CLASSIFICATION CIRCUIT OPTIMIZATION OF PT AMMAN MINERAL NUSA TENGGARA WITH VARIOUS VORTEX FINDER DIAMETER, SPIGOT DIAMETER, AND FEED PRESSURE RATE

• Main Author: FILBERT (NIM : 12514011), JONATHAN
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/28302
• Institution: Institut Teknologi Bandung

PT Amman Mineral Nusa Tenggara (PT AMNT) is one of the mining companies in Indonesia that process copper. Until now, PT AMNT has a processing capacity of 120.000 tonnages of ore each day with processing stockpiled ore entirely. The stockpile ore has high value of WiBM (>14.5 WiBM). With that value, grind size is increased (at around 217 micron) and indirectly decrease throughput (~16%) while create a large number of grind size and throughput variations. Beside that, there are few problems that exist in grinding, classification, and flotation circuit due to processing stockpiled ore. In order to overcome the problem, PT AMNT has installed new dewatering screen on SAG Mill discharge.. In 2018, PT AMNT had installed dewatering screen on SAG Mill discharge. This equipment was installed to decrease screen aperture from 14-15 mm on trommel screen to 10-12 mm. Throughput and grind size are aimed to be in small variation after this installment with the oversize particle size target product. Classification circuit optimization is needed after the installment of dewatering screen. In this research, the effect of vortex finder diameter, spigot diameter, and feed pressure rate on overflow solid percentage and overflow particle size were examined. Research of the effect of vortex finder diameter and feed pressure rate on underflow solid percentage and hydrocyclone performance was also conducted. <br /> <br /> Several experiments have been conducted in this research. Sample was taken from the plant with various feed pressure rate (26-38 kPa) and vortex finder diameters (290 and 372 mm) in hydrocyclone cluster 3 at mill concentrator area 130. For spigot diameter variation, sample was taken at Anstat Box. Sample that was taken from the plant then wet weighted and dried with filter press and oven. After that, samples were dry weighted and the solid density were determined by calculating the ratio between slurry weight and dry weighted sample. Next, sieve analysis was conducted at size fraction of 12500-1180 &#956;m to achieve sizing data. If -1180 was weighted >500 gram, homogenization and splitting were conducted to gain a sample of 250 gram. The sample then was wet screened at size fraction of 38 &#956;m. The sample of +38 later would be dried and sieved at size fraction of 850-38 &#956;m to achieve sizing data at the smaller size fraction. The sizing data was balanced with JKSimMet. Mass balancing result then was plotted to Plitt curve and optimal condition achieved. <br /> <br /> Sample couldn’t be taken beyond 30 kPa when the vortex finder diameter was 372 mm due to roping so the feed pressure rate was changed to 22 kPa. Vortex finder diameter and feed pressure rate had effect on overflow particle size and hydrocyclone performance. Changing the vortex finder diameter to a smaller size would decrease P80 and d50. With the increasing of feed pressure, overflow product would be finer. Feed pressure rate and vortex finder diameter also had effect on overflow and underflow density. Higher pressure rate decreased overflow density and increased underflow density. Smaller vortex finder increased overflow density and increased underflow density due to ore hardness and throughput difference. Spigot diameter had effect on overflow particle size and density. Larger spigot diameter would produce lower overflow density and finer product. If the configuration of hydrocyclone of PT AMNT remained the same (vortex finder diameter 290 mm, spigot diameter 180 mm), the optimum feed pressure was 30-34 kPa. Although the most efficient partition occur at 38 kPa, feed pressure range of 30-34 kPa was suggested <br /> <br /> because it fulfilled the target of P80 and overflow density. To gain the optimum condition of classification circuit, vortex finder diameter should be in 230-285 mm. Spigot condition need to be evaluate regularly in diameter with range of 180-205 mm to achieve the overflow particle size and density needed.