Sulphur Emission Improvement at Nickel Processing Plant
Sulphur emission is a long time challenge for the company, the largest nickel mining and processing in Indonesia. Sulphur is added at the end of nickel ore reduction process in kiln. Excessive sulphur emission at the kiln discharge end area could occur when the Sulphur is not fully absorbed by the calcine (processed nickel ore) and the sulphur gas suction system not properly functioning. As part of the continuous improvement program implementation, which is helped by Relogica, the kiln area management decided to address the sulfur emission issue with continuous improvement approach.
Nickel production process consists of several steps. It starts from ore mining, ore drying; ore reduction (kiln); smelting process; and converting process. Sulphur is required for the chemical reaction in the smelting process to get nickel with 26% purity which is then delivered to converting process to get 78% purity. Sulphur emission happens when Sulphur not well mixed with calcine and gas suction system does not perform well. Sulphur gas discharge takes place during calcine transfer from kiln surge bin to calcine container. It is when the surge bin gate open.
The management then established cross-functional improvement team involving employees from several disciplines and functions to address the issue. The team focused on sulphur emission that occurred in Kiln 1 area. Following the improvement methodology where improvement project must have clear boundaries and manageable scope to be completed in a short period of time. The improvement project must be successful and deliver real benefit quickly; this can be achieved with proper project scoping. Problems are solved piece by piece. Problems that are outside the scope will be solved in the next improvement project. The improvement process must be performed systematically, using a structured team based approach. Relogica provided 9 Steps Improvement methodology based on PDCA principle (Plan-Do-Check-Action). The improvement teams were trained with the methodology before the improvement project commenced.
After doing data collection, observation, and interview involving people working in the area, team analyzed the problem to determine the root cause of why the sulfide gas pollution occurs when the calcine transferred to the container. The existing method for sulfur adding and mixing system, the gas absorption system and kiln operation parameter - which influence sulphur emission – were also reviewed and analyzed.
Finally, the team determined the solutions which were tested in the pilot activity. The solutions included improvement of the ducting & gas absorption system; Sulphur supply flow & mixing process; and calcine volume & temperature monitoring system inside kiln surge bin. The control room operator was involved to monitor sulphur parameter closely during kiln operation. Each implemented solution was followed by sulfide gas pollution level measurement to check its effectiveness.
At the end of the improvement project, sulphur emission can be reduced by approximately 49%. We believe this was achieved through the good teamwork, involving all stakeholders, combined with a systematic & effective problem-solving methodology.
An additional achievement that should be noted was the employee empowerment which was built during the improvement activities. We want to enforce employee to care for their workplace by finding and addressing any problems in their workplace in team approach. Problem solving and improvement activities must be performed continuously by the employees through teamwork.
The activities will become a continuous learning process for the employees. It has proven to be an effective process in building the capability and confidence of employees in undertaking problem solving and improvement activities. The most important point for the improvement program is that improvement is fun. Our experience shows that people always enjoy and have fun doing effective and successful improvement activities.
Management support is a must for continuous improvement activities. But don’t worry; the management would automatically be enthusiastic with continuous improvement activities once it successfully delivers real results, both tangible and intangible. Continuous improvement makes everybody happy.