Recovery Improvement at the West Block Screening Station of Nickel Mining through the Integration of Six Sigma and Sologic Method

Screening recovery, measured as the ratio of Screen Station Product (SSP) to the Run-of-Mine (ROM) ore fed, significantly declined by 16%, from 60% to 50%, during 2017–2021. This research addresses this decline by identifying root causes and proposing improvement steps using a combination of the Six Sigma method and the Sologic method. The Six Sigma method, which follows the DMAIC cycle (Define, Measure, Analyze, Improve, Control), was used to systematically identify and address process inefficiencies, while the Sologic method was employed for root cause analysis. Ten primary causes with high to moderate risk levels were identified and categorized into transitory, non-transitory, and omission types using the Sologic method. Three improvement steps involving substitution, engineering technology, and administrative control were implemented, focusing on transitory causes. Based on validated causes, improvement plans focused on recycling reject material, enhancing tramming activities, and refreshing dumping procedures through operator training to improve recovery and minimize carryover. Recycling reject material successfully increased the daily recycled material from 118 to 591 tonnes, while enhancing tramming activities raised trammed material from 10,396 to 11,473 tonnes/day. These improvements increased screening station recovery from 50% to 59% and raised the sigma value from 3.46 to 4.60. Continuous monitoring through the Floor Management Development System (FMDS) and gemba activities ensured the effectiveness and consistency of these changes.