Root Cause Analysis on Process Monitoring in Ammonium Sulphate Fertilizer Production

Abstract

Ammonium sulphate, often known as ZA fertilizer, was extensively employed nitrogen (N) fertilizers for crop cultivation in Malaysia. While ZA fertilizer has been widely used for increased crop yields, concerns about its inconsistent performance despite application have risen. Hence, this study delves into the root causes of this issue. There are two phases in process monitoring which are Phase I implemented 30 subgroups while Phase II implemented 14 subgroups with 5 critical-to-quality, CO₂, NH₃, ratio of CO₂/NH₃, specific weight and temperature respectively. Before revealing the root cause, IGV and VV control charts were implemented to monitor the process variability in the production. Process monitoring analysis using IGV and VV charts revealed the VV chart's superior sensitivity in detecting variations, particularly for the eight samples exhibiting out-of-control signals which are 2nd sample, 5th sample, 6th sample, 10th sample, 11th samples, 12th sample, 13th sample and 14th sample respectively. Further investigation of Root Cause Analysis using TCV on the eight out-of-control signals, it was identified CO₂  followed by NH₃ as key contributors to these inconsistencies. Hence, CO₂ and NH₃ need to be focused and solid plans should be developed to address each root cause.