MODELLING OF PH CONTROL SYSTEM IN CLEANER CIRCUIT SULFIDE ORE FLOTATION PROCESS AT PT AMMAN MINERAL NUSA TENGGARA

• Main Author: Hidayat, Hilman
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/47154
• Institution: Institut Teknologi Bandung

PT Amman Mineral Nusa Tenggara (PT AMNT) is one of the mining companies in Indonesia that processes copper ore. There are several main minerals contained in the ore processed by PT AMNT, namely chalcopyrite (CuFeS2), bornite (Cu5FeS3) and pyrite (FeS2). At present, PT AMNT processes 120,000 tons of ore per day, all of which comes from ore that has long been stored in stockpiles. One of the main factors in the processing of sulfide minerals is the pH in the flotation process. The pH of the flotation process on PT AMNT's cleaner circuit tends to be unstable and often does not reach the set point pH value. A new pH control system on the sulfide ore flotation process cleaner circuit is needed to stabilize the pH value. The study was started with an analysis of plant operating data on the PT AMNT cleaner circuit. This analysis was carried out to determine the factors that affect the pH of the cleaner circuit. After that, determining the dominant determinant of pH at each point of the cleaner circuit. Then the results of the analysis of the dominant factor determining the pH were used as the basis for the step test response. Step response test was done by changing the lime valve opening in the PT AMNT cleaner circuit. The step test response was used to determine the gain, time delay and time constants respectively. The step test response results were then modeled using MATLAB with the closed loop system model. The results of analysis of plant operating data showed that the dominant factors affecting pH in column 1 and 2 areas were the percentage of acid mine water in process water, the ratio of free copper to oxidized copper and S / Cu. The dominant factor affecting pH in column 3 and 4 areas was the pH of columns 1 and 2. The dominant factor affecting pH in cleaner area 3 was the pH of the cleaner area 1. The results of data processing of lime valve opening in the cleaner circuit showed that the pH to control the cleaner circuit was sufficient by controlling the pH in the columns 1 and 2. Based on the results of the step test response showed a significant difference in the value of the gain constant when operating conditions using process water with a different composition. The operating conditions of the 100% sea water in process water had a gain constant of 1.776 x 10-4 and a condition of 70% of acid mine water had a gain constant of 4,719 x 10-4. Therefore modeling was done by adding input of process water conditions to the PT AMNT control system. Modeling with the new control system proved that pH becomes more stable and faster to reach the set point pH value.