
Mr. Masruri was Mine Manager / Kepala Teknik Tambang at PT. Arutmin Indonesia’s Asam – Asam mine in South Kalimantan where he became Regional Mine Manager and Head of Mine Engineering to complete all infrastructure facilities at the mine and port, he then progressed to Chief Operating Officer.


Luki Wilianto
Geology Manager
Luki Wilianto joined Cokal from PT. Thiess Contractors Indonesia. Luki has been working in the Indonesian Coal Mining industry for over 15 years and has significant experience in the field of Geology and Mining.  Having worked for PT Thiess Contractors Indonesia, PT Britmindo (Mining Consultant) and PT Wahana Baratama Mining (Bayan Resources Group).
During this time, he has either managed or contributed significantly to numerous due diligences, design and supervision of coal exploration programs, and mining studies related to the geological modelling, estimation, assessment, evaluation, mine planning and report accordance with JORC Code and KCMI for numerous Indonesian coal mining companies.
Mr. Luki graduated from UPN “Veteran” University of Yogyakarta, Indonesia, majoring in Geological Engineering, is a Member of the Australasian Institute of Mining and Metallurgy (MAusIMM) and an Indonesian Competent Person of “Ikatan Ahli Geologi” (CPI-IAGI).
Muhamad Arie Cahyono
Mine Planner Manager
Muhamad Arie Cahyono joined Cokal from PT. Thiess Contractor Indonesia. Arie has 15 years mining experience including coal geological modelling and mine planning. Having worked in PT Thiess Contractors Indonesia, PT Britmindo (Mining Consultant) and PT Bayan Resources Tbk where he was responsible to develop a life of mining plan among of company projects.
He worked in all aspects of the mining operation including validating geological models, developing pit and dump designs and dewatering strategies and ensuring mining contractors adhered to the company’s mine plans. He is an expert user of mining and geological modeling software used by Cokal and is competent to evaluate resources and reserves.
Mr. Arie is a member of PERHAPI and registered as Competent Person Indonesia (CPI).
Tee Kok Hui
Surveyor Manager
Tee Kok Hui joined Cokal from Island and Partners Sdn Bhd. Tee has 41 years’ experience in many aspects of the construction industry. For Cokal he is managing the survey teams preparing the data for road, port and mine design.